| 摘要 |
PROBLEM TO BE SOLVED: To provide an exhaust emission control device enhancing capacity of reducing a nitrogen oxide.SOLUTION: An exhaust emission control device includes: a reduction catalyst 22B that is arranged in an exhaust passage, and reduces a nitrogen oxide contained in exhaust; an ammonia generation catalyst 22A that is arranged on the upstream side in an exhaust flow direction with respect to the reduction catalyst 22B, and supplies ammonia to exhaust; and a downstream addition valve 24 that is arranged on the upstream side in the exhaust flow direction with respect to the reduction catalyst 22B, and supplies hydrocarbon to exhaust. The reduction catalyst 22B has an ammonia reduction layer that promotes reduction reaction of a nitrogen oxide using ammonia, and a hydrocarbon reduction layer that promotes reduction reaction of a nitrogen oxide using hydrocarbon. |
