WO2023047933A1 - 排ガス浄化用触媒 - Google Patents

排ガス浄化用触媒 Download PDF

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Publication number
WO2023047933A1
WO2023047933A1 PCT/JP2022/033325 JP2022033325W WO2023047933A1 WO 2023047933 A1 WO2023047933 A1 WO 2023047933A1 JP 2022033325 W JP2022033325 W JP 2022033325W WO 2023047933 A1 WO2023047933 A1 WO 2023047933A1
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Prior art keywords
exhaust gas
catalyst
region
outflow
inflow
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Ceased
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PCT/JP2022/033325
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English (en)
French (fr)
Japanese (ja)
Inventor
真吾 秋田
広樹 栗原
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Mitsui Kinzoku Co Ltd
Original Assignee
Mitsui Mining and Smelting Co Ltd
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Application filed by Mitsui Mining and Smelting Co Ltd filed Critical Mitsui Mining and Smelting Co Ltd
Priority to CN202280063948.4A priority Critical patent/CN117999124A/zh
Priority to JP2023549454A priority patent/JP7802813B2/ja
Priority to EP22872689.9A priority patent/EP4406649A4/en
Priority to US18/691,275 priority patent/US20240382942A1/en
Publication of WO2023047933A1 publication Critical patent/WO2023047933A1/ja
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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    • 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
    • B01J35/19—Catalysts containing parts with different compositions
    • 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
    • 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
    • B01D53/944—Simultaneously removing carbon monoxide, hydrocarbons or carbon making use of oxidation catalysts
    • 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
    • B01D53/9459—Removing one or more of nitrogen oxides, carbon monoxide, or hydrocarbons by multiple successive catalytic functions; systems with more than one different function, e.g. zone coated catalysts
    • B01D53/9463—Removing one or more of nitrogen oxides, carbon monoxide, or hydrocarbons by multiple successive catalytic functions; systems with more than one different function, e.g. zone coated catalysts with catalysts positioned on one brick
    • B01D53/9472—Removing one or more of nitrogen oxides, carbon monoxide, or hydrocarbons by multiple successive catalytic functions; systems with more than one different function, e.g. zone coated catalysts with catalysts positioned on one brick in different zones
    • 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
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    • B—PERFORMING OPERATIONS; TRANSPORTING
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    • B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
    • B01J23/40—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals of the platinum group metals
    • B01J23/44—Palladium
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    • 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
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    • B01J37/0009—Use of binding agents; Moulding; Pressing; Powdering; Granulating; Addition of materials ameliorating the mechanical properties of the product catalyst
    • B01J37/0018—Addition of a binding agent or of material, later completely removed among others as result of heat treatment, leaching or washing,(e.g. forming of pores; protective layer, desintegrating by heat)
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    • 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
    • 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
    • F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
    • F01N3/101—Three-way catalysts
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
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    • 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
    • F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
    • F01N3/24—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by constructional aspects of converting apparatus
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    • 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
    • F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
    • F01N3/24—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by constructional aspects of converting apparatus
    • F01N3/28—Construction of catalytic reactors
    • F01N3/2803—Construction of catalytic reactors characterised by structure, by material or by manufacturing of catalyst support
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    • 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
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    • F01N3/24—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by constructional aspects of converting apparatus
    • F01N3/28—Construction of catalytic reactors
    • F01N3/2803—Construction of catalytic reactors characterised by structure, by material or by manufacturing of catalyst support
    • F01N3/2825—Ceramics
    • F01N3/2828—Ceramic multi-channel monoliths, e.g. honeycombs
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    • F01N2370/00—Selection of materials for exhaust purification
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    • F01N2510/00—Surface coverings
    • F01N2510/06—Surface coverings for exhaust purification, e.g. catalytic reaction
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    • F01N2510/0682—Surface coverings for exhaust purification, e.g. catalytic reaction characterised by the distribution of the catalytic coatings having a discontinuous, uneven or partially overlapping coating of catalytic material, e.g. higher amount of material upstream than downstream or vice versa

Definitions

  • the present invention relates to an exhaust gas purifying catalyst.
  • Exhaust gases emitted from internal combustion engines such as automobiles and motorcycles contain harmful components such as hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (NOx).
  • a three-way catalyst is used for the purpose of purifying and rendering these harmful components harmless.
  • catalysts containing precious metal elements such as platinum element (Pt), palladium element (Pd), and rhodium element (Rh) are used, and Pt and Pd are mainly involved in oxidative purification of HC and CO. , Rh are mainly involved in reducing NOx.
  • Exhaust gas contains particulate matter (PM) along with harmful components such as HC, CO, and NOx, and is known to cause air pollution.
  • PM particulate matter
  • GDI Gasoline Direct Injection engine
  • GPF Gasoline Particulate Filter
  • the wall-flow type substrate has an inflow-side cell whose exhaust gas inflow side end is open and an exhaust gas outflow side end is closed, and an exhaust gas inflow side end that is closed and an exhaust gas outflow side end is closed. It has open outflow cells and porous partitions separating the inflow cells and the outflow cells.
  • the wall flow type substrate when the exhaust gas that has flowed in from the exhaust gas inflow side end (opening) of the inflow cell passes through the porous partition wall and flows out from the exhaust gas outflow side end (opening) of the outflow cell , the PM in the exhaust gas is trapped in the pores inside the partition wall.
  • Patent Literature 1 describes an exhaust gas purifying catalyst that includes a wall-flow type substrate and a catalyst portion provided inside partition walls of the wall-flow type substrate.
  • Patent Document 2 describes an exhaust gas purifying catalyst that includes a wall-flow type substrate and a catalyst portion provided on the outer surface of partition walls of the wall-flow type substrate.
  • JP 2016-150305 A Japanese Patent Publication No. 2018-537265
  • an object of the present invention is to provide an exhaust gas purifying catalyst comprising a wall-flow type base material and a catalyst portion, which is capable of improving PM trapping performance and suppressing an increase in pressure loss.
  • An exhaust gas purifying catalyst comprising a substrate extending in an exhaust gas flow direction and at least one of a first catalyst portion and a second catalyst portion provided on the substrate,
  • the base material is an inflow-side cell extending in the exhaust gas flow direction, the inflow-side cell having an open end on the exhaust gas inflow side and a closed end on the exhaust gas outflow side; an outflow-side cell extending in the exhaust gas flow direction, the outflow-side cell having an exhaust gas inflow-side end closed and an exhaust gas outflow-side end open; a porous partition partitioning the inflow-side cells and the outflow-side cells; with
  • the first catalyst portion is formed in a predetermined region of the inflow-side cell-side surface of the partition wall that extends along the exhaust gas flow direction from an exhaust gas inflow-side end portion of the partition wall,
  • the second catalyst portion is formed in a predetermined region of the outflow-side cell-side surface of the partition wall, which extend
  • the first catalyst part has the following formulas (11) and (12): 0.20 ⁇ R 11 ⁇ 0.80 (11) 0.30 ⁇ R 12 ⁇ 0.85 (12) [In the formula, R 11 represents the ratio of the area of the part covered with the first catalyst portion to the area of the predetermined region of the inflow-side cell-side surface, and R 12 represents the first unevenness.
  • the second catalyst part has the following formulas (21) and (22): 0.20 ⁇ R 21 ⁇ 0.80 (21) 0.30 ⁇ R 22 ⁇ 0.85 (22) [In the formula, R21 represents the ratio of the area of the part covered with the second catalyst portion to the area of the predetermined region of the outflow-side cell-side surface, and R22 represents the second unevenness. It represents the ratio of the surface roughness of the surface to the surface roughness of the predetermined region of the outflow side cell side surface. ] and the exhaust gas purifying catalyst.
