Mixed Oxides of Iron and Manganese as Potential Low-Cost Oxygen Carriers for Chemical Looping Combustion

Low-cost oxygen carriers with multicycle chemical looping combustion (CLC) performance and CO2 selectivity have been explored to realize a practical oxygen carrier to obtain sequestration-ready CO2 from the combustion processes. The cubic structures of the pure mixed oxides of Fe and Mn (Fe3Mn3O8 and FeMnO3; Fe-Mn-O) were prepared successfully as oxygen carriers through a coprecipitation method. The Fe-Mn-O systems showed 100% CH4 combustion performance in the absence of air or oxygen. MnO and Fe3O4 are the reduced products of the Fe-Mn-O systems after the CH4 combustion reaction. The regeneration of the Fe-Mn-O phase was achieved readily by reoxidation of their reduced products in air. The Fe-Mn-O systems showed a stable and multicycle CLC performance, however, the individual oxides of Fe and Mn showed an inferior CLC performance. Pure CO2 was formed during the CH4 combustion reaction of the Fe-Mn-O systems with practically no toxic CO byproduct. Therefore, the mixed oxide phase of Fe and Mn shows potential as a practical oxygen carrier in terms of its multicycle CLC performance and CO2 selectivity.