Key intermediates from simultaneous removal of NOx and chlorobenzene over a V2O5-WO3/TiO2 catalyst: a combined experimental and DFT study

Simultaneous elimination of NOx and dioxins in a selective catalytic reduction (SCR) converter has been proved to be a promising technology for multipollutant control in stationary emission. Lack of a systematic understanding of the complex interaction mechanism between a SCR reaction and catalytic oxidation is one of the main challenges of this technology. Herein, using chlorobenzene (CB) as the model molecule of dioxins, we perform an in-depth study on the interaction mechanism and key intermediates over a V2O5-WO3/TiO2 catalyst via in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and density functional theory (DFT) calculations. The results indicate that CB suppresses the active cis-N2O22- formation due to the enhancement of the reducibility of V oxides. The dissociated Cl- combines with vanadium to form vanadium chloride which activates adjacent bridging hydroxyl groups, resulting in the enhancement of surface Bronsted acidity. Besides, the presence of NO and O-2 is conducive to CB deep oxidation while NH3 exhibits an inhibitory effect.