Facile hydrothermal synthesis of VO2 nanosheets as robust catalysts for liquid-phase selective oxidation of benzyl alcohol under atmospheric O2

Abstract

The liquid-phase selective oxidation of benzyl alcohol is a sustainable route for the synthesis of benzaldehyde. Wherein, the exploration of heterogeneous and cheap metal oxide catalysts instead of noble metal catalysts is of interest in both practical implementation and green chemistry. Herein, vanadium dioxide (VO₂) nanosheets were prepared via a one-step hydrothermal reduction of V₂O₅ by citric acid. The hydrothermal temperature and time played important roles in determining the crystalline structure, morphology, and distribution of V valences of VO₂ materials. In the selective oxidation of benzyl alcohol by atmospheric O₂, VO₂ materials as heterogeneous catalysts showed catalytic activity. Based on XPS and O₂-TPD analysis, the catalytically active sites were proposed as V⁴⁺ species. At a reaction temperature of 95 °C, the maximum yield of benzaldehyde was up to 91.6% after 6 h, and the VO₂-140-5 catalyst can be recycled at least five times without any obvious loss in activity.