Nanocomposites and nanomaterials

Technology for obtaining catalysts with magnetic properties based on CuO/SiO2/CoFe2O4 composites
Zhyhailo М.М., Makido O.Yu., Khovanets’ G.I., Khavunko O.Yu.
Department of Physical Chemistry of Fossil Fuels of the Institute of Physical–Organic Chemistry and Coal Chemistry named after L. M. Lytvynenko NAS of Ukraine.
Naukova Str., 3а, Lviv-79060, Ukraine.
E-mail: zhyhailo.mariia@gmail.com

One of the important issues of catalytic chemistry is the problem of preventing of catalysts losses, increasing of their recovery rate and removal from the reaction mixture. Recently, researchers have paid great attention to the use of nanosized magnetic catalysts, which can be easily separated from the reagents by applying an external magnetic field [1, 2].
In this work, pre-obtained CoFe2O4/SiO2 composites with a developed surface and magnetic properties were used as a basis for obtaining nanocatalysts based on copper oxide. CoFe2O4/SiO2 composites were obtained by two-stage technology. The first stage involves simultaneous precipitation of cobalt and iron hydroxides by alkaline hydrolysis of their salts, taken in the ratio of 1:2, respectively. The second stage is the precipitation of SiO2 onto the formed particles at the alkaline sol-gel transition of TEOS. The precipitate was rinsed to pH = 7 and dried at 100 °C. The obtained composite was calcined at 400 °C to convert Fe(OH)3 and Co(OH)2 and the corresponding hydroxooxides to CoFe2O4 complex oxide. At the next stage, copper hydroxide was precipitated onto the surface of the obtained CoFe2O4/SiO2 composites. The precipitation was carried out from a solution of copper acetate with a solution of sodium hydroxide, followed by calcination at a temperature of 200 °C. This technology allows to obtain CuO/SiO2/CoFe2O4 composites, which have a developed surface and preserve magnetic properties of the «core». 
The use of CuO/SiO2/CoFe2O4 composite as a catalyst in the process of cumene oxidation by molecular oxygen allowed to increase the rate of oxidation reaction by 6-8 times. Taking into account the possibility of easy removal of such a catalyst from the reaction medium, composites of this type seem to be promising for this process.

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2.	Shi B.N., Wan J.F., Liu C.T., Yu X.J., Ma F.W. Synthesis of CoFe2O4/MCM-41/TiO2 composite microspheres and its performance in degradation of phenol // Mater Sci Semicond Proces.-2015-37.-P. 241-249.