Novel Bimetallic Oxygen Carriers for Use in Chemical Looping Combustion

Chemical looping combustion (CLC) is a promising technology for coal-derived energy production. CLC offers a major advantage over conventional coal combustion by directly producing  a concentrated stream of CO₂ without expending the significant energy required for CO₂ separation. The development of robust oxygen carriers is critical for the efficient operation and adoption of CLC technology.

Traditional oxygen carriers such as CuO, Fe₂O₃, NiO, and CoO have disadvantages including low reactivity (Fe₂O₃), low melting point and high agglomeration (CuO), and health and environmental concerns (NiO). The development of new oxygen carriers with enhanced performance characteristics is required for successful deployment of coal CLC processes.

This invention describes the use of novel bimetallic oxygen carriers consisting of group II metal ferrites (MgFe₂O₄, CaFe₂O₄, SrFe₂O₄, and BaFe₂O₄) and transition metal ferrites (MnFeO₃ and CoFe₂O₄) for CLC of solid fuels such as coal, pet coke, and biomass. All the metal ferrites demonstrated better performance for coal CLC when compared to Fe₂O₃, including high and stable reactivity over multiple reduction/oxidation cycles as well as high attrition resistance. Further, the ferrite-based oxygen carriers displayed a low tendency to agglomerate at high temperatures. The metal ferrites can be produced using readily available materials at a cost comparable to Fe₂O₃ oxygen carriers.