Theoretical-experimental evaluation of rheological behavior of asphaltene solutions in toluene and p-xylene: Effect of the additional methyl group

Moncayo-Riascos, Ivan; Taborda, Esteban A.; Hoyos, Bibian; Franco, Camilo A.; Cortés, Farid B.

doi:10.1016/j.molliq.2020.112664

Cited by 21 publications

(47 citation statements)

References 78 publications

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“…For this reason, numerous studies have focused on proposing alternatives to avoid asphaltene aggregation to mitigate the damage caused by asphaltene precipitation and deposition. ,, Model solutions have been widely used for this purpose. A model solution is frequently used as a simplified representation of crude oil, composed of asphaltene in aromatic and/or aliphatic solvents. − Typically, toluene , and n -heptane ,, are used separately or in a mixture referred to as a heptol. Several authors have used model solutions to characterize the physical aggregation and rheological behavior of heavy crude oils. ,,− Asphaltenes are obtained by a sequential washing procedure of a given crude oil with aliphatic solvents ( n -pentane or n -heptane), the details of which have been extensively detailed in the literature. ,, …”

Section: Introductionmentioning

confidence: 99%

“…Theoretical studies based on computational molecular simulations have made it possible to elucidate phenomenological aspects of asphaltene aggregation and their impact on viscosity. ,,,, Using model solutions to develop an atomistic description of the experimentally evaluated systems has permitted researchers to establish ideas concerning asphaltene aggregation mechanisms, ,,− viscosity determinations, ,,, and other phenomena. One of the most important, and perhaps most controversial activities, is representing the entire complexity of the asphaltene fraction of crude oil in an average molecular structure or a group of molecular structures. ,,− Therefore, several studies focused on proposing adequate molecular structures which allow a reliable representation of the physical behavior of a specific asphaltene type. ,,, Numerous investigations have focused on determining the mechanisms of asphaltene aggregation in n -heptane and toluene using molecular dynamics. ,,, The results indicate that asphaltene aggregation is promoted in both solvents. ,− Furthermore, authors have identified that the aggregation of asphaltenes in organic solvents, such as n -heptane or toluene, occurs via van der Waals type energies and the π–π interactions between the aromatic nuclei of asphaltene molecular structures. ,,, In contrast, the behavior of asphaltene molecules dissolved in polar solvents, such as water, are determined to a greater extent by electrostatic interactions and the formation of hydrogen bonds than van der Waals interactions. − …”

Section: Introductionmentioning

confidence: 99%

“…Most of the studies reported in the literature focus on determining the effect of asphaltene molecular structures on the aggregation and rheological behavior of model solutions, varying the type of asphaltene, keeping the solvent conditions (i.e., n -heptane, toluene, or heptane) constant, without considering the solvent effects in a fixed asphaltene solution. ,,, Alternatively, our understanding of asphaltene aggregation and viscosity may be improved by considering the effect of the other fractions (aromatics and resins, mainly). In the case of model solutions, it is necessary to determine the effects of specific solvents.…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

et al. 2021

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“…Moncayo-Riascos et al [60] carried out both MD simulations and experiments to assess the influence of adding a methyl group to a solvent on rheological properties of asphaltenes. Based on their experimental and theoretical results, adding a methyl group resulted in significantly increasing the asphaltene-solvent solution's viscosity.…”

Section: Introductionmentioning

confidence: 99%

Molecular Interactions between Asphaltene and Surfactants in a Hydrocarbon Solvent: Application to Asphaltene Dispersion

Ahmadi

Chen

2020

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Heavy oil and bitumen supply the vast majority of energy resources in Canada. Different methods can be implemented to produce oil from such unconventional resources. Surfactants are employed as an additive to water/steam to improve an injected fluid’s effectiveness and enhance oil recovery. One of the main fractions in bitumen is asphaltene, which is a non-symmetrical molecule. Studies of interactions between surfactants, anionic, and non-anionic, and asphaltene have been very limited in the literature. In this paper, we employed molecular dynamics (MD) simulation to theoretically focus on the interactions between surfactant molecules and different types of asphaltene molecules observed in real oil sands. Both non-anionic and anionic surfactants showed promising results in terms of dispersant efficiency; however, their performance depends on the asphaltene architecture. Moreover, a hydrogen/carbon (H/C) ratio of asphaltenes plays an inevitable role in asphaltene aggregation behavior. A higher H/C ratio resulted in decreasing asphaltene aggregation tendency. The results of these studies will give a deep understanding of the interactions between asphaltene and surfactant molecules.

