Home – Home – Jornals – Chemistry for Sustainable Development 2020 number 3

In solving the ecological problems caused by the contamination of the Arctic shelf with oil products, the application of satellite images is relevant. These images allow monitoring observations of the state of oil-producing territories and timely revelation and evaluation of the risks of oil pollution in hard-to-reach and fragile tundra and marine ecosystems. On the basis of remote and land-based imaging data, the zones under the risk of oil pollution were mapped over the territory of the Kolguyev island. The ecological state of soils and coastal waters of the island are considered. A technology for the purification of oil-polluted regions with the application of aboriginal psychrophilic microflora stimulated by nutritive mineral substrates is proposed.

Rhenium containing catalysts are prepared on the basis of high-silica zeolite of pentasil family with a silicate modulus 40. Modification of the zeolite with rhenium introduced using various methods results in the changes in its structural characteristics: a decrease in specific surface area, pore volume and diameter. The most noticeable decrease in these parameters is observed when impregnation and ion exchange are used. The use of rhenium-containing zeolite catalysts for upgrading the straight-run gasoline fraction of oil allows increasing the yield of liquid products - high-octane gasolines characterised by a low content of aromatic hydrocarbons and a high octane number. A decrease in the aromatizing activity of Re-containing catalysts contributes not only to improvements in the environmental characteristics of resulting gasolines but also into an increase in the time of the stable operation of catalysts. Due to an increase in the rate of hydrogenation, the introduction of rhenium significantly reduces the amount of coke deposits formed on the catalysts under study during the process. According to the rate of formation of coke deposits, Re/MFI catalysts prepared using different methods are ranked as follows: ion exchange < ultrafine powder < impregnation < mixing with salt < MFI. Carbon densification products formed on rhenium-containing catalysts are less condensed and more homogeneous than coke obtained on unmodified zeolites. According to the degree of decrease in catalytic activity or aromatizing ability during the same time of operation, the catalysts under study may be ranked as follows: MFI > Re/MFI (ion exchange) > Re/MFI (ultrafine powder) > Re/MFI (impregnation) > Re/MFI (mixing with salt).

The laws governing the conversion of components of natural and associated petroleum gases into aromatic hydrocarbons over zeolite catalysts modified with active metal additives are investigated. According to the data obtained, the catalysts under study exhibit high activity in the course of the aromatization of lower C2-C4 alkanes. For almost complete conversion of the feedstock, the selectivity towards the formation of aromatic hydrocarbons over Ga-AC and Zn-ZSM-5 samples at 550 °C is 44.6 and 37.8 %, respectively. The highest catalytic activity and selectivity in the conversion of natural gas into aromatic hydrocarbons is exhibited by Zn-containing zeolites. The yield of aromatic hydrocarbons over them reaches 26.7 % at 650 °C. This is higher by 9.0 and 19.0 % than the yield over Ga-containing and unmodified zeolites, respectively. The revealed differences in the behaviour of the catalysts are due to various functional features of their active sites formed when metals are introduced into the zeolite matrix. The yield of aromatic hydrocarbons from the conversion of a mixture of C2-C4 alkanes over zeolite-containing catalysts is significantly higher than that in the case of natural gas conversion, which is due to the high thermodynamic stability of its major component - methane. The nature of coke deposits formed on the surface of the catalysts under study during the aromatization of low-molecular C2-C4 paraffins was studied by means of differential thermal analysis. The stability of Zn-ZSM-5 in this process was determined to be higher than that of the Ga-containing zeolite.

