Abstract: A method for producing an exhaust gas purifying catalyst including a composite oxide represented by the following general formula (3), the method including a primary baking step of baking a coprecipitate obtained from an aqueous mixed salt solution of respective elements, a citrate complex obtained from an aqueous citric acid mixed salt solution of salts of the respective elements and citric acid, or a precipitate obtained from an alkoxide mixed solution of the respective elements at 500 to 1200° C., the respective elements constituting the exhaust gas purifying catalyst represented by the following general formula (3), including A, B and Fe but excluding Pd; a step of adding an aqueous solution of Pd salt to a primary composite oxide obtained through the primary baking step to give a precursor composition; and a secondary baking step of baking the precursor composition at 800 to 1400° C., AO.x(B2-y-ZFeyPdZO3-?) (3).

Abstract: Provided is a catalyst composition capable of preventing decrease in catalytic activity due to grain growth of noble metal under high temperature or under change in oxidation reduction or further for long term use, and of achieving excellent catalytic activity over a long time. The catalyst composition containing a composite oxide represented by the following general formula (1): AO.x(B2-yCyO3-?)??(1) (wherein A represents an element selected from monovalent elements, divalent elements and lanthanides; B represents a trivalent element; and C represents a noble metal; x represents an integer of 1 to 6; y represents an atomic ratio satisfying the following relation; 0<y<2; and a represents a deficient, atomic ratio of oxygen atoms) is prepared.

Abstract: An excellent oxygen storage capacity is achieved even in the case used for a long period of time under high temperature conditions. An oxygen storage material contains a first particle made of a composite oxide of cerium and zirconium or a composite oxide of cerium, a rare-earth element other than cerium and zirconium, a second particle including a composite oxide of a rare-earth element, an alkaline-earth element and zirconium, and a precious metal. A part of the precious metal forms a solid solution with the composite oxide included in the second particle.

Abstract: Provided is a method for purifying exhaust gas discharged from an internal combustion engine of a vehicle, using an exhaust gas purifying catalyst including a composite oxide represented by the following general formula AO.x(B2-yCyO3-?), wherein A represents an element selected from monovalent elements, divalent elements and lanthanides; B represents a trivalent element; and C represents a noble metal; x represents an integer of 1; y represents an atomic ratio satisfying the following relation: 0<y<2; and ? represents a deficient atomic ratio of oxygen atoms; and wherein the composite oxide has a spinel type crystal phase, and wherein the exhaust gas purifying catalyst removes carbon monoxide (CO) exhaust gas discharged from the internal combustion engine of the vehicle.

Abstract: An exhaust gas-purifying catalyst (1) contains a rare-earth element, an alkaline-earth element, zirconium and a precious metal, wherein an atomic ratio of the alkaline-earth element with respect to a sum of the rare-earth element and the zirconium is 10 atomic % or more, a part of the rare-earth element and a part of zirconium form a composite oxide with at least a part of the alkaline-earth element, and the composite oxide and a part of the precious metal form a solid solution.

Abstract: An object of the present invention is to provide an exhaust gas-purifying catalyst that is less prone to cause a decrease in its activity even when used at high temperatures in an atmosphere whose oxygen concentration is high. An exhaust gas-purifying catalyst of the present invention includes a composite oxide of alkaline-earth metal and aluminum, and platinum, wherein at least a part of the composite oxide and at least a part of the platinum forms a solid solution.

Abstract: Provided is a catalyst with a noble metal efficiently supported on the surfacemost thereof. A composite oxide-containing layer is formed on a catalyst carrier so as to contain a perovskite-type composite oxide represented by the following general formula (1) and an other composite oxide, and a noble metal layer is further formed on the catalyst carrier so as to be supported on the surfacemost of the catalyst carrier by immersing the catalyst carrier formed with the composite oxide-containing layer in an aqueous noble metal salt solution to impregnate the catalyst carrier with the aqueous noble metal salt solution: AxByO3±???(1) (wherein A represents at least one element selected from rare earth elements and alkaline earth metals; B represents at least one element selected from transition elements (excluding rare earth elements); x represents an atomic ratio of less than 1; y represents an atomic ratio of 1.0; and ? represents an oxygen excess or an oxygen deficiency.

