Tuning the Temperature and Pressure to Promote THF-CH ₄ and CH ₄ Hydrate Formation for Solidified Natural Gas Storage

The hydrate-based solidification is a promising technology for natural gas storage and transport, and further development requires optimization of the hydrate formation conditions to enhance kinetics and maximize the gas storage capacity as much as possible. The present study employs methane as a model natural gas and aims to enhance the formation kinetics of tetrahydrofuran (THF)-CH 4 and CH 4 hydrates by tuning the temperature and pressure conditions. The formation kinetics were investigated over a temperature range of 275.15 K–279.15 K, and the effect of the driving force for crystallization on gas storage capacity was examined. The results indicate that gas consumption improved by increasing the subcooling, and 275.15 K is an optimal temperature for THF-CH 4 and CH 4 hydrate formation. At 275.15 K and 7.0 MPa, the gas storage capacity reached 111 V/V (volume of CH 4 /volume of hydrate), approaching the theoretical maximum for structure II (sII) hydrate. The THF-CH 4 and CH 4 hydrate exhibited high stability under self-preservation conditions (271.15 K and 0.1 MPa), with only 5% CH 4 loss. The findings define potential process operating conditions for kinetically efficient gas hydrate crystallization aiming to capture as much methane as possible in the solid hydrate state.