Experimental Verification of Methane鈥揅arbon Dioxide Replacement in Natural Gas Hydrates Using a Differential Scanning Calorimeter

详细信息    查看全文

• 作者：Seungmin Lee ; Yohan Lee ; Jaehyoung Lee ; Huen Lee ; Yongwon Seo
• 刊名：Environmental Science & Technology
• 出版年：2013
• 出版时间：November 19, 2013
• 年：2013
• 卷：47
• 期：22
• 页码：13184-13190
• 全文大小：365K
• 年卷期：v.47,no.22(November 19, 2013)
• ISSN：1520-5851

文摘

The methane (CH₄) 鈥?carbon dioxide (CO₂) swapping phenomenon in naturally occurring gas hydrates is regarded as an attractive method of CO₂ sequestration and CH₄ recovery. In this study, a high pressure microdifferential scanning calorimeter (HP 渭-DSC) was used to monitor and quantify the CH₄ 鈥?CO₂ replacement in the gas hydrate structure. The HP 渭-DSC provided reliable measurements of the hydrate dissociation equilibrium and hydrate heat of dissociation for the pure and mixed gas hydrates. The hydrate dissociation equilibrium data obtained from the endothermic thermograms of the replaced gas hydrates indicate that at least 60% of CH₄ is recoverable after reaction with CO₂, which is consistent with the result obtained via direct dissociation of the replaced gas hydrates. The heat of dissociation values of the CH₄ + CO₂ hydrates were between that of the pure CH₄ hydrate and that of the pure CO₂ hydrate, and the values increased as the CO₂ compositions in the hydrate phase increased. By monitoring the heat flows from the HP 渭-DSC, it was found that the noticeable dissociation or formation of a gas hydrate was not detected during the CH₄ 鈥?CO₂ replacement process, which indicates that a substantial portion of CH₄ hydrate does not dissociate into liquid water or ice and then forms the CH₄ + CO₂ hydrate. This study provides the first experimental evidence using a DSC to reveal that the conversion of the CH₄ hydrate to the CH₄ + CO₂ hydrate occurs without significant hydrate dissociation.