(106d) Sustainable Solar Fuel Production By a Mixed Metal Oxide Based Thermochemical H2o/CO2 Splitting Cycle

Currently, fossil fuels are the major energy source utilized for the fulfillment of the energy requirement. The continuous and excessive utilization of fossil fuels leads to increase in the greenhouse gas emissions and oil prices. The usage of fossil fuel affects the world both environmentally and economically. To solve this issue, production of carbon free renewable and sustainable fuels which can replace fossil fuels is essential. Therefore, we are currently investigating a metal oxide (MO) based two-step thermochemical H₂O/CO₂ splitting cycle powered by concentrated solar energy for the production of solar H₂ (which can be used directly as a fuel) and solar syngas (which can be used to produce liquid transportation fuels via catalytic Fischer Tropsch process). In these cycles, the first step consists of the endothermic reduction of a metal oxide at elevated temperatures releasing O₂. The second step corresponds to the slightly exothermic re-oxidation of the reduced metal oxide at lower temperatures by H₂O, CO₂, or a mixture of the two producing H₂, CO or syngas. Among many metal oxides investigated for solar fuel production, in recent years, research has been focused towards non-volatile mixed metal oxides such as ferrites and doped ceria. In our laboratory, various doped ferrites and doped ceria materials (which are not yet investigated for H₂O or CO₂ splitting cycles) were synthesized via various synthesis approaches such as sol-gel method, combustion synthesis, co-precipitation method, and others. These materials were characterized by powder XRD, BET surface area analysis, SEM, TEM, XPS, ICP, EDX, and others. Furthermore, the solar fuels production ability of these derived materials was further examined by performing multiple thermochemical cycles using a thermogravimetric analyzer and a packed bed reactor set-up. Obtained results indicate that the mixed metal oxides derived in our laboratory are capable of producing constant and high amounts of solar fuel in multiple thermochemical cycles. The redox reactivity of the derived materials was observed to be unchanged during multiple cycles. Results associated with the synthesis, characterization, and thermochemical experiments will be presented in detail.