钴镁铝类水滑石液相选择性催化苯甲醇氧化合成苯甲醛

采用共沉淀法制备了不同Co₂AlMg_x(x=0.5、1、1.5和2)原子比的类水滑石,用X射线粉末衍射(XRD)、扫描电子显微镜(SEM)、傅里叶变换红外光谱(FT-IR)、表面孔吸附(BET)及电感耦合等离子光谱(ICP)等技术手段表征了催化剂的结构、组成和比表面积,并考察了其催化苯甲醇选择氧化制苯甲醛的性能。 结果表明,随着Mg含量的增加,催化剂的碱性增强,苯甲醛的选择性提高。 在优化条件:苯甲醇0.02 mol,催化剂Co₂AlMg₁类水滑石100 mg,过氧化氢叔丁醇0.04 mol,溶剂乙腈8 mL,反应温度60 ℃,反应时间9 h下,苯甲醇的转化率为39.5%,苯甲醛的选择性达到89.2%。 催化剂重复使用5次后其活性与选择性未见明显降低,表明催化剂具有较好的稳定性。

Selective Oxidation of Benzyl Alcohol to Benzaldehyde Catalyzed by Co2/Al/Mgx Hydrotalcite-like Materials in Liquid Phase

Co₂/Al/Mg_x layered double hydroxides(LDHs) with different Co₂/Al/Mg_x ratios(x=0.5, 1, 1.5 and 2) were prepared and characterized by XRD, SEM, FT-IR, BET and ICP techniques. These catalysts were studied for selective oxidation of benzyl alcohol to benzaldehyde. The results indicate that the selectivity of benzaldehyde increases with increasing of Mg content. Under the optimized condition: 0.02 mol of benzyl alcohol, 100 mg of Co₂AlMg₁-LDH, 0.04 mol of tert-butyl hydroperoxide, 8 mL of acetonitrile, reaction temperature 60 ℃ and reaction time 9 h, the conversion of benzyl alcohol is 39.5% and the selectivity of benzaldehyde reaches 89.2%. The catalysts are reused 5 times without obvious loss of the catalytic activity and selectivity.