| 摘要 |
<P>PROBLEM TO BE SOLVED: To improve recovery properties from sulfur poisoning and prevent deterioration and damage of a filter catalyst. <P>SOLUTION: An exhaust emission control device having an NOx storage reduction catalyst 2 and the filter catalyst 3 in series is used. Exhaust gas is made flow from the NOx storage reduction catalyst 2 to the filter catalyst 3 at a time of normal operation and a direction of exhaust gas flow is reversed to a direction from the filter catalyst 3 to the NOx storage regeneration catalyst at a time of recovery process in which exhaust gas to which reducer is added is made flow. Since exhaust gas is heated by reaction heat in the filter catalyst 3, the NOx storage reduction catalyst 2 can be recovered from sulfur poisoning by low temperature exhaust gas, over heat of the filter catalyst 3 can be prevented. <P>COPYRIGHT: (C)2007,JPO&INPIT |
