Periodic first-principles density functional (DFT) calculations have been performed to give an understanding of the active site and mechanism for the selective catalytic reduction (SCR) of NO by NH3 over NH5 in the presence of gaseous oxygen. Two synergetic functional groups, i.e. dual vanadium sites, have been found on the V2O5(010) surface: the hydroxy group (V-OH) containing vanadyl oxygen for the formation of NH4+ species, and the V=O group for the activation of the NH4+ formed. The results have revealed that NH3 is adsorbed preferentially on the Bronsted acid, and the NO hardly combines with the surface lattice oxygens to form NO2, but rather gaseous NO interacts with the pre-adsorbed NH4+ species to release N2 and H2O. This study suggests that the catalytic process of the SCR reaction follows an Eley-Rideal type mechanism.
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