  • the first catalyst part has the following formula (13): 0.060 ⁇ R 13 ⁇ 0.55 (13) [In the formula, R 13 represents a value obtained by multiplying R 11 by R 12 , and R 11 and R 12 are as defined above. ]
  • the second catalyst part has the following formula (23): 0.060 ⁇ R 23 ⁇ 0.55 (23) [In the formula, R23 represents a value obtained by multiplying R21 by R22 , and R21 and R22 are as defined above. ]
  • the ratio of the total length of the predetermined region of the inflow-side cell-side surface and the length of the predetermined region of the outflow-side cell-side surface to the length of the substrate is 0.30 or more.
  • the first catalyst part and the second catalyst part independently contain at least one catalytically active component selected from platinum element (Pt), palladium element (Pd) and rhodium element (Rh).
  • the exhaust gas purifying catalyst according to any one of [1] to [4].
  • an exhaust gas purifying catalyst capable of improving PM trapping performance and suppressing an increase in pressure loss is provided.
  • FIG. 1 is a partial cross-sectional view showing a state in which an exhaust gas purifying catalyst according to one embodiment of the present invention is arranged in an exhaust path of an internal combustion engine.
  • FIG. 2 is an end view taken along the line AA of FIG. 1.
  • FIG. 3 is an end view taken along the line BB of FIG. 1.
  • FIG. 4 is an enlarged view of the area indicated by symbol R1 in FIG.
  • FIG. 5 is an enlarged view of the area indicated by symbol R2 in FIG.
  • FIG. 6 is a CC line end view of FIG.
  • FIG. 7A is an enlarged view of the area indicated by symbol R31 in FIG.
  • FIG. 7B is an enlarged view of the area indicated by symbol R32 in FIG.
  • FIG. 8 is a diagram for explaining the first and second regions of the inflow-side cell-side surface of the partition wall and the first and second regions of the outflow-side cell-side surface of the partition wall (from FIG. 6 to the first catalyst portion and the second catalyst part are omitted).
  • FIG. 9 is a perspective view of a cut piece used to calculate R11 or R12 .
  • 10 is a plan view of the cut piece shown in FIG. 9 (a plan view of the cut piece shown in FIG. 9 in the Z direction).
  • FIG. 11 is a conceptual diagram of an SEM image used for calculating R11 .
  • FIG. 12 is a conceptual diagram of a profilometer scan image used to calculate R12 .
  • FIG. 13 is a perspective view of a cut piece used for calculating R21 or R22 .
  • FIG. 14 is a plan view of the cut piece shown in FIG. 13 (a plan view of the cut piece shown in FIG. 13 in the Z direction).
  • FIG. 15 is a conceptual diagram of an SEM image used for calculating R21 .
  • FIG. 16 is a conceptual diagram of a profilometer scan image used for calculating R22 .
  • an exhaust gas purifying catalyst 1 is arranged in an exhaust path in an exhaust pipe P of an internal combustion engine.
  • the internal combustion engine is, for example, a gasoline engine (such as a GDI engine), a diesel engine, or the like.
  • the exhaust gas purifying catalyst 1 is arranged in the exhaust path of the internal combustion engine so that the axial direction of the substrate 10 substantially coincides with the exhaust gas flow direction E.
  • length means the axial dimension of substrate 10, unless otherwise specified.
  • the exhaust gas purifying catalyst 1 includes a substrate 10 extending in the exhaust gas flow direction E, a first catalyst portion 20 provided on the substrate 10, and a catalyst portion 20 provided on the substrate 10. and a second catalyst unit 30 .
  • the exhaust gas purifying catalyst 1 may include at least one of the first catalyst portion 20 and the second catalyst portion 30 . Therefore, embodiments in which one of the first catalyst unit 20 and the second catalyst unit 30 is omitted are also included in the present invention. However, from the viewpoint of improving exhaust gas purification performance and PM trapping performance, it is preferable that the exhaust gas purification catalyst 1 includes both the first catalyst portion 20 and the second catalyst portion 30 .
  • the material constituting the base material 10 can be selected as appropriate.
  • the material forming the base material 10 include ceramic materials and metal materials, with ceramic materials being preferred.
  • Ceramic materials include, for example, carbide ceramics such as silicon carbide, titanium carbide, tantalum carbide, and tungsten carbide; nitride ceramics such as aluminum nitride, silicon nitride, boron nitride, and titanium nitride; alumina, zirconia, cordierite, mullite, and zircon. , oxide ceramics such as aluminum titanate and magnesium titanate, and silicon-containing silicon carbide.
  • the ceramic material is preferably a silicon-containing ceramic material such as silicon carbide, silicon nitride, cordierite, mullite, or the like.
  • a ceramic material can be used individually by 1 type or in combination of 2 or more types.
  • the substrate 10 includes a tubular portion 11, porous partition walls 12 provided in the tubular portion 11, and cells 13 (cells 13a and 13b) partitioned by the partition walls 12. ).
  • the axial direction of the base material 10 coincides with the axial direction of the tubular portion 11 .
  • the tubular portion 11 has a cylindrical shape, but may have other shapes such as an elliptical tubular shape and a polygonal tubular shape.
  • partition walls 12 exist between adjacent cells 13 (cells 13a and 13b), and the adjacent cells 13 (cells 13a and 13b) are partitioned by the partition walls 12.
  • the cells 13 extend in the exhaust gas flow direction E and have an exhaust gas inflow side end and an exhaust gas outflow side end.
  • the base material 10 includes a first sealing portion 14 that seals the ends of some of the cells 13 on the exhaust gas outflow side, and seals the ends of the remaining cells 13 on the exhaust gas inflow side.
  • a second sealing portion 15 is provided, whereby some of the cells 13 are open at the ends on the exhaust gas inflow side, and the ends on the exhaust gas outflow side are closed with the first sealing portion 14.
  • the remaining cells 13 are the outflow-side cells 13b whose ends on the exhaust gas inflow side are closed with the second sealing portion 15 and whose ends on the exhaust gas outflow side are open. ing.
  • a plurality (four in this embodiment) of outflow-side cells 13b are arranged around one inflow-side cell 13a.
  • the outflow-side cell 13b arranged around the inflow-side cell 13a are separated by a porous partition wall 12 .
  • Exhaust gas discharged from the internal combustion engine flows through the exhaust path in the exhaust pipe P from one end to the other end of the exhaust pipe P, and is purified by the exhaust gas purification catalyst 1 arranged in the exhaust pipe P.
  • the exhaust gas that has flowed in from the exhaust gas inflow end (opening) of the inflow cell 13a passes through the porous partition wall 12 and flows out from the exhaust gas outflow end (opening) of the outflow cell 13b.
  • a mode is called a wall-flow type.
  • the exhaust gas purifying catalyst 1 when the exhaust gas that has flowed in from the exhaust gas inflow side end (opening) of the inflow-side cell 13a passes through the porous partition wall 12, particulate matter (PM) in the exhaust gas is , the pores of the partition wall 12 , the pores of the first catalyst portion 20 and the pores of the second catalyst portion 30 . Therefore, the exhaust gas purifying catalyst 1 is useful as a particulate filter for gasoline engines or a diesel particulate filter for diesel engines.
  • the planar view shape of the exhaust gas inflow side end (opening) of the inflow-side cell 13a is quadrangular, but may be other shapes such as hexagon and octagon. The same applies to the exhaust gas inflow side end (opening) of the outflow side cell 13b.
  • the cell density per square inch of the base material 10 can be appropriately adjusted, but from the viewpoint of more effectively improving the PM trapping performance and suppressing the increase in pressure loss, it is preferably 200 cells or more and 350 cells or less. is.
