Role of Aromatic Polyimide Membrane in CO2 Separations

This chapter summarizes the potential of polyimide membrane in CO₂ removal with strong emphasis on its structural flexibility. The aromatic structure in the polyimide backbone contributes strongly to the polyimide chain rigidity, which increases its glass transition temperature. The permeability-selectivity trade-off is one of the major concerns that restricts the widespread application of polyimide membrane for industrial CO₂ removal. More sophisticated modification on that particular polyimide structure is necessary to push the gas separation performances beyond the trade-off plot. Glassy polymer such as polyimide tends to swell during sorption of carbon dioxide, which in turn leads to reduction in the membrane permselectivity. Molecular Dynamics simulation serves as an alternative technique to simulate the gas transport properties of polyimide matrix such as the gas diffusivity and solubility. Economic analysis suggests that polyimide membrane is more cost effective compared to the conventional amine absorption in CO₂ separation from flue gas stream.