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

Ho, W. S. W., The Ohio State University
Chen, Y., The Ohio State University
Ramasubramanian, K., The Ohio State University
Severance, M. A., The Ohio State University
Tong, Z., The Ohio State University
Vakharia, V., The Ohio State University
Zhao, L., The Ohio State University
Zhao, Y., The Ohio State University
Dutta, P. K., The Ohio State University

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 180oC.  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.