Bui, T;
Phan, A;
Monteiro, D;
Lan, Q;
Ceglio, M;
Acosta, E;
Krishnamurthy, P;
(2017)
Evidence of Structure-Performance Relation for Surfactants used as Anti-Agglomerants for Hydrates Management.
Langmuir
, 33
(9)
pp. 2263-2274.
10.1021/acs.langmuir.6b04334.
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Abstract
Molecular dynamics simulations were employed to study the structure of molecular-thin films of anti-agglomerants adsorbed at the interface between sII methane hydrates and a liquid hydrocarbon. The liquid hydrocarbon was composed of dissolved methane and higher molecular weight alkane such as n-hexane, n-octane, or n-dodecane. The anti-agglomerants considered were surface-active compounds with three hydrophobic tails and a complex hydrophilic head that contains both amide and tertiary ammonium cation groups. The length of the hydrophobic tails and the surface density of the compounds were changed systematically. The results were analyzed in terms of the preferential orientation of the anti-agglomerants, density distributions of various molecular compounds, and other molecular-level properties. At low surface densities the hydrophobic tails do not show preferred orientation, irrespectively of the tail length. At sufficiently high surface densities, our simulations show pronounced differences in the structure of the interfacial film depending on molecular features and on the type of the hydrocarbons present in the system. Some anti-agglomerants are found to pack densely at the interface and exclude methane from the interfacial region. At these conditions the anti-agglomerants film resembles a 'frozen interface'. The hydrophobic tails of the anti-agglomerants that show this feature are of length comparable to that of the n-dodecane in the liquid phase. It is possible that the structured interfacial layer is in part responsible for determining the performance of anti-agglomerants in flow-assurance applications. The simulation results are qualitatively compared against experimental data obtained with the rocking cell apparatus. It was found that the anti-agglomerants for which our simulations suggest evidence of frozen interface at sufficiently high surface densities are those that show excellent performance in rocking cell experiments.
| Type: | Article |
|---|---|
| Title: | Evidence of Structure-Performance Relation for Surfactants used as Anti-Agglomerants for Hydrates Management |
| Location: | United States |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1021/acs.langmuir.6b04334 |
| Publisher version: | http://doi.org/10.1021/acs.langmuir.6b04334 |
| Language: | English |
| Additional information: | Copyright © 2017 American Chemical Society. This document is the Accepted Manuscript version of a Published Work that appeared in final form in Langmuir, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see http://pubs.acs.org/doi/pdf/10.1021/acs.langmuir.6b04334 |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Chemical Engineering UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences |
| URI: | https://discovery.ucl.ac.uk/id/eprint/1538555 |
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