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EP4577333A1 - Système de post-traitement d'échappement comprenant des catalyseurs à trois voies - Google Patents

Système de post-traitement d'échappement comprenant des catalyseurs à trois voies

Info

Publication number
EP4577333A1
EP4577333A1 EP23771887.9A EP23771887A EP4577333A1 EP 4577333 A1 EP4577333 A1 EP 4577333A1 EP 23771887 A EP23771887 A EP 23771887A EP 4577333 A1 EP4577333 A1 EP 4577333A1
Authority
EP
European Patent Office
Prior art keywords
way catalyst
ceria
alumina
mixed oxide
combination
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
EP23771887.9A
Other languages
German (de)
English (en)
Inventor
Xiaolai Zheng
Shiang Sung
Stephen C Johnson
Daniel Lee COHEN
Yipeng Sun
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.)
BASF Mobile Emissions Catalysts LLC
Original Assignee
BASF Mobile Emissions Catalysts LLC
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by BASF Mobile Emissions Catalysts LLC filed Critical BASF Mobile Emissions Catalysts LLC
Publication of EP4577333A1 publication Critical patent/EP4577333A1/fr
Pending legal-status Critical Current

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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
    • 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
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/92—Chemical or biological purification of waste gases of engine exhaust gases
    • B01D53/94—Chemical or biological purification of waste gases of engine exhaust gases by catalytic processes
    • B01D53/9459—Removing one or more of nitrogen oxides, carbon monoxide, or hydrocarbons by multiple successive catalytic functions; systems with more than one different function, e.g. zone coated catalysts
    • B01D53/9477—Removing one or more of nitrogen oxides, carbon monoxide, or hydrocarbons by multiple successive catalytic functions; systems with more than one different function, e.g. zone coated catalysts with catalysts positioned on separate bricks, e.g. exhaust systems
    • 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
    • B01J21/00—Catalysts comprising the elements, oxides, or hydroxides of magnesium, boron, aluminium, carbon, silicon, titanium, zirconium, or hafnium
    • B01J21/02—Boron or aluminium; Oxides or hydroxides thereof
    • B01J21/04—Alumina
    • 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
    • B01J21/00—Catalysts comprising the elements, oxides, or hydroxides of magnesium, boron, aluminium, carbon, silicon, titanium, zirconium, or hafnium
    • B01J21/06—Silicon, titanium, zirconium or hafnium; Oxides or hydroxides thereof
    • B01J21/066—Zirconium or hafnium; Oxides or hydroxides thereof
    • 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
    • B01J23/40—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals of the platinum group metals
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
    • B01J23/54—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
    • B01J23/56—Platinum group metals
    • B01J23/63—Platinum group metals with rare earths or actinides
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL-COMBUSTION ENGINES
    • F01N13/00—Exhaust or silencing apparatus characterised by constructional features
    • F01N13/009—Exhaust or silencing apparatus characterised by constructional features having two or more separate purifying devices arranged in series
    • F01N13/0093—Exhaust or silencing apparatus characterised by constructional features having two or more separate purifying devices arranged in series the purifying devices are of the same type
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL-COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
    • F01N3/101—Three-way catalysts
    • 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
    • B01D2255/1023—Palladium
    • 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
    • B01D2255/209—Other metals
    • B01D2255/2092—Aluminium
    • 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
    • B01D2258/00—Sources of waste gases
    • B01D2258/01—Engine exhaust gases
    • B01D2258/012—Diesel engines and lean burn gasoline engines
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2258/00—Sources of waste gases
    • B01D2258/01—Engine exhaust gases
    • B01D2258/014—Stoichiometric gasoline engines
    • 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
    • B01J2523/00—Constitutive chemical elements of heterogeneous catalysts
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL-COMBUSTION ENGINES
    • F01N2370/00—Selection of materials for exhaust purification
    • F01N2370/02—Selection of materials for exhaust purification used in catalytic reactors
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/12—Improving ICE efficiencies

Definitions

  • the presently claimed invention relates to an exhaust aftertreatment system comprising at least two three-way catalysts (TWC’s).
  • TWC three-way catalysts
  • the presently claimed invention relates to the exhaust aftertreatment system comprising at least two three-way catalysts (TWC’s) of which one TWC is located in an upstream position and the other TWC is located in a downstream position.
