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Hexa(ethylhexyl)-hexa-(peri)-hexabenzocoronene (HEH-HBC) was selected as model compound of asphaltenes. In fact, in the "island" model the asphaltenes are described with a relatively large aromatic core surrounded by aliphatic chains attached to the edges of the core. In their turn the asphaltenes are considered model compounds of MAONs (Mixed Aromatic-aliphatic Organic Nanoparticles), the possible carriers of the Unidentified Infrared Bands (UIBs), i.e. a set of certain infrared features found in very different astrophysical objects. The differential scanning calorimetric analysis (DSC) shows that HEH-HBC displays a discotic liquid crystal behavior, similar to that observed also in a selected authentic petroleum asphaltene sample. The electronic absorption spectrum of HEH-HBC was recorded for the first time in hydrocarbon solvents fully transparent in the UV, permitting to observe the UV part of HEH-HBC and to compare it with that of unsubstituted HBC. The FT-IR spectrum of HEH-HBC was recorded not only at room temperature but also at higher resolution at the liquid nitrogen temperature. The molar extinction coefficients and integrated molar absorptivity of the main bands were also estimated. The results are briefly discussed from an astrochemical perspective. [ABSTRACT FROM AUTHOR]

The work deals with the study of the effect of the process of heavy oil etherification on the aggregative stability of asphaltenes and their structural changes. The etherification was carried out at various temperatures from 25 to 100 °C for 8 h. It has been found that with an increasing temperature of oil treatment with isopropyl alcohol, an increase in the yield of resins and asphaltenes by 4 wt% is observed. Based on the data of IR-spectroscopy and NMR, it has been found that isopropyl radicals were likely to be incorporated into asphaltenes. In the structure of asphaltenes, aliphaticity, and branching increase by 3.5 and 2.9 times compared to the initial asphaltenes, respectively. Structural and group characteristics of asphaltenes were changed after the oil etherification, which was especially evident after the 100 °C of process temperature. It was also found that the treatment of heavy oil with isopropyl alcohol practically does not affect the stability of asphaltenes. [ABSTRACT FROM AUTHOR]

The regular solution model is used with Hankinson-Brobst-Thomson (HBT) molar volume correlation for saturates, aromatics, resins and asphaltenes (SARA) fractions for pure crude oils and blends to predict the precipitation of asphaltenes. The parameters of the HBT correlation were tuned with experimental data for SARA fractions densities. At the same temperature and pressure conditions, the precipitation of asphaltenes is greatly influenced by the presence of other compounds. SARA fractions were obtained according with ASTM D2007 using n-heptane as precipitant solvent. The use of average properties for saturates, aromatics and resins and the assumptions made in the model could reproduce precipitation curves for all study cases. Calculations of asphaltene precipitation prediction for pure oils showed an average absolute deviation between 0.12 and 0.69% for oil of Gulf of Mexico and Cold Lake oil, respectively. For blends it showed values between 0.08 and 0.65% for Cold Lake/Lloydminster-Asphaltene free blend and Cold Lake/Lloydminster-Gulf of Mexico blend respectively. The proposed model maintains its simplicity and can predict the asphaltene precipitation accurately. [ABSTRACT FROM AUTHOR]

Products from the thermal conversion of heavy crude oil in the presence of Ni- and Co-containing catalysts formed in situ from a mixture of appropriate salts with ethanol have been studied. In the catalytic process, the light fraction yield increases from 51 to 63% and the coke yield decreases from 3 to 2 wt % compared with the respective parameters of thermal cracking. In the case of a mixed Ni+Co catalyst, the lowest yields of gas (5 wt %) and coke (0.1 wt %) are observed. The decrease in sulfur content in both the thermal cracking (by 17%) and catalytic cracking products (by 12–32 rel %) occurs primarily due to the removal of sulfur in the form of gaseous products. The structural group characteristics of average asphaltene molecules before and after heavy crude oil cracking have been studied. Using X-ray diffraction analysis, Ni0.96S, Ni9S8, and Co9S8 phases have been identified in the solid cracking products. [ABSTRACT FROM AUTHOR]

The article is devoted to the problem of predicting the viscosity of an oil mixture. Viscosity is an important characteristic of oil when calculating pressure losses due to friction when moving in a well, through field pipelines, through a network of main oil pipelines. In the presence of a complex branched network of pipelines and the flow of oil from various wells and fields in the condition of constantly changing production flow rates, a large number of mixture variants can be formed. Laboratory determination of viscosity for each theoretically possible mixture is practically difficult to implement, therefore, it is promising to determine the viscosity of the mixture by a computational method based on parameters amenable to additivity. Such parameters can be density, component composition and its derivatives, such as the content of paraffins, resins, asphaltenes, and fractional composition. The article analyzes various regressions of the first and second kind to obtain equations for determining viscosity depending on the mentioned parameters. A model is being developed to predict the viscosity-temperature dependence of an oil mixture based on information on density, paraffin content, resins, asphaltenes and fractional composition. The results can be applied to the calculation of field and trunk oil pipeline networks.

