| 摘要 |
<P>PROBLEM TO BE SOLVED: To secure a high NOx elimination rate of NOx in an exhaust gas while suppressing the emission of SOx from an SOx trap catalyst. <P>SOLUTION: The SOx trap catalyst 12, an NOx storage catalyst 13, a urea water supply valve 18 and an NOx selective reduction catalyst 17 are arranged in an engine exhaust passage in that order from the upstream side. When an NOx emitting fuel for emitting NOx from the NOx storage catalyst 13 is supplied, the NOx emitting fuel is supplied according to a request when the quantity of SOx emitted from the SOx trap catalyst 12 is set below a predetermined value, and urea water is supplied when the quantity of SOx is set above the predetermined value then. <P>COPYRIGHT: (C)2009,JPO&INPIT |
