Publications by authors named "Mikhail Varfolomeev"

Organic rich sedimentary rocks of the Late Cretaceous Muwaqqar Formation from the Lajjun outcrop in the Lajjun Sub-basin, Western Central Jordan were geochemically analyzed. This study integrates kerogen microscopy of the isolated kerogen from 10 oil shale samples with a new finding from unconventional geochemical methods [i.e.

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In this work, a solid-state method for the synthesis of perovskite La(FeCuMnMgTi)O high-entropy oxide (HEO) nanoparticles is detailed. Additionally, the high performance of these nanoparticles as catalysts in the aerobic and solvent-free oxidation of benzyl alcohol is demonstrated. The structural features of HEO nanoparticles are studied by X-ray diffraction and high-resolution transmission electron microscopy.

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In this work, La(FeCuMnMgTi)O HEO nanoparticles with a perovskite-type structure are synthesized and used in the electrocatalytic CO reduction reaction (CORR). The catalyst demonstrates high performance as an electrocatalyst for the CORR, with a Faradaic efficiency (FE) of 92.5% at a current density of 21.

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Hydrogen bonding (HB) is a fascinating phenomenon that exhibits unusual properties in organic and biomolecules. The qualitative manifestation of hydrogen bonds is known in numerous chemical processes. However, quantifying HB strength is a challenging task, especially in the case of intra-molecular hydrogen bonds.

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In this study, Nickel oxide-based catalysts (NiO) were synthesized and used for the in-situ upgrading process of heavy crude oil (viscosity 2157 mPa·s, and API gravity of 14.1° at 25 °C) in aquathermolysis conditions for viscosity reduction and heavy oil recovery. All characterizations of the obtained nanoparticles catalysts (NiO) were performed through Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Atomic Force Microscopy (AFM), X-Ray and Diffraction (XRD), and ASAP 2400 analyzer from Micromeritics (USA), methods.

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The vapor pressures of six solid 5-X-1,10-phenanthrolines (where X = Cl, CH, CN, OCH, NH, NO) were determined in suitable temperature ranges by Knudsen Effusion Mass Loss (KEML). From the temperature dependencies of vapor pressure, the molar sublimation enthalpies, Δ(⟨⟩), were calculated at the corresponding average ⟨⟩ of the explored temperature ranges. Since to the best of our knowledge no thermochemical data seem to be available in the literature regarding these compounds, the Δ(⟨⟩) values obtained by KEML experiments were adjusted to 298.

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The influence of kinetic hydrate inhibitors on the process of natural gas hydrate nucleation was studied using the method of dielectric spectroscopy. The processes of gas hydrate formation and decomposition were monitored using the temperature dependence of the real component of the dielectric constant ε'(T). Analysis of the relaxation times τ and activation energy ΔE of the dielectric relaxation process revealed the inhibitor was involved in hydrogen bonding and the disruption of the local structures of water molecules.

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Heavy oil and vacuum residue were used to obtain road bitumen BND 50/70 using two different methods of steam distillation at 323-362 °C and by oxidation, a method using packed column at temperature of 211-220 °C. The obtained residues using two methods steam distillation and oxidation are known as non-oxidized bitumen and oxidized bitumen, respectively. The products were evaluated using different standards including GOST 33133-2014, GOST 22245-90, and ASTM D5.

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Upgrading of heavy oil in supercritical water (SCW) was analyzed by a comprehensive analysis of GC, GC-MS, NMR, and SEM-EDX with the aid of electron paramagnetic resonance (EPR) as a complementary technical analysis. The significant changes in the physical properties and chemical compositions reveal the effectiveness of heavy oil upgrading by SCW. Especially, changes of intensities of conventional EPR signals from free radicals (FRs) and paramagnetic vanadyl complexes (VO) with SCW treatment were noticed, and they were explained, respectively, to understand sulfur removal mechanism (by FR intensity and environment destruction) and metal removal mechanism (by VO complexes' transformation).

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The design of new dual-function inhibitors simultaneously preventing hydrate formation and corrosion is a relevant issue for the oil and gas industry. The structure-property relationship for a promising class of hybrid inhibitors based on waterborne polyurethanes (WPU) was studied in this work. Variation of diethanolamines differing in the size and branching of -substituents (methyl, -butyl, and -butyl), as well as the amount of these groups, allowed the structure of polymer molecules to be preset during their synthesis.

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Petroleum coke is one of the waste products generated in the oil refining industry that can be used as fuel in energetics. However, the low volatile matter content and graphite-like structure of petroleum coke are the reasons for its high ignition temperature and combustion complexity. In this research, petroleum coke combustion and oxidation kinetics in the presence of metal catalysts were investigated.

