Two-step fabrication of BaCo0.7Fe0.2Nb0.1O3−δ asymmetric oxygen permeable membrane by dip coating

Asymmetric membranes for high temperature oxygen separation with identical materials for dense layers and porous supports have been extensively reported in recent years. This paper presents a versatile method for manufacturing such asymmetric membrane, including pre-sintering, dip coating and co-firing. The porous support was elaborated through trial of different pore-forming agents and the amount. The thickness of top layer was controlled by adjusting the concentration of slurries. Several test approaches were employed to detect the detailed parameters of porous supports, such as SEM, mercury intrusion porosimetry and nitrogen permeation measurement. High performance support with excellent permeability and sufficient mechanical strength (43.84 MPa) was fabricated successfully. A stable pore structure with open porosity of 33.26% was achieved. The prepared asymmetric membrane with thickness of 20 μm for dense layer was subjected to oxygen permeation test and the result reached as high as 4.51 ml (STP) cm-2 min-1. The results suggest that the oxygen permeability was limited by both bulk diffusion and surface exchange kinetics.