Enhancement of Fe/Ce oxygen carrier performance in chemical looping dry reforming of methane

Chemical looping dry reforming of methane (CL-DRM) is a promising technology for production of syngas and the utilization of greenhouse gases, which highly relies on efficient oxygen carrier (OC) to facilitate the energy and material transfer. In this work, Fe2O3/CeO2 oxygen carriers in physical and crystalline contact modes were synthesized and used for CL-DRM. The Fe2O3/CeO2 crystal interface significantly promoted the oxygen release of both Fe2O3 and CeO2. The completely reduced iron elements dispersed uniformly into the CeO2 support and formed pure CeFeO3 in the oxidation step. CeFeO3 showed enhanced methane conversion rate (81.3 %), CO selectivity (96.6 %) and lower temperature sensitivity. The time-resolved reaction performance of Fe-Ce oxygen carriers was investigated to understand the relationship between the oxygen vacancy concentration and reactivity of Fe-Ce oxygen carrier. With the increasing concentration of oxygen vacancies, the oxygen carrier exhibited elevated activity and enhanced selectivity. The redox range of CL-DRM was then tuned to enhance the reaction conversion and product purity. In the deep reduction range of oxygen carrier, the deposited carbon also served as the active redox intermediate for chemical looping and enhanced both the reaction conversion rate and the product purity to nearly 100 %. These findings showcased rational methods for design and utilization of iron-based oxygen carriers and expanded the potential for chemical looping applications.