HK1109358A - Nonwoven composites and related products and methods - Google Patents

Description

Nonwoven composites and related products and methods

Technical Field

The present invention relates to substrates suitable for catalyzing particular reactions and for filtering particulate matter, and to embodiments related thereto, such as, but not limited to, treating emissions from internal combustion engines, and more particularly to catalyst/substrate combinations and related products and methods of manufacture suitable for use in emission control and related processes. It is believed that the embodiments of the invention described herein significantly improve the quality of the human living environment by helping to restore or maintain one or more essential life-sustaining natural elements, including air, water and/or soil. The present invention and its embodiments are described more fully hereinafter in the summary and detailed description.

Waste gas, industrial, and pollution

Engines produce much of the power and mechanical work used globally. The internal combustion engine is perhaps the most widely distributed device because it is more efficient than external combustion engines such as those found on older trains and ships. In an internal combustion engine, combustion of fuel is performed internally. Such engines produce motion and power for many purposes. Examples include motor vehicles, locomotives, ships, recreational vehicles, tractors, construction equipment, generators, power plants, manufacturing facilities, and industrial equipment. Fuels used to power internal combustion engines include, but are not limited to, gasoline, compressed gas, diesel, ethanol, and vegetable oils. The inefficiencies inherent in engine machinery and the fuels used to power them result in the emission of many pollutants. Thus, while they bring significant innovation and convenience, the millions of engines currently in use throughout the world represent a significant source of air pollution.

Internal combustion engines produce two main types of pollutants: particulate and non-particulate. Particulate contamination is typically small solid and liquid particles. Examples include carbonaceous soot, dust and other related particulates. Non-particulate pollutants include gases and small molecules such as carbon monoxide, nitrogen oxides, sulfur oxides, unburned hydrocarbons, and volatile organic compounds. Particulate contaminants may be filtered from the exhaust gas and, in some cases, may be further burned. Converting the non-particulate contaminants into non-contaminants. Non-engine sources such as "exhaust" chemical reactions and volatile emissions can also produce both types of pollutants.

Air pollution can cause serious health problems for humans and the environment. Ground ozone and airborne particulates are two types of pollutants that pose one of the greatest threats to human health in our country. Ozone (O)₃) Can stimulate respiratory system, and cause cough, throat pain and/or burning sensation in respiratory tract. Ozone is one of the causes of smoke formation. Ozone can also weaken the lung function, causing chestTightness, wheezing and feeling of shortness of breath, and can aggravate asthma. Particulate contamination consists of tiny solids or droplets that are small enough to penetrate deep into the lungs causing serious health problems. When exposed to these small particles, people can feel nose and throat irritation, lung injury and bronchitis, and can increase the risk of people's heart or lung disease. Short-term effects of air pollutants include irritation of the eyes, nose and throat. It can also lead to upper respiratory tract infections such as bronchitis and pneumonia. Other symptoms may include headache, nausea, and allergic reactions. Long term health effects may include chronic respiratory disease, lung cancer, heart disease, and even damage to the brain, nerves, liver, or kidneys. Continued exposure to air pollutants affects the lungs of growing children and may exacerbate or complicate the medical condition of the elderly.

Medical conditions caused by air pollution can be very expensive. The impact of healthcare costs, loss of productivity at the workplace, and human welfare cost billions of dollars each year. Understanding the health effects of pollution and finding a means to ameliorate, prevent or eliminate pollution will not only improve the overall respiratory health of the population, but will also reduce the material burden and cost of the health care system.

To this end, governments, environmental agencies, and various industries have been responsible for reducing the level of air pollution emitted from various sources. Government agencies are the subject of regulated emission standards and implemented regulations. In the European Union (EU), regulations stem from european community legislation; each member country enforces these regulations. For example, most EU countries impose taxes on sources that produce excessive air pollution. A new development is Kyoto Protocol (Kyoto Protocol), advising the reduction of greenhouse gases worldwide. Many countries, including the EU, have recognized this agreement. Some of the strictest standards around the world have been promulgated by the european union, japan and the united states, but regulations on air pollution have been promulgated by many other countries including argentina, brazil, mexico, korea, thailand, india, singapore and australia. In the united states, there are many different groups that affect regulations in certain regions, such as: state environment agencies such as the California Air Resources Board (CARB), national parks, forest agencies, and mine safety and health authorities. Some states and metropolitan areas that fail the National Ambient Air Quality Standard (NAAQS) are designated "off-spec areas" and implement their own standards. CARB has historically been one of the most stringent air pollution regulations in the united states. The leading U.S. regulatory agency is the Environmental Protection Agency (EPA). It was created by the Nixon government in 1970 with a revision in the air cleaning Act (CAA) of 1963. The clean air act is a comprehensive federal law that governs the emission of air from regional, stationary, and mobile pollution sources. (see, e.g., 42U.S. c.ss 7401 by air cleaning act, et al (1970)). The clean air act has undergone five major amendments, the last one being in 1990. The 1990 amendments to the air cleaning act were mostly aimed at dealing with problems not related or related to deficiencies such as acid rain, ground ozone, stratospheric ozone depletion and air poisons. These amendments require the EPA to issue 175 new regulations including vehicle emissions, gasoline reformulation, use of ozone depleting chemicals, and the like.

In compliance with air cleaning regulations, the EPA regulates pollutants that are or may be harmful to humans. The set of "target contaminants" includes: (1) ozone (O)₃) (ii) a (2) Lead (Pb); (3) nitrogen dioxide (NO)₂) (ii) a (4) Carbon monoxide (CO); (5) particulate Matter (PM); and (6) sulfur dioxide (SO)₂). Each index contaminant is described in turn.

Ground ozone (the major component of smoke) remains a pollution problem in the united states. Ozone is not directly emitted to the air, but Volatile Organic Compounds (VOCs) or reactive organic gases (logs) and nitrogen oxides (NOx) react to produce ozone in the presence of heat and sunlight. VOCs/ROGs are emitted from many sources including combustion fuels and from solvents, petroleum processing and pesticides from sources such as motor vehicles, chemical plants, refineries, manufacturing plants, consumers and commercial and other industrial sources. Motor vehicles, power plants, and other combustion sources emit nitrogen oxides. Ozone and ozone-generating precursor contaminants can also be carried by wind for miles from their source. In 1997, the EPA revised national environmental air quality standards for ozone, replacing the 1 hour ozone 0.12ppm standard with a new 8 hour 0.08 parts per million (ppm) standard.

Nitrogen dioxide (NO)₂) Is a reactive gas that can be generated by oxidizing Nitric Oxide (NO). Nitrogen oxides (NOx) (this term is used to describe NO, NO)₂And other nitrogen oxides) play a major role in the formation of ozone and smog. The major sources of artificial NOx emissions include high temperature combustion processes such as those occurring in automobiles, heavy construction equipment, and power plants. Household heaters and gas stoves also produce considerable amounts of NO₂。

Carbon monoxide (CO) is a colorless, odorless, toxic gas that can be generated by the incomplete combustion of carbon in fuel. In the united states, motor vehicle exhaust accounts for about 60% of CO emissions. In cities, up to 95% of CO emissions may come from automobile exhaust. Other sources of CO emissions include industrial processes, non-transportation fuel combustion, and natural sources of pollution such as phosphorus fires.

Particulate Matter (PM) is a term used to describe a mixture of solid particles and liquid droplets found in air. Some particles are large enough or black to be visible as soot or smoke. Other particles are very small and can only be detected by electron microscopy. These particles come from many different stationary and mobile sources of pollution as well as from natural sources of pollution, within a wide range of particle sizes ("fine" particles less than 2.5 μm in diameter and coarser particles greater than 2.5 μm). Fines (PM-2.5) are produced from the combustion of fuel from motor vehicles, power generation and industrial facilities, as well as from residential fireplaces and wood stoves. Coarse (PM-10) particles are typically released from sources such as road going vehicles, material handling equipment, crushing and grinding operations, and wind blown dust. Some particles are emitted directly from their sources such as chimneys and automobiles. In some cases, such as sulfur oxides, SO₂Gases of NOx and VOC interact with other compounds in the air to form fine particles. Their chemical and physical composition changes with location, season and climate. In 1997, the EPA added two new PM-2.5 standards, with annual and 24 hour standards being defined as 15 micrograms per cubic meter (. mu.GA) and 65. mu.g/m, respectively.

Sulfur dioxide can be generated when sulfur-containing fuels, such as coal and oil, are burned, for example, in metal melting and other industrial processes.

The last indicator contaminant, lead, has historically been the result of the use of leaded fuels in automobiles. The impact from the transportation sector has declined over the past decade due to regulatory efforts to reduce the Pb content of gasoline. Currently, metalworking is the primary source of Pb emissions to the atmosphere.

The air cleaning act requires the EPA and the states to set up a plan for national ambient air quality standards that meet these six target pollutants. These six are in addition to the 188 "toxic air pollutants" listed separately. Examples of toxic air pollutants include benzene, which is present in gasoline; perchloroethylene, discharged from some dry cleaning equipment; and methylene chloride, are used in many industries as solvents and paint strippers. Some airborne poisons are released from natural sources of pollution, but most originate from man-made sources, including mobile sources (e.g., cars, trucks, and buses) and stationary sources (e.g., factories, refineries, and power plants). CAA requires the EPA to plan for these 188 contaminants in two stages. The first stage consists of identifying the sources of toxic pollutants and developing technical standards that effectively reduce these sources. The EPA has identified a list of over 900 fixed sources of pollution that have led to new airborne toxicant emission standards that have impacted many industrial sources, including: chemical plants, oil refineries, aerospace manufacturing plants and steel plants, as well as smaller sources such as dry cleaners, commercial sterilizers, secondary lead smelters and electro-chromic equipment. The second phase consists of strategies and procedures to evaluate remaining hazards and ensure that the overall plan has achieved a substantial reduction in pollution; this phase is still in progress.

Internal combustion engines are directly affected by these regulations because they emit the target pollutants. These engines run on two fuels. The most commonly used fuels are gasoline and diesel. Each fuel contains a complex mixture of hydrocarbon compounds as well as trace amounts of many other substances including sulfur. Even when fully combusted, these fuels produce pollutants. In addition, some fuels are not fully oxidized due to the inability of the engine to "safely" burn, thus creating additional pollutants. Other types of fuels may also be used, such as ethanol blends, vegetable oils, and other fuels known in the art.

In gasoline engines, modern automotive engines carefully control the amount of fuel burned in order to reduce emissions. Efforts are made to maintain the air-fuel ratio very close to the stoichiometric point, which is the calculated ideal air-fuel ratio. In theory, all of the fuel would be combusted with all of the oxygen in the air at this ratio. The fuel mixture actually differs considerably from this ideal ratio during driving. Sometimes the mixture may be lean (e.g., air to fuel ratio higher than typical values of 14.7) and sometimes the mixture may be rich (e.g., air to fuel ratio lower than 14.7). These deviations produce a wide variety of air emissions.

The main emissions from gasoline automobile engines include: nitrogen (N)₂) (air 78% N)₂)；Carbon dioxide (CO)₂) Combustion products; and water vapor (H)₂O), another combustion product. Most of these emissions are not harmful to humans (but it is generally believed that atmospheric CO is present₂Excess is a factor contributing to global warming). But gasoline engines also produce carbon monoxide, nitrogen oxides and unburned hydrocarbons, all of which are contained in EPA's target pollutants (unburned hydrocarbons form part of the ozone formation mechanism along with NOx).

Diesel engines also produce index pollutants. These engines utilize a hydrocarbon fraction that auto-ignites upon sufficient compression in the presence of oxygen. Typically, diesel fuel is combusted in cylinders to produce larger quantities of particulate matter and oxides of the pollutants nitrogen and sulfur (NOx and SOx, respectively) than gasoline. Even so, diesel mixtures are generally dilute, with relatively abundant amounts of oxygen present. Thus, the combustion of shorter chain hydrocarbons is generally more complete, producing less carbon monoxide than gasoline. Longer chain hydrocarbons are more difficult to burn completely and can lead to particulate residues such as "soot".

Despite these drawbacks, fossil fuels are relatively abundant, easy to handle, and economical. Therefore, these fuels will still represent a major source of mechanical power and pollution in the coming years. Furthermore, the popularity of internal combustion engines explains why fossil fuels will still be a necessary energy source.

There are at least three markets for internal combustion engines that produce primary air pollution: 1) moving road engines, equipment and vehicles, 2) moving off-road engines, equipment and vehicles, and 3) stationary or "point" sources of pollution. In each of these markets, government agencies and other organizations have mandated limits on air pollution levels. These limits have become increasingly stringent as the number of internal combustion engines used has proliferated and the damage to air pollution has become more understood. Increasingly tightening regulations have required the industry to continually research, develop, and invest in new emission control technologies, from fuel formulations to new engine designs to aftertreatment devices. These technologies vary in effectiveness and cost, but have become essential to companies to comply with regulations. A single emission control technology has not been able to remove all of the relevant pollutants, so multiple technologies often must be used together to enable a particular type of vehicle or equipment to meet regulatory emission limits. These markets, their regulations and the technologies on which they rely are described in subsequent paragraphs. The techniques are described in more detail later in this section, including their advantages and disadvantages. While these sections focus on engines, equipment, and vehicles in the united states, similar products and regulations exist in other regions. For example, the EU has a similar market size, but as a diesel emission control technology, the EU focuses on selective catalytic reduction over exhaust gas recirculation, using catalytic converters in a larger proportion of small off-road engines, while in light vehicles the proportion of diesel engines is much larger. Other regions have their own unique differences from the united states, but use essentially the same type of equipment and limit the same type of air pollutants.

Movable road engines, equipment and vehicles include, but are not limited to, passenger cars, light trucks, minivans, Sport Utility Vehicles (SUVs), buses, vans, minivans, buses, and two or three wheeled motorcycles designed for use on the road. These markets have historically been typical in emission control and are currently continuing to do so in accordance with regulations that dictate lower standards for air pollutants.

The automobile and truck markets are divided by weight. Vehicles below the Gross Vehicle Weight (GVWR) of 8,500 pounds are considered light vehicles. Vehicles designed for passenger loading between 8,500lbs GVHR and 10,000lbs GVHR are considered medium-sized vehicles. Vehicles over 8,500lbs GVWR that are not designed for passenger use are heavy vehicles.

Passenger cars and light vehicles were previously managed by vehicle weight and fuel type, but future standards will manage them in one group. About 1700 million new passenger cars and light vehicles produced in the united states use diesel engines for less than 1%. Passenger and light vehicles include those manufactured by manufacturers such as Ford, General Motors (GM), DaimlerChrysler, BMW, Honda, Hyundai, Daewoo, First Automobile Group, Toyota, Nissan, SAIC-Chevy, and Subaru.

Regulations for passenger cars and light vehicles have existed for decades but have recently become much more stringent. The Tier 2 standard, which is adopted gradually from the Model Year (MY) 2004-. Vehicles below 6,000lbs GVWR must meet the standard completely by 2007, and vehicles of 6,000 and 8,500lbs and MDVs must meet the standard by 2009. Contaminants included in the Tier 2 standard include: NOx, formaldehyde (HCHO), CO, PM, and non-methane organic gases. California has historically been under more stringent regulations than EPA, and other states, including new jersey, new york, buddmont, , and the state of massachusetts, have joined california's lower emission standards for new and old vehicles. Manufacturers who do not comply with the standard basically forbid the production of their vehicles in these markets, finding penalties in the markets. In the aftermarket, states manage emissions from automobiles and light vehicles through inspection and maintenance (I/M) programs. These programs are often created by state execution plans (SIPs) required by National Ambient Air Quality (NAAQ) non-compliant areas. Emissions control techniques are employed, often in parallel, to meet new vehicle and accessory market standards.

Historically, three-way catalytic converters have been commonly used in automobiles and light-duty vehicles. Recent improvements to these converters (e.g., increasing substrate porosity, optimizing washcoats, reducing catalyst loading, etc.) have resulted in increasingly improved emission control. To comply with the latest edition of U.S. regulations, manufacturers will likely increase the catalyst loading or number of substrates per vehicle. A vehicle in service that does not meet inspection/maintenance standards must be replaced with a faulty technology or purchased with additional equipment. Other emission control devices include, but are not limited to, advanced injection systems (such as injection timing, injection pressure, rate profiling, common rail injection, and electronic control), modified combustion chamber designs (such as higher compression ratios, piston shapes, and nozzle positions), variable valve timing, catalytic converters, and filters.

Heavy vehicles (HDVs) include private and commercial trucks and buses above 8,500lbs GVHR. Most of these engines run on diesel fuel; over 300,000 are produced annually in the united states. Manufacturers and engine suppliers include, but are not limited to, Cummins, Caterpillar, Detroit Diesel, GM, Mack/Volvo, Intemational/Navistar, Sterling, Western Star, Kenworth, and Peterbilt. Other companies that offer other emissions Control technologies for the aftermarket include, but are not limited to, Donaldson, Engelhard, Johnson Matthey, Lubrizol, Fleetguard, Cleaire, Clean Air Partners, and Engine Control Systems.

Heavy trucks are facing stringent emission reduction standards for PM, NOx, CO, and non-methane hydrocarbons (NMHC). The PM standard was in effect in 2007, while the NOx and NMHC standards were adopted progressively from the 2007-2010 stage. Similar to light vehicles, california and certain other states and metropolitan areas often mandate stricter emissions standards than EPA. And (4) vehicles which do not meet the standard are forbidden to be sold by manufacturers. Efforts to size and improve not meeting NOx standards amount to up to $12,000 per car penalty. The HDV market faces the most stringent emission standards, although other industries such as locomotives, marine, agricultural and construction also use engines that are very similar to those in heavy vehicles. At the same time, some states and metropolitan areas (e.g., california, new york city, and seattle) require additional improvement or incentives to improve to further reduce pollution levels. These regions have identified technologies that meet approved levels and conditions. Examples include Donaldson's diesel oxidation catalyst muffler and diesel particulate filter, Cleaire's diesel oxidation catalyst and diesel particulate filter, and Johnson Matthey's continuous regeneration technology particulate filter.

Emission control technologies employed to meet these standards and improvements include, but are not limited to, advanced injection systems (injection timing, injection pressure, velocity patterns, common rail injection, and electronic control), exhaust gas recirculation, changes in combustion chamber design (higher compression ratios, piston shape, and nozzle position), advanced turbocharging, ACERT, diesel particulate filters, NOx adsorbers, selective catalytic reduction, conventional catalytic converters, catalytic exhaust mufflers, and diesel oxidation catalysts. Many of these emission control technologies have begun to be newly developed to meet 2007 standards. Significant costs and efforts have been paid to identify emission control solutions for 2007 HDVs.

Motorcycles are another type of mobile road vehicle, including two-wheeled and three-wheeled motorcycles designed for road use. Motorcycles mainly use gasoline fuel. Manufacturers include, but are not limited to: harley Davidson, BMW, Honda, Kawasaki, Triumph, Tianjin Gangtian, Lifan Motorcycle, and Yamaha. The regulations for road motorcycles were adopted in 1978 and were not revised until 2003, while california passed new standards after the regulations in 2003. Pollutants monitored in the new standards include HC, NOx, and CO.

Emissions control technologies for motorcycles include, but are not limited to, 2-stroke engines to 4-stroke, advanced injection systems (injection timing, injection pressure, velocity pattern, common rail injection, and electronic control), pulse air systems, modified combustion chamber design (higher compression ratio, piston shape, and nozzle location), and the use of catalytic converters. The limitations of motorcycle emission control technology are different from those of light or heavy vehicles. Motorcycles focus more on the look, placement, and heat of the aftertreatment device because there is less room to "hide" the device and the occupants are much closer to the exothermic oxidation reaction.

The category of mobile road engines, equipment and vehicles includes, but is not limited to, engines for agriculture, construction, mining, horticulture, private ships, watercraft, commercial ships, locomotives, aircraft, snowmobiles, off-road motorcycles and ATVs.

Small engines emit a considerable amount of air pollution for their size; they are the largest independent emissions sources of the total amount of non-road HC; small engine equipment includes, but is not limited to, leaf blowers, trimmers, brush cutters, chain saws, lawn mowers, riding mowers, log splitters, snow blowers, and chippers. Engine and equipment manufacturers include, but are not limited to, John Deere, Komatsu, Honda, Ryobi, Electrolux (Husqvarna and Poulan, also available as Craftsman), Fuji, Tecumseh, Stihl, American YardProducts, and Briggs and Stratton.

The EPA started in 1993 (phase I) to manage small engines with the standards in effect in 1997 and continued to reduce emission levels in 2002 (phase II) with new standards. These standards classify devices into handheld and non-handheld categories, based on differences in engine displacement. These regulations primarily control hydrocarbon and nitrogen oxide emissions.

Emissions control technologies include, but are not limited to, utilizing catalysts (i.e., LE technology by John Deere and layered scavenging design by Komatsu), 2-stroke engine conversion to 4-stroke, advanced injection systems (injection timing, injection pressure, velocity pattern, common rail injection and electronic control) or changing combustion chamber design (higher compression ratio, piston shape and nozzle position).

Recreational vehicle markets include off-road motorcycles, snowmobiles, and all-terrain vehicles (ATVs). They are manufactured by manufacturers and engine suppliers such as Honda, John Deere, Kawasaki, Mitsubishi Motors, Nissan, Toyota, Yanmar, Arctic Cat, Bombardier, Brunswick, International Powercraft, Polaris, Suzuki and Yamaha.

The EPA began to manage recreational vehicles later than many other markets, but california was already managing it at an early stage. EPA manages snowmobiles from the 2006 + 2009 annual stage and from the 2006 + 2007 annual stage off-road motorcycles and ATVs. The pollutants controlled include HC, CO, and NOx. Emission control technologies for recreational vehicles include, but are not limited to, 2-stroke engines to 4-stroke, advanced injection systems (injection timing, injection pressure, velocity patterns, common rail injection, and electronic control), pulsing air, or changing combustion chamber designs (higher compression ratios, piston shapes, and nozzle locations).

In the mining industry, regulations are set by mine safety and health authorities. Mining is often considered the most environmentally hazardous due to the high degree of vibration, impact and dust. Temperature and flammability are also of concern in the mining industry. Diesel oxidation catalysts have been improved on some mining equipment, while diesel particulate filters are becoming increasingly popular.

In the agricultural and construction markets, the EPA manages spark ignition and compression ignition engines. These engines may be used in tractors, forklifts, dozers, generators, pavers, rollers, trenchers, drills, blenders, cranes, balers, compressors, and the like. Engine and equipment manufacturers include, but are not limited to: agco, Komatsu, CNH Global, Caterpillar, Cummins, Daewoo, John Deere & Co, Dueutz, Detroit Diesel, and Kubota.

The EPA started to manage the diesel portion of these engines in 1994 (Tier 1), and recently advanced the standard with Tier 2 (adopted progressively from 2001-2006). The standard was again raised at Tier 3 level since 2006 + 2008. The Tier 3 standard may require the use of emission control devices similar to those used on heavy vehicles, such as tractor-trailers. Regulations for gasoline, liquefied propane gas, or Compressed Natural Gas (CNG) engines used in agricultural and construction applications have also recently changed. The Tier 1 standard, starting in 2004, matched the standard used by CARB before; the Tier 2 standard is expected to start to execute in 2007. There is a voluntary planning of vehicles with lower emissions than the standard, named "blue sky series". Depending on the engine size and fuel type, the particulate matter, carbon monoxide, nitrogen oxides and non-methane hydrocarbons must be significantly reduced in order to meet the current and soon to be adopted standards.

Emissions control technologies are similar to those employed on heavy-duty vehicles, including but not limited to advanced injection systems (injection timing, injection pressure, velocity patterns, common rail injection, and electronic control), exhaust gas recirculation, changing combustion chamber design (higher compression ratio, piston shape, and nozzle position), advanced turbocharging, ACERT, diesel particulate filter, NOx adsorber, selective catalytic reduction, conventional catalytic converter, catalytic exhaust muffler, and diesel oxidation catalyst. Exhaust Gas Recirculation (EGR) is problematic because it tends to produce sulfuric acid at the engine inlet. EGR also requires cooling and necessitates a larger radiator, which results in larger front ends, resulting in aerodynamic and fuel economy limitations.

In marine applications, engines may be generally divided according to whether gasoline or diesel fuel is used, whether for private or commercial use, or according to engine size. Marine installations include private ships, yachts, ferries, tugboats and seagoing vessels. Manufacturers and engine suppliers include, but are not limited to: bombardier (Evinrude, Johnson, Ski Doo, Rotax, etc.), Caterpillar, Cummins, DetroitDiesel, GM, Isuzu, Yanmar, Alaska Diesel, Daytona Marine, MarinePower, Atlantic Marine, Bender Shipbuilg, Bolliger Shipyards, VT Hall Marine, Eastern Shipbuilg, Gladding-Hearn, Jeffoat, Main Iron Works, Master Bowpat, Patti Shipyard, Quality shiards, and Verret Shipyard, MAN & W Diesel, Wattsila, Mitsushi, Bath IronWorks, Northic Grumat, and neutron Growards including Avonn and Newcastle.

The EPA manages ships, whether they are recreational, private or commercial. From recreational vehicles to tankers, classification is based primarily on engine displacement. Diesel non-recreational boats below 30 liter (30L) displacement including fishing, tug, dredge and cargo ships, there are new standards for NOx and PM in force between 2004 and 2007, depending on engine size. Diesel non-recreational ships exceeding 30L include container ships, tankers, bulk carriers, and cruise ships, with NOx standards (Tier 1) in force in 2004 and additional HC, PM, and CO standards (Tier 2) in force in 2007. Diesel recreational vessels include yachts, cruisers and other types of recreational vessels whose standards match those of diesel non-recreational vessels below 30L displacement, but which are executed later, depending on engine size and starting in 2006 + 2009. Gasoline and diesel boats have only recently had limitations on HC emissions from outboard engines, personal watercraft and jet boats. Stern drives and inboard engines are inherently cleaner and not limited.

Emissions control technologies are similar to those used on heavy-duty vehicles, including but not limited to the use of "green-end" when the ship is at dock, 2-stroke to 4-stroke engines, secondary water cooling, exhaust gas recirculation, diesel particulate filters, selective catalytic reduction, diesel oxidation catalysts, catalytic converters, advanced fuel injection (injection timing, injection pressure, velocity patterns, common rail injection, and electronic control), advanced turbocharging, variable valve timing, and changing combustion chamber design (higher compression ratio, piston shape, and nozzle location). Providing auxiliary power with a smaller engine (e.g., auxiliary power unit APU) also helps control emissions. Although brine and its accompanying contaminants and cooling of the ship cause difficulties in the after-treatment, the APU can work well with the after-treatment device.

The locomotive market relies primarily on diesel fuel (coal-fired and wood-limited use), including trains for freight and passenger railroads, long haul transportation, common car and turnout service. Over 600 trains are produced annually in the united states. Manufacturers and engine suppliers include, but are not limited to, GM's electrokinetic Division, GE transfer Systems, Caterpillar, DetroitDiesel, Cummins, MotovePower, Peria locomative Works, Reublic locomative, Trinity, Greenbrier, and CSX.

The train management began in 2000, largely mimicking the regulations of heavy vehicles. Standards include emission standards for newly produced engines as well as for engines that are retrofitted (about once in 4-8 years), depending on whether the engine is used for turnouts or long haul transport. Tier 0 was used in Engine Model Year (MY) from 1973-2001, Tier 1 was used in MY2002-2004, and Tier 2 was used in MY2005 and beyond. The penalty for non-compliance is no more than $25,000 per day per engine at the most. The pollutants controlled include particulate matter, NOx, HC, CO, and smoke opacity (smokeopacity).

Emissions control technologies are similar to those employed on heavy-duty vehicles, including but not limited to advanced injection systems (injection timing, injection pressure, velocity patterns, common rail injection, and electronic control), exhaust gas recirculation, changing combustion chamber design (higher compression ratio, piston shape, and nozzle location), selective catalytic reduction, diesel oxidation catalysts, aftercoolers, split cooling (split cooling), zeolite molecular sieves, and NOx reduction catalysts. The use of smaller auxiliary power units also becomes an emission control strategy, which is less restrictive on the use of aftertreatment devices.

The aircraft market includes all types of aircraft, including aircraft manufactured by Boeing, Airbus, Cessna, Gulfstream, and Lockheed Martin, among others. Both the EPA and the european union comply with the International Civil Aviation Organization (ICAO) emission standards. The EPA adopted the current standards for ICAO for CO and Nox in gas turbine engines in 1997 and its HC standard in 1984. In the united states, the FAA monitors and enforces these standards. Many emissions controls are accomplished by engine technology and fuel changes.

Stationary sources of contamination include those that cannot be moved. The EPA has imposed regulations that include more than 80 major industrial sources, including power plants, chemical plants, oil refineries, aerospace manufacturing plants and steel plants, as well as smaller sources such as dry cleaning, commercial disinfectors, secondary lead smelters and chrome plating equipment. Power plants can employ stationary diesel engines, stationary gas turbines, and nuclear power and other pollution sources. Each of these sources of contamination produces different contaminants; for example, nuclear power plants produce iodine and hydrogen, gas turbines produce NOx, CO, SOx, CH₄And VOCs, refinery produced steam, CO, NOx, VOCs, CO₂、CH₄And PM. Various industries require different control techniques to reduce airborne pollutant emissions.

EPA regulations contain six index pollutants and an additional 188 toxic air pollutants. The implementation plan includes an Acid Rain Program intended to reduce sulfur emissions and an Ozone Transport Commission's NOx bucket Program intended to reduce NOx emissions. RECLAIM is a plan formulated for trading NOx and SOx credits. In addition, quota trading programs (cap and trade programs) have been implemented in some industries and regions, allowing companies to trade their emission credits.

The technologies employed to control emissions from stationary sources vary widely, but examples include filters, scrubbers, adsorbers, Selective Catalytic Reduction (SCR), precipitators, zero loss catalysts, turbo catalysts, or oxidation catalysts. Some suppliers of fixed pollution source market emission control systems include: m + W Zander, Crystall, Jacobs E., Takasogo, IDC, ADP, Marshall, Bechtel, Megte, Angui, Adwest, Eisenmann, Catalytic products, LTG, Durr, Siemens, and Alston. The catalyst suppliers included: nikki, BASF, Cormetech, w.r.grace, Johnson Matthey, UOP, and Sud Chemie.

Due to the importance of improving air quality and complying with relevant laws and regulations, significant time, money, and effort has been invested in technologies that can reduce emissions. The three technical fields include: a) engine modifications, b) fuel modifications and c) aftertreatment. These approaches are typically solutions that are not mutually exclusive or independent. Engine improvements include, but are not limited to, technologies such as advanced injection systems, exhaust gas recirculation, electronic sensors and fuel control, combustion chamber design, advanced turbocharging, and variable valve timing. Fuel improvements include, but are not limited to, formulations such as high cetane number, low aromatics, low sulfur fuels, fuel borne catalysts (fuel borne catalysts), Liquefied Petroleum Gas (LPG), oxidation of fuels, Compressed Natural Gas (CNG), and biodiesel. Post-processing techniques include, but are not limited to: catalytic converters (2, 3 and 4-way), particulate traps, selective catalytic reduction, NOx adsorbers, HC adsorbers, and NOx reduction catalysts, among others. Some systems combine blocks of these and other technologies; the acetert or catalyzed diesel particulate trap of Caterpillar is an example of a combined system and apparatus. There are also some technologies that are currently in use, either technically or commercially limited.

Advanced injection systems include injection timing, injection pressure, velocity patterns, air-assisted fuel injection, continuous multi-point injection, common rail injection, adjusting orifice size or moving orifices and some electronically controlled changes. In common rail systems, a computerized fuel pump controls the flow and timing of the fuel (such as the Mercedes-Benz E320 system employed). The secondary injection may promote combustion of HC and CO in the manifold. The change of the injection system can reduce various emissions and improve the fuel economy; but this requires a lot of work on the engine to ensure efficiency.

Exhaust Gas Recirculation (EGR) directs some of the exhaust gas back to the engine inlet. By mixing the exhaust gases with fresh intake air, the amount of oxygen entering the engine is reduced, resulting in reduced nitrogen oxide emissions. EGR does not require regular maintenance and works well in combination with high swirl, high turbulence combustion chambers. EGR also has drawbacks such as reduced fuel efficiency and engine life, increased demand for vehicle cooling systems, limited effectiveness against pollutants other than NOx, and the need for control algorithms and sensors. For this reason, EGR is often used in parallel with additional control techniques. Companies involving EGR technology include Doubletree Technologies, ETC, STT Emtec, Cummins, Detroit Diesel, Mack, and Volvo.

Optimizing or incrementally improving combustors is another way manufacturers and developers control emissions. Reducing crevice volume may limit the trapping of unburned fuel (and thus limit HC production), while reducing the amount of lubricating oil may also reduce HC production and may limit catalyst poisoning. Other measures include: improved surface finish of cylinders and pistons, improved piston ring design and materials, and improved exhaust valve stem sealing. "fast-burning" combustors can also be made by: increasing combustion rate, reducing pre-ignition, adding diluents to the air-fuel mixture, and/or increasing turbulence within the chamber. While optimizing the combustion chamber can result in reduced emissions, it is another technique that requires modification of the engine, which can be an expensive process.

Variable valve timing involves calibrating the engine valves to open and close to maximize fuel and engine efficiency. Sensors are typically used to sense engine speed and adjust the opening and closing of the valves accordingly. This technique can increase engine torque and power, and can improve swirl and intake velocity, thereby improving combustion efficiency. Variable valve technology reduces emissions less than some other technologies, often resulting in reduced fuel efficiency.

Reformulating or using different fuels is another emission control technique because some fuels are naturally more polluting than others, and some fuels tend to poison the catalyst that purifies the exhaust gas. For example, the transition from leaded to lead-free fuels in the united states results in a significant reduction in lead emissions. Reducing the sulfur content of the fuel reduces SOx emissions and increases the efficiency of many catalytic converters because sulfur can poison the catalyst. Another type of fuel, natural gas, typically produces less particulate contamination than diesel fuel and may also reduce NOx and combustion noise. In contrast, natural gas can also increase vehicle weight (due to the need for high pressure tanks) and present refueling limitations.

The use of after-treatment devices (equipment used after combustion of fuel) is extremely common in certain industries affected by emission control regulations. One example of an aftertreatment device is a catalytic converter. Catalytic converters can vary widely and can have different functions, but generally refer to devices that treat exhaust gases with catalysts. Over the years, the composition of the substrate and the catalyst thereon has changed, as have the arrangement and number of converters.

Two-way catalytic converters for gas phase pollutant oxidation, e.g. oxidation of HC and CO to H₂O and CO₂. Diesel Oxidation Catalysts (DOCs) are another type of two-way catalytic converter used with diesel engines. While these converters effectively control HC and CO and require little maintenance, they can increase NOx emissions and are sensitive to sulfur.

Three-way catalytic converter for oxidation (conversion of CO and HC to CO)₂And H₂O) and reduction (conversion of NOx to N₂Gas) reaction. Three-way catalytic converters have been reducing vehicle emissions since the seventies of the twentieth century. Further improvements in performance with these devices are limited by a number of factors such as temperature range and surface area of the device substrate and catalyst poisoning. To comply with increasingly stringent regulations, some automobiles require multiple catalytic converters.

The four-way catalytic converter performs oxidation and reduction reactions and traps particulate matter to burn it away (regeneration can be done in an active or passive manner).

Suppliers of Catalytic converters and their related components include, but are not limited to, Corning, NGK, Denso, Ibiden, Emitec, Johnson Matthey, Engelhard, Catalytic Solutions, Delphi, Umicore, 3M, Schwarische Hutten-Werke GmbH (SHW); schulte (HJS), Clean Diesel Technology, Clean air systems, Arviniter, Tenneco, Ebersperscher, Faurecia, Donaldson, and Fleetguard.

Particulate traps or filters are another type of aftertreatment device commonly used in diesel applications because diesel fuel produces more particulate matter than gasoline or some alternative fuel. In a Diesel Particulate Trap (DPT), particulates in the exhaust stream pass through a filter that collects them. The removal of particulate matter collected on the trap, referred to as "regeneration," can be performed in a variety of ways. One method uses an external heater to raise the temperature of the filter to a level required to "burn off" PM. Another approach releases small amounts of diesel fuel in the exhaust stream. When the fuel particles contact the filter, the fuel burns off at an elevated temperature. This higher temperature also burns off PM in the filter. Yet another approach is to use a fuel borne catalyst to facilitate regeneration. In another approach, known as a "catalyzed diesel particulate trap," the catalyst is applied directly to the filter itself, reducing the temperature required to burn off PM. Finally, an oxidation catalyst may be utilized prior to the filter to facilitate burning off PM. Johnson Matthey's Continuous Regeneration Trap (CRT) is such a system. Diesel particulate traps may reduce PM by as much as 85% in some applications. In addition to PM, traps utilizing catalysts may also reduce other pollutants (e.g., HC, CO, and PM) with catalysts (as previously mentioned). Instead, these traps may become clogged with PM, soot and ash, and the catalytic variants may be poisoned. These also add to the cost and weight of the vehicle.

Diesel particulate traps may use many different types of filters, including: ceramic monolithic porous fibers (Corning, NGK), filament wound filters (3M), woven fibers (BUCK), woven fibers (HUG, 3M), sintered metal fibers (SHW, HJS), or filter paper, among others. Suppliers of these devices and their related technologies include, but are not limited to, Donaldson, Engelhard, Johnson Matthey, HJS, Eminos, Deutz, CoRning, ETG, Paas, and EngineControl Systems.

Selective Catalytic Reduction (SCR) is another example of an aftertreatment system. In this technique, a chemical, such as urea, that acts as a reducing agent is added before the exhaust gas reaches the catalyst chamber. Urea is hydrolyzed to form ammonia. The ammonia then reacts with NOx in the exhaust to produce N₂Gas, thereby reducing NOx emissions. The ammonia may be injected directly or maintained in solid urea, urea solution or crystalline form. An oxidation catalyst is often used in parallel with SCR to reduce CO and HC. Unfortunately, while SCR is effective at reducing NOx and has little catalyst decay and good fuel economy, additional tanks and infrastructure to refill the tanks are required on the vehicle. Also depending on the consent of the end user; companies and drivers are required to refill the tanks to maintain emissions control. Suppliers of SCRs or their components include, but are not limited to, Engelhard, Johnson Matthey, Miratech Corporation, McDermott, ICT, Sud Chemie, SK Catalysts, and PE Systems. Although limited in use in the united states, it is expected that SCR will be widely used in europe to reduce emissions, particularly in the heavy truck market.

A NOx adsorber is a material that stores NOx in a lean state and releases and catalytically reduces NOx in a rich state (typically every few minutes). This technology can be used in both gasoline and diesel applications, although gasoline provides a better fuel rich, high temperature environment. The NOx adsorbent reduces the contents of HC, NOx and CO, but has little effect on PM. They can function over a wide temperature range. In contrast, the NOx adsorption capacity decreases depending on the temperature, engine control and sensors are required, and the sulfur content of the fuel suppresses or disables the NOx adsorption capacity. In diesel applications, there are additional constraints, including the amount of oxygen present in the exhaust, HC utilization, temperature range, and smoke or particulate formation.

The NOx reducing catalyst can also be used to control emissions by: 1) active injection of reductant into the system prior to the catalyst and/or 2) use of a washcoat with zeolite that adsorbs HC, thereby creating an oxidation zone that is beneficial for reduction of NOx. While this technique may reduce NOx and PM, it is more expensive than many other techniques and may result in poor fuel economy or sulfate particulates.

The HC adsorber is designed to trap VOCs when the catalyst is treating low temperatures and then release VOCs when the catalyst is heated. This can be achieved by: 1) applying the sorbent directly onto the catalytic converter substrate, allowing for minor variations but with less control, 2) placing the sorbent in a separate but connected exhaust pipe before the catalytic converter and with air transfer passages when the converter is heated, and/or 3) placing the sorbent after the catalyst. The latter two options require adsorbent cleaning options. While this technique results in reduced cold start emissions, it is difficult to control and increases cost.

Since emissions have proven difficult to control, emissions control techniques are often combined in the system. Examples of combined systems include DeNOx and DPT (e.g., HJS' SCRT systems), catalytic converters placed in mufflers, SCR or catalytic diesel particulate filters integrated with mufflers.

AcERT is another example of a system that incorporates multiple emission control technologies. There are four target areas for ACERT from Caterpillar: air intake treatment, combustion, electronic and exhaust gas aftertreatment. Key components include single and series turbocharging for cooling the intake air; variable valve actuation for improved fuel combustion; electronic multiplex drive for integrated computer control; and catalytic conversion for reducing tailpipe particulate emissions. These subsystems cooperate to enable companies to increase fuel economy. An important disadvantage of this technique is the large volume of catalyst required.

There are many other emission control technologies, some of which are not yet technically feasible.

