Insights into the Synergistic Catalytic Effect of TiO2 Supported V‐W Oxides for Selective C−H Bond Oxidation of Cyclohexane to KA Oil

It is urgent to develop an efficient and stable non-noble metal catalyst for selective C-H bond oxidation of cyclohexane. Herein, a series of V-W oxides supported on TiO₂ catalysts (V-W/TiO₂) were fabricated. The V-W/TiO₂ catalysts exhibited much higher catalytic activity for the selective oxidation of cyclohexane to KA oil, compared to that of V/TiO₂ and W/TiO₂ catalysts. The good distribution of active metals and the synergistic effect were responsible for the enhanced catalytic activity. H₂-TPR results disclosed that the presence of V in V-W/TiO₂ affected the reducibility of W⁶⁺ species, and XPS verified that an electronic interaction was formed between them. Such results led to good catalytic reusability of V-W/TiO₂ catalyst during the reactions, and no obvious activity loss was found after six runs. The reaction mechanism was investigated, and the results verified that hydroxyl radicals generated from H₂O₂ homolysis were the main active oxidative species. Theoretical study revealed that V dopant could regulate electronic structure of adjacent O atom, facilitating the adsorption of cyclohexane, and lower energy was needed for the rate-limiting step over V-W/TiO₂ during the whole oxidation reaction. This work developed an efficient V-W/TiO₂ catalyst for the selective oxidation of cyclohexane via a synergistic effect.