  • the cell density per square inch of the substrate 10 is the total number of cells 13a and 13b per square inch in a cross section obtained by cutting the substrate 10 along a plane perpendicular to the axial direction of the substrate 10. is.
  • the partition wall 12 has a porous structure through which the exhaust gas can pass.
  • the thickness of the partition wall 12 can be adjusted as appropriate, it is preferably 150 ⁇ m or more and 350 ⁇ m or less, more preferably 180 ⁇ m or more and 320 ⁇ m or less, from the viewpoint of more effectively improving the PM trapping performance and suppressing the increase in pressure loss. be.
  • the average pore diameter (average pore diameter) of the partition walls 12 can be adjusted as appropriate. It is preferably 13 ⁇ m or more and 22 ⁇ m or less.
  • the porosity (porosity) of the partition walls 12 can be adjusted as appropriate, but from the viewpoint of more effectively suppressing the increase in pressure loss, it is, for example, 40% or more and 80% or less, preferably 45% or more and 75% or less. , more preferably 50% or more and 75% or less, and still more preferably 60% or more and 70% or less.
  • the average pore diameter and porosity of the partition walls 12 can be measured by mercury porosimetry using a mercury porosimeter.
  • a test piece cut out from the substrate 10 (excluding the first sealing portion 14 and the second sealing portion 15) is placed in the measurement cell of the mercury porosimeter, the pressure in the measurement cell is reduced, Mercury is introduced into the measurement cell and pressurized, and the pore diameter and pore volume are measured from the pressure during pressurization and the volume of mercury introduced into the pores of the partition walls 12 in the test piece. Measurements are made, for example, at pressures ranging from 0.5 to 20000 psia.
  • 0.5 psia corresponds to 0.35 ⁇ 10 ⁇ 3 kg/mm 2 and 20000 psia corresponds to 14 kg/mm 2 .
  • the pore size range corresponding to this pressure range is 0.01 to 420 ⁇ m.
  • a contact angle of 140° and a surface tension of 480 dyn/cm are used as constants for calculating the pore diameter from the pressure.
  • the average pore diameter of the partition walls 12 is the pore diameter at which the cumulative pore volume is 50% in the pore diameter distribution of the partition walls 12 (the pore diameter at 50% of the integrated value of the pore volume).
  • the porosity of the partition walls 12 can be calculated based on the following formula.
  • partition wall material is cordierite
  • 2.52 can be used as the true specific gravity of cordierite.
  • Porosity (%) of partition walls 12 total pore volume/(total pore volume + 1/true specific gravity of partition wall material) x 100
  • the length L10 of the base material 10 can be adjusted as appropriate, but is preferably 50 mm from the viewpoint of improving exhaust gas purification performance, improving PM trapping performance, and easiness of mounting in the limited space of a vehicle. 160 mm or less, more preferably 80 mm or more and 130 mm or less.
  • the volume of the base material 10 can be adjusted as appropriate, but is preferably 0.5 L from the viewpoint of improving exhaust gas purification performance, improving PM trapping performance, and easiness of mounting in the limited space of a vehicle. 2.5 L or less, more preferably 0.5 L or more and 2.0 L or less, more preferably 0.7 L or more and 1.8 L or less.
  • the volume of substrate 10 means the apparent volume of substrate 10 .
  • the first catalyst portion 20 is formed in the first region S1a of the surface of the partition wall 12 on the inflow side cell 13a side.
  • the inflow-side cell 13a side surface of the partition wall 12 is the outer surface of the inflow-side cell 13a side that defines the outer shape of the partition wall 12 .
  • the surface of the partition wall 12 on the inflow side cell 13a side is composed of a first region S1a and a second region S1b.
  • the first region S1a is a region extending along the exhaust gas flow direction E from the exhaust gas inflow side end of the partition wall 12 on the surface of the partition wall 12 on the inflow side cell 13a side.
  • the region in which the first catalyst portion 20 is formed in the first region S1a may be one continuous region or a plurality of discontinuous regions. That is, the first catalyst portion 20 may be composed of one continuous structure, or may be composed of a plurality of discontinuous structures. For example, the first catalyst portion 20 may be composed of a plurality of discontinuous structures scattered over the first region S1a.
  • "Structure" means a material that has a certain shape.
  • the shape of the structure examples include layered, spherical, granular, acicular, scale-like (flake-like), amorphous, and combinations of two or more of these. 4 and 6, the first catalyst part 20 is shown as one layered structure for convenience from the viewpoint of simplicity of the drawings.
  • the fact that the first catalyst portion 20 is formed in the first region S1a can be confirmed by using a scanning electron microscope--energy dispersive X-ray spectrometer (SEM-EDX) or the like. This can be confirmed by confirming that (an element contained in the first catalyst portion 20 but not contained in the base material 10) exists in the first region S1a.
  • SEM-EDX scanning electron microscope--energy dispersive X-ray spectrometer
  • the second region S1b is a region other than the first region S1a on the surface of the partition wall 12 on the side of the inflow-side cell 13a, and the first catalyst portion 20 is not formed in the second region S1b.
  • the first catalytic portion 20 protrudes from the first region S1a toward the inflow-side cell 13a, covering part of the first region S1a.
  • the first catalyst portion 20 may have a first portion protruding from the first region S1a toward the inflow-side cell 13a and a second portion existing inside the partition wall 12 . Since the partition wall 12 is porous, the second portion may be formed together with the first portion when forming the first catalyst portion 20 . The first portion and the second portion may be continuous.
  • the second catalyst portion 30 is formed in the first region S2a of the surface of the partition wall 12 on the outflow side cell 13b side.
  • the outflow-side cell 13b side surface of the partition wall 12 is the outer surface of the outflow-side cell 13b side that defines the outer shape of the partition wall 12 .
  • the surface of the partition wall 12 on the outflow side cell 13b side is composed of a first region S2a and a second region S2b.
  • the first region S2a is a region extending in the direction opposite to the exhaust gas flow direction E from the exhaust gas outflow side end of the partition wall 12 on the outflow side cell 13b side surface of the partition wall 12 .
  • the region in which the second catalyst portion 30 is formed in the first region S2a may be one continuous region or a plurality of discontinuous regions. That is, the second catalyst portion 30 may be composed of one continuous structure, or may be composed of a plurality of discontinuous structures. For example, the second catalyst portion 30 may be composed of a plurality of discontinuous structures scattered over the first region S2a.
  • the significance of the structure and specific examples of the shape of the structure are the same as above. 5 and 6, the second catalyst portion 30 is shown as one layered structure for convenience from the viewpoint of simplicity of the drawings.
  • the fact that the second catalyst portion 30 is formed in the first region S2a can be confirmed by using a scanning electron microscope-energy dispersive X-ray spectrometer (SEM-EDX) or the like. This can be confirmed by confirming that (an element contained in the second catalyst portion 30 but not contained in the base material 10) exists in the first region S2a.
  • SEM-EDX scanning electron microscope-energy dispersive X-ray spectrometer
  • the second region S2b is a region other than the first region S2a on the surface of the partition wall 12 on the outflow side cell 13b side, and the second catalyst portion 30 is not formed in the second region S2b.
  • the second catalyst portion 30 protrudes from the first region S2a toward the outflow-side cell 13b, covering part of the first region S2a.
  • the second catalyst portion 30 may have a first portion protruding from the first region S2a toward the outflow-side cell 13b and a second portion existing inside the partition wall 12 . Since the partition wall 12 is porous, the second portion may be formed together with the first portion when forming the second catalyst portion 30 . The first portion and the second portion may be continuous.
  • the length LS1a of the first region S1a extends in the axial direction of the substrate 10 through the point located closest to the exhaust gas outflow side among all the points on the surface of the first catalyst portion 20 formed in the first region S1a. It means the distance between the vertical plane and the end surface of the substrate 10 on the exhaust gas inflow side.
