Abstract: The influences of zinc and manganese promoters on the structure and reaction behavior of CuFe catalyst for higher alcohol synthesis were investigated by N2 adsorption, X-ray diffraction (XRD), H2 temperature-programmed reduction (H2-TPR), in situ diffuse reflectance infrared spectroscopy (DRIFT) and CO+H2 reaction. It was found that the zinc additive suppressed the dispersion of active phases but improved their activation ability towards CO molecule due to the formation of a new spinel phase, ZnFe2O4. The presence of manganese showed a more favorable effect on the dispersion of active phases and then promoted the synergistic effect between copper and iron although the adsorption tendency towards CO declined due to the dilution effect of manganese. Compared with binary CuFe catalyst, CuZnFe catalyst had a higher activity with the decreasing of C2+OH selectivity, and CuFeMn catalyst showed improved total alcohol selectivity although both CO conversion and C2+OH selectivity decreased. The results of the doubly promoted CuFe catalyst evidently indicated the existence of synergistic effect between zinc and manganese, which modified the texture parameters, decreased the reduction temperature of Cu and altered the reduction behavior of Fe. More importantly, the abundance of CO adsorption on the CuFe catalyst was greatly increased due to the co-addition of zinc and manganese. Therefore, the overall catalytic performance of doubly promoted CuFe catalyst was superior to that of the single promoted CuFe catalyst.

Key words: Higher alcohol synthesis, CuFe catalyst, Zinc promoter, Manganese promoter, Synergistic effect