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WO2001056686A1 - Piege a soufre pour systemes d'adsorption d'oxydes d'azote permettant d'ameliorer la resistance au soufre - Google Patents

Piege a soufre pour systemes d'adsorption d'oxydes d'azote permettant d'ameliorer la resistance au soufre Download PDF

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Publication number
WO2001056686A1
WO2001056686A1 PCT/US2001/002841 US0102841W WO0156686A1 WO 2001056686 A1 WO2001056686 A1 WO 2001056686A1 US 0102841 W US0102841 W US 0102841W WO 0156686 A1 WO0156686 A1 WO 0156686A1
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WO
WIPO (PCT)
Prior art keywords
sulfur
noχ
trap
adsorber
exhaust gas
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Application number
PCT/US2001/002841
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English (en)
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WO2001056686A9 (fr
Inventor
Danan Dou
Michel Molinier
Owen Bailey
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Delphi Technologies, Inc.
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Publication of WO2001056686A1 publication Critical patent/WO2001056686A1/fr
Publication of WO2001056686A9 publication Critical patent/WO2001056686A9/fr

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/92—Chemical or biological purification of waste gases of engine exhaust gases
    • B01D53/94—Chemical or biological purification of waste gases of engine exhaust gases by catalytic processes
    • B01D53/9481—Catalyst preceded by an adsorption device without catalytic function for temporary storage of contaminants, e.g. during cold start
    • B01D53/949—Catalyst preceded by an adsorption device without catalytic function for temporary storage of contaminants, e.g. during cold start for storing sulfur oxides
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL-COMBUSTION ENGINES
    • F01N13/00—Exhaust or silencing apparatus characterised by constructional features
    • F01N13/009—Exhaust or silencing apparatus characterised by constructional features having two or more separate purifying devices arranged in series
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL-COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/0807—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by using absorbents or adsorbents
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL-COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/0807—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by using absorbents or adsorbents
    • F01N3/0814—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by using absorbents or adsorbents combined with catalytic converters, e.g. NOx absorption/storage reduction catalysts
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL-COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/0807—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by using absorbents or adsorbents
    • F01N3/0821—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by using absorbents or adsorbents combined with particulate filter
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL-COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/0807—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by using absorbents or adsorbents
    • F01N3/0828—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by using absorbents or adsorbents characterised by the absorbed or adsorbed substances
    • F01N3/0842—Nitrogen oxides
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL-COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/0807—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by using absorbents or adsorbents
    • F01N3/0828—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by using absorbents or adsorbents characterised by the absorbed or adsorbed substances
    • F01N3/085—Sulfur or sulfur oxides
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL-COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/0807—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by using absorbents or adsorbents
    • F01N3/0871—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by using absorbents or adsorbents using means for controlling, e.g. purging, the absorbents or adsorbents
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL-COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/0807—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by using absorbents or adsorbents
    • F01N3/0871—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by using absorbents or adsorbents using means for controlling, e.g. purging, the absorbents or adsorbents
    • F01N3/0878—Bypassing absorbents or adsorbents
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/10—Noble metals or compounds thereof
    • B01D2255/102—Platinum group metals
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/20—Metals or compounds thereof
    • B01D2255/204—Alkaline earth metals
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/92—Chemical or biological purification of waste gases of engine exhaust gases
    • B01D53/94—Chemical or biological purification of waste gases of engine exhaust gases by catalytic processes
    • B01D53/9404—Removing only nitrogen compounds
    • B01D53/9409—Nitrogen oxides
    • B01D53/9413—Processes characterised by a specific catalyst
    • B01D53/9422—Processes characterised by a specific catalyst for removing nitrogen oxides by NOx storage or reduction by cyclic switching between lean and rich exhaust gases (LNT, NSC, NSR)
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/92—Chemical or biological purification of waste gases of engine exhaust gases
    • B01D53/94—Chemical or biological purification of waste gases of engine exhaust gases by catalytic processes
    • B01D53/9445—Simultaneously removing carbon monoxide, hydrocarbons or nitrogen oxides making use of three-way catalysts [TWC] or four-way-catalysts [FWC]
    • B01D53/945—Simultaneously removing carbon monoxide, hydrocarbons or nitrogen oxides making use of three-way catalysts [TWC] or four-way-catalysts [FWC] characterised by a specific catalyst
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL-COMBUSTION ENGINES
    • F01N2570/00—Exhaust treating apparatus eliminating, absorbing or adsorbing specific elements or compounds
    • F01N2570/04—Sulfur or sulfur oxides
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL-COMBUSTION ENGINES
    • F01N2570/00—Exhaust treating apparatus eliminating, absorbing or adsorbing specific elements or compounds
    • F01N2570/14—Nitrogen oxides
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL-COMBUSTION ENGINES
    • F01N2610/00—Adding substances to exhaust gases
    • F01N2610/03—Adding substances to exhaust gases the substance being hydrocarbons, e.g. engine fuel
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/02—Circuit arrangements for generating control signals
    • F02D41/021—Introducing corrections for particular conditions exterior to the engine
    • F02D41/0235—Introducing corrections for particular conditions exterior to the engine in relation with the state of the exhaust gas treating apparatus
    • F02D41/027—Introducing corrections for particular conditions exterior to the engine in relation with the state of the exhaust gas treating apparatus to purge or regenerate the exhaust gas treating apparatus
    • F02D41/0275—Introducing corrections for particular conditions exterior to the engine in relation with the state of the exhaust gas treating apparatus to purge or regenerate the exhaust gas treating apparatus the exhaust gas treating apparatus being a NOx trap or adsorbent
    • F02D41/028—Desulfurisation of NOx traps or adsorbent
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
    • Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/12—Improving ICE efficiencies

Definitions

  • the present disclosure relates to nitrogen oxide adsorption materials used in exhaust systems of internal combustion engines.
