期刊
JOURNAL OF PHYSICAL CHEMISTRY C
卷 113, 期 28, 页码 12355-12361出版社
AMER CHEMICAL SOC
DOI: 10.1021/jp9009977
关键词
-
资金
- NSF [CTS-0419204]
The formation of methane-ethane (C1-C2) clathrate hydrate was studied with high-resolution, solid-state (13)C NMR and density functional theory techniques. The (13)C NMR experiments yield a number of significant findings: (1) the hydration number of C2(aq) is 26, (2) the initial quantity of C2-5(12)6(2) sI hydrate cages outnumber C1-5(12) cages at 274 K, (3) C1-C2 sII hydrate forms at a C1-C2 gas phase composition where only sI hydrate is thermodynamically stable, (4) the initial composition of C1-C2 sII hydrate at 268 K contains less than the original amount of C 1, (5) a quasi-liquid water layer solvating both C I and C2 exists at 268 K, (6) any C1(qll) and C2(qll) present at 253 K is too small to be detected, (7) the initial amounts of C1-C2 sI and sII hydrates formed at 253 K are much smaller than those formed at 268 and 274 K, and (8) Cl(aq), C2(aq) and C1(qll), C2(qll) facilitate the formation of C1-C2 sI and sII clathrate hydrate at 268 and 274 K, respectively. On the basis of these experimental observations, a model is developed that states that the aqueous hydration number of the most water-soluble clathrate hydrate former controls the structure of the clathrate hydrate that forms during the initial stages of the clathrate hydrate formation reaction. For methane-ethane clathrate hydrate, this means that ethane in a water liquid phase or quasi-liquid layer eliminates or adds two water molecules to its hydration shell to form the ethane-filled 5(12)6(2) or 5(12)6(4) cage building blocks of structure I or structure II clathrate hydrate, respectively. Density functional theory computations on methane-filled 5(12), ;5(12)6(2), and 5(12)6(4) and ethane-filled 5(12)6(2), 5(12)6(3), and 5(12)6(4) clathrate hydrate cages yield the stabilization energy of the gas-filled cages and provide theoretical evidence consistent with the experimentally based clathrate hydrate formation model. The proposed model is found to explain the results of other clathrate hydrate formation reactions.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据