Oxygen permeation improvement under CO2-rich environments through catalytic activation of hierarchically-structured perovskite membranes

Abstract

[EN] Catalytic activation of a highly porous La0.6Sr0.4Co0.2Fe0.8O3- (LSCF) freeze-cast asymmetric membrane has been realized by screen-printing a 30m 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 degrees C), at which catalytic gas exchange is the most limiting process. An enhancement of 54% in JO(2) is obtained (JO(2)=0.17mLmin(-1)cm(-2)) in air at 600 degrees 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 degrees C with a high value of 16.3mLmin(-1)cm(-2). The most appealing effect of the catalytic layer is its protective feature under oxycombustion conditions, that is, under a CO2-rich atmosphere at high temperature. Indeed, the oxygen permeation drop in the presence of CO2 is significantly lower in the presence of a catalytic porous layer. Interestingly, the full recovery of JO(2) flux after CO2 removal in the sweep flux evidences the absence of a carbonation process. Finally, the stability of the functionalized membrane was evaluated at 850 degrees C and under a 50% CO2-containing atmosphere; this revealed a linear degradation rate for oxygen permeation of 4.27x10(-2)mLmin(-1)cm(-2) per day.