V-Mo-O催化剂的制备及催化甲苯合成苯甲醛的研究

在低温液相条件下，催化氧化甲苯合成苯甲醛是具有竞争力的苯甲醛合成路线。采用溶胶凝胶法制备了V-Mo-O催化剂，评估了在液相低温条件下选择性氧化甲苯的催化性能。研究表明，钒钼配比和焙烧温度对催化剂性能影响显著，适宜的钒钼物质量的配比为6:7，适宜的焙烧温度为500℃。扫描电镜实验表明，该条件下合成的催化剂呈棒状结构，直径约700nm,长度约6µm。X射线衍射观测到催化剂中拥有Mo6V9O40和MoO3物相。X光电子能谱表征，棒状催化剂外表面覆盖一层主含MoO3物种的薄层，这种不同氧化态钼物种的分层组装可能有助于氧物种的传递，提高了其催化性能。当反应温度为80℃，氧化剂为双氧水，溶剂为冰乙酸时，甲苯在该催化剂上的转化率为38.9%，苯甲醛的选择性为69.7%。

V-Mo-O catalyst preparation and catalytic oxidation of toluene to benzaldehyde

A competitive benzaldehyde synthetic route was catalytic selective oxidation of toluene under mild conditions. Assessed V-Mo-O catalyst performance of selective catalytic oxidation of toluene under mild conditions , catalysts were prepared by the sol-gel method. The results showed that the molar ratio of vanadium molybdenum and calcination temperature had significant effects on the catalyst performance, The most suitable molar ratio of vanadium molybdenum was 6:7, and the most suitable calcination temperature was 500 oC. The results of SEM showed that Catalyst was rod structure, the diameter was about 700nm ,the length was about 6µm ,and the Mo6V9O40 and MoO3 phase was observed by the XRD. The results of XPS showed that the rod structure catalyst was covered with a thin layer of MoO3, the different layers assembled with different oxidation state of Mo may contribute to the transmission of oxygen species, which led catalytic performance was improved.When the reaction temperature was 80oC, hydrogen peroxide was as the oxidant, ice acetic acid was as the solvent , the conversion rate of toluene was 38.9%, the selectivity of benzaldehyde was 69.7%.