Experimental and theoretical study on performance of Cu-Fe spinel supported with certain inerts during chemical looping combustion

CuFe2O4 spinel oxygen carriers supported with certain inerts (CuF2O4@Support, Support = MgO, ZrO2 and TiO2) were investigated for their reactivity and redox performance. The experimental results show that the main reduction peak temperature of CuF2O4@ZrO2 with CO is about 448 degrees C. The uniform distribution of nanocrystalline CuF2O4 grains on ZrO2 is responsible for the increase of the low-temperature reactivity of OC. The deactivation rate of the CFO-based OCs after 15 redox cycles were 57.08 % (CuF2O4), 35.99 % (CuF2O4@MgO), 6.13 % (CuF2O4@ZrO2) and 11.67 % (CuF2O4@TiO2), respectively. The Zener pinning effect caused by ZrO2 is beneficial to the redox performance of OC. The DFT results show that CO oxidation goes through two elementary reactions upon the CuF2O4@ZrO2 surface (Ea = 97.96 kJ/mol), but three steps upon CuF2O4@MgO (Ea1 = 168.22 kJ/mol, Ea2 = 115.77 kJ/mol) and CuF2O4@TiO2 (Ea1 = 117.06 kJ/mol, Ea2 = 48.02 kJ/mol) surfaces. The electron density difference and PDOS analysis suggest that CuF2O4@ZrO2 exhibits the highest affinity towards CO, the interaction between fuel molecules and CuF2O4@ZrO2 is the strongest among the three modified OCs. Therefore, ZrO2 may be a potential support for CuF2O4-based oxygen carriers. This work may provide a new perspective for the development and industrialization of Cu-Fe spinel OCs.