Modeling and optimization of shape selective separation of petrochemical light hydrocarbon mixtures using zeolites

For in vitro biodegradation studies, hydrocarbons are typically incorporated into culture media. However, the absence of sterilization protocols presents a challenge. The diesel is a non-sterile complex hydrocarbon mixture that is difficult to sterilize using conventional methods. This study aimed to develop a simple and effective method for diesel sterilization that preserves its integrity to allow its use in culture medium. Two sterilization approaches were tested: UV irradiation (15 and 30min) and filtration through polypropylene membranes. Results showed that UV sterilization of diesel (B7 blend) requires a longer irradiation time, which may alter its chemical composition. Filtration was the most effective method to achieve the sterilization of the hydrocarbon. This technique enabled subsequent diesel assimilation assays. This work proposes an easy-to-implement reproducible sterilization method, which is crucial for accurately assessing microbial degradation and for advancing laboratory-based research in bioremediation. We also proposed diesel as a possible model for studying complex hydrocarbons.

Tight oil reservoirs are currently a hot topic in petroleum exploration and development. However, due to the low porosity and low permeability of reservoirs and the lack of external energy supplementation, there is a significant mismatch between resources and production in tight oil. Mining and experimental studies have shown that CO2 and gaseous hydrocarbons have a high injectivity and effective oil displacement effect in tight oil reservoirs. Currently, research is mostly focused on a single energy supplement medium, and whether CO2 hydrocarbon mixtures can more effectively improve oil recovery needs to be further studied. The features of crude oil expansion capacity and interaction energy changes following various fluid interactions were investigated via molecular dynamics simulation techniques in response to the ambitious comprehension of the mechanistic changes underlying the CO2–CH4 synergistic effect during the development of tight oil reservoirs. The research results indicate that the expansion and diffusion abilities of crude oil are improved after being treated with pure CO2, CO2-CH4 (9:1), CO2-CH4 (7:3), and CO2-CH4 (1:1), and enhanced with increasing CO2 content in the injected fluid.

In pursuit of cost-efficient adsorbent materials for capturing acetylene (C2H2) from mixtures of C2 hydrocarbons and CO2, we have designed a novel 3D framework Co7-Me·S using inexpensive isonicotinic acid (Hina) and methyl-modified isophthalic acid (H2Me-ip) as mixed linkers under hydrothermal synthesis conditions. Co7-Me·S exhibits excellent air and water stability. Its abundant carboxylate oxygen atoms and coordinated water molecules can form multiple hydrogen bonds with C2 hydrocarbon molecules. Breakthrough tests and GCMC simulations confirm that the activated Co7-Me can capture C2H2 molecules from C2H2/C2H4, C2H2/CO2, and C2H2/C2H4/CO2 mixtures and simultaneously capture C2H2 and C2H6 from a three-component C2 hydrocarbon mixture, achieving one-step purification of C2H4. Moreover, the successful acquisition of single-crystal structure data with C2H2 guest molecules further confirmed the material's high selectivity for C2H2 guest molecules.

CO2 injection for enhanced oil recovery (EOR) and geological carbon sequestration (GCS) in shale reservoirs offers a promising win-win strategy. Yet, the mechanisms by which CO2 flooding and huff-and-puff (HNP) mobilize multicomponent shale oil in inorganic nanopores remain unclear, particularly regarding their respective contributions to oil recovery and CO2 storage. Here, we employ molecular dynamics (MD) simulations to compare CO2 flooding and HNP in calcite dead-end nanopores saturated with a multicomponent hydrocarbon mixture. We analyze interfacial and transport behaviors, extract localized molecular clusters to quantify self-diffusion coefficients, and examine the roles of flood and flowback pressures. Results show that flooding promotes greater CO2 penetration into nanopores but suppresses counter-current hydrocarbon migration, limiting swelling-driven recovery. In contrast, HNP enables CO2 diffusion during the huff stage and reverse pressure gradients during the puff stage, which enhance oil swelling and achieve higher recovery at the expense of lower storage efficiency. Elevated CO2 density increases the diffusion coefficients of all components, underscoring the critical roles of pressure gradients and molecular transport. By extracting localized molecular clusters, we further obtained pressure-dependent diffusion bounds for CO2 and hydrocarbons and quantify injection and flowback pressure windows that jointly optimize oil recovery and the CO2 storage efficiency. On this basis, we propose a well-count-agnostic and field translatable hybrid method that achieves 60.44% oil recovery and 47.18% CO2 storage efficiency. These findings provide molecular-scale guidance for full-process CCUS design in unconventional reservoirs.

