Patent ID: 7670577

Claim:
Method for operating a nitrogen oxide storage catalytic converter in the exhaust-gas purification system of a diesel engine with alternating storage and regeneration phases, with the catalytic converter storing the nitrogen oxides contained in the exhaust gas during operation of the engine with a lean air/fuel mixture, and with the catalytic converter being regenerated by operating the engine with a rich air/fuel mixture when the nitrogen oxide concentration downstream of the catalytic converter rises above a limit value, characterized in that, during operating phases at exhaust-gas temperatures of between 120° C. and 250° C., the storage catalytic converter is regenerated in the usual way periodically by enriching the exhaust gas while the exhaust gas temperature remains the same, and in that, from time to time, directly after a regeneration of said type, in a second regeneration step, the exhaust-gas temperature is additionally raised, for complete regeneration of the storage catalytic converter, into a range of between 300° C. and 400° C., and therefore also the firmly bonded nitrates are desorbed and converted.