Novel membrane materials for CO₂ removal from mixtures with H₂

Crosslinked copolymers (PEGDA-co-PEGMEA) prepared by photopolymerizing mixtures of poly(ethylene glycol) diacrylate (PEGDA) and poly(ethylene glycol) methyl ether acrylate (PEGMEA) were presented. These materials exhibited very high CO₂ permeability and high CO₂/H₂ pure gas selectivity. Mixed gas CO₂/H₂ separation performance in these copolymers was evaluated. CO₂ permeability increased with increasing CO₂ partial pressure because of plasticization of the polymer chains by CO₂. The increase became more significant at lower temperatures because CO₂ sorption increased with decreasing temperature. The pure gas and mixture CO₂ permeability fell on the same trend line, suggesting that the presence of H₂ had a negligible effect on CO₂ permeability. H₂ permeability increased with increasing CO₂ partial pressure. Lower temperature improved both CO₂ permeability and CO₂/H₂ mixed gas selectivity. Decreasing temperature improved CO₂/H₂ selectivity in the nanocomposite containing 44 wt % MgO and the balance PEGDA. Mixed gas CO₂ permeability in the nanocomposite was compared with pure gas CO₂ permeability in the pure polymer at -20°C. This comparison was reasonable because CO₂ permeability values for various compositions fall on the same trend line. The addition of MgO nanoparticles improved CO₂ permeability. This is an abstract of a paper presented in the ACS Fuel Chemistry Meeting Fall 2005 (Washington, DC Fall 2005).