Abstract In this work, we report hydrate phase equilibria data for CO₂ + H₂O + C 7 H 16 + C 9 H 20 + C 16 H 34 systems with TBAB () and its modelling using a modified Chen–Guo model, which incorporates a modification to the Helmholtz molar free energy term and a polynomial equation in terms of temperature and/or solubility of the compounds. The experimental data were obtained using the non‐visual isochoric method by pressure search over a temperature range of 273.69–292.03 K and a pressure interval of 1.32–4.59 MPa using several hydrocarbon mixtures (C 7 H 16 + C 9 H 20 + C 16 H 34 ) with mass fraction composition, namely (). The combined experimental uncertainties were estimated for temperature and pressure conditions to be 0.15 K and 0.02 MPa, respectively, while the relative standard uncertainty in composition (mass fraction) was 0.0020. The present modified model represented quite well the measured hydrate‐phase equilibria data, yielding an average absolute percentage deviation () of 0.033% (without TBAB) and 0.023% (with TBAB) meanwhile a maximum absolute percentage deviation () of 0.085% (without TBAB) and 0.044% (with TBAB).

Exploring cluster formation in CO₂ + hydrocarbon mixtures: From binary to ternary systems

Systematic performance assessment of double-stage high-temperature heat pumps based on zeotropic mixtures of natural hydrocarbons

Summary Retrograde gas condensation is an intriguing and seemingly counterintuitive phase behavior phenomenon in which some gas mixtures condense as the pressure decreases at certain regimes above the critical temperature. This work aims to provide an explanation that bridges the gap between phenomenological observations and microscopic mechanisms using thermodynamic modeling and molecular dynamics (MD) simulation. Phase envelopes for a selection of binary hydrocarbon mixtures have been generated and compared with experimental results using the Peng-Robinson (PR) equation of state (EOS). We also used MD simulation in the NVT ensemble to simulate the constant composition expansion of a ternary methane (C1), normal butane (nC4), and normal decane (nC10) mixture; the intermolecular energies and other structural and transport properties were computed from the MD simulations to elucidate the retrograde condensation behavior. The optimized potentials for liquid simulations-all atom (OPLS-AA) force field was used along with the leap-frog algorithm to integrate Newton’s equations of motion with the velocity rescaling thermostat to maintain the temperature. EOS modeling was in good agreement with experimental data for the studied binary mixtures. Additionally, EOS modeling was used to showcase the differences between the critical temperature and cricondentherm of different binary mixtures; this showcases the extent of the negative slope region in the phase envelope, which is associated with retrograde condensation. MD simulations revealed that the intermolecular interaction energies (IEs) among heavier hydrocarbon components with low vapor pressures increase as pressure decreases at certain regions above the critical temperature and below the cricondentherm. Gas condensate systems typically exhibit methane mole fractions of 0.6–0.8; however, the liquid dropouts were predominantly composed of heavier hydrocarbon compounds. In the MD simulation, pressures corresponding to aggregation of nC10 also showed a slow decay in the radial distribution function (RDF) between terminal and secondary carbon atoms in the nC10 with nC4, suggesting the assemblage of the heavier fractions in liquid-like molecular clusters. Furthermore, variation in the ratio of self-diffusion of the heavier components compared with the lighter components was observed, which can be attributed to the increased intermolecular interactions of the heavier components at the liquid dropout region. Despite their extensive application in studying complex fluids, reports of MD simulations in retrograde condensation are almost missing from the literature. To our knowledge, this study represents one of the first applications of MD simulations to retrograde condensation, providing direct molecular-scale evidence of how clustering, intermolecular energies, and diffusion behavior evolve during constant composition expansion.

One-step adsorptive purification of ethylene (C2H4) from C2 ternary hydrocarbon mixtures containing acetylene (C2H2) and ethane (C2H6) remains a fundamental challenge as it involves simultaneously selective adsorption of C2H6 over C2H4 and C2H2 over C2H4. Here, we report the successful practice of a Nanopore Environment Engineering approach within isoreticular metal-organic frameworks (MOFs) that enables optimal separation of C2 ternary mixtures. Using a pair of pyrimidine-bridged tetracarboxylate ligands bearing either methyl (─CH3) or amino (─NH2) groups, we synthesized two csq-type Zr-MOFs, HIAM-411 and HIAM-412, with modulated nanopore environments. While HIAM-411 displays selective adsorption of C2H2 and C2H6 over C2H4, its separation efficiency is largely restricted by the relatively low C2H2/C2H4 selectivity. In contrast, the amino-functionalized HIAM-412 exhibited significantly strengthened hydrogen bonding interactions with C2H2, achieving an approximately 3-fold enhancement in the productivity of the high-purity C2H4. Our study highlights the critical role of nanopore environment regulation in optimizing the multicomponent separation performance of C2 hydrocarbons.

