Splitting of CO2 by Manganite Perovskites to Generate CO by Solar Isothermal Redox Cycling

Abstract

Solar isothermal thermochemical splitting of CO, by oxides such as CeO2 to generate CO has been reported in the literature. With CeO2, isothermal CO2 splitting occurs at 1773 K, but the results are not satisfactory in terms of fuel yield. The limited reducibility and sublimation prevent the use of CeO2. La1-xSrxMnO3 (LSM)-based perovskites have recently been identified as a potential candidate for a two-step process in view of the greater oxygen release at reduced temperature and greater fuel yield compared to that of CeO2. Considering the extraordinary properties of perovskite manganites in the two-step process, we have employed La1-xSrxMnO3 (x = 0.3, 0.4, and 0.5) for solar isothermal CO production and obtained CO yields of 133.9 mu mol/g by La0.5Sr0.5MnO3 at a temperature as low as 1673 K under the reduction and oxidation conditions of 10(-5) atm O-2 and 1 atm CO2, respectively. The global CO production rate by La0.5Sr0.5MnO3 (601.8 mu mol/g/h) is far superior (similar to 3 times higher) to that of CeO2 at 1773 K. Further improvement in performance is achieved by using Y0.5Sr0.5MnO3, containing a very small rare earth ion. This perovskite produces 1.8 times more CO than La0.5Sr0.5MnO3 at a record low temperature of 1573 K. These results the potential for practical application. are noteworthy and demonstrate the potential for practical application.