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

Mn 2 O 3 is a conventional catalyst that is applied in photothermal catalytic oxidation of toluene while regular anions like SO 4 2- , Cl - , and NO 3 - from different Mn precursors are left in Mn 2 O 3 . When applied in toluene degradation, the declining activity of Mn 2 O 3 is always observable because the residual anions block the Mn 4+ /Mn 3+ active sites, shield the oxygen vacancies, and cube the production of active oxygen species (O 2 - , O - ). Herein, it is found that the residual SO 4 2- , Cl - , and NO 3 - make Mn 2 O 3 incapacitated in deeply oxidizing the intermediates and cutting off the reaction process, and their influence ranks in the order of SO 4 2- >Cl - >NO 3 - . Compared with pristine Mn 2 O 3 , the drops in CO 2 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 SO 4 2- , Cl - , and NO 3 - and points out an effective way to abate their negative effect for the first time. • NO 3 - poses a neglectable impact on Mn 2 O 3 ’s catalytic activity. • SO 4 2- and Cl - anions cover the OVs and active sites, causing reduced catalytic properties. • Multiple rinsing washes the anions away from MnC 2 O 4 to endow high activity of Mn 2 O 3 .