Construction Of Magnetic Noble Metal Nanocatalyst And Its Application In Organic Reaction

In recent years, the interest in catalysis by metal nanoparticles is increasing dramatically because of the high surface area per volume and catalytic activity of metal nanoparticles. However, the nanoparticles are easy to reunite, difficult to separation, short life and thus limits their practical application. Therefore, developing a heterogeneous catalyst system with high dispersion and long life is becoming the research focus in the field. It is worth noting that the surface-functionalized magnetic nanoparticles for immobilizing precious metals is receiving more and more attention. This thesis is mainly divided into the following five parts:(1) Palladium-based catalyst supported on amine-functionalized magnetite nanoparticles was successfully prepared by a facile one-pot template-free method combined with a metal adsorption-reduction procedure. The catalyst was characterized with different technologies. The catalyst afforded fast conversions for various aromatic nitro and unsalurated compounds and with turn-over frequency (TOP) of 83.33 h-1 under H2 atmosphere in ethanol even at room temperature. Furthermore, it was found that the catalyst showed a high activity for the Heck reaction, affording over 93% yield in all the cases investigated. Interestingly, the novel catalyst could be facilely recovered from the reaction mixture and recycled eighth times without significant loss in activity.(2) A novel and high-performance palladium-based catalyst for Heck reaction was prepared easily by the co-precipitation method and it was characterized by a variety of instruments. The catalyst afforded a fast conversion of the 4-bromonitrobenzene to 4-nitrostilbene at a catalyst loading of 5 mol%, and the efficiency of the catalyst remains unaltered even after 6 repeated cycles. The excellent catalytic performance of the Pd/Fe3O4 catalyst might be attributed to the enhanced synergistic effect between Pd nanoparticles and magnetite.(3) A magnetically recoverable palladium catalyst prepared by immobilization of palladium acetate over ligand-modified magnetic nanoparticles and it was tested with a serious of apparatus. The new developed catalyst for oxidation and carbonylative Suzuki coupling reactions and are easily recovered by magnetic separation from the reaction mixture.(4) A facile method is presented for the immobilization of gold nanoparticles on polyethyleneimine functionalized magnetite. The catalyst was characterized with different technologies and investigate its physical and chemical properties. This catalyst afforded a fast conversion of the 4-nitrophenol to 4-aminophenol at the presence of NaBH4, and an excellent yield was still achieved after it was reused ten times.(5) A facile route for ethylenediaminetetraacetic acid (EDTA) immobilization on the surface of polyethylenimine modified Fe3O4 nanoparticles for remediation of heavy metals from aqueous solutions. The different characterization methods prove that the Fe3O4-NH2/PEI-EDTA nano-adsorbent has been prepared successfuly. The research work on the adsorption revealed that the concentration of Pb2+ altered from 10 to 0.12 mg/L and it indicated that 98.8% of Pb2+could be removed from aqueous solutions at pH 5.05, and Fe3O4-NH2/PEI-EDTA loaded heavy metal ions after being treated with 0.1 M HCl could be used as a reusable nano-adsorbent.