  • the length LS1a of the first region S1a can be adjusted as appropriate.
  • the first region S1a may extend from the exhaust gas inflow side end of the partition wall 12 to the exhaust gas outflow side end of the partition wall 12 along the exhaust gas flow direction E, but does not reach the exhaust gas outflow side end of the partition wall 12. It is preferable to extend along the exhaust gas flow direction E from the exhaust gas inflow side end of the partition wall 12 so as not to be absent.
  • the length LS2a of the first region S2a passes through the point closest to the exhaust gas inflow side among all the points on the surface of the second catalyst portion 30 formed on the first region S2a, and extends in the axial direction of the substrate 10. and the end face of the substrate 10 on the exhaust gas outflow side.
  • the length LS2a of the first region S2a can be adjusted as appropriate.
  • the first region S2a may extend from the exhaust gas outflow end of the partition wall 12 to the exhaust gas inflow end of the partition wall 12 along the direction opposite to the exhaust gas flow direction E. It is preferable to extend from the end of the partition wall 12 on the exhaust gas outflow side along the direction opposite to the exhaust gas flow direction E so as not to reach the side end.
  • the total length L10 of the length LS1a of the first region S1a and the length LS2a of the first region S2a is the length L10 of the base material 10. to ((LS1a+LS2a)/L10) is preferably 0.30 or more and 1.8 or less, more preferably 0.50 or more and 1.5 or less, and still more preferably 1.0 or more and 1.3 or less.
  • the sum of the length LS1a of the first region S1a and the length LS2a of the first region S2a means the length LS2a of the first region S2a in the embodiment in which the first catalyst portion 20 is omitted, and the length LS2a of the first region S2a. In an embodiment in which the part 30 is omitted, it means the length LS1a of the first region S1a.
  • the ratio of the length LS1a of the first region S1a to the length L10 of the substrate 10 is preferably It is 0.15 or more and 0.90 or less, more preferably 0.20 or more and 0.80 or less, and still more preferably 0.30 or more and 0.80 or less.
  • the ratio of the length LS2a of the first region S2a to the length L10 of the substrate 10 is preferably It is 0.15 or more and 0.90 or less, more preferably 0.20 or more and 0.80 or less, and still more preferably 0.30 or more and 0.80 or less.
  • An example of a method for measuring the length LS1a of the first region S1a is as follows.
  • a sample extending in the axial direction of the substrate 10 and having the same length as the length L10 of the substrate 10 is cut out from the exhaust gas purification catalyst 1 .
  • the sample is, for example, cylindrical with a diameter of 25.4 mm. It should be noted that the value of the diameter of the sample can be changed as needed.
  • the sample is cut at intervals of 5 mm along a plane perpendicular to the axial direction of the base material 10, and the first cut piece, the second cut piece, . obtain.
  • the cut piece length is 5 mm.
  • the composition of the cut piece is analyzed using an inductively coupled plasma-optical emission spectrometer (ICP-OES), an X-ray fluorescence spectrometer (XRF), SEM-EDX, etc., and based on the composition of the cut piece, the cut piece is It is confirmed whether or not a part of the first catalyst portion 20 is included.
  • ICP-OES inductively coupled plasma-optical emission spectrometer
  • XRF X-ray fluorescence spectrometer
  • SEM-EDX etc.
  • the length LS1a of the first region S1a included in the sample is calculated based on the following formula.
  • the length LS1a of the first region S1a included in the sample 5 mm ⁇ (the number of cut pieces including part of the first catalyst portion 20)
  • the length LS1a of the first region S1a is (5 ⁇ k) mm.
  • An example of a more detailed measuring method of the length LS1a of the first region S1a is as follows.
  • the k-th cut piece (that is, the cut piece obtained from the most exhaust gas outflow side of the sample among the cut pieces including a part of the first catalyst part 20) is cut in the axial direction of the base material 10, and SEM, EPMA
  • the length of a portion of the first region S1a included in the k-th cut piece is measured by observing a portion of the first catalyst portion 20 existing on the cut surface using a measuring device such as a .
  • the length LS1a of the first region S1a included in each sample is measured, and the average value is taken as the length LS1a of the first region S1a. do.
  • the above description regarding the method for measuring the length LS1a of the first region S1a also applies to the method for measuring the length LS2a of the first region S2a.
  • the length LS1a of the first region S1a is read as “the length LS2a of the first region S2a”
  • the first catalyst portion 20 is read as the "second catalyst portion 30”.
  • the sample is cut at intervals of 5 mm by a plane perpendicular to the axial direction of the base material 10, and the first cut piece , the second segment, . . . , the n-th segment.
  • the total mass of the first catalyst part 20 and the second catalyst part 30 per unit volume of the base material 10 is preferably 5 g/L or more and 25 g/L or less, more preferably 10 g/L or more and 20 g/L or less.
  • the total mass of the first catalyst part 20 and the second catalyst part 30 means the mass of the second catalyst part 30 in the embodiment in which the first catalyst part 20 is omitted, and the second catalyst part 30 is omitted. In the embodiment, it means the mass of the first catalyst part 20 .
  • the total mass of the first catalyst portion 20 and the second catalyst portion 30 per unit volume of the substrate 10 is obtained by the formula: (total mass of the first catalyst portion 20 and the second catalyst portion 30)/(volume of the substrate 10) calculated from
  • the mass of the first catalyst part 20 per unit volume of the base material 10 (the mass after drying and firing) is preferably 2 g/ L or more and 20 g/L or less, more preferably 3 g/L or more and 15 g/L or less.
  • the mass of the first catalyst portion 20 per unit volume of the substrate 10 is calculated from the formula: (mass of the first catalyst portion 20)/(volume of the substrate 10).
  • the mass of the second catalyst part 30 per unit volume of the base material 10 is preferably 2 g. /L or more and 20 g/L or less, more preferably 3 g/L or more and 15 g/L or less.
  • the mass of the second catalyst portion 30 per unit volume of the substrate 10 is calculated from the formula: (mass of the second catalyst portion 30)/(volume of the substrate 10).
  • part of the first region S1a is covered with the first catalyst portion 20, while the remaining portion of the first region S1a is not covered with the first catalyst portion 20 and is exposed.
  • the surface of the first catalytic portion 20 and the rest of the first region S1a together form the first uneven surface 41.
  • FIG. 4 and 6 are described as if the entire first region S1a is covered with the first catalyst portion 20 for convenience from the viewpoint of simplicity of the drawings, but in reality, FIG. 7A 2, part of the first region S1a is covered with the first catalyst portion 20, while the remaining portion of the first region S1a is not covered with the first catalyst portion 20 and is exposed.
  • part of the first region S2a is covered with the second catalyst portion 30, while the rest of the first region S2a is not covered with the second catalyst portion 30 and is exposed.
  • the surface of the second catalytic portion 30 and the rest of the first region S2a together form the second uneven surface .
  • 5 and 6 show that the entire first region S2a is covered with the second catalyst portion 30 for the sake of convenience.
  • a portion of S2a is covered with the second catalyst portion 30, while the rest of the first region S2a is not covered with the second catalyst portion 30 and is exposed.
  • the first catalyst part 20 has the following formulas (11) and (12): 0.20 ⁇ R 11 ⁇ 0.80 (11) 0.30 ⁇ R 12 ⁇ 0.85 (12) meet. As a result, it is possible to improve the PM trapping performance and suppress the increase in pressure loss.
  • R11 represents the ratio of the area of the part of the first region S1a covered with the first catalyst portion 20 to the area of the first region S1a.
  • R12 represents the ratio of the surface roughness of the first uneven surface 41 to the surface roughness of the first region S1a.
