Patent ID: 7174705

Claim:
An internal combustion engine comprising an arrangement for operating the internal combustion engine in a first operating mode, in a which a lean exhaust gas is generated by the internal combustion engine, a second operating mode, in which a reducing exhaust gas is generated by the internal combustion engine, and a third, desulfating operating mode, and an exhaust gas treatment system through which the exhaust gas of the internal combustion engine is conducted, the exhaust gas treatment system including a nitrogen oxide storage catalytic converter for removing, in the first operating mode, nitrogen oxides and sulfur oxides from the exhaust gas and storing it in the nitrogen oxide storage catalytic converter and, in the second operating mode with a reducing hot exhaust gas, releasing nitrogen oxide stored in the nitrogen oxide catalytic converter and reducing it and thereby also producing ammonia by the reduction of nitrogen oxides in, or released to, the exhaust gas from the nitrogen oxide storage catalytic converter and, in the third, desulfating operating mode, releasing sulfur oxides deposited in the nitrogen oxide storage catalytic converter as sulfur-containing compounds, and an SCR catalytic converter arranged downstream of the nitrogen oxide storage catalytic converter to receive the ammonia produced by the nitrogen storage catalytic converter in the second operating mode and also the sulfur-containing compounds released in the third, desulfating operating mode and being configured to convert the sulfur-containing compounds to SO 2 and to absorb the ammonia from the exhaust gas in the second operating mode, and the reduce nitrogen oxides in the exhaust gas with the ammonia stored in the SCR catalytic converter.