A thermodynamic property of Ca2Fe2O5 was exploited to improve the efficiency of the steam-iron process
to produce hydrogen. The ability of reduced Ca2Fe2O5 to convert a higher fraction of steam to hydrogen
than chemically unmodified Fe was demonstrated in a packed bed. At 1123 K, the use of Ca2Fe2O5
achieved an equilibrium conversion of steam to hydrogen of 75%, in agreement with predicted thermodynamics
and substantially higher than that theoretically achievable by iron oxide, viz. 62%. Furthermore,
in Ca2Fe2O5, the full oxidation from Fe(0) to Fe(III) can be utilised for hydrogen production – an improvement
from the Fe to Fe3O4 transition for unmodified iron. Thermodynamic considerations demonstrated
in this study allow for the rational design of oxygen carriers in the future. Modifications of reactors to
capitalise on this new material are discussed.
2016 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license