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Basic Research And Thermodynamic Of Relative Solution For Direct Electrosynthesis Process Of P-Aminophenol

Posted on:2007-04-28Degree:DoctorType:Dissertation
Country:ChinaCandidate:J H ZhaoFull Text:PDF
GTID:1101360185472208Subject:Chemical processes
Abstract/Summary:PDF Full Text Request
p-Aminophenol(PAP) is an important medicine, rubber and dye intermediate with wide uses and optimum application prospects. With the development of medicine, rubber and dye industry, the need for p-aminophenol was yearly increased both in China and abroad, however the supply is insufficient. The technology of direct electrochemical synthesis of PAP is characterized by mild reaction conditions, high product purity and reduced waste, and is called as "Green Technology". So the studies to fluid phase equilibria, volumetric and viscosity properties, the analysis method, the electro-catalytic activity and selectivity of cathode materials, the design and flow characteristic of reactor, the technological conditions optimization and the fouling and cleaning processes of Nafion membrane etc. have a great science and applied significance for electrochemical synthesis of p-aminophenol using nitrobenzene (NB) as raw material. The research contents of this paper are one of subjects funded by Henan Key Research Projects (No. 03223023800) in 2003.In the electro-synthesis process of p-aminophenol, supporting electrolytes were sulfuric acid aqueous solution, and the reaction solution were the mixtures consisting of p-aminophenol, water, H2SO4, aniline and un-reacted NB. The analysis method that can simultaneously and rapidly analyzes the contents of p-aminophenol and aniline in reaction mixture liquid was not found in literature. In this paper, a new analysis method that can simultaneously analyzes the contents of p-aminophenol and aniline in reaction mixture liquid was proposed by combining gas phase chromatography method with equivalence absorbency double-wavelength UV spectrophotometry method.The cathode is the catalyst and a reaction field for electro-catalytic reaction. Base on the properties of the electro-synthesis process of p-aminophenol and with the methods of CV, steady-state polarization curve and controlled potential electrochemical reduction, the electro-catalytic properties of Cu, Ni, Monel alloy and Cu-Hg electrode were investigated, respectively. It was found that the Monel alloy and Cu-Hg cathodes exhibited higher overpotential to hydrogen evolution, better electro-catalytic activity and p-aminophenol selectivity, and can be applied in the electro-synthesis process of p-aminophenol. Further thinking of the factor of mercury pollution aspect, Monel alloy was finally selected as the cathode material for electrochemical reduction NB to p-aminophenol.According to the analysis of the chemical reaction engineering theory and the NB electrochemical reduction mechanism, the fluid flow patterns in the electrolyzer used as direct electrochemical reduction NB to p-aminophenol should be close to plug-flow. Based on the outcome, the Plate and frame electrolyzer that can be used in direct electrochemical reduction NB to p-aminophenol was designed. In terms of the results of the residence time distribution(RTD) experiments and the direct electrochemical reduction experiments of NB, it can be known, when the catholyte flow rate is 300L.h-1, the fluid flow patterns in the electrolyze are close to plug-flow and both the current efficiencies and the yield of PAP are the highest.In this study, using Nafion 427 cation-exchange membrane as membrane, Monel alloy as cathode and Pb-Sb alloy as anode, the technology conditions for synthesizing...
Keywords/Search Tags:p-Aminophenol(PAP), Nitrobenzene (NB), Monel alloy, Direct electrochemical synthesis, Membrane cleaning, Solution thermodynamic, Solubility, Density, Volumetric properties, viscosity
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