Patent ID: 6938411
Filing Date: 2005-09-06
Classification: B01D,F01N,F02D,Y02A,Y02T

Abstract:
1. 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, comprising in a first cycle, passing the exhaust gas stream over a nitrogen oxide storage catalyst and a particulate filter arranged in succession, 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, and periodically denitrating the storage catalyst by enriching the exhaust gas and in a second cycle at first regenerating the particulate filter by increasing the temperature of the lean exhaust gas to a value at which the particulate combustion on the particulate filter is ignited and thereafter desulfurizing the nitrogen oxide storage catalysts by enriching the exhaust gas; wherein the temperature of the lean exhaust gas is increased by burning hydrocarbons on the nitrogen oxide storage catalyst.