| 摘要 |
The exhaust gas treatment unit, set in the exhaust line of an i.c. engine, consists of a housing containing a catalyst in the form of a support (18) through which the exhaust gases can pass, coated with a mixture of a first substance (20) which can oxidize nitrogen monoxide into nitrogen dioxide, and a second substance (22) which stores the nitrogen dioxide. The concentration of the first substance in the mixture reduced from the front of the support to the rear in order to enhance the nitrogen dioxide storage capacity, especially when the exhaust gas temperature is below 400 deg C. The support can be in the form of a single block of material or in two blocks, each with a front end and a rear end. The first substance in the coating contains a precious metal such as platinum, palladium or radium (sic), while the second is based on an alkali or alkaline earth. |
