Effect of H2 on selective catalytic reduction of NOx by C3H6 over Ag/Al2O3 and Cu/Al2O3 catalysts

The effect of H-2 on the selective catalytic reduction (SCR) of NO, by C3H6 was investigated over Ag/Al2O3 and Cu/Al2O3 catalysts by steady in situ diffuse reflectance infrared Fourier transform spectroscopy. The presence of H-2 might accelerate the partial oxidation of C3H6 over Ag/Al2O3 to enolic species and acetate. The enolic species can react easily with nitrates to form surface -NCO species. An enhancement of enolic species formation promoted the SCR of NOx over Ag/Al2O3 in the presence of H-2. As for the Cu/Al2O3 catalyst, the addition of H-2 did not influence the partial oxidation of C3H6 to acetate but inhibited apparently the formation of nitrates, and subsequently blocked the reaction between acetate and nitrates to form the key -NCO species. This led to the deactivation of Cu/Al2O3 in the SCR of NO, in the presence of H-2.