  • the surface roughness of the first region S1a means the surface roughness of the first region S1a before the first catalyst portion 20 is formed.
  • R 11 satisfies the above formula (11) represents a state in which the pores in the vicinity of the first region S1a are appropriately filled with the first catalyst portion 20, and this makes it possible to suppress an increase in pressure loss. Become.
  • R 12 satisfies the above formula (12) represents a state in which the large pores in the vicinity of the first region S1a are appropriately filled with the first catalyst portion 20, thereby improving the PM trapping performance. become feasible.
  • the second catalyst part 30 is represented by the following formulas (21) and (22): 0.20 ⁇ R 21 ⁇ 0.80 (21) 0.30 ⁇ R 22 ⁇ 0.85 (22) meet.
  • R21 represents the ratio of the area of the part of the first region S2a covered with the second catalyst portion 30 to the area of the first region S2a.
  • R22 represents the ratio of the surface roughness of the second uneven surface 42 to the surface roughness of the first region S2a.
  • the surface roughness of the first region S2a means the surface roughness of the first region S2a before the second catalyst portion 30 is formed.
  • R 21 satisfies the above formula (21) represents a state in which the pores in the vicinity of the first region S2a are appropriately filled with the second catalyst portion 30, and this makes it possible to suppress the increase in pressure loss. Become.
  • R 22 satisfies the above formula (22) represents a state in which the large pores in the vicinity of the first region S2a are appropriately filled with the second catalyst portion 30, thereby improving the PM trapping performance. become feasible.
  • R 11 is preferably 0.20 or more and 0.80 or less, more preferably 0.20 or more and 0.70 or less, and still more preferably 0.25 or more and 0.70 or less. 0.65 or less.
  • R12 is preferably 0.30 or more and 0.85 or less, more preferably 0.40 or more and 0.80 or less, and even more preferably 0.50. 0.80 or less.
  • R 21 is preferably 0.20 or more and 0.80 or less, more preferably 0.20 or more and 0.70 or less, and still more preferably 0.25 or more and 0.25 or more. 0.65 or less.
  • R22 is preferably 0.30 or more and 0.85 or less, more preferably 0.40 or more and 0.80 or less, and even more preferably 0.50. 0.80 or less.
  • the first catalyst portion 20 has the following formula (13): 0.060 ⁇ R 13 ⁇ 0.55 (13) is preferably satisfied.
  • R13 represents a value obtained by multiplying R11 by R12 .
  • R 11 and R 12 have the same meanings as above.
  • R 13 is preferably 0.10 or more and 0.55 or less, more preferably 0.10 or more and 0.50 or less. It is preferably 0.10 or more and 0.45 or less, and more preferably 0.10 or more and 0.43 or less.
  • the second catalyst portion 30 has the following formula (23): 0.060 ⁇ R 23 ⁇ 0.55 (23) is preferably satisfied.
  • R23 represents a value obtained by multiplying R21 by R22 .
  • R 21 and R 22 have the same meanings as above.
  • R 23 is preferably 0.10 or more and 0.55 or less, more preferably 0.10 or more and 0.50 or less. It is preferably 0.10 or more and 0.45 or less, and more preferably 0.10 or more and 0.43 or less.
  • the exhaust gas purifying catalyst 1 is cut along a plane parallel to the axial direction of the base material 10 and a plane perpendicular to the axial direction of the base material 10, and a portion represented by symbol M in FIG. 6 is cut out from the exhaust gas purifying catalyst 1. , cut pieces M shown in FIGS. 9 and 10 are prepared.
  • the cut piece M includes the first uneven surface 41 but does not include the second uneven surface 42 .
  • the length of the first uneven surface 41 included in the cut piece M is equal to the length of the cut piece M.
  • the cut piece M can be obtained from the vicinity of the exhaust gas inflow side end of the exhaust gas purifying catalyst 1 .
  • the first uneven surface 41 is included by cutting two locations 5 mm and 15 mm apart in the exhaust gas flow direction E from the end of the substrate 10 on the exhaust gas inflow side, respectively, along a plane perpendicular to the axial direction of the substrate 10.
  • a cut piece M having a length of 10 mm, which does not include the second uneven surface 42, can be obtained.
  • the size of the cut piece M can be changed as needed.
  • the first uneven surface 41 is exposed, and the second region S2b (the region is not covered with the second catalyst portion 30) is exposed. ing.
  • a region indicated by symbol R4 in FIG. 10 is observed with a scanning electron microscope (SEM) from the Z-axis direction (the direction perpendicular to the paper surface of FIG. 10), and an SEM image G11 shown in FIG. 11 is captured.
  • SEM scanning electron microscope
  • the SEM image G11 is captured such that the length direction Y of the cut piece M is the lateral direction of the SEM image G11.
  • the SEM image G11 includes the first uneven surface 41, the second region S2b (the region is not covered with the second catalyst portion 30), and the partition wall 12 located therebetween (FIG. 10). reference).
  • the thickness of the partition wall 12 included in the SEM image G11 is calculated. Specifically, as shown in FIG. 11, intersection points Q1 and Q2 between a central line CL11 perpendicular to the lateral direction of the SEM image G11 and the contour lines of the partition walls 12 are specified, and a distance D12 between the intersection points Q1 and Q2 is determined. It is the thickness of the partition wall 12 .
  • a line PL1 parallel to the horizontal direction of the SEM image G11 is drawn from the intersection Q1
  • a line PL2 parallel to the horizontal direction of the SEM image G11 is drawn from the intersection Q2.
  • a rectangular measurement area MR11 is set at a position separated by a distance D1 from the line PL1 in the first uneven surface 41, and a second area S2b (this area is the second catalyst portion).
  • a rectangular measurement region MR12 is set at a position separated from the line PL2 by a distance D2.
  • the distances D1 and D2 are 0.5 times the thickness of the partition 12 (distance D12).
  • the dimension in the vertical direction (the X-axis direction in FIG. 11) of the measurement regions MR11 and MR12 is 1.5 times the thickness (distance D12) of the partition wall 12, and the dimension in the horizontal direction (the Y-axis direction in FIG. 11) of the measurement regions MR11 and MR12 direction) is five times the thickness of the partition wall 12 (distance D12).
  • a Si mapping image of the SEM image G11 is obtained.
  • the element to be mapped is an element unique to the base material 10 (an element contained in the base material 10 but not contained in the first catalyst part 20 and the second catalyst part 30), silicon Elements other than (Si) may be used.
  • the measurement areas MR11 and MR12 are binarized.
  • R11 1 ⁇ (number of dots in binarized measurement region MR11)/(number of dots in binarized measurement region MR12)
  • the number of dots in the binarized measurement region MR11 is regarded as the area of a part of the first region S1a that is not covered with the first catalyst portion 20, and the binarized measurement region MR12 is calculated. is regarded as the area of the first region S1a.
  • R 11 is calculated for each of the three cut pieces M, and the average value is defined as R 11 of the exhaust gas purifying catalyst 1 .
  • the measuring equipment and measuring conditions used for calculating R11 are as follows.
  • a cut piece M shown in FIGS. 9 and 10 is prepared in the same manner as above.
  • the first uneven surface 41 is exposed, and the second region S2b (the region is not covered with the second catalyst portion 30) is exposed. ing.
  • the height MH of the partition walls 12 positioned between these exposed surfaces is adjusted to 500 ⁇ m or more.
  • the scan image G12 is captured such that the length direction Y of the cut piece M is aligned with the Y-axis direction of the scan image G12 (vertical direction in FIG. 12).
  • the scan magnification is adjusted so that the entire area indicated by reference numeral R5 in FIG. 10 is included in the scan range.
