WO2024008078A1 - Article catalytique pour traitement de gaz d'échappement de moteur - Google Patents

Article catalytique pour traitement de gaz d'échappement de moteur Download PDF

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Publication number
WO2024008078A1
WO2024008078A1 PCT/CN2023/105720 CN2023105720W WO2024008078A1 WO 2024008078 A1 WO2024008078 A1 WO 2024008078A1 CN 2023105720 W CN2023105720 W CN 2023105720W WO 2024008078 A1 WO2024008078 A1 WO 2024008078A1
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Prior art keywords
catalyst coating
component
coating layer
catalytic article
pore
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PCT/CN2023/105720
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English (en)
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WO2024008078A9 (fr
Inventor
Nating YANG
Min JIN
Xiaoshuang YANG
Chenghao Sun
Shau Lin CHEN
Juncong JIANG
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Basf Corporation
Basf (China) Company Limited
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Publication of WO2024008078A1 publication Critical patent/WO2024008078A1/fr
Publication of WO2024008078A9 publication Critical patent/WO2024008078A9/fr

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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
    • 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
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/92—Chemical or biological purification of waste gases of engine exhaust gases
    • B01D53/94—Chemical or biological purification of waste gases of engine exhaust gases by catalytic processes
    • B01D53/9445—Simultaneously removing carbon monoxide, hydrocarbons or nitrogen oxides making use of three-way catalysts [TWC] or four-way-catalysts [FWC]
    • B01D53/945—Simultaneously removing carbon monoxide, hydrocarbons or nitrogen oxides making use of three-way catalysts [TWC] or four-way-catalysts [FWC] characterised by a specific catalyst
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/50—Catalysts, in general, characterised by their form or physical properties characterised by their shape or configuration
    • B01J35/56—Foraminous structures having flow-through passages or channels, e.g. grids or three-dimensional monoliths
    • B01J35/57—Honeycombs
    • 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
    • B01J35/63—Pore volume
    • 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
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/02—Impregnation, coating or precipitation
    • B01J37/0215—Coating
    • B01J37/0219—Coating the coating containing organic compounds
    • 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
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/02—Impregnation, coating or precipitation
    • B01J37/024—Multiple impregnation or coating
    • B01J37/0244—Coatings comprising several layers
    • 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
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/02—Impregnation, coating or precipitation
    • B01J37/024—Multiple impregnation or coating
    • B01J37/0248—Coatings comprising impregnated particles
    • 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
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/02—Impregnation, coating or precipitation
    • B01J37/03—Precipitation; Co-precipitation
    • B01J37/038—Precipitation; Co-precipitation to form slurries or suspensions, e.g. a washcoat
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/10—Noble metals or compounds thereof
    • B01D2255/102—Platinum group metals
    • B01D2255/1021—Platinum
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/10—Noble metals or compounds thereof
    • B01D2255/102—Platinum group metals
    • B01D2255/1025—Rhodium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/20—Metals or compounds thereof
    • B01D2255/204—Alkaline earth metals
    • B01D2255/2042—Barium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/40—Mixed oxides
    • B01D2255/407—Zr-Ce mixed oxides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/90—Physical characteristics of catalysts
    • B01D2255/902—Multilayered catalyst
    • B01D2255/9022—Two layers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/90—Physical characteristics of catalysts
    • B01D2255/908—O2-storage component incorporated in the catalyst
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/90—Physical characteristics of catalysts
    • B01D2255/92—Dimensions
    • B01D2255/9205—Porosity

Definitions

  • the present invention relates to a three-way conversion catalytic article useful for treatment of engine exhaust gases and an exhaust treatment system comprising the catalytic article.
  • the present invention relates to a catalytic article useful for treatment of exhaust gases from stoichiometric engines, especially saddle-riding type vehicle engines.
  • Engine exhaust substantially consists of particulate matter and gaseous pollutants such as unburned hydrocarbons (HC) , carbon monoxide (CO) and nitrogen oxides (NOx) .
  • HC unburned hydrocarbons
  • CO carbon monoxide
  • NOx nitrogen oxides
  • TWC catalysts three-way conversion catalysts
  • TWC catalysts are known effective near stoichiometric conditions, under which the basic reactions including reduction and oxidation may be exemplified as follows,
  • TWC catalysts generally utilize one or more platinum group metals (PGMs) , e.g., rhodium (Rh) , platinum (Pt) , palladium (Pd) , ruthenium (Ru) , osmium (Os) and iridium (Ir) , as catalytically active species, which are typically supported on support particles of a refractory metal oxide and/or an oxygen storage capacity (OSC) material.
  • PGMs platinum group metals
  • Rh platinum group metals
  • platinum platinum
  • Pt platinum
  • Pd palladium
  • Ru ruthenium
  • Ru osmium
  • Ir iridium
  • the support particles carrying the PGMs are generally coated on a ceramic or metallic honeycomb substrate to provide a TWC catalytic article.
  • the TWC catalytic article may have a single coating layer or multiple different coating layers of TWC catalysts.
  • a TWC catalytic article for saddle-riding-type vehicle particularly needs to exert high purification capacity since such a catalytic article has a small volume capacity due to the limited space for the catalytic article to be mounted, suffers a rapid atmospheric variation, and is easily exposed to a high temperature.