  • Exhaust gas from vehicles powered by gasoline engines is typically treated with one or more three-way conversion (TWC) automotive catalysts, which are effective to abate pollutants of nitrogen oxides (NOx), carbon monoxide (CO), and hydrocarbon (HC) in the engine exhaust.
  • TWC three-way conversion
  • a typical exhaust after-treatment system for a gasoline engine consists of two TWC catalysts, namely, a first/upstream TWC catalyst mounted in a position near the exhaust manifold and the engine compartment (the close-coupled position, CC), and a second/downstream TWC catalyst placed in a position either directly next to the first TWC catalyst (the second close-coupled position, CC2) or underneath the vehicle body (the underfloor position, UF).
  • a conventional TWC catalyst comprises two platinum group metals (PGMs), namely palladium (Pd) and rhodium (Rh) as active catalytic components. These platinum group metals are supported on oxygen storage components (OSCs) and/or refractory metal oxide supports.
  • PGMs platinum group metals
  • OSCs oxygen storage components
  • DE 10 2019 208436 Al relates to an aftertreatment method for a lean burn engine.
  • the method is designed to control an aftertreatment system sequentially equipped with an ammonia production catalyst module, a selective catalytic reduction catalyst, and a CO clean-up catalyst on an exhaust pipe through which an exhaust gas flows.
  • US 2010/061903 Al relates to a catalyst system to be used in an automobile exhaust gas purification apparatus, comprised of using two or more exhaust gas purification catalysts comprising a first catalyst supported on an inorganic structural carrier, and a second catalyst supported on a part of the inorganic structural carrier positioned at the downstream side.
  • US 2002/048542 Al discloses a catalytic trap for conversion ofNOxin an exhaust gas stream comprising a catalytic trap material and a refractory carrier member on which the catalytic trap material is coated.
  • US 2009/042722 Al discloses a method for preparing a catalyst having a base metal undercoat with an oxygen storage component.
  • the existing exhaust after-treatment system for a gasoline engine utilizes high loading of palladium which renders the exhaust system least cost effective. That has led to a renewed interest in the automobile industry to use substantial amount of Pt for TWC applications, given the current low price of Pt in the market. Accordingly, the present invention is focussed on providing a high-performance, cost-effective emission control system comprising at least two three-way catalysts (TWC’s) with use of a substantial amount of Pt.
  • TWC three-way catalysts
  • the object of the presently claimed invention is to provide an exhaust aftertreatment system which provides comparable or improved performance when compared with a conventional Pd/Rh based TWC system.
  • Another object of the presently claimed invention is to provide the exhaust aftertreatment system which delivers improved NOx performance during fuel-cut events.
  • Still another object of the presently claimed invention is to provide the exhaust aftertreatment system which allows a substantial replacement of Pd with Pt (20-80%) thereby rendering the system cost-effective.
  • the present invention provides an exhaust aftertreatment system comprising a first three-way catalyst deposited at least on a part of a first substrate; and a second three-way catalyst deposited at least on a part of a second substrate, wherein the first three-way catalyst comprises platinum supported on alumina, ceriazirconia mixed oxide, ceria-alumina composite, or any combination thereof, palladium supported on alumina, ceria-zirconia mixed oxide, ceria-alumina composite, or any combination thereof, and rhodium supported on alumina, ceria-zirconia mixed oxide, ceriaalumina composite, or any combination thereof, wherein the second three-way catalyst comprises platinum supported on alumina, ceriazirconia mixed oxide, ceria-alumina composite, or any combination thereof.
  • the present invention also provides a method of reducing the emissions of hydrocarbons, carbon monoxide, and nitrogen oxide levels in a gaseous exhaust stream, the method comprising contacting a gaseous exhaust stream with exhaust aftertreatment system according to the present invention to reduce the levels of hydrocarbons, carbon monoxide, and nitrogen oxide in the exhaust gas.
  • the present invention further provides use of the exhaust aftertreatment system according to the present invention for purifying a gaseous exhaust stream comprising hydrocarbons, carbon monoxide, and nitrogen oxide.
  • FIGURE 1 illustrates configurations of TWC catalyst systems.
