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The results of a DFT study of elementary acts, both catalytic transformations of alkanes on hydride-hydroxyl forms of Fe4O7 and NiFe3O7 clusters, and processes of hydrocarbons transformation on iron and nickel-oxide clusters without initially hydride-hydroxyl filling are presented. Homolytic scission of the C–H bonds of alkanes on the hydride-hydroxyl form of the Fe4O7 cluster is accompanied by the formation of alkyl radicals capable of biradicals recombination according to the singlet type. There is also an additional reaction direction, which is represented by a singlet intra-associative rearrangement generating alcohols chemisorbed with the iron atom of the Fe4O6 cluster. This reaction is irreversible, proceeds with a large exothermic effect of 45.90 kcal∙mol-1, sufficient to overcome the chemisorption bond and diffuse into the volume of the supercritical fluid. The calculated characteristics of the interaction of alkanes with an iron-positioned hydroxyl group indicate that the activation energies of the forward direction of elementary acts in the homologous series: primary and secondary C–H bonds, lie in the range of 30.91-32.74 kcal∙mol-1, that is, these reactions are not very selective and strongly endothermic, since the activation energies of the reverse directions of the corresponding elementary acts are in the range of 1.40-3.27 kcal∙mol-1. The transition in the homologous series from the primary and secondary C–H bonds of propane to the tertiary C–H bonds of isobutane significantly changes the activation specificity of the homolytic scission of C–H bonds. The relative activation energy of the forward direction of the reaction decreases by about 8.00 kcal∙mol-1. A reaction system with the participation of the nickel-iron-oxide cluster NiFe3O7 and propane has been studied quantum-chemically. The result of the interaction of these reagents is the formation of isopropyl alcohol (propan-2-ol), which is chemisorbed with the nickel atom of the NiFe3O6 cluster. This reaction is irreversible and proceeds with a large exothermic effect of 50.95 kcal∙mol-1. The energetics of this process qualitatively coincides with the activation characteristics of the second stage of methane transformation on the Fe4O6 cluster; however, in this case, the reaction is a one-stage. It is noted that when carrying out various SCF extraction processes, for example, during the purification and regeneration of nickel and iron oxide catalysts, it should be borne in mind that the use of a propane-butane mixture as a supercritical fluid can be accompanied by its saturation with heavier hydrocarbons of linear and branched structure and alcohols. However, in real technological SCF processes, it is realistic to select the optimal temperature and flow regime that minimizes this effect. In the presence of a pre-reaction complex involving the hydrogen bond of the hydroxyl group of the initial propylene glycol and the interstitial oxygen atom (Fe–O–Fe) of the Fe4O7 cluster, a one-stage reaction with the oxidation product 1-hydroxypropan-2-ol becomes possible. The Fe4O6 iron oxide cluster with four coordinated iron centers having a hydroxyl group bound to each of them interacts with propylene glycol to form 1-hydroxypropan-2-ol, and the Fe–OH and Fe–O–Fe cluster substructures are the oxidative centers. In this case, the product of the reaction is a water molecule chemisorbed on the iron center and a hydrogen atom chemisorbed on the Fe–O–Fe substructure. This reaction is extremely exothermic (Q = 62.55 kcal∙mol-1) and has a very low activation energy for the forward direction of the reaction. By the example of the described heterogeneous hydrate-dissociative effects involving metal oxide surfaces and simple or functionalized alkanes, it can be seen that it is the protonated and hydroxylated forms of metal oxide surfaces that are responsible for elementary acts related to supercritical water oxidation.

The primary oxidation stages of 3O2 model acyclic and cyclic alkanes and their subsequent triplet and singlet elementary events were studied for the first time by the DFT method with the density functional B3LYP and basis set 6-311++g(df,p). According to quantum chemical DFT calculations the C–H radical cleavage of the bonds of acyclic and cyclic alkanes upon interaction with 3O2 is almost completely thermodynamically shifted toward the initial state of the reaction system. This energy of primary oxidizing events explains the extremely low reactivity of saturated alkanes in comparison with asphaltene structural fragments under the conditions of SCF technology for the extraction of heavy oils and asphaltenes by a propane-butane mixture. It has been demonstrated that for all elementary acts of primary alkane oxidation the product of the direct reaction direction is not a free pair of radicals but a triplet hydrogen complex with a pronounced hydrogen bond between the hydroperoxyl radical and the radical form of the corresponding hydrocarbon. A new, previously not taken into account very exothermic (H = -29.25 – -30.77 kcal/mol) reaction direction is described which corresponds to triplet recombination of alkyl radicals and a hydroperoxyl radical in its oxygen-concentrated part. The products of this recombination are triplet forms of alkane hydroperoxides in which there is a fairly loosened triplet O---O bond with a length of 2.20-2.23 Å, which is ~0.72-0.77 Å more than bond length in the singlet state.

