OSC MATERIAL-CONTAINING CATALYST FOR CLEANING EXHAUST GAS

摘要

PROBLEM TO BE SOLVED: To provide a catalyst for cleaning exhaust gas further improved in the exhaust gas cleaning performance, among various exhaust gas cleaning catalysts proposed containing a ceria/zirconia (CeO2-ZrO2) composite oxide as the OSC material.

SOLUTION: The catalyst for cleaning exhaust gas has the OSC material disposed in a preceding stage and a rear stage of the catalyst. The absorbing/discharging speed of the OSC material disposed in the preceding stage is faster than that of the OSC material disposed in the rear stage. A ratio Ra/Rb of the particle size (Ra) of the OSC material disposed in the preceding stage and the particle size (Rb) of the OSC material disposed in the rear stage is less than 1.0.

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