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 CO 2 can be thermally reduced to carbon with concentrated solar energy. The concept involves reactions between CO 2 and iron oxides. Thus, we experimentally studied the thermochemical reactivity of iron oxides for splitting CO 2 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 (Fe 1- y O). The CO 2 decomposition occurs in two steps at temperatures near 773 K: First wustite reacts with CO 2 to form CO and magnetite (Fe 3 O 4 ); then CO disproportionates to C(gr) and CO 2 . Fe 3 O 4 can be recycled to Fe 1- y O by thermal dissociation above 2200 K using highly concentrated solar radiation as the only energy source for process heat.