The complex structure of asphaltene itself leads to obvious precipitation and aggregation characteristics, and it interacts with wax molecules, thereby affecting the wax precipitation characteristics of waxy crude oil. To clarify the effect of asphaltene on wax deposition behavior, molecular dynamics simulations were conducted to analyze the aggregation behavior of wax molecules in waxy crude oil systems and the effect of asphaltene on wax deposition. Subsequently, dynamic wax deposition experiments were used to validate the simulation results, and the influence of asphaltene on wax deposition behavior was further discussed in conjunction with the simulation results. The results show that the lower the temperature of the crude oil system, the lower the cooling rate, and the higher the aggregation degree of wax molecules; As the concentration of asphaltene increases, the existence state of asphaltene will undergo a transition, with a concentration of 0.2 wt% asphaltene as the transition boundary. The aggregation of asphaltene molecules is mainly in the form of F-type stacking, and the presence of asphaltene weakens the structural strength of the wax deposition layer. On the other hand, the aggregated asphaltene hinders the growth of wax crystal clusters due to spatial hindrance; Increase the concentration of asphaltene in the model oil, when the asphaltene concentration is 0.2 wt%, the wax deposition rate reaches its maximum, which means that the asphaltene concentration will affect its existence state in the waxy crude oil system, thereby affecting the wax deposition behavior. And analyzed the effects of temperature and moisture content on wax deposition. [ABSTRACT FROM AUTHOR]

Present review focuses on the most recent advances in a liquid‐phase nuclear magnetic resonance (NMR) of the coal‐derived products—coal tar pitches, asphaltenes, and humic and fulvic acids, covering exclusively the results in the liquid‐phase NMR studies leaving apart an overwhelming amount of publications dealing with the solid‐state NMR investigations in this field (which are comprehensively reviewed elsewhere). Owing to the complexity of the coal‐derived products, their 1H and 13C NMR spectra consist of a number of overlapping signals belonging to different hydrocarbon types. Comprehensive studies of coal tar pitches, asphaltenes, and humic and fulvic acids by means of NMR over the past several decades revealed characteristic functional groups of those fractions together with spectral regions in which they resonate. Quantitative 1H and 13C NMR spectra characterize aromatic and saturated carbons spread over many structural moieties, which provides a solid guideline into molecular structure of the coal‐derived products. Nowadays, quantitative 13C NMR measurements yield information about a variety of structural parameters such as functional group distribution, aromaticity, degree of condensation of aromatic rings, and medium chain lengths together with many other more specific parameters. The structural NMR studies of coal and coal‐derived products are developing on a backdrop of a marked progress in computational NMR. At present, we are witnessing an unprecedentedly fast development of theoretical and computational methods in the field of NMR spectroscopy. Discussed in the present review are the most recent advances in the NMR studies of the processing products of peat, lignite or brown coal, anthracite or hard coal, and graphite in solution, like coal tar pitches, asphaltenes, and humic and fulvic acids. [ABSTRACT FROM AUTHOR]

AbstractThe presence of natural lipophilic emulsifiers, such as asphaltenes (A), resin (R) and petroleum acids (PA) in crude oil, plays a crucial role in stabilizing the W/O emulsions. This study primarily focuses on elucidating the influence of their interactions on the interfacial properties of the water/model oil system, as well as its emulsion stability. First, equilibrium interfacial tension (IFT), interfacial dilational modulus (IDM) and phase angle are measured. Then, emulsion stability experiments are performed. Finally, microscopic images of the emulsions were captured to evaluate droplet size and dispersity. Results show that the addition of petroleum acid to both asphaltene-only and resin-only system reduces IFT and dilational modulus, weakening the strength of the interfacial film. The inhibitory effect of petroleum acid on resins’ adsorption at the interface is more pronounced compared to asphaltenes’. A low proportion of resin and petroleum acid (A/R ≥ 5, A/PA ≥ 7) enhances emulsion stability by co-adsorbing with asphaltenes at the oil–water interface. Conversely, a high proportion of resin and petroleum acid leads to a decrease in IDM and emulsion stability. For asphaltene/petroleum acid–water system, when A/PA ≤ 5, the presence of petroleum acid decreases the droplet size but enhances droplet dispersion while decreasing emulsion stability. It can be inferred that the presence of petroleum acids contributes more to the formation rather than stabilization of emulsions. This work deepens insights into the emulsion behavior of natural surfactants, providing theoretical guidance for the formation of stable emulsions underground and efficient demulsification above ground. [ABSTRACT FROM AUTHOR]

