In Situ Raman Analysis on the Dissociation Behavior of Mixed CH4–CO2 Hydrates

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• 作者：Xuebing Zhou ; Zhen Long ; Shuai Liang ; Yong He ; Lizhi Yi ; Dongliang Li ; Deqing Liang
• 刊名：Energy & Fuels
• 出版年：2016
• 出版时间：February 18, 2016
• 年：2016
• 卷：30
• 期：2
• 页码：1279-1286
• 全文大小：457K
• ISSN：1520-5029

文摘

Previous studies have indicated that CH₄–CO₂ hydrate replacement is closely related to the crystal dissociation and reformation processes. To further elucidate the replacement mechanism, the melting processes of mixed CH₄–CO₂ hydrates were characterized using in situ Raman spectroscopy and compared to that of pure CH₄ and CO₂ hydrates. Analysis results from powder X-ray diffraction showed that the crystalline structure of the mixed CH₄–CO₂ hydrates is strucutre I. The current study suggested that the hydrate crystal units collapse as an entity with no clear dependence upon gas distributions within the hydrate phase. The dissociation time was found to be stoichastic, consistent with the polycrystalline nature of the hydrate particles. Interestingly, for hydrates containing CH₄, the Raman peaks of both CH₄ and CO₂ in the hydrate phase showed a temporary rise during the hydrate dissociation processes, suggesting the reformation of hydrates below the hydrate dissociation surface. A dissociation inside the hydrate crystal together with the self-preservation effect was assumed to be responsible for such a phenomenon.