In Situ Observations of Methane Hydrate Formation Mechanisms by Raman Spectroscopy
A bstract : We compared time‐resolved Raman spectroscopic measurements of CH 4 ‐saturated aqueous solution with CH 4 hydrate crystal formed from the same solution. At 287.1 K and 6.6 MPa the C‐H stretching mode for CH 4 molecules in the solution (ν sol = 2911.7 cm −1 ) was intermediate between that...
| Published in: | Annals of the New York Academy of Sciences |
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| Main Authors: | , , , , |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
Wiley
2000
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| Subjects: | |
| Online Access: | http://dx.doi.org/10.1111/j.1749-6632.2000.tb06814.x https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1749-6632.2000.tb06814.x https://nyaspubs.onlinelibrary.wiley.com/doi/pdf/10.1111/j.1749-6632.2000.tb06814.x |
| Summary: | A bstract : We compared time‐resolved Raman spectroscopic measurements of CH 4 ‐saturated aqueous solution with CH 4 hydrate crystal formed from the same solution. At 287.1 K and 6.6 MPa the C‐H stretching mode for CH 4 molecules in the solution (ν sol = 2911.7 cm −1 ) was intermediate between that in the large cage (ν L = 2905.1 cm −1 ) and that in the small cage (ν S = 2914.1 cm −1 ), thus indicating an intermediate molecular environment. Comparison of these results with previous work on the CO 2 ‐H 2 O system indicated that water molecules in the type‐I small‐cage‐like structure surrounded CH 4 molecules in the solution. Furthermore, the free energy barrier for CH 4 hydrate nucleation is likely to be formation of the large cage structure, which is probably larger than that for CO 2 hydrate formation. |
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