Novel Ag-Pd/Al2O3-SiO2 for lean NOx reduction by C3H6 with high tolerance of SO2

Activity test and in situ DRIFTS experiments were carried out on the selective catalytic reduction of NOx by propene over Ag (5 wt%)-Pd (0.01 wt%)/Al2O3 and Ag (5 wt%)-Pd (0.01 wt%)/Al2O3-SiO2. The activity test results showed that the Ag-Pd/Al2O3-SiO2 had a higher NOx conversion than Ag-Pd/Al2O3 in the presence of SO2. The in situ DRIFTS results showed the SO2 poisoned Ag-Pd (0.01 wt%)/Al2O3 surface inhibited the formation of enolic species and NO3-, which are reactive intermediates to form -NCO species. However, the SO2 poisoned Ag-Pd (0.01 wt%)/Al2O3-SiO2 surface can hardly affect the formation of enolic species, NO3- and -NCO species. The reaction mechanism of NOx reduction and the effect of adding SiO2 are discussed based on these results.