La(1−x)SrxFe(1−y)GayO3−δ perovskite membrane: Oxygen semi-permeation, thermal expansion coefficient and chemical stability under reducing conditions

The La(1−x)SrxFe(1−y)GayO3−δ perovskites are one of the most promising materials for catalytic membrane reactor because of their excellent oxygen semi-permeation, low thermal expansion coefficient and good chemical stability at high temperature (700–1000 °C) under a wide range of oxygen partial pressure (from 0.21 to 10−19 atm). In this paper, the thermal expansion coefficient (TEC) and the oxygen semi-permeation of La(1−x)SrxFe(1−y)GayO3−δ perovskite in relation with Sr and Ga substitutions have been measured and discussed. The chemical stability of La(1−x)SrxFe(1−y)GayO3−δ perovskite formulations under diluted methane atmosphere is tested and discussed.This study leads to identify the Sr and Ga substitution ratios presenting the best compromise between high oxygen semi-permeation, low thermal expansion coefficient and good chemical stability in working conditions. In this way, one of the best compromises between good oxygen permeation fluxes, dimensional and chemical stabilities are La0.6Sr0.4Fe0.6Ga0.4O3−δ and La0.6Sr0.4Fe0.7Ga0.3O3−δ.

Research highlights
► The dimensional stability is mostly affected by Sr substitution.
► The oxygen semi-permeation increases significantly with Sr content from x = 0.1 to 0.4.
► The Ga content increases the chemical stability of the perovskite phase under methane.
► The best compromise materials are LSFG6464 and LSFG6473 perovskite phases.