Method and a catalyzer unit for reducing pollutants such as oxides of nitrogen in exhaust gases of internal combustion engines
AssigneeDaimler-Benz Aktiengesellschaft
InventorMartin Hartweg
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Abstract
A method for catalytically reducing pollutants, in particular oxides of nitrogen in oxygen-containing exhaust gases of internal combustion engines, uses a catalyzer unit arranged in the exhaust gas flow of the engine. The catalyzer unit has a catalytic layer, an ion conducting layer and a counterelectrode. The catalytic layer exhibits a non-Faraday modification of the catalytic activity.
Claims20
A method for catalytically reducing pollutants, the method comprising the steps of:
- arranging a catalyzer unit exhibiting a non-Faraday electrochemical modification of a catalytic activity in an exhaust gas flow of an internal combustion engine, said catalyzer unit having a catalytic layer, an ion conducting layer chemically stable in the exhaust gas flow, and a counterelectrode;
- controlling the catalytic activity of the catalyzer unit using a voltage applied to the catalyzer unit as a function of at least one of a composition and temperature of the exhaust gas.
A catalyzer unit for catalytically reducing pollutants, arranged in an exhaust gas line of an internal combustion engine and having a substance catalytically effective relative to oxides of nitrogen, comprising:
- a catalytic layer;
- an ion conducting layer connected to said catalytic layer for conducting ions, said ion conducting layer being chemically stable relative to an exhaust gas;
- a counterelectrode connected to said ion conducting layer so as to be electrically conducting;
- a controllable voltage source;
- wherein said catalytic layer has an electrically conducting connection to one pole of said controllable voltage source and said counterelectrode has an electrically conducting connection to another pole of said controllable voltage source;
- wherein said catalytic layer is isolated from said counterelectrode with respect to electrical conduction through said ion conducting layer;
- and
- wherein a reaction rate of hydrocarbons on said catalytic layer with oxides of nitrogen being high at high voltages and being lower at one of lower and reversed polarity voltages.
Dependencies are inferred from the claim text.