Performance of the layered cobaltites in membrane mediated oxygen separation from air and methane partial oxidation

[Display omitted] •Dense ceramic membranes are utilized for oxygen separation from the air.•The bulk oxygen diffusion is shown to be controlling the oxygen separation.•Partial oxidation of methane (POM) is firstly realized on double cobaltite ceramics.•Membrane degradation features after the POM experiments are studied. The performance of dense ceramics LnBaCo2–xAlxO6–δ, where Ln = Pr, Sm, and Gd, and x = 0.025 and 0.1, was studied at oxygen separation from the air and membrane-mediated catalytic partial oxidation of methane. The best oxygen permeability was observed for PrBaCo2–xAlxO6–δ at x =0.025. The increase of aluminum content and the decrease of the rare-earth size resulted in a fast decline of the oxygen separation efficiency. The oxygen flux is found to improve more than ten times at partial oxidation of methane (POM) with the selectivity for CO near 90%. The energy-dispersive X-ray spectroscopy (EDX) analysis gives evidence to phase separation effects in the membrane material after 800 h of the POM run.