  • T WC catalysts three-way conversion catalysts
  • Such catalysts containing precious metals like platinum, palladium, and rhodium, have been found both to successfully promote the oxidation of unburned hydrocarbons (HC) and carbon monoxide (CO) and to promote the reduction of nitrogen oxides (NO ⁇ ) in exhaust gas, provided that the engine is operated around stoichiometry balanced for combustion (“combustion stoichiometry”; i.e., an air to fuel (A/F or ⁇ ) ratio of about 14.7 and 14.4, in the case of a gasoline engine).
  • combustion stoichiometry i.e., an air to fuel (A/F or ⁇ ) ratio of about 14.7 and 14.4, in the case of a gasoline engine).
  • lean-burn conditions three way catalysts are efficient in oxidizing the unburned hydrocarbons and carbon monoxides, but are inefficient in the reduction of nitrogen oxides.
  • These adsorbers generally comprise a catalytic metal, such as platinum, palladium and/or rhodium, in combination with an alkali and/or alkaline earth element (hereinafter the "alkali material"), loaded on a porous support such as alumina, gamma-alumina, zirconia, alpha-alumina, cerium oxide (ceria), or magnesium oxide.
  • the catalytic material in the adsorber acts first to oxidize NO to NO 2 . NO 2 then reacts with the alkali and alkaline earth materials to form stable nitrate salts. In a stoichiometric or rich environment, the nitrate is thermodynamically unstable, and the stored NO ⁇ is released for catalysis, whereupon NO ⁇ is reduced to N gas.
  • the support will, itself, be deposited on a chemically stable and thermally insulating substrate, or metallic substrate.
  • substrates include cordierite and mullite, among others.
  • the substrate may be of any size or shape, such as is required by the physical dimensions of the designed exhaust system.
  • the internal configuration of the substrate may be any known or commonly employed configuration.
  • Substrates are typically formed as monolithic honeycomb structures, layered materials, or spun fibers, among other configurations.
  • No. 5,727,385 to Hepburn discloses a NO ⁇ trap, comprising (i) at least one precious metal selected from platinum and palladium loaded on a porous support; and (ii) at least one alkali or alkaline earth metal (a) loaded on a porous support or (b) present as an oxide thereof.
  • Hepburn optionally includes a three- way catalyst located either between the two components or after the NO ⁇ trap.
  • the NO ⁇ adsorbers remove the NO ⁇ from the exhaust stream during lean burn conditions and/or low temperatures, they are plagued with the problem of sulfur poisoning under such conditions. Sulfur, a contaminant present in fuel, adsorbs onto the NO ⁇ adsorber, reducing the sites available for trapping NO ⁇ .
  • the exhaust gas catalyst system comprises: a sulfur trap disposed within an exhaust stream, said sulfur trap comprising a sulfur scavenger component; and a NO ⁇ adsorber catalyst disposed within the exhaust stream, downstream from said sulfur trap.
  • Figure 1 is a graphic representation of sulfur concentration vs. adsorption time, showing fresh sulfur adsorption of a sulfur trap at 400°C and an
  • Figure 2 is a graphic representation of sulfur concentration vs. release time, showing fresh sulfur release from a sulfur trap at 700°C and an A/F ratio of 13, following exposure to sulfur as depicted in figure 1. High sulfur regenerability for the sulfur trap is established.
  • Figure 3 is a graphic representation of sulfur concentration vs. adsorption time, showing sulfur adsorption of a fresh sulfur trap as a function of temperature (200-700°C lines) at high space velocity. High sulfur adsorption efficiency across a wide temperature window for the sulfur trap is established.
  • Figures 4 and 5 shows graphic representations of sulfur concentration vs.
  • FIG. 6 shows graphic representations of sulfur concentration vs. adsorption time at 400°C for 40 minutes at an A/F ratio of 20 ( Figure 6) and sulfur concentration vs. release time at 700°C for 10 minutes with an A F ratio of 13, ( Figure 7).
