Asphaltene solubility in common solvents: A molecular dynamics simulation study

Amjad‐Iranagh, Sepideh; Rahmati, Mahmoud; Haghi, Mahdi; Hoseinzadeh, Mohsen; Modarress, Hamid

doi:10.1002/cjce.22321

Cited by 29 publications

(25 citation statements)

References 43 publications

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“…Figure demonstrates the experimental data and estimated values of asphaltene precipitation by CMIS and GMDH models for nC 5 and nC 10 at 20 °C as a function of solvent to crude oil dilution ratio. By increasing the chain length of the solvent, the interactions with asphaltene side chains increase, which subsequently improves asphaltene solubility . As illustrated in Figure , both models follow the trend of experimental data with variation of types of solvents and solvent to crude oil dilution ratio.…”

Section: Resultssupporting

confidence: 52%

See 1 more Smart Citation

Modelling asphaltene precipitation titration data: A committee of machines and a group method of data handling

Hemmati‐Sarapardeh¹,

Dabir²,

Ahmadi³

et al. 2018

Can J Chem Eng

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Asphaltene precipitation causes different problems in the oil industry. In this study, a large data bank was used to model asphaltene precipitation titration data as a function of temperature, type of solvent, and solvent to crude oil dilution ratio. Three multilayer perceptron (MLP) neural networks and three radial basis function (RBF) neural networks were developed to estimate asphaltene precipitation data. The MLP models were optimized with scaled conjugate gradient (SCG), Levenberg‐Marquardt (LM), and Bayesian regularization (BR) algorithms and the RBF models were optimized with the particle swarm optimization (PSO) algorithm, imperialist competitive algorithm (ICA), and genetic algorithm (GA). All of the proposed models show an acceptable degree of accuracy and have an average absolute percent relative error (AAPRE) less than 4 %. Afterwards, three of the best models including MLP‐LM, MLP‐BR, and RBF‐GA were combined and a committee machine intelligent system (CMIS) was designed, which offers a higher accuracy compared to the other intelligent models. Aside from these intelligent models, the group method of data handling (GMDH) was used to develop an explicit and simple expression for estimating asphaltene precipitation. The proposed CMIS and GMDH models were compared to models developed based on scaling theory and the results show that the proposed models in this study outperform pre‐existing models. The validity and accuracy of the CMIS and GMDH models were proven by statistical and graphical techniques. Finally, a sensitivity analysis suggested that the solvent to crude oil dilution ratio has the largest effect on asphaltene precipitation.

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Section: Resultssupporting

confidence: 52%

“…By increasing the chain length of the solvent, the interactions with asphaltene side chains increase, which subsequently improves asphaltene solubility. [104] As illustrated in Figure 8, both models follow the trend of experimental data with variation of types of solvents and solvent to crude oil dilution ratio.…”

Section: Resultsmentioning

confidence: 59%

Modelling asphaltene precipitation titration data: A committee of machines and a group method of data handling

Hemmati‐Sarapardeh¹,

Dabir²,

Ahmadi³

et al. 2018

Can J Chem Eng

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“…Average energies were determined to obtain the asphaltene–asphaltene and asphaltene–solvent interaction energies. Finally, the fourth evaluation parameter corresponds to the solubility parameter analysis for the asphaltene and solvent molecules, which has been widely used to estimate the solubility of asphaltene in a solvent. , Equation was used to calculate this value. where δ i is the solubility parameter, E coh is the cohesive energy, ΔH v is the evaporation enthalpy, R the constant of ideal gases, T is the temperature, and v m is the molar volume. The cohesive energy difference was calculated as the energy difference between a single molecule under ideal gas conditions and the average energy of a molecule within the bulk fluid. , …”

Section: Molecular Dynamics Methodsmentioning

confidence: 99%

“…Finally, the fourth evaluation parameter corresponds to the solubility parameter analysis for the asphaltene and solvent molecules, which has been widely used to estimate the solubility of asphaltene in a solvent. 39,61 Equation 2 was used to calculate this value.…”

