Solar thermochemical process for hydrogen production via two-step water splitting cycle based on Ce1−xPrxO2−δ redox reaction

Abstract Ce 1− x Pr x O 2− δ ( x  = 0, 0.05, 0.1, 0.2 and 0.3), as reactive ceramics synthesized by combustion method for H 2 production via two-step water splitting reaction with concentrated solar energy, was investigated in present work. XRD analysis of the samples shows that Pr 6 O 11 underwent a phase transition into Pr 2 O 3 and Pr 2 O 3 cannot be oxidized by steam to yield H 2 in two-step water splitting reaction. The solid solutions of the samples containing Ce were formed with a single cubic CeO 2 fluorite structure after synthesis and even after two-step water splitting reaction. Although Pr cannot be oxidized by steam to generate H 2 in two-step water splitting reaction, the promotion effect is present with the introduction of 5 mol% and 10 mol% Pr into CeO 2 on the amounts of O 2 and H 2 , but the volume of H 2 evolved is enhanced or not, strongly dependent on the H 2 -generation temperature. The optimum H 2 -generation temperature is 1023 K.