Computational thermodynamic analysis of a solar thermochemical manganese oxide - Manganese sulfate water splitting cycle

Abstract

In this paper computational thermodynamics modeling of the solar H2 production via twostep thermochemical manganese oxide - manganese sulfate (MnO-MnS) water splitting cycle is reported. In this cycle, the first step corresponds to the exothermic oxidation of manganese oxide via SO2 and H2O producing MnSO4 and H2 and second step is related to the endothermic reduction of MnSO4 into MnO, SO2, and O2. The MnO and SO2 produced in the second step can be recycled to the step 1 and hence, reutilized for the production of H2 via water splitting reaction. The equilibrium compositions for the MnSO4 thermal reduction and water splitting steps were determined by performing thermodynamic analysis and are reported here. Furthermore, exergy analysis was performed to determine the cycle efficiency and solar to fuel energy conversion efficiency attainable without heat recuperation.