Surface modified ceria-zirconia mixed oxide compounds for gasoline exhaust applications

Abstract

A composition is provided comprising a ceria-zirconia mixed oxide, the ceria-zirconia mixed oxide being surface-modified with a perovskite compound of formula (I), x-y A' y B 1-z B' z O3, 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, B' is an ion of a metal selected from the group consisting of 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 0.7 to 1, y is 0 to 0.5, and z is 0 to 0.5.

Description

[Technical field]

[0001] The present invention relates to compositions comprising ceria-zirconia mixed oxides surface modified with a perovskite-type compound, methods for producing such compositions, compositions obtained or obtainable by such methods, catalytic articles, emission treatment systems and methods for treating exhaust gases. [Background technology]

[0002] Three-way catalysts (TWCs) are used to separate CO, HC, and NO from the exhaust of gasoline engines at a stoichiometric air-fuel ratio. x to harmless compounds (about 98%). Specifically, the oxidation of CO and HC to CO2 and water vapor (HO) is primarily catalyzed by Pd, while NO x The reduction of N2 to N2 is primarily catalyzed by Rh. Modern TWCs use supported platinum group metal (PGM) catalysts (Pd, Rh, Pt, etc.) deposited on single, bi- or multi-layer supports, with the support material consisting of high surface area metal oxides, primarily stabilized alumina, and ceria-containing oxygen storage materials. The supported catalysts are washcoated onto ceramic monolith substrates.

[0003] Ce 4+ / Ce 3+ Cerium oxide (CeO2) is known for its high oxygen storage capacity (OSC) due to its redox couple function. x O y ) plays an important role in TWC performance. Ce x O y In addition to providing a high surface area for PGM metal dispersion, Ce can also assist in the feedback control of stoichiometric conditions by incorporating or donating oxygen during fuel lean / rich perturbation. x O y When zirconium oxide (ZrO2) is further incorporated into the fluorite structure (denoted as CZO), Cex O y The thermal stability of the OSC is improved and the formation of oxygen vacancies enhances the mobility of lattice oxygen. Other unique elements (Y, Nd, La, Pr, etc.) are also added to the OSC formulation to further enhance the TWC performance.

[0004] ABO 3-δ Perovskite-type materials are known in the art and can exhibit significant variation in oxygen non-stoichiometry δ through reaction with gas-phase oxygen. Perovskites with improved composition also exhibit OSC capacity and intrinsic TWC activity. In general, the OSC and catalytic activity of perovskite oxides are highly dependent on the nature of the B-site cations, while A-site cations have been found to be important in perovskite structure formation by influencing vacancy density and charge-valence balance. Oxygen uptake and release has been associated with the presence of structural defects and changes in the oxidation state of the B-site cations. At temperatures below 600°C, surface oxygen species (α) are adsorbed on the oxide surface, while at higher temperatures, bulk oxygen from the lattice, called interfacial oxygen (β), is activated and participates in catalytic reactions via the Mars-van-Krevelen mechanism. Furthermore, incorporation of PGM metals into the perovskite structure has been reported to result in "intelligent catalysis" (PGM migration between bulk and surface under redox conditions), which could potentially alleviate metal sintering in harsh automotive conditions.

[0005] However, the main limitations of using perovskites for emission reduction stem from their reduced ability to develop large surface areas (i.e., they have low surface-to-volume ratios). Furthermore, they sinter dramatically above 600 °C and can also undergo phase transformations / separations under redox conditions. Summary of the Invention

[0006] One aspect of the present disclosure relates to a composition comprising a ceria-zirconia mixed oxide, the ceria-zirconia mixed oxide being surface-modified with a perovskite compound of formula (I), x-y A'y B 1-z B' z O3, 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, B' is an ion of a metal selected from the group consisting of 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 0.7 to 1, y is 0 to 0.5, and z is 0 to 0.5.

[0007] Another aspect of the present disclosure relates to a method for producing a composition comprising a ceria-zirconia mixed oxide, the ceria-zirconia mixed oxide being surface-modified with a perovskite compound of formula (I), x-y A' y B 1-z B' zO3, in which 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; wherein A is an ion of a metal selected from the group consisting of 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 between 0.7 and 1, y is between 0 and 0.5, and z is between 0 and 0.5, and the method comprises providing a solution comprising an organic acid, water, 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, and heating the slurry.

[0008] Another aspect of the present disclosure relates to a composition obtained or obtainable by the method of the above aspect.

[0009] Another aspect of the present disclosure relates to a method for producing a composition comprising a ceria-zirconia mixed oxide, the ceria-zirconia mixed oxide being surface-modified with a perovskite compound of formula (I), x-y A' y B 1-z B' zO3, in which 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; wherein r is an ion of a metal selected from the group consisting of 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 contacting a ceria-zirconia mixed oxide with A, B, and optionally A' and / or B' by incipient wetness impregnation 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' to form an impregnated ceria-zirconia mixed oxide, and heating the impregnated ceria-zirconia mixed oxide.

[0010] Another aspect of the present disclosure relates to a composition obtained or obtainable by the method of the above aspect.

[0011] Another aspect of the present disclosure relates to a method for producing a composition comprising a ceria-zirconia mixed oxide, the ceria-zirconia mixed oxide being surface-modified with a perovskite compound of formula (I), x-y A' y B 1-z B' zO3, in which 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, and x is an ion of a metal selected from the group consisting of Cr, Ti, Zr, Al, Ga, Sc, Nb, V, W, Bi, Zn, Sn, Pt, Rh, Pd, Ru, Au, Ag, and Ir, x is between 0.7 and 1, y is between 0 and 0.5, and z is between 0 and 0.5, and the method comprises 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.

[0012] Another aspect of the present disclosure relates to a composition obtained or obtainable by the method of the above aspect.

[0013] Another aspect of the present invention relates to a method for producing a composition comprising a ceria-zirconia mixed oxide, the ceria-zirconia mixed oxide being surface-modified with a perovskite compound of formula (I), x-y A' y B 1-z B' zO3, in which 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, and x is an ion of a metal selected from the group consisting of 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 includes providing an aqueous solution containing 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, contacting the slurry with a base, recovering a solid residue from the slurry, and heating the solid residue.

[0014] Another aspect of the present disclosure relates to a composition obtained or obtainable by the method of the above aspect.

[0015] Another aspect of the present disclosure relates to a catalytic article comprising a substrate having a composition of the present invention disposed thereon.

[0016] The present invention also includes an emission treatment system including the catalytic article described herein and a method of treating an exhaust gas, the method including providing a catalytic article described herein and contacting the catalytic article with an exhaust gas. [Brief description of the drawings]