  • the TWC catalytic article have a single thick coating layer or multiple coating layers, it is difficult for the exhaust gas to diffuse into the interior part of the catalyst coating close to the substrate side.
  • the exhaust gas hardly diffuses to the deep part of the catalyst coating and thus the catalyst performance cannot be sufficiently brought out.
  • WO2015/037613A discloses an exhaust gas purifying catalyst comprising a catalyst layer comprising two or more types of inorganic porous particles each having a different particle size, a catalytically active component and voids, wherein as a first characteristic, the voids satisfying a condition of L/2/ ( ⁇ S) 1/2 ⁇ 2 occupy 50%or more by number of all the voids in the catalyst layer wherein S represents a void cross-sectional area, and L represents a void cross-sectional circumference; and as a second characteristic, in the void cross-sectional area in the catalyst layer, an average void radius, determined assuming that the void shape is a perfect circle, is 10 ⁇ m to 20 ⁇ m. It is described that the miscibility and diffusibility of the gas in the catalyst layer are improved and thereby excellent purifying performance can be exhibited.
  • US2017/0232425A1 discloses an exhaust gas purifying catalyst having a first catalyst layer which is formed on a surface of a substrate and a second catalyst layer which is formed on the upper side of the first catalyst layer, wherein the first catalyst layer comprises a precious metal, an OSC material and an alumina, and the OSC material and the alumina are comprised at a mass ratio of OSC material to alumina in the range of from 1 : 7 to 1 : 3, and the second catalyst layer comprises a precious metal, an OSC material and an alumina, and the OSC material and the alumina are comprised at a mass ratio of OSC material to alumina in the range of from 1 : 1 to 10 : 0, and wherein an average particle size (D 50 ) of the alumina in the first catalyst layer is 10 to 16 ⁇ m, and an average particle size (D 50 ) of the OSC material in the first catalyst layer is 3 to 12 ⁇ m.
  • the first catalyst layer comprises a precious metal, an OSC material and an a
  • the gas diffusibility in the catalyst layer can be improved, the catalytic activity is rarely reduced, and the entire catalyst layer can be effectively utilized even in an internal-combustion engine which is used under an exhaust gas atmosphere where it is exposed to high temperature exhaust gas, and where a space velocity of the passed exhaust gas is extremely high.
  • WO2013118425A1 discloses a porous apatite catalyst layer containing apatite, in which a peak top is present within a void volume diameter range of from 100 nm to 1000 nm in logarithmic differentiation void volume distribution measured by a mercury intrusion porosimeter. It is described that a new catalyst structure is provided which is capable of maintaining gas diffusivity to a deep part of a catalyst layer even under condition that a gas flow rate is high.
  • WO2014156676A1 discloses a catalyst structure including a substrate, an upper catalyst layer, and a lower catalyst layer, the catalyst structure having a first peak or a second peak at a pore volume diameter of 10 nm to 50 nm and a pore volume diameter of 50 nm to 100 nm, respectively, in the logarithmic differential pore volume distribution analyzed by mercury intrusion porosimetry. It is described that the catalyst structure can increase gas diffusibility to the deep part of the catalyst layer and can sufficiently exhibit a function as a three-way catalyst.
  • a catalytic article comprising a PGM-based catalyst coating layer having interparticle pores of micrometer and nanometer levels on a substrate.
  • the present invention provides a catalytic article, especially a TWC catalytic article, comprising a catalyst coating on a substrate, wherein the catalyst coating comprises at least one catalyst coating layer comprising a platinum group metal component in supported form and has a pore volume distribution such that a peak top of pore volume diameter of nano level is present in the range of from 90.0 nm to 140.0 nm and a peak top of pore volume diameter of micron level in present in the range of from 5.5 ⁇ m to 10.0 ⁇ m, in a logarithmic differential pore volume distribution as determined by mercury intrusion porosimetry.
  • the present invention provides a process for preparing the catalytic article as described in the first aspect, which comprises
  • the pore-forming agent is in form of particles and used in an amount of at least 0.5%by weight, based on the loading of the catalyst coating layer as formed.
  • the present invention provides an exhaust treatment system comprising the catalytic article as described herein located downstream of a stoichiometric engine, particularly a gasoline engine such as a saddle-riding-type vehicle engine.
  • Figures 1A and 1B show logarithmic differential pore volume distribution of samples S1 to S4 as described in Examples.
  • Figures 2A and 2B show logarithmic differential pore volume distribution of samples S5 to S8 as described in Examples.
  • platinum group metal component As used herein, the terms “platinum group metal component” , “palladium component” , “platinum component” and “rhodium component” are intended to describe the presence of respective platinum group metal in any possible valence state, which may be for example metal or metal oxide as the catalytically active form, or may be for example metal compound, complex or the like which, upon calcination or use of the catalyst, decomposes or otherwise converts to the catalytically active form.
  • support refers to a material in form of particles for receiving and carrying one or more platinum group metal (PGM) components, and optionally one or more other components such as stabilizers, promoters and binders.
  • PGM platinum group metal
  • any reference to a platinum group metal component in “supported form” is intended to mean that the platinum group metal component is supported on and/or in support particles.
