Abstract: A porous composite metal oxide, including a mixture of first ultrafine particles containing alumina and second ultrafine particles containing zirconia, wherein the first ultrafine particles and the second ultrafine particles are uniformly dispersed in such a way as to satisfy a condition that standard deviations of content ratios (% by mass) of all metal elements contained in the porous composite metal oxide at 0.1% by mass or more are each 10 or less, the standard deviations being obtained by measuring content ratios of the metal elements at 100 measurement points within a minute analysis region of 20 nm square by energy dispersive X-ray spectroscopy using a scanning transmission electron microscope equipped with a spherical aberration correction function.

Abstract: A ceria-zirconia base composite oxide contains a composite oxide of ceria and zirconia. In the ceria-zirconia base composite oxide, a content ratio between cerium and zirconium in the composite oxide is in a range from 43:57 to 48:52 in terms of molar ratio ([cerium]:[zirconium]). An intensity ratio of a diffraction line at 2?=14.5° to a diffraction line at 2?=29° {I(14/29) value} and an intensity ratio of a diffraction line at 2?=28.5° to the diffraction line at 2?=29° {I(28/29) value}, which are calculated from an X-ray diffraction pattern obtained by an X-ray diffraction measurement using CuKa after heating under a temperature condition of 1100° C. in air for 5 hours, respectively satisfy the following conditions: I(14/29) value?0.015, and I(28/29) value?0.08.

Abstract: A method of synthesizing metal composite oxide, the method including: a step of separately introducing into a high-speed stirring apparatus a ceria composite oxide microparticle colloid having a mean particle diameter of 10 nm or less after adding a dispersant and an alumina microparticle colloid having a mean particle diameter of 10 nm or less after adding a dispersant; a step of synthesizing alumina-ceria composite oxide microparticles by allowing the ceria composite oxide microparticles and the alumina microparticles that have been introduced into the high-speed stirring apparatus to react in a microscopic space; and a step of applying a shearing force of 17000 sec?1 or more to the alumina-ceria composite oxide microparticles.

Abstract: An exhaust gas purifying catalyst that contains a first oxygen storage material on which no noble metal is supported and which has a pyrochlore phase type regular array structure, and a second oxygen storage material which has a higher oxygen storage rate and a lower oxygen storage capacity than the first oxygen storage material and on which a platinum group noble metal is supported.

Abstract: A ceria-zirconia base composite oxide contains a composite oxide of ceria and zirconia. In the ceria-zirconia base composite oxide, a content ratio between cerium and zirconium in the composite oxide is in a range from 43:57 to 48:52 in terms of molar ratio ([cerium]: [zirconium]). An intensity ratio of a diffraction line at 2?=14.5° to a diffraction line at 2?=29° {I(14/29) value} and an intensity ratio of a diffraction line at 2?=28.5° to the diffraction line at 2?=29° {I(28/29) value}, which are calculated from an X-ray diffraction pattern obtained by an X-ray diffraction measurement using CuKa after heating under a temperature condition of 1100° C. in air for 5 hours, respectively satisfy the following conditions: I(14/29)value?0.015, and I(28/29)value?0.08.

Abstract: A method of synthesizing metal composite oxide, the method including: a step of separately introducing into a high-speed stirring apparatus a ceria composite oxide microparticle colloid having a mean particle diameter of 10 nm or less after adding a dispersant and an alumina microparticle colloid having a mean particle diameter of 10 nm or less after adding a dispersant; a step of synthesizing alumina-ceria composite oxide microparticles by allowing the ceria composite oxide microparticles and the alumina microparticles that have been introduced into the high-speed stirring apparatus to react in a microscopic space; and a step of applying a shearing force of 17000 sec?1 or more to the alumina-ceria composite oxide microparticles.

Abstract: A particulate inorganic oxide containing aluminum oxide, a metal oxide forming no composite oxide with aluminum oxide, and an additional element including at least one of a rare-earth element and an alkali earth element, the inorganic oxide containing a secondary particle formed by aggregating primary particles; wherein at least a part of the secondary particle includes a plurality of first primary particles, each having a particle size of 100 nm or less, containing aluminum oxide and the additional element, and a plurality of second primary particles, each having a particle size of 100 nm or less, containing the metal oxide and the additional element; wherein at least a part of the first and second primary particles has a surface concentrated region where the additional element has a locally increased content in a surface layer part thereof.

Abstract: A porous composite metal oxide, including a mixture of first ultrafine particles containing alumina and second ultrafine particles containing zirconia, wherein the first ultrafine particles and the second ultrafine particles are uniformly dispersed in such a way as to satisfy a condition that standard deviations of content ratios (% by mass) of all metal elements contained in the porous composite metal oxide at 0.1% by mass or more are each 10 or less, the standard deviations being obtained by measuring content ratios of the metal elements at 100 measurement points within a minute analysis region of 20 nm square by energy dispersive X-ray spectroscopy using a scanning transmission electron microscope equipped with a spherical aberration correction function.

Abstract: An exhaust gas purifying catalyst that contains a first oxygen storage material on which no noble metal is supported and which has a pyrochlore phase type regular array structure, and a second oxygen storage material which has a higher oxygen storage rate and a lower oxygen storage capacity than the first oxygen storage material and on which a platinum group noble metal is supported.

