Spectroscopic Explanation of Metastablity in Gas Hydrate Formation

Clathrate hydrates have been researched for their various applications such as natural gas hydrate production, energy gas storage, carbon capture and sequestration, and synthesis and fabrication of versatile energy devices. The structure H(sH) hydrate is important in the oil industry because its large cage(5¹²6⁸) can accommodate larger molecules found in crude oil regions that cannot occupy the large cages of structure I(sI) (5¹²6²) and structure II(sII) (5¹²6⁴) hydrates. However, there is only limited research of sH hydrate, contrary to sI and sII. The major difficulties of understanding of sH hydrate are that 1) sH can be formed only in the presence of large guest molecules (LGMs) and 2) most of the LGMs are insoluble or sparingly soluble in water. Also, there have been no reports on sI-sII-sH whole-phase-behaviour. The aforementioned barriers can be overcome by exploiting hydrophilic LGMs such as hexamethyleneimine(HMI). These highly water-soluble LGMs can create a homogeneous solution, which guarantees uniform hydrate phases. Therefore, the kinetic behaviour of gas hydrate phases can be compared using HMI at a laboratory scale.