Heavy Oil Fractions Research Articles

First field application of functionalized nanoparticles-based nanofluids in thermal enhanced oil recovery: From laboratory experiments to cyclic steam stimulation process

The increasing global demand for fossil fuels and the depletion of light crude oil reserves have driven the petroleum industry to focus on exploiting heavy crude oils, which present significant challenges in recovery and processing. To address these challenges, enhanced oil recovery (EOR) technologies are being developed, with a strong emphasis on advances in catalysis and nanomaterials science. This research significantly contributes to developing new technologies for petroleum exploitation by introducing a novel nanofluid designed to facilitate in-situ upgrading of heavy oil, improving its quality for downstream refining and fuel production. The nanofluid, engineered to enhance the productivity of a heavy oil reservoir under cyclic steam stimulation, targets improvements in oil recovery and fuel-quality indicators such as API gravity and viscosity. Laboratory tests demonstrated the nanofluid’s capability to reduce oil viscosity, improve oil mobility, and selectively interact with heavy oil fractions like resins and asphaltenes. Displacement tests simulating steam injection conditions showed an improvement in oil recovery, increasing from 56 % to 76 % after nanofluid application. The treatment also led to a notable increase in API gravity, from 11.6° to 29.2°, and a significant reduction in viscosity, from 39,987 cP to 104 cP, indicating enhanced crude oil quality, critical for refining and fuel production. Field trials in two wells in Colombia demonstrated the nanofluid’s practical effectiveness, with production increases averaging 97 % and incremental yields of 11,966 barrels in well A and 3213 barrels in well B. Post-treatment, the crude oil exhibited sustained improvements in quality, with API gravity increasing from 11.6° to 13.4° and viscosity decreasing from 39,987 cP to 11,734 cP. These results confirm the long-term durability of the nanofluid’s effects and its potential to enhance fuel production from heavy oil reservoirs. Additionally, the field trial indicated a 48 % reduction in operational costs, primarily due to decreased steam generation and lower CO2 emissions, highlighting the environmental and economic benefits of nanofluid technology for petroleum exploitation.

Innovations in residue upgrading for the Niger delta by transforming heavy oil fractions into high-value products: A state of the art review

This review discusses new innovations in residue upgrading technologies for the conversion of heavy oil fractions into high-value products, especially for Delta and Rivers States of the Niger Delta region. Recent works within the 2020-2024 period show that upgrading methods have been significantly developed; however, no prior work has been done regarding applying those upgrading techniques to the peculiar nature of crude oil from this region. The paper probes the environmental impacts of these technologies, emphasizing the need for localized assessment that would take into consideration the fragile ecosystems of Delta and Rivers States. It further assesses the economic viability of scaling up the implementation of advanced upgrading processes within the current refining infrastructure. The discussion covers variable quality heavy oil in these regions and what that does to upgrading efficiency, how to integrate these technologies into the current refining practices, underlines the potential socio-economic advantages for the local communities through the creation of jobs and enhancing the skills of those communities to underscore the importance of these innovations for sustainable development. The review establishes that in such siamese twin areas, further research is needed to ensure that heavy oil resources in Delta and Rivers States are utilized effectively while ensuring that there is a minimal environmental impact from the extraction process.

Spatial distribution of remaining movable and non-movable oil fractions in a depleted Maastrichtian chalk reservoir, Danish North Sea: Implications for CO2 storage

