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 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.