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WO2025028434A1 - Catalyseur d'épuration de gaz d'échappement - Google Patents

Catalyseur d'épuration de gaz d'échappement Download PDF

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Publication number
WO2025028434A1
WO2025028434A1 PCT/JP2024/026778 JP2024026778W WO2025028434A1 WO 2025028434 A1 WO2025028434 A1 WO 2025028434A1 JP 2024026778 W JP2024026778 W JP 2024026778W WO 2025028434 A1 WO2025028434 A1 WO 2025028434A1
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WIPO (PCT)
Prior art keywords
oxide particles
layer
mass
exhaust gas
catalyst layer
Prior art date
Legal status (The legal status 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 status listed.)
Pending
Application number
PCT/JP2024/026778
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English (en)
Japanese (ja)
Inventor
明秀 前田
淳 澤田
輝 石井
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Mitsui Kinzoku Co Ltd
Original Assignee
Mitsui Mining and Smelting Co Ltd
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Filing date
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Publication of WO2025028434A1 publication Critical patent/WO2025028434A1/fr
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Anticipated expiration legal-status Critical

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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
    • 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
    • B01J35/60—Catalysts, in general, characterised by their form or physical properties characterised by their surface properties or porosity
    • 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
    • F01N3/18—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 methods of operation; Control
    • 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
    • F01N3/24—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

Definitions

  • the present invention relates to a catalyst for purifying exhaust gas.
  • Exhaust gas emitted from internal combustion engines of automobiles, motorcycles, etc. contains harmful components such as hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (NOx).
  • exhaust gas purification catalysts containing precious metal elements such as Pt, Pd, and Rh are used.
  • Pt and Pd are mainly involved in the oxidation purification of HC and CO, while Rh is mainly involved in the reduction purification of NOx.
  • Exhaust gas purification catalysts are required to react under high SV (Space Velocity) conditions. For this reason, it is important to increase the exhaust gas diffusion properties of the catalyst layer. In particular, motorcycles are more likely to experience high SV conditions than four-wheeled automobiles, and the reduction in emissions due to unpurified exhaust gas blowing through is an issue.
  • SV Space Velocity
  • Patent Document 1 describes an exhaust gas purifying catalyst including a substrate and a catalyst layer provided on the substrate, The catalyst layer meets the following conditions: (1) In a pore distribution curve measured by a mercury porosimeter, the largest peak of pore volume is in the pore diameter range of 1 ⁇ m or more and 10 ⁇ m or less; (2) In an electron microscope observation image (observation magnification: 1000 times) of the surface of the catalyst layer, when the areas of a plurality of voids contained in the electron microscope observation image are calculated, the standard deviation of the areas of the plurality of voids is 30 ⁇ m2 or less; The document describes an exhaust gas purification catalyst that satisfies all of the above requirements.
  • the present invention aims to provide an exhaust gas purification catalyst that can improve exhaust gas diffusion and reactivity to diffused exhaust gas.
  • a catalyst for purifying exhaust gas comprising a metal honeycomb substrate and a catalyst layer provided on the metal honeycomb substrate, the catalytic layer contains a precious metal element, Ce-based oxide particles, and Ce-Zr-based composite oxide particles; a logarithmic differential pore volume distribution curve of the catalytic layer obtained by mercury intrusion porosimetry has a first peak value in a pore diameter range of 5 nm or more and 15 nm or less and a second peak value in a pore diameter range of 200 nm or more and 3200 nm or less; The first peak value is 0.060 mL/g or more; The exhaust gas purifying catalyst, wherein the second peak value is 0.018 mL/g or more.
  • the Al-based oxide particles have a median diameter of 15 ⁇ m or more and 30 ⁇ m or less.
  • the catalyst layer comprises a first layer provided on the metal honeycomb substrate and a second layer provided on the first layer; at least a portion of the Ce-based oxide particles and at least a portion of the Ce-Zr-based composite oxide particles are contained in the first layer;
  • a content of the Ce-based oxide particles in the first layer is 10 mass % or more and 80 mass % or less, based on a total mass of the Ce-based oxide particles and the Ce-Zr-based composite oxide particles in the first layer.
  • the catalyst layer contains Al-based oxide particles, The exhaust gas purifying catalyst according to any one of [8] to [10], wherein at least a part of the Al-based oxide particles is contained in the first layer.
  • the present invention provides an exhaust gas purification catalyst that can improve exhaust gas diffusion and reactivity to diffused exhaust gas.
  • FIG. 1 is a partial end view showing a state in which an exhaust gas purifying catalyst according to one embodiment of the present invention is disposed in an exhaust path of an internal combustion engine.
  • FIG. 2 is an end view taken along line AA of FIG.
  • FIG. 3 is an enlarged view of the area indicated by the symbol R in FIG.
  • FIG. 4 is an end view taken along line BB of FIG.
  • catalyst 1 an exhaust gas purification catalyst 1 (hereinafter referred to as "catalyst 1") according to one embodiment of the present invention will be described with reference to Figures 1 to 4.
  • the catalyst 1 is disposed in an exhaust passage in an exhaust pipe P of an internal combustion engine.
  • the internal combustion engine is, for example, a gasoline engine.
  • Exhaust gas discharged from the internal combustion engine flows through the exhaust passage in the exhaust pipe P from one end to the other end of the exhaust pipe P, and is purified by the catalyst 1 provided in the exhaust pipe P.
  • the exhaust gas flow direction is indicated by the symbol X.
  • the upstream side of the exhaust gas flow direction X may be referred to as the "exhaust gas inflow side" or "upstream side”
  • the downstream side of the exhaust gas flow direction X may be referred to as the "exhaust gas outflow side" or "downstream side”.
  • exhaust gas purification catalysts may be arranged in the exhaust passage in the exhaust pipe P, upstream or downstream of the catalyst 1.
  • the catalyst 1 comprises a metal honeycomb substrate 10 (hereinafter referred to as "substrate 10") and a first layer 21 provided on the substrate 10.
  • the substrate 10 is a honeycomb structure made of a metal material.
  • the metal material constituting the substrate 10 can be appropriately selected from known metal materials. Examples of materials constituting the substrate 10 include alloys such as stainless steel.
  • the tubular portion 11 defines the outer shape of the substrate 10, and the axial direction of the tubular portion 11 coincides with the axial direction of the substrate 10.
  • the shape of the tubular portion 11 is cylindrical, but it may be other shapes such as an elliptical cylinder or a polygonal cylinder.
  • partitions 12 there are partitions 12 between adjacent cells 13, and adjacent cells 13 are separated by the partitions 12.
  • the thickness of the partitions 12 is, for example, 20 ⁇ m or more and 1500 ⁇ m or less.
  • the cell 13 extends in the exhaust gas flow direction X and has an end on the exhaust gas inlet side and an end on the exhaust gas outlet side.
  • both the exhaust gas inlet end and the exhaust gas outlet end of cell 13 are open. Therefore, exhaust gas that flows in from the exhaust gas inlet end (opening) of cell 13 flows out from the exhaust gas outlet end (opening) of cell 13.
  • This type of configuration is called a flow-through type.
  • the end (opening) of cell 13 on the exhaust gas inlet side has a rectangular shape in plan view, but may have other shapes such as a hexagon or octagon.
  • the end (opening) of cell 13 on the exhaust gas outlet side also has a similar shape in plan view.
  • the cell density per square inch of the substrate 10 is, for example, 100 cells or more and 1000 cells or less.
  • the cell density per square inch of the substrate 10 means the total number of cells 13 per square inch in a cross section obtained by cutting the substrate 10 along a plane perpendicular to the exhaust gas flow direction X.
  • the volume of the substrate 10 is, for example, 0.1 L or more and 20 L or less.
  • the volume of the substrate 10 means the apparent volume of the substrate 10.
  • Catalyst layer The catalyst layer 20 will now be described.
  • the catalyst layer 20 is provided on the cell 13 side surface of the partition section 12.
  • the cell 13 side surface of the partition section 12 means the outer surface of the partition section 12 extending in the exhaust gas flow direction X.
  • the catalyst layer 20 may be provided directly on the cell 13 side surface of the partition section 12 or may be provided via another layer, but is usually provided directly on the cell 13 side surface of the partition section 12.
  • the catalyst layer 20 extends along the exhaust gas flow direction X from the end of the partition section 12 on the exhaust gas inlet side to the end of the partition section 12 on the exhaust gas outlet side.
  • the catalyst layer 20 may extend along the exhaust gas flow direction X from the end of the partition section 12 on the exhaust gas inlet side so as not to reach the end of the partition section 12 on the exhaust gas outlet side, or may extend along the direction opposite to the exhaust gas flow direction X from the end of the partition section 12 on the exhaust gas outlet side so as not to reach the end of the partition section 12 on the exhaust gas inlet side.
  • a first peak value exists in the pore diameter range of 5 nm or more and 15 nm or less, and a second peak value exists in the pore diameter range of 200 nm or more and 3200 nm or less.
