Effect of Fe impregnation sequence on ethanol synthesis from syngas over Mn and Fe promoted Rh/γ-Al2O3

Fe promoted Rh-Mn/Al2O3 catalysts with different Fe impregnation sequences were used for ethanol formation from syngas. The effect of Fe impregnation sequence on the structure and performance of the catalysts was investigated by means of N-2 adsorption, CO adsorption, H-2-TPR, H-2-TPD, CO-TPD, XPS and DRIFTS. The results showed that the RhMnFe/Al2O3 catalyst prepared by co-impregnation method showed higher ethanol selectivity than those prepared by sequential impregnation methods. Characterization results indicated that the RhMnFe/Al2O3 catalyst exhibited moderate CO hydrogenation and dissociation ability, stronger CO insertion ability and synergistic effect, which was responsible for its higher ethanol selectivity.