[0017] [Figure 1] FIG. 1 is a powder XRD pattern of 10% BaMnO3 modified CZO according to Example A1. [Diagram 2]FIG. 1 is a powder XRD pattern of 10% La0.9MnO3 modified CZO according to Example A6. [Diagram 3] FIG. 1 shows the OSCs of conventional CZO, (A3) 10% BaMnO3 modified CZO, (A8) 10% La0.9MnO3 modified CZO, (A10) 10% CaMnO3 modified CZO, and (A12) 10% LaFeO3 modified CZO. [Figure 4a] FIG. 14 shows the perturbation aged TWC light-off performance versus NOx conversion of washcoated (B1) (aged) reference Pd catalyst on a plain CZO support, and (B2) (aged) Pd catalyst on a BaMnO3-type perovskite modified CZO support. [Figure 4b] FIG. 14 shows the perturbation aged TWC light-off performance versus CO conversion of washcoated (B1) (aged) reference Pd catalyst on a plain CZO support, and (B2) (aged) Pd catalyst on a BaMnO3-type perovskite modified CZO support. [Figure 4c] FIG. 14 shows the perturbation aged TWC light-off performance versus THC conversion for washcoated (B1) (aged) reference Pd catalyst on a plain CZO support, and (B2) (aged) Pd catalyst on a BaMnO3-type perovskite modified CZO support. [Figure 5a] Figure 14 shows the perturbation aged TWC light-off performance versus NOx conversion of washcoated (B3) (aged) reference Rh catalyst on a plain CZO support, (B4) (aged) Rh catalyst on a La0.9MnO3-type perovskite modified CZO support, and (B5) (aged) Rh catalyst on a LaFeO3-type perovskite modified CZO support. [Figure 5b]Figure 14 shows the perturbation aged TWC light-off performance versus CO conversion for washcoated (B3) (aged) reference Rh catalyst on a plain CZO support, (B4) (aged) Rh catalyst on a La0.9MnO3-type perovskite modified CZO support, and (B5) (aged) Rh catalyst on a LaFeO3-type perovskite modified CZO support. [Figure 5c] Figure 14 shows the perturbation aged TWC light-off performance versus THC conversion for washcoated (B3) (aged) reference Rh catalyst on a plain CZO support, (B4) (aged) Rh catalyst on a La0.9MnO3-type perovskite modified CZO support, and (B5) (aged) Rh catalyst on a LaFeO3-type perovskite modified CZO support. [Figure 6a] Figure 13 shows the perturbation aged TWC light-off performance versus NOx conversion for washcoated (B6) (aged) reference Pd fully formulated catalyst, (B7) (aged) Pd catalyst with 10% BaMnO3 modified CZO-type perovskite modified CZO support, and (B8) (aged) Pd catalyst with 10% LaFeO3 modified CZO-type perovskite modified CZO support. [Figure 6b] Figure 13 shows the perturbation aged TWC light-off performance versus CO conversion for washcoated (B6) (aged) reference Pd fully formulated catalyst, (B7) (aged) Pd catalyst with 10% BaMnO3 modified CZO-type perovskite modified CZO support, and (B8) (aged) Pd catalyst with 10% LaFeO3 modified CZO-type perovskite modified CZO support. [Figure 6c]Figure 14 shows the perturbation aged TWC light-off performance versus THC conversion for washcoated (B6) (aged) reference Pd fully formulated catalyst, (B7) (aged) Pd catalyst with 10% BaMnO3 modified CZO-type perovskite modified CZO support, and (B8) (aged) Pd catalyst with 10% LaFeO3 modified CZO-type perovskite modified CZO support. [Figure 7a] FIG. 13 shows the perturbation aged TWC light-off performance versus NOx conversion of washcoated (B9) (aged) reference Pt fully formulated catalyst, and (B10) (aged) Pt catalyst with 20% CaMnO3 modified CZO support. [Figure 7b] FIG. 13 shows the perturbation aged TWC light-off performance versus CO conversion of washcoated (B9) (aged) reference Pt fully formulated catalyst, and (B10) (aged) Pt catalyst with 20% CaMnO3 modified CZO support. [Figure 7c] FIG. 14 shows perturbation aged TWC light-off performance versus THC conversion for washcoated (B9) (aged) reference Pt fully formulated catalyst, and (B10) (aged) Pt catalyst with 20% CaMnO3 modified CZO support. [Figure 8a] FIG. 13 shows the perturbation aged TWC light-off performance versus NOx conversion for washcoated (B11) (aged) reference RhPt fully formulated catalyst, (B12) (aged) RhPt catalyst with 10% BaMnO3 modified CZO support, (B13) (aged) RhPt catalyst with 10% La0.9MnO3 modified CZO support, and (B14) (aged) RhPt catalyst with 10% CaMnO3 modified CZO support. [Figure 8b]FIG. 13 shows perturbation aged TWC light-off performance versus CO conversion for washcoated (B11) (aged) reference RhPt fully formulated catalyst, (B12) (aged) RhPt catalyst with 10% BaMnO3 modified CZO support, (B13) (aged) RhPt catalyst with 10% La0.9MnO3 modified CZO support, and (B14) (aged) RhPt catalyst with 10% CaMnO3 modified CZO support. [Figure 8c] FIG. 13 shows perturbation aged TWC light-off performance versus THC conversion for washcoated (B11) (aged) reference RhPt fully formulated catalyst, (B12) (aged) RhPt catalyst with 10% BaMnO3 modified CZO support, (B13) (aged) RhPt catalyst with 10% La0.9MnO3 modified CZO support, and (B14) (aged) RhPt catalyst with 10% CaMnO3 modified CZO support. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] The present invention aims to address at least some of the problems associated with the prior art, or at least to provide a commercially acceptable alternative solution.

[0019] In a first aspect, the present invention provides a composition comprising a ceria-zirconia mixed oxide, the ceria-zirconia mixed oxide being surface-modified with a perovskite compound of formula (I), Formula (I) is A x-y A' y B 1-z B' z O3, wherein 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 0.7 to 1; y is between 0 and 0.5; z is 0 to 0.5.

[0020] Each aspect or embodiment defined in this specification may be combined with any other aspect or embodiment unless expressly indicated otherwise. In particular, any feature indicated as being preferred or advantageous may be combined with any other feature indicated as being preferred or advantageous.

[0021] Ceria-zirconia mixed oxide is a typical support material used in emissions treatment catalysts such as TWC. Ceria-zirconia mixed oxide is known to provide high surface area for active PGM metals and promoter species. Ceria-zirconia mixed oxide may be referred to herein as "CZO." The relative ratio of Ce:Zr in the mixed oxide is not particularly limited for purposes of the present invention, i.e., it may range from 0 wt. % ceria to 100 wt. % ceria.

[0022] Surprisingly, the inventors of the present invention have found that by surface modifying such ceria-zirconia mixed oxide supports with perovskite compounds, the ceria-zirconia mixed oxide can be endowed with additional or enhanced OSC properties while still retaining most of its surface area under thermal aging conditions. This may also advantageously facilitate improved promotion of the supported PGM species, if present, supported on the modified support (composition of the present invention) to obtain improved TWC conversion. Ceria-zirconia mixed oxides are promising supports for perovskite compounds due to their high surface area and inability to enter the perovskite lattice with any of the most used cations, e.g., La, Ba, Sr, Co, Mn or Fe.

[0023] The term "surface modified" as used herein may include, for example, that the perovskite compound is supported or coated on the ceria-zirconia mixed oxide. That is, the perovskite compound is attached or supported physically and / or chemically, preferably in (highly) dispersed form, on the surface of the ceria-zirconia mixed oxide. The term "surface modified" does not include a mere physical blend or mixture of the bulk perovskite compound and the ceria-zirconia mixed oxide. In this sense, the perovskite compound is not in bulk form. The term "surface modified" as used herein may also include that the perovskite compound has a smaller particle size than the ceria-zirconia mixed oxide. The term "surface modified" as used herein may also include that the ceria-zirconia mixed oxide is in bulk form and the perovskite compound is dispersed on the surface and / or in the pores of the bulk ceria-zirconia mixed oxide.

[0024] Without being bound by theory, it is believed that by providing such a surface-modified ceria-zirconia mixed oxide, in which the ceria-zirconia mixed oxide is surface-modified with the perovskite compound of formula (I), the perovskite compound can be stabilized by the ceria-zirconia mixed oxide. Thus, the disadvantages of bulk perovskite compounds, such as their low surface area to volume ratio and their lack of stability at exhaust gas catalyst operating temperatures, can be mitigated while providing the ceria-zirconia mixed oxide support with their advantageous OSC properties. That is, the ceria-zirconia mixed oxide phase can act both as a support to provide a large surface area and as a support to stabilize the perovskite nanocrystalline phase (e.g., from sintering) under thermal aging conditions. Synergistic interactions between the dispersed perovskite and the supporting species (e.g., PGM and promoter) can also occur, which can result in improved TWC performance. In addition to the promotion effect, the perovskite itself may also exhibit intrinsic activity for the TWC reaction that promotes PGM performance, which may allow for a potential reduction in PGM loading, which is desirable in the art, especially due to cost.

[0025] Such advantages cannot be realized by the use of bulk phase perovskite compounds in catalysts for treating exhaust gases, particularly TWC catalysts.

[0026] Thus, advantageously, the compositions of the present invention may be used in place of existing support materials to provide OSC properties to the catalyst, such as when ceria-zirconia mixed oxides are used as support materials in known catalytic articles, or may replace existing OSC support materials, such as ceria-zirconia support materials, which may provide additional and / or improved OSC properties. For example, by replacing a conventional support material with the compositions of the present invention, NO x , T of conversion for CO and / or THC (total hydrocarbon) reduction 50 It has been shown that the temperature at which 50% conversion is reached can be significantly reduced.

[0027] In summary, the inventors have surprisingly been able to harness the advantages of perovskite-type compounds OSCs for use in emissions treatment catalysts, while at least partially mitigating the disadvantages and instability of such compounds in bulk form at the operating temperatures of catalysts, e.g., TWCs.

[0028] As used herein, the term "perovskite" has its ordinary meaning in the art, i.e., perovskite-type compounds may refer to a class of compounds having a crystal structure similar to or a distorted version of CaTiO.

[0029] The composition and / or the perovskite compound of formula (I) may contain unavoidable impurities, typically less than 1 wt%, preferably less than 0.5 wt%, more preferably less than 0.1 wt%.

[0030] Preferably, the composition consists of a ceria-zirconia mixed oxide, which is surface modified with a perovskite compound of formula (I).

[0031] Preferably, A and / or A' are ions 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' are ions of a metal selected from the group consisting of Ca, Ba, La and Sr. Preferably, B and / or B' are ions of a metal selected from the group consisting of Mn, Co, Fe, Zr and Ni, more preferably, B and / or B' are ions of a metal selected from the group consisting of Mn, Zr and Fe. Preferably, B and / or B' are doped with a PGM element including 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, ions of a metal selected from the group consisting of Pt, Pd and Rh. Such compositions may be particularly suitable for use in applications described herein, such as in TWCs.

[0032] Preferably, x is from 0.8 to 1, more preferably from 0.9 to 1, or alternatively, but even more preferably, from 0.7 to 0.9, more preferably from 0.8 to 0.9. Preferably, y is from 0 to 0.3, more preferably from 0 to 0.2, more preferably from greater than 0 to 0.2. Preferably, z is from 0 to 0.4, more preferably from 0 to 0.3, even more preferably from greater than 0 to 0.2. Such compositions may be particularly suitable for use in applications described herein, such as in TWCs.

