The simultaneous elimination of NOx and VOCs over industrial V-based catalytic filter: Reaction behaviors and catalyst structural evolutions

Abstract

The effective elimination of multiple pollutants (e.g., SOx, NOx, VOCs, dusts) in a simple unit is a long-term goal in the field of flue gas purification. In this work, the simultaneous removal of NOx and toluene was explored over the industrial V2O5-MoO3/TiO2 catalytic filter. The catalytic evaluations show that two reactions may share the same type of active sites, and observed adverse interaction effects at low temperatures, which significantly weakened as the temperature increased. Water vapor plays an amazing role with almost 100% removal efficiency of both NOx and VOCs for long-term test under harsh conditions at 350 ℃. Multiple structural characterizations confirmed the great structure stability. Especially, the catalyst components can be sulfated by SO2 and become more dispersed and uniform owing to the formation of solid solution phase, which further improves the removal performance. Moreover, the mechanism over the dynamically balanced V5+/4+/3+-SO3/42- sites was proposed, and the main reaction pathway of toluene oxidation follows the route of benzaldehyde → benzoic acid → maleic anhydride → CO2. Particularly, the In-situ DFIRTS results further confirm the above reaction/interaction effects and sulfur/steam-resistance mechanisms during the simultaneous removal of both NOx and VOCs. The excellent sulfur/steam-resistance performance and special structure features of the industrial V-based catalytic filter foreshadow the promising industrial application prospect for the effective purification of flue gas containing VOCs.