  • the maximum value of the two or more maximum values corresponds to the "first peak value.”
  • the maximum value of the two or more maximum values corresponds to the "second peak value.”
  • the first peak value is 0.060 mL/g or more.
  • the first peak value reflects the amount of relatively small pores that contribute to an increase in the specific surface area of the catalyst layer 20.
  • the specific surface area of the catalyst layer 20 increases, and the exhaust gas contactability and exhaust gas adsorption ability of the catalyst layer 20 are improved.
  • the improved exhaust gas contactability and exhaust gas adsorption ability of the catalyst layer 20 improves the reactivity of the catalyst layer 20 to the diffused exhaust gas.
  • the second peak value is 0.018 mL/g or more.
  • the second peak value reflects the amount of relatively large pores that contribute to improving the exhaust gas diffusion property of the catalyst layer 20.
  • the second peak value is 0.018 mL/g or more, the gas diffusion property of the catalyst layer 20 is improved. By improving the gas diffusion property of the catalyst layer 20, unpurified exhaust gas is prevented from passing through the catalyst layer 20 without being purified.
  • the first peak value is preferably 0.075 mL/g or more, more preferably 0.080 mL/g or more, and even more preferably 0.090 mL/g or more.
  • the second peak value is preferably 0.030 mL/g or more, more preferably 0.035 mL/g or more, and even more preferably 0.040 mL/g or more.
  • the upper limit of the second peak value is not particularly limited. From the viewpoint of achieving a balance between an increase in the specific surface area of the catalyst layer 20 and an improvement in the gas diffusivity of the catalyst layer 20, the second peak value is preferably 0.110 mL/g or less, more preferably 0.080 mL/g or less, and even more preferably 0.070 mL/g or less. Each of these upper limits may be combined with any of the lower limits described above.
  • the second peak value is preferably in the pore diameter range of 200 nm or more and 1600 nm or less, more preferably in the pore diameter range of 200 nm or more and 950 nm or less, even more preferably in the pore diameter range of 300 nm or more and 700 nm or less, and most preferably in the pore diameter range of 400 nm or more and 600 nm or less.
  • log differential pore volume distribution curve refers to a curve obtained by dividing the pore volume increase (differential pore volume dV) by the common logarithm (log) difference between the upper and lower values of the corresponding pore diameters (difference value d(logD)), and plotting the value (log differential pore volume dV/d(logD)) against the midpoint of the pore diameter increase (average pore diameter for each interval).
  • pore diameter refers to diameter.
  • the horizontal axis represents the pore diameter ( ⁇ m) of catalyst layer 20
  • the vertical axis represents the logarithmic differential pore volume (mL/g) of catalyst layer 20 per unit mass of cut pieces M1 or M2 obtained from catalyst 1. Cut pieces M1 and M2 will be described later.
  • the logarithmic differential pore volume distribution curve of the catalyst layer 20 can be obtained by the following method.
  • the 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 the portions indicated by symbols M1 and M2 in FIG. 4 are cut out to obtain cut pieces M1 and M2 including a portion of the partition section 12 and a portion of the catalyst layer 20.
  • the length of the portion of the partition section 12 included in cut pieces M1 and M2 is equal to the length of cut pieces M1 and M2.
  • the length of the portion of the catalyst layer 20 included in cut pieces M1 and M2 is equal to the length of cut pieces M1 and M2.
  • the cut pieces M1 and M2 can be obtained from near the exhaust gas inlet end and near the exhaust gas outlet end of the catalyst 1, respectively.
  • a cut piece M1 having a length of 20 mm including a part of the partition wall 12 and a part of the catalyst layer 20 can be obtained, and by cutting the substrate 10 at two locations 10 mm and 30 mm away from the exhaust gas outlet end in the direction opposite to the exhaust gas flow direction X along a plane perpendicular to the axial direction of the substrate 10, a cut piece M2 having a length of 20 mm including a part of the partition wall 12 and a part of the catalyst layer 20 can be obtained.
  • the size of the cut piece M1 or M2 can be changed as appropriate.
  • the cut piece M1 or M2 has a rectangular parallelepiped shape with a cross section of, for example, 10 mm long x 10 mm wide and a length of 20 mm.
  • Mercury intrusion porosimetry can be carried out using the Shimadzu Corporation's Autopore IV9520 automatic porosimeter under the following conditions and procedures.
  • a logarithmic differential pore volume distribution curve (log differential pore volume distribution curve) is calculated from the mercury injection pressure, the amount of mercury injected, and the mass of the cut piece M1 or M2.
  • the above steps (a), (b) and (c) can be carried out automatically using software provided with the device. Other conditions can be in accordance with JIS R 1655:2003.
  • the cut pieces M1 or M2 include a part of the partition wall 12 of the substrate 10 and a part of the catalyst layer 20, but since the partition wall 12 of the substrate 10 does not have a pore diameter, the logarithmic differential pore volume distribution obtained by the mercury intrusion method reflects the logarithmic differential pore volume distribution of the catalyst layer 20.
  • a logarithmic differential pore volume distribution curve of the catalyst layer 20 may be obtained by performing mercury intrusion using one of the cut pieces M1 or M2, or a logarithmic differential pore volume distribution curve of the catalyst layer 20 may be obtained by performing mercury intrusion using both the cut pieces M1 and M2. In the former case, one logarithmic differential pore volume distribution curve is obtained, and in the latter case, two logarithmic differential pore volume distribution curves are obtained.
  • the specific surface area of the catalyst layer 20 is preferably 70 m 2 /g or more and 200 m 2 /g or less, more preferably 75 m 2 /g or more and 145 m 2 /g or less, and even more preferably 80 m 2 /g or more and 100 m 2 /g or less.
  • the catalyst layer 20 as a whole satisfies the condition that the first peak value corresponding to the amount of relatively small pores is 0.060 mL / g or more, and satisfies the condition that the second peak value corresponding to the amount of relatively large pores is 0.018 mL / g or more, so that the desired specific surface area of the catalyst layer 20 can be realized.
  • the specific surface area of the catalyst layer 20 is particularly highly correlated with the first peak value.
  • the specific surface area of the catalyst layer 20 can be measured by N 2 gas adsorption method using QUADRASORB SI manufactured by Quantachrome.
  • the mass of the catalyst layer 20 per unit volume of the portion of the substrate 10 where the catalyst layer 20 is provided is preferably 100 g/L or more and 300 g/L or less, more preferably 110 g/L or more and 250 g/L or less, and even more preferably 120 g/L or more and 200 g/L or less.
  • the mass of the catalyst layer 20 per unit volume of the portion of the substrate 10 on which the catalyst layer 20 is provided is calculated from the formula: (mass of the catalyst layer 20)/((volume of the substrate 10) ⁇ (average length L20 of the catalyst layer 20 /length L10 of the substrate 10 )).
  • length refers to the axial dimension of the substrate 10, unless otherwise specified.
  • the "mass of catalyst layer 20" refers to the sum of the masses of precious metal elements in metal equivalent and the masses of metal elements other than precious metal elements in oxide equivalent of all metal elements contained in catalyst layer 20. In other words, the “mass of catalyst layer 20” refers to the calculated mass obtained by summing the masses of precious metal elements contained in catalyst layer 20 in metal equivalent and the masses of metal elements other than precious metal elements contained in catalyst layer 20 in oxide equivalent. Note that “metal elements” also include metalloid elements such as Si and B.
  • ious metal elements include Au, Ag, Pt, Pd, Rh, Ir, Ru, and Os.
  • oxides of rare earth elements other than Ce, Pr, and Tb are referred to as sesquioxides ( Ln2O3 , where Ln represents a rare earth element other than Ce, Pr, and Tb), oxides of Ce are referred to as CeO2 , oxides of Pr are referred to as Pr6O11 , oxides of Tb are referred to as Tb4O7 , oxides of Al are referred to as Al2O3 , oxides of Zr are referred to as ZrO2 , oxides of Si are referred to as SiO2 , oxides of B are referred to as B2O3 , oxides of Cr are referred to as Cr2O3 , oxides of Mg are referred to as MgO , oxides of Ca are referred to as CaO, oxides of Sr are referred to as SrO, oxides of Ba are referred to as BaO, oxides of Fe are referred to as Fe3O4 , and oxides of Mn are referred to
  • An example of a method for measuring the average length L20 of the catalyst layer 20 is as follows.
  • a sample is cut out from the catalyst 1, extending in the axial direction of the substrate 10 and having the same length as the length L 10 of the substrate 10.
  • the sample is, for example, cylindrical with a diameter of 25.4 mm. The diameter value of the sample can be changed as necessary.
  • the sample is cut at 5 mm intervals by a plane perpendicular to the axial direction of the substrate 10, and a first cut piece, a second cut piece, ..., an nth cut piece are obtained in order from the end side of the exhaust gas inflow side of the sample.
  • the length of the cut piece is 5 mm.
