| 摘要 |
The present invention is directed to a catalyst system for the reduction of the harmful exhaust-gas constituents hydrocarbons (THC), carbon monoxide (CO), nitrogen oxides (NOx), and the environmentally detrimental secondary emissions ammonia (NH3) and nitrous oxide (N2O), of combustion engines operated using gasoline, and to a corresponding method for exhaust-gas purification. The system is characterized by a particular arrangement of catalysts, and is used in the case of engines which are operated with predominantly, on average, stoichiometric air/fuel mixtures. Here, a three-way catalyst produced in accordance with the current prior art is preferably installed in a close-coupled position. In the underfloor position there is situated an SCR catalyst produced in accordance with the current prior art, followed by a further three-way catalyst produced in accordance with the current prior art. The three-way catalyst in the underfloor region furthermore has a lower oxygen storage capacity than the close-coupled three-way catalyst. |
