High-temperature oxygen sorption in a fixed bed packed with perovskite-type ceramic sorbents

Oxygen sorption and desorption on two perovskite-type ceramics, La _0.1Sr_0.9Co_0.5Fe_0.5O _3-δ and La_0.1Sr_0.9Co_0.9Fe _0.1O_3-δ, were studied in a fixed-bed system. The perovskite-type ceramic packed fixed bed gives very sharp oxygen sorption breakthrough curves with long breakthrough time in the range of 400-900 °C as a result of a favorable oxygen sorption isotherm, high oxygen sorption capacity, and fast oxygen sorption rate for the sorbents. The perovskite-type ceramic sorbents can be reversibly regenerated and exhibit good structural and chemical stability against sorption and regeneration cycles. These results suggest that the perovskite-type ceramic sorbents can be used in fixed-bed processes for effective removal of oxygen from gas streams using a reducing gas sorbent regeneration. The perovskite-type ceramic sorbents can also adsorb a considerable amount of oxygen in 200-300 °C but at a much slower rate. The desorption breakthrough curves are characterized by long tails due to slower desorption rate constants (compared to sorption) and highly favorable oxygen sorption isotherms for these two materials. Process conditions or sorbent material composition should be further optimized or improved in order to develop a fixed-bed process packed with this group of sorbents for air separation.