Sorption studies of microporous sol-gel modified ceramic membranes

Abstract

Sorption experiments with H2, CO2, CH4 and iso-C4H10 were performed on microporous SiO2 and SiO2/TiO2 (30 mol% TiO2) non-supported membrane top-layers using volumetric and gravimetric techniques. For silica, the sorption capacity decreases in the order CO2>iso-C4H10>CH4>H2 at temperatures <373 K. The isosteric heat of adsorption q st is 23, 24, 10 and 6 kJ·mol−1 for respectively CO2, iso-C4H10, CH4 and H2. The sub-atmospheric adsorption isotherms are of Henry-type for temperatures equal and higher than 348 K for CO2, temperatures higher than 373 K for iso-C4H10, temperatures equal and higher than 194 K for H2 and for temperatures equal and higher than 273 K for CH4. The sorption capacity for the SiO 2/TiO 2 sample was only slightly lower than for silica, as may be expected due to the lower porosity.