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“…To investigate the practical approaches for preventing or postponing the asphaltene precipitation, many researchers endeavor to find practical, cost-effective, and environmentally benign solutions to overcome the asphaltene deposition problems. − Hu et al investigated the effect of the ionic liquids based on [Cnpy] + and [C 4 iql] + cations and the alkylbenzene-derived amphiphiles Cnphol, Cnbsa, and CnbsNa on the asphaltene precipitation. Their proposed mechanism illustrated that due to having high-charge-density anions, ionic liquids could act as effective inhibitors via the destruction of asphaltene associations.…”

Section: Introductionmentioning

confidence: 99%

Investigating the Performance of Carboxylate-Alumoxane Nanoparticles as a Novel Chemically Functionalized Inhibitor on Asphaltene Precipitation

et al. 2020

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In recent years, researchers have attempted to find some practical approaches for asphaltene adsorption and the prevention or postponement of asphaltene precipitation. Among different techniques, nanotechnology has attracted the researchers' attention to overcome the formation damage resulting from the deposition of asphaltenes. In this study, the application of two types of carboxylate-alumoxane nanoparticles (functionalized boehmite by methoxyacetic acid (BMA) and functionalized pseudo-boehmite by methoxyacetic acid (PBMA)) for asphaltene adsorption and precipitation was investigated. First, the synthesis of two functionalized nanoparticles was performed via the sol− gel method. For the assessment of the adsorption efficiency and adsorption capacity of these nanoparticles toward asphaltene adsorption, the batch adsorption experiments applying ultraviolet−visible (UV−Vis) spectroscopy were performed. The Langmuir and Freundlich isotherms were studied to describe the interaction between asphaltene molecules and carboxylate-alumoxane nanoparticles. For determining the "onset" point of asphaltene precipitation, the indirect method, which was based on the difference in the optical property of various solutions containing different concentrations of asphaltene, was utilized by applying UV−Vis spectroscopy. The isotherm models indicate that the adsorption of asphaltene on the surface of nanoparticles is better fitted to the Freundlich isotherm model compared with the Langmuir model. In the presence of PBMA (0.1 wt %), the onset point was delayed around 26, 20, and 17% in the asphaltene concentrations of 1000, 3000, and 5000 ppm, respectively, in comparison with their reference synthetic oils. On the other hand, these postponements for BMA nanoparticles (0.1 wt %) were 17%, 9%, and insignificant for the asphaltene concentrations of 1000, 3000, and 5000 ppm, respectively. The results reveal that two functionalized nanoparticles tend to adsorb asphaltene molecules and have a positive impact on the postponement of asphaltene precipitation due to molecular interactions between the surface of carboxylate-alumoxane nanoparticles and asphaltene molecules. However, PBMA nanoparticles exhibited better performance on the asphaltene adsorption and postponement of asphaltene precipitation, which is related to its smaller size, as well as higher surface area, compared with BMA nanoparticles.

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Theoretical-experimental evaluation of rheological behavior of asphaltene solutions in toluene and p-xylene: Effect of the additional methyl group

Cited by 21 publications

References 78 publications

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

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

Molecular Interactions between Asphaltene and Surfactants in a Hydrocarbon Solvent: Application to Asphaltene Dispersion

Investigating the Performance of Carboxylate-Alumoxane Nanoparticles as a Novel Chemically Functionalized Inhibitor on Asphaltene Precipitation

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