WO2023148473A1 - Surface-modified ceria-zirconia mixed oxide compound for gasoline exhaust gas applications - Google Patents

Surface-modified ceria-zirconia mixed oxide compound for gasoline exhaust gas applications Download PDF

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Publication number
WO2023148473A1
WO2023148473A1 PCT/GB2023/050151 GB2023050151W WO2023148473A1 WO 2023148473 A1 WO2023148473 A1 WO 2023148473A1 GB 2023050151 W GB2023050151 W GB 2023050151W WO 2023148473 A1 WO2023148473 A1 WO 2023148473A1
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Prior art keywords
composition
hours
ceria
mixed oxide
heating
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PCT/GB2023/050151
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English (en)
French (fr)
Inventor
Janet FISHER
Michael Howard
Jing Lu
Andrea Eva PASCUI
Kerry SIMMANCE
Qinghe ZHENG
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Johnson Matthey PLC
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Johnson Matthey PLC
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Priority to JP2024531554A priority Critical patent/JP2025505487A/ja
Priority to CN202380014719.8A priority patent/CN118317831A/zh
Publication of WO2023148473A1 publication Critical patent/WO2023148473A1/en
Anticipated expiration legal-status Critical
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    • 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]
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
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    • F01N3/28—Construction of catalytic reactors
    • F01N3/2803—Construction of catalytic reactors characterised by structure, by material or by manufacturing of catalyst support

Definitions

  • the invention relates to a composition comprising a ceria-zirconia mixed oxide, the ceria-zirconia mixed oxide being surface-modified with a perovskite type compound, methods of manufacturing such a composition, compositions obtained or obtainable by such methods, a catalyst article, an emissions treatment system and a method of treating an exhaust gas.
  • a three-way catalyst allows simultaneous conversions (-98%) of CO, HCs and NO X from gasoline engine exhaust to innocuous compounds at stoichiometric air-to-fuel ratio.
  • the oxidation of CO and HCs to CO2 and steam (H2O) is mainly catalyzed by Pd
  • the reduction of NO X to N2 is mainly catalyzed by Rh.
  • PGM platinum group metal
  • Modern TWCs use supported platinum group metal (hereinafter “PGM”) catalysts (Pd, Rh, Pt, etc. ⁇ deposited on a single, double or multilayer support, with the support material consisting of metal oxides with high specific surface area, primarily stabilized alumina and ceria-containing oxygen storage materials.
  • the supported catalyst is washcoated on a ceramic monolithic substrate.
  • Cerium oxide (Ce x O y ), well known for its high oxygen storage capacity (OSC) due to the function of the Ce 4+ /Ce 3+ redox pair, plays an important role in TWC performance.
  • Ce x O y can also assist the feed-back control of stoichiometric condition by uptaking or donating oxygen during fuel lean/rich perturbations.
  • ZrCh zirconium oxide
  • Ce x O y fluorite structure denoted as CZO
  • Other proprietary elements Y, Nd, La, Pr, etc. are also added to OSC formulas to further enhance the TWC performance.
  • ABOs-rt perovskite-type materials are known in the art and can exhibit significant swings in oxygen non-stoichiometry 3 through the reaction with gas phase oxygen.
  • Perovskites with advanced compositions also present OSC capacity and intrinsic TWC activity.
  • OSC and catalytic activity of perovskite oxides are largely dependent on the nature of the B-site cation, while the A-site cation is found to be important in the perovskite structural formation by influencing vacancy density and charge-valence balance.
  • the oxygen uptake and release are associated with the existence of structural defects and the change of oxidation state of the B-site cation.
  • perovskites for emissions abatement emerged from their reduced ability to develop large surface areas (i.e. they have low surface-area-to- volume ratio). Moreover, they drastically sinter above 600 °C, sometimes accompanied by phase transition/separation under redox conditions.
  • One aspect of the present disclosure is directed to a composition comprising a ceriazirconia mixed oxide, the ceria-zirconia mixed oxide being surface-modified with a perovskite type compound of formula (I); wherein formula (I) is defined by Ax-yA’yBi-zB’zOy where: A is an ion of a metal selected from the group consisting of Li, Na, K, Cs, Mg, Sr, Ba, Ca, Y, La, Ce, Pr, Nd, and Gd; A’ is an ion of a metal selected from the group consisting of Li, Na, K, Cs, Mg, Sr, Ba, Ca, Y, La, Ce, Pr, Nd, and Gd; B is an ion of a metal selected from the group consisting of Cu, Mn, Mo, Co, Fe, Ni, Cr, Ti, Zr, Al, Ga, Sc, Nb, V, W, Bi, Zn, Sn, Pt, Rh, Pd
  • Another aspect of the present disclosure is directed to a method of manufacturing a composition comprising a ceria-zirconia mixed oxide, the ceria-zirconia mixed oxide being surface-modified with a perovskite type compound of formula (I); wherein formula (I) is defined by Ax-yA’yBi-zB’zCh; where: A is an ion of a metal selected from the group consisting of Li, Na, K, Cs, Mg, Sr, Ba, Ca, Y, La, Ce, Pr, Nd, and Gd; A’ is an ion of a metal selected from the group consisting of Li, Na, K, Cs, Mg, Sr, Ba, Ca, Y, La, Ce, Pr, Nd, and Gd; B is an ion of a metal selected from the group consisting of Cu, Mn, Mo, Co, Fe, Ni, Cr, Ti, Zr, Al, Ga, Sc, Nb, V, W, Bi, Zn, Sn, P
  • Another aspect of the present disclosure is directed to a composition obtained or obtainable by the method of the above aspect.
  • Another aspect of the present disclosure is directed to a method of manufacturing a composition comprising a ceria-zirconia mixed oxide, the ceria-zirconia mixed oxide being surface-modified with a perovskite type compound of formula (I); wherein formula (I) is defined by Ax-yA’yBi-zB’zCh; where: A is an ion of a metal selected from the group consisting of Li, Na, K, Cs, Mg, Sr, Ba, Ca, Y, La, Ce, Pr, Nd, and Gd; A’ is an ion of a metal selected from the group consisting of Li, Na, K, Cs, Mg, Sr, Ba, Ca, Y, La, Ce, Pr, Nd, and Gd; B is an ion of a metal selected from the group consisting of Cu, Mn, Mo, Co, Fe, Ni, Cr, Ti, Zr, Al, Ga, Sc, Nb, V, W, Bi, Zn, Sn, P
  • Another aspect of the present disclosure is directed to a composition obtained or obtainable by the method of the above aspect.
  • Another aspect of the present disclosure is directed to a method of manufacturing a composition comprising a ceria-zirconia mixed oxide, the ceria-zirconia mixed oxide being surface-modified with a perovskite type compound of formula (I); wherein formula (I) is defined by Ax-yA’yBi-zB’zCh; where: A is an ion of a metal selected from the group consisting of Li, Na, K, Cs, Mg, Sr, Ba, Ca, Y, La, Ce, Pr, Nd, and Gd; A’ is an ion of a metal selected from the group consisting of Li, Na, K, Cs, Mg, Sr, Ba, Ca, Y, La, Ce, Pr, Nd, and Gd; B is an ion of a metal selected from the group consisting of Cu, Mn, Mo, Co, Fe, Ni, Cr, Ti
  • Another aspect of the present disclosure is directed to a composition obtained or obtainable by the method of the above aspect.
