Asphaltene Fractions Research Articles

Exploration of graphitic carbon from crude oil vacuum residue

Preparation of graphitic carbon from low value refinery waste has captivated immense interest in past years owing to its low cost and abundant nature. Successful utilization of petroleum vacuum residue is a major challenge in the petroleum industry. In this study pyrolysis of vacuum residue fractions has been carried out for the preparation of graphitic carbon like material. The vacuum residue fractions were obtained from three different crude oils originated from Middle East, Canada and South America. The purity of the Aromatic, Resin and Asphaltene (ARA) fractions were confirmed using TLC-FID which denoted complete separation. The chemical composition were determined using elemental analysis and it revealed ARA fractions to be carbon rich regardless of its origin. Further, sulphur content was found to be high in ARA fractions from Heavy Crude oil (HCO). The degree of polymerization and molecular weight measured using GPC specify that asphaltene has high accumulation with high molecular weight compared with aromatic and resins. ARA derived carbon and heat-treated materials were analysed by TGA, XRD and Raman spectroscopy to study microstructural changes in formation of graphite like material. Thermogravimetric analysis of all ARA samples revealed the different decomposition stages for pyrolyzed, calcined and graphitized samples. The results of XRD demonstrated that the distance between the planes (d-spacing) is above 3.35 Å for all high temperature treated ARA derived carbon materials irrespective of its origin, indicating formation of graphite like structure. In Raman analysis, the nature and intensity of G and D bands evolution during each step of pyrolysis is supporting XRD results for formation of highly ordered graphitic carbon material. Furthermore, understanding feed quality has direct influence on high efficiency, low costs and sustainability, the major issues for oil refinery business.

Low rigidity despite high asphaltene content in bitumen: The role of resins

This research presents a laboratory study on three different bitumens, chosen as representative, coming from three different oils with different origins (Saudi Arabia, Venezuela, Russia) for assessing their structural differences due their different origins. The three bitumens have penetration indexes of 160/220, 70/100, 70/100 respectively, whereas their S.A.R.A. compositions showed marked differences particularly in the asphaltene and resin content, being the bitumen from Saudi Arabia particularly rich in such fractions, and that from Venezuela possessing the lower content of these. Rheological characterization carried out as a function of frequency and temperature suggests that: (i) the modulus at an angular frequency of 1 rad/s takes the lowest value for sample from Saudi Arabia, in accordance with the penetration index trend of the samples (ii) from a microscopic point of view, the average number of first neighbors involved in the flowing process is around one. Further analysis involved the extraction of the asphaltenic fraction according to the standard ASTM D4124 procedure: the melting point of the asphaltene fraction is 175 and 195 °C for the samples from Venezuela and Russia, respectively, while it can hardly be detected for the sample from Saudi Arabia. This anomalous behavior has been interpreted with the aid of X-Ray scattering data, which highlighted a lower order in asphaltene assembly at higher level of aggregation, which means that asphaltene molecules are arranged to form local assemblies with structural well-defined order only at short range, being higher levels of aggregations more disordered. All the data self-consistently show that the bitumen from Saudi Arabia, thanks to a higher content of resins, can stabilize more efficiently aphaltenes and therefore the latter can form ordered stacks only ad short range (only few Angstroms), leaving a more amorphous structure at longer ranges with consequently higher penetration index and lower modulus.

A study on the mechanisms and influencing factors of interfacial physicochemical interactions between asphalt and mineral aggregates based on multiscale evaluation methods

The elucidation of interfacial physicochemical mechanisms between asphalt and mineral aggregates is vital for comprehending the interface formation in asphalt mixtures and enhancing their performance. To this end, multiscale evaluation methods were used to investigate the mechanisms and influencing factors of interfacial physicochemical interactions between asphalt and mineral aggregates (IPIAMA). Initially, the dynamic shear rheometer (DSR) was used to measure the complex shear modulus (G*) of various asphalt mastics. Subsequently, the interface film thickness was calculated using G* in conjunction with the Hashin and Mori-Tanaka (MT) micromechanical models. This indicator facilitated quantitative assessments and the analysis of influencing factors. The results indicated that the MT model underestimated the interface film thickness by approximately 0.08–0.29 % compared to the Hashin model, a discrepancy attributable to assumptions regarding aggregate particle interlocking. Moreover, the interface film thickness systematically varied with factors such as aggregate content, type of aggregate, and type of asphalt, ranging from 0.24 to 0.53 μm. To further elucidate the IPIAMA mechanisms behind these variations, the fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), x-ray photoelectron spectroscopy (XPS), and the ultraviolet test (UV) testing were conducted. FTIR tests demonstrated that the primary components of mineral aggregates—dolomite, calcite, and quartz—contributed to the physical adsorption increments on asphalt functional groups by 0.0185, 0.0509, and 0.004, respectively. SEM images revealed that dolomite and calcite possessed more surface fissures and pores than quartz. XPS tests showed that calcium carbonate and magnesium carbonate chemically reacted with asphalt, resulting in electron shifts of 0.9 eV and 1.1 eV, respectively, while silicon oxide only exhibited electron shifts when combined with a silane coupling agent-modified asphalt. UV tests demonstrated that lighter asphalt fractions were preferentially absorbed into the pores and micro-cracks of mineral aggregates. Consequently, the complex IPIAMA involved physical adsorption, chemical reactions, and selective absorption, strongly correlating with factors such as mineral composition, surface morphology, and asphalt type.

