Oxygen permeability of Ce0.8Sm0.2O2-aEuroparts per thousandδ-LnBaCo2O5+δ (Ln=La, Nd, Sm, and Y) dual-phase ceramic membranes

Ce0.8Sm0.2O2 -aEuro parts per thousand delta-LnBaCo(2)O(5 + delta) (SDC-LnBCO, Ln=La, Nd, Sm, and Y) composites were prepared and characterized as dense ceramic membranes for oxygen separation. Ce0.8Sm0.2O2 -aEuro parts per thousand delta (SDC) shows a good chemical compatibility with LaBaCo2O5 + delta (LBCO), NdBaCo2O5 + delta (NBCO), and SmBaCo2O5 + delta (SBCO), while a little of impurity is detected in the sample with YBaCo2O5 + delta (YBCO). The SDC-SBCO and SDC-YBCO samples exhibit larger grain size than SDC-LBCO and SDC-NBCO. The incorporation of SDC increases the structural stability and decreases the thermal expansion coefficient of LnBCO at high temperature. The oxygen permeation flux of SDC-LnBCO dual-phase membrane decreases with decreasing Ln(3+) radius, which is 2.57 x 10(-7), 1.58 x 10(-7), 8.05 x 10(-8), and 7.57 x 10(-8) mol cm(-2) s(-1) at 925 A degrees C for SDC-LBCO, SDC-NBCO, SDC-SBCO, and SDC-YBCO membranes, respectively. Increasing the flow rate of feeding and sweeping gas can create oxygen partial pressure gradient, and thus, increase the oxygen permeability. These results indicate that SDC-LBCO and SDC-NBCO composites are promising candidates for oxygen permeation membrane.