The composition and structure of nitrogenous bases of the resins of bituminous oil from the Ashalchinskoye deposit of Tatarstan are investigated using a complex of analytical methods including elemental and functional analyses, determination of molecular masses, 1H NMR spectroscopy, structural group analysis, gas chromatography, and mass spectrometry. The nitrogen bases of the resins in oil are analysed before and after their thermal treatment at 450 °C for 30 min in the inert medium. It is established that the nitrogenous bases of the initial resins and "secondary" maltenes are represented by high and low molecular weight compounds. High molecular weight bases prevail in both cases, though their proportion in "secondary" maltenes is much lower. Thermally transformed bases are characterised by lower average molecular weights. This is due to the destruction of alkyl and naphthenic moieties proceeding in the course of thermolysis and resulting in the changes in their structure and the formation of lower molecular weight compounds. As revealed by means of structural group analysis, the mean molecules of a significant part of high molecular weight bases of the "secondary" maltenes are more aromatic due to a decrease in the number of naphthenic cycles and in the number of paraffin carbon atoms in their structural blocks. Low molecular weight bases differ from those of the initial resins in a higher number of naphthenic cycles in the structural blocks of their mean molecules. Alkyl-substituted quinolines and benzoquinolines, naphthoquinolines, naphtho[2,1,8-def]quinolines, thiophenoquinolines, and benzothiophenoquinolines have been identified among the major compounds of initial resins and "secondary" maltenes. The maximum in their distribution falls on alkylbenzoquinolines. The bases of "secondary" maltenes are characterized by a higher relative content of alkylquinolines and alkylthiophenoquinolines. A distinctive feature of the bases of "secondary" maltenes is also an increased proportion of structures with a lower number of carbon atoms in alkyl substituents.

The ability of heavy oil asphaltenes and oil residues to generate low and high molecular weight components during thermolysis at 290 °C is assessed. It was established that the conversion of asphaltenes exceeds 99 mass %, regardless of the degree of their transformation during the rectification of heavy oil. Oil asphaltenes generate the maximal amount of resins (21.4 mass %). while fuel oil and tar asphaltenes generate 9.4 and 7.3 mass %, respectively. It was shown that thermal transformations of asphaltenes during the rectification of heavy oil lead to the removal of large structural fragments from their molecules, thereby reducing the ability of asphaltenes to generate resinous substances at 290 °C. At the same time, the molecular structure of asphaltenes is compacted, which leads to an increase in their tendency to form coke-like products. The yield of coke-like products of the low-temperature thermolysis of asphaltenes from oil, fuel oil and tar is 42.1, 54.4 and 58.1 mass %, respectively. It is established that the thermal transformations of asphaltenes in the process of heavy oil rectification do not have any significant effect on their ability to generate gas and liquid hydrocarbons during thermal degradation. The results of the study should be taken into account when developing new technologies for the primary processing of heavy crude oils and upgrading the existing ones.

The rocks of Lower Cretaceous section in four exploration wells at the oil-producing fields of the Yamalo-Nenets Autonomous District were investigated. Dispersed organic matter was characterised by the composition of hydrocarbons using gas chromatography - mass spectrometry (GC-MC). Steranes, hopanes, n-alkanes and isoprenoid alkanes, naphthalenes, phenanthrenes, sesquiterpanes, dibenzothiophenes and dibenzofurans, retene, cadalene and simonellit were identified. Metalloporphyrins and perylene were determined by means of spectrophotometry. It was shown that the sediments studied were deposited under suboxidative conditions in the sedimentation basin with a significant contribution of both phytoplankton and terrestrial vegetation to the initial organic matter. Sedimentation proceeded near the coastline of the sea or in a coastal water body, which was periodically flooded by the sea. The thermal maturity of the organic matter corresponds to the major zone of oil formation.

The effect of the integrated action of low-frequency acoustic treatment, demulsifiers and the temperature factor on the stability and structural-mechanical properties of oil-water emulsions of paraffin low-resin oil from the Ignyalinskoye deposit is investigated. After low-frequency acoustic treatment of emulsions, water phase droplets are dispersed, and their number increases. Acoustic processing and introduction of demulsifier do not lead to the destruction of oil-water emulsions (10 mass %) stabilizing them due to an increase in the fragmentation of the dispersed phase. The integrated action is an effective method of the destruction of 50 mass % emulsions. After integrated processing, the size of the droplets of disperse phase in oil systems increases. Acoustic treatment of oil, oil-water emulsions (10 and 50 mass %) is accompanied by a quantitative increase in resin-asphaltene components. However, significant changes are observed only in the structural-group composition of asphaltenes.

