Dual-phase Ga-containing Ce0.9Pr0.1O2-δ-Pr0.6Sr0.4Fe1-xGaxO3-δ oxygen transport membranes with high CO2 resistance

Here we report a new series of Ga-doped dual-phase mixed ionic and electronic conducting (MIEC) oxygen transport membranes (OTMs) with the compositions of Ce0.9Pr0.1O2-delta-Pr0.6Sr0.4Fe1-xGaxO3-delta (CPO-PSF1-xGxO, x=0.025, 0.05, 0.075, 0.1, 0.15, 0.2). The structure, surface topography, oxygen permeability, and stability are studied. The optimal CPO-PSF0.95G0.05O OTM performs the highest oxygen permeation fluxes of 0.75 mL min-1 cm-2 and 0.41 mL min-1 cm-2 with He or CO2 as the sweep gas, respectively. All Ga-doped OTMs maintain excellent stability in the two different atmospheres over 120 h. Moreover, a kind of MIEC-MIEC OTM with a composition of Ce0.85Pr0.1Cu0.05O2-delta-Pr0.6Sr0.4Fe0.95Ga0.05O3-delta is obtained by Cu doping. It performs higher ox- ygen permeation fluxes of 1.19 mL min-1 cm-2 and 0.46 mL min-1 cm-2 under the same conditions and operates stably for 250 h under the He and CO2 cycle switching as the sweep gas. Through stability tests in a reducing atmosphere, our findings are expected to improve the studies and possible applications of OTMs in solid oxide fuel cells.