[0033] Preferably, y > 0. Preferably, z > 0. Such compositions may be particularly suitable for use in the applications described herein, such as in TWCs.

[0034] In an alternative preferred embodiment, z is 0. In an alternative preferred embodiment, y is 0. Preferably, y=z=0. However, when y>0, z can be 0, and when z>0, y can be 0.

[0035] Preferably, when y=z=0, A is La and B is Mn. In an alternative preferred embodiment, when y=z=0, A is Ca and B is Mn. In an alternative preferred embodiment, when y=z=0, A is La and B is Fe. In an alternative preferred embodiment, when y=z=0, A is Ba and B is Mn. In an alternative preferred embodiment, when y=z=0, A is Sr and B is Mn. In an alternative preferred embodiment, when y=z=0, A is Ba and B is Fe. In an alternative preferred embodiment, when y=z=0, A is Ca and B is Fe. In an alternative preferred embodiment, when y=z=0, A is Sr and B is Fe. Such compositions may be particularly suitable for use in applications described herein, such as TWCs.

[0036] Preferably, x is 1. Such compositions may be particularly suitable for use in the applications described herein, such as in TWCs.

[0037] Preferably, the ceria-zirconia mixed oxide is doped. Suitable dopants are known in the art. For example, preferably, the ceria-zirconia mixed oxide is doped with one or more oxides 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 oxides can be particularly useful as support materials. Preferably, the dopant is present in the ceria-zirconia mixed oxide in an amount of 0.001% to 20% by weight, more preferably 0.5% to 10% by weight, based on the total weight of the ceria-zirconia mixed oxide.

[0038] Preferably, the composition comprises 1-50 wt.%, preferably 5-30 wt.%, more preferably 5-25 wt.%, even more preferably 10-20 wt.% of the perovskite compound, based on the total weight of the perovskite compound and the ceria-zirconia mixed oxide. The perovskite compound may, for example, be highly dispersed on the ceria-zirconia mixed oxide. Such a ratio of the perovskite compound may provide a particularly stable composition with improved OSC properties.

[0039] Preferably, the ceria-zirconia mixed oxide is further surface-modified with a mixed oxide composite of formula (I), which may occur when phases other than the perovskite phase of formula (I) are present, for example due to incomplete formation of the perovskite phase during synthesis.

[0040] In a further aspect, the present invention provides a method for producing a composition comprising a ceria-zirconia mixed oxide, the ceria-zirconia mixed oxide being surface-modified with a perovskite compound of formula (I), Formula (I) is A x-y A' y B1-z B' z O3, wherein 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 0.7 to 1; y is between 0 and 0.5; z is 0 to 0.5, and the method is providing a solution comprising an organic acid, water, 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; and heating the slurry.

[0041] Such a method may be regarded as a (modified) Pechini method.

[0042] The term "slurry" as used herein may include a liquid containing 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, and even more typically for at least 1 hour. Increasing the contact time and / or stirring time may increase the dispersion of the perovskite compound on the ceria-zirconia mixed oxide.

[0043] Contacting the solution with the ceria-zirconia mixed oxide may typically include, for example, adding the ceria-zirconia mixed oxide in powder form to the solution. However, contacting the solution with the ceria-zirconia mixed oxide may also include combining the solution with a ceria-zirconia mixed oxide, for example a slurry containing ceria-zirconia mixed oxide powder in water. The contacting step is not particularly limited in this respect.

[0044] In some preferred embodiments, the solution further comprises an organic solvent, preferably ethylene glycol, however, more preferably the solution does not comprise an inorganic solvent, i.e. the solution is preferably an aqueous solution.

[0045] The one or more salts preferably include acetate, nitrate, oxynitrate, chloride, ammonium nitrate, hydroxide, oxalate and / or citrate, more preferably acetate, nitrate and / or oxynitrate.

[0046] Preferably, the heating of the slurry includes a first step of heating the slurry to a temperature of 150-350°C to form a gel. The term "gel" as used herein may include, for example, a colloid in a solid form rather than a sol or a thick viscous slurry. Without being bound by theory, this relatively low temperature heating may promote evaporation of at least a portion of the water in the slurry, thickening the slurry, and / or may promote the formation of a perovskite type compound on the ceria-zirconia mixed oxide. More preferably, the heating of the slurry includes a first step of heating the slurry to a temperature of 200-300°C, such as 250-300°C to form a gel.

[0047] Preferably, heating the slurry includes calcination, preferably after the heating step mentioned above (i.e. including a first step of heating the slurry to a temperature of 150-350°C to form a gel). The term "calcination" as used herein may encompass a heat treatment process in the absence or limited supply of air or oxygen causing pyrolysis or thermal transformation. Typically, however, calcination in this context involves heating in air in an oven. Preferably, calcination involves heating at a temperature of 300-500°C, preferably 350-450°C for 1-10 hours, preferably 3-6 hours. In an alternative or additional preferred embodiment, calcination involves heating at a temperature of 600-1000°C, preferably 700-900°C for 1-8 hours, preferably 2-5 hours. More preferably, the calcination comprises a first calcination step involving heating at a temperature of 300-500°C, preferably 350-450°C for 1-10 hours, preferably 3-6 hours, followed by a second calcination step involving heating at a temperature of 600-1000°C, preferably 700-900°C for 1-8 hours, preferably 2-5 hours. Without wishing to be bound by theory, it is believed that the first low temperature calcination step may promote the formation of the perovskite-precursor metal mixed oxide, i.e. the formation of the mixed oxide from the precursor salt, and then the second high temperature calcination step may promote the formation of a dense perovskite structure supported on the ceria-zirconia mixed oxide (i.e. a surface modified ceria-zirconia mixed oxide). It is emphasized that the perovskite type compound is not in bulk form but is supported on the surface of the ceria-zirconia mixed oxide.

[0048] Preferably, 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.

[0049] Preferably, the composition produced by the method of this aspect is the composition of the first aspect described herein.

[0050] In a further aspect, the present invention provides a composition obtained or obtainable by the method of the above aspect.

[0051] Surprisingly, the inventors of the present invention have found that by surface modifying such ceria-zirconia mixed oxide supports with perovskite compounds, the ceria-zirconia mixed oxide can be endowed with additional or enhanced OSC properties while still retaining most of its surface area under thermal aging conditions. This may also advantageously facilitate improved promotion of the supported PGM species, if present, supported on the modified support (composition of the present invention) to obtain improved TWC conversion. Ceria-zirconia mixed oxides are promising supports for perovskite compounds due to their high surface area and inability to enter the perovskite lattice with any of the most used cations, e.g., La, Ba, Sr, Co, Mn or Fe.

[0052] Without being bound by theory, it is believed that by providing such a surface-modified ceria-zirconia mixed oxide, in which the ceria-zirconia mixed oxide is surface-modified with the perovskite compound of formula (I), the perovskite compound can be stabilized by the ceria-zirconia mixed oxide. Thus, the disadvantages of bulk perovskite compounds, such as their low surface area to volume ratio and their lack of stability at exhaust gas catalyst operating temperatures, can be mitigated while providing the ceria-zirconia mixed oxide support with their advantageous OSC properties. That is, the ceria-zirconia mixed oxide phase can act both as a support to provide a large surface area and as a support to stabilize the perovskite nanocrystalline phase (e.g., from sintering) under thermal aging conditions. Synergistic interactions between the dispersed perovskite and the supporting species (e.g., PGM and promoter) can also occur, which can result in improved TWC performance. In addition to the promotion effect, the perovskite itself may also exhibit intrinsic activity for the TWC reaction that promotes PGM performance, which may allow for a potential reduction in PGM loading, which is desirable in the art, especially due to cost.

[0053] Such advantages cannot be realized by the use of bulk phase perovskite compounds in catalysts for treating exhaust gases, particularly TWC catalysts.

[0054] Thus, advantageously, the compositions of the present invention may be used in place of existing support materials to provide OSC properties to the catalyst, such as when ceria-zirconia mixed oxides are used as support materials in known catalytic articles, or may replace existing OSC support materials, such as ceria-zirconia support materials, which may provide additional and / or improved OSC properties. For example, by replacing a conventional support material with the compositions of the present invention, NO x It has been shown that the T50 (temperature at which 50% conversion is reached) of conversion for CO and / or THC (total hydrocarbon) reduction can be significantly reduced.

[0055] In summary, the inventors have surprisingly been able to harness the advantages of OSCs of perovskite-type compounds for use in emissions treatment catalysts, while at least partially mitigating the disadvantages and instability of such compounds in bulk form at the operating temperatures of the catalyst, e.g., TWC. In other words, the same advantages apply to the composition of this embodiment as to the composition of the first embodiment.

[0056] In a further aspect, the present invention provides a method for producing a composition comprising a ceria-zirconia mixed oxide, the ceria-zirconia mixed oxide being surface-modified with a perovskite compound of formula (I), Formula (I) is A x-y A' y B 1-z B' z O3, wherein 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 0.7 to 1; y is between 0 and 0.5; z is 0 to 0.5, and the method is contacting a ceria-zirconia mixed oxide with A, B, and optionally A' and / or B' by incipient wetness impregnation 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' to form an impregnated ceria-zirconia mixed oxide; and heating the impregnated ceria-zirconia mixed oxide.

