γ-Al2O3 membranes were successfully deposited on the top of porous α-Al2O3 support by sol-gel process and characterized by means of XRD, SEM,N2 adsorption and gas permeation. The γ-Al2O3 membranes, free of pin-holes and cracks, adhere tightly to the supports and have a thickness of about 7μm. When sintered at 400 ℃, γ-Al2O3 membranes have a narrow pore size distribution, with a pore diameter of 3.6nm, and the transport of both H2 and CO2 in supported γ-Al2O3 membrane is governed by Knudsen mechanism, with H2 permeance of 3.3×10 -6 molm -2 Pa -1 s -1 and H2/CO2 permselectivity close to the ideal Knudsen value at 50 ℃. The γ-Al2O3 membranes are suitable for being used as the substrates of microporous membranes.
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