NICKEL-GRAPHENE CATALYST FOR MAGNESIUM HYDROGENATION AND FOR CARBON NANOSTRUCTURES SYNTHESIS

Abstract

The results of obtaining graphene-like nanomaterials (GLM) by reduction of graphite oxide, preparation of nickel-graphene catalysts and formation of carbon-graphene and magnesium-graphene composites are presented. The optimal preparation conditions and the functional characteristics of the obtained materials are determined. The method described in this work makes possible to obtain nickel-graphene composites (Ni/GLM) containing 5–25 wt.% of Ni nanoparticles of size 2–5 nm. Such composites are effective catalysts for the hydrogenation of magnesium. They were used to create hydrogen storage materials on magnesium base with a reversible capacity more 6.5 wt.% of hydrogen. The addition of Ni/GLM promotes an increase in the rate of Mg hydrogenation due to the high catalytic activity of nanoscale Ni in the dissociation of H2 molecules, and the coating of the fine particles of MgH2 with the GLM retains the submicron size of the Mg particles formed during dehydrogenation and ensures high thermal conductivity of the Mg/MgH2 + Ni/GLM composites. It was determined that in MgH2 + Ni/GLM composites, along with the stable α-phase of MgH2, a metastable γ-phase of MgH2 contains, which leads to a decrease in the dehydrogenation temperature by ~ 50 °C. Using Ni/GLM catalysts, carbon nanotubes (CNT) and nanofibers (CNF) on the surface of graphene-like structures were synthesized. The catalytic decomposition of C2H4 on Ni/GLM at temperatures of 500–700 °C leads to the formation of CNF on the surface of the GLM, and the decomposition of CH4 at 900 °C – with the formation of CNT. The CNT and CNF formed have a diameter in the range from 5 to 20 nm, and the length increases from 5 to 300 nm with rise of synthesis duration. Such three-dimensional structures have a high specific surface area and are attractive as sorbents of gases and carriers of metal catalysts.Forcitation:Tarasov B.P., Arbuzov A.A., Volodin A.A., Mozhzhukhin S.A., Klyuev M.V. Nickel-graphene catalyst for magnesium hydrogenation and for carbon nanostructures synthesis. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2017. V. 60. N 8. P. 43-46.