  • Another aspect of the present invention is directed to a method of manufacturing a composition comprising a ceria-zirconia mixed oxide, the ceria-zirconia mixed oxide being surface-modified with a perovskite type compound of formula (I); wherein formula (I) is defined by Ax-yA’yBi-zB’zCh; where: A is an ion of a metal selected from the group consisting of Li, Na, K, Cs, Mg, Sr, Ba, Ca, Y, La, Ce, Pr, Nd, and Gd; A’ is an ion of a metal selected from the group consisting of Li, Na, K, Cs, Mg, Sr, Ba, Ca, Y, La, Ce, Pr, Nd, and Gd; B is an ion of a metal selected from the group consisting of Cu, Mn, Mo, Co, Fe, Ni, Cr, Ti, Zr, Al, Ga, Sc, Nb, V, W, Bi, Zn, Sn, P
  • Another aspect of the present disclosure is directed to a composition obtained or obtainable by the method of the above aspect.
  • Another aspect of the present disclosure is directed to a catalyst article comprising a substrate, the substrate having a composition of the invention disposed thereon.
  • the invention also encompasses an emission treatment system comprising the catalyst article described herein and a method of treating an exhaust gas, the method comprising: providing the catalyst article described herein; and contacting the catalyst article with an exhaust gas.
  • FIG. 1 shows a powder XRD pattern of 10% BaMnOs-modified CZO according to the Example Al.
  • FIG. 2 shows a powder XRD pattern of 10% Lao.yMnOs-modified CZO according to the Example A6.
  • FIG. 3 shows OSC conventional CZO, (A3) 10% BaMnOs-modified CZO, (A8) 10% Lao.pMnOs-modified CZO, (A10) 10% CaMnOs-modified CZO, and (Al 2) 10% LaFeOs- modified CZO.
  • FIG. 4a shows perturbated aged TWC light off performance for NO X conversions of washcoated (Bl) Reference Pd catalyst (aged) on single CZO support, and Pd catalysts (aged) on (B2) BaMnOs-type perovskite-modified CZO support.
  • FIG. 4b shows perturbated aged TWC light off performance for CO conversions of washcoated (Bl) Reference Pd catalyst (aged) on single CZO support, and Pd catalysts (aged) on (B2) BaMnOs-type perovskite-modified CZO support.
  • FIG. 4c shows perturbated aged TWC light off performance for THC conversions of washcoated (Bl) Reference Pd catalyst (aged) on single CZO support, and Pd catalysts (aged) on (B2) BaMnOs-type perovskite-modified CZO support.
  • FIG. 5a shows perturbated aged TWC light off performance for NO X conversions of washcoated (B3) Reference Rh catalyst (aged) on single CZO support, and Rh catalysts (aged) on (B4) Lao.pMnCh-, and (B5) LaFeCh- type perovskite-modified CZO supports.
  • FIG. 5b shows perturbated aged TWC light off performance for CO conversions of washcoated (B3) Reference Rh catalyst (aged) on single CZO support, and Rh catalysts (aged) on (B4) Lao.pMnOs-, and (B5) LaFeOs- type perovskite-modified CZO supports.
  • FIG. 5c shows perturbated aged TWC light off performance for THC conversions of washcoated (B3) Reference Rh catalyst (aged) on single CZO support, and Rh catalysts (aged) on (B4) Lao.pMnOs-, and (B5) LaFeOs- type perovskite-modified CZO supports.
  • FIG. 6a shows perturbated aged TWC light off performance for NO X conversions of washcoated (B6) reference Pd fully formulated catalyst (aged), and Pd catalysts (aged) with (B7) 10% BaMnOs-, and (B8) 10% LaFeO-, modified CZO-type perovskite-modified CZO supports.
  • FIG. 6b shows perturbated aged TWC light off performance for CO conversions of washcoated (B6) reference Pd fully formulated catalyst (aged), and Pd catalysts (aged) with (B7) 10% BaMnOs-, and (B8) 10% LaFeOs modified CZO-type perovskite-modified CZO supports.
  • FIG. 6c shows perturbated aged TWC light off performance for THC conversions of washcoated (B6) reference Pd fully formulated catalyst (aged), and Pd catalysts (aged) with (B7) 10% BaMnOs-, and (B8) 10% LaFeO-, modified CZO-type perovskite-modified CZO supports.
  • FIG. 7a shows perturbated aged TWC light off performance for NO X conversions of washcoated (B9) reference Pt (aged) fully formulated catalyst, and Pt catalysts (aged) with (B10) 20% CaMnOs-modified CZO support.
  • FIG. 7b shows perturbated aged TWC light off performance for CO conversions of washcoated (B9) reference Pt (aged) fully formulated catalyst, and Pt catalysts (aged) with (B10) 20% CaMnOs-modified CZO support.
  • FIG. 7c shows perturbated aged TWC light off performance for THC conversions of washcoated (B9) reference Pt (aged) fully formulated catalyst, and Pt catalysts (aged) with (BIO) 20% CaMnCh-modified CZO support.
  • FIG. 8a shows perturbated aged TWC light off performance for NO X conversions of washcoated (Bl l) reference RhPt (aged) fully formulated catalyst, and RhPt catalysts (aged) with (B12) 10% BaMnCh-, (B13) 10% Lao. 9 Mn0 3 -, and (B14) 10% CaMnCh- modified CZO supports.
  • FIG. 8b shows perturbated aged TWC light off performance for CO conversions of washcoated (Bl l) reference RhPt (aged) fully formulated catalyst, and RhPt catalysts (aged) with (B12) 10% BaMnO 3 -, (B13) 10% Lao. 9 Mn0 3 -, and (B14) 10% CaMnO 3 - modified CZO supports.
  • FIG. 8c shows perturbated aged TWC light off performance for THC conversions of washcoated (Bl l) reference RhPt (aged) fully formulated catalyst, and RhPt catalysts (aged) with (B12) 10% BaMnO 3 -, (B13) 10% Lao. 9 Mn0 3 -, and (B14) 10% CaMnO 3 - modified CZO supports.
  • the present invention seeks to tackle at least some of the problems associated with the prior art or at least to provide a commercially acceptable alternative solution thereto.
  • the present invention provides a composition comprising a ceriazirconia mixed oxide, the ceria-zirconia mixed oxide being surface-modified with a perovskite type compound of formula (I); wherein formula (I) is defined by Ax-yA’yBi- z B’zO 3 ; where:
  • A is an ion of a metal selected from the group consisting of Li, Na, K, Cs, Mg, Sr, Ba, Ca, Y, La, Ce, Pr, Nd, and Gd;
  • A’ is an ion of a metal selected from the group consisting of Li, Na, K, Cs, Mg, Sr, Ba, Ca, Y, La, Ce, Pr, Nd, and Gd;
  • B is an ion of a metal selected from the group consisting of Cu, Mn, Mo, Co, Fe, Ni, Cr, Ti, Zr, Al, Ga, Sc, Nb, V, W, Bi, Zn, Sn, Pt, Rh, Pd, Ru, Au, Ag, and Ir;
  • B’ is an ion of a metal selected from the group consisting of Cu, Mn, Mo, Co, Fe, Ni, Cr, Ti, Zr, Al, Ga, Sc, Nb, V, W, Bi, Zn, Sn, Pt, Rh, Pd, Ru, Au, Ag, and Ir;
  • x is from 0.7 to 1 ;
  • y is from 0 to 0.5; and
  • z is from 0 to 0.5.
  • a ceria-zirconia mixed oxide is a typical support material used in emission treatment catalysts, such as TWCs.
  • Ceria-zirconia mixed oxides are known to provide high surface area for active PGM metals and promoter species.
  • the ceria-zirconia mixed oxide may be referred to as “CZO” herein.
  • the relative ratio of Ce:Zr in the mixed oxide is not particularly limited for the purposes of this invention, i.e. it may be from 0 wt.% ceria to 100 wt.% ceria.
