Composite membrane based on ionic conductor and mixed conductor for oxygen permeation

A composite membrane, which comprises of one fluorite oxide phase (Ce0.8Gd0.2O1.9) for oxygen ionic transport and one perovskite oxide phase (Gd0.2Sr0.8FeO3−δ) for both oxygen ionic and electronic transport, was investigated. XRD results revealed that the two oxides are compatible and showed good oxygen permeation stability at 950°C (more than 1100 h). Oxygen flux of the composite membrane was two times higher than that of the Gd0.2Sr0.8FeO3−δ mixed conducting membrane at the same conditions. At steady state, oxygen flux of a 0.5 mm membrane was 0.80 ml/(cm2 min) under oxygen partial pressure gradient of air/He and ∼5.0 ml/(cm2 min) for syngas production at 950°C, respectively. After ∼440 h operation under syngas conditions, SEM analysis revealed that the syngas side of the membrane still kept dense and the EDX showed the transfer of elements occurred in the depth of a few microns.