The Recovery Technique Of Adipic Acid And Foundational Research

Adipic acid is the most important dicarboxylic acid, and it is a valuable raw material used in the chemical industry.A large amount of waster liquor of cyclohexane oxidation comes from the process of bionic catalytic oxidation of cyclohexane. There is a great deal of adipic acid in the waste liquor of cyclohexane. In this study, the recovery technology of adipic acid was done in order to increase the accessional value of the reaction apparatus, reduce the cost of production, reduce pollution of environment, and increase economic value and social performance.Be based on the optimal technical conditions of using nitric acid to dispose waste liquor of cyclohexane oxidation, correlative physical characteristics was determined and the factors of influencing the adipic acid crystal were studied. The condition of primary and secondary crystallization was investigated. The amount of water for primary crystallization was 80～85% of raw material and the amount of water for secondary crystallization was more than 85% of material. On this condition, the yield of adipic acid is 100%, and the purity can be more than 99%. The effects of the operational parameters, such as crystal temperature, cooling rate, and seed amount on the crystal size distribution (CSD), yield and purity of the products were studied in this paper.The conditions of using hydrogen peroxide to dispose waste liquor of cyclohexane oxidation were studied. Some factors of influencing the quality of adipic acid, such as reaction temperature, the amount of hydrogen peroxide, reaction time and catalyst were investigated. Without catalyst, the highest purity of adipic acid was 98.67% which was obtained using amount of hydrogen peroxide that was equal to 2/3 of the raw material quality at 70℃for 2.5h, however, the reclaiming yield of adipic acid was 79.72%.By using laser monitoring technique, solid-liquid equilibrium data of glutaric acid in cyclohexanol, cyclohexanone, their five mixed solvents and acetic acid were measured within the temperature range from 292.15K to 354.60K. Empirical formula andλh equation were used to correlate the solubilities of glutaric acid in eight solvents and the corresponding parameters were given. In addition, the solubility data of glutaric acid in five mixtures (cyclohexanone+cyclohexanol) could be predicted with Wilson equation and NRTL equation utilizing the parameters of the binary systems. The results showed that empirical formula andλh model could correlate the solubility data of glutaric acid in eight solvents and the maximal average relative deviations were 1.15% and 2.20%. At higher temperature, Wilson equation and NRTL equation could predict the solubility of different proportional ternary system better.