| Summary: | The demand for natural gas globally is rising due to the need for energy caused by population and economic growth. This demand calls for more effective approaches to store and transport natural gas, which consists primarily of methane. Gas hydrates, ice-like materials that encapsulate gas molecules, possess the potential for high energy density. The feasibility of this methane storage method relies upon the efficiency of hydrate formation, which must be improved before it can be developed commercially. In this study, two microporous zeolitic imidazolate frameworks, ZIF-8 (zinc based) and ZIF-67 (cobalt based), were evaluated as methane hydrate formation promoters. ZIF-8 and ZIF-67 increased the water-to-hydrate conversion in a water-and-methane system from 4.5% to 85.6% and 87.7%, respectively, thus remarkably improving the gas storage by a factor of 14.4 and 14.7, respectively. Isothermal tests revealed that ZIF-8 and ZIF-67 reduced the methane hydrate nucleation induction time by 51.6% and 92.2%, respectively. Both ZIFs maintained their structural integrity and exhibited consistent recyclability, which indicates that the materials would have a long lifecycle as promoters. These results show that ZIF-8 and ZIF-67 are effective gas hydrate growth promoters, and application of these ZIFs makes methane storage in gas hydrates industrially appealing.
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