Characterization of Fe2O3/CeO2 oxygen carriers for chemical looping hydrogen generation

Abstract

Fe2O3 is currently the most proper active metal oxide for chemical looping hydrogen generation (CLHG). However, supports are necessary to improve the reactivity and redox stability. CeO2 can enhance the oxygen mobility, leading to high redox reactivity and carbon deposition resistance, which can be an excellent alternative support for oxygen carriers. In this paper, Fe2O3/CeO2 oxygen carriers prepared by the co-precipitation method with different Fe2O3 loadings were investigated on a batch fluidized bed regarding the hydrogen yield and purity, redox reactivity and stability in CLHG with CO as fuel. The results showed that Fe6Ce4 is the best given comprehensive performance with no CO or CO2 observed in the obtained hydrogen (detection limit 0.01% in volume). The oxygen mobility property for the reducible support CeO2 and the physical contact between un-integrated Fe2O3 and CeO2 could improve the reduction of Fe2O3. In addition, the formation of the hematite-like solid solution and perovskite-type CeFeO3 could bring about abundant oxygen vacancies and promote the oxygen mobility, which contributes to the elimination of carbon deposition, counteracts the negative effect of serious sintering and guarantees the reactivity and redox stability of the Fe2O3/CeO2 oxygen carriers. The Fe2O3/CeO2 oxygen carriers were characterized by carbon monoxide temperature-programmed reduction measurement and X-ray diffraction patterns, and Fe6Ce4 was also selected to be characterized by scanning electron microscopy images and energy dispersive X-ray spectrometer analysis.