A combination of methods, including scanning electron microscopy, X-ray diffraction analysis, Fourier transform infrared spectroscopy, and structural group analysis was used to trace the evolution of the molecular and supramolecular organization of asphaltenes in light and heavy crude oils during their thermal conversion in supercritical n-hexane. It has been shown that thermolysis of asphaltense under supercritical conditions is accompanied by the disintegration of the initial nanoaggregate and formation of smaller particles. Moreover, the asphaltenes of light crude oil undergo more extensive degradation. It was found out that the cracking of saturated fragments and the condensation of aromatic nuclei in the molecules of the resulted high-molecular components under conversion conditions occur simultaneously. This is evidenced by an increase in the size of quasi-crystallites in the structure of 'secondary' asphaltenes, an increase in the degree of aromaticity, and a decrease in the content of naphthenic rings in the structure of 'secondary' asphaltenes and the resulted resins. The resulted oil components are enriched in long-chain n-alkanes and depleted in heteroatoms. They are characterized by similar molecular composition. The compounds identified in the oils are n-alkanes, alpha-olefins, naphthenes, mono-and polycyclic aromatic hydrocarbons, including naphthene-aromatic and sulfur-containing structures. It was found out that oil components resulted from the conversion of light crude oil asphaltenes contain alkyl derivatives of policyclic aromatic hydrocarbons of higher molecular weight than those obtained by converting heavy crude asphaltenes. The data obtained indicate similarities in the thermal transformations of light and heavy crude oil asphaltenes. Differences in the macromolecular architecture of the original asphaltenes manifest themselves in the composition of the degradation products. This finding mayAbe useful for molecular characterization of the oils and prediction of the behavior of their resin-asphaltene components during thermal processing.

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.

The microstructure and functional compositions of the asphaltenes of bituminous oils from the Ashalchinskoye (Permian), Usinskoye (Permo-Carboniferous), and Nurlatskoye (Devonian) oil fields and their high- and low-molecular-weight components were studied using infrared spectroscopy, scanning electron microscopy, and transmission electron microscopy. It was shown that asphaltenes from the Ashalchinskoye oil were characterized by a smooth surface, while asphaltenes from the Usinskoye and Nurlatskoye oils had rough and porous surfaces. The sizes of asphaltene nanoaggregates from the Usinskoye and Nurlatskoye oils were smaller than those of the Ashalchinskoye oil. At the same time, asphaltene nanoaggregates from the Ashalchinskoye and Nurlatskoye fields formed a disordered tangled structure. A distinctive feature of asphaltenes from the Usinskoye oil was the presence of more ordered layers characteristic of crystal-like formations. Asphaltenes of Ashalchinskoye and Nurlatskoye oils were characterized by increased degrees of aromaticity and branching of aliphatic substituents in their macromolecules and a high relative concentration of fragments with a sulfoxide group. Their high-molecular-weight asphaltenes were less aromatic than low-molecular-weight ones, and their composition had a lower tentative concentration of carbonyl and sulfoxide groups. In the structure of asphaltenes form the Usinskoye oil, the fraction of aliphatic fragments and fragments containing a carbonyl group was increased. High-molecular-weight asphaltenes of this oil also contained fewer sulfoxide and carbonyl groups but more aromatic fragments than their low-molecular-weight asphaltenes.

