Perovskite membranes materials

In the early 1990s, Balachandran et al. (51,64,65) of the Argonne National Laboratory, in collaboration with Amoco (now part of BP), investigated the partial oxidation of methane using membrane materials consisting of Sr-Fe-Co-O mixed oxides with the perovskite structure, which have high oxygen permeabilities. In their experiments (51,66), the membrane tubes, which were... 

Industry is continuously in search for suitable membrane materials which may produce high purity oxygen at low cost and preferably at low temperamre. This type of material is yet to be developed. Presently the zirconia and perovskite membranes... 

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. 

Some of the many different types of catalysts which have good catalytic properties for the OCM reaction qualify as membrane materials. Membrane reactors for OCM were designed and tested by Nozaki et al. (1992). Three kinds of reactors were developed the first one consisted of a porous membrane covered with a thin film of catalyst (type I) the second one, a dense ionic-conducting membrane (non porous) with catalytic layer (type II) and the third one was a membrane made of perovskite-type mixed oxides which was active for OCM (type III). Figure 11 presents the diagram for the membrane reactor system and table 13 shows the different materials used for supports and coated catalysts. 

Solid oxide electrolytes with both ionic and electronic conductivities are very attractive as membrane materials as no external circuit is needed [see Figure 4(b)]. The work of Teraoka et alJ showed the potential of perovskite materials with aliovalent substitutions. A typical perovskite has the formula ABO3 (e.g. 

Apart from the hydrogen-removal studies, reactions in which O2 has to be removed, e.g. NO and CO2 decomposition, are of environmental interest. The membrane materials used for this purpose are mixed oxides such as zirconias [90, 91] and perovskites [92]. 

MIEC Perovskites as Oxygen Separation Membrane Materials for the Oxy-fuel Combustion Power Production... 

A material for which the chemical stability in the presence of CO2 and SO2 has been extensively studied is BSCF, as it is one of the membrane materials with the highest flux. The presence of CO2 causes a reversible decline in oxygen flux. Even at concentrations of 500 ppm CO2 (ambient air), a slight decrease in the oxygen permeation rate is observed [34]. This decrease is caused by the formation of carbonates of alkaline earth metals on the exposed surface of the membrane. The carbonate formation of perovskite materials AB03 g in the presence of CO2 can be expressed as follows [72] ... 

Tong, J., Yang, W., Zhu, B. and Cai, R. (2002) Investigation of ideal zirconium-doped perovskite-type ceramic membrane materials for oxygen separation. Journal of Membrane Science, 203, 175. 

Lin Y S and Zheng Y (1996), Catalytic properties of oxygen semipermeable perovskite-type ceramic membrane materials for oxidative coupling of methane ,/ Catal, 164,220-231. 

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