Depleted oil and gas fields constitute potentially important storage sites for CO2 in the subsurface, but large-scale injection of supercritical (sc) CO2 in chalk has not yet been attempted. One of the risks is the adverse effect of the substantial amount of remaining oil in the chalk reservoirs on scCO2 injection. In order to counter an undesired effect on injectivity, a fundamental understanding of the spatial distribution and quantity of the movable, semi-movable, and non-movable oil, and solid bitumen/asphaltenes fractions of the remaining oil is critical. In this study a combination of organic geochemistry (gas chromatography of the saturated fraction and programmed pyrolysis), and reflected light microscopy was applied to evaluate and measure the spatial distribution, volume, and saturation of different oil fractions in a well-defined reservoir interval of a waterflooded Maastrichtian chalk reservoir in the Danish Central Graben, North Sea. A total of 127 samples from a slightly deviated vertical well and two ∼5 km-long horizontal wells from the Halfdan and Dan fields were analyzed. An original uneven distribution of oil saturation and composition or different production efficiency of different levels in the reservoir may account for variations in the total oil and oil fraction saturations. Gas chromatography shows that the solvent extractable oil is quite similar in composition, characterized by a dominance of polar compounds and a high content of asphaltenes. Extended slow heating (ESH) pyrolysis reveals that most of the remaining oil saturation consists of semi-movable oil and total non-movable oil (non-movable oil plus solid bitumen/asphaltenes). Reduced oil gravity values (API) are related to evaporation loss of the lightest hydrocarbon fraction during core storage and increase of the relative proportion of the heavier oil fractions by waterflooding during production. Microscopy disclosed three forms of oil: i) Patchy distributed lighter, movable oil showing a bluish fluorescence, ii) Brownish staining with a dark orange to brownish fluorescence, and iii) Dark brown non-fluorescing oil and black solid bitumen/asphaltenes occurring in microfossils and along deformation bands and stylolites, constituting the heavy non-movable oil fractions. There is a general correlation between bulk rock porosity and the total non-movable oil saturation. It thus appears that the heavy non-movable oil fractions preferentially occur in association with low-permeability heterogeneities within high-permeability stratigraphic intervals. These intervals appear to favor accumulation of non-movable oil and solid bitumen/asphaltenes and may carry a higher risk for impeding scCO2 flow.

Study of the co-pyrolysis behavior and bio-oil characterization of walnut shell and polyethylene by thermogravimetric analyzer and bubbling fluidized bed

In the present work, co-pyrolysis experiments of walnut shell (WS), polyethylene (PE) and their blends were performed in the thermogravimetric analyzer and lab-scale bubbling fluidized bed reactor, to clarify co-pyrolysis behaviors, synergy interactions and pyrolysis oil properties. Besides, the HZSM-5 zeolite was used as the catalyst and its catalytic characteristics were studied. Results indicated that as PE mass ratio rose from 0 to 100 %, the initial temperature monotonically increased from 265.4 to 417.3 °C, while its terminal temperature progressively decreased from 668.3 to 527.5 °C, suggesting that the addition of PE was able to accelerate the pyrolysis of samples. The co-pyrolysis of blends was distinguished into three stages, with a negative interaction observed in the first stage and positive interactions found in second and third stages. Besides, in the bubbling fluidized bed experiments, the liquid phase product yield first elevated and then reduced with rising temperature, and a high temperature promoted the degradation of oxygen-containing compounds and enhanced aromatics generation. The synergistic interaction in the co-pyrolysis of WS and PE declined the liquid phase product yield while elevating the gas phase product yield. On the other hand, blending with PE facilitated the generation of alkanes and olefins, while inhibiting the contents of oxygen-containing components and aromatics, and simultaneously, the heavy oil fraction was increased. Finally, the carbon deposited on the surface of catalysts was amorphous carbons, and could be removed by oxidation process, whereas its catalytic properties progressively declined with rising cycle number, leading to a downtrend of aromatics and olefins and an opposite trend for oxygen-containing components.

Water-accommodated fractions of heavy and light oils impact DNA integrity, embryonic development, and immune system of Japanese medaka at early life stages.