[0057] Incipient wetness impregnation (IW or IWI) is a technique well known in the art. Those skilled in the art will be able to perform a suitable incipient wetness impregnation method without further instruction.

[0058] Contacting the ceria-zirconia mixed oxide with A, B, and optionally A' and / or B' by incipient wetness impregnation 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' may for example comprise impregnating the ceria-zirconia mixed oxide with A, B, and optionally A' and / or B' by incipient wetness impregnation 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'.

[0059] The one or more salts preferably include acetate, nitrate, oxynitrate, chloride, ammonium nitrate, hydroxide, oxalate and / or citrate, more preferably acetate, nitrate and / or oxynitrate.

[0060] Preferably, heating the impregnated ceria-zirconia mixed oxide comprises a first step of drying the impregnated ceria-zirconia mixed oxide at a temperature of 50-150°C, preferably 50-100°C, for 1 hour to 24 hours, preferably 6 hours to 12 hours.

[0061] Preferably, heating the impregnated ceria-zirconia mixed oxide comprises calcining, preferably after the heating step mentioned above (i.e. comprising a first step of drying the impregnated ceria-zirconia mixed oxide at a temperature of 50-150°C, preferably 50-100°C for 1 hour to 24 hours, preferably 6 hours to 12 hours). Preferably, the calcination comprises heating at a temperature of 300-500°C, preferably 350-450°C for 1 hour to 10 hours, preferably 3-6 hours. In an alternative or additional preferred embodiment, the calcination comprises heating at a temperature of 600-1000°C, preferably 700-900°C for 1 hour to 8 hours, preferably 2-5 hours. More preferably, the calcination comprises a first calcination step involving heating at a temperature of 300-500°C, preferably 350-450°C for 1-10 hours, preferably 3-6 hours, followed by a second calcination step involving heating at a temperature of 600-1000°C, preferably 700-900°C for 1-8 hours, preferably 2-5 hours. Without being bound by theory, it is believed that the first low temperature calcination step may promote the formation of the perovskite-precursor metal mixed oxide, i.e. the formation of the mixed oxide from the precursor salt, and then the second high temperature calcination step may promote the formation of a dense perovskite structure supported on the ceria-zirconia mixed oxide (i.e. a surface modified ceria-zirconia mixed oxide). It is emphasized that the perovskite type compound may be supported on the surface of the ceria-zirconia mixed oxide in a dispersed state, rather than in bulk form.

[0062] Preferably, the composition produced by the method of this aspect is the composition of the first aspect described herein.

[0063] In a further aspect, the present invention provides a composition obtained or obtainable by the method of the above aspect.

[0064] Surprisingly, the inventors of the present invention have found that by surface modifying such ceria-zirconia mixed oxide supports with perovskite compounds, the ceria-zirconia mixed oxide can be endowed with additional or enhanced OSC properties while still retaining most of its surface area under thermal aging conditions. This may also advantageously facilitate improved promotion of the supported PGM species, if present, supported on the modified support (composition of the present invention) to obtain improved TWC conversion. Ceria-zirconia mixed oxides are promising supports for perovskite compounds due to their high surface area and inability to enter the perovskite lattice with any of the most used cations, e.g., La, Ba, Sr, Co, Mn or Fe.

[0065] Without being bound by theory, it is believed that by providing such a surface-modified ceria-zirconia mixed oxide, in which the ceria-zirconia mixed oxide is surface-modified with the perovskite compound of formula (I), the perovskite compound can be stabilized by the ceria-zirconia mixed oxide. Thus, the disadvantages of bulk perovskite compounds, such as their low surface area to volume ratio and their lack of stability at exhaust gas catalyst operating temperatures, can be mitigated while providing the ceria-zirconia mixed oxide support with their advantageous OSC properties. That is, the ceria-zirconia mixed oxide phase can act both as a support to provide a large surface area and as a support to stabilize the perovskite nanocrystalline phase (e.g., from sintering) under thermal aging conditions. Synergistic interactions between the dispersed perovskite and the supporting species (e.g., PGM and promoter) can also occur, which can result in improved TWC performance. In addition to the promotion effect, the perovskite itself may also exhibit intrinsic activity for the TWC reaction that promotes PGM performance, which may allow for a potential reduction in PGM loading, which is desirable in the art, especially due to cost.

[0066] Such advantages cannot be realized by the use of bulk phase perovskite compounds in catalysts for treating exhaust gases, particularly TWC catalysts.

[0067] Thus, advantageously, the compositions of the present invention may be used in place of existing support materials to provide OSC properties to the catalyst, such as when ceria-zirconia mixed oxides are used as support materials in known catalytic articles, or may replace existing OSC support materials, such as ceria-zirconia support materials, which may provide additional and / or improved OSC properties. For example, by replacing a conventional support material with the compositions of the present invention, NO x It has been shown that the T50 (temperature at which 50% conversion is reached) of conversion for CO and / or THC (total hydrocarbon) reduction can be significantly reduced.

[0068] In summary, the inventors have surprisingly been able to harness the advantages of OSCs of perovskite-type compounds for use in emissions treatment catalysts, while at least partially mitigating the disadvantages and instability of such compounds in bulk form at the operating temperatures of the catalyst, e.g., TWC. In other words, the same advantages apply to the composition of this embodiment as to the composition of the first embodiment.

[0069] In a further aspect, the present invention provides a method for producing a composition comprising a ceria-zirconia mixed oxide, the ceria-zirconia mixed oxide being surface-modified with a perovskite compound of formula (I), Formula (I) is A x-y A' y B 1-z B' z O3, wherein 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 0.7 to 1; y is between 0 and 0.5; z is 0 to 0.5, and the method is 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.

[0070] Spray drying is a well known technique in the art and one of ordinary skill in the art would be able to carry out a suitable spray drying method without further instruction.

[0071] Contacting the solution with the ceria-zirconia mixed oxide may typically include, for example, adding the ceria-zirconia mixed oxide in powder form to the solution. However, contacting the solution with the ceria-zirconia mixed oxide may also include combining the solution with a ceria-zirconia mixed oxide, for example a slurry containing ceria-zirconia mixed oxide powder in water. The contacting step is not particularly limited in this respect.

[0072] The one or more salts preferably include acetate, nitrate, oxynitrate, chloride, ammonium nitrate, hydroxide, oxalate and / or citrate, more preferably acetate, nitrate and / or oxynitrate.

[0073] Preferably, the solution is an aqueous solution.

[0074] Preferably, the heating of the spray dried powder comprises calcination. Preferably, the calcination comprises heating at a temperature of 300-500°C, preferably 350-450°C for 1-10 hours, preferably 3-6 hours. In an alternative or additional preferred embodiment, the calcination comprises heating at a temperature of 600-1000°C, preferably 700-900°C for 1-8 hours, preferably 2-5 hours. More preferably, the calcination comprises a first calcination step comprising heating at a temperature of 300-500°C, preferably 350-450°C for 1-10 hours, preferably 3-6 hours, which first calcination step is followed by a second calcination step comprising heating at a temperature of 600-1000°C, preferably 700-900°C for 1-8 hours, preferably 2-5 hours. Without wishing to be bound by theory, it is believed that a first low temperature calcination step may promote the formation of the perovskite-precursor metal mixed oxide, i.e., from the precursor salt, and then a second high temperature calcination step may promote the formation of a dense perovskite structure supported on the ceria-zirconia mixed oxide (i.e., a surface-modified ceria-zirconia mixed oxide). It is emphasized that the perovskite compound is not in bulk form but is supported on the surface of the ceria-zirconia mixed oxide.

[0075] Preferably, the inlet temperature of the spray drying is 100 to 300° C., more preferably 150 to 250° C. The inlet temperature is a well-known term in the field of spray drying.

[0076] Preferably, the composition produced by the method of this aspect is the composition of the first aspect described herein.

[0077] In a further aspect, the present invention provides a composition obtained or obtainable by the method of the above aspect.

[0078] Surprisingly, the inventors of the present invention have found that by surface modifying such ceria-zirconia mixed oxide supports with perovskite compounds, the ceria-zirconia mixed oxide can be endowed with additional or enhanced OSC properties while still retaining most of its surface area under thermal aging conditions. This may also advantageously facilitate improved promotion of the supported PGM species, if present, supported on the modified support (composition of the present invention) to obtain improved TWC conversion. Ceria-zirconia mixed oxides are promising supports for perovskite compounds due to their high surface area and inability to enter the perovskite lattice with any of the most used cations, e.g., La, Ba, Sr, Co, Mn or Fe.

