A common feature of H2-assisted HC-SCR over Ag/Al2O3

Abstract

CH₄, C₂H₂, C₂H₄, C₃H₆, and C₃H₈ were selected as reductants for selective catalytic reduction (SCR) of NO_x over Ag/Al₂O₃. Activity measurement showed that NO_x reduction by hydrocarbons containing two- or three-carbon atoms was clearly promoted by H₂ over Ag/Al₂O₃ at low temperatures, while such enhancement did not occur in the case of CH₄-SCR. Gas chromatography and gas chromatography coupled to a mass spectrometer analysis showed that the partial oxidation of hydrocarbons with more than one carbon atom was triggered at low temperatures by H₂ addition over Ag/Al₂O₃. On the surface of Ag/Al₂O₃, in situ diffuse reflectance infrared Fourier transform spectra indicated that this enhancement mainly originated from the formation of reactive enolic species, which is a common feature of H₂-assisted HC-SCR.