Relationship between the molecular structure of V2O5/TiO2 catalysts and the reactivity of SO2 oxidation

Abstract

The relationship between the molecular structure of V₂O₅/TiO₂ catalysts and the reactivity of SO₂ oxidation was investigated. The dispersion state and surface properties of supported vanadia over V₂O₅/TiO₂ catalysts were studied with various experimental techniques. Isolated vanadia species were dispersed on the TiO₂ surface as Ti–O–V bonds at VO_x coverage far below the monolayer. Polymeric vanadia species were then formed through the V–O–V bonds as the VO_x coverage increased. SO₂ temperature-programmed desorption and in situ diffuse reflectance infrared Fourier transform spectroscopy were conducted to study the interaction between SO₂ and V₂O₅/TiO₂. On the V₂O₅/TiO₂ catalysts, the turnover frequency of SO₂ oxidation was almost constant with increased VO_x coverage under the condition of constant temperature. VO was demonstrated to play a critical role in the SO₂ adsorption and oxidation. A possible reaction mechanism was established in this study.