  • FIGURE 2 illustrates FTP-75 Tailpipe cumulative NOx emissions of Examples S5 and S6 collected on a SULEV30 vehicle calibrated with frequent fuel-cut events.
  • FIGURE 3A is a perspective view of a honeycomb-type substrate carrier which may comprise the catalyst composition in accordance with one embodiment of the presently claimed invention.
  • FIGURE 3B is a partial cross-section view enlarged relative to FIG. 3 A and taken along a plane parallel to the end faces of the substrate carrier of FIG. 3 A, which shows an enlarged view of a plurality of the gas flow passages shown in FIG. 3 A.
  • FIGURE 4 is a cutaway view of a section enlarged relative to FIG. 3 A, wherein the honeycombtype substrate in FIG. 3 A represents a wall flow filter substrate monolith.
  • washcoat is interchangeably used for “first three-way catalyst” or “the second three-way catalyst” which forms one or more layers on a part of a respective substrate.
  • washcoat has its usual meaning in the art of a thin, adherent coating of a catalytic or other material applied to a substrate material.
  • a washcoat is formed by preparing a slurry containing a certain solid content (e.g., 15-60% by weight) of particles in a liquid vehicle, which is then coated onto a substrate and dried to provide a washcoat layer on the respective substrate.
  • TWC catalyst refers to a catalyst that simultaneously promotes a) reduction of nitrogen oxides to nitrogen and oxygen; b) oxidation of carbon monoxide to carbon dioxide; and c) oxidation of unburnt hydrocarbons to carbon dioxide and water.
  • NOx refers to nitrogen oxide compounds, such as NO and/or NO2.
  • stream broadly refers to any combination of flowing gas that may contain solid or liquid particulate matters.
  • upstream and downstream refer to relative directions according to the flow of an engine exhaust gas stream from an engine towards a tailpipe, with the engine in an upstream location and the tailpipe and any pollution abatement articles such as filters and catalysts being downstream from the engine.
  • close-coupled refers to a position of one or more catalytic converters which are placed in a proximity to the engine-out manifold.
  • underfloor refers to a position of one or more catalytic converters which are placed away from the close-coupled position.
  • the underfloor catalytic converter is placed in the underfloor of the vehicle body between a close-coupled catalytic convert and a muffler.
  • the amount of platinum group metal/s such as platinum/palladium/rhodium, and/or support material such as ceria-zirconia mixed oxide, ceria-alumina composite, alumina etc is calculated as weight %, based on the total weight of the washcoat present on the substrate, i.e., the amount is calculated without considering the substrate amount, though substrate is part of the overall catalytic system.
  • the present invention focussed on addressing low NOx performance during fuel-cut events associated with the existing exhaust aftertreatment system and improving the overall performance despite a substantial replacement of Pd with Pt (20-80%).
  • the present invention in first aspect provides an exhaust aftertreatment system comprising: a. a first three-way catalyst deposited at least on a part of a first substrate; and b. a second three-way catalyst deposited at least on a part of a second substrate, wherein the first three-way catalyst comprises: i. platinum supported on alumina, ceria-zirconia mixed oxide, ceriaalumina composite or any combination thereof, ii. palladium supported on alumina, ceria-zirconia mixed oxide, ceriaalumina composite or any combination thereof, and iii.
  • the second three-way catalyst comprises platinum supported on alumina, ceriazirconia mixed oxide, ceria-alumina composite or any combination thereof.
  • the amount of platinum supported on alumina, ceria-zirconia mixed oxide, ceriaalumina composite, or any combination thereof in the first three-way catalyst and the second three-way catalyst is preferably in the range of 0.01 to 5.0 wt. %, based on the total weight of the first three-way catalyst and the second three-way catalyst. More preferably, the amount of platinum supported on alumina, ceria-zirconia mixed oxide, ceria-alumina composite, or any combination thereof in the first three-way catalyst and the second three-way catalyst is in the range of 0.02 to 3.0 wt. %, based on the total weight of the first three-way catalyst and the second three-way catalyst.
  • the amount of platinum supported on alumina, ceria-zirconia mixed oxide, ceria-alumina composite, or any combination thereof in the first three-way catalyst and the second three-way catalyst is in the range of 0.03 to 2.5 wt. %, based on the total weight of the first three-way catalyst and the second three-way catalyst.
