Permeation of gases through a supported alumina membrane

The permeations of He, N₂, and CO₂ through the supported alumina membrane were studied in this work. The permeabilities of gases were measured under temperature ranges of 299.4-372.7 K and pressure up to 220 kPa. Experimental results showed that the gas transported through the alumina membrane can be described by the combination of Knudsen diffusion, Poiseuille flow, and surface diffusion. However, Knudsen diffusion played the most important role on the permeabilities of gases. A semi-empirical expression of permeability was obtained as a function of temperature and pressure for each pure gas. The permeate fluxes of He-N₂, He-CO₂, and N₂-CO₂ mixtures were calculated from permeabilities of pure gases with assumptions of perfect gas behavior and complete mixing permeator. The predicted data were coincidence with the experimental results except for N₂-CO₂ mixture. The deviation of permeability between the predicted and the experimental data for N₂-CO₂ system can be reduced by taking into account of viscosity effect.