Separation of CO₂ from Model Flue Gas by Facilitated Transport Membrane with Hydrogel

Abstract

Gel-coated membranes were prepared by coating hydrophobic microporous PTFE membranes with hydrophilic PVA-PAA gel and used as facilitated transport membrane for the removal of CO₂ from model flue gas consisting of 10% CO₂ and 90% N₂. K₂CO₃ and Na₂CO₃ were used as carriers of CO₂. Gas permeation experiments were performed at the permeate side pressure of 40mmHg. A facilitated transport membrane prepared by impregnating the gel layers with an aqueous 2 mol/kg K₂CO₃ solution showed the CO₂ permeance of 2.5 × 10^-5 cm³ (STP) / (cm² s cmHg) and this value was much higher than that observed with a conventional facilitated transport membrane prepared by impregnating a hydrophilic microporous membrane with the same carrier solution. The CO₂/N₂ selectivity was higher than 100. It was confirmed by the long-term test that the gel-coated membrane was stable with no decrease in the CO₂ permeance for continuous six-month testing period due to the hygroscopic nature of the gel layer.