  • Figure 8 is a graphic representation of sulfur concentration vs. adsorption time at 400°C for 40 minutes at an A/F ratio of 20 (with 100 ppm SO in feed gas) of a fresh and two aged warm-up catalysts, aged at 900°C and 950°C for 16 hours in air and water.
  • Figure 10 is a graphic representation of sulfur concentration vs. release time, showing sulfur release at 700°C and ⁇ of 13 from a fresh and two thermally aged sulfur traps after sulfur adsorption at 400°C for 40 minutes and an A/F ratio of 20 with 100 ppm SO 2 .
  • Figure 11 is a graphic representation of NO ⁇ adsorption performance of the sulfur trap at 300°C vs. adsorption time, showing NO ⁇ adsorption of fresh and aged (at 900°C or 950°C) sulfur trap warm up catalyst. Establishes that the sulfur trap provides a modest NO ⁇ trapping function.
  • Figure 12 is a graphic representation of NO ⁇ conversion percentage vs. evaluation temperatures, showing NO ⁇ conversions of fresh and aged (at 900°C or 950°C) sulfur trap at high SV. Establishes that the sulfur trap provides a modest NO ⁇ conversion function.
  • Figure 13 is a graphic representation of sulfur concentration vs. release time at 700°C, and at an A/F ratio 13, of an aged (900°C in air) sulfur trap for palladium, palladium/platinum, and palladium/ platinum/rhodium precious group metal loadings.
  • Figure 14 is a graphic representation of NO ⁇ adsorption percentage at 300°C of NO ⁇ adsorbers with and without sulfur trap protection.
  • Figure 15 is a graphic representation of NO ⁇ conversion percentage at (30 seconds lean/2 seconds rich) of NO ⁇ adsorbers with and without sulfur trap protection.
  • Figure 16 shows a simple scheme for an exhaust gas catalyst system, comprising a sulfur trap, located in close coupled position with an internal combustion engine, and a NO ⁇ adsorber, placed in underfloor position.
  • Figure 17 shows a more complex scheme for an exhaust gas catalyst system in a diesel engine, further comprising a particulate trap.
  • Figure 18 is a graphical illustration of transmittance of sulfur through a NO ⁇ adsorber during continuous regeneration.
  • Figure 19 is a bar graph illustrating that after severe aging at 995°C maximum bed temperature for 100 hours, start up catalysts with (lines 16,18,20) and without (lines 15,17,19) sulfur scavengers have substantially equivalent light off performance.
  • Figures 20 and 21 are graphical illustrations showing lean adsorption and rich release of sulfur from two platinum based sulfur traps, wherein lines 21 and 30 represent temperature, while lines 22 and 31 represent sulfur concentration.
  • lines 21 and 30 represent temperature
  • lines 22 and 31 represent sulfur concentration.
  • the second formulation (figure 21) releases sulfur at 300°C, and is therefore suitable for a continuous regeneration strategy
  • the first formulation (figure 20) releases no sulfur at 300°C, and is thus suitable for a periodic regeneration strategy.
  • Figure 22 is a graphical illustration of the rich and lean adsorption of different sulfur species by a NO ⁇ adsorber; line 221 represents H 2 S at an A/F of 13, line 222 represents SO 2 at an A/F of 13, and line 223 represents SO at an A F of 20.
  • Figure 23 is a graphical illustration of NO ⁇ adsorber conversion efficiency after aging for 20 hours with no sulfur (line 232) or in the presence of H 2 S (line 233) or SO (line 231) in a rich environment (A/F is 13.2).
  • Figure 24 is a graphical representation of the projection of frequency of sulfur trap regeneration (periodic regeneration strategy) as a function of ppm sulfur content in the fuel for two different sulfur trap formulations, both platinum based. DESCRIPTION OF THE PREFERRED EMBODIMENT
  • the exhaust gas catalyst system provides improved management of NO ⁇ and sulfur components through incorporation of a sulfur trap upstream from a NO ⁇ adsorber, the sulfur trap comprises a sulfur scavenging component and optionally an oxidation catalyst and/or a lean NO ⁇ catalyst.
  • the sulfur trap comprises a sulfur scavenging component and optionally a catalytic component (NO ⁇ and/or oxidation catalyst) comprising one or more precious metals, e.g., an oxidation catalyst and/or a NO ⁇ catalyst, disposed on a substrate.
  • a catalytic component NO ⁇ and/or oxidation catalyst
  • Parameters in selecting sulfur scavenging components for the sulfur trap include the temperatures at which these components release sulfur species and the level of exhaust richness required to trigger such release. These parameters may be adjusted to the particular exhaust design, and materials selected, accordingly.
  • the sulfur scavenging component comprises trapping element(s) having a sufficient affinity for sulfur to enable adsorption in a lean exhaust environment (e.g., at an A F ratio of about 17 and above) and optionally, a support. Materials are also preferably selected on their ability to release sulfur at relatively low temperatures under rich exhaust conditions.
