| abstract |
(57) [Abstract] [Purpose] Even when the exhaust temperature of the engine is low, NOx contained in the exhaust gas is reduced with high efficiency, and HC and CO are also reduced. [Configuration] N provided in the exhaust pipe 12 of the engine 10 The Ox catalyst 18 and the hydrocarbon-based reducing agent 27 provided on the exhaust gas upstream side of the NOx catalyst 18 toward the NOx catalyst 18 And a reducing agent supply means 26 for supplying a reducing agent 27 to the injection nozzle 16. Further, a first oxidation catalyst 13 provided on the exhaust gas upstream side of the injection nozzle 16 and capable of oxidizing NO in the exhaust gas, and the NOx catalyst 1 8 is provided on the exhaust gas downstream side, and a second oxidation catalyst 21 capable of oxidizing HC and CO in the exhaust gas is provided. |