Experimental and modeling study on tubular dense membranes for oxygen permeation

Tubular La_0.6Sr_0.4Co_0.2Fe_0.8O_3-δ perovskite-type membranes were prepared by isostatic pressing. A mathematical model was developed to simulate the performance of the tubular perovskite-type dense membranes for oxygen permeation. The experimental oxygen permeation fluxes of tubular La_0.6Sr_0.4Co_0.2Fe_0.8O_3-δ perovskite-type membrane increased with decreasing downstream oxygen partial pressure and increasing helium flow rate, which coincided with the results of the oxygen permeation modeling study. Parametric study indicated that air should be supplied sufficiently during the oxygen permeation operation. Modeling oxygen permeation fluxes as a function of the tubular membrane length and tubular membrane thickness are discussed in detail. The oxygen flux slightly decreased after long-term operation over 110 h. EDS and XRD analysis indicated that SrSO₄, CoSO₄, SrO, Co₂O₃, and La₂O₃ were formed on the surfaces of the tubular membrane due to the interaction with trace SO₂ in the air and the helium, and segregation of surface elements. The oxygen permeation of tubular La_0.6Sr_0.4Co_0.2Fe_0.8O_3-δ membrane was stable after SO₂ in the air and the helium has been removed.