Characterization of emissions from rubber modified asphalt and their impact on environmental burden: Insights into composition variability and hazard assessment

Rubber modified asphalt (RMA) is a promising avenue for recycling waste tires but faces concerns over hazardous fumes emission during production and construction. This study employs a specialized apparatus to analyze RMA's emission behavior, focusing on crumb rubber size variations under thermal conditions. Ozone Formation Potential (OFP) and Secondary Organic Aerosol Formation Potential (SOAFP) were quantified to evaluate the environmental burden. Results indicate distinct periods of emission behavior for different pollutants, with H2S emissions primarily occurring within the initial 150 min while volatile organic compounds (VOCs) dominate within the first 270 min. The size of rubber particles and thermal exposure duration influence the VOCs microscopic emission characteristics and environmental burdens. Polycyclic aromatic hydrocarbons (PAHs) emerge as the primary contributors to OFP and SOAFP, accounting for nearly 65 % and 25 %−60 %, respectively. High molecular weight aliphatic hydrocarbons (ALHs) also significantly contribute to SOAFP, with PAHs dominating throughout, while ALHs peak during the middle stage. H2S emissions likely stem from rubber, while early VOC emissions originate from rubber, transitioning to petroleum asphalt during the middle and late stages. Asphalt fractions influence emission behavior and property evolution. These findings inform emission suppression strategies and highlight the need for tailored approaches to mitigate emissions effectively.

SYNTHETIC WATER-IN-OIL EMULSIONS: EFFECT OF OIL COMPOSITION ON STABILITY AND DEMULSIFIER PERFORMANCE

Stable water-in-oil (w/o) emulsions are undesirable from an operational standpoint, with the asphaltenes present in petroleum being considered the main stabilizers of these emulsions. Demulsifiers are agents added to destabilize these emulsions. The objective of this work is to evaluate the stability of w/o emulsions formed from an oil phase with different polarities (kerosene and toluene) containing asphaltene fractions C3I, C5I, and C7I, and how these systems affect the action of a demulsifier additive. Systems containing asphaltenes in toluene were more stable when using the C7I fraction due to its greater polarity and, consequently, considerable action at the interface. With the oil phase composed of a less polar solvent (kerosene), the C3I fraction increased the stability of the emulsion by reducing the action of the demulsifying additive, with an upper asphaltenes concentration limit of 1.0% observed where the action of the demulsifying agent was affected.

Photo-induced ageing processes in bitumen

Asphalt roads and waterproofing membranes on roofs are exposed to sunlight, which induces irreversible changes in those materials. The underlying chemical processes initially affect the surface but later on impact the bulk chemistry and the mechanical properties. Bitumen, the binding and sealing material, is particularly susceptible to such influences. However, the molecular processes that initiate material deterioration are still poorly explored. Here, we show that ultraviolet and visible light cause the formation of a unique set of oxidation products and alter aromatic structures on the bituminous surface. Qualitative and quantitative information is obtained using infrared, fluorescence and NMR spectroscopy. Bulk ageing studies have shown a shift of molecules from the aromatics to the resins and asphaltenes fractions, potentially influencing colloidal stability. The evaluation of surface processes was facilitated in ageing studies with thin sub-µm specimens. We find that gaseous oxygen is essential for molecular changes to occur. The formation of carboxylic acids, esters and aliphatic alcohols, coupled with the degradation and restructuring of aromatic systems, demonstrates the unique nature of light ageing. This is due to a nuanced interplay between oxidation, degradation, condensation and aromatisation reactions. The ageing rates depend on the origin of the binder and increase as the wavelength of the light source decreases. Ageing follows an asymptotic growth with time. All results considered, this study enabled us to decipher critical molecular processes during photochemical ageing. In this regard, we hope to develop more effective strategies for mitigating and preventing the adverse impact of solar radiation on bituminous infrastructure in the future.

