Efficient α-MnO2 with (210) facet exposed for catalytic oxidation of toluene at low temperature: A combined in-situ DRIFTS and theoretical investigation

The alpha-MnO2 catalysts with (1 1 0), (2 1 0) and (3 1 0) crystal facets exposed were prepared via hydro-thermal method and studied for the catalytic oxidation of toluene. Some characterization technologies and DFT theoretical calculation were combined to analyze the as-synthesized catalysts. The alpha-MnO2 catalyst exposed with the (2 1 0) plane displayed best catalytic performance and attained complete toluene conversion at 140 degrees C. The O-2-TPD and XPS results exhibited the amount of surface lattice oxygen on alpha-MnO2-210 catalyst was largest. Lower accumulation and faster disintegration of intermediates which was characterized by in-situ DRIFTS could be discovered on the surface of alpha-MnO2-210 catalyst. The results of DFT calculation showed that the unique atomic arrangement of alpha-MnO2-210 catalyst enhanced the charge separation and conversion, promoting the formation of active oxygen and the activation of toluene. The Ea of alpha-MnO2-210 catalyst was 24.75 kJ mol(-1), lowest among the three catalysts. This work highlights the facet effects on catalytic property and provides new insight into the understanding of catalytic oxidation reaction mechanism of toluene. (C) 2020 Elsevier Ltd. All rights reserved.

Automated summary

Different crystal facets of alpha-MnO2 catalysts prepared by hydro-thermal method exhibit varying catalytic activities towards toluene, with the (2 1 0) facet displaying the best performance and achieving complete conversion at lower temperature. The results suggest that the unique atomic arrangement of the (2 1 0) facet enhances charge separation and conversion, leading to improved catalytic properties.