Thermodynamic simulation and experimental investigation of manganese oxide (MnOx) for integrated CO2 capture and conversion via chemical looping route

Abstract

Due to its high energy conversion efficiency, low economic cost and collaborative pollution control, chemical looping is emerging as a promising technology to deal with CO2 emissions in energy and environmental fields. Based on the dual property of being carbonated and oxidized of MnO, the integrated CO2 capture and conversion performance of manganese oxide is analyzed via chemical looping CH4-O2-CO2 route. Thermodynamic calculation and process simulation indicate the equilibrium reduced solid is MnO instead of metallic Mn, which is consistent with material characterization. The gaseous oxygen released by MnO2 is the prerequisite for its reactivity from thermodynamic analysis and is the effective step for MnO2-CH4 reforming experiments. The CH4 reforming performance of Mn2O3 is limited from thermodynamic hierarchy and the lattice oxygen capacity of Mn3O4 affects its reactivity with CH4. Mn2O3 obtains the best partial oxidation reforming selectivity under higher operating temperature. The lattice oxygen is replenished with an obtained mole ratio of MnO2:Mn2O3 as 0.12:0.03 through air oxidation under medium temperature conditions. The weight increment at CO2 atmosphere indicates the 41.6 mol.% CO2 capture ability of MnO. The CH4-O2-CO2 cycle experiment proves the achievement in realizing the integrated CO2 capture and utilization with one material via chemical looping route.