Perovskite Membranes for Selective

Molten Carbonate/Perovskite Membranes for Selective CO2 Permeation... 

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. 

Two different sections are required because metallic Pd-based membranes for selective H2 extraction can only be operated below typically 700 °C because of membrane stability, while acceptable O2 fluxes through available perovskite-type O2 permselective membranes can only be realized above 900-1000 °C. In this case, the air separation is achieved in situ resulting in lower costs and intrinsic CO2 capture. 

Ammonia oxidation for the manufacture of NO (an intermediate in nitric acid production) is carried out in an oxidation reactor incorporating a Ca- and Sr-substituted lanthanum ferrite perovskite membrane. NO selectivity of the order of 98% is achieved by the membrane, while N2 is rejected completely. The membrane reactor obviates the need for expensive noble metal catalysts and does not produce environmentally harmful N2O. 

The considerations in this chapter were mainly prompted by the potential application of mixed-conducting perovskite-type oxides to be used as dense ceramic membranes for oxygen delivery applications, and lead to the following general criteria for the selection of materials... 

Taheri, Z., Nazari, K., Safekordi, AA., Seyed-Matin, N., Ahmadi, R., Esmaeili, N., and Tofigh, A. (2008) Oxygen permeation and oxidative coupling of methane in membrane reactor a new fecile synthesis method for selective perovskite catalyst. 

Zhang, K., Sunarso, J., Shao, Z., Zhou, W Sun, C., Wang, S., and Liu, S. (2011) Research progress and materials selection guidelines on mixed conducting perovskite-type ceramic membranes for oxygen production. RSC Adv., 1, 1661-1676. 

Taheri, Z., Nazari, K., Safekordi, A., et al (2008). Oxygen Permeation and Oxidative Coupling of Methane in Membrane Reactor A New Facile Synthesis Method for Selective Perovskite Catalyst, J. Mol Catal A Chem., 286, pp. 79-86. 

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