  • Trapping elements including silver (Ag), aluminum (Al), barium (Ba), cerium (Ce), cobalt (Co), copper (Cu), lanthanum (La), lithium (Li), magnesium (Mg), sodium (Na), neodymium (Nd), rubidium (Rb), tin (Sn), strontium (Sr), and zinc (Zn), among others, as well as combinations and alloys comprising at least one of the foregoing elements, have been found to be optimally effective and are accordingly preferred. Combinations of two or more elements are particularly preferred since such combination provides a more balanced adsorption performance over wider A F ratio and temperature ranges.
  • the trapping element(s) may be applied to supporting materials as is known in the art.
  • Suitable support materials include high surface area materials (e.g., a surface area of about 50 m 2 /g or greater), such as alumina (gamma-alumina, alpha alumina, theta alumina, and the like), zeolite, zirconia, magnesium oxide, titania, silica, and combinations comprising at least one of the foregoing support materials, among others. Since ceria stores oxygen in lean phases which translates to a fuel economy penalty during lean to rich modulations where storage of O in lean phase consumes additional reductants, ceria within the sulfur trap catalyst should be minimized or eliminated.
  • the support material has a surface area above about 300 square meters per gram (m /g).
  • m /g there are no real upper limits for the amount of sulfur scavenging and/or catalytic components that can or should be loaded onto the support, except in as much as overloading of the support material can cause undesirable backpressures and pressure drops within the exhaust system.
  • there are no real lower limits for the amount of sulfur scavenging and/or catalytic components that can be loaded onto the support it being recognized that the effectiveness of the trapping elements increase as the amount of the trapping elements loaded onto the support increases.
  • Exemplary sulfur scavenging components comprise barium in an amount of up to about 1,480 grams per cubic foot (g/ft 3 ); strontium in an amount of up to about 940 g/ft ; and magnesium in an amount of up to about 500 g/ft .
  • a particularly preferred sulfur scavenging component designed to provide optimal amounts of trapping elements while reducing backpressure comprises a combination of about 370 to about 740 g/ft 3 barium, about 235 to about 375 g/ft 3 strontium, and about 125 to about 250 g/ft 3 magnesium.
  • a sulfur trap composition could have a catalytic component comprising up to about 95 wt% sulfur scavenging component, up to about 25 wt% catalyst (NO ⁇ and/or oxidation), and optionally up to about 40 wt% stabilizers, disposed on a substrate; with about 40 wt% to about 90 wt% sulfur scavenging component, about 2 wt% to about 20 wt% catalyst, and about 2 wt% to about 40 wt% stabilizers preferred; and about 60 wt% to about 85 wt% sulfur scavenging component, about 3 wt% to about 10 wt% catalyst, and about 5 wt% to about 30 wt% stabilizers especially preferred; based upon the total weight of the catalytic component.
  • a catalytic component comprising up to about 95 wt% sulfur scavenging component, up to about 25 wt% catalyst (NO ⁇ and/or oxidation), and optionally up to about 40 wt%
  • the catalytic component of the sulfur trap could comprise about 40 wt% Ba, about 25 wt% Sr, about 6 wt% Ce, about 6 wt% precious metals, and about 23 wt% stabilizers.
  • the catalytic component of the sulfur trap could comprise about 50 wt% Ba, about 32 wt% Sr, about 7 wt% precious metals, and about 11 wt% stabilizers.
  • the support is, itself, carried on a high temperature, insulating substrate.
  • substrates which are stable in high temperatures (e.g., temperatures up to about 1,200°C), include cordierite, mullite, and metal substrates, among others.
  • This substrate which may be in any known or commonly employed configuration, is typically formed as a monolithic honeycomb structure, layered materials, or spun fibers, among other configurations.
  • the sulfur scavenging component obtained may be utilized alone, or combined with precious metals, including palladium, platinum, gold, rhodium, osmium, iridium, and ruthenium, as well as combinations and alloys comprising at least one of the foregoing metals.
  • a preferred sulfur trap catalyst precious metal (PM) loading comprises: up to about 60 g/ft 3 platinum, up to about 250 g/ft 3 palladium, and up to about 30 g/ft 3 rhodium.
  • a particularly preferred sulfur trap catalyst has a PM loading, designed for optimal performance, comprising: about 10 to about 40 g/ft 3 platinum, about 40 to about 100 g/ft 3 palladium, and about 3 to about 10 g/ft 3 rhodium.
  • platinum generally enhances palladium-based light off functions by facilitating nitrogen oxide (NO) to nitrogen dioxide (NO 2 ) and sulfur dioxide (SO 2 ) to sulfite (SO 3 ) oxidation, thereby improving both NO ⁇ and sulfur oxides (SO ⁇ ) trapping efficiencies.
