Abstract
In order to improve the oxygen permeation rates of oxygen transport membranes (OTM), asymmetric membranes with a thin dense layer must be fabricated on a porous support. In this paper, we focus on preparing and characterizing structures with functional layers consisting of Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF) and La0.68Sr0.3Fe0.8Co0.2O3-δ (LSFC). The supports for these structures were prepared by tape casting and warm pressing, and samples were analysed in terms of nitrogen permeability and porosity. The coating of the functional layers was performed via screen printing. For BSCF, multiple layers were necessary to obtain a gas-tight structure. Oxygen permeation measurements of the asymmetric structures showed an increase in the oxygen flux in comparison to bulk membranes with a thickness of L =1 mm. However, this enhancement is subproportional to the reduced thickness, indicating rate limiting effects, i.e. surface exchange kinetics in the case of LSFC and concentration polarization in the porous support in the case of BSCF.
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