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous contaminants generally found in complex mixtures. PAHs are known to cause pleiotropic effects on living organisms, including developmental defects, mutagenicity, carcinogenicity and immunotoxicity, and endocrine disruptions. The main goal of this study is to evaluate the toxicity of water-accommodated fractions (WAFs) of oils in two life stages of the Japanese medaka, larvae and juveniles. The deleterious effects of an acute exposure of 48h to two WAFs from Arabian light crude oil (LO) and refined oil from Erika (HO) were analyzed in both stages. Relevant endpoints, including ethoxy resorufin-O-deethylase (EROD) activity, DNA damage (Comet assay), photomotor response, and sensitivity to nervous necrosis virus (NNV) infection, were investigated. Larvae exposed to both oil WAFs displayed a significant induction of EROD activity, DNA damage, and developmental anomalies, but no behavioral changes. Deleterious effects were significantly increased following exposure to 1 and 10μg/L of LO WAFs and 10μg/L of HO WAFs. Larval infection to NNV induced fish mortality and sharply reduced reaction to light stimulation. Co-exposure to WAFs and NNV increased the mortality rate, suggesting an impact of WAFs on fish defense capacities. WAF toxicity on juveniles was only observed following the NNV challenge, with a higher sensitivity to HO WAFs than to LO WAFs. This study highlighted that environmentally realistic exposure to oil WAFs containing different compositions and concentrations of oil generated high adverse effects, especially in the larval stage. This kind of multi-marker approach is particularly relevant to characterize the toxicity fingerprint of environmental mixtures of hydrocarbons and PAHs.

Transferable preference learning in multi-objective decision analysis and its application to hydrocracking

Hydrocracking represents a complex and time-consuming chemical process that converts heavy oil fractions into various valuable products with low boiling points. It plays a pivotal role in enhancing the quality of products within the oil refining process. Consequently, the development of efficient surrogate models for simulating the hydrocracking process and identifying appropriate solutions for multi-objective oil refining is now an important area of research. In this study, a novel transferable preference learning-driven evolutionary algorithm is proposed to facilitate multi-objective decision analysis in the oil refining process. Specifically, our approach involves considering user preferences to divide the objective space into a region of interest (ROI) and other subspaces. We then utilize Kriging models to approximate the sub-problems within the ROI. In order to enhance the robustness and generalization capability of the Kriging models during the evolutionary process, we transfer the mutual information between the sub-problems in the ROI. To validate the effectiveness as well as efficiency of our proposed method, we undertake a series of experiments on both benchmarks and the oil refining process. The experimental results conclusively demonstrate the superiority of our approach.

Enhancing refinery heavy oil fractions analytical performance through real-time predicative modeling.

This study introduces a suite of robust models aimed to advance the determination of physiochemical properties in heavy oil refinery fractions. By integrating real-time analytical technique inside the refinery analysis, we have developed a single analyzer capable of employing six partial least square regression equations. These designed models enable to provide real-time prediction of critical petroleum properties, such as sulfur content, micro carbon residues (MCR), asphaltene content, heating value, and the concentrations of nickel and vanadium metals. Specifically tailored for heavy oil in refinery feeds with an American petroleum institute (API) gravity range of 3° to 32° and sulfur content of 2.8 to 5.5 wt%, the models streamline the analysis process within refinery operations, bridging the gap between catalytic and non-catalytic processes across refinery units. The accuracy of our physiochemical prediction models has been validated against American Society for Testing and Materials (ASTM) standards, demonstrating their capability to deliver precise real-time property values. This approach not only enhances the efficiency of refinery analysis but also sets a new standard for the monitoring and optimization of heavy oil processing in real-time approach.

Исследование условий теплового самовозгорания тяжелых углеводородов (на примере битумов) на развитой поверхности волокнистой негорючей теплоизоляции

Experimental and analytical studies of thermal spontaneous combustion of substances of heavy oil fraction distilling (fuel oil, bitumen, tar) when contacting with a developed surface of non-flammable fibrous (such as slag and glass wool, fiberglass) material of thermal insulation of a tank have been conducted based on the example of bitumen. Experimental studies and calculations have shown that on the developed surface of fibrous materials impregnated with bitumen, the process of bitumen decomposition involving the generation of thermal and thermal-oxidative degradation products of heavy hydrocarbons able to auto-ignite (ignite spontaneously on the developed non-flammable fibrous surface) or ignite in case of availability of ignition source is possible under certain conditions at relatively low temperatures (~120 °С and lower), i.e., at temperatures close to the maximum process temperature (~180 °С) and significantly lower temperatures compared to the temperature of spontaneous ignition of bitumen (~330–380 °С). The calculations of thermal flows have shown how (via what methods) the thermal conductivity of thermal insulation impregnated with bitumen can be improved and, thereby, the probability of its spontaneous combustion can be reduced or prevented. Based on experimental and analytical studies and calculations, the proposals for preventing spontaneous combustion of thermal insulation materials of storage tanks for bitumen and other hydrocarbons of high distillation of petroleum products have been formulated.

