Microstructure, kinetics and mechanisms of CO2 catalytic decomposition over freshly reduced nano-crystallite CuFe2O4 at 400-600 °C

The decomposition Of CO2 was investigated as a process of both industrial and environmental importance. Copper ferrite was obtained by the thermal decomposition of acetate precursors. CuFe2O4 were isothermally reduced in H-2 flow at 400-600 degrees C, the isothermal reduction profiles obtained in this study show that a topochemical mode of reduction is done by which the reduction process proceeds. The nano-wires metallic phase of iron (106 nm) and copper (56 nm), produced from the complete reduction of CuFe2O4, were subjected to the direct reoxidation in CO2 flow at 400-600 degrees C. The reoxidation process was found to be controlled by both the reduction and reoxidation temperatures. CO2 decomposes to carbon nano-tubes during the reoxidation of the freshly reduced CuFe2O4. The prepared, completely reduced and reoxidized CuFe2O4 compacts, were characterized by XRD, SEM, TEM and reflected light microscope. For the reoxidation process, it is found that at the initial stages the reaction is controlled by the interfacial chemical reaction mechanism with some contribution to the gaseous diffusion mechanism. On the other hand at the intermediate and final stages the mechanism by which the reoxidation process proceeds was found to be the solid-state diffusion. (c) 2005 Elsevier B.V. All rights reserved.