Tuning 1,3-dioxolane concentration for optimized methane storage in sII hydrates

Abstract

Natural gas hydrates are a promising energy resource for achieving sustainable development goals; however, their effective and economical storage and transportation remain challenging. While the effects of thermodynamic conditions on gas hydrate storage efficiency have been extensively studied, the impact of 1,3-dioxolane (DIOX) concentration has rarely been explored. In this study, molecular dynamics simulation was employed to investigate the regulatory mechanism of DIOX concentration on the gas storage efficiency of DIOX–CH4 hydrate. As the DIOX concentration increased, the growth rate of DIOX–CH4 hydrate initially increased, peaked at 5.56 mol. %, and then declined. The growth rate of DIOX–CH4 hydrate was influenced by the DIOX concentration through the synergistic effects of DIOX and CH4 on the formation of different hydrate cages. The gas storage capacity (GSC) markedly decreased as the DIOX concentration increased and was predominantly controlled by the occupancy of 512 cages. This impact was further amplified by similar effects on the occupancy of 51264 cages. In addition, the influence of temperature and pressure on hydrate growth and GSC was evaluated at a DIOX concentration of 5.56 mol. %. The growth patterns, consistent with those reported in prior studies, indicated similar underlying growth mechanisms. The optimal storage efficiency was achieved at 270 K and 1 MPa. These findings suggest that DIOX–CH4 hydrate is a promising solution for the storage and transportation of natural gas at a DIOX concentration of 5.56 mol. % under mild conditions, which highlights its potential for practical application.