| 摘要 |
PROBLEM TO BE SOLVED: To stabilize refining of reduction agent by forming a member of a refining device in contact with the gas with a member having a large heat capacity and another member having a small heat capacity so as to guide in the reduction agent to different portion according to operating conditions. SOLUTION: In the upstream of a NOx catalyst 3, a refining catalyst 4 is disposed, which consists of a first gas passage body 5 made of metal having a small heat capacity and a second gas passage body 6 made of ceramic having a large heat capacity with the first gas passage body at the center. Moreover, in the upstream of the refining catalyst, a first nozzle 7 and second nozzle are disposed. The first nozzle 7 is enabled to blow fuel toward the first gas passage body, while the second nozzle 8 is enabled to blow fuel toward the second gas passage body. Fuel is guided in either one or both of the first nozzle and the second nozzle with a switch valve 14 according to operating conditions. |
