Acidic and basic ion‑exchange resins were prepared by chemical modification of petroleum asphaltenes. The resulting products were characterized by IR spectroscopy and MALDI mass spectrometry. Feasibility was demonstrated for carrying out catalytic acylation of salicylic acid in the presence of acidic and basic catalysts derived from petroleum asphaltenes to give acetylsalicylic acid. Asphaltene‑derived ion‑exchange resins containing either sulfonic acid (SA) or amino groups (AA) were used as catalysts. These catalyzed reactions gave acetylsalicylic acid in 78

The products from the reaction of petroleum asphaltenes with sulfuric acid under various conditions, accompanied by oxidation, sulfonation, and decomposition reactions, were studied. The change in the content of stable free radicals and vanadyl complexes in the products from the reaction of asphaltenes with sulfuric acid in relation to the time and temperature was determined by EPR spectroscopy. The chemical processes in the reaction of asphaltenes with sulfuric acid take place most strongly in the first hour, being accompanied by peak growth of the concentration of stable free radicals. With increase in the length of treatment of the asphaltenes with sulfuric acid there is a decrease in the concentration of stable free radicals accompanied by a decrease in the content of sulfo groups in the products. After only 30 min of the process there was a marked decrease in the content of vanadyl complexes in the reaction products.

Stepwise oxidation-sulfonation of vacuum residue asphaltenes was carried out. It was shown that oxidation leads to the formation of carboxyl groups around the perimeter of the polyaromatic core. By contrast to ammonium persulfate, potassium dichromate oxidizes to a greater extent the sulfur atoms in the composition of asphaltenes which undergo desulfurization in an acidic medium. In the oxidation-sulfonation products the C/H parameter increases by a factor of 2.1, and the O/C parameter, by a factor of 19. The reaction of sulfonation of the oxidized asphaltenes proceeds less efficiently than that of the initial asphaltenes, as expressed in the value of the total static exchange capacity. Complexes of the oxidation-sulfonation products of asphaltenes with divalent copper cations were converted to redox ion-exchange materials by subsequent reduction with sodium dithionite in an alkaline medium.

Strongly acidic cation exchangers were obtained by the sulfonation and successive sulfonation and nitration of petroleum asphaltenes. The cation exchangers were characterized by IR spectroscopy and acid–base back titration; the surface morphology was studied by scanning electron microscopy. The kinetic regularities of the Kabachnik–Fields reaction were studied at various temperatures in the course of catalysis by the cation exchangers based on asphaltenes and in the absence of a catalyst.

The literature data on the abiotic degradation of asphaltenes are the subject of a systematic review. Such degradation may proceed under natural conditions. In particular, the action of sunlight, especially, ultraviolet radiation, initiates photolysis and photooxidation in asphaltenes leading to an increase in their oxygen content, thereby shifting the hydrophilic-lipophilic balance toward hydrophilicity and increased access of the reaction products for subsequent biotic degradation by microorganisms. The action of ionizing radiation does not lead to a significant change in the molecular composition of asphaltenes since they are highly inert to radiation. An exception is found for the irradiation of asphaltenes by intense electron beams, leading to their considerable degradation.

This review is devoted to the generalization and systematization of the available literature data on the processes of abiotic degradation of asphaltenes, which can occur in natural conditions. In particular, it was shown that exposure to sunlight, and especially UV radiation, triggers photolysis and photooxidation reactions in asphaltenes, leading to an increase in the oxygen content in them, thereby shifting the hydrophilic-lipophilic balance towards hydrophilicity. At the same time the availability of reaction products for subsequent biotic degradation by microorganisms is increased. Exposure to ionizing radiation does not lead to a significant change in the molecular composition of asphaltenes, due to their high radiation resistance. As exception there is the irradiation of asphaltenes with intense electron beams, which leads to their significant degradation.

The sorption properties of native and modified petroleum asphaltenes with respect to phenol were studied under static conditions. The asphaltenes were modified by nitration, followed by reduction with sodium sulfide. Sorption isotherms of phenol were constructed on the basis of the obtained data, and equations for the adsorption processes were calculated. It was found that the adsorption isotherms can be described most accurately by the Freundlich and Langmuir equations. It was found that the process occurs as a result of physical adsorption.

The sorption properties of native and modified petroleum asphaltenes with respect to phenol have been studied under static conditions. Modification of asphaltenes was carried out by nitration, followed by reduction with sodium sulfide. Based on the data obtained, phenol sorption isotherms were constructed and the equations for the adsorption processes were calculated. It was found that the adsorption isotherms can be described most correctly by the Freundlich and Langmuir equations. It was revealed that the process is carried out due to physical adsorption.

Novel anion-exchange resins were prepared from asphaltenes by nitration with nitric acid followed by reduction of the nitrated asphaltenes with sodium sulfide. The aminated asphaltenes were investigated as anion exchange resins for the treatment of phenol-containing wastewater. Their maximum adsorption capacity was found to be 2.3-fold superior to that of an industrial AV-17-8 (OH– form) AER sample.

