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Self-preservation and structural transition of gas hydrates during dissociation below the ice point: an in situ study using Raman spectroscopy
The hydrate structure type and dissociation behavior for pure methane and methane-ethane hydrates at temperatures below the ice point and atmospheric pressure were investigated using in situ Raman spectroscopic analysis. The self-preservation effect of sI methane hydrate is significant at lower temp...
Autores principales: | , , , , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
Nature Publishing Group
2016
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5150642/ https://www.ncbi.nlm.nih.gov/pubmed/27941857 http://dx.doi.org/10.1038/srep38855 |
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author | Zhong, Jin-Rong Zeng, Xin-Yang Zhou, Feng-He Ran, Qi-Dong Sun, Chang-Yu Zhong, Rui-Qin Yang, Lan-Ying Chen, Guang-Jin Koh, Carolyn A. |
author_facet | Zhong, Jin-Rong Zeng, Xin-Yang Zhou, Feng-He Ran, Qi-Dong Sun, Chang-Yu Zhong, Rui-Qin Yang, Lan-Ying Chen, Guang-Jin Koh, Carolyn A. |
author_sort | Zhong, Jin-Rong |
collection | PubMed |
description | The hydrate structure type and dissociation behavior for pure methane and methane-ethane hydrates at temperatures below the ice point and atmospheric pressure were investigated using in situ Raman spectroscopic analysis. The self-preservation effect of sI methane hydrate is significant at lower temperatures (268.15 to 270.15 K), as determined by the stable C-H region Raman peaks and A(L)/A(S) value (Ratio of total peak area corresponding to occupancies of guest molecules in large cavities to small cavities) being around 3.0. However, it was reduced at higher temperatures (271.15 K and 272.15 K), as shown from the dramatic change in Raman spectra and fluctuations in A(L)/A(S) values. The self-preservation effect for methane-ethane double hydrate is observed at temperatures lower than 271.15 K. The structure transition from sI to sII occurred during the methane-ethane hydrate decomposition process, which was clearly identified by the shift in peak positions and the change in relative peak intensities at temperatures from 269.15 K to 271.15 K. Further investigation shows that the selectivity for self-preservation of methane over ethane leads to the structure transition; this kind of selectivity increases with decreasing temperature. This work provides new insight into the kinetic behavior of hydrate dissociation below the ice point. |
format | Online Article Text |
id | pubmed-5150642 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2016 |
publisher | Nature Publishing Group |
record_format | MEDLINE/PubMed |
spelling | pubmed-51506422016-12-19 Self-preservation and structural transition of gas hydrates during dissociation below the ice point: an in situ study using Raman spectroscopy Zhong, Jin-Rong Zeng, Xin-Yang Zhou, Feng-He Ran, Qi-Dong Sun, Chang-Yu Zhong, Rui-Qin Yang, Lan-Ying Chen, Guang-Jin Koh, Carolyn A. Sci Rep Article The hydrate structure type and dissociation behavior for pure methane and methane-ethane hydrates at temperatures below the ice point and atmospheric pressure were investigated using in situ Raman spectroscopic analysis. The self-preservation effect of sI methane hydrate is significant at lower temperatures (268.15 to 270.15 K), as determined by the stable C-H region Raman peaks and A(L)/A(S) value (Ratio of total peak area corresponding to occupancies of guest molecules in large cavities to small cavities) being around 3.0. However, it was reduced at higher temperatures (271.15 K and 272.15 K), as shown from the dramatic change in Raman spectra and fluctuations in A(L)/A(S) values. The self-preservation effect for methane-ethane double hydrate is observed at temperatures lower than 271.15 K. The structure transition from sI to sII occurred during the methane-ethane hydrate decomposition process, which was clearly identified by the shift in peak positions and the change in relative peak intensities at temperatures from 269.15 K to 271.15 K. Further investigation shows that the selectivity for self-preservation of methane over ethane leads to the structure transition; this kind of selectivity increases with decreasing temperature. This work provides new insight into the kinetic behavior of hydrate dissociation below the ice point. Nature Publishing Group 2016-12-12 /pmc/articles/PMC5150642/ /pubmed/27941857 http://dx.doi.org/10.1038/srep38855 Text en Copyright © 2016, The Author(s) http://creativecommons.org/licenses/by/4.0/ This work is licensed under a Creative Commons Attribution 4.0 International License. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder to reproduce the material. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/ |
spellingShingle | Article Zhong, Jin-Rong Zeng, Xin-Yang Zhou, Feng-He Ran, Qi-Dong Sun, Chang-Yu Zhong, Rui-Qin Yang, Lan-Ying Chen, Guang-Jin Koh, Carolyn A. Self-preservation and structural transition of gas hydrates during dissociation below the ice point: an in situ study using Raman spectroscopy |
title | Self-preservation and structural transition of gas hydrates during dissociation below the ice point: an in situ study using Raman spectroscopy |
title_full | Self-preservation and structural transition of gas hydrates during dissociation below the ice point: an in situ study using Raman spectroscopy |
title_fullStr | Self-preservation and structural transition of gas hydrates during dissociation below the ice point: an in situ study using Raman spectroscopy |
title_full_unstemmed | Self-preservation and structural transition of gas hydrates during dissociation below the ice point: an in situ study using Raman spectroscopy |
title_short | Self-preservation and structural transition of gas hydrates during dissociation below the ice point: an in situ study using Raman spectroscopy |
title_sort | self-preservation and structural transition of gas hydrates during dissociation below the ice point: an in situ study using raman spectroscopy |
topic | Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5150642/ https://www.ncbi.nlm.nih.gov/pubmed/27941857 http://dx.doi.org/10.1038/srep38855 |
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