| 摘要 |
<P>PROBLEM TO BE SOLVED: To prevent the occurrence of S poisoning of an NOx occlusion reduction catalyst. <P>SOLUTION: A catalyst converter 7 is situated in an exhaust passage 5 of an internal combustion engine. The catalyst converter 7 is formed that an SOx trap 73 to occlude SOx in an exhaust gas when an exhaust gas air-fuel ratio is lean and discharge occluded SOx when the exhaust gas air-fuel ratio is turned into a rich air-fuel ratio; a hydrogen producing catalyst 75 to produce hydrogen from HC, CO etc. in exhaust gas when the exhaust gas air-fuel ratio is turned into a rich air-fuel ratio; and an NOx occlusion reduction catalyst 77 to occlude NOx in exhaust gas when an exhaust gas air-fuel ratio is lean and effect occluding purification of the occluded NOx when an exhaust gas air-fuel ratio is turned into a rich air-fuel ratio are situated in the order named from the upper stream side. By situating a hydrogen producing catalyst between a SOx trap and NOx occluding reducing catalyst, SOx discharged from the SOx trap is prevented from occlusion into the NOx occlusion reduction catalyst, and desorption of SOx from the NOx occlusion reduction catalyst is promoted. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
