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 en ergy. The concept involves reactions between CO2 and iron oxides. Thus , we experimentally studied the thermochemical reactivity of iron oxid es 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 product s on the structural change of wustite (Fe1-yO). The CO2 decomposition occurs in two steps at temperatures near 773 K: First wustite reacts w ith CO2 to form CO and magnetite (Fe3O4); then CO disproportionates to C(gr) and CO2. Fe3O4 can be recycled to Fe1-yO by thermal dissociatio n above 2200 K using highly concentrated solar radiation as the only e nergy source for process heat.