Mesoporous vanadium oxide as catalyst for liquid-phase selective oxidation of diphenylmethane to benzophenone
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The mesoporous vanadium oxide (MVO) was prepared from the surfactant cetyltrimethylammonium bromide along with benzyl alcohol as co-surfactant. It was found that the presence of benzyl alcohol in the synthetic mixture was essential to the formation and stability of MVO material. Characteristic mesoporous structure with uniform channel spacing as well as large surface area and pore volume of MVO sample were identified by XRD, SEM, TEM, and N2 sorption techniques. The structure of vanadium–oxygen framework was explored using FT-IR and 51V MAS NMR spectroscopy; the MVO sample possessed distorted tetrahedron structure. Results from TPR studies indicated the easier reducibility of MVO as compared to bulk V2O5. In the liquid-phase selective oxidation of diphenylmethane to benzophenone in acetic acid as solvent, the MVO catalyst exhibited remarkably better catalytic performance than bulk V2O5; at 60 °C, the conversion and benzophenone selectivity reached 39.6 and 96.7% after 1 h reaction time, with a catalyst turnover frequency of 24.2 h−1. These superior results were properly correlated to the physico-chemical properties of MVO catalyst.
KeywordsMesoporous vanadium oxide Characterization Oxidation Diphenylmethane Benzophenone
The authors would like to thank the National Science Council of the Republic of China for financial support. We are grateful to Prof. K. J. Chao of National Tsing Hua University for her helpful comments and discussion.
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