Catalytic converter

The concern for pollution caused in part by automobiles led to the 1970 air cleaning act, which required a 90% reduction in automobile exhaust. Some people are disputed about this forced reduction, but it is generally accepted that this forced reduction is an advance for clean air and better health.

The automotive industry is initially resistant to newly proposed regulations. Part of the resistance may stem from the industrial development of improved fuels. From the middle of the twentieth to the middle of the eighties of the twentieth century, motor gasoline fuels contain the additive Tetraethyllead (TEL). TEL improves fuel performance by preventing pre-ignition in the engine cylinders. Pre-ignition occurs when the fuel/air mixture in the engine combustion chamber ignites prematurely. This causes damage to the engine and results in reduced efficiency and power due to knock.

To meet government mandated emission reduction standards, engineers have devised catalytic converters. Catalytic converters were added to vehicle exhaust systems from approximately 1976. The catalytic converter effectively reduces emissions to a certain level. But the common gasoline formulation containing TEL interferes with the function of the catalytic converter. TEL in the fuel is eventually removed from the fuel because it poisons the metal catalyst of the catalytic converter.

While many people may know that many vehicles have catalytic converters, the technology is generally not known. The purpose of the catalytic converter is to convert or turn the pollutant exhaust gas into a less harmful compound such as nitrogen (N)₂About 78% of atmosphere), water (H)₂O) and carbon dioxide (CO)₂Products of photosynthesis within plants).

Use of catalytic converters to promote conversion of undesirable pollutants to relatively harmless molecules such as N₂、H₂O and CO₂. Catalytic converters primarily provide a surface on which contaminants are converted to relatively harmless products. The catalyst allows the reaction to proceed faster (or at lower temperatures) by reducing the activation energy required. The catalyst is not consumed in the reaction and can be reused (unless the catalyst is poisoned).

Typical pollutants in exhaust gases include nitrogen oxides (NOx), unburned hydrocarbons, carbon monoxide, and particulate matter. The nitrogen oxides may be reduced to form nitrogen gas. NO or NO₂Molecular contact catalystWhen the catalyst promotes the denitrification of the molecule with O₂Formally decomposing oxygen. Then nitrogen atoms attached to the catalyst react to formN₂Gas:and。

carbon monoxide, unburned hydrocarbons and particulate matter can be further oxidized to form non-pollutants. For example, carbon monoxide is treated as follows:。

the overall result of the catalytic converter is complete combustion of the fuel to produce non-pollutants.

Conventional catalytic converters have many limitations in the efficiency of eliminating pollutants. For example, if located too close to the engine, it may crack due to overheating or rapid temperature changes. Strictly speaking, the filter of a conventional catalytic converter cannot be located in close proximity to or within the engine exhaust manifold, which is the best location to utilize the high temperatures in the field before the temperature drops due to radiative cooling resulting from the high thermal conductivity of the exhaust pipe material. Engine vibrations and rapid changes in temperature present near and within the exhaust manifold can cause fatigue in conventional filter materials and significantly shorten the life of the filter. Furthermore, certain catalysts used in conventional filters are less efficient or even no longer functional at high temperatures, i.e. above 500 ℃. Accordingly, conventional catalytic converter filters are typically located in the exhaust passage at a location remote from the engine.

Structure of catalytic converter and particulate filter

The components and materials of the catalytic converter are diagrammatically shown in fig. 4a and 4 b. The catalyst substrate is held within the converter housing (also referred to as a can) by a packing mat (typically made of ceramic fibers). The converter is connected to the vehicle exhaust system by a terminal cone that may be welded to the housing or made as one piece with the housing, depending on the converter assembly technology. The other part end seal and/or support steel ring shown in the figure is optional; these components are not typically present in modern passenger car converters, but may be required in more demanding applications such as integrated converters, large converters for heavy duty engines, or diesel particulate filters. Catalytic converters, especially those in gasoline applications, may also be equipped with steel heat shields (not shown) to protect adjacent vehicle components from exposure to excessive temperatures.

Catalytic converters are generally composed of at least five major components: 1) a substrate; 2) a catalytic coating; 3) a wash coat; 4) cushion (matting) and 5) can. A conventional catalytic converter is shown in diagram X. In certain applications, a catalytic coating is optional, as described in detail below.

Base material

A substrate is a solid surface on which contaminants can be converted to non-contaminants. Physically, the substrate provides interfacial interactions for many molecular species in any physical state, such as solid, liquid, or gas. The substrate generally has a large surface area to provide a large area over which contaminants can be converted to non-contaminants.

Over the past several decades, many different materials and designs have been tested as substrates for chemical reactions. For example, the primary physical structures include honeycomb monolith structures and bead structures. (see FIG. 1). The honeycomb structure comprises a plurality of channels, generally parallel to each other along the length of the substrate. The substrate has a channel running the length of the substrate. The channel width varies, typically depending on the matrix material and its application. These passages allow exhaust gas to flow from the engine through the catalytic converter and exit through the exhaust pipe. While the exhaust gas flows through the substrate channels, the contaminant molecules are converted into non-contaminant molecules through chemical reactions and physical changes.

In a bead structure, the substrate is made of a stack of small beads (similar to a string of jelly beans placed inside a tube). Exhaust gas can flow around the beads (through channels and crevices). The pollutants are converted to non-pollutants when the exhaust gas hits the beads. Bead structure was one of the early attempts to maximize the surface area of the substrate contacted by the exhaust gas molecules.

Many different materials have been used as substrates. These include ceramics, Fiber Reinforced Ceramic Matrix Composites (FRCMCs), foams, powdered ceramics, nanocomposites, metals, and fiber mat substrates. The most commonly used is the ceramic known as cordierite, produced by Corning. Cordierite is a ceramic formed from a refractory powder. FRCMC is an open-cell foam in which a catalyst is disposed on the cell walls, the foam being disposed within the catalyst such that exhaust gas must exit through the cells of the foam. Foams are solids containing many pores formed by bubbles and fired voids. Powdered ceramic substrates differ from cordierite and related ceramics in that powdered ceramics are formed from sintered ceramic powders. Nanocomposites are materials that employ nanopowders and/or nanofibers. Metals may also be used as the substrate. Corrugated metal foils, such as steel sheets, are typically rolled into a honeycomb structure. The fibrous mat substrate is a small scale woven material. Some fibrous mat substrates employ NEXTEL fibers produced by 3M. In addition, "two-dimensional" nonwoven fibrous composites have also been tried, utilizing folded pleats and/or corrugations to form honeycomb structures. See, for example, US4,894,070, 5,196,120, and 6,444,006B 1.

Catalytic coating

The third component of current catalytic converters is the catalytic coating. As its name implies, the catalytic coating is the component that actually catalyzes the conversion of contaminants to non-contaminants.

A catalyst is generally defined as a substance that affects the rate of a chemical reaction but is not one of the original reactants or the final product, i.e., it is not consumed or altered in the reaction. In several known catalytic reaction mechanisms, the catalyst forms an intermediate compound with the reactants but rejuvenates during the reaction. Many other catalytic processes are not fully explained or fully understood. The principles governing the selection and preparation of catalysts for specific purposes are not fully explained or fully understood. Many advances in this area have been made through elaborate exploration protocols, including testing of countless materials. Catalysts are widely used in chemical and petrochemical processes to promote reactions that are too slow or require high temperatures to achieve good efficiency. Catalysts are also used to convert harmful components of engine exhaust gases, such as hydrocarbons and carbon monoxide, into harmless substances such as carbon dioxide and water vapor.

A catalyst is a substance that accelerates certain chemical reactions between components of the exhaust gas. In emission control catalysis, solid catalysts are used to catalyze the gas phase reactions. By providing sufficient contact between the gas phase and the solid catalyst, catalysis and observed reaction rates are maximized. In catalytic reactors, such intimate contact is often achieved by providing a high catalytic surface area by highly dispersing the catalyst on a high specific surface area support (carrier).

The catalytic coating is applied to the substrate after the substrate is formed. The coating forms a layer on the surface of the substrate, the layer containing the catalyst. Different types of catalysts are required depending on, for example, the chemical reaction, the desired application, temperature conditions, economic factors, etc. Many metal catalysts are known in the art. For example, platinum, palladium and rhodium are most commonly used. Much research has been done to develop new catalysts.

The rate of chemical reactions, including catalytic reactions, generally increases with increasing temperature. Conversion efficiencyA strong dependence on temperature is characteristic of all emission control catalysts. A typical relationship between the catalytic conversion rate of the pollutants and the temperature is shown in fig. 4 with a solid line (a). The conversion approaches zero at low temperatures, increases slowly and then more rapidly, reaching a plateau at high gas temperatures. Discussion of combustion reactions, the term light-off temperature is commonly used to characterize this property. Catalyst light-off is the minimum temperature required to initiate a catalytic reaction. The above definition is not very accurate due to the gradual increase in reaction rate. By more precise definition, the light-off temperature is the temperature at which the conversion reaches 50%. This temperature is generally denoted as T₅₀. When comparing the activity of different catalysts, the lowest light-off temperature for a given reaction indicates the highest catalyst activity.

In some catalyst systems, increasing the temperature only increases the conversion efficiency to no more than a certain point, as shown by the dashed line (B) in FIG. 4. Further increases in temperature, although increasing the reaction rate, result in a decrease in catalyst conversion efficiency. Efficiency degradation is often explained by other competing reactions that consume reactant concentrations or by thermodynamic equilibrium limitations.

The temperature range corresponding to high conversion efficiency is generally referred to as the catalyst temperature optimum range. Such conversion curves are characteristic of selective catalytic processes. Good examples include the selective reduction of NO with hydrocarbons or ammonia.

Another important variable affecting conversion efficiency is transThe size of the reactor. The gas flow rate through a catalytic reactor is generally expressed as Space Velocity (SV) relative to the reactor size. Space velocity is defined as the volume of gas in the reactor per unit volume of monomer measured under standard conditions (STP), e.g. (3) SV ═ V/V_rShown, where V is the gas volume flow rate at STP, m³/h；V_rIs the reactor volume, m³(ii) a And SV is the reciprocal of time, often in l/h or h^-1And (4) showing.

In various catalytic emission control applications, the space velocity is in the range of 10,000l/h to 300,000 l/h. The space velocity of a monolith reactor is calculated based on its external dimensions, such as the diameter and length of the cylindrical ceramic catalyst substrate. This method is not always suitable for catalyst comparison as it does not take into account the geometric surface area of the substrate, the pore density, the wall thickness or the catalyst loading. However, it is a common and generally accepted industry standard.

Typical platinum loading in filters for twenty-century ninety-year off-road engines is 35g/ft³To 50g/ft³In the meantime. These filters are mounted on relatively heavily contaminated engines and requireRegeneration is performed at a minimum temperature of approximately 400 ℃. Later, catalytic filters were found to regenerate at much lower temperatures when used on the engine of much cleaner city buses and other road vehicles. But higher platinum loadings are required to maintain low temperature regeneration. Typical platinum loadings for cleaning filters used in engines in low temperature applications are 50-75g/ft³。

Washcoating

In most cases, the catalytic coating includes a washcoat as a fourth component. The wash coat is applied to the surface of the substrate, thereby increasing the surface area of the substrate. The washcoat also provides a catalyst-adherent surface. A metal catalyst may be impregnated on top of this porous high surface area layer of inorganic support (i.e. washcoat-the term "catalyst support" may be used to refer to ceramic/metal substrates, as well as support/washcoat materials).

Many substances are useful as washcoats. Widely used materials for catalyst supports include activated alumina and silica (silica).

Washcoats are porous, high surface area layers bonded to the surface of a support. The exact function is indeed complex and not yet understood or clearly explained. The primary function of washcoats is to provide the very high surface area required to disperse the catalytic metal. In addition, washcoats can physically separate to prevent undesirable reactions between components of complex catalytic systems.

The material of the wash coat comprises an inorganic base metal oxide such as Al₂O₃(alumina or alumina), SiO₂、TiO₂、CeO₂、ZrO₂、V₂O₅、La₂O₃And zeolites. Some of them are used as catalyst supports. Others are added to the washcoat as promoters or stabilizers. Still others exhibit catalytic activity of their own. Good washcoat materials are characterized by high specific surface area and thermal stability. The specific surface area is determined by a nitrogen adsorption measurement technique in combination with mathematical modeling, known as the BET (Brunauer, Emmet and Teller) method. Thermal stability is evaluated by exposing a sample of a given material to elevated temperatures under a controlled atmosphere, typically in the presence of oxygen and water vapor. The BET surface area loss, re-measured at different time intervals during the test, indicates the degree of thermal degradation of the test material.

The washcoat may be applied to the catalyst support from an aqueous slurry. The wet washcoated portions are then dried and calcined at elevated temperatures. The quality of the catalyst washcoat can have a significant impact on the performance and durability of the finished catalyst. Since the precious metal is then applied to the washcoated portion by dip coating, i.e., by "soaking" the washcoated pores with the catalyst solution, the washcoat loading will determine the loading of the precious metal catalyst in the finished product. Thus, it is of paramount importance that the washcoating process results in a reproducible and very uniform washcoat. Details of the washcoating process and its parameters are protected as trade secrets by all catalyst manufacturers.

Pot for storing food

The substrate is packaged into a can, such as a steel housing, to form a catalytic converter. The canister has multiple functions. It houses the catalytic substrate and protects the substrate from the external environment. In addition, the canister forces the exhaust gas to flow through and/or over the catalytic substrate.

The catalytic substrate may also be packaged within a muffler, and is referred to as a "catalyst muffler" or "catalytic muffler". In this case, one steel tank contains both the catalyst and noise abatement components such as baffles and perforated pipes. The catalyst muffler may provide a more space-saving design than a catalytic converter and muffler combination.

The catalytic substrate is typically placed in a canister and has a configuration made in one of several ways, including: clamshell, strapping (tourniquet), shoe box, padding, and swage, as shown in fig. 28.

Cushion layer

In addition to the canister, the catalytic substrate is typically packaged within the canister with a mat material. The packaging cushions, which are typically made of ceramic fibers, may be used to protect the substrate and evenly distribute the pressure from the shell. The mat typically comprises vermiculite, which expands at high temperatures to compensate for thermal expansion of the shell and provide sufficient clamping force under all operating conditions.

For example, the ceramic monolith is encased in a special packaging material that securely holds the monolith ceramic within the steel can, evenly distributes pressure and prevents cracking. Ceramic fiber mats are used mostly to package catalytic converters for gasoline and diesel applications. These packaging cushions can be classified as follows: an inflatable (heat expandable) pad; regular (high vermiculite); low vermiculite; a non-intumescent mat or a hybrid mat.

Thermal insulation

In many applications, it is necessary to insulate the catalytic converter to avoid damage to surrounding vehicle components (e.g., plastic parts, fluid hoses) or to prevent cabin temperature from rising in converters mounted closer to the engine. One approach to thermal management of the converter is to use steel heat shields placed around the converter body. Another approach is to provide a layer of thermal insulation within the housing by (1) increasing the thickness of the mounting mat or (2) providing a dedicated additional layer of low thermal conductivity insulation. While Heat shields have traditionally been used under floors, increasing pad thickness has been proposed to provide the best solution for cabin-Mounted Converters (Said Zidat and Michael parameterizer, "Heat insulation methods for modified Mount convertors," Delphi Automotives, Technical Centre Luxembourg, SAE Technical Paper Series 2000-01-0215). One of the advantages of using a thicker mat rather than a heat shield is that the average temperature of the mat is lower, which minimizes the risk of damage to the vermiculite mat in an integrated gasoline engine application.

Particle catcher

Another device for removing pollutants from exhaust gases is a particulate trap. A common particulate trap used on diesel engines is the Diesel Particulate Trap (DPT). The primary purpose of particulate traps is to filter and trap particulate matter of various sizes in a fluid stream, such as an exhaust stream. The effectiveness of particulate filters is generally measured in terms of their ability to filter different sizes of PM, such as PM-2.5 and PM-10.

Diesel traps are relatively effective at removing soot from diesel engine exhaust. The most widely used diesel traps are the wall-flow filters, which filter the diesel exhaust by trapping soot on the porous walls of the filter body. Wall-flow filters are designed to almost completely filter out soot without significantly obstructing the exhaust flow.

Because the soot layer collects on the surface of the filter inlet passage, the low permeability of the soot layer creates a pressure drop across the filter and a gradual rise in the back pressure of the filter relative to the engine, causing the engine to run harder, thereby affecting the engine operating efficiency. Eventually, the pressure drop becomes unacceptable and the filter must be regenerated. In conventional systems, the regeneration process involves heating the filter to initiate soot combustion. In some cases, regeneration is achieved under controlled conditions that operate the engine, thereby initiating slow combustion and lasting for many minutes during which the temperature in the filter is raised from about 400-600 ℃ to a maximum temperature of about 800-1000 ℃.

In some applications, the highest temperature during regeneration tends to occur adjacent the outlet end of the filter due to the cumulative effect of the soot combustion wave advancing from the inlet face to the outlet face of the filter as the exhaust flow carries combustion heat outwardly along the filter. In some cases, so-called "uncontrolled regeneration" may occur when high oxygen levels and low flow rates in the exhaust (e.g., engine idle conditions) occur simultaneously with or immediately following the initiation of combustion. During uncontrolled regeneration, soot combustion may produce temperature spikes within the filter, which may thermally shock and crack or even melt the filter. The most commonly observed temperature gradients are the radial temperature gradient where the temperature in the center of the filter is higher than the temperature in the rest of the substrate and the axial temperature gradient where the outlet end of the filter is hotter than the rest of the substrate.

In addition to trapping soot, the filter also traps metal oxide "ash" particles carried by the exhaust gas. Typically, these deposits result from unburned lubricating oil that accompanies the exhaust gas under certain conditions. These particles are not combusted and are not removed during regeneration. However, if the temperature is high enough during uncontrolled regeneration, the ash may eventually sinter to the filter or even react with the filter resulting in partial melting.

It would be an advance in the art to obtain a filter with improved resistance to melting and thermal shock damage such that the filter can withstand not only many controlled regenerations over its useful life, but also much fewer but more aggressive uncontrolled regenerations.

Continuous regeneration trap

One conventional method for catalytic conversion is the diesel particulate trap ("DPT"). DPT is a filter that collects particulate matter in the exhaust. Then must be burned before the filter becomes cloggedThe collected particulate matter is discarded. Burning off the particulate matter is referred to as "regeneration". There are several conventional methods for regenerating DPTs. First, coating the filter surface with a precious metal catalyst or a base metal catalyst can reduce the temperature required for particulate oxidation. Second, the filter can be used to generate NO₂After the chamber containing the oxidation catalyst, this helps to burn off the particulate matter. Third, the system may use a fuel borne catalyst. Finally, an external heat source can be utilized, wherein no catalyst is presentIn which case the soot burns at 550 c or at about 260 c in the presence of a noble metal catalyst. Regeneration leaves ash as the carbon burns, requiring constant maintenance to clean the filter.

Yet another conventional approach utilizes diesel oxidation catalysts ("DOCs"). DOCs are catalytic converters that oxidize CO and hydrocarbons. The activity of hydrocarbons extends to polynuclear aromatic hydrocarbons ("PAHs") and soluble organic fractions of particulate matter ("SOF"). Catalyst formulations have been developed that selectively oxidize SOFs while minimizing the oxidation of sulfur dioxide or nitrogen oxides. However, DOCs can produce sulfuric acid and increase NO₂And (4) discharging.

The role of the catalyst in a Catalyzed Diesel Particulate Filter (CDPF) is to lower the soot combustion temperature and thereby promote regeneration of the filter by oxidizing Diesel Particulate Matter (DPM) at exhaust temperatures experienced during normal engine/vehicle operation, typically in the range of 300-. In the absence of a catalyst, DPM can be oxidized at very high rates at temperatures in excess of 500 ℃, which are rarely the case in diesel engines during actual operation. Substrates reported for use in these catalyst applications include cordierite and silicon carbide wall-flow monoliths, wire mesh, porous ceramic and ceramic fiber media, and the like. The most commonly used CDPF is a catalytic ceramic wall flow monolith structure.

Catalytic ceramic traps were developed in the early eighties of the twentieth century. Their earliest applications included diesel powered vehicles and later underground mining machinery. The catalytic filter was introduced commercially in california in 1985 for use in commercial Mercedes automobiles. Mercedes types 300SD and 300D with turbocharged engines were fitted with 5.66 "diameter x 6" filters installed between the engine and the turbocharger.

Later use of diesel traps in automobiles was abandoned because of problems of insufficient durability, increased pressure drop, and filter plugging. At present, even though these problems have not been solved, catalyzed ceramic traps are one of the most important diesel filter technologies. CDPFs are increasingly used in many heavy duty applications such as city buses and city diesel trucks. For many years, limited amounts of catalytic filters have also been used in underground mining (north america and australia) and in certain stationary engine applications.

Catalyzed ceramic filters are commercially available for many on-highway, off-road and stationary engine applications as OEM and after-market (retrofit) products. Suppliers include Engelhard, OMG dmc2, and some smaller emission control manufacturers primarily specializing in the off-road market.

The primary component of a conventional filter is a ceramic (typically cordierite or SiC) wall-flow monolith structure. The porous walls of the monolith are coated with an active catalyst. As the diesel exhaust fumes permeate through these walls, soot particles are deposited within the wall pore network and on the intake passage surfaces. The catalyst promotes the oxidation of DPM by oxygen present in the exhaust gas.

Pressure drop

The exhaust flow through a conventional catalytic converter creates a significant amount of backpressure. Backpressure buildup in a catalytic converter is an important indicator of catalytic converter success. If the catalytic converter becomes partially or fully plugged, a restriction will be created in the exhaust system. Subsequent back pressure build-up will result in a dramatic decrease in engine performance (e.g., power and torque) and fuel economy, and may even result in engine misfire after engine start-up if the blockage is severe. Conventional attempts to reduce pollutant emissions are costly because of the high cost of both materials and the original engine that modified or manufactured the appropriate filter.

High filtration efficiency of wall-flow filters is achieved at the expense of a relatively high pressure drop, which increases with increasing filter soot loading. The filter is initially clean. As particles begin to deposit within the pores of the monolithic structure walls (deep filtration), the pressure drop begins to increase in a non-linear manner with time. This phase is referred to as the initial loading phase, during which the properties of the pores, such as permeability and filter porosity, are constantly changing due to the increasing deposition of soot within the network of pores. After the filtration capacity of the pores has reached saturation, the soot begins to deposit as a layer in the inlet channels of the monolithic structure (cake filtration phase). During this time a linear increase in pressure drop (and soot loading) was observed. One property that varies is the thickness of the soot layer. Some authors also identified intermediate short transition periods from when the particles began to deposit on the channel surfaces until the soot layer was completely formed (Tan, j.c., et al, 1996, "a Study on the Regeneration Process in Diesel Particulate traps Using a coater Fuel addition", SAE 960136; versaaevel, p.et al, 2000, "Some atmospheric emissions on Diesel Particulate filter modeling and complex bed catalysts and Experiments", SAE 2000-01-0477).

Pressure drop simulations in cleaning the filter substrate have been completed. A relatively simple Model has been developed that shows excellent agreement with the test results (Masoudi, M., et al., 2000, "differentiating Pressure Drop of Wall-Flow Diesel Particulate Filters-Theory and Experiment", SAE 2000-01-0184; Masoudi, M., et al., 2001, "differentiation of a Model and Development of a silicon for differentiating the Pressure Drop of Diesel Particulate Filters," SAE 2001-01-0911). However, in practice the pressure drop of the filter is mostly caused by soot deposits. In practice, the pressure drop of a clean wall-flow filter may be in the range of 1kPa to 2kPa, while a pressure drop of a 10kPa loaded filter may in some cases be considered low to moderate.

The total pressure drop of a particle loaded filter can be divided into the following four components: pressure drop due to sudden filter inlet and outlet contraction and expansion; pressure drop due to channel wall friction; pressure drop due to permeability of the particle layer; and the pressure drop due to the permeability of the wall.

The pressure drop due to sudden filter inlet and outlet contraction and expansion is similar to the same part of a clean filter, except now the effective channel size (hydraulic diameter) becomes smaller due to the soot layer, resulting in more gas contraction.

The pressure drop due to channel wall friction also increases compared to the clean filter case because the hydraulic diameter of the channels decreases. The Δ P channel can be a significant contributor to the total pressure drop when the soot layer is thick.

The pressure drop (Δ Ρ particles) due to the permeability of the particle layer can be an important contributor to the overall pressure drop.

The pressure drop (Δ Ρ wall) due to the permeability of the wall is now also higher than in a clean filter, since the wall pores are partially filled with soot. The increase in Δ Ρ wall attributable to the initial soot loading phase within the pores is represented by Δ PI in fig. 3.

The total pressure drop may be expressed as follows:

Δ P ═ Δ P inlet/outlet + Δ P channels + Δ P particles + Δ P walls

Mathematical modeling of pressure drop in soot loaded diesel filters becomes a complex and difficult task. Important properties of soot, such as permeability and packing density, depend on the application, engine operating conditions, and other parameters. Efforts are being made to simulate pressure drop in wall flow filters and increasingly sophisticated models are being developed. Prediction of the actual soot loading may require a theoretical model of the regeneration process itself.

Catalytic converter and particulate filter type

Catalytic converters may be classified according to a number of factors, including: a) the type of engine on which the converter is used, b) the position of the catalytic converter relative to the engine, c) the amount and type of catalyst used in the converter, and d) the type and structure of the substrate used. In addition, each of these catalytic converters is typically used in conjunction with other emission control devices, such as CRT, EGR, SCR, aert, and other devices and methods.

Engine

Catalytic converters are used on at least two types of engines, gasoline and diesel engines. There are many types of specific gasoline and diesel engines in these two general categories. For example, gasoline and diesel engines are manufactured with different displacement and power. Some engines are equipped with turbochargers and/or intercoolers. Most automobile and truck engines are water cooled, while many motorcycle engines are air cooled. Some applications require high power to be available, while others require maximum fuel economy. All of these variables and others may affect the extent to which pollutants are produced during the combustion of a fuel. Furthermore, there are different regulatory requirements on emission standards depending on the use of the engine, such as on-road, off-road, or stationary.

Position of

The catalytic converter may in principle be mounted at any location along the exhaust stream of the engine. But the physical characteristics of conventional catalytic converters limit their location. It is most common in vehicles to mount the catalytic converter at some distance from the engine block, closer to the muffler, and under the vehicle body. The catalytic converter is typically not mounted close to the engine because the catalytic converter may fail for several reasons. These include extreme temperatures, thermal shock, mechanical vibration, mechanical stress, and space constraints near the engine. Furthermore, the physical equipment that holds the engine may limit the location of the catalytic converter or particulate filter.

For example, in its 2004 focu.s.^TMIn (D), the Ford Motor Company is equipped with a manifold catalytic converter, as in one of its products by Honda Motor Corporation. These systems are actually adjacent to the manifold and not part of the manifold. The high temperatures and extreme vibration generated by cylinder explosions and moving parts can subject current catalytic converters (if placed in the manifold) to extreme thermal and mechanical shock. In addition, Northup Grumman Corporation in US 5,692,373 proposes a design for a manifold catalytic converter. It is believed that even current cordierite substrates present a situation that tolerates such environmental challenges.

In other applications, such as motorcycles (e.g., Harley-Davidson), the presence of a catalytic converter in some locations may cause serious injury to the user. Due to the high operating temperature of the catalytic converter, it is preferable to use a catalytic converter that is less harmful to the user, such as a smaller catalytic converter, a converter that does not become so hot, and the like.

In some cases, an exhaust system (e.g., in an automobile) may contain more than one catalytic converter or particulate filter along its exhaust stream. (see fig. 4). For example, the exhaust system may have another catalytic converter located between the engine and the main catalytic converter. This configuration is referred to as a pre-catalytic converter (pre-cat). The pre-catalytic converter may have a more dense configuration. Another assembly is a post-catalytic converter (back-cat) with a secondary catalytic converter located after (or after) the primary catalytic converter. Post catalytic converters are also sometimes used to retrofit catalytic converters.

Double effect, triple effect and quadruple effect

Catalytic converters can be generally classified as double-effect, triple-effect or quadruple-effect converters. At least the following types of converters are commercially available: an oxidation converter, a three-way converter (no air), a three-way oxygenation converter, and a four-way converter.

The oxidation (double effect) converter represents an earlier generation converter designed to oxidize Hydrocarbons (HC) and carbon monoxide (CO). While these devices represent the most basic form of catalytic converter technology, in some areas they are still viable pollution reduction options. The oxidation converter typically contains platinum or palladium. But other non-noble metals may also be used.

Early in the eighties of the twentieth century, most vehicle manufacturers began using converters designed to reduce NOx in addition to oxidizing HC and CO. These three-way converters are used with computer controlled engine systems and oxygen sensors for more precise control of air-fuel ratio. These converters are called three-way converters because they process three compounds: HC. CO and NOx.

Most modern automobiles are equipped with "three-way" catalytic converters, typically having one or more substrates in series, using Corning's clay extrusion technology. By "three-way" is meant three controlled emissions that the converter helps reduce: carbon monoxide, volatile organic compounds (VOCs, e.g., unburned hydrocarbons), and NOx molecules. Such converters use two different types of catalysts, namely a reduction catalyst and an oxidation catalyst.

In a three-way catalytic converter, a reduction catalyst is typically present in the first stage of the catalytic converter for reversing the nitrogen oxidation occurring within the combustion chamber. Platinum and rhodium are commonly utilized to help reduce NOx emissions. The oxidation catalyst, which may be comprised of a metal such as platinum and/or palladium, is typically located in the second zone of the catalytic converter.

Three-way converters having both reduction and oxidation catalysts in one housing are sometimes referred to as three-way plus oxidation converters. These converters employ air jets between two substrates. This air jet assists the oxidation chemistry.

The four-way converter processes carbon monoxide, nitrogen oxides, unburned hydrocarbons and particulates. These include, for example, quadrcat four-way catalytic converters manufactured by Ceryx. According to its manufacturer, the catalytic converter reduces the four main sources of air pollution-NOx, hydrocarbons, carbon monoxide and particulate matter to levels that make diesel engines meet 2002/2004 emission standards. Others include those described in US4,329,162 and 5,253,476.

Catalytic converters, like other catalysts, promote a reaction by lowering the activation energy required to complete the desired reaction. For example, if a temperature of 550 ℃ was previously required for the reaction of the particles with oxygen to burn out, this same reaction may require only a temperature of 260 ℃ in the presence of a catalyst. This lower energy threshold allows the catalytic system to be physically placed downstream of the engine where space is larger, even at lower temperatures. Otherwise, the catalytic system would need to be placed upstream of the higher temperature. But this is impractical with current technology because substrates are more likely to be damaged when placed closer to the engine.

Diesel engines produce emissions that are high in NOx and particulates and low in CO and hydrocarbons due to high temperatures and pressures. Compression combustion is less complete than when a gasoline engine is fired. However, diesel fuel provides better gas mileage than gasoline engines due to the relatively dilute mixture with high air content. Three-way catalysts are not effective in diesel exhaust because of excess air. NOx reduction catalysts are typically required to maintain a good stoichiometric ratio of fuel to air, which is not easily achieved in diesel-fueled engines.

Catalytic converter technology can be used in a variety of applications, including internal combustion engines and stationary combustion engines. Internal combustion engines are the most common engines used in vehicles. A catalytic converter is installed as a device in a vehicle exhaust system to pass the entire exhaust stream through a substrate, into contact with a catalyst, and then out of the tailpipe. Catalytic converters can also be part of a fairly complex system involving various active strategies such as injecting reactants before the catalyst or sophisticated engine control algorithms. Examples include many diesel catalyst systems being developed for NOx reduction. The simplicity and passivity attributes already enumerated in the advantages of the catalyst may no longer be applicable to those systems.

Conventional attempts to reduce pollutant emissions can be expensive, in part, due to raw material costs and the need to retrofit or manufacture the original engine with appropriate filters in certain applications.

Advances in catalytic converter and particulate filter technology

The invention that led to the advancement of catalytic converters was an extruded cordierite honeycomb monolith structure developed by Corning. (see US4,033,779). Over billions of pounds of pollutants have been removed from exhaust gas streams by this method since the seventies of the twentieth century, which is capable of withstanding the extreme environment of an engine exhaust system, using catalysts from the precious and base metal groups (platinum, palladium, rhodium, etc.) within a washcoat firmly anchored to the surface of a bumpy substrate, typically cordierite. Over the years, changes and improvements to this core technology have gradually been made, including changes to the arrangement of catalytic converters and their compositions and methods of manufacture. But there are still fundamental deficiencies that have not been overcome to date. Currently, the state of the art reaches physical and economic limits, with only minor improvements being obtained at great expense.

Limitation of the current substrate

While current catalytic converter and particulate filter technology is suitable to some extent for reducing emission pollution, current technology does have some drawbacks. There are also properties that cannot be met by current catalytic converters. Some of the deficiencies are inherent in the type of substrate used. Thus, an improved substrate for a catalytic converter or particulate filter would be a significant advance in the basic physical and chemical properties of the materials used as catalyst substrates in catalytic converters. In addition, the improved substrate should be of significantly improved quality, enabling manufacturers and users to more easily comply with 2007, 2010 and beyond emission standards.

The substrates of conventional monolithic catalytic converters are typically formed by extrusion. This complex and relatively expensive method has been used for the last twenty-five years. But extrusion methods have limitations. There are limits to how small channels can be created within the material while still maintaining quality control. The extrusion method also limits the shape of the catalytic converter to a cylinder or parallelogram, or a shape with the sides parallel to the extrusion axis. This shape limitation has not been a problem under previous emission standards. The need to design catalytic converters and particulate filters to achieve near zero emission performance may require non-linear and/or non-cylindrical filter designs and vehicle integration.

Reducing the wall thickness increases the surface area, for example, in some cases decreasing the wall thickness from 0.006 inch to 0.002 inch increases the surface area by 54%. By increasing the surface area, more particulate can be deposited in a smaller volume. FIG. 1 illustrates a prior art honeycomb configuration 102 formed within a ceramic filter element 100 configured to increase the surface area of a catalytic converter. The honeycomb structure 102 is formed by an extrusion process in which long channels are formed with their major axes parallel to the extrusion. The openings of these channels face the incoming exhaust gas flow.

With advances in technology, ceramic cordierite substrates having reduced wall thicknesses have been produced. 400/6.5 of the standard configuration 400cpsi cell density and 0.0065 "(or about 0.17mm) previously used in passenger cars is gradually replaced with thinner walled substrates (0.0055 to 0.004 mil). But is already approaching the physical limits of the material. Due to the physical properties of ceramics, particularly cordierite, it is not practical to use substrates made of even thinner walled cordierite ceramics. Thinner walled materials do not meet other necessary characteristics (e.g., durability, heat resistance).

Diesel catalysts typically have thicker walls than their automotive counterparts, due in part to their larger size. Since diesel wall flow filters typically have thicker walls, there are physical limits to the number of channels per square inch that these filters can have. Generally, there are no commercially available diesel wall flow filters having more than 200 channels per square inch.

Another limitation of currently available substrates is their reduced catalytic efficiency at lower temperatures. At low temperatures of the converter system, such as at engine start-up, the temperature is not high enough to initiate the catalytic reaction. Cordierite, silicon carbide and various metal substrates used in catalytic converters and currently sold by Corning, NGK, Denso and others are made of very tough, dense materials that are excellent in mechanical strength and resistance to thermal shock and vibration. However, these materials require time to absorb heat from start-up to a temperature sufficient to allow the catalytic reaction to proceed. Due to the catalytic reaction start-up delay, it is estimated that about 50% of the total emissions of modern engines are released into the atmosphere within the first 25 seconds of engine operation. Even small improvements in the key seconds of "cold start" can lead to significant improvements in the amount of contaminants successfully treated each year. While efforts have been made to address this problem, there remains a need for a catalytic converter that reduces emissions during this critical cold start. Even with the most advanced and expensive technology currently employed, a cordierite-based catalytic converter requires about 20 seconds to start up.

In order to reach the reaction temperature more quickly, attempts have been made to move the converter closer to the engine exhaust manifold where higher temperatures can be reached more quickly and also where higher temperatures promote more vigorous reactions during operation. Due to the limited space available under the hood of an automobile, the size of the converter system, and thus the throughput that can be successfully handled, is limited. Current substrates are not effectively used within the cabin of a vehicle. In addition, it is undesirable to add additional weight to the nacelle, and many of the current substrates are dense and have limited porosity (about 50% or less), requiring both heavy and bulky systems to handle large-scale exhaust volumes. Furthermore, substrates such as cordierite tend to melt under many operating conditions, causing plugging and increasing back pressure.

Other methods of compensating for cold starts include a refinery adsorption system that temporarily stores NOx and/or hydrocarbons so that the converter can treat NOx and/or hydrocarbons as soon as the converter reaches a critical temperature. Some of these systems require parallel piping and elaborate adsorption surfaces, additional valves and control mechanisms, or multiple different washcoats for catalyst adhesion to the substrate and isolation of the reaction environment. This is achieved byThe problem is particularly challenging in diesel engines that may need to trap large amounts of soot particulates, NOx, and SOx. In some large industrial diesel engines, rotating banks of diesel particulate traps are utilized to collect, store, and then dispose of the particulates. (in other systems, NOx is stored and reduced to N in the presence of NOx₂While using it as an oxidant to convert CO to CO₂。)

Given the regulatory limits on total emissions, a system that can easily even curtail some of the 50% emissions that occur during cold start may not require some of the costly and elaborate work described above. For use with these work areas, such a system can significantly reduce emissions. As previously explained, however, conventional systems are generally complex and expensive, and also tend to misfire and/or operate erratically.

Another inherent limitation of conventional systems is the typical "residence time" required to burn off the particles. It is important that the converter be able to ignite quickly, considering the large flow rates of the exhaust gases emitted during operation and the flow rates that the gases must achieve. Thus, a catalytic converter that can ignite quickly, can withstand extreme thermal and vibrational shock, and can build up internal temperatures quickly during cold start would greatly enhance the industry's ability to reduce emissions, meet the upcoming 2007 and 2010 environmental standards, produce cleaner-running automobiles, trucks, buses, and heavy industrial engines.

If the substrate is also lightweight, it will also lead to improved mileage statistics for new vehicles. However, no substrate has been found to date which addresses many or all of these problems.

Design considerations for substrates for catalytic converters or particulate filters

The catalyst substrate is a critical component that affects the performance, strength, and durability of the catalytic converter system. In addition, the filter substrate also significantly affects the operational performance of the particulate filter. Ideally, the substrate used in a catalytic converter or particulate filter should have a number of attributes. These attributes include, but are not necessarily limited to, one or more of the following: a) a surface area; b) porosity/permeability; c) the radiance; d) thermal conductivity; f) thermal properties such as thermal shock resistance, thermal expansion, and thermal conductivity; g) density; h) structural integrity; i) efficiency of pollutant treatment; j) catalyst requirements; and k) the weight of the system. Optimizing a catalytic or filtration substrate for one or more attributes would be an advance in the field of filtering fluids and catalytic reactions.

Disclosure of Invention

Various embodiments are described in this summary. These and other embodiments of the invention are described in the detailed description section below.

The inventors of the present invention have discovered that a non-woven sintered refractory fiber ceramic (nSiRF-C) composite material (as described herein) can be used as and made into an improved substrate for catalytic converters, particulate filters, and related devices.

The inventors of the present invention have also discovered that improved catalytic substrates and improved filtration substrates can be prepared from materials having the specific attributes described herein. For example, suitable attributes include high melting point, low thermal conductivity, low thermal expansion system, resistance to thermal and vibrational shock, low density, and very high porosity and permeability. An exemplary material having these properties in one embodiment is nSiRF-C.

An example of a material with suitable properties is an nSiRF-C composite. An example of nSiRF-C is an alumina enhanced thermal barrier ("AETB") material or similar material that may be used as a catalytic substrate or a filtration substrate according to embodiments of the present invention. AETB materials are known in the art and include alumina boria silica (also known as alumina-boria-silica, aluminoborosilicate, and aluminoborosilicate) fibers, silica fibers, and alumina fibers. One known application of AETB is as exterior tiles on aerospace vehicles, which are ideal for returning aerospace vehicles to the atmosphere. AETB has never been used as a filter substrate or catalytic converter substrate.

The inventors of the present invention have realised that the attributes that make AETB suitable for the aerospace industry are also preferred in combustion technology. AETB has the properties of high melting point, low thermal conductivity, low coefficient of thermal expansion, resistance to thermal and vibrational shock, low density, and very high porosity and permeability. Such a combination of desirable attributes is currently lacking in filtration and catalytic converter substrates.

It has also been discovered that nSiRF-C composites such as AETB and similar suitable substrates can be prepared, shaped, molded, cut, and/or molded (or otherwise physically modified) into new forms suitable for use as substrates for particulate filters and catalytic converters.

The present invention has a number of advantages over the prior art. First, the present invention will result in improved air quality and respiratory health. The invention can obviously reduce the possibility of carbon monoxide poisoning.

