High-efficiency gas storage via methane-tetrahydrofuran hydrate formation: Insights from hydrate structure and morphological analyses

Hydrate-based gas storage and transportation is limited by harsh hydrate formation conditions and low formation rate, which cannot be used in large-scale commercial applications. In this work, based on the good thermodynamic properties of tetrahydrofuran (THF), we systematically studied the hydrate formation kinetics of CH 4 –THF (5.56 mol%) hydrate under static conditions (4 MPa and 282.2–288.2 K). The experimental results showed that CH 4 storage was greatest at 288.2 K within 5 h, reaching a value of 0.0483 ± 0.005 mol/mol, which was 19.85% higher than that at 282.2 K. Based on the quantitative results of Raman spectroscopy, the proportion of CH 4 in the small cages of sII hydrates increased by approximately 11.63% with an increase in temperature from 282.2 to 288.2 K. In addition, by observing the growth behavior and morphology of CH 4 -THF hydrate, it was found that the morphology of CH 4 -THF hydrate became looser with the decrease of undercooling ( Δ T s u b $\mathrm{\Delta }{T}_{\mathrm{s}\mathrm{u}\mathrm{b}}$ ), which effectively promoted the formation of hydrate. Furthermore, the energy consumption during CH 4 -THF hydrate formation was greatly decreased with the increase of temperature, saving about 98.62% at 288.2 K. This study provides a theoretical basis for the storage and transportation of natural gas via the solid hydrate method.