Fabrication Of High Magnetic Catalyst Support With Core-Shell Structure

Aporous high-magnetic particle was prepared in this work, which can be used ascatalytic carrier in the magnetically stabilized bed reactor. These magnetic particleshave a core-shell-γ-Fe₂O₃/SiO₂/TiO₂ structure. The micrometer-γ-Fe₂O₃ magneticparticles were adopted as core, and the dense SiO₂layer was then coated in order toeliminate the negetive effect of Fe element on acetylene selective hydrogenation. Atlast, the TiO₂ layer, as a popular support of Pd metals, was loaded on the outside.Besides, the SiO₂ layer also can be a support for loading metals.In this paper, modified Stober method was used to coat SiO₂ layer onγ-Fe₂O₃core, which followed by the sol-gel method to coat the TiO₂ layer on the layer of SiO₂.The amount of raw materials, baking temperature, reactive temperature, surface-activeagents on the effects of coating were investigated and the best reaction conditionswere determined. XRD is used to analyse the crystal form of the composite particles.TG-DTA method is used to determine the calcining temperature. the VSM is used toanalyse the saturation magnetization of the composite particle. The concentratedhydrochloric acid treatment is used to test the coating density. XPS, EDS were used tocharacter the composition of the elements both in surface and body. The surface areaand pore size were characterized by BETanalysis.The results show that core-shellγ-Fe₂O₃/SiO₂/TiO₂ composite particles with ahigh saturation magnetization and high-coated rate can be got by controlling theprocess conditions. And its magnetism, coating density, surface area and pore size areup to the request of the catalyst support for the magneticallystabilized bedreactor.