Abstract
This paper reports formation of the gas-containing semiclathrate hydrate from tetra-n-butylammonium (TBA) carboxylates + CH_4 gas. Formation conditions of the gas hydrates were measured by the isochoric method using the high pressure autoclave. The TBA acrylate formed gas hydrates with CH_4 gas. Four stages of the hydrate formation were observed, which means that four hydrate phases may exist in the system. The phase diagram showed that there is the phase property-change depending on the formation pressure. Characterization of the TBA acrylate + CH_4 hydrate phase was also performed by the single crystal X-ray diffraction measurement. The crystal structure was identical with the TBA acrylate hydrate formed in the absence of gas, however, CH_4 molecules were found in the dodecahedral cage.
