Solar co-production of samarium and syngas via methanothermal reduction of samarium sesquioxide

Abstract

This paper reports the thermodynamic analysis of the solar methanothermal reduction of Sm2O3 for the co-production of Sm and syngas in (a) Sm-Syngas open cycle, and (b) Sm-Syngas closed cycle. As per the chemical thermodynamic equilibrium modeling, the conversion of Sm2O3 into Sm increase with the increase in the CH4/Sm2O3 ratio and 100% conversion is possible at 2528 K if CH4/Sm2O3 ratio is equal to 3 is used. Exergy efficiency analysis of both open and closed cycles indicate that the QSm2O3-reduction, Qsolar, Qre-radiation, and Qquench increases with the increase in the CH4/Sm2O3 ratio. Likewise, WFC-Ideal-1, QFC-Ideal-1, and HHVsyngas-1 also increases with the upsurge in the CH4/Sm2O3 ratio. Similar observations were realized in case of Sm-Syngas closed cycle. The ?exergy (33.91%) and ?solar-to-fuel (45.93%) of the Sm-Syngas open cycle was observed to be maximum in case of CH4/Sm2O3 ratio = 3. As one of the applications, Sm was utilized toward splitting of H2O and CO2 together for the production of syngas via Sm-Syngas closed cycle. At similar operating conditions, the ?exergy-closed (45.22%) and ?solar-to-fuel-closed (61.24%) of the Sm-Syngas closed cycle was observed to be higher as compared to the Sm-Syngas open cycle. Furthermore, it was observed that, these efficiency values can be increased significantly due to the utilization of higher values of C and recycling of the heat rejected by the quench unit and H2O/CO2 splitting reactor.