  • the amount of palladium supported on alumina, ceria-zirconia mixed oxide, ceria-alumina composite, or any combination thereof in the first three-way catalyst and the second three-way catalyst is in the range of 0.02 to 2.0 wt. %, based on the total weight of the first three-way catalyst and the second three-way catalyst.
  • the amount of rhodium supported on alumina, ceria-zirconia mixed oxide, ceriaalumina composite, or any combination thereof in the first three-way catalyst and the second three-way catalyst is preferably in the range of 0.01 to 2.0 wt. %, based on the total weight of the first three-way catalyst and the second three-way catalyst. More preferably, the amount of rhodium supported on alumina, ceria-zirconia mixed oxide, ceria-alumina composite, or any combination thereof in the first three-way catalyst and the second three-way catalyst is in the range of 0.01 to 1.5 wt. %, based on the total weight of the first three-way catalyst and the second three-way catalyst.
  • the amount of rhodium supported on alumina, ceria-zirconia mixed oxide, ceria-alumina composite, or any combination thereof in the first three-way catalyst and the second three-way catalyst is in the range of 0.01 to 1.0 wt. %, based on the total weight of the first three-way catalyst and the second three-way catalyst.
  • the weight ratio of platinum supported on alumina, ceria-zirconia mixed oxide, ceria-alumina composite, or any combination thereof in the first three-way catalyst to the platinum supported on alumina, ceria-zirconia mixed oxide, ceria-alumina composite, or any combination thereof in the second three-way catalyst is greater than 1.
  • the weight ratio of platinum supported on alumina, ceria-zirconia mixed oxide, ceria-alumina composite, or any combination thereof in the first three-way catalyst to the platinum supported on alumina, ceria-zirconia mixed oxide, ceria-alumina composite, or any combination thereof in the second three-way catalyst is in the range of 2: 1 to 20: 1.
  • the weight ratio of platinum supported on alumina, ceria-zirconia mixed oxide, ceria-alumina composite, or any combination thereof in the first three-way catalyst to the platinum supported on alumina, ceria-zirconia mixed oxide, ceria-alumina composite, or any combination thereof in the second three-way catalyst is in the range of 2.5: 1 to 12: 1.
  • the weight ratio of the rhodium supported on alumina, ceria-zirconia mixed oxide, ceria-alumina composite, or any combination thereof in the first three-way catalyst to the rhodium supported on alumina, ceria-zirconia mixed oxide, ceria-alumina composite, or any combination thereof in the second three-way catalyst is in the range of 1 :3 to 50: 1, more preferably in the range of 1 : 1 to 50: 1.
  • the weight ratio of the rhodium supported on alumina, ceriazirconia mixed oxide, ceria-alumina composite, or any combination thereof in the first three- way catalyst to the rhodium supported on alumina, ceria-zirconia mixed oxide, ceria-alumina composite, or any combination thereof in the second three-way catalyst is in the range of 1 :2 to 20: 1, more preferably in the range of 1 : 1 to 20: 1.
  • the weight ratio of the rhodium supported on alumina, ceria-zirconia mixed oxide, ceria-alumina composite, or any combination thereof in the first three-way catalyst to the rhodium supported on alumina, ceria-zirconia mixed oxide, ceria-alumina composite, or any combination thereof in the second three-way catalyst is in the range of 1 : 1.5 to 4: 1, more preferably in the range of 1 : 1 to 4: 1.
  • the weight ratio of the total amount of platinum, palladium and rhodium, each supported on alumina, ceria-zirconia mixed oxide, ceria-alumina composite, or any combination thereof in the first three-way catalyst to the total amount of platinum optionally with rhodium and palladium, each supported on alumina, ceria-zirconia mixed oxide, ceriaalumina composite, or any combination thereof in the second three-way catalyst is in the range of 1.1 : 1 to 20: 1.
  • the weight ratio of the total amount of platinum, palladium and rhodium, each supported on alumina, ceria-zirconia mixed oxide, ceria-alumina composite, or any combination thereof in the first three-way catalyst to the total amount of platinum optionally with rhodium and palladium, each supported on alumina, ceria-zirconia mixed oxide, ceria-alumina composite, or any combination thereof in the second three-way catalyst is in the range of 4: 1 to 20: 1.
