Optimized Reactants Mixture and Products Hydrolysis in the Manganese Oxide Thermochemical Cycle

A novel system composed by an aqueous slurry prepared by MnO and NaOH mixture was tested for the hydrogen production in the sodium manganese oxide thermochemical cycle. The hydrogen evolution occurs at lower temperature than conventional mixtures utilized in the cycle. Experiments performed in a Temperature Programmed Desorption/Reaction apparatus (TPD/TPR) have evidenced hydrogen production around 500°C. The hydrolysis step of α-NaMnO₂ has been studied and the importance to conduct hydrolysis reaction under inert gas is discussed. A manganese disproportion mechanism is hypothesized to explain the appearance of manganese (II) and manganese (IV) containing phases.