Synthesis and Seeding Time Effect on the Inter-Crystalline Structure of Hydroxy-Sodalite Zeolite Membranes by Single Gas (H2 and N2) Permeation

Microporous hydroxy-sodalite zeolite membranes with different morphologies were synthesized via secondary growth technique with vacuum seeding on tubular α-Al2O3 supports at two different synthesis conditions (i.e. two different routes). Microstructures of the synthesized membranes were characterized by X-ray diffraction (XRD), Scanning electron microscope (SEM) and single gas permeation using H2 and N2. Also, the effect of seeding time on microstructure and performance of the synthesized hydroxy-sodalite top-layers was investigated at four different levels (60, 120, 180 and 240 s). Permeation test was carried out in order to attain a more exact comparison of both applied routes and seeding times. Microstructure of the synthesized hydroxy-sodalite zeolite membrane layers and the effects of the investigated factors on the elimination of inter-crystalline pores were evaluated by the permeation of single gases (H2 and N2) under different pressure differences at ambient temperature. The permeation results confirmed the high quality of the hydroxy-sodalite zeolite membranes manufactured via the first route at seeding time of 60s for the hydrogen purification under extremely low temperatures (< 200 K) and/or extremely high pressures (> 100 bars).