THF Hydrates as Model Systems for Natural Gas Hydrates: Comparing Their Mechanical and Vibrational Properties

Tetrahydrofuran (THF) hydrates are often used as analogues for natural gas hydrates in experimental research because they can form at atmospheric pressure, despite the fundamental differences between THF and hydrocarbon guest molecules. In this work, we provide new and significant insights regarding the accuracy of this substitution, which has been a point of contention for many years, by investigating the elastic properties, crystal anisotropy, atomic structure, and vibrational properties of THF and THF-xenon hydrates using density functional theory. We found that our computed THF hydrate properties fall within the range of literature values for hydrocarbon hydrates, suggesting that THF hydrates are suitable substitutes for research into the mechanical properties of natural gas hydrates. Furthermore, we found that THF hydrates follow the same structure-property relationships as hydrocarbon hydrates: compressibility is governed primarily by hydrogen bond density, compressional wave velocity is a function of the average guest molecular mass, and the Young's modulus can be approximated from hydrogen bond properties. Taken together, these results have important implications for the development of THF and natural gas hydrate technologies.