Oxygen permeation, dense ceramic membranes

Extensively studied is oxygen permeation through dense ceramic membranes (e.g. perovskhes). Temperatures > 600 °C are applied. Here, oxygen splits at the surface and is transited as 0 . Porous membranes include porous polymer films (cellulosics, polyamides) as well as amorphous inorganic materials (alumina, silica). 

R.H.E. Van Doom, H. Kruidhof, H.J.M. Bouwmeester and A.J. Burggraaf, Oxygen permeation through dense ceramic membranes of Sr-doped LaCoOs-s membranes. To be submitted. 

Shao, Z., Xiong, G., Tong, J. et al. (2001) Ba effect in doped Sr(Coo.8Feo.2)03 g on the phase structure and oxygen permeation properties of the dense ceramic membranes. Separation and Purification Technology, 25,419-429. 

Figure 5.1 shows schematically the oxygen permeation through dense ceramic membranes. For the electrolyte membrane, an external circuit is... 

Figure 5.1 Oxygen permeation in dense ceramic membranes (a) electrochemical oxygen pump (b) oxygen permeation together with production of electricity ...

Fermeation rate. From an economic point of view, the oxygen fluxes in the dense ceramic membranes are required to be higher than 5mL(STP) cm min" (or 1.9 x 10 molcm s ) so as to achieve commercial benefits [21]. However, most currently developed membranes exhibit much lower permeation rate than this. 

Dense ceramic membranes allow oxygen or hydrogen permeation in a dissociated or ionized form other than the conventional molecular diffusion, and thus exhibit extremely high selectivity (up to 100%). They can be incorporated into membrane reactors for a variety of oxidation and dehydrogenation reactions where the membrane functions as either a product extractor or a reactant distributor. Three configurations, that is, disc/flat-sheet, tubular and hollow fibre membranes have been applied in membrane reactors. They exhibit respective advantages/disadvantages in terms of the ease and cost of fabrication, the effective membrane area/volume ratio, and... 

FIGURE 10.3 (a) Hydrogen and (b) oxygen permeation through dense oxide ceramic membranes. 

It has been reported [22] that micro/nano surface reactive layers introduced on the surface of oxygen ion transport membranes enhanced the oxygen permeability of dense oxygen-permeable perovskite-type ceramic membranes, Lao.7Sro.3Gao.6Feo.403 6. The results also showed that the oxygen permeation flux is influenced by the surface area of the surface-reactive layer. 

Air separation membranes are typically dense ceramic (typically perovskite) membranes, which selectively permeate oxygen in ionic form. Over the past two decades. Air Products (ITMs) and Praxair (oxygen transport membranes [OTMs]) have worked towards the commercial scale-up of these membranes for applications in power generation, gasification, and gas to liquid conversion [94]. Air Products has focused on a planar configuration, whereas Praxair on tubular membranes. 

Oxygen permeation measurements and sealing dense MIEC ceramic membranes... 

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