Separation of carbon dioxide by asymmetric hollow fiber membrane of cellulose triacetate

Permeation behavior of pure CO 2 , O 2 , and N 2 and separation characteristics of CO 2 –air mixtures were examined using hollow fiber modules of asymmetric cellulose triacetate membrane at 30°C. The ideal separation factor for CO 2 relative to N 2 ranged from 21 to 24. Permeation behavior for pure CO 2 was interpreted in terms of the total immobilization model, i.e., a limiting case of the dual‐mode mobility model for glassy polymer, where the diffusion coefficient for Henry's law mode is not assumed to be constant and depends on gas pressure via a modified free‐volume model. Based on pure gas permeabilities to CO 2 , O 2 , and N 2 , simulation for the separation of CO 2 –air mixtures was made using a counter‐current plug flow model, and the result fitted the corresponding experimental data fairly well. Membrane plasticization induced by CO 2 had negligible effect on permeation to mixture of CO 2 and air in the range of CO 2 composition up to 50% and upstream total pressure up to 1.5 MPa.