Abstract: A method of producing a porous composite metal oxide comprising the steps of: dispersing first metal oxide powder, which is an aggregate of primary particles each with a diameter of not larger than 50 nm, in a dispersion medium by use of microbeads each with a diameter of not larger than 150 ?m, thus obtaining first metal oxide particles, which are 1 nm to 50 nm in average particle diameter, and not less than 80% by mass of which are not larger than 75 nm in diameter; dispersing and mixing up, in a dispersion medium, the first metal oxide particles and second metal oxide powder, which is an aggregate of primary particles each with a diameter of not larger than 50 nm, and which is not larger than 200 nm in average particle diameter, thus obtaining a homogeneously-dispersed solution in which the first metal oxide particles and second metal oxide particles are homogeneously dispersed; and drying the homogeneously-dispersed solution, thus obtaining a porous composite metal oxide.

Abstract: A particulate inorganic oxide contains an aluminum oxide, a metal oxide forming no composite oxide with an aluminum oxide, and at least one additional element selected from the group consisting of rare earth elements and alkaline earth elements. In the inorganic oxide, a percentage content of the aluminum oxide to a total amount of aluminum in the aluminum oxide, a metal element in the metal oxide, and the additional element is in a range from 48 at % to 92 at % in terms of element content. At least 80% of primary particles in the inorganic oxide have a particle diameter of 100 nm or smaller. At least a part of the primary particles have a surface concentrated region where a percentage content of the additional element is locally increased in a surface layer part thereof. The content of the additional element in the surface concentrated region to a whole amount of the inorganic oxide is in a range from 0.06% by mass to 0.98% by mass in terms of oxide amount.

Abstract: A particulate inorganic oxide contains an aluminum oxide, a metal oxide forming no composite oxide with an aluminum oxide, and at least one additional element selected from the group consisting of rare earth elements and alkaline earth elements. In the inorganic oxide, a percentage content of the additional element to a total amount of aluminum in the aluminum oxide, a metal element in the metal oxide, and the additional element is in a range from 1.1 at % to 8.0 at % in terms of element content. At least 80% of primary particles in the inorganic oxide have a particle diameter of 100 nm or smaller. At least a part of the primary particles have a surface concentrated region where a percentage content of the additional element is locally increased in a surface layer part thereof. The content of the additional element in the surface concentrated region to a whole amount of the inorganic oxide is in a range from 0.06% by mass to 0.98% by mass in terms of oxide amount.

Abstract: A particulate inorganic oxide containing aluminum oxide, a metal oxide forming no composite oxide with aluminum oxide, and an additional element including at least one of a rare-earth element and an alkali earth element, the inorganic oxide containing a secondary particle formed by aggregating primary particles; wherein at least a part of the secondary particle includes a plurality of first primary particles, each having a particle size of 100 nm or less, containing aluminum oxide and the additional element, and a plurality of second primary particles, each having a particle size of 100 nm or less, containing the metal oxide and the additional element; wherein at least a part of the first and second primary particles has a surface concentrated region where the additional element has a locally increased content in a surface layer part thereof.

Abstract: A metal oxide which has a large pore volume, and is very useful as a catalyst support. An alkaline material is added to an aqueous solution in which a compound of a metal element for composing an oxide is dissolved, a resultant mixture is co-precipitated, an obtained precipitate is washed, a washed precipitate is stirred in water along with a surfactant, and is calcined. By adding the surfactant after washing, the pH is not changed so that the adding effect of the surfactant is achieved to its upper most limit, thereby obtaining a metal oxide which has a large pore volume and a large mean diameter of secondary particles, and exhibits excellent gas diffusion properties.

Abstract: A method of producing a porous composite metal oxide comprising the steps of: dispersing first metal oxide powder, which is an aggregate of primary particles each with a diameter of not larger than 50 nm, in a dispersion medium by use of microbeads each with a diameter of not larger than 150 ?m, thus obtaining first metal oxide particles, which are 1 nm to 50 nm in average particle diameter, and not less than 80% by mass of which are not larger than 75 nm in diameter; dispersing and mixing up, in a dispersion medium, the first metal oxide particles and second metal oxide powder, which is an aggregate of primary particles each with a diameter of not larger than 50 nm, and which is not larger than 200 nm in average particle diameter, thus obtaining a homogeneously-dispersed solution in which the first metal oxide particles and second metal oxide particles are homogeneously dispersed; and drying the homogeneously-dispersed solution, thus obtaining a porous composite metal oxide.

Abstract: A metal oxide which has a large pore volume, and is very useful as a catalyst support. An alkaline material is added to an aqueous solution in which a compound of a metal element for composing an oxide is dissolved, a resultant mixture is co-precipitated, an obtained precipitate is washed, a washed precipitate is stirred in water along with a surfactant, and is calcined. By adding the surfactant after washing, the pH is not changed so that the adding effect of the surfactant is achieved to its upper most limit, thereby obtaining a metal oxide which has a large pore volume and a large mean diameter of secondary particles, and exhibits excellent gas diffusion properties.