Fig. 8: Effects of feed pressures and physical ageing on membranes.

a Pure CO2 permeability versus feed pressure. b CO2/CH4 ideal selectivity versus feed pressure. c CO2 permeability versus feed pressure for separating equimolar CO2/CH4 gas mixtures. d CO2/CH4 selectivity versus feed pressure for separating equimolar CO2/CH4 gas mixtures. e Pure gas permeability versus aging time of XPIM-BM/TB- 250 °C-10 h. f Gas selectivity versus aging time of XPIM-BM/TB- 250 °C-10 h.