Preparation Of Magnetic Transition Metal Catalyst And The Performance Of Heck Reaction

Magnetic nano-catalysts have not only the structures and properties of nanoparticles, but also magnetic. So the catalysts have high catalytic performance, and can be recycled for several times. Noble metal Palladium (Pd) is very expensive, while transition metals are cheap and non-toxic. Therefore, the preparation of highly active catalysts with low cost and green environmental protection, has become a focus and attracted many researchers in this field.The catalysts used in this paper are nanoscale magnetic catalyst; made of Fe3O4 as magnetic core and m-SiO2@SiO2@Fe3O4 as carrier. The use of amino modified silica layer—m-SiO2-NH2@SiO2@Fe3O4 in order to achieve good load of active component, Three kinds of catalyst was successfully achieved:Cu/m-SiO2@SiO2@Fe3O4, Cu-Pd/m-SiO2@SiO2@Fe3O4 and Co-Pd/m-SiO2@SiO2@Fe3O4. The characterization of catalysts was conducted using diffenet analytical methods such as XRD, FT-IR, TEM. This paper has choose the reaction of iodobenzene and methyl acrylate as Heck reaction model to explore the catalytic performance and catalytic reusability of the catalyst. The results are as follows:(1) In this paper, a nanoparticle with uniform size distribution of about 110nm was successfully prepared with good dispersion properties, superparamagnetic Fe3O4 nanoscale spherical particles. Amino modified m-SiO2-NH2@SiO2@Fe3O4 metal loading is more uniform, agglomeration does not occur and the load of Cu metal particles has a diameter of 2-4nm.(2) The catalytic performance of Cu/m-SiO2@SiO2@Fe3O4 is good under the following optimum reaction conditions:the Cu loading was 17.5wt% iodobenzene:methyl acrylate:base is 1:1.5:1.2 (molar ratio), DMF is a solvent, triethylamine as base, conversion of iodobenzene was 55.16% at 140? for 18h. The catalyst had good recovery performance and can be reused for three times.(3) The catalytic performance of Cu-Pd/m-SiO2@SiO2@Fe3O4 is good under the following optimum reaction conditions:the Cu loading was 4wt% when the loading amount of Pd was 0.5wt%, iodobenzene:methyl acrylate: base(molar ratio) is 1:1.5:1.2, DMF as the solvent and triethylamine as base, the conversion rate of iodobenzene was 99.55% at 120? for 3h, and the catalyst can be reused for 5 times.(4) The catalytic performance of Co-Pd/m-SiO2@SiO2@Fe3O4 is good under the optimum conditions:the Co loading was 4wt% when the loading amount of Pd was 0.5wt%, iodobenzene:methyl acrylate:base(molar ratio) is 1:1.5:1.2, triethylamine as base, NMP as solvent, the conversion of the reaction is 99.68% at 120? for 3h. The catalysts can be reused for 5 times.