Molecular dynamic simulations to evaluate dissociation of hydrate structure II in the presence of inhibitors: A mechanistic study

Kondori, Javad; Zendehboudi, Sohrab; James, Lesley

doi:10.1016/j.cherd.2019.05.048

Cited by 27 publications

(19 citation statements)

References 46 publications

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“…MD has been successfully employed to model asphaltene precipitation ,− and asphaltene deposition on calcite − and silica. , Also, MD is able to model the interfacial properties in the presence of different substances such as asphaltene, ,− asphaltene and resin, emulsifier, and demulsifier of water/oil emulsion . MD has been used to estimate the solubility parameter for asphaltenes in different solvents, , diffusion coefficients, ,,, and hydrate stability and dissociation. − Recently, the MD approach has been used to model asphaltene aggregation during enhanced oil recovery (EOR) processes such as water injection − and gas injection . The focus of the current study is on the inhibition of asphaltene aggregation.…”

Section: Theory Of Computational Approachmentioning

confidence: 99%

New Molecular Insights into Aggregation of Pure and Mixed Asphaltenes in the Presence of n-Octylphenol Inhibitor

2020

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Asphaltene stability can be perturbed during the oil production and transportation, leading to asphaltene precipitation and deposition. Chemical inhibitors are usually added to the oil phase to postpone asphaltene deposition. The chemical bonding between asphaltene and inhibitor molecules, and the steric hindrance are the key mechanisms of aggregation inhibition. Nevertheless, the interaction mechanisms between asphaltenes and chemical inhibitors still need more research investigations. In this paper, we use an advanced computational chemistry tool, molecular dynamics (MD), to analyze the inhibitory effect of noctylphenol (OP) on three different asphaltene structures at 1 bar and 300 K. To meet the objectives, the asphaltene aggregation and aggregate characterization in both cases of pure and mixed asphaltenes are studied. It is concluded that the archipelago asphaltene (A1) does not aggregate appreciably in the absence of OP; nevertheless, OP reduces the aggregation. The addition of OP is more effective in reducing the aggregation rate for the continental asphaltene, containing hydroxyl and pyridine groups (A2), which is due to the formation of strong hydrogen bonds between the asphaltene and OP, compared to the aromatic stacking between asphaltene and asphaltene. The presence of hydrogen bonds significantly changes the characteristics of aggregates in both scenarios: in the absence and presence of OP. Hence, OP exhibits less efficiency for the continental asphaltene case without hydrogen bond potential (A3). For the mixed asphaltene systems, OP considerably lowers the aggregation rate when A2 and A3 are simultaneously present; the higher relative portion of OP to A2 is the main reason for this behavior. This study reveals that the OP can be an effective inhibitor, depending on the distribution of different types of asphaltenes in the crude oil. The same strategy can be used to screen proper inhibitors or inhibitor mixtures for various types of asphaltenes.

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Section: Theory Of Computational Approachmentioning

confidence: 99%

New Molecular Insights into Aggregation of Pure and Mixed Asphaltenes in the Presence of n-Octylphenol Inhibitor

2020

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“…However, replacing partial Ti cations with W or Ce gave a somewhat lower or higher g ( r ) value for Ti–O in comparison with TiO 2 , indicating an unfriendly structural disorder. 32 As shown in Fig. 2c, the TiO 2 lattice had no obvious changes with the introduction of Mn, while the compulsive insertion of W or Ce into the lattice was of huge influence on the mobility of TiO 2 unit cells, resulting in lattice deformation and even collapse.…”

Section: Resultsmentioning

confidence: 89%

“…The MSD is a parameter that shows the real distance traveled by an identical particle, and its curve analysis could describe the behavior of molecules in the solid, gas and liquid phases. 32,33 The RDF, g(r), is commonly used to characterize molecular packing details in a structure which gives the probability of finding a reference particle at a radial distance from another one. 34,35 Thus, theoretical calculations were carried out by modeling all samples in the MSD and RDF of TiO 2 with different doping metal ions to confirm the possibility and stability of the recombinant unit cell.…”

Section: Preparation Of Ti-based Materialsmentioning

confidence: 99%

Sustainable catalytic oxidation of 1,3-butadiene over dispersedly assembled Ce_0.027W_0.02Mn_0.054TiO_xfeaturing synergistic redox cycles