Section: Molecular Dynamics Methodsmentioning

confidence: 99%

Physical Insights about Viscosity Differences of Asphaltene Dissolved in Benzene and Xylene Isomers: Theoretical–Experimental Approaches

et al. 2021

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This study characterized the rheological behavior of asphaltenes dissolved in aromatic solvents of different chemical nature to understand the solvent effect. For this purpose, n-C7 asphaltenes were obtained from extra-heavy crude oil and dissolved at three concentrations (1, 8, and 15 wt %) in solvents with different molecular structures: benzene and three xylene isomers. The experimental results revealed appreciable differences in the viscosity of the asphaltene solutions in each solvent which were more marked at higher concentrations (>1 wt %) of n-C7 asphaltenes. Molecular dynamics simulations were conducted to characterize some physical aspects that result in rheological differences. The average aggregate sizes, mean square displacement, asphaltene–asphaltene and asphaltene–solvent interaction energies, and solubility parameters were calculated. The smallest aggregation size was obtained for solutions in o-xylene, followed by m-xylene and p-xylene. Although benzene promoted greater asphaltene aggregation (similar to that obtained with p-xylene), it did not provide the highest viscosity. This result is due to the synergic interactions between the asphaltene aggregate and the solvent, which modified the fluid’s internal friction, evidenced macroscopically as a higher viscosity. Therefore, asphaltene aggregates demonstrated freer movement in benzene than in p-xylene. The main difference between the three xylene isomers corresponds to the dipole moment and solubility parameter due to the location of the −CH3 substituent. This study improves our understanding of the relationship between the aggregation and rheological behavior of crude oils, characterizing the physical behavior to propose alternatives that reduce asphaltene aggregation and its viscosity.

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“…It is widely accepted that two kinds of liquid tend to be mutually miscible on the condition of |Δδ| < 1.3-2.1 with nonpolar groups or hydrogen bonds between molecules. Since the hydrogen bonding interaction is not included in the COMPASS force field, it is incorporated into other nonbonding interaction terms, so the calculated solubility parameters are expressed by δ vdw and δ elec , which represent the solubility parameter generated by van der Waals force and electrostatic force, respectively [43], where δ 2 � δ vdw 2 + δ ele 2 . From Table 2, we can see that the difference between the calculated solubility parameters and experimental values of n-heptane and toluene under the conditions of 298 K and asphaltene-asphaltene (π-π) asphaltene-asphaltene (π-σ) asphaltene-rein asphaltene-aromatic asphaltene-hexadecane asphaltene-saturate 0.1 MPa is quite small, and the error range is less than 1%.…”

Section: Solubility Parametersmentioning

confidence: 99%

Investigating the Compatibility of Various Components in Marine Low-Sulfur Fuel Oil by Molecular Dynamics Simulations

Zhou

Wei

Xue

et al. 2021

Journal of Chemistry

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Asphaltene aggregation and precipitation are one of the major issues for marine low-sulfur fuel oil used on board. Many research studies have been carried out to investigate the aggregation behavior of asphaltene under different conditions, but the mechanism of asphaltene aggregation in low-sulfur fuel oil at the molecular level is still unclear. In this work, molecular dynamics (MD) simulations were performed to calculate the solubility parameters, intermolecular interaction energies, and radial distribution function (RDF) curves of each component in marine low-sulfur fuel oil to examine their mutual compatibility. Simulation results indicate that the solubility parameter of resin gains the highest value and it is close to asphaltene. The solubility parameters of aromatic, hexadecane, and saturate decrease successively. The interaction energy between resin and asphaltene molecules is higher than that between the same kind of molecules, which means that resin can inhibit the aggregation of asphaltene molecules. Typically, a light distillate component (hexadecane) is added to heavy fuel oil to yield low-sulfur oil, and our calculations reveal that this has a negative effect on asphaltene aggregation. Specifically, asphaltene is more likely to self-aggregate, as shown by the increase in peak height in the radial distribution function of the asphaltene-asphaltene pair. The findings of this study will provide theoretical support for the production of marine low-sulfur fuel.

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Asphaltene solubility in common solvents: A molecular dynamics simulation study

Cited by 29 publications

References 43 publications

Modelling asphaltene precipitation titration data: A committee of machines and a group method of data handling

Modelling asphaltene precipitation titration data: A committee of machines and a group method of data handling

Physical Insights about Viscosity Differences of Asphaltene Dissolved in Benzene and Xylene Isomers: Theoretical–Experimental Approaches

Investigating the Compatibility of Various Components in Marine Low-Sulfur Fuel Oil by Molecular Dynamics Simulations

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