  • the composition of the cut piece is analyzed using an X-ray fluorescence analyzer (XRF) (for example, an energy dispersive X-ray analyzer (EDX), a wavelength dispersive X-ray analyzer (WDX), etc.), an inductively coupled plasma atomic emission spectrometer (ICP-AES), a scanning electron microscope-energy dispersive X-ray analysis method (SEM-EDX), etc., and it is confirmed whether the cut piece includes a part of the catalyst layer 20 based on the composition of the cut piece.
  • XRF X-ray fluorescence analyzer
  • EDX energy dispersive X-ray analyzer
  • WDX wavelength dispersive X-ray analyzer
  • ICP-AES inductively coupled plasma atomic emission spectrometer
  • SEM-EDX scanning electron microscope-energy dispersive X-ray analysis method
  • the cut surface can be observed using a scanning electron microscope (SEM), an electron probe microanalyzer (EPMA), or the like to confirm whether the cut piece contains a portion of the catalyst layer 20.
  • SEM scanning electron microscope
  • EPMA electron probe microanalyzer
  • elemental mapping of the cut surface may also be performed.
  • the length of the catalyst layer 20 contained in the sample is (5 x k) mm.
  • a more detailed example of a method for measuring the length of the catalyst layer 20 included in a sample is as follows.
  • the kth piece i.e., the piece obtained from the exhaust gas outflow side of the sample among the pieces including a part of the catalyst layer 20
  • the kth piece is cut in the axial direction of the substrate 10, and the length of the part of the catalyst layer 20 in the kth piece is measured by observing the part of the catalyst layer 20 present on the cut surface using an SEM, an EPMA, etc.
  • the length of the catalyst layer 20 contained in each sample is measured, and the average value thereof is taken as the average length L 20 of the catalyst layer 20.
  • the catalyst layer 20 extends from the end of the exhaust gas outlet side of the partition section 12 in the direction opposite to the exhaust gas flow direction X so as not to reach the end of the exhaust gas inlet side of the partition section 12, the sample is cut at 5 mm intervals along a plane perpendicular to the axial direction of the substrate 10, and the first cut piece, second cut piece, ..., nth cut piece are obtained in order from the end of the exhaust gas outlet side of the sample.
  • the catalyst layer 20 contains one or more precious metal elements.
  • the precious metal element can be selected from, for example, Au, Ag, Pt, Pd, Rh, Ir, Ru, Os, etc., but is preferably selected from Rh, Pt, and Pd.
  • the precious metal element is contained in the catalyst layer 20 in a form capable of functioning as a catalytically active component, such as a metal, an alloy containing the precious metal element, or a compound containing the precious metal element (e.g., an oxide of the precious metal element).
  • a catalytically active component such as a metal, an alloy containing the precious metal element, or a compound containing the precious metal element (e.g., an oxide of the precious metal element).
  • the content of the precious metal elements in the catalyst layer 20 in terms of metal conversion is preferably 0.010 mass% or more and 20 mass% or less, more preferably 0.050 mass% or more and 10 mass% or less, and even more preferably 0.10 mass% or more and 5.0 mass% or less, based on the mass of the catalyst layer 20.
  • the content of the precious metal elements in terms of metal conversion in the catalyst layer 20 means the content of the one precious metal element in terms of metal conversion when the catalyst layer 20 contains one type of precious metal element, and means the total content of the two or more precious metal elements in terms of metal conversion when the catalyst layer 20 contains two or more types of precious metal elements.
  • the metal-equivalent content of the precious metal elements in the catalyst layer 20 can be determined from the composition of the raw materials.
  • the metal-equivalent content of the precious metal elements in the catalyst layer 20 can be determined using scanning electron microscope-energy dispersive X-ray analysis (SEM-EDX). Specifically, this is as follows:
  • Elemental analysis is performed on the sample obtained from catalyst layer 20 using SEM-EDX to identify the type of constituent elements in the entire sample and to determine the mole percentage of each identified metal element.
  • the mole percentage of each metal element is determined for each of 10 SEM fields of view, and the average of the mole percentages of each metal element in the 10 fields of view is taken as the mole percentage of each metal element in catalyst layer 20. From the mole percentages of each metal element in catalyst layer 20, the mass percentage of the precious metal group elements in catalyst layer 20 in metal equivalent and the mass percentage of each metal element other than the precious metal group elements in catalyst layer 20 in oxide equivalent are calculated.
  • the mass percentage of the precious metal group elements in catalyst layer 20 in metal equivalent is calculated from the formula: (mass of the precious metal group elements in metal equivalent calculated from mole percentage)/((mass of the precious metal group elements in metal equivalent calculated from mole percentage)+(mass of the metal elements other than the precious metal group elements in oxide equivalent calculated from mole percentage)) ⁇ 100.
  • the mass % of each metal element other than the precious metal group elements in the catalyst layer 20 in terms of oxide is calculated from the formula: (mass of each metal element other than the precious metal group elements in terms of oxide calculated from mol %) / ((mass of the precious metal group elements in terms of metal calculated from mol %) + (mass of the metal elements other than the precious metal group elements in terms of oxide calculated from mol %)) x 100.
  • At least a portion of the catalytically active components containing precious metal elements is preferably supported on one or more supports selected from Ce-based oxide particles and Ce-Zr-based composite oxide particles.
  • the catalyst layer 20 contains Al-based oxide particles
  • at least a portion of the catalytically active components containing precious metal elements is preferably supported on one or more supports selected from Ce-based oxide particles, Ce-Zr-based composite oxide particles, and Al-based oxide particles.
  • Ce-based oxide particles, Ce-Zr-based composite oxide particles, and Al-based oxide particles are described below.
  • At least a portion of the catalytically active component is supported on the carrier means that at least a portion of the catalytically active component is physically and/or chemically adsorbed and/or held on the outer surface and/or inner pore surface of the carrier. Whether at least a portion of the catalytically active component is supported on the carrier can be confirmed, for example, by using SEM-EDX. Specifically, when at least a portion of the catalytically active component and the carrier are present in the same region in elemental mapping obtained by analyzing a sample obtained from the catalyst layer 20 with SEM-EDX, it can be determined that at least a portion of the catalytically active component is supported on the carrier.
  • the catalyst layer 20 contains Ce-based oxide particles.
  • the Ce-based oxide particles contained in the catalyst layer 20 are distinguished from the Ce-based oxide particles used as a raw material for the catalyst layer 20.
  • the Ce-based oxide particles contained in the catalyst layer 20 are simply referred to as "Ce-based oxide particles,” and the Ce-based oxide particles used as a raw material for the catalyst layer 20 are referred to as "Ce-based oxide particles as raw material.”
  • Ce-based oxide particles can be used as a carrier for catalytically active components. From the viewpoint of improving the supportability of catalytically active components, it is preferable that the Ce-based oxide particles are porous.
  • the Ce-based oxide particles are distinguished from ceria used as a binder (hereinafter referred to as "ceria binder").
  • the ceria binder is derived from ceria sol used as a raw material for the catalyst layer 20, or water-soluble cerium salts such as cerium nitrate and cerium nitrate.
  • the Ce-based oxide particles are composed of Ce-based oxides.
  • the Ce-based oxide refers to an oxide containing Ce, in which Ce is the element with the highest content by mass, other than O, constituting the oxide. However, those that fall under the category of Ce-Zr-based composite oxide particles are not considered to fall under the category of Ce-based oxide particles. Note that the content of Zr in the Ce-based oxide particles, calculated as ZrO2 , is usually smaller than the content of Zr in the Ce-Zr-based composite oxide particles, calculated as ZrO2 , and from this point, the Ce-based oxide particles are distinguished from the Ce-Zr-based composite oxide particles.
  • the Ce-based oxide particles may contain one or more metal elements other than Ce.
  • the metal elements other than Ce may be selected from rare earth elements other than Ce (e.g., Y, Pr, Sc, La, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, etc.), alkaline earth metal elements (e.g., Mg, Ca, Sr, Ba, etc.), Fe, Mn, Ni, Zr, Al, etc.
  • the metal elements other than Ce may form a solid solution phase together with Ce and O, or may form a single phase that is a crystalline phase or an amorphous phase (e.g., an oxide phase of a metal element other than Ce), or may form both a solid solution phase and a single phase.
  • Ce-based oxide particles examples include ceria particles (particles composed of CeO2 ), particles obtained by modifying the surface of ceria particles with a metal element other than Ce or its oxide, and particles obtained by dissolving a metal element other than Ce in ceria particles.
  • Ce-based oxide particles are an important material for achieving a first peak value of 0.060 mL/g or more and a second peak value of 0.018 mL/g or more. Below, we will explain Ce-based oxide particles that are preferable for achieving the desired first peak value and second peak value.
  • the Ce content in the Ce-based oxide particles is preferably 90 mass% or more, more preferably 95 mass% or more, and even more preferably 99 mass% or more, based on the mass of the Ce-based oxide particles.
  • the upper limit is theoretically 100 mass%, but considering the presence of unavoidable impurities, it may actually be less than 100 mass%.
