Process for desulphating a nitrogen oxide storage catalyst

It is proposed a method for desulfating a nitrogen oxide storage catalyst which is arranged in the exhaust gas purification system of an internal combustion engine, particularly a diesel engine used in motor vehicles, together with a particulate filter. The desulfurization is carried out by heating the nitrogen oxide storage catalyst over a predetermined desulfation minimum temperature and subsequently carrying out a lean-rich change operation of the internal combustion engine. DOLLAR A According to the invention, the heating at least at times when the sulfur loading of the nitrogen oxide storage catalyst has exceeded a minimum value Smin and a regeneration of the particulate filter is started and it is then carried out a lean-rich change operation of the internal combustion engine when predetermined, determined by the engine operating , desulfation release conditions are met. DOLLAR A use in motor vehicles, especially passenger vehicles with diesel engines or direct injection gasoline engine.