Experimental Study of Natural Cu Ore Particles as Oxygen Carriers in Chemical Looping with Oxygen Uncoupling (CLOU)

The possibility of using three natural Cu ore particles as oxygen carriers in the chemical looping with oxygen uncoupling (CLOU) was investigated. The reaction kinetics of Cu2O with O-2 and the decomposition kinetics of CuO in a CO2 atmosphere at different temperatures and oxygen fractions were studied using thermogravimetric analysis (TGA). Both oxygen uptake and oxygen release exhibit a high reaction rate. Multiple oxygen uptake and oxygen release cycles indicated that three natural Cu ore oxygen carriers have high reactivity and cyclic stability. The high-temperature oxygen uptake and oxygen release process for producing O-2-CO2 gas mixtures in a fluidized-bed reactor packed with Cu-based oxygen-carrier particles through air separation with carbon dioxide as the purge gas was investigated. Oxygen was absorbed, and heat is stored by the Cu based oxygen-carrier particles with air being fed. An O-2-CO2 stream can be obtained when the fluidized bed was regenerated with carbon dioxide as the fluidizing gas. The O-2 fraction in the O-2-CO2 gas mixtures can be controlled by adjusting the reaction temperature, depending upon both thermodynamics and kinetics. Among the three natural Cu ore particles, the particles with a high Cu content experienced a serious agglomeration, while for the particles with a low Cu content, agglomeration did not occur after 20 cycles at a very high temperature (980 degrees C). This natural Cu ore oxygen carrier offers potential for further study and application in the chemical looping combustion and CLOU processes.