Decomposition H2O and CO2 with Nano-size Cu-Ferrites Prepared by Irradiation of Ultrasonic Wave

초록

In order to improve the reactivity of the redox reaction for the CO2 decomposition, the nanosize ferrite (Ni0.5Cu0.5)Fe2O4 with spinel structure was prepared by the irradiation of the ultrasonic wave for 6 h. The particle size of the prepared ferrite was smaller than 20nm and it was applied to the CO2 decomposition. The reduction of the ferrite started from 180℃ and the weight decreased about 24 wt% up to 800℃. As a result of the reduction, the spinel structure of (Ni0.5Cu0.5)Fe2O4 changed to mixed phases of Fe, Cu, Fe-Ni, and FeO. The CO2 decomposition with the reduced ferrite up to 800℃ consisted of two-step reaction. CO was produced as a main product in the first CO2 decomposition. However, carbon was deposited at the same time as producing CO in the second CO2 decomposition. After the CO2 decomposition, the weight of the reduced ferrite was increased about 15 wt% and phases changed to a mixed phase of metallic Ni and Cu, and Fe3O4. So, CO2 was decomposed by oxidation of Fe and FeO. When Fe was oxidized by CO2, CO in first CO2 decomposition was produced by a catalytic action of Cu, but in the second CO2 decomposition, carbon and CO were produced by a catalytic action of Ni with Cu.