Effect of hydrogen on reaction intermediates in the selective catalytic reduction of NOx by C3H6

Selective catalytic reduction of NOx by C3H6 in the presence of H2 over Ag/Al2O3 was investigated using in situ DRIFTS and GC–MS measurements. The addition of H2 promoted the partial oxidation of C3H6 to enolic species, the formation of –NCO and the reactions of enolic species and –NCO with NOx on Ag/Al2O3 surface at low temperatures. Based on the results, we proposed reaction mechanism to explain the promotional effect of H2 on the SCR of NOx by C3H6 over Ag/Al2O3 catalyst.