Relevance. Thermal destruction is one of the main processes for upgrading heavy oils provided in the technological workflow. It is difficult to process such oils using existing basic technologies due to their high resin content. Hence, obtaining and summarizing information on the effect of thermal action on the composition and structure of organic nitrogen bases in resin components of heavy oils is of great importance for the development of innovative technical solutions for their rational use. The need for this work is due to their negative impact on the efficiency of primary processes of heavy oil refining and further catalytic upgrading of distillate fractions. Aim. To obtain comparative characteristics of the structural-group and molecular composition of organonitrogen bases isolated from resins of heavy oils and liquid products of their thermal destruction. Methods. Autoclave thermolysis in nitrogen atmosphere, complexation, extraction, liquid-adsorption chromatography, elemental and functional analysis, molecular weight measurement, H-1 NMR spectroscopy, structural-group analysis, gas chromatography-mass-spectrometry. Results. The authors have studied the composition and structure of organic nitrogen bases isolated from resins of bituminous oils and from liquid products of conversion of resinous components. These oils differ in the age of host rocks, the content of resin components, nitrogen compounds, and the content of bases in their composition. It was found out that organic nitrogen bases of the original and thermally converted resins are high-and low-molecular compounds, which are mainly represented by high molecular weight bases precipitated by hydrogen chloride. As a result of thermal cracking, the relative content of hexane-soluble compounds increases, while the content of hexane-insoluble compounds decreases dramatically in the composition of these bases. The method of structural-group analysis showed that the main thermal transformations of high-and low-molecular bases of resins of bituminous oils are the destruction of alkyl substituents and cyclization of shortened alkyl chains with the formation of naphthene rings. Compositionally similar alkyl-substituted quinolines, benzoquinolines, azapyrenes, thiophenoquinolines and benzothiophenoquinolines were identified among the low-molecular organic nitrogen bases of the original resins and liquid products of their cracking. The content of benzoquinolines in the composition of the identified bases decreases while the relative content of quinolines increases more noticeably in the course of the thermolysis of resins, an increase in the content of compounds containing a smaller total number of carbon atoms in the alkyl substituents of the aromatic cycles is observed for organic nitrogen bases of the conversion products.

Relevance. The need to obtain new data on the pattern of thermal transformations of resin, asphaltene and oil components of the fuel oil subjected to thermal or thermocatalytical treatment. These data will help to improve the efficiency of thermal and thermocatalytic treatment of fuel oil for increasing the yield of desired products. Aim. To study the structural organization of resin-asphaltene substances and the molecular composition of oil components isolated from the residue of crude oil produced at the Krapivinskoe field and the products of its thermal destruction. Methods. Transmission electron microscopy, X-ray phase analysis, IR spectroscopy, 1 1H NMR spectroscopy, structural group analysis and gas chromatography-mass spectrometry. Results. The authors have carried out the comparative study of the composition and structure of resin and asphaltene macromolecules and the molecular composition of residue obtained in the course of atmospheric distillation of Krapivinskoe oil and liquid products of its thermal and initiated cracking. It was found out that asphaltenes of the initial fuel oil and its cracking products have a predominantly amorphous structure. The presence of stacking ordered crystallites is less characteristic of asphaltenes isolated from liquid products of initiated cracking, which is due to the presence of a developed alkyl chain configuration in their macromolecules. In cracking processes, the mean asphaltene molecule becomes smaller due to a lower number of aromatic and naphthenic rings in the polycyclic system. On the contrary, the mean resin molecules become larger, mainly due to an increase in the number of aromatic cycles and paraffin carbon atoms in alkyl fragments. Paraffin carbon atoms in the structure of thermocracked asphaltenes are included into the methyl groups only, while in the structure of asphaltenes subjected to the initiated cracking they are mainly included into the long linear or weakly branched alkyl chains. In the mean molecules of the resin samples under study, paraffin carbon atoms form both short and relatively long alkyl substituents. Their fraction in the structure of mean resin molecules of cracking products is much higher than that in the structure of the mean resin molecule of the initial fuel oil. A distinctive feature of the oil components of the converted fuel oil is a wider range of identified compounds. They also include branched alkanes, n n-alkylcyclopentanes, n n-alkyldimethylbenzenes, phenyl derivatives of benzene and naphthalene, fluorenes, tetra-, penta-and hexacyclic aromatic hydrocarbons, benzo-and dibenzothiophenes, naphtho-and naphthobenzothiophenes. The products of destruction of resinasphaltene substances of the initial fuel oil and its oil components are considered as a likely source of these compounds.

