New insights into the various decomposition and reactivity behaviors of NH4HSO4 with NO on V2O5/TiO2 catalyst surfaces

This study illustrated the interaction between NH4HSO4 and V2O5/TiO2 catalysts in the selective catalytic reduction of NO with NH3, along with the variation in the decomposition and reactivity of NH4HSO4 with NO on the catalyst surface resulting from the interaction. On the catalyst surface, sulfur species transformed from HSO4- into bidentate SO42-, which was subsequently bonded to TiO2 sites; N-containing species remained as NH4+. Given NH4HSO4 deposition on the catalyst surface, electrons around the Ti atoms deviated toward SO42- because of the species' strong electronegativity, thereby leaving Ti atoms in an electron-deficit state. Consequently, compared with those of crystallite NH4HSO4, the decomposition and reactivity of NH4HSO4 with NO were promoted on the catalyst surface. An increase in NH4HSO4 deposition amount led to the occurrence of the (NH4)(2)TiO(SO4)(2) phase, which adversely affected the decomposition and reactivity behaviors observed. High V2O5 contents enhanced the reactivity of NH4HSO4 with NO between 100 and 250 degrees C. H2O also exerted negative effects on the reactivity of NH4HSO4 with NO. In situ diffuse reflectance infrared Fourier transform spectroscopy confirmed that the as-formed NH4HSO4 functions as a reductant during reaction with NO, similar to the behavior of impregnated NH4HSO4. (C) 2015 Elsevier B.V. All rights reserved.