Transport in mixed ionic electronic conductor solid oxide membranes with porous electrodes: Large pressure gradient

✍ Scribed by Minyao Zhou; Huiming Deng; Benjamin Abeles

• Publisher: Elsevier Science
• Year: 1996
• Tongue: English
• Weight: 454 KB
• Volume: 93
• Category: Article
• ISSN: 0167-2738
• DOI: 10.1016/s0167-2738(96)00483-3

✦ Synopsis

We extend the model of a mixed ionic electronic conductor (MIEC) oxygen perm-selective solid oxide membrane with porous electrodes, previously treated in the limit of small pressure gradient, to the case of arbitrary pressure gradient. The model is based on the assumption that the oxygen vacancy concentration varies only weakly with gas pressure and that the surface exchange reaction rate varies as $ where p is the oxygen gas pressure. While the model applies specifically to SrCo,.,Fe, A -6 it is expected to be applicable also to other mixed ionic electronic conductor materials with high acceptor dopant concentrations. Numerical solution of the diffusion-reaction equations, in the case of a large pressure gradient, show that the enhancement in oxygen permeability due to the porous electrodes scales with the simple analytical expression for the flux enhancement obtained in the limit of a small pressure gradient. Enhancement of over two orders of magnitude in oxygen flux are predicted for membranes with large surface area porous electrodes.