  • Rhodium located on the sulfur trap surface, enhances NO ⁇ reduction, both at stoichiometry and during lean to rich modulations and also promotes high steady state hydrocarbon conversions. Accordingly, a tri -metallic formulation is preferred to provide effective storing of NO ⁇ (to the extent that it occurs in the sulfur trap) and SO ⁇ and for converting stored NO ⁇ during lean to rich modulations.
  • Rhodium addition to platinum and palladium improves sulfur release under rich conditions. Not to be limited by theory, this is believed to be attributable to enhanced rates of steam reforming, which results in the production of hydrogen (H 2 ) gas; a very effective constituent for NO ⁇ and sulfate reduction. Consistent with this, the tri-metallic formulation is also found to be more effective for the release of sulfur during high temperature rich desulfation than palladium only and platinum/palladium formulations of the same support architecture.
  • Figure 13 shows that after high temperature aging (900°C in air), the platinum-palladium-rhodium catalyst (line 121) has better sulfur release at 700°C and A F ratio 13, than the platinum-palladium (line 122) and palladium (line 123) catalysts.
  • the sulfur trap catalyst itself may be made out of the sole sulfur scavenger component, or it may be made as a mixture (or juxtaposition) of the sulfur scavenger component and either of an oxidation catalyst or a lean NO ⁇ catalyst. Where either of the oxidation catalyst or lean NO x catalyst accompanies the sulfur scavenging component, the sulfur trap catalyst may be formed by any conventional technique. The one of three main production techniques are preferred. First, all components can be mixed in the same washcoat and applied to the substrate. Alternately, the sulfur scavenging component and either of the oxidation catalyst or lean NO ⁇ catalyst can be applied as separate layers (in any order) on the same catalyst brick (monolith). As a third alternative, the components can be banded onto a dual brick system, where the sulfur scavenging component and either of the oxidation catalyst or lean NO ⁇ catalyst can be applied to separate bricks or separate areas of one brick.
  • sulfur traps can be employed in various manners: (a) sulfur trap close-coupled brick and NO ⁇ adsorber underfloor brick; (b) sulfur trap close-coupled brick and a dual brick underfloor arrangement with the first portion being a sulfur trap and the second portion being a NO ⁇ adsorber; and (c) sulfur trap close-coupled brick with a NO ⁇ adsorber underfloor brick with a sulfur trapping function incorporated via the use of the sulfur scavenging components.
  • the startup catalyst adsorbs sulfur with nearly 100% efficiency at temperatures of about 200°C to about 700°C, whether fresh or after severe thermal aging at about 700°C to about 950°C for 16 hours.
  • the following Figures detail experimental performance characteristics for a sulfur trap catalyst, comprising approximately: 40 g/ft platinum, 80 g/ft palladium, 11 g/ft 3 rhodium, 740 g/ft 3 barium, and 472 g/ft 3 strontium.
  • Figure 1 shows fresh sulfur adsorption for a sulfur scavenging component at 400°C and an A/F ratio of 20, with 100 ppm (parts per million) SO with sulfur breakthrough, or unadsorbed sulfur, measured in total sulfur mode, in which all species of sulfur are analyzed.
  • Figure 2 shows fresh sulfur release for a sulfur scavenging component at 700°C and an A/F ratio of 13.
  • Figure 3 shows sulfur adsorption of a fresh sulfur scavenging component at high space velocity as a function of temperature (200-700°C (the line numbers correlate with the temperatures in °C)). Sulfur breakthrough was measured in total sulfur mode. A new sample was used in each adsorption test. As can be seen in Figure 3, the fresh sulfur scavenging component shows high sulfur adsorption efficiency across a wide temperature window for the sulfur scavenging component.
  • Figures 4 and 5 show sulfur release from a fresh sulfur scavenging component at 600°C and at 700°C, respectively, over three A/F ratios, 13 (lines 41, 51), 13.6 (lines 42, 52), and 14 (lines 43, 53), after adso ⁇ tion with 100 ppm SO 2 at 400°C for 40 minutes. Temperature was ramped up to 600°C or 700°C in nitrogen gas, whereupon synthetic gas simulating exhaust, at the particular A/F ratio, was switched online for 10 minutes. Sulfur emission was measured in total sulfur mode. Figures 4 and 5 show that the sulfur scavenging component is regenerable.
  • Figures 6 and 7 show sulfur adso ⁇ tion of a fresh sulfur scavenging component at 400°C at an A F ratio of 20 and lOOppm SO 2 for 40 minutes ( Figure 6) and sulfur release of a fresh sulfur scavenging component at 700°C at an A/F ratio of 13 and lOOppm SO 2 for 10 minutes (Figure 7). Sulfur breakthrough was measured in total sulfur mode. Figures 6 and 7 show good sulfur storage and release performance after repeated sulfur poisoning and regeneration.
