Home – Home – Jornals – Advanced Search

The behavior of a three-component electrolyte in a microdevice utilizing a spherical ion-selective granule under an applied electric field and a pressure difference is investigated. In practical applications, one of the electrolyte components corresponds to charged analyte particles present at an initially low concentration. It is shown that the analyte concentration can be increased in the wake of the granule, and the degree of concentration enhancement is independent of the initial concentration. The physical mechanism of this phenomenon is described. This paper also presents the parameter values-such as the potential difference, pressure difference, and the characteristics of the electrolyte and the granule-for which this enhancement is achievable.

Changes in the properties of a DC-excited gas-discharge plasma in uniform weak longitudinal magnetic fields are analyzed. The state and behavior of such a system in a weak magnetic field can be studied using the reaction-diffusion equation, which describes the ionization-recombination equilibrium in the plasma, together with modern concepts of ambipolar diffusion. It is shown that, in the presence of an external magnetic field, the transverse diffusion coefficient decreases, the coherence of emerging plasma states in the system is disrupted, noise or turbulence arises in diffusive and stratified regimes (including contracted ones), and the striation period increases. Complete destruction of the spatiotemporal structure of a striation occurs when the magnetic field strength exceeds a critical value. A similar effect is also achieved by increasing the working gas pressure. The presented findings allow all the above-mentioned behavioral features of the ionized gas to be interpreted as different manifestations of an integrated plasma-field system.

The amplification of a shock wave pulse transmitted through a sand layer is investigated as a function of layer thickness. It is shown that, as the sand layer thickness becomes somewhat higher, the amplitude of the probing pulse first increases and then decreases. Pressure peaks form almost simultaneously throughout the entire sand layer.

Integration in Lagrangian variables is performed for a submodel describing steady-state motions of an ideal gas with constant pressure in the flow region. A general solution is obtained for the invariant submodel of steady-state rotational isobaric motions. Examples of helical gas motions with constant pressure are considered.

The catalytic oxidation and extraction of sulphur-containing compounds of the diesel fraction by metal-containing ionic liquids based on imidazolium bromide (IL) and metal salts (FeCl₃, SnCl₄, ZnCl₂, СоС1₂, МnС1₂) have been investigated. The composition of sulphur-containing compounds and polycyclic aromatic hydrocarbons in the initial and purified diesel fraction was determined by gas chromatography - mass spectrometry. The optimal conditions for oxidation and extraction have been determined: temperature 30 °C, extraction time 60 min, the molar ratio IL / metal salt = 1 : 0.25. A higher degree of sulphur-containing compounds removal (80-95 %) is observed in the systems ILFeCl₃, ILSnCl₄, ILZnCl₂. Results of the studies of group and individual composition of dibenzothiophene derivatives have shown that in terms of recovery degree the homologues are ranged as follows: dibenzothiophene > trimethyldibenzothiophene > methyldibenzothiophene > dimethyldibenzothiophene. The efficiency of extraction of naphthalene and phenanthrene homologues is 75-80 %.

Results of studies on the activity and stability of Mo/ZSM-5 catalysts with a hierarchical pore system in the process of non-oxidative conversion of methane into aromatic hydrocarbons are presented. ZSM-5 zeolites were synthesised by hydrothermal synthesis with the addition of different amounts of polyaniline (3 %, 6 % and 12 %) as the second structure-forming agent (template), along with hexamethylenediamine (HMDA). The Mo/ZSM-5 catalysts were prepared from the zeolites and nano-sized Mo powder by solid-phase synthesis. According to IR spectroscopic data, all the synthesised zeolites belong to the ZSM-5 type and have 100 % crystallinity. It is shown that the addition of the second template (polyaniline) at synthesis stage improves the textural characteristics of the zeolite: increased specific surface area and mesopore volume, with an insignificant change of micropore volume, in comparison with ZSM-5 synthesised using only HMDA. With an increase in the amount of polyaniline added at the synthesis stage, the average pore size in the zeolite is observed to increase to 3.1 nm. The addition of polyaniline also causes changes in their acidic properties. The strength and concentration of strong acid centres of zeolite, related to Brønsted acid centres, are observed to decrease, which is probably due to changes in the distribution of Al atoms in zeolite structure and, as a consequence, to the redistribution of Brønsted and Lewis acidity. Non-oxidative methane conversion was carried out at a temperature of 750 °C and atmospheric pressure in a quartz reactor with a fixed catalyst bed. Catalytic tests have shown that the addition of polyaniline leads to the production of samples characterised by higher activity and selectivity for benzene formation. The best activity and stability are observed for Mo/ZSM-5 catalyst based on the zeolite synthesised with the addition of 6 % polyaniline, methane conversion was 11.5 %, and benzene yield was 6.7 %.

