Specific Features of the In Situ Formation of an Unsupported NiWS Nanosize Catalyst from Oil-Soluble Precursors

This paper describes the specific features of the formation of an unsupported nickel-tungsten sulfide nanosize catalyst in situ in a hydrocarbon feedstock from oil-soluble precursors-nickel and tungsten compounds in the presence of elemental sulfur additive. The catalysts formed at different times of the catalytic experiment (2, 5, 7 and 10 h) were analyzed by transmission electron microscopy and X-ray photoelectron spectroscopy. According to STEM-EDX elemental spectra, the formation of tungsten and nickel sulfides was established, with a further increase in the amount of active Ni-W-S phase on the surface of the crystalline nickel sulfide. It was found that the time of catalyst formation affects its morphology and phase composition. Evaluation of the hydrogenating catalytic activity confirms that an increase in the time of catalyst formation leads to an increase in its activity, which is associated with the peculiarities of the morphology of sulfide particle aggregates as well as an increase in the degree of promotion of tungsten disulfide crystallites by nickel atoms.