Computational discovery of metal oxides for chemical looping hydrogen production

Highlights

• Chemical looping hydrogen (CLH) production adds the benefit of producing pure CO₂

• Iron-based oxides were found with H₂ yields up to 8× that of state-of-the-art MO_x

• Fe_0.4Co_0.6O_x has a theoretical H₂O conversion capability >50% at 700°C

• CLH could produce H₂ at $1.25 ± $0.38/kg at a scale of 50 tpd

Summary

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 (MO_x) 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, Fe_0.4Co_0.6O_x is found to have a theoretical conversion efficiency capability > 50% at 700°C. Experimental results are presented, and a technoeconomic model quantifies the importance of MO_x 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.