Abstract: Provided is a catalyst composition capable of preventing decrease in catalytic activity due to grain growth of noble metal under high temperature or under change in oxidation reduction or further for long term use, and of achieving excellent catalytic activity over a long time. The catalyst composition containing a composite oxide represented by the following general formula (1): AO.x(B2-yCyO3-?)??(1) (wherein A represents an element selected from monovalent elements, divalent elements and lanthanides; B represents a trivalent element; and C represents a noble metal; x represents an integer of 1 to 6; y represents an atomic ratio satisfying the following relation: 0<y<2; and ? represents a deficient atomic ratio of oxygen atoms) is prepared.

Abstract: The exhaust gas-purifying catalyst includes at least one of a first composite oxide represented by a formula A(Al2-xBx)O4 and a second composite oxide represented by a formula (Al2-yCy)O3, wherein element A is a divalent transition metal other than platinum-group elements, each of elements B and C is a transition metal other than platinum-group elements, x satisfies 0<x<2, and y satisfies 0<y<2.

Abstract: Disclosed is a catalyst composition containing a composite oxide. The composite oxide contains a transition element (excluding platinum group elements) which is transformed into a solid solution in the composite oxide under an oxidizing atmosphere and is precipitated from the composite oxide under a reducing atmosphere.

Abstract: An excellent oxygen storage capacity is achieved even in the case used for a long period of time under high temperature conditions. An oxygen storage material contains a first particle made of a composite oxide of cerium and zirconium or a composite oxide of cerium, a rare-earth element other than cerium and zirconium, a second particle including a composite oxide of a rare-earth element, an alkaline-earth element and zirconium, and a precious metal. A part of the precious metal forms a solid solution with the composite oxide included in the second particle.

Abstract: To provide a heat-resistant oxide which is excellent in heat resistance and durability at high temperature and has high activity, a heat-resistant oxide which has an oxide crystal structure and in which a rate of a solid solution of a noble metal in the oxide crystal structure is 50% or more is obtained by heat-treating (secondarily baking) a precursor composition comprising zirconia, at least one coordinative element selected from the group consisting of rare earth elements, alkaline earth elements, aluminum and silicon, and at least one noble metal selected from the group consisting of platinum, rhodium and palladium at 650° C. or higher.

Abstract: To provide a method for industrially efficiently producing an exhaust gas purifying catalyst containing a perovskite-type composite oxide which is stable and has a less reduced specific surface area and is also effectively prevented from decreasing in its catalytic performance even in endurance in high temperature oxidative reducing atmospheres, a pre-crystallization composition containing elementary components constituting a perovskite-type composite oxide containing a noble metal is prepared, is mixed with a powder of theta-alumina and/or alpha-alumina to prepare a mixture, and the mixture is heat treated. Thus, the resulting perovskite-type composite oxide supported by the powder of theta-alumina and/or alpha-alumina can keep its thermostability at a sufficient level thereby to effectively prevent the catalytic performance from decreasing. This method can industrially efficiently produce the exhaust gas purifying catalyst.

Abstract: To provide a perovskite-type composite oxide which has stable quality in which a solid solution of Pd is formed at a high rate, a method for producing the perovskite-type composite oxide, and a catalyst composition containing the perovskite-type composite oxide, the perovskite-type composite oxide is produced by formulating materials in accordance with each atomic ratio of a perovskite-type composite oxide represented by the following general formula (1): AxB(1-y)PdyO3+???(1) wherein A represents at least one element selected from rare earth elements and alkaline earth metals; B represents at least one element selected from transition elements (excluding rare earth elements, and Pd), Al and Si; x represents an atomic ratio satisfying the following condition: 1<x; y represents an atomic ratio satisfying the following condition: 0<y?0.5; and ? represents an oxygen excess.

