Preparation And Reaction Properties Of Magnetic Catalysts With Core-Shell Structure

Magnetic nanoparticle catalysts with core-shell structures have two features. On the one hand, nanoparticle material has the characteristic of high specific surface area, On the other hand, ultrafine magnetic crystals have super paramagnetism which has made contribution to the adsorption and catalytic process. So magnetic nanoparticle catalysts can be attracted easily by external magnetic field separation, separated quickly and recycled. It makes the research and application of super paramagnetic material and magnetic separation technology develop rapidly.In this thesis, we select Fe3O4 nanoparticles as the kernel of core-shell structure and C@ Fe3O4 carrier with core-shell structure was prepared and coated with carbonation of the organic matters. Then I load the precious metal Pd, non-precious metal (Cu, Ni) and bimetallic (Pd/Cu, Pd/Ni) on the C@ Fe3O4 carrier. The main research work illustrated as follows:We use FeCl3·6H2O as raw materials to prepare Fe3O4 magnetic nanoparticles by solvothermal synthesis, and use soluble starch as carbon source to coat a layer of carbon on the magnetic Fe3O4 nanoparticles by hydrothermal method, then, load metal components on it by reducing with Sodium borohydride. Through the above steps, M-C@Fe3O4 magnetic nanoparticles catalyst was prepared. According to Heck reaction performance characterization, the catalyst has good physical and chemical properties:Pd/C@Fe3O4, Cu/Pd/C@Fe3O4、Ni/Pd/C@Fe3O4、 Cu/C@Fe3O4 Ni/C@Fe3O4 magnetic nanometer catalyst shows different catalytic activity in changing the catalyst quantity, reaction temperature, reaction time and the active component percentage, In the reaction with Pd/C@Fe3O4, the conversion and selectivity reach 100% within 3 hour, because of the precious metal Pd. Cu/Pd/C@Fe3O4、Ni/Pd/C@Fe3O4 shows good catalytic activity with low content of Pd. These 3 magnetic nanometer catalysts can keep high conversion and selectivity after repeatedly used 6 times.Cu/C@Fe3O4 Ni/C@Fe3O4 also has catalytic activity, but it decreased after repeatedly used 4 times.