  • ceria-zirconia mixed oxide support with a perovskite-type compound can impart further or enhanced OSC properties to the ceria-zirconia mixed oxide, while still being able to retain most of its surface area at thermal ageing conditions.
  • This may advantageously also facilitate improved promotion of supported PGM species supported on the modified support (the composition of the invention), if present, in order to obtain improved TWC conversions.
  • Ceriazirconia mixed oxides are promising supports for perovskite type compounds due to their high surface area and inability to enter into the perovskite lattice with any of the most used cations, e.g. La, Ba, Sr, Co, Mn, or Fe.
  • surface-modified may encompass that the perovskite type compound is supported or coated on the ceria-zirconia mixed oxide, for example. That is, the perovskite type compound is physically and/or chemically attached to or supported on the surface of the ceria-zirconia mixed oxide, preferably in a (highly) dispersed form.
  • surface-modified does not encompass merely a physical blend or mixture of the bulk perovskite type compound and the ceria-zirconia mixed oxide. The perovskite type compound is not in bulk form in this sense.
  • surface-modified as used herein may also encompass that the perovskite type compound has smaller particle sizes than the ceria-zirconia mixed oxide.
  • surface-modified as used herein may also encompass that the ceriazirconia mixed oxide is in bulk form, and the perovskite type compound is dispersed on the surface and/or within the pores of the bulk ceria-zirconia mixed oxide.
  • the perovskite compound may be stabilised by the ceria-zirconia mixed oxide.
  • the drawbacks of bulk perovskite type compounds such as their low surface-area-to-volume ratio and their lack of stability at exhaust gas catalyst operating temperatures, may be mitigated, while imparting their advantageous OSC properties to the ceria-zirconia mixed oxide support.
  • the ceria-zirconia mixed oxide phase may act both as a support to provide high surface area and to stabilize the perovskite nanocrystalline phase (e.g. from sintering) at thermal ageing conditions.
  • Synergistic interactions between the dispersed perovskites and the supporting species (e.g. PGM and promoter) may also occur, which may lead to enhanced TWC performance.
  • the perovskite itself may also exhibit intrinsic activity for TWC reactions, facilitating the PGM performance, which may allow for potential reduction of PGM loading. There is a desire in the field to reduce the amount of PGM loading, due, inter alia, to costs.
  • the composition of the invention may be used in place of existing support materials, such as where ceria-zirconia mixed oxide is used as a support material in a known catalyst article, to provide OSC properties to the catalyst, or even to replace existing OSC support materials, such as ceria-zirconia support materials, which may lead to further and/or improved OSC properties.
  • existing support materials such as where ceria-zirconia mixed oxide is used as a support material in a known catalyst article
  • existing OSC support materials such as ceria-zirconia support materials
  • replacing conventional support materials with the composition of the invention can significantly decrease the T50 (the temperature at which 50% conversion is reached) of conversion for NO X , CO and/or THC (total hydrocarbon) abatement.
  • the present inventors have surprisingly been able to utilise the OSC benefits of perovskite type compounds for use in emission treatment catalysts, while at least partially mitigating the drawbacks and instability of such compounds in bulk form at the operating temperatures of the catalysts, e.g. TWCs.
  • perovskite as used herein takes on its usual meaning in the art, i.e. a perovskite type compound may refer to the class of compounds which have a similar or distorted type of crystal structure to CaTiO,.
  • composition and/or perovskite type compound of formula (I) may comprise inevitable impurities, typically less than 1 wt.%, preferably less than 0.5 wt.%, more preferably less than 0.1 wt.%.
  • the composition consists of a ceria-zirconia mixed oxide, the ceria-zirconia mixed oxide being surface-modified with a perovskite type compound of formula (I).
  • a and/or A’ is an ion of a metal selected from the group consisting of Ca, Mg, Ba, Ca, Y, La, Sr, Nd, Ce and Gd, more preferably A and/or A’ is an ion of a metal selected from the group consisting of Ca, Ba, La and Sr.
  • B and/or B’ is an ion of a metal selected from the group consisting of Mn, Co, Fe, Zr and Ni, more preferably, B and/or B’ is an ion of a metal selected from the group consisting of Mn, Zr, and Fe.
  • B and/or B’ is doped with PGM elements comprising one or more of Pt, Pd and Rh, i.e. B and/or B’ may further comprise, in addition to the preferred metals listed above, an ion of a metal selected from the group consisting of Pt, Pd and Rh.
  • PGM elements comprising one or more of Pt, Pd and Rh
  • B and/or B’ may further comprise, in addition to the preferred metals listed above, an ion of a metal selected from the group consisting of Pt, Pd and Rh.
  • Such compositions may be particularly suitable for use in the applications described herein, for example in a TWC.
  • x is from 0.8 to 1, more preferably from 0.9 to 1 or alternatively, but still preferred, from 0.7 to 0.9, more preferably from 0.8 to 0.9.
  • y is from 0 to 0.3, more preferably from 0 to 0.2, more preferably from greater than 0 to 0.2.
  • z is from 0 to 0.4, more preferably from 0 to 0.3, still more preferably from greater than 0 to 0.2.
  • Such compositions may be particularly suitable for use in the applications described herein, for example in a TWC.
  • Such compositions may be particularly suitable for use in the applications described herein, for example in a TWC.
  • z is 0.
  • y is 0.
  • z can be 0 when y > 0 and y can be 0 when z > 0.
  • compositions may be particularly suitable for use in the applications described herein, for example in a TWC.
  • x is 1.
  • Such compositions may be particularly suitable for use in the applications described herein, for example in a TWC.
  • the ceria-zirconia mixed oxide is doped. Suitable dopants are known in the art.
  • the ceria-zirconia mixed oxide is doped with an oxide of one or more of La, Ba, Sr, Mg, Mn, Y, Nd, Pr, Ti, Fe, Cu, Co, Zn, Si, Al, and Ni, more preferably La, Y, Nd and Pr.
  • Such doped ceria-zirconia mixed oxide may be particularly effective as a support material.
  • the dopant is present in the ceria-zirconia mixed oxide in an amount of from 0.001 wt.% to 20 wt.%, and more preferably from 0.5 wt.% to 10 wt.%, based on the total weight of ceria-zirconia mixed oxide.
  • the composition comprises from 1 to 50 wt.% of the perovskite type compound, based on the total weight of the perovskite type compound and the ceria-zirconia mixed oxide, preferably from 5 to 30 wt.%, more preferably from 5 to 25 wt.%, still more preferably from 10 to 20 wt.%.
  • the perovskite type compound may be highly dispersed on the ceria-zirconia mixed oxide, for example. Such a ratio of perovskite type compound may provide a particularly stable composition having improved OSC properties.
  • the ceria-zirconia mixed oxide is further surface-modified with a mixed oxide composite of formula (I). This may occur, for example, when phases other than the perovskite phase of formula (I) are present, such as due to incomplete formation of the perovskite phase during synthesis.
  • the present invention provides a method of manufacturing a composition comprising a ceria-zirconia mixed oxide, the ceria-zirconia mixed oxide being surface-modified with a perovskite type compound of formula (I); wherein formula (I) is defined by Ax-yA’yBi-zB’zCh; where:
  • A is an ion of a metal selected from the group consisting of Li, Na, K, Cs, Mg, Sr, Ba, Ca, Y, La, Ce, Pr, Nd, and Gd;
  • A’ is an ion of a metal selected from the group consisting of Li, Na, K, Cs, Mg, Sr, Ba, Ca, Y, La, Ce, Pr, Nd, and Gd;
  • B is an ion of a metal selected from the group consisting of Cu, Mn, Mo, Co, Fe, Ni,
  • B’ is an ion of a metal selected from the group consisting of Cu, Mn, Mo, Co, Fe, Ni,
  • Such a method may be considered as a (modified) Pechini method.
