Ferrite based redox reactions are considered as one of the most promising redox system for the production of solar fuels such as solar H2, solar CO, or solar syngas via thermochemical splitting of water and CO2. In previous investigations, various ferrites based materials such as Fe3O4/FeO, Ni-ferrite, Co-ferrite, Mn-ferrite, Zn-ferrite, Ni-Zn-ferrite, Ni-Mn-ferrite, and etc. were investigated for the solar thermochemical splitting of water and CO2. These materials were derived via different synthesis approaches such as sol-gel, co-precipitation, SHS, aerosol spary analysis, solid state synthesis, combustion synthesis, and etc. Various reactor set-ups were also investigated towards the production of solar fuels via thermochemical splitting of H2O and CO2 using ferrites based materials such as packed bed reactors, fluidized bed reactors, aerosol reactors, cavity reactors and etc.
In this work, we performed the computational thermodynamic modeling to identify the solar to fuel conversion efficiency of the ferrite based two-step thermochemical splitting of water and CO2. Commercially available thermodynamic softwares and databases such as HSC Chemistry and FactSage were used to perform the thermodynamic simulations. At first, the equibrium thermodynamic compositions associated with the solar thermal reduction of ferrites and splitting of water and CO2 using the reduced ferrite materials were identified. The variation of the reaction enthalpy, entropy and Gibbs free energy for the thermal reduction and water/CO2 splitting steps with respect to the operating conditions were also determined. Furthermore, solar reactor efficiency analysis was performed by following the second law of thermodynamics and solar absorption efficiency of the solar reactor, solar energy input to the solar reactor, radiation heat losses from the solar reactor, net energy absorbed in the solar reactor, rates of entropy produced in the solar reactor and cooling units were calculated and plotted. At the end, the solar to fuel conversion efficiency of the ferrite based thermochemical water and CO2 splitting cycle was determined and compared with the previously investigated other metal oxide cycles. The thermodynamic simulation results will be presented in detail.