Hydrocracking of a HDPE/VGO Blend: Influence of Catalyst-to-Feed Ratio on Fuel Yield and Composition

The effects that the catalyst-to-feed ratio have on the yields of products and composition of the naphtha and light cycle oil (LCO) fractions in the hydrocracking of a blend composed of high-density polyethylene (HDPE) and vacuum gasoil (VGO) using a PtPd/HY catalyst were assessed. The hydrocracking runs were carried out in a batch reactor fixing the following operation conditions: 420 °C, 80 bar, 120 min and an HDPE-to-VGO ratio of 0.2 gHDPE gVGO−1, varying the catalyst-to-feed mass ratio within the 0.05–0.1 gcatalyst gfeed−1 range. The obtained results exposed that a catalyst-to-feed mass ratio of 0.075 gcatalyst gfeed−1 provided the best results, since the conversion of the heavy cycle oil (HCO) fraction and of the HDPE offered quite high values (73.1 and 63.9%, respectively) without causing an excessive overcracking in the form of gas products (the yield of gases was of 25%). Moreover, an interesting yield of naphtha (37.0 wt%) with an RON within the commercial standards (92.5) was obtained. With regard to coke formation, not-so-developed structures were formed for a catalyst-to-feed mass ratio of 0.075 gcatalyst gfeed−1, easing their combustion and presumably extending the lifespan of the catalyst.

Synthesis of superhydrophobic carbon sphere by pyrolysis of heavy oil fraction of coal tar/ferrocene mixture and their magnetic nanostructure

This present work describes the ferrocene-catalyzed conversion of heavy oil fraction of coal tar to carbon sphere aggregate films in the form of necklace-like carbon spheres, carbon sphere‑carbon nanotube composite, and pomegranate-like carbon spheres by chemical vapor deposition (CVD). Necklace-like carbon spheres exhibit hydrophobic surfaces, whereas pomegranate-like carbon spheres-CNT composites and pomegranate-like carbon spheres display superhydrophobic surfaces. The as-prepared hydrophobic and superhydrophobic surfaces were carefully characterized by Scanning Electron Microscopy (SEM), High-Resolution Transmission Electron Microscopy (HRTEM), Atomic Force Microscopy (AFM), and Magnetic Force Microscopy (MFM) to confirm the effect of geometric carbon aggregates with thermally decomposed ferrocene (FeCp2) catalysts on their magnetic nanostructure. The surface chemistry as well as oxidation resistance was studied by Fourier Transform Infrared spectroscopy (FTIR), Raman spectroscopy, and Thermal Gravimetric Analysis (TGA). FeCp2 catalyst concentration in the heavy oil fraction of coal tar was observed to have a direct correlation with morphology, disordered level of graphitic structure, magnetic domain pattern arrangement, and thermal oxidation resistance of as-produced carbon sphere aggregate.

Study of the N-Paraffins Addition Effect on the Effectiveness of Depressant Additives for the Production of Low-Freezing Diesel Fuels

The use of depressant additives is the most common method for producing diesel fuels with improved low-temperature properties. However, the depressants effectiveness largely depends on the composition of the diesel fuel, in particular on the content of n-paraffinic hydrocarbons, which to the greatest extent determine the low-temperature properties of the fuel. The work revealed the regularities of the n-paraffins addition influence on the depressant additives effectiveness. It was found that the addition of n-paraffins to blends of diesel fuels with depressants in low concentrations (0.05–0.50% wt.) enhances the depressants effectiveness in relation to the cold filter plugging point: maximum at 6–16 °C depending on the diesel fuel sample. It is shown that the effect is observed for DF of various compositions, various depressants, and also n-paraffins of various compositions. It was established that the positive effect of adding n-paraffins increases with the heavier added n-paraffins. Recommendations have been developed for obtaining diesel fuels with improved low-temperature properties and enhancing the depressant additives effectiveness: for a sample of straight-run diesel fuel F1, it is recommended to use a blend of fuel, depressant A1 and 0.50% wt. n-paraffins, separated from heavy gasoil; for a sample of straight-run diesel fuel F2, it is recommended to use a blend of fuel, depressant A2 and 0.50% wt. n-paraffins, separated from heavy gasoil or a blend of fuel, depressant A1 and 0.05% wt. n-paraffins, separated from highly paraffinic oil fraction. The revealed patterns and the developed recommendations will allow increasing the production of low-freezing DF brands, and also offer a resource-efficient option for using heavy gas oil fractions. The results obtained in the work contribute to expanding the understanding of the mechanism of interaction between diesel fuel hydrocarbons and the active ingredients of depressant additives.

