MIEC scale

To develop an alternative MIEC cathode not only the ex situ properties, e.g., cr, TEC, /), and k, but also the electrocatalytic activity, structural and chemical stability, and Cr-tolerance must be considered. Beyond testing in small SOFC button cells, the viability of new cathode materials must ultimately be proven in large-scale stack cells under practical current and temperature gradients. The issues involved in the development of cathode materials for large-scale stacks are significantly more complex than those in the small button cells briefly reviewed in this chapter. However, this does provide serious challenges as well as opportunities for materials scientists and engineers in the development of commercially viable ITSOFCs. 

Figure 16.1 Different types of MIEC laboratory scale membrane reactors (a) short hollow fiber with Au sealing in the hot zone, (b) short tubular membrane, and (c) disk membrane.

The phase inversion/sintering technique has to be further improved to produce in a large scale MIEC hollow fiber membranes with constant macrostructure and performances so as to reduce the membrane costs. 

As far as other MIEC membrane materials are concerned. Tan et al. developed a pilot-scale membrane system (shown in Figure 4.17) comprising 889 LSCF6428... 

While this sealing technique, as all the sealants based on ceramic/glass, is very attractive for laboratory/small-scale applications, a more robust technique has to be applied in order to exploit the MIEC membranes at larger scales. Among the various sealing techniques proposed so far, the reactive air brazing (RAB) seems to be the most appropriate for industrial applications. 

In a recent paper, the authors investigated the integration of MIEC membranes for air separation in a small-to-medium-scale unit for H2 production (in the range of 650-850 N m /h) via autothermal reforming of methane [65]. 

Figure 33.18 Plant design of the autothermal process with MIEC membranes for small-scale Ha production.

The most important consideration for a MIEC membrane is the delivery of a stable continuous transmembrane flux. This flux is central to membrane performance and therefore oxygen permeation studies in MIEC membrane characterization are fundamental. From an economic standpoint, an oxygen flux of 1 to 10 ml cm min (STP) has been cited as the requirement for future needs [25,26]. In order to provide a broad overview of this research area we will briefly outline synthesis and characterization methods applied to the MIEC perovskites before moving on to look at selected MIEC membranes currently used in laboratory-scale tests. 

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