Comparison of Nickel and Cobalt Mixed‐Metal Ferrites for Hydrogen Production using Chemical Looping

A simple model of the chemical‐looping hydrogen‐production system was developed to investigate the syngas reduction of and H 2 O/O 2 oxidation of Fe 2 O 3 , CoFe 2 O 4 , and NiFe 2 O 4 . The model was used to calculate the metal oxide reduction conversion in a packed‐bed reactor (PBR) before breakthrough of CO/H 2 , the reduction product gas composition, the steam necessary to fully oxidize the reduced material, and the steam‐associated energy requirements and to analyze the possibility of hybrid H 2 O/O 2 oxidation for H 2 and electricity generation. Model results were compared to laboratory PBR experimental results with additional analysis by thermogravimetric analysis, differential scanning calorimetry, and temperature‐programmed reduction for each material. Use of NiFe 2 O 4 and CoFe 2 O 4 was found to increase the flexibility of the chemical‐looping hydrogen process, which allowed more H 2 production than is currently possible with Fe‐based materials while maintaining the ability for electricity generation from supplemental O 2 oxidation. The mixed‐metal spinel materials were ideally suited for converting lower quality syngas into H 2 by lower temperature reactions.