Solar Syngas Production via H2O/CO2-Splitting Thermochemical Cycles with Zn/ZnO and FeO/Fe3O4 Redox Reactions

The solar production of syngas from H2O and CO2 is examined via two-step thermochemical cycles based on Zn/ZnO and FcO/FC3O4 redox reactions. The first, endothermic step is the thermal dissociation of the metal oxide using concentrated solar radiation as the energy source of high-temperature process heat. The second, nonsolar, exothermic step is the reaction of the metal or reduced metal oxide with a Mixture of H2O and CO2 yielding syngas (H-2 and CO), together with the initial form of the metal oxide that is recycled to the First step. Chemical equilibrium compositions for the systems of Zn and FeO with CO2 + H2O Were Computed as a function of temperature and pressure for different stoichiometries. A series of dynamic thermogravimetric experimental runs in the range 673-1423 K was carried Out to evaluate the reaction kinetics and syngas quality of the second step. The molar now rate fractions of the gaseous products exhibited linear dependencies on the molar flow rate fractions of the gaseous reactants for both the FeO/Fe3O4 and Zn/ZnO systems.