COMPOSITE OXIDE MATERIAL AND EXHAUST GAS PURIFICATION CATALYST USING SAME

摘要

The object of the present invention is to provide an oxygen storage material used for an exhaust gas purifying catalyst that is superior in stability at high temperatures. The composite oxide material of the invention comprises crystalline particles of a ceria-zirconia composite oxide with a pyrochlore structure and crystals of a ceria-zirconia composite oxide with a fluorite structure on the particle surface, in which the crystals of the ceria-zirconia composite oxide with a fluorite structure contains zirconia in a larger amount than that of ceria, and such crystals are integrated with the crystalline particles of the ceria-zirconia composite oxide with a pyrochlore structure. The composite oxide material of the invention has high oxygen storage capacity that is less likely to decrease at high temperatures.