The preparation of SPEEK /phosphate salts membranes and application for CO2/CH4 separation

SPEEK/phosphate salts membranes were prepared and utilized for CO2/CH4 separation. SPEEK with abundant –SO3H groups and EO groups on polymer chains would be beneficial for CO2 transport. The doped phosphate salts (NaH2PO4, Na2HPO4 and Na3PO4) with different acid‐base properties increased the water content in the membrane, and water was expected to increase both the solubility and diffusivity of CO2 in the membrane. All membranes were characterized by FTIR, TGA, and XRD. The CO2 permeability and CO2/CH4 selectivity of SPEEK/Na3PO4 membranes were higher than that of SPEEK/NaH2PO4 and SPEEK/Na2HPO4 membranes. Compared to the pure SPEEK membrane, the CO2 permeability and CO2/CH4 selectivity of SPEEK/Na3PO4−10 membrane were increased by 144% and 65%, respectively.