  • slurry as used herein may encompass a liquid comprising insoluble material, e.g. insoluble particles.
  • the slurry is typically stirred, more typically for at least 10 minutes, more typically for at least 30 minutes, even more typically for at least an hour.
  • Increased contacting and/or stirring times may increase the dispersion of the perovskite type compound on the ceria-zirconia mixed oxide.
  • Contacting the solution with a ceria-zirconia mixed oxide may typically comprise adding ceria-zirconia mixed oxide, for example in powder form, to the solution.
  • contacting the solution with a ceria-zirconia mixed oxide may comprise combining the solution with a slurry comprising ceria-zirconia mixed oxide, for example a ceria-zirconia mixed oxide powder in water.
  • the contacting step is not particularly limited in this regard.
  • the solution further comprises an organic solvent, preferably ethylene glycol.
  • the solution does not comprise an inorganic solvent, i.e. the solution is preferably an aqueous solution.
  • the one or more salts preferably comprise acetate, nitrate, oxynitrate, chloride, ammonium nitrate, hydroxide, oxalate and/or citrate salts, more preferably acetate, nitrate and/or oxynitrate salts.
  • heating the slurry comprises a first step of heating the slurry to a temperature of from 150 to 350 °C to form a gel.
  • gel as used herein may encompass a colloid in a more solid form than a sol or a thick, viscous slurry, for example. Without wishing to be bound by theory, this relatively low temperature heating may facilitate the evaporation of at least some of the water in the slurry to thicken the slurry and/or the formation of the perovskite type compound on the ceria-zirconia mixed oxide. More preferably, heating the slurry comprises a first step of heating the slurry to a temperature of from 200 to 300 °C, such as from 250 to 300 °C to form a gel.
  • heating the slurry comprises calcination, preferably after the heating step described above (i.e. comprising a first step of heating the slurry to a temperature of from 150 to 350 °C to form a gel).
  • calcination as used herein may encompass a thermal treatment process in the absence of, or limited supply of, air or oxygen to bring about a thermal decomposition or change.
  • calcination in the present context involves heating in air in an oven.
  • the calcination comprises heating at a temperature of from 300 to 500 °C, preferably from 350 to 450°C, for from 1 to 10 hours, preferably from 3 to 6 hours.
  • the calcination comprises heating at a temperature of from 600 to 1000 °C, preferably from 700 to 900 °C for from 1 to 8 hours, preferably from 2 to 5 hours. More preferably, the calcination comprises a first calcination step comprising heating at a temperature of from 300 to 500 °C, preferably from 350 to 450 °C, for from 1 to 10 hours, preferably from 3 to 6 hours, followed by a second calcination step comprising heating at a temperature of from 600 to 1000 °C, preferably from 700 to 900 °C, for from 1 to 8 hours, preferably from 2 to 5 hours.
  • the first, lower temperature, calcination step may facilitate the formation of a mixed oxide of the perovskite-precursor metals, i.e. forming a mixed oxide from the precursor salts
  • the second, higher temperature, calcination step may then facilitate the formation of a dense perovskite structure supported on the ceria-zirconia mixed oxide (i.e. a surface- modified ceria-zirconia mixed oxide).
  • the perovskite type compound is not in bulk form, but is supported on the surface of the ceria-zirconia mixed oxide.
  • the organic acid comprises a carboxylic acid, more preferably a di- or tricarboxylic acid.
  • the organic acid preferably comprises, or even consists of, citric acid, tannic acid, humic acid, succinic acid, EDTA, DTPA and/or other chelating agents, more preferably citric acid, tannic acid, humic acid, succinic acid, EDTA and/or DTPA, even more preferably citric acid.
  • the composition manufactured by the method of this aspect is the composition of the first aspect described herein.
  • the present invention provides a composition obtained or obtainable by the method of the above aspect.
  • ceria-zirconia mixed oxide support with a perovskite-type compound can impart further or enhanced OSC properties to the ceria-zirconia mixed oxide, while still being able to retain most of its surface area at thermal ageing conditions.
  • This may advantageously also facilitate improved promotion of supported PGM species supported on the modified support (the composition of the invention), if present, in order to obtain improved TWC conversions.
  • Ceriazirconia mixed oxides are promising supports for perovskite type compounds due to their high surface area and inability to enter into the perovskite lattice with any of the most used cations, e.g.
  • the perovskite compound may be stabilised by the ceria-zirconia mixed oxide.
  • the drawbacks of bulk perovskite type compounds such as their low surface-area-to-volume ratio and their lack of stability at exhaust gas catalyst operating temperatures, may be mitigated, while imparting their advantageous OSC properties to the ceria-zirconia mixed oxide support.
  • the ceria-zirconia mixed oxide phase may act both as a support to provide high surface area and to stabilize the perovskite nanocrystalline phase (e.g. from sintering) at thermal ageing conditions.
  • Synergistic interactions between the dispersed perovskites and the supporting species (e.g. PGM and promoter) may also occur, which may lead to enhanced TWC performance.
  • the perovskite itself may also exhibit intrinsic activity for TWC reactions, facilitating the PGM performance, which may allow for potential reduction of PGM loading. There is a desire in the field to reduce the amount of PGM loading, due, inter alia, to costs.
  • the composition of the invention may be used in place of existing support materials, such as where ceria-zirconia mixed oxide is used as a support material in a known catalyst article, to provide OSC properties to the catalyst, or even to replace existing OSC support materials, such as ceria-zirconia support materials, which may lead to further and/or improved OSC properties.
  • existing support materials such as where ceria-zirconia mixed oxide is used as a support material in a known catalyst article
  • existing OSC support materials such as ceria-zirconia support materials
  • replacing conventional support materials with the composition of the invention can significantly decrease the T50 (the temperature at which 50% conversion is reached) of conversion for NO X , CO and/or THC (total hydrocarbon) abatement.
  • the present inventors have surprisingly been able to utilise the OSC benefits of perovskite type compounds for use in emission treatment catalysts, while at least partially mitigating the drawbacks and instability of such compounds in bulk form at the operating temperatures of the catalysts, e.g. TWCs.
  • the same advantages as for the composition of the first aspect apply to the composition of this aspect.
  • the present invention provides a method of manufacturing a composition comprising a ceria-zirconia mixed oxide, the ceria-zirconia mixed oxide being surface-modified with a perovskite type compound of formula (I); wherein formula (I) is defined by Ax-yA’yBi-zB’zCh; where:
  • A is an ion of a metal selected from the group consisting of Li, Na, K, Cs, Mg, Sr, Ba, Ca, Y, La, Ce, Pr, Nd, and Gd;
  • A’ is an ion of a metal selected from the group consisting of Li, Na, K, Cs, Mg, Sr, Ba, Ca, Y, La, Ce, Pr, Nd, and Gd;
  • B is an ion of a metal selected from the group consisting of Cu, Mn, Mo, Co, Fe, Ni,
  • B’ is an ion of a metal selected from the group consisting of Cu, Mn, Mo, Co, Fe, Ni,
  • IW or IWI Incipient wetness impregnation
  • Contacting a ceria-zirconia mixed oxide with A, B, and optionally A’ and/or B’ using one or more salts of A, one or more salts of B and optionally one or more salts of A’ and/or one or more salts of B’ via incipient wetness impregnation may comprise impregnating a ceriazirconia mixed oxide with A, B, and optionally A’ and/or B’ using one or more salts of A, one or more salts of B and optionally one or more salts of A’ and/or one or more salts of B’ via incipient wetness impregnation, for example.
