Gas chromatography with mass spectrometric detection (GC -MS) was used to study the composition of bromides obtained upon selective cleavage (chemolysis) of the C-O bond of ether/ester bridges under the action of BBr3 in oil components from ten oil and natural bitumen samples. It is shown that most of the samples under study demonstrate the absence of monoand dibromides of alkanes, alkylcyclohexanes, pregnanes and steranes, cheilanthanes and hopanes in the products of chemolysis. Monobromides of n-alkanes have been identified only in the products of chemolysis of oil components isolated from maltha of the Ashalchinskoye oilfield and the products of its biodegradation under laboratory conditions. In total, the identified products of selective cleavage of ether/ester bridges include monoand dibromides of alkylbenzenes: mainly (C13-C22)-alkyltrimethylbenzenes, (C1-C7)-naphthalenes, phenanthrene, dibenzothiophene and their homologues. Monobromides of C6 -biphenyl, C4-tetralin, dibromides of (C2-C6)-benzothiophenes, (C2-C5)-biphenyls, C1-tetralin, fluorene, and C2-fluorene have been also identified. Tribromides of (C2-C4)-naphthalenes, C2-phenanthrene, and (C1-C2)-fluorenes have been identified in a limited number of samples. In chemolysis products, dibromides occur more rarely than monobromides, while tribromides are much less common than dibromides. The results obtained indicate that the above -mentioned compounds are partially present in oils as structural fragments connected with other fragments of the oil components through one or much less often through two or three ether/ester bridges. The list of structural fragments linked via ether/ester bridges, their composition and relative content differ in oil components of different oil and natural bitumen samples. Ethyl esters of aliphatic acids from C12 to C32, with a clear predominance of even acids and a maximum corresponding to C16 and C18, have been identified in the products of chemolysis of almost all samples.

Selective chemical cleavage (chemolysis) of C-S and C-O bonds of sulphide and ether/ester bridges, respectively, are presented. The revealed difference in the structural-group and molecular composition of some types of compounds before and after chemolysis indicates that alkanes, alkyltrimethylbenzenes, naphthalenes, phenanthrenes, tetra- and pentacyclic aromatic hydrocarbons, and dibenzothiophenes are present in oils not only as molecular entities, but, partially, as structural fragments linked via sulphide and ether/ester bridges with other fragments in complex high-molecular entities. Ester-bound high-molecular C20-C30 homologues predominate among the bound alkanes. The proportion of C13-C16 homologues among alkyltrimethylbenzenes decreases after chemolysis. Chemolysis is accompanied by an increase in the proportion of C3-C4 naphthalenes in petroleum oils. The ratio of homologues among phenanthrenes changes after chemolysis: as a rule, the unsubstituted compound predominates over homologues. The ratio of fluoranthene and pyrene to benzanthracene and chrysene increases among tetracyclic aromatic hydrocarbons. The main trend in the changes in the composition of dibenzothiophenes after chemolysis is a sharp decrease in the proportion of unsubstituted homologue.

The XRD-based study investigates the macrostructural parameters of asphaltenesisolated from natural sulfur-rich asphaltite and from liquid conversion productsof this asphaltite. The conversion was carried out in a supercritical water flowat 400°C and 30 MPa both in the absence and in the presence of aluminum and zincadditives. The XRD data demonstrate a decrease in the stack thickness (Lc) and in the number ofaromatic sheets (M) in asphaltenes isolated from the conversion productscompared to the initial asphaltite. On the other hand, the aromaticity(far) and theaverage aromatic sheet diameter (La) increase by a factor of nearly three;a significant rise is also observed in the proportion of stacked carbon atoms(φa). In the presence of metal additives, thedifferences are more pronounced. This is because the oxidation of zinc andaluminum in supercritical water, accompanied by heat release, increases thelocal temperature of the reactants and generates active hydrogen that preventsradical fragments from recombination.