Oxidative desulfurization of VGO using carbon nanostructures created by NTP-pyrolysis of fuel oil

Desulfurization of heavy oil fractions is complicated due to the high content of stable polycyclic systems including thiophene ring. Therefore, there is a need to develop new efficient and cost-effective desulfurization methods. The catalytic activity of carbon structures obtained by plasma-chemical pyrolysis of hydrocarbon feedstock (fuel oil, non-hydrorefined vacuum gas oil and catalytic cracking residue) was investigated in this work. The catalytic activity of carbon structures was investigated in relation to the process of oxidative desulfurization of light vacuum gas oil. The oxidation process was carried out at 60°C using ultrasonic dispersion for 1 minute. The oxidation products were extracted with furfural. As a result of oxidation followed by extraction, the sulfur content in gas oil decreased from 0.64 to 0.24% wt.

Nitrogen-containing compounds of Kazakhstan petroleum vacuum gas oil

Relevance. The need to accumulate data on nitrogen-containing compounds of heavy fractions, the share of which in secondary oil refining is steadily increasing every year. With the weight of raw materials the amount of sulfur-, nitrogen- and oxygen-containing components in it increases. The high content of heteroatomic compounds has a negative impact on catalytic processing, the quality and performance characteristics of the products obtained, and the environment. One of the widespread processes for upgrading crude oil, in particular, vacuum gas oil, is hydrotreating. However, during the catalytic hydrodesulfurization of heavy distillates the reactions of hydrogenolysis of organic sulfur compounds are inhibited in the presence of nitrogen-containing compounds. At the same time, the degree of hydrodenitrogenation of heavy oil fractions is relatively low. It is known that petroleum nitrogen-containing compounds are divided into nitrogenous bases titrated with acid solutions and nonbasic nitrogen compounds. Nitrogenous bases are represented mainly by alkylbenzo- and alkylnaphthenobenzo derivatives of pyridine. Nonbasic compounds may include benzologs of pyrrole and amides. Determining the composition of nitrogen-containing compounds in vacuum gas oil and studying their transformations during hydrotreatment is an important and actual problem. Aim. Comparative study of high- and low-molecular nitrogenous bases and nonbasic nitrogen-containing compounds of vacuum gas oil of Kazakhstan oil before and after hydrotreating. Objects. Samples taken before and after the catalytic hydrotreatment of vacuum gas oil from Kazakhstan oil. Methods. Hydrotreatment, elemental analysis, potentiometric titration, benzene cryoscopy, IR and 1H NMR spectroscopy, structural group analysis. Results. The paper introduces a comparative characteristic of the composition and structure of high and low molecular weight nitrogenous bases from the original and hydrotreated vacuum gas oil. Under the conditions of hydrotreatment, the total removal of nitrogen was 6.56 wt %, and the content of Nbas. decreased by 36%. At the same time, nitrogenous bases in the hydrotreated product are characterized by low molecular weights. Using IR spectroscopy, similar structural fragments were identified in the nitrogen compounds of the original and hydrotreated vacuum gas oil: pyridine rings (1573–1574 cm–1), carboxylic (3209–3225 and 1701–1709 cm–1) and sulfoxide (1032–1033 cm–1) groups. Among the nitrogen-containing compounds of the original vacuum gas oil, amides (1647–1648 cm–1) were identified, which are absent in the composition of nitrogen-containing compounds of the hydrotreated vacuum gas oil. Hydrocarbon skeletons of molecules include aromatic (1599–1602 cm–1) and aliphatic fragments (2860–2960 and 1454–1460, 1377, 723–727 cm–1). In accordance with the results of the structural group analysis, the averaged molecules of high and low molecular weight nitrogenous bases of the original and hydrotreated vacuum gas oil are represented by naphthenoaromatic structures with different alkyl framing. The differences observed between the values of individual structural parameters of the nitrogenous bases average molecules of the original and hydrotreated vacuum gas oil may indicate the compounds transformations under study during hydrotreatment.

