| 摘要 |
An oxidation catalyst for treating an exhaust gas from a compression ignition engine is disclosed. The catalyst consists of a substrate, a first washcoat region with palladium (Pd) and a first support material containing cerium oxide, and a second washcoat region comprising platinum (Pt) and a second support material. The second washcoat region may also contain palladium, where the mass of Pt may be greater than the mass of Pd. The second support material may comprise a refractory metal oxide such as alumina, silica, titania, zirconia, ceria or mixed or composite oxides. The second washcoat region may be disposed on the substrate, downstream of the first washcoat region. Alternatively the first washcoat later may be disposed or supported on the second washcoat layer. The first washcoat region palladium content may be less than 2% by weight, and preferably between 0.25 and 1.9 %. In the second washcoat region the platinum may br between 0.2 to 15 % by weight. Further aspects include an exhaust system, a vehicle comprising a compression ignition engine, a method of modulating the content of NOx and use of the oxidation catalysts. |
