Tubular dense perovskite type membranes. Preparation, sealing, and oxygen permeation properties

Tubular dense perovskite type membranes were prepared by isostatic pressing and plastic extrusion. The resulting tubular La_0.6Sr_0.4Co_0.2Fe_0.8O _3-δ perovskite type membrane prepared by plastic extrusion (designated as PE-LSCF) has a lower density and oxygen permeation flux compared with that prepared by isostatic pressing (designated as IP-LSCF). A ceramic binder developed by our research center provided reliable sealing for the tubular dense membrane at high temperature. The oxygen permeation flux increases with increasing temperature, and the value is about 0.13 cm³/cm² min (STP) at 1123 K. The activation energy for oxygen permeation is 168 kJ/mol at the temperature range of 1073-1173 K. X-ray diffraction analysis for the membranes over 110 h of operation indicated that SrSO₄, CoSO₄, SrO, Co₂O₃, and La₂O₃ were formed on the surfaces of the tubular membrane, especially for the tubular PE-LSCF membrane, because of interaction with trace SO₂ in the air and the helium and segregation of surface elements.