Exploration And Research On The Technology Of Ammonia Synthesis At Ambient Temperature And Pressure

Ammonia synthesis industry is one of the pillar type industries of China’s chemical industry,which plays a very important role in the national economy.In view of the high fossil energy consumption and high pollution emission of the existing Haber Bosch（H-B）ammonia synthesis process,it is urgent to develop an alternative and sustainable method,which can utilize renewable resources instead of fossil fuels to reduce N₂ to NH₃ under mild conditions.In this paper,the synthesis of ammonia at room temperature and atmospheric pressure was carried out by the catalytic and electrochemical methods of nitrogenase like compounds,The main works completed are as follows:The first chapter is a brief introduction of synthetic ammonia,including industrial synthetic ammonia and normal temperature atmospheric pressure synthetic ammonia;it also introduces the development process of synthetic ammonia,including the development of industrial synthetic ammonia and the progress of normal temperature atmospheric pressure synthetic ammonia;it discusses the mechanism of synthetic ammonia,etc.The second chapter is the research on the synthesis of ammonia by nitrogenase like compounds at room temperature and atmospheric pressure.Tetrahydrofuran solution with bis（trimethylsilyl）amino lithium and anhydrous FeCl₂ reaction,the catalyst was synthesized at low temperature.It includes scanning electron microscopy（SEM）to examine the microstructure,transmission electron microscopy（TEM）to characterize the specific morphological characteristics,X-ray diffraction（XRD）to analyze the crystal structure of the catalyst,and X-ray photoelectron spectroscopy（XPS）to characterize the specific valence characteristics of the prepared catalyst active species,at the same time,the selection of Proton source,the experiment of solvent effect and the comparison of catalytic reaction time are done.In order to better the application prospect of catalyst,the experiment of catalyst loading and the experiment of catalyst stability are done.The results show that the supported Fe-N catalyst withα-Al₂O₃ is stable and has the best catalytic efficiency.In the third chapter,the work of catalytic synthesis of ammonia at room temperature and atmospheric pressure by electrochemistry with aqueous solution as electrolyte is introduced.Nanometer iron was prepared by electrodeposition as working electrode and water-soluble electrolyte as electrolyte.Ammonia was synthesized by cyclic voltammetry.The electrode materials were characterized by SEM,TEM,HRTEM,XRD,XPS,etc.and various electrochemical tests were also carried out,such as the characterization of cyclic voltammetry characteristic curve,constant voltage characterization,electrochemical impedance characterization of different voltages,etc.In order to explore the mechanism of this work,DFT（density functional theory）is calculated.The results show that the method of cyclic voltammetric electrodeposition is the best for the synthesis of NH₃ by electrocatalytic reduction of N₂ in potassium phosphate electrolyte.The highest ammonia production rate is 79×10^-11mol·S^-1·cm^-2,and the corresponding Faraday efficiency is 16.68%.The ammonia production rate and Faraday efficiency are higher than most other aqueous systems.The fourth chapter summarizes the work of this paper and looks forward to the possible problems and challenges in the future.