Embodiments of the invention can be used as catalytic and filtration substrates in current use, as well as direct substitutes for catalytic converters and particulate filters, exhaust and engine systems. As described in detail below, the substrates of the present invention provide a number of advantages over prior art substrates and solve a number of problems not yet solved by prior art substrates. This translates into significant cost savings for the manufacturer. Because the present invention can be used as a direct substitute for current technology, there is no need to redesign the exhaust system. Thus, enhanced filtration and purification of exhaust gas can be achieved without the need for re-staging the production plant and line and with little time investment.

The improved catalytic and filtration characteristics of the present invention may in certain embodiments require the use of less catalyst. This advantage also results in cost savings, since the catalysts used in the relevant applications are mostly expensive.

The preferred thermal attributes of some embodiments of the present invention reduce and/or eliminate the need for certain components of the exhaust system that are involved in the heat accumulation associated with current catalytic converters and particulate filters. Heat shields and thermal insulation may not be required in some embodiments of the present invention. Eliminating these components from the exhaust system and vehicle reduces costs both directly (no components are used, resulting in lower production costs) and indirectly (reduced vehicle weight, resulting in lower combustion costs). Other benefits may include better performance, better mileage, and/or better power.

In certain embodiments, a conventional catalytic converter or particulate filter may be replaced with a smaller catalytic converter or particulate filter of the present invention that has the same or better efficiency in removing contaminants. Catalytic converters or particulate filters are smaller and the space available on board for other uses is larger. Moreover, because the filter or converter of the present invention is smaller, the overall weight of the vehicle is reduced.

Another aspect of some embodiments of the invention is a catalytic substrate suitable for use in a catalytic converter located in whole or in part at the front end of an engine. The catalytic converter (referred to herein as a front-end catalytic converter) has a number of advantages over the prior art. For example, such front-end catalytic converters have traditionally been impractical due to the limitations of currently available catalytic substrates. The commonly used substrate cordierite will absorb too much heat. Because of the preferred thermal characteristics of the substrate of the present invention, a front end catalytic converter comprising the substrate will reduce thermal stress of the turbine on the turbocharger and/or intercooler (if present).

The front-end catalytic converter also does not require additional external hardware such as heat shields. The use of a front end catalytic converter can maintain a preferred appearance of the engine and products such as in a motorcycle. In certain embodiments, the use of a front end catalytic converter also reduces external discoloration of exhaust systems such as mufflers and manifolds. Many additional advantages of the front-end catalytic converter in certain embodiments include one or more of the following: the safety is improved; filtering out particles that would otherwise accumulate in the intercooler, thereby improving intercooler life and saving cost; in some embodiments, no underlayer is required; the use of a front end catalytic converter may reduce or eliminate rattle in the heat shield; and the front-end catalytic converter can be reduced in size of the necessary muffler.

In other embodiments of the front end catalytic converter, smaller particulate matter is more efficiently burned off. In the event of a failure of the front-end catalytic converter, only one small catalytic converter needs to be replaced. The front end catalytic converter also provides these advantages to boats, ships, motorcycles, fallen leaf blowers, and the like.

Furthermore, various embodiments of the present invention provide one or more of the following advantages over the prior art: the appearance is improved; avoiding the use of additional hardware; the invention does not require additional hardware (as may be required due to more stringent management); discoloration of the muffler and exhaust pipe due to exothermic chemical reactions is reduced or eliminated. The present invention may in certain embodiments allow for smaller substrates and thus smaller mufflers or tanks in certain systems. The substrate of the present invention provides greater safety for systems using catalytic converters or particulate filters because the substrate of the present invention has improved thermal properties and does not absorb as much heat as some conventional substrates. Moreover, the substrates of the present invention cool more rapidly than many conventional substrates, resulting in improved safety. Certain embodiments of the present invention provide improved resistance to temperature variability, thereby not cracking, breaking, or failing as severely as some conventional substrates in the presence of sudden temperature changes. In certain embodiments, the substrate is easier to manufacture than conventional substrates (e.g., an nSiRF-C wall flow substrate can be manufactured from one piece of material without clogging the channels). This attribute saves not only time but also money.

In other embodiments, nSiRF-C is lighter in weight than conventional aftertreatment devices. This property is not only important for automobiles, but also is critical in markets where weight is a factor (e.g., small engines, motorcycles, private boats, performance cars).

In certain embodiments, the substrates of the present invention exhibit less backpressure than competing post-treatment devices. Lower backpressure may result in improved vehicle performance, increased power, and improved fuel economy.

Other embodiments of the invention relate, for example, to methods of catalyzing reactions, methods of filtering fluids, methods of preparing catalytic substrates, methods of preparing filtration substrates, substrates prepared according to the methods, and the like, as described in detail below.

Drawings

Fig. 1 is a cross-sectional view of a conventional cordierite substrate having a honeycomb structure. A honeycomb configuration 102 is formed within the cordierite filter element 100. The honeycomb structure 102 is formed by an extrusion process in which long channels (or tubes) are formed with their major axes parallel to the extrusion. The openings of these channels face the incoming exhaust gas flow. As the effluent enters the channel, particles will deposit along the inner membrane of the tube.

Fig. 2a and 2b show micrographs of cordierite samples. In FIG. 2b, spheres 210 represent PM-10 sized particles and spheres 225 represent PM-2.5 sized particles.

Fig. 3 is a photomicrograph of cordierite 205 with spheres 210 representing PM10 particles and second spheres 225 representing PM2.5 particles.

FIG. 4a is a longitudinal cross-sectional view of a schematic of an exemplary catalytic converter. Catalytic converter 400 includes a reduction catalyst 402 and an oxidation catalyst 404. As the exhaust stream 406 enters the catalytic converter 400, the exhaust stream 406 is filtered and exposed to the reduction catalyst 402 and then to the oxidation catalyst 404. The exhaust stream 406 is then treated over an oxidation catalyst 404 to further combust the unburned hydrocarbons and carbon monoxide.

Fig. 4b shows a schematic view of a catalytic converter.

FIG. 5 is a schematic cross-sectional view of three substrates having three different front surface shapes.

FIG. 6 is a schematic illustration of an example flow-through configuration of a catalytic or filtration substrate. The substrate has a plurality of channels 610 formed by channel walls 620. Fluid flow 630 enters the front surface and exits the back surface through channel 610.

FIG. 7 is an example schematic of a wall flow configuration of a catalytic or filtration substrate. The wall flow pattern consists of the same matrix material 720 and channels 710 except that the channels 710 are not fully in communication with the other end. The channels 710 are formed as blind holes, leaving an undrilled portion 740 of the substrate 720 at the end of the channels 710. The fluid stream 730 passes through the channel walls 720 before exiting the substrate from the back surface. A particular advantage of the present invention is that the wall-flow type liquid flow 730 has substantially the same characteristics as the flow-through type.

FIG. 8 is a schematic illustration of an example wall flow configuration of a catalytic or filtration substrate. In this case, the fluid stream 830 enters the substrate from the front surface. Some of the fluid exits the substrate from the back surface through the non-drilled portions 845.

Fig. 9 is an end view of an embodiment of a substrate 900 employing wall flow channels. Alternate channels have non-drilled portions 920 at the inlet or outlet. The drilled channels 910 alternate with the undrilled portions 920 of the channels drilled from opposite sides. As a result, the substrate appears to have "checkerboard" type channels.

10a-10d show a comparison of the front surface areas 1020, 1021, 1022, 1023 and a comparison of the number of holes 1010, 1011, 1012, 1013. Comparing fig. 10a and 10c, each embodiment has the same pore density, i.e. number of channels or pores. But the front surface area of fig. 10c is much higher. It is desirable to minimize the frontal surface area so that structural integrity is maintained. A similar comparison can be made between the embodiments of fig. 10b and 10 d. With respect to FIGS. 10a-10d, the embodiment of FIG. 10b has a preferred construction; the pore density is maximized and the face surface area minimized.

Figure 11 shows an embodiment of a square channel to scale. In this embodiment, the ratio of apertures 1110 to aperture walls 1120 is 31.83: 1.5, or about 20: 1.

Fig. 12 illustrates an embodiment of a substrate 1210 having an exemplary pore to pore wall ratio shown to scale. The substrate 1210 was 4 square inches long by wide and comprised four 1/8 inch by 1/8 inch squares 1220, 1221, 1222, 1223. Each of the four squares 1220, 1221, 1222, 1223 is drilled to have a hole density of 900, with a hole density of 3600 for the total substrate. The wall thickness was 1.5 mils from hole to hole. The spacing between each square 1220, 1221, 1222, 1223 on the substrate 1210 is 7/8 inches, and the squares 1220, 1221, 1222, 1223 are all about 7/16 inches from the nearest edge of the substrate 1210.

Fig. 13a-c show several embodiments of channel structures. Fig. 13a-13c show hexagonal channels 1310, triangular channels 1320, and square channels 1330, respectively. Both of these embodiments successfully practice the present invention because the walls 1315, 1325, 1335 of the channels 1310, 1320, 1330 are substantially parallel to each other.

Fig. 14 shows an embodiment of the present invention. This microscopic view shows the substantially similar dimensions of the rectangular channels 1410, 1411, 1412, 1413 in the substrates 1415, 1416, 1417. Fig. 14c and 14d illustrate fibers 1420, 1421 present in the material. These fibers exhibit porosity that is superior to cordierite platelets in conventional systems.

FIG. 15 is a two-dimensional view of a comb 1500 that can be used in a carding process for preparing a catalytic or filtration substrate of the invention.

Fig. 16 shows various views of a comb 1600 (or a portion thereof) that may be used in some embodiments of the present invention. Figure 16 also provides typical physical dimensions (in inches) of comb 1600.

Fig. 17 is a schematic illustration of surface area enhancements and inlet and outlet tubes that can be formed in a filter element according to embodiments of the present invention. FIG. 17 provides a fluid flow 1704 from the front surface into the channel opening 1702. The fluid exits the back surface of the substrate on the right hand side 1704. The substrate shown in fig. 17 illustrates a substrate having a wall flow configuration in which the channel size gradually decreases as the channel extends through the substrate from the channel opening to the channel end.

FIG. 18 is a longitudinal view (photograph) of an embodiment of a substrate of the present invention. A filter substrate 1800 of the present invention is shown. The outer wall 1802 of the substrate 1800 has a hard coating 1804 thereon. For the sample shown in fig. 18, the hard coating layer consisted of finely divided cordierite and inorganic fibers. The powder is also coated onto the filter substrate 1800 and cured as described herein. The hard coating protects and isolates the filter substrate without changing dimensions.

FIG. 19 is a graphical representation of residence time required to combust particulate matter at different temperatures. Providing the residence time required to burn or burn off the particulate matter (soot material) at various temperatures. It can be seen that the residence time for burning or burning off the soot mass with the initial 0.9 soot mass at 600K is much longer than the residence time at 1200K.

Fig. 20 shows an exhaust substrate system 2000 comprising a substrate 2002 combined with a wire mesh heating element 2004. The substrate 2002 and wire mesh heating elements 2004 are inserted into the exhaust tube 2006 at an angle relative to the exhaust flow. Because the angles cause the wire mesh heating elements 2004 to be positioned behind and below the substrate 2002, the substrate 2002 can be heated more efficiently and uniformly using known principles of heat rise. As previously described, the more uniform and efficient heating allows the substrate 2002 to more completely burn or flash off particles, making the exhaust cleaner.

Fig. 21 is an elevation view of the filter element 2102 and wire mesh heating element 2104 depicted and discussed in relation to fig. 9. It can be seen that the filter element 2102 and the wire mesh heating element 2104 are oval shaped to fit within the tube at an angle. The shape of the exhaust tube, the shape of the filter element 2102, the type and angle of the heating element 2104 can be varied to suit the requirements and limitations of the intended exhaust system application.

Figure 22a is a photomicrograph of a substrate of the invention (specifically AETB).

Figure 22b is a photomicrograph of a substrate of the invention (specifically AETB). Fibers 2205 are visible. Sphere 2210 represents a PM-10 sized particle and sphere 2225 represents a PM-2.5 sized particle.

FIG. 23 is a graph showing the pressure drop (Δ P) of seven test materials as the hourly space velocity (hr) of gas^-1) Graph of the function of (1): corning 200/12 DPT 932F (2340); AETB-11(2310) at 600cpsi, 6mil wall thickness and 11lb/ft, 1100F; 600cpsi, 6mil wall thickness and 11lb/ft³、932F, AETB-11 (2320); 600cpsi, 6mil wall thickness and 11lb/ft³AETB-11(2330) by 662F; 1100F cordierite (2350); 932F cordierite (2360); and 662F cordierite (2370).

FIG. 24 is a graph of% failure versus temperature. The inventive substrate 2410 exhibits a greater rate of material failure at lower temperatures than cordierite substrate 2420.

FIG. 25 is a cross-sectional view of an embodiment of the improved catalytic converter of the present invention. In this embodiment, the catalytic converter includes a durable and heat resistant tube 2502. Tube 2502 has an inlet 2504 and an exhaust outlet 2506. The modified substrate 2510 has one or more zones 2512, 2514. The modified substrate 2510 is encased or encapsulated in one or more underlayment/insulation layers 2515. A cushion layer 2515 may be applied over the filter substrate 2510 to protect the substrate 2510 from vibrational shock from the engine and moving environment, as well as to insulate the external environment from the internal heat temperatures of the filter substrate 2510.

FIG. 26 is a schematic illustration of a catalytic converter or particulate filter 2600 having four substrates 2601a, 2601b, 2601c, and 2601d arranged in parallel. The filter or converter has a front opening 2604 and a rear outlet 2605.

Fig. 27a-c illustrate a catalytic converter or particulate filter 2700 having a substrate 2710 in the form of a laminated film. The inlet 2720 and outlet 2730 are designed at different heights. Fig. 27b and 27c show an alternative embodiment.

Detailed Description

Overview

In certain embodiments, the present invention relates to catalytic substrates suitable for use in a number of applications, including as substrates in catalytic converters. Another aspect of the present invention relates to filtration substrates suitable for use in a number of applications, including as substrates in particulate filters, such as Diesel Particulate Filters (DPFs) or Diesel Particulate Traps (DPTs). The present invention also provides an improved substrate for removing and/or eliminating pollutants from the exhaust gas of a combustion engine. In certain embodiments, the catalytic and filtration substrates provide improvements in the removal of pollutants from exhaust gases. Such improvements include, but are not limited to, one or more of the following: shorter light-off periods, increased depth filtration of PM, reduced backpressure, decreased clogging probability, increased ability to be placed at multiple locations within the exhaust system, including the manifold or exhaust head itself, high probability of catalytic reactions, high conversion of NOx, HC, and CO, faster burning off of PM, minimized usage of catalyst materials, and reduced weight of the aftertreatment exhaust system, among other things.

Other embodiments of the invention include catalytic converters, particulate filters, diesel particulate traps, and the like. The invention also provides methods of making or manufacturing catalytic and filtration substrates, catalytic converters, particulate filters, catalytic mufflers, and exhaust systems. Other embodiments of the invention include a pre-catalytic converter, a post-catalytic converter, a front end catalytic converter, and a manifold catalytic converter, each of which includes a substrate of the invention. Further, in an alternative embodiment, the present invention is directed to a substrate prepared according to the methods described herein.

In another aspect, the invention includes a catalytic or filtration substrate that provides one or more of the following attributes: shorter ignition cycles, increased depth filtration of PM, reduced backpressure, reduced clogging probability, ability to be placed in multiple locations within the exhaust system including the manifold or exhaust head itself, higher probability of catalytic reactions, higher conversion of pollutants such as NOx, HC, and CO, faster burning off of PM, reduced amount of catalyst material required, faster ignition at cold start, lower outer wall temperature of the substrate, etc.

The use of the substrate, catalytic converter, particulate filter or exhaust system of the present invention provides a number of advantages and improvements over the prior art. In certain embodiments, these improved catalytic converters and/or particulate filters are capable of removing and/or eliminating pollutants from the exhaust of combustion engines, with a number of particular advantages, as described in more detail below. An improved exhaust system is also another aspect of the invention described herein. The improved exhaust system results in a reduction in the amount of pollutants emitted by an operating engine.

The invention is described in more detail below, including non-limiting embodiments and examples. The embodiments discussed herein are for illustration only. The present invention is not limited to these embodiments.

Catalytic substrate

The present invention relates to a catalytic substrate comprising (or alternatively consisting of or consisting essentially of) a non-woven sintered refractory fiber ceramic (nSiRF-C) composite material as described herein, which can be used in catalytic converters, particulate filters, and related devices; optionally also including an effective amount of a catalyst such as a catalytic metal. Preferably the catalytic substrate comprises a catalyst. The nSiRF-C composite can be fabricated into configurations suitable for the uses described herein.

The nSiRF-C composite is non-woven. In certain embodiments, the nSiRF-C composite is a material having a defined rigid three-dimensional shape. The fibers of the nSiRF-C composite are not arranged in an organized pattern, but are arranged three-dimensionally in a random, accidental, or omnidirectional manner. In certain embodiments, the nSiRF-C is in the form of a matrix.

nSiRF-C is a sintered composite material. In one embodiment, the sintered composite material is a coherent mass formed by heating without melting. Methods of sintering ceramic materials are well known in the art and, thus, the scope of the present invention is not necessarily limited to the specific embodiments and descriptions set forth herein. Sintering forms a coherent body without resin residue. According to the present invention, the sintered ceramic is a bonded substance in which the formed dispersed fibers are heated without melting.

nSiRF-C is a refractory fiber ceramic composite. Certain embodiments of the nSiRF-C are composed of advanced refractory fibers of varying lengths and compositions, as exemplified in non-limiting embodiments herein.

In one embodiment, the present invention relates to a catalytic substrate suitable for many of the applications described herein. Such substrates include a wide variety of materials having one or more properties, preferably having a variety of properties as described herein. The substrate of the present invention is made of a non-woven fiber ceramic composite made of refractory grade fibers. Such materials are disclosed in US4,148,962, the entire contents of which are incorporated herein by reference. Other suitable materials are disclosed in US 3,953,083.

In one embodiment, the catalytic substrate of the present invention comprises (or alternatively consists of or consists essentially of) an alumina enhanced thermal barrier ("AETB") material or similar material known to those of ordinary skill in the art. AETB materials are known in the art and are more fully described in Leiser et al, "Options for Improving structured Ceramic heights", Ceramic engineering and Science Proceedings, 6, No.7-8, pp.757-768(1985), and Leiser et al, "efficiency of Fiber Size and Composition on Mechanical and technical Properties of Low Density Ceramic Composition instruments", NASA CP 7, pp.231-244(1984), both of which are incorporated herein by reference.

In another embodiment, the catalytic substrate comprises a tile, such as an alumina-enhanced thermal barrier (AETB) with a toughened monolithic fiber insulation (TUFI) and/or Reaction Cured Glass (RCG) coating. Such materials are known in the art.

Another suitable material is Fibrous Refractory Ceramic Insulation (FRCI). In one embodiment, AETB is made from alumina boria silica (also known as alumina-boria-silica, aluminoborosilicate, and aluminoborosilicate) fibers, silica fibers, and alumina fibers. One known application of AETB is as exterior tiles on aerospace vehicles, which are ideal for returning aerospace vehicles to the atmosphere. AETB has the properties of high melting point, low thermal conductivity, low coefficient of thermal expansion, resistance to thermal and vibrational shock, low density, and very high porosity and permeability. Thus, in a preferred embodiment, the catalytic substrate has a high melting point, low thermal conductivity, a low thermal expansion system, resistance to thermal and vibrational shock, low density, high porosity, and high permeability.

In one embodiment, the first component of AETB is alumina fiber. In a preferred embodiment of the present invention, alumina (Al)₂O₃Or alumina, such as SAFFIL) is typically in the commercially available form of about 95 to about 97 weight percent alumina and about 3 to about 5 weight percent silica. In other embodiments, lower purity alumina is also suitable, such as 90%, 92%, and 94%. In other embodiments, higher purity alumina is also suitable. The alumina may be produced by extrusion or by wire drawing. First, a precursor solution is prepared. A slow and gradual polymerization process is initiated, for example by controlling the pH, so that individual precursor molecules combine to form larger molecules. As this process progresses, the average molecular weight/size increases, resulting in an increase in solution viscosity over time. At a viscosity of about 10 centipoise, the solution becomes slightly tacky and the fiber can be drawn or spun. In this state, the fiber can also be extruded through the die. In certain embodiments, the average fiber diameter is in the range of about 1 to about 6 microns, although larger and smaller diameter fibers are also suitable for use in the present invention. Example (b)For example, in other embodiments the fiber diameter is in the range of 1 to 50 microns, preferably 1 to 25 microns, more preferably 1 to 10 microns.

In one embodiment, the second component of AETB is silica fiber. In certain embodiments, Silica (SiO)₂E.g., Q-fibers or quartz fibers) contain more than 99.5 wt.% amorphous silica and the impurity content is very low. Lower purityDegrees of silica (e.g., 90%, 95%, and 97%) are also suitable for use in the present invention. In certain embodiments, amorphous silica is used, which has a low density (e.g., 2.1 to 2.2 g/cm)³) High heat resistance (1600 ℃), low thermal conductivity (about 0.1W/m-K), and near-zero thermal expansion.

In one embodiment, the third component of AETB is alumina boria silica fiber. In some cases, alumina boria silica fibers (3 Al)₂O₃·2SiO₂·B₂O₃E.g., NEXTEL 312) is typically 62.5 wt.% alumina, 24.5 wt.% silica, and 13 wt.% boria. Of course, the exact percentage of the composition of the alumina boria silica may vary. It is predominantly an amorphous product but may contain crystalline mullite. Suitable alumina boria silica fibers and methods for making them are disclosed, for example, in US 3,795,524, the teachings of which are incorporated herein by reference in their entirety.

Another material suitable for use as a substrate in the present invention includes Orbital ceramic thermal barrier material (OCTB) available from Orbital ceramic (Valencia, CA).

Other suitable materials for use as nSiRF-C in the present invention include AETB-12 (which has a composition of about 20% Al)₂O₃About 12% (14% B)₂O₃、72％Al₂O₃、14％SiO₂；NEXTEL^TMFibers), and about 68% SiO₂) (ii) a AETB-8 (composition about 20% Al)₂O₃About 12% (14% B)₂O₃、72％Al₂O₃、14％SiO₂ NEXTEL^TMFiber), 68% SiO₂) (ii) a FRCI-12 (composition of which is about 78 wt.% silicon dioxide (SiO)₂) And 22 wt.% aluminoborosilicate (62% Al)₂O₃、24％SiO₂、14％B₂O₃) ); and FRCI-20 (which has a composition of about 78 wt.% silicon dioxide (SiO)₂) And about 22 wt.% aluminoborosilicate (62% Al)₂O₃、24％SiO₂、14％B₂O₃))。

In a preferred embodiment, the inorganic fiber component consists of or consists essentially of fibrous silica, alumina fibers, and aluminoborosilicate fibers. In this embodiment, the fibrous silica comprises about 50-90% of the inorganic fiber mixture, the alumina fibers comprise about 5-50% of the inorganic fibers, and the aluminoborosilicate fibers comprise about 10-25% of the inorganic fiber mixture. In certain embodiments, the fibers used to make the substrates of the present invention may have both a crystalline phase and a glassy phase.

Other suitable fibers include aluminoborosilicate fibers preferably comprising alumina in the range of about 55 wt% to about 75 wt%, silica in the range of less than about 45 wt% to greater than 0 wt% (preferably less than 44 wt% to greater than 0 wt%), and boria in the range of less than 25 wt% to greater than 0 wt% (preferably about 1 wt% to about 5 wt%), each based on Al₂O₃、SiO₂And B₂O₃Theoretical oxide calculation of). The aluminoborosilicate fibers are preferably at least 50% crystalline by weight, more preferably at least 75% by weight, most preferably about 100% by weight (i.e., crystalline fibers). Size-graded aluminoborosilicate fibers are commercially available, for example, from 3M Company under the trade designations "NEXTEL 312" and "NEXTEL 440". Further, suitable aluminoborosilicate fibers may be prepared as disclosed in US 3,795,524, which is incorporated herein by reference in its entirety.

Other suitable fibers include aluminosilicate fibers, typically crystalline, comprising alumina in the range of about 67 wt% to about 77 wt% (e.g., 69 wt%, 71 wt%, 73 wt%, and 75 wt%) and silica in the range of about 33 wt% to about 23 wt% (e.g., 31 wt%, 29 wt%, 27 wt%, and 25 wt%). Size-graded aluminosilicate fibers are commercially available, for example from the 3M Company under the trade designation "NEXTEL 550". Further, suitable aluminosilicate fibers may be prepared as disclosed in US4,047,965 (Karst et al), the disclosure of which is incorporated herein by reference.

In other embodiments, the fibers used to prepare the substrates of the present invention include the addition of Y₂O₃And ZrO₂α -Al of₂O₃And/or adding SiO₂α -Al of₂O₃(formation of α -Al)₂O₃Mullite).

The catalytic substrate can be prepared from a wide variety of specific materials. In one embodiment, the material from which the substrate of the present invention is made comprises (or alternatively consists of or consists essentially of) refractory silica fibers and refractory alumino-borosilicate fibers. In another embodiment, the material used to make the catalytic substrate comprises refractory silica fibers, refractory grade alumina fibers, and a binder, preferably boron oxide or boron nitride powder. In another embodiment, the fibers are high grade.

In another embodiment, the substrate comprises a refractory composite consisting essentially of aluminosilicate fibers and silica fibers in a weight ratio in a range from about 19: 1 to 1: 19; and about 0.5% to 30% boron oxide, based on the total weight of the fiber. Alternatively, the weight ratio of aluminosilicate fibers to silica fibers is selected from 16: 1, 14: 1, 12: 1, 10: 1, 8: 1, 6: 1, 4: 1, 2: 1, 1: 2, 1: 4, 1: 6, 1: 8, 1: 10, 1: 12, 1: 14, and 1: 16. In other embodiments, the boron oxide is present in an amount of about 5%, 10%, 15%, 20%, 25%, or 30%. In another embodiment, the boron oxide and aluminosilicate fibers are present as aluminoborosilicate fibers. In another embodiment, the catalytic substrate comprises an nSiRF-C composite wherein the ratio of aluminosilicate fibers to silica fibers is in the range of 1: 9 to 2: 3 and the boron oxide content is about 1% to 6% by weight of the fibers.

In another embodiment, fibers suitable for use in making the substrates of the present invention include 3M-produced refractory fibers, such as NEXTEL^TM Ceramic Fiber 312、NEXTEL^TMCeramic Fiber 440、NEXTEL^TMCeramic Fiber 550、NEXTEL^TMCeramic Fiber 610, and NEXTEL^TMCeramic Fiber 720. Composite grade fibre Nextel^TMFibers 610, 650, and 720 are based on α -Al₂O₃Without any glassy phase. This allows it to maintain strength at higher temperatures. Nextel @^TMFiber 610 has substantially α -Al₂O₃The single phase composition of (1). Even when started at the highest strength at room temperature, the strength retention at elevated temperatureAnd is also the lowest. Nextel @^TMFiber 650 (which is added with Y)₂O₃And ZrO₂α -Al of₂O₃) And Nextel^TMFiber 720 (which is SiO added)₂α -Al of₂O₃(formation of α -Al)₂O₃Mullite)) has better strength retention at elevated temperatures and has less creep.

In another suitable embodiment, the nSiRF-C is made of or comprises (or alternatively consists of or consists essentially of) ceramic fibers comprising Al₂O₃、SiO₂And B₂O₃Having the following properties: 1) melting point of about 1600 ℃ to about 2000 ℃, preferably about 1800 ℃; 2) a density of from about 2g/cc to about 4g/cc, preferably from about 2.7g/cc to about 3 g/cc; 3) a refractive index of about 1.5 to about 1.8, more preferably selected from 1.56, 1.60, 1.61, 1.67 and 1.74; 4) monofilament tensile strength (25.4mm gauge) of from about 100MPa to about 3500MPa, more preferably from about 150 to about 200 or from about 2000 to about 3000, or from 150,190. 193, 2100 or 3100; 5) a thermal expansion (100-; and 6) a surface area of less than about 0.4m²A/g, more preferably less than about 0.2m²(ii) in terms of/g. In other embodiments, the crystalline phase of the fibers is mullite and amorphous, substantially amorphous, gamma-Al₂O₃Or amorphous SiO₂. In other embodiments, fibers suitable for use in preparing the substrate of the present invention have a dielectric constant of from about 5 to about 9 (at 9.375 GHz), or preferably selected from 5.2, 5.4, 5.6, 5.7, 5.8, 6, 7, 8, and 9.

In certain embodiments, the substrate of the present invention is substantially "free of hard particles," meaning free of particulate ceramic (i.e., crystalline ceramic, glass, or glass-ceramic) from the fiber manufacturing process.

In certain embodiments, the nSiRF-C composite is "rigid". In one embodiment, rigid means a substrate that cannot be bent any more at 1, 2,3, 4,5, 6, 7, 8,9, 10, 15, 20, or 25 degree angles (relative to the point of bending) without breaking, cracking, or permanently deforming or misshapen.

The diameter of the fibers used in different embodiments of the present invention may vary. In certain embodiments, the average diameter is from about 1 micron to about 50 microns, preferably from 1 micron to about 20 microns. In other embodiments, the average diameter is about 6, 7, 8,9, 10, 11, 12, 13, 14, or 15 microns. In other embodiments, the alumina boria silica fibers have an average fiber diameter of about 10 microns to about 12 microns.

In another embodiment, the catalytic substrate of the present invention further comprises a binder such as boron nitride. In another embodiment of the invention, when alumina boria silica is not used, boron nitride is added instead of alumina boria silica fibers. That is, in certain embodiments, the substrate comprises (consists of or consists essentially of or is made from) silica fibers, alumina fibers, and boron nitride in similar weight percentages as previously described. In another embodiment, the substrate comprises silica fibers, alumina fibers, and a boron binder. In certain embodiments, each of these may contain minor amounts of other materials such as organic binders, inorganic binders, and some fibrous or non-fibrous impurities. In other embodiments, the substrate is free of organic binders. Moreover, in other cases, the adhesives used to make nSiRF-C are physically altered during the manufacturing process, as is known in the art.

Other materials suitable for use in making the substrate of the present invention are disclosed in US 5,629,186, which describes a low density fused fiber ceramic composite made from amorphous silica and/or alumina fibers with 2-12% boron nitride by weight of the fibers. In another embodiment, a thickening agent is added. Suitable thickeners are known in the art.

In other embodiments, the ceramic fibers used to prepare the nSiRF-C have an average tensile strength greater than about 700MPa (100,000psi), preferably greater than about 1200MPa (200,000psi), more preferably greater than about 1800MPa (300,000psi), and most preferably greater than about 2100MPa (350,000 psi).

In another embodiment, a dispersant is added. Suitable dispersants are known in the art.

In other embodiments, the catalytic substrate is treated, altered, modified, and/or enhanced in one or more respects, as described herein and/or as known in the art.

In still other embodiments, trace impurities of various origins are present. In these cases, the impurities do not substantially affect nSiRF-C and/or its properties.

The substrates of the present invention do not comprise NEXTEL^TMA woven fabric or pad.

Catalyst and process for preparing same

In another aspect, the invention relates to a substrate as described above comprising a catalyst. A number of catalysts may be used with the substrate to form the catalytic substrate. The catalyst may be coated on the surface of the substrate. That is, in one embodiment, the catalyst is adsorbed on the surface (e.g., channel walls) of the catalytic substrate. The catalyst may also be present within the core of the substrate and attached to individual fibers of the substrate. In certain embodiments, the present invention may function as well or better than current technology while requiring a smaller amount of catalyst.

In another embodiment, the catalyst is deposited only on the surface of the channel walls and not on the interior of the channel walls. In another embodiment, the catalyst is deposited on the inlet channel walls, on the outlet channel walls, within the walls, or a combination thereof. In yet another embodiment, the first catalyst is embedded (line), coated or impregnated into the initial or adjacent portion of the channel wall; the second catalyst is embedded in, coated on, or permeated through the middle of the channel wall; and the third catalyst is at the end portions of the channel walls.

In one embodiment, the catalytic substrate of the present invention preferably contains a catalytic metal. In another embodiment, the catalytic substrate is free of catalytic metals. However, under certain conditions, the substrate is capable of catalyzing the appropriate reaction without the need for a separate catalytic metal, for example, in certain embodiments, the washcoat, as described below, may function as a catalyst.

Any catalyst that can be applied to a substrate can be used. Such catalysts include, but are not limited to, platinum, palladium (e.g., palladium oxide), rhodium, derivatives thereof including oxides, and mixtures thereof. In addition, the catalyst is not limited to noble goldMetal, noble metal combinations, or limited to oxidation catalysts. Other suitable catalysts include chromium, nickel, rhenium, ruthenium, silver, osmium, iridium, platinum, and gold, derivatives thereof, and mixtures thereof. Other suitable catalysts include palladium and double effect oxides of rare earth metals, as disclosed in US 5,378,142 and 5,102,639, the disclosures of which are incorporated herein by reference. These dual effect oxides may be produced by the solid state reaction of palladium oxide with rare earth metal oxides, e.g., Sm₄PdO₇、Nd₄PdO₇、Pr₄PdO₇Or La₄PdO₇. Other catalysts that may be used in the present invention include those disclosed in US6,090,744 (assigned to Mazda MotorCorporation). Other suitable catalysts include non-metal catalysts, organic catalysts, base metal catalysts, and noble metal catalysts.

Other suitable catalysts are disclosed in 6,692,712 (assigned to Johnson Matthey public Limited Company). Catalysts that do not contain noble metals may be used in the present invention. Such a catalyst is shown in US 5,182,249.

Another suitable platinum catalyst developed by Engelhard consists of Pt/Rh in a 5: 1 ratio (used in an amount of about 5-150 g/ft)³) And MgO (in an amount of about 30-1500 g/ft)³) And (4) forming.

In other embodiments, vanadium and its derivatives such as V₂O₅Are suitable catalysts, in particular for diesel particulate filters. The catalyst is commercially available and has been used in diesel particulate filters.

Has been developed to utilize V₂O₅Other vanadium compounds such as silver vanadate or copper vanadate. An example of a copper vanadate base metal catalyst was developed by Heraeus (Strutz 1989). The catalyst may be prepared by reacting copper vanadate Cu in a Cu: V: K molar ratio of about 3: 2: 0.13₃V₂O₈Doped with potassium carbonate and calcined. Catalyst loadings at 10 and 80g/m²Surface area of filtrationIn the meantime. Another suitable catalyst is Cu/ZSM5, which can be used as a DeNOx (DeNox) catalyst.

Noble metals such as platinum, palladium, and rhodium are the most common and preferred, but other catalysts known in the art may also be used. These three precious metals are known to be excellent and highly effective catalysts for internal combustion engine emissions. Over twenty-five years of catalytic converters, there has been no truly meaningful alternative to this triad. But thousands of combinations of these catalysts are deployed depending on original equipment manufacturers, vehicles, vehicle loads, environmental regulations, engines, transmissions, and the like. Throughout the truck and automobile industry, a wide variety of catalyst combinations and formulations are employed. The catalytic substrates of the present invention include any one or more of these catalyst combinations. Many combinations are considered proprietary materials. Manufacturers such as Ford, GM, and Toyota have unique catalyst formulations for each vehicle type because of the different vehicle weight and engine performance requirements. Manufacturers also have different catalyst formulations for the same vehicle depending on where the vehicle is sold or licensed, e.g., canada, usa, california, mexico. Currently, these formulations may change two to three times per model year per vehicle due to strict government regulations. For this reason, most manufacturers own the application of catalytic coatings.

In another embodiment, the catalytic substrate comprises nSiRF-C and a catalyst used in a commercially available catalytic environment.

In one aspect, when the substrate has been shaped to its final dimensions and the washcoat has been applied and cured, one or more catalysts, such as palladium-platinum based catalysts disclosed in U.S. Pat. Nos. 5,224,852 and 5,272,125, the teachings of which are incorporated herein by reference in their entirety, are applied using known techniques and methods.

In one embodiment, the amount of catalyst is sufficient to effectively catalyze the reaction. For example, in one embodiment, sufficient means that the amount of catalyst (e.g., noble metal) that interacts with the emissions in the exhaust path is sufficient to react with as much (e.g., 80%, 85%, 90%, 95%, 97%, 98%, 99%, etc.) of the emissions as possible.

In one embodiment, the catalyst is deposited on or impregnated into the washcoat, preferably in the form of individual crystals. In this embodiment, the catalyst is not applied as a top-coat type coating on top of the washcoat (like a wall coating). And when the catalyst is impregnated onto the washcoat, the catalyst is applied such that the final product is partially or substantially a crystalline mass of individual crystals. This can be thought of as salt crystals on a pretzel. It is preferable to have sufficient space between the catalysts. At the same time, there should be sufficient precious metal in the fluid path, e.g., exhaust path, to be at the optimum catalytically active operating temperature, i.e., ignition, and the precious metal must fit within the physical constraints, i.e., space, allowed by the vehicle and engine function and design.

The goal of production is to maximize the removal of contaminants while minimizing the amount of catalyst required on the substrate. The amount of contamination generated varies from vehicle to vehicle, and thus in certain embodiments the substrate is tailored to account for the amount of contamination and minimize the amount of precious metal.

In another embodiment, the catalyst may be added to the catalytic substrate during a slurry process when the substrate is prepared, or may be added to the catalytic substrate after the processing process (as described later). In this case, the catalyst is mixed with the fiber slurry prior to any heating step.

Single and multiple catalyst formulations can be used on a single substrate, or multiple substrates can be arranged due to the small size of the filter relative to existing catalytic converters and exhaust systems. Thus, in one embodiment, the catalytic substrate of the invention comprises or consists essentially of one or more zones, wherein each zone has a different catalyst. Alternatively, one or more of the zones may be uncatalyzed. For example, the catalytic substrate of the present invention may include an oxidation catalyst located in one region including the front surface of the substrate and a reduction catalyst located in another region including the back surface.

If the substrate is to be used in a flow-through configuration, it is preferred (but not required) that the catalyst or a substantial portion of the catalyst be present along the channel surfaces. If the substrate is processed into a wall-flow configuration, it is preferred that the catalyst be uniformly distributed throughout the substrate, as the gas will pass through all portions of the substrate rather than just the substrate.

For example, the substrates of the present invention may be used in Catalyzed Diesel Particulate Filters (CDPF). CDPF utilizes a catalyst deposited directly on a substrate. Both noble and base metal catalysts can be used, such as platinum, silver, copper, vanadium, iron, molybdenum, manganese, chromium, nickel, and their derivatives (e.g., oxides), and the like. Depending on the filter type, the catalyst may be impregnated directly into the media or an intermediate washcoat may be used. CDPF can be regenerated using exhaust temperatures of about 325-.

Platinum is one of the most active and most commonly used noble metal catalysts, but palladium, rhodium or ruthenium catalysts (usually mixtures) are also suitable for use in the present invention. Non-platinum group metals commonly used in catalytic converters include vanadium, magnesium, calcium, strontium, barium, copper and silver. In one embodiment, platinum is the preferred catalyst for use with diesel engines. In another embodiment, the palladium and rhodium are suitable for use with gasoline engines.

The catalyst is generally quite expensive. It is therefore desirable to achieve maximum pollution reduction with a minimum amount of catalyst. Both platinum and palladium (two commonly used catalysts) are very expensive noble metals. This object is achieved by a substrate which is porous and permeable and has a large surface area, wherein the catalyst can be present on the substrate in the form of homogeneously distributed crystals or layers. An advantage of the present invention is that the catalyst requirements are lower than for conventional substrates.

Typical platinum loading in filters for twenty-century ninety-year off-road engines is 35g/ft³And 50g/ft³In the meantime. These filters are installed on engines with high pollution and require a minimum temperature of approximately 400c for regeneration. Later, when the catalytic filter was used in the engine of much cleaner city buses and other road vehicles, it was found that the catalytic filter could be regenerated at much lower temperatures. But higher platinum loadings are required to support low temperature regeneration. The platinum loading for cleaning filters used in low temperature applications for engines is typically 50-75g/ft³。

In one embodiment, the catalytic substrate comprises about 1g/ft³To about 100g/ft³About 1g/ft³To about 50g/ft³About 1g/ft³To about 30g/ft³Or about 10g/ft³To about 40g/ft³The catalyst of (1).

In another embodiment, the catalytic substrate is preferably an nSiRF-C such as AETB, OCTB, and FRCI, comprising a ratio of about 5: 1 and a content of about 30g/ft³Platinum and rhodium catalysts.

Filter substrate

The present invention relates to a catalytic substrate comprising a non-woven sintered refractory fiber ceramic (nSiRF-C) composite material (as described herein) useful for particulate filters and related devices. The filter substrate is made in a particular shape, design, size and configuration suitable for filtration, particularly for filtering particulate matter. The filter substrate is particularly useful for filtering particulate matter under extreme conditions (temperature, pressure, etc.), such as filtering exhaust gas streams. The filter substrate can be used in other applications where small particles need to be filtered.