  • Figure 8 shows sulfur adso ⁇ tion at 400°C of a fresh (line 73) and of two aged (900°C (line 72) and 950°C (line 71) for 16 hours in air and water) sulfur trap catalysts at an A/F ratio of 20 for 40 minutes (100 ppm SO in feed gas). Good adso ⁇ tion performance of fresh and aged sulfur scavenging components is established.
  • Figure 9 shows sulfur adso ⁇ tion at 400°C, A/F ratio of 20 and lOppm SO 2 for fresh (line 82) and 900°C aged (lines 81 and 83) sulfur trap catalysts at different flow rates, 45,000 (line 83 (1 inch (") by l"))and 90,000 per hour (line 81 (1" by 0.5"); line 82 (1" x 0.5")).
  • This figure indicating a high sulfur trap efficiency at modest flow rate for both the fresh and aged catalysts.
  • Figure 10 shows sulfur release at 700°C and an A/F ratio of 13 from a fresh (line 93) and two thermally aged (900°C, line 92 and 950°C, line 91) sulfur scavenging components after sulfur adso ⁇ tion at 400°C at an A F ratio of 20, for 40 minutes with 100 ppm SO . Temperature was ramped up to 700°C under nitrogen gas, whereupon rich gas was switched online for 10 minutes. Sulfur emission was measured in total sulfur mode. Figure 10 further establishes that the thermally aged sulfur scavenging component is regenerable. As mentioned above, the sulfur scavenging component may additionally possess some NO ⁇ adso ⁇ tion and conversion properties.
  • Figure 11 shows NO ⁇ adso ⁇ tion of fresh (line 101) and aged sulfur scavenging components (line 102 aged at 900°C in air/H 2 O; line 103 aged at 950°C in air/H 2 O) at high space velocity ("SV", which is the flow of exhaust gas over the catalyst in one hour divided by the catalyst volume) of 61,000 hr-1, showing that the sulfur scavenging components provide a modest NO ⁇ trapping function.
  • SV space velocity
  • the sulfur scavenging component in Figure 11 the component was aged at 900°C (line 102) or 950°C (line 103) in air and water for 16 hours.
  • Figure 12 shows NO ⁇ conversions of fresh (line 111) and aged sulfur scavenging components (line 112 aged at 900°C C in air/H O; line 113 aged at 950°C C in air/H 2 O; both for 16 hours) at high SV, showing that the sulfur scavenging components provide a modest NO ⁇ conversion function.
  • NO ⁇ conversions were plotted at different temperatures for fresh and aged sulfur scavenging component at a SV of 61,000 per hour, with 500 ppm of NO ⁇ and with 30 second to 2 second lean to rich modulations.
  • the sulfur trap exhibits light-off performance equivalent to that of standard three-way catalysts of comparable precious metal (PM) loading.
  • the sulfur trap also provides reasonable levels of NO ⁇ conversion and acceptable NO to NO oxidation efficiencies even at high space velocities (e.g., SV of up to about 60,000 hr-1), such performance being dependent on PM loadings, aging conditions, catalyst volumes, among other parameters.
  • Experimental values showed 8% NO to NO? oxidation for fresh sulfur scavenging component and 1% NO to NO 2 oxidation for sulfur scavenging component aged at 900°C in air and water.
  • the NO ⁇ adsorber used in conjunction with the sulfur trap may be any NO ⁇ adsorber as can be found in the prior art.
  • the NO ⁇ adsorber should comprise a catalyst capable of catalyzing NO ⁇ under rich conditions and a material capable of adsorbing NO under lean conditions.
  • the NO ⁇ adsorber comprises catalyst, such as a precious metal, metal oxide, alkali and/or alkaline earth metal, disposed on a support such as alumina, titania, zirconia, ceria, lanthanum oxide, zeolite, silica, magnesia or a combination comprising at least one of the foregoing.
  • An exemplary NO ⁇ adsorber is described in U.S. Patent No.
  • 5,727,385 to Hepburn which discloses a NO ⁇ adsorber, comprising: (i) at least one precious metal selected from platinum and palladium loaded on a porous support; and (ii) at least one alkali or alkaline earth metal (a) loaded on a porous support or (b) present as an oxide thereof.
  • the sulfur trap is employed upstream of a NO ⁇ adsorber located in an underfloor position in any type of exhaust system, including diesel. Consequently, the NO ⁇ adsorber is protected from sulfur poisoning in the first instance, and purged of sulfur buildup when required.
  • the sulfur trap and NO ⁇ adsorber may simultaneously adsorb, during lean phases, and release, during rich pulses, sulfur species and NO ⁇ species, in which case the sulfur maintenance strategy is referred to as continuous regeneration mode.
  • Figure 21 shows a sulfur trap component consistent with continuous regeneration, i.e. capable of releasing sulfur at low temperature (300°C).