ReaxFF Molecular Dynamics Study on the Microscopic Mechanism for Kerogen Pyrolysis.

Kerogen is mainly composed of carbon, hydrogen, and oxygen, which are the main components of crude oil and gas. The pyrolysis of kerogen is an efficient method to generate clean energy. In the present work, the pyrolysis reaction process of three types of kerogen is simulated using ReaxFF molecular dynamics (MD) methods to study the microscopic mechanism and the distribution of products. The results indicated that the pyrolysis products of the three types of kerogen significantly depend on the molecular structures, temperature, and reaction time. As the temperature increases, the gaseous hydrocarbon and the light and heavy oil fractions decreased, where small molecular fragments polymerized to form new molecular fragments. For an isothermal temperature, with the reaction proceeding, some component polymerization of the pyrolyzed fragments occurred, resulting in the generation of new light oils and heavy oils. Moreover, quantum chemical analysis was employed to reveal the kerogen pyrolysis mechanism. First, the weak bonds such as C-O, C-N, and C-S structures were decomposed to generate large carbon and some heavy shale oil fragments. Second, the cycloalkanes and long-chain alkanes were decomposed to generate a large amount of light shale oil and gaseous hydrocarbons. Finally, the decomposition of C═C in the aromatic ring, the secondary decomposition of light and heavy shale oils, and the further decomposition of short-chain alkanes occurred. In addition, the production of hydrogen (H2) occurred at the late stage of the pyrolysis reaction. Hydrogen radicals were formed by the decomposition of C-H bonds and subsequently collided with each other, resulting in the formation of H2 molecules. The pyrolysis and chemical analysis of kerogen can clearly determine the type and content of hydrocarbon substances, providing scientific data for exploration, development, and utilization of shale gas and shale oil.

Movable and non-movable hydrocarbon fractions in an oil-depleted sandstone reservoir considered for CO2 storage, Nini West Field, Danish North Sea

The Paleocene–Eocene quartz- and glauconite-rich reservoir sandstones of the depleted Nini West oilfield in the Siri Canyon, Danish North Sea, are considered a CO2 storage site. Mobilization of the remaining oil in the reservoir by the injected supercritical CO2 (scCO2) can cause oil displacement and potentially clogging of pore throats by the non-soluble heavy oil fraction. This study focuses on the movable and non-movable oil and solid bitumen/asphaltenes fractions present in the Nini West reservoir, including the effect of scCO2 injection on the residual oil. The residual oil in 14 samples from 13 core plugs from the oil-leg of the Nini-4 well was analyzed, as well as the extracted oil from preserved samples and the Nini stock tank oil (STO). The samples were acquired from preserved, cleaned, restored, and scCO2 flooded core plugs and were analyzed by organic geochemistry, including extended slow heating pyrolysis (ESH®) and organic petrography. The STO is paraffinic with a fairly high asphaltene content, and the preserved samples show that the residual oil occurs in association with glauconite clasts. The extracted oil consists mainly of movable oil fractions and a smaller amount of non-movable oil and solid bitumen/asphaltenes. The organic solvents used in different cleaning methods could remove most of the oil in the samples, but none of them can completely remove the solid bitumen/asphaltenes adhered to the glauconite clasts. The orange-brownish fluorescing solid bitumen/asphaltenes occur in the interior of the glauconite clasts, as coatings on the surface, and in small cracks in the surface, as well as between the laminae of glauconised mica. A sample from a cleaned core that has been restored to original wettability condition while controlling oil and brine saturations, and aged for a month at reservoir conditions, has an oil composition akin to the preserved samples. By scCO2 flooding, the movable oil fractions are entirely removed while the solid bitumen/asphaltenes coatings and remnants in the interior of the glauconite clasts are not mobilized. The presence of solid bitumen/asphaltenes in the organic solvent cleaned samples and in the scCO2 flooded sample suggests that these compounds are highly non-movable. Furthermore, a low proportion of heavy non-movable oil in the scCO2 flooded samples indicates minor asphaltenes precipitation, perhaps due to the high permeability and homogeneity of the sandstones.