In one embodiment, the filtration substrate comprises (or alternatively consists of or consists essentially of) the nSiRF-C composite material described previously for the catalytic substrate. The filter substrate does not contain a catalyst. All variations, embodiments, and examples of materials suitable for use as substrates for catalytic substrates are equally applicable to the filter substrates of the present invention.

The filtration substrate is fabricated into a configuration suitable for the applications described herein, particularly for use in particulate traps such as diesel particulate traps and diesel particulate filters.

In one embodiment, the filter substrate of the present invention is an alumina enhanced thermal barrier ("AETB") material or similar material known to those of ordinary skill in the art. AETB is made from alumina boria silica (also known as alumina-boria-silica, aluminoborosilicate, and aluminoborosilicate) fibers, silica fibers, and alumina fibers. One known application of AETB is as exterior tiles on aerospace vehicles, which are ideal for returning aerospace vehicles to the atmosphere. Attributes that make AETB unique and highly desirable for the aerospace industry are also preferred in organic combustion technology. AETB has a high melting point, low thermal conductivity, low coefficient of thermal expansion, resistance to thermal and vibrational shock, low density, and very high porosity and permeability.

The filter substrate of the present invention is optionally treated with one or more chemical additives.

In another embodiment, the present invention relates to a diesel particulate trap comprising a filter as described herein without any catalyst applied thereto.

In another embodiment, the invention relates to a diesel particulate trap comprising a CRT^®Diesel particulate trap (NO)_XHC adsorber) in combination.

In another embodiment, the invention relates to a diesel particulate trap comprising a filter as described herein in combination with an SCR.

In another embodiment, the filter substrate comprises a plurality of channels, as described in more detail below. Moreover, the filtration substrate can be modified, altered, and/or enhanced in one or more aspects, as described herein and/or as known in the art.

Properties of the catalytic and Filter substrates

The present invention has one or more attributes, preferably at least three, four, five, six, seven, eight, nine, or ten attributes, that are superior to conventional catalytic or filtration substrates.

Is suitable for use

In certain embodiments, the present invention relates to a catalytic or filtration substrate comprising nSiRF-C and a catalyst, suitable for use in a catalytic converter. The substrate is suitable for use in a number of catalytic converters, filtration devices, and applications thereof.

For example, the catalytic and filtration substrates of the present invention are suitable for use in any application that is typically used in prior art substrates. Suitable uses include, but are not limited to, the use of the substrates of the present invention in any of the following exhaust systems: 1) mobile road engines, equipment and vehicles, including automobiles and light trucks; road and street motorcycles, motor tricycles (e.g., motor tricycles, autoichhaws), motor tricycles; heavy duty road engines such as trucks and buses; 2) mobile off-road engines, equipment and vehicles, including compression ignition engines (agricultural, construction, mining, etc.); small spark ignition engines (lawn mowers, leaf blowers, chain saws, etc.); large spark ignition engines (forklifts, generators, etc.); marine diesel engines (commercial ships, diesel engines for entertainment, etc.); marine spark ignition engines (boats, private ships, etc.); recreational vehicles (snowmobiles, off-road motorcycles, all-terrain vehicles, etc.); a locomotive; aerial vehicles (aircraft, ground support equipment, etc.); and 3) stationary sources, which include hundreds of sources, such as power plants, refineries, and manufacturing facilities.

In another embodiment, the catalytic substrate of the present invention is suitable for use in a particular vehicle if the substrate described herein (when part of a catalytic converter) functions to enable the vehicle to meet any of the emission standards defined by the EPA for the years 1990, 2007 and 2010.

In another embodiment, the catalytic substrate efficiently catalyzes the conversion of contaminants to non-contaminants. For example, the conversion of contaminants to non-contaminants is catalyzed with greater than 50% efficiency. In another embodiment, the conversion of contaminants to non-contaminants is catalyzed with an efficiency of greater than 60%. Yet another implementationIn embodiments, the conversion is selected from 70%, 80%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, and 99.9%. In certain embodiments, conversion means the total conversion of non-particulate contaminants. In another embodiment, conversion refers to the conversion of specific non-particulate pollutants, such as NOx to N₂CO to CO₂Or conversion of HCs to CO₂And H₂And O. In other embodiments, conversion means the percentage of particulate matter removed from the exhaust gas.

In another embodiment, the catalytic substrate of the present invention is suitable for a particular application if it passes certain OEM specified and preferred tests such as u.s.federal test protocol 75 (u.s.ftp75). These assays are known in the art. (see, e.g., U.S. EPA publication EPA420-R-92-009, available at http:// www.epa.gov/otaq/inventory/r92009.pdf, the contents of which are incorporated herein by reference in their entirety). In addition, the EPA and/or state/local agencies may have to approve these products for use as post catalytic converters or DPTs in retrofit applications, including substrates contained therein.

Surface area

The available surface area of the substrate is an important feature of a filtration substrate or a catalytic substrate. One of the characteristics of a substrate suitable for use in a catalytic converter is its high Geometric Surface Area (GSA). High GSA allows maximum reaction probability.

The large face open area (OFA) allows a greater amount of gas to pass through without impeding its flow and creating back pressure. The frontal open area (OFA) is defined as the portion of the total cross-sectional area of the substrate available for gas flow (i.e., the cross-sectional area of the filter inlet channel). Generally expressed in relation to the total cross-section of the substrate.

One attribute of the substrate of the present invention is its high surface area or high GSA. The surface area of the substrate is an important feature for catalytic applications. Surface area is the total amount of surface that exhaust emissions must traverse through the exhaust filter. The increased surface area translates into an increased area for chemical reactions and catalytic and thermal processes to occur between the contaminants, making the catalytic converter process faster and more efficient. Speed and efficiency can result in little to no plugging that can lead to exhaust system failure. Moreover, the increased surface area of the substrate of certain embodiments also includes increased filtration efficiency and/or capacity.

The geometric surface area is the total surface area of a cubic inch upon which the precious metal can be impregnated. Substrates with high total surface area are preferred. Certain embodiments of the present invention have a much higher geometric surface area of impregnable catalyst than conventional substrates such as cordierite and SiC.

The total wall volume is the total amount of wall volume present in a one cubic inch formed substrate. The total wall volume is calculated by multiplying the surface area of each wall by the respective wall thickness and then summing. Substrates with a low total wall volume are preferred. In certain embodiments, the total wall volume of the inventive substrate is less than conventional substrate materials such as cordierite and SiC.

In certain embodiments, the total wall volume of the catalytic substrate is from about 0.5 to about 0.1, from about 0.4 to about 0.2, or about 0.3in³/in³(cubic inches/cubic inch). In a preferred embodiment, the total wall volume of the substrate is from about 0.25 to about 0.25About 0.28, more preferably about 0.27, more preferably about 0.272in³/in³。

Because of the smaller total wall volume of the present invention in certain embodiments, the present invention requires a lower amount of catalyst, such as palladium, to achieve catalysis than similarly sized cordierite.

Porosity and permeability

The pore properties also affect the mechanical and thermal properties of the substrate. There may be a balance between porosity and mechanical strength: for some conventional substrates, the smaller pore size and lower porosity substrates are stronger than the higher porosity substrates. In some materials (Yuuki 2003), both the thermal properties-specific heat capacity and thermal conductivity may decrease as porosity increases.

The first wall flow monolith introduced late in the eighties of the twentieth century had channels with diameters as high as 35 μm. To maximize filtration efficiency, the channels are made smaller, typically in the range of 10-15 μm in channel diameter in filters used in the nineties of the twentieth century. In developing new materials, Filter manufacturers primarily consider The catalyst system used to distinguish its target pore Properties (Ogyu, K., et al, 2003), "Classification of Thin Wall SiC-DPF", SAE 2003-01-0377; Yuuki, K., et al, 2003, "The Effect of SiC Properties on The Performance of catalyst particle Filter (DPF)," SAE-2003-01-0383). Applications can be classified as follows:

non-catalyzed filters, such as those used in diesel additive regeneration systems: the main requirement is a high soot volume. Some conventional filters have a porosity of about 40-45% with pores between 10-20 μm.

Catalyzed filters, such as those in passive regeneration systems, require greater porosity and possibly larger pore sizes to be coated with increasingly complex catalyst systems (relative to simple catalysts typically having little or no washcoat material used in the nineties of the twentieth century). The substrate used is about 50g/dm³The loaded catalyst/washcoat system should have an acceptably low pressure loss after application. Some prior art filters have a porosity of about 45-in the range of 55%. It is also possible to use additional heaters.

Filter/NOx absorber devices such as DPNR systems or CRT (continuous regeneration trap) incorporating NOx storage/reduction systems require very high washcoat loadings, possibly above 100g/dm³. Some prior art substrates have a porosity of about 60% (65% porosity substrates have been reported and mechanical strength has become a major limitation in increasing porosity (Ichikawa, S. et al, 2003, "Material Development of High Porous SiC for catalyst dispersed particles Filters," SAE 2003-01-0380).

Another attribute of certain embodiments of the catalytic or filtration substrates of the present invention is their high porosity. In certain embodiments, the porosity of the substrate of the present invention is about 60%, 70%, 80%, or 90%. In other embodiments, the porosity of the substrate is about 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% (expressed as a percentage of void space relative to the solid substrate).

In one embodiment, the porosity of the exemplary embodiment of the present invention is about 97.26%. In contrast, cordierite is about 18-42%. In this embodiment, only about 2.74% of the material of the present invention impedes the flow of exhaust gas. This fine network of material effectively captures the particles and burns them out very efficiently. Since the particulates are trapped by depth filtration rather than just along the channel walls, significant PM accumulation does not occur at regeneration times longer than PM accumulation times. The high porosity translates into better and more efficient interaction of the contaminant with the surface of the catalytic or non-catalytic substrate. At the same time, the accumulated gas flow can be released laterally and in the intended gas flow direction.

Referring to fig. 22a and 22b, exemplary substrates 2200, 2205 of the present invention are shown. Substrates 2200, 2205 are about 97% porous. The substrates 2200, 2205 are more porous and less dense than the cordierite and silicon carbide samples of fig. 2a and 2b, respectively, in substantially the same proportions. In FIG. 22b, the particulate matter PM-102210 and PM-2.52225 are shown to scale. Particulate matter PM-102210 and PM-2.52225 can readily penetrate the fibers of the substrate 2205 as compared to the cordierite sample 205 exemplified in FIG. 2 b. Also, the density of the silicon carbide is about 30-50 times that of the substrate 2200, 2205 as compared to the silicon carbide 300 of fig. 3.

In certain embodiments of the invention, the higher the porosity, the greater the surface area and the lower the back pressure. As a result, the present invention more efficiently reduces NOx, oxidizes hydrocarbons and CO, and traps particulate matter.

Pore characteristics, including volume percent porosity, pore size distribution, structure, and interconnectivity, determine the ability of the monolithic structure to filter particles. Furthermore, if gas molecules can diffuse into the porous substrate, the probability of catalyzing the reaction increases significantly. The porosity characteristics and pore geometry also affect the liquid flow resistance and pressure drop of the overall structure. Certain properties required for high filtration efficiency (e.g., low porosity and small pore size) are contrary to those required for low pressure drop. The pressure drop and the high efficiency require good connectivity between holes and no closed-hole dead-end holes, etc. In another embodiment the substrate of the present invention provides high filtration efficiency and low pressure drop.

Emissivity and thermal conductivity

Another property of the substrates used in catalytic converters and particulate filters is emissivity. Emissivity is a tendency to radiate heat; the relative ease of irradiation, or rate at which irradiation occurs, in terms of heat radiation from the surface of the heated body.

The ideal substrate takes into account the temperature, which (1) achieves high conversion efficiency most quickly; (2) with minimal risk of thermal damage (e.g., due to thermal shock or due to high temperature melting/cracking of the substrate); (3) a minimum amount of auxiliary energy is used; and (4) inexpensive to produce. Increasing the temperature requires additional energy and is costly. In addition, a certain amount of energy is conducted, conducted away or guided away by thermal conductivity.

Emissivity is the ratio of reflection, with a value between 0 and 1, 1 being total reflection. Different substrates used in catalytic converters and particulate filters have different emissivity values. The high emissivity allows the catalytic substrate to minimize heat transfer out of the system, thereby heating the air inside the catalytic converter or particulate filter more quickly. Emissivity is a measure of the thermal reflectivity of a material, and high values are desirable.

In certain embodiments, the substrates of the present invention preferably have an emissivity of about 0.8 to 1.0. In another embodiment, the emissivity of the substrate of the present invention is about 0.82, 0.84, 0.86, 0.88, and 0.9. More suitable values for substrate emissivity in accordance with the invention include 0.81, 0.83, 0.85, 0.87 and 0.89. In other embodiments, the emissivity is about 0.9, 0.92, 0.94, 0.96, or 0.98. The thermal reflectivity allows the gaseous material within the pores to be heated more quickly because the substrate itself retains little heat. This results in faster ignition and little heating of the outer surface of the substrate.

The thermal conductivity of a material is the amount of heat transferred per unit area of a sheet per unit time with the opposite faces of the sheet at a temperature gradient of, for example, 1 degree difference per unit thickness. The unit of thermal conductivity is Watts per meter Kelvin (W/m-K). In a preferred embodiment, the substrates of the present invention have a low thermal conductivity. For example, in one embodiment, the thermal conductivity of the substrate of the present invention is less than about 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, or 0.9. In another embodiment, the thermal conductivity of the substrate of the present invention is less than about 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, or 0.09. In another embodiment, the thermal conductivity of the substrates of the present invention is from about 0.1 to about 0.01, from about 0.2 to about 0.02, from about 0.3 to about 0.03, from about 0.4 to about 0.04, from about 0.5 to about 0.05, from about 0.6 to about 0.06, from about 0.7 to about 0.07, from about 0.8 to about 0.08, or from about 0.9 to about 0.09. In another embodiment, the thermal conductivity of the present invention is about 0.0604W/m-K.

In contrast, cordierite samples ranged from about 1.3W/m-K to 1.8W/m-K. These results show that: as an example of a specific embodiment, if 1000 watts of thermal energy is lost from a given volume of cordierite material, only 33 watts are lost from the same volume of the inventive material. Thus, the thermal conductivity of the inventive material is 30 times that of cordierite.

In addition, in other embodiments, a method of making a substrate further comprises making a catalytic or filtration substrate further comprising a radiation-enhancing agent, the method comprising applying the radiation-enhancing agent to the substrate, preferably an nSiRF-C, more preferably AETB, OCTB, or FRCI material. Other preferred substrates include any of the specific substrates disclosed herein. In other embodiments, the catalytic substrate further comprises a radiation enhancer and a catalyst selected from the group consisting of palladium, platinum, rhodium, derivatives thereof, and mixtures thereof. Other physical and chemical modifications described herein may be used in these embodiments. Radiation enhancers are known in the art.

Thermal Properties

Substrates with low coefficients of thermal expansion can withstand rapid temperature changes without significant expansion or contraction. The appropriate coefficient of thermal expansion also allows the substrate to have the same rate of thermal expansion as the protective pad and can surrounding it.

It is also preferred that the substrate material be able to withstand a high temperature range so as not to melt the catalytic converter or particulate filter when the temperature rises to very high values, such as during accidental fuel combustion. In addition, if the substrate material is capable of withstanding high temperatures, a catalytic converter or filter may be placed closer to the engine.

Relevant properties include low thermal mass and heat capacity. Materials with low thermal mass and heat capacity waste less heat energy in the warming of the catalytic substrate. If the catalytic substrate heats up rapidly, more thermal energy is brought by the exhaust gas to trigger the catalyst components to light off.

Thermal conductivity is the ability of a material to conduct heat due to molecular motion. More specifically, thermal conductivity is also a measure of the amount of heat per unit area per unit thickness of sheet material per unit time at a 1 degree difference in temperature between opposite sides of the sheet. The more thermally conductive the material, the more energy is required to overcome the losses and reach the desired temperature. Preferably the material reflects heat rather than conducts heat. A lower thermal conductivity value is preferred so that more thermal energy is available to the pores and not lost by absorption by the substrate. The chemical nature of the different substances determines the level of thermal conductivity. Furthermore, the thermal conductivity of the filter medium is a major contributor to the efficiency of the exhaust emission filter, as temperature losses adversely affect reactivity. A low thermal conductivity is preferred because the generated thermal energy is more reflected back by the particles and remains in the pores. In other words, the lower the thermal conductivity, the lower the heat loss. Lower heat loss translates into lower energy and higher energy efficiency required to reach the temperature range required for catalytic conversion.

Specific heat is the amount of heat (calories) required to raise the temperature of 1 gram of material by 1 degree celsius. The substrate, which has a high specific heat, reflects ambient heat (e.g., from exhaust or auxiliary sources) back into the pores, where it is needed for combustion or catalytic reduction and oxidation processes. For example, under extreme conditions such as the north pole, the time required to heat a low specific heat filter and cool the hot filter is longer and the likelihood of external thermal damage increases. Lower specific heat is preferred because the operating temperature is faster and uses less energy.

In certain embodiments, the substrates of the present invention have a number of preferred thermal properties. The preferred material results in preferential heating of the air within the pores over the heating of the substrate. The substrates of the present invention preferably have a high melting point, which in certain embodiments is higher than conventional substrates. The high melting point is preferred in part because of the extreme temperatures to which the catalytic or filtration substrate is exposed.

In a preferred embodiment, the substrate of the present invention preferably has a high melting point. In one embodiment, the melting point is greater than about 1500F. In another embodiment, the melting point is greater than about 2000F. In another embodiment, the melting point is greater than about 2500F. In yet another embodiment, the substrate has a melting point of about 2000F to about 4000F. In yet another embodiment, the substrate has a melting point of about 3000F to about 4000F. Other suitable melting point ranges include about 3000 to about 3100, about 3100 to about 3200, about 3200 to about 3300, about 3300 to about 3400, about 3400 to about 3500, about 3500 to about 3600, about 3600 to about 3700, about 3700 to about 3800, about 3800 to about 3900, about 3900 to about 4000. In another preferred embodiment, the melting point of the substrate is about 3632F.

In one embodiment of the invention, the melting point of the substrate is about 3632F. For example, if the vehicle is below freezing temperature, a stream of 1500 ° f smoke will not cause the substrate to crack or break. Similarly, certain embodiments of the substrate do not overheat and crack. Some cordierite samples have melting points of about 1400 ℃.

The specific heat of an exemplary embodiment of the present invention is about 640J/kg-K (joules/kilogram-on). The cordierite specimens were approximately 750J/kg-K. Even though cordierite has a greater specific heat, the cordierite filter will have a greater mass to heat. The result is more thermal energy required to reach operating temperatures, making cordierite less efficient.

The multiple use temperature limit is the maximum temperature that a substance can withstand multiple times without substantial degradation. The higher the temperature at which the substrate can continue to function without microcracking or spalling, the less likely the substrate will fracture or crack over time. This in turn means that the substrate is more durable over a wider temperature range. Higher multiple use temperature limits are preferred. Multiple use temperature limits suitable for certain embodiments of the catalytic or filtration substrates of the present invention are selected from the group consisting of about 2000 ℃, 2100 ℃, 2200 ℃, 2300 ℃, 2400 ℃, 2500 ℃, 2600 ℃, 2700 ℃, 2800 ℃, 2900 ℃, 3000 ℃, and 3100 ℃.

The multiple use temperature limit of an exemplary embodiment of the present invention is 2980 ℃. The cordierite specimens were about 1400 ℃. This embodiment of the invention can withstand more than twice the temperature of cordierite before cracking. This enables the material to function in a wider range of vented environments.

The coefficient of thermal expansion is the ratio of the increment of the length (linear coefficient), area (surface), or volume of an object to the original length, area, or volume, respectively, at a given temperature increase (typically 0 to 1 ℃). The ratio of these three factors is about 1: 2: 3. When not explicitly indicated, volume expansion coefficients are generally meant. The less the substrate expands upon heating, the less likely the filter assembly will leak, crack, or fail. The thermal expansion is preferably low to ensure that the substrate retains its dimensions even when heated or cooled.

The coefficient of thermal expansion of the exemplary embodiment of the present invention is about 2.65 x 10^-6W/m-K (Watt/meter-Ke). Cordierite samples were approximately 2.5X 10^-6W/m-K to 3.0X 10^-6W/mK. The thermal expansion of the material of the present invention is less than 10 times that of cordierite.

The coefficient of thermal expansion of the substrate is preferably compatible with the coefficient of thermal expansion of any washcoat.

In one embodiment, the catalytic or filtration substrates of the present invention have improved resistance to damage from thermal or mechanical stress as compared to certain prior art substrates, such as cordierite; reduced risk of clogging with soot and/or dust; more tolerant of additive dust accumulation when used with fuel additive regeneration; and the efficiency of reducing the number of particles is good.

Density of

When considering a substrate to be used in a catalytic converter or a diesel particulate filter, it is preferable to use a substrate having a low density. The low density material provides a weight reduction to the substrate and thus a reduction in the overall weight of the vehicle. In addition, low density can complement porosity and high permeability.

Higher density translates into higher weight. Weight is an important factor inherent to any engine in operation. The heavier the component, the higher the energy required to move it. In order for these filters to accommodate the increased amount of particulates generated by the engine, the filter size must be increased, which in turn increases vehicle weight and manufacturing and operating costs. Therefore, lower density materials are desirable. Of course, the density should not be too low to provide adequate structural integrity.

Another attribute of the substrate of the present invention is its density. The density of the substrate is lower than that of certain conventional filters and substrates used for filtration and as catalytic substrates. Density is the ratio of the mass of a substance to its volume. Higher densities require more energy to reach operating temperatures. In other words, heating a dense material requires more energy than a less dense material. For a given volume, a higher density translates directly into a higher weight. Weight is detrimental to vehicle mileage and performance because the engine must work harder to move the heavier equipment. The increase in density also translates into more heat being required to reach a temperature suitable for catalytic activity or "light-off" to occur. Some materials currently used as substrates or filters have densities above optimal. For example, cordierite samples are about 2.0g/cm³To 2.1g/cm³. Thus, there is a need for lower density substrates and filters. The density of the substrate of the present invention is lower than that of cordierite.

In one embodiment, the catalytic substrate of the present invention preferably has a low density. The density of the substrate of the present invention may range from about 2 to about 50 pounds per cubic foot (lb/ft)³) Within the range of (1). In preferred embodiments, the density of the substrate is from about 5 to about 30 pounds per cubic foot, more preferablyPreferably in the range of about 8 to 16 pounds per cubic foot. Other preferred embodiments include a density of about 8,9, 10, 11, 12, 13, 14, 15, or 16lb/ft³The catalytic substrate of (1). A low density that still imparts structural integrity is preferred.

In one embodiment, the density of the substrate of the present invention is about 8lbs/ft³And 22lbs/ft³Preferably about 8lbs/ft³And 22lbs/ft³. In another embodiment, the substrate comprises AETB-8 or AETB-16, each having a density of about 8lbs/ft³And about 16lbs/ft³. Other suitable densities include those selected from about 9, 10, 11, 12, 13, 14, 15, and 16lbs/ft³The density of (c).

In another embodiment, the substrate has a density of about 0.10g/cm³To about0.25g/cm³(g/cc).

Structural integrity

The structural integrity of the substrate material is an important feature to consider. Structural integrity means the ability of a material to withstand vibration and mechanical stress, i.e., shaking and baking. For example, substrate strength is important for withstanding packaging loads and subsequent use in engine exhaust streams, and is related to various stresses including engine vibration, road shock, and temperature gradients. Robust catalytic converter systems and particulate filters require high strength substrates. The strength of the substrate material can be controlled by the type of intragranular and intergranular bonding, porosity, pore size distribution, and number of defects. In addition, the substrate may be reinforced by applying a chemical/material coating on the inside of the exterior. The strength of the porous structure of a substrate may also depend on its size, cross-sectional symmetry, and its pore properties such as pore density, channel geometry, and wall thickness. The strength of the substrate must exceed the stresses to which the material is subjected during packaging and handling. If the stress exceeds the strength, the substrate will crack.

The structural integrity of a material can be measured by the tensile modulus of the material. Tensile modulus is the resistance of a material to fracture. In particular, how much longitudinal stress the material can withstand without tearing into pieces. Tensile modulus is usually expressed in terms of pounds per square inch or kilograms per square centimeter required to produce a break, relative to unit cross-sectional area. The tensile modulus is related to whether the substrate can withstand the forces generated by the harsh exhaust stream pressures.

In addition, the substrate should have good coatability so that washcoats and/or catalytic coatings can be applied to the substrate. Similarly, the substrate should have compatibility with the washcoat so that the catalyst is well anchored to the substrate so that the catalyst does not shift its position during normal wear of the system. Good coatability and compatibility with washcoats also improve the long-term effectiveness of catalytic converter systems. Good coatability and compatibility with washcoats also extend catalyst life.

Another attribute of the substrate of the present invention is its structural integrity. The structural integrity of a material can be measured by the tensile modulus of the material. Tensile modulus is the resistance of a material to fracture. In particular, how much longitudinal stress the material can withstand without tearing into pieces. Tensile modulus is usually expressed in terms of pounds per square inch or kilograms per square centimeter required to produce a break, relative to unit cross-sectional area. The tensile modulus is related to whether the substrate can withstand the forces generated by the harsh exhaust stream pressures.

The catalytic substrates of the present invention preferably have a relatively high tensile modulus. For example, in one embodiment, the axial strength of the substrate of the present invention is about 2.21 MPa. Of course, higher axial strengths are also suitable. Other suitable values include 1, 2,3, 4,5, 6, 7, 8,9, and 10 MPa.

Furthermore, the structural integrity of the catalytic substrate of the present invention enables it to withstand the conditions encountered during its use in a commercial in-vehicle catalytic converter.

In another embodiment, the substrates of the present invention, such as nSiRF-C, preferably have high structural integrity and low density.

Contaminant reduction

The substrate plays an important role in enhancing the catalytic activity of the catalyst material coated thereon. The substrate also serves to trap particulate matter which is then burned off into a volatile gas.

Another advantage of the substrate of the present invention is its increased ability to reduce the amount of pollutants in the exhaust gas. The catalytic and filtration capabilities of the present invention are enhanced over certain conventional techniques.

In certain embodiments, the substrates of the present invention are capable of reducing CO emissions in exhaust gases by at least about 50%. In one embodiment, the substrate of the present invention is capable of reducing CO emissions in an exhaust gas by at least about 60%, 70%, 80%, or 90%. In another embodiment, the substrate is capable of reducing CO emissions by at least 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.5%, 99.9%, or 100%.

In certain embodiments, the substrates of the present invention are capable of reducing NOx emissions in exhaust gases by at least about 50%. In one embodiment, the substrate of the present invention is capable of reducing NOx emissions in an exhaust gas by at least about 60%, 70%, 80%, or 90%. In another embodiment, the substrate is capable of reducing NOx emissions by at least 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.5%, 99.9%, or 100%.

In certain embodiments, the substrates of the present invention are capable of reducing HC emissions in an exhaust gas by at least about 50%. In one embodiment, the substrates of the present invention are capable of reducing HC emissions in an exhaust gas by at least about 60%, 70%, 80%, or 90%. In another embodiment, the substrate is capable of reducing HC emissions by at least 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.5%, 99.9%, or 100%.

In other embodiments, the substrates of the present invention are capable of reducing VOC emissions in exhaust gases by at least about 50%. In one embodiment, the substrate of the present invention is capable of reducing VOC emissions in an exhaust gas by at least about 60%, 70%, 80%, or 90%. In another embodiment, the substrate is capable of reducing VOC emissions by at least 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.5%, 99.9%, or 100%.

In other embodiments, the substrates of the present invention are capable of reducing PM-10 emissions in an exhaust gas by at least about 50%. In one embodiment, the substrate of the present invention is capable of reducing PM-10 emissions in an exhaust gas by at least about 60%, 70%, 80%, or 90%. In another embodiment, the substrate is capable of reducing PM-10 emissions by at least 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.5%, 99.9%, or 100%.

In other embodiments, the substrates of the present invention are capable of reducing PM-2.5 emissions in an exhaust gas by at least about 50%. In one embodiment, the substrate of the present invention is capable of reducing PM-2.5 emissions in an exhaust gas by at least about 60%, 70%, 80%, or 90%. In another embodiment, the substrate is capable of reducing PM-2.5 emissions by at least 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.5%, 99.9%, or 100%.

Weight reduction

It is a goal of automotive manufacturers to reduce the overall weight of a vehicle to improve its fuel economy and engine efficiency. Heavy substrates add unnecessary weight to the vehicle. Furthermore, if the substrate is not effective enough to reduce contamination, more than one substrate may need to be placed to achieve the target contamination level. This greatly increases the overall vehicle weight.

Furthermore, current catalytic converters require the use of additional devices, which are often cumbersome. Some of these devices, such as heat shields and special mats, are used to cope with the temperature of the catalytic converter. Others such as oxygen sensors are required to comply with certain government regulations.

In certain embodiments of the invention, the weight of the catalytic substrate or filtration substrate is reduced from the weight of a conventional catalytic or filtration substrate. In part because the density of the substrates of the present invention is lower than that of some conventional substrates. Alternatively, the lighter weight may result from the improved filtration and catalytic functions of certain embodiments of the present invention over conventional techniques, resulting in a reduced need for catalytic or filtration substrates. There are many benefits to having a catalytic or filtration substrate that is lighter in weight. For example, lighter weight of the substrate translates into improved fuel efficiency of the vehicle. Moreover, the lighter weight also translates into a more easily handled and possibly safer hand-held engine assembly.

In a preferred embodiment, the outer surface of the substrate is not heated to the same extent as a conventional catalytic converter substrate during use. In certain embodiments, the need for heat shields and/or insulation is reduced.

Acoustic properties

Acoustic attenuation can be defined as a reduction in thickness, thinness, and thinness; the density is reduced; a decrease in force or strength; or acoustic energy (sound) attenuation. In one embodiment of the invention, acoustic attenuation is the ability of a substrate to attenuate or attenuate acoustic energy in the exhaust of an engine. The inventive substrate may replace or supplement the muffler components of an engine (as disclosed herein), thereby reducing exhaust noise and exhaust system cost. Higher acoustic attenuation is preferred.

In another embodiment, the porosity, density, and size of the substrate may be varied to "tune" the acoustic attenuation for the desired application.

In another embodiment, the acoustic attenuation of the substrate may be combined with standard metal muffler-based techniques to attenuate and/or "tune" the sound present in the exhaust system.

Type of flow

Flow-through type

In one aspect, the substrate is configured for a flow pattern. Flow-through configurations are known in the art. In one embodiment, the channels (or pores) are arranged substantially parallel to each other throughout the length of the substrate. The gas stream enters the substrate at one end, travels through the entire length of the substrate along the channel and exits at the other end.

Many flow-through configurations are suitable and suitable for the catalytic substrates of the present invention. Flow-through configurations known in the art may be applied to the catalytic substrate of the present invention.

In one embodiment, the flow-through configuration comprises a plurality of substantially parallel channels extending completely through the length of the substrate.

In another embodiment, the channel walls are not parallel to the sides or surfaces of the substrate.

Wall flow pattern

Another embodiment of the present invention is a catalytic substrate or filtration substrate of the present invention configured in a wall flow configuration. It has been surprisingly determined that catalytic substrates comprising the nSiRF-C of the invention can be configured in a wall flow configuration.

In another aspect of the invention, the substrate has a wall flow configuration. For example, the substrate is used in a wall-flow catalytic converter or a wall-flow particulate filter. The wall flow configuration may take any of a number of physical arrangements. Substrates having a wall flow configuration may have one or more of the attributes described herein. Moreover, the substrate having a wall flow configuration may further comprise one or more of: catalysts, washcoats, oxygen storage oxides, and radiation enhancers. In addition, substrates comprised of wall flow configurations may be further modified, enhanced or altered as described herein.

In one embodiment, the channel wall thickness is any of the following values. Preferred channel wall thicknesses range from about 2 mils to about 6 mils. In other embodiments, the channel wall thickness ranges from about 10 mils to about 17 mils. Other suitable values include 2,3, 4,5, 6, 7, 8,9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, and 20 mils.

In other embodiments of the wall flow substrate, the substrate has a cell density of about 400cpsi (cells per square inch) and a wall thickness of about 6 mils, or a cell density of about 900cpsi and a channel wall thickness of about 2 mils. Other embodiments include those having a cell density of about 50, 100, 150, 200, 250, 300, or 350 cpsi.

Wall flow ceramic monolith structures derived from flow-through porous supports for catalytic converters are the most common type of diesel filter substrate. They are distinguished from other diesel filter designs by high surface area per unit volume and high filtration efficiency. Monolithic diesel filters are made up of a number of small parallel channels, usually of square cross-section, running axially through the component. The diesel filter monolith is obtained from a flow-through monolith by plugging the channels. Alternately plugging adjacent channels at each end forces the diesel smoke through the porous substrate walls which act as a mechanical filter. To reflect this flow pattern, the substrate is referred to as a wall-flow monolith structure. The most common of the cylindrical types is a wall flow monolith, but oval cross-section components can also be used in space-limited applications.

The wall flow filter walls have a fine distribution of pores, which must be controlled during manufacture. The filtration mechanism of a monolithic wall-flow filter is a combination of cake and depth filtration. Depth filtration on clean filters is the primary mechanism because particles are deposited within the pore interior. As the soot loading increases, a particulate layer forms on the inlet channel walls and cake filtration becomes the primary mechanism. Some conventional monolith filters have a filtration efficiency of about 70% of Total Particulate Matter (TPM). Higher efficiencies are observed for solid PM fractions such as elemental carbon and metallic ash.

According to certain embodiments of the present invention, it is preferred to have a porous material so that more gas can readily pass through the pores to interact with the catalyst deposited within the fiber composite core. Furthermore, having porous walls in certain embodiments may allow for a higher degree of depth filtration, which is also a desirable attribute.

The inventive substrate in wall flow configuration is much more direct in contact with the exhaust gas. The pore characteristics of the material (pore size, porosity, pore connectivity, open and closed pores, etc.) affect the physical interaction between the gas and the filter material and affect properties such as filtration efficiency and pressure drop. In addition, the durability of the substrate depends on the resistance of the material to chemical attack by the exhaust gas constituents. In particular, the material needs to be resistant to corrosion by metallic ash, which may be part of the diesel particulates. There is also a need for resistance to corrosion by sulfuric acid, especially when the filter is used with higher sulfur content fuels. In addition, since a large amount of heat may be released during filter regeneration, the filter material is also required to exhibit excellent thermal properties in terms of high temperature resistance and high temperature gradient. Insufficient temperature tolerance can lead to melting of the material, and insufficient thermal shock resistance can lead to cracking. Other potential problems include microcracking and spalling. In particular embodiments, the filter substrates and catalytic substrates of the present invention address one or more of these problems.

Important parameters to consider when designing the exact geometry of a wall flow monolith structure include: cell density, repeat distance (pressure drop distribution across the wall flow filter is uniform), wall thickness, frontal opening area, specific filtration area, and mechanical integrity factors.

In a particular embodiment of the invention, the wall flow configuration encloses one half of the channels. In another configuration, the substrate of the present invention has a wall flow configuration wherein the closed walls of the channels are located at the beginning or end of the channels. In another configuration, the closure wall is located in the middle of the channel, or alternatively anywhere between the beginning and end of the channel.

Further, the wall flow configuration may include any percentage of channels, e.g., 10%, 25%, 50%, 75%, 90%, 95%, etc.

Channel and channel opening

In one embodiment, the catalytic or filtration substrate does not contain a plurality of channels running the length of the substrate. In certain embodiments, a catalytic or filtration substrate given its porosity and permeability need not have channels located within the substrate for the substrate to function in its intended use, such as a catalytic converter. By placing the emissions within the path of the catalytic substrate, any possible back pressure is reduced by porosity and permeability alone. If a membrane configuration without channels is employed, the preferred application is in a low flow rate environment to reduce the likelihood of substrate structure damage. The membrane configuration is preferably used in "low flow" environments such as in a fireplace or may be in a power plant. Where the flow rate is low and in some cases constant (power plant). Of course, it should be understood that this configuration is also suitable for other applications, including vehicles and stationary engines.

In another embodiment, the catalytic or filtration substrate of the present invention in one embodiment has a plurality of channels extending longitudinally through at least a portion of the substrate. The plurality of channels allow a fluid medium, such as a gas or a liquid, to flow through the substrate. A plurality of channels extend from the front surface to the rear surface. Other channels may extend from the rear surface to the front surface.

The channel may extend through the entire length of the substrate. In such an embodiment, the channel will have a first channel opening at the front surface of the substrate and a second channel opening at the back surface. Alternatively, the channel extends through a portion of the substrate. In certain embodiments, the channel extends through about 99%, 97%, 95%, 90%, 85%, 80%, 70%, 60%, or 50% of the length of the substrate.

The passage holes or passage openings of the substrate can be made in many shapes. For example, the passage openings may be circular, triangular, square, hexagonal, etc. In a preferred embodiment, the passage openings are triangular, square or hexagonal.

In one embodiment, the channel openings are formed such that the thickness of the matrix material is substantially uniform between adjacent channels throughout the substrate. The wall thickness variation may be from about 1% to about 50% in certain embodiments.

In another embodiment, the channels are arranged such that the walls of adjacent channels are parallel to each other. For example, triangular, square or hexagonal channels may be formed such that the walls of adjacent channels are parallel to each other.

The diameter or cross-sectional distance of the channels within the substrate of the present invention may vary. In certain embodiments, the diameter or cross-sectional distance of the channel is from about 5cm to about 100 nm. In certain embodiments, the channel diameter is about 100 nm. Other suitable values include distances or diameters selected from about 1, 2,3, 4,5, 6, 7, 8,9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, and 20 mils.

The dimensions of the channel along its length may vary. For example, the channel may have a cross-sectional distance of about 0.04 inches at its opening and then gradually decrease in size to approach an end wall or point of the channel or opening at the end of the channel. In one embodiment, the front surface of the channel is a square opening having a side of about 10 mils. The channel extends through the length of the substrate and has a second opening in the rear surface. The access opening of the rear surface was square with a side of about 4 mils. The channel tapers along its length from the front surface to the rear surface. Other similar configurations are of course contemplated.

The size of the passage opening may also vary. For example, in certain embodiments, the diameter (or cross-sectional distance) is from about 1 to about 100 mils. Other suitable ranges for the channel opening size include, but are not necessarily limited to, about 1 to about 500 mils, about 1 to about 100 mils, about 1 to about 10 mils. Other suitable dimensions include distances or diameters selected from about 1, 2,3, 4,5, 6, 7, 8,9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, and 20 mils. The substrates of the present invention may also have channels of different sizes. That is, some channels of the substrate embodiment have a plurality of first channels of a first diameter or cross-sectional distance and a plurality of second channels of a second diameter or cross-sectional distance. By way of example, in one embodiment, the substrate of the present invention comprises one or more channels having a cross-sectional distance of about 5 mils, and further comprises one or more channels having a cross-sectional distance of about 7 mils. It is to be understood that other variations of these embodiments are also within the scope of the present invention.

In other embodiments, the channel diameter or cross-sectional distance may be about 5cm, 4cm, 3cm, 2cm, or 1 cm. Substrates having channels with larger diameters or cross-sectional distances are preferred for larger exhaust systems, which may have exhaust pipes with diameters of one or more feet.

The thickness of the channel walls may also vary. For example, the channel walls may have a thickness of less than 1 mil. Other suitable values for channel wall thickness include 1, 2,3, 4,5, 6, 7, 8,9, and 10 mils.

Channels may be measured in number of channels per square inch. In certain embodiments, the substrates of the present invention have from about 50 to about 100,000 channels per square inch. Other suitable values include 100, 200, 300, 400, 500, 600, 700, 800, 900, and 1000. Other embodiments include a catalytic or filtration substrate having 2000 channels per square inch.

In one embodiment, the substrate of the present invention comprises a wall thickness of 600cpsi and 6 mils. The pore density of the inventive substrate samples was compared to two samples of cordierite. The first and second cordierite samples were 100cpsi and 17 mil, 200cpsi and 12 mil wall thickness, respectively. In contrast, the inventive substrate in this embodiment is 600cpsi and 6mil wall thickness.

In one exemplary embodiment, the substrate was drilled with 0.04 inch diameter channels at 0.06 inch intervals across the entire filter. These channels are smaller than conventional cordierite wall flow channels. The result is a much greater increase in surface area than cordierite, even without regard to the surface area present within the bulk pores of the matrix material. The channel is preferably a "blind" channel. Exhaust emissions are forced to pass through the channel walls rather than flow in and out of the channels without reacting with the catalyst.