  • a “support” in a catalytic material or catalyst composition or catalyst washcoat refers to a material such as alumina, ceria-alumina composite, ceria-zirconia mixed oxide etc. that receives metals (e.g., PGMs), stabilizers, promoters, binders, and the like through precipitation, association, dispersion, impregnation, or other suitable methods.
  • metals e.g., PGMs
  • stabilizers e.g., stabilizers, promoters, binders, and the like through precipitation, association, dispersion, impregnation, or other suitable methods.
  • the amount of the ceria-alumina composite present in the first three-way catalyst and the second three-way catalyst is in the range of 5.0 to 80 wt.%, based on the total weight of the first three-way catalyst and the second three-way catalyst. More preferably, the amount of the ceria-alumina composite present in the first three-way catalyst and the second three-way catalyst is in the range of 10 to 60 wt.%, based on the total weight of the first three- way catalyst and the second three-way catalyst.
  • the amount of the ceriaalumina composite present in the first three-way catalyst and the second three-way catalyst is in the range of 15 to 60 wt.%, and more preferably in the range of 15 to 40 wt.%, based on the total weight of the first three-way catalyst and the second three-way catalyst.
  • the amount of CeCE (cerium oxide) in the ceria-alumina composite present in the first three-way catalyst or the second three-way catalyst is preferably 1.0 to 60 wt. %, based on the total weight of the ceria-alumina composite in the respective catalyst. More preferably, the CeCh in the ceria-alumina composite present in the first three-way catalyst or the second three- way catalyst is 10 to 50 wt. %, based on the total weight of the ceria-alumina composite in the respective catalyst. Even more preferably, the CeCh in the ceria-alumina composite present in the first three-way catalyst or the second three-way catalyst is 15 to 50 wt. %, based on the total weight of the ceria-alumina composite in the respective catalyst.
  • the amount of AI2O3 (aluminium oxide) in the ceria-alumina composite present in the first three-way catalyst or the second three-way catalyst is preferably 40 to 99 wt.% based on the total weight of the ceria-alumina composite in the respective catalyst. More preferably, the AI2O3 in the ceria-alumina composite present in the first three-way catalyst or the second three- way catalyst is 50 to 90 wt.% based on the total weight of the ceria-alumina composite in the respective catalyst. Even more preferably, the AI2O3 in the ceria-alumina composite present in the first three-way catalyst or the second three-way catalyst is 50 to 85 wt.% based on the total weight of the ceria-alumina composite in the respective catalyst.
  • the average particle size of ceria in the ceria-alumina composite is less than 200 nm. More preferably, the particles size is in the range of 5.0 nm to 50 nm. The particle size is determined by transition electron microscopy.
  • the ceria-alumina composite present in the first three-way catalyst or the second three-way catalyst may comprise a dopant selected from zirconia, lanthana, titania, hafnia, magnesia, calcia, strontian, baria or any combination thereof.
  • the total amount of dopant in the ceria-alumina composite is preferably in the range of 0.001 to 15 wt.% based on the total weight of the ceria-alumina composite in the respective catalyst.
  • the ceria-alumina composite can be made by methods known to the person skilled in the art like co-precipitation or surface modification. In these methods, a suitable cerium containing precursor is brought into contact with a suitable aluminium containing precursor and the so obtained mixture is then transformed into the ceria-alumina composite. Suitable cerium containing precursors are for example water soluble cerium salts and colloidal ceria suspension. Ceria-alumina can also be prepared by the atomic layer deposition method, where a ceria compound selectively reacts with an alumina surface, which after calcination forms ceria on the alumina surface. This deposition/calcination step can be repeated until a layer of desired thickness is reached.
  • Suitable aluminium containing precursors are for example aluminium oxides like gibbsite, boehmite gamma alumina, delta alumina or theta alumina or their combinations. Transformation of the so obtained mixture into the ceria-alumina composite can then be achieved by a calcinations step of the mixture.
  • complex metal oxide refers to a mixed metal oxide that contains oxygen anions and at least two different metal cations.
  • cerium cations, zirconium cations are distributed within the oxide lattice structure.