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The present review focuses on the most recent advances in liquid‐phase NMR of asphaltenes, leaving apart an overwhelming amount of publications dealing with solid‐state NMR investigations in this field. Owing to the complexity of the coal‐derived products, and in particular, asphaltenes, their 1H and 13C NMR spectra consist of a number of overlapping signals belonging to different hydrocarbon types. Comprehensive studies of asphaltenes by means of NMR reveal the characteristic functional groups of their fractions together with the spectral regions in which they resonate. NMR studies of asphaltenes provide a straightforward guideline for their chemical composition and that of the related coal‐derived products. [ABSTRACT FROM AUTHOR]

The paper presents the results of an investigation into the kinetics of catalytic hydrogenation of vacuum residue at temperatures of 380, 400 and 420 °C and different durations, ranging from 30 to 70 min, using a nanocatalyst containing the active metals nickel and titanium supported on chrysotile. It was found that the yield of oils from 30 to 50 wt.% and tars from 12 to 18 wt.% increased with increasing temperatures and reaction times. A slight increase in the proportion of solids in the range of 2.0 to 6.0 wt.% is explained by the activity of the nanocatalyst used. In the study of the kinetics of vacuum residue hydrogenation, using the nanocatalyst developed by the authors, we were able to achieve a low yield of solids with a short contact time as well as a high yield of low-molecular-weight compounds such as oils and tars. To determine the kinetic parameters (rate constants and activation energies), Simpson's integral method and a random search engine optimization method were used. High values of rate constants are characteristic of reactions in the formation of oils k1, tars k2 and asphaltenes k3 in the temperature range of 380–420 °C. The high values of the rate constants k1, k2 and k3 in the catalytic hydrogenation of the vacuum residue indicate the high reaction rate and activity of the nanocatalyst used. With an increase in temperature from 380 to 420 °C, the rate constant of the formation of gas products from vacuum residue and the conversion of asphaltenes into oils significantly increase, which indicates the accumulation of low-molecular-weight compounds in oils. The activation energy for reactions leading to the formation of oils, tars, asphaltenes, gas and solid products was 75.7, 124.8, 40.7, 205.4 and 57.2 kJ/mol, respectively. These data indicate that the processes of vacuum residue hydrogenation with the formation of oils and asphaltenes require the lowest energy inputs. Reducing the process temperature to increase the selectivity of the vacuum residue hydrogenation process when using the prepared nanocatalyst is recommended. The formation of oils at the initial stage plays a key role in the technology of the heavy hydrocarbon feedstock (HHF) hydrogenation process. Perhaps the resulting oils can serve as an additional solvent for high-molecular-weight products such as asphaltenes, as evidenced by the low activation energy of the process. [ABSTRACT FROM AUTHOR]

Relevance. The pipeline transportation of heavy oils from the extraction site to the processing point is associated with serious problems due to their high viscosity and pour point. Oil deposits form quickly during pumping and causing flow reduction in pipe. Moreover, the increased content of hydrogen sulfide and chloride salts leads to increased rate of corrosion. Structural and mechanical properties and the yield point of highly pourable paraffinic oils depend on a variety of factors, like oil thermostatting temperature. Studying the impact of the heat treatment temperature of highly paraffinic resinous oil on its mobility will allow reducing energy consumption and optimizing the technology of oil pumping and transporting in winter conditions. Aim. To identify the critical temperature ranges for heat treatment of highly paraffinic resinous oil from the Yuzhno-Mayskoe field based on the analysis of data on structural and rheological behaviors, composition of oil sediments and changes in the radii of oil aggregates formed in the studied oil under various heat treatment conditions. Methods. Oil rheological properties were determined using a HAAKE Viscotester iQ rotational viscometer with HAAKE RheoWin measuring device and control system; oil pour point was analyzed using “Kristall” low-temperature indicator of petroleum products meter; asphaltenes were isolated using the “cold” Golde method; oil composition was determined by column liquid adsorption chromatography; oil particle size was recorded by a Photocor Complex spectrometer for dynamic and static light scattering with DynaLS data processing program. Results. The authors have studied heat treatment temperature impact on the viscosity-temperature and energy characteristics of highly paraffinic tarry oil, formation and composition of asphalt, resin and paraffin deposits. They established that the critical temperature of heat treatment is 40°C. At this temperature the densest crystallization structure is formed in the studied oil, characterized by high values of both viscosity, intensive formation of sediment, activation energy of viscous flow and internal energy of destruction of the dispersed structure. It was shown that with photon correlation spectroscopy, during oil heat treatment at 40°C, a spontaneous size increase of oil aggregates occurs in the temperature range of 35–25°C.

