Zhang Lei, Abbenhuis Hendrikus C L, Gerritsen Gijsbert, Bhriain Nollaig Ní, Magusin Pieter C M M, Mezari Brahim, Han Wei, van Santen Rutger A, Yang Qihua, Li Can
State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, China.
Chemistry. 2007;13(4):1210-21. doi: 10.1002/chem.200600752.
A novel interfacial hybrid epoxidation catalyst was designed with a new immobilization method for homogeneous catalysts by coating an inorganic support with an organic polymer film containing active sites. The titanium silsesquioxane (TiPOSS) complex, which contains a single-site titanium active center, was immobilized successfully by in-situ copolymerization on a mesoporous SBA-15-supported polystyrene polymer. The resulting hybrid materials exhibit attractive textural properties (highly ordered mesostructure, large specific surface area (>380 m2 g-1) and pore volume (>or==0.46 cm3 g-1)), and high activity in the epoxidation of alkenes. In the epoxidation of cyclooctene with tert-butyl hydrogen peroxide (TBHP), the hybrid catalysts have rate constants comparable with that of their homogeneous counterpart, and can be recycled at least seven times. They can also catalyze the epoxidation of cyclooctene with aqueous H2O2 as the oxidant. In two-phase reaction media, the catalysts show much higher activity than their homogeneous counterpart due to the hydrophobic environment around the active centers. They behave as interfacial catalysts due to their multifunctionality, that is, the hydrophobicity of polystyrene and the polyhedral oligomeric silsesquioxanes (POSS), and the hydrophilicity of the silica and the mesoporous structure. Combination of the immobilization of homogeneous catalysts on two conventional supports, inorganic solid and organic polymer, is demonstrated to achieve novel heterogeneous catalytic ensembles with the merits of attractive textural properties, tunable surface properties, and optimized environments around the active sites.
通过用含有活性位点的有机聚合物膜包覆无机载体，设计了一种用于均相催化剂的新型固定化方法，从而制备了一种新型界面杂化环氧化催化剂。含单中心钛活性中心的钛倍半硅氧烷（TiPOSS）配合物通过原位共聚成功固定在介孔SBA - 15负载的聚苯乙烯聚合物上。所得杂化材料具有吸引人的结构性质（高度有序的介孔结构、大的比表面积（>380 m2 g-1）和孔体积（>或==0.46 cm3 g-1）），并且在烯烃环氧化反应中具有高活性。在用叔丁基过氧化氢（TBHP）进行环辛烯环氧化反应时，杂化催化剂的速率常数与其均相对应物相当，并且可以循环使用至少七次。它们还可以以过氧化氢水溶液为氧化剂催化环辛烯的环氧化反应。在两相反应介质中，由于活性中心周围的疏水环境，催化剂显示出比其均相对应物更高的活性。由于其多功能性，即聚苯乙烯和多面体低聚倍半硅氧烷（POSS）的疏水性以及二氧化硅和亲水性介孔结构，它们表现为界面催化剂。将均相催化剂固定在无机固体和有机聚合物这两种传统载体上的组合，被证明可以实现具有吸引人的结构性质、可调表面性质以及活性中心周围优化环境等优点的新型多相催化体系。
