纳米γ-Al_(2)O_(3)负载Ag催化剂催化对硝基酚加氢合成对氨基酚

STUDY ON THE SYNTHESIS OF p-AMINOPHENOL THROUGH CATALYZED HYDROGENATION OF p-NITROPHENOL BY NANOSIZEDγ-Al_(2)O_(3)-SUPPORTED Ag

采用湿化学还原法制备了纳米γ-Al_(2)O_(3)负载纳米Ag(Ag/γ-Al_(2)O_(3))催化剂。X射线衍射(XRD)、X射线光电子能谱(XPS)和透射电子显微镜(TEM)表征表明,纳米Ag颗粒很好的分散在载体γ-Al_(2)O_(3)上,纳米金属Ag颗粒平均粒径介于0.8~1.6 nm之间。在氢气压力1.0 MPa、反应温度150℃反应条件下,5.0%Ag/γ-Al_(2)O_(3)催化对硝基酚加氢完全转化时,对氨基酚选择性为100%。以5.0%Ag/γ-Al_(2)O_(3)催化剂为模型催化剂,采用经验幂函数型反应动力学方程拟合的活化能为26.87 kJ/mol, Ag/γ-Al_(2)O_(3)纳米催化剂具有良好的催化对硝基酚加氢制备对氨基酚活性。

Nanosizedγ-Al_(2)O_(3)-supported Ag nanoparticle(Ag/γ-Al_(2)O_(3))catalysts were prepared by the wet chemical reduction method.The characterization by X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),and transmission electron microscopy(TEM)showes that Ag nanoparticles are well dispersed on theγ-Al_(2)O_(3) support and the average particle sizes of metallic Ag nanoparticles range from 0.8 to 1.6 nm.The selectivity for p-aminophenol is 100%when p-nitrophenol is completely converted by the catalytic hydrogenation on a 5%Ag/γ-Al_(2)O_(3) catalyst under mild reaction conditions of 1.0 MPa of H 2 and reaction temperature of 150℃.With 5.0%Ag/γ-Al_(2)O_(3) as the model catalyst,the activation energy of the catalyst was fitted using an empirical power function reaction kinetics equation to be 26.87 kJ/mol,indicating that Ag/γ-Al_(2)O_(3) nanosized catalyst exhibits excellent catalytic activity for the hydrogenation of p-nitrophenol to p-aminophenol.