[MIS17-P03] Equilibrium pressure of clathrate hydrates composed of isotopologue methane
Keywords:gas hydrate, methane hydrate, equilibrium pressure, stable isotope
Methane hydrate samples were synthesized in small pressure cells (volume: 5mL). Fine ice powder (1g) was put in a pressure cell, and introduced CH3D (purity: 98%, Taiyo-Nissan). Clathrate hydrate was formed by melting the ice powder at the temperature of 273.2K under high pressure of methane. We also prepared normal methane (purity: 99.99% for methane, but 98.9% for 12CH4, Takachiho Chemical Industry Co. Ltd.) hydrate as a reference, using the same preparation method. These pressure cells were placed in a temperature-controlled liquid bath, and measured their equilibrium pressures from 273.2K to 277.2K.
The equilibrium pressure of CH3D hydrate was about 0.07MPa larger than that of CH4 hydrate, and the results agreed with the previous report by Hachikubo et al. (2007).
Hachikubo A, Kosaka T, Kida M, Krylov A, Sakagami H, Minami H, Takahashi N, Shoji H (2007) Isotopic fractionation of methane and ethane hydrates between gas and hydrate phases. Geophys Res Lett 34: L21502. doi:10.1029/2007GL030557