Dense ceramic membranes made from mixed conductors were interesting because of their potential applications for methane conversion into syngas (H2 and CO mixture). Such membranes need to present a low differential dimensional variation

between the opposite faces submitted to a large gradient of O partial pressure, in order to minimize mechanical stresses generated through the membrane thickness. Besides, high O permeability was required for high methane reforming rate. La(1−x)SrxFe(1−y)GayO3−δ materials fulfil these 2 main requirements and were retained as membranes in catalytic membrane reactors (CMR). The variations of expansion and O permeation of La(1−x)SrxFe(1−y)GayO3−δ perovskite materials with the partial substitution of La and Fe cations, temperature and O partial pressure, were studied. For low temperatures (<800C), the thermal expansion coefficient (TEC) value of La(1−x)SrxFe(1−y)GayO3−δ materials was independent of cation substitution and of O partial pressure in the range tested (10−5 to 0.21atm). For higher temperatures (>800C ), TEC, then dimensional stability of the membrane, and O permeation of La(1−x)SrxFe(1−y)GayO3−δ materials, were significantly affected by Sr content and O partial pressure. Ga had a stabilisation effect on the TEC and had no influence on O permeation flux. A good compromise between dimensional stability and O permeation of materials was found to be La0.7Sr0.3Fe0.7Ga0.3O3−δ composition.

Oxygen Permeation, Thermal and Chemical Expansion of (La,Sr)(Fe,Ga)O3−δ Perovskite Membranes. E.Juste, A.Julian, G.Etchegoyen, P.M.Geffroy, T.Chartier, N.Richet, P.Del Gallo: Journal of Membrane Science, 2008, 319[1-2], 185-91