Patent ID: 8701393

Claim:
An exhaust purification system of an internal combustion engine comprising: an SO x trap catalyst for trapping SO x contained in exhaust gas arranged in an engine exhaust passage, wherein: said SO x trap catalyst contains SO 2 adsorption-use oxides which adsorb SO 2 contained in exhaust gas and an SO x storage material which stores SO x in the form of sulfates, said SO x trap catalyst has a property of being able to adsorb SO 2 contained in exhaust gas at the SO 2 adsorption-use oxides without oxidizing and has a property whereby SO 2 adsorbed at the SO 2 adsorption-use oxides is oxidized and is stored in the form of sulfates in the SO x storage material when a temperature of the SO x trap catalyst becomes higher than a start temperature of adsorbed SO 2 movement where the SO 2 adsorbed at the SO 2 adsorption-use oxides starts to move toward the SO x storage material, and, during engine operation, the temperature of the SO x trap catalyst is made to repeatedly change from less than said start temperature of adsorbed SO 2 movement to more than said start temperature of adsorbed SO 2 movement, said SO 2 adsorption-use oxides are comprised of metal oxides, and said metal oxides are comprised of an oxygen adsorbing and releasing material which changes in oxidation state in the exhaust gas.