Device for purifying exhaust gas for engine

摘要

A device, for purifying exhaust gas of an engine, comprises a SOx storage arranged in the exhaust passage for temporarily storing SOx contained in an exhaust gas inflowing therein, and an auxiliary catalyst arranged in the exhaust passage downstream of the SOx storage, the auxiliary catalyst having an oxidizing ability. When SOx stored in the SOx storage is discharged therefrom with the atmosphere of the auxiliary catalyst being in a sulfate forming atmosphere, the atmosphere of the auxiliary catalyst is changed to an atmosphere other than the sulfate forming atmosphere. When SOx stored in the SOx storage is discharged therefrom with the atmosphere of the auxiliary catalyst being in an atmosphere other than the sulfate forming atmosphere, the atmosphere of the auxiliary catalyst is maintained at an atmosphere other than the sulfate forming atmosphere.