Another embodiment relates to a catalytic or filtration substrate comprising a plurality of pyramidal channels. The pyramidal shape of the channels makes them useful for many host materials, including the substrates of the present invention, such as nSiRF-C, but not other substrates. The pyramidal channels may be configured such that each channel has two channel openings, for example a through-flow configuration with one opening at the front surface of the substrate and one opening at the rear surface of the substrate. Alternatively, the pyramidal channels may be configured such that each channel has only one opening, e.g., a wall flow configuration. In this embodiment, the openings of some of the channels are located on the front surface, while the openings of other channels are located on the rear surface. Preferably the channels are arranged such that the configuration of adjacent channels is reversed with respect to the position of the channel opening. Moreover, in certain embodiments of the pyramidal wall flow configuration, the channels terminate in an undrilled portion of the substrate. The non-drilled portion of the substrate may be flat or pointed. If the non-drilled portion is flat, the longitudinal cross-section of the channel appears trapezoidal. If the non-drilled portion is sharp, the longitudinal cross-section of the channel appears triangular.

Shape and form

The catalytic and filtration substrates include a number of suitable and heretofore unknown configurations. The substrate is three-dimensional, typically having a front surface (or area or front surface) and a back surface (or area or front surface) connected to one or more side surfaces by a body of the substrate. The front and back surfaces can be many of the shapes described herein. By front surface is meant the surface through which the liquid passes as it enters the substrate. By back surface is meant the surface through which the liquid passes as it leaves the substrate. The surface is generally flat, but may be non-flat in some embodiments.

In certain embodiments, the substrate is cylindrical. The cylinder formed by the substrate is used, for example, to catalyze the reduction of NO in exhaust gases.

Many suitable lengths and widths or diameters are suitable for the substrate of the present invention. Suitable lengths include 1, 2,3, 4,5, 6, 7, 8,9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, and 20 inches. Of course, longer lengths may be preferred for substrates used in diesel applications and for stationary engines, such as in pharmaceutical and chemical plants, manufacturing plants, power plants, and the like. On the other hand, the shape of the substrate can be described in terms of the shape of its front surface. The substrate of the present invention may be prepared such that the front surface has one of several physical configurations. The shape of the front surface can be many shapes including, but not limited to, circular, triangular, square, oval, trapezoidal, rectangular, and the like. Three-dimensionally, the substrate form may be a cylinder or a substantially flat disk. Commercially available substrates are generally one of these two designs. The substrate may have right or rounded corners. Rounded corners are preferred for the shape of the front surface of the substrate. Thus, in one embodiment, the substrate of the present invention is square in shape with rounded corners. In another embodiment, the substrate front face shape is a rounded rectangle. In another embodiment, the front surface of the substrate is trapezoidal in shape with rounded corners.

Typical dimensions of the catalytic substrate of the present invention include, but are not limited to, substrates having a circular cross-section and a diameter of about 3.66, about 4.00, about 4.16, about 4.66, about 5.20, about 5.60, or about 6.00 inches. In other embodiments, the catalytic substrate is in the shape of an oval cylinder with cross-sectional dimensions (minor and major axes, respectively) of about 3.15 by about 4.75 inches, about 3.54 by about 5.16 inches, or about 4.00 by about 6.00 inches.

In another embodiment, the catalytic substrate has a shape and size suitable for use in a front end catalytic converter. Typically, front end catalytic converters are smaller in size than conventional catalytic converters on the engine exhaust system. It is within the ability of one of ordinary skill in the art to determine the appropriate size and shape of the front end catalytic converter. The size and shape of the front end catalytic converter is based on the particular front end and engine configuration with which the front end catalytic converter is used. For example, a conventional cordierite circular substrate having a diameter of about 4.5 inches has a front surface area of about 28.27 square inches. For example, on Ford 4.6V-8, there are two pre-catalytic converters with substrates of approximately this size. These two conventional pre-catalytic converters can be replaced with front-end catalytic converters of eight nSiRF-C substrates, which comprise a diameter of about 1.13 inches.

Alternatively, cylinders are used to catalyze the oxidation of carbon monoxide and unburned hydrocarbons in the exhaust. The length of the cylinder may be greater than, equal to, or less than the diameter of the cylinder.

Different shapes and configurations of filter substrates and catalytic substrates may be employed depending on the particular application, e.g., stationary engines, on-road vehicles, off-road vehicles, etc.

In another embodiment, the catalytic substrate is shaped to replace commercially used substrates of commercially available catalytic converters. In this embodiment, the shape and size of the substrate of the present invention is substantially the same as that of available catalytic converters using different substrates. For example, many catalytic converters in use today comprise a substrate made of cordierite. The shape and size of the cordierite of the catalytic converter is known or can be determined analytically. The substrate of the present invention is then prepared by processing or molding as described later so that the shape and size of the substrate of the present invention are substantially the same as those of known cordierite substrates.

Film configuration

Alternatively, the substrate has a thin film configuration. In this configuration, the length of the substrate is substantially less than the width or diameter of the substrate. In some conventional catalytic converters and particulate filters, a longer travel length of exhaust gas through the substrate corresponds to back pressure build-up. In the thinner substrates of certain embodiments of the present invention, backpressure is minimized, exhaust gas passes through the filter system with less effort, and filtration capacity is increased. This reduction in backpressure results in more efficient engine operation, meaning better gas mileage and greater power.

In one embodiment of the invention, the substrate was 2 inches in diameter and 1/16 inches thick, and had a surface area 400 times greater than a4 inch diameter by 6 inch long conventional cordierite filter. As the substrate itself has been reduced in size, the canister size can also be reduced, resulting in only a small bulge in the exhaust line. Alternatively, the substrate may be incorporated into an exhaust manifold.

In another embodiment, the substrate is in the form of a film. In this case, the film comprising the substrate material described herein has many of the shapes described above, wherein the length of the substrate is substantially less than the width or diameter. Dimensions may be described as ratios of width to length, or diameter to length, for example. Suitable diameter to width ratios include, but are not limited to, about 20: 1, 19: 1, 18: 1, 17: 1, 16: 1, 15: 1, 14: 1, 13: 1, 12: 1, 11: 1, 10: 1, 9: 1, 8: 1, 7: 1, 6: 1, and 5: 1.

Moreover, a substrate having a film configuration may be stacked with one or more individual substrate embodiments. Having a membrane configuration, a plurality of catalytic or filtration substrates having a membrane configuration may be stacked together. For example, a plurality (e.g., 5) of catalytic or filtration substrates in the form of cylinders (or discs) having a diameter of about 1 inch and a length of about 0.2 inch may be stacked together to form a stack of substrates having a length of, for example, about 1 inch.

In the case of a thin film configuration, in one embodiment, the catalytic substrate does not contain a plurality of channels extending through the substrate. Because of the short distance the gas must travel through and the low pressure drop due in part to the high porosity of the present invention, a substrate stack comprising a plurality of catalytic substrates having a thin film configuration may be formed.

Moreover, stacked film configurations also include those in which the individual substrates are not perpendicular to the bottom surface of the catalytic converter or particulate filter. In this embodiment, the substrate may be processed or molded such that the angle between the side (side) and the front (front or back) of the substrate is about 90 ° or less or greater than 90 °, e.g., 80 °,70 °, etc.

Addition of catalyst before sintering

In another embodiment, the catalytic substrate described herein further comprises a catalyst, wherein the catalyst is added to the matrix material prior to the sintering process. In this case, the catalyst is generally added to the slurry prior to forming the green body. In other embodiments, the catalyst is added to the fibers in the mixer. Alternatively, if the catalyst is in a liquid state, in certain embodiments the catalyst is added to the slurry. The substrate may be formed from a slurry comprising one or more catalysts. In one embodiment, the catalyst adheres to the fibers of the substrate when sintered. In another embodiment, the catalyst is located within the pores of the channel walls, as opposed to being attached primarily to the surface of the channel walls.

Substrate zoning

In another embodiment, the catalytic substrate described herein is prepared such that different regions in the substrate have different properties. In other words, one or more physical characteristics or properties of the catalytic substrate may not be consistent or uniform throughout the substrate. For example, in certain embodiments, different regions or zones of the substrate have different densities, different catalysts, different catalyst mixtures, different channel configurations, different porosities, different permeabilities, and/or different thermal properties. As an example, in one embodiment, the catalytic substrate of the present invention comprises an nSiRF-C composite and first and second catalysts, wherein the first catalyst is applied to a first region of the substrate and the second catalyst is applied to a second region of the substrate. In another embodiment, the degree of structural integrity of the substrate varies within the body of the substrate. For example, as described herein, a densified coating may be applied to a surface of a substrate to increase the hardness of the surface, which will reduce potential damage.

Washcoating

Another aspect of the invention relates to the catalytic or filtration substrate described herein further comprising a washcoat. In other embodiments, the catalytic substrate further comprises a catalytic washcoat, e.g., the washcoat comprises a catalyst in addition to the washcoat material. Alternatively, in another embodiment, the washcoat material is catalytically active.

Suitable washcoats include silica, titania, unimpregnated zirconia, zirconia impregnated with a rare earth metal oxide, ceria, collectively rare earth metal oxide-zirconia, and combinations thereof. Other suitable washcoats are disclosed in US6,682,706; 6,667,012, respectively; 4,529,718, respectively; 4,722,920, respectively; 5,795,456, respectively; and 5,856,263, the disclosures of which are incorporated herein by reference in their entirety.

Generally, in certain embodiments, the washcoat may be applied from an aqueous slurry. The alumina powder and/or other washcoat oxides are milled to the desired particle size. The particle size distribution of the washcoat powder affects the mechanical strength of the final washcoat and its adhesion to the substrate, as well as the rheology of the slurry during the washcoating process. In certain embodiments alumina (a very hard material) is milled with air jets or ball mills.

In the next step, the material was dispersed in acidified water in a tank with a high shear mixer. The solids content of the slurry is typically 30-50%. After prolonged mixing, the alumina suspension becomes a stable colloidal system.

The amount of washcoat deposited on the substrate depends on and can be controlled by the rheology (viscosity) of the slurry. In some cases the alumina slurry is a non-newtonian fluid whose viscosity changes with time and the amount of mechanical energy (shear rate) supplied to the system. At any steady shear rate, the viscosity of the slurry is a function of its pH. In certain embodiments, viscosity can be controlled by adjusting pH. However, due to the non-newtonian nature of alumina systems, precise control of viscosity is probably the greatest challenge in the application of washcoat processes.

The washcoat slurry may be applied to the substrate by any known method and procedure, including dipping or casting onto the component, and/or using a specialized coater. Excess slurry is removed from the channels with compressed air. The substrate may then be dried and calcined to bond the washcoat to the walls of the monolithic structure.

In certain embodiments, one, two, or more layers of washcoat may be applied. Each layer may be dried and calcined before the next layer is processed. The multi-layer washcoat is applied for several reasons: (1) catalyst design may require different chemical formulations for each layer, and (2) coating/processing equipment limitations, such as inability to handle very viscous slurries, which are required for thick washcoats in a single operation.

Typical washcoat thicknesses range from 20 to 40 μm, although values outside this range may also be used in the present invention. These values correspond, for example, to washcoat loadings of about 100g/L on a 200cpsi substrate to about 200g/L on a 400cpsi substrate. The specific surface area of the catalyst washcoat material in certain embodiments is between 100 and 200m²Between/g. Of course, other values are also suitable for use in the present invention.

In complex catalyst systems the noble metal and other catalysts may react with each other, with washcoat components, or with support materials to produce undesirable catalytically inactive compounds. If such reactions occur within a given catalytic system, this is difficult to prevent in conventional washcoating techniques. Contact between the reactive components cannot be avoided due to impregnation of the catalytic metal onto the final washcoat.

Isolation washcoating techniques have been developed to physically isolate precious metals by immobilizing them on the particular base metal oxides of the washcoat prior to application of the washcoat to a substrate. By using washcoats with different oxides and/or precious metals, the components of the catalytic system can be separated. Other benefits of this technique include control of the precious metal/base metal ratio and improved precious metal dispersion. This technique can be used in the present invention. Thus, in a preferred embodiment, the present invention is directed to a catalytic substrate comprising nSiRF-C, at least two catalytic metals, and a washcoat, wherein the two catalytic metals are physically segregated.

Isolation washcoating example: release washcoats were first used for automotive three-way catalysts. An example of such a catalyst is a trimetallic system comprising platinum, palladium and rhodium. CatalysisThe first layer of the agent is made of Pd/Al₂O₃And (4) forming. The second (surface) layer is made of Rh/Pt/Ce-Zr. This design prevents the formation of palladium-rhodium alloys, which would deactivate the catalyst.

Alumina or alumina is a basic material for the washcoat of emission control catalysts. High surface area gamma crystal structure (gamma-Al)₂O₃) For catalyst applications. Characterized by high purity. Al (Al)₂O₃The presence of certain elements in the composition may affect its thermal stability, both deproductive and positive. Al (Al)₂O₃In the presence of small amount of Na₂And O is used as a flux to enhance the sintering of the alumina. In contrast, comprising La₂O₃、SiO₂BaO, and CeO₂Several metal oxides have the effect of stabilizing the surface area of the alumina while reducing its sintering rate. Stabilized alumina is commercially available.

In other embodiments, the ceria or ceria is a catalyst washcoatThe topcoat component is, for example, incorporated in an amount of no greater than 25%. In other embodiments, the ceria is added in amounts of about 5%, 10%, 15%, 20%, and 25%. Ceria is an important promoter in automotive emission control catalysts. One function of ceria in a three-way catalyst is oxygen storage, which can be achieved by adding cerium oxide to Ce⁴⁺And Ce³⁺And (4) realizing the cycle. Other effects attributed to ceria include stabilizing the alumina, promoting steam reforming reactions, promoting noble metal dispersion, and promoting noble metal reduction.

Certain diesel oxidation catalyst formulations include a high loading of ceria. The role of ceria is to catalytically oxidize/crack the soluble organic fraction of the diesel particulate.

High surface area ceria can be produced, for example, by calcining a cerium compound. The BET surface area of the cerium oxide can be up to 270m²(ii) in terms of/g. Other embodiments, for example in a three-way catalyst, use about 150m²Ceria per gram surface area. The high-temperature stabilized variety which can endure the temperature of 900-1000 ℃ has the length of about 6-60m²Surface area in g, is suitable for use in the present invention.

In other embodiments, the catalytic or filtration substrate of the invention further comprises zirconia. In certain embodiments, the zirconia provides increased thermal stability to the substrate.

Titanium dioxide is used as an inert, non-sulfated support with some diesel catalysts. Two important crystal structures of titanium dioxide include anatase and rutile. The anatase form is important for catalyst applications. It has a thickness of 50-120m²(ii) a maximum surface area per gram, no greater than 500 ℃, is thermally stable. The rutile structure has a thickness of 10m²Low surface area below/g. Anatase at about 550 ℃The ore is converted to rutile, resulting in deactivation of the catalyst. In another embodiment of the invention, the catalytic substrate comprises nSiRF-C (preferably AETB or OCTB), a catalyst, and titanium dioxide.

Zirconia can be used as a thermal stabilizer and ceria co-catalyst in automotive three-way catalysts, and also as a non-sulfated component of diesel oxidation catalyst washcoats. BET surface area of 100-²(ii) in terms of/g. The surface area is rapidly released at the temperature of 500 ℃ and 700 ℃. Better thermal stability can be obtained using a wide variety of dopants including La, Si, Ce, and Y.

Zeolites are synthetic or naturally occurring aluminum silicate compounds having a well-defined crystalline structure and pore size, the size of the zeolite pores is generally between 3 and 8 Å, falling within the molecular size range²(ii) in terms of/g. The surface area of the mordenite was about 400-500m²(ii) in terms of/g. Most zeolites are thermally stable at temperatures no greater than 500 ℃.

Certain catalytically applied zeolites are ion-exchanged with metal cations. First use a solution containing NH⁴⁺(NH₄NO₃) Treating the acid form zeolite (HZ) with an aqueous solution of (A) to form ammonium-exchanged zeolite (NH)⁴⁺Z^-). The metal-exchanged zeolite (MZ) is then formed by treatment with a salt solution containing a catalytic cation.

Zeolites are excellent adsorbent materials due to their reproducibility and defined pore structure. Have been used as adsorbents in many applications including drying, purification and separation. Synthetic zeolites are also used as catalysts in petrochemical processes.

In recent years, zeolites have been increasingly used in the control of diesel emissions, both as catalysts (SCR, lean NOx catalysts) and as adsorbents (trapping hydrocarbons in diesel oxidation catalysts).

It is to be understood that other embodiments of the present invention include any of the specific substrate embodiments described herein, and that such substrate embodiments also include any of the specific washcoat embodiments.

Oxygen storage oxides

In another embodiment, the catalytic substrate or filtration substrate of the invention further comprises an oxygen storage oxide. Oxygen-storing oxides, e.g. CeO₂Has an oxygen storage capacity (hereinafter abbreviated as "OSC"), i.e., an ability to occlude oxygen and release occluded oxygen. More specifically, CeO is added₂To adjust the oxygen concentration of the gaseous atmosphere, therebyExcess oxygen in the gaseous atmosphere is occluded in CeO in an oxygen-rich state (i.e., a fuel-lean state, which may be simply referred to as "lean state")₂In crystal structure to help catalytic converter reduce NOx to N₂While in the CO-rich and/or HC-rich state (i.e., fuel-rich state, which may be referred to simply as "rich state") occluded oxygen is released into the gaseous atmosphere to assist the catalytic converter in oxidizing CO and HC to CO₂And H₂And O. Thus, CeO is added₂The catalytic activity of the catalytic substrate is improved. Other oxygen storage oxides include Pr₆O₁₁Etc., as disclosed in US6,576,200. Other embodiments include any of the specific substrate embodiments described herein, embodiments of which further comprise an oxygen storage oxide such as CeO₂。

SOx oxidation

In the presence of certain metal catalysts, particularly platinum, sulfur present in fuels such as diesel fuel is converted to SOx, which may then produce environmentally harmful sulfur compounds such as sulfuric acid fumes in the exhaust gas. Most sulfates are typically formed on platinum catalysts at higher exhaust temperatures of about 350 ℃ and 450 ℃. While there is an urgent need to remove sulfur from gasoline and diesel fuel formulations, during the transition period, catalyst formulations have attempted to minimize this problem to the greatest extent possible.

Typical platinum catalysts developed by Engelhard are from 5 to 150g/ft³Pt/Rh in a ratio of 5: 1 and 30-1500g/ft³MgO (U.S. Pat. No. 5,100,632(Engelhard Corporation)). The catalyst may be impregnated onto the substrate from an aqueous-based solution. The catalyst coated filter is preferably used for regeneration at exhaust gas temperatures of 375 ℃ -. The rhodium in the above formula has the effect of inhibiting SO₂Thereby inhibiting sulfate masking in the catalyst.

In certain embodiments, the catalytic substrates of the present invention can address these issues by, for example, having improved heat distribution, thereby reducing thermal decomposition of the catalyst.

Catalyst poisoning is a significant cause of catalyst deactivation. Catalyst poisoning may occur when species present in the exhaust gas chemically deactivate catalytic sites or cause fouling of catalytic surfaces. Poisons in the exhaust gas from internal combustion engines may originate from lubricating oil compositions or fuels.

The interaction between different catalyst species or between a catalyst species and a support component is another temperature-induced manner of catalyst deactivation. Examples are rhodium and CeO in automotive three-way catalysts₂The reaction between them. Such problems can be reduced by alternative support and special washcoat techniques known in the art that physically isolate the reactive components.

Another advantage of the present invention is that nSiRF-C can be pumped in different regions to physically isolate incompatible components, or can be used in stacked film configurations with incompatible components within separate film substrates.

Catalyst deactivation may also occur due to erosion and wear resulting in physical loss of the washcoat. This mechanism may also be important for emission control catalysts due to high gas velocities, temperature variations, and differences in thermal expansion between the washcoat and the matrix material.

Catalyst coating

In some applications, NOx is converted to a salt with an adsorbent catalyst, and the salt can then be removed manually in a regeneration process. However, the presence of sulfur in the fuel can lead to the formation of insoluble SO₄Salts such as barium sulfate may form a protective coating on the catalyst and reduce its efficiency. An advantage of certain embodiments of the present invention is that the catalytic substrate is less susceptible to efficiency degradation due to sulfate coating.

In another embodiment, the catalytic or filtration substrate of the invention further comprises a protective coating suitable for use in ceramics. For example, such a suitable protective envelope is disclosed in US 5,296,288, the disclosure of which is incorporated herein by reference in its entirety. This coating is referred to as a protective coating (PCC) for the ceramic material. Another suitable associated envelope may be Emisshield^TMObtained in form (wessex incorporated, Blacksburg, VA). Emisshield^TMThe emissivity agent in (1) enhances the emissivity of the material, especially at high temperatures. In addition, the protective envelope may reduce damage from external impact and abrasion forces. Suitable envelopes are disclosed in US 5,702,761 and 5,928,775 (diciara, jr. et al), and US 5,079,082(Leiser et al),these disclosures are incorporated herein by reference. The coating may be used with one or more of the specific filtration and catalytic substrates described herein.

In certain embodiments, the catalytic substrate or filtration substrate is resistant to thermal shock and thermal cycling damage. Some substrates are relatively soft and may be damaged by external impact and abrasion forces. To reduce this damage, in a preferred embodiment, the catalytic or filtration substrate of the invention further comprises one or more protective coatings on the surface (preferably the outer surface) of the substrate. Examples of suitable protective envelopes are disclosed in US 5,702,761 and 5,928,775, and US 5,079,082, the disclosures of which are incorporated herein by reference. Thus, in a preferred embodiment, the present invention provides a substrate having properties of higher porosity, higher permeability, and sufficient hardness than conventional substrates. The coating may be used with one or more of the specific filtration and catalytic substrates described herein.

Pressure drop

The present invention also provides substrates that provide improved pressure drop across catalytic converters and particulate filters. Thus, in certain embodiments, the substrates of the present invention can provide a means of removing and/or filtering exhaust gases without significant back pressure build-up or with a lower back pressure build-up than conventional catalytic and particulate filters.

The flow of exhaust through a conventional catalytic converter creates a significant amount of backpressure. Backpressure buildup in a catalytic converter is an important indicator of catalytic converter success. If the catalytic converter becomes partially or fully plugged, the exhaust system will be restricted. Subsequent back pressure build-up will result in a dramatic decrease in engine performance (e.g., power and torque) and fuel economy, and may even result in engine misfire after engine start-up if the blockage is severe. Conventional attempts to reduce polluting emissions are costly due to the materials and the cost of the original engine to retrofit or manufacture the appropriate filter.

In certain embodiments, the substrates of the present invention have properties that result in lower or less pressure drop than conventional substrates used in catalytic converters or particulate filters. The present invention in certain embodiments results in less soot accumulation within the particulate filter and in some cases may result in less frequent filter changes than conventional particulate filters.

Detailed Description

The invention also relates to specific embodiments of the above described catalytic and filtration substrate. Particular embodiments include a substrate comprising (or alternatively consisting essentially of) nSiRF-C and a catalyst. Another embodiment is a filtration substrate comprising nSiRF-C and a plurality of channels.

For example, certain embodiments of the substrate have a plurality of the above attributes. In other embodiments, the substrate of the present invention has 2,3, 4, 5,6, 7,8, 9, or 10 of the above attributes. Particular embodiments may include any combination of attributes. The catalytic substrate is further illustrated by the following non-limiting specific embodiments.

In one embodiment, the substrate of the present invention comprises an nSiRF-C composite having a porosity of about 96% to about 99% and a density of about 10 to about 14lb/ft³A plurality of channels having a wall flow configuration; and optionally with a catalyst.

In one embodiment, the inventive substrate comprises an nSiRF-C composite comprising alumina boria silica fibers, and alumina fibers, having a porosity of about 96% to about 99%, and a density of about 10 to about 16lb/ft³Preferably about 10, 11, 12, 13, 14, 15 or 16lb/ft³A plurality of channels having a wall flow configuration; and optionally with a catalyst. In other embodiments, the substrate further comprises a washcoat, preferably alumina or a derivative thereof.

In another embodiment, the substrates of the present invention include substrates having one or more of the following attributes: a tensile strength of from about 100 to about 150, preferably from about 130 to about 140, more preferably about 133 psi; a thermal conductivity of about 0.5 to about 0.9, preferably about 0.7 to about 0.8, more preferably about 0.770 BTU-ft/hr ft²F; a coefficient of thermal expansion of about 1 to about 5X 10^-6About 1 to about 3X 10^-6More preferably about 1.95X 10^-6(77 ℃ F. -1000 ℃ F. test)) (ii) a An average density of about 15.5 to about 17, preferably about 16 to about 16.8, more preferably about 16.30/lb/ft³(ii) a And optionally a catalyst.

In another embodiment, the substrates of the present invention include substrates having one or more of the following attributes: a tensile strength of from about 50 to about 70, preferably from about 60 to about 65, more preferably about 63 psi; a thermal conductivity of about 0.5 to about 0.9, preferably about 0.7 to about 0.8, more preferably about 0.770 BTU-ft/hr ft²F; a coefficient of thermal expansion of about 1 to about 5X 10^-6About 1 to about 3X 10^-6More preferably about 1.77X 10^-6(77F. to 1000F.); an average density of about 7 to about 9, preferably about 8.2 to about 8.6, more preferably about 8.40/lb/ft³(ii) a And optionally a substrate.

In another embodiment, the substrates of the present invention include substrates having one or more of the following attributes: a tensile strength of from about 60 to about 80, preferably from about 70 to about 79, more preferably about 74 psi; a thermal conductivity of about 0.5 to about 0.9, preferably about 0.7 to about 0.8, more preferably about 0.765 BTU-ft/hr ft²F; a coefficient of thermal expansion of about 1 to about 5X 10^-6About 1 to about 3X 10^-6More preferably about 1.84X 10^-6(77F. to 1000F.); an average density of about 9 to about 11, preferably about 9.5 to about 10.5, more preferably about 10lb/ft³(ii) a And optionally a catalyst.

Another suitable catalytic substrate of the invention is nSiRF-C described herein; and a catalyst, wherein the catalyst comprises: a support pre-doped with copper oxide (CuO); at least one noble metal selected from the group consisting of platinum (Pt), palladium (Pd), rhodium (Rh) and rhenium (Re) as a main catalyst, wherein the at least one noble metal is doped on the surface of the pre-doped support; and is selected from antimony trioxide (Sb)₂O₃) Bismuth trioxide (Bi)₂O₃) Tin dioxide (SnO)₂) And mixtures thereof, wherein the at least one metal oxide is doped on the surface of the pre-doped support. Such a catalyst is described in US6,685,899, which is incorporated herein by reference in its entirety.

In one embodiment, the substrate is suitable for use in a catalytic converter placed in front of an exhaust manifold associated with an exhaust gas stream in the front end of an engine.

Other embodiments of the catalytic substrate include a catalytic substrate comprising an nSiRF-C composite having the approximate properties shown in the table below.

	Embodiment 1	Embodiment 2	Embodiment 3
				Thermal conductivity	4-100×10-2W/m-K	5-7×10-2W/m-K	6.04F-02W/m-K
Specific heat	10-150J/mol K	600-700×10-2J/kg-K	640×10-2J/kg-K
				Density of	.05-5gm/cc	0.1-0.3gm/cc	0.2465gm/cc
Emissivity of radiation	.68-.97	0.7-0.92	0.88
				Axial strength	1.5-3.5MPa	2-3MPa	2.21Mpa
3500rpm Noise attenuation	40-100db	70-80db	74db
				Porosity of the material	80-99％	97-98％	97.26％
Permeability rate of penetration	At least 600	900-∞cd	1093-∞cd
				Regeneration time	0.5-1.5 seconds	0.6-0.9	0.75 second
Surface area		70,000-95,000in2	88,622in2
				Melting Point	1700-5000	3000-4000℃	3,000℃
Thermal expansion (CTE)	0.001×10-6-9×10-6	0.1×10-7-0.4×10-7	0.25×10-71/C

Another embodiment relates to a catalytic substrate comprising nSiRF-C as described in table 1; and a catalyst selected from the group consisting of palladium, platinum, rhodium, derivatives thereof, and combinations thereof.

Preferred substrates comprising advanced nonwoven refractory fibers have a porosity of 90% to 98% and an emissivity value between 0.8 and 1.0.

In one embodiment, the filter substrate of the present invention comprises, or consists essentially of, nSiRF-C, a front inlet end and an outlet end, a matrix of thin and porous intersecting vertically extending walls and horizontally extending walls defining a plurality of channels extending in a substantially longitudinal and mutually parallel manner between the front inlet end and the outlet end; the leading inlet end includes a first section of cells plugged along a portion of its length in a non-tessellated pattern, the first section of non-tessellated cells being smaller than the second section of tessellated cells, and a second section of cells plugged in a tessellated pattern. Such a configuration is further described in US6,673,414, which is incorporated herein by reference in its entirety. No more than three-quarters of the holes of the first section may be unblocked. Or no more than half of the first segment pores may be unblocked. Alternatively, no more than one-fourth of the pores of the first segment may be unplugged.

It is also to be understood that the present invention relates to embodiments consisting of, or consisting essentially of, the limitations of the various embodiments. Thus, for example, one embodiment has been described as a catalytic substrate comprising nSiRF-C and a catalyst, it being understood that the invention also encompasses a catalytic substrate consisting of, or consisting essentially of, nSiRF-C and a catalyst.

Catalytic reaction and filtration method

Another aspect of the invention relates to a method of catalyzing a reaction comprising providing a catalytic substrate of the invention; and directing a fluid stream over and/or through the catalytic substrate at a temperature sufficient to catalyze the reaction. Preferably the reaction converts the contaminants to non-contaminants. For example, in one embodiment the catalytic substrate converts carbon monoxide to carbon dioxide.

The catalytic process is completed with a substrate comprising an alumina-reinforced thermal barrier material as described herein.

In a preferred embodiment, the substrate comprises a suitable catalyst.

In one embodiment, the present invention relates to a method of filtering exhaust gas comprising providing a filtration or catalytic substrate of the present invention as described above, and directing a fluid stream, such as a gas or liquid, through the substrate, wherein the gas comprises particulate matter.

In another embodiment, the method further comprises burning off the filtered particulate matter. Burning off the filtered particulate matter converts the accumulated particulate matter into primarily non-pollutants.

This aspect of the invention is particularly useful with diesel engines. In another aspect, the present disclosure is directed to a method of filtering, wherein the filtering utilizes a diesel particulate filter.

Diesel engines (compressed individually ignited fuel) have recently received worldwide scrutiny for their exhaust emissions, containing a large number of harmful particles in addition to toxic gases. The manufacturer's response is to use known catalytic converter technology on the diesel engine. Unfortunately, regulations regarding emission standards have exceeded the physical and economic limits of conventional catalytic converters. Diesel emissions are distinguished from gasoline emissions by the production of larger quantities of particulate matter. For this reason, the prior art for exhaust emission capture, combustion and oxidation is not sufficient to comply with the most stringent emission standards.

Most buses are made or retrofitted with 85% efficiency diesel particulate traps [ "DPTs" ]. DPTs are costly, complex, have low fuel economy, and have low durability. Further regulations require 100% compliance by 2010, and these regulatory requirements cannot be met with DPTs alone. The high temperature of the engine or exhaust gas allows the particulate matter to be burned with a short residence time. Moving the filter closer to the engine combustion chamber or adding an auxiliary heat source may provide more heat. Thus, there is a need for a filter that: (1) can be placed at very high temperatures, i.e., above 500 ℃, e.g., near the combustion chamber; (2) more resistance to vibration degradation; and (3) still maintain or improve the combustion effect of the particulate matter. The ability to achieve particulate matter combustion even in the absence of a catalyst can provide substantial savings in catalyst and coating costs.

Once the filter captures the particulate matter (e.g., soot), it needs to be warmed up sufficiently in the presence of oxygen to allow complete combustion of the particulate matter. Combustion of the particulate matter may be accomplished using the existing temperature of the exhaust gas and/or providing an auxiliary heat source. The time taken to combust the particulate matter at this temperature is referred to as the desired "residence time", "regeneration time", or "burn-up" period. The shorter residence time of the particles within the pores of the substrate translates into reduced occurrence of pore plugging buildup that can lead to increased gas flow backpressure, which requires additional energy to operate efficiently. Shorter residence times are therefore preferred.

One conventional DPT is listed in US5,611,832 (Isuzu Ceramics Research Institute co., Ltd.), which discloses a DPT for collecting particulates from exhaust gas emitted from a diesel engine. The DPT filter is constructed of woven inorganic fibers covered with silicon carbide ceramic, and a wire mesh disposed therebetween.

Other uses of the filtration substrate or catalytic substrate include the ability to remove or filter contaminants and impurities from fluid streams, such as: dust/soot, smoke, pollen, fluids, bacteria/viruses, odors, oils, volatile organic compounds, liquids, methane, ethylene, and a wide variety of other chemicals, including those listed as the 188 "toxic air pollutants" of the EPA.

Methods of catalyzing reactions and/or filtering fluids may be used in many industries or applications, particularly one or more of the following: the aerospace industry; asbestos; covering and processing asphalt; automobiles and light trucks (topcoats); benzene waste treatment; shipbuilding; brick and construction applications; manufacturing a clay product; manufacturing a cellulose product; producing carboxymethyl cellulose; cellulose ether production; manufacturing a cellulose food coating; producing glass paper; electroplating chromium; a coke oven: pushing, quenching, and battery set; a coke oven; a gas turbine; a degreasing organic cleaning agent; dry cleaning; engine test rooms or stations; fabric printing, coating and dyeing; producing iron alloy; a flexible polyurethane foam; a manufacturing operation; producing flexible polyurethane foam; producing a friction product; gasoline distribution (first stage); general supply; general MACT; burning of hazardous waste; a hazardous organic NESHAP; producing hydrochloric acid; industrial, commercial and institutional boilers; industrial cooling tower process heaters; steel works; iron foundries (surface coatings); leather finishing operation; lime production; a magnetic tape; producing nutrient yeast; loading operation of the marine vessel; mercury battery chlor-alkali plants; metal core (surface coating); metal cans (surface coatings); metal facilities (surface coatings); a mineral wool product; manufacturing a hybrid coating; various metal parts and articles; municipal solid waste landfill; natural gas transmission and storage; off-site waste recovery operations; oil and natural gas production; organic liquid partitioning (non-gasoline); paper and other fabrics (surface coatings); production of pesticide active ingredients; an oil refinery; medicine production; phosphoric acid/phosphate fertilizers; plastic parts (surface coatings); polymers and resins; a polyether polyol product; polybutadiene rubber; polysulfide rubber; a phenolic resin; polyethylene terephthalate; polyvinyl chloride and copolymer production; producing Portland cement; producing primary aluminum; smelting raw lead; raw copper; refining raw magnesium; printing/publishing; a camping Processing Operation (POTW); pulp and paper (non-combustion) MACT I; pulp and paper (non-chemical) MACT III; pulp and paper (combustion source) MACT II; crushing paper pulp and paper; a reciprocating internal combustion engine; production of refractory products; producing reinforced plastic composite materials; secondary aluminum; a secondary lead smelting furnace; manufacturing a semiconductor; shipbuilding & ship repair; performing field remediation; solvent extraction for the production of vegetable oils; a steel pickling-HCL process; processing the taconite; producing tetrahydrobenzaldehyde; producing a tire; wet forming the fibers; production of the mat; a wooden product; wooden furniture; and wool fiber glass production. These industries and applications typically employ fixed emissions sources regulated by the EPA.

Other suitable uses include filtration or catalytic processes in one or more of the following applications: automotive (dust/soot, odor, oil filtration, VOC, methane, other chemicals (gaseous, solid or liquid)); water sprays (dust/soot, odor, oil filtration, VOCs, methane, other chemicals (gaseous, solid or liquid)); snowmobiles (dust/soot, odor, oil filtration, VOCs, methane, other chemicals (gaseous, solid or liquid)); small engines (dust/soot, odor, oil filtration, VOCs, methane, other chemicals (gaseous, solid or liquid)); motorcycle (dust/soot, odor, VOC, methane, other chemicals (gaseous, solid or liquid)); mobile diesel engines (dust/soot, odors, VOCs, methane, other chemicals (gaseous, solid or liquid)); stationary diesel engines (dust/soot, odor, oil filtration, VOCs, methane, other chemicals (gaseous, solid or liquid)); power plants (dust/soot, odors, VOCs, methane, other chemicals (gaseous, solid or liquid)); refineries (VOCs, other chemicals (gaseous, solid or liquid)); and chemical and pharmaceutical (dust/soot, bacteria/viruses, odors, oil filtration, VOCs, methane, other chemicals (gaseous, solid or liquid)).

In addition, other catalytic and/or filtration applications include the use of the substrates of the present invention in one or more of the following areas: incineration and emission in agriculture and forestry; bakeries (dust/ash, smoke, smell, VOC, other chemicals (gaseous, solid or liquid)); filtering the biomedical fluid; breweries and wineries (odor); cabin air (car, submarine, aerospace industry, aircraft) (dust/soot, smoke, pollen, bacteria/viruses, odors, VOCs, other chemicals (gaseous, solid or liquid)); clean room applications (dust/soot, smoke, pollen, bacteria/viruses, odors, oils, VOCs, methane, other chemicals); commercial incineration emissions (odor, VOC, other chemicals (gaseous, solid or liquid)); commercial toxic organic emissions; dry cleaning (VOCs, other chemicals (gaseous, solid or liquid)); volatile emissions (e.g., fuel gasification management); a fireplace; barbeque (fast food) (dust/ash, smoke, odor, VOC, other chemicals (gaseous, solid or liquid)); a health center; general fluid filtration (potable water treatment); food processing and storage (smell, other chemicals (gaseous, solid or liquid)); foundry (odor); fuel cells (VOCs, methane, other chemicals (gaseous, solid or liquid)); gas masks (dust/ash, smoke, pollen, bacteria/viruses, odors, VOCs, other chemicals (gaseous, solid or liquid)); general VOC applications for processing/manufacturing (wood products, coatings industry, textile industry, etc.); glass/ceramic; a greenhouse; domestic appliance-cold (rechargeable appliance) (smell, oil, VOC, other chemical substance (gaseous, solid or liquid state); domestic appliance-hot (water heater and domestic heater) (smell, oil, VOC, other chemical substance (gaseous, solid or liquid state)); HVAC sanitary installation; hydro-reforming (VOC, methane, other chemical substance (gaseous, solid or liquid state)); medical media; office buildings; oil/gasoline transportation; other electro-magnetic insulation (electro-magnetic field); paint usage; petrol stations (smell, VOC); polymer processing (smell, VOC, other chemical substance (gaseous, solid or liquid state)); recovery of precious metals/catalysts from hot gas and liquid; restaurant smoke; sewage and biological waste (/ bacteria/virus, smell, VOC, methane, other chemical substance, Solid or liquid); a slaughterhouse; smokers (dust/ash, smoke); sound insulation; a swimming pool; a tanning chamber; tunnels and parking lots (dust/soot, odors, VOCs, methane, other chemicals (gaseous, solid or liquid)); and waste incineration (dust/soot, odor, VOC, other chemicals (gaseous, solid or liquid)).

Method for preparing a catalytic or filter substrate

In another aspect, the invention relates to a method of making any of the substrates (catalytic or filtration) described herein. The invention also relates to a method for preparing the catalytic substrate according to the invention. In another aspect, the present disclosure is directed to a method of making a diesel particulate filter. The substrate can be prepared by a number of methods described below.

In one aspect of the invention, the catalytic substrates described herein can be prepared from commercially available nSiRF-C blanks. Commercially available nSiRF-C blanks were machined to the appropriate shape, form and size. Substrates of the invention may be prepared from bulk suitable for the matrix material by processing the bulk into a shape suitable for use in the invention. The raw block may be readily cut or sawn into a pre-formed shape and then sanded, turned or machined into a final desired shape of a "slug". While the composition of the matrix material is easily recoverable to chemical, thermal, and vibrational impacts, the matrix material has a low hardness. This low hardness allows machining with little or no resistance or wear to the tool. Despite its low hardness and softness, the block is very durable and easy to machine, engrave or mold. For example, in certain embodiments, the matrix material typically has a Mohs hardness scale between 0.5 and 1.0 (or a Knoop hardness scale of 1-22), the softest being a talc Mohs hardness of 1(1-22 Knoop hardness), and the hardest being a diamond Mohs hardness of 10(8,000-8,500 Knoop hardness). Some prior art matrix materials of other suitable values are harder. For example, silicon carbide has a Mohs hardness of 9-10(2,000-2950 Knoop hardness).

Forming, sanding, turning, or machining the blank to form a semi-finished product of indefinite shape can be accomplished with less difficulty than some conventional substrates such as cordierite. The machining may include turning a cylinder on a lathe, hole sawing, band or clip sawing a shape, sanding a shape or polished surface, or any other machining method commonly used for other solid materials and known in the art. The blank can be machined to very tight tolerances with the same precision as metal, wood or plastic. If the blank is cast in a cylindrical die of the desired diameter in the final shape, the machining process need only cut and sand the cylindrical blank to the desired thickness. The process also reduces substrate loss due to over-machining and speeds up the pre-forming process.

