Co doping induced phase transition and its distinct effects on the catalytic performance of MnO2 toward toluene oxidation

Abstract

Manganese oxides are very important and conventional catalysts that have demonstrated appreciable catalytic activity for the oxidation of volatile organic compounds (VOCs). Nevertheless, pure manganese oxides suffer from poor activity especially at low temperatures, making it difficult to meet industrial applications. In this work, Co species were successfully doped into the lattice of MnO2 aiming at constructing defects to boost its catalytic performance for VOCs oxidation. In combination with the results of systematic characterizations, we found that Co doping forced the catalyst to transform from α‐MnO2 to spinel phase (Co,Mn)(Co,Mn)2O4. During this process, the metal–oxygen bonds are significantly weakened, which induces the massive generation of oxygen defects, endowing the Co modified catalysts with enhanced redox property and improved ability to adsorb and activate gaseous oxygen. As a result, Co doped catalysts show much better catalytic activity compared with pristine α‐MnO2, among which Mn10Co10 exhibits the best performance showing a decrease of 41°C and 51°C in T50 and T90 compared with the raw sample, respectively. Furthermore, Mn10Co10 demonstrates excellent stability, water resistance, and reusability, illustrating a great potential for industrial applications. Moreover, path of toluene decomposition over Co10Mn10 was revealed by in situ DRIFTS experiment, which complies with the sequence of toluene → benzyl alcohol → benzaldehyde → benzoate → maleic anhydride → CO2 and H2O.