碳包铁负载纳米钯催化苯甲醇选择氧化

摘要

A magnetic separable Pd nanoparticles supported on carbon-coated iron nanocrystals (Pd/Fe@C) catalyst was prepared by an impregnation method and characterized by X-ray fluorescence spectroscopy, transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The size of the Pd nanoparticles ranged from 4 nm to 10 nm and the average size was about 7 nm. The principal component of the Pd nanoparticles was determined to be Pd° with Pd 3dsa binding energy at 335.6 eV. The as-made catalyst was applied to the selective oxidation of benzyl alcohol. The effects on the oxidation of benzyl alcohol were investigated in detail, including the amount of catalyst, the solvent, the temperature, and the catalytic activity of recycling. The results indicated that benzaldehyde could be selectively synthesized from benzyl alcohol upon catalysis by Pd/Fe@C. The conversion of benzyl alcohol was 96% and the selectivity for benzalde hyde was 95% when using 0.5% Pd/Fe@C catalyst with acetonitrile as a solvent under an oxygen atmosphere at 80℃. The catalyst can be easily separated magnetically and high catalytic activity was retained after recycling the catalyst four times.%以碳包铁纳米晶(Fe@C)为载体,采用浸渍法制备了一种磁可分离的Pd/Fe@C催化剂,并运用X射线荧光光谱、透射电镜、X射线衍射和X射线光电了能谱对催化剂进行了表征,结果表明,纳米Pd颗粒的粒径分布在4～10 nm,平均粒径约为7nm,Pd物种以Pd0为主,其Pd 3d5/2结合能为335.6 eV.将该催化剂应用于苯甲醇选择性氧化反应,考察了催化剂用量、溶剂、温度对反应的影响以及催化剂的循环使用性能.结果表明,催化剂可使苯甲醇高选择性生成苯甲醛,在催化剂用量(摩尔分数)为0.5％、乙腈为溶剂、80℃常压O2条件下,苯甲醇的氧化反应效果最佳(苯甲醇转化率为96％,苯甲醛选择性为95％).催化剂易干磁分离和回收,循环使用4次仍保持较佳的催化性能.