Hybrid catalyst for NOx reduction using fuel hydrocarbons as reductant

摘要

A method for reducing nitrogen oxides including NO and NO2 in an exhaust stream also comprising oxygen, carbon monoxide and hydrocarbons at a temperature above about 150°C, the method including in embodiments oxidizing NO in the exhaust stream to NO2; reforming raw diesel fuel to produce OHC's from the fuel; adding diesel fuel hydrocarbons and their oxygenates to the exhaust stream for the reduction of nitrogen oxides; and contacting the exhaust stream with a reduction hybrid catalyst comprising BaY-Ag/A1203 to reduce the nitrogen oxides to N2. The method reduces NOx initially through the (HC+OHC)/SCR process producing N2, while also producing NH3 as a byproduct over Ag/A12O3. The NH3 subsequently reduces NOx over the BaY-Ag/Al2O3 hybrid catalyst through the NH3/SCR process, producing more N2 and thereby enhancing the NOx reduction efficiency of the hybrid catalyst system.