Oxygen Permeation Improvement under CO 2 ‐Rich Environments through Catalytic Activation of Hierarchically Structured Perovskite Membranes

Catalytic activation of a highly porous La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3− δ (LSCF) freeze‐cast asymmetric membrane has been realized by screen‐printing a 30 μm thick LSCF porous layer over the dense top layer of the asymmetric membrane. Membrane activation leads to a noticeable improvement of the oxygen permeation flux (JO 2 ) in the low‐temperature region (<700 °C), at which catalytic gas exchange is the most limiting process. An enhancement of 54 % in JO 2 is obtained (JO 2 =0.17 mL min −1  cm −2 ) in air at 600 °C thanks to the addition of the LSCF catalytic porous layer, whereas the maximum oxygen permeation is reached when pure oxygen is fed to the membrane at 1000 °C with a high value of 16.3 mL min −1  cm −2 . The most appealing effect of the catalytic layer is its protective feature under oxycombustion conditions, that is, under a CO 2 ‐rich atmosphere at high temperature. Indeed, the oxygen permeation drop in the presence of CO 2 is significantly lower in the presence of a catalytic porous layer. Interestingly, the full recovery of JO 2 flux after CO 2 removal in the sweep flux evidences the absence of a carbonation process. Finally, the stability of the functionalized membrane was evaluated at 850 °C and under a 50 % CO 2 ‐containing atmosphere; this revealed a linear degradation rate for oxygen permeation of 4.27×10 −2  mL min −1  cm −2 per day.