Flower-Like Co-Ni/C Bimetallic Catalysts for the Selective Hydrogenation of o-Chloronitrobenzene

Abstract

Three dimensional flower-like Co-Ni/C bimetallic catalysts composed of interlaced carbon flakes with highly dispersed metal nanoparticles were synthesized by a facile hydrothermal/solvothermal process followed by a heat treatment in flowing N 2 . The sizes of the metal nanoparticles were from 26 to 4 nm, which became smaller as the Co/Ni molar ratio increased. The catalytic activities for the selective hydrogenation of o -chloronitrobenzene to o -chloroaniline were tested. The conversion of o -chloronitrobenzene over the bimetallic Co-Ni/C catalysts was increased by up to 200% compared with that over a mono-metallic Co/C catalyst, which was due to a synergistic interaction between the Co and Ni species. Hydrogen temperature-programmed desorption results showed that new active sites were formed in the Co 50 Ni 50 /C catalyst due to the formation of a Co-Ni alloy, which gave the improved activity of the Co 50 Ni 50 /C catalyst. 采用简单的水热/溶剂热法, 经后续在氮气气氛中的热处理合成了三维花型 Co-Ni/C 双金属催化剂, 它由交织炭片构成, 金属纳米颗粒高度分散其中. 随着 Co/Ni 摩尔比的增加, 金属颗粒的粒径逐渐从 26 nm 减至 4 nm 左右. 将该催化剂用于邻氯硝基苯选择性加氢制备邻氯苯胺反应, 其催化活性最高为单金属催化活性的 2 倍. 这是由于 Co 和 Ni 物种之间存在协同效应. 氢气程序升温脱附结果显示, Co/Ni 合金的生成使得 Co 50 Ni 50 /C 催化剂产生了新的催化活性位, 因而其活性显著提高. Three dimensional flower-like Co-Ni/C catalysts composed of interlaced nanoflakes with highly dispersed metal nanoparticles gave better activity for the selective hydrogenation of o -chloronitrobenzene because of a synergistic interaction between Co and Ni.