Computational discovery of metal oxides for chemical looping hydrogen production

Chemical looping hydrogen (CLH) production is a promising pathway that can offer both use of renewable resources and efficient CO2 capture capabilities. Here, we use the CALculation of PHase Diagrams (CALPHAD) thermodynamic database to study the water conversion capability of metal oxides (MOx) for CLH. We report the discovery of iron-based oxides with theoretical hydrogen yields up to 8 times higher than those of state-of-the-art oxides (e.g., ceria and ferrites). More specifically, Fe0.4Co0.6Ox is found to have a theoretical conversion efficiency capability > 50% at 700 degrees C. Experimental results are presented, and a technoeconomic model quantifies the importance of MOx oxygen capacity and water conversion in this process. This reflects the potential of CLH production with a hydrogen cost of $1.25 +/- $0.38/kg at a scale of 50 tons per day. This is comparable to steam methane reforming but with the added benefit of producing a stream of pure CO2.

Automated summary

The study discovered iron-based oxides with significantly higher theoretical hydrogen yields and conversion efficiency in chemical looping hydrogen production, showcasing great potential and importance in reducing hydrogen costs.