| 摘要 |
PROBLEM TO BE SOLVED: To optionally select an element such as copper, which cannot be conventionally used as metal active species, as the metal active species of a selective reduction type catalyst.SOLUTION: An exhaust emission cleaning device includes a selective reduction type catalyst 4 selectively reacting NOx with ammonia even under the coexistence of oxygen, in the terminal part of an exhaust tube 2 (an exhaust flow passage), and can add urea water as reductant on the upstream side with respect to the selective reduction type catalyst 4. On the downstream side with respect to the selective reduction type catalyst 4, a wall-through type filter 11 capable of catching a metal active species separated from the selective reduction type catalyst 4 is arranged. |
