High-quality NaA zeolite membranes were synthesized using hydrothermal treatment. To obtain
high-quality nanoporous inorganic membranes applicable to dehydration of natural gas, LTA zeolite
membranes were synthesized and modified in three stages. The morphology and structure of as-synthesized
seeds and membranes were characterized via scanning electron microscopy (SEM), field-emission
scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), and Energy Dispersive X-ray Spectroscopy
(EDX). The performance of membranes was evaluated in permeation of water vapor/methane. In
the first stage, NaA zeolite membranes were synthesized using secondary growth method via concentrated
gel, and showed ideal selectivity of 11 for water vapor/methane. In the second stage, NaA zeolite
membranes were synthesized using clear gel, while the effect of synthesis temperature on the membrane
structure and performance was also investigated. At synthesis temperature of 80 C, which was chosen as
the optimum temperature, the ideal selectivity of 14 was obtained for water vapor/methane. In the last
stage, the substrate of LTA zeolite membranes was modified via chlorination, and NaA zeolite membranes
were synthesized on chlorinated alumina substrates. Thionyl chloride was used as chlorinating reagent.
The membranes synthesized on chlorinated substrates showed ideal selectivity of 26 for water vapor/
methane. Moreover, KA zeolite membranes were prepared by ion-exchanging the zeolite layer of the
substrate-modified membranes. Ideal selectivity of 37 was observed for water vapor/methane for
substrate-chlorinated KA membranes.