Effect of impregnation sequence of Ce promoter on the microstructure and performance of Ce-promoted Rh-Fe/SiO2 for the ethanol synthesis

• SiO2 supported trimetalic Rh-Fe-Ce catalysts were used for ethanol synthesis.
• Different impregnation methods were used for the catalyst preparation.
• Ce improved the ethanol selectivity of Rh-Fe/SiO2 catalyst.
• The improvement extents depended on the catalyst preparation methods.
• The Rh-Ce interface is conducive to synthesize ethanol.

Ce-promoted Rh-Fe/SiO2 catalysts were prepared using different impregnation methods and evaluated in syngas conversion to ethanol. The catalyst prepared by co-impregnation method (Rh-Fe-Ce/SiO2) showed higher ethanol selectivity than those prepared by sequential impregnation methods (Ce/Rh-Fe/SiO2 and Rh-Fe/Ce/SiO2). Characterization results indicated that when Ce was co-impregnated with Rh and Fe, it had higher dispersion and inhibited the reduction of Rh oxides. Additionally, the reduction of CeO2 was promoted. The Rh-Fe-Ce/SiO2 catalyst exhibited the highest spatial association between Rh and Ce, which was responsible for the highest ethanol selectivity.

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