Study On The Catalytic Performance Of Nickel-based Catalysts For Reductive Coupling Of Nitro Compounds To Imine Compounds

With the development and progress of society,the demand of imine in practical production is increasing.How to efficiently produce imine under low energy consumption and low investment invest has always been the focus of scientific research.The traditional method to synthesize imines is to reduce nitro compounds into amines,and then condense with carbonyl compounds.The traditional catalysts for catalytic reduction of nitro compounds mainly have some defects,such as difficult separation,high cost and poor selectivity.Therefore,the design and development of highly efficient catalysts for the reduction of nitro compounds is the research focus.In this paper,Ni based nanoparticles were loaded on different oxides to prepare catalysts containing nitrogen-doped carbon materials,and the effect of metal nanoparticles on the reduction of nitro compounds was studied.1.Using chitosan,dicyandiamide,magnesium nitrate hexahydrate and nickel nitrate hexahydrate as clean materials of renewable biomass,Ni/CN-Mg O-T was prepared by simple physical mixing and calcination at high temperature in N₂.The catalytic performance of Ni/CN-Mg O-T for hydrogenation of nitro compounds and coupling reaction with carbonyl compounds was studied.It was found that different calcination temperature has a significant effect on the performance of the catalyst.When the calcination temperature is 600℃,t h e ca t al y t i c p er fo r m a nc e i s t h e b e st.The conversion of nitrobenzene was 97.3%and the yield of imine was 92.8%at 80℃for 12 h.Under the optimal experimental conditions,the yields of imines with different substituents were 84.2-92.1%,showing good catalytic activity and product selectivity.2.A nickel based catalyst（Ni/LCN-Al₂O₃-T）with ordered distribution of nickel on the surface of alumina was prepared.One pot catalyzed hydrogen transfer reduction coupling of nitro compounds with alcohols to imines.It was found that the addition of o-phenylenediamine could uniformly disperse the nickel nanoparticles on the surface of alumina support.Under the synergistic effect of nickel and alumina,the coupling of nitro compounds with alcohol by hydrogen transfer reaction could be efficiently catalyzed.Under the optimal conditions,the conversion of nitrobenzene is more than99%,and the selectivity of imine is more than 99%.There is no outer hydrogen source in the whole process,and the atomic utilization rate reaches 100%.