| 摘要 |
<P>PROBLEM TO BE SOLVED: To hold high NOx occluding capability of an NOx occlusion catalyst. <P>SOLUTION: An SOx trap catalyst 11 capable of trapping SOx contained in an exhaust gas is arranged within an engine exhaust path at an upstream side of the NOx occlusion catalyst 12. When an SOx trap rate by the SOx trap catalyst 11 decreases, the SOx trap catalyst 11 is made to rise in temperature with an air-fuel ratio of the exhaust gas flowing into the SOx trap catalyst 11 kept lean. At this time, SOx trapped diffuses into an inside the SOx trap catalyst 11, so that the SOx trap rate recovers. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