The structural organisation and chemical composition of asphaltenes of heavy oils from the sediments of the Paleozoic complex of the Volga-Ural and Timan-Pechora oil and gas provinces are studied using a mix of physicochemical research methods (electron microscopy, proton magnetic resonance spectroscopy, X-ray diffraction, chemical destruction, and combined gas chromatography-mass spectrometry). It is shown that the asphaltenes of oils from the Permian-Carboniferous and Devonian sediments, unlike the asphaltenes of Permian oil with their smooth surface, are characterised by a loose and porous surface, and smaller sizes of nanoaggregates forming a disordered tangled structure caused by the presence of a branched alkyl chain configuration, which hinders aromatic sheets stacking. The crystallites of asphaltene nanoaggregates of heavy oils are characterised by similar thickness, average diameter, and number of aromatic layers in their cluster core, as well as the distance between the aromatic layers and saturated fragments. It has also been determined that the mean molecule of asphaltenes of the Permian oil is larger in size due to the high content of aromatic and naphthenic cycles in the naphthenoaromatic system. A structural feature of the asphaltene components of Devonian oils is a more branched alkyl chain configuration. The structure of the asphaltenes of heavy oils includes fragments linked through sulphide, ether, methylene and polymethylene bridges. Among them, acyclic, mono- and polycyclic naphthenic and aromatic hydrocarbons, as well as sulphur- and oxygen-containing compounds have been identified. The same representatives of sulphur-bound and ether-bound saturated and aromatic hydrocarbons in the structure of asphaltene molecules of heavy oils are similar in composition, but differ from each other in molecular mass distribution. The results of the investigation expand our understanding of the structure of asphaltenes of heavy oils, which may be used to model their structure for developing new controlled methods for processing hydrocarbon raw materials.

Relevance. Conditioned by the need to expand the amount of data on composition and structure of the asphaltene constituents of heavy oils. The data are important for creation of new and modernization of existing technologies for processing unconventional hydrocarbon raw materials. Aim. To study the composition of structural fragments in macromolecules of asphaltenes of bituminous oils from the Ashalchinskoe, Usinskoe, and Nurlatskoe oilfields using the ruthenium ion-catalyzed oxidation. Object. Fractions of high-molecular asphaltenes, which make up the bulk of the asphaltene constituents of the Ashalchinskoe, Usinskoe, and Nurlatskoe oils (94.1; 92.1 and 95.0 rel. %). Methods. Elemental analysis, cryoscopy in benzene, selective chemical destruction of Car–C bonds using a ruthenium ion-catalyzed oxidation, gas chromatography–mass spectrometry. Results. It has been established that the structure of high-molecular asphaltenes of bituminous oils from the Ashalchinskoe, Usinskoe, and Nurlatskoe oilfields contains fragments bound to the core of their molecules through Car.–C bridges and compounds trapped in the hollow cells of macromolecular entities of asphaltenes during kerogen cracking. It follows from the analysis of the oxidation products that the covalently bonded fragments are represented by C8–C32 n-alkanes, branched C9–C30 alkanes (2-methylalkanes and C15, C19, C20 isoprenoids), C22–C24 cheilanthanes, C27, C29–C33 hopanes and long chain alkyl bridges (C9–C30) connecting aromatic blocks. Most of the fragments linked by Car.–C bridges are linear paraffin chains. Typical biological markers, i. e. n-alkanes and hopanes were identified among the occluded compounds.

Comparative characteristics of resins, asphaltenes, andlow polarcomponents of heavy oils from the Ashalchinskoye (I) and Nurlatskoye(II) oil fields (Republic of Tatarstan, Russia) are given. These oilsdiffer in the age of host rocks (Permian and Devonian, respectively)and the content of their components and heteroatoms. An X-ray phaseanalysis and scanning and transmission electron microscopy revealthat, in contrast to smooth surface asphaltenes of oil I, asphaltenesof oil II are characterized by a loose and porous surface and smallersizes of nanoaggregates. Nanoaggregates form a disorderly tangledstructure because of the alkyl side-chain configuration, which makesit difficult to stack aromatic sheets. The crystallites of nanoaggregatesof asphaltenes of oil II are smaller than the crystallites of nanoaggregatesof asphaltenes of oil I. The application of the method of structural-groupanalysis based on the use of the measured indicators of the elementalcomposition, average molecular weights, and the results of H-1 NMR spectroscopy made it possible to establish that overall sizesof mean molecules of resins and asphaltenes of heavy oil I are largerdue to the increased content of aromatic and naphthenic cycles inthe naphthenoaromatic system. A feature of the structure of the resin-asphaltenecomponents of oil II is a greater number of alkyl substituents inthe side chains. According to gas chromatography-mass spectrometry(GC-MS) analysis, the low polar components under study arecharacterized by a similar set of saturated hydrocarbons (n-alkanes, mono-, and polycycloalkanes) but differ in thecomposition of identified aromatic hydrocarbons and heteroorganiccompounds. A feature of the low polar components of oil II is thepresence of a wider range of n-alkyl- and phenylalkyl-substitutedbenzenes and nitrogen- and oxygen-organic compounds in their composition.

