Download or read book Mixed-conducting Oxides for Gas Separation Applications written by and published by . This book was released on 1999 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mixed-conducting oxides are attracting increased attention because of their potential uses in high-temperature electrochemical applications such as solid-oxide fuel cells, batteries, sensors, and gas-permeable membranes. We are developing mixed-conducting, dense ceramic membranes to selectively transport oxygen and hydrogen. Ceramic membranes made of Sr-Fe-Co oxide (SFC), which exhibits high combined electronic and oxygen ionic conductivities, can be used to selectively transport oxygen during the partial oxidation of methane to synthesis gas (syngas, a mixture of CO and H2). Steady-state oxygen permeability of SrFeCo{sub 0.5}O(subscript x) has been measured as a function of oxygen-partial-pressure gradient and temperature. At 900 C, oxygen permeability was (almost equal to)2.5 scc·cm−2-min−1 for a 2.9-mm-thick membrane, and this value increases as membrane thickness decreases. We have fabricated tubular SrFeCo{sub 0.5}O(subscript x) membranes and operated them at 900 C for>1000 h during conversion of methane into syngas. Yttria-doped BaCeO3 (BCY) is a good protonic conductor; however, its lack of electronic conductivity can potentially limit its hydrogen permeability. To enhance the electronic conductivity and thus improve hydrogen permeation, a membrane composite material was developed. Nongalvanic permeation of hydrogen through the composite membrane was characterized as a function of thickness.