Magnetic separation for a continuous solar-two-step thermochemical cycle for solar hydrogen/CO production using ferrites

A novel solar-two-step thermochemical concept for continuous production of H2 or CO from solar energy and H2O or CO2 using the redox pair MOFe2O3/MO as reactive particles is proposed and assessed. Here, an efficient continuous separation mechanism is devised by the use of an external magnetic field and the weak magnetization of MOFe2O3 at the working temperatures. The mechanism is suitable for systems of ferrites with a Curie temperature in the range 500–800 ∘C where water or CO2 decomposition occurs. One of the most promising candidates is the Fe3O4/FeO system. Pyromagnetic coefficients for Fe3O4 were obtained experimentally. A simple magnetic trap was employed and the separation ratios Fe3O4/FeO were obtained. The results are encouraging and motivate the development of full-scale solar reactor prototypes.