Exploring asphaltene aggregation: Model systems based on toluene-heptane mixtures

This work evaluates how chemical characteristics, such as polarity and aromaticity, can affect asphaltene aggregation. The asphaltene fraction was extracted from two different crude oils by precipitation in n-heptane, and these extracted asphaltenes were named A and B. Based on infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR) analyses, we found that asphaltenes B present greater aromaticity. According to X-ray photoelectron spectroscopy (XPS), asphaltene B showed higher heteroatom content. Model systems based on toluene/n-heptane/asphaltene (0.05 g/L) were prepared to evaluate the aggregation/precipitation of asphaltenes. Dynamic light scattering (DLS) analysis of aggregation kinetics revealed that aromatic asphaltenes with higher heteroatom content tend to form larger aggregates. Moreover, hydroxyl content exhibits a greater impact on aggregation compared to diffusivity. Furthermore, once the aggregates reach a critical size, the suspension stability is reduced, and the aggregates sediment. The atomic force microscopy (AFM) and DLS results revealed a wide range of particle size distribution. The larger clusters likely consisted of smaller aggregates that adhered together. Still, we highlight that the sizes of these aggregates determined by AFM are not directly comparable to the measurements obtained from DLS. The drying of the samples for the AFM measurements probably affects the asphaltene aggregation process. For this reason, the results obtained from the AFM and DLS techniques are not comparable.

Use of Hansen Solubility Parameters (HSP) in the selection of highly effective rejuvenators for aged bitumen

While there is considerable research regarding the recycling and reuse of aged bitumen in terms of the evaluation of rheological properties, there is not much fundamental understanding regarding the underlying mechanisms of the rejuvenation process. Specifically, the rationale behind rejuvenator selection and the efficiency of rejuvenators is not well understood. This paper proposes an approach for rejuvenator selection based on Hansen Solubility Parameters (HSP). To fully validate its feasibility, rheological and chemical tests were also performed. The results revealed that highly efficient rejuvenators have similar HSP with bitumen and greater HSP radii. The overlapping ratio between the Hansen spheres of bitumen and rejuvenators could be considered as a reliable tool to screen rejuvenators. Linear correlations were found between the efficiency of rejuvenators and solubility spheres. The rheological and chemical tests using master curve analysis and saturates, aromatics, resins and asphaltenes (SARA) fractionation further supported using HSP as a basis for rejuvenator selection.

Deasphalting of crude oils: A molecule-based model to explore an optimization approach and alternative solvents

Actual motivation to reduce environmental impact leads to an increase in the study of green technologies, even those used in processes with fossil fuels. However, far from the proposed reduction of such energies, heavier crude oils are being processed to fulfill the energy demand. Heavy crude oils require an upgrading process to mitigate the effect of noxious components or contaminants such as asphaltenes and heavy metals. In this work, a deasphalting process was studied by simulation as a pretreatment to eliminate the heavy compounds of crude oil. The simulation of such a deasphalting process was carried out by Aspen Plus® software by combining a model for crude oil, formed by 33 molecules and able to describe its complex composition, mainly in the asphaltene fraction, and a model for the phase equilibria that use liquid-liquid equilibrium equations and the modified UNIFAC (Dortmund) model.A new objective function, including extraction yield, asphaltene reduction, and the ratio solvent/crude oil, was proposed and used to optimize extraction conditions and compare the performance of several solvents. Up to 12 pure solvents of different nature (tert-butanol, n-butanol, iso-propanol, methanol, ethylene glycol, acetone, methyl-isobutyl ketone, per-fluoro heptane, anisole, 1-metil-2-pyrrolidone, sulfolane, and n-heptane) were checked as well as some binary mixtures of them to explore more sustainable alternatives against conventional paraffin as precipitating agents. Satisfactory results were obtained when alcohols or ketones were used. A deeper study was developed to understand the effects of the alcohols' molecular structure (branching, chain length, and molecular weight) as solvents. Higher branching reduces the solvent/oil ratio, while higher molecular weight leads to higher extraction yield but poorer asphaltene reduction.