Abstract: Provided is a catalyst with a noble metal efficiently supported on the surfacemost thereof. A composite oxide-containing layer is formed on a catalyst carrier so as to contain a perovskite-type composite oxide represented by the following general formula (1) and an other composite oxide, and a noble metal layer is further formed on the catalyst carrier so as to be supported on the surfacemost of the catalyst carrier by immersing the catalyst carrier formed with the composite oxide-containing layer in an aqueous noble metal salt solution to impregnate the catalyst carrier with the aqueous noble metal salt solution: AxByO3±???(1) (wherein A represents at least one element selected from rare earth elements and alkaline earth metals; B represents at least one element selected from transition elements (excluding rare earth elements); x represents an atomic ratio of less than 1; y represents an atomic ratio of 1.0; and ? represents an oxygen excess or an oxygen deficiency.

Abstract: A catalyst composition which prevents deterioration due to grain growth of Rh and/or Pt, includes a perovskite-type composite oxide represented by the following general formula (1): A1?xA?xB1?(y+z)B?yNzO3??(1) wherein A represents at least one element selected from alkaline earth metals; A? represents at least one element selected from rare earth elements; B represents at least one element selected from Ti, Zr, and Hf; B? represents at least one element selected from transition elements (excluding rare earth elements, Ti, Zr, Hf, Rh, and Pt) and Al; N represents at least one element selected from Rh and Pt; x represents an atomic ratio satisfying the following condition: 0?x?0.4; y represents an atomic ratio satisfying the following condition: 0?y<0.5; z represents an atomic ratio satisfying the following condition: 0<z?0.5; and X represents 0 when N represents Pt alone.

Abstract: An exhaust gas-purifying catalyst is less prone to cause a decrease in its activity even when used in a high temperature atmosphere containing oxygen at a high concentration. The exhaust gas-purifying catalyst includes a composite oxide and Pd or a second solid solution of a composite and Rh and/or Pt. The first and second solid solutions have perovskite structure and are represented by ABO3 and CDO3, respectively. The composite oxide catalyst is supported by a composite oxide support including a composite oxide of spinel structure represented by EF2O4 or a composite oxide represented by GAl12O19. A and B represent a rare-earth element and a transition element, respectively. C and G represent an alkaline-earth element. D represents one or more of Ti, Zr, Hf and Ce. E represents an alkaline-earth element and/or a transition element. F represents one or more of Al, Mg and transition elements.

Abstract: To provide a catalyst composition containing a novel perovskite-type composite oxide which permits reversible entrance and exit of noble metals, a catalyst composition is prepared so as to contain a perovskite-type composite oxide represented by the general formula (1): AxA?wByB?(1-y-z)NzO3±???(1) (wherein A represents at least one element selected from alkaline earth metals; A? represents at least one element selected from rare earth elements; B represents a tetravalent rare earth element; B? represents at least one element selected from transition elements (excluding tetravalent rare earth elements, Rh, Pd and Pt); N represents at least one element selected from Rh, Pd and Pt; x and w represent an atomic ratio satisfying the following relations: 0.8?x+w?1.3 (0.8?x?1.3, 0?w?0.4); y represents an atomic ratio satisfying the following relation: 0<y<1.0; z represents an atomic ratio satisfying the following relation: 0<z?0.5; and ? represents an oxygen excess or deficiency amount).

Abstract: An exhaust gas-purifying catalyst (1) contains a rare-earth element, an alkaline-earth element, zirconium and a precious metal, wherein an atomic ratio of the alkaline-earth element with respect to a sum of the rare-earth element and the zirconium is 10 atomic % or more, a part of the rare-earth element and a part of zirconium form a composite oxide with at least a part of the alkaline-earth element, and the composite oxide and a part of the precious metal form a solid solution.

Abstract: An object of the present invention is to provide a catalyst composition containing a perovskite-type composite oxide which exhibits a satisfactory catalytic performance over a long time even in a high temperature atmosphere and has a stable quality in which Rh and/or Pt dissolves to form a solid solution at a high rate. To achieve the object described above, in the present invention the catalyst composition is prepared to comprise an Rh-containing perovskite-type composite oxide represented by the following general formula (I) and/or a Pt-containing perovskite-type composite oxide represented by the following general formula (II) and a thermostable oxide optionally containing a noble metal.