Wang

et al. 2022

Environ. Sci.: Nano

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“…The difficulty of gas diffusion in the hydrate-liquid side also causes a change in the dissociation rate and is considered as a rate-controlling stage in the hydrate dissociation process. − The reversible regrowth occurs at the interface and nucleates the water molecules around gas molecules in the liquid phase, thereby forming partial hydrate cavities . In addition, the preferential dissociation of some cavity types due to specific guest properties and their distributions was previously observed. , Iwai et al found that CH 4 hydrates were more stable than CO 2 hydrates under the calculated conditions . Kondori observed different decomposition behaviors of hydrate systems with different compositions.…”

Section: Introductionmentioning

confidence: 95%

“…The optimal configuration of sI binary hydrates according to molecular dynamic simulations was when CO 2 and CH 4 occupy the large 5 12 6 2 and small 5 12 cavities, respectively. It was also found that the presence of CH 4 molecules in large cavities decreased the stability of sII hydrates for the mixtures of CH 4 –C 3 H 8 , CH 4 –iso-C 4 H 10 , and CH 4 –C 3 H 8 –iso-C 4 H 10 …”

Section: Introductionmentioning

confidence: 97%

Experimental and Simulation Study for the Dissociation Behavior of Gas Hydrates─Part II: sII Mixed Gas Hydrates

2023

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This study is an extension of our research on the dissociation behavior of sI CH 4 hydrates (Part I). In this study, investigations of the dissociation of binary and multicomponent structure II hydrates were carried out. A novel approach involving in situ and ex situ Raman spectroscopic measurements together with molecular dynamics simulations were applied for a systematic assessment of the hydrate dissociation and gas release behavior due to the destabilization of hydrate cavities. The hydrate decomposition was induced by thermal stimulation to mimic the warming of oceans and atmosphere brought by climate changes. The interactions between the released gas, aqueous phase, and hydrates were described. The results demonstrated that in the vicinity of the hydrate surface, the liquid phase was oversaturated with the gas molecules and some unstable partial hydrate cavities were also formed. Consequently, the release of gas was temporarily stopped or very slow. Throughout the process, the hydrate underwent decomposition−reformation−continuing decomposition until the crystal disappeared. A faster breakdown of small cavities (5 12 ) was recorded, leading to an increase in the large-to-small cavity ratio during dissociation. Moreover, the results indicated a faster release of CH 4 molecules compared to C 3 H 8 over the dissociation process of the sII CH 4 −C 3 H 8 hydrate. This could be due to the higher diffusivity of CH 4 molecules from the hydrate surface to the gas phase as well as its lower potential to stabilize the cavities compared to C 3 H 8 . The release of CH 4 molecules was also faster compared to CO 2 and C 2 H 6 molecules in the sII mixed hydrate, leading to changes in the hydrate composition throughout the process.

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Molecular dynamic simulations to evaluate dissociation of hydrate structure II in the presence of inhibitors: A mechanistic study

Cited by 27 publications

References 46 publications

New Molecular Insights into Aggregation of Pure and Mixed Asphaltenes in the Presence of n-Octylphenol Inhibitor

New Molecular Insights into Aggregation of Pure and Mixed Asphaltenes in the Presence of n-Octylphenol Inhibitor

Sustainable catalytic oxidation of 1,3-butadiene over dispersedly assembled Ce_0.027W_0.02Mn_0.054TiO_xfeaturing synergistic redox cycles

Experimental and Simulation Study for the Dissociation Behavior of Gas Hydrates─Part II: sII Mixed Gas Hydrates

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Molecular dynamic simulations to evaluate dissociation of hydrate structure II in the presence of inhibitors: A mechanistic study

Cited by 27 publications

References 46 publications

New Molecular Insights into Aggregation of Pure and Mixed Asphaltenes in the Presence of n-Octylphenol Inhibitor

New Molecular Insights into Aggregation of Pure and Mixed Asphaltenes in the Presence of n-Octylphenol Inhibitor

Sustainable catalytic oxidation of 1,3-butadiene over dispersedly assembled Ce0.027W0.02Mn0.054TiOxfeaturing synergistic redox cycles

Experimental and Simulation Study for the Dissociation Behavior of Gas Hydrates─Part II: sII Mixed Gas Hydrates

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Product

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Sustainable catalytic oxidation of 1,3-butadiene over dispersedly assembled Ce_0.027W_0.02Mn_0.054TiO_xfeaturing synergistic redox cycles