CERAMIC MEMBRANES FROM SOL-GEL TECHNOLOGY

The use of membranes for gas separation is a relatively recent but rapidly growing technique. There are polymeric membranes for gas separations, but they are chemically and thermally unstable for some applications. Ceramic membranes can provide stability under drastic conditions, and for combustion gas purification they are probably the only useful membranes. The sol-gel technique facilitates preparation of thin ceramic layers with controlled pore size. Ceramic membranes were made by slip-casting sols on a support which was composed of two ceramic layers. Membranes made of pure Al2O3, a mixture of Al2O3-TiO2, and a mixture of Al2O3-SiO2 were tested for their ability to separate the gas mixtures N2-O2, N2-CO2 and N2-SO2. The mechanisms of flow through the porous membranes are discussed in relation to their efficiency of gas separation.