Study of mass transfer through new templated silica membranes prepared by sol–gel method

Different templated silica membranes were prepared by sol–gel polymerization route using cationic and non-ionic surfactants as template agent. The αα-alumina support and prepared silica membranes were used in single-gas permeation and mixed-gas separation experiments. Gas transport mechanisms through porous membranes as well as influences of main parameters in each mechanism were reviewed in detail. The characteristics of gas transport through the support as macroporous membrane and templated silica membranes were investigated with several gas diffusion models in the range of 200–400 °C and at pressure differences ranging from 0.2 to 1 bar. The experimental gas permeation data of alumina support were analyzed using the viscous flow model. The results clearly showed good agreement between the model analysis and the experimental data. The prepared templated asymmetric silica membranes represented different behaviors due to their different characteristics. The experimental data of the silica membrane which is templated by polyoxyethylene (4) lauryl ether (Brij30) showed that the permeation followed the Knudsen diffusion model in which the permeance decreased with increasing temperature. The experimental gas permeation data of cetylpyridinium bromide (CPB) templated silica membrane as well as non-templated silica membrane, as microporous membranes, revealed that they followed the configurational diffusion model in which the permeance increased with temperature. Separation factors obtained from the mixed-gas separation experiments with 50/50 (vol%) gas mixtures were slightly lower than the permselectivities.