A module for separating oxygen from an oxygen-containing gaseous mixture comprising planar solid-state membrane units, each membrane unit comprising planar dense mixed conducting oxides layers, planar channel-free porous support layers, and one or more planar intermediate support layers comprising at least one channeled porous support layer. The outer rim circumscribing the planar solid-state membrane units comprises a dense mixed conducting oxide layer and a channel-free porous support layer.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
 This invention was made with government support under Cooperative Agreement Number DE-FC26-98FT40343 between Air Products and Chemicals Inc. and the U.S. Department of energy. The U.S. Government has certain rights to this invention.