(100a) Dual Phase Membranes for High Temperature CO2 Separation and Membrane Reactors

CO₂ transport membranes have many applications including CO₂ capture from industrial combustion processes and membrane reactors.  'Dual phase' membranes are made from a porous, oxygen ion-conducting support that has been infiltrated with molten carbonates. As long as a partial pressure differential exists across the membrane, CO₂ will selectively permeate through the membrane as a dissolved CO₃^2- ion, while O^- ions are transported in the opposite direction by the support material.  Previous research has been done on dual phase membranes in the form of disks, but this project focuses on tubular membranes which are more readily applicable to industrial situations. Using tubular membranes made from Yittria-Stabilized Zirconia and a eutectic mixture of Li, Na, and K carbonates, we were able to fabricate a very thin, dual phase membrane that showed a high flux and permeance of CO₂ over a temperature range of 550 to 750°C, comparable to the highest fluxes reported in the literature. The permeability was lower, which may be due to the rate-limiting surface reaction. Current work is being done to improve the membrane performance, including improving the homogeneity of the carbonate coating on the membrane, using a support material with a higher oxygen ion conductivity, and increasing the rate of the surface reaction with a catalyst.