Method of removing nitrogen oxides from the exhaust gas of a lean-burn internal combustion engine and exhaust-gas purification system therefor
The present invention relates to a method of removing nitrogen oxides from the exhaust gas of a lean-burn internal combustion engine by selective catalytic reduction (SCR) using ammonia. The exhaust gas is routed first over a platinum-containing pre-catalyst and then over an SCR catalyst. The ammoni...
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Main Authors | , , , , , , , |
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Format | Patent |
Language | English |
Published |
01.01.2008
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Subjects | |
Online Access | Get full text |
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Summary: | The present invention relates to a method of removing nitrogen oxides from the exhaust gas of a lean-burn internal combustion engine by selective catalytic reduction (SCR) using ammonia. The exhaust gas is routed first over a platinum-containing pre-catalyst and then over an SCR catalyst. The ammonia needed for the selective catalytic reduction is added to the exhaust gas upstream of the pre-catalyst at an exhaust-gas temperature below 250° C., while it is supplied to the exhaust gas between the pre-catalyst and the SCR catalyst at an exhaust gas temperature above 150° C. By adopting this procedure, a very large temperature range for the selective catalytic reduction with high nitrogen conversion rates is obtained. |
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Bibliography: | Application Number: US20040547249 |