[go: up one dir, main page]

WO2018180705A1 - Catalyseur de purification de gaz d'échappement - Google Patents

Catalyseur de purification de gaz d'échappement Download PDF

Info

Publication number
WO2018180705A1
WO2018180705A1 PCT/JP2018/010816 JP2018010816W WO2018180705A1 WO 2018180705 A1 WO2018180705 A1 WO 2018180705A1 JP 2018010816 W JP2018010816 W JP 2018010816W WO 2018180705 A1 WO2018180705 A1 WO 2018180705A1
Authority
WO
WIPO (PCT)
Prior art keywords
exhaust gas
layer
pore
catalyst
trapping layer
Prior art date
Application number
PCT/JP2018/010816
Other languages
English (en)
Japanese (ja)
Inventor
江里子 田中
Original Assignee
株式会社キャタラー
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 株式会社キャタラー filed Critical 株式会社キャタラー
Publication of WO2018180705A1 publication Critical patent/WO2018180705A1/fr

Links

Images

Classifications

    • 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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
    • B01J23/54—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
    • B01J23/56—Platinum group metals
    • B01J23/63—Platinum group metals with rare earths or actinides
    • 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
    • F01N3/02—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust
    • F01N3/021—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters
    • F01N3/022—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters characterised by specially adapted filtering structure, e.g. honeycomb, mesh or fibrous
    • 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
    • F01N3/02—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust
    • F01N3/021—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters
    • F01N3/033—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters in combination with other devices
    • F01N3/035—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters in combination with other devices with catalytic reactors
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/50—Catalysts, in general, characterised by their form or physical properties characterised by their shape or configuration
    • B01J35/56—Foraminous structures having flow-through passages or channels, e.g. grids or three-dimensional monoliths

