Development of MgAl2O4-stabilized, Cu-doped, Fe2O3-based oxygen carriers for thermochemical water-splitting

Abstract

The commercially dominating technology for hydrogen production (i.e. steam methane reforming) emits large quantities of CO₂ into the atmosphere. On the other hand, emerging thermochemical water splitting cycles allow the production of a pure stream of H₂ while simultaneously capturing CO₂. From a thermodynamic point of view, the Fe₂O₃–Fe couple is arguably the most attractive candidate for thermochemical water splitting owing to its high H₂ yield and H₂ equilibrium partial pressure. However, the low reactivity of Fe₂O₃ with methane and the high activity of Fe for methane decomposition (leading to carbon deposition and in turn CO_x poisoning of the H₂ stream) are major drawbacks. Here, we report the development of MgAl₂O₄-stabilized, Cu-modified, Fe₂O₃-based redox materials for thermochemical water-splitting that show a high reactivity towards CH₄ and low rates of carbon deposition. To elucidate the effect of Cu doping on reducing significantly the rate of carbon deposition (while not affecting negatively the high redox activity of the material) extended X-ray absorption fine structure spectroscopy and energy dispersive X-ray spectroscopy was employed.