Hydrogen production by two-step thermochemical cycles based on commercial nickel ferrite: Kinetic and structural study

• Commercial Ni ferrite produces oxygen and hydrogen through 2-step thermochemical cycles.
• Thermodynamic and kinetic studies have been performed.
• Activation energies and rate constants are estimated for each step of the cycle.
• Hydrogen and oxygen production over several thermochemical cycles is reported.

One of the promising routes for hydrogen production consists of the dissociation of the water molecule through two-step thermochemical cycles based on iron oxides, i.e., ferrites. In a previous work, our group evaluated the activity of five commercial ferrites for this purpose, being Ni ferrite the one that exhibits the highest hydrogen production. In this work, the results obtained after a more exhaustive study of the thermochemical cycle based on a commercially available Ni ferrite are presented. Structural characterization of NiFe2O4 after each step of the thermochemical cycle is shown, as well as oxygen and hydrogen production over several cycles. In addition, kinetic parameters of this cycle are also studied, fitting the experimental data obtained under isothermal conditions to the most appropriate model among those ascribed to gas–solid non-catalytic multistep reaction systems.