In certain embodiments, the shape of the front face of the substrate is circular 510, oval 520, and racetrack 530, as shown in fig. 5. Obviously, these shapes need not be precise. Three-dimensionally, the substrate may be in the form of a cylinder or a substantially flat disk. Designs with right angles are not very effective in some applications. Although easy to process, a square or angular design has proven to be a catcher for rust and corrosive substances such as snow-melting salts. Thus, in certain embodiments, rounded corners are preferred for the front shape of the semi-finished product.

The blank may be formed with a band saw, a jig saw, CNC, or other methods known to those of ordinary skill in the art. The blank may be further shaped by manual rubbing, lathe sanding, belt sanding, or orbital sanding. It is preferred to vacuum out the airborne particles to prevent them from clogging the pores of the material. Moreover, these particles can enter the bearings of the drill press and damage the drill press, wear off and scuff the bearings. The ceramic dust is also fine and may be easily inhaled by the operator.

In another embodiment, the invention relates to a method of making a catalytic or filtration substrate according to the invention, comprising preparing a nSiRF-C composite blank; and optionally machining the blank to form the inventive substrate. If the billet is prepared in a shape suitable for use in one or more processes of the present invention, the billet does not necessarily need to be machined into a different shape. In this case, a billet is prepared with a suitably shaped die as described below. Alternatively, the blank or substrate may be machined to the appropriate shape. Further, as described in more detail below, a plurality of channels are machined into the substrate.

The step of preparing the blank (or substrate) includes known methods of preparing these materials. Any known method of making a suitable blank or substrate may be used. For example, suitable methods are disclosed in US 4,148,962 and 6,613,255, which disclosures are incorporated herein by reference in their entirety.

By way of non-limiting example, in one embodiment, the step of preparing a suitable substrate comprises:

heating a plurality of refractory silica fibers, refractory alumina fibers, and refractory aluminoborosilicate fibers;

mixing the fibers;

washing the fibers;

optionally cutting the fibers into one or more lengths;

blending or mixing the chopped fibers into a slurry;

adjusting the viscosity of the slurry, preferably by adding a thickener;

adding a dispersing agent;

adding the slurry to a mold;

removing water from the slurry to form a green body;

removing the green body from the mold;

drying the green body in an oven, preferably at a temperature of about 250 to about 500 ° f; and

the green body is heated in an oven at 2500F. at about 2000F, preferably preheated and incrementally heated.

The blank is then optionally machined to form the inventive substrate, as described above.

In another embodiment, the process further comprises machining a plurality of channels in the substrate.

In another embodiment, the process further comprises adding a washcoat to the substrate.

In another embodiment, the process further comprises adding a catalytic coating to the substrate.

In yet another embodiment, the mixing of the fibers is performed after washing and heating the fibers.

In yet another embodiment, boron nitride is used in the process of making the substrate of the present invention.

In yet another embodiment, a thickener is used. Preferably, the thickeners and dispersants used in the process are substantially removed from the substrate during the heating step. For example, the thickener and dispersion may burn during sintering.

The substrate 2510 is from a blank produced by forming chopped and/or non-woven inorganic fibers in a rigid configuration and a binder. The blank is machined or machined to the desired outer dimensions of the substrate 2510. The interior of the substrate 2510 is then machined or worked to provide the desired surface area increasing configuration such as channels, washcoats, or catalysts. The durable inorganic hardened coating 2511 can be applied to the substrate 2510 by brushing, spraying, dipping, or any other commonly used coating method. In addition, the substrate 2510 can include an oxidation or reduction catalyst applied by brushing, spraying, dipping, or any other commonly used application method.

In one embodiment, the catalytic or filtration substrate of the present invention comprises nSiRF-C; and a coating comprising 23.0 to 44.0 wt% silica powder, 25.0 to 45.0 wt% colloidal silica, 19.0 to 39.0 wt% water, and one or more emissivity agents selected from the group consisting of silicon tetraboride, silicon hexaboride, silicon carbide, molybdenum disilicide, tungsten disilicide, and zirconium diboride mixed; wherein the solid content of the protective coating is 45-55 wt%. Such a capsule is disclosed in US5,296,288.

The present invention utilizes a variety of high-grade non-woven sintered inorganic refractory fibers, such as those found in AETB. Other suitable materials for use as nSiRF-C in the present invention include AETB-12 (composition of about 20% Al)₂O₃About 12% (14% B)₂O₃、72％Al₂O₃、14％SiO₂；NEXTEL^TMFibers), and about 68% SiO₂) (ii) a AETB-8 (composition about 20% Al)₂O₃About 12% (14% B)₂O₃、72％Al₂O₃、14％SiO₂；NEXTEL^TMFiber), 68% SiO₂) (ii) a FRCI-12 (composition of about 78 wt% Silica (SiO)₂) And about 22 wt% aluminoborosilicate (62% Al)₂O₃、24％SiO₂、14％B₂O₃) ); and FRCI-20 (composition of about 78 wt% Silica (SiO)₂) And about 22 wt% aluminoborosilicate (62% Al)₂O₃、24％SiO₂、14％B₂O₃))。

In a preferred embodiment, the inorganic fiber composition consists of or consists essentially of fibrous silica, alumina fibers, and aluminoborosilicate fibers. In this embodiment, the fibrous silica comprises about 50-90% of the inorganic fiber mixture, the alumina fibers comprise about 5-50% of the inorganic fibers, and the aluminoborosilicate fibers comprise about 10-25% of the inorganic fiber mixture. In certain embodiments, the fibers used to make the substrates of the present invention may have both crystalline and glassy phases.

Other suitable fibers include aluminoborosilicate fibers, preferably containing alumina in the range of about 55 to about 75 weight percent, silica in the range of less than about 45 to greater than 0 (preferably less than 44 to greater than 0) weight percent, and boria in the range of less than 25 to greater than 0 (preferably about 1 to about 5 weight percent, each as Al₂O₃、SiO₂And B₂O₃The form is calculated based on the theoretical oxide. The aluminoborosilicate fibers preferably have at least 50% by weight crystallinity, more preferably at least 75%, and most preferably about 100% (i.e., crystalline fibers). Size-graded aluminoborosilicate fibers are commercially available, for example, from 3M company under the trade designations "NEXTEL 312" and "NEXTEL 440". Further, suitable aluminoborosilicate fibers may be prepared as disclosed, for example, in US3,795,524, the contents of which are incorporated herein by reference in their entirety.

Other suitable fibers include aluminosilicate fibers, typically crystalline, comprising alumina in the range of about 67 to about 77, e.g., 69, 71, 73, and 75 weight percent and silica in the range of about 33 to about 23, e.g., 31, 29, 27, and 25 weight percent. Sized aluminosilicate fibers are commercially available, for example from 3M company under the trade designation "NEXTEL 550". Furthermore, suitable aluminosilicate fibers may be prepared as disclosed, for example, in US 4,047,965(Karst et al), the contents of which are incorporated herein by reference.

In other embodiments, the fibers used to prepare the substrates of the present invention comprise the addition of Y₂O₃And ZrO₂α -Al of₂O₃And/or adding SiO₂α -Al of₂O₃(formation of α -Al)₂O₃Mullite).

Many particular materials are useful for preparing the catalytic substrate. In one embodiment, the material from which the substrate of the present invention is made comprises (consists of or consists essentially of) refractory silica fibers and refractory aluminoborosilicate fibers. In another embodiment, the material used to prepare the catalytic substrate comprises refractory silica fibers, refractory grade alumina fibers, and a binder, preferably boron oxide or boron nitride powder.

In one embodiment, the catalytic substrate of the present invention comprises (consists of or consists essentially of) an alumina-enhanced thermal barrier ("AETB") material or similar material known to those of ordinary skill in the art. AETB Materials are known in the art and are described more fully in Leiser et al, "Options for Improving structured ceramics heights", Ceramic Engineering and Science Proceedings, 6, No.7-8, pp.757-768(1985) and Leiser et al, "efficiency of Fiber Size and Composition on mechanical and Thermal Properties of Low Density Ceramic Composition information Materials", NASA CP 2357, pp.231-244(1984), all of which are incorporated herein by reference.

In another embodiment, the catalytic substrate comprises ceramic tiles, such as alumina-enhanced thermal barriers (AETB) with toughened monolithic fiber insulation (TUFI) and/or reaction-cured glass (RCG) coatings. Such materials are known in the art.

Another suitable material is Fibrous Refractory Ceramic Insulation (FRCI). In one embodiment, AETB is made from alumina boria silica (also known as alumina-boria-silica, aluminoborosilicate, and aluminoborosilicate) fibers, silica fibers, and alumina fibers. One known application of AETB is as exterior tiles on aerospace vehicles, which are ideal for returning aerospace vehicles to the atmosphere. AETB has the properties of high melting point, low thermal conductivity, low coefficient of thermal expansion, resistance to thermal and vibrational shock, low density, and very high porosity and permeability.

In one embodiment, the first component of AETB is alumina fiber. In a preferred embodiment of the present invention, alumina (Al)₂O₃Or alumina, such as SAFFIL) is typically in the form of commercial products of about 95 to about 97 weight percent alumina and about 3 to about 5 weight percent silica. In other embodiments, less pure alumina may also be used, such as 90%, 92%, and 94%. In other embodiments, higher purity alumina may also be used. The alumina may be produced by extrusion or by wire drawing. First, a solution of a precursor substance is prepared. A slow and gradual polymerization process is initiated, for example by controlling the pH, so that individual precursor molecules combine to form larger molecules. As this process progresses, the average molecular weight/size increases, resulting in an increase in solution viscosity over time. At a viscosity of about 10 centipoise, the solution becomes slightly tacky and can be applied to fibersDrawing or spinning. In this state, the fiber may also be extruded through the die. In certain embodiments, the average diameter of the fibers is in the range of about 1 to 6 microns, although larger and smaller diameter fibers are also suitable for use in the present invention.

In one embodiment, the second component of AETB is silica fiber. In certain embodiments, Silica (SiO)₂E.g., Q-fibers or quartz fibers) contain more than 99.5 wt.% amorphous silica and very low levels of impurities. Lower purity silicas, such as 90%, 95%, and 97%, are also suitable for use in the present invention. In certain embodiments, a composition having a low density (e.g., 2.1-2.2 g/cm) is used³) Amorphous silica with high heat resistance (1600 ℃), low thermal conductivity (about 0.1W/m-K), and near zero thermal expansion.

In one embodiment, the third component of AETB is alumina boria silica fiber. In some cases, alumina boria silica fibers (3 Al)₂O₃·2SiO₂·B₂O₃E.g., NEXTEL 312) is typically 62.5 wt.% alumina, 24.5 wt.% silica, and 13 wt.% boria. Of course, the exact percentages of the components in the alumina boria silica may vary. Mainly amorphous products but may also contain crystalline mullite. Suitable alumina boria silica fibers and methods for making the same are disclosed, for example, in US3,795,524, the teachings of which are incorporated herein in their entiretyWhich is incorporated herein by reference.

Other materials suitable for use as nSiRF-C in the present invention include: AETB-12 (composition about 20% Al)₂O₃About 12% (14% B)₂O₃、72％Al₂O₃、14％SiO₂；NEXTEL^TMFibers), and about 68% SiO₂) (ii) a AETB-8 (composition about 20% Al)₂O₃About 12% (14% B)₂O₃、72％Al₂O₃、14％SiO₂ NEXTEL^TMFiber), 68% SiO₂) (ii) a FRCI-12 (composition of which is about 78 wt.% silicon dioxide (SiO)₂) And 22 wt.% aluminoborosilicate (62% Al)₂O₃、24％SiO₂、14％B₂O₃) ); and FRCI-20 (which has a composition of about 78 wt.% silicon dioxide (SiO)₂) And about 22 wt.% aluminoborosilicate (62% Al)₂O₃、24％SiO₂、14％B₂O₃))。

In a preferred embodiment, the inorganic fiber component consists of or consists essentially of fibrous silica, alumina fibers, and aluminoborosilicate fibers. In this embodiment, fibrous silica comprises about 50-90% of the inorganic fiber mixture, alumina fibers comprise about 5-50% of the inorganic fibers, and aluminoborosilicate fibers comprise about 10-25% of the inorganic fiber mixture.

Fibers similar to those of AETB described herein may be used in addition to, or in place of, AETB fibers.

The production of fibers by melting can be carried out in two general ways. The first method involves centrifugal spinning in combination with gaseous attenuation. A glass stream of appropriate viscosity is continuously flowed from a furnace onto a bushing rotating at thousands of revolutions per minute. Centrifugal force projects the glass outward toward a spinning wall containing thousands of holes. The glass passes through these holes, is again driven by centrifugal force, and is attenuated by the hot gas stream prior to collection.

In the second melting technique, a heating tank with hundreds or thousands of holes (depending on the application) in the bottom surface is fed with a molten gas. The glass flows through the holes and is drawn to form individual fibers. The fibers are combined into a strand and collected on a mandrel.

In one embodiment, the AETB fiber mixture in the slurry preferably comprises three components, including glass fibers, alumina fibers, and alumina boria silica fibers. The fibrous silica comprises about 50-90% of the inorganic fiber mixture; the alumina fibers comprise about 5-50% of the inorganic fiber mixture; the alumina boria silica comprises about 10-25% of the inorganic fiber mixture. In other embodiments, the slurry comprises any mixture of fibers that can be used to prepare the substrate of the present invention as described above.

In a preferred embodiment, the fibrous component of the substrate is a mixture of 64% amorphous silica, 21% alumina and 15% alumina boria silica fibers, using trace amounts such as 0.3 to 1.0mg/m²The surfactant(s) aid in the dispersion of the bulk fibers in the slurry before and during casting.

In one embodiment, the fibers in the slurry are primarily inorganic fibers. Preferably, in one embodiment, the present invention does not use any carbon in forming the substrate.

Alumina-zirconia fibers may be added to the inorganic fiber mixture as a fourth component or as an alternative to other fibers.

Mixed fiber

In one step of an embodiment of the present invention, the fibers are mixed. Many known fiber mixing methods can be used to mix the fibers. Examples are high shear mixing which may be employed.

Heating fiber

In one step of the invention, the fibers are heated in a known manner. The fibers are first heated so that the fibers can be more uniformly chopped. The heat treated fibers are washed to remove all dust, debris and loose particles, leaving only the fibers ready for disposal.

In a preferred embodiment, the fibers are thermally cleaned.

Washing fiber

In one step of the present invention, the fibers are washed. In a preferred method, the fibers are washed to render the fibers substantially free of dust and particulates. In one embodiment, the silica fibers are washed in acid to remove impurities, rinsed, dried, and then heat treated to impart structural integrity.

Chopped fiber

In another step of the present invention, the fibers are chopped. The fibers used in the present invention are generally available in loose or chopped fiber form. Methods of chopping fibers are known in the art. Most processes are continuous processes that can process many fibers or strands simultaneously. Typically, the product is fed between a set of wheels or drums, one of which supports regularly spaced cutting blades. The fiber is cut to length as it is drawn through the cutter. While the specific manufacturing details of forming a preform from chopped fibers remain proprietary, the technology generally involves one of two production mechanisms: melting and sol-gel. The fibers are preferably heat treated prior to final chopping.

Preferably, the fibers are then cut to size. Suitable fiber lengths include, but are not limited to, about 0.1, 0.2, 0.3, 0.4, 0.5, or 0.6 inches. Other suitable lengths include 1/8 ", 1/4", and 1/2 ". Preferably the fibers are relatively uniform in size. In another embodiment, the fibers comprising the catalytic or filtration substrate have an average length of 1/4 inches (about one percent meter), a diameter of about 1 to 12 microns, or 1 to 6, or 10 to 12 microns, and a median fiber diameter of 3 microns. In a preferred embodiment, no particulate material is added, as it may block the pores. Fibers suitable for use in the present invention are commercially available, for example from 3M. Of course, in other embodiments, longer fibers are used.

Forming a slurry

In another step of the process of the present invention, a slurry comprising the fibers is prepared. Rather than extruding ceramic or wrapping a yarn or fabric around a porous core tube, the substrate may be prepared by a conventional sol-gel process. The method comprises the following steps: the well-mixed sol of inorganic fibers and colloidal solution is first drawn (by vacuum or gravity drawing) to a fiber mold to produce a sol or green body or billet.

Alternatively, an extrusion casting press process may be used, wherein the pressure is reduced to a negative value or a vacuum process. The vacuum process can form an inorganic fiber mat having an ultra-low density while maintaining its strength. The combination of sol-gel processes with pressurized or vacuum processes helps to produce exceptionally low densities, which is extremely beneficial for particulate filtration.

The fibers are mixed together in the slurry. In some embodiments, the slurry may contain 1 to 2 weight percent solids, flowing almost like water. Alternatively, the slurry may contain from about 0.5 to about 5 weight percent solids. Other weight percentages are also acceptable, as is known in the art.

The chopped fibers are mixed together in a slurry with a high shear mixer. Deionized water is preferably used in the slurry to avoid impurities that may melt or destabilize the fiber in use. In one embodiment, the slurry may be pumped through a centrifugal cyclone to remove fine glass and other contaminants, including high soda particles.

Alternatively, no more than 30 weight percent organic fibers or particles may be added to the fiber slurry. During the sintering phase of production, the organic fibers volatilize or burn off from the article. The fibers burn leaving voids that provide a path for the gas to escape. The permeability of the tile can be tailored by varying the type and proportion of the polymer fibers. The blank produced by this method is porous and can thus be cooled efficiently by introducing a bleed gas.

Adjusting viscosity

In another embodiment, the viscosity is adjusted to a suitable range. The higher viscosity prevents the fibers from "flattening out", i.e., laying flat or being oriented only in a substantially horizontal direction. Boron nitride may be added as a thickener to coat the fibers in preparation for high strength sintering. In one embodiment of the invention, boron nitride is added and alumina boria silica fibers are not used in the slurry.

Adding a dispersing agent

In one embodiment, the method comprises adding one or more dispersants to the mixture or slurry.

In one embodiment of the invention, one or more surfactants are added to the slurry during the process of the invention. The surfactant is present in an amount of about 5 to about 10 weight percent. The use of surfactants aids in the dispersion of the bulk fibers in the slurry before and during casting, thereby preventing the fibers from bunching together.

In one embodiment of the invention, one or more catalysts as described above are added to the slurry. The catalyst is added at this stage of the process to give a substrate in which the catalyst is impregnated within the porous material. In one embodiment, this configuration requires no further washcoating or catalysis.

Molding compound

In one embodiment, the slurry is poured into a mold to form a billet. The shape of the mold can be any desired shape. In certain embodiments, the shape of the mold will produce a substrate having a shape suitable for use in a catalytic converter or particulate filter. For example, the die may be cylindrical. Alternatively, the mold is pentagonal. It is preferred that the slurry not settle in the mould because the fibres can settle out. In one embodiment, vacuum suction is used to keep the fibers from settling and to keep the porosity and density of the material uniform throughout the blank. Vacuum suction techniques can be used to control the alignment of the fibers and the density of the green body from many directions.

As an example, in a rounded 24in 24X 24in (576 in)²) Blanks of catalytic or filter substrates were produced in a x 4in mold. Of course, larger or smaller sized blanks may be produced.

The material of the mold may be any material that is stable in the presence of water, including but not limited to metal or plastic. Other suitable materials include aluminum, PLEXIGLAS, and other composite materials. Aluminum is very durable for long periods of time, while PLEXIGLAS material is inexpensive and easy to machine. Suitable permeable surfaces are available in the form of fine metal screens. Greater than about 50in²May in some cases be preferred to use a backing or support structure to prevent sagging.

Some embodiments may require an anaerobic, i.e., oxygen-free, environment during casting. The oxygen-free atmosphere creates an environment that minimizes metal oxidation and uniquely strengthens the fiber bond. The wetted blank is placed in a chamber filled with ammonia gas, such as a large plastic bag. Ammonia gas is most commonly used because of its low cost and ready availability. Nitrogen and/or hydrogen may also be added. Nitrogen is preferred over hydrogen because hydrogen is active. In fact, any gas may be added as long as a reducing and oxygen-free environment is maintained. The gas is preferably supplied at a constant flow rate until the wetted sol blank forms a gel blank. At this point, the gas is turned off, exposing the gel blank to the open air, allowing the gas to escape.

The carbon or organic based shapes may be introduced into the green body as a pore-forming rod during the molding stage. Upon high temperature sintering, these rods can decompose leaving the desired plurality of channels.

Dewatering of sludges

In one embodiment of producing the billet, the slurry is placed in a closed mold, at least one dimension of which is adjustable and at least one wall of which is semi-permeable. The fibers are collected and bonded at the semi-permeable wall by applying a compressive force through the adjustable wall to expel water from the slurry through the semi-permeable wall. The compression is continued until the desired preform, i.e. blank size, is reached. This approach is generally limited to simple geometric shapes such as blocks or cylinders.

Gravity is generally insufficient as a driving force, and thus a vacuum pump is required. Vacuum pumps use little to no pressure. In some cases, vacuum dewatering is used, but the suction used is minimal. Vacuum serves as a sensitive means of accelerating the drying process to avoid increasing the density. Preferably with only moderate vacuum assistance.

More complex shaped billets may be prepared by other methods, for example, where the head of the slurry is placed and held above a semi-permeable template. A vacuum pump is used to create a low pressure outside the infiltration template. This pressure differential drives the water through the permeate template where the fibers are collected and bonded. This pressure differential is maintained until the desired thickness is reached. This process is suitable for applications where the desired substrate is highly curved, as a near net shape or near its final form of the blank can be produced.

Injecting or mixing multiple (two or more) slurry formulations and varying the vacuum rate(s) of the draw provides a billet with regions that are denser and/or physically different than other regions. The blank may have graded or different layers or cores of different chemical composition and density. The blank may have one or more zones, each zone having a unique shape, location, and desired physical properties. Each zone may vary in strength, thermal or electrical conductivity, catalyst adhesion capability, thermal expansion, vibration or thermal shock, weight, porosity and permeability, sound attenuation, or any other preferred property as desired.

The billet can also be delaminated using different slurry formulations and molding techniques. Further, the blank is not limited to only parallel planar layers such as layers on a cake, but may be formed into blanks having horizontal, angled, spherical, pyramidal, and free-form layers, or any other configuration known in the art. It should also be noted that the density of the blank may be altered chemically and physically during the process if desired.

A blank may also be formed by placing multiple blanks of any configuration (whether cured or uncured) of different chemical composition inside or within another blank. The core blank may be manually placed into the blank or injected into the core. The result is one or more cores of lower or higher density. The shape or form of these cores and blanks is not limited and is a combination of core laminations. The core may even be produced within the core. This process can be repeated an unlimited number of times to obtain a unique number of combinations of blanks of unlimited shape as desired.

Drying of green bodies

In one step of the embodiment, the slurry in the mold is dried for a sufficient time to dehydrate it, i.e., drive off any water it may contain. Gravity can be used to drain the water. Micro-vacuum assistance may be employed. Other methods known in the art may of course be used.

Removing the green body from the mould and drying the green body

In one step of an embodiment of the present invention, the green body is removed from the mold. The billet can typically be removed when it is sufficiently dry to enable processing. Alternatively, the billet is removed when it is sufficiently dry to be handled by the machine.

For example, when the blank is sufficiently dry to be processed, it is removed from the mold. The billet is then dried in an oven. A temperature low enough to complete the dewatering process and to allow the fibers to substantially retain their desired configuration is employed. Most preferably the temperature is sufficient to dry the blank as required but insufficient to cause any or substantially any sintering of the blank. In another preferred embodiment, a temperature of about 250-500F is used in this step. In yet another embodiment, the billet is dried at a temperature of about 180 ℃ for about 2 to about 6, preferably about 4 hours. Other times and temperatures known in the art may be used.

The dried billet may then optionally be soaked in a sol-gel binder, preferably an alumina sol-gel binder, at various temperatures for a period of time (e.g., several days), as is known in the art, while the billet "siphons" (i.e., absorbs) the binder solution into the billet. Suitable binders are known in the art and may be required to impart structural integrity to the preform as well as to facilitate sintering. The blank may utilize a single or multiple adhesive process to alter the strength and conductivity of the blank. Multiple applications of adhesive will increase the strength of the blank but may also reduce or plug the pores. Any suitable adhesive may be used. The binder may be an oxide binder such as SiO₂Or Al₂O₃. The oxide binder may also be a glass structure, a crystalline structure, or other inorganic binder. The adhesive may be applied using known techniques and methods, as disclosed in US3,549,473, the teachings of which are incorporated herein by reference in their entirety.

Drying (sintering) of green compact

In another step of an embodiment of the present invention, the green body is heat cured. The temperature for heat curing or sintering is generally higher than the temperature used for drying the green body. In one embodiment, the temperature is ramped up over one or more hours, preferably several hours, until the desired temperature is reached. In one embodiment, the oven is preheated and incrementally heated to about 2000-. Other temperatures known in the art are also suitable.

In a preferred embodiment, after the binder gels, the billet is cured by heating the billet to about 200F for about 4 hours, then slowly raising the temperature to about 600F over about 5 hours. After the maximum temperature is reached and maintained, the billet is rapidly quenched. The end result is a rigid inorganic fiber blank. The hot setting process of the billet can also vary in the temperature used, the length of the setting time, the quenching temperature and time, the temperature ramp up, and the timing of the ramp up temperature increase.

Firing the billet provides the energy required for fiber-to-fiber contact sintering, thereby forming a bond that imparts strength to the substrate. For example, increasing the number of fiber-to-fiber contacts may increase strength. Increasing the number of contacts increases density and twist. The more distorted the pore network, the lower the permeability. Sintering does not fuse the fibers together, but rather chemically bonds them. The billet is gradually heated in a high temperature furnace. The billet is preheated and then incrementally heated to about 2000 and 2500 degrees Fahrenheit until the desired density and fusion are achieved. In a preferred embodiment auxiliary chemicals such as thickeners are burned off. Leaving a substrate comprising or consisting essentially of sintered fibers.

In a preferred embodiment, the viscous (thickener) chemicals and dispersants are burned out.

In other embodiments, multiple curing steps are performed. This increases the hardness of the substrate.

The variables in the drying and curing process may be adjusted according to the density, strength, porosity or permeability, or high temperature resistance of the desired fiber blank. In certain embodiments, the curing process may employ multiple cures, and the time intervals and paths of heating and cooling may be varied. The blank may also be rapidly cooled to quench or temper the blank. The slurry may be subjected to additional heat or other treatments such as densified coatings or multiple curing and sintering.

Physical modification

In certain embodiments of the method, a catalyst is applied to the blank. In one method of applying a catalyst to a substrate, the substrate may be formed from a slurry containing the catalyst. Other suitable methods of applying the catalyst may be employed. Another advantage of the present invention is that it has been unexpectedly discovered that catalysts can be applied to nSiRF-C materials using methods that apply catalysts to other materials.

In another embodiment of the invention, the catalyst is added to the slurry prior to molding. In this case, a catalytic substrate is formed with the catalyst directly on the individual fibers that make up the substrate. In certain embodiments, this method of adding catalyst to the substrate provides an effective method of dispersing the catalyst within the core of the catalytic substrate without the catalyst being present only along the channel walls. In this embodiment, a washcoat is not necessary.

Machining

Blanks in the form of green blocks may be cut or sawn into a specified shape and then sanded, turned or machined into a "semi-finished product" of the final desired shape. While the composition of the material is readily recoverable to chemical, thermal and vibrational shock, in preferred embodiments the hardness is extremely low. This low hardness allows machining with little or no resistance or wear to the tool. Although the blank in certain embodiments is low in hardness and soft, it is very durable and easy to machine, engrave or form. The materials typically have a Mohs hardness of between 0.5 and 1.0 (or a Knoop hardness of 1-22), the softest being a talc Mohs hardness of 1(1-22 Knoop hardness), and the hardest being a diamond Mohs hardness of 10(8,000-8,500 Knoop hardness). For example, silicon carbide has a Mohs hardness of 9-10(2,000-2950 Knoop hardness). The blank is extremely soft and requires little effort to machine or engrave like styrofoam or light wood, relative to other known materials.

The blank may be formed, sanded, turned, or machined to form a semi-finished product of indefinite shape. The machining may include turning a cylinder on a lathe, hole sawing, band or clip sawing a shape, sanding a shape or polished surface, or any other machining method commonly used for other solid materials and known in the art. The blank can be machined to very tight tolerances with the same precision as metal, wood or plastic. If the blank is cast in a cylindrical die of the desired diameter in the final shape, the machining process need only cut and sand the cylindrical blank to the desired thickness. The process also reduces substrate loss due to over-machining and speeds up the pre-forming process.

There are many possible front and back surface shapes, including circular 510, oval 520, and racetrack 530, as shown in FIG. 5. Three-dimensionally, the substrate may be in the form of a cylinder or a substantially flat disk. Conventional substrates are one of these three designs. The right angle design is not very effective. Although easy to process, a square or angular design has proven to be a catcher for rust and corrosive substances such as snow-melting salts. Thus, a rounded corner is preferable for the front surface shape of the semi-finished product.

The blank or substrate or blank may be formed using a band saw, a jig saw, CNC, or other methods known to those of ordinary skill in the art. The semi-finished product may be further formed by hand rubbing, lathe sanding, belt sanding, or orbital sanding. The unloaded particles must be vacuumed out to prevent them from plugging the pores of the material. Moreover, these particles can enter the bearings of the drill press and damage the drill press, wear off and scuff the bearings. The ceramic dust is also fine and may be easily inhaled by the operator.

The shaped semifinished product is used as a substrate in the present invention. For catalytic applications, the surface area of the substrate is an important characteristic. The surface area is the sum of the areas that the exhaust gas must pass through when passing through the exhaust gas filter. The increased surface area means more space for chemical reactions between the pollutants and catalytic and thermal processes to occur, making the catalytic converter process faster and more efficient. Speed and efficiency may result in little to no plugging that may lead to exhaust system failure.

In one embodiment, the total surface area of the substrate of the present invention is 83.58 square inches per cubic inch. This translates into a much higher area that can be impregnated with the noble metal than cordierite samples having fairly macroscopic dimensions (e.g., diameter, length, and width). But it should be noted that this calculation of the total surface area does not even include the density, porosity and permeability of the different materials.

In an exemplary embodiment of the invention, the substrate is used in a diesel engine exhaust filtration system. The substrate was formed using an AETB formulation to produce approximately 13 "by 5" blanks having a density between 8 and 25 pounds per cubic foot. A cylindrical semi-finished product or an oval stud semi-finished product having a diameter of 6 inches and a height of 5 inches was cut out of the blank using a diamond tip or a tungsten carbide band saw. The semifinished product is further machined to precise tolerances to form the substrate on a self-rotating lathe (for right circular cylinders) or a plywood face sander.

Making holes and channels in a substrate

In one embodiment of the invention, a plurality of channels are formed within the filtering or catalytic substrate substantially longitudinally with respect to the intended gas flow. These channels extend partially or completely through the length of the substrate. Fig. 5-14 illustrate schematic diagrams of some embodiments of the invention having multiple channels. In certain embodiments, the channels are angled with respect to the direction of fluid flow.

The inner surfaces of these channels may be chemically coated to trap and treat more contaminants in a small volume of the substrate. Where channels are formed in the substrate, smaller diameter channels, such as 200, 400, 500, 600, 700, 800, 900, 1000, 1100, 1200, 1300, 1400, 1500, 1600, 1700, 1800, 1900, 2000, 2100, 2200, 2300, 2400, or 2500cpsi small channels are preferred to maintain a high surface area.

In another embodiment, the channel extends through the entire length of the substrate. The substrate has a flow-through configuration.

Alternatively, the channels do not extend through the entire length of the substrate but extend through about 50% to about 99% of the length of the substrate. Such substrates are considered to be in a wall flow configuration. The remaining undrilled portions of the channels of the wall flow substrate may have different thicknesses. FIG. 8 shows a wall flow substrate 820 having undrilled portions 840, 845 of different wall thickness, according to an embodiment of the invention. In this embodiment, alternate inlet channels have a wider wall thickness than the other inlet channels as well as the outlet channels. The different thicknesses of the unwritten portions may be configured in any combination to provide thinner or thicker unwritten portions of the inlet or outlet passages, wherein the thicknesses of all of the unwritten portions may or may not be substantially similar. The wall thickness is so thin and porous that the exhaust 830 passes from the exhaust inlet channel through the wall into the exhaust channel, trapping the exhaust particles. The length between the inner edges 850 and 855 of the non-drilled portion is referred to as the intersection. With some or all of the unwelded portions 840 of the incoming channels being thicker, the exhaust flow 830 may exit the substrate 820 through the channel walls of the substrate in the intersection region. The exhaust flow 830 may still pass through the thinner undrilled portion 845. In another embodiment of the invention, the non-drilled portions of the channels are selectively impregnated with catalyst so that the amount of catalyst is different from that on the channel walls.

The thickness of this unwritten portion is limited. The gas flow rate is increased by increasing the surface area of the wall of comparable thickness. If the undrilled portion is too thin, it may rupture due to additional back pressure.

Mechanical drilling

Once an embodiment of the substrate is cut and machined from the blank, it can be inserted into a drilling fixture for drilling. A plurality of channels may be drilled in the substrate substantially parallel to the major axis of the cylinder and the exhaust gas discharge flow direction. The smaller the channel diameter, the more channels can be disposed in the substrate.

In another embodiment, a via is drilled in a substrate. The substrate was placed in a metal jig for drilling. The clamp may be, for example, a pair of large metal walls that hold the substrate blank securely in place so that it does not move while not crushing the substrate. The clamp grips the substrate and holds it steady for drilling. After one side of the base material is drilled, the clamp is accurately rotated by 180 degrees to drill the other side of the base material. If not exactly rotated 180 degrees, the drilled passages will not be perfectly aligned or parallel. Furthermore, the pressure at the inlet needs to be substantially the same or similar to the pressure at the outlet. To ensure that the walls are parallel, the fixture must not move the substrate more than 0.0001 inches in any undesired direction.

The channels of the substrate of the present invention may be prepared by mechanical drilling. In one embodiment, computer numerical control ("CNC") drilling is utilized, which is common and preferred in machinery shops. CNC drilling is much slower and not economically feasible in a large scale manufacturing environment requiring thousands of filters to be produced per day. CNC drilling precision and accuracy are high. CNC drilling is done with multiple passes of the drill bit. Each CNC pass drills a bit deeper into the substrate and the drill bit removes the fibrous material as it exits.

The drill bit may be tungsten carbide, which may be tough and brittle, or a similar material known to those of ordinary skill in the art.

The drill bit penetrated at a feed rate of about 10 feet per minute. A slow feed rate is required to prevent the drill from melting. The drill bit melted as it penetrated at a feed rate of 25 feet/minute. Also, because the apertures are very large, the drill bit tends to walk or move. Slower penetration rates may solve this problem.

A slow rotating drill bit is preferred. The drill bit should be rotated at about 200 rpm. Rotating the drill bit at higher speeds, such as about 10,000rpm, may cause the drill bit to melt. The drill bit is kept cool throughout the drilling process with a lubricant such as water, alcohol or glycerol.

Once the substrate is cut and sanded to final size, channels are cut or drilled into the substrate. In this example embodiment, the channels are cut with DPSSL. Because the substrate is porous and permeable, the substrate need not be as thick as a conventional filter. In addition, thinner or smaller substrates are less expensive to produce because cutting a single blank may produce multiple substrates with a reduced amount of any coating or catalyst that needs to be applied.

Water drill

In another embodiment, the channels are formed using water cutting (or water drilling). Water cutting utilizes a fine water jet of very high pressure to cut holes in a substrate. But the water jet cannot be stopped during the cutting process so as to leave blind holes (i.e. channels that do not pass completely through the substrate). The physical characteristics of the water jet limit the size of the channel opening to a diameter no less than the diameter of the water jet. In certain embodiments, rectangular holes may be formed with water jets.

Pneumatic drill

In another aspect of the invention, the substrate is prepared by a gas drilling process. Gas drilling is known in the art and can be used with the substrates of the present invention to prepare channels within the substrate.

Comb press

In another embodiment, the channels are formed or shaped by a carding process. The comb is preferably a metal device having a plurality of tines that can be pressed (e.g., reamed) into the substrate. The comb for reaming includes a plurality of tines. The length, width, thickness, and shape of the tines can vary depending on the desired channel properties, configuration, and size.

In certain embodiments, the comb is pressed into the substrate substantially perpendicular to the surface of the substrate. In other embodiments, the comb is pressed into the substrate at an angle to the surface of the substrate. The use of a comb is a preferred method, particularly for forming blind channels. It will be appreciated that suitable combs can also be prepared such that the comb consists of multiple rows and columns, for example 4 x 4 or 16 x 16 tines.

Typically, the comb pressing process involves repeatedly pressing the comb into the substrate material multiple times until most or all of the channels are formed. This method is referred to herein as stepping. Optionally the comb is removed from the channel after each pressing so that excess matrix material can be removed from the channel by, for example, air. It is preferred to prevent fiber buildup during the step/reaming step. Fiber buildup can lead to wall rupture. To control this characteristic, the channels and bit surfaces may be cleaned with vacuum and/or compressed air.

In one embodiment, the comb is pressed into the substrate with a force sufficient to expel or dislodge an amount of matrix material from the channel walls. In a preferred embodiment, sufficient force is applied to the comb to extend the tines about 0.1 inches into the channel. Other suitable values include 0.05, 0.15, and 0.2. It is preferred that the force applied to form or shape the channels is sufficient to form or shape the channels without substantially damaging the walls of the channels. The method includes repeatedly pressing the tines into the substrate until a channel of a desired length and shape is created.

The shape of the tines determines the shape of the channel. For example, rectangular tines on a comb are used to form a rectangular channel with a rectangular channel opening.

Wedge-shaped tines on the comb are used to form a wedge-shaped channel. Wedge-shaped tines are used to create channels with channel walls parallel to the square opening. As shown in fig. 17, substrate 1700 contains parallel wedge-shaped "blind" channels 1702, i.e., channels without outlets. The closed channels 1702 force the gas 1704 through the pore channel walls and then out.

The four-sided pyramidal tines on the comb are used to form pyramidal channels. The walls are parallel and the opening is substantially square. But the wall thickness at the channel opening is minimal because the channels meet somewhere rather than being connected by a straight wall in front. This results in a reduction in front surface area and hence a reduction in back pressure. The comb is isolated by the four-sided pyramid-shaped sharp teeth without a thin gasket. In this embodiment, referring to fig. 16, a suitable comb has tines that taper rather than having flat ends. Of course, the present invention includes tines of various other shapes.

Tent-shaped pointed teeth on the comb are used to form the polygonal channel. The front surface area of the polygonal channel is minimal.

Referring to fig. 16, dimensions of an exemplary comb 1600 according to one embodiment of the invention are shown. Comb 1600 is approximately 6.000 inches long and 0.0308 inches wide. Comb 1600 includes a base 1610 from which a plurality of tines 1620 extend. The base 1610 is 0.4375 inches tall. The plurality of tines 1620 are 1.250 inches long and 0.0308 inches wide, spaced 0.010 inches apart.

In one embodiment of the carding process, the channels are first formed with a drill and are circular. To create a forming channel with parallel walls, according to one embodiment of the invention, the tines of the comb ream (i.e., squeeze or punch) the circular channel to create the forming channel. One embodiment of a comb 1500 is shown in fig. 15. The reaming is preferably performed on a CNC punch. The remaining indentations are the forming channels and channel openings. The wall thickness of the bore may vary as described above. In certain embodiments, the carding process produces a catalytic or filtration substrate having a channel wall thickness of from about 4 mils to about 20 mils, preferably from about 6 mils to about 10 mils.

In the comb process, the metal comb may be mounted in a CNC press for reaming in a box called a jig. Within the jig, the comb was isolated with a thin shim. The spacing between the combs is a low tolerance requiring the combs to be tightly held within the fixture to limit movement during reaming. Referring to fig. 16, a shim 1630 acts as a spacer for the comb 1600. Shim 1630 is sized to be 0.010 inches wide, 6.000 inches long, and 0.4375 inches high.

At least one mesh is preferably provided over the comb to maintain the tines aligned. Preferably the web is floating to distribute the alignment as required. In addition, the web is beneficial for tines of varying lengths, for example, from about 0.5 inches to about 6.0 inches long. The at least one web may be positioned at any location along the tines, such as floating, spring loaded, or fixed. The at least one web may float along the tines. The tines are not fixed to the at least one web, but rather the web is adjustable by placing the web on the tines. The at least one net may be spring loaded onto the tines. The web is spring loaded and the pressure of the substrate against the web maintains the distance between the tines near the edge of the substrate. The at least one web may also be secured to the tines at any location along the length of the tines.

Another embodiment of the invention is directed to a method of making a catalytic or filtration substrate having a plurality of channels comprising forming the plurality of channels in steps on the substrate with a comb. In a preferred embodiment, the process is a step-wise process. I.e. the entire channel is not formed by inserting the tines of a comb once. But rather the tines of the comb are repeatedly inserted and removed in small increments until the desired channel length is obtained. The dislodged matrix material is preferably removed from the channel between each step or every other step.

