Enhancing the CO 2 Separation Performance of Matrimid 5218 Membranes for CO 2 /CH 4 Binary Mixtures

The effect of CO 2 ‐philic additive polyethylene glycol (PEG) 200 in Matrimid 5218 on the separation performance of prepared membranes was evaluated in a binary gas mixture. Matrimid/PEG 200 flat‐sheet blended membranes with low PEG concentrations were prepared by the dense film‐casting method. Pure Matrimid and blended membranes were characterized by FTIR spectroscopy, scanning electron microscopy, differential scanning calorimetry, thermogravimetric analysis, and permeation measurements. The addition of 4–5 % of PEG enhanced considerably the CO 2 permeability of the Matrimid matrix. The best formulation, Matrimid/PEG 200 (96/4), showed in comparison to pure Matrimid a more than threefold increase in CO 2 permeability and an increase in separation factor of about 40 %.