Crystal-growth studies of natural gas clathrate hydrates using a pressurized optical cell
- Exxon Research and Engineering Company, Annandale, NJ (United States)
The crystal-growth behavior of structure I (sI), structure II (sII), and structure H (sH) clathrate hydrates has been studied using a specially designed, pressurized optical cell. Single crystals of each hydrate type, methane sI, methane-propane (95%-5%) sII, and methane-methylcyclopentane sH, were grown in equilibrium with aqueous liquid + vapor {+-} liquid hydrocarbon. Each structure type exhibits characteristic crystal morphology, which suggests that crystal habit in natural settings, such as sea-floor outcrops, may allow visual identification of hydrate types. In addition, the relative growth-rate schemes and resulting crystal morphology of each structure can be related to the unit-cell density distribution of the small cages in each structure. Four-phase P-T equilibrium data for methane-methylcyclopentane sH data were also measured using optical methods. Evaluation of these and previously published phase-equilibrium data for all three known hydrate structures strongly suggests that hydrate assemblages of coexisting sII and sH should be common in natural settings. 63 refs., 6 figs., 6 tabs.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 518372
- Journal Information:
- American Mineralogist, Journal Name: American Mineralogist Journal Issue: 1-2 Vol. 82; ISSN AMMIAY; ISSN 0003-004X
- Country of Publication:
- United States
- Language:
- English
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