Revealing Zeolites Active Sites Role as Kinetic Hydrate Promoters: Combined Computational and Experimental Study

Clathrate hydrates are emerging as a novel storage medium for safe and compact methane storage. However, their industrial-scale applicability is hindered by relatively lower gas uptake and sluggish formation kinetics. In this study, we have employed zeolites with acidic (H-Y, FAU-type) and basic (Na-X, FAU-type) surface properties as kinetic hydrate promoters (KHPs). The impact of physical parameters as pressure and the gas-to-liquid ratio has also been studied. In a combined experimental and computational study, we assessed the performance of the two types of zeolites in different concentrations and pressures for binary CH4-THF clathrate hydrate synthesis in a nonstirred configuration. The kinetic study results showed that the acidic zeolite (H-Y) exhibited superior performance over the basic one (Na-X), reaching its optimum at 0.5 wt % zeolite, which agreed well with the DFT calculations. The methane conversion reached 94.25% at this concentration and a relatively mild pressure (6 MP). The induction time and t(90) (time to reach 90% of final gas uptake) were reduced by 35% and 31%, respectively. Our results open the door for a better understanding of the role of acidic zeolites as possible environmental benign KHPs that can help the utilization of water as a medium for green energy storage and transportation.

Automated summary

Clathrate hydrates are a potential storage medium for methane, but their applicability is limited by low gas uptake and slow formation kinetics. This study explores the use of acidic and basic zeolites as kinetic hydrate promoters (KHPs). The results show that acidic zeolites outperform basic ones, with the optimum performance achieved at 0.5 wt% zeolite concentration.