Mesoporous Silica Supported Pd, Rh Organometallic Catalyst Preparation And Its Catalytic Reaction

The development of immobilization of homogeneous catalyst has obtained great achievements, in which does not only overcome the problem of catalyst separation and efficient recycling but also solve the problems of minimal product contamination from metal leaching. Especially, microwave-assisted catalysis as a non-convenient method can accelerate transition-metal-catalyzed reactions while catalytic processes in aqueous medium can meet the need of green processes, showing the potential application in industry. Mesoporous materials have high surface area, regular and adjustable pores structure that do not allow the aggregation of active catalysts and can keep excellent catalytic performance as homogeneous catalysts. Furthermore, they are modified easily via surface functionalization due to abundant silicon-hydroxyl groups. Besides, they also have a facile preparation, remarkable thermal and mechanical stability. These features demonstrate that mesoporous materials may be potentially ideal catalyst supports. In this thesis, two kinds of mesoporous silica-supported catalysts are developed and their catalytic properties are discussed in detail.In the first part, a mesoporous silica-supported Pd catalyst Me-Pd-IMI-SBA-15 with ordered two-dimensional hexagonal mesostructure was prepared through complexation of Pd(OAc)2 with a mesoporous imidazole-functionalized SBA-15 materials (IMI-SBA-15) that synthesized by a co-condensation approach. During the Suzuki–Miyaura cross-coupling reaction of phenylboronic acid with aryl halides under microwave irradiation, the catalyst Me-Pd-IMI-SBA-15 exhibited excellent catalytic activity. Such catalyst could be recovered easily and used repetitively ten times without significantly affecting its catalytic activity. In the second part, a kind of heterogeneous chiral mesoporous catalyst with ordered mesostructure was prepared through entrapment of the organometallic complex Cp*Rh-Ts-DPEN within a mesoporous cage SBA-16. During the asymmetric transfer hydrogenation of aromatic ketones in aqueous medium, the catalyst exhibited excellent catalytic activity and enantioselectivity. Such catalyst could be recovered easily and used repetitively ten times without significantly affecting its catalytic activity and enantioselectivity.