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).