EXHAUST GAS PURIFICATION APPARATUS FOR INTERNAL COMBUSTION ENGINE

摘要

An internal combustion engine wherein an NO X storing catalyst (12) is arranged in an engine exhaust passage and an NO X selective reducing catalyst (14) is arranged downstream of the NO X storing catalyst (12). Just before the air-fuel ratio of the exhaust gas flowing into the NO X storing catalyst (12) is temporarily switched from lean to rich to release NO X from the NO X storing catalyst (12), an amount of NO X necessary for removing ammonia adsorbed on the NO X selective reducing catalyst (14) is fed to the NO X selective reducing catalyst (14) under a lean air-fuel ratio.