  • the Ce content in the Ce-based oxide particles in terms of CeO2 can be obtained by analyzing a sample obtained from the catalyst layer 20 by energy dispersive X-ray spectroscopy (EDX), and from the obtained elemental mapping and EDX elemental analysis of the specified particles.
  • EDX energy dispersive X-ray spectroscopy
  • the Ce-based oxide particles and other particles e.g., Ce-Zr based composite oxide particles, Al based oxide particles, etc.
  • composition analysis evaluation of composition analysis
  • the median diameter of Ce-based oxide particles as raw material can be measured using a laser diffraction scattering particle size distribution analyzer automatic sample feeder by putting the sample to be measured into an aqueous dispersion medium, irradiating it with ultrasound, and then using a laser diffraction scattering particle size distribution analyzer.
  • the specific method for measuring the median diameter of Ce-based oxide particles as raw material is as follows.
  • the sample to be measured is put into an aqueous dispersion medium, irradiated with 40 W ultrasound for 360 seconds at a flow rate of 32.5 mL/sec, and then measured using a laser diffraction scattering particle size distribution analyzer (Microtrac MT3300EXII, manufactured by Microtrac Bell).
  • a laser diffraction scattering particle size distribution analyzer (Microtrac MT3300EXII, manufactured by Microtrac Bell).
  • the median diameter of the Ce-based oxide particles can be estimated from the particle diameter (e.g., a unidirectional diameter such as the Feret diameter) of the Ce-based oxide particles, which is determined by observing a sample obtained from the catalyst layer 20 using a scanning electron microscope.
  • the particle diameter e.g., a unidirectional diameter such as the Feret diameter
  • XRD X-ray diffraction
  • the CeO2 crystallite size of the Ce-based oxide particles may be adjusted, for example, by adjusting the firing conditions when producing the Ce-based oxide particles, or by providing a crystallization step (e.g., exposure to hydrothermal conditions, etc.) in the production stage of the Ce-based oxide particles.
  • the catalyst layer 20 contains Ce—Zr based composite oxide particles.
  • the Ce-Zr-based composite oxide particles contained in the catalyst layer 20 are to be distinguished from the Ce-Zr-based composite oxide particles used as a raw material for the catalyst layer 20.
  • the Ce-Zr-based composite oxide particles contained in the catalyst layer 20 will be simply referred to as "Ce-Zr-based composite oxide particles”
  • the Ce-Zr-based composite oxide particles used as a raw material for the catalyst layer 20 will be referred to as "Ce-Zr-based composite oxide particles as raw material.”
  • Ce-Zr composite oxide particles can be used as a carrier for catalytically active components. From the viewpoint of improving the supportability of catalytically active components, it is preferable that the Ce-Zr composite oxide particles are porous.
  • Ce-Zr composite oxide particles have oxygen storage capacity (i.e., the ability to store oxygen when the oxygen concentration in the exhaust gas is high and release oxygen when the oxygen concentration in the exhaust gas is low), and they mitigate fluctuations in the oxygen concentration in the exhaust gas and expand the operating window of the catalytically active components. Therefore, by including Ce-Zr composite oxide in the catalyst layer 20, the exhaust gas purification capacity of the catalyst layer 20 is improved.
  • the Ce-Zr composite oxide particles are composed of Ce-Zr composite oxides.
  • Ce-Zr composite oxides are oxides that contain Ce and Zr.
  • the metal elements other than Ce and Zr may form a solid solution phase together with Ce, Zr, and O, or may form a single phase that is a crystalline phase or an amorphous phase (e.g., an oxide phase of a metal element other than Ce), or may form both a solid solution phase and a single phase.
  • the Ce content in the Ce-Zr composite oxide particles, calculated as CeO2 is preferably 5% by mass or more and 90% by mass or less, more preferably 5% by mass or more and 70% by mass or less, even more preferably 7% by mass or more and 60% by mass or less, and even more preferably 10% by mass or more and 50% by mass or less, based on the mass of the Ce-Zr composite oxide particles.
  • the Ce content in the Ce-Zr composite oxide particles, calculated as CeO2 can be determined in the same manner as the Ce content in the Ce-based oxide particles, calculated as CeO2 .
  • the total of the Ce content in terms of CeO2 and the Zr content in terms of ZrO2 in the Ce-Zr-based composite oxide particles is preferably 70 mass% or more, more preferably 75 mass% or more, even more preferably 80 mass% or more, and even more preferably 85 mass% or more, based on the mass of the Ce-Zr-based composite oxide particles.
  • the upper limit is 100 mass%.
  • the median diameter of the Ce-Zr composite oxide particles as the raw material is preferably 0.1 ⁇ m to 15 ⁇ m, more preferably 0.5 ⁇ m to 12 ⁇ m, and even more preferably 1 ⁇ m to 10 ⁇ m.
  • the meaning of the median diameter is as described above.
  • the median diameter of the Ce-Zr composite oxide particles as the raw material is maintained, so that the median diameter of the Ce-Zr composite oxide particles is usually the same as the median diameter of the Ce-Zr composite oxide particles as the raw material.
  • the median diameter of the Ce-Zr composite oxide particles as the raw material can be measured in the same manner as the median diameter of the Ce-Zr oxide particles as the raw material.
  • the catalyst layer 20 preferably contains Al-based oxide particles in addition to the Ce-based oxide particles and the Ce-Zr-based composite oxide particles.
  • the Al-based oxide particles contained in the catalyst layer 20 are distinguished from the Al-based oxide particles used as a raw material for the Al-based oxide particles contained in the catalyst layer 20.
  • Al-based oxide particles the Al-based oxide particles contained in the catalyst layer 20 will be simply referred to as "Al-based oxide particles”
  • Al-based oxide particles used as a raw material for the Al-based oxide particles contained in the catalyst layer 20 will be referred to as "Al-based oxide particles as raw material”.
  • the Al-based oxide particles can be used as a carrier for catalytically active components. From the viewpoint of improving the supportability of the catalytically active components, it is preferable that the Al-based oxide particles are porous.
  • the Al-based oxide particles are distinguished from alumina used as a binder (hereinafter referred to as "alumina binder").
  • the alumina binder is derived from alumina sol used as a raw material for the catalyst layer 20.
  • the adhesion between particles (for example, adhesion between Ce-based oxide particles and Al-based oxide particles, adhesion between Ce-Zr-based composite oxide particles and Al-based oxide particles, etc.) is improved, and the adhesion between the catalyst layer 20 and the substrate 10 is also improved.
  • Al-based oxide particles are composed of Al-based oxides.
  • Al-based oxides refer to oxides that contain Al, and in which the element other than O that constitutes the oxide has the highest content by mass of Al.
  • Ce-Zr composite oxide particles are not considered to be Al-based oxide particles.
  • the Al-based oxide particles may contain one or more metal elements other than Al.
  • the metal elements other than Al may be selected from rare earth elements other than Ce (e.g., Y, Pr, Sc, La, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, etc.), alkaline earth metal elements (e.g., Mg, Ca, Sr, Ba, etc.), B, Si, Zr, Cr, etc.
  • rare earth elements other than Ce
  • Ce rare earth elements
  • Sm e.g., Y, Pr, Sc, La, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, etc.
  • alkaline earth metal elements e.g., Mg, Ca, Sr, Ba, etc.
  • B Si, Zr, Cr, etc.
  • semimetal elements such as B and Si.
  • the metal elements other than Al may form a solid solution phase with Al and O, or may form a single phase that is a crystalline phase or an amorphous phase (e.g., an oxide phase of a metal element other than Al), or may form both a solid solution phase and a single phase.
  • Al-based oxide particles examples include alumina particles (particles composed of Al2O3 ), particles obtained by modifying the surface of alumina particles with a metal element other than Al or its oxide, and particles obtained by dissolving a metal element other than Al in alumina particles.
  • the amount of Al in the Al-based oxide particles calculated as Al 2 O 3 is preferably 70 mass % or more, more preferably 80 mass % or more, and even more preferably 90 mass % or more, based on the mass of the Al-based oxide particles.
  • the upper limit is theoretically 100 mass %, but considering the presence of unavoidable impurities, it may actually be less than 100 mass %.
  • the median diameter of the Al-based oxide particles as the raw material is preferably 15 ⁇ m to 30 ⁇ m, more preferably 16 ⁇ m to 25 ⁇ m, and even more preferably 17 ⁇ m to 21 ⁇ m.
  • the significance of the median diameter is as described above.
  • the median diameter of the Al-based oxide particles as the raw material is maintained, so that the median diameter of the Al-based oxide particles is usually the same as the median diameter of the Al-based oxide particles as the raw material.
  • the median diameter of the Al-based oxide particles as the raw material can be measured in the same manner as the median diameter of the Ce-based oxide particles as the raw material.
  • the median diameter of the Al-based oxide particles can be estimated from the particle diameter of the Al-based oxide particles (for example, a unidirectional diameter such as a Feret diameter) obtained by observing a sample obtained from the catalyst layer 20 using a scanning electron microscope.
