Design And Preparation Of A Hydrogenation-catalyzed P-nitrophenol Catalyst

As an important chemical intermediate,aminophenol?AP?is widely utilized to manufacture many chemical products,such as analgesic and antipyretic drugs,photographic developer and dyeing agent.Among the present AP synthetic routes,hydrogenating the corresponding nitrophenol?NP?is considered as the most convenient and efficient method with low energy consumption.Between these reaction,hydrogenation of 4-nitrophenol?4-NP?to 4-aminophenol?4-AP?is an important representative reaction.However,the excessive cost and scarcity of noble metal catalysts make it very vital to maximize its catalytic activity.In order to improve the utilization of noble metal catalysts,this paper prepared two kinds of supported noble metal catalysts and their catalytic performance in the reaction was studied:1.Here,we firstly synthesize a Fe₂O₃@C composite with shell/core structure via a low-temperature hydrothermal reaction.Though subsequent adsorption and calcination process of different temperature,many Pt nanoparticles are formed and supported on the surface of the microspheres to finally fabricating the magnetic Fe₂O₃@C-Pt-T catalyst.Through systematic characterization and experimental analysis,it is found that the calcination temperature has great influence on the morphology,structure and catalytic performance of the catalyst.The Fe₂O₃@C-Pt-600 catalyst has the best performance,which was calcination at 600 ?,it can fully converts the substrate in 6 min under the ambient condition.Due to the unique magnetic property derived from the ?-Fe₂O₃ core,the Fe₂O₃@C-Pt particles can be easily separated from the reaction solution using a magnet.On the other hand,the abundant oxygen-containing groups on the surface of biomass-based hydrothermal carbon endow the HTC a good adsorption to metal cations in aqueous solution,which is the shell of the catalyst.The loaded Pt particles on the surface is the catalytic activity center of the catalyst,which not only saves the amount of noble metals,but also improves the catalytic performance of the catalyst.As a result,the Fe₂O₃@C-Pt catalyst shows the great hydrogenation catalytic performance,and could maintain this good property for ten runs after magnetically recovered.2.ZnO nano materials with perfect rod structure were synthesized by low temperature hydrothermal method,which are the carrier system.Based on the photo-response property of ZnO,a supported PtO₂/ZnO catalyst with small size,highdispersion was prepared under the UV-light irradiation in this work.To analyze the influence of UV-light illumination time on the catalytic activity of the PtO₂/ZnO-T catalyst,the various samples with different illumination times are investigated under the indicate reaction situations.Through systematic characterization and experimental analysis,it is found that the illumination time has great influence on the catalytic performance of the catalyst,and the catalytic performance of the PtO₂/ZnO-₃0 catalyst obtained under the optimized conditions?irradiated for ₃0 min?has the best catalytic activity.And the PtO₂/ZnO-₃0 catalyst obtained through the UV-induced in-situ route demonstrated a better catalytic activity in hydrogenation than that of the corresponding Pt/ZnO catalyst and the PtO₂ catalyst which was prepared via the traditional wet-oxidation method.Furthermore,the PtO₂/ZnO-₃0 catalyst was not observed obvious change after ten runs of reaction,which indicated a high stability of the catalyst.As a result,the as-obtained PtO₂/ZnO-₃0 catalyst is expected to exhibit the good practical application in the industrial productions.