CuFe@SiO2催化剂的制备及其在CO加氢合成低碳醇中的应用

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

    摘要
  • 摘要: 采用共还原-原位包覆法制备一系列SiO2包覆铜铁双金属纳米颗粒的催化剂 (CuFe@SiO2), 借助N2物理吸附、XRD、TEM、SEM-EDS、XPS和H2-TPR等手段对不同Cu/Fe物质的量比的CuFe@SiO2催化剂的物理化学性质进行了表征, 并考察了催化剂在CO加氢合成低碳醇中的催化反应性能。结果表明, 所制得的催化剂均为孔分布处于介孔范围的SiO2包覆的铜铁纳米颗粒。随着Cu/Fe物质的量比降低, 铜铁以复合氧化物存在的比例、总醇及C2+OH选择性先增大后减小。其中, 总醇及C2+OH选择性在Cu/Fe物质的量比为1时达到最大, 这是由于此时催化剂存在较多的CuFe2O4复合氧化物, 铜铁协同作用较强, 同时催化剂也呈现较大的比表面积及孔容, 有利于所生成的醇更快扩散至催化剂表面而避免二次加氢生产烃类。

     

    Abstract: 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.

     

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