  • any reference to an amount of loading in the unit of “g/ft 3 ” or “g/in 3 ” is intended to mean the weight of the specified component or coating layer per unit volume of the substrate or substrate part, on which they are carried.
  • the term “catalyst coating” refers to a catalyst-comprising covering which is deposited on the surfaces of walls of a substrate which define channels for exhaust stream passing through.
  • a catalyst coating may have a non-layered or layered configuration.
  • the catalyst coating consists of a single coating layer; for a layered configuation, the catalyst coating consists of two or more coating layers wherein at least one is a catalyst-comprising coating layer.
  • a coating layer may be prepared by repeating a coating step twice or more to attain a targeted loading and thus will comprise more than one sub-layer having the same chemical composition and catalytic activity which may be distinguishable only with SEM analysis.
  • Such a coating layer comprising more than one sub-layer having the same chemical composition and catalytic activity will be referred to a single or one coating layer. Accordingly, when two or more coating layers are referred to herein, the coating layers will have different chemical compositions or catalytic activities from each other.
  • catalyst coating layer particularly refers to a coating layer comprising a platinum group metal component in supported form.
  • exhaust As used herein, the terms “exhaust” , “exhaust gas” , “exhaust stream” and the like are used interchangeably with each other and refer to any engine effluents that may also contain particulate matter.
  • a catalytic article comprising a catalyst coating on a substrate
  • the catalyst coating comprises at least one catalyst coating layer comprising a platinum group metal component in supported form and has a pore volume distribution such that a peak top of pore volume diameter at nano level is present in the range of from 90.0 nm to 140.0 nm and a peak top of pore volume diameter at micron level is present in the range of from 5.5 ⁇ m to 10.0 ⁇ m, in a logarithmic differential pore volume distribution as determined by mercury intrusion porosimetry.
  • the catalyst coating of the catalytic article according to the present invention may comprise or consist of one catalyst coating layer comprising a platinum group metal component in supported form.
  • the catalyst coating of the catalytic article according to the present invention may comprise or consist of two catalyst coating layers comprising a platinum group metal component in supported form.
  • the catalyst coating of the catalytic article according to the present invention consists of a top catalyst coating layer comprising a first platinum group metal component in supported form and a bottom coating layer comprising a second platinum group metal component in supported form.
  • the catalyst coating of the catalytic article according to the present invention may comprise three or more coating layers wherein at least one, preferably two or more coating layers comprise a platinum group metal component in supported form.
  • the peak of pore volume diameter at nano level extends from 10 nm to 250 nm, and the peak of pore volume diameter at micron level extends from 1 to 22 ⁇ m, in a logarithmic differential pore volume distribution as measured by mercury intrusion porosimetry.
  • the PGM component may be a rhodium (Rh) component, a platinum (Pt) component, a palladium (Pd) component, a ruthenium (Ru) component, an osmium (Os) component, an iridium (Ir) component or any combinations thereof, among which a Pt component, a Pd component, a Rh component or any combinations thereof are usually used.
  • Rh platinum group metal
  • the PGM component may be a rhodium (Rh) component, a platinum (Pt) component, a palladium (Pd) component, a ruthenium (Ru) component, an osmium (Os) component, an iridium (Ir) component or any combinations thereof, among which a Pt component, a Pd component, a Rh component or any combinations thereof are usually used.
  • the catalyst coating of the catalytic article according to the present invention comprises the PGM component selected from a Rh component in combination with either or both of a Pt component and a Pd component.
  • the platinum group metal (PGM) components may be comprised in the same one catalyst coating layer in the catalytic article.
  • the PGM components may be arranged in different catalyst coating layers when the catalyst coating of the catalytic article comprises two or more catalyst coating layers comprising a PGM component in supported form.
  • the catalyst coating of the catalytic article comprises two catalyst coating layers comprising a PGM component in supported form, wherein one catalyst coating layer comprises a Rh component in supported form and optionally a Pt component in supported form as the PGM component, and the other catalyst coating layer comprises a Pt component in supported form and optionally a Pd component in supported from as the PGM component.
  • the catalyst coating of the catalytic article comprises or consists of a top catalyst coating layer comprising a PGM component in supported form and a bottom catalyst coating layer comprising a PGM component in supported form, wherein the top catalyst coating layer comprises a Rh component in supported form and optionally a Pt component in supported form as the PGM component, and the bottom catalyst coating layer comprises a Pt component in supported form and optionally a Pd component in supported from as the PGM component.
  • the catalyst coating of the catalytic article may comprise a top catalyst coating layer comprising a PGM component in supported form and a bottom catalyst coating layer comprising a PGM component in supported form, wherein the top catalyst coating layer comprises a Rh component in supported form as the PGM component, and the bottom catalyst coating layer comprises a Pt component in supported form as the PGM component.
  • the catalyst coating of the catalytic article may comprise a top catalyst coating layer comprising a PGM component in supported form and a bottom catalyst coating layer comprising a PGM component in supported form, wherein the top catalyst coating layer comprises a Rh component in supported form and a Pt component in supported form as the PGM component, and the bottom catalyst coating layer comprises a Pt component in supported form and a Pd component in supported from as the PGM component.
  • refractory metal oxides As useful support materials for the platinum group metal component in the catalytic article according to the present invention, refractory metal oxides, oxygen storage components and any combinations thereof may be mentioned.
