| Preparation and characterization of ordered mesoporous silica membrane on porousceramic suppprt and its formation mechanism were investigated in this paper. Usingmesoporous silica sol synthesized by a direct-templating method, ordered mesoporoussilica membranes onα-Al2O3 microfiltration tube membrane were fabricated via avacuum-assisted dip-coating process. The structure, appearance of mesoporous silicapowder and membranes were characterized by SXRD, HRTEM, FT-IR, TG-DTA, SEM,nitrogen adsorption-desorption and gas permeability test. The results show that theas-synthesized materials are SBA-15 type mesoporous silica with a highly ordered2-dimension hexagonal mesostructure. SEM images indicate that the membranes supportedbyα-Al2O3 porous ceramic tube are defect-free. The gas permeance of N2 and theseparation factor of H2/N2 measured at room temperature and the pressure difference of0.10 MPa is 1.16×10-5 mol/m2·s·Pa and 2.74, respectively. It is showed that the gasdiffusion through the membranes is mainly governed by Knudsen diffusion mechanism.Using mesoporous silica sol synthesized by a sol-gel organic template method, orderedmesoporous silica membranes were assembled on the outer surface ofα-Al2O3 hollow fibervia a filtering coating process combined with evaporation induced self-assembly (EISA).The characterization results show that the as-synthesized materials are SBA-15 typemesoporous silica with an ordered 2-dimension hexagonal mesostructure. Nitrogenadsorption isotherm measurment indicates that pore volume and specific surface area of theunsupported membranes is 0.58 mL/g and 492.3 m2/g, respectively, which are both higherthan the unsupported membranes synthesized by a direct-templating method. SEM imagesindicate that the membranes supported byα-Al2O3 hollow fiber are defect-free. Gaspermeability test suggests that the gas diffusion through the membranes is stronglygoverned by Knudsen diffusion mechanism. The gas permeance of N2 and the separationfactor of H2/N2 measured at room temperature and the pressure difference of 0.10 MPa is1.58×10.5 mol/m2·s·Pa and 2.94, respectively. The formation mechanism of the mesoporoussilica membrane on the outer surface ofα-Al2O3 hollow fiber is discussed. It is mutualcontrolled by the pressure of the filtering coating process and evaporation induced selfassembly of surfactant-silica on the hydrophobic support.
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