Novel Ag–Pd/Al 2O 3–SiO 2 for lean NO x reduction by C 3H 6 with high tolerance of SO 2

Abstract

Activity test and in situ DRIFTS experiments were carried out on the selective catalytic reduction of NO x by propene over Ag (5 wt%)–Pd (0.01 wt%)/Al 2O 3 and Ag (5 wt%)–Pd (0.01 wt%)/Al 2O 3–SiO 2. The activity test results showed that the Ag–Pd/Al 2O 3–SiO 2 had a higher NO x conversion than Ag–Pd/Al 2O 3 in the presence of SO 2. The in situ DRIFTS results showed the SO 2 poisoned Ag–Pd (0.01 wt%)/Al 2O 3 surface inhibited the formation of enolic species and NO 3 - , which are reactive intermediates to form –NCO species. However, the SO 2 poisoned Ag–Pd (0.01 wt%)/Al 2O 3–SiO 2 surface can hardly affect the formation of enolic species, NO 3 - and –NCO species. The reaction mechanism of NO x reduction and the effect of adding SiO 2 are discussed based on these results.