钠对苯甲醛加氢合成苯甲醇催化剂Cu/SiO_2的修饰作用影响活性

Effect of Sodium Modifier on Activity of Cu/SiO_2 Catalysts for Hydrogenation of Benzaldehyde

采用浸渍法引入不同含量的钠元素对Cu/SiO2催化剂进行了改性,并对苯甲醛加氢合成无氯苯甲醇反应进行了研究.XRD,H2-TPR,BET,IR等表征分析结果表明:经钠元素修饰后的催化剂并没有改变CuO的晶相结构,但增强了活性组分和载体间的相互作用,使CuO的还原温度得到提高;催化剂表面的酸量和酸强度随钠元素修饰量的增加而显著降低;钠的最佳负载量为1.0%(w),Na-Cu/SiO2催化剂能够有效抑制副产物甲苯的生成,显著地提高产物苯甲醇的高温选择性.

Cu/SiO2 catalysts were modified by the sodium by impregnation method, catalytic activity for hydrogenation of benzaldehyde to non-chloride benzyl alcohol was investigated in a continuous flow fixed-bed reactor under atmospheric pressure. It was found that the selectivity of benzyl alcohol was significantly enhanced over sodium modified Cu/SiO2 catalysts. The optimum loading amount of sodium on Cu-based catalysts is about w= 1.0%. The Na-CuO/SiO2 catalysts were characterized by XRD, H2-TPR, BET and FT-IR, the results revealed that reducing temperature of CuO was increased after modification by sodium. Meanwhile, the sodium species reduced the intensity and amounts of the acidic centers on catalytic surface, which effectively inhibited the formation of toluene at higher temperature.