[0079] Without being bound by theory, it is believed that by providing such a surface-modified ceria-zirconia mixed oxide, in which the ceria-zirconia mixed oxide is surface-modified with the perovskite compound of formula (I), the perovskite compound can be stabilized by the ceria-zirconia mixed oxide. Thus, the disadvantages of bulk perovskite compounds, such as their low surface area to volume ratio and their lack of stability at exhaust gas catalyst operating temperatures, can be mitigated while providing the ceria-zirconia mixed oxide support with their advantageous OSC properties. That is, the ceria-zirconia mixed oxide phase can act both as a support to provide a large surface area and as a support to stabilize the perovskite nanocrystalline phase (e.g., from sintering) under thermal aging conditions. Synergistic interactions between the dispersed perovskite and the supporting species (e.g., PGM and promoter) can also occur, which can result in improved TWC performance. In addition to the promotion effect, the perovskite itself may also exhibit intrinsic activity for the TWC reaction that promotes PGM performance, which may allow for a potential reduction in PGM loading, which is desirable in the art, especially due to cost.

[0080] Such advantages cannot be realized by the use of bulk phase perovskite compounds in catalysts for treating exhaust gases, particularly TWC catalysts.

[0081] Thus, advantageously, the compositions of the present invention may be used in place of existing support materials to provide OSC properties to the catalyst, such as when ceria-zirconia mixed oxides are used as support materials in known catalytic articles, or may replace existing OSC support materials, such as ceria-zirconia support materials, which may provide additional and / or improved OSC properties. For example, by replacing a conventional support material with the compositions of the present invention, NO x , T of conversion for CO and / or THC (total hydrocarbon) reduction 50 It has been shown that the temperature at which 50% conversion is reached can be significantly reduced.

[0082] In summary, the inventors have surprisingly been able to harness the advantages of OSCs of perovskite-type compounds for use in emissions treatment catalysts, while at least partially mitigating the disadvantages and instability of such compounds in bulk form at the operating temperatures of the catalyst, e.g., TWC. In other words, the same advantages apply to the composition of this embodiment as to the composition of the first embodiment.

[0083] In a further aspect, the present invention provides a method for producing a composition comprising a ceria-zirconia mixed oxide, the ceria-zirconia mixed oxide being surface-modified with a perovskite compound of formula (I), Formula (I) is A x-y A' y B 1-z B' z O3, wherein 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 0.7 to 1; y is between 0 and 0.5; z is 0 to 0.5, and the method is providing an aqueous 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; contacting the slurry with a base; recovering a solid residue from the slurry; and heating the solid residue.

[0084] Contacting the solution with the ceria-zirconia mixed oxide may typically include, for example, adding the ceria-zirconia mixed oxide in powder form to the solution. However, contacting the solution with the ceria-zirconia mixed oxide may also include combining the solution with a ceria-zirconia mixed oxide, for example a slurry containing ceria-zirconia mixed oxide powder in water. The contacting step is not particularly limited in this respect.

[0085] The one or more salts preferably include acetate, nitrate, oxynitrate, chloride, ammonium nitrate, hydroxide, oxalate and / or citrate, more preferably acetate, nitrate and / or oxynitrate.

[0086] The method includes contacting the slurry with a base. Preferably, contacting the slurry with a base includes contacting the slurry with a solution comprising a base, preferably an aqueous solution comprising a base. Such a method may be referred to as a "co-precipitation" method. Without being bound by theory, it is believed that the addition of a base may result in the precipitation of A, A', B and / or B' cations on the ceria-zirconia mixed oxide support. The method may further include filtering and / or washing the ceria-zirconia mixed oxide after the addition of the base (i.e., having the precipitated contents thereon) and prior to heating the solid residue.

[0087] Recovering the solid residue from the slurry can include filtering the slurry to obtain the solid residue. As used herein, the term "solid residue" can include, for example, filter cakes. Such filter cakes are well known in the art.

[0088] Preferably, heating the solid residue comprises a first step of drying the solid residue at a temperature of 50-150° C., preferably 50-100° C., for 1 hour to 24 hours, preferably 6 hours to 12 hours.

[0089] Preferably, heating the solid residue comprises a calcination, preferably after the heating step mentioned above (i.e. comprising a first step of drying the solid residue at a temperature of 50-150°C, preferably 50-100°C for 1 hour to 24 hours, preferably 6 hours to 12 hours). Preferably, the calcination comprises heating at a temperature of 300-500°C, preferably 350-450°C for 1 hour to 10 hours, preferably 3-6 hours. In an alternative or additional preferred embodiment, the calcination comprises heating at a temperature of 600-1000°C, preferably 700-900°C for 1 hour to 8 hours, preferably 2-5 hours. More preferably, the calcination comprises a first calcination step involving heating at a temperature of 300-500°C, preferably 350-450°C for 1-10 hours, preferably 3-6 hours, followed by a second calcination step involving heating at a temperature of 600-1000°C, preferably 700-900°C for 1-8 hours, preferably 2-5 hours. Without being bound by theory, it is believed that the first low temperature calcination step may promote the formation of the perovskite-precursor metal mixed oxide, i.e. the formation of the mixed oxide from the precursor salt, and then the second high temperature calcination step may promote the formation of a dense perovskite structure supported on the ceria-zirconia mixed oxide (i.e. a surface modified ceria-zirconia mixed oxide). It is emphasized that the perovskite type compound may be supported on the surface of the ceria-zirconia mixed oxide in a dispersed state, rather than in bulk form.

[0090] Preferably, the base comprises ammonium hydroxide.

[0091] Preferably, recovering the solid residue from the slurry comprises filtering the slurry to obtain the solid residue and washing the solid residue with water, preferably with an excess of water.

[0092] Preferably, the composition produced by the method of this aspect is the composition of the first aspect described herein.

[0093] In a further aspect, the present invention provides a composition obtained or obtainable by the method of the above aspect.

[0094] Surprisingly, the inventors of the present invention have found that by surface modifying such ceria-zirconia mixed oxide supports with perovskite compounds, the ceria-zirconia mixed oxide can be endowed with additional or enhanced OSC properties while still retaining most of its surface area under thermal aging conditions. This may also advantageously facilitate improved promotion of the supported PGM species, if present, supported on the modified support (composition of the present invention) to obtain improved TWC conversion. Ceria-zirconia mixed oxides are promising supports for perovskite compounds due to their high surface area and inability to enter the perovskite lattice with any of the most used cations, e.g., La, Ba, Sr, Co, Mn or Fe.

[0095] Without being bound by theory, it is believed that by providing such a surface-modified ceria-zirconia mixed oxide, in which the ceria-zirconia mixed oxide is surface-modified with the perovskite compound of formula (I), the perovskite compound can be stabilized by the ceria-zirconia mixed oxide. Thus, the disadvantages of bulk perovskite compounds, such as their low surface area to volume ratio and their lack of stability at exhaust gas catalyst operating temperatures, can be mitigated while providing the ceria-zirconia mixed oxide support with their advantageous OSC properties. That is, the ceria-zirconia mixed oxide phase can act both as a support to provide a large surface area and as a support to stabilize the perovskite nanocrystalline phase (e.g., from sintering) under thermal aging conditions. Synergistic interactions between the dispersed perovskite and the supporting species (e.g., PGM and promoter) can also occur, which can result in improved TWC performance. In addition to the promotion effect, the perovskite itself may also exhibit intrinsic activity for the TWC reaction that promotes PGM performance, which may allow for a potential reduction in PGM loading, which is desirable in the art, especially due to cost.

[0096] Such advantages cannot be realized by the use of bulk phase perovskite compounds in catalysts for treating exhaust gases, particularly TWC catalysts.

[0097] Thus, advantageously, the compositions of the present invention may be used in place of existing support materials to provide OSC properties to the catalyst, such as when ceria-zirconia mixed oxides are used as support materials in known catalytic articles, or may replace existing OSC support materials, such as ceria-zirconia support materials, which may provide additional and / or improved OSC properties. For example, by replacing a conventional support material with the compositions of the present invention, NO x It has been shown that the T50 (temperature at which 50% conversion is reached) of conversion for CO and / or THC (total hydrocarbon) reduction can be significantly reduced.

[0098] In summary, the inventors have surprisingly been able to harness the advantages of OSCs of perovskite-type compounds for use in emissions treatment catalysts, while at least partially mitigating the disadvantages and instability of such compounds in bulk form at the operating temperatures of the catalyst, e.g., TWC. In other words, the same advantages apply to the composition of this embodiment as to the composition of the first embodiment.

[0099] In a further aspect, the present invention provides a catalytic article comprising a substrate having disposed thereon a composition described herein.

[0100] As used herein, the term "catalyst article" may include an article on or within which a catalyst is supported. The article may take the form of, for example, a honeycomb monolith, or a filter, such as a wall-flow filter or a flow-through filter.

[0101] The term "substrate" as used herein can include, for example, ceramic or metal honeycombs, or filter blocks, such as wall-flow or flow-through filters. Substrates can include ceramic monolith substrates. Substrates can vary in their material composition, size and configuration, cell shape and density, and wall thickness. Suitable substrates are known in the art.

