In Situ Formation of FeRh Nanoalloys for Oxygenate Synthesis

Early and late transition metals are often combined as a strategy to tune the selectivity of catalysts for the conversion of syngas (CO/H₂) to C₂₊ oxygenates, such as ethanol. Here we show how the use of a highly reducible Fe₂O₃ support for Rh leads to the in situ formation of supported FeRh nanoalloy catalysts that exhibit high selectivity for ethanol synthesis. In situ characterizations by X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS) reveal the coexistence of iron oxide, iron carbide, metallic iron, and FeRh alloy phases depending on reaction conditions and Rh loading. Structural analysis coupled with catalytic testing indicates that oxygenate formation is correlated to the presence of FeRh alloys, while the iron oxide and carbide phases lead mainly to hydrocarbons. The formation of nanoalloys by in situ reduction of a metal oxide support under working conditions represents a simple approach for the preparation bimetallic catalysts with enhanced catalytic properties.