The distribution patterns of saturated and aromatic hydrocarbons in sod-podzolic soils one year after an accidental oil spill at an oil field in the Nefteyugansk district of the Khanty-Mansi Autonomous Okrug are considered. Soil samples were collected from the depth of 0-10, 10-30, and 30-50 cm. The composition and distribution of hydrocarbons were determined using gas chromatography-mass spectrometry. The total pollutant content was found to be unevenly distributed: the highest concentrations are confined to the surface layer, while the minimum values are characteristic of the middle interval (10-30 cm). In all horizons, n-alkanes account for the majority of the contamination, while isoprenoid alkanes and polycyclic aromatic compounds are present in smaller quantities. It has been shown that in the intermediate (10-30 cm) layer, the ratio of individual aromatic compounds changes: in particular, the contribution of methyl-substituted naphthalene homologues decreases and the relative content of phenanthrene homologues increases. Predominance of high-molecular-weight odd n-alkanes, characteristic of biogenic soil organic matter, was also recorded in this layer. Individual n-alkanes include homologues from C₁₃ to C₃₅. It has been found that the average number of carbon atoms in homologous series for compounds with long alkyl chains increases for most groups of compounds when moving from oil to soil.

A comparative study of the composition of the supramolecular and molecular structure of resin-asphaltene components isolated from the light oil of the Krapivinskoye field and heavy oil of the Usinsk field and the residues after their atmospheric distillation has been carried out. Using a set of methods - scanning and transmission electron microscopy, X-ray diffraction and structural group analysis - the features of the surface morphology of asphaltenes and their nano- and microstructure, as well as the features of the structural organisation of oil resins before and after their primary processing were revealed. It has been established that asphaltenes and resins of heavy oil undergo more pronounced structural transformations. The results obtained expand the understanding of the behaviour of high-molecular oil components under thermal action and can be used to optimise technologies for processing residual fractions and predict their operational properties.

Results of the synthesis of binary systems and ternary system of deep eutectic solvents (DESs) based on glycerol, choline chloride and urea are presented, along with the studies of their physicochemical and rheological properties, including the properties of their aqueous solutions. Based on the conducted studies involving the addition of a complex surfactant to DES, a new neutral-alkaline oil-displacing composition was developed. The results of laboratory tests aimed at studying the effect of the developed composition on the filtration characteristics of the heterogeneous formation of the Usinskoye field, as well as on the composition and properties of oil itself, are presented. The neutral-alkaline oil-displacing composition is applicable to various geological and physical conditions, in particular in the northern and Arctic regions. The effectiveness of the composition was evaluated under natural, steam-thermal, and steam-cyclic development conditions. Its use was found to smooth out filtration flows, increase reservoir sweep efficiency, restore permeability, and, as a consequence, increase oil displacement efficiency significantly over a wide temperature range. Analysis of the composition and properties of heavy, high-viscosity oil using IR spectroscopy and chromatography - mass spectrometry has shown that the developed composition alters oil characteristics by breaking the bridges linking saturated hydrocarbons with the esters/acids of resinous components. This leads to an increase in the proportion of oil fractions, with a simultaneous reduction of resin content, resulting in lower viscosity and improved oil quality.

The West Siberian oil and gas basin has large reserves of hard-to-recover oil from low-permeability reservoirs. The share of such reserves is more than 80 %, but less than 17 % is currently under development. Statistical analysis of the physicochemical properties and occurrence conditions has been carried out for hard-to-recover Western Siberian oils from deposits characterised by low permeability, the development of which will increase oil production in the region. A set including 1970 oil samples from 488 oilfields of the West Siberian oil and gas basin, taken from the database of the Institute of Petroleum Chemistry SB RAS, was used for analysis. The distribution of oilfields with low-permeability reservoirs in the basin is revealed, and the typification of oilfields with the reservoirs differing in permeability and porosity of rocks is presented. The lithological and stratigraphic distribution of low-permeable deposits of various types is shown. The features of physicochemical characteristics of oils and occurrence conditions have been revealed.