Perovskite oxygen separation

Middelkoop, V., Chen, H., Michielsen, B., et al. (2014) Development and characterisation of dense lanthanum-based perovskite oxygen-separation capillary membranes for high-temperature applications. Journal of Membrane Science, 468, 250-258. 

Double Substitution In such processes, two substitutions take place simultaneously. For example, in perovskite oxides, La may be replaced by Sr at the same time as Co is replaced by Fe to give solid solutions Lai Sr Coi yFey03 5. These materials exhibit mixed ionic and electronic conduction at high temperatures and have been used in a number of applications, including solid oxide fuel cells and oxygen separation. 

Perovskite-structured oxides with high electronic and oxygen ion conductivities could be used as a membrane alternative to solid electrolytes for oxygen separation. In such materials, both oxygen ions and electronic defects are transported in an internal circuit in the membrane material. 

Our research is focused on the control of both the microstructure and the architecture of perovskite-type mixed-conducting reactors for high temperature applications, especially for oxygen separation from air and syngas production. 

We will first consider the development activity which has occurred in the application of oxygen separation and collection. A wide range of materials has been examined in this area including perovskites, brownmillerites, fluorites and composites of various structures. There has also been progress in membrane architec-... 

There are two main approaches for fabricating oxygen separation membranes. The first is to use a mixture of two distinct materials - an oxygen-ion conductor such as doped zirconia, and an electron conductor such as a noble metal or a doped perovskite (see Fig. 6.1). The second approach is to use a material which is capable of conducting both oxygen ions and electrons (see Fig. 6.2). 

There are several advantages to using a dual-phase membrane over a singlephase mixed electronic ionic conductor. These include the fact that the ionic conductors such as YSZ are much more chemically and thermally stable compared to most perovskites. Thus, dual-phase membranes are Ukely to be able to tolerate the harsh conditions of an oxygen separation device. They also show good tolerance to both CO2 and steam. The difficulty comes in the selection of an electronically conducting material. The cost of noble metals makes their incorporation into commercial devices unlikely. Therefore, the electron-conducting phase is Umited to a... 

M. van der Haar, Mixed-Conducting Perovskite Membranes for Oxygen Separation, Ph.D. Dissertation, Universiteit Twente, The Netherlands, 2001. 

J. Caspary, H. Wang, ). Caro, Hollow fibre perovskite membranes for oxygen separation. Journal of Membrane Science 2005, 258 (1/2), 1-4. 

Perovskite Membranes for High Temperature Oxygen Separation... 

Whereas most perovskite material have operation temperatures above 800 °C, our BCFZ perovskite hollow fiber membrane could be successfully used for oxygen separation from air between 400 and 500 °C (Figure 16.6). As Figure 16.6 shows, the oxygen permeation flux increases from 0.03 to 0.45 mL cm min as the temperature rises from 400 to 500 °C. However, in... 

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