Relevance. The need to obtain information about the chemical nature of the resin-asphaltene and oil components of atmospheric residue from distillation of crude oil produced at the Krapivinskoe field in order to select optimal technologies for its rational utilization. Aim. To study the structures of asphaltene macromolecules and resin substances and the molecular composition of the oil components of atmospheric residue from distillation of crude oil produced at the Krapivinskoe field. Methods. Transmission electron microscopy, X-ray phase analysis, IR spectroscopy, 1H NMR spectroscopy, structural group analysis, chemical destruction, gas chromatography-mass spectrometry. Results. The structure of resin-asphaltene substances and the molecular composition of atmospheric residue obtained in the course of atmospheric distillation of oil from the Krapivinskoe field in laboratory conditions have been characterized using a complex of physicochemical research methods. It was found out that asphaltenes of atmospheric residue have a predominantly amorphous structure because of the presence of a developed alkyl chain configuration in their macromolecules. Mean asphaltene molecules consist of three structural blocks, which basis is triarene cores condensed with four to five naphthenic rings. These naphthenoaromatic systems neighbor upon methyl substituents only. The mean molecules of atmospheric residue resins are predominantly single-block. Their structural blocks are more compact due to the smaller number of aromatic and naphthenic rings in the naphthenoaromatic system. A feature of mean resin molecules is also the presence of relatively long alkyl substituents in the blocks. It was established that the structure of asphaltenes and atmospheric residue resins contains fragments linked to each other or to the naphthenoaromatic core of their macromolecules through sulfide and ether bridges. In both types of ‘linked’ fragments, n-alkanes, n-alkylcyclohexanes and hopanes were identified. Among the fragments linked through sulfide bridges, n-alkylbenzenes, n-alkylmethylbenzenes and n-alkanoic acids were additionally identified, while ethyl esters of n-alkanoic acids were identified among fragments linked through ether bridges. A structural feature of the atmospheric residue resins is the presence of phenylalkanes with different positions of the phenyl substituent in both types of bridge-linked compounds. Steranes and phenanthrenes are present in the composition of compounds linked through sulfide bridges. The oil components of atmospheric residue contain n-alkanes, n-alkylcyclohexanes, hopanes, steranes, n-alkylbenzenes, n-alkylmethylbenzenes, alkylnaphthalenes and alkylphenanthrenes.

Relevance. The need to establish the true mechanisms of the formation of supramolecular structures in petroleum dispersed systems. It is important to identify the role of individual functional groups in asphaltene aggregation. This will help develop effective ways to prevent sediment formation in process equipment during production, transportation and processing of heavy oils. Aim. To study the effect of quinoline on the composition, structure and aggregative stability of asphaltenes from heavy oils of various chemical types. Objects. Heavy oils from the Zyuzeevskoe field and the Usinskoe field; model petroleum systems with a basic nitrogen content of 1,0 to 3,0 wt %; asphaltenes of the original and model petroleum systems. Methods. Liquid adsorption chromatography, gas chromatography-mass spectrometry, potentiometric titration, elemental analysis, cryoscopy in naphthalene, 1H NMR spectroscopy, structural group analysis, spectrophotometry. Results. With an increase in Nbas concentration in an petroleum system to 3 wt %, the content of asphaltenes decreases regardless of the type of petroleum system. It has been established that quinoline is actively involved in the formation of supramolecular structures of naphthenic type oil. With an increase in the Nbas content in the naphthenic petroleum system to 3 wt % the molecular weight of asphaltenes increases 1,5 times with a 2-fold increase in the proportion of basic nitrogen in their composition. This is accompanied by an increase in the proportion of naphthenoaromatic structure in the average asphaltene molecule. The structure of asphaltenes isolated from model methane-type petroleum systems, on the contrary, is enriched in alkyl fragments. It wasn established that the presence of quinoline in asphaltenes of heavy oils as a coprecipitated component significantly reduces their aggregative stability. With an increase in the molecular weight of asphaltenes in naphthenic petroleum systems to 2000 amu. and the proportion of basic nitrogen up to 2,69 wt % the rate of their aggregation before precipitation is reduced by 5–6 times. The aggregative stability of methane oil asphaltenes decreases when Nbas content in their composition is higher than 1,9 wt % and does not depend directly on their molecular weight.

