Exhaust emission control device of internal combustion engine

摘要

An exhaust gas purification device of an internal combustion engine arranging a catalyst (22) suitable for reduction of NOx in exhaust gas by ammonia in the presence of excess oxygen in an engine exhaust passage (21), said device comprising: feeding means (31,32,33) for feeding a liquid (30) containing an ammonia generating compound to the catalyst; feed control means (40) for controlling the amount of feed of the liquid, decision means (40) for deciding if the temperature of the catalyst is in an ammonia generating compound storage region, or if the temperature of the catalyst is in an ammonia release region which causes the ammonia to be released a little at a time from the stored ammonia generating compound; wherein, when the engine is decelerated in a state where the supply of fuel is stopped, and thus, an amount of NOx in the exhaust gas becomes zero, said feeding means (40) feeds the liquid to store the ammonia generating compound in the catalyst.