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Updated: May 11, 2026

Methane Hydrate Crystallization on Sessile Water Droplets
Published on: May 26, 2021
Structure-H methane + 1,1,2,2,3,3,4-heptafluorocyclopentane mixed hydrate at pressures up to 373 MPa
Sumihiro Suzuki1, Yuuki Matsumoto, Yoshito Katsuta
1Division of Chemical Engineering, Department of Materials Engineering Science, Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan.
Abstract:
Thermodynamic stability boundary of structure-H hydrates with large guest species and methane (CH4) at extremely high pressures has been almost unclear. In the present study, the four-phase equilibrium relations in the structure-H CH4 + 1,1,2,2,3,3,4-heptafluorocyclopentane (1,1,2,2,3,3,4-HFCP) mixed hydrate system were investigated in a temperature range of (281.05 to 330.12) K and a pressure range up to 373 MPa. The difference between equilibrium pressures in the structure-H CH4 + 1,1,2,2,3,3,4-HFCP mixed hydrate system and the structure-I simple CH4 hydrate system gets larger with increase in temperature. The structure-H CH4 + 1,1,2,2,3,3,4-HFCP mixed hydrate survives even at 330 K and 373 MPa without any structural phase transition. The maximum temperature where the structure-H CH4 + 1,1,2,2,3,3,4-HFCP mixed hydrate is thermodynamically stable is likely to be beyond that of the structure-H simple CH4 hydrate.
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