摘要:
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 2θ=14.5° to a diffraction line at 2θ=29° {I(14/29) value} and an intensity ratio of a diffraction line at 2θ=28.5° to the diffraction line at 2θ=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.
摘要:
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 2θ=14.5° to a diffraction line at 2θ=29° {I(14/29) value} and an intensity ratio of a diffraction line at 2θ=28.5° to the diffraction line at 2θ=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.
摘要:
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.
摘要:
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.
摘要:
The object of the present invention is to provide an exhaust gas purifying catalyst that can achieve high purification performance while suppressing H2S emissions. The object is solved by an exhaust gas purifying catalyst in which the top layer of a catalyst coating layer comprises a ceria-zirconia composite oxide having a pyrochlore-type ordered array structure, in which the ceria-zirconia composite oxide contains at least one additional element selected from the group consisting of praseodymium, lanthanum, and yttrium at 0.5 to 5.0 mol % in relation to the total cation amount, and the molar ratio of (cerium+additional element):(zirconium) is within the range from 43:57 to 48:52.
摘要:
The object of the present invention is to provide an exhaust gas purifying catalyst that can achieve high purification performance while suppressing H2S emissions. The object is solved by an exhaust gas purifying catalyst in which the top layer of a catalyst coating layer comprises a ceria-zirconia composite oxide having a pyrochlore-type ordered array structure, in which the ceria-zirconia composite oxide contains at least one additional element selected from the group consisting of praseodymium, lanthanum, and yttrium at 0.5 to 5.0 mol % in relation to the total cation amount, and the molar ratio of (cerium+additional element):(zirconium) is within the range from 43:57 to 48:52.
摘要:
The object of the present invention is to provide a high-performance exhaust gas purifying catalyst that can achieve oxygen absorption/release capacity and NOx purification performance. The object is solved by an exhaust gas purifying catalyst, which comprises a ceria-zirconia composite oxide having a pyrochlore-type ordered array structure in the upstream part of the catalyst coating layer, in which the ceria-zirconia composite oxide contains at least one additional element selected from the group consisting of praseodymium, lanthanum, and yttrium at 0.5 to 5.0 mol % of the total cation amount, and has a molar ratio of (cerium+the additional element):(zirconium) of 43:57 to 48:52.
摘要:
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.
摘要:
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 μm, 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.
摘要:
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.