title: Structure-H methane + 1,1,2,2,3,3,4-heptafluorocyclopentane mixed hydrate at pressures up to 373 MPa.
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.
authors.affiliation: Division of Chemical Engineering, Department of Materials Engineering Science, Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan.
authors.forename: Sumihiro
authors.initials: S
authors.lastname: Suzuki
authors.forename: Yuuki
authors.initials: Y
authors.lastname: Matsumoto
authors.forename: Yoshito
authors.initials: Y
authors.lastname: Katsuta
authors.forename: Shunsuke
authors.initials: S
authors.lastname: Hashimoto
authors.forename: Takeshi
authors.initials: T
authors.lastname: Sugahara
authors.forename: Kazunari
authors.initials: K
authors.lastname: Ohgaki
mesh_terms: D003517:Cyclopentanes / Q000737:chemistry*; D006845:Hydrocarbons, Fluorinated / Q000737:chemistry*; D008697:Methane / Q000737:chemistry*; D015394:Molecular Structure; D011312:Pressure; D014867:Water / Q000737:chemistry; D005466:Fluorocarbons
chemical_list: D003517:Cyclopentanes; D006845:Hydrocarbons, Fluorinated; D008697:Methane; D014867:Water; C585233:1,1,2,2,3,3,4-heptafluorocyclopentane; D005466:Fluorocarbons