Experimental study of gas separation and permeation properties of silica-alumina asymmetric membranes prepared by sol-gel method

In the present study, templated and non-templated asymmetric silica membranes were prepared successfully by sol-gel polymerization route using cationic surfactants (CPB) as template agent. Silica membranes were characterized using N2 adsorption and SEM techniques. SEM results showed that after four times coating process a thin film of silica with a thickness of 2μm was deposited on support surface. BET and BJH methods using nitrogen physisorption data, revealed that the surface area of the membrane was increased significantly when a surfactant was used as template also the average pore size of the silica membrane was increased when the template was added. The prepared silica membranes were used in single gas permeation and mixed gas separation experiments. Permselectivities of H2/CH4 (149) and H2/CO2 (15.5) were obtained for free template membrane and 135 and 35, respectively for templated membrane at 400°C. Separation factors for H2/CH4 and H2/CO2 obtained from the mixed-gas separation experiments with 50/50 (vol%) gas mixtures were 131 and 12.9 for non-templated and 123 and 28.4 for templated silica membranes, respectively