Highly Selective Encaging of Carbon Dioxide Molecules in the Mixed Carbon Dioxide and Nitrogen Hydrate at Low Temperatures

详细信息    查看全文

• 作者：Ji-Ho Yoon ; Taro Kawamura ; Michica Ohtake ; Satoshi Takeya ; Takeshi Komai ; Yoshitaka Yamamoto ; Hiroshi Emi ; Mitsuhiro Kohara ; Susumu Tanaka ; Osamu Takano ; Kazuo Uchida
• 刊名：Journal of Physical Chemistry B
• 出版年：2006
• 出版时间：September 7, 2006
• 年：2006
• 卷：110
• 期：35
• 页码：17595 - 17599
• 全文大小：108K
• 年卷期：v.110,no.35(September 7, 2006)
• ISSN：1520-5207

文摘

The structural identification and guest compositions of the mixed CO₂ and N₂ hydrates at low temperatureconditions were investigated by both theoretical predictions and experimental measurements. From the modelcalculations, at very low temperatures, the highly CO₂-concentrated hydrates over 95 mol % CO₂ on thebasis of water-free concentration could coexist with the gas mixtures of low CO₂ concentrations in equilibrium.X-ray diffraction measurements of the hydrates formed with the gas mixture of 3.16 mol % CO₂ and balancedN₂ indicate that the formed hydrates at all conditions considered in this study were identified as structure I,whereas the model predicts a structural transition to structure II around 220 K. However, it was also foundthat the formed hydrate samples contain a considerable amount of hexagonal ice resulting from incompleteconversion of ice to the hydrates. The compositional analysis suggests that a favorable encaging of CO₂ inthe mixed hydrate can be obtained by the hydrate formation at low temperatures and relative amount of CO₂molecules in the mixed hydrates increases with a decrease of temperature.