| Five Cu-Fe/SiO2 catalysts were prepared by deposition-precipitation, solid state impregnation, solid-state chemical reaction, citric acid combustion, ultrasound-assisted wet impregnation, and their physicochemical and catalytic properties for higher alcohols synthesis were investigated. The results showed that the Cu-Fe/SiO2 catalyst prepared by ultrasound-assisted impregnation had higher dispersion and reducibility of active metal oxides, and the largest Scu, which increased the amount of adsorbed CO and the capability for CO dissociation. As a result, the CO conversion and space time yield of total alcohols of the catalyst reached 14.04% and 104.3 g·kg-1·h-1, respectively, which were better than the other catalysts.The effects of different impregnation sequences for the precursors of iron and copper on the catalytic properties of Cu-Fe/SiO2 catalysts for higher alcohols synthesis were investigated. The means of CO-IR, XPS, CO-TPD, H2-TPR, nitrogen adsorption-desorption, XRD and N2O titration were used to characterize the physics-chemical properties of the catalysts. The result indicated that when copper was impregnated and calcined first followed by iron impregnation, it would be beneficial to the reduction of iron oxide, and the particle size of Fe2O3 was the smallest, the peak area of Fe2O3 in H2-TPR was the biggest, the intensity of CO adsorption band in CO-IR was the strongest. The CO hydrogenation result showed that the Fe/Cu/SiO2 catalyst had the biggest CO conversion and the STY of alcohols reached 126.6 g-kg-1·h-1. However, if the iron was impregnated and calcined first followed by copper impregnation, the strongest synergistic interaction of copper and iron would be obtained over Cu/Fe/SiO2 catalyat, which would improve the selectivity of C2+OH, the selectivity and the STY of total alcohols, respectively reached 36.1% and 153.3 g·kg-1·h-1, which was the best in all catalysts.MCF, SBA-15 and KIT-6 supported Cu-Fe catalysts were prepared by co-impregnation method, and their catalytic properties for higher alcohols synthesis were investigated by CO hydrogenation. The means of CO-IR, XPS, CO-TPD, H2-TPR, nitrogen adsorption-desorption, XRD and N2O titration were used to characterize the physics-chemical properties of the catalysts. The results indicated that Cu-Fe catalyst supported on MCF has the smallest size of CuO, the biggest peak areas of active metal oxides in H2-TPR, the most intensity of CO adsorption. As a result, the Cu-Fe/MCF catalyst showed the higest CO conversion and STY of alcohols being of 19.8% and 161.0 g·kg-1·h-1, respectively. |
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