The characteristics of produced oils in the miscible CO2 displacement process

CO2 flooding is an effective technique for enhancing oil recovery by changing the hydrocarbon fluid’s characteristics. One of the fundamental mechanisms of the interaction between CO2 and hydrocarbon fluid by miscible CO2 injection is the extraction phenomenon of the hydrocarbon components by CO2. It results in altered produced and residual oil characteristics. This study aims to examine the characterizations of produced oil during the process of CO2 displacement. It is critical to anticipate any issues that can arise from miscible CO2 flooding, such as asphaltene deposition. A light-dead oil sample from an Indonesian oil field was used in this investigation. The miscible CO2 displacement process was conducted by a slim tube experiment at operating temperature of 90°C and 70°C, which represents the reservoir and surface temperature, respectively. The properties of produced oil were further characterized by analyzing the composition based on its polarity, including saturate, aromatic, resin, and asphaltene. The results show that increasing injection pressures decrease resin and asphaltene fractions in produced oil. Furthermore, the proportions of asphaltene and resin fractions in the crude sample exhibit a significant decrease when conducted at a lower temperature in comparison to when carried out at a higher temperature. This study helps to explain how the displacement process by CO2 affects the properties of the produced oil.

Effect of oxidation kinetic aging on the adhesion behaviour of asphalt-aggregate interfaces from molecular view

ABSTRACT Asphalt oxidation kinetic aging effect on the adhesion behavior of asphalt-aggregate interfaces at atomistic scale was investigated in this study. The asphalts were aged at different aging durations. The sulfoxide and carbonyl functional group content as well as SARA fractions of the asphalts at different aging times were studied through the tests of Fourier Transform Infrared Spectroscopy (FTIR) and Saturate, Aromatic, Resin and Asphaltene (SARA) fractions. Asphalt molecular models of virgin, rapid-rate aged, slow-rate aged and full-aged were established based on SARA fractions and FTIR results, to construct asphalt quartz and asphalt-calcite interface systems at different aging stages. The simulation results showed that the nanostructure of asphalt is influenced by the aggregate type and asphalt oxidative aging. The growth rates of adhesion energy of asphalt-quartz and asphalt-calcite systems increase rapidly first and then slowly with aging time, but the growth rates are different. Meanwhile, the Van der Waals energy is the major energy source of adhesion energy, and the contribution of van der Waals and electrostatic energy to adhesion energy is different. The aging of asphaltene and resin promotes the adhesion ability to quartz or calcite, while the aging of aromatic components is not conducive and the saturate has almost no effect.

Liquid-Liquid equilibrium measurements analysis of synthetic multicomponent solvent (n-Pentane, n-Hexane, n-Heptane, Cyclo-Hexane, Toluene)/Bitumen System: Implications for solvent-aided in-situ bitumen extraction

Understanding the Liquid-Liquid Equilibrium (LLE) of multicomponent solvent/bitumen systems is pivotal in optimizing in-situ bitumen extraction. While Vapor-Liquid Equilibria (VLE) of solvent-bitumen systems has been extensively studied, LLE data and predictive models for these mixtures, especially those involving synthetic multicomponent solvents, are scarce. This study provides comprehensive LLE measurements of bitumen and a multicomponent synthetic solvent (n-pentane + n-hexane + n-heptane + cyclo-hexane + toluene) conducted under controlled equilibrium conditions at temperatures of 295 to 352 K, solvent concentrations up to 70 wt% at 1.291 MPa. Application of common correlation used in the construction of solvent-aided process fluid models exhibited average absolute relative deviations (AARDs) of 0.37 % for density and 8.87 % for viscosity. We identified the boundaries marking the shift from homogenous single-phase liquid to two-phase (LLE) states, which occurs within the synthetic multicomponent solvent concentration range of 50 to 60 wt%. We also successfully constructed calibration curves to measure solvent concentrations in both phase regions. The molecular weight distribution and saturates, aromatics, resins, and asphaltene (SARA) fractionation of both liquid phases were determined, highlighting that the heavy liquid phase is primarily asphaltene (∼46 wt%). The insights gained from the measurements and analysis find applications in designing and optimizing solvent-assisted thermal recovery processes for bitumen extraction.