  • the one or more salts preferably comprise acetate, nitrate, oxynitrate, chloride, ammonium nitrate, hydroxide, oxalate and/or citrate salts, more preferably acetate, nitrate and/or oxynitrate salts.
  • heating the impregnated ceria-zirconia mixed oxide comprises a first step of drying the impregnated ceria-zirconia mixed oxide at a temperature of from 50 to 150 °C, preferably from 50 to 100 °C for from 1 hour to 24 hours, preferably 6 hours to 12 hours.
  • heating the impregnated ceria-zirconia mixed oxide comprises calcination, preferably after the heating step described above (i.e. comprising a first step of drying the impregnated ceria-zirconia mixed oxide at a temperature of from 50 to 150 °C, preferably from 50 to 100 °C for from 1 hour to 24 hours, preferably 6 hours to 12 hours).
  • the calcination comprises heating at a temperature of from 300 to 500 °C, preferably from 350 to 450 °C, for from 1 to 10 hours, preferably from 3 to 6 hours.
  • the calcination comprises heating at a temperature of from 600 to 1000 °C, preferably from 700 to 900 °C for from 1 to 8 hours, preferably from 2 to 5 hours. More preferably, the calcination comprises a first calcination step comprising heating at a temperature of from 300 to 500 °C, preferably from 350 to 450 °C, for from 1 to 10 hours, preferably from 3 to 6 hours, followed by a second calcination step comprising heating at a temperature of from 600 to 1000 °C, preferably from 700 to 900 °C, for from 1 to 8 hours, preferably from 2 to 5 hours.
  • the first, lower temperature, calcination step may facilitate the formation of a mixed oxide of the perovskite-precursor metals, i.e. forming a mixed oxide from the precursor salts
  • the second, higher temperature, calcination step may then facilitate the formation of a dense perovskite structure supported on the ceria-zirconia mixed oxide (i.e. a surface-modified ceriazirconia mixed oxide).
  • the perovskite type compound is not in bulk form, but may be supported on the surface of the ceria-zirconia mixed oxide in a dispersed state.
  • the composition manufactured by the method of this aspect is the composition of the first aspect described herein.
  • the present invention provides a composition obtained or obtainable by the method of the above aspect.
  • surface-modifying such a ceria-zirconia mixed oxide support with a perovskite-type compound can impart further or enhanced OSC properties to the ceria-zirconia mixed oxide, while still being able to retain most of its surface area at thermal ageing conditions. This may advantageously also facilitate improved promotion of supported PGM species supported on the modified support (the composition of the invention), if present, in order to obtain improved TWC conversions.
  • Ceriazirconia mixed oxides are promising supports for perovskite type compounds due to their high surface area and inability to enter into the perovskite lattice with any of the most used cations, e.g. La, Ba, Sr, Co, Mn, or Fe.
  • the perovskite compound may be stabilised by the ceria-zirconia mixed oxide.
  • the drawbacks of bulk perovskite type compounds such as their low surface-area-to-volume ratio and their lack of stability at exhaust gas catalyst operating temperatures, may be mitigated, while imparting their advantageous OSC properties to the ceria-zirconia mixed oxide support.
  • the ceria-zirconia mixed oxide phase may act both as a support to provide high surface area and to stabilize the perovskite nanocrystalline phase (e.g. from sintering) at thermal ageing conditions.
  • Synergistic interactions between the dispersed perovskites and the supporting species (e.g. PGM and promoter) may also occur, which may lead to enhanced TWC performance.
  • the perovskite itself may also exhibit intrinsic activity for TWC reactions, facilitating the PGM performance, which may allow for potential reduction of PGM loading. There is a desire in the field to reduce the amount of PGM loading, due, inter alia, to costs.
  • the composition of the invention may be used in place of existing support materials, such as where ceria-zirconia mixed oxide is used as a support material in a known catalyst article, to provide OSC properties to the catalyst, or even to replace existing OSC support materials, such as ceria-zirconia support materials, which may lead to further and/or improved OSC properties.
  • existing support materials such as where ceria-zirconia mixed oxide is used as a support material in a known catalyst article
  • existing OSC support materials such as ceria-zirconia support materials
  • replacing conventional support materials with the composition of the invention can significantly decrease the T50 (the temperature at which 50% conversion is reached) of conversion for NO X , CO and/or THC (total hydrocarbon) abatement.
  • the present inventors have surprisingly been able to utilise the OSC benefits of perovskite type compounds for use in emission treatment catalysts, while at least partially mitigating the drawbacks and instability of such compounds in bulk form at the operating temperatures of the catalysts, e.g. TWCs.
  • the same advantages as for the composition of the first aspect apply to the composition of this aspect.
  • the present invention provides a method of manufacturing a composition comprising a ceria-zirconia mixed oxide, the ceria-zirconia mixed oxide being surface-modified with a perovskite type compound of formula (I); wherein formula (I) is defined by Ax-yA’yBi-zB’zCh; where:
  • A is an ion of a metal selected from the group consisting of Li, Na, K, Cs, Mg, Sr, Ba, Ca, Y, La, Ce, Pr, Nd, and Gd;
  • A’ is an ion of a metal selected from the group consisting of Li, Na, K, Cs, Mg, Sr, Ba, Ca, Y, La, Ce, Pr, Nd, and Gd;
  • B is an ion of a metal selected from the group consisting of Cu, Mn, Mo, Co, Fe, Ni, Cr, Ti, Zr, Al, Ga, Sc, Nb, V, W, Bi, Zn, Sn, Pt, Rh, Pd, Ru, Au, Ag, and Ir;
  • B’ is an ion of a metal selected from the group consisting of Cu, Mn, Mo, Co, Fe, Ni, Cr, Ti, Zr, Al, Ga, Sc, Nb, V, W, Bi, Zn, Sn, Pt, Rh, Pd, Ru, Au, Ag, and Ir; x is from 0.7 to 1 ; y is from 0 to 0.5; and z is from 0 to 0.5, the method comprising: providing a solution comprising one or more salts of A, one or more salts of B and optionally one or more salts of A’ and/or one or more salts of B’; contacting the solution with a ceria-zirconia mixed oxide to form a slurry; spray drying the slurry to form a spray-dried powder; and heating the spray-dried powder. Spray drying is a well-known technique in the field. The skilled person would be able to perform an appropriate spray drying method without further direction.
  • Contacting the solution with a ceria-zirconia mixed oxide may typically comprise adding ceria-zirconia mixed oxide, for example in powder form, to the solution.
  • contacting the solution with a ceria-zirconia mixed oxide may comprise combining the solution with a slurry comprising ceria-zirconia mixed oxide, for example ceria-zirconia mixed oxide powder in water.
  • the contacting step is not particularly limited in this regard.
  • the one or more salts preferably comprise acetate, nitrate, oxynitrate, chloride, ammonium nitrate, hydroxide, oxalate and/or citrate salts, more preferably acetate, nitrate and/or oxynitrate salts.
  • the solution is an aqueous solution.
  • heating the spray-dried powder comprises calcination.
  • the calcination comprises heating at a temperature of from 300 to 500 °C, preferably from 350 to 450 °C, for from 1 to 10 hours, preferably from 3 to 6 hours.
  • the calcination comprises heating at a temperature of from 600 to 1000 °C, preferably from 700 to 900 °C for from 1 to 8 hours, preferably from 2 to 5 hours.
  • the calcination comprises a first calcination step comprising heating at a temperature of from 300 to 500 °C, preferably from 350 to 450 °C, for from 1 to 10 hours, preferably from 3 to 6 hours, followed by a second calcination step comprising heating at a temperature of from 600 to 1000 °C, preferably from 700 to 900 °C, for from 1 to 8 hours, preferably from 2 to 5 hours.
