(54c) Facilitated Transport Membranes for CO2 Separation and Capture

This presentation is in honor of Dr. John Quinn for his pioneering work on facilitated transport membranes including those for CO₂ separation, and it covers CO₂ facilitated transport membranes for: (1) hydrogen purification for fuel cells and (2) CO₂ capture from flue gas in power plants and from <1% CO₂ concentration sources. We have synthesized CO₂-selective membranes by incorporating amino groups into polymer networks. The membranes have shown high CO₂ permeability and selectivity vs. hydrogen, carbon monoxide and nitrogen. We have elucidated the effect of amine steric hindrance in the solid membrane, showing significant enhancement for CO₂ transport. The membranes were scaled up to 14 inches in width by using a continuous roll-to-roll machine equipped with a thin-film-coating assembly. For the CO₂ separation from a synthesis gas stream containing CO₂ and H₂S, i.e., hydrogen purification for fuel cells or pre-combustion CO₂ capture in IGCC (integrated gasification combined cycle) technology, thicker amine-containing membranes with around 15 ± 1 microns of selective layer thicknesses were fabricated. For the post-combustion CO₂ capture from flue gas, thinner amine-containing membranes with < 200 ± 20 nm of selective layer thicknesses were scaled up. From gas transport measurements, the flat-sheet samples of the scale-up membranes for both applications exhibited similar performances compared to the membranes synthesized in lab scale. CO₂ permeance of approximately 200 GPU and CO₂/H₂ selectivity > 200 were for the thicker membranes for the purification of hydrogen and synthesis gas along with CO₂ capture (e.g., pre-combustion capture), and CO₂ permeance of about 800 GPU and CO₂/N₂ selectivity > 140 were for the thinner membranes for CO₂ capture from flue gas. The scale-up membrane has been fabricated into spiral-wound membrane modules. Techno-economic analysis has shown that the post-combustion capture process using the thin membrane has approached DOEâ??s capture cost target for 2025.