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

摘要

Abstract A novel solar-two-step thermochemical concept for continuous production of H $$_2$$ 2 or CO from solar energy and H $$_2$$ 2 O or CO $$_2$$ 2 using the redox pair MOFe $$_2$$ 2 O $$_3$$ 3 /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 MOFe $$_2$$ 2 O $$_3$$ 3 at the working temperatures. The mechanism is suitable for systems of ferrites with a Curie temperature in the range 500–800 $$^{circ }$$ ° C where water or CO $$_2$$ 2 decomposition occurs. One of the most promising candidates is the Fe $$_3$$ 3 O $$_4$$ 4 /FeO system. Pyromagnetic coefficients for Fe $$_3$$ 3 O $$_4$$ 4 were obtained experimentally. A simple magnetic trap was employed and the separation ratios Fe $$_3$$ 3 O $$_4$$ 4 /FeO were obtained. The results are encouraging and motivate the development of full-scale solar reactor prototypes.