二氧化硅负载五氧化二钒合成、表征和催化性能研究

在以丙酮为溶剂、以V2O5/SiO2为催化剂、8-羟基喹啉为助剂的催化条件下,以过氧化氢水溶液为氧化剂,对环己烯催化氧化制备环己烯酮的催化反应体系进行了研究。考察了V2O5的负载量以及8-羟基喹啉的用量及反应温度对环己烯氧化反应的影响,发现适当的负载量有利于V2O5催化性能的提高。结果表明,当V2O5负载量(质量分数)为5%、催化剂的量和8-羟基喹啉的质量相等、反应温度为30℃时环己烯的转化率和环己烯酮的选择性较好。这源于V2O5高度分散于SiO2载体上,增大了活性组分V2O5的表面积,从而增加了其活性中心的个数及活性组分与反应物的接触面积,从而增加了催化活性。

V2O5/SiO2catalyst:synthesis, characterization and investigation of their catalytical property

The catalytic property of V2 O5-loaded SiO2 carrier was examined by oxidation of cyclohexene to 2-cyclohexen-l-one using H2O5 as oxidized agent in the presence of 8 hydroxyquinoline in acetone solvent at different reaction conditions. Particu- larly, the influence of catalyst V2O5 quantity, assistant-catalyst 8 hydroxyquinoline quantities and reaction temperature on the oxidation of cyclohexene was investigated in detail. It is found that 5 % V2O-5-1oaded SiO2 carrier is in favor of the improve- ment of the catalytic activity while other reaction conditions are the same. The experimental results verify that the conversion rate of cyclohexene and the reaction selectivity of 2- cyclohexen-l-one are better with 5% V2O5 on SiO2 carrier, the equal quantity of catalyst and 8-hydroxyquinoline and the reaction temperature at 30 ℃. This is attributed to better dispersion of V2O5 among SiO2 carrier, leading to the large surface areas of V2O5 , which is in favor of producing more active sites as well as increasing the contact area of reactants and the active component.