Carbon Dioxide Capture Using a CO₂-Selective Facilitated Transport Membrane

A novel CO 2 -selective membrane with the facilitated transport mechanism has been synthesized to capture CO 2 from the industrial gas mixtures, including flue gas. Both mobile and fixed amine carriers were incorporated into the cross-linked poly(vinyl alcohol) (PVA) during the membrane synthesis. The membrane showed desirable CO 2 permeability (with a suitable effective thickness) and CO 2 /N 2 selectivity up to 170 °C. In the CO 2 capture experiments from a gas mixture with N 2 and H 2, a permeate CO 2 dry concentration of >98% was obtained, using steam as the sweep gas. The effects of the feed flow rate and the sweep:feed molar ratio on the membrane separation performance were investigated. A one-dimensional isothermal model was established to examine the performance of a hollow-fiber membrane module composed of the described CO 2 -selective membrane. The modeling results show that a CO 2 recovery of >95% and a permeate CO 2 dry concentration of >98% are achievable from a 1000 standard cubic feet per minute (SCFM) (or 21.06 mol/s) flue gas stream with a 2 ft (0.61 m) hollow-fiber module that contained 980 000 fibers.