  • the refractory metal oxide is generally a high surface area alumina-based material, zirconia-based material or a combination thereof.
  • alumina-based material refers to a material comprising alumina as a base and optionally a dopant.
  • zirconia-based material refers to a material comprising zirconia as a base and optionally a dopant.
  • Suitable examples of the alumina-based materials include, but are not limited to alumina, for example a mixture of the gamma and delta phases of alumina which may also contain substantial amounts of eta, kappa and theta alumina phases, lanthana doped alumina, baria doped alumina, ceria doped alumina, zirconia doped alumina, ceria-zirconia doped alumina, lanthana-zirconia doped alumina, baria-lanthana doped alumina, baria-ceria doped alumina, baria-zirconia doped alumina, baria-lanthana-neodymia doped alumina, lanthana-ceria doped alumina, and any combinations thereof.
  • alumina for example a mixture of the gamma and delta phases of alumina which may also contain substantial amounts of eta, kappa and theta a
  • zirconia-based materials include, but are not limited to zirconia, lanthana doped zirconia, yttria doped zirconia, neodymia doped zirconia, praseodymia doped zirconia, titania doped zirconia, titania-lanthana doped zirconia, lanthana-yttria doped zirconia, and any combinations thereof.
  • the refractory metal oxide useful as the support may be selected from baria doped alumina, lanthana doped alumina, ceria doped alumina, zirconia doped alumina, lanthana-zirconia doped alumina, lanthana doped zirconia, and any combinations thereof.
  • the amount of the refractory metal oxide is 10 to 90%by weight, if used, based on the total weight of a single coating layer.
  • the oxygen storage component refers to an entity that has a multi-valence state and can actively react with oxidants such as oxygen or nitrogen oxides under oxidative conditions or react with reductants such as carbon monoxide or hydrogen under reduction conditions.
  • the oxygen storage component comprises one or more reducible rare earth metal oxides, such as ceria.
  • the oxygen storage component may also comprise one or more of lanthana, praseodymia, neodymia, europia, samaria, ytterbia, yttria, zirconia and hafnia to constitute a composite oxide with ceria.
  • the oxygen storage component is selected from ceria-zirconia composite oxides and stabilized ceria-zirconia composite oxides.
  • the amount of oxygen storage component is from 15 to 85 %by weight, if used, based on the total weight of a single coating layer.
  • the support materials for different platinum group metal (PGM) components in the same catalyst coating layer may be the same or different. Also, the support materials for the same platinum group metal (PGM) component in different catalyst coating layers may be the same or different if two or more catalyst coating layers are comprised in the catalytic article according to the present invention. Further, more than one supports may be used for the same platinum group metal (PGM) component in one catalyst coating layer.
  • the catalytic article according to the present invention may comprise the catalyst coating layer (s) comprising a platinum group metal component in supported form at a loading in the range of from 0.1 to 15.0 g/in 3 , or from 0.5 to 10.0 g/in 3 , or from 1.0 to 4.0 g/in 3 .
  • the loading as described here refers to sum of all of such catalyst coating layers.
  • the catalyst coating layer (s) comprising a platinum group metal component in supported form as described herein may comprise the PGM component at a total loading in the range of from 0.5 to 100.0 g/ft 3 , or from 1.0 to 60.0 g/ft 3 , or from 5.0 to 20.0 g/ft 3 , calculated as respective PGM elements.
  • the catalyst coating layer (s) may optionally comprise a stabilizer and/or a promoter as desired.
  • Suitable stabilizer includes non-reducible oxides of metals selected from the group consisting of barium, calcium, magnesium, strontium and any combinations thereof.
  • barium oxide and magnesium oxide are used as the stabilizer.
  • Suitable promoter includes non-reducible oxides of rare earth metals selected from the group consisting of lanthanum, praseodymium, yttrium, cerium, tungsten, neodymium, gadolinium, samarium, hafnium and any combination thereof.
  • the catalyst coating having the pore volume distribution as described herein may extend along the entire length of the walls of the substrate, or along only a part of the length of the porous walls of the substrate.
  • Metallic materials useful for constructing the substrate may include heat resistant metals and metal alloys such as titanium and stainless steel as well as other alloys in which iron is a substantial or major component.
  • Such alloys may contain one or more nickel, chromium, and/or aluminium, and the total amount of these metals may advantageously comprise at least 15%by weight of the alloy, for example 10 to 25%by weight of chromium, 3 to 8%by weight of aluminium, and up to 20%by weight of nickel.
  • the alloys may also contain small or trace amounts of one or more metals such as manganese, copper, vanadium, titanium and the like.
  • the surface of the metallic substrate may be oxidized at high temperature, e.g., 1000 °C or higher, to form an oxide layer on the surface of the substrate, improving the corrosion resistance of the alloy and facilitating adhesion of the washcoat layer to the metal surface.
  • Ceramic materials useful for constructing the substrate may include any suitable refractory material, e.g., cordierite, mullite, cordierite-alumina, silicon nitride, zircon mullite, spodumene, alumina-silica-magnesia, zircon silicate, sillimanite, magnesium silicates, zircon, petalite, alumina, and aluminosilicates.
