Methane and Carbon Dioxide Hydrate Phase Behavior in Small Porous Silica Gels: Three-Phase Equilibrium Determination and Thermodynamic Modeling
Methane and Carbon Dioxide Hydrate Phase Behavior in Small Porous Silica Gels: Three-Phase Equilibrium Determination and Thermodynamic Modeling
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DOI：
10.1021/la0257844
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发表时间：
2002-11
期刊：
影响因子：
3.9
通讯作者：
Y. Seo;Huen Lee;T. Uchida
中科院分区：
文献类型：
--
作者：
Y. Seo;Huen Lee;T. Uchida
测定了CH 4+水和CO2 +水二元混合物在公称直径为6.0、15.0和30.0 nm的硅胶孔中的水合相平衡，并与基于货车der Waals和Platteeuw模型的计算结果进行了比较。在一定温度下，孔隙水合物的三相H-LW-V平衡曲线与体相水合物的三相H-LW-V平衡曲线相比，随孔隙尺寸的增大而向高压区移动。多孔硅胶中水的活度用一个修正项来表示，以考虑毛细管效应和活度降低。利用Uchida等人最近提出的水合物与液态水之间的界面张力值，5计算值与实验值吻合较好。通过核磁共振波谱分析，发现硅胶孔（6.0、15.0和30.0 nm）中的CH 4水合物的结构和水合数与本体CH 4水合物的结构和水合数相同。
Hydrate phase equilibria for the binary CH4 + water and CO2 + water mixtures in silica gel pores of nominal diameters 6.0, 15.0, and 30.0 nm were measured and compared with the calculated results based on van der Waals and Platteeuw model. At a specified temperature, three phase H−LW−V equilibrium curves of pore hydrates were shifted to the higher pressure region depending on pore sizes when compared with those of bulk hydrates. The activities of water in porous silica gels were expressed with a correction term to account for both capillary effect and activity decrease. By using the values of interfacial tension between hydrate and liquid water phases which were recently presented by Uchida et al.,5 the calculation values were in better agreement with the experimental ones. The structure and hydration number of CH4 hydrate in silica gel pores (6.0, 15.0, and 30.0 nm) were found to be identical with those of bulk CH4 hydrate through NMR spectroscopy.