  • a first, lower temperature, calcination step may facilitate the formation of a mixed oxide of the perovskite-precursor metals, i.e.
  • the second, higher temperature, calcination step may then facilitate the formation of a dense perovskite structure supported on the ceria-zirconia mixed oxide (i.e. a surface-modified ceriazirconia mixed oxide).
  • a dense perovskite structure supported on the ceria-zirconia mixed oxide i.e. a surface-modified ceriazirconia mixed oxide.
  • the perovskite type compound is not in bulk form, but is supported on the surface of the ceria-zirconia mixed oxide.
  • the inlet temperature of the spray drying is from 100 to 300 °C, more preferably from 150 to 250 °C.
  • the inlet temperature is a well-known term within the field of spray drying.
  • the composition manufactured by the method of this aspect is the composition of the first aspect described herein.
  • the present invention provides a composition obtained or obtainable by the method of the above aspect.
  • ceria-zirconia mixed oxide support with a perovskite-type compound can impart further or enhanced OSC properties to the ceria-zirconia mixed oxide, while still being able to retain most of its surface area at thermal ageing conditions.
  • This may advantageously also facilitate improved promotion of supported PGM species supported on the modified support (the composition of the invention), if present, in order to obtain improved TWC conversions.
  • Ceriazirconia mixed oxides are promising supports for perovskite type compounds due to their high surface area and inability to enter into the perovskite lattice with any of the most used cations, e.g. La, Ba, Sr, Co, Mn, or Fe.
  • the perovskite compound may be stabilised by the ceria-zirconia mixed oxide.
  • the drawbacks of bulk perovskite type compounds such as their low surface-area-to-volume ratio and their lack of stability at exhaust gas catalyst operating temperatures, may be mitigated, while imparting their advantageous OSC properties to the ceria-zirconia mixed oxide support.
  • the ceria-zirconia mixed oxide phase may act both as a support to provide high surface area and to stabilize the perovskite nanocrystalline phase (e.g. from sintering) at thermal ageing conditions.
  • Synergistic interactions between the dispersed perovskites and the supporting species (e.g. PGM and promoter) may also occur, which may lead to enhanced TWC performance.
  • the perovskite itself may also exhibit intrinsic activity for TWC reactions, facilitating the PGM performance, which may allow for potential reduction of PGM loading. There is a desire in the field to reduce the amount of PGM loading, due, inter alia, to costs.
  • the composition of the invention may be used in place of existing support materials, such as where ceria-zirconia mixed oxide is used as a support material in a known catalyst article, to provide OSC properties to the catalyst, or even to replace existing OSC support materials, such as ceria-zirconia support materials, which may lead to further and/or improved OSC properties.
  • existing support materials such as where ceria-zirconia mixed oxide is used as a support material in a known catalyst article
  • existing OSC support materials such as ceria-zirconia support materials
  • replacing conventional support materials with the composition of the invention can significantly decrease the T50 (the temperature at which 50% conversion is reached) of conversion for NO X , CO and/or THC (total hydrocarbon) abatement.
  • the present inventors have surprisingly been able to utilise the OSC benefits of perovskite type compounds for use in emission treatment catalysts, while at least partially mitigating the drawbacks and instability of such compounds in bulk form at the operating temperatures of the catalysts, e.g. TWCs.
  • the same advantages as for the composition of the first aspect apply to the composition of this aspect.
  • the present invention provides a method of manufacturing a composition comprising a ceria-zirconia mixed oxide, the ceria-zirconia mixed oxide being surface-modified with a perovskite type compound of formula (I); wherein formula (I) is defined by Ax-yA’yBi-zB’zCh; where:
  • A is an ion of a metal selected from the group consisting of Li, Na, K, Cs, Mg, Sr, Ba, Ca, Y, La, Ce, Pr, Nd, and Gd;
  • A’ is an ion of a metal selected from the group consisting of Li, Na, K, Cs, Mg, Sr, Ba, Ca, Y, La, Ce, Pr, Nd, and Gd;
  • B is an ion of a metal selected from the group consisting of Cu, Mn, Mo, Co, Fe, Ni,
  • B’ is an ion of a metal selected from the group consisting of Cu, Mn, Mo, Co, Fe, Ni,
  • Contacting the solution with a ceria-zirconia mixed oxide may typically comprise adding ceria-zirconia mixed oxide, for example in powder form, to the solution.
  • contacting the solution with a ceria-zirconia mixed oxide may comprise combining the solution with a slurry comprising a ceria-zirconia mixed oxide, for example ceria-zirconia mixed oxide powder in water.
  • the contacting step is not particularly limited in this regard.
  • the one or more salts preferably comprise acetate, nitrate, oxynitrate, chloride, ammonium nitrate, hydroxide, oxalate and/or citrate salts, more preferably acetate, nitrate and/or oxy nitrate salts.
  • the method comprises contacting the slurry with a base.
  • contacting the slurry with a base comprises contacting the slurry with a solution comprising the base, preferably an aqueous solution comprising the base.
  • a solution comprising the base preferably an aqueous solution comprising the base.
  • Such a method may be referred to as a “co-precipitation” method.
  • the method may further comprise filtering and/or washing the ceria-zirconia mixed oxide after addition of the base (i.e. with the precipitated content thereon) and prior to heating the solid residue.
  • Recovering a solid residue from the slurry may encompass filtering the slurry to obtain a solid residue.
  • the term “solid residue” as used herein may encompass a filter cake, for example. Such a filter cake is well known in the art.
  • heating the solid residue comprises a first step of drying the solid residue at a temperature of from 50 to 150 °C, preferably from 50 to 100 °C for from 1 hour to 24 hours, preferably 6 hours to 12 hours.
  • the calcination comprises heating at a temperature of from 300 to 500 °C, preferably from 350 to 450 °C, for from 1 to 10 hours, preferably from 3 to 6 hours.
  • the calcination comprises heating at a temperature of from 600 to 1000 °C, preferably from 700 to 900 °C for from 1 to 8 hours, preferably from 2 to 5 hours.
  • the calcination comprises a first calcination step comprising heating at a temperature of from 300 to 500 °C, preferably from 350 to 450 °C, for from 1 to 10 hours, preferably from 3 to 6 hours, followed by a second calcination step comprising heating at a temperature of from 600 to 1000 °C, preferably from 700 to 900 °C, for from 1 to 8 hours, preferably from 2 to 5 hours.
  • a first, lower temperature, calcination step may facilitate the formation of a mixed oxide of the perovskite-precursor metals, i.e.
  • forming a mixed oxide from the precursor salts, and the second, higher temperature, calcination step may then facilitate the formation of a dense perovskite structure supported on the ceria-zirconia mixed oxide (i.e. a surface- modified ceria-zirconia mixed oxide).
  • a dense perovskite structure supported on the ceria-zirconia mixed oxide i.e. a surface- modified ceria-zirconia mixed oxide.
  • the perovskite type compound is not in bulk form, but may be supported on the surface of the ceria-zirconia mixed oxide in a dispersed state.
  • the base comprises ammonium hydroxide.
  • recovering a solid residue from the slurry comprises filtering the slurry to obtain a solid residue and washing the solid residue with water, preferably excess water.
  • the composition manufactured by the method of this aspect is the composition of the first aspect described herein.
  • the present invention provides a composition obtained or obtainable by the method of the above aspect.
  • ceria-zirconia mixed oxide support with a perovskite-type compound can impart further or enhanced OSC properties to the ceria-zirconia mixed oxide, while still being able to retain most of its surface area at thermal ageing conditions.
