Tight coupling of oxygen vacancies and acidity on α-MnO2 through cerium doping engineering for efficient removal of multi-component VOCs

Abstract

An α-MnO2-based MnCe catalyst was synthesised by incorporating Ce, which demonstrated outstanding catalytic performance in the oxidation of multicomponent VOCs. Notably, the MnCe-7% catalyst achieved over 90% conversion and CO2 selectivity at temperatures below 300 °C in the presence of both toluene and chlorobenzene (CB). Furthermore, the catalytic activity remained above 80% at 256 °C in the presence of 5.0 vol.% H2O vapor. Structural analyses and DFT calculations indicated that the highly dispersed Ce could replace K in the interlayer and Mn in the intralayer of α-MnO2, resulting in a substantial increase in the number of oxygen vacancies and acidic sites. The close interaction between oxygen vacancies and acidic sites facilitated the oxidation and adsorption of VOCs, which was crucial for the high activity demonstrated by the MnCe-7% catalyst. Furthermore, the VOC-TPD and in situ DRIFTS results suggested that the mixed catalysis of toluene and CB on MnCe-7% concurrently engaged the MvK and E-R mechanisms. Toluene was found to supply additional H atoms, promoting the cleavage of C–Cl bonds in CB and enhancing the reaction kinetics.