  • focusing is performed in the second region S2b, and the scanning range in the Z-axis direction (the direction perpendicular to the paper surface of FIG. 10) is ⁇ 400 ⁇ m with respect to the focused second region S2b. and Since the height MH of the partition 12 is adjusted to 500 ⁇ m or more, the partition 12 is out of the scanning range, and as shown in FIG.
  • a line QL1 passing through the left end point P1 and parallel to the Y-axis direction of the scan image G12 and a line QL2 passing through the right end point P2 and being parallel to the Y-axis direction of the scan image G12 are drawn. is the boundary line between the first uneven surface 41 and the partition wall 12 .
  • a distance DS1 between the line QL1 and the line QL2 is defined as the width (dimension in the X-axis direction) of the first uneven surface 41 .
  • a line QL3 passing through the left end point P3 and parallel to the Y-axis direction of the scan image G12 and a line QL4 passing through the right end point P4 and being parallel to the Y-axis direction of the scan image G12 are drawn. is the boundary line between the second region S2b and the partition wall 12.
  • the distance DS2 between the line QL3 and the line QL4 be the width (dimension in the X-axis direction) of the second region S2b.
  • a rectangular measurement is placed at a predetermined distance (0.25 times the width of the first uneven surface 41 (distance DS1)) from the lines QL1 and QL2.
  • a region MR21 is set, and a rectangular measurement region MR22 is placed in the second region S2b at a predetermined distance (0.25 times the width of the second region S2b (distance DS2)) from the lines QL3 and QL4. set.
  • the dimension of the measurement region MR21 in the X-axis direction (horizontal direction in FIG. 12) is 0.5 times the width (distance DS1) of the first uneven surface 41, and the Y-axis direction (vertical direction in FIG.
  • the dimension of the measurement region MR22 in the X-axis direction is 0.5 times the width (distance DS2) of the second region S2b, and the dimension in the Y-axis direction (vertical direction in FIG. 12) of the measurement region MR22. is twice the width (distance DS2) of the second region S2b.
  • the area ratio means the integrated area ratio from the smaller surface roughness (the same applies hereinafter).
  • the difference V1 is regarded as the surface roughness of the first uneven surface 41
  • the difference V2 is regarded as the surface roughness of the first region S1a (the first region S1a before the first catalyst portion 20 is formed). regard it as
  • R12 is calculated for each of the three cut pieces M, and the average value is taken as the R12 of the exhaust gas purifying catalyst 1 .
  • the measuring equipment and measuring conditions used for calculating R12 are as follows.
  • the difference V2 is usually 20 ⁇ m or more and 120 ⁇ m or less, preferably 40 ⁇ m or more and 100 ⁇ m or less, more preferably 50 ⁇ m or more and 80 ⁇ m or less.
  • the exhaust gas purifying catalyst 1 is cut along a plane parallel to the axial direction of the substrate 10 and a plane perpendicular to the axial direction of the substrate 10, and a portion indicated by a symbol N in FIG. 6 is cut out from the exhaust gas purifying catalyst 1. , cut pieces N shown in FIGS. 13 and 14 are prepared.
  • the cut piece N includes the second uneven surface 42 but does not include the first uneven surface 41 .
  • the length of the second uneven surface 42 included in the cut piece N is equal to the length of the cut piece N.
  • the cut piece N can be obtained from the vicinity of the end of the exhaust gas purifying catalyst 1 on the exhaust gas outflow side.
  • the second A cut piece N having a length of 10 mm, which includes the uneven surface 42 but does not include the first uneven surface 41, can be obtained.
  • the size of the cut piece N can be appropriately changed as needed.
  • the second uneven surface 42 is exposed, and the second region S1b (the region is not covered with the first catalyst portion 20) is exposed. ing.
  • a region indicated by reference numeral R6 in FIG. 14 is observed with a scanning electron microscope (SEM) from the Z-axis direction (direction perpendicular to the paper surface of FIG. 14), and an SEM image G21 shown in FIG. 15 is captured.
  • SEM scanning electron microscope
  • the SEM image G21 is captured such that the length direction Y of the cut piece N is the horizontal direction of the SEM image G21.
  • the SEM image G21 includes the second uneven surface 42, the second region S1b (the region is not covered with the first catalyst portion 20), and the partition wall 12 positioned therebetween (FIG. 14). reference).
  • the thickness of the partition wall 12 included in the SEM image G21 is calculated. Specifically, as shown in FIG. 15, intersection points Q1′ and Q2′ between the center line CL21 perpendicular to the lateral direction of the SEM image G21 and the contour lines of the partition walls 12 are specified, and the intersection points Q1′ and Q2′ are identified. A distance D12′ of .
  • a line PL1' parallel to the horizontal direction of the SEM image G21 is drawn from the intersection Q1', and a line PL2' parallel to the horizontal direction of the SEM image G21 is drawn from the intersection Q2'.
  • a rectangular measurement region NR11 is set at a position separated by a distance D1′ from the line PL1′ in the second uneven surface 42, and a second region S1b (this region is the first
  • a rectangular measurement area NR12 is set at a position separated by a distance D2′ from the line PL2′ in the inside (not covered with the catalyst portion 20).
  • the distances D1' and D2' are 0.5 times the thickness of the partition wall 12 (distance D12').
  • the dimension in the vertical direction (the X-axis direction in FIG. 15) of the measurement regions NR11 and NR12 is 1.5 times the thickness (distance D12′) of the partition wall 12, and the dimension in the horizontal direction (Y direction in FIG. 15) of the measurement regions NR11 and NR12 axial direction) is five times the thickness of the partition 12 (distance D12').
  • a Si mapping image of the SEM image G21 is obtained.
  • the element to be mapped is an element unique to the base material 10 (an element contained in the base material 10 but not contained in the first catalyst part 20 and the second catalyst part 30), silicon Elements other than (Si) may be used.
  • the measurement areas NR11 and NR12 are binarized.
  • R21 1 ⁇ (number of dots in binarized measurement region NR11)/(number of dots in binarized measurement region NR12)
  • the number of dots in the binarized measurement region NR11 is regarded as the area of a part of the first region S2a that is not covered with the second catalyst portion 30, and the binarized measurement region NR12 is regarded as the area of the first region S2a.
  • R 21 is calculated for each of the three cut pieces M, and the average value is taken as the R 21 of the exhaust gas purifying catalyst 1 .
  • the measuring equipment and measuring conditions used for calculating R21 are the same as those for R11 .
  • a cut piece N shown in FIGS. 13 and 14 is prepared in the same manner as above.
  • the second uneven surface 42 is exposed, and the second region S1b (the region is not covered with the first catalyst portion 20) is exposed. ing.
  • the height NH of the partition 12 located between these exposed surfaces is adjusted to 500 ⁇ m or more.
  • the area indicated by reference numeral R7 in FIG. 14 is scanned with a surface roughness meter from the Z-axis direction (the direction perpendicular to the paper surface of FIG. 14), and the scanned image G22 shown in FIG. measure the thickness.
  • the scan image G22 is captured so that the length direction Y of the cut piece N is aligned with the Y-axis direction of the scan image G22 (vertical direction in FIG. 16).
  • the scan magnification is adjusted so that the entire area indicated by reference numeral R7 in FIG. 14 is included in the scan range.
  • focusing is performed in the second region S1b, and the scanning range in the Z-axis direction (the direction perpendicular to the paper surface of FIG. 14) is ⁇ 400 ⁇ m with respect to the focused second region S1b. and Since the height NH of the partition 12 is adjusted to 500 ⁇ m or more, the partition 12 is out of the scan range, and as shown in FIG.
  • line analysis is performed on the center line CL22 perpendicular to the Y-axis direction (vertical direction in FIG. 16) of the scan image G22.