  • This may advantageously also facilitate improved promotion of supported PGM species supported on the modified support (the composition of the invention), if present, in order to obtain improved TWC conversions.
  • Ceriazirconia mixed oxides are promising supports for perovskite type compounds due to their high surface area and inability to enter into the perovskite lattice with any of the most used cations, e.g. La, Ba, Sr, Co, Mn, or Fe.
  • the perovskite compound may be stabilised by the ceria-zirconia mixed oxide.
  • the drawbacks of bulk perovskite type compounds such as their low surface-area-to-volume ratio and their lack of stability at exhaust gas catalyst operating temperatures, may be mitigated, while imparting their advantageous OSC properties to the ceria-zirconia mixed oxide support.
  • the ceria-zirconia mixed oxide phase may act both as a support to provide high surface area and to stabilize the perovskite nanocrystalline phase (e.g. from sintering) at thermal ageing conditions.
  • Synergistic interactions between the dispersed perovskites and the supporting species (e.g. PGM and promoter) may also occur, which may lead to enhanced TWC performance.
  • the perovskite itself may also exhibit intrinsic activity for TWC reactions, facilitating the PGM performance, which may allow for potential reduction of PGM loading. There is a desire in the field to reduce the amount of PGM loading, due, inter alia, to costs.
  • the composition of the invention may be used in place of existing support materials, such as where ceria-zirconia mixed oxide is used as a support material in a known catalyst article, to provide OSC properties to the catalyst, or even to replace existing OSC support materials, such as ceria-zirconia support materials, which may lead to further and/or improved OSC properties.
  • existing support materials such as where ceria-zirconia mixed oxide is used as a support material in a known catalyst article
  • existing OSC support materials such as ceria-zirconia support materials
  • replacing conventional support materials with the composition of the invention can significantly decrease the T50 (the temperature at which 50% conversion is reached) of conversion for NO X , CO and/or THC (total hydrocarbon) abatement.
  • the present inventors have surprisingly been able to utilise the OSC benefits of perovskite type compounds for use in emission treatment catalysts, while at least partially mitigating the drawbacks and instability of such compounds in bulk form at the operating temperatures of the catalysts, e.g. TWCs.
  • the same advantages as for the composition of the first aspect apply to the composition of this aspect.
  • the present invention provides a catalyst article comprising a substrate, the substrate having the composition described herein disposed thereon.
  • catalyst article used herein may encompass an article in which a catalyst is supported thereon or therein.
  • the article may take the form of, for example, a honeycomb monolith, or a filter, e.g. a wall flow filter or a flow-through filter.
  • substrate may encompass, for example, a ceramic or metallic honeycomb, or a filter block, e.g. a wall flow filter or flow-through filter.
  • the substrate may comprise a ceramic monolithic substrate.
  • the substrate may vary in its material composition, size and configuration, cell shape and density, and wall thickness. Suitable substrates are known in the art.
  • disposed thereon in the context of this aspect may encompass both having the composition directly disposed on the substrate, i.e. with no intervening material, and/or indirectly disposed on the substrate, i.e. with intervening material. If the substrate is porous, then the term “disposed thereon” may also encompass having the composition disposed therein, for example within the pores of the substrate, i.e. wherein the composition is disposed thereon and/or therein. In other words, the composition described herein may be incorporated into one or more washcoat regions, zones or layers disposed in any order on the substrate.
  • Such substrate-washcoat formulations are well-known in the field.
  • washcoat as used herein is well-known in the field and refers to an adherent coating that is applied to a substrate usually during the production of a catalyst.
  • the catalyst article is for treating exhaust gas.
  • the catalyst article comprises a three-way catalyst (TWC), more preferably the catalyst article is a TWC.
  • a platinum group metal is supported on the composition.
  • the PGM may be supported on the surface and/or within the pores of the ceria-zirconia mixed oxide.
  • the PGM may also be supported on the perovskite type compound.
  • the PGM may be located at a boundary between the ceria-zirconia mixed oxide and the perovskite type compound supported thereon. Without wishing to be bound by theory, it is thought that the presence of the perovskite type compound may further promote the catalytic activity of the PGM as well as increasing the resistance of the PGM nanoparticles to sintering. PGM sintering may lower the catalytic activity of the PGM.
  • PGM as used herein encompasses one or more platinum group metals selected from ruthenium, rhodium, palladium, osmium, iridium, and platinum.
  • the PGM comprises Pt, Pd, Rh, or a mixture or alloy thereof. Such metals may be particularly suitable for carrying out three-way catalysis.
  • the PGM may be in the form of an alloy.
  • the catalyst article is for use in an emission treatment system.
  • the catalyst article is for three-way catalysis.
  • the catalyst article has a washcoat loading of from 1 g/in 3 to 3 g/in 3 .
  • the substrate comprises a wall flow filter substrate.
  • the substrate comprises a flow-through substrate.
  • the catalyst article comprises a bottom layer of support material having rhodium thereon and a top layer of support material having palladium thereon.
  • the catalyst article comprises a bottom layer of support material having palladium thereon and a top layer of support material having rhodium thereon.
  • the support material may comprise any suitable known support material.
  • the support material comprises the composition described herein. That is, the support material present in the bottom layer and/or the top layer may comprise the composition described herein.
  • the catalyst article preferably comprises from 2 g/ft 3 to 15 g/ft 3 rhodium, more preferably from 3 g/ft 3 to 10 g/ft 3 rhodium.
  • the catalyst article preferably comprises from 20 g/ft 3 to 200 g/ft 3 palladium, more preferably from 30 g/ft 3 to 150 g/ft 3 palladium.
  • the catalyst article preferably comprises from 2 g/ft 3 to 200 g/ft 3 platinum, preferably from 10 g/ft 3 to 100 g/ft 3 platinum.
  • the present invention provides an emission treatment system comprising the catalyst article described herein.
  • the emission treatment system is for a gasoline engine.
  • the gasoline engine operates under stoichiometric conditions.
  • the present invention provides a method of treating an exhaust gas, the method comprising: providing the catalyst article described herein; and contacting the catalyst article with an exhaust gas.
  • the exhaust gas is from a gasoline engine.
  • the gasoline engine operates under stoichiometric conditions.
  • Example Al Synthesis of 10 wt% BaMnCh modified CZO by Pechini method
  • the resulting slurry was slowly heated to 275 °C and continuously stirred until a gel was formed.
  • Example A2 Synthesis of 10 wt% BaMnCh modified CZO by aqueous method
  • the resulting slurry was heated to 275 °C and continuously stirred until a gel was formed. 5. After the gel was cooled to room temperature, it was transferred to a big crucible, and covered with alumina foil (with holes on the cover).
  • Example A3 Synthesis of 10 wt% BaMnCh modified CZO by incipient wetness impregnation method
  • the resulting impregnated CZO was dried at 80 °C for 1 hr, and mixed periodically to prevent wicking.
  • Example A4 Synthesis of 10 wt% BaMnOs modified CZO by spray drying method
  • CZO powder (1009 g) was added to the above solution, target solid content of 30%, with mechanical mixing for at least 1 hr to make a slurry.
  • the slurry was spray dried while ensuring sufficient mixing of the slurry during the whole spray drying process.
  • the spray dried powder was collected and calcined in a static oven at 400 °C/4h, followed by 800 °C/4h.
  • Example A5-A13 Synthesis procedures for Example A5-A13 were similar to Examples Al- A4, with the main precursor amounts summarized in the following Table 1.
  • the impregnated CZO was dried at 80 °C for 1 hr, and mixed periodically to prevent wicking, before calcining at 500 °C for 30 min in static air.