Synthesis and functionalization of carbon nanospheres from asphaltene fraction for crude oil upgrading and viscosity reduction

Nanoparticles provide a promising, cost-effective eco-friendly solution to the challenges posed by heavy-oil reservoirs, significantly enhancing oil recovery rates by reducing viscosity without requiring extensive thermal inputs. In this study, carbon nanospheres (CNSs) and functionalized-CNSs nanofluids were prepared by incorporating surfactants (T80 or BMIMCl). These nanofluids were evaluated for their efficacy in upgrading crude oil, particularly focusing on viscosity-reduction. Rheological tests were conducted across varying shear rates (60–300 s−1) and concentrations (0.02–3 wt.%) to comprehensively assess the impact of these additives on the crude oil’s proprieties. The results showed a notable enhancement in crude oil viscosity reduction, with the following order observed: CNS-TiO2 < CNS-TiO2/DMIMCl < CNS-TiO2/T80, yielding reduction rates of 95%, 95.83%, and 97.08%, respectively, at an optimal dosage of 2.75 wt.% and a shear rate of 300 s−1. The surface functionalization of CNS particles and their crystallinity are the main mechanisms driving the reduction in oil viscosity. Moreover, the properties of the crude oil were investigated upon the utilization of CNS-TiO2/T80 nanofluid. It was found that this nanofluid led to a substantial reduction in sulfur content by 78.32% and a significant decrease in the percentage of heavier molecules, ranging from C12 to C35 and up to C36, with 47.76% and 97.98%, respectively.

Multicomponent Photocatalytic-Dispersant System for Oil Spill Remediation.

In the present work, the potential application of a fabricated halloysite nanotubes-Ag-TiO2 (HNT-Ag-TiO2) composite loaded with a binary surfactant mixture made up of lecithin and Tween 80 (LT80) in remediating oil spillages was examined. The as-prepared Ag-TiO2 that was used in the fabrication of the HNT-Ag-TiO2-LT80 composite was characterized by X-ray diffraction, Raman spectroscopy, UV-vis and diffuse reflectance spectroscopy, CV analyses, and SEM-EDX. The synthesized composite was also characterized by thermogravimetric analysis, Fourier-transform infrared spectroscopy, and scanning electron microscopy-energy dispersive X-ray spectroscopy. The synthesized composite was active in both the UV and visible light regions of the electromagnetic spectrum. The oil-remediating potential of the as-prepared composite was examined on crude oil, and aromatics and asphaltene fractions of crude oil. The composite was able to reduce the surface tension, form stable emulsions and smaller oil droplet sizes, and achieve a high dispersion effectiveness of 91.5%. A mixture of each of the crude oil and its fractions and HNT-Ag-TiO2-LT80 was subjected to photodegradation under UV light irradiation. The results from the GC-MS and UV-vis analysis of the photodegraded crude oil revealed that the photocatal composite was able to photodegrade the crude oil, aromatics, and asphaltene fractions of crude oil with the formation of intermediate photodegradation products depicting that the HNT-Ag-TiO2-LT80 has a potential as an oil spill remediation material.

A novel method for examining the influence of molecular and structural properties of the asphaltene fraction on the wettability change of the calcite surface

Asphaltene deposition in the porous media of the reservoir during the production life causes serious challenges with significant economic cost. From the point of view of proactive action to prevent the formation of such precipitates, today asphaltene inhibitors are widely used in the oil industry. The successful performance of inhibitors strongly depends on molecular structure of asphaltene. This study investigates the effect of molecular-structural properties of asphaltene in four crude oil samples on calcite surface wettability. The wettability of the calcite surface is evaluated with contact angle test and micromodel. The crude oil properties are determined using DHA (Detailed Hydrocarbon Analysis) and FTIR (Fourier Transform Infrared Spectroscopy) tests, while the molecular-structural properties of asphaltene are assessed using elemental analysis, FESEM (Field Emission Scanning Electron Microscopy), NMR (Nuclear Magnetic Resonance), and FTIR techniques. Based on FTIR analysis of oil samples, the higher polarity of samples B and G compared to samples F and A can be attributed to the presence of C = O carboxylic acid stretches. In addition, DHA analysis indicates that sample B, which contains heavier compounds comprising 27.4220 % of the C14+ compounds by weight, exhibits distinct characteristics. The FESEM images demonstrate a uniform and smooth spread surface morphology of the asphaltene samples. However, the elemental analysis does not establish a correlation between the heteroelement ratios of N/C, O/C, and S/C and asphaltene adsorption tendency. FTIR and NMR analyses suggest that the wetting properties observed on the surface are mainly attributed to the high aromatic and aliphatic compounds present in the asphaltene of sample B, while the polar compounds are less influential. The results reveal that crude oil sample B exhibits the highest percentage of damage to the porous medium caused by asphaltene deposition, with a rate of 36.18 % and a contact angle of 163.53 degrees. This indicates a wetter surface of the oil compared to other samples. Samples G and A follow with contact angles of 157.34° and 153.60°, respectively. On the other hand, sample F shows the lowest wettability change on the calcite surface with a contact angle of 144.77° and only 0.08 % damage to the porous medium.

