Abstract: ZSM-5 zeolite membranes synthesized on rough porous α-Al₂O₃ tubes with an average pore size of 2μm in the absence of organic template crystallization gel were investigated. The
molar composition of nanosized ZSM-5 seeds was 9TPAOH: 25TEOS: 0.25 Al₂O₃: 480H₂O. Porous α-Al₂O₃ tubes were seeded with these colloidal TPA-silicalite-1 crystals with
a size of 90～100nm. The seeded supports were calcined in accordance with DTA/TG of nanosized ZSM-5 and treated in a synthesis sol-gel to grow the seed crystals into ZSM-5 membranes on the outer
surface of porous α-Al₂O₃ tubes. The molar composition of the crystallization gel without organic templates was 67Na2O:Al₂O₃: 240SiO₂: 6000H₂O. XRD patterns show that the
film consists of well-crystallized ZSM-5 zeolite. SEM investigation indicates that the zeolite films on the supports are defect free and that the film thickness is approximately 8μm. The permeability
for H₂ is 1.50×10^-6mol$·m^-2·s^-1·Pa^-1 and the ideal separation factor for H₂/N₂ is about 3.85.

Key words: nanosized seeds, template, ZSM-5 zeolite membrane, permeance