固载MnP-PGMA/SiO_2催化剂的制备及其对乙苯氧化反应的催化性能  

Preparation of Immobilized MnP-PGMA/SiO_2 Catalyst and Its Catalytic Activity for Ethylbenzene Oxidation

作　　者：章艳[1] 高保娇[1] 王蕊欣[1] 

机构地区：[1]中北大学化学工程系,山西太原030051

出　　处：《催化学报》2008年第3期247-252,共6页

基　　金：山西省自然科学基金(20040402 JJ).

摘　　要：在溶液聚合体系中,将聚甲基丙烯酸缩水甘油酯(PGMA)接枝在硅胶微粒表面,制备了接枝微粒PGMA/SiO2;通过环氧键的开环反应,实现了Meso-四(对羟基苯基)卟啉(THPP)在PGMA/SiO2上的键合,制备了键合有羟基苯基卟啉(HPP)的HPP-PGMA/SiO2;进一步使锰盐与HPP-PGMA/SiO2发生配位反应,制备了固载MnP(锰卟啉)-PGMA/SiO2催化剂.以分子氧为氧源,将MnP-PGMA/SiO2催化剂用于乙苯氧化反应,常压下实现了乙苯向苯乙酮的转化,并探索了乙苯氧化过程中的若干规律.结果表明,MnP-PGMA/SiO2催化剂能有效活化分子氧,显著催化乙苯氧化为苯乙酮的反应过程;于95℃常压下反应12 h,苯乙酮收率接近18%,产物α-甲基苄醇的含量则极少.在催化氧化体系中,作为仿生催化剂的MnP存在最适宜用量,过量的MnP反而会抑制催化剂活性.在PGMA/SiO2表面,MnP的固载密度越小,催化剂的活性越高.在循环使用中,催化剂的活性呈升高的趋势.Ploy（glycidyl methacrylate） （PGMA） was grafted on the surface of silica gel particles in a solution polymerization system, and PGMA/SiO2 was prepared. Subsequently, meso-tetra（4-hydroxylphenyl） porphyrin （THPP） was bound on PGMA/SiO2 through the ring-opening reaction between the epoxy groups of the grafted PGMA and the hydroxyl groups of THPP, resulting in the HPP-PGMA/SiO2. Further, the coordination reaction between HPP-PGMA/SiO2 and MnC12 was performed, and the immobilized MnP （manganoporphyrin）-PGMA/SiO2 was obtained. The MnP-PGMA/SiO2 catalyst was used in the oxidation of ethylbenzene with molecular oxygen as the oxidant, and the transform of ethylbenzene into acetophenone was realized. The effects of various factors, such as the catalyst amount and MnP-immobilizing density, on the supported MnP-PGMA/SiO2 catalyst were examined. The results showed that the supported MnP-PGMA/SiO2 catalyst can effectively activate molecular oxygen and obviously catalyze the oxidation of ethylbenzene to acetophenone. MnP-PGMA/SiO2 exhibited high catalytic activity and selectivity, and the yield of acetophenone reached 18 % under the conditions of p（O2） = 0.1 MPa, T = 95℃ , and t = 12 h, but the content of α-methyl benzoic alcohol was very small. As a biosimulation catalyst, MnP in the supported catalyst had an optimum amount for the reaction, and the excess amount would inhibit the catalyst activity. The supported MnP-PGMA/SiO2 catalyst with a smaller MnP-immobilizing density had higher catalytic activity, and the catalytic activity increased slowly when the catalyst was reused.

关 键 词：聚甲基丙烯酸缩水甘油酯 硅胶 接枝聚合 锰卟啉 负载型催化剂 乙苯 氧化 苯乙酮 

分 类 号：O643.3[理学—物理化学]