Definitions

  • the present invention relates to an exhaust gas purifying catalyst. Specifically, the present invention relates to an exhaust gas purifying catalyst having a catalyst layer containing a metal catalyst.
  • Exhaust gas discharged from an internal combustion engine such as a diesel engine or a gasoline engine contains particulate matter (PM) mainly composed of carbon (PM).
  • PM particulate matter
  • an exhaust gas purification filter In order to efficiently collect and remove this from the exhaust gas, an exhaust gas purification filter has been conventionally used.
  • an exhaust gas purification catalyst in which an exhaust gas purification filter and another catalyst are integrated has been promoted from the viewpoint of the mountability of an exhaust gas purification system.
  • a catalyst layer containing a three-way catalyst is formed on an exhaust gas purification filter for collecting PM, and simultaneously with the collection of PM, carbon monoxide (CO), hydrocarbon (HC), nitrogen oxide ( NO x) an exhaust gas purifying catalyst for purifying (gasoline particulate filter (GPF)) is proposed.
  • the catalyst layer is formed containing a SCR catalyst in the exhaust gas purifying filter for PM trapping, at the same time as the trapping of PM, is proposed an exhaust gas purifying catalyst (SCR filter) to perform the purification of the NO x Yes.
  • SCR filter exhaust gas purifying catalyst
  • Patent Document 1 discloses a catalytic filter (exhaust gas purification catalyst) in which a base material having porous partition walls is used and a catalyst layer containing a three-way catalyst is provided inside the partition walls of the base material. .
  • this catalytic filter the diameter of the pores of the partition walls is reduced by the catalyst layer, so that PM in the exhaust gas can be collected by functioning the partition walls as a filter medium.
  • Patent Document 2 discloses an exhaust gas purification filter catalyst in which a fiber layer in which fibrous materials made of a heat-resistant material are intertwined is formed on the outermost surface of a cell partition wall of an entry side cell.
  • PM having a large particle size can be collected by the fiber layer before reaching the cell partition wall surface.
  • Patent Document 3 discloses that a catalyst layer having a gap of 0.5 ⁇ m to 1.0 ⁇ m in diameter can be filtered by adding a foaming agent (pore forming agent) such as citric acid or starch to the slurry for catalyst formation. Techniques for forming the surface and the pores of the filter are disclosed.
  • the diameter of the gap is set to 0.5 ⁇ m or more so that PM secondary particles (about 0.5 ⁇ m in diameter) in which a plurality of PMs are aggregated easily enter the gap of the catalyst layer, and the contact ratio between PM and the catalyst is increased.
  • the diameter of the gap is set to 1.0 ⁇ m or less.
  • the acicular material constituting the fiber layer may be oriented in the same direction.
  • the gas permeability in a fiber layer falls and the problem that a pressure loss raises significantly generate
  • voids are formed in the catalyst layer.
  • the voids are slightly larger than the PM secondary particles, the voids are clogged when the collected PM is deposited. There is a problem that a sudden rise in pressure loss occurs.
  • the present invention has been created to solve such a problem.
  • the purpose of the present invention is to suppress an increase in pressure loss, to suitably collect PM, and to further purify harmful components other than PM. It is to provide a purification catalyst.
  • the exhaust gas-purifying catalyst disclosed herein is disposed in the exhaust passage of the internal combustion engine, and collects particulate matter in the exhaust gas discharged from the internal combustion engine.
  • Such an exhaust gas purifying catalyst includes a base material having porous partition walls, a catalyst layer provided inside the partition walls of the base material, and a porous PM trapping layer provided on the partition walls of the base material.
  • the catalyst layer includes a support and a metal catalyst.
  • PM collection layer contains a metal oxide, and when the said PM collection layer is made into 100% in the electron microscope observation image of a cross section, a large pore with a circle equivalent diameter larger than 5 micrometers is 45% or more. Accounted for.
  • a porous PM trapping layer is formed on the catalyst layer.
  • Such a porous PM collection layer functions as a filtration layer, and when exhaust gas passes through the PM collection layer, PM in the exhaust gas can be collected.
  • the PM trapping layer of the exhaust gas purifying catalyst disclosed here is formed such that large pores having an equivalent circle diameter larger than 5 ⁇ m occupy 45% or more of the PM trapping layer. Since this PM collection layer has relatively large pores at a high ratio compared to the fiber layer of Patent Document 2 and the catalyst layer of Patent Document 3 described above, it has a significantly high gas permeability. Have. For this reason, in such an exhaust gas purifying catalyst, a good gas flow path is secured, and an increase in pressure loss can be suitably suppressed.
  • this PM collection layer can exhibit a PM collection function as a filtration layer as above-mentioned, it can suppress invasion of PM into the partition of a base material. For this reason, compared with the technique described in Patent Document 3, for example, an increase in pressure loss during PM deposition can be suppressed relatively low. Moreover, pressure loss hysteresis can be reduced.
  • the catalytic function is exhibited when the exhaust gas passes through the partition wall of the filter, so that the gas flow into the partition wall becomes uneven or hindered. If it does, there exists a tendency for the purification performance with respect to harmful components other than PM to fall.
  • the present inventor has confirmed that the purification performance of the exhaust gas purification catalyst disclosed herein can be maintained in a relatively good state. This is because a PM trapping layer having a large proportion of large pores has good gas permeability, so that a sufficient amount of exhaust gas is discharged to the catalyst layer formed under the PM trapping layer. Presumably because it can be supplied uniformly.
  • the amount of PM (PM accumulation amount) collected by the exhaust gas purification catalyst (or exhaust gas purification filter) is estimated based on pressure loss. That is, when the pressure loss exceeds a predetermined value, it is determined that the PM accumulation amount has increased, and the regeneration process is performed.
  • the pressure loss stably increases in accordance with the amount of PM trapped. Therefore, the amount of PM trapped can be accurately estimated based on the pressure loss rise, and the regeneration controllability can be achieved. Can be improved.
  • the large pores are 60% or more when the entire pores are 100%. Accounted for. Thereby, the gas permeability of the PM trapping layer becomes better, and an increase in pressure loss and PM deposition pressure loss associated with the formation of the PM trapping layer can be suppressed better. Therefore, the effect of the present invention can be exhibited at a high level.
  • the porosity of the PM trapping layer is 70% or more in the electron microscope observation image of the cross section of the PM trapping layer.
  • the PM trapping layer has a first pore having a pore diameter of 1 ⁇ m or more and less than 10 ⁇ m, and a pore diameter of 0.5 ⁇ m or more and 1 ⁇ m.
  • a multi-pore structure having second pores that are less than thereby, since the PM collection layer has a structure having multistage pore diameters (openings), a more excellent PM collection function can be exhibited. As a result, PM can be highly inhibited from entering the catalyst layer. Therefore, the effect of the present invention can be exhibited at a high level.
  • the pore volume of the first pore is the pore volume of the second pore. 4 times or more. Thereby, the gas permeability of PM collection layer becomes still better, and suppression of pressure loss can be exhibited at a still higher level.
  • the surface aperture ratio is 25% or more in the electron microscope observation image of the surface of the skeleton portion of the PM trapping layer.
  • the pore diameter P corresponding to 5% cumulative from the small pore side 5 and a pore diameter P 95 corresponding to a cumulative 95% from the small pore side are both 0.02 ⁇ m or more and 4 ⁇ m or less.
  • the PM trapping layer provided on the catalyst layer has an extension direction of the partition walls from an end on the exhaust gas inflow side when the total length in the extension direction of the partition walls is 100%. Is provided with a length of 90% or more.
