Dissociation Behavior of C2H6 Hydrate at Temperatures below the Ice Point: Melting to Liquid Water Followed by Ice Nucleation
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- 作者：Hiroshi Ohno ; Ikumi Oyabu ; Yoshinori Iizuka ; Takeo Hondoh ; Hideo Narita ; Jiro Nagao
- 刊名：Journal of Physical Chemistry A
- 出版年：2011
- 出版时间：August 18, 2011
- 年：2011
- 卷：115
- 期：32
- 页码：8889-8894
- 全文大小：848K
- 年卷期：v.115,no.32(August 18, 2011)
- ISSN：1520-5215
文摘
The dissociation of C2H6 hydrate particles by slow depressurization at temperatures slightly below the ice melting point was studied using optical microscopy and Raman spectroscopy. Visual observations and Raman measurements revealed that ethane hydrates can be present as a metastable state at pressures lower than the dissociation pressures of the three components: ice, hydrate, and free gas. However, they decompose into liquid water and gas phases once the system pressure drops to the equilibrium boundary for supercooled water, hydrate, and free gas. Structural analyses of obtained Raman spectra indicate that structures of the metastable hydrates and liquid water from the hydrate decay are fundamentally identical to those of the stable hydrates and supercooled water without experience of the hydration. These results imply a considerably high energy barrier for the direct hydrate-to-ice transition. Water solidification, probably induced by dynamic nucleation, was also observed during melting.