Time-resolved observation of V2O5/TiO2 in NH3-SCR reveals the equivalence of Brønsted and Lewis acid sites

The involvement of Lewis and Brønsted acid sites on V2O5/TiO2 catalyst in the selective catalytic reduction of NO with NH3 (NH3-SCR) is under debate. Here, a Li doping strategy is applied to selectively block Brønsted sites, which aims to prepare model catalysts with the same V loading but different ratios of the two acid sites. Time-resolved in situ DRIFTS observation demonstrates that the surface ammonia species pre-adsorbed on Lewis and Brønsted sites can participate equally in the reaction. Consideration of site redistribution in the early stages of the transient reaction is key to accurate measurement of the ammonia consumption rate.