Anti-Poisoning Mechanisms of Sb on Vanadia-Based Catalysts for NO x and Chlorobenzene Multi-Pollutant Control.

Modulating vanadia-based metal oxides is one of the effective methods for designing difunctional catalysts for simultaneous control of NO and chlorobenzene (CB) from the emissions of industrial sources. Excessive NH adsorption and polychlorinated species accumulation on the surface are the primary issues poisoning catalysts and reducing their lifetime. Herein, Sb is selected as an NH adsorption alleviator and polychlorinated species preventor dopant on VO-WO/TiO. The catalyst exhibits an excellent performance for total NO and 90% CB conversions at 300-400 °C under a gas hourly space velocity (GHSV) of 60,000 mL g h. The HCl and N selectivities are maintained at 90 and 98%, respectively. The anti-poisoning ability could be attributed to the generated V-O-Sb chains on the surface: the band gap of vanadium is narrowed and the electron capability is strengthened. The above variation weakens the Lewis acid sites and blocks the electrophilic chlorination reactions of the catalyst surface (formation of polychlorinated species). In addition, oxygen vacancies on Sb-O-Ti also increase: the ring opening of benzoates is accelerated and NH adsorption energy is weakened. The above variation lowers the energy barriers of C-Cl cleavage even under NH pre-adsorption models and enhances NO reduction thermodynamically and kinetically.