A MEMBRANE AND USE THEREOF

The present invention relates to a dense single-phase membrane having both high ionic and electronic conductivity and capable of separating oxygen from an oxygen containing gaseous mixture, where the membrane comprises a mixed metal oxide material with interstitial oxygen excess represented by the formula A y A'y 'A"y"B x B'x'B"x"B'''x'''O4+.delta., where A, A' and A" are chosen from group 1, 2 and 3 and the lanthanides; and B, B', B" and B"' are chosen from the transition metals according to the periodic table of the elements adopted by IUPAC wherein 0.ltoreq.y.ltoreq.2, 0.ltoreq.y'.ltoreq.2, 0.ltoreq.y".ltoreq.2, 0.ltoreq.x.ltoreq.1, 0.ltoreq.x'.ltoreq.1, 0.ltoreq.x".ltoreq.1, 0.ltoreq.x'''.ltoreq.1, and x and y each represents a number such that y+y'+y"=2, x+x'+x"+x'''=1, and .delta. is a number where 0.ltoreq..delta. &l t; 1 quantifying the oxygen excess. Furthermore, the invention relates to a use o f the membrane for production of pure oxygen, oxygen enrichment of a sweep gas for fossil energy conversion, for synthesis gas production and for production ofoxygen for application in any catalytic or non-catalyti c processes wherein oxygen is one of the reactants.