Changes in the structural parameters of tar and asphaltene molecules of sediments obtained after oil dewaxing with liquefied petroleum gas at temperatures of 0, -5, -15 and -25 ° C were studied. It is shown that with a decrease in process temperature the amount of precipitate formed in the process increases from 10.9 to 13.4 mass %; deeper dewaxing, complete deasphalting and partial detarring also take place. It was established that a decrease in precipitation temperature from 0 to -25 ° C causes changes in the structural-group characteristics of asphaltene and resin molecules: molecular mass, the number of aromatic and naphthenic cycles, alkyl substituents and structural blocks in the molecule.

The process of elimination of hydrogen sulphide from methane in the plasma of barrier discharge in the presence of octane vapour is investigated. The use of octane vapour in the initial mixture with methane and hydrogen sulphide allows us to avoid the formation of deposit on the electrodes of the plasmachemical reactor and to achieve the high level of inhibition of the reactions leading to the formation of polymer-like compounds. The extent of hydrogen sulphide removal reaches 98 %, methane conversion does not exceed 10 %. Power consumption for the removal of hydrogen sulphide is 83 (kW · h)/kg. The major gaseous products of the treatment in the barrier discharge are hydrogen (30 %) and ethane (30 %). Among sulphur-containing products, mainly mono- and dialkyl sulphides were detected. A possible mechanism of the process is proposed. The ways to manage the plasmachemical process are substantiated.

The state of vegetation cover at the territory of Archinskoye, Shinginskoye, Kazanskoye, Yuzhno-Tabaganskoye and Zapadno-Ostaninskoye hydrocarbon deposits in the Tomsk Region was studied using satellite data from the MODIS spectroradiometer. The time series of the values of the Enhanced Vegetation Index (EVI) were calculated for the period from 2007 to 2019. Analysis of the dynamics of changes in the average EVI values allowed us to determine the minimal and maximal values of the index for the studied territories, and to identify a trend of an increase in its values, which indicates a good (non-depressed) state of vegetation and an improvement in the environmental situation of the studied territories of oil-producing complexes in the Tomsk Region.

The effect of the nature of the carbon template used in the synthesis of zeolites with a mesoporous pore system on their physicochemical properties is studied. It was revealed with the help of IR spectroscopy and X-ray phase analysis that the nature of the carbon material used in the synthesis of zeolites does not affect their crystallinity, which is 100 % for all zeolites. Investigation of the textural characteristics of the samples showed that the addition of carbon material to the reaction mixture during the synthesis of zeolite results in a decrease in the specific surface area and an increase in the volume of mesopores. The volume of micropores changes only slightly. The addition of carbon at the stage of zeolite synthesis leads to the formation of mesopores, the sizes of which are 3.5-20.0 nm in the case of the use of carbon black, and 3.3-8.6 nm in the case of nanoglobular carbon. The catalytic properties of Mo/ZSM-5 catalysts prepared on the basis of synthesised zeolites are studied, and the dependence of their activity and stability during the non-oxidative conversion of methane on the physicochemical properties of the zeolites used is shown. The formation of a mesoporous structure in the zeolite promotes a more uniform and dense distribution of Mo clusters with sizes not exceeding 1 nm in zeolite channels. It is shown that 4.0 % Mo/ZSM-5 catalysts based on zeolites with a mesoporous structure exhibit higher activity and stability in the non-oxidative conversion of methane to aromatic hydrocarbons than the catalysts based on zeolites with a microporous structure. The highest methane conversion is achieved over a 4.0 % Mo/ZSM-5 catalyst based on zeolite synthesised with carbon black.

The effect of the nature of the carbon template used in the synthesis of zeolites with a mesoporous pore system on their physicochemical properties is studied. It was revealed with the help of IR spectroscopy and X-ray phase analysis that the nature of the carbon material used in the synthesis of zeolites does not affect their crystallinity, which is 100 % for all zeolites. Investigation of the textural characteristics of the samples showed that the addition of carbon material to the reaction mixture during the synthesis of zeolite results in a decrease in the specific surface area and an increase in the volume of mesopores. The volume of micropores changes only slightly. The addition of carbon at the stage of zeolite synthesis leads to the formation of mesopores, the sizes of which are 3.5-20.0 nm in the case of the use of carbon black, and 3.3-8.6 nm in the case of nanoglobular carbon. The catalytic properties of Mo/ZSM-5 catalysts prepared on the basis of synthesised zeolites are studied, and the dependence of their activity and stability during the non-oxidative conversion of methane on the physicochemical properties of the zeolites used is shown. The formation of a mesoporous structure in the zeolite promotes a more uniform and dense distribution of Mo clusters with sizes not exceeding 1 nm in zeolite channels. It is shown that 4.0 % Mo/ZSM-5 catalysts based on zeolites with a mesoporous structure exhibit higher activity and stability in the non-oxidative conversion of methane to aromatic hydrocarbons than the catalysts based on zeolites with a microporous structure. The highest methane conversion is achieved over a 4.0 % Mo/ZSM-5 catalyst based on zeolite synthesised with carbon black.