  • the median diameter of the above-mentioned Ce-based oxide particles, Ce-Zr-based composite oxide particles, and Al-based oxide particles may be adjusted using a known grinding method such as a ball mill, or may be adjusted using a granulation method such as a spray-drying method during particle production.
  • the catalytic layer 20 may contain one or more inorganic oxide particles other than Ce-based oxide particles, Ce-Zr-based composite oxide particles, and Al-based oxide particles.
  • the inorganic oxide particles can be used as a carrier for a catalytically active component. From the viewpoint of improving the supportability of the catalytically active component, the inorganic oxide particles are preferably porous.
  • the inorganic oxide particles may or may not have an oxygen storage capacity (OSC).
  • OSC oxygen storage capacity
  • inorganic oxides constituting the inorganic oxide particles include oxides of rare earth elements other than Ce, zirconia (ZrO 2 ), silica (SiO 2 ), titania (TiO 2 ), zeolite (aluminosilicate), and oxides based on MgO, ZnO, SnO 2, etc.
  • the catalyst layer 20 may contain components such as a binder and a stabilizer.
  • binders include inorganic oxide binders such as alumina sol, ceria sol, zirconia sol, titania sol, and silica sol.
  • stabilizers include nitrates, carbonates, oxides, and sulfates of alkaline earth metal elements (e.g., Sr, Ba, etc.).
  • Ce-based oxide particles preferably means Ce-based oxide particles that are preferable for achieving the desired first peak value and second peak value described above.
  • the content of the Ce-Zr-based composite oxide particles in the catalyst layer 20 is preferably 5% by mass or more and 95% by mass or less, more preferably 30% by mass or more and 85% by mass or less, and even more preferably 40% by mass or more and 75% by mass or less, based on the total mass of the Ce-based oxide particles and the Ce-Zr-based composite oxide particles in the catalyst layer 20.
  • the total content of Ce-based oxide and Ce-Zr-based composite oxide particles in the catalyst layer 20 is preferably 15% by mass or more and 80% by mass or less, more preferably 25% by mass or more and 70% by mass or less, and even more preferably 35% by mass or more and 65% by mass or less, based on the mass of the catalyst layer 20.
  • the content of the Ce-Zr-based composite oxide particles in the catalyst layer 20 is preferably 10% by mass or more and 65% by mass or less, more preferably 20% by mass or more and 60% by mass or less, and even more preferably 30% by mass or more and 55% by mass or less, based on the total mass of the Ce-based oxide particles, the Ce-Zr-based composite oxide particles, and the Al-based oxide particles in the catalyst layer 20.
  • the content of the Al-based composite oxide particles in the catalyst layer 20 is preferably 10% by mass or more and 60% by mass or less, more preferably 20% by mass or more and 50% by mass or less, and even more preferably 25% by mass or more and 40% by mass or less, based on the total mass of the Ce-based oxide particles, the Ce-Zr-based composite oxide particles, and the Al-based oxide particles in the catalyst layer 20.
  • the total content of Ce-based oxide, Ce-Zr-based composite oxide particles, and Al-based oxide particles in the catalyst layer 20 is preferably 50% by mass or more and 99% by mass or less, more preferably 60% by mass or more and 95% by mass or less, and even more preferably 70% by mass or more and 90% by mass or less, based on the mass of the catalyst layer 20.
  • the content of Ce-based oxide particles, Ce-Zr-based composite oxide particles, and Al-based oxide particles in the catalyst layer 20 can be determined from the composition of the raw materials.
  • the average of the oxide-equivalent content of the predetermined element in the multiple visual fields is regarded as the oxide-equivalent content of the predetermined element in the sample.
  • Elemental mapping is performed by SEM-EDX on the sample obtained from the catalyst layer 20 to identify the types of particles contained in the sample (Ce-based oxide particles, Ce-Zr-based composite oxide particles, and in some cases Al-based oxide particles).
  • C For each type of particle, a number of arbitrarily selected particles (e.g., 50 particles) are subjected to elemental analysis by SEM-EDX to identify the types of constituent elements in the plurality of particles and to determine the content of the predetermined element in terms of oxide.
  • the average value of the content of the predetermined element in terms of oxide in the plurality of particles is regarded as the content of the predetermined element in terms of oxide in each type of particle.
  • (D) Calculate the content of each type of particle in the sample by creating and solving an equation that represents the relationship between the content of a specified element in the sample in terms of oxide, the content of a specified element in each type of particle in terms of oxide, and the content of each type of particle in the sample.
  • the Ce source, Zr source, and Al source in the catalyst layer 20 are composed of only three types of Ce-based oxide particles, Ce-Zr-based composite oxide particles, and Al-based oxide particles
  • the content of Ce-based oxide particles, Ce-Zr-based composite oxide particles, and Al-based oxide particles in the catalyst layer 20 can be measured by the following procedure.
  • elemental analysis is performed using SEM-EDX on 30 randomly selected fields of view of the sample obtained from the catalyst layer 20 to identify the types of constituent elements in the entire sample and to determine the oxide-equivalent content of the specified element.
  • the average of the oxide-equivalent content of the specified element in the 30 fields of view is taken as the oxide-equivalent content of the specified element in the sample.
  • elemental mapping is performed using SEM-EDX on the sample obtained from the catalyst layer 20 to identify the types of particles contained in the sample (Ce-based oxide particles, Ce-Zr-based composite oxide particles, and Al-based oxide particles).
  • 50 randomly selected particles are subjected to elemental analysis using SEM-EDX to identify the types of constituent elements in the 50 particles and to determine the oxide-equivalent content of the specified element.
  • the average of the oxide-equivalent content of the specified element in the 50 particles is taken as the oxide-equivalent content of the specified element in each type of particle.
  • the Ce content in the entire sample calculated as CeO2 (hereinafter referred to as "P T ")
  • the Ce content in the Ce-based oxide particles calculated as CeO2 (hereinafter referred to as " P1 ")
  • the Ce content in the Ce-Zr based composite oxide particles calculated as CeO2 (hereinafter referred to as " P2 )
  • the Ce content in the Al-based oxide particles calculated as CeO2 (hereinafter referred to as " P3 ”)
  • the content of Zr in the entire sample calculated as ZrO2 (hereinafter referred to as " QT ")
  • the content of Zr in the Ce-based oxide particles calculated as ZrO2 (hereinafter referred to as " Q1 ")
  • the content of Zr in the Ce-Zr based composite oxide particles calculated as ZrO2 (hereinafter referred to as " Q2 ")
  • the content of Zr in the Al-based oxide particles calculated as ZrO2 (hereinafter referred to as " Q3 ")
  • the content of each type of particle in the sample is calculated by creating and solving an equation that represents the relationship between the oxide-converted content of the specified element in the sample, the oxide-converted content of the specified element in each type of particle, and the content of each type of particle in the sample.
  • X, Y, and Z can be calculated, and the content (mass basis) of Ce-based oxide particles in the catalyst layer 20 can be calculated from X, the content (mass basis) of Ce-Zr-based composite oxide particles can be calculated from Y, and the content (mass basis) of Al-based oxide particles can be calculated from Z.
  • the catalyst layer 20 may have a single-layer structure or a multilayer structure.
  • the following describes an embodiment of the catalyst layer 20 having a laminated structure.
  • the catalyst layer 20 includes a first layer 21 provided on the substrate 10 and a second layer 22 provided on the first layer 21.
  • At least a portion of the Ce-based oxide particles in the catalyst layer 20 is included in the first layer 21.
  • a portion of the Ce-based oxide particles in the catalyst layer 20 may be included in the first layer 21, or all of the Ce-based oxide particles in the catalyst layer 20 may be included in the first layer 21.
  • the first layer 21 preferably contains Ce-based oxide particles that are favorable for achieving the desired first and second peak values described above.
  • At least a portion of the Ce-Zr composite oxide particles in the catalyst layer 20 is contained in the first layer 21.
  • a portion of the Ce-Zr composite oxide particles in the catalyst layer 20 may be contained in the first layer 21, or all of the Ce-Zr composite oxide particles in the catalyst layer 20 may be contained in the first layer 21.
  • At least a portion of the precious metal elements in the catalyst layer 20 are contained in the second layer 22.
  • a portion of the precious metal elements in the catalyst layer 20 may be contained in the second layer 22, or all of the precious metal elements in the catalyst layer 20 may be contained in the second layer 22.
  • the catalyst layer 20 contains Al-based oxide particles
  • at least a portion of the Al-based oxide particles in the catalyst layer 20 is contained in the first layer 21.
  • a portion of the Al-based oxide particles in the catalyst layer 20 may be contained in the first layer 21, or all of the Al-based oxide particles in the catalyst layer 20 may be contained in the first layer 21.
  • first layer 21 and the second layer 22 it is preferable that at least the first layer 21 contributes to the desired first peak value and second peak value.
  • the second layer 22 may also contribute to the desired first peak value and second peak value.
  • the first layer 21 is provided on the cell 13 side surface of the partition section 12.
  • the meaning of "cell 13 side surface of the partition section 12" is as described above.
