Patent ID: 8099952

Claim:
An exhaust purification device of an internal combustion engine, the device comprising: an NO x selective reducing catalyst disposed in an engine exhaust passage, the NO x selective reducing catalyst using an ammonia generated from urea fed to the NO x selective reducing catalyst to selectively reduce NO x contained in an exhaust gas; an oxidation catalyst disposed in the engine exhaust passage upstream of the NO x selective reducing catalyst; an NO x adsorption catalyst disposed in the engine exhaust passage upstream of the oxidation catalyst, the NO x adsorption catalyst having a property of adsorbing the NO x contained in the exhaust gas when a temperature of the NO x adsorption catalyst is below a predetermined temperature and releasing an adsorbed NO x when the temperature of the NO x adsorption catalyst is above the predetermined temperature and having a property of trapping SO x contained in the exhaust gas, such that an inflow of the SO x to the oxidation catalyst is suppressed by the NO x adsorption catalyst to thereby prevent the SO x from obstructing NO released from the NO x adsorption catalyst from being oxidized to NO 2 at the oxidation catalyst; an NO x purification rate by the NO x selective reducing catalyst decreasing at a predetermined specific NO x selective reducing catalyst temperature region when the SO x flows into the oxidation catalyst; and an electronic control unit that causes SO x poisoning recovery processing to be performed on the NO x adsorption catalyst and the oxidation catalyst when the NO x purification rate at the specific NO x selective reducing catalyst temperature region has fallen below a predetermined level.