| 摘要 |
An oxidation catalyst is provided which is capable of combusting PM in a diesel engine exhaust gas at a low temperature and which has low degradation due to heat generated during combustion (i.e., has high heat resistance). A composite oxide for an exhaust gas purification catalyst is formed from Ce, Bi, R, R′, and oxygen, and when the molar ratios of Ce, Bi, R, and R′ are expressed as Ce:Bi:R:R′=(1−x−y−z) :x:y:z, it satisfies 0<x≦̸0.4, 0<y<1.0, and 0<z≦̸0.5. Since this composite oxide has no change in its BET value even when treated at a high temperature, and can withstand a high amount of sulfur poisoning, retrogradation due to poisoning is low. Therefore, this exhaust gas purification catalyst is suitable as a PM combustion catalyst.
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