Synthesis, Characterization, and Impregnation of Some Ionic Liquids on Polymer Membrane for Separation of Carbon Dioxide from Its Mixture with Methane

Some 1-alkyl-3-methylimidazolium-based ionic liquids were synthesized, characterized, and immobilized on membranes to form supported ionic liquid membranes. The supported ionic liquid membranes were characterized by SEM. The initial transmembrane pressures were investigated for each type of impregnated membrane. The CO2/CH4 single gas and mixed gas permeability (CO2 and CH4) have been investigated. The results showed that the CO2/CH4 ideal selectivities and mixed gas selectivities reached 15.45-23.9 and 13.91-22.82, respectively (equivalent to separation yields of 93.3-95.98 %). The 1-alkyl-3-methylimidazolium acetate impregnated membrane leads to a slightly lower CO2/CH4 selectivity, however, this ionic liquid is stable, free of halogen and has a low price. The impregnated membranes prepared from polyvinylidene fluoride are more-stable than those from polyethersulfone support, and have a higher affinity for CO2 compared to other gas. The obtained high CO2/CH4 selectivities indicate that immobilized membranes can be used for CO2 separation processes.