Importance of the Inclusion of Dispersion in the Modeling of Asphaltene Dimers

Mackie, Iain D.; DiLabio, Gino A.

doi:10.1021/ef100797h

Cited by 13 publications

(12 citation statements)

References 37 publications

(78 reference statements)

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“…To accurately describe p-stacking interactions, as well as to emphasize the importance of dispersion energy as a key factor in stabilizing the stacked dimers, dispersion-corrected DFT functional, B97-D [43], associated with basis sets 6-31G ⁄ and 6-311+G ⁄⁄ , was selected as the level of DF calculations to optimize the structures. Recently, B97-D has been widely used to describe macro structures like asphaltene sheets and DNA-base pairs [44][45][46][47][48] Counterpoise (CP) correction [49,50] was performed to limit basis set superposition error (BSSE) while studying intermolecular interactions.…”

Section: Methodsmentioning

confidence: 99%

The influence of asphaltene-resin molecular interactions on the colloidal stability of crude oil

Mousavi

Abdollahi

Pahlavan

et al. 2016

Fuel

132

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g r a p h i c a l a b s t r a c t Micellar structure of asphaltene in a dispersing medium of lighter resins, aromatics, and saturates. a b s t r a c tIn the colloidal hypothesis of vacuum residua and asphalt, micelles are assumed to have an asphaltenic core with the greatest weight and aromaticity and an outer shell composed of lighter and less aromatic molecules. The true nature of the micelles, and the asphaltenic core in particular, has always been a debatable issue among asphalt researchers. One of the frequently asked questions is whether asphaltenes exist as stacked layers within the micelles or as single molecular units stabilized by resin molecules. In this paper, we investigate the correlation between the number of asphaltene sheets and the final stability of the system in a medium of asphaltene and resin components. Our evaluation is based on rigorous quantum mechanical calculations using a DFT-D approach. Our quantitative findings corroborate the view that the colloidal behavior of crude oil is better described by asphaltene-asphaltene associations. Moreover, our calculations show that if both asphaltene and resin are present, resin-asphaltene interactions are preferred over asphaltene-asphaltene interactions only if the number of resin molecules per micelle is greater than the number of asphaltene molecules per micelle.

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Section: Methodsmentioning

confidence: 99%

The influence of asphaltene-resin molecular interactions on the colloidal stability of crude oil

Mousavi

Abdollahi

Pahlavan

et al. 2016

Fuel

132

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“…However, in their standard implementation, they are not capable of taking into account dispersion effects in weakly bound complexes. To correct these deficiencies, DFT–vdW- and DFT–dispersion-corrected approaches have appeared recently in the literature . It is worth noting that standard DFT families, such as BLYP and B3LYP, are only able to give repulsive dimeric interactions, whereas PW91 pure functional is able to give a correct description of the intermolecular potential for a great variety of molecular dimers. , In this context, we have recently demonstrated that this particular functional gives a good description for σ–π and π–π interactions in a series of heteroaromatic monocyclic molecular complexes of benzene, pyridine, and thiophene molecules, where the binding energies are compared to results obtained with more sophisticated methods, such as MP4 and CCSD.…”

Section: Introductionmentioning

confidence: 99%

Molecular Interactions between Orinoco Belt Resins

Castellano¹,

Gimon²,

Canelón³

et al. 2012

Energy Fuels

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This paper describes the characterization of structural, energetic, and electric properties of the molecular complexes between Orinoco belt resins through the application of computational molecular mechanics (MM), semi-empirical parametrization (PM6), and density functional theory (DFT) (PW91 and HCTH) in conjunction with the double numeric and polarized (DNP) basis set. The resin sources for the studied molecules are Orinoco belt vacuum residues (Carabobo, Hamaca, Merey, Merey-Mesa, and Zuata). Molecular structures of these compounds were proposed from analysis of experimental characterization. The study of molecular interactions has shown that these resins are able to form stable van der Waals complexes, where their computed stability has a large dependence upon the applied theory level. A qualitative description of the formation of these complexes could be obtained with these methodologies. In particular, MM overestimates resin interaction energies when compared to PM6 and DFT (PW91 and HCTH) results. However, the HCTH/DNP approach leads to interaction energy values for resin−resin complexes that lie in the range from −2.39 to −7.09 kcal/mol, in better agreement with literature reports and chemical expectations than PW91/DNP interaction energy values. The stability of these complexes and the strength of the resin self-association can be rationalized considering their chemical nature and the induced electric properties (dipole moment and polarizabilities) by molecular interactions. Additionally, inclusion of dispersion in the DFT calculations of the resin molecular complexes improves the energetic pattern of the studied molecules significantly.

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“…In this regard, asphaltene systems have often been represented as a mixture of various (often three) structures with different sizes and characteristics, and that can be considered individually as asphaltene molecules [9][10][11][12].…”

Section: Modelmentioning

confidence: 99%

Aggregation study of asphaltenes from colombian Castilla crude oil using molecular simulation

León-Barreneche

Hoyos

Cañas-Marín

2015

Rev. Fac. Ing. Antioquia

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A molecular simulation model to study the mechanism for asphaltene aggregation is presented. Four species were selected, obtained from structural analysis of asphaltenes from the oil extracted from Castilla oil field, in Colombia. Energetic contributions to the aggregation process for each species were studied, and the solubility parameter was evaluated. Finally, the aggregation process between different species was studied in order to determine the tendency of the molecules towards self-association. Results show that for all species, aggregation state is energetically favorable; also, both Van der Waals interactions and electrostatic forces contribute equally to the aggregation process. It was also found that the molecular structure of the substances has a big influence on the manner in which asphaltenes aggregate. For continental structures, long ramifications cause a physical obstacle for aggregation. On the other hand, the molecular flexibility associated with archipelago structures enables the aggregation with other species, but somehow hinders the process of self-association. The solubility parameter for all four substances was within the range established by literature. RESUMEN:Se presenta un modelo de simulación molecular para estudiar el mecanismo de agregación de asfaltenos. Se seleccionaron cuatro especies, obtenidas a partir de análisis estructurales del petróleo extraído del campo Castilla, en Colombia. Se estudiaron las contribuciones energéticas al proceso de agregación y se calculó el parámetro de solubilidad para cada especie. Finalmente, se estudió el proceso de agregación entre las diferentes especies con el fin de determinar la tendencia de las moléculas hacia la autoasociación. Los resultados muestran que para todas las especies, el estado de agregación es energéticamente favorable, y que tanto las fuerzas de Van der Waals como las fuerzas electrostáticas contribuyen en igual magnitud al proceso de agregación. Se encontró también que la estructura molecular de las moléculas tiene una gran influencia en la manera cómo se agregan los asfaltenos. Para las estructuras continentales, las ramificaciones largas ocasionan un impedimento físico para la agregación. Por otro lado, la flexibilidad asociada a las moléculas tipo archipiélago favorece la agregación con otras especies, pero de alguna manera entorpece la autoasociación. El parámetro de solubilidad para todas las especies se encontró dentro del rango establecido por la literatura.

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Importance of the Inclusion of Dispersion in the Modeling of Asphaltene Dimers

Cited by 13 publications

References 37 publications

The influence of asphaltene-resin molecular interactions on the colloidal stability of crude oil

The influence of asphaltene-resin molecular interactions on the colloidal stability of crude oil

Molecular Interactions between Orinoco Belt Resins

Aggregation study of asphaltenes from colombian Castilla crude oil using molecular simulation

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