Data on the composition and structure of aliphatic and aromatic fragments bound through oxygen in the molecules of resinous-asphaltene and oil components of bitumoid from the sample of Dmitrievskoe oil shale have been obtained.

An effect of biogenic oxidation of heavy high-viscosity oil from the Ashalchinskoye oilfield by native soil microflora (laboratory experiment) on the composition and structure of its resin components is investigated by using a complex of physicochemical research methods (elemental analysis, IR spectroscopy, selective chemical cleavage of sulfide and ether bonds, gas chromatography-mass spectrometry). It has been found out that the share of alkyl fragments decreases, while the conventional content of aromatic fragments and oxygen-containing structures increases in the structure of resin heavy high-viscosity oil substances in the course of biodegradation. The biodegradation of resins heavy oil is accompanied by changes in the qualitative and molecular compositions of the compounds bound in their structure through sulfide and ether bridges. The share of aromatic hydrocarbons is lower, while the relative content of heteroorganic compounds is higher in the compounds identified in the products of chemical destruction of biodegraded oil resins. The predominance of saturated hydrocarbons remains stable. The molecular composition of bound n-alkanes, n-alkylbenzenes, and naphthalenes changes most noticeably in the course of biodegradation. The relative content of linear hydrocarbons is lower in the alkanes determined in the products of chemical degradation of resins of the biodegraded oil. The share of macromolecular compounds and homologues with an even number of carbon atoms is higher in linear hydrocarbons. In naphthalenes, the relative content of the least resistant to microbial oxidation naphthalene and its C-1 and C-2 homologues is lower, while the share of C-3 and C-4 homologues is higher. Monoalkylbenzenes of resins are subject to biooxidation in the entire range of the number of carbon atoms. The obtained information allows a more detailed assessment of the influence of the biodegradation process on the composition and structure of heavy high-viscosity oil resins.

An effect of biogenic oxidation of high-viscosity oil from the Ashalchinskoye oilfield by native soil microflora (laboratory experiment) on the composition of structural fragments bound through sulfide and ether bridges in the macromolecules of its asphaltene components is investigated by using the method of selective chemical destruction. Chemolysis of ether and sulfide bonds in asphaltene macromolecules was carried out using boron tribromide and nickel boride, respectively. Composition of structural fragments linked through sulfide and ether bridges was revealed by GC-MS analysis using a DFS instrument "TERMO-scientific". It has been found out that the biodegradation of asphaltenes is accompanied by changes in the qualitative and molecular composition of sulfur- and ether-bound compounds. The share of aromatic hydrocarbons is lower, while the relative content of heteroorganic compounds is higher in the compounds identified in the products of chemical destruction of asphaltenes of biodegraded oil. This is most noticeable in structures bound through sulfur. However, the prevalence of saturated hydrocarbons, which in biooxidized asphaltenes are predominantly bound through oxygen, remains stable. This is the molecular composition of bound alkanes of both types represented by n-alkanes and isoalkanes in the samples under study, which changes most noticeably in the course of biodegradation. The relative content of linear hydrocarbons, where the share of macromolecular compounds and homologues with an even number of carbon atoms increases, is lower in the ether- and sulfur-bound alkanes identified in the products of chemical destruction of biomodified asphaltenes. The content of pristane and phytane in the ester-bound isoalkanes is noticeably decreased, which suggests the participation of isoprenoids in the process of microbial oxidation. The information obtained allows a more detailed assessment of the influence of the biodegradation process on the composition and structure of asphaltenes.

