Exploring the role of V2O5 in the reactivity of NH4HSO4 with NO on V2O5/TiO2 SCR catalysts

Abstract

In this study, attention was focused on the interactions between NH₄HSO₄ and vanadium species in the selective catalytic reduction (SCR) of NO with NH₃, along with the role of vanadium species in the reactivity of NH₄HSO₄ with NO on V₂O₅/TiO₂ catalysts. Both vanadium and sulfate species occupied the TiO₂ surface basic hydroxyl groups; the decreased TiO₂ surface basic sites resulting from the introduction of NH₄HSO₄ in turn promoted the formation of polymeric vanadium species. Given increases in vanadium content, formation of polymeric vanadium species and reactive electrophilic oxygen species on the catalysts occurred, which was an important reason for the enhanced reactivity of NH₄HSO₄ with NO on the high V content catalysts. Besides, a higher electron cloud density around the S atoms in SO₄²⁻ could be detected for the high V content catalysts, on which SO₄²⁻ would be easily reduced to SO₂ during the TPSR process. In situ diffuse reflectance infrared Fourier transform spectroscopy confirmed that NH₄⁺ in NH₄HSO₄ functioned as a reductant during reaction with gaseous NO, while S-containing functional groups were stabilized as tridentate sulfate anions on the catalyst surface.