  • suitable refractory material e.g., cordierite, mullite, cordierite-alumina, silicon nitride, zircon mullite, spodumene, alumina-silica-magnesia, zircon silicate, sillimanite, magnesium silicates, zircon, petalite, alumina, and aluminosilicates.
  • a flow-through substrate which has a plurality of fine, parallel gas flow passages extending from an inlet face to an outlet face of the substrate such that passages are open to fluid flow therethrough.
  • the passages which are essentially straight paths from their fluid inlet to their fluid outlet, are defined by walls on which the catalytic material is applied as a washcoat so that the gases flowing through the passages contact the catalytic material.
  • the flow passages of the monolithic substrate are thin-walled channels, which can be of any suitable cross-sectional shape and size such as trapezoidal, rectangular, square, sinusoidal (S-shape) , hexagonal, oval, circular, etc.
  • Such structures may contain 60 to 900, or even more gas inlet openings (i.e., cells) per square inch of cross section.
  • the substrate may have 200 to 750, more usually 300 to 600 cells per square inch ( "cpsi" ) .
  • the wall thickness of flow-through substrates may vary, with a typical range of from 1 mil to 0.1 inches.
  • the substrate is a wall-flow substrate having a plurality of fine, parallel gas flow passages extending along from an inlet face to an outlet face of the substrate wherein alternate passages are blocked at opposite ends.
  • the configuration requires the gas stream flow through the porous walls of the wall-flow substrate to reach the outlet face.
  • the wall-flow substrates may contain up to 700 cells per square inch (cpsi) , for example 100 to 400 cpsi.
  • the cross-sectional shape of the passages can vary as described above for the passages of the flow-through substrate.
  • the wall thickness of wall-flow substrates may vary, with a typical range of from 2 mils to 0.1 inches.
  • the present invention provides a process for preparing the catalytic article as described in the first aspect, which comprises
  • the pore-forming agent is in form of particles and used in an amount of at least 0.5%by weight, based on the loading of the catalyst coating layer as formed.
  • the substrate on which the slurry comprising a platinum group metal component in supported form and a pore-forming agent may be a blank substrate or may have been precoated with any suitable bottom coating layers.
  • the blank substrate is intended to mean a substrate carrying no coating before the slurry comprising a platinum group metal component in supported form and a pore-forming agent is applied onto it.
  • the catalyst coating layer as formed in accordance with the process according to the present invention may constitute the catalyst coating of the catalytic article.
  • the catalyst coating layer as formed in accordance with the process according to the present invention may constitute one of coating layers of the catalyst coating of the catalytic article.
  • the catalyst coating layer as formed may be a top coating layer or a bottom coating layer.
  • the present invention provides a process for preparing the catalytic article as described in the first aspect, which comprises
  • the pore-forming agent is in form of particles and used in an amount of at least 0.5%by weight, based on the loading of each catalyst coating layer as formed.
  • a catalyst coating which comprises two catalyst coating layers and has a pore volume distribution as specified hereinabove may be provided on the substrate.
  • a catalyst coating comprising more catalyst coating layers and has a pore volume distribution as specified hereinabove may also be provided on the substrate by applying a further slurry comprising a platinum group metal component in supported form and a pore-forming agent in an amount as specified above.
  • the pore-forming agent is preferably used in an amount of at least 1%by weight, or at least 3%by weight, or at least 4%by weight, based on the loading of each catalyst coating layer as formed from the slurry comprising the pore-forming agent. More preferably, the pore-forming agent may be used in an amount of 50%by weight or less, or 30%by weight or less, based on the loading of each catalyst coating layer.
  • the pore-forming agent may be an organic or inorganic material body which can be burned-off and leave voids during the calcination step providing a coating or coating layer.
  • the pore-forming agent may be selected from organic materials such as natural and synthetic polymers, organic small molecule compounds, inorganic materials such as inorganic salts and carbon materials, cellulose-containing natural materials, and any combinations thereof.
  • Suitable natural and synthetic polymers as the pore-forming agent may include, but are not limited to, polyether polyols such as polyethylene glycols and alkyl-capped derivatives thereof, styrenic homopolymers or copolymers such as polystyrenes, poly (meth) acrylic acids and ester derivatives thereof such as polymethyl methacrylate, celluloses, ether and ester derivatives of celluloses, polyvinyl alcohols, polyvinyl pyrrolidones and any combinations thereof.
  • polyether polyols such as polyethylene glycols and alkyl-capped derivatives thereof
  • styrenic homopolymers or copolymers such as polystyrenes
  • poly (meth) acrylic acids and ester derivatives thereof such as polymethyl methacrylate
  • celluloses, ether and ester derivatives of celluloses polyvinyl alcohols
  • polyvinyl pyrrolidones any combinations thereof.
  • Suitable organic small molecule compounds as the pore-forming agent may include, but are not limited to, benzoic acid and derivatives thereof, carbamide (urea) , sugar crystals and any combinations thereof.
  • Suitable inorganic salts as the pore-forming agent may include, but are not limited to, ammonium bicarbonate, magnesium carbonate, and any combinations thereof.
  • Suitable carbon materials as the pore-forming agent may include, but are not limited to, carbon black, carbon fiber, graphite and any combinations thereof.
  • Suitable cellulose-containing natural materials as the pore-forming agent may be granulated products from dried plants, which include, but are not limited to, sunflower, cotton, rice, wheat, sorghum, breadfruit tree, sugar cane, corn, bamboo and any combinations thereof.
