Template-free nanosized ZSM-5 seeds with an average size of 15nm were prepared. By using these seeds, thin ZSM-5 zeolite membranes were prepared on the outer surface of a porous a-alumina tube with a pore size of 2μm in a gel system by varying-concentration synthesis with organic-free template. X-ray diffraction showed that the film consisted of well-crystallized ZSM-5 zeolite. Scanning electron microscopy indicated that the zeolite films on the supports were defect-free and that the film thickness was approximately 8μm. The permeances for H2, N2, CH4 and CO2 were 8.94 x 10-7, 3.27 x 10-7, 3.9 x 10-7, 3.14 x l0-7 and 0.874 x 10-7mol/m2sPa, respectively. The ideal selectivity of membranes at room temperature for H2/CO2, H2/N2 and H2/CH4 were 2.84, 2.73 and 2.29, respectively.

Synthesis of ZSM-5 Zeolite Membranes without Organic Templates using a Varying-Concentration Technique. Y.Cheng, R.Liao, J.Li, L.Wang, X.Sun: Rare Metals, 2006, 25[6], 384-9. See also: Chinese Journal of Inorganic Chemistry, 2005, 21[6], 796-800