Patent ID: 8051647

Claim:
An exhaust purification device of an internal combustion engine comprising: a main SO x trap catalyst arranged in an engine exhaust passage, for trapping SO x contained in an exhaust gas, dividing the exhaust passage downstream of the main SO x trap catalyst into a main exhaust passage and a bypass passage bypassing the main exhaust passage; an NO x storage catalyst arranged in the main exhaust passage for storing NO x contained in the exhaust gas when an air-fuel ratio of an inflowing exhaust gas is lean and releasing stored NO x when the air-fuel ratio of the inflowing exhaust gas becomes a stoichiometric air-fuel ratio or rich; and an auxiliary SO x trap catalyst arranged in the main exhaust passage upstream of the NO x storage catalyst, the exhaust gas is made to flow through the main exhaust passage, and the exhaust gas is made to flow through the bypass passage when the main SO x trap catalyst is regenerated, wherein the main SO x trap catalyst has a property that when the main SO x trap catalyst rises in temperature under a lean air-fuel ratio of the exhaust gas, the trapped SO x gradually diffuses inside the main NO x trap catalyst and has a property that when the air-fuel ratio of the exhaust gas flowing into the main SO x trap catalyst becomes rich, if the temperature of the main SO x trap catalyst is higher an SO x release temperature, the trapped SO x is released, and when the SO x trap rate by the main SO x trap catalyst falls below a predetermined rate, a regeneration action of the main SO x trap catalyst is performed.