Knowledge Bank

The discovery and exploration of shale gas has provided the U.S. with abundant energy resources. Methane from shale gas has been widely considered a game-changing energy resource. However, the large quantity of CO2 emissions associated with methane combustion raises environmental concerns. Chemical Looping Combustion (CLC) processes are widely considered to be transformative clean energy conversion technologies. These technologies utilize an oxygen carrier to efficiently oxidize the fuel to sequestrable CO2 and steam. Thus, the performance of the oxygen carrier, i.e., supported iron oxides, is critical for these processes. In this study, iron oxides on different support materials are synthesized and compared. The reactivity for various supported iron oxides is investigated by Thermogravimetric Analyzer (TGA). The effect of varying the reducing gas composition (a mixture of methane and nitrogen) is also examined. Furthermore, a minimum gas flow rate of 100 mL/min with 66.67% methane gas composition is identified. Three supported iron oxides, namely MgAl2O4, MgO and Al2O3, are explicitly studied by thermogravimetric analysis experiments, which exhibited a similar two-stage reduction pattern. However, the distinct performances of each stage amongst these supported iron oxides indicate complex iron oxide-support interactions. Supported iron oxide at different stages are sampled and investigated by post-experimental solid characterization method. For instance, the surface area and total pore volume are determined by Brunauer-Emmett-Teller (BET) theory. This experiment illuminates the important mechanistic impacts of different supports on the iron oxide reduction by methane. Through the understanding of such interactions, the oxygen carrier can be optimized to facilitate the development of more efficient methane conversion in CLC processes.