Abstract:

A series of molybdovanadophosphoric heteropoly acid catalysts were prepared by precipitation method. With oxygen as the oxidant, the catalyst was used for one-step oxidation of isooctanol to isooctanoic acid under atmospheric pressure. The effects of vanadium and cesium addition, as well as process conditions, on the catalyst performance and the reaction were investigated, and possible reaction mechanisms were deduced. The results showed that vanadium could accelerate the redox cycle of catalysts and improve their redox performance and catalytic efficiency, while cesium could affect the acidity and specific surface area of the catalyst by replacing protons in heteropolyacids. Appropriate acidity, high specific surface area, and rapid redox cycle processes were key factors for catalysts to have high activity and selectivity. Among all the prepared catalysts, Cs₃H₂PMo₁₀V₂O₄₀ showed the best catalytic activity under the optimal reaction conditions (solvent is benzene, reaction temperature was 120℃, catalyst dosage was isooctanol mass 11% of, oxygen flow rate was 20mL/min, reaction time is 10h), and the conversion of isooctanol could reach 60.7%, and the selectivity of isooctanoic acid was 81.5%. The catalyst could be reused for 5 times with good stability.

Key words: heteropoly acid, catalyst, oxidation, isooctanoic acid, stability

摘要：

采用沉淀法制备了一系列磷钼钒杂多酸催化剂，以氧气为氧化剂，在常压下将其用于异辛醇一步氧化合成异辛酸，考察了钒和铯两种元素添加量以及工艺条件对催化剂性能和反应的影响，并推测了可能的反应机理。结果表明：钒可以加速催化剂的氧化还原循环过程，提高其氧化还原性能，促进催化效率的提升；铯会通过取代杂多酸中的质子影响催化剂的酸性和比表面积。适宜的酸性、高的比表面积以及快速的氧化还原循环过程是催化剂具有高活性和选择性的关键。在所有制备的催化剂中，Cs₃H₂PMo₁₀V₂O₄₀具有最佳的催化效果，在最优反应条件下（溶剂为苯，反应温度为120℃，催化剂用量为异辛醇质量的11%，氧气流量为20mL/min，反应时间为10h），异辛醇转化率可达60.7%，异辛酸选择性为81.5%。催化剂可重复使用5次，具有较好的稳定性。

关键词: 杂多酸, 催化剂, 氧化, 异辛酸, 稳定性