Optical Interpretation of the Chemical Process of CH4鈥揅O2 Exchange and Its Application to Gas Hydrate Production

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• 作者：Hyery Kang ; Yun-Ho Ahn ; Dong-Yeun Koh ; Seongheun Kim ; Jaehun Park ; Huen Lee
• 刊名：Journal of Physical Chemistry C
• 出版年：2015
• 出版时间：September 17, 2015
• 年：2015
• 卷：119
• 期：37
• 页码：21353-21357
• 全文大小：307K
• ISSN：1932-7455

文摘

The guest-exchange method (or replacement) for methane production from gas hydrates has recently received attention because it can be used for both carbon dioxide sequestration and methane production. The structure of gas hydrates is maintained as a structure I (sI) hydrate while methane molecules are exchanged with carbon dioxide. In this study, CH₄ + CO₂ mixed gas hydrates were examined under terahertz light at various temperatures to simulate CH₄鈥揅O₂ exchange reactions. Each gas hydrate composition examined was a representative composition at each step of the exchange reaction. The molecular composition was also accurately analyzed by gas chromatography. Refractive indices calculated by the terahertz time-domain spectroscopy (THz-TDS) of gas hydrate samples were correlated to the guest composition, and this novel method was proven to be used to quantify the extent of replacement via optical constant. Furthermore, changes in the water framework from the sI hydrate to ice using THz-TDS were investigated with an increasing temperature. Overall, this study reveals the process of guest exchange and phase transition from a gas hydrate to ice via the optical properties in the terahertz region, and it offers a powerful tool in gas hydrate production.