Mg改性NiGa类水滑石催化分子氧选择氧化醇制醛的性能

Selective Oxidation of Alcohol to Aldehyde Catalyzed by Mg Modified NiGa Hydrotalcite-like Compounds

摘要:

采用共沉淀法制备了系列Mg改性的NiGa类水滑石催化剂（Ni2MgxGa-LDHs，x=0、1 和 2），采用XRD、SEM、FTIR、ICP及Hammet指示剂等方法分析催化剂的结构、组成及表面碱含量，考察了Ni2MgxGa-LDHs在催化氧气选择性氧化醇制醛反应中的性能。结果表明：Mg的引入可以有效提高催化剂的表面碱性及其催化醇的选择性氧化性能，在苯甲醇1 mmol、均三甲苯5 mL、Ni2Mg2Ga-LDH 0.5 g、反应温度120 ℃、O2流量10 mL/min的条件下反应4 h，苯甲醇的转化率和苯甲醛的选择性均达到99%以上。此催化体系具有较好的底物适用性。催化剂重复使用4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.

Abstract:

A series of Mg modified NiGa hydrotalcite-like compounds (Ni2MgxGa-LDHs，x=0, 1 and 2) have been prepared by coprecipitation method, and the structure, composition and the amount of surface basic site were characterized by XRD, SEM, FTIR, ICP and Hammet indicators method. These catalysts were then studied in the selective oxidation of alcohol to aldehyde using molecular oxygen as the oxidant. The results indicated that introduction of Mg could efficiently improve the surface basicity and the catalytic activity in the selective oxidation of alcohol. Under the selected conditions (benzyl alcohol 1 mmol, me-sitylene 5 mL, Ni2Mg2Ga-LDH 0.5 g, 120 ℃, O2 10 mL/min, 4 h), the conversion of benzyl alcohol and the selectivity of benzaldehyde reached above 99%. The catalytic system could tolerate various substrates. The catalysts could be recycled 4 times without obvious loss of the catalytic activity, indicating its high stability.