Tuning the two phases ratio by nonmetal ion doping in dual‐phase mixed‐conductive ceramic membranes

Abstract

AbstractThe mixed protonic–electronic conductor of BaCe0.5Fe0.5O3−δ can be automatically decomposed into a dual‐phase material of the cerium‐rich oxide BaCe0.85Fe0.15O3−δ (BCFe8515) and the iron‐rich oxide BaCe0.15Fe0.85O3−δ (BCFe1585). The BaCe0.5Fe0.5O3−δ membrane possessed an extremely high hydrogen (H2) permeation flux, but poor stability. Therefore, in this work, for the first time, the nonmetal P is doped to increase the proportion of the BaCe0.85Fe0.15O3−δ (P‐doped Ce‐rich) phase to improve the stability of the dual‐phase membrane. The developed dual‐phasic ceramic membranes of BaCe0.5Fe0.5−xPxO3−δ (BCFePx) (x = 0, 0.025, 0.05, 0.1) exhibit enhanced stability compared to their parent oxides. Under the condition of 950°C, feed gas with dry 50% H2‐50% He and sweep gas with wet Ar, the H2 permeation flux of BCFeP0.05 membrane stabilized at 1.56 mL min−1 cm−2 after the long‐term stability test for 480 h. The enhanced stability resulted from the increase of the P‐doped Ce‐rich phase content and the inhibition of Fe2O3 phase precipitation from the BaCe0.15Fe0.85O3−δ (P‐doped Fe‐rich) phase in the reducing atmosphere by doping non‐metal P element.