| abstract |
An internal combustion engine in which a NOx selective reduction catalyst (15) is placed in an engine exhaust path, an oxidation catalyst (13) is placed upstream of the NOx selective reduction catalyst (15), and a NOx adsorption catalyst (12) is placed upstream of the oxidation catalyst (13). The NOx adsorption catalyst (12) exhibits, when its temperature rises, the properties of releasing NOx adsorbed to it and of capturing SOx contained in exhaust gas. The NOx adsorption catalyst (12) suppresses inflow of SOx into the oxidation catalyst (13) so that, in the oxidationcatalyst (13), oxidation of NO, released from the NOx adsorption catalyst (12), by NO2 is not prevented by the SOx. |