## 2 Materials and Methods  
Among of the main factors affecting hydrogenation of hydrocarbon feedstocks is the nature of the catalyst. Optimal catalyst compositions would allow the process to be carried out under milder conditions and improve the organic conversion of the feedstock and the desired products' quality. Classic catalysts for hydrogenation processes for processing hydrocarbons are made on the basis of nickel and cobalt salts [15; 16]. This study proposed a binary composition of the hydrogenation catalyst based on Co and Ni, where the silicate chrysotile-asbestos was used as the support. The support has a developed specific surface area: it consists of the thinnest flexible fibers and has a porous structure--this allows it to adsorb and tightly hold atoms inside the pores, and provides high activity in hydrogenation reactions. The catalyst was prepared as follows: the support was impregnated with solutions of active metal chlorides. The salts were prepared by dissolving metal oxides in various concentrations of hydrochloric acid (0.2 M, 0.6 M, and 1 M). Metal oxides dissolve well in hydrochloric acid. The resulting solutions of CoCl\({}_{3}\) and NiCl\({}_{2}\) salts were then impregnated with chrysotile. The mixture was heated in a water bath for 2 h and then washed with water until neutral. The separated precipitate was dried in a drying oven at 105 \({}^{\circ}\)C and then calcined in a muffle furnace at 600 \({}^{\circ}\)C for 60 min. During the treatment of the support with acid, magnesium was washed out (to replace it with metals) and washed from various impurities, which positively affects the activity of the catalyst. Previously, ref. [17] showed the preparation of a nanocatalyst by depositing solutions of cobalt nitrate and nickel nitrate on chrysotile. In this work, metals were simultaneously applied to the surface of chrysotile and magnesium leaching from chrysotile, while in the previous paper [17] the process of obtaining a nanocatalyst was carried out in two stages: in the first stage, magnesium was leached from chrysotile; in the second stage, metal salt solutions were applied on the chrysotile's surface. Photospectrometric examination of the filtrate showed almost complete adsorption of metals on the support surface, 83-89%. Salts of Co and Ni applied on the silicate chrysotile-absestos were used as a catalytic additive. The procedure for preparation and characteristics of the catalysts are given in ref. [17]. The catalysts thus prepared contain metals dispersed on the support surface in the form of small crystals of various sizes which are very stable and have high activity. Catalysts were tested in the hydrogenation reaction of a heteroaromatic compound (benzothiophene), modeling the composition of a heavy hydrocarbon feedstock. The number of elements on the nanocatalyst surface was determined by X-ray fluorescence analysis obtained in air at 600 \(\mu\)A in a FOKUS-2M spectrometer equipped with a molybdenum anode X-ray tube at 30 kV. The results of the elemental chemical composition of the nanocatalyst are presented in Table 1.  
The use of the X-ray fluorescence analysis method to quantify metals in a nanocatalyst showed that the concentration of metals in the sample was set only locally, not in the whole sample. This is due to the fact that the electron beam does not capture the entire area of the sample. Therefore, to determine the quantitative composition of metals, we used the method of atomic emission spectroscopy. The composition of nickel, cobalt, and silicon oxide was determined on a Profile Plus inductively coupled plasma atomic emission spectrometer at a temperature of 21 \({}^{\circ}\)C and an atmospheric pressure of 727 mmHg. The quantitative composition of nickel and cobalt in the NiCo/chrysotile nanocatalyst is shown in Table 2.  
Micrographs of the surface morphology of leached chrysotile nanotubes and nickel and the cobalt-supported nanocatalyst were obtained using a scanning electron microscope MIRA3 TESCAN.