  • the exhaust gas system comprises a sulfur trap (3), located within the exhaust stream and a NO ⁇ adsorber (4) downstream of the sulfur trap (3), in an underfloor position.
  • the sulfur trap (3) can optionally be solely a sulfur scavenger component, the combination of an oxidation catalyst and a sulfur scavenging component or the admixture of a lean NO ⁇ catalyst and sulfur scavenging component.
  • the sulfur scavenging component requires regenerations that are achieved by rich excursions either in a continuous or in a periodic way.
  • the duration of the regenerations is depending on the adopted maintenance strategy, and tuned to create both sufficient richness and sufficient exotherm over the sulfur trap (3) to cause sulfur release.
  • regeneration requirements can be established on a time basis, or, optionally, a sensor can be employed to determine when sulfur purges must be achieved.
  • the sulfur trap is operated at temperatures up to about 600°C or so, and typically about 150°C - 550°C, with lean/rich modulations at appropriate intervals to maintain the desired sulfur removal from the exhaust stream, i.e., a continuous regeneration mode.
  • the lean cycle is up to about 300 seconds(s) or so, with about 10 to about 250 seconds preferred, and about 30 to about 240 seconds especially preferred.
  • the rich cycle is up to about 15 seconds or so, with up to about 10 seconds preferred, and about 1 to about 5 seconds especially preferred (see Figure 18, illustration of a continuous regeneration).
  • Lean/rich modulations can be achieved via an in cylinder fuel injection (2 A) or via an in exhaust injection (2B), as illustrated in Figure 16 and 17.
  • the exhaust gas catalyst system having high sulfur storage capacity across a range of temperatures and A/F ratios, and effective prevention of NO ⁇ adsorber sulfur poisoning while providing additional catalytic components, will preferably be located in a close coupled position.
  • the sulfur trap provides high sulfur protection maintained via periodic or continuous regenerations, and good durability in trapping efficiencies despite aging and regenerations along with multifunctional properties, allowing for substantive performance in sulfur adso ⁇ tion, warm-up catalytic activity, and lean NO ⁇ catalysis. Further, as for the NO ⁇ adsorber in an underfloor position, utilization of sulfur protection significantly extends NO ⁇ adsorber high-activity periods. Consequently, NO adsorber desulfurization is rarely required, translating to better fuel economy.
  • the sulfur trap presented in Figure 20, which is suitable for a periodic regeneration strategy, can comprise, for example, any sulfur scavenging components including, but not limited to, Ag, Zn, Ce, Co, Ba, Mg, and the like, noble metals including, but not limited to, Pd, Rh, and the like, and of support including alumina and titania, and the like, as well as mixtures comprising at least one of the foregoing materials.
  • sulfur scavenging components including, but not limited to, Ag, Zn, Ce, Co, Ba, Mg, and the like, noble metals including, but not limited to, Pd, Rh, and the like, and of support including alumina and titania, and the like, as well as mixtures comprising at least one of the foregoing materials.
  • the sulfur trap presented in Figure 21, which is suitable for continuous regeneration strategy, can comprise, for example, any sulfur scavenging components including, but not limited to, Ag, Zn, Ba, Sr, and the like, noble metal catalysts including Pt, Pd, Rh, and support including alumina, titania and zeolite, and the like, as well as mixtures comprising at least one of the foregoing materials.
  • any sulfur scavenging components including, but not limited to, Ag, Zn, Ba, Sr, and the like, noble metal catalysts including Pt, Pd, Rh, and support including alumina, titania and zeolite, and the like, as well as mixtures comprising at least one of the foregoing materials.
  • Figure 24 is a projection of sulfur trap regeneration frequency as a function of sulfur content in the fuel, in the case of a periodic regeneration strategy (which inco ⁇ orates average speed, space velocities and similar assumptions).
  • a regeneration of the sulfur trap would be required about every 5,000 miles only. If the NO ⁇ adsorber downstream from the sulfur trap survives 10 regenerations of the sulfur trap before it needs a desulfurization itself, then the NO ⁇ adsorber desulfurization will be required about every 50,000 miles, with NO ⁇ adsorber desulfurization required whenever the NO ⁇ conversion ratio falls below the required level (e.g., about 60%, 70%, 80%, or more, depending on the application).

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  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Health & Medical Sciences (AREA)
  • Biomedical Technology (AREA)
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  • General Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Materials Engineering (AREA)
  • Exhaust Gas After Treatment (AREA)
  • Catalysts (AREA)
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Abstract

L'invention concerne un système de catalyse de gaz d'échappement, comprenant: un catalyseur de réchauffage du piège à soufre, logé dans le flux d'échappement et comprenant: un composant chélateur du soufre; et un catalyseur d'adsorption d'oxydes d'azote, logé dans le flux d'échappement en aval dudit piège à soufre dans une position sous plancher. Le procédé consistant à réduire l'empoisonnement au soufre d'un adsorbeur de monoxyde d'azote logé dans un système de catalyse de gaz d'échappement, comprend la mise en place d'un piège à soufre dans le flux d'échappement en amont de l'adsorbeur d'oxydes d'azote. Le piège à soufre comprenant un composant chélateur du soufre.
