EXHAUST EMISSION PURIFIER FOR INTERNAL COMBUSTION ENGINE

摘要

PURPOSE:To suppress the increase of an exhaust amount of transient NOx when an air-fuel ratio is changed from lean to stoic. CONSTITUTION:An NOx catalyst 6 containing quantities of La (0.03mol/1cat or more) and carrying platinum is disposed in the exhaust gas passage 4 of a lean combustible internal combustion engine 2. A three-component catalyst 8 is disposed on the downstream of the NOx catalyst. When an air-fuel ratio is changed from lean to stoic, NOx separated from the NOx catalyst 6 is purified by means of a three-component catalyst 8.