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OwnerNicola Soeger, Wolfgang Schneider +4inventors
InventorsNicola Soeger, Wolfgang Schneider, Yvonne Demel, Lothar Mussmann, Ralf Sesselmann, Thomas Kreuzer
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In exhaust gas purification units for decreasing nitrogen oxides in lean-burn exhaust gas of internal combustion engines by selective catalytic reduction by means of ammonia, introduction of excess ammonia leads to undesirable emissions of unused ammonia. These emissions can be decreased by means of ammonia barrier catalysts. In the ideal case, ammonia is oxidized to nitrogen and water by these catalysts. These require additional space in the exhaust gas purification unit which may have to be taken away from the space provided for the SCR main catalyst. In addition, the use of such ammonia barrier catalysts can result in overoxidation of the ammonia to nitrogen oxides. To overcome these disadvantages, a catalyst containing two superposed layers is proposed for the removal of nitrogen-containing pollutant gases from diesel exhaust gas. The lower layer contains an oxidation catalyst and the upper layer can store at least 20 milliliters of ammonia per gram of catalyst material. This catalyst displays reduced ammonia breakthrough at good SCR conversions in the low-temperature range. It can be used as SCR catalyst having reduced ammonia breakthrough or as ammonia barrier catalyst.
A catalyst for removing nitrogen-containing pollutant gases from the exhaust gas of diesel engines, which contains a honeycomb body and a coating composed of two superposed catalytically active layers,
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An exhaust gas purification unit for removing nitrogen-containing pollutant gases from the exhaust gas of diesel engines, which contains an SCR catalyst and an ammonia barrier catalyst, characterized in that the ammonia barrier catalyst contains a honeycomb body and a coating comprising two superposed catalytically active layers, wherein the lower layer applied directly to the honeycomb body contains an oxidation catalyst and
An exhaust gas purification unit for removing nitrogen-containing pollutant gases from the exhaust gas of diesel engines, which contains an SCR catalyst, wherein
Dependencies are inferred from the claim text.