  • the granulated products may be obtained from various part of plants such as leaf, bark, straw, root, husk and any combinations thereof.
  • the pore-forming agent may be particles having a variety of geometries, including but are not limited to spheres, tablets, cylinders or fibers.
  • the pore-forming agent has an average particle size D 50 in the range of from 1 to 50 ⁇ m, or from 10 to 30 ⁇ m, or from 15 to 20 ⁇ m.
  • the pore-forming agent is in form of particles having a maximal particle size of 60 ⁇ m, preferably 40 ⁇ m.
  • a slurry for a washcoat may be prepared by suspending finely divided particles of a catalyst (e.g., the PGM component in supported form) in an appropriate vehicle, e.g., water, to which a promoter, a binder, a stabilizer, a viscosity modifier and/or a surfactant may be added.
  • a catalyst e.g., the PGM component in supported form
  • an appropriate vehicle e.g., water
  • the slurry may be comminuted/milled to result in substantially all of the solids having average particle sizes of higher than 10 microns, e.g., in the range of from 15 to 50 microns.
  • the comminution/milling may be accomplished in a ball mill, a continuous Eiger mill, or any other similar equipments.
  • the slurry generally has a pH of 2 to less than 9, and may be adjusted, if necessary, by adding an inorganic or an organic acid and/or base.
  • the solids content of the slurry may be, e.g., 15 to 60 %by weight.
  • the pore-forming agent when used, may be incorporated into the slurry at any timing during the preparation of the slurry, for example before the comminution/milling.
  • the obtained slurry may be applied on a substrate by dipping the substrate into the slurry, or otherwise coating onto the substrate, such that a desired loading of a coating layer will be deposited on the substrate. Thereafter, the coated substrate may be dried at a temperature in the range of from 100 to 300 °C and/or calcined by heating at a temperature in the range of from 350 to 650 °C for a period of time, for example 1 to 3 hours. Drying and calcination are typically done in air. The coating, drying, and calcination processes may be repeated if necessary to achieve the final desired gravimetric amount of the catalyst washcoat layer on the support.
  • the catalyst washcoat loading may be determined through calculation of the difference in the weights of the substrate before and after applying the washcoat.
  • the catalytic article according to the present invention may be used to treat exhaust streams from combustion engines of automobiles, especially gasoline engines.
  • the catalytic article according to the present invention may particularly be effective to treat exhaust streams from saddle-riding type vehicle engines.
  • the catalytic article according to the present invention is a TWC catalytic article.
  • an exhaust treatment system which comprises the catalytic article as described herein located downstream of a stoichiometric engine, particularly a gasoline engine.
  • the exhaust treatment system is particularly useful for a saddle-riding type vehicle engine.
  • a method for treating an exhaust stream particularly from a stoichiometric engine is provided, which includes contacting the exhaust stream with the catalytic article or the exhaust treatment system as described herein.
  • the present invention provides a method for treating an exhaust stream from a gasoline engine, preferably a saddle-riding type vehicle engine.
  • a catalytic article comprising a catalyst coating on a substrate, wherein the catalyst coating comprises at least one catalyst coating layer comprising a platinum group metal component in supported form and has a pore volume distribution such that a peak top of pore volume diameter at nano level is present in the range of from 90.0 nm to 140.0 nm and a peak top of pore volume diameter at micron level is present in the range of from 5.5 ⁇ m to 10.0 ⁇ m, in a logarithmic differential pore volume distribution as determined by mercury intrusion porosimetry.
  • the catalytic article according to Embodiment 9 or 10, wherein the catalyst coating comprises a top catalyst coating layer comprising a first platinum group metal component in supported form and a bottom coating layer comprising a second platinum group metal component in supported form.
  • the catalyst coating comprises two catalyst coating layers comprising a PGM component in supported form wherein one catalyst coating layer comprises a Rh component in supported form and optionally a Pt component in supported form as the PGM component, and the other catalyst coating layer comprises a Pt component in supported form and optionally a Pd component in supported from as the PGM component.
  • the catalyst coating comprises a top catalyst coating layer comprising a Rh component in supported form and optionally a Pt component in supported form as the PGM component, and a bottom catalyst coating layer comprising a Pt component in supported form and optionally a Pd component in supported from as the PGM component.
  • the pore-forming agent is in form of particles and used in an amount of at least 0.5%by weight, based on the loading of the catalyst coating layer as formed.
  • the pore-forming agent is in form of particles and used in an amount of at least 0.5%by weight, based on the loading of each catalyst coating layer as formed.
  • the pore-forming agent is selected from polyether polyols such as polyethylene glycols and alkyl-capped derivatives thereof, styrenic homopolymers or copolymers such as polystyrenes, poly (meth) acrylic acids and ester derivatives thereof such as polymethyl methacrylate or crosslinked polymethyl methacrylate, celluloses, ether and ester derivatives of celluloses, polyvinyl alcohols, polyvinyl pyrrolidones and any combinations thereof.
