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AssigneeSiemens Aktiengesellschaft
InventorsChristian Dahlheim, Maximilian Fleischer, Hans Meixner
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The method reduces the nitrogen oxide concentration in the exhaust of an internal combustion engine. A noticeable reduction in the NO.sub.x emission of a diesel motor can be achieved by applying the Selective Catalytic Reduction (SCR) method. In this method, ammonia is injected into a catalyzer through which the exhaust gas flows, this ammonia reacting with nitrogen monoxide or, respectively, nitrogen dioxide to form nitrogen and water. Since the exhaust gas should contain neither nitrogen monoxide nor excess ammonia, suitable methods are required for regulating the metering of NH.sub.3. For controlling the amount of urea added to the exhaust gas as a reduction agent, the NO and NH.sub.3 concentration is measured using a detector located in the exhaust systems following the SCR catalyzer. The detector contains a vanadate layer manufactured on the basis of a specific sputtering method as a sensitive element. The electrical resistance thereof is highest when the conversion of nitrogen monoxide to form nitrogen and water occurs stoichiometrically.
A method for reducing nitrogen oxide concentration in exhaust gas in an exhaust system of an internal combustion engine or of a firing system, a reduction agent that contains ammonia being added to the exhaust gas and nitrogen oxides being converted into nitrogen and water in a catalyzer unit in the exhaust system through which the exhaust gas flows, comprising the steps of:
A method for reducing nitrogen oxide concentration in exhaust gas in an exhaust system of an internal combustion engine or of a firing system, the exhaust system having a catalyzer unit through which the exhaust gas flows, comprising the steps of:
A method for reducing nitrogen oxide concentration in exhaust gas in an exhaust system of an internal combustion engine or of a firing system, the exhaust system having a catalyzer unit through which the exhaust gas flows, comprising the steps of:
Dependencies are inferred from the claim text.