Abstract: An arrangement and method for reducing the nitrogen oxide content in the exhaust gas of an internal combustion engine with the aid of ammonia and/or ammonia-releasing reduction agents, whereby ammonia and/or ammonia-containing reduction agent is added to the exhaust gas stream upstream of a catalyst combination composed of an SCR catalyst and a subsequent NH3-oxidation catalyst in such a way that a homogeneous mixture of exhaust gas and ammonia is present upstream of the SCR catalyst. To optimize the reaction or conversion of nitrogen oxides, disposed downstream of the combination of a first SCR catalyst and a first NH3-oxidation catalyst is at least one second catalyst having SCR activity in order in this way to reduce the nitrogen oxides formed at the first NH3-oxidation catalyst due to insufficient selectivity of the catalyst to nitrogen with not yet oxidized NH3.

Abstract: A method for application in conjunction with an exhaust gas post-treatment system for metering an ammonia-releasing reducing agent into the exhaust gas stream of an internal combustion engine installed in a motor vehicle and operated with excess air. A control unit meters the quantity of reducing agent as a function of a stored model and during the operation of the internal combustion engine varies the metered quantity during certain operating phases and compares the change in the measured value of at least one NOx sensor installed downstream of the SCR catalyst with an expected value.

Abstract: A method for use in conjunction with an exhaust gas post-treatment system for metering an ammonia-releasing reducing agent into the exhaust gas stream of an internal combustion engine installed in a motor vehicle and operating with excess air. A control unit meters the quantity of reducing agent as a function of a stored model and, during the operation of the internal combustion engine, determines, by comparison of a value proportional to the nominal emission or the nominal conversion stored in the control unit of the internal combustion engine for the associated operating point of the internal combustion engine and/or of the exhaust gas post-treatment system with a value proportional to the actual emission or the actual conversion metrologically determined by the control unit.

Abstract: An arrangement and method for reducing the nitrogen oxide content in the exhaust gas of an internal combustion engine with the aid of ammonia and/or ammonia-releasing reduction agents, whereby ammonia and/or ammonia-containing reduction agent is added to the exhaust gas stream upstream of a catalyst combination composed of an SCR catalyst and a subsequent NH3-oxidation catalyst in such a way that a homogeneous mixture of exhaust gas and ammonia is present upstream of the SCR catalyst. To optimize the reaction or conversion of nitrogen oxides, disposed downstream of the combination of a first SCR catalyst and a first NH3-oxidation catalyst is at least one second catalyst having SCR activity in order in this way to reduce the nitrogen oxides formed at the first NH3-oxidation catalyst due to insufficient selectivity of the catalyst to nitrogen with not yet oxidized NH3.

Abstract: A method for use in conjunction with an exhaust gas post-treatment system for metering an ammonia-releasing reducing agent into the exhaust gas stream of an internal combustion engine installed in a motor vehicle and operating with excess air. A control unit meters the quantity of reducing agent as a function of a stored model and, during the operation of the internal combustion engine, determines, by comparison of a value proportional to the nominal emission or the nominal conversion stored in the control unit of the internal combustion engine for the associated operating point of the internal combustion engine and/or of the exhaust gas post-treatment system with a value proportional to the actual emission or the actual conversion metrologically determined by the control unit.

Abstract: A method for application in conjunction with an exhaust gas post-treatment system for metering an ammonia-releasing reducing agent into the exhaust gas stream of an internal combustion engine installed in a motor vehicle and operated with excess air. A control unit meters the quantity of reducing agent as a function of a stored model and during the operation of the internal combustion engine varies the metered quantity during certain operating phases and compares the change in the measured value of at least one NOx sensor installed downstream of the SCR catalyst with an expected value.

Abstract: An arrangement and method for reducing the nitrogen oxide content in the exhaust gas of an internal combustion engine with the aid of ammonia and/or ammonia-releasing reduction agents, whereby ammonia and/or ammonia-containing reduction agent is added to the exhaust gas stream upstream of a catalyst combination composed of an SCR catalyst and a subsequent NH3-oxidation catalyst in such a way that a homogeneous mixture of exhaust gas and ammonia is present upstream of the SCR catalyst. To optimize the reaction or conversion of nitrogen oxides, disposed downstream of the combination of a first SCR catalyst and a first NH3-oxidation catalyst is at least one second catalyst having SCR activity in order in this way to reduce the nitrogen oxides formed at the first NH3-oxidation catalyst due to insufficient selectivity of the catalyst to nitrogen with not yet oxidized NH3.