Elucidating the sensitivity of vanadyl species to water over V2O5/TiO2 catalysts for NOx abatement via operando Raman spectroscopy

Abstract

Vanadia-based catalysts are widely used in the selective catalytic reduction of NOx with NH3 (NH3-SCR) for NOx abatement. However, the effect of water on specific vanadyl species is still unclear. Herein, the temperature-dependent sensitivity of vanadyl species to water has been originally elucidated via operando Raman spectroscopy. Interestingly, the stronger competitive adsorption of NH3 on polymeric vanadyl species in the presence of H2O dominants the NH3-SCR reaction above 250 °C despite the polymeric vanadyl show stronger adsorption to H2O than the monomeric ones. By contrast, the association of water molecules via hydrogen bonding dominants the activity degeneration to both monomeric and polymeric vanadyl species at temperatures below 250 °C. Furthermore, the stronger adsorption of water on polymeric vanadyl will give rise to even worse degeneration. This work elucidates the interaction of vanadyl species with water, which is essential for the development of high-performance catalysts for water-tolerant NOx abatement.