The paper presents the results of an investigation into the kinetics of catalytic hydrogenation of vacuum residue at temperatures of 380, 400 and 420 °C and different durations, ranging from 30 to 70 min, using a nanocatalyst containing the active metals nickel and titanium supported on chrysotile. It was found that the yield of oils from 30 to 50 wt.% and tars from 12 to 18 wt.% increased with increasing temperatures and reaction times. A slight increase in the proportion of solids in the range of 2.0 to 6.0 wt.% is explained by the activity of the nanocatalyst used. In the study of the kinetics of vacuum residue hydrogenation, using the nanocatalyst developed by the authors, we were able to achieve a low yield of solids with a short contact time as well as a high yield of low-molecular-weight compounds such as oils and tars. To determine the kinetic parameters (rate constants and activation energies), Simpson’s integral method and a random search engine optimization method were used. High values of rate constants are characteristic of reactions in the formation of oils k1, tars k2 and asphaltenes k3 in the temperature range of 380–420 °C. The high values of the rate constants k1, k2 and k3 in the catalytic hydrogenation of the vacuum residue indicate the high reaction rate and activity of the nanocatalyst used. With an increase in temperature from 380 to 420 °C, the rate constant of the formation of gas products from vacuum residue and the conversion of asphaltenes into oils significantly increase, which indicates the accumulation of low-molecular-weight compounds in oils. The activation energy for reactions leading to the formation of oils, tars, asphaltenes, gas and solid products was 75.7, 124.8, 40.7, 205.4 and 57.2 kJ/mol, respectively. These data indicate that the processes of vacuum residue hydrogenation with the formation of oils and asphaltenes require the lowest energy inputs. Reducing the process temperature to increase the selectivity of the vacuum residue hydrogenation process when using the prepared nanocatalyst is recommended. The formation of oils at the initial stage plays a key role in the technology of the heavy hydrocarbon feedstock (HHF) hydrogenation process. Perhaps the resulting oils can serve as an additional solvent for high-molecular-weight products such as asphaltenes, as evidenced by the low activation energy of the process.

The modulation of bulk properties including the cohesive strength and the solubility of the asphaltenes, due to the inclusion of graphene nanosheets and the thermoplastic polymer, is probed by performing all-atom classical molecular dynamics (MD) simulations. The impact of morphological heterogeneity, including the size of the aromatic core of the asphaltene molecule, the nature of the heteroatom attached to the aromatic core, the orientation of the graphene nanosheets, and the surface area of the nanomaterial, on the bulk properties of the model systems of nanocomposites and interfaces is explored. The cohesive strength of the asphaltene composites is significantly enhanced by the introduction of graphene nanosheets. The addition of styrene–butadiene–styrene (SBS) block copolymer into the graphene-reinforced asphaltene systems improves the cohesive strength, structural plasticity, and compatibility between the nanomaterial and the asphaltenes. The π–π stacking interaction between the graphitic surface and the aromatic core of the asphaltene is identified to be the major driving force for modulating the cohesive strength. The dispersion interaction maximizes in the hierarchical layered structure compared to the randomly oriented structure of the graphene nanosheets and the asphaltene molecules. The energetics of non-covalent interaction are further assessed within the framework of dispersion-corrected density functional theory (DFT)-based methods. The DFT-derived adsorption energies and thermochemical properties substantiate the stronger interaction and the thermodynamic favorability of the adsorption processes in both the gas phase and solvent medium (toluene). The simulated IR and Raman spectra are also analyzed to reveal the nature of the interaction. [ABSTRACT FROM AUTHOR]

High content of asphaltenes and waxes leads to the high pour point and the poor flowability of heavy oil, which is adverse to its efficient development and its transportation in pipe. Understanding the interaction mechanism between asphaltene-wax is crucial to solve these problems, but it is still unclear. In this paper, molecular dynamics simulation was used to investigate the interaction between asphaltenewax and its effects on the crystallization behavior of waxes in heavy oil. Results show that molecules in pure wax are arranged in a paralleled geometry. But wax molecules in heavy oil, which are close to the surface of asphaltene aggregates, are bent and arranged irregularly. When the mass fraction of asphaltenes in asphaltene-wax system (ωasp) is 0-25 wt%, the attraction among wax molecules decreases and the bend degree of wax molecules increases with the increase of ωasp. The ωasp increases from 0 to 25 wt %, and the attraction between asphaltene-wax is stronger than that among waxes. This causes that the wax precipitation point changes from 353 to 333 K. While the ωasp increases to 50 wt%, wax molecules are more dispersed owing to the steric hindrance of asphaltene aggregates, and the interaction among wax molecules transforms from attraction to repulsion. It causes that the ordered crystal structure of waxes can't be formed at normal temperature. Simultaneously, the asphaltene, with the higher molecular weight or the more hetero atoms, has more obvious inhibition to the formation of wax crystals. Besides, resins also have an obvious inhibition on the wax crystal due to the formation of asphalteneresin aggregates with a larger radius. Our results reveal the interaction mechanism between asphaltene-wax, and provide useful guidelines for the development of heavy oil. [ABSTRACT FROM AUTHOR]