The relevance of the research is caused by the fact that the processing of oil residues, heavy oils and natural bitumens based on thermal destruction of high-molecular components of hydrocarbon feedstock result not only in formation of new distillate fractions but they are always accompanied by the formation of oil-insoluble carbonation products, commonly known as coke. The main sources for coke formation are the resins and asphaltenes of the feedstock. Thermal destruction of resins and asphaltenes is widely used to study their molecular structure. Information on the composition and properties of insoluble products obtained by thermal treatment of resin-asphaltene substances will provide information on the pathways of their formation. The features of the macrostructure of insoluble coke-like products obtained in the course of thermolysis of resins and asphaltenes of Usinsk oil at various temperatures have not been established.The main aim of the research is to measure the parameters of the macrostructure of insoluble products obtained at different temperatures of autoclave thermolysis of resins and asphaltenes of Usinsk oil in an inert atmosphere.Objects: chloroform-insoluble products of resins and asphaltenes of the heavy, high-sulfur and highly resinous oil from the Usinsk oil field subjected to autoclave thermolysis in an argon atmosphere at 250, 450 and 650 degrees C.Methods: Raman spectroscopy, X-ray difraction.Results. Using Raman spectroscopy and X-ray diffraction phase analysis, the insoluble products of autoclave thermolysis of resins and asphaltenes of Usinsk oil have been characterized. It was found out that the products obtained during autoclave thermolysis at temperatures of 450 and 650 degrees C correspond in their characteristics to products of a relatively high degree of carbonation. Their Raman spectra contain bands in the region of 1350 and 1580 cm(-1) (D- and G-bands) and their overtones lying in the region of 2700 and 3400 cm(-1) are characteristic of carbon materials with a low degree of order. The parameters of their macrostructure, determined by the method of X-ray phase analysis and the features of the diffraction patterns also correspond to carbene-carbides and coke. At the same time, insoluble products obtained from resins at 250 degrees C exhibit fluorescence under registration of Raman spectra. Hence they are very close to the initial asphaltenes in terms of the macrostructure parameters calculated from the results of X-ray phase analysis. This gives grounds to classify them as asphaltene-like substances which confirms our conclusions drawn earlier on the basis of data of their elemental composition, IR-spectra, pyrolytic analysis in the Rock Eval mode and "on line" flash pyrolysis.

The structural group characteristics of resins and asphaltenes, isolated from high-sulfur natural asphaltite of the Ivanovskoe oilfield in Orenburg oblast and the liquid products of its conversion in a flow of supercritical water (SCW) at 400°C and 30 MPa with and without admixture of zinc or aluminum, have been investigated. It has been shown that as a result of SCW treatment, the molecular weight of the resins and asphaltenes decreases two- to fivefold in comparison with the components of the initial asphaltite. This is determined by a decrease in the number of structural blocks in the molecules which become more compact due to the decrease both in the number of rings, predominantly naphthenic ones, in the blocks and in the number of carbon atoms in the aliphatic substituents. The fraction of aromatic carbon atoms substantially increases, and the degree of substitution of the aromatic nucleus decreases in the resins and asphaltenes isolated from the conversion products. The differences in the structural chemical characteristics of the resins and asphaltenes manifest themselves to a greater extent in the case the metal admixtures.

It has been shown that the hydrothermal–catalytic conversion of solid natural asphaltite of the Spiridonovskoe oilfield (Republic of Tatarstan) at 250°C in the presence of hematite yields liquid products with a reduced amount of resins and asphaltenes. At the same time, a dispersed phase of insoluble carburized substances of the carbene and carboid types appears in the conversion products. The structural-group and molecular compositions of oils in the liquid products of conversion, which are enriched in aromatic, polycycloaromatic, and carbonyl-containing structural units and sulfoxides according to 1 H NMR and IR data, have been determined. It has been established that the molecular composition of oils from the initial asphaltite and its conversion products is almost the same, but there are changes in the relative amount of various types of compounds. A low concentration of alkanes and an increased concentration of triterpanes characterize the initial Spiridonovskoe asphaltite as a biodegraded object. In the conversion products, the relative amount of alkanes has sharply increased and the concentrations of tri- and tetracyclic aromatic hydrocarbons (HC) and dibenzothiophenes have become greater. The proportion of phenanthrenes and tetracyclic aromatic hydrocarbons has increased by factors of 9.3 and 2.6, respectively, and alkylcyclohexanes have been identified, which are absent in the original asphaltite. But the relative amount of polycyclic naphthenes (pregnanes, steranes, cheilanthanes, and hopanes) significantly decreased. The revealed differences are apparently determined by the scale of generation of these compounds by the degradation of resins and asphaltenes, in which the compounds occur as structural units of molecules or in an adsorbed and/or occluded form.