In another embodiment, the carding process is an automated process that utilizes machines and/or robots to form channels.

Method for making comb

There are many methods of making the comb used in the present invention. The comb may be made of materials including, but not limited to, stainless steel, tungsten, or key material. Methods of forming the comb include laser cutting, water cutting, and electrical discharge machining, or other forming methods available to those of ordinary skill in the art.

The comb may be manufactured with DPSSL. The comb can also be made by water cutting. For example, one embodiment utilizes a water cutting process to make thirty to forty combs at a time.

Electronic discharge machining ("EDM") is an alternative method of making combs. EDM is a thermal etching process that removes electrically conductive material by a series of repeated electrical discharges between an electrode and an electrically conductive workpiece in the presence of a dielectric liquid. EDM may similarly be used on the substrate if the substrate is made electrically conductive. EDM is of at least two types: (1) a ram and (2) a wire.

When using an EDM ram, i.e. a scoring die, the electrode/tool pair is connected to a ram which is connected to one pole (usually the positive pole) of a pulsed power supply. The workpiece is connected with the cathode. The workpiece is then positioned such that a gap exists between the workpiece and the electrode. A dielectric liquid is injected into the gap. Once the power is turned on, thousands of pulses of direct current or DC per second cross the gap, starting the erosion process. The resulting spark temperature may be in the range of 14,000 to 21,000 degrees Fahrenheit. As erosion continues, the electrode operates while maintaining the gap size constant.

The comb is preferably manufactured by wire EDM. The wire method uses a consumable charged wire as an electrode that creates complex cuts as it moves in a predetermined pattern around the workpiece.

If the wall is too thin, any burrs on the tines may tear the wall as it enters or exits during reaming. Therefore, the comb should be polished to remove any burrs or sharp edges that may catch on the fibers. Cutting and polishing the comb may generate heat, which may cause the comb to buckle. To ensure that the resulting holes are parallel and do not break, a tolerance of about 0.0001 inches is preferably maintained.

The comb used for reaming includes a plurality of tines. The length, width, thickness, and shape of the tines may vary depending on the properties of the desired channel. Referring to fig. 16, dimensions of a comb 1600 according to one embodiment of the invention are shown. Comb 1600 is approximately 6.000 inches long and 0.0308 inches wide. Comb 1600 includes a base 1610 from which a plurality of tines 1620 extend. The base 1610 is 0.4375 inches tall. The plurality of tines 1620 are 1.250 inches long and 0.0308 inches wide, spaced 0.010 inches apart.

Laser machining

Other methods include diode pumped solid state laser ("DPSSL") drilling; chemical lasers such as CO₂(ii) a Electron beam ("EB") drilling; or an electrode drill ("EDM"), or using other methods known to those of ordinary skill in the art. Any laser suitable for cutting comb material may be used.

The substrate may be cut using laser drilling, such as DPSSL drilling. The method uses a laser programmed with a CAD program to drill holes. The CAD program is loaded into the CAM program. The laser cuts with oxygen or preferably nitrogen in fine pulses. DPSSL can cut lanes at a rate of about 2,000 lanes per minute. In one embodiment, the diameter of the channel is about 100 nanometers. Laser drilling may be performed using known techniques and methods, as disclosed in US 4,686,128, the teachings of which are incorporated herein by reference in their entirety. In one embodiment, the process utilizes laser drilling to produce channels of about 0.5 inches or less in depth (or length).

In one embodiment, the channels created are large enough to allow the particles to enter but small enough to remove most of the particles from the exhaust stream.

Furthermore, in one embodiment, the matrix porosity is 97%, meaning that there is a large amount of space for gas to pass through the substrate. Such a large porosity also provides additional surface area for particle deposition.

Pulsed laser

Gator series	G355-3	G532-5	G532-10
					Wavelength of light	355	532	1064	nm
Average output power1)	3	5	10	W
					Pulse repetition frequency2)	0-15,000	0-15,000	0-15,000	Hz
Pulse energy1)	0.3	0.5	1	mJ
					Duration of pulse (FWHM)1)	15±3	15±3	15±3	Ns
Beam diameter (l/e)2)1)	1.0*	1.0	0.7	mm
					Space model	TEM00	TEM00	TEM00
M21)	＜1.2	＜1.2	＜1.2

1) Measured at a 10kHz repetition rate;

2)0-15,000Hz (decaying power). Triggering within 7500Hz to 15,000 Hz. The actual random firing mode, which is triggered off between 0 and 15,000Hz at maximum power mode, is optional. 3) The Gator laser utilizes a closed loop water system for temperature control.

Preferably, the matrix material is substantially free of impurities such as carbon when machined with a laser.

Die hole

In another embodiment, a substrate of the present invention is prepared with preformed channels in the blank. In this embodiment, a channel is created in the blank with a channel former. The channel model is a rod of suitable size and shape to form the desired channel when the green body is formed.

Different types of materials may be used for the channel model. For example, the channel model may be a very durable material, such as a metal or polymer that can withstand the temperature of the drying process. Once the green or final blank is formed, the rod is removed leaving a channel. The channels may be further machined as previously described.

Alternatively, in other embodiments, the rod is made of a material that vaporizes or decomposes upon exposure to a suitable radiation or heat source, such as a laser or heat. In another embodiment, the channel model is made of carbon, or carbon derivatives, or the like.

Detailed Description

In certain embodiments, the channels are drilled with a CNC drill, which is computer controlled to maintain consistency, as described below. The drilling process is carried out under constant spray water to prevent dust airborne which presents an OSHA hazard and may enter the drill bearings to destroy the drill.

The drilled substrate is optionally dried in an oven to remove or bake out any water or other liquid that may be present in the pores prior to application of any catalyst. The baking time is not critical. Sufficient time is allowed to remove most or substantially all of the water. The evaporation of water can be determined by simply weighing the substrate. The baking time mainly accelerates the dehydration process. After the filter element is heated at several different time intervals and the weight is stable, the substrate is ready for application of any catalyst or coating.

In a preferred embodiment, the channels of the substrate are prepared by drilling and then by comb-pressing. Because of the low thermal conductivity of the preferred substrate, most of the heat generated during the drilling and cutting process is reflected back to the drill bit away from the substrate when drilling the substrate. As a result, the drill bit may absorb some of the heat to expand, overheat, and/or melt. The drill bit is preferably cooled, preferably with water. In another embodiment, the drill is operated at a reduced rate of penetration, such as 200RPM, to minimize heat generation. Of course, other rates of penetration (faster and slower) are also suitable. In another preferred embodiment, the drilling is with a two or four or six sided drill with improved twist and bit (drill point) configuration.

Furthermore, in a preferred embodiment, the channel is drilled through multiple drilling. For example, a channel about 1 inch long can be prepared by drilling each time about 0.1 inch deep into the substrate until the final length is reached. Between the bores, the matrix material drilled in the channels may be removed.

Center punch and locating hole

The step-wise approach is used because the material drilled by the drilled-out chopped fibers must be removed.

In a preferred embodiment, a portion of the blind channel is drilled deeper than the intended depth so that the fibers can be loaded into the extra area during the carding process. The comb is designed to enter a prescribed depth of wall flow configuration with additional voids to accommodate any loose substrate remaining in the channel.

The product obtained by the method

In another embodiment, the invention relates to a product made by the process described herein. In particular, the present invention relates to a catalytic substrate prepared according to any of the embodiments described herein. In another aspect, the present invention relates to a filtration substrate prepared according to any of the embodiments described herein.

Applications of

Various embodiments and applications of the present invention are discussed below. These application examples are discussed only for illustration and not to limit the scope of the invention. Any of the embodiments of the catalytic substrate and filtration substrate described above may be used in a variety of applications.

Catalytic converter

In another embodiment, the invention relates to a catalytic converter comprising the catalytic substrate of the invention. The catalytic converter of the invention can be used in an engine exhaust system in a manner similar to the use of known catalytic converters. Of course, the catalytic converter of the present invention has advantages over prior art catalytic converters. Because of these advantages, the catalytic converter can be used in a manner that known catalytic converters cannot be used.

Any of the embodiments of the substrate of the present invention described above may be used in one or more specific applications, such as catalytic converters. In one embodiment, the catalytic converter comprises a catalytic substrate of the present invention; a mat layer surrounding the catalytic substrate; and a can, preferably a metal can; and optionally a washcoat.

Another aspect of the invention relates to a catalytic converter disposed in or adjacent to an exhaust manifold of an engine exhaust system, the converter comprising a catalytic substrate of the invention. Such catalytic converters are referred to as manifold catalytic converters (other terms include manifold catalytic converters, manifold converters, etc.). The manifold catalytic converters of the present invention include those known in the art in which prior art substrates are replaced with catalytic substrates of the present invention. Such manifold catalytic converters are disclosed in, for example, US6,605,259 and 5,692,373.

In another embodiment, the present invention is directed to an improved catalytic converter, the improvement comprising the novel substrate described herein. Any embodiment of the substrate may be used in the improved catalytic converter.

In another embodiment, the present invention relates to an improved catalytic converter for treating exhaust gas from an internal combustion engine comprising a substrate, a metal oxide washcoat, and at least one catalyst adhered to metal oxide particles, the improvement comprising a substrate comprising an nSiRF-C composite and a catalytic metal.

In another embodiment, the present invention is directed to an improved catalytic converter for treating the exhaust gas of an internal combustion engine comprising a substrate, a metal oxide washcoat, and at least one catalyst adhered to metal oxide particles, the improvement comprising a substrate comprising an nSiRF-C composite and a catalytic metal.

In another embodiment, the present invention is directed to an improved catalytic converter for treating the exhaust gas of an internal combustion engine comprising a substrate, a metal oxide washcoat, and at least one catalyst adhered to metal oxide particles, the improvement comprising a substrate comprising an AETB composite.

In another embodiment, the invention is directed to a main catalytic converter having a catalytic substrate comprising an nSiRF-C composite and a catalyst. The main catalytic converter (sometimes referred to as an underfloor catalytic converter) is located partially or entirely within the engine head. In one embodiment, the main catalytic converter comprises a catalytic substrate of the present invention, wherein the substrate has a density of about 12lb/ft³The porosity is about 97%, which has low thermal expansion, high structural integrity, and low thermal conductivity. In a preferred embodiment, the main catalytic converter comprises a substrate having a wall thickness of about 6 mils at about 600 cpsi. The main catalytic converter in this embodiment has a wall flow configuration. In a preferred embodiment, the main catalytic converter has a substantially box-shaped channel shape (varying in length across the substrate) with substantially square openings (or wells). In a preferred embodiment, the catalytic substrate of the main catalytic converter is made by a comb-press process. Further, in this embodiment, the catalytic substrate comprises an alumina washcoat. In this embodiment, the main catalytic converter is capable of catalyzing the oxidation and reduction of pollutants, such as energetic oxygenCatalysts for the conversion of contaminants and also catalysts capable of reducing contaminants. The tank of the main catalytic converter is prepared by forging. A kind ofIn a preferred embodiment, the main catalytic converter comprises two substrate units. In certain embodiments, the main catalytic converter is used alone or in combination with a pre-catalytic converter. In a preferred embodiment, the main catalytic converter comprises an expanded mat. The main catalytic converter can be used for all internal combustion engines. The main catalytic converter may be used with a fuel borne catalyst. In addition, the substrate of the main catalytic converter may be protection-enhanced.

In certain embodiments, the main catalytic converter of the present invention, as described above, may also be used with one or more aftertreatment systems. These aftertreatment systems include NOx adsorbers, HC adsorbers, and SCR systems, among others.

Further, embodiments having the same or similar configurations and properties as the main catalytic converter described above may be used for the thin film catalyst. The thin film catalyst comprises a catalytic substrate having a thin film configuration as described above.

In another embodiment, the invention is directed to a front end catalytic converter having a catalytic substrate comprising an nSiRF-C composite and a catalyst. The front end catalytic converter is partially or completely positioned in the engine head. In one embodiment, the front end catalytic converter comprises a catalytic substrate of the present invention, wherein the substrate has a density of about 12lb/ft³The porosity is about 97%, which has low thermal expansion, high structural integrity, and low thermal conductivity. In a preferred embodiment, the front end catalytic converter comprises a substrate having a wall thickness of about 6 mils at about 600 cpsi. The front end catalytic converter in this embodiment has a wall flow configuration. In a preferred embodiment, the front end catalytic converter has a substantially pyramidal channel shape with substantially square openings (or holes). In a preferred embodiment, the catalytic substrate of the front-end catalytic converter is formed by a comb-press method. In this embodiment, the front end catalytic converter is capable of catalyzing the oxidation and reduction of the pollutants, such as with a catalyst capable of oxidizing the pollutants and also with a catalyst capable of reducing the pollutants. In certain embodiments, the front end catalytic converter is used alone or in combination with a pre-catalytic converter. One kind of optimizationIn an embodiment, the front end catalytic converter includes a hybrid mat layer. The front-end catalytic converter can be used for all internal combustion engines.The front end catalytic converter may be used with a fuel borne catalyst.

One or more front-end catalytic converters may be used with the same engine. There are one or more of the following advantages to using the front end catalytic converter of the present invention: the weight of the underfloor exhaust system is reduced; the filtering action of exhaust gas particulates that would otherwise be absorbed by the intercooler is increased, so that the life of the intercooler is improved; no cushion layer is needed; the rattle in the heat shield is reduced; the size of the muffler is reduced; the burning-out of the particles is improved; in some embodiments, in the event of a failure of one front-end catalytic converter, the exhaust gas may still be effectively treated with three more on other operating front-end catalytic converters, such as a 4-cylinder engine. The front end catalytic converter is beneficial for boats, ships, motorcycles, small handheld engines, drop leaf blowers, and related engines, and other applications where a non-exposed catalytic converter is preferred.

In another embodiment, a catalytic converter of the present invention may be interposed between the front end and the exhaust manifold, as shown in fig. 43. In this embodiment, the catalytic converter is partially disposed between the engine head and the exhaust manifold. An advantage over conventional systems is that the converter is very close to the combustion chamber, thereby improving efficiency. For example, this embodiment may be adapted to all engines with catalytic converters installed on Ford 4.6 liters. This in turn means that it can be installed in all other products such as Lincoln products for FordExplorer, Mustang, Crown Victoria, Econoline, 150/250/350pickup, Expedition, and Ford-mounted engines. The catalytic converter may also be installed in certain embodiments in different model years in which it has been used for many years. Such a 4.6 casting is available for millions of vehicles in the united states alone. It is also friendly to the incorporation of oxygen sensors.

In another embodiment, the invention is directed to a post-catalytic converter having a catalytic substrate comprising an nSiRF-C composite and a catalyst. In another embodiment, the invention catalyzes a processThe carburetor is a post-catalytic converter. The post catalytic converter is located after the main catalytic converter. In one embodiment, the post-catalytic converter comprises a catalytic substrate of the present invention, wherein the substrate has a density of about 12lb/ft³The porosity is about 97%, which has low thermal expansion, high structural integrity, and low thermal conductivity. In a preferred embodiment, the post-catalytic converter comprises a substrate having a wall thickness of about 6 mils at about 600 cpsi. As described later in this embodimentThe catalytic converter has a wall flow configuration. In a preferred embodiment, the catalytic substrate of the post-catalytic converter is made by a comb-press process. In a preferred embodiment, the post-catalytic converter has passage holes of different shapes, including triangular, square, and hexagonal. Also, the channel shape may vary. In this embodiment, the post-catalytic converter is capable of catalyzing the oxidation and reduction of the pollutants, such as with a catalyst capable of oxidizing the pollutants, and also with a catalyst capable of reducing the pollutants. In certain embodiments, the post-catalytic converter is used alone or in combination with a pre-catalytic converter. In a preferred embodiment, the post-catalytic converter comprises a non-intumescent mat. The post-catalytic converter can be used for all internal combustion engines. In another embodiment, the post-catalytic converter is not used with a fuel borne catalyst. Typically, the post-catalytic converter of this embodiment is placed near the standard muffler location, but other locations are possible. In an alternative embodiment, the post-catalytic converter is incorporated into a muffler. Such embodiments may include: a) the substrate itself acts as a muffler instead of a muffler, or b) the substrate is placed within a typical metal muffler assembly so that it is incorporated into a muffler.

In another embodiment, the invention relates to a Diesel Oxidation Catalyst (DOC), wherein the substrate of the DOC is a catalytic substrate as described herein. In a preferred embodiment, the substrate of the DOC of the invention is AEBT or OCBT, preferably AEBT-10, AEBT-12, AEBT-16 or OCBT-10. The DOC embodiment has a catalyst selected from the group consisting of palladium, platinum, rhodium, mixtures thereof, and derivatives thereof.

Other suitable embodiments include catalytic DPFs comprising the catalytic substrate of the present invention, preferably the substrate comprises an AETB material such as AEBT-12, and further comprises a catalyst.

Particulate filter (DPF, DPT)

In another embodiment, the invention relates to a particulate filter comprising the catalytic substrate of the invention. The particulate filter of the present invention may be used in an engine exhaust system in a manner similar to that using known catalytic converters. Of course, the particulate filter of the present invention has advantages over prior art catalytic converters. Because of these advantages, the catalytic converter can be used in a manner that known catalytic converters cannot be used.

In another embodiment, the present invention is directed to an improved particulate filter, the improvement comprising the novel substrate described herein. Any embodiment of the substrate may be used in the improved particulate filter.

In another embodiment, the present invention is directed to an improved particulate filter for treating exhaust gases of internal combustion engines comprising a filtration substrate, the improvement comprising a substrate comprising an nSiRF-C composite having a plurality of channels extending into and optionally through the substrate. The configuration of the channels may vary, as previously provided.

In another embodiment, the present invention relates to an improved particulate filter for treating exhaust gas from an internal combustion engine comprising a filtration substrate, the improvement comprising said substrate comprising an nSiRF-C composite having from about 100 to about 1000, preferably about 600 channels extending partially through said substrate, wherein said substrate has a wall flow configuration.

In another embodiment, the present invention is directed to an improved particulate filter for treating exhaust gas from an internal combustion engine comprising a substrate, and a metal oxide washcoat, the improvement comprising a substrate comprising AETB.

In another embodiment, the invention relates to a Diesel Particulate Filter (DPF) having a filter substrate comprising an nSiRF-C composite as described above. The filter substrate is configured to be suitable for use in a DPF. The DPF is partially or completely positioned in the engine head. A kind ofIn embodiments, the DPF comprises a filtration substrate of the present invention, wherein the substrate has a density of about 12lb/ft³The porosity is about 97%, which has low thermal expansion, high structural integrity, and low thermal conductivity. In a preferred embodiment, the main catalytic converter comprises a substrate having a wall thickness of about 6 mils at about 600 cpsi. The main catalytic converter in this embodiment has a wall flow configuration. In a preferred embodiment, the main catalytic converter has a substantially box-shaped channel shape (varying in length across the substrate) with substantially square openings (or wells). In a preferred embodiment, the catalytic substrate of the main catalytic converter is made by a comb-press process. Further, in this embodiment, the catalytic substrate comprises an alumina washcoat. In this embodiment, the main catalytic converter is capable of catalyzing the oxidation and reduction of the pollutants, for example, there are catalysts capable of oxidizing the pollutants and there are also catalysts capable of reducing the pollutants. The main catalytic converterThe can of (a) is prepared by forging. In a preferred embodiment, the main catalytic converter comprises two substrate units. In certain embodiments, the main catalytic converter is used alone or in combination with a pre-catalytic converter. In a preferred embodiment, the main catalytic converter comprises an expanded mat. The main catalytic converter can be used for all internal combustion engines. The main catalytic converter may be used with a fuel borne catalyst. In addition, the substrate of the main catalytic converter may be protection-enhanced. The protective coating may be applied to the inside or outside surface of the substrate.

Can type

The catalytic converter of the present invention has a tank. The tank may be prepared according to methods known in the art. Furthermore, the canister of the catalytic converter or particulate filter of the present invention may be made of materials known in the art, such as steel.

In a preferred embodiment, the catalytic converter of the present invention has an outlet pipe which is connectable to the tailpipe of a commercially available vehicle. Preferably the catalytic converter fits a tailpipe of about 2.5 or 3 inches in diameter.

For example, suitable cans include those made by any of the following methods: clam shell, bundling strapShoe box, padding, and forging. The above canning method utilizes two different clearance control mechanisms: (1) fixing the gap and (2) fixing the can filling force. From the perspective of the welding process, these processes produce converters with one or two seams. These classifications are shown in the following table (Rajadurai 1999).

	Fixed clearance	Force of fixation
			Single joint	Stuffing and forging	Binding belt
Double seam	Clam shell	Shoe box

Closing the can with a holding force provides more accurate gap density control by eliminating the dimensional tolerance effects of the substrate, can, and mat itself. Closing the tank to a fixed gap has the advantage of producing a converter of fixed final dimensions, which simplifies the converter design, mainly in terms of welding of the cone to the final tank.

Circular or elliptical converters with low aspect ratios generally prefer a single seam design, providing a uniform gap density distribution. The single seam shell also provides greater manufacturing flexibility and lower tooling costs. High aspect ratio elliptical converters typically require a double seam design. In this case, the stamping of the reinforcing ribs into the shell prevents deformation thereof and resulting gap non-uniformity. The double-seamed shell is produced by a stamping process, which is very expensive to manufacture and requires high production.

Clam shell

In one embodiment, the catalytic converter of the present invention includes a canister made using clamshell technology. In another embodiment, the particulate filter comprises a canister manufactured using clamshell technology. In north america, the clamshell is traditionally the most common design for underfloor converters in passenger cars and light trucks. The configuration of the clamshell type catalytic converter is shown in fig. 6. The ceramic catalytic substrate is wrapped in a mat layer and placed at the bottom of the shell. The other symmetrical part of the shell is then placed on top, pressed together and welded.

The tongue design is used to secure the cushion to prevent exhaust gas from bypassing the substrate. The converter described above further includes an end seal. The seal serves here to protect the cushion from gas impact and erosion, rather than from leakage. Most converters using a mat do not have end seals. If only a wire mesh mounting is used instead of a backing layer, an end seal is required, at least on the inlet face of the substrate.

Clamshell converters are typically equipped with an external heat shield. Internal insulation designs have also been developed in which clam shell stampings are lined on the inside with an additional layer of insulation.

Older catalytic converter designs included support rings or deep pockets within clamshell stamped articles that prevented axial movement of the substrate within the can. In a properly designed converter, an inflated mat with high bearing pressure is used, which is not required. There are many automotive converter substrates that are not axially supported and still exhibit high durability. But larger and heavier substrates or non-expanding cushions using lower bearing pressures may require axial support. Another consideration is erosion of the underlayer. The shape or end taper of the converter housing should be designed to protect the mat from direct impingement by the hot exhaust gases. Some converter manufacturers improve the corrosion resistance of the edges of the blanket exposed to the gas by impregnating them with chemicals. The high bearing pressure of modern converters also improves the corrosion resistance of the mats.

Many automotive applications use converters of a dual monolith construction. Two or more monoliths may be used due to manufacturing limitations on monolith length or to incorporating different specifications of catalyst within one converter. In most converters of the double monolith construction, the substrates are separated by a space, which is maintained by forming a separation pocket in the clam shell press. In some designs, the spacing between the substrates is maintained by metal or ceramic rings. A butt-joint block arrangement without a gap therebetween is also possible. Some gasoline engine commercial converters (Kuisell, R.C., 1996, "Butting monooliths in catalytic converters," SAE 960555) employ a butt design with a smaller pressure drop than the gap design.

The geometry of the converter shell must provide the required cushion compression. The clamshell profile includes stamped stiffening ribs to provide the desired rigidity and uniform pressure distribution. This is particularly important for flat oval catalyst substrates. Care should be taken when designing the ribs that there are no areas of excess pressure that could cause damage to the substrate or the mat. The clamshell method requires high dimensional tolerances for the overall structure and the stamped clamshell product. During clamshell canning the cushion compression continues until the half shells close, creating a certain gap thickness. The gap thickness depends on the overall structure and the dimensions of the shell. Thus, any variation in overall structural dimensions results in a change in mat density and consequent change in canning pressure, which can lead to converter durability problems.

Strapping is the most common method that directly controls the holding pressure during the canning process. The most robust catalytic converter can be produced because the straps are not sensitive to dimensional differences that may exist in the substrate monolith structure. In practice, the strapping process is limited to circular or near-circular catalyst substrate cross-sections. Its applicability to automotive converters of either elliptical or flat elliptical shape for use under the floor is very limited. The strap is once again popular with european automobile manufacturers, but as the automobile converter moves from under the floor to a location immediately adjacent the engine, it becomes more versatile in north america. The strapping is also suitable for large-diameter catalytic converters for heavy-duty diesel engines.

In the strapping technique, the base material is first wrapped in a tongue-and-groove shaped backing layer. The wrapped monolithic structure is then placed in a longitudinally split can. The can is rolled from a rectangular sheet of metal. The rectangular portion below the overlap portion is typically chamfered. In some designs, the can overlap is formed by an additional stamping operation to form a protruding lip to provide space for the can rim under the overlap. This design prevents the inner edge of the can from cutting into the liner or creating localized pressure build-up that can damage the can components, especially when a thin liner is used. The can with the wrapped monolith is then placed in a strapping machine, applying a controlled force to the assembly. While still under pressure, the can is spot welded, removed from the strapping machine, and seam welded. Push-out tests are sometimes performed as quality assurance measures. The axial displacement of the overall structure resulting from the application of the control force is measured in a dedicated test device. Finally, the converter header or end cone, and the flanges and/or ports are welded onto the converter block in a separate operation. The final assembly can be tested for solder quality by pressurizing with air while immersed in water.

The strapping machine includes a steel band ring for applying a force to the can components. One end of the ring is rigidly connected to the machine and the other end is pulled by a pneumatic or hydraulic brake. Vibration is applied during canning within some machines to minimize closing forces and ensure a more uniform pressure distribution.

The actual canning force required to achieve a target fixed density for a given mat can be determined by a series of tests. Several converters are closed with different closing forces. The canning force should be selected to produce the desired mat density. It is important that the strapping machine produce a repeatable closing speed and time pattern due to mat pressure relaxation. After the target closing force is reached, the machine should hold the can in a constant position, allowing spot welding to be performed, not at a constant force. Applying a constant force to the can when the mat relaxes pressure will result in over-compression of the mat.

Shoe box technology uses a two-part shell, similar to the clamshell method. But the shells are closed under a fixed force, the edge of one of the half-shells overlapping the edge of the other half-shell. Thus, the shoe box has the advantage of a sturdy package of straps in that it is insensitive to dimensional tolerances with the substrate.

Reinforcing ribs may be stamped into the shoe box. Thus, the technique can be used to can flat oval substrates where the strap is not suitable.

Packing

In the stuffing technique, the mat-wrapped monolith is pushed into a cylindrical can. The can is typically made from a length of tube but may also be rolled and welded from sheet metal. Non-cylindrical shapes (e.g., trapezoidal) are also possible. The method can be used for a converter of a small passenger car and a large converter for a heavy engine. Smooth insertion of the overall structure is promoted by a packed cone (Li, F.Z., 2000, "the Assembly Deformations and Pressure of filled Catalytic conversion for the hystersis Behavior of Pressure vs. Density Cure of internal Material Mat", SAE 2000-01-0223). After the operation is completed, the end cones are welded at the two ends of the cylinder to complete the tank assembly.

Although the plugged converter looks similar to the strapping assembly, the actual substrate holding mechanism is the same as the clamshell design. In particular the mat holding pressure depends on the geometry of the shell and the overall structure. Therefore, the plugging technique requires high reproducibility of the diameter of the substrate.

Corning (Eisenstoncock, G., et al., 2002, "Evaluation of software for Use in Packaging Ultra thin Ceramic Substrates", SAE2002-01-1097) proposes a modification of the plugging technique called soft-mounting technique. The objective is to minimize the highest pressure of the mat during plugging so that a lower strength ultra thin walled substrate can be canned. It is critical to use a tapered cylindrical tool called a mandrel placed in front of the substrate to induce the highest pressure of the mat during insertion.

In the soft mounting method, the cushion layer is inserted into the tank, and the tank is fixed on the flange in the process. The mat-lined can is then pushed down over the mandrel and substrate (i.e., the mandrel is positioned over the substrate). The inward beveling of the mandrel ends facilitates insertion into the can-liner assembly. The mandrel presses the mat against the can as it passes. The substrate is not subjected to the instantaneous maximum load required to extrude the mat as it moves into position inside the can instead of the mandrel.

Forging

In a forged converter, the converter shell is machined to the desired diameter after the mat-wrapped substrate has been inserted. Forging is a relatively new packaging technique and is done in fully automatic CNC control equipment suitable for mass-produced passenger car applications. Forged converters can be made from a length of tube and its end cone, which are obtained by rotary forming in the same production equipment.

The gap control mechanism can be classified as constant gap thickness, as in the case of packing, but the CNC control line can automatically calculate the substrate diameter difference. The forged converter must first be made to a diameter slightly smaller than the target diameter of the final product, allowing the shell to "jump back" after machining. This is a disadvantage of this method, which can lead to excessive peak pressures and substrate damage during canning.

The catalytic converter header provides a transition between the inlet and outlet tubes and the substrate cross-section. Most converter headers are conical or funneled with axial flow. Other designs such as truncated headers (Wendland, D.W., et al., 1992, "Effect of Header traversal on Monolith converter Emission Control Performance", SAE 922340) or headers with tangential gas inlets may also be used but are not commonly used. The purpose of the inlet header is to diffuse the inlet flow, i.e. to reduce the gas velocity and increase its static pressure with the least possible total pressure loss. In practice, the total header losses may be 10% to 50% of the total converter pressure drop, depending on geometry and flow conditions. These pressure losses can be minimized by designing the converter inlet header to provide a more uniform flow distribution. There is also a notion that the flow distribution within a catalytic converter is uniform to improve its emissions performance and/or durability. In one embodiment of the invention, the catalytic converter or particulate filter has a header with an angle of about 30%.

Cushion layer

The catalytic converter or particulate filter of the present invention may also optionally include a mat layer. Any of the embodiments described above or below may include a backing layer. In certain embodiments, the present invention further comprises a blanket (or mat or batting). For example, in one embodiment, the catalytic converter of the present invention comprises a catalytic substrate, a mat, and a canister as described above. Underlayments suitable for use in the present invention are known in the art.

The underlayer in certain embodiments can be selected based on a number of attributes described herein and known in the art. The catalytic converter canister is preferably designed to provide the desired holding pressure for a given catalytic substrate and a given mat layer. The seating pressure of the mat increases exponentially as the mat compresses from its initial bulk density to its final target density. The fixed pressure showed viscoelastic relaxation, i.e., the highest initial pressure occurring at canning was significantly reduced by mat fiber rearrangement the first few seconds or minutes thereafter (Myers 2000). The anchoring pressure loss of the expanded cushion due to relaxation varies between 30 and 60% of the initial maximum anchoring pressure.

Due to the slack in the mat, and the pressure loss in later use, fixed pressure is not a convenient parameter for canning process standards. And a fixed density, often referred to as the Gap Bulk Density (GBD), is typically used for this purpose. The exact density for a given application should be in agreement with the shim manufacturerThe quotient is called basis weight. Weight/area in g/m²Or kg/m²Expressions (since these are units of mass rather than weight, the customary term "mass/area" is strictly applied instead of "weight/area"). Useful mat weights/areas are 1050 to 6200g/m²In the range, the uncompressed thickness is between 1.5 and 10 mm. The automobile converter is usually used at 3000-4000g/m²The expanded mat of (1). More demanding applications or large converters recommend using higher mat weights, such as 6200g/m²(6.2kg/m²)。

Another important property of a catalytic converter mounting mat is its weight/area ratio, sometimes also referred to as basis weight. Weight/area in g/m²Or kg/m²Expressions (since these are units of mass rather than weight, the customary term "mass/area" is strictly applied instead of "weight/area"). Useful mat weights/areas are 1050 to 6200g/m²In the range, the uncompressed thickness is between 1.5 and 10 mm. Automobile steering wheelThe chemical reactor is usually used at 3000-²The expanded mat of (1). More demanding applications or large converters recommend using higher mat weights, such as 6200g/m²(6.2kg/m²)。

The packing cushions may be attacked by hot exhaust gas impingement. Erosion resistance is an important characteristic of the underlayer. Erosion resistance is strongly dependent on the bulk of the gap. (Rajadurai, S. et al, 1999, "Single sea stuffied Converter Design for Thinwall shows", SAE 1999-01-3628).

Many other properties of the anchor pad have been specified and/or tested and are available from the pad layer manufacturer. Examples of such properties include thermal conductivity, gas tightness, and coefficient of friction.

In designing a fixation system, the following considerations are taken into account in certain embodiments:

fixing pressure: assuming that the fixed mat is the only means of connecting the substrate to the shell (i.e., the converter has no end seal or support ring), the mechanical coupling is provided by a combination of radial pressure and friction on the mat surface. The holding pressure is the minimum pressure required to hold the substrate in place.

The maximum fixed pressure. As previously mentioned, the cushion layer has the same properties as a viscoelastic solid, creating a peak holding pressure during initial compression, and then gradually relaxes to a residual holding pressure. In thin-walled substrates, the maximum pressure may cause the catalyst core to fail during packaging. This transient behavior of the mat, which relies on constant force as opposed to constant gap size, must also be considered when designing canning methods, such as the strapping method.

Temperature characteristics. For an intumescent mat, the mat pressure is dependent on the temperature sufficient to activate the vermiculite. Vermiculite activation requires an inlet temperature of at least 500 ℃; higher inlet temperatures may be required depending on the heat transfer conditions within a particular system. In gasoline applications, the vehicle underbody is activated within the first few hours of engine operation. Oven treatment of catalytic converters may be required in diesel applications, where exhaust gas temperatures may never reach sufficiently high levels during normal vehicle operation. Vermiculite expansion is partially reversible, causing the mat to expand when the temperature increases and to contract when the converter cools. This property of vermiculite more than offsets the expansion of the converter shell, producing very high holding pressures at higher temperatures. In contrast, non-intumescent mats exhibit a near constant fixed pressure over the temperature range. The slight decrease in pressure with increasing temperature is attributable to the expansion of the gap due to thermal expansion of the converter shell. At temperatures above 500 ℃, the intumescent mat provides a higher holding pressure than the non-intumescent mat. But at temperatures below 500c the fixation pressure from an intumescent mat is actually much lower than the fixation pressure from a non-intumescent mat. Thus, a non-intumescent mat is a preferred mounting material in many diesel applications where the converter inlet temperature is kept below 500 ℃. An intumescent mat with a low vermiculite content creates a fixed pressure between a conventional intumescent mat and a non-intumescent mat. The hybrid mats exhibit pressure levels similar to the non-intumescent mats, but they maintain a certain pressurization at high temperatures, counteracting the gap expansion.

The gap expands. When the converter is exposed to high temperatures, the gap thickness increases due to the difference in thermal expansion coefficient between the substrate and the shell. Thermal expansion of the gap can be a significant source of fixed pressure loss. Void swelling is particularly important in applications where non-swelling mats are used, as it cannot be counteracted by vermiculite swelling. As a Design criterion, the gap expansion should be kept below 10% (Olson, J.R., 2004, "Diesel Emission Control Devices-Design Factors influencing Mount Mat Selection," SAE 2004-01-1420).

The gap expansion depends on the following design factors:

diameter of the base material: the larger the substrate, the higher the resulting gap expansion rate. Thus, clearance expansion may still be a problem in heavy duty diesel applications, despite the lower converter temperature.

Gap thickness: the thicker the gap, the less the gap expands.

Shell temperature: the higher the temperature the greater the resulting gap expansion.

Shell material CTE: steels with higher coefficients of thermal expansion produce higher gap expansion. Thus, it is easier to control the gap expansion using ferritic (as opposed to austenitic) steel grades.

And (6) aging the cushion layer. Once the converter is put into service, the intumescent mat expands, resulting in an increase in the holding pressure. Many other aging factors are responsible for the gradual irreversible loss of the fixation pressure, such as the following: thermal cycling; vibration acceleration and other mechanical factors; the cushion layer is soaked by water (condensate liquid and car washing liquid); and the organic binder burns out when the cushion layer is heated first.

Advantages and disadvantages of current underlayers

Conventional applications utilize expanded and non-expanded fibrous mats to secure the honeycomb substrate within the cartridge, as exemplified in european patent application EP0884459 (packer) and european patent specification EP0912820 (Hwang). According to one conventional system, the fiber mat allows only larger catalyst elements to be secured within the cartridge.

Expansion cushion

Intumescent mats were originally developed for gasoline converters. By the early nineties of the twentieth century, they became the most common type of ceramic mat used in all internal combustion engine applications, including catalytic converters for diesel engines. Intumescent mats have the property of partially reversibly expanding when exposed to high temperatures. The thermal expansion curves for these pads are available from several manufacturers, including 3M and Unifrax. After expansion, their holding pressure against the substrate increases, resulting in a very reliable holding system. Due to its temperature expansion characteristics, the intumescent mat actually increases its holding pressure at high temperatures, counteracting the holding pressure loss caused by thermal expansion of the steel shell.

The intumescent mat is made of alumina-silica ceramic fibers and contains vermiculite, which is caused to thermally expand. A typical composition has 30-50% alumina-silica fibers, 40-60% vermiculite, and 4-9% organic binder (usually an acrylic latex). After the converter is assembled, the mat must be exposed to temperatures on the order of about 500 ℃ to achieve initial expansion, which is typically accomplished on-board the vehicle within the first few hours of engine operation. Organic cushion binders that decompose at high temperatures are responsible for the characteristic odor that the cushion layer emits when initially heated.

The vermiculite component limits the maximum operating temperature of the intumescent mat to a relatively low value. The mat significantly lost its holding pressure at a temperature of about 750 c. This temperature is typically defined as the average mat temperature. Thus, if heat loss from outside the converter shell results in a temperature gradient across the mat, the mat can be used at higher exhaust gas temperatures. The use of an intumescent mat in thermal isothermal applications where heat loss through the converter wall does not occur is limited. This case includes a catalyst installed in a muffler, for example, for a motorcycle.

The high vermiculite component content is also responsible for the high holding pressure, especially at higher exhaust gas temperatures. It has been found that the pressure from the intumescent mat is too great for the ultra thin walled substrate, resulting in possible damage to the part. For these applications, bedding manufacturers have proposed intumescent mats (sometimes referred to as "premium" or "second generation" intumescent mats) that reduce the vermiculite content, providing lower holding pressures than conventional designs.

Non-expansive pad

The non-intumescent mat does not contain vermiculite. Thus, they can provide a higher temperature limit of about 1250 ℃. The main component of the non-intumescent mat is alumina fibers with the addition of an organic binder. In certain embodiments of the invention, it may be preferable for the catalytic converter or particulate filter to comprise a substrate as described herein and a non-intumescent mat of fibrous material.

Substrate support relies on built-in compression or fiber "springs" to provide a constant, fixed pressure over the temperature range of use. As the converter shell expands with temperature, an effective converter holding pressure drop is observed at higher temperatures. Thus, non-intumescent mats (as opposed to vermiculite mats) fix the catalyst substrate most strongly at low temperatures. As the temperature increases, the holding force of the substrate within the converter decreases.

Non-intumescent mats are useful not only in high temperature applications (thin-walled substrates) where high holding pressures cannot be tolerated, but also in low temperature converters, such as those used in diesel engines. Since they do not rely on vermiculite expansion, no oven treatment is required in low temperature diesel converters.

Hybrid underlayment

The improved catalytic converter or particulate filter of the present invention may also include a hybrid mat layer. Such pads are known in the art. In one embodiment, the hybrid mat contains a two layer design: a layer of intumescent mat overlies a layer of non-intumescent mat. Its properties and performance are also intermediate, better than the low temperature holding pressure of an intumescent mat, but higher than the high temperature pressure of a non-intumescent mat. In a preferred embodiment, the improved diesel particulate filter of the present invention includes a hybrid mat for light and heavy duty applications.

Wire mesh

The ceramic catalyst substrate may be packaged with a woven stainless steel mesh instead of a blanket. It is generally believed that the holding pressure characteristics of wire mesh are not as good as mat layers, but can still be used in certain catalytic converters (traditionally, Ford has used wire mesh). Wire mesh always requires an end seal to prevent gas from bypassing the substrate.

Auxiliary heating source

As another configuration or previously disclosed example embodiment, the filter element should include a series of electrically heated rods that are added to the substrate after the catalyst is applied. The heating element is preferably applied after the catalyst to prevent the curing process from damaging any electrical contacts. In one embodiment, the heating elements or rods are placed about 1/4 inches or any desired distance from each side. In certain embodiments, wire mesh configurations or other heating elements described herein may also be employed, placed perpendicular to the direction of gas flow and installed during formation of the fiber blank. The electrical contacts are protected with Nextel fabric or similar material. The heating element is activated as a preheater prior to engine start-up and remains in operation (partially or fully) until the exhaust gas temperature exceeds the temperature reached by the auxiliary heating element.

