Patent ID: 8307639

Claim:
An exhaust purification device of an internal combustion engine, the exhaust purification device comprising: an SO x trap catalyst disposed in an engine exhaust passage, the SO x trap catalyst able to trap SO x contained in an exhaust gas and having a property of trapping the SO x contained in the exhaust gas when an air-fuel ratio of the exhaust gas flowing into the SO x trap catalyst is lean and having the trapped SO x gradually diffuse to an inside of the SO x trap catalyst when a temperature of the SO x trap catalyst rises under a lean air-fuel ratio of the exhaust gas; and an electronic control unit having control logic configured to control a hydrocarbon supply valve disposed upstream of the SO x trap catalyst so that the hydrocarbon supply valve increases an amount of hydrocarbons in the exhaust gas flowing into the SO x trap catalyst by an amount that causes a locally rich region in which an air-fuel ratio locally becomes rich to be formed in an upstream side of the SO x trap catalyst, the control logic causing the amount of increase of the hydrocarbons to be set so that the SO x released from the locally rich region in the upstream side of the SO x trap catalyst is trapped in the SO x trap catalyst once again at a more downstream side of the SO x trap catalyst without flowing out from a downstream end of the SO x trap catalyst, thereby increasing an SO x trap rate of the SO x trap catalyst and prolonging a lifetime of the SO x trap catalyst, wherein the control logic of the electronic control unit is further configured so that when the SO x trap rate again falls after prolonging the lifetime of the SO x trap catalyst, the temperature of the SO x trap catalyst is raised under the lean air-fuel ratio of the exhaust gas to thereby restore the SO x trap rate by causing the trapped SO x to gradually diffuse to the inside of the SO x trap catalyst.