Clathrate Hydrate Formed with Methane and 2-Propanol:  Confirmation of Structure II Hydrate Formation

Abstract

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.

Hydrate equilibrium data for the CO2 + N2 system with the use of tetra-n-butylammonium bromide (TBAB), cyclopentane (CP) and their mixture

“…Ohmura et al [20], a pressure-temperature diagram was obtained for each experimental run from which the hydrate dissociation condition could also be determined. For measuring an equilibrium condition at a higher pressure, the pressure of the system was increased by successively supplying gas mixture to the equilibrium cell until achieving the desired pressure and then repeating the temperature cycle.…”

Four phase hydrate equilibria of methane and carbon dioxide with heavy hydrate former compounds: Experimental measurements and thermodynamic modeling

“…To find the equilibrium conditions of H-L Aq -L HC -V for methane/ carbon dioxide as the help gas and benzene/cyclohexane as the heavy hydrate former, isochoric pressure-search procedure [25][26][27] was applied in this work. The complete experimental runs consist of two different paths: cooling path, in which the temperature of the cell is decreased stepwise until the hydrate forms, and heating path, in which the temperature of the cell is returned to the initial value.…”

“…Our main goal was to investigate hydrate formation pressure for four phase equilibrium conditions, [25][26][27]. To demonstrate the reliability of the experimental method, validation tests were performed and the generated data were compared with literature data [2,3,[19][20][21][22][23][24].…”

Clathrate Hydrates of Isopentane + Carbon Dioxide and Isopentane + Methane: Experimental Measurements of Dissociation Conditions

“…The temperature was then increased with steps of 0.1 K. At every temperature step, temperature was kept constant with sufficient time to achieve an equilibrium state in the vessel. In this way, a pressure-temperature diagram was obtained for each experimental run, from which we determined the hydrate dissociation point [2][3][4]11]. If the temperature is increased in the hydrate-forming region, hydrate crystals partially dissociate, thereby substantially increasing the pressure.…”

“…If the temperature is increased in the hydrate-forming region, hydrate crystals partially dissociate, thereby substantially increasing the pressure. If the temperature is increased outside the hydrate region, only a small increase in the pressure is observed as a result of temperature increase [2][3][4]11]. Consequently, the point at which the slope of pressure-temperature data plots changes sharply is considered to be the point at which all hydrate crystals have dissociated and hence reported as the dissociation point [2-4, 11].…”