Exhaust emission control apparatus for internal combustion engine

摘要

In an exhaust emission control apparatus having an NOx catalyst (9) disposed in an exhaust passage (8) of an internal combustion engine, the present invention is intended to suppress deterioration in exhaust emissions when the temperature of the NOx catalyst is raised. In case where the temperature of the NOx catalyst (9) need be raised, an amount of nitrogen oxides occluded in the NOx catalyst is decreased in advance to the raising of the temperature of the NOx catalyst, whereby the amount of nitrogen oxides to be discharged from the NOx catalyst upon raising the temperature of the NOx catalyst can be decreased. <IMAGE>