Achieving toluene efficient mineralization over K/α-MnO2 via oxygen vacancy modulation

Oxygen vacancy plays an important role in adsorption and activation of oxygen species and therefore promotes the catalytic performance of materials in heterogeneous oxidation reactions. Here, a series of K-doped alpha-MnO2 materials with different K loadings were synthesized by a reproducible post processing process. Results show that the presence of K+ enhances the reducibility and oxygen vacancy concentration of alpha-MnO2 due to the break of charge balance and the formation of low valence Mn species. 4-K/MnO2 material exhibits the highest toluene oxidation activity and satisfied long-term stability and water resistance owing to its superior reducibility and abundant surface absorbed oxygen (O-ads). In situ DRIFTS demonstrate that O-ads greatly accelerates toluene dehydrogenation rate and promotes benzoate formation, enhancing the activation and decomposition of toluene molecules. Moreover, the C=C cleavage of benzene ring (forming maleic anhydride) is the rate-determining step of toluene oxidation, which can be easily occurred over 4-K/MnO2. (C) 2021 Elsevier Inc. All rights reserved.

Automated summary

The presence of K+ enhances the reducibility and oxygen vacancy concentration of alpha-MnO2, leading to improved catalytic performance in oxidation reactions. The 4-K/MnO2 material exhibits the highest catalytic activity and long-term stability due to its superior reducibility and abundant surface absorbed oxygen.