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

Abstract

A novel solar-two-step thermochemical concept for continuous production of H 2 or CO from solar energy and H 2 O or CO 2 using the redox pair MOFe 2 O 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 O 3 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 CO 2 decomposition occurs. One of the most promising candidates is the Fe 3 O 4 /FeO system. Pyromagnetic coefficients for Fe 3 O 4 were obtained experimentally. A simple magnetic trap was employed and the separation ratios Fe 3 O 4 / FeO were obtained. The results are encouraging and motivate the development of full-scale solar reactor prototypes.