The destruction of organic matter in oil-contaminated clay soil by native microflora was studied under laboratory conditions. Peat and the solution of a composition containing a surfactant and a nitrogenous substrate, as well as their combination with phytoremediation, were used as stimulating additives. After biodegradation, the residual oil was extracted and examined by means of IR spectroscopy, gas-liquid chromatography (GLC) and chromatography-mass spectrometry. According to the data of IR spectroscopy, peat and a solution of the composition promote the utilisation of paraffins, which is accompanied by an increase in the relative content of aromatic and carbonyl-containing structures. The isoprenoid coefficient K_i , which reflects the degree of hydrocarbon biodegradation, was calculated from GLC spectra as the ratio of iso- and n -alkanes. It increases with the introduction of stimulating substrates and soil loosening. The maximal biodegradation (biodestruction) coefficient is observed for the sample of oil-contaminated clay soil containing the surfactant composition, which contributes to oil emulsification and accelerates biodegradation. Acyclic ( n- and isoalkanes), alicyclic (cyclohexanes, drimanes, cheilanthanes, regular and rearranged steranes and hopanes), naphthenoaromatic (mono- and triaromatic steranes), and aromatic (mono-, bi-, tri-, tetra- and pentacyclic) hydrocarbons were detected in the soil organic compound (SOC) by means of chromatography-mass spectrometry. As a result of biodestruction stimulated by the introduction of peat and the nutrient substrate, the concentration of hydrocarbons decreased significantly: n-alkanes - by 74-82 %, aromatic compounds - by 97-99 %, cyclohexanes - by 78-92 %, oil steranes and hopanes - by 88-97 %. The introduction of the composition containing a nitrogenous substrate and a surfactant into the soil leads to a significant decrease in the content of C₁₂-C₃₄ alkanes to the level of background soil. The introduction of peat additive veils (shades) the results of alkane oxidation due to their presence in peat itself. The use of stimulating substrates leads to a decrease in the content of aromatic hydrocarbons during biodegradation: monocyclic by 82-89 %, bicyclic - by 55-81 %, tricyclic - by 74-89 %, tetracyclic - by 54-77 %.

Rubber-like elastic cryogels were formed from a two-component solution of polyvinyl alcohol in water after a freezing-thawing cycle, and their rheological properties are investigated. The interest in such environmentally friendly polymer cryostructures having viscoelastic properties is due to the fact that they are currently in high demand in the northern regions of the country. Cryogels are promising structural materials used for the development of new arctic technologies for oilfield engineering and for strengthening seasonally thawing soil in the permafrost zone, as well as for the construction and arrangement of hydraulic structures. As a result of the studies of the properties of cryostructuring agents, it was revealed that due to the mechanical action of external loads, elastic moduli of deformed cryogel samples decrease monotonously with time. Elastic moduli are traditionally used to quantitatively characterise the physical and mechanical properties of Hookean materials. The results of comparative experiments conducted by different researchers using the same cryogel samples are interpreted ambiguously due to the inconstancy of the elastic moduli of viscoelastic systems. In this work, the possibility and necessity to use cryogel relaxation time values as a quantitative criterion for describing the rheological properties of polyvinyl alcohol cryogels are experimentally substantiated. The values of the relaxation time of cryogels are proposed to be used instead of cryogel elasticity moduli to evaluate the viscoelastic properties of polymer systems in future design calculations.

