Preparation of SiO₂-coated CuFe catalysts for synthesis of higher alcohols from CO hydrogenation

A series of SiO₂-coated CuFe (SiO₂@CuFe) catalysts with different Cu/Fe molar ratios were prepared by co-reduction and in situ coating method.The physicochemical properties of the catalysts were characterized with XRD, TEM, SEM-EDS, XPS and H₂-TPR techniques and N₂ sorption experiment.It was shown that well-dispersed CuFe nanoparticles were completely coated by mesoporous silica in the as-prepared catalysts.The content of Cu-Fe composite oxide in the catalyst and the selectivity of total alcohols and C₂⁺ alcohols both exhibit a volcano trend with the decrease of Cu/Fe molar ratios.When the Cu/Fe molar ratio was 1, the largest amount of CuFe₂O₄ was formed, consequently, causing the strongest interaction between Cu and Fe.In addition, the obtained catalyst possessed higher BET surface area and larger BJH pore volume than the other samples.Thus, alcohol products easily diffuse into/out of its pores, thus avoiding the further hydrogenation to hydrocarbons.As a result, it shows the highest selectivity to total alcohols and C₂⁺ alcohols.