  • FIG. 1 is a diagram schematically illustrating an exhaust gas purification apparatus according to an embodiment.
  • FIG. 2 is a perspective view schematically showing an exhaust gas purifying catalyst according to an embodiment.
  • FIG. 3 is a diagram schematically showing a cross section along the cylinder axis direction of the exhaust gas purifying catalyst according to the embodiment.
  • FIG. 4 is a cross-sectional SEM observation image (magnification: 200 times) of the exhaust gas purifying catalyst according to an embodiment.
  • FIG. 5 is a graph showing the pressure loss increase rate measured in the test example.
  • FIG. 6 is a graph showing the PM collection rate measured in the test example.
  • FIG. 7 is a graph showing the PM discharge behavior measured in the test example.
  • FIG. 8 is a cross-sectional SEM observation image of the exhaust gas purifying catalyst of Example 1.
  • FIG. 9 is a surface SEM observation image of the PM trapping layer of Example 1.
  • Drawing 1 is a mimetic diagram of exhaust gas purification device 1 concerning one embodiment.
  • the exhaust gas purification device 1 is provided in the exhaust system of the internal combustion engine 2.
  • the internal combustion engine (engine) 2 is supplied with an air-fuel mixture containing oxygen and fuel gas.
  • the internal combustion engine 2 burns this air-fuel mixture and converts the combustion energy into mechanical energy.
  • the air-fuel mixture combusted at this time becomes exhaust gas and is discharged to the exhaust system.
  • the internal combustion engine 2 having the configuration shown in FIG. 1 is mainly composed of an automobile gasoline engine.
  • the exhaust gas purifying apparatus 1 can also be applied to engines other than gasoline engines (for example, diesel engines).
  • the exhaust gas purifying apparatus 1 includes an exhaust passage (exhaust manifold 3 and exhaust pipe 4), an ECU 5, an exhaust temperature increasing catalyst 9 including a carrier and a metal catalyst, and an exhaust gas purifying catalyst 10.
  • the exhaust gas purification device 1 purifies harmful components (for example, carbon monoxide (CO), hydrocarbons (HC), nitrogen oxides (NO x )) contained in the exhaust gas discharged from the internal combustion engine 2, and converts the exhaust gas into the exhaust gas. Collect particulate matter (PM) contained.
  • One end of the exhaust manifold 3 is connected to an exhaust port (not shown) that connects the internal combustion engine 2 and the exhaust system.
  • the other end of the exhaust manifold 3 is connected to the exhaust pipe 4.
  • the arrow in a figure has shown the distribution direction of waste gas.
  • the exhaust manifold 3 and the exhaust pipe 4 constitute an exhaust gas exhaust passage.
  • An exhaust gas temperature raising catalyst 9 and an exhaust gas purification catalyst 10 are arranged in the exhaust pipe 4.
  • the exhaust gas temperature raising catalyst 9 is provided upstream of the exhaust gas purifying catalyst 10.
  • the exhaust gas temperature increasing catalyst 9 has a function of increasing the exhaust gas temperature flowing into the exhaust gas purifying catalyst 10 when the exhaust gas purifying catalyst 10 is regenerated.
  • the exhaust temperature raising catalyst 9 may be, for example, a conventionally known three-way catalyst, typically a catalyst including a noble metal such as platinum (Pt), palladium (Pd), rhodium (Rh).
  • a noble metal such as platinum (Pt), palladium (Pd), rhodium (Rh).
  • the exhaust temperature raising catalyst 9 is not necessarily required, and may be omitted depending on circumstances. Note that the configuration of the exhaust gas temperature raising catalyst 9 does not characterize the present invention, and thus the description thereof is omitted here.
  • the ECU 5 is an engine control unit that controls the internal combustion engine 2 and the exhaust gas purification device 1.
  • the ECU 5 includes a digital computer, for example, like a general control device.
  • the ECU 5 further includes a central processing unit (CPU: central processing unit) that executes instructions of the control program, a ROM (read only memory) that stores the control program executed by the CPU, and a working area for developing the control program.
  • CPU central processing unit
  • ROM read only memory
  • a RAM random access memory
  • storage device recording medium
  • the ECU 5 is provided with an input port (not shown).
  • the ECU 5 is electrically connected to sensors (for example, a pressure sensor 8) installed in each part of the internal combustion engine 2 and the exhaust gas purification device 1. Thereby, the information detected by each sensor is transmitted to the ECU 5 as an electrical signal through the input port.
  • the ECU 5 is also provided with an output port (not shown).
  • the ECU 5 controls the internal combustion engine 2 and the exhaust gas purification device 1 by transmitting a control signal via the output port.
  • the ECU 5 estimates how much PM is collected in the exhaust gas purification catalyst 10 (PM accumulation amount) based on the pressure loss value of the pressure sensor 8.
  • PM accumulation amount the pressure loss value exceeds a predetermined value
  • the ECU 5 raises the exhaust gas purifying catalyst 10 to a predetermined temperature, and burns and removes PM.
  • the exhaust gas purification apparatus 1 provided with the exhaust gas purification catalyst 10 is excellent in regeneration controllability. Further, the exhaust gas purification device 1 can improve fuel efficiency by minimizing the frequency of the regeneration process.
  • FIG. 2 is a perspective view of the exhaust gas purifying catalyst 10 according to one embodiment.
  • FIG. 3 is a view schematically showing a cross section along the cylinder axis direction of the exhaust gas purifying catalyst 10 according to one embodiment.
  • FIG. 4 is a cross-sectional SEM observation image (magnification: 200 times) of the exhaust gas purifying catalyst 10 according to an embodiment.
  • the exhaust gas flow direction is depicted by the arrow direction. That is, the left side of FIGS. 2 and 3 is the upstream side of the exhaust passage (exhaust pipe 4), and the right side is the downstream side of the exhaust path (exhaust pipe 4).
  • the exhaust gas purification catalyst 10 has a function of collecting particulate matter (PM) contained in the exhaust gas and purifying the exhaust gas.
  • the exhaust gas purifying catalyst 10 of this embodiment includes a base material 11 having porous partition walls 16, a catalyst layer 30 formed inside the partition walls 16 of the base material 11, and a porous layer formed on the catalyst layer 30.
  • the PM collection layer 20 is provided.
  • each member which comprises this exhaust gas purification catalyst 10 is demonstrated.
  • the base material 11 constitutes the framework of the exhaust gas purifying catalyst 10.
  • various materials and forms conventionally used for this type of application can be appropriately employed.
  • those formed of a high heat-resistant material such as ceramics such as cordierite, aluminum titanate, silicon carbide (SiC), and alloys such as stainless steel can be suitably used.
  • the outer shape of the substrate 11 can be a cylindrical shape, an elliptical cylindrical shape, a polygonal cylindrical shape, or the like.
  • a base material 11 having a cylindrical outer shape is employed.
  • the shape of the base material 11 can be, for example, a honeycomb shape, a foam shape, a pellet shape, and the like. In the embodiment of FIG. 2, the honeycomb-shaped base material 11 is employed.
  • the base material 11 includes an inlet cell 12 having an open end on the exhaust gas inflow side, an exit cell 14 having an end on the exhaust gas outflow side, and an inlet cell 12.
  • a partition wall 16 that partitions the outlet cell 14 is provided.
  • a sealing portion 12a is disposed and sealed at the end of the inlet side cell 12 on the exhaust gas outflow side.
  • a sealing portion 14a is disposed and sealed at the end of the outlet cell 14 on the exhaust gas inflow side.
  • the shapes of the entrance side cell 12 and the exit side cell 14 are various geometric shapes such as a square, a parallelogram, a rectangle such as a rectangle and a trapezoid, a triangle, other polygons (for example, a hexagon, an octagon), and a circle. It can be a shape.
  • the partition wall 16 that partitions the inlet side cell 12 and the outlet side cell 14 has a porous structure through which exhaust gas can pass.
  • the average pore diameter of the partition wall 16 is not particularly limited, but is preferably about 5 to 30 ⁇ m, for example, 10 to 20 ⁇ m, from the viewpoint of improving PM collection performance and suppressing an increase in pressure loss.
