PERMEATION OF PURE CARBON-DIOXIDE AND METHANE AND BINARY-MIXTURES THROUGH CELLULOSE-ACETATE MEMBRANES

Steady‐state permeation rates for pure CO2 and CH4 and their binary mixtures through homogeneous dense cellulose triacetate membranes have been measured at three temperatures between 20 and 40°C and pressures up to 2.8 MPa. The pressure dependence of the mean permeability coefficient for CO2 can be described by the total immobilization model in conjunction with a modified free‐volume model. No appreciable pressure dependence of the permeability coefficient for CH4 is observed, while the permeability coefficients for CH4 in binary mixture of CO2 and CH4 depend on applied gas pressure. The pressure dependences of the mean permeability coefficients for the components in the binary mixture are discussed in terms of the above mobility model. Membrane plasticization induced by CO2 affects permeation by both gases. Copyright © 1990 John Wiley & Sons, Inc.