Reduced phase stability and faster formation/dissociation kinetics in confined methane hydrate
The mechanisms involved in the formation/dissociation of methane hydrate confined at the nanometer scale are unraveled using advanced molecular modeling techniques combined with a mesoscale thermodynamic approach. Using atom-scale simulations probing coexistence upon confinement and free energy calc...
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ftpubmed:oai:pubmedcentral.nih.gov:8072328 2023-05-15T17:11:40+02:00 Reduced phase stability and faster formation/dissociation kinetics in confined methane hydrate Jin, Dongliang Coasne, Benoit 2021-04-20 http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8072328/ http://www.ncbi.nlm.nih.gov/pubmed/33850020 https://doi.org/10.1073/pnas.2024025118 en eng National Academy of Sciences http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8072328/ http://www.ncbi.nlm.nih.gov/pubmed/33850020 http://dx.doi.org/10.1073/pnas.2024025118 https://www.pnas.org/site/aboutpnas/licenses.xhtmlPublished under the PNAS license (https://www.pnas.org/site/aboutpnas/licenses.xhtml) . Proc Natl Acad Sci U S A Physical Sciences Text 2021 ftpubmed https://doi.org/10.1073/pnas.2024025118 2021-10-17T00:22:39Z The mechanisms involved in the formation/dissociation of methane hydrate confined at the nanometer scale are unraveled using advanced molecular modeling techniques combined with a mesoscale thermodynamic approach. Using atom-scale simulations probing coexistence upon confinement and free energy calculations, phase stability of confined methane hydrate is shown to be restricted to a narrower temperature and pressure domain than its bulk counterpart. The melting point depression at a given pressure, which is consistent with available experimental data, is shown to be quantitatively described using the Gibbs–Thomson formalism if used with accurate estimates for the pore/liquid and pore/hydrate interfacial tensions. The metastability barrier upon hydrate formation and dissociation is found to decrease upon confinement, therefore providing a molecular-scale picture for the faster kinetics observed in experiments on confined gas hydrates. By considering different formation mechanisms—bulk homogeneous nucleation, external surface nucleation, and confined nucleation within the porosity—we identify a cross-over in the nucleation process; the critical nucleus formed in the pore corresponds either to a hemispherical cap or to a bridge nucleus depending on temperature, contact angle, and pore size. Using the classical nucleation theory, for both mechanisms, the typical induction time is shown to scale with the pore volume to surface ratio and hence the pore size. These findings for the critical nucleus and nucleation rate associated with such complex transitions provide a means to rationalize and predict methane hydrate formation in any porous media from simple thermodynamic data. Text Methane hydrate PubMed Central (PMC) Proceedings of the National Academy of Sciences 118 16 e2024025118 |
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Physical Sciences Jin, Dongliang Coasne, Benoit Reduced phase stability and faster formation/dissociation kinetics in confined methane hydrate |
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Physical Sciences |
description |
The mechanisms involved in the formation/dissociation of methane hydrate confined at the nanometer scale are unraveled using advanced molecular modeling techniques combined with a mesoscale thermodynamic approach. Using atom-scale simulations probing coexistence upon confinement and free energy calculations, phase stability of confined methane hydrate is shown to be restricted to a narrower temperature and pressure domain than its bulk counterpart. The melting point depression at a given pressure, which is consistent with available experimental data, is shown to be quantitatively described using the Gibbs–Thomson formalism if used with accurate estimates for the pore/liquid and pore/hydrate interfacial tensions. The metastability barrier upon hydrate formation and dissociation is found to decrease upon confinement, therefore providing a molecular-scale picture for the faster kinetics observed in experiments on confined gas hydrates. By considering different formation mechanisms—bulk homogeneous nucleation, external surface nucleation, and confined nucleation within the porosity—we identify a cross-over in the nucleation process; the critical nucleus formed in the pore corresponds either to a hemispherical cap or to a bridge nucleus depending on temperature, contact angle, and pore size. Using the classical nucleation theory, for both mechanisms, the typical induction time is shown to scale with the pore volume to surface ratio and hence the pore size. These findings for the critical nucleus and nucleation rate associated with such complex transitions provide a means to rationalize and predict methane hydrate formation in any porous media from simple thermodynamic data. |
format |
Text |
author |
Jin, Dongliang Coasne, Benoit |
author_facet |
Jin, Dongliang Coasne, Benoit |
author_sort |
Jin, Dongliang |
title |
Reduced phase stability and faster formation/dissociation kinetics in confined methane hydrate |
title_short |
Reduced phase stability and faster formation/dissociation kinetics in confined methane hydrate |
title_full |
Reduced phase stability and faster formation/dissociation kinetics in confined methane hydrate |
title_fullStr |
Reduced phase stability and faster formation/dissociation kinetics in confined methane hydrate |
title_full_unstemmed |
Reduced phase stability and faster formation/dissociation kinetics in confined methane hydrate |
title_sort |
reduced phase stability and faster formation/dissociation kinetics in confined methane hydrate |
publisher |
National Academy of Sciences |
publishDate |
2021 |
url |
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8072328/ http://www.ncbi.nlm.nih.gov/pubmed/33850020 https://doi.org/10.1073/pnas.2024025118 |
genre |
Methane hydrate |
genre_facet |
Methane hydrate |
op_source |
Proc Natl Acad Sci U S A |
op_relation |
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8072328/ http://www.ncbi.nlm.nih.gov/pubmed/33850020 http://dx.doi.org/10.1073/pnas.2024025118 |
op_rights |
https://www.pnas.org/site/aboutpnas/licenses.xhtmlPublished under the PNAS license (https://www.pnas.org/site/aboutpnas/licenses.xhtml) . |
op_doi |
https://doi.org/10.1073/pnas.2024025118 |
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Proceedings of the National Academy of Sciences |
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118 |
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16 |
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e2024025118 |
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1766068451794747392 |