Abstract: An object of the present invention is to provide means for releasing oxygen at a temperature lower than conventional means in an exhaust gas purification catalyst. A Ce—Zr composite oxide is provided, which has a crystallite diameter of 6.5 nm or less and a BET specific surface area of 90 m2/g or more.

Abstract: An exhaust gas cleaning catalyst is provided with a fire-resistant three-dimensional structural body, a first catalyst layer provide on a first surface side of the fire-resistant three-dimensional structural body, and a second catalyst layer provided on a side of the first catalyst layer opposite to the fire-resistant three-dimensional structural body. The first catalyst layer contains: a complex oxide including cerium and zirconium; and elemental rhodium. The second catalyst layer contains: a complex oxide including cerium and zirconium; and elemental palladium. The amount of cerium included in the second catalyst layer, in terms of cerium dioxide, is 10-25 g per liter of the fire-resistant three-dimensional structural body.

Abstract: An object of the present invention is to provide means for improving the hydrogen generation properties of a hydrogen-producing catalyst. A hydrogen-producing catalyst according to one aspect of the present invention comprises Rh and a composite containing Al, Ce, and Zr. When a ratio of the number of Al atoms to the number of Ce atoms (Al/Ce) in the composite measured by X-ray fluorescence (XRF) analysis is R1 and a ratio of the number of Al atoms to the number of Ce atoms (Al/Ce) in the composite measured by an X-ray photoelectron spectroscopy (XPS) method is R2, a value of R2/R1 is greater than 2.25 and less than 5.92.

Abstract: An exhaust gas cleaning catalyst is provided with a fire-resistant three-dimensional structural body, a first catalyst layer provide on a first surface side of the fire-resistant three-dimensional structural body, and a second catalyst layer provided on a side of the first catalyst layer opposite to the fire-resistant three-dimensional structural body. The first catalyst layer contains: a complex oxide including cerium and zirconium; and elemental rhodium. The second catalyst layer contains: a complex oxide including cerium and zirconium; and elemental palladium. The amount of cerium included in the second catalyst layer, in terms of cerium dioxide, is 10-25 g per liter of the fire-resistant three-dimensional structural body.

Abstract: An object of the present invention is to provide means for improving the hydrogen generation properties of a hydrogen-producing catalyst. A hydrogen-producing catalyst according to one aspect of the present invention comprises Rh and a composite containing Al, Ce, and Zr. When a ratio of the number of Al atoms to the number of Ce atoms (Al/Ce) in the composite measured by X-ray fluorescence (XRF) analysis is RI and a ratio of the number of Al atoms to the number of Ce atoms (Al/Ce,) in the composite measured by an Xray photoelectron spectroscopy (XPS) method is R2, a value of R2-R1 is greater than 2.25 and less than 5.92.