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

Abstract Ce-promoted Rh-Fe/SiO 2 catalysts were prepared using different impregnation methods and evaluated in syngas conversion to ethanol. The catalyst prepared by co-impregnation method (Rh-Fe-Ce/SiO 2 ) showed higher ethanol selectivity than those prepared by sequential impregnation methods (Ce/Rh-Fe/SiO 2 and Rh-Fe/Ce/SiO 2 ). 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 CeO 2 was promoted. The Rh-Fe-Ce/SiO 2 catalyst exhibited the highest spatial association between Rh and Ce, which was responsible for the highest ethanol selectivity.