ABSTRACT This work investigates the volatile fraction released from black mass (BM) obtained from spent lithium‐ion batteries subjected to microwave (MW) thermal treatment. MW processing is emerging as an alternative to conventional pyrometallurgy for improving energy efficiency and recovery of critical metals such as lithium, yet the associated emission profile remains poorly characterized. However, the studies of the emissions associated with these treatments are quite limited. Here, a multilevel full factorial Design of Experiments is applied for the first time to evaluate the influence of MW power, exposure time, and BM mass on heating dynamics and lithium extraction efficiency. Volatile organic compounds generated during MW processing are identified by headspace solid‐phase microextraction coupled to gas chromatography–mass spectrometry (HS‐SPME/GC‐MS), showing a complex mixture of aliphatic and aromatic hydrocarbons, carbonate esters, and phosphorus‐ and fluorine‐containing species. Multinuclear NMR spectroscopy (¹H, ⁷Li, ¹⁹F, ³¹P) confirms the presence of electrolyte‐derived residues such as Li⁺, PF₆ − , and phosphate esters. The combined analytical approach clarifies degradation pathways during MW heating and highlights the need to monitor and mitigate the formation of potentially hazardous volatile species in future MW‐assisted recycling processes. Statistical models reveal that the time to reach 600°C and the maximum temperature depend primarily on power and exposure time, while Li recovery is governed by BM mass and its interaction with power.

Abstract Aviation is a major contributor to greenhouse gas emissions, and thus developing renewable alternatives such as lignin-derived biofuels is critical. Current catalytic routes for hydrodeoxygenation of bio-oil model compounds, such as isoeugenol, fail to produce the desired aromatics to cycloalkane ratios required for aviation fuels. We hypothesized that tailoring metal-support interactions in a nickel aluminate spinel catalyst can enable selective formation of hydrocarbon blends meeting fuel specifications. Hydrodeoxygenation of isoeugenol was conducted in a batch reactor using a nickel aluminate spinel catalyst synthesized via a one-pot sol-gel method. Reactions were conducted at 250–300 °C and 20–40 bar hydrogen pressure, and products were analyzed by gas chromatography-mass spectrometry to determine yields of aromatics, cycloalkanes, and intermediates. Catalyst structure and surface properties were characterized using X-ray diffraction, X-ray photoelectron spectroscopy, X-ray absorption spectroscopy, and electron microscopy to establish structure–performance relationships. Under optimized conditions of 275 °C at 20 bar H 2 , aromatic and cycloalkane yields reached 16 wt% and 30 wt%, respectively. Reaction trends showed that elevated temperatures favor cycloalkane formation while hydrogen pressure controls intermediate conversion. The moderate Lewis acidity combined with medium-sized Ni 0 crystallites promote selective hydrogenation and deoxygenation while minimizing over-hydrogenation. This catalytic system produces fuel-grade hydrocarbon mixtures in a single step, exceeding previously reported performance. These findings provide a practical route for lignin valorization and the production of renewable aviation fuels with reduced greenhouse gas emissions.

Solvothermal liquefaction (STL) is a promising thermochemical technique for recycling organic waste materials. In this study, three polymer feedstocks, high molecular weight polystyrene (PS), styrene-butadiene rubber (SBR), and scrap tire waste (STW), were subjected to STL under subcritical (270 °C) and supercritical (320 °C) conditions, using toluene as the solvent. The resulting liquid products were characterized by atmospheric pressure photoionization Fourier transform ion cyclotron resonance mass spectrometry (APPI FT-ICR MS), carbon-13 nuclear magnetic resonance (13C NMR), and Fourier transform infrared (FT-IR) spectroscopy. All feedstocks yielded significant amounts of liquid products. PS was fully liquefied at both temperatures, whereas SBR and STW left 16-22 wt % solid residues. Spectroscopic analyses showed that PS primarily decomposed into styrene monomers and small oligomers. In contrast, SBR and STW produced complex mixtures of aliphatic and polycyclic aromatic hydrocarbons (PAHs) and their derivatives. The SBR-derived liquids were rich in large, alkylated PAHs, while STW mainly generated polyisoprene oligomers with sulfur and oxygen functionalities. Supercritical conditions resulted in higher liquid yields than the subcritical ones but also increased the aromaticity of the products. Based on the results, STL is a promising thermochemical technique for waste polymer valorization but requires fine-tuning and further product downstream fractionation and processing.

