The Preparation Of Magnetic Nano-Catalysts And Their Application In Suzuki Reaction

As one kind of new nano-catalyst, magnetic nano-catalyst has high catalytic activity and favorable magnetic recovery,which can have wide application prospects in organic synthesis catalysis, photocatalysis, biocatalysis. Now a days, because of the good chemical stability, high dispersibility, uniform particle size and surface properties,the magnatic core/shell nano-composite which composed by Fe3O4core and inorganic shell has become a desirable catalysts carrier to make nagnetic nano-catalysts.In this paper, we make the core/shell nano-catalyst as our object of study, make some research about its preparation and its catalytic performance in the Suzuki reaction.The Fe3O4nanoparticle was prepared by modified solvothermal synthesis, and then we make a SiO2shell on the surface of Fe3O4nanoparticle. That is the magnetic SiO2@Fe3O4core/shell nanoparticle. Through different reduction methods, we load a series of different bimetallic active component. The catalysts were analyzed and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM),vibrating sample magnetometer (VSM), N2adsorption-desorption and plasma coupled spectrometer (ICP) and other characterization methods. The catalytic performance in the Heck reaction is investigated, the main research work illustrated as follows:1, The Fe3O4nanoparticles were prepared by modified solvothermal synthesis, then use TEOS as silicon source, prepare a SiO2shell on the surface of Fe3O4nanoparticles by ultrasonic assisted method, to get the monodispersed magneticSiO2@Fe3O4nanoparticles. The SiO2shell of the nanoparticles showed abundant wormlike poers on it, and the magnetic SiO2@Fe3O4nanoparticles have great monodispersity and good shape.On the other hand, the Fe3O4nanoparticles prepared by PVP method showed better performance than the Fe3O4nanoparticles prepared by the sodium acrylate method.2, Make the metal ions loaded on the magnetic SiO2@Fe3O4nanoparticles, and then restore these ions by sodium borohydride, hydrazine hydrate or hydrogen, so that we can get the magnetic Pd/SiO2@Fe3O4nano-catalyst and the magnetic M-Pd/SiO2@Fe3O4nano-catalyst. The catalytic performance in the Suzuki reaction was characterized, and the result showed that the magnetic Pd/SiO2@Fe3O4nano-catalyst prepared by H2has the best catalytic performance in Suzuki reactions. In the magnetic M-Pd/SiO2@Fe3O4nano-catalysts, when Ni:Pd =4:1, the nano-catalyst showed the best catalytic performance.After recycled for5times, the conversion of bromobenzene was above80%.