Ce–Fe oxygen carriers for chemical-looping steam methane reforming

Chemical-looping steam methane reforming (CL-SMR) is a novel process for the co-production of pure hydrogen and syngas (synthesis gas) without purification processes. Ce1−xFexO2−δ oxides (x = 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 1) prepared by chemical precipitation were characterized by X-ray powder diffraction, BET, Raman spectra, temperature-programmed reduction technologies and used as oxygen carrier for the CL-SMR process. The methane conversion/water splitting redox properties of samples were evaluated at the different temperatures (800, 850, and 900 °C). With the combination of CeO2 and Fe2O3, Fe2O3 particles were well dispersed on ceria surface and a small amount of iron ions was incorporated into the CeO2 lattice to form a Ce–Fe–O solid solution. It was found that reducibility of CeO2 was enhanced by the added Fe2O3. These results therefore led to the conclusion of the strong Ce–Fe interaction in CeO2–Fe2O3 mixed oxides. As a result, the redox activity of CL-SMR was significantly improved, and increased in desired product yield. The redox performance was also affected by the redox temperatures, and the desired product yield was obviously enhanced at the higher temperatures. It was found that Ce0.5Fe0.5O2−δ oxygen carrier showed the highest performance for the co-production of syngas and hydrogen.

► Ce0.5Fe0.5O2−δ exhibited high performance in chemical steam methane reforming.
► Chemical interaction in Ce–Fe mixed oxides enhanced its redox property.
► Ce–Fe mixed oxides showed good activity for selective oxidation of methane.