  • polyether polyols such as polyethylene glycols and alkyl-capped derivatives thereof
  • styrenic homopolymers or copolymers such as polystyrenes
  • poly (meth) acrylic acids and ester derivatives thereof such as polymethyl methacrylate or crosslinked polymethyl methacrylate
  • celluloses, ether and ester derivatives of celluloses polyvinyl alcohols, polyvinyl pyrrolidones and any combinations thereof.
  • An exhaust treatment system which comprises the catalytic article as defined in any of Embodiments 1 to 13 located downstream of a stoichiometric engine.
  • a method for treating an exhaust stream, particularly from a stoichiometric engine which includes contacting the exhaust stream with the catalytic article as defined in any of Embodiments 1 to 13 or the exhaust treatment system as defined in Embodiment 26 or 27.
  • the obtained mixture was then mixed with an aqueous solution of 0.6 g 1-octanol, 4 g barium acetate and 45 g alumina to provide a slurry having a solid content of 33 wt%.
  • the slurry was then milled until the resulting particle size D 90 of 45 microns, and then adjusted by nitric acid to a final pH of 4.5.
  • the solid content of the obtained slurry (hereinbelow, referred to as slurry B) is 30 wt%.
  • a metallic flow-through substrate of 40 mm in diameter and 90 mm in length was used as the substrate, which has channels with a cross-sectional shape of sinusoidal, 300 cells per square inch and 5 mil wall thickness.
  • the slurries A and B were then disposed over the full length of the substrate in sequence.
  • the substrate was dried at 110 °C to remove between 85 and 95 %of moisture and then calcined at 550 °C for 2 hours after each coating.
  • the loadings of the bottom coating layer obtained from the slurry A and the top coating layer obtained from the slurry B are 2.08 g/in 3 and 1.25 g/in 3 respectively.
  • the bottom coating layer contains 4.5 g/ft 3 Pt and the top coating layer contains 3.5 g/ft 3 Rh.
  • Example 2 (Sample S2, Inventive)
  • PMMA polymethyl methacrylate
  • Example 3 (Sample S3, Inventive)
  • the preparation is same as that of Example 2 except that 0.208 g/in 3 and 0.132 g/in 3 of the PMMA are added to the slurries A and B before milling, respectively.
  • the preparation is same as that of Example 2 except that 0.416 g/in 3 and 0.264 g/in 3 of the PMMA were added to the slurries A and B before milling, respectively.
  • aqueous hexahydroxyplatinic acid diethanolamine (12 wt%Pt) was diluted into water and loaded by incipient wetness to supports consisting of 41.81 g ceria doped alumina (10 wt%CeO 2 ) and 150.52 g ceria-zirconia (45 wt%CeO 2 ) .
  • the solid content after incipient wetness was 68 wt%.
  • the obtained mixture was then mixed with an aqueous solution of 0.7 g 1-octanol, 6.99 g barium acetate, 6.0 g nitric acid and 3.3 g alumina to provide a slurry having a solid content of 45 wt%.
  • the slurry was then milled until the resulting particle size D 90 was 45 microns.
  • the obtained slurry (hereinbelow, referred to as slurry C) had a final pH of 4.5 and a solid content of 41 wt
  • 0.144 g aqueous neodymium nitrate (30 wt%Nd) and 2.465 g aqueous rhodium nitrate (10 wt%Rh) were diluted into water respectively and loaded in sequence to supports consisting of 10.61 g zirconia doped alumina (20 wt%ZrO 2 ) and 37.13 g ceria-zirconia (22 wt%CeO 2 ) by incipient wetness, to obtain a mixture having a solid content after incipient wetness of 66 wt%.
  • aqueous hexahydroxyplatinic acid diethanolamine (12 wt%Pt) was diluted into water and loaded to support of 42.44 g ceria doped alumina (10 wt%CeO 2 ) by incipient wetness, to obtain a mixture having a solid content after incipient wetness of 60 wt%.
  • the above mixtures were then mixed in an aqueous solution of 0.7 g 1-octanol, 3.0 g nitric acid, 2.55 g barium sulfate and 4.24 g alumina to provide a slurry having a solid content of 33 wt%.
  • the slurry was then milled until the resulting particle size D 90 was 20 microns.
  • the obtained slurry (hereinbelow, referred to as slurry D) had a final pH of 4 and a solid content of 31 wt%.
  • a metallic flow-through substrate of 40 mm in diameter and 90 mm in length was used as the substrate, which has channels with a cross-sectional shape of sinusoidal, 300 cells per square inch and 5 mil wall thickness.
  • the slurries C and D were then disposed over the full length of the substrate in sequence.
  • the substrate was dried at 120 °C to remove between 85 and 95 %of moisture and then calcined at 550 °C after each coating.
  • the loadings of the bottom coating layer obtained from the slurry C and the top coating layer from the slurry D are 2.04 g/in 3 and 0.96 g/in 3 , respectively.
  • the bottom coating layer contains 2.5 g/ft 3 Pt
  • the top coating layer contains 1.5 g/ft 3 Pt, 4.0 g/ft 3 Pd and 2.0 g/ft 3 Rh.
  • Example 6 (Sample S6, Inventive)
  • PMMA polymethyl methacrylate
  • Example 7 (Sample S7, Inventive)
  • the preparation is same as that of Example 6 except that 0.204 g/in 3 and 0.096 g/in 3 of the PMMA were added to the slurries C and D before milling, respectively.