  • the first layer 21 may be provided directly on the cell 13 side surface of the partition section 12 or may be provided via another layer, but is usually provided directly on the cell 13 side surface of the partition section 12.
  • the first layer 21 extends along the exhaust gas flow direction X from the end of the partition section 12 on the exhaust gas inlet side to the end of the partition section 12 on the exhaust gas outlet side.
  • the first layer 21 may extend along the exhaust gas flow direction X from the end of the partition section 12 on the exhaust gas inlet side so as not to reach the end of the partition section 12 on the exhaust gas outlet side, or may extend in the opposite direction to the exhaust gas flow direction X from the end of the partition section 12 on the exhaust gas outlet side so as not to reach the end of the partition section 12 on the exhaust gas inlet side.
  • the mass of the first layer 21 per unit volume of the portion of the substrate 10 where the first layer 21 is provided is preferably 100 g/L or more and 180 g/L or less, more preferably 110 g/L or more and 160 g/L or less, and even more preferably 120 g/L or more and 150 g/L or less.
  • the mass of the first layer 21 per unit volume of the portion of the substrate 10 where the first layer 21 is provided is calculated from the formula: (mass of the first layer 21)/((volume of the substrate 10) ⁇ (average length L21 of the first layer 21 /length L10 of the substrate 10 )).
  • catalyst layer 20 is read as “first layer 21.”
  • the sample is cut at 5 mm intervals along a plane perpendicular to the axial direction of the substrate 10, and the first cut piece, second cut piece, ..., nth cut piece are obtained in order from the end of the sample on the exhaust gas outlet side.
  • Ce-based oxide particles preferably means Ce-based oxide particles that are favorable for achieving the desired first and second peak values described above.
  • the content of Ce-based oxide particles in the first layer 21 is preferably 10% by mass or more and 80% by mass or less, more preferably 20% by mass or more and 70% by mass or less, and even more preferably 30% by mass or more and 60% by mass or less, based on the total mass of the Ce-based oxide particles and the Ce-Zr-based composite oxide particles in the first layer 21.
  • the content of the Ce-Zr based composite oxide particles in the first layer 21 is preferably 20% by mass or more and 90% by mass or less, more preferably 30% by mass or more and 80% by mass or less, and even more preferably 40% by mass or more and 70% by mass or less, based on the total mass of the Ce based oxide particles and the Ce-Zr based composite oxide particles in the first layer 21.
  • the total content of Ce-based oxide and Ce-Zr-based composite oxide particles in the first layer 21 is preferably 30% by mass or more and 80% by mass or less, more preferably 40% by mass or more and 70% by mass or less, and even more preferably 45% by mass or more and 65% by mass or less, based on the mass of the first layer 21.
  • the content of the Ce-Zr-based composite oxide particles in the first layer 21 is preferably 10% by mass or more and 80% by mass or less, more preferably 20% by mass or more and 70% by mass or less, and even more preferably 30% by mass or more and 60% by mass or less, based on the total mass of the Ce-based oxide particles, the Ce-Zr-based composite oxide particles, and the Al-based oxide particles in the first layer 21.
  • the total content of Ce-based oxide, Ce-Zr-based composite oxide particles, and Al-based oxide particles in the first layer 21 is preferably 50% by mass or more and 99% by mass or less, more preferably 60% by mass or more and 95% by mass or less, and even more preferably 70% by mass or more and 90% by mass or less, based on the mass of the first layer 21.
  • the second layer 22 is disposed on the first layer 21.
  • the second layer 22 is provided on the first layer 21 means that a part or all of the second layer 22 is present on the main surface opposite to the main surface on the partition wall 12 side, out of the two main surfaces of the first layer 21.
  • Main surface of the first layer 21 means the outer surface of the first layer 21 extending in the exhaust gas flow direction X.
  • the second layer 22 may be provided directly on the main surface of the first layer 21 or may be provided via another layer, but is usually provided directly on the main surface of the first layer 21.
  • the second layer 22 may be provided so as to cover a part of the main surface of the first layer 21 or may be provided so as to cover the entire main surface of the first layer 21.
  • the second layer 22 provided on the first layer 21 includes both an embodiment in which the second layer 22 is provided directly on the main surface of the first layer 21 and an embodiment in which the second layer 22 is provided on the main surface of the first layer 21 via another layer.
  • the second layer 22 extends along the exhaust gas flow direction X from the end of the partition section 12 on the exhaust gas inlet side to the end of the partition section 12 on the exhaust gas outlet side.
  • the second layer 22 may extend along the exhaust gas flow direction X from the end of the partition section 12 on the exhaust gas inlet side so as not to reach the end of the partition section 12 on the exhaust gas outlet side, or may extend in the opposite direction to the exhaust gas flow direction X from the end of the partition section 12 on the exhaust gas outlet side so as not to reach the end of the partition section 12 on the exhaust gas inlet side.
  • the mass of the second layer 22 per unit volume of the portion of the substrate 10 where the second layer 22 is provided is preferably 50 g/L or more and 140 g/L or less, more preferably 55 g/L or more and 120 g/L or less, and even more preferably 60 g/L or more and 100 g/L or less.
  • the mass of the second layer 22 per unit volume of the portion of the substrate 10 where the second layer 22 is provided is calculated from the formula: (mass of the second layer 22)/((volume of the substrate 10) ⁇ (average length L22 of the second layer 22 /length L10 of the substrate 10 )).
  • the sample is cut at 5 mm intervals along a plane perpendicular to the axial direction of the substrate 10, and the first cut piece, second cut piece, ..., nth cut piece are obtained in order from the end of the sample on the exhaust gas outlet side.
  • the second layer 22 contains one or more precious metal elements. As described above, the precious metal elements in the second layer 22 correspond to at least a portion of the precious metal elements in the catalyst layer 20.
  • the content of the precious metal element in the second layer 22 in terms of metal conversion is preferably 0.010 mass% or more and 20 mass% or less, more preferably 0.050 mass% or more and 10 mass% or less, and even more preferably 0.10 mass% or more and 5.0 mass% or less, based on the mass of the second layer 22.
  • the content of the precious metal element in terms of metal conversion in the second layer 22 means the content of the one precious metal element in terms of metal conversion when the second layer 22 contains one type of precious metal element, and means the total content of the two or more precious metal elements in terms of metal conversion when the second layer 22 contains two or more types of precious metal elements.
  • the metal-equivalent content of the precious metal elements in the second layer 22 can be measured in the same manner as the metal-equivalent content of the precious metal elements in the catalyst layer 20.
  • the second layer 22 preferably includes one or more carriers, and at least a portion of the catalytically active component including the precious metal element is supported on one or more carriers.
  • the meaning of "at least a portion of the catalytically active component is supported on a carrier" and the method of confirmation are the same as above.
  • the carrier can be selected from inorganic oxides, for example.
  • the inorganic oxide is, for example, particulate. From the viewpoint of improving the supportability of the catalytically active component, it is preferable that the inorganic oxide is porous.
  • the inorganic oxide may or may not have oxygen storage capacity (OSC: Oxygen Storage Capacity).
  • OSC Oxygen Storage Capacity
  • an inorganic oxide having OSC may be referred to as an "OSC material.”
  • the inorganic oxide used as a carrier is distinguished from the inorganic oxide used as a binder (for example, inorganic oxide-based binders such as alumina binder, zirconia binder, titania binder, and silica binder).
  • inorganic oxides include Ce-based oxides, Ce-Zr-based composite oxides, Al-based oxides, oxides of rare earth elements other than Ce, oxides based on zirconia (ZrO 2 ), silica (SiO 2 ), titania (TiO 2 ), zeolite (aluminosilicate), MgO, ZnO, SnO 2, etc.
  • the Ce-based oxides, Ce-Zr-based composite oxides, and Al-based oxides are as described above.
  • the Ce-based oxide particles may be Ce-based oxide particles that are preferable for achieving the desired first and second peak values described above, or may be other Ce-based oxide particles.
  • the catalyst 1 can be produced by forming a catalyst layer 20 on a substrate 10 .
  • the catalyst layer 20 can be formed by mixing a source of precious metal elements (e.g., salts of precious metal elements), Ce-based oxide particles as raw materials, Ce-Zr-based composite oxide as raw materials, optionally Al-based oxide particles as raw materials, and optionally other components (e.g., binder, solvent, etc.) to prepare a slurry, applying the slurry onto the substrate 10, drying, and firing.
  • a source of precious metal elements e.g., salts of precious metal elements
  • Ce-based oxide particles as raw materials
  • Ce-Zr-based composite oxide as raw materials
  • Al-based oxide particles optionally other components
  • the catalyst layer 20 includes a first layer 21 and a second layer 22, the catalyst 1 can be manufactured by forming the first layer 21 on the substrate 10 and then forming the second layer 22 on the upper side of the first layer 21.
  • the first layer 21 can be formed by mixing Ce-based oxide particles as raw materials, Ce-Zr-based composite oxide as raw materials, and optionally Al-based oxide particles as raw materials, and optionally other components (e.g., binder, solvent, etc.) to prepare a first slurry, applying the first slurry onto the substrate 10, drying, and firing.
