Hydrogen production via a novel CoO/Co based chemical looping water gas shift: Validation and improvement strategies

Hydrogen production via thermochemical cycles represents an attractive, simple, and clean pathway for hydrogen generation. In this work, a novel chemical looping water gas shift (CL-WGS) process for hydrogen production using CoO as oxygen carrier and CO as reducing agent was developed and validated. The process exhibited high hydrogen production capacity and excellent reversibility achieving a total hydrogen production of 12.72 mmol H 2 /g material over ten redox cycles. Hydrogen production increased upon cycling from 0.89 mmol H 2 /g material in the first cycle to 1.61 mmol H 2 /g material in the tenth cycle. This enhanced hydrogen production is attributed to a higher accessible active surface area upon cycling. Carbon deposition played a key role in this enhancement, acting as a physical spacer and promoting particle fragmentation upon extended cycling. Further improvements in hydrogen production were achieved via partial substitution of CoO with 10 mol% NiO and the addition of 5 wt% TiO 2 nanoparticles, both of which enhanced CoO reducibility and mitigated particle sintering. The highest performance was obtained for the thermochemical material containing both NiO and TiO 2 , yielding 24.81 mmol H 2 /g material over ten redox cycles and highlighting the synergistic effect between the two strategies.