Mixed ionic-electronic conductors are materials which conduct both oxide ions and electronic charge carriers (electron and/or hole) simultaneously. Perovskite-type oxides (ABO3) with valence-variable cations and oxide ion vacancies such as La1-xSrxCo1-yFe yO3-δ (LSCFs) are representative and most intensively studied mixed conductors. LSCFs and their relatives desorb and absorb a large amount of oxygen reversibly from and into the crystal lattice without changing their fundamental crystal structures. By full use of the reversible oxygen sorption-desorption and mixed conductive properties, oxygen separation from, for example, air with 100% selectivity is possible at temperatures above 300 °C. High temperature oxygen separation is very important technology to recover waste heat from high-temperature facilities and can contribute the improvement of energy efficiencies. Oxygen separation is also a key technology for oxy-fuel combustion, because its exhaust consists, in principle, of H2O and CO2 which is ready for CCS (Carbon dioxide Capture and Storage). In this review article, two types of oxygen separation technologies by using mixed ionic-electronic conductors are outlined; membrane separation at high temperature range (usually above 800 °C) and temperature/pressure swing separation at medium to high temperature range (for example, 300-800 7deg;C). After describing basic aspects of mixed conductive perovskite-type oxides, current research status and future challenges will be reviewed.
|ジャーナル||Nihon Enerugi Gakkaishi/Journal of the Japan Institute of Energy|
|出版ステータス||出版済み - 9月 2010|
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