Preparation Of Magnetic Core-shell Nanocatalyst And Its Application In Organic Reaction

As the normal catalyst is difficult to be separated from the reaction system, which will limit the recycling of the catalyst, this thesis adopt the method of introducing magnetic into the carrier of catalyst to synthetize the magnetic carrier loaded active site catalysts. Moreover, we also study the catalytic activities of catalysts in different organic reactions and the capability of separation and recycling. The main content of this thesis is as follows:(1) Firstly, we synthesized mesoporous silica nanospheres which coated on Fe3O4magnetic nanoparticles by using CTAB as template and TEOS as silicon source. Secondly, the silica nanospheres was amino functional by linking (3-aminopropyl)triethoxysilane with mesoporous silica nanospheres. Finally, cobalt acetylacetonate was immobilized on the carrier by forming schiff base to prepare the catalyst. After the structural characterization of TEM, FT-IR, VSM, XRD and N2adsorption-desorption, the catalyst was tested in the reaction of oxidation of cyclohexane. The catalyst showed good catalytic activity. Under the reaction conditions:140℃and1.0MPa, the conversion was8.4%and the selectivity was85%. After the reaction, the catalyst could be quickly recovered from the reaction mixture in the presence of an external magneticforce. Moreover, the catalyst did not show any significant loss in activity in the cyclic tests.(2) The Fe3O4particle was coated with a shell of polyaniline which was synthesized by in-situ polymerization of aniline on the surface of magnetic-particle. Then, the active component Pd2+was immobilized on the surface of the carrier through the coordinatebond. After the structural characterization of TEM, FT-IR, VSM, XRD and XPS, the catalyst was tested in the reaction of carbonylative Suzuki coupling reactions. The catalyst showed good catalytic activity. Under the reaction conditions:80℃, anisole as solvent and K2CO3as inorganic base, all the reactions afforded over87%yield and it could selectively reduce the formation of direct-coupling product. The main reason for the above phenomena was that there existed π-π conjugation between the PANI shell and aromatic substrate. The separation of the catalyst was very simple and the catalyst was recycled five times without any significant loss in activity.