Hydrogen production by water splitting on manganese ferrite-sodium carbonate mixture. Feasibility tests in a packed bed solar reactor-receiver

The sodium manganese mixed ferrite thermochemical cycle Na(Mn1/3Fe2/3)O2/(MnFe2O4 + Na2CO3) for sustainable hydrogen production has been implemented in a solar reactor-receiver, packed with indirectly heated MnFe2O4/Na2CO3 mixture pellets, with the aim of verifying its feasibility and of determining the critical aspects of the process. The reactor operates at nearly constant temperature in the range 750–800 °C; the shift between the hydrogen-producing and regeneration steps is obtained by switching the reactive gas from water to carbon dioxide. Hydrogen produced during 1-h operation of the reactor is in the range of 130–460 μmol/g of mixture, depending on experimental conditions. Compared to other existing prototypes, the implemented process obtains comparable production efficiencies while operating at lower temperature both in the hydrogen production and regeneration phases.