Rapid nucleation of tetrahydrofuran (THF) hydrate is essential for developing a THF hydrate-based cold storage technology. Earlier works have hypothesized the role of aluminum complexes in initiating the nucleation of clathrate hydrates using aluminum metal electrodes and substrates. This study investigates if the nucleation promotional effect of hydrate can be achieved using the aluminum salt, AlCl₃, due to the formation of aluminum aqua complexes in water. Metal chlorides NaCl and MgCl₂ are also utilized to evaluate the effect of cation type in initiating nucleation, i.e., the effect of charge/radius ratio. The induction time is measured in a stirred reactor at various subcoolings and concentrations of 0.05, 0.1, 0.5, 1, and 2 wt %. The nucleation time is studied in two reactor configurations based on the nature of salt introduction in the THF solution, i.e., salt premixed in solution and salt injected inside the solution. The sudden rise in the reactor temperature due to hydrate formation is used as an indicator of hydrate formation. Results indicate that AlCl₃ promotes hydrate nucleation as AlCl₃ reduces induction time by 92.2% at 0.05 wt % concentration compared with water. Nearly instantaneous nucleation is also achieved by directly injecting AlCl₃. MgCl₂ and NaCl do not show a similar effect on induction time as AlCl₃. The pH and Raman spectra measurements with and without salts are carried out to explain the effect of cations on the THF–water solution.

中文翻译：

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铝阳离子能否促进 THF 水合物生长的成核？


四氢呋喃（THF）水合物的快速成核对于开发基于THF水合物的冷存储技术至关重要。早期的工作假设铝配合物在使用铝金属电极和基材引发笼形水合物成核中的作用。本研究探讨了使用铝盐 AlCl ₃ 是否可以通过在水中形成铝水复合物来实现水合物的成核促进效果。金属氯化物 NaCl 和 MgCl ₂ 也用于评估阳离子类型对引发成核的影响，即电荷/半径比的影响。诱导时间是在搅拌反应器中在不同的过冷度和 0.05、0.1、0.5、1 和 2 wt% 的浓度下测量的。根据 THF 溶液中盐引入的性质，即盐在溶液中预混合和盐注入溶液内部，在两种反应器配置中研究了成核时间。由于水合物形成而引起的反应器温度的突然升高被用作水合物形成的指标。结果表明，AlCl ₃ 促进水合物成核，因为与水相比，0.05 wt% 浓度的 AlCl ₃ 诱导时间缩短了 92.2%。通过直接注入AlCl ₃ 也可以实现几乎瞬时成核。 MgCl ₂ 和 NaCl 对诱导时间的影响与 AlCl ₃ 不同。进行有盐和无盐的 pH 和拉曼光谱测量，以解释阳离子对 THF 水溶液的影响。