[0102] The term "disposed thereon" in the context of this embodiment can include both having a composition disposed directly on the substrate, i.e., without intervening materials, and / or having a composition disposed indirectly on the substrate, i.e., with intervening materials. If the substrate is porous, the term "disposed thereon" can also include having a composition disposed therein, for example, within the pores of the substrate, i.e., the composition is disposed on and / or within it. In other words, the compositions 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 generally well known in the art. The term "washcoat" as used herein is well known in the art and generally refers to an adherent coating applied to a substrate during the production of a catalyst.

[0103] Preferably, the catalyst article is for treating exhaust gases. Preferably, the catalyst article comprises a three-way catalyst (TWC), more preferably the catalyst article is a TWC.

[0104] Preferably, platinum group metals (PGMs) are supported on the composition. The PGMs may be supported on the surface and / or in the pores of the ceria-zirconia mixed oxide. The PGMs may also be supported on the perovskite compound. Furthermore, the PGMs may be located at the interface between the ceria-zirconia mixed oxide and the perovskite compound supported thereon. Without wishing to be bound by theory, it is believed that the presence of the perovskite compound may further promote the catalytic activity of the PGM and increase the resistance of the PGM nanoparticles to sintering. PGM sintering may reduce the catalytic activity of the PGM. These benefits may be facilitated by charge transfer and / or oxygen transfer between the perovskite and PGM phases, resulting in improved PGM stability. For example, when the supported PGM particles have a small particle size, it is believed that in extreme cases, the particles may interact with / adsorb the PGM in / on the perovskite framework under oxidizing conditions, which may reduce the possibility of PGM sintering. The perovskite may at least promote the formation of PGM oxides. The term PGM as used herein includes one or more platinum group metals selected from ruthenium, rhodium, palladium, osmium, iridium, and platinum. Preferably, the PGM includes Pt, Pd, Rh, or mixtures or alloys thereof. Such metals may be particularly suitable for performing three-way catalysis. The PGM may be in the form of an alloy.

[0105] Preferably, the catalyst article is for use in an emission treatment system. Preferably, the catalyst article is for three-way catalysis.

[0106] Preferably, the catalyst article has a surface area of ​​1 g / in 3 ~3g / in 3 The washcoat loading is

[0107] Preferably, the substrate comprises a wall-flow filter substrate. In an alternative preferred embodiment, the substrate comprises a flow-through substrate.

[0108] Preferably, the catalyst article comprises a bottom layer of support material having rhodium thereon and a top layer of support material having palladium thereon. In an alternative preferred embodiment, 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. However, preferably, the support material comprises a composition as described herein. That is, the support material present in the bottom layer and / or the top layer may comprise a composition as described herein.

[0109] When present, the catalyst article preferably has a coating weight of 2 g / ft 3 ~15g / ft 3 of rhodium, more preferably 3g / ft 3 ~10g / ft 3 When present, the catalyst article preferably contains 20 g / ft 3 ~200g / ft 3 of palladium, more preferably 30 g / ft 3 ~150g / ft 3 When present, the catalytic article preferably contains 2 g / ft 3 ~200g / ft 3 of platinum, more preferably 10 g / ft 3 ~100g / ft 3 Contains platinum.

[0110] In a further aspect, the present invention provides an emission treatment system comprising the catalytic article described herein. Preferably, the emission treatment system is for a gasoline engine. Preferably, the gasoline engine operates under stoichiometric conditions.

[0111] In a further aspect, the present invention provides a method of treating an exhaust gas, the method comprising providing a catalytic article as described herein and contacting the catalytic article with an exhaust gas. The exhaust gas is preferably from a gasoline engine. Preferably, the gasoline engine is operated under stoichiometric conditions.

[0112] The invention will now be described with reference to the following non-limiting examples. EXAMPLES

[0113] A. Synthesis Examples Example A1: Synthesis of 10 wt% BaMnO3 modified CZO by Pechini method 1. In a 1000 mL beaker, n (M total ):n(citric acid):n(ethylene glycol)=2:3:90 molar ratio (wherein, M total are all metal cations (Ba and Mn) in the perovskite formula), and calculated amounts of citric acid and ethylene glycol were dissolved. 2. An appropriate amount of DI water was added, followed by continuous stirring, to form a clear solution. 3. The calculated amounts of barium acetate (20 g) and manganese acetate tetrahydrate (20 g) were added. This was stirred continuously for 1 hour. 4. The required amount of CZO powder (192 g) was added. This was mixed for 1 hour with continuous stirring. 5. The resulting slurry was slowly heated to 275°C and continuously stirred until a gel was formed. 6. After the gel was cooled to room temperature, it was transferred to a large crucible and covered with alumina foil (having holes on the cover). 7. Low-temperature calcination was carried out in stagnant air at 400°C for 4 hours (heating rate 10°C / min). 8. After the sample was cooled, it was transferred to a smaller crucible and calcined at high temperature at 800°C for 4 hours (heating rate 10°C / min).

[0114] Example A2: Synthesis of 10 wt% BaMnO3 modified CZO by aqueous method 1. In a 1000 mL beaker, n (M total ):n(citric acid)=2:3 molar ratio (wherein, M total are the total metal cations (Ba and Mn) in the perovskite formula) and the calculated amount of citric acid was dissolved in 500 mL of DI water. This was stirred continuously until a thick slurry was formed. 2. The calculated amounts of barium acetate (20 g) and manganese acetate tetrahydrate (20 g) were added. This was stirred continuously for 1 hour. 3. The required amount of CZO powder (192 g) was added and mixed for 1 hour with continuous stirring. 4. The resulting slurry was heated to 275°C and stirred continuously until a gel was formed. 5. After the gel was cooled to room temperature, it was transferred to a large crucible and covered with alumina foil (having holes on the cover). 6. Low-temperature calcination was carried out in stagnant air at 400°C for 4 hours (heating rate 10°C / min). 7. After the sample was cooled, it was transferred to a smaller crucible and calcined at high temperature at 800°C for 4 hours (heating rate 10°C / min).

[0115] Example A3: Synthesis of 10 wt% BaMnO3 modified CZO by incipient wetness impregnation method 1. CZO powder (192 g) was impregnated using incipient wetness impregnation with a mixed solution of barium acetate (20 g) and manganese acetate tetrahydrate (20 g) at 10 wt% equivalent BaMn (1:1 molar ratio). 2. The resulting impregnated CZO was dried at 80°C for 1 h and mixed periodically to prevent wicking. 3. Low-temperature calcination was carried out in stagnant air at 400°C for 4 hours, followed by high-temperature calcination at 800°C for 4 hours (heating rate 10°C / min).

[0116] Example A4: Synthesis of 10 wt% BaMnO3 modified CZO by spray drying method 1. A solution of barium acetate (107 g) and manganese acetate tetrahydrate (103 g) was prepared and mixed for 1 hour until the Ba / Mn precursor was completely dissolved. 2. CZO powder (1009 g) was added to the above solution at a target solids content of 30% with mechanical mixing for at least 1 hour to make a slurry. 3. The slurry was spray dried, ensuring adequate mixing of the slurry during the entire spray drying process. 4. The spray dried powder was collected and calcined in a static oven at 400°C / 4h followed by 800°C / 4h.

[0117] Examples A5 to A13 The synthesis procedures for Examples A5 to A13 were similar to those for Examples A1 to A4, and the amounts of the main precursors are summarized in Table 1 below.

[0118] [Table 1] Note: I. Synthesis procedure similar to Example A1 (Pechini method) using different amounts of metal precursors and CZO II. Synthesis procedure similar to Example A2 (aqueous method) using different amounts of metal precursors and CZO. III. Synthesis procedure similar to Example A3 (incipient wetness impregnation, IWI) with different amounts of metal precursors and CZO. IV. Synthesis procedure similar to Example A4 (spray drying method, SD) using different amounts of metal precursors and CZO. Barium acetate. b. Manganese acetate tetrahydrate. c. Lanthanum nitrate hexahydrate. d.Calcium nitrate tetrahydrate. e. Iron nitrate nonahydrate.

[0119] B. Catalyst Preparation Examples Reference Example B1: 3 wt% Pd / CZO washcoat catalyst 1. CZO powder was impregnated with 3 wt % Pd (as a palladium nitrate solution) using incipient wetness impregnation. 2. The impregnated CZO was dried at 80°C for 1 h, mixed periodically to prevent wicking, and then calcined at 500°C for 30 min in still air. A slurry was prepared with DI water and appropriate amounts of binders and thickeners for a final batch solids content of 3.22%. The slurry was vigorously mixed in a VWR vortex mixer until homogenous. 4. A 1x3 inch ceramic substrate core was coated aiming for an addition of 1.2 inches from the inlet end and then allowed to air cure and dry. 5. The bricks were calcined in a static oven at 500°C for 30 minutes.

[0120] Example B2: 3 wt% Pd / 10% BMO modified CZO washcoat catalyst 1. 10% BaMnO3 modified CZO powder (Example A1) was impregnated with 3 wt% Pd (as a palladium nitrate solution) using incipient wetness impregnation. 2. The impregnated CZO was dried at 80 °C for 1 h, mixed periodically to prevent wicking, and then calcined at 500 °C for 30 min in still air. A slurry was prepared with DI water and appropriate amounts of binders and thickeners for a final batch solids content of 3.22%. The slurry was vigorously mixed in a VWR vortex mixer until homogenous. 4. A 1x3 inch ceramic substrate core was coated aiming for an addition of 1.2 inches from the inlet end and then allowed to air cure and dry. 5. The bricks were calcined in a static oven at 500°C for 30 minutes.

