| 摘要 |
PROBLEM TO BE SOLVED: To provide a practical exhaust emission control device which can maintain high NOx reduction effect without lowering performance even during driving for a long time. SOLUTION: This exhaust emission control device is so constituted that a NOx occlusion and reduction catalyst 12 is provided in the middle of an exhaust pipe 10 for passing an exhaust gas 8 whose NOx is oxidized and temporarily occluded in the state of nitrate when oxygen concentration in the exhaust gas 8 is high and is decomposed and emitted to reduce and purify with a reducer 11 interposed when the oxygen concentration in the exhaust gas 8 is low, an NO2 generation catalyst 14 is provided at a front stage of the NOx occlusion and reduction catalyst 12 with improved function for generating NO2 by selectively reacting NO and oxygen in the exhaust gas 8, and the reducer 11 can be added on the upstream of the NO2 generation catalyst 14 in the appropriate manner. |