Research on azeotropic breaking extraction technology for High-Value chemicals from wash oil

In response to the challenge of achieving high-purity separation within a mixture containing acenaphthene, dibenzofuran, fluorene, and biphenyl in coal tar wash oil fractions, the azeotropic behavior of this mixture was investigated through phase equilibrium experiments to elucidate the azeotropic system. Once the azeotropic system was identified, attention shifted to intermolecular forces, and simulation calculations utilizing the Lennard-Jones potential energy function were employed to reveal the mechanism underlying high-purity separation in the azeotropic system. Building upon this foundation, the feasibility of solvent crystallization was explored as a means to break the azeotrope and achieve high-purity separation. This involved a thorough analysis of the intermolecular interactions between the crystallization solvent and the mixture system. Ethanol, methanol, and pentanol were chosen as potential solvents for conducting solvent crystallization experiments.Results demonstrate that ethanol performs admirably within the solvent crystallization method, exhibiting a high degree of crystallization selectivity for acenaphthene. On the other hand, pentanol demonstrates advantages in the separation and crystallization for removing biphenyl. Using ethanol as the solvent for crystallization, the acenaphthene content can be refined to 99.17%, while the biphenyl content can be reduced to a mere 0.002%. These findings underscore the effectiveness of ethanol as a solvent in effectively addressing the azeotropic challenge arising from the coexistence of biphenyl and acenaphthene, ultimately achieving an efficient separation of the targeted substances. Considering both crystallization selectivity and yield, ethanol emerges as the most suitable crystallization solvent for this intricate multi-component system. This study presents a practical solution for the efficient separation of acenaphthene, dibenzofuran, fluorene, and biphenyl—all of which constitute azeotropic systems within the heavy distillate fraction of wash oil.

Development of computational approach for calculation of hydrogen solubility in hydrocarbons for treatment of petroleum

For hydrogenation process, knowing the solubility of hydrogen (H2) in hydrocarbons is critical to improve the efficiency of process. We investigated the H2 solubility computation in four heavy crude oil feedstocks using machine learning techniques. Temperature, pressure, and feedstock type were considered as the inputs to the models, while the hydrogen solubility was the sole response. Specifically, we employed three different models: Support Vector Regression (SVR), Gaussian process regression (GPR), and Bayesian ridge regression (BRR). To achieve the best performance, the hyper-parameters of these models optimized using the whale optimization algorithm (WOA). We evaluated the models using a dataset of solubility measurements in various feedstocks, and we compared their performance based on several metrics. Our results show that the WOA-SVR model tuned with WOA achieves the best performance overall, with a RMSE of 1.38 × 10−2 and an R-squared of 0.991. These findings suggest that machine learning techniques can provide accurate predictions of hydrogen solubility in different feedstocks, which could be useful in the development of hydrogen-related technologies. Besides, the solubility of hydrogen in the four heavy oil fractions are estimated in different ranges of temperatures and pressures of 150 °C–350 °C and 1.2 MPa–10.8 MPa, respectively.