It was shown that the averaged asphaltene molecules of bituminous oils include no more than four structural blocks, the skeletons of which differ in the numbers of aromatic and naphthenic rings and the numbers of carbon atoms in alkyl substituents. The crystalline part of the macromolecules of the test asphaltenes had a layered structure. In terms of the number of layers of a packed structure, the thickness and the average diameter of its packing, and the number of aromatic rings in a layer, the test asphaltenes differed insignificantly.

The relevance. Accumulation of data on the structure of asphaltenes of methane-naphthenic oil of the Krapivinskoe oil field from the Upper Jurassic deposits in the territory of the Tomsk region is one of the conditions necessary for solving problems associated with its production, transportation, and processing. The purpose of the work is to study the composition of asphaltenes in oil from the Krapivinskoe oil field using the oxidation reaction catalyzed by ruthenium ions. The object of investigation is the fraction of high molecular weight asphaltenes that make up the bulk of asphaltene components of the Krapivinskoe oil (87,9 % rel.). Methods: selective chemical destruction of Car-C bonds using the oxidation reaction catalyzed by ruthenium ions and gas chromatography-mass spectrometry. Results. It was found out that the composition of high-molecular-weight asphaltenes of methane-naphthene oil contains fragments bound to the cores of their molecules through the C-ar-C bridges and occluded compounds. Covalently bound fragments are represented by C-5-C-18 n-alkanes, aromatic structures of the biphenyl type, and naphthalenes located at the periphery of asphaltene molecules. Among the occluded compounds n-alkanes, alkylcycloalkanes, steranes, terpanes, alkylbenzenes, naphthalenes, phenanthrenes, fluorenes, pyrene, chrysene, fluoranthene, biphenyls, phenylnaphthalenes, dibenzothiophenes, benzonaphthothiophenes, indole, carbazol, quinoline, benzoquinolines, phenols, dibenzofurans, and benznaphtofurans were identified. Saturated hydrocarbons are typical biological markers; they are trapped in hollow cells of macromolecular formations of asphaltenes during kerogen cracking. Aromatic hydrocarbons and heteroorganic compounds are products of thermal destruction of parent asphaltenes; they are blocked by geomacromolecules at later stages of the formation of their macrostructure. The information obtained expands the understanding of the structure of asphaltenes in oil dispersed systems, so it may be used to construct a hypothetical model of their molecules.

The average structural-group characteristics of molecules of asphaltenes and nitrogen bases of bituminous oil from the Ashalchinskoye oil field and the products of their molecular mass fractionation are described. It was found out that the molecules of the fractions of asphaltenes and nitrogen bases differ in the quantitative values of all structural parameters characterizing the ring composition and the characteristics of aliphatic fragments. Carbon skeletons of structural blocks (units) of molecules of asphaltene fractions vary from biarenes with long aliphatic chains to triarenes containing only methyl groups as alkyl substituents. The carbon skeletons of the structural units of nitrogen base molecules vary from alkylarenes to biarenes containing both methyl groups and longer aliphatic chains as alkyl substituents. The structural units of molecules of all asphaltene fractions and fractions of low molecular weight nitrogen bases are characterized by extreme distribution of aromatic cores in naphthenoaromatic systems. A feature of the molecules of high molecular weight nitrogen bases is the central location of the aromatic core in the polycyclic system.

Ruthenium ion-catalyzed oxidation of methanonaphthene oil (Krapivinskoye oilfield) revealed that its high molecular asphaltenes contain aromatic–aliphatic bridges and non- covalently bound (occluded) compounds. Covalently bound fragments are represented by C 5 –C 18 n -alkanes, aromatic biphenyl-type structures, and naphthalenes located in the peripheral part of asphaltene molecules. Typical biological markers, i.e . terpanes, steranes, and n -alkanes have been identified among the occluded compounds.

An oxidation reaction catalyzed by ruthenium ions has revealed that high-molecular asphaltenes of methano-naphthene oil from the Krapivinskoye oilfield contains structural fragments linked by means of Car-C bridges and non-covalently bound (occluded) compounds. It was found that covalently bound fragments in the composition of high mo-lecular weight asphaltenes of Krapivinskaya oil are represented by alkanes of normal structure, aromatic structures of biphenyl type and naphthalenes located in the periphery of the molecule. Typical hydrocarbon biomarkers such as n-alkanes, steranes, and terpanes are present among the occluded compounds.