  • Ce-based oxide particles as raw materials
  • Ce-Zr-based composite oxide as raw materials
  • Al-based oxide particles as raw materials
  • other components e.g., binder, solvent, etc.
  • the second layer 22 can be formed by mixing a source of precious metal elements and, optionally, other components (e.g., inorganic oxides, binders, solvents, etc.) to prepare a second slurry, applying the second slurry onto the first layer 21, drying, and firing.
  • other components e.g., inorganic oxides, binders, solvents, etc.
  • Sources of precious metal elements include, for example, salts of precious metal elements, such as nitrates, ammine complex salts, acetates, and chlorides.
  • Binders include, for example, alumina sol, zirconia sol, titania sol, silica sol, and ceria sol.
  • Solvents include, for example, water, organic solvents, and the like.
  • the drying temperature is, for example, 70°C or higher and 150°C or lower, and the drying time is, for example, 5 minutes or longer and 1 hour or shorter.
  • the firing temperature is, for example, 200°C or higher and 700°C or lower, and the firing time is, for example, 0.5 hours or longer and 5 hours or shorter.
  • the firing can be carried out, for example, in an air atmosphere.
  • the heat load can be performed, for example, by firing at 1000 ° C. for 1 hour under an air atmosphere.
  • the CeO2 crystallite size in the Ce-based oxide particles as a raw material is preferably 6 nm or more, more preferably 10 nm or more, even more preferably 20 nm or more, and even more preferably 30 nm or more.
  • the upper limit of the CeO2 crystallite size in the Ce-based oxide particles as a raw material is, for example, 200 nm, preferably 100 nm, more preferably 55 nm. Each of these upper limits may be combined with any of the above lower limits.
  • the method for measuring the CeO2 crystallite size in the Ce-based oxide particles as a raw material is the same as the method for measuring the CeO2 crystallite size in the Ce-based oxide particles, except that the measurement is performed using the Ce-based oxide particles as a raw material.
  • the specific surface area of the Ce-based oxide particles as the raw material is preferably 100 m 2 /g or more and 200 m 2 /g or less, more preferably 120 m 2 /g or more and 180 m 2 /g or less, and even more preferably 130 m 2 /g or more and 160 m 2 /g or less.
  • the specific surface area of the Ce-based oxide particles as the raw material can be measured by N 2 gas adsorption method using powdered Ce-based oxide particles and QUADRASORB SI manufactured by Quantachrome.
  • the specific surface area of the Ce-based oxide particles contained in the slurry is preferably 60 m 2 /g or more and 160 m 2 /g or less, more preferably 70 m 2 /g or more and 140 m 2 /g or less, and even more preferably 80 m 2 /g or more and 120 m 2 /g or less.
  • the specific surface area of the Ce-based oxide particles contained in the slurry can be measured by N 2 gas adsorption method using a slurry containing Ce-based oxide particles and QUADRASORB SI manufactured by Quantachrome.
  • the slurry containing Ce-based oxide particles can be prepared by mixing water and Ce-based oxide particles.
  • the specific surface area of the Ce-based oxide particles contained in the slurry is preferably measured in a state in which the slurry does not contain Ce-Zr composite oxide particles, Al-based oxide particles, and binder.
  • Example 1 Formation and analysis of the first layer (1-1) Preparation of Ce-based oxide particles, Ce-Zr-based composite oxide particles, and Al-based oxide particles Ce-based oxide particles were prepared.
  • Ce-Zr based composite oxide particles were prepared.
  • the Ce content in terms of CeO2 was 20 mass%
  • the Zr content in terms of ZrO2 was 70 mass%
  • the Nd content in terms of Nd2O3 was 10 mass%.
  • Al-based oxide particles were prepared.
  • the content of Al in terms of Al 2 O 3 was 99 mass %
  • the content of La in terms of La 2 O 3 was 1 mass %.
  • the measurement was performed twice using pure water as the aqueous dispersion medium, with 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, and the average value of the obtained measured values was adopted as the median diameter of the measurement sample.
  • the median diameter of the Ce-based oxide particles measured in this way was 5.0 ⁇ m.
  • the median diameter of the Al-based oxide particles was measured under the same conditions as for the median diameter of the Ce-based oxide particles.
  • the median diameter of the Al-based oxide particles was 19 ⁇ m.
  • CeO2 crystallite size in Ce-based oxide particles was measured as follows.
  • X-ray diffraction (XRD) was performed using Ce-based oxide particles and a commercially available powder X-ray diffractometer (Rigaku Corporation's "MiniFlex600" under the following conditions: X-ray source: CuK ⁇ , operation axis: 2 ⁇ / ⁇ , measurement method: continuous, counting unit: cps, start angle: 5°, end angle: 90°, sampling width: 0.02°, scan speed: 10°/min, voltage: 40 kV, current: 150 mA.
  • XRD X-ray diffraction
  • the CeO2 crystallite size in the Ce-based oxide particles was 6.6 nm.
  • the specific surface area of the Ce-based oxide particles contained in the slurry was measured by N2 gas adsorption method using QUADRASORB SI manufactured by Quantachrome.
  • the slurry containing Ce-based oxide particles was prepared by putting water and Ce-based oxide particles into a mixing vessel and mixing the water and Ce-based oxide particles.
  • the specific surface area of the Ce-based oxide particles contained in the slurry was measured in a state in which the slurry did not contain Ce-Zr composite oxide particles, Al-based oxide particles, or binder.
  • the specific surface area of the Ce-based oxide particles contained in the slurry was 84 m2 /g.
  • the amounts of each component in the slurry for forming the first layer were adjusted so that, based on the mass of the first layer after firing (100 mass%), the Ce-based oxide particles were 18.5 mass%, the Ce-Zr-based composite oxide particles were 43.1 mass%, the Al-based oxide particles were 26.5 mass%, and the remainder was the binder.
  • the metal honeycomb substrate was immersed in the slurry for forming the first layer, and the metal honeycomb substrate coated with the slurry for forming the first layer was dried at 80°C for 1 hour, and then fired at 450°C for 1 hour to form the first layer.
  • the mass of the first layer per unit volume of the portion of the metal honeycomb substrate where the first layer was provided was 120 g/L.
  • the amount of each component in the slurry for forming the second layer was adjusted so that palladium was 0.2 mass% in terms of metal, Ce-Zr based composite oxide particles were 87.8 mass%, and the remainder was binder, based on the mass of the second layer after firing (100 mass%).
  • an exhaust gas purification catalyst that includes a metal honeycomb substrate and a catalyst layer provided on the metal honeycomb substrate, the catalyst layer including a first layer provided on the metal honeycomb substrate and a second layer provided on the first layer.
  • Example 2 An exhaust gas purifying catalyst was produced by the same operation as in Example 1, except that the amounts of the components in the first layer-forming slurry were adjusted so that, based on the mass of the fired first layer (100 mass%), the Ce-based oxide particles were 30.8 mass%, the Ce-Zr-based composite oxide particles were 30.8 mass%, the Al-based oxide particles were 26.5 mass%, and the remainder was the binder.
  • Example 3 An exhaust gas purifying catalyst was produced by the same operation as in Example 1, except that the amounts of the components in the first layer-forming slurry were adjusted so that, based on the mass of the fired first layer (100 mass%), the Ce-based oxide particles were 43.1 mass%, the Ce-Zr-based composite oxide particles were 18.5 mass%, the Al-based oxide particles were 26.5 mass%, and the remainder was the binder.
  • Example 4 The same Ce-based oxide particles, Ce-Zr-based composite oxide particles, Al-based oxide particles, and metal honeycomb substrate as those in Example 1 were prepared.
  • the amount of each component in the slurry for forming a catalyst layer was adjusted so that, based on the mass of the catalyst layer after firing (100 mass%), palladium was 0.2 mass% in metal equivalent, platinum was 0.2 mass% in metal equivalent, rhodium was 0.1 mass% in metal equivalent, Ce-based oxide particles were 18.7 mass%, Ce-Zr-based composite oxide particles were 45.3 mass%, Al-based oxide particles were 22.7 mass%, and the remainder was binder.
  • the metal honeycomb substrate was immersed in the catalyst layer forming slurry, and the metal honeycomb substrate coated with the catalyst layer forming slurry was dried at 80°C for 1 hour, and then fired at 450°C for 1 hour to form the catalyst layer.
  • the mass of the catalyst layer per unit volume of the portion of the metal honeycomb substrate where the catalyst layer was provided was 140 g/L.
  • an exhaust gas purification catalyst that includes a metal honeycomb substrate and a catalyst layer provided on the metal honeycomb substrate, the catalyst layer being a single layer.
