Abstract: The invention proposes a particulate filter having a catalytic coating which contains two catalysts arranged one behind the other. The first catalyst is located in the gas inlet region of the filter and contains a palladium/platinum catalyst. The second catalyst is arranged downstream of the first catalyst and preferably contains platinum alone as catalytically active component. The combination of these two catalysts provides the coated filter with a good ageing stability and resistance to sulphur poisoning.

Abstract: The invention relates to a catalyst arrangement for purifying the exhaust gases of internal combustion engines operated under lean conditions. It is proposed that a thinwalled, porous carrier be coated on one side with a nitrogen oxide storage catalyst and on the other side with an SCR catalyst. When the exhaust gas is passed through the catalytic coatings and the support material, a significant improvement in the nitrogen oxide conversion is achieved compared to a series arrangement of the catalysts on separate carriers. Wall flow filters have been found to be useful as thin-walled carriers.

Abstract: The invention proposes a particulate filter having a catalytic coating which contains two catalysts arranged one behind the other. The first catalyst is located in the gas inlet region of the filter and contains a palladium/platinum catalyst. The second catalyst is arranged downstream of the first catalyst and preferably contains platinum alone as catalytically active component. The combination of these two catalysts provides the coated filter with a good ageing stability and resistance to sulphur poisoning.

Abstract: The present invention relates to a method of removing nitrogen oxides from the exhaust gas of a lean-burn internal combustion engine by selective catalytic reduction (SCR) using ammonia. The exhaust gas is routed first over a platinum-containing pre-catalyst and then over an SCR catalyst. The ammonia needed for the selective catalytic reduction is added to the exhaust gas upstream of the pre-catalyst at an exhaust-gas temperature below 250° C., while it is supplied to the exhaust gas between the pre-catalyst and the SCR catalyst at an exhaust gas temperature above 150° C. By adopting this procedure, a very large temperature range for the selective catalytic reduction with high nitrogen conversion rates is obtained.

Abstract: The invention relates to a catalyst arrangement for purifying the exhaust gases of internal combustion engines operated under lean conditions. It is proposed that a thinwalled, porous carrier be coated on one side with a nitrogen oxide storage catalyst and on the other side with an SCR catalyst. When the exhaust gas is passed through the catalytic coatings and the support material, a significant improvement in the nitrogen oxide conversion is achieved compared to a series arrangement of the catalysts on separate carriers. Wall flow filters have been found to be useful as thin-walled carriers.

Abstract: The present invention relates to a method of removing nitrogen oxides from the exhaust gas of a lean-burn internal combustion engine by selective catalytic reduction (SCR) using ammonia. The exhaust gas is routed first over a platinum-containing pre-catalyst and then over an SCR catalyst. The ammonia needed for the selective catalytic reduction is added to the exhaust gas upstream of the pre-catalyst at an exhaust-gas temperature below 250° C., while it is supplied to the exhaust gas between the pre-catalyst and the SCR catalyst at an exhaust gas temperature above 150° C. By adopting this procedure, a very large temperature range for the selective catalytic reduction with high nitrogen conversion rates is obtained.