The relevance of the research is caused by the fact that thermal destruction is one of the most common processes of refining oil residues, heavy oils, and natural bitumens. Thermal and thermocatalytic processes of conversion of the above mentioned hydrocarbon feedstocks are accompanied by formation of supplementary distillate fractions ("secondary" oils) during thermal degradation of resinasphaltene substances of initial objects. Transformation of oils of the initial object and "secondary" oils occurs simultaneously at temperatures corresponding to the thermal disruption of "weak" and "strong" bonds in their constituent compounds. When choosing the optimum modes of thermal and thermocatalytic processing of heavy oil feedstock, the results of assessment of thermal stability of its components should be taken into account. One of the methods for studying the thermal stability of sedimentary organic matter is the Rock-Eval pyrolysis. Information about the potential of this method for analysis of oils is very limited. However, the information on their thermal stability and characteristic temperatures of destruction of their constituents could be obtained from the pyrogram of oils. The analysis of the pyrogram will also provide information on the difference in these parameters for oils isolated from crude oils and natural bitumens, sampled in various oil provinces and significantly differing in their component composition. The main aim of the research is a comparative analysis of thermal stability of oils isolated from natural bitumens and crude oils differing in the total content of resin-asphaltene substances, products of their laboratory biodegradation and conversion in supercritical water using the Rock-Eval method. Objects: oils isolated from 18 samples of crude oils and natural bitumens, products of their laboratory biodegradation and conversion in supercritical water. Methods: elemental analysis, NMR H-1-spectroscopy, Rock-Eval pyrolytic analysis. Results. it is shown that the information on thermal stability of oils isolated from crude oils and natural bitumens sampled in various oil provinces and differing in their component composition could be obtained via Rock-Eval pyrolysis. The presence of three peaks characteristic for oils is evident from the pyrograms. They are observed within different temperature ranges. Hence, S1 peak (isotherm 180 degrees C) corresponds to the process of the gasoline fraction (initial boiling point (IBP)...180 degrees C) evaporation. The S2a peak (180..350 degrees C) corresponds to overlapping of evaporation of intermediate fractions of oils and rupture of "weak" C-S, C-O bonds in the structural fragments of their compounds. The S2b peak (350...550 degrees C) corresponds to overlapping of evaporation of high-boiling fractions of oils and rupture of ("strong" C-O, C-C bonds in their structural fragments. The samples under study differ by more than one order of magnitude (from 0,32 to 3,91) in the ratio of the yields in volatile products at 350...550 and 180...350 degrees C (S-2b/S-2a) and in the ratio of the yields in the gasoline fraction of oils - S1 and S-2b+S-2a (0,044 to 0,518). The samples of oils under study also differ in the temperature of maximum rate of release of hydrocarbons in the course of pyrolysis in the range of S2b peak (from 445 to 466 degrees C). This difference is more significant in the range of the S2a peak (from 292 to 350 degrees C).

It has been shown that deep biodegradation of the components of oils with the change in the molecular composition of aliphatic, naphthenic, and aromatic hydrocarbons (HCs) occurs upon the biodegradation of Ashal’chinskoe crude petroleum by indigenous soil microflora under laboratory conditions. It has been found that alkanes and tri- and tetracyclic aromatic HCs are present in the oils of the biodegraded petroleum not only in the molecular form but also in the form of structural fragments linked through ether or sulfide bridges in the composition of complex high-molecular-weight entities. The composition of O- and S-linked compounds of the aforementioned types is different in the oils of the petroleum subjected to biodegradation.

A new approach towards determination of structure and composition of fragments coupled via a C-O bond in ethers and esters of petroleum and natural bitumen oils is developed. It is based on the use of the known chemical reaction of selective cleavage of ether/ester bridges in petroleum oil components using BBr3. Unlike the known approach involving the stage for reduction of products of chemical modification of oils with lithium aluminium hydride, it is proposed to analyse the composition of the resulting organic bromides by the GC-MS method. Mono- and dibromo derivatives of C-13-C-22 alkyltrimethylbenzenes are identified in chemical modification products on an example of natural bitumen oils from the Ashalchinsk field (Tatarstan). Unlike C-18-C-22 compounds, C-13-C-17 homologues are not detected in initial oils, therefore they are entirely coupled to other fragments of complex high molecular mass formations by one or two ester-ether bridges. Furthermore, as established during analysis of GC-MS results, there are ions corresponding to monobromides of characteristic fragment ions of n-alkanes, and also to mono- and dibromides of characteristic molecular ions of naphthalene, phenanthrene, dibenzothiophene, and their homologues. Hence, in complex high molecular mass formations of the studied oils, some of the listed compounds are linked via one or two ether/ester bridges.