  • a slurry was prepared with DI water, and appropriate amount of binder and thickening agent for a final batch solid of 22%. The slurry was mixed vigorously with VWR vortex mixer until homogeneous.
  • the brick was fired at 500 °C for 30 min in a static oven.
  • Example B2 3 wt% Pd/10% BMP modified CZO washcoated catalyst
  • the impregnated CZO was dried at 80 °C for 1 hr, and mixed periodically to prevent wicking, before calcining at 500 °C for 30 min in static air
  • a slurry was prepared with DI water, and appropriate amount of binder and thickening agent for a final batch solid of 22%. The slurry was mixed vigorously with VWR vortex mixer till homogeneous.
  • the brick was fired at 500 °C for 30 min in a static oven.
  • Examples B3-B5 Catalyst preparation procedures for Examples B3- B5 were similar to Example Bl and B2, with the main precursor amounts summarized in the following Table 2.
  • a solution was prepared with the required amount of Pd nitrate (with Pd loading 100 g/ft 3 ).
  • the brick was fired at 500 °C for 30 min in a static oven.
  • Example B7 Fully formulated single layer Pd washcoat with 10%BMQ modified CZO
  • a solution was prepared with the required amount of Pd nitrate (with Pd loading 100 g/ft 3 ).
  • the brick was fired at 500 °C for 30 min in a static oven.
  • Example B8 Fully formulated single layer Pd washcoat with 10%LFQ modified CZO
  • a solution was prepared with the required amount of Pd nitrate (with Pd loading 100 g/ft 3 ).
  • the brick was fired at 500 °C for 30 min in a static oven.
  • a solution was prepared with the required amount of Pt nitrate (with Pt loading 20 g/ft 3 ).
  • Example BIO Fully formulated single layer Pt washcoat with 20%CMQ modified CZO
  • a solution was prepared with the required amount of Pt nitrate (with Pt loading 20 g/ft 3 ).
  • the brick was fired at 500 °C for 30 min in a static oven.
  • Rh nitrate (with Rh loading 3.6 g/ft 3 ) was added to a slurry of CZO (1.1 g/in 3 ), and mixed for at least 15 min.
  • the pH was adjusted to > 6 with ammonia; before mixing for at least 1 hour.
  • Example B12 Fully formulated single layer RhPt washcoat with 10%BMQ modified CZO
  • Rh nitrate (with Rh loading 3.6 g/ft 3 ) was added to a slurry of 10% BaMnO, modified CZO (A3, 1.1 g/in 3 ), and mixed for at least 15 min.
  • the pH was adjusted to > 6 with ammonia; before mixing for at least 1 hour.
  • the brick was fired at 500 °C for 30 min in a static oven.
  • Example B13 Fully formulated single layer RhPt washcoat with 10%LMQ modified CZO
  • Rh nitrate (with Rh loading 3.6 g/ft 3 ) was added to a slurry of 10% Lao.yMnO-, modified CZO (A8, 1.1 g/in 3 ), and mixed for at least 15 min.
  • the pH was adjusted to > 6 with ammonia; before mixing for at least 1 hour.
  • Example B14 Fully formulated single layer RhPt washcoat with 10%CMQ modified CZO
  • Rh nitrate (with Rh loading 3.6 g/ft 3 ) was added to a slurry of 10% CaMnCh modified CZO (A10, 1.1 g/in 3 ), and mixed for at least 15 min.
  • the pH was adjusted to > 6 with ammonia; before mixing for at least 1 hour.
  • the brick was fired at 500 °C for 30 min in a static oven.
  • FIG. 1 shows a powder XRD pattern of 10% BaMnO 3 -modified CZO according to the Example Al.
  • FIG. 2 shows a powder XRD pattern of 10% Lao.yMnOs-modified CZO according to the Example A6. Both perovskite phases were highly dispersed and were detected by XRD.
  • FIG. 3 shows OSC of selected perovskite-modified CZO samples. After surface modification with the perovskite phases, the total OSC of CZO support was significantly improved. In particular, samples including conventional CZO, (A3) 10% BaMnO 3 -modified CZO, (A8) 10% Lao.9Mn0 3 -modified CZO, (A10) 10% CaMnO 3 -modified CZO, and (A12) 10% LaFeO 3 -modified CZO were tested. During the OSC measurement, a powder sample was pre-oxidized at each temperature, and CO was subsequently flowed through the sample, when CO was converted to CO2 by the oxygen species donated from the powder sample.
  • the total OSC of the solid sample therefore corresponds to the amount of CO2 produced per gram of sample.
  • Low temperature ( ⁇ 350 °C) OSC of these modified CZO samples reached as high as 0.25 to 0.8 mmol CO2 prod./g, while high temperature (> 500 °C) OSC of these samples reached as high as 0.75 to 0.95 mmol CO2 prod./g.
  • FIG. 4a, FIG. 4b and FIG. 4c respectively, show TWC light off performance (NO X conversion, CO conversion and THC conversion) of single CZO vs. modified CZO supported Pd catalysts.
  • the modified support was synthesized via Pechini method. Compared to the reference catalyst, improvements in TWC conversions were shown with the BaMnO-, perovskite-modified support, especially with NO X conversion.
  • FIG. 5a, FIG. 5b and FIG. 5c respectively, show TWC light off performance (NO X conversion, CO conversion and THC conversion) of single CZO vs. modified CZO supported Rh catalysts.
  • the figures show perturbated aged TWC light off performance for (a) NO X , (b) CO, and (c) THC conversions of washcoated (B3) Reference Rh catalyst (aged) on single CZO support, and Rh catalysts (aged) on (B4) Lao.pMnOs-, and (B5) LaFeOs- type perovskite-modified CZO supports.
  • the modified supports were synthesized via incipient wetness impregnation method. Compared to the reference catalyst, pronounced improvements in TWC conversions were shown with perovskite-modified supports.
  • FIG. 6a, FIG. 6b and FIG. 6c respectively, show TWC light off performance (NO X conversion, CO conversion and THC conversion) of fully formulated Pd catalysts with perovskite-modified supports vs a reference Pd catalyst.
  • the figures show perturbated aged TWC light off performance for (a) NO X , (b) CO, and (c) THC conversions of washcoated (B6) reference Pd fully formulated catalyst (aged), and Pd catalysts (aged) with (B7) 10% BaMnOs-, and (B8) 10% LaFeOs modified CZO-type perovskite-modified CZO supports.
  • FIG. 7a, FIG. 7b and FIG. 7c respectively, show TWC light off performance (NO X conversion, CO conversion and THC conversion) of fully formulated Pt catalysts with perovskite-modified supports vs a reference Pt catalyst.
  • the figures show perturbated aged TWC light off performance for (a) NO X , (b) CO, and (c) THC conversions of washcoated (B9) reference Pt (aged) fully formulated catalyst, and Pt catalysts (aged) with (B10) 20% CaMnO 3 -modified CZO support.
  • significant improvements in TWC conversions were shown with selected perovskite-modified support.
  • FIG. 8a, FIG. 8b and FIG. 8c respectively, show TWC light off performance (NO X conversion, CO conversion and THC conversion) of fully formulated RhPt bimetallic catalysts with perovskite-modified support vs a reference RhPt catalyst.
  • the figures show perturbated aged TWC light off performance for (a) NO X , (b) CO, and (c) THC conversions of washcoated (Bl l) reference RhPt (aged) fully formulated catalyst, and RhPt catalysts (aged) with (B12) 10% BaMnO 3 -, (B13) 10% Lao. 9 Mn0 3 -, and (B14) 10% CaMnO 3 - modified CZO supports.

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