CATALYST FOR CLEANING EXHAUST GAS

摘要

PROBLEM TO BE SOLVED: To provide a catalyst for cleaning exhaust gas, deterioration of cleaning performance of which after an endurance test is performed at high temperature is suppressed.

SOLUTION: Both of an upper catalyst layer and a lower catalyst layer contain ceria and zirconia and have the same molar ratio of (CeO2/ZrO2) of 20/80 to 40/60, and further the molar ratios of (CeO2/ZrO2) in the upper catalyst layer and the lower catalyst layer are set equal. Though the reason is not clear, the shift of Rh existing in the upper catalyst layer to the lower catalyst layer is suppressed in a high-temperature oxidative atmosphere.

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