Clathrate hydrate formed with methane and 2-propanol: Confirmation of structure II hydrate formation

This paper reports confirmation of structure II hydrate formation in a methane-2-propanol-water system, which was previously suggested by Østergaard et al. (Ind. Eng. Chem. Res. 2002, 41, 2064-2068) based on a comparison of the phase-equilibrium data with corresponding statistical- thermodynamics predictions. A hydrate crystal sample was prepared with a 16.4 mass % aqueous solution of 2-propanol pressurized with methane and then subjected to a powder X-ray diffraction analysis. The X-ray diffraction pattern thus obtained from the sample indicated that the crystallographic structure of the hydrate was structure II. The pressure-temperature data for aqueous liquid-hydrate-methane-rich vapor three-phase equilibrium in a temperature range from T = 273 to 283 K are also reported.