Self-preservation of methane hydrate revealed immediately below the eutectic temperature of the mother electrolyte solution
Self-preservation of methane hydrate revealed immediately below the eutectic temperature of the mother electrolyte solution
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DOI：
10.1016/j.ces.2013.01.014
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发表时间：
2013-03
影响因子：
4.7
通讯作者：
Hiroshi Sato;H. Sakamoto;Shotaro Ogino;Mimachi Hiroko;T. Kinoshita;Iwasaki Toru;Sano Kenichi;
中科院分区：
文献类型：
--
作者：
Hiroshi Sato;H. Sakamoto;Shotaro Ogino;Mimachi Hiroko;T. Kinoshita;Iwasaki Toru;Sano Kenichi;
为了阐明天然气水合物的自保存现象，在常压下，测量了由稀电解质溶液制备的甲烷水合物在温度从233 K升高到273 K时的分解速率。在电解质+水体系的共晶温度（TE）附近，分解被显著抑制。然而，当电解质的浓度相对较高时，在TE处发生分解速率的短暂激增。我们推测，电解质晶体的存在增加了水分子的流动性。这促进了连续冰层的形成，作为甲烷扩散的障碍。随着温度的升高，这种机制变得明显。然而，当温度超过TE时，稳定液体的出现导致冰层局部融化，甲烷扩散的屏障减弱。
To elucidate the phenomenon of self-preservation of gas hydrates, the decomposition rates of methane hydrates prepared from dilute electrolyte solutions were measured while the temperature was increased from 233 to 273K at atmospheric pressure. Decomposition was significantly suppressed near the eutectic temperature (TE) of the electrolyte+water system. When the concentration of the electrolyte was relatively high, however, a transitory upsurge in the decomposition rate occurred at TE. We speculate that the presence of electrolyte crystals increases the mobility of water molecules. This promotes the formation of a contiguous layer of ice that acts as an obstacle to diffusion of methane. This mechanism becomes marked as the temperature increases. When the temperature exceeds TE, however, the occurrence of stable liquid causes local melting of the ice layer with attenuation of the barrier for methane diffusion.