| abstract |
According to the method of the present invention, NO (nitrogen monoxide) in the exhaust gas of a diesel engine is first oxidized to NO 2 (nitrogen dioxide) by an oxidizing catalyst (5). Further, carbon particles in the exhaust gas are trapped by a DPF (7) (diesel particulate filter). The exhaust gas containing NO 2 formed by oxidation of nitrogen monoxide is, then, fed to the DPF (7), and NO 2 in the exhaust gas reacts with the carbon particles trapped in the DPF (7). When the NO 2 reacts with carbon particles, carbon particles are oxidized (burned) by NO 2 and removed from DPF (7), and, at the same time, NO 2 is reduced to NO by the carbon particles. The exhaust gas containing NO formed by the reaction between the carbon particles and NO 2 is fed to an NO X absorbent (9). In the NO X absorbent (9), NO is absorbed by the NO X absorbent (9) and, thereby, removed from the exhaust gas. Therefore, according this method, the carbon particles collected by the DPF (7) can be easily burned by NO 2 , thereby being removed from the DPF (7) without increasing the amount of NO released to the atmosphere. |