  • complex oxide and “mixed oxide” can be used interchangeably.
  • the metal cations are distributed within the oxide lattice structure, these structures are also commonly referred to as solid solutions.
  • the amount of ceria-zirconia mixed oxide present in the first three-way catalyst and the second three-way catalyst is in the range of 30 to 75 wt.%, and more preferably in the range of 40 to 60 wt.%, based on the total weight of the first three-way catalyst and the second three-way catalyst.
  • ceria (calculated as CeCh) of the ceria-zirconia mixed oxide present in the first three-way catalyst or the second three-way catalyst is present in an amount of 10 to 60 wt. %, based on the total weight of the ceria-zirconia mixed oxide present in the respective catalyst and zirconia (calculated as ZrCh) of the ceria-zirconia mixed oxide present in the first three-way catalyst or the second three-way catalyst is present in an amount of 40 to 90 wt.%, based on the total weight of the ceria-zirconia mixed oxide present in the respective catalyst.
  • ceria (calculated as CeCh) of the ceria-zirconia mixed oxide present in the first three-way catalyst or the second three-way catalyst is present in an amount of 20 to 50 wt. %, based on the total weight of the ceria-zirconia mixed oxide in the respective catalyst and zirconia (calculated as ZrCh) of the ceria-zirconia mixed oxide present in the first three- way catalyst or the second three-way catalyst is present in an amount of 50 to 80 wt.%, based on the total weight of the ceria-zirconia mixed oxide in the respective catalyst.
  • ceria (calculated as CeCE) of the ceria-zirconia mixed oxide present in the first three-way catalyst or the second three-way catalyst is present in an amount of 30 to 50 wt. %, based on the total weight of the ceria-zirconia mixed oxide in the respective catalyst and zirconia (calculated as ZrCE) of the ceria-zirconia mixed oxide present in the first three-way catalyst or the second three-way catalyst is present in an amount of 50 to 70 wt.%, based on the total weight of the ceria-zirconia mixed oxide in the respective catalyst.
  • the ceria-zirconia mixed oxide serves as oxygen storage component.
  • oxygen storage component refers to an entity that has a multi-valence state and can actively react with reductants such as carbon monoxide (CO) and/or hydrogen under reduction conditions and then react with oxidants such as oxygen or nitrogen oxides under oxidative conditions.
  • reductants such as carbon monoxide (CO) and/or hydrogen under reduction conditions
  • oxidants such as oxygen or nitrogen oxides under oxidative conditions.
  • the ceria-zirconia mixed oxide present in the first three- way catalyst or the second three-way catalyst comprises a dopant selected from lanthana, titania, hafnia, magnesia, calcia, strontia, baria, yttrium, hafnium, praseodymium, neodymium, or any combinations thereof.
  • the dopant metal may be incorporated in a cationic form into the crystal structure of the complex metal oxide, may be deposited in an oxi die form on the surface of the complex metal oxide, or may be present in the oxidic form as a blend of mixtures of both dopants and complex metal oxide on a micro-scale, so to say in a composite form with the complex metal oxide.
  • the dopant(s) are comprised in an amount of 1.0 to 20 wt.%, or more preferably in an amount of 5.0 to 15 wt.%, based on the total weight of the ceriazirconia mixed oxide present in the respective catalyst.
  • Alumina present in the first three-way catalyst or the second three-way catalyst is preferably gamma alumina or activated alumina. It typically exhibits a BET surface area of fresh material in excess of 60 square meters per gram (“m 2 /g”), often up to about 200 m 2 /g or higher.
  • Activated alumina is usually a mixture of the gamma and delta phases of alumina, but may also contain substantial amounts of eta, kappa and theta alumina phases.
  • the activated alumina is high bulk density gamma-alumina, low or medium bulk density large pore gamma-alumina, low bulk density large pore boehmite or gamma-alumina.
  • the amount of alumina present in the first three-way catalyst and the second three-way catalyst is in the range of 5.0 to 70 wt.%, based on the total weight of the first three-way catalyst and the second three-way catalyst. More preferably, the amount of the alumina present in the first three-way catalyst and the second three-way catalyst is in the range of 5.0 to 20 wt.%, based on the total weight of the first three-way catalyst and the second three- way catalyst. Also preferred is that the amount of the alumina present in the first three-way catalyst and the second three-way catalyst is in the range of 10 to 60 wt.%, based on the total weight of the first three-way catalyst and the second three-way catalyst.
