Production of carbon from carbon dioxide with iron oxides and high-temperature solar energy

We demonstrate from both a theoretical and experimental point of view that CO2 can be thermally reduced to carbon with concentrated solar energy. The concept involves reactions between CO2 and iron oxides. Thus, we experimentally studied the thermochemical reactivity of iron oxides for splitting CO2 into C(gr) and O-2 using high-temperature powder X-ray diffraction, gas chromatography, and mass spectrometry. Emphasis was given to the dependence of the gaseous and solid reaction products on the structural change of wustite (Fe1-yO). The CO2 decomposition occurs in two steps at temperatures near 773 K: First wustite reacts with CO2 to form CO and magnetite (Fe3O4); then CO disproportionates to C(gr) and CO2. Fe3O4 can be recycled to Fe1-yO by thermal dissociation above 2200 K using highly concentrated solar radiation as the only energy source for process heat.