Pd亚纳米簇@SiO_(2)催化芳香硝基化合物加氢制芳胺

Subnano-Pd@SiO_(2)nanospheres for catalyzing hydrogenation of aromatic nitro compounds to arylamines

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@SiO_(2)核壳材料,其中Pd质量分数为4%(以催化剂总质量计)、平均粒径为0.7 nm。采用TEM、XRD、XPS、N_(2)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 H_(2)),催化剂Pd亚纳米簇@SiO_(2)上硝基苯加氢反应4 h,苯胺的产率高达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%~100.0%)。催化剂Pd亚纳米簇@SiO_(2)循环使用4次后,活性无明显下降。

Subnano-Pd@SiO_(2)core shell materials,with a high loading amount of 4%(based on the mass of catalyst)and an average particle size of 0.7 nm,were prepared by one-pot method in an reverse microemulsion system made up of cetyltrimethyl ammonium bromide/n-butanol/cyclohexane with newly prepared Pd(NO_(3))_(2)solution as raw material.The physio-chemical properties of the subnano-Pd@SiO_(2)obtained were then analyzed by TEM,XRD,XPS and N_(2)adsorption-desorption,followed by investigation on its catalytic performances on the hydrogenation reaction of aromatic nitro compounds.The results showed a aniline with a yield of 99.5%was obtained through the hydrogenation of nitrobenzene in presence of subnano-Pd@SiO_(2)under mild reaction conditions of 50℃and 1.0 MPa H_(2)for 4 h.Meanwhile subnano-Pd@SiO_(2)was also efficient in catalyzing hydrogenation of various aromatic nitro compounds to arylamines with high yields(98.5%~100.0%).The activity of subnano-Pd@SiO_(2)did not show significant decrease even after being recycled for 4 times.