EXHAUST PURIFICATION DEVICE FOR INTERNAL COMBUSTION ENGINE

摘要

A hydrocarbon supply valve (15), an exhaust purification catalyst (13), and a particulate filter (14) are arranged in the engine exhaust passage of an internal combustion engine. When hydrocarbons are supplied from the hydrocarbon supply valve (15) with a period of five seconds or less, reductive intermediates are generated within the exhaust purification catalyst (13), and the NOx is purified by these reductive intermediates. When it is time to discharge the absorbed SOx from the exhaust purification catalyst (13), the air-fuel ratio of the exhaust gas flowing into the exhaust purification catalyst is made rich and the reductive intermediates that have accumulated on the exhaust purification catalyst (13) are desorbed in the form of ammonia, and the absorbed SOx from the exhaust purification catalyst (13) is discharged by means of the desorbed ammonia.