Kinetics of CO2 splitting by microwave irradiation using honeycomb-like pellets of Fe3O4/FeO

Abstract

Thermochemical fuel production is expected to improve CO2 utilization, and two-step chemical looping processes such as those driven by solar energy are being investigated extensively. In this study, CO2 splitting was performed under microwave irradiation using iron oxides (Fe3O4 and FeO) as the reducing agents. In addition, honeycomb-like pellets of the oxides were used to increase the contact area with the CO2 gas and prevent sintering at high temperatures. The microwave radiation could heat both Fe3O4 powder and the honeycomb-like pellets of the two iron oxides rapidly. The kinetics of the reduction of CO2 to CO under microwave irradiation were investigated by in-situ gas analysis. The apparent activation energy as calculated from the Arrhenius plot was 76.1 kJ/mol for the Fe3O4 powder, 48.3 kJ/mol for the honeycomb-like FeO pellets, and 25.3 kJ/mol for the honeycomb-like Fe3O4 pellets. The proposed microwave-based process for CO2 splitting using honeycomb-like pellets is a promising one for the processing of large amounts of CO2 gas per unit time.