Gas transport mechanisms 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. a-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 have been reviewed in details. 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 200-400oC 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 and results clearly showed good agreement between the model analysis and the experimental data. The prepared templated asymmetric silica membranes represented different behavior each other due to their different characteristics. The experimental data of silica membrane which 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 mixed-gas separation experiments with 50/50 (vol%) gas mixtures were slightly lower than the permselectivities