| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a sufficient NOx conversion rate by warming up a NOx selective reduction catalyst in an early stage and also neutralizing the HC poisoning of the NOx selective reduction catalyst. <P>SOLUTION: A NOx selective reduction catalyst 15 is disposed in an engine exhaust passage, and an oxidation catalyst 12 is disposed in the engine exhaust passage upstream of the NOx selective reduction catalyst 15. HC is supplied to the oxidation catalyst 12 from an HC supply valve 28 when an engine is started to raise the temperature of the NOx selective reduction catalyst 15 by the oxidative reaction heat of the HC. At this time, the temperature of the NOx selective reduction catalyst 15 is raised to a range of HC desorption temperature where the HC is desorbed from the NOx selective reduction catalyst 15. <P>COPYRIGHT: (C)2009,JPO&INPIT |