  • the thickness of the partition wall 16 is not particularly limited, but is preferably about 1 to 30 mils (1 mil is about 25.4 ⁇ m) from the viewpoint of improving PM collection performance and suppressing an increase in pressure loss.
  • the porosity of the partition wall 16 is not particularly limited, but is preferably about 20 to 70% by volume, for example, 30 to 60% by volume, from the viewpoint of improving PM collection performance and suppressing an increase in pressure loss.
  • the catalyst layer 30 is provided inside the partition wall 16 of the base material 11 described above.
  • the catalyst layer 30 in the present embodiment includes two types of layers, that is, an entry side catalyst layer 32 and an exit side catalyst layer 34.
  • the entry side catalyst layer 32 is provided on the exhaust gas inflow side inside the partition wall 16, and the exit side catalyst layer 34 is provided on the exhaust gas outflow side inside the partition wall 16.
  • the inlet side catalyst layer 32 is formed with a predetermined thickness from the surface of the partition wall 16 in contact with the inlet side cell 12 toward the inside of the partition wall 16, and from the vicinity of the end on the exhaust gas inflow side. It is formed in a predetermined length along 16 extending directions X.
  • the outlet side catalyst layer 34 is formed with a predetermined thickness from the surface of the partition wall 16 in contact with the outlet side cell 14 toward the inner side of the partition wall 16 and extends from the vicinity of the end on the exhaust gas outflow side.
  • a predetermined length is formed along the direction X.
  • Each layer (incoming catalyst layer 32 and outgoing catalyst layer 34) constituting the catalyst layer 30 in the present embodiment includes a carrier and a metal catalyst supported on the carrier.
  • a metal catalyst that can be used for this type of exhaust gas purifying catalyst can be used without particular limitation.
  • a metal catalyst for example, a three-way catalyst that oxidizes CO and HC in exhaust gas and reduces NO x can be used.
  • the three-way catalyst include platinum group elements such as platinum (Pt), palladium (Pd), rhodium (Rh), ruthenium (Ru), osmium (Os), and iridium (Ir).
  • the metal catalyst included in the catalyst layer 30 is not limited to the above-described three-way catalyst.
  • an SCR catalyst that reduces NO x in an atmosphere in which a predetermined reducing agent (such as urea) is present. can also be used.
  • a transition metal ion exchange zeolite in which a transition metal (such as Cu or Fe) is supported on zeolite can be used.
  • the content of the metal catalyst is not particularly limited, but for example, in the range of 0.01% by mass to 10% by mass (for example, 0.05% by mass to 5% by mass) with respect to the total mass of the support contained in the catalyst layer 30. It is good to do.
  • the composition of harmful components in the exhaust gas and the exhaust gas inside the substrate It is preferable to appropriately change the type and content of the metal catalyst used for the inlet side catalyst layer 32 and the outlet side catalyst layer 34 in consideration of the distribution route and the like. Thereby, more preferable exhaust gas purification performance can be exhibited.
  • a metal oxide having a large specific surface area and high durability (particularly heat resistance) is preferably used for the carrier supporting the metal catalyst.
  • the metal oxide used in such a carrier include alumina (Al 2 O 3 ), ceria (CeO 2 ), zirconia (ZrO 2 ), silica (SiO 2 ), titania (TiO 2 ), and the like.
  • the catalyst layer 30 may contain various additives in addition to the metal catalyst and the carrier.
  • an OSC material can be used as the additive.
  • Such an OSC material has a function of occluding and releasing oxygen, and the exhaust gas atmosphere inside the catalyst layer 30 can be stably maintained in the vicinity of stoichiometric (theoretical air-fuel ratio). Can be exhibited stably.
  • Examples of such OSC materials include ceria-zirconia composite oxide.
  • Another example of additives contained in the catalyst layer 30 is, like the NO x adsorbing agent and stabilizer with the NO x storage capacity.
  • the catalyst layer 30 is formed inside the partition wall 16, whereby the pores of the partition wall 16 are narrowed.
  • the thickness of the catalyst layer 30 formed in the pores of the partition wall 16 is about 0.1 ⁇ m to 6 ⁇ m (for example, about 3 ⁇ m), and the pores of the partition wall 16 after the formation of the catalyst layer 30 is 5 ⁇ m to 15 ⁇ m (for example, about 12 ⁇ m).
  • PM trapping layer As shown in FIGS. 3 and 4, in the exhaust gas purifying catalyst 10 according to this embodiment, PM is formed on the partition wall 16 of the base material 11 (the surface on the side in contact with the inlet cell 12). A collection layer 20 is provided. As shown in FIG. 4, the PM trapping layer 20 is a layer in which large pores are formed at a high rate. By providing such a PM trapping layer 20 on the partition wall 16, an increase in pressure loss of the exhaust gas purifying catalyst 10 can be suppressed and PM can be trapped suitably. Further, since the PM trapping layer 20 does not greatly hinder the catalytic action of the metal catalyst in the catalyst layer 30, in this embodiment, harmful components (CO, HC, NO x ) other than PM are suitably used. It can also be purified. Hereinafter, the PM collection layer 20 in the present embodiment will be specifically described.
  • the skeleton portion of the PM trapping layer 20 mainly contains a metal oxide.
  • a metal oxide a material having predetermined heat resistance and strength can be preferably used.
  • alumina Al 2 O 3
  • ceria CeO 2
  • zirconia ZrO 2
  • silica SiO 2
  • a material formed of a heat-resistant material such as titania (TiO 2 ) can be preferably used.
  • the shape of the metal oxide contained in the skeleton portion of the PM trapping layer 20 is preferably a needle shape having a high aspect ratio.
  • the “needle shape” in the present specification is a concept including a shape called a long bar shape, a wire shape, a scale shape, or the like.
  • the average aspect ratio of such acicular metal oxide particles is approximately 3 or more, preferably Is preferably 5 or more, for example, about 10 to 50.
  • the average length of the metal oxide particles in the major axis direction is generally about 0.1 ⁇ m or more, preferably 0.5 ⁇ m or more, for example, 1 to 10 ⁇ m.
  • the average length (typically the diameter) of the metal oxide particles in the minor axis direction is generally about 0.01 ⁇ m or more, preferably 0.05 ⁇ m or more, for example, 0.1 to 1 ⁇ m.
  • the width of the PM collection layer 20 is not particularly limited.
  • the PM trapping layer 20 may be provided on the entire wall surface of the partition wall 16 or may be provided only on a part thereof. In one example, when the total surface area of the partition 16 is 100%, the PM trapping layer 20 may cover the surface of approximately 50% or more, for example, 80% or more, preferably 90% or more.
  • the length of the PM trapping layer 20 is approximately when the total length Lw of the partition wall 16 in the extending direction X (in the exhaust gas flow direction) is 100%.
  • the PM trapping layer 20 may be provided continuously on the wall surface of the partition wall 16 or may be provided intermittently. Further, the length of the PM trapping layer 20 can be adjusted by, for example, the amount of slurry introduced in the manufacturing method described later.
  • the average thickness of PM collection layer 20 (the length perpendicular to the extending direction of partition wall 16) is not particularly limited, but from the viewpoint of exhibiting the effect of the present invention at a high level and from the viewpoint of better exhibiting PM collection performance. It is generally about 1 to 300 ⁇ m, typically 5 to 100 ⁇ m, for example, about 10 to 50 ⁇ m. Further, the coating amount per 1 L of the base material of the PM trapping layer 20 is not particularly limited, but from the viewpoint of reducing the pressure loss at a higher level, it is generally 100 g / L or less, preferably 50 g / L or less, for example, 30 g. / L or less.
  • the PM trapping layer 20 has a high porosity and has structural characteristics excellent in gas permeability.
  • the porosity of the PM collection layer 20 calculated based on observation with an electron microscope (that is, the ratio of pores in the PM collection layer 20) Va is approximately 60% or more, preferably 70% or more, It may be 90% or less, typically 85% or less, for example 80% or less.
  • the mechanical strength of PM collection layer 20 can be improved by making said porosity Va into a predetermined value or less.
  • the porosity Va can be adjusted, for example, by controlling the mixing ratio of the carrier and the pore-forming agent in the slurry and the size (particle size) of the carrier and / or the pore-forming agent in the production method described later. .
