Dual Phase Sorbents for High Temperature Air Separation

Ceramic sorbents based on combined perovskite/spinel structure have been investigated for their potential use in oxygen- enriched CO₂ stream production. Oxides of strontium and barium doped with cobalt and iron were chosen for this study. X-ray diffraction studies revealed a dual-phase structure containing perovskite and spinel systems. Microstructure observed by SEM showed the spinel phase as intergrowth structure in the dominantly perovskite phase. Thermogravimetric studies show a higher desorption rate and sorption capacity compared to the similar perovskite sorbents which with a lower CO₂ uptake can produce an optimum sorbent material for air separation in oxyfuel power generation. Sintering temperature also showed an effect on oxygen sorptive/desorptive properties. Improved properties can be explained based on the defect chemistry of the new structure.