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 O₂ 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 (Fe_1-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 Fe_1-yO by thermal dissociation above 2200 K using highly concentrated solar radiation as the only energy source for process heat.