RAMAN STUDY OF THE METHANE + TBME MIXED HYDRATE IN A DIAMOND ANVIL ...
It is well known that methane hydrate undergoes several phase transformations at high pressures. At room temperature and low to moderate pressure, methane and water form a stable cubic structure I (sI) hydrate that is also known as MH-I. The structure is transformed to a hexagonal phase (sH/MH-II) a...
| Main Authors: | , , , , |
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| Format: | Text |
| Language: | English |
| Published: |
The University of British Columbia
2008
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| Subjects: | |
| Online Access: | https://dx.doi.org/10.14288/1.0040981 https://doi.library.ubc.ca/10.14288/1.0040981 |
| Summary: | It is well known that methane hydrate undergoes several phase transformations at high pressures. At room temperature and low to moderate pressure, methane and water form a stable cubic structure I (sI) hydrate that is also known as MH-I. The structure is transformed to a hexagonal phase (sH/MH-II) above 1.0GPa. Another phase transformation occurs above 1.9GPa where the filled ice structure (MH-III) is stable up to 40 GPa before a new high pressure phase transition occurs. Experiments at such high pressures have to be performed in a diamond anvil cell (DAC). Our main interest, though, is to form sH methane hydrate at a lower pressure than reported in previous studies but with some methane in the large cages consequently increasing the methane content. This can be accomplished by introducing the molecules of the large hydrate forming substance (tert-butyl methyl ether/TBME) at a concentration slightly below the stoichiometric amount as suggested by molecular dynamics simulations. In this study we have ... |
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