| 摘要 |
A method for reducing nitrogen oxides comprising NO and NO2 in an exhaust gas stream also comprising oxygen, carbon monoxide and hydrocarbons at a temperature of at least about 150 deg.C is provided to reduce NOx initially through the (HC+OHC)/SCR process of producing N2 and also producing NH3 as a byproduct on Ag/Al2O3, wherein the NH3 subsequently reduces NOx on the BaY-Ag/Al2O3 hybrid catalyst through the NH3/SCR process, produces more N2 and enhances the NOx reduction efficiency of the hybrid catalyst system accordingly. A method for reducing nitrogen oxides comprising NO and NO2 in an exhaust gas stream also comprising oxygen, carbon monoxide and hydrocarbons at a temperature of at least 150 deg.C comprises the steps of: oxidizing NO in the exhaust gas stream into NO2; adding diesel fuel hydrocarbons and oxygenates thereof to the exhaust gas stream for the reduction of nitrogen oxides; and contacting the exhaust gas stream with a hybrid reduction catalyst comprising an alkali metal or an alkaline earth metal, a zeolite, a transition metal, and a metal oxide to reduce the nitrogen oxides into N2. A method for reducing nitrogen oxides comprising NO andNO2 in an exhaust gas stream also comprising oxygen, carbon monoxide and hydrocarbons at a temperature of at least 150 deg.C comprises the steps of: oxidizing NO in the exhaust gas stream into NO2; adding diesel fuel hydrocarbons and oxygenates thereof to the exhaust gas stream for the reduction of nitrogen oxides; and contacting the exhaust gas stream with a hybrid reduction catalyst comprising BaY-Ag/Al2O3 to reduce the nitrogen oxides into N2. A method for preparing a hybrid NOx reduction catalyst comprises the steps of: mixing BaY with Ag/Al2O3 to form a homogeneous physical mixture; compressing the homogeneous physical mixture to form a wafer; and annealing the wafer to form a hybrid catalyst comprising BaY-Ag/Al2O3.
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