  • Example 8 (Sample S8, Inventive)
  • the preparation is same as that of Example 6 except that 0.408 g/in 3 and 0.192 g/in 3 of the PMMA were added to the slurries C and D before milling, respectively.
  • the pore volume distribution in the catalyst coating of each catalyst article was examined by a mercury porosimeter (Poremaster 60) .
  • the measurement was performed on the standard mercury injection procedure using an automatic porosimeter “Poremaster 60” manufactured by Anton Paar Quanta Tec Inc. Samples for the measurement were prepared by scratching pieces of the catalyst coating from each catalyst article.
  • Measurement cell sample chamber volume of 3 cm 3 , and intrusion volume of 0.39 cm 3 ;
  • Measurement point 1071 points (where the points were carved to be at equal intervals when the pore diameter was applied by the logarithm) .
  • Test samples were prepared by accommodating respective catalytic articles as prepared in above Examples, in fresh state or upon aging in accordance with standard bench cycle (SBC) at a temperature of 820 to 940 °C and a lambda value of 0.9 to 1.1 for 18 hours, into a housing with an inlet and an outlet for passing the gas stream to be treated.
  • the test samples each were equipped on a 125 cc Wuyang-Honda motorbike (WH125T-9A) or a 125 cc Dachangjiang motorbike (DCJ-HJ125T-22A) .
  • the emissions of each pollutant were measured using the World motorcycle Test Cycle (WMTC) in accordance with GB14622-2016, Type I.
  • P2 Hot phase from 600 to 1200 seconds.
  • Test results of emission are summarized in Tables 2 to 5 below.
  • the catalytic articles according to the present invention which comprises a catalyst coating having the pore volume distribution as described herein exhibit overall improved control of HC, CO and NO x emissions, compared with the catalytic articles (S1 and S4) comprising a catalyst coating not having the pore volume distribution as described herein.
  • the catalytic articles according to the present invention which comprises a catalyst coating having the pore volume distribution as described herein exhibit overall improved control of HC, CO and NO x emissions, compared with the catalytic article (S5) comprising a catalyst coating not having the pore volume distribution as described herein.

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Abstract

L'invention concerne un article catalytique comprenant un revêtement de catalyseur sur un substrat, le revêtement de catalyseur comprenant au moins une couche de revêtement de catalyseur comprenant un composant métallique de groupe de platine sous forme supportée et présentant une distribution de volume de pore de sorte qu'un sommet de pic de diamètre de volume de pore à un niveau micrométrique est présent dans la plage de 90,0 nm à 140,0 nm et un sommet de pic de diamètre de volume de pore à un niveau micrométrique est présent dans la plage de 5,5 µm à 10,0 µm, dans une distribution de volume de pore différentiel logarithmique telle que déterminée par porosimétrie par intrusion de mercure. L'invention concerne également un procédé de préparation de l'article catalytique et un système de traitement d'échappement comprenant l'article catalytique.
PCT/CN2023/105720 2022-07-05 2023-07-04 Article catalytique pour traitement de gaz d'échappement de moteur WO2024008078A1 (fr)

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Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH1043588A (ja) * 1996-08-01 1998-02-17 Nissan Motor Co Ltd 排気ガス浄化用触媒
GB2470724A (en) * 2009-06-01 2010-12-08 Gm Global Tech Operations Inc A catalyst for treating exhaust emissions
CN102186582A (zh) * 2008-10-17 2011-09-14 株式会社Ict 废气净化用催化剂以及使用该催化剂的净化方法
CN102333579A (zh) * 2009-02-26 2012-01-25 约翰森·马瑟公开有限公司 用于从强制点火发动机排出的尾气中滤除颗粒物质的过滤器
CN105264188A (zh) * 2013-04-24 2016-01-20 庄信万丰股份有限公司 包括催化型分区涂覆的过滤器基底的强制点火发动机和排气系统
CN107405614A (zh) * 2015-02-27 2017-11-28 株式会社丰田中央研究所 废气净化用催化剂、其制造方法、和使用其净化废气的方法
WO2021126685A1 (fr) * 2019-12-19 2021-06-24 Basf Corporation Article de catalyseur pour capturer une matière particulaire

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH1043588A (ja) * 1996-08-01 1998-02-17 Nissan Motor Co Ltd 排気ガス浄化用触媒
CN102186582A (zh) * 2008-10-17 2011-09-14 株式会社Ict 废气净化用催化剂以及使用该催化剂的净化方法
CN102333579A (zh) * 2009-02-26 2012-01-25 约翰森·马瑟公开有限公司 用于从强制点火发动机排出的尾气中滤除颗粒物质的过滤器
GB2470724A (en) * 2009-06-01 2010-12-08 Gm Global Tech Operations Inc A catalyst for treating exhaust emissions
CN105264188A (zh) * 2013-04-24 2016-01-20 庄信万丰股份有限公司 包括催化型分区涂覆的过滤器基底的强制点火发动机和排气系统
CN107405614A (zh) * 2015-02-27 2017-11-28 株式会社丰田中央研究所 废气净化用催化剂、其制造方法、和使用其净化废气的方法
WO2021126685A1 (fr) * 2019-12-19 2021-06-24 Basf Corporation Article de catalyseur pour capturer une matière particulaire

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