Enhancement of H2 and light oil production and CO2 emission mitigation during co-pyrolysis of oily sludge and incineration fly ash

The proper treatment and utilization of oily sludge (OS) and incineration fly ash (IFA) remains a significant challenge due to their hazardous nature. To attain effective recovery of petroleum hydrocarbons and synergistic disposal, this study investigated the co-pyrolysis of OS and IFA, resulting in successful energy recovery, CO2 mitigation, and heavy metal immobilization. Results revealed that the peak ratio of light oil to heavy oil fractions reached 179.42% with 20 wt% IFA addition, accompanied by the highest aromatic hydrocarbons selectivity of 30.72% and the lowest coke yield of 106.13 mg/g OS under the optimal temperature of 600 °C. In-depth analysis indicated that IFA inhibited the poly-condensation of macromolecular PAHs and promoted their cracking into light aromatic hydrocarbons. The addition of 50 wt% IFA significantly increased H2 yield (21.02 L/kg OS to 60.95 L/kg OS) and facilitated CO2 sequestration due to its higher content of Ca-bearing minerals. Moreover, high IFA ratios promoted the reduction of Fe species in OS to a low-valence state. Heavy metals in co-pyrolysis char were well immobilized into stable fractions with lower environmental risks. This work highlights the potential of co-pyrolysis as a viable approach for simultaneous disposal of multiple hazardous wastes and offers new insights for their utilization.

Assessment of asphaltene and resin fractions in crude oil using laser-induced fluorescence spectroscopy based on modified Beer-Lambert (LIFS-MBL)

Crude oil is one of the most significant petrogenic sources of polycyclic aromatic compounds (PACs). These substances play an essential role in the pollution of the marine environment. Therefore, the rapid identification of this pollutant source and its fractions is vital. For this purpose, a fast and on-site method of laser-induced fluorescence spectroscopy based on modified Beer-Lambert (LIFS-MBL) is proposed here using solvent densitometry. Three optical parameters of the self-quenching (K), the extinction (α), and the peak concentration (Cp) are experimentally extracted from MBL graphs. Note that the parameters above are known to be unique characteristics of various crude oils. The corresponding compounds are generally classified into saturate, aromatic, resin, and asphaltene fractions, abbreviated as SARA. Differentiation among these fractions is achieved using the LIFS-MBL method by selecting the optimal excitation wavelength at 405 nm. This line effectively rules out the light aromatic rings and focuses on heavy fractions. The correlation of optical parameters with heavy oil fractions is verified according to analysis of variance. Statistical relations are proposed to calculate crude oil fractions values. The values of light fractions including saturate and aromatic components can also be determined by the heavy fractions. In this method, the test time is notably reduced from four days using the standard methods to less than half an hour according to the presented LIFS-MBL technique.

Development of a simple and efficient oil-soluble nanocatalytic system for aquathermolysis upgrading of heavy crude oil

Catalytic aquathermolysis is one of the key and cost-effective chemical method for recovering heavy oil. This process transforms the asphaltene and resin compounds of the oil into lighter fractions. Oil-soluble transition metal-based catalysts have been reported as efficient catalysts that improve the viscosity reduction efficiency of the aquathermolysis process. Previous studies have mainly focused on using long alkyl chains as oil-soluble ligands to prepare the catalysts. However, aromatic ligands that effectively interact with asphaltene and resin fractions have not been extensively studied. In other words, the molecular structure of ligand used in the catalyst synthesis significantly changes its activity in aquathermolysis. This study aims to fill this gap using catechol as a novel ligand to develop oil-soluble catalyst (Ni-OSC), which can interact with heavy oil fractions during aquathermolysis. Ni-OSC decreased the content of resin and asphaltene by 32.1% and 26.5%, respectively, and increased the amounts of saturated and aromatic hydrocarbons by 19.6% and 22.9%, respectively, compared to heavy oil. Moreover, a GC–MS study indicated that low molecular weight hydrocarbons in the composition of heavy oil increased, and the relative content of alkanes raised to 79% in the presence of Ni-OSC. The catalyst also increased the concentration of alkylbenzenes and naphthalenes in the composition of aromatic compounds, improving the quality and recovery of heavy oil. Furthermore, the viscosity of heavy oil was considerably reduced, and a maximum hydrogen to carbon ratio of 2.03 was observed in Ni-OSC system. To the best of our knowledge, this is the highest reported hydrogen-to-carbon ratio for catalytic aquathermolysis of heavy oil using oil-soluble catalysts.