[0121] Examples B3 to B5 The catalyst preparation procedures of Examples B3 to B5 were the same as those of Examples B1 and B2, and the amounts of main precursors are summarized in Table 2 below.

[0122] [Table 2]

[0123] Reference Example B6: Fully formulated single layer Pd washcoat 1. A solution was prepared using the required amount of Pd nitrate (Pd loading: 100 g / ft 3 ). 2.1g / in 3 of stabilized alumina powder and 1g / in 3 of CZO material was added and mixed for 1 hour. 3.300g / ft 3 of barium sulfate was added and mixed for at least 1 hour. 4. After adding the appropriate amount of binder, mix for 1 hour. 5. The solids content was adjusted to 30%, thickener was added, and then mixed overnight. A 6.1×3 inch ceramic substrate core was coated 50-55% from the inlet end, dried by air curing, and then coated 50-55% of the add-on length from the outlet end. 7. The bricks were calcined in a static oven at 500°C for 30 minutes.

[0124] Example B7: Fully formulated single layer Pd washcoat with 10% BMO modified CZO 1. The required amount of Pd nitrate (Pd loading 100g / ft 3 ) was used to prepare the solution. 2.1g / in 3 of stabilized alumina powder and 1g / in 3 of 10% BaMnO3 modified CZO material (Example A3) was added and then mixed for 1 hour. 3.300g / ft 3 of barium sulfate was added and mixed for at least 1 hour. 4. After adding the appropriate amount of binder, mix for 1 hour. 5. The solids content was adjusted to 30%, thickener was added, and then mixed overnight. A 6.1×3 inch ceramic substrate core was coated 50-55% from the inlet end, dried by air curing, and then coated 50-55% of the add-on length from the outlet end. 7. The bricks were calcined in a static oven at 500°C for 30 minutes.

[0125] Example B8: Fully formulated single layer Pd washcoat with 10% LFO modified CZO 1. The required amount of Pd nitrate (Pd loading 100g / ft 3 ) was used to prepare the solution. 2.1g / in 3 of stabilized alumina powder and 1g / in 3 of 10% LaFeO3 modified CZO material (Example A12) was added and then mixed for 1 hour. 3.300g / ft 3 of barium sulfate was added and mixed for at least 1 hour. 4. After adding the appropriate amount of binder, mix for 1 hour. 5. The solids content was adjusted to 30%, thickener was added, and then mixed overnight. A 6.1×3 inch ceramic substrate core was coated 50-55% from the inlet end, dried by air curing, and then coated 50-55% of the add-on length from the outlet end. 7. The bricks were calcined in a static oven at 500°C for 30 minutes.

[0126] Reference Example B9: Fully Formulated Single Layer Pt Washcoat 1. The required amount of Pt nitrate (Pt loading 20g / ft 3 ) was used to prepare the solution. 2.1g / in 3 of stabilized alumina powder and 1g / in 3 of CZO material was added. 3. The pH was adjusted to 5-7 with ammonia and then mixed for 1 hour. 4. The solids content was adjusted to 30%. 5. The appropriate amount of thickener was added and then mixed overnight. 6. A 1x3 inch ceramic substrate core was coated aiming for an addition of 1.2 inches from the inlet end and then allowed to air cure and dry. 7. The bricks were calcined in a static oven at 500°C for 30 minutes.

[0127] Example B10: Fully formulated single layer Pt washcoat with 20% CMO modified CZO 1. The required amount of Pt nitrate (Pt loading 20g / ft 3 ) was used to prepare the solution. 2.1g / in 3 of stabilized alumina powder and 1g / in 3 of 20% CaMnO3 modified CZO (A11) was added. 3. The pH was adjusted to 5-7 with ammonia and then mixed for 1 hour. 4. The solids content was adjusted to 30%. 5. The appropriate amount of thickener was added and then mixed overnight. 6. A 1x3 inch ceramic substrate core was coated aiming for an addition of 1.2 inches from the inlet end and then allowed to air cure and dry. 7. The bricks were calcined in a static oven at 500°C for 30 minutes.

[0128] Reference Example B11: Fully Formulated Single Layer RhPt Washcoat 1. Rh nitrate (Rh loading 3.6g / ft 3 ) into a slurry of CZO (1.1 g / in 3 ) and mixed for at least 15 minutes. 2. The pH was adjusted to >6 with ammonia and then mixed for at least 1 hour. 3. Alumina slurry (0.4g / in 3 ) and platinum nitrate (Pt loading 3.6 g / ft 3 ) was added and mixed for at least 15 minutes. 4. The pH was adjusted to >6 with ammonia and then mixed for at least 30 minutes. 5. After adding the appropriate amount of binder, mix for at least 30 minutes. 6. The solids were adjusted to a target of approximately 25% and thickener was added, then mixed overnight. A 7.1×3 inch ceramic substrate core was coated 50-55% from the inlet end, allowed to air cure and then coated 50-55% of the add-on length from the outlet end. 8. The bricks were calcined in a static oven at 500°C for 30 minutes.

[0129] Example B12: Fully formulated single layer RhPt washcoat with 10% BMO modified CZO 1. Rh nitrate (Rh loading 3.6g / ft 3 ) into a slurry of 10% BaMnO3-modified CZO (A3, 1.1 g / in 3 ) and mixed for at least 15 minutes. 2. The pH was adjusted to >6 with ammonia and then mixed for at least 1 hour. 3. Stabilized alumina slurry (0.4 g / in 3 ) and platinum nitrate (platinum loading 3.6 g / ft 3) is added and then mixed for at least 15 minutes. 4. The pH was adjusted to >6 with ammonia and then mixed for at least 30 minutes. 5. After adding the appropriate amount of binder, mix for at least 30 minutes. 6. The solids were adjusted to a target of approximately 25% and thickener was added, then mixed overnight. A 7.1×3 inch ceramic substrate core was coated 50-55% from the inlet end, allowed to air cure and then coated 50-55% of the add-on length from the outlet end. 8. The bricks were calcined in a static oven at 500°C for 30 minutes.

[0130] Example B13: Fully formulated single layer RhPt washcoat with 10% LMO modified CZO 1. Rh nitrate (Rh loading 3.6g / ft 3 (having 10% La 0.9 MnO3-modified CZO slurry (A8, 1.1 g / in 3 ) and mixed for at least 15 minutes. 2. The pH was adjusted to >6 with ammonia and then mixed for at least 1 hour. 3. Stabilized alumina slurry (0.4 g / in 3 ) and platinum nitrate (platinum loading 3.6 g / ft 3 ) is added and then mixed for at least 15 minutes. 4. The pH was adjusted to >6 with ammonia and then mixed for at least 30 minutes. 5. After adding the appropriate amount of binder, mix for at least 30 minutes. 6. The solids were adjusted to a target of approximately 25% and thickener was added, then mixed overnight. A 7.1×3 inch ceramic substrate core was coated 50-55% from the inlet end, allowed to air cure and then coated 50-55% of the add-on length from the outlet end. 8. The bricks were calcined in a static oven at 500°C for 30 minutes.

[0131] Example B14: Fully formulated single layer RhPt washcoat with 10% CMO modified CZO 1. Rh nitrate (Rh loading 3.6g / ft 3 ) into a slurry of 10% CaMnO3-modified CZO (A10, 1.1 g / in 3 ) and mixed for at least 15 minutes. 2. The pH was adjusted to >6 with ammonia and then mixed for at least 1 hour. 3. Stabilized alumina slurry (0.4 g / in 3 ) and platinum nitrate (platinum loading 3.6 g / ft 3 ) is added and then mixed for at least 15 minutes. 4. The pH was adjusted to >6 with ammonia and then mixed for at least 30 minutes. 5. After adding the appropriate amount of binder, mix for at least 30 minutes. 6. The solids were adjusted to a target of approximately 25% and thickener was added, then mixed overnight. A 7.1×3 inch ceramic substrate core was coated 50-55% from the inlet end, allowed to air cure and then coated 50-55% of the add-on length from the outlet end. 8. The bricks were calcined in a static oven at 500°C for 30 minutes.

[0132] C. Results and Testing FIG. 1 shows the powder XRD pattern of 10% BaMnO3 modified CZO according to Example A1. FIG. 2 shows the results of the 10% La 0.9 Figure 1 shows the powder XRD pattern of MnO3 modified CZO. Both perovskite phases were highly dispersed and detected by XRD. FIG. 3 shows the OSC of selected perovskite-modified CZO samples. After surface modification with perovskite phase, the total OSC of the CZO support was significantly improved. In particular, the OSC of the conventional CZO, (A3) 10% BaMnO3-modified CZO, (A8) 10% La 0.9Samples including MnO3 modified CZO, (A10) 10% CaMnO3 modified CZO, and (A12) 10% LaFeO3 modified CZO were tested. During the OSC measurements, the powder samples were pre-oxidized at the respective temperatures, followed by flowing CO through the samples, where CO was converted to CO2 by oxygen species donated by the powder samples. Thus, the total OSC of the solid samples corresponds to the amount of CO2 produced per gram of sample. The low-temperature (≦350°C) OSC of these modified CZO samples was high, ranging from 0.25 to 0.8 mmol CO2 produced / g, whereas the high-temperature (≧500°C) OSC of these samples was high, ranging from 0.75 to 0.95 mmol CO2 produced / g.