  • the porosity Va of the PM collection layer 20 can be calculated as follows. (1) First, a sample piece including the PM collection layer 20 is embedded with a resin, and the cross section of the PM collection layer 20 is cut out. (2) Next, the cross section of the cut specimen is observed with a scanning electron microscope (SEM) to obtain a cross-sectional SEM observation image (reflection electron image, observation magnification 600 times). The observation visual field is set so that approximately 20 or more, for example, 50 or more pores partitioned by the skeleton portion of the PM collection layer 20 are included, and a cross-sectional SEM observation image is obtained.
  • SEM scanning electron microscope
  • the porosity of large pores calculated based on observation with an electron microscope (that is, the ratio of pores having an equivalent circle diameter larger than 5 ⁇ m in the PM collection layer 20) Vb is about 45. % Or more, for example, 50% or more, and is not more than Va as described above, and is generally 85% or less, typically 80% or less, for example, 70% or less.
  • Vb of the large pores By setting the porosity Vb of the large pores to a predetermined value or more, gas permeability can be improved, and an increase in pressure loss accompanying the formation of the PM trapping layer 20 can be suppressed.
  • the mechanical strength of PM collection layer 20 can be improved by making said Vb into a predetermined value or less.
  • the porosity Vb can be adjusted, for example, by controlling the mixing ratio of the carrier and the pore-forming agent in the slurry and the size (particle size) of the carrier and / or the pore-forming agent in the production method described later. .
  • the porosity Vb of the large pores of the PM collection layer 20 is a pore portion having an equivalent circle diameter of 5 ⁇ m or less from the porosity (the porosity calculated in the above (6)) Va of the PM collection layer 20. After removing, the ratio (area%) of the area occupied by the pores can be measured and calculated.
  • the ratio of the porosity Vb of the large pores to the porosity Va is approximately 60% or more, preferably 70% or more, and approximately 99% or less, typically It may be 98% or less, for example 90% or less, and in one example 80% or less.
  • the PM trapping layer 20 typically has a first pore defined by a skeleton portion and a second pore formed inside the skeleton portion and communicating with the first pore. And have.
  • the PM collection layer 20 has a multi-pore structure (for example, a binary pore structure), and is configured so that PM can be collected also in the skeleton portion.
  • the average pore diameter of the first pore and the second pore is equal to or less than the average pore diameter of the pores of the partition wall 16 after the catalyst layer 30 (typically, the entrance catalyst layer 32) is formed. Preferably, it is smaller than the average pore diameter of the pores of the partition wall 16 after the catalyst layer 30 is formed.
  • the average pore size relationship satisfies the following relationship: second pore ⁇ first pore ⁇ pore of partition wall 16 after formation of catalyst layer 30.
  • the PM trapping layer 20 has first pores partitioned by a skeleton portion, and is configured in a three-dimensional network.
  • the arbitrary cross section of the PM trapping layer 20 may have a plurality of divided portions by dividing the skeleton portion. It is considered that the greater the number of divided parts (number of divisions), the higher the pore connectivity. That is, the number of divisions can be an index indicating the connectivity of the pores in the PM collection layer 20.
  • the number of divisions per unit cross-sectional area (0.01 mm 2 ) is approximately 10 or more, typically 20 or more, preferably 30.
  • the number of divisions per unit cross-sectional area of the skeleton portion can be calculated as follows. (1) First, a sample piece including the PM collection layer 20 is embedded with a resin, and the cross section of the PM collection layer 20 is cut out. (2) Next, the cross section of the cut specimen is observed with a scanning electron microscope (SEM) to obtain a cross-sectional SEM observation image (reflection electron image, observation magnification 600 times). (3) Next, using the two-dimensional image analysis software winroof (registered trademark), the processing range is set in the PM trapping layer 20, and the skeleton portion is extracted by automatic binarization (discriminant analysis method). Get a value image.
  • SEM scanning electron microscope
  • the average thickness of the skeleton portion is approximately 5 ⁇ m or less, typically 4 ⁇ m or less, preferably 3.5 ⁇ m or less, for example, 3 ⁇ m or less. Thereby, the increase in the pressure loss accompanying formation of PM collection layer 20 can be suppressed.
  • the lower limit of the average thickness is not particularly limited, but from the viewpoint of improving the mechanical strength, it is preferably about 0.5 ⁇ m or more, typically 1 ⁇ m or more, for example, 1.5 ⁇ m or more.
  • the average thickness of the skeleton part is the same as the calculation of the number of divisions described above, and after performing (1) to (4), the length of the shortest part (minimum length passing through the center of gravity) for each divided part is It is obtained by calculating and arithmetically averaging the values.
  • the surface opening ratio of the skeleton portion is approximately 20% or more, typically 25% or more, preferably 30% or more, and generally 60% or less, typically 55%.
  • the surface aperture ratio of the skeleton portion of the PM trapping layer 20 can be calculated as follows. (1) First, the sample piece including the PM trapping layer 20 is fixed to the surface of the sample table so that the extending direction of the substrate 11 and the surface of the sample table are parallel to each other. (2) Next, the surface of the sample piece was observed with a field emission scanning electron microscope (FE-SEM), and a surface SEM observation image (secondary electron image, observation magnification 20000 times) from the outermost surface side of the PM collection layer 20. ) (3) Next, using a two-dimensional image analysis software winroof (registered trademark), a surface opening is extracted by automatic binarization (discriminant analysis method) to obtain a binary image.
  • FE-SEM field emission scanning electron microscope
  • a surface SEM observation image secondary electron image, observation magnification 20000 times
  • the average pore diameter of the second pores formed in the skeleton portion of the PM trapping layer 20 is typically smaller than the average pore diameter of the first pores, for example, smaller than 5 ⁇ m.
  • the pore diameter P 5 corresponding to a cumulative 5% from the small pore side having a smaller pore diameter is, for example, 0.01 ⁇ m or more, preferably 0.02 ⁇ m or more, typically 0.03 ⁇ m or more, for example, 0.035 ⁇ m or more. In general, it is preferably 0.1 ⁇ m or less, typically 0.05 ⁇ m or less, for example 0.04 ⁇ m or less.
  • the pore diameter P 95 corresponding to 95% cumulative from the small pore side having a small pore diameter is generally 1 ⁇ m or more, typically 1.5 ⁇ m or more, for example, 2 ⁇ m or more, for example, 5 ⁇ m or less, preferably 4 ⁇ m. Hereinafter, it is typically 3.5 ⁇ m or less, for example, 3 ⁇ m or less.
  • the pore diameter P 5 and the pore diameter P 95 are both 0.01 to 5 ⁇ m, preferably 0.02 to 4 ⁇ m.
  • the average pore diameter of the second pores was determined by measuring the shape characteristics in the analyzed image after performing steps (1) to (4) in the same procedure as the calculation of the surface opening ratio. It is obtained by measuring the equivalent diameter.
  • the pores included in the PM collection layer 20 have pores that are equal to or smaller than the pore size of the partition wall 16 after the catalyst layer 30 is formed.
  • the PM trapping layer 20 has two pore peaks in the pore diameter range of 0.5 to 10 ⁇ m.
  • the peak A may have a peak A in a range of 1 ⁇ m or more and less than 10 ⁇ m
  • the peak B may have a peak B in a range of a pore size of 0.5 ⁇ m or more and less than 1 ⁇ m.
  • the two peaks A and B are the first pores defined by the skeleton portion of the PM trapping layer 20 and the first pores formed inside the skeleton portion and communicating with the first pores. 2 pores may be suggested.
  • the pore volume (V1) of the peak A derived from the first pore is approximately 0.03 cm 3 / g or more, preferably 0.04 cm 3 / g or more, More preferably, it is 0.05 cm 3 / g or more. Thereby, the increase in the pressure loss accompanying formation of PM collection layer 20 can be suppressed.
  • V1 is approximately 0.1 cm 3 / g or less, for example, may is 0.08 cm 3 / g or less.
