(226a) New Developments on Membranes for CO2 Separation and Capture

This presentation covers new developments on carbon dioxide-selective membranes for: (1) hydrogen purification for fuel cells and (2) carbon capture from flue gas.  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 up to 180^oC.  We have elucidated the effect of amine steric hindrance in the solid membrane, showing significant enhancement for CO₂ transport.  Hydrogen sulfide permeates through the membrane much faster than CO₂, allowing H₂S removal in the treated synthesis gas before water-gas-shift (WGS) reaction.  Our initial experiments have shown a nearly complete removal of H₂S from 50 ppm in synthesis gas to about 10 ppb in the hydrogen product.  Using the membrane, we have obtained <10 ppm carbon monoxide in the hydrogen product in WGS membrane reactor experiments via CO₂ removal.  The data have been in good agreement with our modeling predictions.  The membrane is being scaled up for commercialization.  For CO₂ capture from flue gas in coal-fired power plants for sequestration, we will discuss a new concept of inorganic/polymer composite membranes along with initial membrane transport results.  We will also discuss the process modeling along with cost sensitivity for the CO₂ capture to achieve the US DOE target of £35% increase on the cost of electricity (COE) and £$40/tonne CO₂ captured for 2025.  Cost calculations show that this target can be met with an air-sweep process to achieve 90% CO₂ recovery and 95% purity of the CO₂ product.  This process operates at slightly above atmospheric feed pressure (about 1.1 atm) with feed compression for cost optimization and requires a low membrane module price of $2.5/ft² ($27/m²), a CO₂/N₂ selectivity of about 150 combined with a high CO₂ permeance of 3000 GPU.