Coal additives impregnated with nickel and iron for use in Veba Combi Cracking technology are investigated. The morphology of the surface and pore space of a modified coal additive is presented. The additive is shown to be similar to lignite in terms of its elemental composition. A comparative assessment of the textural properties of the original and modified coal additive is carried out. A relationship between the composition of the coal additive and the final products of heavy residue cracking in the presence of hydrogen in the temperature range of 435–460°C and a pressure of 17 MPa is shown. Catalytically active metals present in the composition of the coal additive were shown to affect the conversion degree of resinous-asphaltene components, formation of coke-like substances, and yield of light distillate fractions. The catalytic activity of the nickel- and iron-impregnated coal additive in the process of tar thermal cracking in a hydrogen atmosphere is established. The results obtained confirm the positive effect of impregnation of coal additives with catalytically active centers. This effect consists in an increased conversion degree of high-molecular components of heavy residual oil feedstock, thus indicating the significant potential of Veba Combi Cracking technology. [ABSTRACT FROM AUTHOR]

The work is devoted to the study of the influence of nitrogenous bases on the composition of oil and the structure of asphaltenes on their colloidal stability in solution. Model petroleum systems with a basic nitrogen content of 1, 2, and 3% wt. were used as objects of study. Asphaltene-like nitrogenous bases were obtained by thermolysis of model petroleum systems with different nitrogen contents. The results were obtained using elemental analysis, non-aqueous potentiometric titration, spectrophotometry, 1H NMR spectroscopy, and liquid adsorption chromatography. It was established that the content of Nbas in asphaltenes increases by 0.3–1.3% wt. with the increase in quinoline content in petroleum components. Quinoline is incorporated into the supramolecular structure of asphaltenes and increases their average molecular weight by 650 amu. and aromaticity by 2%. The aggregative stability of asphaltenes decreases by 1.5–6 times with an increase in their average molecular weight and an increase in Nbas in their composition as a component of a dispersion medium. The colloidal stability of synthetic asphaltene-like substances, on the contrary, is due to the appearance of their molecular sequence of fragments containing Nbas in aromatic rings. [ABSTRACT FROM AUTHOR]

This study presents a novel method for separating asphaltene from crude oil at room temperature, eliminating the need for heating or refluxing. Traditional methods often suffer from high energy consumption, costly equipment, and safety risks associated with flammable steam. This research focuses on deasphalting heavy crude oil from southern Iraq, containing 3.934 wt.% of asphaltene. Using a lab-made flow injection analysis system, 27 experiments were conducted, varying solvent flow rates (10 mL/min to 50 mL/min), mixing coil lengths (200 cm to 300 cm), and combinations of aromatic and aliphatic solvents. An optimal design (custom) and response surface method (RSM) were employed to pinpoint the best conditions. The optimal deasphalting process involved a solvent flow rate of 50 ml/min, a 300 cm mixing coil, and a xylene/n-heptane (1:10 vol/vol) solvent blend. Statistical analysis confirmed the significance of parameters, encompassing single parameters, interactions, and quadratic effects, all with pvalues under the 0.05 confidence level. The efficiency of the deasphalting procedure was assessed practically and theoretically, yielding efficiency percentages of 71.97% and 73.48%, respectively, for asphaltene extraction. This innovative method offers a promising solution for efficient and safe asphaltene separation from crude oil without the need for energy-intensive processes. [ABSTRACT FROM AUTHOR]

A comprehensive investigation of a highly complex petroleum refinery (Nelson complexity index of 10.7) during the processing of 11 crude oils and an imported atmospheric residue replacing the design Urals crude oil was performed. Various laboratory oil tests were carried out to characterize both crude oils, and their fractions. The results of oil laboratory assays along with intercriteria and regression analyses were employed to find quantitative relations between crude oil mixture quality and refining unit performance. It was found that the acidity of petroleum cannot be judged by its total acid number, and acid crudes with lower than 0.5 mg KOH/g and low sulphur content required repeated caustic treatment enhancement and provoked increased corrosion rate and sodium contamination of the hydrocracking catalyst. Increased fouling in the H-Oil hydrocracker was observed during the transfer of design Urals crude oil to other petroleum crudes. The vacuum residues with higher sulphur, lower nitrogen contents, and a lower colloidal instability index provide a higher conversion rate and lower fouling rate in the H-Oil unit. The regression equations developed in this work allow quantitative assessment of the performance of crucial refining units like the H-Oil, fluid catalytic cracker, naphtha reformer, and gas oil hydrotreatment based on laboratory oil test results. [ABSTRACT FROM AUTHOR]

