Structural Performance of Micro and Nano-structured Ceria for Solar Thermochemical Fuel Production

Abstract

Flame-made nano-structured and commercial micro-structured ceria powders are assessed for two-step carbon dioxide splitting (CDS) driven by a reduction step of methane partial oxidation (MPO). The MPO and CDS reaction rates are strongly dependent on the structural properties of the ceria powders. The nano-structured material shows up to 167% and 144% higher H2 and CO average production rates during MPO, respectively, and 97% higher CO average production rate during CDS than the micro-structured commercial ceria. After 10 consecutive cycles, the rates are still 57%, 54% and 15% higher, respectively. The higher reaction rates for the nano-structured ceria are attributed to the initially 10 times higher specific surface area of the flame-made nano-structured ceria (76.6 m2 g-1) than that of commercial micro-structured powders (7.3 m2g-1). These findings indicate that thermal and chemical stabilization of nano-scale structural features is the key to achieving long-term cyclability of ceria in high temperature solar thermochemical fuel production