Pd／Fe3O4-MCNT磁性催化剂的制备、表征及催化性能

Preparation,Characterization and Catalytic Properties of Pd/Fe_3O_4-MCNT Magnetically Recyclable Catalysts

利用多元醇法制备了单分散Fe3O4纳米粒子修饰多壁碳纳米管(MCNT)的磁性复合材料,并以X射线衍射(XRD)、透射电镜(TEM)和X射线能量色散谱(EDS)对碳纳米管磁性复合材料的结构和组成进行了表征.研究发现,通过调控Fe3O4前驱体与MCNT载体的质量比,可以很好地控制沉积的磁性纳米粒子大小.以碳纳米管磁性复合材料为载体,采用多元醇法成功制备了Pd负载量为3.0%(w)的Pd/Fe3O4-MCNT磁性催化剂.磁性质测试表明碳纳米管磁性复合材料在负载Pd前后都具有良好的超顺磁性.以肉桂醛加氢为探针反应研究了Pd/Fe3O4-MCNT的催化性能,结果表明该催化剂表现出良好的催化加氢性能,在外加磁场下催化剂能与液相反应体系高效分离,循环使用4次后,催化性能没有明显下降,显示了良好的循环利用性能.

A magnetic composite of multi-walled carbon nanotubes （MCNT） decorated with mono-dispersed Fe30, nanoparticles was prepared by a polyol method. The structure and composition of the resultant composite were characterized by X-ray diffraction （XRD）, transmission electron microscopy （TEM） and energy dispersive spectroscopy （EDS） techniques. We found that the size of the Fe3O4 nanoparticles supported on the MCNT could be easily controlled by changing the mass ratio of the Fe30, precursor to the MCNT. By a subsequent polyol process, 3% （w） Pd was loaded onto a Fe3O4-MCNT composite to form Pd/Fe3O4-MCNT magnetic catalysts. The results from magnetic measurements indicated that the prepared composites before and after Pd loading possess superparamagnetic characteristics at room temperature. The prepared Pd/Fe3O4-MCNT catalysts were evaluated by the selective hydrogenation of cinnamaldehyde as a probe reaction and it showed high activity toward the conversion of cinnamaldehyde to hydrocinnamaldehyde. Under a magnetic field, the catalyst powder was easily separated from the liquid-phase reaction system. The catalyst did not show any significant degradation after four cycles indicating the good recyclability of the prepared composite catalyst.