  • the part where the outside of the scan range continues for 10 ⁇ m or more is regarded as the partition wall 12, and the x-coordinates of the left end point P1′ and the right end point P2′ of the second uneven surface 42 and the left end point P3′ of the second region S1b are measured. and the x-coordinate of the right end point P4'.
  • a line QL1' passing through the left end point P1' and parallel to the Y-axis direction of the scan image G22, and a line QL2' passing through the right end point P2' and being parallel to the Y-axis direction of the scan image G22. are drawn, and these lines are defined as boundary lines between the second uneven surface 42 and the partition wall 12 .
  • a distance DS1' between the line QL1' and the line QL2' is defined as the width of the second uneven surface 42 (dimension in the X-axis direction).
  • a line QL3' passing through the left end point P3' and parallel to the Y-axis direction of the scan image G22, and a line QL4' passing through the right end point P4' and being parallel to the Y-axis direction of the scan image G22. are drawn, and these lines are used as boundary lines between the second region S1b and the partition wall 12 .
  • a distance DS2' between the line QL3' and the line QL4' is defined as the width (dimension in the X-axis direction) of the second region S1b.
  • a rectangular shape is formed at a predetermined distance (0.25 times the width of the second uneven surface 42 (distance DS1')) from the lines QL1' and QL2'.
  • a measurement region NR21 having a shape is set, and a predetermined distance (0.25 times the width of the second region S1b (distance DS2')) from the lines QL3' and QL4' in the second region S1b,
  • a rectangular measurement area NR22 is set.
  • the dimension of the measurement region NR21 in the X-axis direction (horizontal direction in FIG.
  • the dimension in the X-axis direction (horizontal direction in FIG. 16) of the measurement region NR22 is 0.5 times the width (distance DS2′) of the second region S1b
  • the dimension in the Y-axis direction (vertical direction in FIG. 16) of the measurement region NR22 ) is twice the width (distance DS2′) of the second region S1b.
  • the difference V1′ is regarded as the surface roughness of the second uneven surface 42
  • the difference V2′ is the roughness of the first region S2a (the first region S2a before the second catalyst portion 30 is formed). regarded as surface roughness.
  • R 22 is calculated for each of the three cut pieces N, and the average value is taken as the R 22 of the exhaust gas purifying catalyst 1 .
  • the measuring equipment and measuring conditions used for calculating R22 are the same as those for R12 .
  • the difference V2' is usually 20 ⁇ m or more and 120 ⁇ m or less, preferably 40 ⁇ m or more and 100 ⁇ m or less, more preferably 50 ⁇ m or more and 80 ⁇ m or less.
  • the first catalyst portion 20 and the second catalyst portion 30 each contain at least one precious metal element.
  • the noble metal element can be selected from, for example, platinum element (Pt), palladium element (Pd), rhodium element (Rh), ruthenium element (Ru), iridium element (Ir), osmium element (Os), etc. From the viewpoint of improving exhaust gas purification performance, it is preferable to select from Pt, Pd and Rh elements.
  • the noble metal element is in a form capable of functioning as a catalytically active component, for example, in the form of a noble metal, an alloy containing a noble metal element, a compound containing a noble metal element (for example, an oxide of a noble metal element), or the like. Included in section 30 .
  • the catalytically active component is preferably particulate from the viewpoint of improving exhaust gas purification performance.
  • the amount of the noble metal element per unit volume of the substrate 10 is, from the viewpoint of the balance between exhaust gas purification performance and cost, In terms of noble metal, it is preferably 0.5 g/L or more and 1.5 g/L or less.
  • first catalyst part 20 and the second catalyst part 30 each contain a carrier, and that the catalytically active component be carried on the carrier.
  • the catalytically active component is supported on the carrier means a state in which the catalytically active component is physically or chemically adsorbed or held on the outer surface or the inner surface of the pores of the carrier.
  • EDS energy dispersive spectrometer
  • the carrier examples include inorganic oxide particles.
  • the inorganic oxide that constitutes the inorganic oxide particles may be an inorganic oxide having an oxygen storage capacity (OSC: Oxygen Storage Capacity) (hereinafter sometimes referred to as an "oxygen storage component"), or a component other than the oxygen storage component. may be an inorganic oxide of
  • oxygen storage components include cerium oxide, composite oxides containing cerium element and zirconium element (CeO 2 —ZrO 2 -based composite oxides), and the like.
  • cerium oxide and zirconium oxide preferably form a solid solution phase.
  • Cerium oxide and zirconium oxide may each form a single phase (cerium oxide phase, zirconium oxide phase) in addition to a solid solution phase.
  • the CeO 2 —ZrO 2 -based composite oxide may contain one or more metal elements other than the cerium element and the zirconium element.
  • Metal elements other than the cerium element and the zirconium element or their oxides may form a solid solution phase with cerium oxide and/or zirconium oxide, or may form a single phase.
  • Examples of metal elements other than the cerium element and the zirconium element include rare earth elements other than the cerium element, alkaline earth metals, and transition metals.
  • inorganic oxides other than oxygen storage components include alumina, silica, silica-alumina, alumino-silicate, alumina-zirconia, alumina-chromia, alumina-ceria, alumina-lanthana, and titania.
  • a method for manufacturing the exhaust gas purifying catalyst 1 will be described below.
  • a substrate 10, a slurry for forming the first catalyst portion 20, and a slurry for forming the second catalyst portion 30 are prepared.
  • the composition of the slurry for forming the first catalyst portion 20 and the second catalyst portion 30 is adjusted according to the composition of the first catalyst portion 20 and the second catalyst portion 30, respectively.
  • the slurry contains, for example, a source of precious metal elements, inorganic oxide particles, a binder, a pore former, a solvent, and the like.
  • Examples of the supply source of the noble metal element include salts of the noble metal element, and examples of the salt of the noble metal element include nitrates, ammine complex salts, acetates, and chlorides.
  • Inorganic oxides constituting the inorganic oxide particles include, for example, oxygen storage components, inorganic oxides other than oxygen storage components, and the like.
  • binders include alumina sol, zirconia sol, titania sol, silica sol, and ceria sol.
  • pore-forming material include crosslinked polymethyl(meth)acrylate particles, crosslinked polybutyl(meth)acrylate particles, crosslinked polystyrene particles, crosslinked polyacrylate particles, and melamine resins.
  • solvents include water and organic solvents. Examples of organic solvents include alcohol, acetone, dimethylsulfoxide, dimethylformamide and the like. The solvent may be one solvent or a mixture of two or more solvents. Examples of mixtures of two or more solvents include a mixture of water and one or more organic solvents, a mixture of two or more organic solvents, and the like.
  • the end of the substrate 10 on the exhaust gas inflow side is immersed in the slurry for forming the first catalyst portion 20, the slurry is sucked from the opposite side, and then dried. Thereby, the precursor of the first catalyst part 20 is formed.
  • the length LS1a of the first region S1a where the precursor of the first catalyst part 20 is formed can be adjusted.
  • the thickness of the precursor of the first catalyst part 20 (and thus R 11 and R 12 ) and the mass of the precursor of the first catalyst portion 20 per unit volume of the substrate 10 (and thus the mass of the first catalyst portion 20 per unit volume of the substrate 10) can be adjusted.
  • the drying temperature is, for example, 40-120°C.
  • the end of the substrate 10 on the exhaust gas outflow side is immersed in the slurry for forming the second catalyst portion 30, the slurry is sucked from the opposite side, and then dried. Thereby, the precursor of the second catalytic portion 30 is formed.
  • the length LS2a of the first region S2a where the precursor of the second catalyst portion 30 is formed can be adjusted.