  • the pore volume (V2) of the peak B derived from the second pore is typically smaller than the peak A.
  • V2 is approximately 0.02 cm 3 / g or less, for example, it is 0.015 cm 3 / g or less may.
  • the ratio (V1 / V2) of the pore volume of the first pore to the pore volume of the second pore is approximately 3 or more, preferably 4 or more, more preferably 5 or more, for example 6 or more. . Thereby, the increase in the pressure loss accompanying formation of PM collection layer 20 can be suppressed.
  • an upper limit is not specifically limited, From a viewpoint of improving mechanical strength, it is generally 30 or less, preferably 20 or less, for example, 10 or less.
  • the pore distribution of the PM trapping layer 20 can be calculated as follows. First, a sample piece of the base material 11 provided with the PM collection layer 20 and the catalyst layer 30 is prepared, and the pore distribution of the sample piece is measured in a pressure range of 1 to 60000 psi using a commercially available mercury porosimeter. To do. Thereby, the pore distribution curve which shows the relationship between pore diameter and pore volume is obtained. By comparing the obtained pore distribution curve with the pore distribution curve of the substrate 11 on which only the catalyst layer 30 is provided, the state of the pores formed in the PM collection layer 20 is confirmed. Moreover, the pore volume of each peak can be calculated
  • the integrated pore volume (cm 3 / g) of each peak of the sample piece including the PM collection layer 20 is calculated from the integrated pore volume distribution curve, and the base material on which only the catalyst layer 30 is provided.
  • the pore volume (cm 3 / g) per unit mass of the PM trapping layer 20 can be obtained by subtracting the pore volume in the region of 11 in the same range.
  • the PM trapping layer 20 having large pores at a relatively high ratio as compared with the prior art is formed.
  • gas permeability is improved, so that an increase in pressure loss accompanying the formation of the PM trapping layer 20 can be suppressed.
  • the exhaust gas purifying catalyst according to the present embodiment can simultaneously purify (detoxify) harmful components other than PM in the exhaust gas while the exhaust gas passes through the catalyst layer 30.
  • the purification performance of the metal catalyst in the catalyst layer tends to decrease, but in this embodiment, Since the PM trapping layer 20 having a relatively high proportion of large pores is formed, a sufficient amount of exhaust gas can be supplied to the catalyst layer 30, and the purification performance of the catalyst layer 30 can be improved. Degradation can be kept to a minimum.
  • the PM collection layer 20 according to the present embodiment has a multi-pore structure (for example, a binary pore structure) including first pores and second pores, and the skeleton of the PM collection layer 20. The part has a PM trapping function. Therefore, an excellent PM collecting function can be exhibited.
  • the PM trapping layer 20 has a multi-pore structure, so that PM is prevented from being deposited in the pores inside the partition wall 16. Therefore, pressure loss hysteresis can be suppressed.
  • the exhaust gas-purifying catalyst 10 having the above-described configuration can be produced, for example, based on the following procedure.
  • the catalyst layer 30 is formed inside the partition wall 16 of the base material 11.
  • a mixed liquid is prepared by mixing a metal oxide serving as a support and a compound serving as a metal catalyst supply source at a predetermined ratio.
  • the prepared mixed liquid is dried and then fired at a predetermined temperature and time to produce a composite material powder in which a metal catalyst is supported on a carrier.
  • a slurry for forming a catalyst layer is prepared by mixing the composite material together with a desired additive in an appropriate solvent (for example, ion-exchanged water).
  • the catalyst layer 30 is formed inside the partition wall 16 by applying the slurry for forming the catalyst layer to the partition wall 16 of the substrate 11 and then drying the slurry.
  • the catalyst layer forming slurry is supplied to the inlet cell 12 of the substrate 11.
  • suction is performed from the exit side cell 14.
  • the slurry permeates from the inlet side cell 12 into the partition wall 16, so that the inlet side catalyst layer 32 can be formed inside the partition wall 16 by drying the base material 11 in this state.
  • the slurry for forming the catalyst layer is supplied to the exit side cell 14 of the base material 11 and sucked from the entrance side cell 12, so that the slurry is infiltrated into the partition wall 16 from the exit side cell 14.
  • the outlet catalyst layer 34 can be formed inside the partition wall 16.
  • the PM collection layer 20 is formed on the partition wall 16 of the substrate 11. Specifically, first, a metal oxide powder serving as a skeleton of the PM collection layer 20 is prepared, and the metal oxide powder, a pore-forming agent, and an appropriate solvent (for example, ion-exchanged water) are in a predetermined ratio. To prepare a slurry for forming a PM trapping layer. Next, the PM collection layer forming slurry is supplied into the inlet cell 12 of the base material 11, and the PM collection layer forming slurry is applied onto the partition wall 16 of the base material 11. By drying and baking the base material 11 in this state, the PM trapping layer 20 is formed on the partition wall 16 of the base material 11.
  • a metal oxide powder serving as a skeleton of the PM collection layer 20 is prepared, and the metal oxide powder, a pore-forming agent, and an appropriate solvent (for example, ion-exchanged water) are in a predetermined ratio.
  • an appropriate solvent for example, ion-exchanged water
  • the pore-forming agent contained in the PM trapping layer forming slurry is thermally decomposed and removed during firing, and the portions where the pore-forming agent was present become pores.
  • a porous PM trapping layer in which large pores having an equivalent circle diameter larger than 5 ⁇ m occupy 45% or more of the volume of the PM trapping layer can be formed.
  • the metal oxide is prevented from being aligned in the same direction by the action of the pore forming agent, the skeleton portion of the PM trapping layer is also formed to be relatively porous, and suitable gas permeation is achieved. Can demonstrate its sexuality.
  • any pore forming agent may be used as long as it can be thermally decomposed and removed during firing.
  • examples include starch, carbon powder, activated carbon, and polymer organic materials (for example, polyethylene, polypropylene, melamine resin, polymethyl methacrylate (PMMA) resin) and the like.
  • the average particle diameter of the pore former is approximately 2 ⁇ m or more, preferably 5 ⁇ m or more, for example, about 5 to 20 ⁇ m.
  • the mixing ratio of the metal oxide powder and the pore forming agent can be an important factor from the viewpoint of realizing the PM trapping layer 20 described above.
  • the mixing ratio of the metal oxide powder and the pore forming agent may vary depending on, for example, the physical properties of the metal oxide powder (for example, the aspect ratio and the length in the long axis direction).
  • the volume may be adjusted to be approximately 3 times or more and approximately 15 times or less, for example, 10 times or less.
  • the PM collection layer 20 with good gas permeability can be realized better.
  • the rate of increase in pressure loss due to the formation of the PM collection layer 20 can be suppressed to approximately 1.6 times or less that of the base material 11 alone.
  • the viscosity of the slurry can also be an important factor from the viewpoint of realizing the PM trapping layer 20 described above.
  • the viscosity of the slurry for forming the PM trapping layer is approximately 30 mPa ⁇ s or more, preferably 50 mPa ⁇ s or more and approximately 500 mPa ⁇ s or less when the measurement temperature is 25 ° C. and the shear rate is 300 to 500 s ⁇ 1. It is good to adjust so that it becomes.
  • the slurry viscosity can be measured with a commercially available viscometer (for example, a dynamic viscoelasticity measuring device). By using the slurry having such a viscosity, the PM trapping layer 20 can be satisfactorily formed on the surface of the substrate.
  • various additives such as a thickener, a surfactant, and a dispersant can be used.
  • the thickener include cellulose polymers such as hydroxyethyl cellulose (HEC), methyl cellulose (MC), carboxymethyl cellulose (CMC), hydroxypropyl methyl cellulose (HPMC), and hydroxyethyl methyl cellulose (HEMC).
  • surfactant a nonionic (nonionic) thing is mentioned, for example.