—The extraction of oil products from oil sludge with liquid and supercritical fluid processes is studied. The initial oil sludge contains 30, 5.9, and 5.7 wt % of water, mechanical impurities, and asphaltenes, respectively. The extraction, with a 3 : 1 (wt %) mixture of propane and butane at 85–120°C and pressures of 10 and 15 MPa, allows petroleum products to be obtained with significantly low viscosity and low amount of sulfur and water.

The authors present the results of investigation and experimental implementation of several processes: production of heavy oil residue and its deasphaltizing and impregnation of carbonate rock with deasphalted oil. Heavy oil residue has been produced during fractionation of highly-vicious oil by steam-thermal method. Deasphaltizing of oil-residue and impregnation of carbonate rock are implemented with the use of extraction and supercritical fluid impregnation processes with propane-butane solvent.

A comprehensive process for the deasphaltizing of heavy oil residue and subsequent treatment (impregnation using a solvent in the supercritical fluid state) of a carbonate macadam by bituminous compounds (deasphaltizate) is developed. The purpose is to improve the functionality of the material and, above all, to reduce its water absorption capacity. The process parameters are specified based on the newly obtained data on the thermal capacity of heavy oil residue and deasphaltizate. The results of the process of experimental implementation and the characteristics of impregnated macadam, including the water absorption capacity which decreased from 3.6 to 0.54%, are presented.

The investigation on thermodynamic properties (density ρ, viscosity ν) of heavy oil has been carried out in the temperature range 298 - 363 K at pressure 0.098 MPa, and thermal expansion coefficient αp at pressures up to 49 MPa. The results of specific heat measurements of oil and oil products are presented at pressures up to 29 MPa and temperatures up to 613 K for heavy oil and temperature range of 323 - 473 K at atmospheric pressure for oil products. Thermal effects occurring during the processing of crude oil have been investigated. According to the obtained values of thermal expansion coefficients, density of the oil has been calculated for pressures up to 49 MPa.

The steam-thermal method for refinery of highly-viscous oils and the process of propane-butane liquid extraction have been implemented for production of the impregnation material for carbon rock. The process of steam-thermal treatment has been carried out for highly-viscous oil from Ashalchinskoye accumulation with the “steam-oil” ratio changing from 1.1:1 to 1.4:1. The extraction process has been carried out at temperature T = 85°C and pressures from 4.5 to 8 MPa. Water absorption of carbonate rock has decreased to 0.34% as a result of SCF-impregnation process.

An efficient technology of impregnation of carbonate crushed stone by oil-product based on SCF-impregnation process usage with propane/butane solvent was developed. Regular impregnation throughout the volume of crushed stone sample is achieved. As a result of the appliance of proposed technology, the humidity of the treated crushed stone samples decreased down to 0.54%.

The experimental data on supercritical CO2 extraction of microalgae are presented. It is confirmed that microalgae contains omega-3 fatty acid components. Phase equilibria data are presented for the triolein-methanol (T = 413 K, P = 5.8 - 11.9 MPa) and ethyl eicosapentaenoate-carbon dioxide (T = 313 - 333 K, P = 10 - 21 MPa) binary systems. The scheme of the batch-type experimental setup for supercritical transesterification of oils is presented. Temperature and molar ratio dependences of non-refined palm oil yield to fatty acid methyl esters (FAME) are presented for T = 563 - 693 K, methanol to palm oil molar ratio 39:1. Experiments on ultrasonic emulsification of rapeseed oil-ethanol mixture (molar ratios 150:1 - 7:1) were conducted. Research data on ultrasonic emulsion stability are presented for the time range of 0 - 40 minutes after ultrasonication completion. Correlation is defined between FAME yield of emulsified reaction mixtures and the emulsion grain size. FAME yields are compared for emulsified and non-emulsified reaction mixtures.

Raw material Vietnamese green tea leaves were processed by different procedures involving supercritical carbon dioxide flow and periodical decompressions of high pressure CO2, in order to determine their influence on the extraction of active components by water phase during tea brewing. Several thermodynamic characteristics of supercritical fluid CO2 decaffeination of Vietnamese green tea are reported as a function of temperature and pressure. The imbibition of green tea leaves in supercritical CO2 conditions intensifies mass transfer of active components of green tea in water brewing, an optimal combination of degree of tea leaf quality preservation, low prime cost and good profitability.