Synergetic effects of mixed copper-iron oxides oxygen carriers in chemical looping combustion

► The components of CuO-Fe2O3 oxygen carrier were optimized to obtain good reactivity and physical stability. ► Synergistic effect of CuO-Fe2O3 was observed and characterized for chemical looping reaction. ► The nature of the fuel influences the reactivity and reduction status of the oxygen carriers. ► Possible reasons for the deeper reduction of Fe2O3 in the presence of CuO are presented.