Sensitivity of the aggregation behaviour of asphaltenes to molecular weight and structure using molecular dynamics

Ungerer, Philippe; Rigby, David L.; LeBlanc, B.P.; Yiannourakou, Marianna

doi:10.1080/08927022.2013.850499

Cited by 98 publications

(94 citation statements)

References 24 publications

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“…The aggregation process of asphaltene is apparently irreversible, which is attributed to the dispersion energy between the PAHs of asphaltenes. 31 The orientation of asphaltene aggregates in single-solvent or binary solvents system was also investigated by molecular simulations. Greenfield and Zhang 32 found that the molecular orientation of neighboring molecules was closely related to the molecular structure and the environmental temperature.…”

Section: Introductionmentioning

confidence: 99%

Molecular Dynamics Simulation of Self-Aggregation of Asphaltenes at an Oil/Water Interface: Formation and Destruction of the Asphaltene Protective Film

2015

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It is well known that asphaltene molecules play a significant role in stabilizing emulsions of water in crude oil or diluted bitumen solutions. Molecular dynamics simulations were employed to investigate the aggregation and orientation behaviors of asphaltene molecules in a vacuum and at various water surfaces. Two different continental model asphaltene molecules were employed in this work. It was found that the initially disordered asphaltenes quickly self-assembled into ordered nanoaggregates consisting of several molecules, in which the aromatic rings in asphaltenes were reoriented to form a face-to-face stacked structure. More importantly, statistical analysis indicates that most of the stacked polycyclic aromatic planes of asphaltene nanoaggregates tend to be perpendicular to the water surface. If the asphaltene molecules are considered as "stakes", then the asphaltene nanoaggregate can be regarded as a "fence". All the fence-like nanoaggregates were twined and knitted together, which pinned them perpendicularly on the water surface to form a steady protective film wrapping the water droplets. The mechanism of stabilization of the water/oil emulsions is thereby well understood. Demulsification processes using a chemical demulsifier were also studied. It was observed that the asphaltene protective film was destroyed by a demulsifier of ethyl cellulose molecules, leading to exposure of the water droplet. The results obtained in this work will be of significance in guiding the development of demulsification technology.

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Section: Introductionmentioning

confidence: 99%

Molecular Dynamics Simulation of Self-Aggregation of Asphaltenes at an Oil/Water Interface: Formation and Destruction of the Asphaltene Protective Film

2015

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“…We benefit from the wide versatility of the PCFF+ force field type to model a wide range of already parameterized organic groups including amino acids and polypeptides with a good accuracy. [37][38][39] Furthermore, PCFF+ relies on ab initio parameterization, making additional ab initio-parameterization using this forcefield a coherent choice. The currently available PCFF+ force field was supplemented with the missing non-bonded Lennard-Jones interactions and the missing bonded terms between the inorganic sub-network and the organic benzenedicarboxylate (bdc) linker (i.e.…”

Section: Forcefield Parametrizationmentioning

confidence: 99%

“…For the purpose of MD calculations, a set of PCFF+ force field parameters [37][38][39] were specifically developed to model MIL-68-NH2. We benefit from the wide versatility of the PCFF+ force field type to model a wide range of already parameterized organic groups including amino acids and polypeptides with a good accuracy.…”

Section: Forcefield Parametrizationmentioning

confidence: 99%

“…[25][26][27][28][29] Another powerful route relies on post-synthetic modification strategies. 14,[30][31][32][33] In 2011, Canivet et al reported the application of solid-phase peptide-coupling to the aminofunctionalized In-MIL-68-NH2 in order to covalently immobilize proline and alanine amino acids within the framework.…”

Section: Introductionmentioning

confidence: 99%

“…In a first step, dispersion-corrected periodic DFT calculations were coupled with MD simulations to predict the key interactions determining the conformations of the amino acids grafted to the MOF and to explore their dynamics. For that purpose a new parametrized version of the PCFF+ force field, known to yield an excellent description of organic systems, [37][38][39] was specially developed and validated against ab initio MD calculations. The development of this force field was a key step to provide access to nanosecond length MD simulations of the functionalized MOFs.…”

Section: Introductionmentioning

confidence: 99%

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Molecular Level Characterization of the Structure and Interactions in Peptide‐Functionalized Metal–Organic Frameworks

Todorova

Rozanska

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et al. 2016

Chemistry A European J

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We use DFT, newly parameterized Molecular Dynamics simulations and last generation 15 N DNP surface enhanced solid-state NMR spectroscopy to understand graft-host interactions and effects imposed by the MOF host on peptide conformations in a peptide-functionalized MOF. Focusing on two grafts typified by MIL-68-Proline (-Pro) and MIL-68-Glycine-Proline (-Gly-Pro), we identified the most likely peptide conformations adopted in the functionalized hybrid frameworks. We found that hydrogen bond interactions between the graft and the surface hydroxyl groups of the MOF are key in determining the peptides conformation(s).15 N DNP SENS methodology shows unprecedented signal enhancements when applied to these peptide-functionalized MOFs. The calculated chemical shifts of selected MIL-68-NH-Pro and MIL-68-NH-Gly-Pro conformations are in a good agreement with the experimentally obtained 15 N NMR signals. The study shows that the conformations of peptides when grafted in a MOF host are unlikely to be freely distributed, and conformational selection is directed by strong host-guest interactions.

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Methane and carbon dioxide in dual‐porosity organic matter: Molecular simulations of adsorption and diffusion

2020

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Shale gas, which predominantly consists of methane, is an important unconventional energy resource that has had a potential game-changing effect on natural gas supplies worldwide in recent years. Shale is comprised of two distinct components: organic material and clay minerals, the former providing storage for hydrocarbons and the latter minimizing hydrocarbon transport. The injection of carbon dioxide in the exchange of methane within shale formations improves the shale gas recovery, and simultaneously sequesters carbon dioxide to reduce greenhouse gas emissions. Understanding the properties of fluids such as methane and methane/carbon dioxide mixtures in narrow pores found within shale formations is critical for identifying ways to deploy shale gas technology with reduced environmental impact. In this work, we apply molecularlevel simulations to explore adsorption and diffusion behavior of methane, as a proxy of shale gas, and methane/carbon dioxide mixtures in realistic models of organic materials. We first use molecular dynamics simulations to generate the porous structures of mature and overmature type-II organic matter with both micro-and mesoporosity, and systematically characterize the resulting dual-porosity organic-matter structures. We then employ the grand canonical Monte Carlo technique to study the adsorption of methane and the competing adsorption of methane/carbon dioxide mixtures in the organic-matter porous structures. We complement the adsorption studies by simulating the diffusion of adsorbed methane, and adsorbed methane/carbon dioxide mixtures in the organic-matter structures using molecular dynamics.

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Sensitivity of the aggregation behaviour of asphaltenes to molecular weight and structure using molecular dynamics

Cited by 98 publications

References 24 publications

Molecular Dynamics Simulation of Self-Aggregation of Asphaltenes at an Oil/Water Interface: Formation and Destruction of the Asphaltene Protective Film

Molecular Dynamics Simulation of Self-Aggregation of Asphaltenes at an Oil/Water Interface: Formation and Destruction of the Asphaltene Protective Film

Molecular Level Characterization of the Structure and Interactions in Peptide‐Functionalized Metal–Organic Frameworks

Methane and carbon dioxide in dual‐porosity organic matter: Molecular simulations of adsorption and diffusion

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