摘要
为改善浸渍法制备的负载型钨磷酸催化剂HPWA／SiO2，在有水参与的反应中活性中心Keggin结构钨磷酸（HPWA）的流失，换用溶胶-凝胶法制备了一系列ω（HPWA）=11．1％～40％的负载型钨磷酸催化剂HPWA—SiO2。通过红外光谱和紫外漫反射光谱联合表征，证明溶胶-凝胶法制备的HPWA—SiO2催化剂中，钨磷酸依然保持Keggin结构，没有转变为钨硅盐等而失去酸催化功能。在此基础上对溶胶一凝胶法制备的HPWA—SiO2和浸渍法制备的HPWA／SiO2进行了水相中钨磷酸流失率考察，结果表明，溶胶一凝胶法制备的HPWA—SiO2催化剂的流失率基本保持在0．71％～0．84％，而浸渍法制备的HPWA／SiO2催化剂的流失率为2．4％，是前者的3倍多，从而证明溶胶-凝胶法制备的负载型钨磷酸催化剂，能够更好地防止钨磷酸活性中心在水相反应中的流失。
The phosphotungstic acid （HPWA） with Keggin structure as active center would leak out in the reaction including water phase from silica-loading heteropolyacid catalyst HPWA/SiO2 prepared by impregnation. So another type of silica-included heteropolyacid catalysts HPWA-SiO2 with different mass loading（ 11.1% - 40. 0% ） were prepared by sol-gel method in order to decrease the leakage of HPWA in reactions. By means of FT-IR and UV diffuse reflection techniques, it was confirmed that in the HPWA-SiO2 catalysts prepared by sol-gel method, HPWA on the supporters still kept the Keggin structure and had acid catalytic function. Then the leakages of HPWA-SiO2 catalysts and HPWA/SiO2 catalysts were compared. The results showed that the leakages of HPWA-SiO2 catalysts prepared by solgel method with 11.1% - 40. 0% mass loading were among 0. 71% - 0.84% , and the leakage of HPWA/SiO2 catalyst prepared by impregnation with 25% mass loading was 2. 4%. The silica-included HPWA catalyst prepared by sol-gel method could effectively prevent the active center HPWA from leaking out in the reaction including water phase.
出处
《精细化工》
EI
CAS
CSCD
北大核心
2007年第7期671-673,共3页
Fine Chemicals
基金
广东省自然科学基金(0530012706021469)
广东省科技计划项目(2005B10201053)~~