In this study, an approach for the preparation of heterogeneous acid catalysts based on asphaltenes isolated from vacuum residue is proposed. Varying the conditions for the sulfonation of asphaltenes made it possible to obtain materials with an acid value of 1.16 to 2.76 meq g−1 and a total sulfur content of 6.4 to 12.3 wt%. The samples obtained were characterized by acid-base titration, nitrogen adsorption, sulfur elemental analysis and transmission electron microscopy techniques, and were studied as potential acid catalysts in the ketalization reaction between glycerol and acetone. Sulfonated asphaltenes (SA) were characterized by a homogeneous distribution of sulfonic groups over the granule surface and an almost complete absence of a porous structure. The ketalization reaction in the presence of SA proceeded without intradiffusion restrictions; as a result of which, their activity was higher than for known heterogeneous catalysts. The most active SA sample (total acid value, 1.16 meq g−1) had an apparent activation energy of 18.0 kJ mol−1, which was lower than the value obtained for the zeolite BEA-40 (29–53 kJ mol−1) and the Amberlyst 36 resin (27 kJ mol−1), and was close to the value for the homogeneous p-TSA catalyst (14.5 kJ mol−1). The SA heterogeneous catalysts did not show any acid leaching and had no loss of activity after five catalytic cycles, with the total turnover number TON = 7247.

The relationships of the reaction of the of tar asphaltenes with concentrated nitric acid were studied under various quantitative, temperature, and time conditions. According to IR spectroscopic data, nitration occurs to the highest degree during the action of a 50-fold excess of 64% nitric acid on the asphaltenes at 60°C for 4 hours. Nitration is accompanied by oxidation side reactions leading to the formation of nitrate, phenolic, carbonyl, and sulfoxide groups. It was established by mass spectrometry that there is a tendency for the number-average and weight-average molecular weights of the nitration products to decrease in comparison with the initial asphaltenes. It was found by electron paramagnetic resonance that the content of stable free radicals and vanadyl complexes in the products of the nitration reaction decreases.

The feasibility of the room temperature catalytic cyclization of hydrazine hydrate and acrylic acid in the presence of an acidic catalyst containing petroleum asphaltenes was explored. The effect of sulfocationite on the synthesis of the target pyrazolidin-3-one was studied. Reaction masses and their distillation residues were analyzed. Gas chromatography–mass spectrometry and electrospray ionization were used to reveal different individual, oligomeric and polymeric products. The most probable structures of the obtained products were proposed.

The possibility of the catalytic cyclization reaction between hydrazine hydrate and acrylic acid at room temperature on an acid catalyst based on petroleum asphaltenes was studied. The effect of sulfocationite on the possibility of obtaining the target pyrazolidine-3-one was investigated. The reaction mixtures and their bottoms are analyzed. Different oligomeric and polymeric products were identified by gas chromatography-mass spectrometry and electrospray ionization. The most probable structures of the resulting products were described.

Results of a study of the reaction products of asphaltene sulfonation with sulfuric acid in various temperature and time ranges have been described. The maximum sulfur content in sulfonated cation exchangers at an asphaltene sulfonation temperature of 100 and 120°С and a reaction time of 2 h has been determined. The maximum static exchange capacity of 4.3 meq/g has been found for the products of sulfonation with a sulfuric acid–oleum mixture. The asphaltene-based strongly acidic sulfocationite has been tested in the 2,2-dimethyl-1,3-dioxolane synthesis reaction.

Quantum-chemical modeling of the spatial and electronic structure of asphaltenes containing different numbers of electron-withdrawing substituents used the DFT/B3LYP-6-31G(d,p) method to predict the reactivity of petroleum asphaltenes upon their chemical modification. The change of torsion angle of the polycondensed aromatic asphaltene structure depending on the type of substituent was studied. The electronic structure and electron-density charge distribution over the aromatic carbon atoms were analyzed to determine the predominant direction of electrophilic substitution of the studied asphaltene model structures. A high degree of polycondensation of the asphaltenes and the presence of electron-donating aromatic heterocyclic fragments were shown not to affect significantly the direction of attack of an electrophilic reagent. Introduction of electron-withdrawing substituents decreased the rate of electrophilic substitution.

Oxidation of petroleum asphaltenes by potassium iodide (KI) is described. Oxidation under mild conditions is shown to be accompanied by iodination of the asphaltene aromatic core. The inducing reaction is the oxidation of sulfide sulfur atoms in the asphaltenes with reduction of iodate anion to molecular iodine; the coupled reaction, electrophilic substitution. X-ray photoelectron spectroscopy detected an increase in the mass fraction of oxygen as compared with the initial sample and formation of C–I bonds. IR spectroscopy found that oxidation of the asphaltenes is accompanied by the formation of carboxyl and sulfoxide groups. Raman spectroscopy revealed a decrease in the size of the oxidized asphaltene molecules as compared to the native asphaltenes. X-ray powder diffraction analysis showed a decrease in the interplanar spacing of the asphaltene oxidation product that was due to ordering and a denser arrangement of the aliphatic fragments.

In this work, variations of heavy oil asphaltenes' oxidation reactions under different conditions were investigated. By IR spectroscopy was shown a predominant destruction of occluded and adsorbed compounds in asphaltenes when using KIO(3)and NaIO(4)as oxidizing agents. In the case of CH3COOH/H(2)O(2)and KMnO(4)was determined the destruction of asphaltenes supermolecules with a formation of carboxyl groups. EPR spectroscopy demonstrated decrease of content of vanadyl complexes spin per gram of oxygenates 0.5-2 times in comparison with initial asphaltenes, which indicates the separation of occluded metalloporphyrins. Content of free stable radicals in high molecular products increased in 2-4 times.

The applicability of express methods for determining the effectiveness of solvents used for heavy oil recovery from carbonate reservoirs is studied. In the three-stage extraction method the wetting and extraction ability of the solvent in oil-saturated carbonate rock can be estimated from the surface tension of the solvent and the attenuation coefficient of the extract, respectively. In the method based on thin-layer chromatography the wetting and extraction ability of the solvent in oil-saturated carbonate rock can be estimated from the average boiling point and refractive index dispersion of the solvent. It was shown that the proposed methods can be used to arrange the solvents in order of their effectiveness in recovery of oil from carbonate reservoirs.