The transformations of oil components from the Zyuzeevskoye field during catalytic aquathermolysis in the presence of a nickel-containing catalyst precursor and hydrogen donors were studied. It was found that the yield of gasoline and diesel fractions increased by more than 36% in the case of catalytic aquathermolysis in the presence of tetralin. The maximum conversion of asphaltenes was achieved with a simultaneous slowing down of coke formation by four times. The calculation of the structural-group parameters of initial asphaltenes and the products of thermal cracking and catalytic aquathermolysis was made, and the hypothetical construction of their molecular structures was proposed. It was established that the phase composition, ratio, and morphology of nickel catalysts after catalytic aquathermolysis (CA) and catalytic aquathermolysis with tetralin (CA+T) depend on the amount of “free” hydrogen and are represented by Ni_0.96S and Ni₉S₈.

Heavy oils are characterized by a high content of resins and asphaltenes, which complicates refining and leads to an increase in the cost of refinery products. These components can be strongly adsorbed on the acid sites of a supported catalyst, leading to its deactivation. Currently, various salts of group 8 metals are being considered for such processes to act as catalysts during oil cracking. At the same time, the nature of the precursor often has a significant impact on the process of refining heavy oil. In this work, catalytic cracking of heavy oil from the Ashalchinskoye field using different precursors (nanodispersed catalysts formed in situ based on NiO) has been studied. The cracking was carried out at 450 °C with a catalyst content from 0.1 to 0.5 wt.%. The catalytic cracking products were analyzed via SARA, GC, XRD and SEM. Nickel acetate and nitrate promote similar yields of by-products, while formate promotes higher yields of gaseous products. Formate and nickel acetate were shown to produce 1.8 and 2.8 wt.% more light fractions than nickel nitrate. When heavy oil is cracked in the presence of Ni(NO₃)₂∙6H₂O, the maximum decrease in sulfur content (2.12 wt.%) is observed compared to other precursors. It has been found that the composition and morphology of the resulting nickel sulfides and compaction products are influenced by the nature of the catalyst precursor. XRD and SEM analyses of coke-containing catalysts indicate the formation of Ni₉S₈ and Ni_0.96S phases during cracking when nickel nitrate is used and the formation of NiS and Ni₉S₈ when nickel acetate and formate are used.

An approach including preliminary oxidation of vacuum gas oil, chromatographic separation of oxidation products, and thermal treatment is considered. Analysis of the products formed in the cracking of polar and non-polar components of vacuum gas oil oxidised with a mixture of hydrogen peroxide and formic acid is described. It has been established that heat treatment of non-polar components allows obtaining up to 85 wt% distillate fractions boiling up to 360 °C, with sulphur content less than 0.3 wt%. The heat treatment of polar components leads to the formation of distillate fractions at a level of about 50 wt%, and sulphur removal reaches 50 %. It has been shown that the cracking temperature of polar oxidation products determines the route of sulphur removal: at a temperature of 450 °C, sulphur-containing fragments are accumulated in coke, while at 500 °C they are predominantly subjected to destruction with the formation of gas components. It has been determined that gaseous products formed in the heat treatment of both polar and non-polar components of oxidised vacuum gas oil mainly consist of saturated hydrocarbons of the C1-C3 series and carbon dioxide. The advantage of separate cracking of polar and non-polar components is elimination of undesired effect on the products formed in thermal decomposition of these components on the route of reactions proceeding in the system. The products obtained in this way are characterized by higher quality. In addition, variation of cracking conditions for separate components of oxidized vacuum gas oil makes it possible to regulate the depth of components destruction and, accordingly, the material balance of the process as a whole.