Influence of residual anions (Cl-, SO42- and NO3-) on Mn2O3 for photothermal catalytic oxidation of toluene

Abstract

Mn2O3 is a conventional catalyst that is applied in photothermal catalytic oxidation of toluene while regular anions like SO42-, Cl-, and NO3- from different Mn precursors are left in Mn2O3. When applied in toluene degradation, the declining activity of Mn2O3 is always observable because the residual anions block the Mn4+/Mn3+ active sites, shield the oxygen vacancies, and cube the production of active oxygen species (O2-, O-). Herein, it is found that the residual SO42-, Cl-, and NO3- make Mn2O3 incapacitated in deeply oxidizing the intermediates and cutting off the reaction process, and their influence ranks in the order of SO42->Cl->NO3-. Compared with pristine Mn2O3, the drops in CO2 conversion efficiency account for 11 %, 60 %, and 73 %, respectively. Nevertheless, rinsing with water is an effective method to remove the residual anions, and the more the rinsing, the better the toluene mineralization degree. This work provides a profound cognition of the deactivation mechanism of SO42-, Cl-, and NO3- and points out an effective way to abate their negative effect for the first time.