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Controlling the Size, Shape and Stability of Supramolecular Polymers in Water
Published on: August 2, 2012
Structure transition and swapping pattern of clathrate hydrates driven by external guest molecules
Sun-Hwa Yeon1, Jiwoong Seol, Huen Lee
1Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology, Yuseong-gu, Daejeon 305-701, Republic of Korea.
Journal of the American Chemical Society
|September 21, 2006
Summary
Methane hydrates (sII and sH) transform into structure I (sI) under methane gas pressure, altering lattice dimensions. This finding supports the prevalence of natural sI methane hydrates in marine sediments.
Area of Science:
- Geochemistry
- Materials Science
- Crystallography
Background:
- Clathrate hydrates, particularly methane hydrates, play a crucial role in natural gas storage and geological processes.
- Understanding hydrate structure transitions is key to predicting their stability and behavior in various environments.
Purpose of the Study:
- To investigate the structural transformation of sII and sH methane hydrates under external methane (CH4) guest molecule pressure.
- To elucidate the impact of these transformations on host-guest network lattice dimensions.
- To provide insights into the formation mechanisms of naturally occurring methane hydrates.
Main Methods:
- High-power decoupling 13C NMR spectroscopy to identify structural changes.
- Raman spectroscopy to analyze molecular vibrations and confirm phase transitions.
- Synthesis and characterization of mixed CH4 + C2H6 hydrates (sII) and hydrocarbon + CH4 hydrates (sH).
Main Results:
- Observed structural transformation of sII and sH methane hydrates to the crystalline framework of sI under CH4 pressure.
- Demonstrated a favorable change in lattice dimensions of the host-guest networks post-transformation.
- Identified cage-specific swapping patterns of multi-guests within the hydrate structures.
Conclusions:
- The study provides evidence for the structural transition of methane hydrates to sI under specific conditions.
- Findings support the hypothesis for the predominant occurrence of naturally occurring sI methane hydrates in marine sediments.
- The observed guest-swapping phenomena offer a new perspective on inclusion mechanisms in clathrate materials.
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