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 NOx over Ag/Al2O3. Activity measurement showed that NOx 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.