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

Abstract

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 t90 (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.