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甲苯低温液相催化氧化制备苯甲醛是最具有竞争力的苯甲醛绿色合成路线.我们研究了溶胶凝胶法制备的V-Mo-O催化剂在液相低温条件下选择性氧化甲苯制备苯甲醛的性能.结果显示,钒钼摩尔比和焙烧温度是影响催化剂的主要因素,当钒钼的摩尔比为6∶7,焙烧温度为500℃时,催化剂表现出最佳性能.物性表征显示,该条件下合成催化剂V-Mo-O晶体呈棒状结构,直径约700 nm,长度约6μm.体相主要以Mo6V9O40和MoO3相态存在.X光电子能谱表征显示,MoO3物种分散于结晶体外表面,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,有利于提高其催化性能.催化剂在80℃温度下,以双氧水为氧化剂,冰乙酸为溶剂,反应30 min,甲苯的转化率达到38.9%,苯甲醛的选择性为69.7%.
The preparation of benzaldehyde by low temperature liquid phase catalytic oxidation of toluene is the most competitive green synthesis route of benzaldehyde.We studied the selective oxidation of toluene to benzaldehyde by sol-gel V-Mo-O catalyst at low temperature The results showed that the molar ratio of vanadium and molybdenum and the calcination temperature were the main factors affecting the catalyst, and the catalyst showed the best performance when the molar ratio of vanadium and molybdenum was 6: 7 and the calcination temperature was 500 ℃ .Physical characterization showed that this condition The synthesized V-Mo-O crystal has a rod-like structure with a diameter of about 700 nm and a length of about 6 μm. The bulk phase exists mainly in the Mo6V9O40 and MoO3 phases. X-ray photoelectron spectroscopy shows that the MoO3 species is dispersed on the outer surface of the crystal, The hierarchical assembly of molybdenum species in different oxidation states may contribute to the transmission of oxygen species, which is beneficial to improve its catalytic performance.Under the condition of 80 ℃, hydrogen peroxide as oxidant and glacial acetic acid as solvent, the reaction time is 30 min, the conversion of toluene Reached 38.9%, the selectivity of benzaldehyde was 69.7%.