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Phase Equilibrium Of Dibasic Acid Mixed System And Its Thermodynamic Correlation

Posted on:2017-03-07Degree:MasterType:Thesis
Country:ChinaCandidate:L MengFull Text:PDF
GTID:2131330488494468Subject:Chemical processes
Abstract/Summary:PDF Full Text Request
Adipic acid is a raw material for the production of nylon 6 and nylon-66, and it is also a very important organic chemical raw materials. In industry, adipic acid is mainly produced by the oxidation of nitric acid, cyclohexanol or cyclohexanone in the role of copper, vanadium salt as catalyst. In the production process, succinic acid, glutaric acid and other by-products are also produced as well. The so-called mixed dibasic acid is the generic name that contains three dibasic acid mixtures. To protect the environment and make full use of resources, the separation, purification and recycling of mixed dibasic acid is particularly important. Solvent crystallization for separating mixed dibasic acid is an effective separation method, but this method needs more comprehensive accurate solubility data. In this paper, the solubility data for ternary and quaternary systems formed by mixed dibasic acid with ethanol and n-butanol have been measured. These studies provide the necessary theoretical basis for separation of dibasic acids via solvent crystallization, and have important practical significance.The solid-liquid phase equilibrium data of succinic acid+adipic acid+ethanol, succinic acid+glutaric acid+eihanol, adipic acid+glutaric acid+ethanol were determined by Schreinemaker’s method of residue at 283.15K,303.15K and 313.15K, respectively. The phase diagrams of these systems were constructed on the basic of the measured solubilitity. The solubility of ternary systems was correlated by Wilson equation and NRTL equation, and binary interaction parameters of succinic acid-adipic acid, succinic acid-glutaric and adipic acid-glutaric acid were obtained. The results showed that the calculation results had good agreement with the experiment values. As a result, the Wilson equation and NRTL equation could all be used to correlate and calculate the ternary systems. The densities of the equilibrium liquid phase were obtained, and dependence of density for equilibrium liquid phase on mass fraction of succinic acid or adipic acid was shown graphically in this paper. Furthermore, the densities of the equilibrium liquid phase were correlated with an empirical equation, and the corresponding regressed values of model parameters were obtained. The results showed that the empirical equation could correlate well with the equilibrium solution density.The solid-liquid phase equilibrium data of succinic acid+adipic acid+n-butanol, succinic acid+glutaric acid+n-butanol, adipic acid+glutaric acid+n-butanol were determined by Schreinemaker’s method of residue at 283.15K,303.15K and 313.15K, respectively. The phase diagrams of these systems were constructed on the basic of the measured solubilitity. The solubility of ternary systems was correlated by Wilson equation and NRTL equation. The results showed that the calculation had good agreement with the experiment value. As a result, the Wilson equation and NRTL equation could all be used to correlate and calculate the ternary systems. The densities of the equilibrium liquid phase were obtained, and the curves for density of equilibrium liquid phase and mass fraction of succinic acid or adipic acid were shown graphically in this paper. Furthermore, the densities of the equilibrium liquid phase were correlated with an empirical equation, and the corresponding regressed values of parameters were obtained. The results showed that the empirical equation could be used to correlate the data of the equilibrium solution density.The solubility for the quaternary system of succinic acid+glutaric acid+adipic acid+ ethanol and succinic acid+glutaric acid+adipic acid+n-butanol was measured by the moist solid method at 283.15K,303.15K and 313.15K, respectively. There were three crystal areas, three saturation curves and one saturation point. Compared with the ternary phase diagram, when a third substance was added in the system, the solubility of other two materials in the solvent decreased.
Keywords/Search Tags:Succinic acid, Glutaric acid, Adipic acid, Crystallization, Solubility, Phase equilibrium, Phase diagram, Wilson, NRTL
PDF Full Text Request
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