镁铝水滑石固载重铬酸钾及其氧化性能

IMMOBILIZATION OF POTASSIUM DICHROMATE USING Mg-Al HYDROTALCITE AND ITS OXIDATIVE PERFORMANCE

采用共沉淀法制备K2Cr2O7改性Mg-Al水滑石催化剂HT-Cr2O72-,以分子氧为氧化剂.以2-吡啶甲醇的氧化反应为模型,探讨了温度、溶剂、投料比等条件对反应的影响,结果表明,该催化剂可以在温和的条件下实现醇类化合物的高选择性氧化转化.XRD表征给出水滑石经过Cr2O27-阴离子交换以后,X射线衍射峰中最强峰对应晶面的平均粒径减小,但结构仍然完整;XPS表征表明,HT-Cr2O72-中Cr的结合能较K2Cr2O7中Cr的结合能有所降低,是HT-Cr2O72-中Cr的氧化性较Cr2O72-中的Cr有所下降的原因.

Mg-Al hydrotalcite-supported Cr2O7^2-catalysts （abbreviated as HT-Cr2O7^2-） were prepared by coprecipitation method and subjected to liquid-phase oxidation of alcohols in the presence of molecular oxygen under mild conditions. Oxidation of 2-pyridinemethanol as the model reaction was investigated, the influence of reaction conditions including reaction temperature, solvent and materials ratio on the oxidative performance has been studied. Several solvents such as, toluene, benzene and cyclohexane, and elevated reaction tempera- ture favored the reaction. XRD characterization presented the unchanged structure despite the exchange of hydrotalcite with Cr2O7^2- anion; however after hydrotalcite was exchanged with Cr2O7^2- anion, the average particle size decreased according to the broadening of the most intense peak. In comparison with Cr in potassium dichromate, binding energy of Cr in HT-Cr2O7^2- obtained from XPS characterization decreased, indicating the decrease of the oxidative performance.