International Journal of Hydrogen Energy, Vol.35, No.2, 568-576, 2010
Redox cycling of CuFe2O4 supported on ZrO2 and CeO2 for two-step methane reforming/water splitting
CuFe2O4 supported on ZrO2 and CeO2 for two-step methane reforming was evaluated to determine if it could enhance the reactivity, CO selectivity and thermal stability of CuFe2O4. Two-step methane reforming consists of a syngas production step and a water splitting step. CuFe2O4 supported on ZrO2 and CeO2 was prepared using an aerial oxidation method. Non-isothermal methane reduction was carried out on TGA to compare the reactivity of CuFe2O4/ZrO2 and CuFe2O4/CeO2. In addition, a syngas production step was performed at 900 degrees C and water splitting was conducted at 800 degrees C alternatively five times to compare the methane conversion, CO selectivity, cycle ability and hydrogen production by water splitting in a fixed bed reactor. If the 1st syngas production step results are excluded due to over-oxidation, CuFe2O4/ZrO2 and CuFe2O4/CeO2 showed approximately 74.0-82.8% and 60.3-87.5% methane conversion, respectively, and 44.0-47.8% and 65.2-81.5% CO selectivity, respectively. Using CeO2 and ZrO2 as supports effectively improved the reactivity and methane conversion compared to CuFe2O4. CuFe2O4/ZrO2 showed high methane conversion due to the high phase stability and thermal stability of ZrO2 but the selectivity was not improved. After 5 successive cycles, the CeFeO3 phase was found on CuFe2O4/CeO2. Furthermore, methane conversion, CO selectivity and the amounts of hydrogen production of CuFe2O4/CeO2 increased with increasing number of cycles. Additional test up to the 11th cycle on CuFe2O4/CeO2 revealed that CeO2 is a better support that ZnO2 in terms of the reactivity and CO selectivity. (C) 2009 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.