| abstract |
Catalytic activity or NOx reduction is suitably performed at low temperatures. The system comprises a post-treatment device (13), which is provided in the exhaust passage (12) of an engine (11) and contains catalysts (14, 15, 16), which are activated by HC in the exhaust gas, a fuel supply means (23) that supplies a fuel containing a high-boiling point HC and a low-boiling point HC to the exhaust passage (12) on the upstream side of the post-treatment device (13) when the temperature of the exhaust gas supplied to the post-treatment device (13) is lower than a prescribed temperature, and an HC trap catalyst (17) that is provided in the exhaust passage (12) between the post-treatment device (13) and the fuel supply means (23) and that adsorbs the high-boiling point HC but allows the passage of the low-boiling point HC in the HC included in the fuel supplied from the fuel supply means (23) into the exhaust passage (12). |