Influence of microstructure and architecture on oxygen permeation of La(1−X)SrXFe(1−Y)(Ga, Ni)YO3−δ perovskite catalytic membrane reactor

The catalytic membrane reactor studied consisted of a mixed ionic and electronic conductor dense layer La1-xSrxFe1-yGayO3-delta. High temperature XRD analysis, from room temperature to 900 C under air and nitrogen atmosphere, showed a reversible monoclinic to rhombohedral phase transition around 300 C, and good chemical and dimensional stabilities of La0.8Sr0.2Fe0.7Ga0.3O3-delta material. The La0.8Sr0.2Fe0.7Ga0.3O3-delta dense layer deposited by tape casting was coated with La0.8Sr0.2Fe0.7Ga0.3O3-delta on the air side and La0.8Sr0.2Fe0.7Ni0.3O3-delta on the inert side using screen printing. The influence of the dense membrane microstructure and the surface exchange kinetics on the oxygen semi-permeation performance was evaluated. Small grain size, mainly below 1 micron in the dense membrane significantly increased the oxygen flux. A porous layer of La0.8Sr0.2Fe0.7Ni0.3O3-delta or La0.8Sr0.2Fe0.7Ga0.3O3-delta on the air or inert side of the membrane increased strongly the specific oxygen semi-permeation. The impact of the porous layer was more important than the reduction of the grain size. In this case, the surface exchange kinetics was the limiting step of oxygen permeation, and Ni-containing formulation led to the highest flux.