| 摘要 |
A catalyst and a method for selectively reducing nitrogen oxides with ammonia at low temperatures are provided. The catalyst includes a first component of copper, chromium, cobalt, nickel, manganese, iron, niobium, or mixtures thereof, a second component of cerium, a lanthanide, a mixture of lanthanides, or mixtures thereof, and a zeolite. The catalyst may also include strontium as an additional second component. The catalyst has high hydrothermal stability. The catalysts have high activity for conversion of nitrogen oxides in exhaust streams, and are not significantly influenced by the NO/N02 ratio. The catalyst and the method may have special application to selective reduction of nitrogen oxides in exhaust gas from diesel vehicles, as the temperature of exhaust gas &om diesel vehicles is low, and the exhaust gas generally has a high NO/NO2 ratio.
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