摘要 |
An exhaust system includes a first SCR catalyst and a second SCR catalyst positioned downstream of the first SCR catalyst. A first injector is provided upstream of the first SCR catalyst, and a second injector is provided upstream of the second SCR catalyst. The exhaust system further includes a gaseous ammonia supply device fluidly connected to the first injector for supplying gaseous ammonia to the exhaust gas by the first injector, and an ammonia-containing reductant reservoir fluidly connected to the second injector for supplying a fluid ammonia-containing reductant, such as urea, to the exhaust gas by the second injector. The first SCR catalyst has a smaller volume than the second SCR catalyst for a fast warm-up of the first SCR catalyst. |