Hydrocarbon deposits occurring at a depth of more than 4.5 km are poorly studied, although they are situated on all continents. This slows down the assimilation of these resources. Analysis of the information from the database of the Institute of Petroleum Chemistry of Siberian Branch of the Russian Academy of Sciences on the physicochemical properties of oil showed that the largest oil reserves are concentrated at depth down to 3000 m. The features of the changes of physicochemical properties of oils were established to depend on the depth of occurrence. It is shown that in different oil basins the density and viscosity of oil decreases with depth. The content of sulphur, resins and asphaltenes decreases with depth, while the content of petroleum gas and fractions increases with depth. The analysis of hydrocarbon occurrence conditions at great depths was carried out. The prospects of oil and gas potential of the deep sediments of oil and gas basins in Russia and Western Siberia, in particular, are evaluated.

Black coal is formed by a carbon framework originating from metamorphism of condensed polycyclic organic compounds. This framework includes volatile organic substances, as well as a definite amount of mineral admixtures that form ash after coal combustion. The content of individual polycyclic aromatic hydrocarbons (PAHs) in coal depends on the nature of initial plant material that participated in the stages of coal formation, and on thermodynamic conditions of this process. One of the major representatives of PAHs possessing a strong carcinogenic effect is benz(a)pyrene. The group of PAHs compounds also includes phenanthrene, fluoranthene, pyrene, chrysene, which are the major components of emissions during coal production, transportation, storage, concentrating, gasification, coking and combustion, and serve as convenient tracers to evaluate the pollution of the atmosphere, surface waters, and soil. The latter plays the part of a special accumulator into which PAHs get as a result of the global transport of emissions from anthropogenic sources and arrival from natural sources into the atmosphere. Because of this, soil relates to the most representative objects to study PAHs accumulation. The presence of these compounds may play the role of indicators depicting the presence of pollution source. As a rule, PAHs are determined by means of gas and high-performance liquid chromatography. Gas chromatography in combination with mass spectrometry appears to be the most promising method. To obtain reliable data on PAHs content in various objects, special attention is paid to sample preparation (extraction, purification, concentrating). Methodically correct arrangement of this stage allows excluding a noticeable fraction of the possible error of quantitative determination. The paper presents a review of the methods of PAHs extraction from solid matrices, in particular from fossil coal. It is demonstrated that all ranks of coal may be the sources from which toxic and carcinogenic PAHs enter various environmental objects. A review of the scientific foundations and modern practical methods of PAHs extraction from black coal is presented, the data on the distribution of the representatives of this group of compounds and on the prediction of carcinogenic activity during coal mining, transportation and processing are assessed.

The thermal stability and reactivity of heavy oil asphaltenes at temperatures below 300 °C were evaluated. In this work, we used an original method of sequential stepwise thermolysis of asphaltenes at temperatures of 120, 230, and 290 °C in the inert gas flow with the removal of the resulting products from the reaction zone at each stage of the process. This approach allows us to minimise the occurrence of secondary reactions to assess the true reactivity of asphaltenes, and also to take into account the differences in the binding energies in their molecules to determine the real thermal stability of asphaltenes within different temperature ranges. It was established that when asphaltenes are heated to 300 °C, they undergo intense thermal degradation with the formation of gas, oils, resins and insoluble coke-like substances. In the process of sequential stepwise thermolysis up to 290 ºС, the conversion of heavy oil asphaltenes exceeds 90 %. At a temperature of 120 °C, the conversion of asphaltenes can reach 13 % with the formation of mainly resinous substances (more than 10 mass %). An increase in thermolysis temperature to 230 °C leads to an increase in the conversion of asphaltenes to 40 % due to their ability to generate significant amounts of gas and oils (14-18 mass %), as well as coke-like products (2-10 mass %) under these conditions. In the process of subsequent thermolysis of asphaltenes at a temperature of 290 ºС, the maximum amount of coke-like substances (29-37 mass %) is formed. The yield of low molecular weight products is also significant and amounts to about 20 mass %. Thus, at temperatures below 300 ^oС, asphaltenes of heavy oils are characterised by low thermal stability and extremely high reactivity in thermal processes. The results obtained must be taken into account when developing new and modernising existing oil refining technologies.