Abstract: The present invention provides a cerium-zirconium based compound oxide having a total pore volume of at least 0.4 ml/g, the volume of pores having a diameter of 10 nm to 100 nm of 0.25 ml/g or more, and the volume of pores having a diameter of 100 nm to 10 ?m of 0.2 ml/g or less. The cerium-zirconium based compound oxide preferably has excellent thermal stability, which allows the desirable pore volume to be maintained even after conducting a further heat treatment at 1,000° C. for 3 hours.

Abstract: The present invention provides a zirconia-based mixed oxide which, together with improving the heat resistance of specific surface area at a high temperature (1000° C. for 3 hours), has a ceria reduction rate of 80% or more, or in other words, improves the heat resistance of specific surface area and the reduction rate of ceria. The zirconia-based mixed oxide has zirconia for the main component thereof and contains 5% or more of ceria and 1 to 30% of a rare earth metal oxide other than ceria, wherein the specific surface area after heat treating for 3 hours at 1000° C. is 50 m2/g or more, the reduction rate of the ceria contained in the mixed oxide is 80% or more, and preferably the specific surface area after heat treating for 3 hours at 1100° C. is 20 m2/g or more.

Abstract: A catalyst system to be used in an automobile exhaust gas purification apparatus which exerts excellent purification capability to a nitrogen oxide, even when hydrocarbon concentration varies, by subjecting exhaust gas discharged from an automotive internal engine to contacting with a catalyst, an exhaust gas purification apparatus using the same, and an exhaust gas purification method. A catalyst system etc.

Abstract: A cerium-zirconium mixed oxide with improved heat resistance of the specific surface area at a high temperature (1000° C.) is provided along with a manufacturing method therefor. This cerium-zirconium mixed oxide comprises of spherical particles 5 to 20 nm in size and rodlike particles 5 to 20 nm in diameter and to 150 nm in length, and preferably has a pore volume of 0.3 cm3/g or more and a specific surface area of 35 m2/g or more after 5 hours of heat treatment at 1000° C.

Abstract: A zirconia porous body with excellent stability of heat resistance is manufactured. This relates to a zirconia porous body having peaks at pore diameters of 8 to 20 nm and 30 to 100 nm in a pore distribution based on the BJH method, with a total pore volume of 0.4 cc/g or more, and to a zirconia porous body having a peak at a pore diameters of 20 to 110 nm in a pore distribution based on the BJH method, with a total pore volume of 0.4 cc/g or more.

Abstract: A sol of the present invention is a sol comprising zirconium oxalate compound as a dispersoid, wherein a mol ratio of oxalic acid to Zr (oxalic acid/Zr) is from 1.2 to 3 and a particle diameter D50 of the dispersoid is from 10 to 100 nm. This sol is produced by adding oxalic acid to a dispersion liquid of zirconium hydroxide, and the addition of oxalic acid is carried out in twice.

Abstract: To provide an yttria-stabilized zirconia sintered body having high hydrothermal deterioration resistance in addition to excellent thermal shock resistance. Methods for Achieving the Object A stabilized zirconia sintered body comprising yttria, wherein 1) the sintered body is substantially composed of monoclinic crystals and cubic crystals; and 2) an increase of the monoclinic crystals included in the sintered body is 10% by volume or less after the body is subjected to hydrothermal deterioration test for 5 hours, at 180° C., at 10 atmospheres.

Abstract: A zirconia porous body with excellent stability of heat resistance is manufactured. This relates to a zirconia porous body having peaks at pore diameters of 8 to 20 nm and 30 to 100 nm in a pore distribution based on the BJH method, with a total pore volume of 0.4 cc/g or more, and to a zirconia porous body having a peak at a pore diameters of 20 to 110 nm in a pore distribution based on the BJH method, with a total pore volume of 0.4 cc/g or more.

Abstract: The present invention provides a catalyst system for vehicle exhaust gas purification devices which exhibit excellent capacity of removing nitrogen oxide emissions from internal combustion engine exhaust gases when they are brought into contact with the catalyst even when hydrocarbon concentration in exhaust gases varies, exhaust gas purification device using the same and method for purification of exhaust gases.

Abstract: A cerium-zirconium mixed oxide with improved heat resistance of the specific surface area at a high temperature (1000° C.) is provided along with a manufacturing method therefor. This cerium-zirconium mixed oxide comprises of spherical particles 5 to 20 nm in size and rodlike particles 5 to 20 nm in diameter and 30 to 150 nm in length, and preferably has a pore volume of 0.3 cm3/g or more and a specific surface area of 35 m2/g or more after 5 hours of heat treatment at 1000° C.

Abstract: A zirconium- and cerium-based mixed oxide having good thermal stability and oxidation-reduction performance, in particular, is provided. The mixed oxide which comprises zirconium and cerium is characterized in (1) that cubic phase purity of a zirconia- and ceria-based solid solution is not less than 95% by volume of the crystal phase thereof and (2) that the cubic phase purity is not less than 75% by volume even after two repetitions of the step of subjecting the mixed oxide to heat treatment at 1,000° C. and then cooling the same to room temperature. A method of producing the mixed oxide is also provided which comprises admixing basic zirconium sulfate with a cerium ion-containing solution and then adding a base to the resulting mixed solution to thereby causing formation of a precipitate.

Abstract: Mixed oxides excellent in thermal stability of specific surface area and in oxidation-reduction performance are provided on an industrial scale. Catalyst materials useful in exhaust gas purification are also provided. The invention is concerned with mixed oxides containing cerium, zirconium and sulfur, namely cerium- and zirconium-based mixed oxides having the composition: 50 to 79% by weight as cerium oxide, 20 to 49% by weight as zirconium oxide, and 1 to 5% by weight as sulfate (SO.sub.4). The invention also relates to a method of producing cerium- and zirconium-based mixed oxides which comprises mixing a cerous-alkali metal sulfate double salt with a zirconium ion-containing solution and then adding a base to the mixed solution to thereby cause formation of a precipitate. The invention further relates to catalyst materials for exhaust gas purification which comprise a mixed oxide containing cerium, zirconium and sulfur, namely a cerium- and zirconium-based mixed oxide containing sulfur in an amount of 0.

Abstract: The present invention provides novel amorphous phosphosilicates represented by the formulae Zr(PO.sub.4).sub.2y (SiO.sub.2).sub.z.n'H.sub.2 O (I) and M.sub.2/l Zr(PO.sub.4).sub.2y (SiO.sub.2).n'H.sub.2 O (III) and the processes for producing the same.