| 摘要 |
The filter (1) has upstream and downstream channels (11a, 11b) defined by porous walls (12) that are impregnated with two catalytic coatings (14, 15) for oxidizing unburnt products and for reducing nitrogen oxides, respectively. One of the coatings comprises materials that absorb nitrogen oxides at low temperature and to desorb nitrogen oxides at high temperature, where the nitrogen oxides emitted at low temperature during starting of a diesel engine are trapped by the materials and are released and reduced by selective reduction catalysts when desorption temperature is attained. The materials contain compounds such as alumina, titanium dioxide, zirconium dioxide, yttrium oxide, cerium (IV) oxide, silicon dioxide, zeolites, alkaline metals, transition metals, lanthanides, actinides, perovskites and alkaline-earth metal. |
