Iron oxides with gadolinium-doped cerium oxides as active supports for chemical looping hydrogen production

Supporting materials are often employed to enhance the stability of iron oxides oxygen carriers, but the reactivity is compromised for the dilution of the active phase. Here, we report several iron oxides supported by ionic conducting gadolinium-doped cerium oxides (GDC) for efficient chemical looping hydrogen production. The results show that GDC support can simultaneously improve redox stability and activity. Specifically, the produced Fe₂O₃/Gd_0.3Ce_0.7O_3−δ exhibits a high hydrogen production rate of ~0.71 mmol·g⁻¹·min⁻¹ and hydrogen yield of ~10 mmol·g⁻¹ with negligible decay through 20 redox cycle. When using methane as the reducing agent, Fe₂O₃/Gd_0.3Ce_0.7O_3−δ shows high methane conversion of 75.67% and much lower carbon deposition than Fe₂O₃. The high performance is attributed to the improved oxide ion-conductivity through the oxygen carrier, which is further verified as the ability of the GDC support to accelerate the oxygen diffusion in the bulk. The explored support effects in this work can be extended to design oxygen carrier materials with both high activity and stability.