Preparation and Oxygen Permeation of La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) Perovskite-Type Membranes: Experimental Study and Mathematical Modeling

La0.6Sr0.4Co0.2Fe0.8O3-delta nanopowder, synthesized via an autocombustion technique, was pressed into disk-shaped membranes. Results of permeation experiments revealed that oxygen permeation flux increases as temperature, feed side oxygen partial pressure, and feed and sweep gas flow rates increase, while it decreases with membrane thickness and permeate side oxygen partial pressure. A Nernst-Planck based mathematical model, including surface exchange kinetics and bulk diffusion, was developed to predict oxygen permeation flux. Considering nonelementary surface reactions and introducing system hydrodynamics into the model resulted in an excellent agreement (RMSD = 0.0344, AAD = 0.0274 and R-2 = 0.9960) between predicted and measured fluxes. Feed side surface exchange reactions, bulk diffusion, and permeate side surface exchange reaction resistances are in the range of R-ex' = 7 X 10(3) to 9 X 10(6), R-diff = 1 X 10(5) to 2 X 10(7), and R-ex '' = 1 X 10(4) to 2 X 10(7) (s/m), respectively. The permeation rate-limiting step was determined using the membrane dimensionless characteristic thickness.