Patent ID: 7832201
Filing Date: 2010-11-16
Classification: B01D,F01N,F02D

Abstract:
1. Method for regenerating a nitrogen oxide storage catalyst in the exhaust-gas purification system of a vehicle having a lean-burn engine, the storage catalyst having an activity window for the nitrogen oxide storage between 150 and 500° C., comprising contacting exhaust gas from the lean-burn engine with the nitrogen oxide storage catalyst and regenerating the catalyst within the activity window by briefly switching the lean-burn mode to rich-burn mode, forming the rich-burn mode from two rich pulses comprising a first rich pulse and a second rich pulse, passing the first rich pulse followed by the second rich pulse in contact with the nitrogen oxide storage catalyst with a time interval between them, the first rich pulse always being shorter than the second rich pulse and the time interval between the two rich pulses being 2 to 20 seconds.