Presented are the results on the study of insoluble products obtained at autoclave thermolysis of resins and asphaltenes of the oil from the Usinskoye oil field in an argon atmosphere at 160-650 degrees C. A high yielded chloroform insoluble thermolysis product obtained from the resins of heavy high-sulfur oil at 250 degrees C significantly differs from products obtained from resins and asphaltenes at 450 and 650 degrees C but according to the results of Rock Eval and 'on-line' flash pyrolysis (600 degrees C, 20 s), and elemental analysis it is similar to 'asphaltene-like' substances. Their formation is probably due to the cleavage at 250 degrees C of the most labile S-S or C-S bonds in the resin molecules followed by generation and recombination of macroradicals. The thermal destruction of these substances at higher temperatures (450 and 650 degrees C) is accompanied by the formation of more carbonized coke-like products.

The paper deals with the results on the study of distribution and composition of nitrogen compounds, particularly low-molecular nitrogen bases in the components of sulfur rich natural asphaltite and the products of its conversion in supercritical water at 400 degrees C, 30 MPa without any additives and in the presence of aluminum and zinc. Decrease in the content ratio of nitrogen in all variants of conversion is usually ranged as follows: insoluble conversion residue (ICR) > liquid product (LP) > volatile product (VP). About 50% of nitrogen compounds convert into ICR even at a sharp decrease in ICR yield in the presence of metal additives. The components isolated from conversion LP are usually characterized by higher nitrogen contents as compared with asphaltite components. In comparison with asphaltite, the pattern of nitrogen distribution over the components of LP changes significantly. A higher yield in extracts of nitrogen bases (NB) as compared with the initial asphaltite suggests a generation of additional portion of low-molecular NB due to the destruction of asphaltenes and resins contained in asphaltite during its conversion. The extracts contain much more aromatic compounds and their molecules have lower numbers of alkyl substituents. The contents of neutral NC (carbazoles and benzocarbazoles) and basic (benzoquinolines, dibenzoquinolines, azapyrenes, and benzoazapyrenes) are several-fold higher in the products obtained in the presence of aluminum additives. In addition, a sharp increase in unsubstituted structures among the above mentioned NC is observed in the same samples as compared with homologues. This is apparently due to the fact that the structural fragments in asphaltenes and resins are mainly linked by biphenyl bonds or via methylene or sulfide bridges.

The relevance of the research is caused by the fact that thermal destruction is one of the most common processes used to refine oil residues, heavy oils and natural bitumen. The use of such technologies promotes the formation of distillate fractions due to destruction of high-molecular components of feedstock and is always accompanied by the formation of oil-insoluble carbonization products, usually called coke. Some processes of oil refining are purposefully used to produce coke. Resin-asphaltene substances are considered as the main coke genes. Various options of resin and asphaltene thermal destruction are widely used to study their molecular structures. The study of the composition and properties of insoluble products obtained by thermal treatment of resin-asphaltene substances will provide information on the ways of their formation. The nature of insoluble products of resin and asphaltene thermal destruction at relatively low temperatures (160...250 degrees C) has not been studied yet. The main aim of the research is the comparative study of composition and properties of insoluble products obtained at different temperatures of autoclave thermolysis of resins and asphaltenes from the Usinskaya oil in an inert atmosphere. Objects: resins and asphaltenes of heavy, high-sulfur and highly resinous oil from the Usinskoye oil field, chloroform-insoluble products of their autoclave thermolysis in an argon atmosphere at 250, 450 and 650 degrees C. Methods: autoclave thermolysis in argon atmosphere, extraction, elemental analysis, IR and Raman spectroscopy, "Rock-Eval" pyrolytic analysis, flash pyrolysis (600 degrees C, 20 s) with "on-line" analysis of volatile products by gas chromatography with a mass-spectrometric detector. Results. The paper introduces the results on the study of insoluble products obtained at autoclave thermolysis of resins and asphaltenes from the Usinskaya oil in argon atmosphere at 160...650 degrees C. Chloroform-insoluble thermolysis products obtained with high yield from the resins of heavy high-sulfur oil at 250 degrees C significantly differ from the insoluble products obtained from resins and asphaltenes at 450 and 650 degrees C. By elemental composition, IR- and Raman spectra, the results of Rock Eval pyrolytic analysis and "on-line" flash pyrolysis (600 degrees C, 20 s) they correspond to "asphaltene-like" substances. Their formation is probably due to the breakage at 250 degrees C of the most labile S-S or C-S bonds in the resin molecules with generation and subsequent recombination of macroradicals. The thermal destruction of these substances at higher temperatures (450 and 650 degrees C) is accompanied by formation of more carbonized coke-like products.