Relevance. The development of new methods for regulating the rheological properties of water-oil emulsion using thermal and chemical methods will allow reducing the viscosity of oil well products and energy consumption for pumping hydrocarbon mixtures. Aim. To determine the activation energy of viscous flow and particle sizes of the internal phase of the initial emulsion of the Archinskoe deposit and the emulsion with an introduced demulsifier. Methods. All experiments required to investigate the rheological properties of colloidal disperse systems were performed using HAAKE Viscotester iQ rotational viscometer. Results. Comparative experimental studies were carried out on the effect of the introduced demulsifier on the effective viscosity of the water-oil emulsion of the Archinskoe deposit. Laboratory-scale experiments were performed using the rotational viscometry, which allows one to evaluate the dependence of viscosity on shear rate and temperature. It was established that the studied samples are liquids with pronounced non-Newtonian properties, which are a consequence of the paraffinic nature of oil and its water-oil emulsion. The structure of nanoparticles of the dispersed phase of dehydrated oil and its emulsion is discussed and justified. Using the analytical Arrhenius–Frenkel–Eyring expression, which describes the dependence of viscosity on temperature and the physical and chemical nature of the liquid system, the results of viscometrical experiments were processed and the activation energies of viscous flow and the particle size of the inverse emulsion were calculated in the absence of a demulsifier and in its presence. Laboratory experiments have confirmed that for complete dehydration of oil well products, it is not enough to introduce only a demulsifier, but it also requires heating the emulsion to a temperature sufficient to melt and dissolve paraffin particles, which form a structural and mechanical barrier situated on the surface of the emulsion droplets.

This article presents studies on the modification of petroleum bitumen with polymer waste in the presence of vermiculite. An increase in temperature leads to an increase in the interaction of components, partial breakage of polyethylene and bitumen macromolecules, and the formation of radical-free valences. As a result, fragments of polyethylene and bitumen molecules react with each other, and the formation of qualitatively new structural formations occurs via the strong connection of polar and amorphous bitumen with nonpolar structurally viscous polyethylene. Domestically produced Kulantau vermiculite was used to ensure stable adhesion over a wide temperature range and increase the specific surface area, which acquired additional energy, resulting in an increase in the degree of adhesion to bitumen and increased durability of the binder with improved rheological characteristics. Because of the increased service life of road asphalt pavements, the use of the latter results in a considerable decrease in the cost of polymer-bitumen binders. Based on improved binder formulations, asphalt concrete exhibits excellent water resistance and strength at 50 °C (4.7 to 5.0 MPa). In summary, the modification of bitumen with polymer waste and vermiculite offers a promising avenue for improving the performance and longevity of asphalt pavements.

Сatagenetic transformations of asphaltenes of organic matter (OM) from recent sediments and fossil rocks were studied on rocks sampled from different sedimentary basins (Timan-Pechora, Mezen, West Siberian, Kuznetsk, Aldan-Maya and Middle Amur) of Russia. Changes in the elemental composition of asphaltenes were analyzed with the Veselovsky’s model of the formation of major groups of fossil fuels using cO parameter (cO = (O/8 – N)/(C/3)) as compared with the total carbon based on elemental analysis. Just as the Van-Krevelen diagram, the plot built in C–cO coordinates for OM of various genetic forms demonstrates a significant difference in the asphaltenes composition evolution during catagenesis. At the same time, the cO parameter has notably increased in asphaltenes of both types of OM. Structural transformations of asphaltenes during catagenesis were identified in the course of high-resolution NMR (nuclear magnetic resonance) spectroscopy. The research results comprise data on carbon distributions in the aromatic and aliphatic groups in the investigated asphaltenes of different type OM of sediments and rocks at different stages of lithogenesis. A correlation between the asphaltene composition and structural parameters depending on thermocatalytic transformations is revealed. The asphaltenes of terrestrial organic matter are distinguished by higher cO values and different carbon yields of aromatics (higher) and aliphatics (lower) throughout the catagenesis phase. The highly transformed marine OM is marked by surge condensation of aromatic rings in asphaltenes, which makes them similar to asphaltenes of the terrestrial type OM.

The evolution of the elemental composition of dispersed organic matter (DOM) heterocyclic components during catagenesis was traced via studying samples from the Tyumen (SG-6) and Srednevylyuy-27 (SV-27) super-deep wells of Siberia. During mesocatagenesis, the composition of terrigenous DOM asphaltenes and resins undergoes directed changes: a decrease in hydrogen and oxygen content, enrichment with carbon, and graphitization of the structure. During apocatagenesis, due to high-temperature destruction, on the one hand, there is a condensation of individual blocks of asphaltenes and their transition to an insoluble form (formation of epiasphaltenic kerogens – EPAK). On the other hand, the lighter part of the asphaltenes goes into the formation of hydrocarbons and gas formation – a relative increase in the concentration of the former in % by mass of residual bitumoids is noted, as well as structural redistributions within benzene and spirit-benzene resins. In all studied parameters of the elemental composition, a symmetrical (unidirectional) transformation of resinous and asphaltene components of bitumoids from the SG-6 and SV-27 wells under harsh thermobaric conditions is noted. The obtained results should be taken into account when predicting new oil and gas accumulation zones in deep-laid horizons.