Hydrothermal liquefaction (HTL) of algal biomass is a promising approach for renewable biofuel production. The actual study investigates the effects of reaction temperature (225–325 °C), residence time (15–60 min), algae-to-water mass ratio (1:5–1:20), and pressure on the yield and quality of biofuel derived from municipal wastewater-grown mixed algal-cyanobacterial biomass. Eleven HTL experiments were conducted, and the resulting products were separated into gas, liquid, and solid phases for thermal and chemical analyses. Selected biofuel samples were characterized using gas chromatography–mass spectrometry (GC–MS), elemental analysis, and thermogravimetric analysis (TGA). The biofuels contained complex mixtures of aliphatic hydrocarbons, aromatics, phenolics, carboxylic acids, esters, and nitrogen-containing compounds, classified into biogasoline, bio-jet fuel, biodiesel, and motor oil fractions. Optimal yields of biofuel, gas, and solid residues were 16.86%, 26.14%, and 40.43%, respectively, achieved at a 1:10 algae-to-water ratio, 30 min reaction time, and 250 °C. The biofuel composition comprised 11.37% gasoline, 29.41% kerosene, 9.71% diesel, with a heating value of 42.93 MJ·kg⁻¹. A higher fraction of gasoline, kerosene and diesel-range compounds enhances energy density and combustion stability, while lower oxygen and nitrogen content improves storage and fuel properties. Solid residues exhibited uniform physical properties but were unsuitable for high-grade biochar due to low carbon and high inorganic content. These findings demonstrate that HTL of municipal wastewater-grown microalgae is a viable route for sustainable biofuel production, integrating resource recovery with renewable energy generation, while systematically evaluating key operational parameters and characterizing the resulting biofuel for downstream applications.

Numerical Study on Condensation Flow and Heat Transfer of Hydrocarbon Mixtures in Inclined Tubes under Static and Swaying Conditions

The accurate prediction of reservoir fluid flow dynamics under reservoir conditions based on the interfacial tension (IFT) and contact angle (CA) is critical to the flexibility of the carbon dioxide-enhanced oil recovery (CO2-EOR) scheme. Thus, in this paper, a novel data set consisting of IFT and CA data for the CO2-oil-rock systems was established via a high-temperature and high-pressure visualization platform based on the axisymmetric drop shape analysis (ADSA) method. Experimental measurements were carried out covering a large temperature range from 308 to 368 K and pressures up to 17 MPa. The densities of CO2-dissolved oil samples used in the CO2-oil IFT determination were estimated via the volume-translated Peng-Robinson Equation of State (VTPR EOS) method, and molar volume translation parameters (vc,i) for multicomponent hydrocarbon mixtures were obtained. The findings indicate that there was a strong correlation between the interfacial behaviors and CO2-oil interactions: the CO2-oil IFT decreased with increasing pressure, while the CO2- oil-rock CAs for all three substrates (calcite, kaolinite, and quartz) increased with the pressure. Variations in the CA with dependent on the substrate suggested that the oil-wetting characteristics were enhanced on quartz surfaces. Furthermore, dodecane bouncing and spreading on core surfaces were observed under supercritical CO2 conditions. Additionally, a robust empirical correlation was developed to predict the CO2-oil IFT at a specified temperature, pressure, and oil composition. Based on this model, the near-miscible displacement pressure window was determined. This research offers crucial experimental data and insights into interfacial phenomena to enhance the efficiency of CO2-EOR processes.

ABSTRACT It is urgently necessary to develop a highly stable fluorine‐free foam system. Optimizing the mixture of surfactants is the key to improving the stability and oil resistance of the foam. This paper systematically studied the application of a binary mixed system composed of non‐ionic hydrocarbon surfactants (alkyl glucoside, APG‐0810) and two non‐ionic organic silicon surfactants (CoatOsil‐77 and UF‐5811) in the oil resistance of fluorine‐free foams. Under both oil‐free and oil‐containing conditions, the surface tension, conductivity, viscosity, foaming ability and oil resistance were evaluated. Adding n‐heptane through micro emulsification increased the surface tension; the conductivity increased in AC# and AU#, while it decreased in CU#. The foaming ability of AC#, AU#, and CU# decreased by 50%, 36.1%, and 75% respectively, and the foam half‐life decreased by 40.5%, 50%, and 82.6% respectively. Among them, the AC# system exhibited the best oil resistance, and the liquid film stability persisted for 150 s under oil‐containing conditions. The mixture of APG‐0810/CoatOsil‐77 showed excellent performance, providing a theoretical basis for the design of stable fluorine‐free oil‐resistant foams.

