Download or read book Oxygen-permeable Ceramic Membranes for Gas Separation written by and published by . This book was released on 1998 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mixed-conducting oxides have a wide range of applications, including fuel cells, gas separation systems, sensors, and electrocatalytic equipment. Dense ceramic membranes made of mixed-conducting oxides are particularly attractive for gas separation and methane conversion processes. Membranes made of Sr-Fe-Co oxide, 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, i.e., CO + H2). The authors have fabricated tubular Sr2Fe2CoO{sub 6+{delta}} membranes and tested them (some for more than 1,000 h) in a methane conversion reactor that was operating at 850--950 C. An oxygen permeation flux of (almost equal to) 10 scc/cm2 · min was obtained at 900 C in a tubular membrane with a wall thickness of 0.75 mm. Using a gas-tight electrochemical cell, the authors have also measured the steady-state oxygen permeability of flat Sr2Fe2CoO{sub 6+{delta}} membranes as a function of temperature and oxygen partial pressure(pO2). Steady-state oxygen permeability increases with increasing temperature and with the difference in pO2 on the two sides of the membrane. At 900 C, an oxygen permeability of (almost equal to) 2.5 scc/cm2 · min was obtained in a 2.9-mm-thick membrane. This value agrees with that obtained in methane conversion reactor experiments. Current-voltage (I-V) characteristics determined in the gas-tight cell indicate that bulk effect, rather than surface exchange effect, is the main limiting factor for oxygen permeation of (almost equal to) 1-mm-thick Sr2Fe2CoO{sub 6+{delta}} membranes at elevated temperatures (> 650 C).