Study On The Preparation Process Of Glyoxylic Acid By Oxygen-Purged Nitrate Oxidation And Analytical Method For The Product By Liquid Chromatography

This thesis consists of two parts: study on the preparation process of glyoxylic acid by oxygen-purged nitrate oxidation and analytical method for the product by liquid chromatographyThe currently most adopted process of glyoxylic acid production is the oxidation of glyoxal with nitric acid.The main drawbacks of the process are the air pollution caused by the release of nitrogen oxides and reduced yield due to over oxidation.This ressearch aims to solve the above process problems by introduction of 1 atm oxygen into the oxidation reation mixture to reduce the amount of nitric acid used to generate glyoxglic acid and emission of nitrogen oxides.This study examined the influence of various reaction factors on the yield of glyoxylic acid and glyoxal conversion rate,then conducted orthogonal experiment,obtained the optimized process conditions.The study found the yield and transformation rate are mainly influenced by the amount of nitric acid and nitrous acid,and oxygen flow rate.The current optimal conditions are:reagent ratio is 1:0.22:0.11:0.46,oxygen flow rate for 50±5ml/min.The initiation temperature is about 45±1?,the oxidation temperature is about 63±1? and the incubation temperature is about 78±1?.Under the optimum conditions,the yield of the glyoxylic acid reached to above 86.6%,glyoxal conversion rate up to 98.9%,better than the 84.6% of the existing literature glyoxylate yield and 80.0% of industrial production of glyoxylic acid yield.The process can significantly reduce the cost of nitrate input and environmental protection and increases the profit margin of glyoxylic acid.The thesis has a significant guidance for environmentally friendly production of glyoxylic acid.The HPLC method for the analysis of the glyoxylic acid product has been established in this thesis.The method can detect glyoxylic acid,oxalic acid and glyoxal,with a small amount of reagent,short time,smaller error.BIO-RAD M column is selected for this method.The column was filled with polystyrene divinylbenzene resin,which uses ion regulation to separate mixtures,resultig in an effective separation of glyoxylic acid,oxalic acid and glyoxal derived from glyoxal and can give good peak shape for all the analytes.The standard addition recovery rates are above 96% and relative standard deviations are less than 1%.Chromatographic conditions: the mobilephase was 0.008mol/L sulfuric acid aqueous solution;flow rate was set to 0.6m L/min;wavelength was 210nm;column temperature was 35?.The analysis method estabilished by the research has important practical value on quality control of glyoxylic acid in the chemical industry.