(55a) Catalytic Reduction of CO2 into Solar Fuels Via Ferrite Based Redox Reactions

CO₂ is considered as the major greenhouse gas and its continuous emission from various sources such as chemical industry, automobile exhaust, combustion of fossil fuels and others leads to one of the major environmental issues i.e. global warming. It is highly important to work towards the reduction in the excessive discharge of CO₂ and also the utilization of the liberated CO₂ towards value added products. In this regard, one of the promising options is to reduce the CO₂ into CO via ferrite (doped iron oxide) based thermochemical redox cycles performed using concentrated solar energy. This produced CO can be combined with the H₂ produced from the water splitting reaction via similar ferrite based thermochemical cycle to yield into syngas which can be further processed to liquid fuels such as Methanol, Diesel, and Kerosene via the Fischer-Tropsch process. It is highly important to note that the ferrite materials were considered as the bench-mark for the production of hydrogen via water splitting cycle, however; their utilization towards the CO₂ splitting reactions is not yet investigated in detail. Hence, in this study, various ferrite based materials (transition metal doped iron oxides) such as Ni-, Zn-, Co-, Mn-, Mg-, and Cu-ferrite were synthesized via sol-gel method. After characterizing the composition, morphology, surface area, and other physico-chemical properties, the derived ferrite materials were tested towards thermochemical CO₂ splitting using a thermogravimetric analyzer (TGA). The ferrite powder was thermally reduced at 1400^oC, while the CO₂ splitting reaction was performed at lower temperatures (800 to 1100^oC). O₂ and CO release was further monitored by gas chromatography. The synthesized ferrite materials were compared with each other and also with the ceria based materials based on their redox reactivity and thermal stability by performing multiple thermochemical thermal reduction and CO₂ splitting steps.