Novel New Oxygen Carriers for Chemical Looping Combustion of Solid Fuels

Several bimetallic oxygen carriers, MFe2O4 (M = Co, Ni, Cu, Mg, Ca, Sr, and Ba) and MnFeO3, prepared by the precipitation method in a microwave and the direct decomposition method, were tested for potential use in the application of chemical looping combustion (CLC) of solid fuels. Thermogravimetric analysis (TGA) was used to study their reduction rate, oxidation rate, and cyclic reduction/oxidation properties. Comparative experimental data of novel bimetallic ferrites and pure Fe2O3 and CuO showed that all bimetallic ferrites had better reduction rates than pure Fe2O3. The Group 2 metal ferrites had better reduction and oxidation rates than transition-metal ferrites. BaFe2O4 was the highest performing among all bimetallic ferrites during both reduction and oxidation reactions. The reduction rate of BaFe2O4 is comparable to that of CuO at higher reaction temperatures (>900 degrees C). A 10 wt % loading of an inert support on the surface of the bimetallic oxygen carriers significantly decreased the particle agglomeration during the cyclic tests, which contributed to a better cyclic reaction performance.