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Steam injection is the most widely used technique for effectively reducing the viscosity of heavy oil in heavy oil production, in which in situ upgrading of heavy oil by aquathermolysis plays an important role. Earlier, transition-metal catalysts have been used for improving the efficiency of steam injection by catalytic aquathermolysis and achieving a higher degree of in situ oil upgrading. However, the unclear mechanism of aquathermolysis makes it difficult to choose efficient catalysts for different types of heavy oil.

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In this work sulfonated chitosan (SCS) was introduced as a promising green kinetic methane hydrate and corrosion inhibitor to overcome the incompatibility problem between inhibitors. Evaluation of hydrate inhibition performance of SCS with high-pressure autoclave and micro-differential scanning calorimeter revealed that hydrate formation was delayed 14.3 ± 0.

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A facile, new and promising technique based on waterborne polymers for designing and synthesizing kinetic hydrate inhibitors (KHIs) has been proposed to prevent methane hydrate formation. This topic is challenging subject in flow assurance problems in gas and oilfields. Proposed technique helps to get KHIs with required number and distance of hydrophilic and hydrophobic groups in molecule and good solubility in water.

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Piperidine and N-methylpiperidine hydrates aggregate in liquid aqueous solutions due to hydrogen bonds between hydration water molecules. No such effects occur in the mixtures of the amines with methanol, that supports the idea of active role of water solvent in the aggregation. However, the question of contributions in thermodynamic functions due to specific interactions, van der Waals forces, and the size and shape of the molecules remains open.

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In this work enthalpies of dissolution in water of polyethylene glycols (PEGs) having an average molecular weight of 1000 and 1400, Pluronic-F127, phenacetin as well as the composites prepared from them were measured using solution calorimetry at 298.15 K. Intermolecular interaction energies of polymer-phenacetin were calculated on the basis of an additive scheme.

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In the paper, results of calorimetric measurements, IR spectra, and calculated ab initio stabilization energies of dimers are reported for binary systems butan-2-one + (methanol, ethanol, propan-1-ol, butan-1-ol, and chloroform). Changes in the total enthalpy of specific interactions due to dissolution of butan-2-one in the alcohols, calculated using equations derived in previous works, are positive. That results from the endothermic breaking of the O-H···O-H bonds not completely compensated by the exothermic effects of formation of the O-H···O═C ones.

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Temperature dependence of vapor pressures for 12 dihalogen-substituted benzenes (halogen = F, Cl, Br, I) was studied by the transpiration method, and molar vaporization or sublimation enthalpies were derived. These data together with results available in the literature were collected and checked for internal consistency using structure-property correlations. Gas-phase enthalpies of formation of dihalogen-substituted benzenes were calculated by using quantum-chemical methods.

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Experimental study of hydrogen bond cooperativity in hetero-complexes in the gas phase was carried out by IR-spectroscopy method. Stretching vibration frequencies of O-H groups in phenol and catechol molecules as well as of their complexes with nitriles and ethers were determined in the gas phase using a specially designed cell. O-H groups experimental frequency shifts in the complexes of catechol induced by the formation of intermolecular hydrogen bonds are significantly higher than in the complexes of phenol due to the hydrogen bond cooperativity.

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Methoxyphenols are the structural fragments of different antioxidants and biologically active molecules, which are able to form strong intermolecular and intramolecular hydrogen bonds in condensed matter. In the present work, thermochemical, Fourier transform infrared (FTIR)-spectroscopic and quantum-chemical studies of methoxyphenols and its H-bonded complexes in solution and gas phase have been carried out. Thermodynamic properties (standard molar enthalpies of formation, vapor pressure, vaporization enthalpies, sublimation enthalpies, and fusion enthalpies) of 2-methoxyphenol, 3-methoxyphenol, 4-methoxyphenol, 1,2-dimethoxybenzene, 1,3-dimethoxybenzene, and 1,4-dimethoxybenzene have been studied in this work.

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FTIR spectroscopic study of hydrogen bonding of 1,2-dihydroxybenzene (catechol) with proton acceptors has been carried out. The influence of intramolecular and intermolecular hydrogen bonds on the strengths of each other in complexes of 1,2-dihydroxybenzene with various proton acceptors has been analyzed. It was shown that intramolecular hydrogen bond is strengthened when 1,2-dihydroxybenzene interacts with bases (ethers, amines, nitriles, etc.

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Solvent effects on OH stretching vibrations in several complexes with hydrogen bonding have been investigated by FTIR spectroscopy. To assess the influence of van der Waals (vdW) interactions on frequency shifts, a new parameter of solvent, square root deltacavhS, is proposed. This parameter has been derived from equations describing enthalpy of non-specific solvation.

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