Abstract: The synthesis of Atype zeolite membranes on porous α Al₂O₃ supports via the method of seeding plus secondary hydrothermal crystallization has been studied. The seed layers, which were prepared from colloidal Atype zeolite synthesized from the reaction mixture of n[(TMA)₂O]: n (SiO₂): n (Al₂O₃): n (Na₂O): n (H₂O)=13.4:11.25:1.8:0.3:700, were treated by steam of ammonia to inhibit the formation of cracks when dried. Compact zeolite membranes constituted with multipletwined zeolite crystals were accessed by hydrothermal growth of seed layers in the reaction sol of n (Na₂O): n (Al₂O₃): n (SiO₂): n (H₂O)=3:1:1:800. In highly alkaline hydrothermal solutions, seed layers tended to dissolve and loose zeolite membranes with many defects were obtained. The gas permeanbility on Atype zeolite membrane dried at 393 K, in which water molecular still inhabited the zeolitic channels, was quite low, suggesting that the membrane was close to free of defects. Defects were formed mainly due to different thermal expansion coefficients between α Al₂O₃ support and zeolite membrane when the calcinations at 823 Kwas carried out to free the channel of membrane zeolites.

Key words: Zeolite membrane, Membrane separation, Atype zeolite, Inorganic membrane