SWA/TiO_2微球的制备及催化α-蒎烯异构化性能

采用溶胶-凝胶法和浸渍法,制备了纳米负载型H4SiW12O40（SWA）催化剂,考察了载体种类、SWA浸渍浓度对催化剂性能的影响。结果表明,用TiO2固载、8%SWA浸渍所得催化剂SWA/TiO2的催化性能较佳。利用XRD、TEM和BET比表面测定技术对其结构进行了表征。结果显示,该催化剂颗粒为圆球形,粒径为40～50 nm,具有较好的分散性。载体TiO2的引入明显增大了SWA的比表面积。将纳米SWA/TiO2用于催化α-蒎烯异构化反应,实验结果表明,该催化剂具有较好的催化活性和选择性,异构化反应的主产物是莰烯。在适宜的实验条件下,α-蒎烯的转化率达98%,莰烯的产率达58%。与其它负载型催化剂比较,SWA/TiO2具有用量少、活性高、反应时间短等特点。

Preparation of nanometer microsphere of titanium dioxide supported silicotungstic acid and catalytic performance for a-pinene isomerization

Nanometer microsphere SWA/Ti02, a novel supported catalyst, was prepared by sol-gel method and impregnation. The effects of the kinds of carriers, the impregnating consistence of silicotungstic acid （SWA） were investigated. The results showed that the catalyst displayed excellent activity when it suppor- ted by TiO2 and impregnated with 8% SWA. The structure of SWA/TiO2 was characterized by XRD,TEM and BET surface area measurement technology. The results indicated that the catalyst had a narrow parti- cle size distribution with an average particle diameter about 40 ~ 50 nm. The surface area of catalyst was obviously increased supported by TiO2. Nanometer SWA/TiO2 was used as a catalyst in a-pinene isomeri- zation. Experimental results showed that the catalyst had better catalytic activity and selectivity. The main product of isomerization reaction was camphene. Under the suitable technology conditions, the conversion of ct-pinene reached 98% and the camphene yield reached 58%. Compared with other supported cata- lysts, the SWA/TiO2 can short reaction time, high activity and decrease catalyst quantity.