Scalable Synthesis and Characterization of Active Iron Aluminate Material for Solar Thermal Water Splitting

Solar thermochemical fuels have emerged as a competitive alternative to fossil fuels as they are carbon-neutral and functionally interchangeable with conventional fuels. These fuels are produced by splitting water and carbon dioxide at high temperature, producing hydrogen and carbon monoxide. The reaction normally requires an extraordinarily high temperature, but it can be lowered to a more manageable temperature with the help of an iron aluminate oxygen carrier.

This work focuses on developing a scalable synthesis method for the active material, as well as characterization of the material under harsh chemical looping conditions. Spray drying is an attractive method for producing spherical, robust microparticles as it is cheap, scalable, and widely adopted in industry. A literature review indicated that, while similar particles had been produced in previous studies, this particular formulation was novel and would require some experimentation. In these experiments, factors such as solids vol%, use of additives, and spray drying conditions were varied, and the resulting slurry was sprayed in a BUCHI B-290 Mini Spray Dryer. The spray dried particles were then calcined. A formulation has been developed and is being tested at pilot scale. In a separate experimental campaign, the robustness of the active material under rapid cycling was investigated. Iron aluminate material was synthesized via the Modified Pechini method, and a small amount was subjected to repeated redox cycles at 1400 ℃ in a stagnation flow reactor. The Modified Pechini method is a sol-gel method that allows for a more homogeneous microstructure in the final product. The material has thus far undergone over 1000 redox cycles in this campaign, with 2000 total cycles planned, to demonstrate consistent reactivity over long periods of time.