Temperature dependence of gas transport and sorption in carbon molecular sieve membranes derived from four 6FDA based polyimides: Entropic selectivity evaluation

摘要: Abstract Temperature dependences of gas transport and sorption properties on four previously isothermally studied 6FDA based carbon molecular sieve (CMS) membranes: 6FDA/DETDA, 6FDA:BPDA(1:1)/DETDA, 6FDA/DETDA:DABA(3:2) 6FDA/1,5-ND:ODA(1:1), were examined over the temperature range from 35 °C to 50 °C. The permeability, diffusivity these materials are reported, activation energies permeation diffusion as well heats for gases CO2, CH4, O2, N2 compared. Permselectivity at was probed three pairs: CO2/CH4, O2/N2, N2/CH4, results show that selectivity is dominant factor in providing permselectivity. Diffusion can be factored further into an energetic entropic selectivity. dependence both their contributions overall discussed detail this study. All CMS membranes showed larger than unity discriminations. 6FDA/DETDA derived membrane, with most compact structure, largest N2/CH4 about 7.40, 4.24, 2.17 respectively. Analysis factors provides insights effects polymer precursor backbone structures key materials.