Unraveling the effects of the coordination number of Mn over α-MnO2 catalysts for toluene oxidation

By Feng Wang, Jiang Deng, Sarawoot Impeng, Yongjie Shen, Tingting Yan, Guorong Chen, Liyi Shi, Dengsong Zhang. 2020

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Abstract Herein, nanorod-like α-MnO2 catalysts with 5-, 4-, and 3-coordinated Mn exposed on the surface (α-MnO2-Mn5c, α-MnO2-Mn4c, and α-MnO2-Mn3c) were employed for toluene combustion. The toluene combustion performance followed an order of α-MnO2-Mn4c > α-MnO2-Mn3c > α-MnO2-Mn5c. The effects of the coordination number of Mn over α-MnO2 catalysts for toluene oxidation were unraveled. The excellent activity of α-MnO2-Mn4c was due to stronger interactions between Mn4c with reactants and a larger amount of charge transfer from the Mn4c to the adsorbed O2, as evidenced by computational results. The results of operando diffuse reflectance infrared Fourier transform spectroscopy and gas chromatography-mass spectrometry revealed that toluene oxidation over α-MnO2 catalysts proceeded by coordination number-dependent rate-determining step. For α-MnO2-Mn4c, the rate-determining step was the cleavage of benzene species, while decarboxylation of benzoic acid was more sluggish for α-MnO2-Mn5c. These findings strongly pave a way for understanding the coordination number-induced improvement of catalytic performance of nanorod-like α-MnO2 catalysts for toluene oxidation and a deeper understanding of the mechanism of toluene degradation.

Subfields: Catalysis, Electrical and Electronic Engineering, Materials Chemistry

View Paper: https://www.semanticscholar.org/paper/5957c2132904ef5f6a54151dd82a15ec21d1bac6