EXHAUST PURIFYING DEVICE FOR INTERNAL COMBUSTION ENGINE

摘要

A NOx removing device (4) having NOx absorbing ability and ammonia holding ability is arranged in an exhaust pipe (2) of an internal combustion engine (1). A reforming catalyst (3) is arranged in the upstream of the NOx removing device (4). The reforming catalyst (3) produces hydrogen and carbon monoxide through a steam reforming reaction when the exhaust is in a reducing atmosphere. The hydrogen and carbon monoxide produced by the reforming catalyst (3) is supplied to the NOx removing device (4) and contributes to formation of ammonia. The thus-produced ammonia is held in the NOx removing device (4) and reduces NOx in the exhaust when the exhaust is in an oxidizing atmosphere.