Spectroscopic identification on cage occupancies of binary gas hydrates in the presence of ethanol.

Ethanol has been widely used for inhibiting gas hydrate formation due to its cost and efficiency. However, recent research showed that ethanol can act as a hydrate former when coguested with CH(4) molecules at various ethanol concentrations. Herein, we report tuning phenomenon of the gas hydrate in the presence of ethanol by means of spectroscopic measurements. On the basis of the experimental results, it is verified that ethanol molecules cannot inhibit hydrate formation effectively, but enhance the gas storage in the hydrate phase when a much less amount of the inhibitor than the stoichiometric concentration is used. The cage occupancies of binary hydrate systems in the presence of a thermodynamic inhibitor, showing similar guest behaviors in the presence of a promoter such as tetrahydrofuran (THF), can provide useful information on the molecular behaviors of guest species.