| 摘要 |
Nitrogen oxide storage catalysts are used for eliminating nitrogen oxides from the exhaust gas of primarily lean-operating internal combustion engines. The increased sulfur concentration in the fuel poisons the catalyst during service when said catalysts are used in diesel vehicles. The poisoned state is reversible in reduced exhaust gas conditions at elevated temperatures. In conventional nitrogen oxide storage catalysts, temperatures exceeding 600‹C have to be generated for the desulfurization process, which is not always possible in diesel vehicles that have a nitrogen oxide storage catalyst in the underbody region. The invention relates to a method which makes it possible to lower the desulfurization temperature of conventional nitrogen oxide catalysts containing a platinum component and at least one nitrogen oxide storage material. In said method, the basicity of the chemical environment of the platinum is reduced while the nitrogen oxide storage material can remain unchanged. Also disclosed is an improved nitrogen oxide storage catalyst which features a reduced desulfurization temperature and is used for carrying out said method. Such catalysts are particularly suitable for aftertreating the nitrogen oxides in the exhaust gases of diesel engines. ® KIPO & WIPO 2009 |