  • Example 5 An exhaust gas purifying catalyst was produced by the same operation as in Example 4, except that the amount of each component in the catalyst layer forming slurry was adjusted so that, based on the mass of the catalyst layer after firing (100 mass%), platinum was 0 mass% in metal conversion (i.e., platinum nitrate was not added when preparing the catalyst layer forming slurry), palladium was 0.05 mass% in metal conversion, rhodium was 0.08 mass% in metal conversion, Ce-based oxide particles were 18.7 mass%, Ce-Zr-based composite oxide particles were 45.4 mass%, Al-based oxide particles were 22.7 mass%, and the remainder was binder.
  • Comparative Example 1 An exhaust gas purifying catalyst was produced by carrying out the same operation as in Example 1, except that the amount of each component in the first layer forming slurry was adjusted so that, based on the mass of the first layer after firing (100 mass%), the Ce-based oxide particles were 0 mass% (i.e., no Ce-based oxide particles were added when preparing the first layer forming slurry), the Ce-Zr-based composite oxide particles were 61.5 mass%, the Al-based oxide particles were 26.5 mass%, and the remainder was the binder.
  • Comparative Example 2 An exhaust gas purifying catalyst was produced by carrying out the same operation as in Example 1, except that the amounts of each component in the first layer forming slurry were adjusted so that, based on the mass of the fired first layer (100 mass%), the Ce-based oxide particles were 61.5 mass%, the Ce-Zr-based composite oxide particles were 0 mass% (i.e., Ce-Zr-based composite oxide particles were not added when preparing the first layer forming slurry), the Al-based oxide particles were 26.5 mass%, and the remainder was the binder.
  • Comparative Example 3 An exhaust gas purifying catalyst was produced by the same operation as in Example 4, except that the amount of each component in the catalyst layer forming slurry was adjusted so that, based on the mass of the catalyst layer after firing (100 mass%), palladium was 0.2 mass% in metal conversion, platinum was 0.2 mass% in metal conversion, rhodium was 0.1 mass% in metal conversion, Ce-based oxide particles were 0 mass% (i.e., Ce-based oxide particles were not added when preparing the catalyst layer forming slurry), Ce-Zr-based composite oxide particles were 45.3 mass%, Al-based oxide particles were 45.3 mass%, and the remainder was binder.
  • Comparative Example 4 An exhaust gas purifying catalyst was produced by performing the same operation as in Comparative Example 3, except that the amount of each component in the catalyst layer forming slurry was adjusted so that, based on the mass of the catalyst layer after firing (100 mass%), platinum was 0 mass% in metal conversion (i.e., platinum nitrate was not added when preparing the catalyst layer forming slurry), palladium was 0.05 mass% in metal conversion, rhodium was 0.08 mass% in metal conversion, Ce-based oxide particles were 0 mass% (i.e., Ce-based oxide particles were not added when preparing the catalyst layer forming slurry), Ce-Zr-based composite oxide particles were 45.4 mass%, Al-based oxide particles were 45.4 mass%, and the remainder was binder.
  • platinum was 0 mass% in metal conversion (i.e., platinum nitrate was not added when preparing the catalyst layer forming slurry)
  • palladium was 0.05 mass% in metal conversion
  • rhodium was 0.08 mass% in metal
  • the cut piece M1 was obtained by cutting two places, 10 mm and 30 mm away from the exhaust gas inlet side end of the substrate in the exhaust gas flow direction X, along a plane perpendicular to the axial direction of the substrate.
  • the cut piece M1 has a rectangular parallelepiped shape with a cross section of 10 mm long x 10 mm wide and a length of 20 mm.
  • the logarithmic differential pore volume distribution of the catalyst layer was measured by mercury intrusion porosimetry using the cut pieces M1 cut from each of the exhaust gas purification catalysts of Examples 1 to 4 and Comparative Examples 1 to 3, and the logarithmic differential pore volume distribution curve of the catalyst layer was obtained.
  • the specific measurement conditions are as follows.
  • the exhaust gas purification catalysts of Examples 4 and 5 differ in terms of the metal-equivalent contents of platinum, palladium, and rhodium, but are identical in terms of the contents of Ce-based oxide particles, Ce-Zr-based composite oxide particles, and Al-based oxide particles. Therefore, it is presumed that the first peak value, the second peak value, and the position of the second peak value in Example 5 are similar to those in Example 4.
  • the exhaust gas purification catalysts of Comparative Examples 3 and 4 differ in terms of the metal-equivalent contents of platinum, palladium, and rhodium, but are identical in terms of the contents of Ce-based oxide particles, Ce-Zr-based composite oxide particles, and Al-based oxide particles. Therefore, it is presumed that the first peak value, the second peak value, and the position of the second peak value of Comparative Example 4 are similar to those of Comparative Example 3.
  • the exhaust gas purification catalysts of Examples 4 and 5 differ in terms of the metal-equivalent contents of platinum, palladium, and rhodium, but are the same in terms of the contents of Ce-based oxide particles, Ce-Zr-based composite oxide particles, and Al-based oxide particles. Therefore, it is presumed that the specific surface area of Example 5 is similar to that of Example 4.
  • the exhaust gas purification catalysts of Comparative Examples 3 and 4 differ in terms of the metal-equivalent contents of platinum, palladium, and rhodium, but are identical in terms of the contents of Ce-based oxide particles, Ce-Zr-based composite oxide particles, and Al-based oxide particles. Therefore, it is presumed that the specific surface area of Comparative Example 4 is similar to that of Comparative Example 3.
  • the exhaust gas purification catalyst of Example 4 was placed on the upstream side of the exhaust passage of the muffler of a motorcycle, and the exhaust gas purification catalyst of Example 5 was placed on the downstream side, and the emissions (g/km) of carbon monoxide (CO), hydrocarbons (HC), non-methane hydrocarbons (NMHC), and nitrogen oxides (NOx) were measured. The measurements were performed under the same conditions as above, except that the vehicle used was changed to a single-cylinder 100cc motorcycle.
  • the exhaust gas purification catalyst of Comparative Example 3 was placed on the upstream side of the exhaust passage of the muffler of the motorcycle, and the exhaust gas purification catalyst of Comparative Example 4 was placed on the downstream side, and the same measurements as above were performed. The results are shown in 4.
  • the exhaust gas purification catalysts of Examples 4 and 5 differ in terms of the metal-equivalent contents of platinum, palladium, and rhodium, but are the same in terms of the contents of Ce-based oxide particles, Ce-Zr-based composite oxide particles, and Al-based oxide particles.
  • the T50 for CO, HC, and NOx for each of the exhaust gas purification catalysts in Examples 1 to 3 and Comparative Examples 1 and 2 was evaluated using the following evaluation criteria.

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Abstract

Le but de la présente invention est de fournir un catalyseur d'épuration de gaz d'échappement avec lequel il est possible de réaliser une diffusion de gaz d'échappement améliorée et une réactivité améliorée avec un gaz d'échappement diffusé. Afin d'atteindre le but, la présente invention concerne un catalyseur d'épuration de gaz d'échappement (1) comprenant un matériau de base en nid d'abeilles métallique (10) et une couche de catalyseur (20) disposée sur le matériau de base en nid d'abeilles métallique (10). La couche de catalyseur (20) contient un élément de métal noble, des particules d'oxyde à base de Ce et des particules d'oxyde composite à base de Ce-Zr. Une courbe de distribution de volume de pore différentiel logarithmique de la couche de catalyseur (20) obtenue par un procédé d'intrusion de mercure montre une première valeur de pic dans la plage de diamètre de pore de 5 nm à 15 nm et une seconde valeur de pic dans la plage de diamètre de pore de 200 nm à 3200 nm, la première valeur de pic étant de 0,060 mL/g ou plus, et la seconde valeur de pic étant de 0,018 mL/g ou plus.
PCT/JP2024/026778 2023-07-31 2024-07-26 Catalyseur d'épuration de gaz d'échappement Pending WO2025028434A1 (fr)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2016092957A1 (fr) * 2014-12-12 2016-06-16 本田技研工業株式会社 Catalyseur de purification de gaz d'échappement
WO2020100831A1 (fr) * 2018-11-12 2020-05-22 ユミコア日本触媒株式会社 Catalyseur de purification de gaz d'échappement de moteur à essence, procédé de production de catalyseur, et procédé de purification de gaz d'échappement dans lequel celui-ci est utilisé
WO2022209532A1 (fr) * 2021-03-30 2022-10-06 三井金属鉱業株式会社 Composition de catalyseur pour la purification de gaz d'échappement et catalyseur pour la purification de gaz d'échappement

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2016092957A1 (fr) * 2014-12-12 2016-06-16 本田技研工業株式会社 Catalyseur de purification de gaz d'échappement
WO2020100831A1 (fr) * 2018-11-12 2020-05-22 ユミコア日本触媒株式会社 Catalyseur de purification de gaz d'échappement de moteur à essence, procédé de production de catalyseur, et procédé de purification de gaz d'échappement dans lequel celui-ci est utilisé
WO2022209532A1 (fr) * 2021-03-30 2022-10-06 三井金属鉱業株式会社 Composition de catalyseur pour la purification de gaz d'échappement et catalyseur pour la purification de gaz d'échappement

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