[0133] Figures 4a, 4b, and 4c show the TWC light-off performance (NO x In particular, the figure shows (a) NO conversion, CO conversion and THC conversion for (B1) the (aged) reference Pd catalyst on a washcoated (single) CZO support, and (B2) the (aged) Pd catalyst on a BaMnO3-type perovskite-modified CZO support. x The perturbation aged TWC light-off performance versus (a) conversion, (b) CO conversion, and (c) THC conversion is shown. Reaction conditions: with rich pretreatment, 150-700°C, λ=0.96-1.04, GHSV=200,000hr -1 The modified supports were synthesized by the Pechini method. Compared with the reference catalyst, the BaMnO3 perovskite modified supports showed higher catalytic activity, especially NO x The conversion showed an improvement in TWC conversion.

[0134] 5a, 5b, and 5c show the TWC light-off performance (NO x In particular, the figure shows the conversion of the (aged) reference Rh catalyst on a washcoated (B3) single CZO support, the conversion of the (aged) La 0.9(a) NO of (aged) Rh catalyst on MnO3-type perovskite-modified CZO support and (B5) (aged) Rh catalyst on LaFeO3-type perovskite-modified CZO support. x The perturbation aged TWC light-off performance versus (a) conversion, (b) CO conversion, and (c) THC conversion is shown. Reaction conditions: with rich pretreatment, 150-700°C, λ=0.96-1.04, GHSV=200,000hr -1 The modified supports were synthesized by the incipient wetness impregnation method. Compared to the reference catalyst, the perovskite modified supports showed a significant improvement in TWC conversion.

[0135] 6a, 6b, and 6c show the TWC light-off performance (NO x In particular, the figure shows (a) NO conversion, CO conversion and THC conversion for the washcoated (B6) (aged) reference Pd fully formulated catalyst, (B7) (aged) Pd catalyst with 10% BaMnO3 modified CZO-type perovskite modified CZO support, and (B8) (aged) Pd catalyst with 10% LaFeO3 modified CZO-type perovskite modified CZO support. x Figure 1 shows the perturbation aged TWC light-off performance for (a) conversion, (b) CO conversion, and (c) THC conversion. Reaction conditions: with rich pretreatment, 150-700°C, λ=0.96-1.04, GHSV=200,000hr -1 . Reference Pd(100g / ft 3 The perovskite-modified supports showed a significant improvement in TWC conversion compared to the Pd-based catalysts (Pd loading of 100 g / ft). The order of overall TWC activity was Pd with 10% BaMnO3-CZO > Pd with 10% LaFeO3-CZO > reference Pd (100 g / ft 3 ) order.

[0136] 7a, 7b, and 7c show the TWC light-off performance (NO xIn particular, the figure shows (a) NO conversion, CO conversion and THC conversion for the washcoated (B9) (aged) reference Pt fully formulated catalyst, and (B10) (aged) Pt catalyst with 20% CaMnO3 modified CZO support. x The perturbation aged TWC light-off performance versus (a) conversion, (b) CO conversion, and (c) THC conversion is shown. Reaction conditions: with rich pretreatment, 150-700°C, λ=0.96-1.04, GHSV=200,000hr -1 Compared to the reference Pt catalyst, the selected perovskite modified supports showed a significant improvement in TWC conversion.

[0137] 8a, 8b, and 8c show the TWC light-off performance (NO x In particular, the figure shows the conversion rates of the washcoated (B11) (aged) reference RhPt fully formulated catalyst, (B12) (aged) RhPt catalyst with 10% BaMnO3 modified CZO support, (B13) (aged) 10% La 0.9 (a) NO of (aged) RhPt catalyst with MnO3 modified CZO support and (B14) (aged) RhPt catalyst with 10% CaMnO3 modified CZO support x The perturbation aged TWC light-off performance versus (a) conversion, (b) CO conversion, and (c) THC conversion is shown. Reaction conditions: with rich pretreatment, 150-700°C, λ=0.96-1.04, GHSV=200,000hr -1 Compared to the reference RhPt catalyst, the selected perovskite modified supports showed a significant improvement in TWC conversion, with RhPt>10%La with 10%CaMnO3-CZO. 0.9 The order was RhPt with MnO3-CZO>RhPt with 10%BaMnO3-CZO.

[0138] The foregoing detailed description has been provided for purposes of explanation and illustration and is not intended to limit the scope of the appended claims. Many variations of the presently preferred embodiments described herein will be apparent to those of ordinary skill in the art and remain within the scope of the appended claims and their equivalents.

Claims

1. A composition comprising a ceria-zirconia mixed oxide, the ceria-zirconia mixed oxide being surface-modified with a perovskite-type compound of formula (I), Formula (I) is A ｘ－ｙ A' ｙ B １－ｚ B' ｚ O ３ is defined by: 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 0.7 to 1; y is 0 to 0.5; The composition wherein z is 0 to 0.

5.

2. 2. The composition of claim 1, wherein A and / or A' are ions of a metal selected from the group consisting of Ca, Mg, Ba, Ca, Y, La, Sr, Nd, Ce, and Gd.

3. 3. The composition of claim 2, wherein A and / or A' are ions of a metal selected from the group consisting of Ca, Ba, La, and Sr.

4. 3. The composition of claim 1, wherein B and / or B' are ions of a metal selected from the group consisting of Mn, Co, Fe, Zr and Ni.

5. 3. The composition of claim 1, wherein B and / or B' are ions of a metal selected from the group consisting of Mn, Zr, and Fe.

6. 3. The composition according to claim 1, wherein the ceria-zirconia mixed oxide is doped.

7. 7. The composition of claim 6, wherein 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, preferably La, Y, Nd and Pr.

8. 3. The composition according to claim 1, wherein the composition comprises 1 to 50 wt. %, preferably 5 to 30 wt. %, of the perovskite compound, based on the total weight of the perovskite compound and the ceria-zirconia mixed oxide.

9. A method for producing a composition comprising a ceria-zirconia mixed oxide, the ceria-zirconia mixed oxide being surface-modified with a perovskite compound of formula (I), Formula (I) is A ｘ－ｙ A' ｙ B １－ｚ B' ｚ O ３ is defined by: 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 0.7 to 1; y is 0 to 0.5; z is 0 to 0.5, and the method comprises: providing a solution comprising an organic acid, water, 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; and heating the slurry.

10. A method for producing a composition comprising a ceria-zirconia mixed oxide, the ceria-zirconia mixed oxide being surface-modified with a perovskite compound of formula (I), Formula (I) is A ｘ－ｙ A' ｙ B １－ｚ B' ｚ O ３ is defined by: 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 0.7 to 1; y is 0 to 0.5; z is 0 to 0.5, and the method comprises: contacting a ceria-zirconia mixed oxide with A, B, and optionally A' and / or B' by incipient wetness impregnation 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' to form an impregnated ceria-zirconia mixed oxide; and heating said impregnated ceria-zirconia mixed oxide.

11. A method for producing a composition comprising a ceria-zirconia mixed oxide, the ceria-zirconia mixed oxide being surface-modified with a perovskite compound of formula (I), Formula (I) is A ｘ－ｙ A' ｙ B １－ｚ B' ｚ O ３ is defined by: 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 0.7 to 1; y is 0 to 0.5; z is 0 to 0.5, and the method comprises: 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.

12. A method for producing a composition comprising a ceria-zirconia mixed oxide, the ceria-zirconia mixed oxide being surface-modified with a perovskite compound of formula (I), Formula (I) is A ｘ－ｙ A' ｙ B １－ｚ B' ｚ O ３ is defined by: 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 0.7 to 1; y is 0 to 0.5; z is 0 to 0.5, and the method comprises: providing an aqueous 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; contacting the slurry with a base; recovering a solid residue from the slurry; and heating the solid residue.

13. A catalytic article comprising a substrate, the substrate having the composition of claim 1 or 2 disposed thereon.

14. The catalyst article of claim 13 , wherein the catalyst article comprises a three-way catalyst (TWC), and preferably the catalyst article is a TWC.

15. The catalytic article of claim 13, wherein a platinum group metal (PGM) is supported on the composition.

16. 16. The catalytic article of claim 15, wherein the PGM comprises Pt, Pd, Rh, or a mixture or alloy thereof.

17. 1 g / in ３ ~3g / in ３ 14. The catalyst article of claim 13 having a washcoat loading of

18. The catalytic article of claim 13 , wherein the substrate comprises a wall-flow filter substrate or a flow-through substrate.

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