  • the thickness of the precursor of the second catalyst portion 30 (and thus R 21 and R 22 ) and the mass of the precursor of the second catalyst portion 30 per unit volume of the substrate 10 (and thus the mass of the second catalyst portion 30 per unit volume of the substrate 10) can be adjusted.
  • the drying temperature is, for example, 40-120°C.
  • the particle size of the inorganic oxide particles in the slurry can be adjusted as appropriate. From the viewpoint of easily adjusting R 11 , R 12 , R 21 and R 22 to desired ranges, D 90 of the inorganic oxide particles in the slurry is preferably 10 ⁇ m or more and 30 ⁇ m or less, more preferably 15 ⁇ m or more and 25 ⁇ m or less. be. D90 is the particle size at which the cumulative volume is 90% in the volume-based particle size distribution measured by a laser diffraction scattering particle size distribution measurement method.
  • the particle size of the pore-forming material can be adjusted as appropriate.
  • the median diameter D 50 of the pore-forming material is preferably 1 ⁇ m or more and 30 ⁇ m or less, more preferably 3 ⁇ m or more and 25 ⁇ m or less. It is preferably 5 ⁇ m or more and 20 ⁇ m or less.
  • D50 is the particle size at which the cumulative volume is 50% in the volume-based particle size distribution measured by a laser diffraction/scattering particle size distribution measurement method.
  • Measurement of D 50 or D 90 is performed using a laser diffraction scattering particle size distribution analyzer automatic sample feeder ("Microtorac SDC” manufactured by Microtrac Bell), and the sample to be measured is put into an aqueous dispersion medium, 26 mL After irradiating 40 W ultrasonic waves for 360 seconds at a flow rate of /sec, a laser diffraction scattering type particle size distribution analyzer ("Microtrac MT3300EXII” manufactured by Microtrac Bell) is used. The measurement was performed twice under the conditions of a particle refractive index of 1.5, a particle shape of a true sphere, a solvent refractive index of 1.3, a set zero of 30 seconds, and a measurement time of 30 seconds. Take the average value as D50 or D90 . Pure water is used as the aqueous dispersion medium.
  • the calcination temperature is preferably 350 to 550° C. from the viewpoints of preventing a decrease in catalytic activity and of successfully calcining the pore-forming material.
  • the atmosphere during firing is, for example, an air atmosphere.
  • Example 1 (1) Preparation of Slurry A rhodium nitrate aqueous solution and a dinitrodiammineplatinum nitric acid aqueous solution were mixed, and Ce--Zr composite oxide powder and alumina powder were added to the mixed liquid. Next, a pore-forming material (crosslinked polymethyl(meth)acrylate particles having a median diameter D50 of 20 ⁇ m), alumina sol, and water as a solvent were added to the mixed liquid to prepare a slurry.
  • a pore-forming material crosslinked polymethyl(meth)acrylate particles having a median diameter D50 of 20 ⁇ m
  • the amount of each component in the slurry is 1% by mass of rhodium in terms of metal, 75% by mass of Ce—Zr-based composite oxide powder, and alumina powder, based on the mass of the catalyst portion formed by drying and firing the slurry. was 7% by mass, platinum was 9% by mass in terms of metal, and alumina sol was adjusted to be 8% by mass in terms of solid content. Also, the amount of the pore-forming material in the slurry was adjusted so as to be 30.0% by mass of the mass of the catalyst portion formed by drying and firing the slurry. The mass of the catalyst portion formed by drying and firing the slurry is obtained by subtracting the mass of components (for example, solvent, pore-forming material, etc.) that disappear due to the drying and firing of the slurry from the mass of the slurry.
  • the D90 of the metal oxide powder (Ce--Zr composite oxide powder and alumina powder) in the slurry was 20 ⁇ m.
  • a substrate having porous partition walls separating the cells and the outflow-side cells was prepared.
  • the partition walls had a thickness of 200 to 250 ⁇ m, the total number of inflow-side cells and outflow-side cells in a cross section perpendicular to the axial direction of the substrate was 300 cells per square inch, and the volume of the substrate was 1.5 ⁇ m. 0L and the length of the substrate is 91 mm.
  • the average pore diameter of the partition walls is 15 ⁇ m, and the porosity (porosity) of the partition walls is 63%.
  • the end of the substrate on the exhaust gas inflow side was immersed in the slurry, the slurry was sucked from the opposite side, and then dried at 90°C for 10 minutes.
  • a first precursor (first catalyst portion before firing) composed of the solid content of the slurry was formed on the inflow side cell side of the partition wall of the substrate.
  • the end of the substrate on the exhaust gas outflow side was immersed in the slurry, the slurry was sucked from the opposite side, and then dried at 90°C for 10 minutes.
  • the second precursor (the second catalyst portion before firing) composed of the solid content of the slurry was formed on the outflow side cell side of the partition wall of the base material.
  • Example 1 an exhaust gas purifying catalyst of Example 1 was obtained.
  • the length of the substrate is the length of the first region of the inflow side cell side surface of the partition wall where the first catalyst portion is formed.
  • the ratio of the length of the first region where the second catalyst portion is formed on the outflow side cell side surface of the partition wall to the length of the base material is 0.70.
  • the immersion conditions were adjusted so that the total mass (WC amount) of the first catalyst portion and the second catalyst portion per unit volume of the substrate was 11 g/L.
  • R 11 , R 12 , R 21 and R 22 were calculated according to the above method.
  • Pressure loss ratio (pressure loss of exhaust gas purifying catalyst of Example 1/pressure loss of substrate) x 100
  • a pressure loss ratio of less than 105% was evaluated as "S”
  • a pressure loss ratio of 105% or more and less than 125% was evaluated as "A”
  • a pressure loss ratio of 125% or more was evaluated as "B”.
  • the measurement conditions for PM trapping performance were as follows. Evaluation vehicle: 1.5L direct-injection turbo engine Gasoline used: Fuel for certification test PM measurement device: Horiba Ltd.
  • the PM trapping performance ratio (%) was obtained based on the following formula.
  • PM collection performance ratio (PM collection performance of exhaust gas purifying catalyst of Example 1/PM collection performance of substrate) x 100
  • Example 2 When the exhaust gas inflow side and the exhaust gas outflow side end of the substrate are immersed in the slurry, the total mass (WC amount) of the first catalyst portion and the second catalyst portion per unit volume of the substrate is 16 g/L. 2, the same operation as in Example 1 was performed, except that the immersion conditions were adjusted.
  • Example 3 When the exhaust gas inflow side and the exhaust gas outflow side end of the substrate are immersed in the slurry, the total mass (WC amount) of the first catalyst portion and the second catalyst portion per unit volume of the substrate is 20 g / L. 2, the same operation as in Example 1 was performed, except that the immersion conditions were adjusted.
  • Example 4 The same procedure as in Example 1 was carried out, except that crosslinked polymethyl(meth)acrylate particles having a median diameter D50 of 5 ⁇ m were used as the pore-forming material.
  • Example 1 The same operation as in Example 1 was performed, except that the D90 of the metal oxide powder (Ce--Zr composite oxide powder and alumina powder) in the slurry was adjusted to 0.5 ⁇ m.
  • Reference Signs List 1 Exhaust gas purifying catalyst 10 Base material 20 First catalyst part 30 Second catalyst part 11 Cylindrical part 12 of base material Partition wall 13 of base material Cells 13a in the base material Inflow-side cells 13b Outflow-side cells S1a First region S1b of the inflow-side cell-side surface of the partition wall Second region S1b of the inflow-side cell-side surface of the partition wall Region S2a First region S2b on the outflow-side cell-side surface of the partition wall Second region 41 on the outflow-side cell-side surface of the partition wall First uneven surface 42 Second uneven surface

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