Concentration-Dependent Solar Thermochemical CO(2)/H(2)O Splitting Performance by Vanadia–Ceria Multiphase Metal Oxide Systems

The effects of V and Ce concentrations (each varying in the 0–100% range) in vanadia–ceria multiphase systems are investigated for synthesis gas production via thermochemical redox cycles of CO(2) and H(2)O splitting coupled to methane partial oxidation reactions. The oxidation of prepared oxygen carriers is performed by separate and sequential CO(2) and H(2)O splitting reactions. Structural and chemical analyses of the mixed-metal oxides revealed important information about the Ce and V interactions affecting their crystal phases and redox characteristics. Pure CeO(2) and pure V(2)O(5) are found to offer the lowest and highest oxygen exchange capacities and syngas production performance, respectively. The mixed-oxide systems provide a balanced performance: their oxygen exchange capacity is up to 5 times higher than that of pure CeO(2) while decreasing the extent of methane cracking. The addition of 25% V to CeO(2) results in an optimum mixture of CeO(2) and CeVO(4) for enhanced CO(2) and H(2)O splitting. At higher V concentrations, cyclic carbide formation and oxidation result in a syngas yield higher than that for pure CeO(2).