  • the amount of alumina present in the catalytic article is in the range of 15 to 60 wt.%, based on the total weight of the first three-way catalyst and the second three-way catalyst.
  • Alumina present in the first three-way catalyst and the second three-way catalyst is preferably doped with a dopant selected from barium, lanthana, zirconia, neodymian, yttria, ceria, titania or any combination thereof, wherein the amount of the dopant is preferably 1.0 to 30 wt.% based on the total weight of the alumina and dopant present in the respective catalyst.
  • alumina doped with dopant/s is selected from lanthana-alumina, titaniaalumina, ceria-zirconia-alumina, zirconia-alumina, lanthana-zirconia-alumina, baria-alumina, baria-lanthana-alumina, baria-lanthana-neodymia-alumina, yttrium-alumina, or any combination thereof.
  • Substrates of the first three-way catalyst and the second three-way catalyst of the presently claimed invention may be constructed of any material typically used for preparing automotive catalysts.
  • the substrate is a ceramic substrate, metal substrate, ceramic foam substrate, polymer foam substrate or a woven fiber substrate.
  • the substrate is a ceramic or a metal monolithic honeycomb structure.
  • the substrate provides a plurality of wall surfaces upon which the catalytic layer/s or washcoat described herein above are applied and adhered, thereby acting as a carrier for the catalytic material.
  • Preferable metallic substrates 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 wt. % of the alloy, e.g., 10-25 wt. % of chromium, 3-8 % of aluminium, and up to 20 wt. % 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 metal substrate may be oxidized at high temperature, e.g., 1000 °C and 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.
  • Preferable ceramic materials used to construct 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, aluminosilicates, and the like.
  • 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, aluminosilicates, and the like.
  • the first three-way catalyst covers 50 to 100 % of length of the first substrate. More preferably, the first three-way catalyst covers 70 to 100 % of the length of the first substrate and even more preferably, the first three-way catalyst covers 90 to 100 % of length of the first substrate. Most preferably, the first three-way catalyst covers the whole length or the whole accessible surface area of the substrate.
  • the second three-way catalyst covers 50 to 100 % of length of the second substrate. More preferably, the second three-way catalyst covers 70 to 100 % of the length of the second substrate and even more preferably, the second three-way catalyst covers 90 to 100 % of length of the second substrate. Most preferably, the second three-way catalyst covers the whole length or the whole accessible surface area of the substrate.
  • Embodiment 2 is a diagrammatic representation of Embodiment 1:
  • Embodiment 3 is a diagrammatic representation of Embodiment 3 :
  • Embodiment 4 is a diagrammatic representation of Embodiment 4:
  • Embodiment 5 is a diagrammatic representation of Embodiment 5:
  • the exhaust aftertreatment system according to embodiment 1, wherein the weight ratio of platinum supported on alumina, ceria-zirconia mixed oxide, ceria-alumina composite, or any combination thereof in the first three-way catalyst to the platinum supported on alumina, ceriazirconia mixed oxide, ceria-alumina composite, or any combination thereof in the second three- way catalyst is in the range of 2: 1 to 20: 1, preferably in the range of 2.5: 1 to 12: 1.
  • Embodiment 6 The exhaust aftertreatment system according to embodiment 2, wherein the weight ratio of the rhodium supported on alumina, ceria-zirconia mixed oxide, ceria-alumina composite, or any combination thereof in the first three-way catalyst to the rhodium supported on alumina, ceriazirconia mixed oxide, ceria-alumina composite, or any combination thereof in the second three- way catalyst is in the range of 1 :3 to 50: 1, preferably in the range of 1 : 1 to 50: 1, more preferably in the range of 1 :2 to 20: 1, more preferably in the range of 1 : 1 to 20: 1, more preferably in the range of 1 : 1.5 to 4: 1, and more preferably in the range of 1 : 1 to 4: 1.