The use of an auxiliary heat source applied to the filter substrate may be adapted to increase the temperature within the filter substrate and/or to make the additional heat more efficient by distributing it evenly throughout the filter substrate. The auxiliary heating source may comprise a resistive heating element. The heating element may have a rod-like configuration and may be inserted after formation of the filter substrate or during the sol-gel process. The filter substrate may have one or more electrical heating elements and the heating elements may be heated simultaneously, independently, arranged in a cyclic, patterned, or random fashion. The heating element may be in the form of a wire mesh configuration, which may be inserted during or after formation of the filter substrate. The filter may use single wire mesh or multiple wire mesh heating elements, which may be heated simultaneously or independently. In addition, the wire mesh heating elements may be heated in a cyclic, patterned, or random arrangement. The heating element may also take the form of a rod, spiral or spiral configuration, inserted during or after formation. The filter substrate may contain one or more spiral or helical heating elements that are heated simultaneously or independently, including in a cyclic, patterned, or random arrangement. Finally, the filter substrate can contain a combination of any of the heating elements previously described.

In addition to the resistive heating elements described above, the auxiliary heating source may also employ infrared or microwave heated heating elements. The various heating sources may be implemented within the filter substrate itself or may be used as external heating elements for heating the filter substrate. The various heating sources may be used independently or in combination with any other heating element or heating source.

The filter substrate is encased in a sufficiently durable housing to protect the filter substrate from normal impacts encountered during vehicle transport. The housing may comprise a common metal housing such as stainless steel, steel or other metal alloy. The material may also be non-metallic, including ceramic based housings. The filter substrate may be encapsulated in an insulating material or batting prior to encapsulation in the housing. The present invention may also include a heat shield.

The inlet and outlet tubes of the filter substrate may be coated with an oxidation catalyst. This catalyst can make the irradiation process faster, resulting in the system treating the exhaust gas in a much shorter time as a whole. The catalyst may be a noble metal catalyst, including platinum, palladium, or rhodium based catalysts, among others. The catalyst may be applied directly to the surface of the filter substrate. The catalyst may be applied by spraying the catalyst onto the filter substrate, dipping the filter substrate into a solution, or injecting the catalyst into the filter substrate itself. The use of an oxidation catalyst will promote ignition of the particulate matter at lower temperatures. In addition, the catalyst may also act as a supplemental heater within the filter substrate.

The exhaust gas filter system may be integrated with the engine exhaust passage, including being integrated within the exhaust manifold of the engine itself. Because the filter substrate is so resistant to heat and vibration, it can be placed in close proximity to the engine exhaust and the exhaust gases leave the engine. The unique ability of the filter substrate to withstand high thermal and vibrational stresses makes the arrangement of the present invention much closer to an engine. Close proximity placement provides advantages over conventional exhaust filters or catalytic converters that cannot withstand such high thermal or vibrational stresses.

While the invention has been described in detail and with reference to specific embodiments thereof, it will be apparent to one skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope thereof. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

Embodiments of catalytic converter

The catalytic converter and particulate filter of the present invention are further illustrated by the following non-limiting specific embodiments. The many specific embodiments described herein illustrate but do not necessarily limit the scope of the invention. The catalytic converter of the present invention may be used on many engines and vehicles. Thus, in one embodiment, the catalytic converter of the present invention is suitable for use on a vehicle or engine manufactured by any of the following companies: Daimler-Chrysler; chrysler; a Dodge; eagle; jeep; plymouth; general Motors; AM General (e.g., HUMMERs); buick; cadillac; chevrolet; geo; GMC; hummer; LaSaIIe; oldsmobile; pontiac; saturn; ford; a context; lincoln; mercury; ace Motor Corp; american Motors; avanti BMW; Daimler-Chrysler; fiat; ford; GAZ, respectively; general Motors; honda; mitsubishi; renault; peugeot; toyota; and Volkswagen Group. Others include Holden; lightburn; hartnet; AlphaSports; finch; amuza; australian Kitcar, FPV; bavariaccars; birchfield; G-Force; bomac; bullet; homebush; carbontech; HSV; classic Glass; kraft werkz; classic Revival; a Cobra Craft; a pipe; (ii) Daktari; a PRB; daytona; python; deuce Customs; RCM; devaux; RMC; DRB; roaring Forties; elfin; robnell; evans; Austro-Daimler; OAF; puch; steyr; Steyr-Daimler-Puch; FN; germain; miese; minerva; nagant; vivinus; gurgel; puma; a to E; AC; allad; alvis; ariel; armstrong siddeley; ashley; aston Martin; austin; Austin-Healey; bentley; berkeley; bond; bristol; BSA; caterham; clan; daimler; removing; de Lorean; elva; F-L; fairthorpe; ford; frazer Nash; gilbern; ginetta; Gordon-Keeble; hillman; humber; jaguar; james and Brown; jensen; jowett; lagonda; lanchester; land Rover; Lea-Francis; lister; locost; lotus; M-R; marcos; McLaren; MG; morgan; morris; mini; ogle; pantoher; Peerless/Warwick; a pipe; range Rover; reeliant; riley; rochdale; Rolls-Royce; rover; S-W; singer; standard; sterling; sunbeam; swallow; talbot; tornado; trident; triumph; turner; TVR; vanden Plas; vauxhall; wolseley; bricklin; McLaughlin; aero; jawa; laurin & Klelement; praga; skoda; tatra; walter; kewet; elcat; valmet; RaceAbout; amilcar; Alpine-Renault, aka; bonnet; bugatti; CD; CG; citroen; DB; de Dion-Bouton; delage; delahaye; Delaunay-Belleville; facel Vega; gordini; Hispano-Suiza; hotchkiss; peugeot; renault; rosengart; simca; Sizaire-Naudin; talbot; (ii) Tracta; venturi; voisin; A-G; amphicar; audi; Auto-Union; BMW; fendt; glas; goggomobil; H-P; heinkel (heinkel trojan); horch; Kasbohrer-Setra; kleinschnittger; MAN; magirus; maybach; Mercedes-Benz; merkur; messerschmitt; neoplan; NSU; an Opel; porsche; S-W; smart; stoewer; titan; a trailer; volkswagen (vw); wartburg; wanderer; thomond; bajaj Tempo; hindustan; mahindra; maruti; premier; reva; san Storm; sipani; tata; abarth; alfa Romeo; autobianchi; bugatti Automobili SpA; de Tomaso; dino; ferrari; fiat; iso; innocenti; isotta Fraschini; itala; lamborghini; lancia; maserati; OM; piaggio; qvale; vespa; zust; daihatsu; honda (alsoacura); isuzu; mazda; mitsubishi; mitsuoka; nissan aka.datsun (alsoInfiniti); subaru; suzuki; toyota (also lexus); proton; ACE; AMI; AMM; bufori; inokom; naza; perodua; swedish Assembly; TanChong; TD 2000; donkervorort; spyker; DAF; pyonghwa; tokchon; kewet; think aka. pivco; troll; syrena; UMM; aro; dacia; marta; oltcit; volga; moskvitch; GM Daewoo Motors; hyundai Motorcompany; kia Motors; renault Samsung Motors; SangYong Motorcompany; nilsson; nordic Uhr; s.a.m.; saab; scania; thunlin; tidaholm; tjorven (old as Kalman on the export marker); volvo; and Yugo.

Catalytic or filter muffler

In one embodiment, the invention also relates to a catalytic muffler comprising a catalytic or filtration substrate of the invention. The catalytic substrate or filter substrate is contained in a canister with a muffler, as described herein.

In one embodiment, the catalytic muffler of the present invention comprises a catalytic muffler of known design in which the prior art catalytic substrate is replaced with the catalytic substrate of the present invention. Suitable known catalytic mufflers include US6,622,482; 6,604,6004, respectively; 6,341,662, respectively; and 4,457,895.

Exhaust system

In another embodiment, the invention relates to an exhaust system comprising a catalytic substrate of the invention. Exhaust systems typically include a number of components. The exhaust system includes an engine and a device adapted to direct exhaust gases away from the engine.

The exhaust system includes an internal combustion engine and a conduit that directs exhaust gases out of an exhaust port of a combustion chamber. Other optional parts of the exhaust system include an exhaust manifold, a muffler and an exhaust pipe.

In another embodiment, the present invention relates to an exhaust system comprising the filter substrate of the present invention.

In another aspect, the present invention relates to an improved exhaust system that utilizes the catalytic substrate of the present invention. In another aspect, the present invention relates to an improved exhaust system that utilizes the filter substrate of the present invention.

The exhaust system of the present invention is suitable for use with any one of: 1) mobile road engines, equipment and vehicles, including automobiles and light trucks; motorcycles for highways and streets; heavy duty road engines such as trucks and buses; 2) mobile off-road engines, equipment and vehicles, including compression ignition engines (agricultural, construction, mining, etc.); small spark ignition engines (lawn mowers, leaf blowers, chain saws, etc.); large spark ignition engines (forklifts, generators, etc.); marine diesel engines (commercial ships, diesel engines for entertainment, etc.); marine spark ignition engines (boats, private ships, etc.); recreational vehicles (snowmobiles, off-road motorcycles, all-terrain vehicles, etc.); a locomotive; aerial vehicles (aircraft, ground support equipment, etc.); and 3) stationary sources, which include hundreds of sources, such as power plants, refineries, and manufacturing facilities. In another embodiment, the invention relates to an exhaust system comprising a substrate, a catalytic converter, a particulate filter, or a catalytic muffler of the invention.

Other suitable exhaust systems of the present invention include those used in certain marine vehicles. The catalyst is typically disposed within an exhaust pipe leading from the engine. The exhaust pipe is directed through a compartment in the hull to an outlet near the stern. This arrangement results in the exhaust pipe being susceptible to vibration, particularly if a prior art substrate is used. Furthermore, in private ships, the space in which the engine can be placed is limited to keep the size of the ship small and the center of gravity low. Moreover, some prior art substrates such as cordierite cannot be too close to the engine (and may overheat and melt). An exhaust system for a marine vehicle comprising a catalytic converter or particulate filter according to the invention may overcome one or more of these problems. The catalytic converter or particulate filter may be placed in the same location in the exhaust system of the marine vessel as a conventional converter or filter, or may be placed elsewhere. For example, in certain embodiments, the catalytic converter is smaller than prior art catalytic converters, but substantially the same efficiency in removing and/or filtering contaminants. See, for example, US5,983,631 (yamahahahakushiki Kaisha).

In other embodiments, the exhaust system of the present invention includes one or more additional aftertreatment devices or methods for reducing or limiting the amount of pollutants emitted in the exhaust system. Suitable devices and methods include CRT, EGR, SCR, and ACERT, among others. For example, in one embodiment, the exhaust system comprises a catalytic converter of the present invention and a CRT. The exhaust system may further include an SCR system. Other combinations and variations are also possible and are understood to be within the scope of the invention.

In another embodiment, the invention relates to an exhaust system comprising a NOx adsorber having a catalytic substrate comprising an nSiRF-C composite and a catalyst. The main catalytic converter is partially or completely positioned in the engine head. In one embodiment, the main catalytic converter comprises a catalytic substrate of the present invention, wherein the substrate has a density of about 12lb/ft³The porosity is about 97%, which has low thermal expansion, high structural integrity, and low thermal conductivity. In a preferred embodiment, the main catalytic converter comprises a substrate having a wall thickness of about 6 mils at about 600 cpsi. The main catalytic converter in this embodiment has a wall flow configuration. In a preferred embodiment, the main catalytic converter has a channel. In a preferred embodiment, the channels of the catalytic substrate of the main catalytic converter are made by a comb-pressing process. Further, in this embodiment, the catalytic substrate comprises an optional washcoat. In this embodiment, the main catalytic converter is capable of catalyzing the oxidation and reduction of the pollutants, for example, there are catalysts capable of oxidizing the pollutants and there are also catalysts capable of reducing the pollutants. In a preferred embodiment, the NOx combined exhaust system comprises an intumescent mat. The main catalytic converter can be used for all internal combustion engines. The NOx combined system is preferably used without a fuel borne catalyst. Typically, the NOx combined exhaust system has a substrate located near the muffler, but other locations are possible.

Vehicle with a steering wheel

In another embodiment, the invention relates to an improved vehicle, the improvement comprising a catalytic converter or particulate filter according to the invention. In various embodiments, the improved vehicle includes any specific embodiment of the catalytic converter and particulate filter described herein.

Suitable example improved vehicles include vehicles manufactured by one or more of the following companies: Daimler-Chrysler; chrysler; a Dodge; eagle; jeep; plymouth; general Motors; AM General (e.g., HUMMERs); buick; cadillac; chevrolet; geo; GMC; hummer; LaSaIIe; oldsmobile; pontiac; saturn; ford; a context; lincoln; mercury; ace Motor Corp; american Motors; avanti BMW; Daimler-Chrysler; fiat; ford; GAZ, respectively; general Motors; honda; mitsubishi; renault; peugeot; toyota; volkswagen Group; and Yugo.

Examples

Example 1

The residence time or burn-out time is the amount of time that the hydrocarbons that make up the exhaust pollution remain in the exhaust filter to complete combustion or oxidation. The residence time of the present invention is significantly better than conventional systems. Fig. 19 provides graphs 1902, 1904, 1906, 1908 of the residence time required to combust or ignite soot at temperatures of 600K, 900K, 1000K, and 1200K, respectively. The more kinetic energy the particles possess, the higher the likelihood of a successful reaction. As shown in fig. 19, the residence time 1902 for burning or igniting soot of soot mass 0.9 at a temperature of 600K is much longer than the residence time 1908 at 1200K. The longer the residence time, the smaller the allowable throughput, and the greater the risk of more particulates accumulating in the filter pores and clogging them. Plugging may also be the result of overheating of the ceramic material to the point of melting, thereby blocking or clogging the filter pores. The residence time values 1902, 1904, 1906 are characteristic of cordierite samples. The residence time 1902, 1904, 1906 for complete combustion is in the range of about 2 minutes to 20 hours. Residence time 1908 represents one embodiment of the present invention, and complete combustion takes only about 0.75 seconds.

Example 2

Base material

Substrates 1-7 were prepared as described herein. AETB-12 was purchased from COI Ceramics and used as the chosen nSiRF-C material at a density of 12lbs/ft³. Is prepared from AETB-12 with size of 8 × 8 × 4The blank was machined with the standard carbide drill tipped machining method described in this patent. The substrate was machined into a cylindrical shape of the following dimensions: radius 2 inches, longitudinal length 1 inch.

Through-flow, wall-flow, and mixed through-flow/wall-flow channels were drilled in the substrate using standard CNC drilling methods described in this patent and known in the art. These passages were drilled at 10,000RPM with a 0.042 "diameter stainless steel drill bit. During drilling it was observed that: due to the high thermal emissivity and conductivity of the material, the drill bit is subjected to high temperatures, causing the drill bit to fail and eventually melt. The wall thickness was not measured.

Substrates 1 and 2 have a flow-through configuration. Substrates 3-6 have a wall flow configuration. The substrate 3 had about 25% flow-through channels and about 75% wall-flow channels. Substrate 4 has about 50% flow-through channels and about 50% wall-flow channels. Substrates 5 and 6 had about 75% flow-through channels and about 25% wall-flow channels.

Some substrates were coated with an alumina washcoat followed by a catalyst coating with a 5: 1 Pt: Rh ratio. Specifically, substrates 1, 2 and 7 are not coated with any chemical. Substrates 3,4, 5 and 6 were coated with a uniform washcoat using standard techniques known in the art. The quality of the washcoats applied to each substrate is given in the column entitled washcoat quality. Following the washcoating, substrates 3,4, 5 and 6 were coated with a catalyst mixture comprising 5: 1Pt/Rh using a standard. The mass of the catalyst mixture applied to each substrate/filter is reported as the mass of catalyst (g/ft)³) Given in the column. The washcoated and precious metal catalyst loaded substrate is canned using techniques known in the art.

Base of Wood material Number (C)	Dry substrate Weight of (2) (g)	Wet base surface Coating layer		Base surface for repairing Evaluation of coatings Metering g/in3	Sintering Of (g)	Base surface for repairing Coating layerQuality of (1) Amount (g/in)3)	H2Absolute value of O		Wet (GMS)	Of catalysts Quality (g)
											GMS	NET	Wet weight (GMS)	H2O Absolute value (GMS/IN3)
		1	29.0				178.5	149.4							2.91	63.0	2.71			---	---
2	28.9			182.0	153.1	2.99			65.3	2.90
		3	30.0				158.0	128.0							2.50	61.0	2.50	167.4	8.47	164.9	24.3Pt，4.8Rh
4	30.4			163.3	132.9	2.59			61.9	2.51	168.4	8.50	155.1	21.8Pt，4.4Rh
		5	30.3				165.7	135.4							2.64	62.0	2.52	169.8	8.58	170.4	25.3Pt，5.1Rh
6	30.9			184.6	153.7	3.00			67.3	2.90			202.5	31.6Pt，6.3Rh
																			Average value of 8.52 S/D＝0.23 N＝3		Average value of 30.9 S/D＝5.0 N＝4
7	24.3			105.1	80.8	2.47			44.6	2.54			99.7	20.2Pt，4.0Rh

Example 3

Preparation of catalytic and filtration substrates

The substrate/filter was prepared exactly as described in example 2, unless explicitly mentioned.

In a significant difference from the substrate/filter described in example 1, the final depth was 3/4 inches in a 1 inch blank, the comb assembly was removed from the CNC and the opposite (mirror image) comb assembly was installed on the CNC punch using the same step reaming method. The end result of this processing method was 600cpsi, 6 mil wall and 1/2 inch wall flow overlap. As shown in fig. 28, the dimensions of the substrate/filter in the wall flow configuration were 1 "diameter x 1" thick, and the pattern inside the blank was 0.8 "x 0.8" square. Early successful Δ P test with this substrate to observe N₂The gas flow has a pressure drop due to flow obstruction caused by the wall flow configuration. FIG. 29 shows 27 deg.CPressure drop as a function of gas flow rate was measured in the reactor tube flow measurement system at temperatures of 29 c and 400 c. Figure 30 shows the pressure drop as a function of temperature measured in the same reactor at a constant flow rate of 125 SLPM. These initial results are positive, indicating that the nSiRF-C substrate/filter does not produce very high back pressure in the wall flow configuration.

Example 4

Preparation of catalytic and filtration substrates

The substrate/filter was prepared exactly as described in example 12, unless explicitly mentioned.

In a significant difference from the substrate of example 1, the densities purchased from COI Ceramics were 11, 12, and 16lbs/ft, respectively³The blanks AETB-11, AETB-12, and AETB-16 produced three different substrates.

For the substrate/filter produced by AETB-11, the final depth was 3/4 inches in a 1 inch blank, the comb assembly was removed from the CNC and the opposite (mirror image) comb assembly was installed on the CNC punch using the same step reaming method. The end result of this processing method was 600cpsi, 6 mil wall and 1/2 inch wall flow overlap. For the substrates/filters produced by AETB-12 and AETB-16, the final depth in the 1 inch blank was 7/8 inches, the comb assembly was removed from the CNC and the opposite (mirror image) comb assembly was installed on the CNC punch using the same stepped reaming method. The end result of this processing method was 600cpsi, 6 mil wall and 3/4 inch wall flow overlap.

All substrate/filter dimensions tested at this stage were 1 "diameter x 1" thick. These substrates were subjected to another early Δ P test to observe the pressure drop observed for substrate density and wall flow configuration as a function of space time velocity. This particular test was conducted at 932 deg.F. The test results are shown in fig. 31. In addition to the data observed for our AETB-11, AETB-12, and AETB-16 substrates/filters, Corning reported the results for their 400/6.6 flow-through cordierite substrates/filters and 200/12 cordierite DPT (wall flow configuration). Corning data were reported by Corning techniques. Our results show that while the wall flow configuration of Corning DPT produced excessively high back pressure compared to cordierite flow through type filters, our nSiRF-C filters produced back pressure comparable to cordierite flow through type substrates even when used in the wall flow configuration. It is concluded that wall-flow DPTs made with nSiRF-C materials, as invented by the present invention, are an excellent alternative, since backpressure is a big problem in wall-flow DPTs, as observed in fig. 31. In addition, it was observed that the back pressure observed with the AETB-11 substrate/filter compared to the AETB-12 and AETB-16 substrates/filters, and we can infer that increasing the length of the "overlapping" channels resulted in better back pressure performance.

FIG. 32 is the same experiment conducted at an operating temperature of 1100F, resulting in nearly the same trend.

Example 5

Preparation of catalytic and filtration substrates

Substrates/filters were prepared as described in example 2, unless explicitly mentioned.

AETB-12 was purchased from COI Ceramics as a selected nSiRF-C material at a density of 12lbs/ft³. The experimental laser-based drill channel technique produced holes at 3000cpsi and 30000 cpsi. The DPSS laser system described in this patent and the related art was used to drill holes. The holes produced with a pulsed high-energy laser system are square, and due to this particular configuration, the front surface area is high. In a delta P test conducted with the same flow test reactor as described in example 3,the presence of a very high front surface area (due to the large value of the channel wall thickness) is evident. It was observed that the initial prototype created with the laser-based drilling technique was successful, and the delta back pressure had to reach a value of less than 10 inches of water. Further modifications may be made to reduce (or increase) cell density and to vary wall thickness as required by the application.

FIG. 33 shows the pressure change at 27 ℃ and 400 ℃ with N for an AETB-12 substrate/filter with a cell density of 30000cpsi₂A change in the airflow rate. FIG. 34 shows AETB-12 substrates/filters at different N for a cell density of 30000cpsi₂The pressure change at the airflow rate varies with the operating temperature.

FIG. 35 shows AETB-12 groups at 29 ℃ and 400 ℃ for a pore density of 3000cpsiPressure change of material/filter with N₂A change in the airflow rate.

Example 6

Diesel particulate filter

The substrates were produced with an AETB formulation and produced as blanks having dimensions of about 13 inches by about 5 inches with a density of about 8 pounds per cubic foot. A cylindrical semi-finished product having a diameter of about 6 inches and a height of 5 inches was cut from the blank with a diamond tipped saw. The substrate was further machined on a spinning lathe to precise tolerances (within.001 inches).

A plurality of channels were then formed in the substrate to produce a substrate having a wall flow configuration containing 600 channels per square inch. These channels are formed using the combined drilling and carding techniques described herein. The channels are square with dimensions of about 6 mils by 6 mils. The adjacent walls of adjacent channels are substantially parallel to each other. The channels do not extend the entire length of the substrate but are about 4.9 inches long.

Example 7

Measurement of Total surface area

The first and second cordierite samples had total surface areas of 33.2 and 46.97 square inches/cubic inch, respectively. Thus, the first cordierite sample had 33.20 square inches of surface-supported precious metal in the 1-inch cube. The total surface area of the substrate samples of the present invention was 83.58 square inches per cubic inch.

The total wall volume of the first and second cordierite samples was 0.311in³/in³(cubic inches/cubic inch). The total wall volume of the substrate of the present invention is 0.272 cubic inches per cubic inch. Although this value is smaller than the first and second cordierite samples, the porosity and permeability of the present invention are much higher, making this smaller total wall volume more effective.

Example 8

Activity assay

The activity test measures the amount of contaminants entering and leaving the filter. In the activity test, a sample filter is placed in a reactor and a gas of known flow rate and temperature is pumped through the material. The activity test then measures the amount of contaminants that are removed from the filter. See the figure24, activity tests for an exemplary inventive substrate 2410 and cordierite sample 2420 are shown. This test measures a concentration of 500ppm and a space velocity of 40,000hr^-1Activity of toluene. The cell density of both samples was 400 cpsi.

This test demonstrates that the inventive substrate 2410 ignites faster and at a significantly lower temperature than the cordierite sample 2420. Substrate 2410 reached 85% failure in about 3 to 4 seconds at a temperature of about 335 ° f. Cordierite 2420 reached 85% damage at about 380 ° f. Substrate 2410 reached 90% failure in about 4 to 5 seconds at about 360 ° f. Cordierite 2420 reached 90% failure in about 8 seconds at about 450 ° f. The substrate 2410 reaches substantially 100% burn at about 425F in about 5 seconds. Cordierite 2420 is predicted to achieve substantially 100% failure in about 28 seconds at about 800 ° f.

Example 9

Permeability of catalytic substrate

The permeability of the exemplary embodiment of example 2 of the present invention was about 1093cd (centidarcy). The other test values exceed the maximum value measured by the test device. The cordierite samples had a permeability of about 268cd compared to conventional systems.

Example 10

Test example 2 catalytic converter

Similar to the activity test, the EPA employs a test known as federal test procedure ("FTP") 75 to physically mount the filter on the tailpipe of an automobile and drive the automobile under specified conditions. The EPA uses this test to verify vehicle emissions. FTP 75 tests the vehicle for three states. The first state includes the crank operating at non-idle for 505 seconds. This state reflects what is experienced at the beginning of the trip until mid-trip when the engine and emission control system begin operation at ambient temperature and not at optimal level (i.e., the catalyst is cold, not reaching the required "light-off" temperature for effective control of emissions from the engine). The second state included 864 seconds of travel without idle, key off, and 5 seconds of sampling. This state reflects the engine condition when the vehicle is running continuously long enough that all systems have reached a stable operating temperature. The vehicle then has a wet end time of between 540 seconds and 660 seconds. This wet engine time reflects the engine condition that has been shut off without cooling to ambient conditions. The third state is where the crank is operating at non-idle for 505 seconds. In these cases, the engine and catalyst are warm, and although not at maximum operating efficiency at start-up, emissions performance is significantly improved over the cold start approach.

Example 11

Thermal testing of catalytic substrates

The thermal conductivity of an exemplary embodiment of the present invention is about 0.0604W/m-K (energy per meter thickness and per K temperature change (watts)). In contrast, cordierite samples are about 1.3 to 1.8W/m-K. These results show that: if a given volume of cordierite material loses 1000 watts of thermal energy, the same volume of the inventive material loses only 33 watts. Thus, the thermal conductivity of the material of the present invention is 30 times that of cordierite.

The specific heat of an exemplary embodiment of the present invention is about 640J/kg-K (joules/kilogram-on). The cordierite specimens were approximately 750J/kg-K. Even though cordierite has a greater specific heat, the cordierite filter has a greater mass to heat. The result is more thermal energy required to reach operating temperatures, making cordierite less efficient.

The multiple use temperature limit is the highest temperature that a substance can withstand multiple times without any degradation. The higher the temperature at which the substrate can continue to function without microcracking or spalling, the less likely the substrate will fracture or crack over time. This in turn means that the substrate is more durable over a wider temperature range. Higher temperature limits are preferred.

The multiple use temperature limit of the exemplary embodiment of the present invention is 2,980 ℃. The cordierite specimens were about 1,400 ℃. Thus, the inventive material can withstand more than twice the temperature of cordierite before cracking. This allows the material to function in a wider range of exhaust gas environments.

The thermal expansion system is the ratio of the increment of the length (linear coefficient), area (surface), or volume of an object to the original length, area, or volume, respectively, at a given temperature rise (typically 0 to 1 ℃). The ratio of these three factors is about 1: 2: 3. When not explicitly indicated, volume expansion coefficients are generally meant. The less the substrate expands upon heating, the less likely the filter assembly will leak, crack, or fail. The thermal expansion is preferably low to ensure that the substrate retains its dimensions even when heated or cooled.

The coefficient of thermal expansion of the exemplary embodiment of the present invention is about 2.65 x 10^-6W/m-K (Watt/meter-Ke). Cordierite samples were approximately 2.5X 10^-6W/m-K to 3.0X 10^-6W/mK. The thermal expansion of the material of the present invention is less than 10 times that of cordierite.

In one embodiment, the substrate preferably has a coefficient of thermal expansion comparable to that of the washcoat. If the thermal expansion systems are dissimilar, the washcoat will spall, delaminate, "flake off" or separate from the substrate, causing the precious metal to be blown away or plug the pores. This will eventually lead to increased back pressure, overheating and system failure.

Example 12

Structural integrity

AETB-12 had a tensile modulus of about 2.21MPa (megapascal pressure, about 100,000 times atmospheric pressure). The cordierite specimens were about 25.0 MPa. While cordierite is about 10 times stronger, the inventive material can withstand pressures of 200,000 atmospheres before fracturing. This value is sufficient for the applications described herein.

Example 13

Acoustic testing

Acoustic attenuation can be defined as a reduction in thickness, thinness, and thinness; the density is reduced; a decrease in force or strength; or weakened. In one embodiment of the invention, the acoustic attenuation is the ability of the substrate to attenuate or attenuate acoustic energy in the exhaust of an engine. The substrate of the present invention may replace or fit the muffler assembly of an engine (as disclosed herein), thereby reducing exhaust noise and exhaust system cost. Higher acoustic attenuation is preferred.

There is currently no accepted laboratory test available for any configuration of the present invention. All acoustic tests of the american society for testing and materials ("ASTM") are used for large spaces such as sound isolation booths rather than for materials. In simple tests using a sound meter, however, the automotive noise was found to be at least 25 db less than that of a conventionally muffled vehicle when the substrate of the present invention was used in the exhaust system. For reference, 110 db is the level that causes permanent damage to the human ear, and 60 db is the amount of noise in the luxury car that idles when the window is rolled up.

Example 14

Comparison with the prior art substrate

A suitable nSiRF-C (AETB-12) coupon was compared to cordierite and SiC to measure a variety of properties.

	AETB-12	Cordierite	Silicon carbide (SiC)
				Thermal conductivity	6.04×10-2W/m-K	1.3-1.8W/m-K	20W/m-K
Specific heat	640J/kg-K	750J/kg-K	950J/kg-K
				Density of	0.2465gm/cc	2-2.1gm/cc	3.2gm/cc
Emissivity of radiation	0.88	.13	.90
				Axial strength	2.21MPa	2.5MPa	18.6MPa
At 3500rpm Noise attenuation	74db	100db	100db
				Porosity of the material	97.26％	18-42％	30-40％
Permeability rate of penetration	1093-∞cd	268cd	6.65cd
				Regeneration time	0.75 second	2 minutes to 20 hours	50 seconds to 20 hours
Surface area	88,622in2	847in2	847in2
				Melting Point	3,000℃	1,400℃	2400
Thermal Expansion (CTE)	0.25×10-71/C	0.7×10-61/C	4-5×10-61/C

Example 15

In one embodiment, the substrate of the present invention has 600cpsi and 6 mil walls. The pore density of the inventive substrate samples was compared to two cordierite samples. The first and second cordierite samples were 100cpsi with wall thicknesses of 17 mils and 200cpsi with 12 mils, respectively. The inventive substrate in this embodiment has 600cpsi, and 6 mil walls.

In this exemplary embodiment, the substrate was drilled with 0.04 inch diameter channels spaced 0.06 inches across the entire filter. These channels are smaller than conventional cordierite. The result is a much increased surface area over cordierite, even without regard to the surface area present in the macropores of the substrate. The channel is preferably a "blind" channel. The exhaust gas is forced through the channel walls rather than flowing into and out of the channels without reacting with the catalyst.

The channels were drilled with a CNC drill which was computer controlled to maintain consistency. The drilling process is carried out at a constant spray rate to prevent dust airborne, which presents an OSHA hazard and may enter the drill bearings to destroy the drill.

The drilled substrate is dried in an oven to remove or bake out any water or other liquid that may be present in the pores prior to application of any catalyst. The baking time is not a variable and the evaporation of water can be determined by simply weighing the substrate. The baking time mainly accelerates the dehydration process. After the filter element is heated at several different time intervals and the weight is stable, the substrate is ready for application of any catalyst or coating.

Glossary

The term "substrate" as used herein means a solid surface upon which contaminants can be converted to non-contaminants. The substrate is understood to include a filter element, a catalytic substrate, or a filtration substrate.

The term "sintered" as used herein means a material that has been heated without melting.

The term "nonwoven" as used herein means that the fibers are not interwoven or interlaced.

The term "blank" as used herein means a block of unformed or unprocessed matrix material.

The term "green body" as used herein means an uncured blank.

The term "front surface" as used herein means the surface through which fluid enters the substrate. In some embodiments, the channel front surface has an opening and the channel is perpendicular to the front surface.

The term "back surface" as used herein means the surface through which fluid passes away from the substrate. In some embodiments, the channel has an opening at a rear surface and the channel is perpendicular to the rear surface.

The term "mil" as used herein means a unit of measure equal to one thousandth of an inch.

The term "light-off temperature" as used herein means the temperature at which the conversion of the reaction in the catalytic converter is 50%. I.e. the light-off temperature is the temperature at which 50% of one or more pollutants or total pollutants are converted to non-pollutants.

The term "burn-off" as used herein means the process of burning particulate matter and other matter filtered by the substrate. For example, burn-out may occur in a Diesel Particulate Filter (DPF).

The term "channel" as used herein means a three-dimensional opening in a substrate that extends through at least a portion of the substrate and has a defined shape and length.

The term "channels per square inch" as used herein means the number of channels present in a one-inch cross-section of the substrate. The term holes per square inch is synonymous.

The term "channel shape" as used herein means the three-dimensional shape of a channel.

The term "PM" as used herein means particulate matter. Common PM metrics include PM-10 and PM-2.5.

As used herein, the term "total surface area" is the total surface area, meaning the total surface area within one cubic inch on which the precious metal can be impregnated.

The term "two-way catalytic converter" as used herein means the oxidation of only gas phase contaminated HC and CO to CO₂And H₂Catalytic converter of O.

As used herein, the term "three-way catalytic converter" means the oxidation of CO and HC to CO₂And H₂O but also NOx to N₂The catalytic converter of (1).

The term "four-way catalytic converter" as used herein means a catalytic converter that accomplishes the oxidation and reduction described for a three-way catalytic converter and also traps particulates burning them away (which can be regenerated in an active or passive manner).

The term "adapted" as used herein is meant to satisfy specific regulatory policy requirements.

The term "thermal conductivity" as used herein means the amount of heat transferred through a sheet of a given material per unit area in a unit time with the opposite faces of the sheet material at a temperature gradient per unit (e.g., 1 degree difference in temperature per unit thickness).

The term "underlayment" as used herein generally means any material used to provide insulation and/or protection to a substrate. The underlayment is sometimes also referred to as batting.

The term "boron binder" as used herein means the agent derived from the boron binder present in nSiRF-C after the sintering process.

The term "step-wise" as used herein means the process of forming or modifying a channel in a substrate by repeatedly forcing the prongs into and out of the matrix material until a channel of the desired length is obtained.

Having now fully described this invention, it will be appreciated by those of ordinary skill in the art that the same can be performed within a wide and equivalent range of conditions, formulations and other parameters without affecting the scope of the invention or any embodiment thereof. All patents and publications cited herein are incorporated by reference in their entirety.

Claims (47)

1. A catalytic or filtration substrate comprising a non-woven sintered refractory fiber ceramic composite and a catalyst, optionally further comprising a washcoat, and optionally further comprising a plurality of channels.

2. The catalytic substrate of claim 1, wherein the composite comprises alumina-boria-silica fibers.

3. The catalytic substrate of claim 1, wherein the composite comprises alumina-zirconia fibers.

4. The catalytic substrate of claim 1, wherein the composite comprises alumina-boria-silica fibers and alumina fibers.

5. The catalytic substrate of claim 1, wherein the composite comprises alumina fibers.

6. The catalytic substrate of claim 1 wherein the composite comprises silica fibers.

7. The catalytic substrate of claim 1, wherein the composite comprises alumina boria silica fibers, and alumina fibers.

8. The catalytic substrate of claim 1, wherein the composite comprises from about 50% to about 90% silica, from about 5% to about 50% alumina, and from about 10% to about 25% aluminoborosilicate.

9. The catalytic substrate of claim 1, wherein the composite is an Alumina Enhanced Thermal Barrier (AETB) composite.

10. The catalytic substrate of claim 9, wherein said AETB is selected from AETB-8, AETB-12 and AETB-14 and AETB-16.

11. The catalytic substrate of claim 1, wherein the composite comprises an Orbital Ceramic Thermal Barrier (OCTB) composite.

12. The catalytic substrate of any of claims 1-11, wherein the composite comprises a boron binder.

13. The catalytic substrate of any of claims 1-12, wherein the catalyst comprises a metal catalyst.

14. The catalytic substrate of any of claims 1-13, wherein the catalyst is selected from the group consisting of palladium, platinum, rhodium, mixtures thereof, and derivatives thereof.

15. The catalytic substrate of any of claims 1-14, wherein the catalyst is at about 1g/ft³To about 50g/ft³Is present in an amount.

16. The catalytic substrate of any of claims 1-15, wherein the washcoat comprises alumina.

17. The catalytic substrate of any of claims 1-16, comprising a plurality of channels extending longitudinally through the substrate, and wherein the substrate comprises a wall flow configuration, a flow-through configuration, or a combination thereof.

18. The catalytic substrate of any of claims 1-17, having from about 100 to about 100,000 channels per square inch.

19. The catalytic substrate of any of claims 1-18, having about 600 channels per square inch.

20. The catalytic substrate of any of claims 1-19, wherein the channels comprise a square, triangular, hexagonal shape, and further have a longitudinal cross-sectional shape that is substantially rectangular, trapezoidal, or triangular.

21. The catalytic substrate of any of claims 1-20, having a front surface area of about 1 square inch to about 50 square inches.

22. The catalytic substrate of any of claims 1-21, which is suitable for use in a commercially available catalytic converter or Diesel Oxidation Catalyst (DOC).

23. The catalytic substrate of any of claims 1-21, which is suitable for use with a stationary engine.

24. The catalytic substrate of any of claims 1-21, adapted for use in a front-end catalytic converter, a manifold catalytic converter, or a pre-catalytic converter.

25. The catalytic substrate of any of claims 1-21 having a density of from about 6 to about 16lb/ft³。

26. The catalytic substrate of any of claims 1-25, wherein the substrate has an emissivity of about 0.8 to about 0.95.

27. The catalytic substrate of any of claims 1-26, wherein the substrate has a porosity of about 90% to about 99%.

28. The catalytic substrate of any of claims 1-27, further comprising an oxygen storage oxide.

29. The catalytic substrate of any of claims 1-28, wherein the substrate produces a pressure drop that is lower than that produced by cordierite.

30. A catalytic converter comprising the catalytic substrate of any one of claims 1-29.

31. The catalytic converter of claim 30, wherein the converter is suitable for use on a commercial automobile.

32. The catalytic converter of claim 31, wherein the converter is selected from a main catalytic converter, a pre-catalytic converter, a post-catalytic converter, or a manifold catalytic converter.

33. A particulate filter comprising the catalytic substrate or filtration substrate of any one of claims 1-29.

34. The particulate filter of claim 33, wherein the filter is a diesel particulate filter.

35. A method of catalyzing a reaction comprising exposing one or more fluid streams to the catalytic substrate or catalytic converter of any one of claims 1-32.

36. The method of claim 35, wherein the fluid is exhaust gas from an internal combustion engine.

37. The method of claim 36, wherein the exhaust gas comprises one or more of six targeted pollutants.

38. A method of filtering a gas comprising exposing one or more fluid streams to a filtration substrate, a catalytic substrate, a particulate filter or a catalytic converter according to any one of claims 1 to 34.

39. The method of claim 38, wherein the fluid is exhaust gas from an internal combustion engine.

40. The method of claim 39, wherein the exhaust gas comprises one or more of six index pollutants.

41. A method of making a catalytic or filtration substrate according to any one of claims 1 to 29, comprising: heating a plurality of refractory silica fibers, refractory alumina fibers, and refractory aluminoborosilicate fibers; mixing the fibers; washing the fibers; optionally cutting the fibers into one or more lengths; blending or mixing the chopped fibers into a slurry; adjusting the viscosity of the slurry, preferably by adding a thickener; adding a dispersing agent; adding the slurry to a mold; removing water from the slurry to form a green body; removing the green body from the mold; drying the green body in an oven, preferably at a temperature of about 250 to about 500 ° f; heating the green body in an oven at about 2000-; optionally machining the blank; optionally forming a plurality of channels in the blank; optionally adding a catalyst; and optionally adding a washcoat to form the substrate.

42. A method of making a filtration substrate according to any one of claims 1-29 comprising: machining a plurality of channels in a non-woven sintered refractory fiber ceramic composite, wherein the machining comprises forming or shaping the channels with a comb press.

43. A filtration substrate prepared according to the method of claim 42 or 43.

44. A composition comprising refractory grade alumina fibers, refractory grade silica fibers, refractory grade alumina boria silica fibers, water, and a catalyst.

45. The composition of claim 44, wherein the fibers have an average length of about 10 microns.

46. The composition of claim 44, wherein the alumina comprises about 50-90% of the inorganic fiber mixture; alumina fibers comprise about 5-50% of the inorganic fiber mixture; and alumina boria silica is about 10-25%.

47. An improved engine exhaust system, the improvement comprising the use of a catalytic substrate, a filtration substrate, a catalytic converter or a particulate filter according to any of claims 1 to 34.