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Updated: May 25, 2026
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Methane Hydrate Crystallization on Sessile Water Droplets
Published on: May 26, 2021
Cage occupancies in the high pressure structure H methane hydrate: a neutron diffraction study
C A Tulk1, D D Klug, A M dos Santos
1Neutron Scattering Science Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
The Journal of Chemical Physics
|February 11, 2012
Summary
Neutron diffraction refined methane hydrate cage occupancies, revealing 3.1 CD(4) molecules in large cages and ~0.9 in smaller ones. This data aids understanding of water-methane interactions in clathrate hydrates.
Area of Science:
- Materials Science
- Chemistry
- Physics
Background:
- Clathrate hydrates are crystalline solids trapping guest molecules within water cages.
- Understanding guest molecule distribution is crucial for hydrate properties and applications.
Purpose of the Study:
- To precisely determine the fractional occupancy of methane (CD(4)) within the cages of hexagonal (sH) methane hydrate.
- To refine intermolecular potential parameters for water-methane interactions.
Main Methods:
- Neutron diffraction experiments were conducted on CD(4):D(2)O clathrate hydrate samples.
- Samples were synthesized using a Paris-Edinburgh press.
- Data analysis employed the Rietveld refinement method.
Main Results:
- Average occupancy of 3.1 CD(4) molecules was found in the large 20-hedron (5(12)6(8)) cages.
- Pentagonal dodecahedron (5(12)) and 12-hedron (4(3)5(6)6(3)) cages in sH hydrate showed average occupancies of 0.89 and 0.90 CD(4) molecules, respectively.
- The study successfully avoided the co-formation of Ice VI, simplifying data analysis.
Conclusions:
- The refined cage occupancies provide critical data for modeling methane clathrate hydrates.
- Results contribute to a better understanding of hydrophobic interactions in hydrate systems.
- This work supports the development of accurate intermolecular potentials for hydrate research.
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