  • Embodiment 7 is a diagrammatic representation of Embodiment 7:
  • the exhaust aftertreatment system according to any of embodiments 1 to 6, wherein the weight ratio of the total amount of platinum, palladium and rhodium, each supported on alumina, ceriazirconia mixed oxide, ceria-alumina composite, or any combination thereof in the first three- way catalyst to the total amount of platinum, optionally with rhodium and palladium , each supported on alumina, ceria-zirconia mixed oxide, ceria-alumina composite, or any combination thereof in the second three-way catalyst is in the range of 4: 1 to 20: 1.
  • Embodiment 8 is a diagrammatic representation of Embodiment 8
  • Embodiment 9 is a diagrammatic representation of Embodiment 9:
  • the exhaust aftertreatment system according to any of embodiments 1 to 8, wherein the second three-way catalyst is a single layered catalyst deposited on the second substrate with a total washcoat loading in the range of 1.5 to 3.2 g/in 3 , preferably in the range of 2.0 to 3.0 g/in 3 , and more preferably in the range of 2.5 to 2.8 g/in 3 .
  • Embodiment 10 is a diagrammatic representation of Embodiment 10:
  • Example 5 System 5 (S5), Comparative: S5 comprises a Pt/Pd/Rh-based upstream catalyst S5- TWC-1 and a Pd/Rh-based downstream catalyst S5-TWC-2.
  • S5-TWC-1 has a zoned bilayer washcoat structure with an inlet bottom zone, an outlet bottom zone (each zone covering about 50% of the substrate length), and a top layer covering 100% of the substrate length.
  • the catalyst was coated on a monolith cordierite substrate having dimensions of 4.66” in diameter and 3.81” in length, a cell density of 800 cpsi, and a wall thickness of 2.5 mils.
  • Table 3 summarizes the tailpipe emissions of NMHC, NOx, and CO acquired on the SULEV30 test vehicle.
  • the FTP-75 on this specific vehicle was calibrated with frequent fuelcut events for better fuel-economy which made the NOx emission control more difficult to achieve.
  • Example System 5 used a Pd/Rh-based downstream TWC.
  • the utilization of the Pt/Rh-based single-coat downstream TWC in System 6 gave substantially improved tailpipe NOx emissions at no penalties to NMHC and CO emissions.
  • Figure 2 illustrated the cumulative NOx emission traces of System 6 versus System 5.
  • the NOx benefit of the invention systems mainly came from the less NOx breakthroughs in the fuel-cut events during deaccelerations.
  • Cited literature - DE 10 2019 208436 Al

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Abstract

La présente invention concerne un système de post-traitement d'échappement comprenant un premier catalyseur à trois voies déposé au moins sur une partie d'un premier substrat ; et un second catalyseur à trois voies déposé au moins sur une partie d'un second substrat, le premier catalyseur à trois voies comprenant du platine supporté sur de l'alumine, de l'oxyde mixte de cérium-zircone, un composite d'oxyde de cérium-alumine, ou toute combinaison de ceux-ci, du palladium supporté sur de l'alumine, de l'oxyde mixte de cérium-zircone, un composite d'oxyde de cérium-alumine, ou toute combinaison de ceux-ci, et du rhodium supporté sur de l'alumine, de l'oxyde mixte de cérium-zircone, un composite d'oxyde de cérium-alumine, ou toute combinaison de ceux-ci, le second catalyseur à trois voies comprenant du platine supporté sur de l'alumine, un oxyde mixte de cérium-zircone, un composite d'oxyde de cérium-alumine ou toute combinaison de ceux-ci.
EP23771887.9A 2022-09-20 2023-09-20 Système de post-traitement d'échappement comprenant des catalyseurs à trois voies Pending EP4577333A1 (fr)

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US20020048542A1 (en) 1999-04-02 2002-04-25 Michel Deeba Catalytic trap and methods of making and using the same
US7276212B2 (en) 2001-10-01 2007-10-02 Engelhard Corporation Exhaust articles for internal combustion engines
KR101405826B1 (ko) 2007-02-01 2014-06-11 엔.이. 켐캣 가부시키가이샤 자동차용 배기가스 정화 장치에 이용되는 촉매계, 그것을 이용한 배기가스 정화 장치 및 배기가스 정화 방법
US10697340B1 (en) 2019-01-31 2020-06-30 Hyundai Motor Company After treatment system and after treatment method for lean-burn engine

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