ABGASREINIGUNGSVORRICHTUNG FÜR VERBRENNUNGSMOTOR

摘要

An exhaust purification catalyst (11) for purifying NOx under a lean air-fuel ratio is arranged in exhaust passage of an internal combustion engine. As a catalyst carrier (50) of this exhaust purification catalyst (11), alumina, which has base points on the carrier surface, is used. The surface of the alumina is made to carry platinum (51) dispersed on it without forming a layer of a NOx absorbent able to absorb NOx. The air-fuel ratio of the exhaust gas flowing into the exhaust purification catalyst (11) is temporarily switched from lean to rich before the entire surface of the platinum (51) suffers from oxygen poisoning.