The relevance of the work is caused by the need to expand the amount of data on resin-asphaltene substances and oil components of heavy oils, which share in the volume of the extracted and processed hydrocarbon raw materials is steadily growing. The refining of oils with high content of asphaltenes, resins, and heteroatomic compounds using existing basic technologies is hard and costly. Hence. information on the composition and structure of the heavy oil components is of great importance for the development of innovative technical solutions of their rational use. This is due. first of all, to the fact that resins and asphaltenes are considered the important reserve for the advanced processing of crude oil while oil components are considered the basis for the production of commercial petroleum products. The purpose of the work is to study the structural-group composition of asphaltene and resin macromolecules and the molecular composition of oil components of heavy oils sampled in various oil and gas provinces and differing in the age of the enclosing deposits and the content of resin-asphaltene and oil components. Methods: liquid adsorption chromatography, elemental analysis, cryoscopy in benzene, H-1 NMR spectroscopy, structural group analysis, combined gas chromatography mass-spectrometry. Results. A comparative description of the composition and structure of macromolecules of resin-asphaltene substances and the molecular composition of oil components of heavy oils from the Ashalchinskoe (I), Usinskoe (II) and Nurlatskoe (III) fields is given. These oils differ in the content of these components and heteroatoms and in the age of the enclosing deposits (Permian. Permian-Carboniferous, and Devonian). It has been found out that the content of asphaltenes and resins increases in the series of heavy oils I-II-III. At the same time, their average molecular weight decreases and the overall sizes of their mean molecules become smaller. This is due to a decrease in the number of structural blocks. which become more compact because of decreasing total number of rings in the naphthenoaromatic system, mainly naphthenic ones. In this case. the number of carbon atoms in the paraffin fragments of the structural blocks of mean molecules increases. The observable changes in the structural parameters of molecules are most pronounced for the resin-asphaltene components of oil from Devonian deposits. It is shown that oil components of heavy oils are characterized by a similar set of saturated hydrocarbons. but differ in the composition of identified aromatic hydrocarbons and heteroorganic compounds. A feature of oil components in the oil III is a wider range of mono- and bicyclic arenes and oxygen-containing structures.

The averaged molecules of asphaltenes and resins of the organic matter of oil shale from the Dmitrievskoe deposit and the liquid products of its conversion in a flow of supercritical benzene were described using structural group analysis based on the joint use of information on the elemental composition, average molecular weights, and 1H NMR-spectrometric data and the results of X-ray diffraction analysis. The results obtained made it possible to expand the understanding of the macromolecular structure of the resin–asphaltene components of oil shale formations and to reveal similarities and differences in their structural organization.

The similarities and differences in the composition of organosulfur compounds in the organic matter of oil shale from Upper Jurassic, Middle Devonian, and Middle Cambrian deposits were characterized using modern analytical techniques (selective chemical destruction with the use of nickel boride, supercritical fluid extraction, gas chromatography–mass spectrometry, and two-dimensional gas chromatography with a time-of-flight mass spectrometric detector).

The results of studies of asphaltenes of bituminous oil from the Ashalchinskoye oilfield and oil and resin-asphaltene components isolated from the liquid products of their conversion in n-hexane under supercritical conditions are presented. It is found out that the mean molecules of secondary asphaltenes and resins differ from those of asphaltenes of the initial sample by the number of structural blocks. They prevail in the mean molecule of secondary asphaltenes, while in the mean molecule of resins they are lesser in number. A feature of the structural blocks of secondary asphaltenes is a lower number of naphthenic cycles, a higher content of sulfur atoms, and a reduced content of nitrogen and oxygen atoms. The structural blocks of the resulted resins consist of minority of aromatic and naphthenic cycles and contain a lesser number of sulfur and nitrogen atoms but more of oxygen atoms than the initial and secondary asphaltenes. The qualitative composition of the compounds identified in the resulted oils is substantially identical to that of the compounds identified in oil components isolated from liquid products of autoclave thermal degradation of asphaltene substances of heavy oils.