Precursor-Route Synthesis Of Co(Ni)-Based Catalyst And Its Catalytic Performance For Reduction Of P-nitrophenol

In recent years,rapid industrialization is considered to be one of the main causes of environmental problems,especially the sharp increase in water pollution.The chemical substances added to the groundwater reservoir in various industries are causing serious health diseases to humans.Among organic pollutants,nitrophenol compounds have become one of the main known pollutants causing water pollution due to their high solubility and stability in aqueous media.In contrast,the aminophenol from reduction of nitrophenol have increase value and can be easily decomposed.Therefore,the conversion of nitro-compounds into corresponding amino-compounds is of great significance.Traditional precious metal-based catalytic materials face the problems of high cost and limited reserves.The development of inexpensive catalysts is pursued.It should also be easy separated from reaction system.The late transition metals nickel(cobalt)are close to precious metals in the periodic table.They have the advantages of being cheap and easily available.Their metal state and nitrides are potential non-precious metal catalysts.This thesis is devoted to the development of the method for controlling the microstructure of cobalt(nickel)-based materials,and to improve their stability and activity in the hydrogenation of nitro compounds.The cobalt(nickel)nitride supported on silicon dioxide and one-dimensional carbon were prepared by rationally designing precursors containing cobalt(nickel).The main content of the paper is as follows:1)Silica has good stability and environmental friendliness,making it a good carrier material.However,the general synthesis needs to firstly synthesize a metal catalyst or a silica support inadvance,and then combine the second component with the first component.The routes are complex and not conducive to mass production.Based on the characteristics of 3-aminopropyltriethoxysilane(KH550)with both-NH2 coordination site and Si component,KH550 and Co2+are coordinated in ethanol to obtain a blue KH550-Co complex.After heating treatment in a NH3 atmosphere,the blue solid turns into a black powder.TEM,XRD and other tests showed the loading of Co4N particles on SiO2 were formed.The SiO2 protection helps the stabilization and separation in use.The results show that Co4N@SiO2 can be used as a good catalyst for the reduction of nitro groups,and can quickly catalyze the conversion of p-nitrophenol to p-aminophenol at room temperature.At the same time,the magnetic properties of Co4N@SiO2 can facilitate the separation of the catalyst by an external magnet,and there is no obvious change in performance after multiple cycles of use.2)Carbon and silicon are in the same main group and are good carrier materials.At the same time,there are many kinds of carbon-containing ligands,which is more conducive to the adjustment of product structure.Dimethylglyoxime(DMG)is widely used as an analytical reagent for the detection of Ni2+,which can coordinate with Ni2+to form a red precipitation of Ni(DMG)2.We found that the adding of surfactant molecules into the system can adjust the final morphology of Ni(DMG)2.Adding polyvinylpyrrolidone molecule can promote the formation of tubular Ni(DMG)2.At the same time,the type of surfactant also has a significant effect on the formation of the tubular structure.One-dimensional Ni3N/Carbon can be obtained by heating treatment of Ni(DMG)2 precursor in NH3.This kind of hollow structure has good application potential in catalysis.