Patent ID: 8104271

Claim:
An exhaust purification device of an internal combustion engine arranging an SO X trap catalyst able to trap SO X contained in exhaust gas inside an engine exhaust passage, wherein the SO X trap catalyst carries at least one of an alkali metal and alkali earth metal diffused inside it, a temperature of the SO X trap catalyst is held at a temperature where a nitrate of the at least one of alkali metal and alkali earth metal becomes a melted state during engine operation, whereby a nitrate movement and coagulation action where the nitrate in the SO X trap catalyst moves to and coagulates at the SO X trap catalyst surface is promoted, and the nitrate movement and coagulation action is used to restore a SO X trap rate and remove the SO X , the SO X trap catalyst has a property of trapping SO X contained in exhaust gas when an air-fuel ratio of the exhaust gas flowing into the SO X trap cat alyst is lean and causing the trapped SO X to gradually diffuse inside the SO X trap when making the temperature of the SO X trap catalyst rise to a SO X diffusion promotion temperature under a lean air-fuel ratio of the exhaust gas, and when the SO X trap rate is no longer restored to the target value even when the restoration action of the SO X trap rate due to the nitrate movement and coagulation action is performed, to restore the SO X trap rate, the temperature of the SO X trap catalyst is made to rise to the SO X diffusion promotion temperature under a lean air-fuel ratio of the exhaust gas.