Enhanced clathrate hydrate formation at ambient temperatures (287.2 K) and near atmospheric pressure (0.1 MPa): Application to solidified natural gas technology

Solidified natural gas is a promising alternative for improving natural gas storage owing to its safe and envi-ronmentally friendly properties. However, harsh conditions limit its application. In this study, the R141b was used as a thermodynamic promoter to enhance methane hydrate formation under mild conditions. Addition of R141b to the water system significantly shifted the phase equilibrium boundary to lower pressures and higher temperatures, in which the R141b-CH4 hydrate can be formed at 0.1 MPa and 287.2 K. Notably, the final pressure of the cell after hydrate formation was near the atmospheric pressure even at an initial pressure of 5.384 MPa, suggesting that the R141b-CH4 mixed hydrate had milder storage conditions and lower costs than liquefied natural gas (approximately 110 K). The higher initial pressure significantly reduces the induction time and increases gas storage. The mechanism of unusual kinetic characteristics of the R141b-CH4 hydrates that were observed can be attributed to the different nucleation behaviour of CH4, R141b, and R141b-CH4 hydrates. This study provides evidence of a new promoter using the solid hydrate method under mild conditions that can be alternatively used for the storage and transport of natural gas, thereby increasing the supply of clean energy without the high economic costs and safety issues.

Automated summary

This study utilizes R141b as a thermodynamic promoter to enhance methane hydrate formation under mild conditions, significantly reducing the phase equilibrium boundary and forming R141b-CH4 mixed hydrate at 0.1 MPa and 287.2 K. It provides evidence of a new promoter that can be alternatively used for the storage and transport of natural gas, offering milder storage conditions and lower costs compared to liquefied natural gas.