PCT/US2001/002841 2000-02-01 2001-01-29 Piege a soufre pour systemes d'adsorption d'oxydes d'azote permettant d'ameliorer la resistance au soufre WO2001056686A1 (fr)

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WO2002058825A3 (fr) * 2001-01-26 2003-03-27 Engelhard Corp Piege a sox destine a augmenter l'efficacite d'un piege a nox et ses procedes de fabrication et d'utilisation
WO2003031780A1 (fr) * 2001-10-11 2003-04-17 Southwest Research Institute Systemes et procede de reduction des emissions des moteurs diesel
WO2007007107A1 (fr) * 2005-07-12 2007-01-18 Johnson Matthey Public Limited Company Desulfuration de catalyseur ag/a12 o3 hc-scr
EP1170472B1 (fr) * 2000-07-05 2007-09-12 Ecocat OY Dispositif et procédé d'épuration de gaz d'échappement
US7485271B2 (en) 2003-08-09 2009-02-03 Johnson Matthey Public Limited Company Catalyst structure for treating NOx containing exhaust gas from a lean burn engine
WO2010026018A1 (fr) * 2008-08-25 2010-03-11 Torsten Schlicht Procédé et installation de gaz d’échappement pour l’épuration de gaz d’échappement contenant des sox, en particulier provenant des moteurs à combustion interne de bateaux
EP2110526A4 (fr) * 2007-02-06 2011-02-16 Toyota Motor Co Ltd Dispositif de purification d'échappement pour moteur à combustion interne
US8387367B2 (en) 2005-11-14 2013-03-05 Johnson Matthey Public Limited Company Reducing coking over Ag/Al2O3 HC-SCR catalyst
US8685353B2 (en) 2005-07-12 2014-04-01 Exxonmobil Research And Engineering Company Regenerable sulfur traps for on-board vehicle applications

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EP1857649B1 (fr) 2001-12-03 2013-07-03 Eaton Corporation Système et procédés pour améliorer le contrôle des émissions de moteurs à combustion interne
JP3858749B2 (ja) * 2002-04-23 2006-12-20 トヨタ自動車株式会社 内燃機関の排気浄化装置
EP1634638B1 (fr) * 2002-06-25 2011-10-19 Ford Global Technologies, LLC Procédé pour l'élimination d'émissions de gaz d'échappement
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JP4100412B2 (ja) * 2005-04-12 2008-06-11 トヨタ自動車株式会社 圧縮着火式内燃機関の排気浄化装置
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JP5589996B2 (ja) * 2011-09-12 2014-09-17 株式会社日立製作所 二酸化炭素捕捉材
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EP1170472B1 (fr) * 2000-07-05 2007-09-12 Ecocat OY Dispositif et procédé d'épuration de gaz d'échappement
WO2002058825A3 (fr) * 2001-01-26 2003-03-27 Engelhard Corp Piege a sox destine a augmenter l'efficacite d'un piege a nox et ses procedes de fabrication et d'utilisation
WO2003031780A1 (fr) * 2001-10-11 2003-04-17 Southwest Research Institute Systemes et procede de reduction des emissions des moteurs diesel
US6742328B2 (en) 2001-10-11 2004-06-01 Southwest Research Institute Systems and methods for controlling diesel engine emissions
US7485271B2 (en) 2003-08-09 2009-02-03 Johnson Matthey Public Limited Company Catalyst structure for treating NOx containing exhaust gas from a lean burn engine
WO2007007107A1 (fr) * 2005-07-12 2007-01-18 Johnson Matthey Public Limited Company Desulfuration de catalyseur ag/a12 o3 hc-scr
US8685353B2 (en) 2005-07-12 2014-04-01 Exxonmobil Research And Engineering Company Regenerable sulfur traps for on-board vehicle applications
US8387367B2 (en) 2005-11-14 2013-03-05 Johnson Matthey Public Limited Company Reducing coking over Ag/Al2O3 HC-SCR catalyst
EP2110526A4 (fr) * 2007-02-06 2011-02-16 Toyota Motor Co Ltd Dispositif de purification d'échappement pour moteur à combustion interne
CN101542084B (zh) * 2007-02-06 2011-12-14 丰田自动车株式会社 内燃机的排气净化装置
US8307639B2 (en) 2007-02-06 2012-11-13 Toyota Jidosha Kabushiki Kaisha Exhaust purification device of internal combustion engine
WO2010026018A1 (fr) * 2008-08-25 2010-03-11 Torsten Schlicht Procédé et installation de gaz d’échappement pour l’épuration de gaz d’échappement contenant des sox, en particulier provenant des moteurs à combustion interne de bateaux

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