Preparation And Extraction Of Glyoxylic Acid By Catalytic Oxidation Of Glyoxal

Glyoxalic acid is a kind of important chemical raw materials,traditional glyoxalic acid production methods are glyoxal nitric acid oxidation method,but the production process of serious environmental pollution,high product purity is not restricted to use in the promotion of the technology.Although the metal catalyst can overcome the above difficulties to some extent,the shortcomings of catalyst instability can not be solved fundamentally.The catalysis of Pd/SiO₂ catalyst by microemulsion was used to catalyze the extraction reaction with trioctylamine as the extractant,so as to improve the activity and selectivity of the catalytic reaction.First of all,the nuclear shell structure which was prepared by microemulsion Pd/SiO₂catalyst,the structure of the catalysts were characterized the BET,examines the preparation conditions of emulsification temperature,PdCl₂ solution concentration and PdCl₂ solution and Tween-80 quality than the influence of the preparation conditions on the catalyst structure.The results showed that the concentration of aqueous solution of 30 and PdCl₂ was0.085mol/L,PdCl₂ solution and Tween-80 mass ratio 1:1,the conversion rate of acetaldehyde was 76.20%,and the selectivity of acetaldehyde was 56.76%.Then,the effects of reaction temperature,reaction time,acetaldehyde concentration and catalyst addition on the performance of catalyst were investigated.The results showed that the reaction temperature was 45,the reaction time was 4h,the concentration of acetaldehyde was 30wt%,and the catalyst added 0.43g,when the conversion rate of glyoxal was 78.46%,and the selectivity of acetaldehyde was 60.49%.Finally octyl amine as the extraction agent,the use of three studied the catalytic reaction,examines the extraction reaction conditions with extraction agent,diluent kinds,the amount of extraction solvent and extraction agent and diluent volume ratio on the extraction reaction.Results show that the extraction solvent and the reaction liquid volume ratio of 1:1,diluent as octyl alcohol,thinner and extractant volume ratio of 50%was octanol+50%TOA,glyoxal conversion rate was 81.62%,the glyoxylate selectivity is 70.23%,superior to the traditional nitric acid oxidation method.