Liquid products with a low content of resins and asphaltenes are resulted from the hydrothermal-catalytic conversion of solid natural asphaltite of the Spiridonovskoye deposit (Republic of Tatarstan) at 250 degrees C in the presence of hematite. In this case, a dispersed phase of insoluble carbonized substances such as carbenes and carboides is observed among the conversion products. Based on the results of IR, H-1 NMR and GC-MS analysis oils of liquid conversion products are enriched with aromatic, polycycloaromatic, carbonyl-containing structural fragments and sulfoxides. The sets of compounds in the oils of the initial asphaltite and its conversion products are almost similar but changes in the relative content of compounds of various types are observed. The products of conversion exhibit a dramatic increase in the relative content of alkanes and noticeable increase in content of tri- and tetracyclic aromatic hydrocarbons and dibenzothiophenes. Alkylcyclohexanes, which are lacking in the initial asphaltite are also identified. However, the relative content of polycyclic naphthenes (pregnanes, steranes, heilanthanes, and hopanes) has decreased markedly. The revealed differences are apparently due to the yield in these compounds resulted from the destruction of resins and asphaltenes and adsorbed and/or occluded components.

The composition of oil fractions (OFs) obtained via the conversion of heavy sulfur-rich petroleum is studied with physicochemical methods. Petroleum is supplied to the upper part of a vertical tubular reactor packed with activated carbon (AC), through which a supercritical water-oxygen fluid is pumped. The experiment is carried out under the following conditions: pressure 30 MPa; temperatures in the upper, middle, and lower parts of the reactor of 673, 723, and 723 K, respectively; and the flow rates of oxygen, petroleum, and water of 0–3.5, 4, and 6 g/min, respectively. Time dependences between the wall temperature of the reactor and power of ohmic heaters show that the autothermal conversion regime is achieved due to heat release during the combustion of high-molecular petroleum components accumulated in the AC bed. The movement of a combustion front along the reactor axis is found. Isoprenoid and normal alkanes, 1-alkyl-2,3,6-trimethylbenzenes, and alkyl derivatives of benzothiophenes and dibenzothiophenes are the main components of OFs of the initial petroleum. A yield of OFs, whose content in the liquid products exceeds 90%, has an extreme dependence on the oxygen flow rate. An increase in the oxygen flow rate (and, consequently, an increase in temperature of the reaction mixture due to heat release during combustion) leads to an increase in the content of alkyl derivatives of bicyclic and tricyclic aromatic hydrocarbons, as well as benzothiophenes and dibenzothiophenes in OFs of the products. The content of components boiling at T < 493 K in OFs of the products increases 2–3-fold in comparison with those of the initial petroleum.

The effect of supercritical water and pyrite on the transformations of propylene upon the uniform heating (1.5 K/min) of reagents to 718 K is studied. The products are analyzed by IR and 1H NMR spectroscopy, mass-spectrometry and gas chromatography/mass-spectrometry. It is established based on the temperature dependences of the pressure of reagents that the addition of pyrite in the absence of water gives rise to a decrease in the starting temperature of propylene oligomerization. In the absence of pyrite, the addition of water suppresses propylene oligomerization. A synergetic effect of supercritical water and pyrite on the degree of conversion of propylene is revealed. It is shown that hydrogen sulfide, thiols, and methyl-derivatives of thiophene are formed in the presence of pyrite, as well as the yield of aromatic and polyaromatic hydrocarbons increases. The mechanisms of the observed processes are discussed.

•Conversion of heavy oil at partial oxidation of activated carbon (AC) by SCW/O2 is studied.•A significant deasphalting and demetallization of oil occurs at SCW conversion in the presence of AC.•Reactions of carbon with SCW contribute to a high yield of products enriched with hydrogen.•Heat generation at combustion of AC and oil residue in SCW/O2 provides for an autothermal conversion.

The composition of oily fractions (OFs) formed by the Kashpir oil shale conversion in a flow of water vapor and supercritical water under uniform heating from 300 to 550°C is studied by means of gas-chromatography/ mass-spectrometry, IR, and 1H NMR spectroscopy. The maximum yield of the oil fraction is observed at 360–390°C. Alkanes, alkenes, and alkyl-derivatives of naphthalene and benzothiophene are the major components of the OFs formed below 440°C. A significant predominance of even alkanes and alkenes over their odd homologies is detected above 440°C. The peculiarities in the varying of the content of specific groups and individual polyaromatic substances are discussed.