Trapping and Methanation of CO₂ in a Domestic Microwave Oven Using Combinations of Sorbents and Catalysts

CO2 trapping and methanation allow to reduce greenhouse gas emissions and recycle CO2 into a sustainable fuel, provided renewable H-2 is employed. Microwave (MW)-based reactors provide an efficient means to use electrical energy for upgrading chemicals, since MW can selectively heat up the load placed in the reactor and not the reactor itself. In this study, CO2 capture and methanation were investigated using solid adsorbents (ZrO2 and Fe3O4), microwave absorbers (SiC and Fe3O4) and Ru/SiO2 as CO2 the methanation catalyst. The sorption and catalyst beds were located in a domestic MW oven that was used to trigger CO2 desorption and methanation in the presence of H-2. The working Fe-based structure turned out to be a mixture of FeO and Fe, which allowed for MW absorption and local heating; it also acted as a CO2 sorbent and reverse water-gas shift catalyst. Various reactor configurations were used, leading to different performances and selectivity to CO and CH4. To the best of our knowledge, this is the first report of its kind showing the potential of using inexpensive microwave technology to readily convert trapped CO2 into valuable products.