This paper presents the study of the effect of multiple ultrasonic impacts on submicron asphaltene aggregates in a toluene/heptane solution, conducted with dynamic light scattering technique. The objects of the study were four samples of asphaltenes obtained from four different oils. For all samples, the change in the average size of the asphaltene submicron aggregates with time was measured after the addition of a precipitant (heptane) to a solution of asphaltenes in toluene at an amount above the threshold concentration. Asphaltene aggregates formed in solution after the addition of the precipitant and were subjected to ultrasonic treatment, which led to the destruction of the asphaltene aggregates. Aggregation of destroyed asphaltenes was observed. The kinetics of this aggregation were similar to the kinetics of aggregation of asphaltenes after the addition of a precipitant. Multiple iterations of asphaltene aggregate destruction in the sample led to a significant change in the kinetics of aggregation: the growth of aggregates slowed and stabilized at a size of approximately 200 nm and 30 nm for the different studied samples.

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Chemical degradation and chromatography–mass spectrometry methods were employed to identify resin components interlinked via ester, ether, and sulfide bridges. The resins were preliminarily isolated from liquid products prepared by thermolysis, at 300 and 450°C, of high-resin heavy oil asphaltenes from the Usinskoye oil field. Unlike the resins isolated at 300°C, their 450°C counterparts predominantly contained compounds that consisted of heteroatoms (i.e., S, N, and O). The particular distribution of bound moieties in the resin samples isolated at these thermolysis temperatures likely indicates that the Usinskoye field heavy oil asphaltenes consist of molecules that vary both in the type and location of ester, ether, and sulfide bridges. [ABSTRACT FROM AUTHOR]

The stability index of petroleum disperse systems can be calculated using continuous scanning of the optical profile of the asphaltene precipitation, taking into account the induction period of the asphaltene particle aggregation under the preset external conditions. Modification of the ASTM D7061 procedure allows taking into account the induction period of the asphaltene aggregation and different aggregation mechanisms (diffusion- and reaction-limited aggregation). This opens prospects for improving the procedures for express analysis of asphaltene-containing dispersions in the future. The control of the stability of asphaltene-containing systems is the base element for developing of a mathematical model of the kinetics of chemical processes occurring in a stratum, pipeline, or reactor. [ABSTRACT FROM AUTHOR]

The effect of low-frequency acoustic treatment and of constant and alternating electromagnetic fields on the reactivity of crude oil and resin–asphaltene components was studied. Irrespective of the kind of the wave treatment, the amount of asphaltenes and resins separated from the treated oil decreases owing the breakdown of aggregates of complex structural units with the release of hydrocarbons of various structures, occluded in the molecular complexes, into the liquid phase. The treatment involves cleavage of weak hydrogen bonds with the formation of additional reaction sites in paramagnetic asphaltenes and diamagnetic resins. The reactivity of both crude oil and the separated resin and asphaltene fractions significantly changes owing to the formation of new reactive structures in the physical fields. These structures differ not only in the size and structure but also in the antioxidant properties. The data obtained allow more detailed evaluation of the effect exerted by various kinds of wave treatment on the composition and structure of asphaltenes and resins of heavy high-viscosity crude. [ABSTRACT FROM AUTHOR]

The effects of temperature gradient on the formation, composition, and strength of oil deposits were investigated. As the crude oil temperature and the wall surface temperature were lowered, the concentrations of the oil fraction and low-molecular-weight paraffins in the deposits increased; simultaneously, the amounts of resins and asphaltenes declined. In the asphalt–resin–paraffin deposits formed in an asphaltene-free oil sample, cooling led to a rise in the content of resins and a decline in the content of the oil fraction. Model experiments demonstrated that the highest inhibitory capacity with respect to paraffin wax deposition was achieved in the case of 0.5–1.0 wt % asphaltenes being added. This can be attributed to the steric effect of aromatic rings manifested in their ability to disrupt the nucleation of paraffin networks. Therefore, the model wax deposits formed after adding asphaltenes exhibited a lower strength than the samples obtained with the addition of benzene resins and alcohol–benzene resins. [ABSTRACT FROM AUTHOR]

The instability of asphaltenes in crude oils, manifested in their precipitation, is a major production issue that may arise both during the recovery and processing of petroleum feedstocks. The purpose of this study was to investigate the molecular structure of asphaltenes in order to shed light on the causes of their precipitation. To this end, the molecular structures of stable (remaining in the solution) and unstable (precipitated) asphaltenes were characterized by EPR, NMR, and IR spectroscopy. Using crude oil asphaltenes and air-blown asphalt as objects for the study, only weak increasing and decreasing trends were observed in the content of aromatics and oxygenates, respectively, in the unstable asphaltene fraction. The stable and unstable asphaltenes were found to differ in adsorption capacity. It was shown that the species adsorbed on asphaltenes are rich in moieties of aromatic acid esters, and that removing these species further eliminates the structural-group composition differences between stable and unstable asphaltenes. The study findings suggest that the stability of asphaltenes in crude oils can be controlled by introducing synthetic aromatic acid esters structurally similar to natural surfactants. [ABSTRACT FROM AUTHOR]