This study examines the activity coefficients of benzene, toluene, and di-(2-ethylhexyl)phosphoric acid (D2EHPA) in binary benzene–D2EHPA and toluene–D2EHPA systems, as well as the ternary n-hexane–toluene–D2EHPA system, using gas chromatography at 293.0 K. The primary objective was to determine UNIFAC model interaction parameters and validate their accuracy for predicting thermodynamic behavior in these systems. Experimental measurements revealed activity coefficient maxima for benzene and toluene at mole fractions of 0.8–0.9, decreasing to 0.46–0.67 in dilute solutions. The UNIFAC interaction parameters were calculated as follows: ACH–HPO4 (−334, 4605), ACCH3–HPO4 (680, 467), and refined CH2–HPO4 (54, 1199). The UNIFAC model achieved deviations of less than 2% from experimental data in both binary and ternary systems. A novel methodology incorporating intermediate standards for gas chromatography was developed to overcome challenges in measuring volatile solvent concentrations, enhancing measurement precision. These findings enable accurate prediction of activity coefficients in mixtures of alkanes, cycloalkanes, and monoaromatic hydrocarbons with D2EHPA, offering significant implications for optimizing metal liquid–liquid extraction processes.

Bentonite is the most widely used raw material for producing organoclays, which have numerous industrial and environmental applications. Due to their hydrophobicity, high swelling, and strong affinity for organic compounds, organoclays are effective in removing organic solvents from contaminated water originating from pipeline leaks, oil spills, traffic accidents, and industrial discharges. Such contamination not only degrades water quality but also forms surface films that hinder oxygen transfer, threatening aquatic ecosystems. In this study, two sodium bentonites with different specific surface areas (30 and 50 m2/g) were modified with three quaternary ammonium salts of varying molar masses and alkyl chain lengths (Sun, Arq, and Arm) to evaluate their performance in organic solvent sorption (gasoline, diesel, and kerosene). The materials were characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), differential thermal analysis (DTA), scanning electron microscopy (SEM), and swelling capacity and sorption efficiency. The swelling capacity was determined according to ASTM D5890-19 (Foster method) using gasoline, diesel, kerosene, toluene, and xylene, while the sorption efficiency was assessed following ASTM F726-17 in gasoline, diesel, and kerosene, chosen due to their high potential for water contamination and frequent occurrence in oil spill and leakage scenarios. These solvents also differ in polarity and aromatic content, providing a relevant model for hydrocarbon mixtures commonly found in the environment. Results showed that the interaction between the clay and the surfactant depended strongly on the modifier’s chemical structure. The sorption capacity increased with greater interlayer expansion, surfactant molar mass, and specific surface area of the clay. Among all samples, the Arm-modified natural bentonite (VLArm) exhibited the best performance, with adsorption capacities of up to 6 g/g for diesel, 5 g/g for gasoline, and 5 g/g for kerosene. These values exceeded most previously reported organoclays. These findings demonstrate that optimizing the combination of clay properties and surfactant chemistry can yield highly efficient, low-cost organoclays for environmental remediation of organic contaminants.

A review of soot formation indices used to assess the contribution of a given substance to soot formation was conducted. Using the Lemaire, Das, and Barrientos methods that rely on the structural group contribution method, the oxygen extended soot formation index (OESI) values were calculated for certain hydrocarbons, alcohols, ketones, and aldehydes. Using the structural group contribution method, the OESI values were calculated for mixtures of hydrocarbons (benzene) with biocomponents (alcohols, aldehydes, and ketones), as studying the soot formation of pure biocomponents is complicated by the extremely low soot emissions during their combustion. The results were compared with experimental data. The Das method yielded results closest to the experimental values when studying mixtures. However, all three methods exhibit significant deviations at high volume fractions of the biocomponent in the mixture, which may be due to an inaccuracy in the method for determining the soot formation index of a mixture when biocomponents are added. Ultimately, the Lemaire method proved to be the most suitable, as it showed good results in determining the OESI index and contains a large number of structural groups studied.