  • the conditions for drying and firing each slurry are not particularly limited. For example, after drying at about 80 to 300 ° C. for about 1 to 10 hours, about 2 to 4 at about 400 to 1000 ° C. It is good to perform baking for about an hour.
  • the exhaust gas purifying catalyst disclosed herein is not limited to the above-described embodiment.
  • the catalyst layer 30 including two layers of the inlet side catalyst layer 32 and the outlet side catalyst layer 34 is provided, but the catalyst layer of the exhaust gas purifying catalyst disclosed here is It may be composed of a single layer.
  • the catalyst layer of the exhaust gas purifying catalyst disclosed herein only one of the above-mentioned inlet side catalyst layer and outlet side catalyst layer may be formed, or the entire partition wall may be covered. A single catalyst layer may be formed. Even in this case, the effect of the present invention can be appropriately exhibited.
  • the PM collection layer 20 described above may contain various materials other than metal oxides.
  • An example of the additive to the PM trapping layer 20 is a PM combustion metal oxide such as CeO 2 .
  • a PM combustion metal oxide such as CeO 2 .
  • SCR catalyst for the NO x purification such as transition metal ion exchanged zeolite was supported zeolite transition metal (Cu or Fe).
  • Example 1 Formation of catalyst layer >> (Example 1) First, a honeycomb substrate (manufactured by cordierite, number of cells: 300 cpsi, partition wall thickness: 12 mil) was prepared as a substrate. Next, a rhodium nitrate solution (Rh content: 0.2 g) and Al 2 O 3 ( ⁇ -Al 2 O 3 ) powder (40 g) as a carrier are mixed with an appropriate amount of ion-exchanged water, and the mixture is mixed. The liquid was dried and then fired (500 ° C., 1 hour) to obtain Rh-supported-Al 2 O 3 powder.
  • Rh content 0.2 g
  • Al 2 O 3 ⁇ -Al 2 O 3
  • the Rh-supported Al 2 O 3 powder, a ceria-zirconia composite oxide (60 g) as an OSC material, and ion-exchanged water were mixed to prepare an inlet catalyst layer slurry.
  • the prepared slurry for the inlet side catalyst layer is supplied to the inlet side cell of the honeycomb base material from the end portion on the exhaust gas inflow side and then dried, so that the total length Lw of the partition wall is within the partition wall in contact with the inlet side cell.
  • An inlet catalyst layer having a length of 70% was formed.
  • the coating amount of the slurry for the inlet side catalyst layer was adjusted so that the formed inlet side catalyst layer was 45 g / L per base material volume.
  • the outgoing catalyst layer was formed next.
  • the slurry for the exit catalyst layer is the same as the entrance catalyst layer described above except that palladium nitrate as the Pd source is used instead of rhodium nitrate as the Rh source.
  • the prepared slurry for the outlet catalyst layer is supplied to the outlet cell of the honeycomb base material from the exhaust gas outlet end, and then dried, so that the total length Lw of the partition wall is increased in the partition wall in contact with the outlet cell.
  • An outgoing catalyst layer having a length of 50% was formed.
  • the coating amount of the slurry for the inlet side catalyst layer was adjusted so that the formed inlet side catalyst layer was 20 g / L per base material volume.
  • a porous PM trapping layer was formed on the surface of the partition wall on which the catalyst layer was formed.
  • the bead made from melamine resin (average particle diameter of 10 micrometers) was added to this liquid mixture as a pore making material.
  • CMC carboxymethylcellulose
  • the PM trapping layer forming slurry is introduced into the inlet side cell from the end portion on the exhaust gas inflow side, and then sucked from the end portion on the exhaust gas outflow side, whereby the partition wall is formed on the wall surface of the partition wall on the exhaust gas inflow side.
  • the slurry was applied over a region of 100% of the length in the stretching direction. This was dried at 150 ° C. and then calcined at 500 ° C. for 1 hour to thermally decompose and remove the pore former component.
  • a catalyst for exhaust gas purification in which a catalyst layer was formed in the partition and a PM trapping layer was formed on the surface of the partition was produced.
  • the coating amount of the slurry for forming the PM collection layer was adjusted so that the formed catalyst layer was 25 g / L per base material volume.
  • Reference Example 2 A PM collection layer forming slurry is prepared under the same conditions as in Example 1 except that no pore-forming agent is added, and a metal oxide layer is formed on the partition wall surface using the slurry. Thus, an exhaust gas purification catalyst was produced. Other conditions were set to the same conditions as in Example 1 above.
  • Example 3 A slurry for forming a PM collection layer was prepared under the same conditions as in Example 1 except that citric acid (foaming agent) was added instead of melamine resin beads, and a partition wall was prepared using the slurry. A metal oxide layer was formed on the surface to produce an exhaust gas purification catalyst. Other conditions were set to the same conditions as in Example 1 above.
  • Example 7 As a result of investigating the PM emission behavior in the exhaust gas purifying catalysts of Example 1 and Reference Example 1, in Example 1, the PM was appropriately obtained even immediately after the engine was started (within 100 seconds from the start of the test). Was collected and the number of exhausted PM particles was reduced. This is because a normal catalyst such as Reference Example 1 causes a phenomenon that minute PM passes through immediately after the engine starts and the number of discharged PM particles increases, but the PM trapping layer in which large pores are formed at a high rate is used. In the catalyst as in Example 1, it is considered that minute PM is collected in the PM collection layer, and the PM passing immediately after the engine is started is suppressed.
  • the exhaust gas purifying catalyst of Example 1 has no significant decrease in the catalytic activity of the metal catalyst even though a separate PM trapping layer is provided on the catalyst layer. Similar to Example 1. This is presumably because a sufficient amount of exhaust gas could be supplied to the catalyst layer because the PM trapping layer formed on the catalyst layer had high gas permeability.
  • FIGS. 8 is a cross-sectional SEM observation image of the exhaust gas purifying catalyst of Example 1
  • FIG. 9 is a surface SEM observation image of the PM trapping layer of Example 1.
  • a binary pore structure having two types of pores as shown in FIGS. 8 and 9 was formed in the PM trapping layer. That is, in the PM collection layers of Example 1 and Example 2, the relatively large first pores defined by the skeleton portion of the PM collection layer and the relatively small pores formed inside the skeleton portion. Second pores. Further, when looking closely at the second pore, as shown in FIG. 9, in the skeleton portion of the PM trapping layer, the needle-like materials used as carriers are connected to each other to form a network, The pores smaller than the first pore (less than 1 ⁇ m) were distributed.
  • illustration is abbreviate
  • the porosity Va of the PM trapping layer was as high as 70% or more (for example, about 70 to 75%). Further, the porosity Vb of the large pores (pores having an equivalent circle diameter larger than 5 ⁇ m) occupied 45% or more (for example, 60% or more) of the entire PM trapping layer. In Examples 1 and 2, the ratio of Vb to Va (Vb / Va) occupied 60% or more (for example, 85% or more). In contrast, in Reference Example 3, the porosity Va of the PM trapping layer was only about 25%.
  • the PM trapping layer has a binary pore structure, and the pores dispersed in the PM trapping layer are connected to each other.
  • the skeleton part was divided in an arbitrary cross section, and the number of divisions was as large as about 50 to 80 / 0.01 mm 2 .
  • the average thickness of the skeleton portion was also suppressed to 4 ⁇ m or less (for example, 2 ⁇ m or less).
  • the number of divisions was as small as about 2, and the average thickness of the skeleton parts exceeded 30 ⁇ m. It was.
  • the surface area ratio of the skeleton portion was in the range of 25 to 55%. Also, the pore diameter of the skeleton portion was in the range of about 0.02 to 4 ⁇ m.
  • Example 1 and Example 2 have a relatively large pore volume V1 at the first pore peak compared to Reference Example 3, and are relative to the pore volume V2 at the second pore peak.
  • the ratio (V1 / V2) of the pore volume V1 of the first pore peak was also as high as 4 or more (for example, 5 or more).
  • V1 / V2 was about 2.
  • an exhaust gas purification catalyst that can suppress an increase in pressure loss and can appropriately collect PM.

