Pd亚纳米簇@SiO2催化芳香硝基化合物加氢制芳胺

Subnano-Pd@SiO2 nanospheres for catalyzing hydrogenation of aromatic nitro compounds to arylamines

摘要:

以新配制的硝酸钯溶液为原料，在十六烷基三甲基溴化铵/正丁醇/环己烷形成的反相微乳液体系中采用一锅法制备Pd亚纳米簇@SiO2核壳材料，得到质量分数达4%（以SiO2的质量计）、平均粒径为0.7 nm的Pd亚纳米簇。采用TEM、XRD、XPS、N2吸附-脱附对材料的物化性质进行了表征，探讨了其对芳香硝基化合物加氢制芳胺反应的催化性能。结果表明，在温和的反应条件下（50 ℃、1.0 MPa H2），催化剂Pd亚纳米簇@SiO2上硝基苯加氢反应4 h，苯胺的收率高达99.5%。在该催化剂上，其他多种芳硝基化合物加氢反应同样获得了较高的芳胺收率（98.5%~100%）。催化剂Pd亚纳米簇@SiO2循环4次后，活性无明显下降。

Abstract:

Subnano-Pd@SiO2 core shell materials were prepared by a one-pot method in a microemulsion made up of cetyltrimethyl ammonium bromide/n-butanol/cyclohexane with newly prepared Pd(NO3)2 solution as raw material. Pd subnanoclusters with an average size of 0.7 nm are uniformly dispersed in the entire SiO2 nanospheres with a high loading amount of 4% on the basis of the mass of SiO2. The physico-chemical properties of the Subnano-Pd@SiO2 were characterized by TEM, XRD, XPS, and N2 adsorption-desorption. The catalytic performances of Subnano-Pd@SiO2 for the hydrogenation reaction of aromatic nitro compounds were investigated. The results showed a 99.5% yield of aniline was achieved through the hydrogenation of nitrobenzene under mild reaction conditions of 50 ℃ and 1.0 MPa H2 for 4 h. Meanwhile, Subnano-Pd@SiO2 was efficient for the hydrogenation of various aromatic nitro compounds to give high yields (98.5%~100%) of arylamines. The activity of Subnano-Pd@SiO2 did not decrease significantly even after being recycled for 4 times.