| abstract |
(57) [PROBLEMS] To recover the purifying ability of a NOx storage reduction catalyst within a short time in an exhaust purification device provided with a three-way catalyst and a NOx storage reduction catalyst disposed downstream of the three-way catalyst. SOLUTION: Ni as a catalyst species is supported on an alumina supporting layer of a NOx storage reduction catalyst. When the engine is operated in the rich air-fuel ratio range and a reducing atmosphere is formed around the NOx catalyst, a reaction of converting NiO to NiS occurs, and H2S is consumed. As a result, the consumption of SO2 proceeds, and the oxidation of the oxidizing atmosphere takes place. To convert BaSO4, which is an oxidation product of sulfur attached to the NOx catalyst, to BaCO3, which is a NOx storage agent. Is promoted, and the purification capability of the NOx catalyst is restored. |