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Environmental & Geological Engineering (AREA)
  • Biomedical Technology (AREA)
  • Health & Medical Sciences (AREA)
  • Analytical Chemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Catalysts (AREA)
  • Processes For Solid Components From Exhaust (AREA)

Abstract

L'invention concerne un catalyseur de purification de gaz d'échappement qui est disposé dans un passage d'échappement d'un moteur à combustion interne et collecte un matériau particulaire (MP) dans un gaz d'échappement qui est évacué du moteur à combustion interne. Ce catalyseur de purification de gaz d'échappement comprend : un substrat qui a une paroi de séparation (16) poreuse ; une couche de catalyseur (30) qui est formée à l'intérieur de la paroi de séparation (16) du substrat ; et une couche de collecte de MP (20) poreuse qui est disposée sur la paroi de séparation (16) du substrat. De plus, la couche de catalyseur (30) de ce catalyseur de purification de gaz d'échappement comprend un support et un catalyseur métallique. Par ailleurs, la couche de collecte de MP (20) contient un oxyde métallique ; et dans une image d'observation au microscope électronique d'une section transversale de la couche de collecte de MP (20), de grands pores qui ont un diamètre de cercle équivalent supérieur à 5 µm occupent 45 % ou plus si la couche de collecte de MP (20) correspond à 100 %.
PCT/JP2018/010816 2017-03-31 2018-03-19 Catalyseur de purification de gaz d'échappement WO2018180705A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2017072785 2017-03-31
JP2017-072785 2017-03-31

Publications (1)

Publication Number Publication Date
WO2018180705A1 true WO2018180705A1 (fr) 2018-10-04

Family

ID=63675705

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/JP2018/010816 WO2018180705A1 (fr) 2017-03-31 2018-03-19 Catalyseur de purification de gaz d'échappement

Country Status (1)

Country Link
WO (1) WO2018180705A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113039015A (zh) * 2018-11-15 2021-06-25 株式会社科特拉 微粒过滤器
JPWO2022130978A1 (fr) * 2020-12-16 2022-06-23

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2011098337A (ja) * 2009-10-09 2011-05-19 Ibiden Co Ltd ハニカムフィルタ
WO2011125772A1 (fr) * 2010-03-31 2011-10-13 日本碍子株式会社 Filtre en nid d'abeilles
JP2012075989A (ja) * 2010-09-30 2012-04-19 Ngk Insulators Ltd ハニカム構造体の製造方法
JP2014198654A (ja) * 2013-03-29 2014-10-23 日本碍子株式会社 ハニカム構造体
JP2016175045A (ja) * 2015-03-20 2016-10-06 日本碍子株式会社 目封止ハニカム構造体

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2011098337A (ja) * 2009-10-09 2011-05-19 Ibiden Co Ltd ハニカムフィルタ
WO2011125772A1 (fr) * 2010-03-31 2011-10-13 日本碍子株式会社 Filtre en nid d'abeilles
JP2012075989A (ja) * 2010-09-30 2012-04-19 Ngk Insulators Ltd ハニカム構造体の製造方法
JP2014198654A (ja) * 2013-03-29 2014-10-23 日本碍子株式会社 ハニカム構造体
JP2016175045A (ja) * 2015-03-20 2016-10-06 日本碍子株式会社 目封止ハニカム構造体

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113039015A (zh) * 2018-11-15 2021-06-25 株式会社科特拉 微粒过滤器
JPWO2022130978A1 (fr) * 2020-12-16 2022-06-23
WO2022130978A1 (fr) * 2020-12-16 2022-06-23 ユミコア日本触媒株式会社 Filtre à particules fines, procédé d'élimination de matériau particulaire des gaz d'échappement d'un moteur à combustion interne, et procédé de production d'un filtre à particules fines

Similar Documents

Publication Publication Date Title
JP6934311B2 (ja) 排ガス浄化フィルタ
JP4971166B2 (ja) ハニカム触媒体、ハニカム触媒体製造用のプレコート担体及びハニカム触媒体の製造方法
JP7023770B2 (ja) 排ガス浄化用触媒
CN107073463B (zh) 废气净化用催化剂
JP4819814B2 (ja) ハニカム構造体、及びハニカム触媒体
CN109973176B (zh) 排气净化过滤器
CN111980785B (zh) 废气净化装置
JP2011104524A (ja) 触媒担持フィルタ、及び排ガス浄化システム
EP3673996A1 (fr) Catalyseur pour la purification des gaz d'échappement
JP7381372B2 (ja) 排ガス浄化装置
WO2020100582A1 (fr) Filtre à particules
WO2020031975A1 (fr) Filtre à particules d'essence revêtu de catalyseur et son procédé de production
CN115263496A (zh) 排气净化装置
WO2018180705A1 (fr) Catalyseur de purification de gaz d'échappement
WO2020202253A1 (fr) Filtre de purification d'échappement
EP4571062A1 (fr) Filtre à particules
JP7332530B2 (ja) 排ガス浄化装置
JP7271610B2 (ja) パティキュレートフィルタ
JP7475138B2 (ja) 排ガス浄化用触媒
JP2020193568A (ja) 排ガス浄化装置
JP6542690B2 (ja) フィルタ触媒の製造方法
US20250177921A1 (en) Method for Producing Exhaust Gas Purification Catalyst
JP2025101761A (ja) パティキュレートフィルタおよび内部コート用スラリー
WO2022269947A1 (fr) Filtre à particules
CN112512687A (zh) 废气净化催化剂及其制造方法

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 18776238

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 18776238

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: JP