Study on Effect of SO2 on the Selective Catalytic Reduction of NOx with Propene over Ag/Al2O3 by in Situ DRIFTS

In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) was used to investigate the effect of SO2 on the selective catalytic reduction (SCR) of NOx by C3H6 over an Ag/Al2O3 catalyst. The DRIFTS spectra showed an obvious blue shift in the band of sulfate species when its coverage over Ag/Al2O3 was increased. The sulfate species not only inhibited the formation of NO3−, but also suppressed the reaction of the enolic species or acetate species with NO3− to form –NCO species. These behaviors are responsible for the deactivation of Ag/Al2O3 during the SCR of NOx by C3H6 in the presence of SO2.