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The direct conversion of syngas to ethanol is a promising route for the sustainable production of value-added chemicals and fuels. While Fe-promoted Rh-based catalysts have long been studied because of their notable activity and selectivity toward ethanol, the catalyst structure and the nature of Rh–Fe interaction remain poorly understood under reaction conditions, due to the intrinsic complexity of heterogeneous catalysts prepared by conventional approaches. In this work, we construct well-defined RhFe@SiO 2 model catalysts via surface organometallic chemistry, composed of small and narrowly distributed nanoparticles supported on silica. Such a RhFe@SiO 2 catalyst converts syngas into ethanol, reaching an overall ethanol selectivity of 38% among all products at 8.4% CO conversion, while the nonpromoted Rh@SiO 2 catalyst mostly yields methane (selectivity >90%) and no ethanol. Detailed in situ X-ray absorption spectroscopy and diffuse-reflectance infrared Fourier transform spectroscopy studies reveal that the RhFe@SiO 2 catalyst corresponds to an Rh–Fe alloy with ca. 3:1 Rh/Fe ratio alongside residual Fe II single sites. The alloy is stable under working conditions, promoting high activity and ethanol selectivity.
Zhou et al. (Mon,) studied this question.