Among the known synthesis procedures and reagents for unsupported Ni–Mo–W catalysts, there is no consensus about optimal preparation conditions of their precursors. In the present work, Ni–Mo–W precursors were prepared via three preparation techniques—hydrothermal synthesis, precipitation method and spray drying—after the synthesis of complex compounds in solution. Ni–Mo–W precursors were studied by the XRD analysis, SEM methods, Raman and UV-vis spectroscopies and XPS measurements and used for the hydrotreatment of straight-run gasoil. Precursors prepared by hydrothermal synthesis contain particles with stacked plate shapes, while other methods provide spherical particles. The formation of different amounts of individual molybdates, tungstates or mixed phases such as W_1−xMo_xO₃ possibly doped by Ni was detected. The precipitation technique results in the formation of spheres, with W located at the center and is unavailable for catalysis. The catalytic activity increased when all active metals are available for the feedstock, and a more mixed phase containing Ni, Mo and W is formed. This mixed phase is realized when the synthesis of the Ni–Mo–W precursors is carried out in solution followed by spray drying. The resulting catalyst has 1.2–4 times higher activity than catalysts prepared by other methods.

Hydrotreating is one of the largest processes used in a refinery to improve the quality of oil products. The great demand of the present is to develop more active catalysts which could improve the energy efficiency of the process when it is necessary for heavier feedstock to be processed. Unsupported catalysts could solve this problem, because they contain the greatest amount of sulfide active sites, which significantly increase catalysts’ activity. Unfortunately, most of the information on the preparation and properties of unsupported catalysts is devoted to powder systems, while industrial plants require granular catalysts. Therefore, the present work describes a method for the preparation of granular Ni—Mo—W unsupported hydrotreating catalysts and studies the influence of the Ni/Mo/W atomic ratio on their properties. Catalysts have been prepared by plasticizing Ni—Mo—W precursor with aluminum hydroxide followed by granulation and drying stages. Ni—Mo—W precursor and granular catalysts were studied by X-ray diffraction (XRD), nitrogen adsorption–desorption method, high-resolution transmission electron microscopy (HRTEM), and thermal analysis. Granular catalysts were sulfided through a liquid-phase sulfidation procedure and tested in hydrotreating of straight-run vacuum gasoil. It was shown that the Ni/Mo/W atomic ratio influenced the formation and composition of active compounds and had almost no influence on the textural properties of catalysts. The best hydrodesulfurization (HDS) activity was obtained for the catalyst with Ni/Mo/W ratio—1/0.15/0.85, while hydrodenitrogenation (HDN) activity of the catalysts is very similar.

This review considers and systematizes the results of studying the deactivation of hydrotreatment catalysts currently available in the scientific and technical literature. The effect the composition of the feedstock and the conditions of hydrotreatment have on the coking of catalysts is shown. The reasons for the morphological changes of the active component and the possibility of reducing this type of catalyst deactivation during commercial operation are considered. The effect of a pressure drop on the run time, the action of catalyst poisons, and the ways, in which they enters the hydrotreatment distillates is shown. This information could be useful and interesting to chemical engineers studying catalytic systems, and to workers of oil refining industry.

Problems related to granular catalysts testing in hydrotreatment of petroleum distillates in laboratory are discussed. Requirements for laboratory facilities that ensure high reliability in determining the performance of diesel fraction hydrotreatment in industrial reactors are formulated. It is shown that diluting catalyst pellets with small particles of inert nonporous material (silicon carbide) allows us to obtain reproducible results in small three-phase reactors, minimizing such factors as the incomplete wetting of the catalyst, the wall effect, and the back-mixing of liquids. Laboratory facilities and analysis techniques are described, and results obtained at different laboratories in studying catalysts for the deep hydrotreatment of diesel fractions are compared.

Intrinsic catalytic properties of mineral matrices of various kinds (basalts, clays, sandstones) were studied, which are of interest for in-situ heavy oil upgrading (i.e., underground) to create advanced technologies for enhanced oil recovery. The elemental, surface and phase composition and matrix particle morphology, surface and acidic properties were studied using elemental analysis, X-ray diffraction, adsorption and desorption of nitrogen and ammonia. The data on the catalytic activity of inorganic matrices in ammonium nitrate decomposition (reaction with a large gassing), oxidation of hydrocarbons and carbon monoxide, and hydrocracking of asphaltenes into maltenes (the conversion of heavy hydrocarbons into more valuable light hydrocarbons) were discussed. In order to check their applicability for the asphaltenes hydrocracking catalytic systems development, basalt and clay matrices were used as supports for iron/basalt, nickel/basalt and iron/clay catalysts. The catalytic activity of the matrices in the reactions of the decomposition of ammonium nitrate, oxidation of hydrocarbons and carbon monoxide, and hydrocracking of asphaltens was observed for the first time.