1 Adding a New Molecule to the Cages of the Hydrate Zoo
Clathrate hydrates are formed when low molecular-weight gases combine with water to form ice-like substances at high pressures and low temperatures, such as in the deep ocean. In nature, vast quantities of methane hydrates exist in the continental shelves and permafrost regions primarily due to the...
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| Language: | English |
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.506.6835 http://www.mbari.org/education/internship/07interns/papers/InternPapers/OMancillas.pdf |
| Summary: | Clathrate hydrates are formed when low molecular-weight gases combine with water to form ice-like substances at high pressures and low temperatures, such as in the deep ocean. In nature, vast quantities of methane hydrates exist in the continental shelves and permafrost regions primarily due to the methanogenesis of organic carbon. However, other molecules could form hydrates if present. Mustard gas, a chemical weapon with a history of ocean disposal, is known to form 1,4-thioxane (TO) when in contact with seawater. Because of its possible availability in these ocean disposal sites, the question arises as to whether TO could participate in the formation of clathrate hydrates. Hydrates containing TO were synthesized in the laboratory in a high-pressure cell and characterized with Raman spectroscopy. While TO was not found to stabilize a hydrate on its own, TO + CH4 hydrates were formed readily. Hydrate dissociation points were measured to create a phase equilibrium (P-T) diagram that allowed for comparisons of the stability of a TO + CH4 hydrate with pure CH4 hydrate. From the P-T behavior, TO stabilized the double hydrate with CH4 at higher temperatures compared to a simple CH4 hydrate. A double TO + N2 hydrate was also shown to form in this study. The formation of a hydrate containing TO with both CH4 and N2 showed that any desired small help gas should be able to stabilize a hydrate with TO. 3 |
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