Evaluation of rock and fluid intermolecular interaction between asphaltene and sand minerals using electrochemical, analytical spectroscopy and microscopy techniques

Long-time contact of heavy crude oil with rock leads to an adsorption phenomenon, which causes the rock surface to become oil-wet and appears as a barrier to the fluid flow in the porous media. However precise understanding of how asphaltene fractions influence sand wettability is lacking. The wetness of neat and asphaltene-aged sandstone was calculated using two relative permeability and contact angle methods. Then the molecular interaction between asphaltene and sand minerals was systematically analyzed using Fourier-transform infrared spectroscopy. Furthermore, the zeta potential was representative of electrostatic properties and surface charge alteration of the sand after these phenomena. Scanning electron microscopy with energy-dispersive X-ray (EDX) analysis also showed elemental mapping and dispersion of asphaltene particles on the rock surface. According to contact angle and EDX analyses of asphaltene samples, the contact angle rises from 115° to 141° by an increase in carbon adsorption on the sand surface from 8.23 to 41.56%. Spectroscopy results demonstrated that hydrogen-bonding, π-bonding, and sulfur-containing compounds such as sulfoxide improve asphaltene adsorption onto the sand surface. The higher the aromaticity index and hydrogen potential index of asphaltene, the greater the ability of asphaltene to change wettability. Adsorption of surface active components would make the surface charge of the sand more negative. The presence of nitrogen/sulfur-containing functional groups on the sand surface changed the electrostatic properties, as a sand surface coated with asphaltene would reduce the percentage of metal cations.

Probing the interaction between asphaltene-wax and its effects on the crystallization behavior of waxes in heavy oil via molecular dynamics simulation

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 asphaltene-wax 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 asphaltene-resin aggregates with a larger radius. Our results reveal the interaction mechanism between asphaltene-wax, and provide useful guidelines for the development of heavy oil.

Characteristics of Asphaltene Fractions Responsible for the Formation of Stable Water‑Oil Emulsions

Characteristics of Asphaltene Fractions Responsible for the Formation of Stable Water‑Oil Emulsions

Chemical kinetics of SARA fractions pyrolysis: Resins

This work presents a predictive and generally applicable approach to resin pyrolysis modeling. Resins extracted from heavy fuel oil 380 (HFO) and vacuum residue oil (VRO) were tested for elemental composition, chemical structure, thermal degradation behavior, and distribution of pyrolysis products using different state-of-the-art experimental techniques. The in-house experiments, together with extensive literature research, guided the formulation of five pseudo-components for the definition of a fuel surrogate. The atomic ratios of the surrogate molecules were defined to be able to replicate the elemental composition of all the data with their linear combination. This approach makes the model flexible and readily applicable to any resin sample just by knowing its elemental composition. The kinetics mechanism was developed by coupling each pseudo-component with a decomposition reaction pathway. The choice of the kinetics parameters was driven by the experimental information available. The model presented a satisfactory agreement with experimental data used for the validation. The kinetic model represents a step of a more comprehensive project aimed at reconstructing the chemical kinetics of heavy and residual oils as a combination of their saturate, aromatic, resin, and asphaltene (SARA) fractions.

Oil Deasphalting Using PAN Membranes with Small Pore Size

With the development of oil fields, the proportion of the highest molecular weight component, asphaltenes, increases in the composition of the extracted raw materials. The tendency of asphaltenes to aggregate causes a number of problems, which makes the problem of oil deasphalting relevant. In this work, studies were carried out on the separation of the asphaltene fraction from oil using PAN membranes. In order to reduce the pore size of membranes obtained by the phase inversion method, an additional component, acetone, was introduced into the spinning solution. The permeability of the resulting membranes for water is 37.6 ± 1.7 L/(m2 h atm), and for toluene, 25.3 ± 1.8 L/(m2 h atm), and the pore size is 4.6±0.5 nm. When filtering oil solutions diluted with toluene (1 g/L), the retention capacity of membranes for asphaltenes was 73 ± 4% and more than 95% if the oil content in the solution was more than 10 g/L. A study was made of the parameters of membrane clogging during the filtration of oil solutions in toluene. It is noted that when passing from toluene to oil solutions, the permeability of membranes decreases by 10 times. At the same time, the decrease in permeability is reversible, and when the oil solution was replaced with a pure solvent, the membrane restored up to 99% of its permeability.