HOLLOW FIBER INORGANIC MEMBRANES FOR GAS SEPARATIONS

Pure gas permeabilities of He, H-2, CO2, N2, and CO were measured for microporous silica hollow fiber membranes as a function of temperature. The transport mechanism for gas permeation is clearly non-Knudsen since several heavier gases permeate faster than lighter gases. An excellent correlation is obtained between permeability and kinetic diameter of the penetrant. The proposed mass transfer mechanism is a combination of surface diffusion and molecular sieving. High ideal separation factors (permeability ratios) are observed at 343 K for H-2/N2 and H-2/CO of 163 and 62.4, respectively, which compare very favorably with polymeric and molecular sieve gas separation membranes.