Umicore Ag & Co Kg

Michael Hoffmann

Thomas Kreuzer

Harald Klein

Adolf Schäfer-Sindlinger

Klaus-Ingo Prieger

The invention relates to a method for desulfating a nitrogen oxide storage catalyst that contains stored nitrogen oxides and sulfur oxides and that forms part of an exhaust gas purification system of a lean-burn engine. The method provides that, to initiate desulfation, the temperature of the catalyst is increased to the point where thermal desorption of the nitrogen oxides stored in the catalyst sets in, and the onset of thermal desorption of the nitrogen oxides is used as the signal to enrich the air/fuel mixture to perform the desulfation.

Method for desulfating a nitrogen oxide storage catalyst

A method for removing nitrogen oxides and particulate matter from the lean exhaust gas of a combustion engine that also contains low concentrations of sulfur oxides. The exhaust gas stream is passed over a nitrogen oxide storage catalyst and a particulate filter, where nitrogen oxides and sulfur oxides are adsorbed by the storage catalyst under lean exhaust gas conditions and the particulate matter is deposited on the particulate filter. The storage catalyst is in a first cycle is periodically denitrated by enriching the exhaust gas regeneration of the particulate filter. Desulfurization of the nitrogen oxide storage catalyst is carried out in a second cycle by raising the temperature of the lean exhaust gas to a value at which the particulate matter combustion on the particulate filter is initiated and then the storage catalyst can be desulfurized by enriching the exhaust gas.

Growing community of inventors

Aschaffenburg, Germany

Michael Hoffmann