[Selective reduction of NOx with propene over SnO2/Al2O3 catalyst]

In the study, a series of SnO2/Al2O3 catalysts with various Sn loading were prepared by three different methods (impregnation, co-precipitation and single step sol-gel) and their catalytic activities for the selective reduction of NOx with propene were investigated. It was found that the catalyst preparation method as well as the Sn loading exerted a significant influence on the catalyst activity. Catalysts prepared by sol-gel method exhibited the highest activity toward NOx reduction and the optimal Sn loading is 5%. 5% SnO2/Al2O3 catalyst prepared by sol-gel method was found to be less inhibited by the presence of H20 than those prepared by other methods. Even in the co-presence of H2O and SO2, it still showed the highest activity. The increase of oxygen and propene concentration promotes the NOx reduction, respectively.