Insights into the Synergistic Catalytic Effect of TiO 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 TiO catalysts (V-W/TiO) were fabricated. The V-W/TiO catalysts exhibited much higher catalytic activity for the selective oxidation of cyclohexane to KA oil, compared to that of V/TiO and W/TiO catalysts. The good distribution of active metals and the synergistic effect were responsible for the enhanced catalytic activity. H-TPR results disclosed that the presence of V in V-W/TiO affected the reducibility of W species, and XPS verified that an electronic interaction was formed between them. Such results led to good catalytic reusability of V-W/TiO 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 HO 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/TiO during the whole oxidation reaction. This work developed an efficient V-W/TiO catalyst for the selective oxidation of cyclohexane via a synergistic effect.