Study On Solid-liquid Equilibrium Of Cyclohexane Oxidation System

Cyclohexane oxidation is an important chemical reaction in the industry.It is one of the pivotal means to prepare cyclohexanone,cyclohexanol,adipic acid,etc.This process also produce by-products glutaric acid,succinic acid,caprolactone,water,etc.So,the components of the reaction system are complex.In order to reasonably and efficiently recover the solvent and design the process conditions for product separation and purification,the basic data of solid-liquid equilibrium of the complex component system is essential.Therefore,the main content of this article is to determine and improve the solid-liquid equilibrium data of the cyclohexane oxidation system,and use the thermodynamic model to carry out correlation research.The details are as follows:1.Using dynamic laser method to measure adipic acid,glutaric acid and succinic acid in different ratios of propionic acid+caprolactone,propionic acid+cyclohexanone,propionic acid+cyclohexane and propionic acid+water binary solvents in the temperature range of283.95K-340.45 K.The experimental data is related to the Apelblat model equation and the NRTL model equation,and the corresponding relative average deviation is 3.00 % and 2.55%,as well as obtained a series of solid-liquid phase equilibrium model parameters.The results show that compared with the Apelblat model,the NRTL model equation can better correlate glutaric acid,succinic acid and adipic acid in propionic acid + ?-caprolactone system,propionic acid + cyclohexanone system,propionic acid + cyclohexane system solubility data and other solid-liquid equilibrium data in the solvent system under study.2.Use the obtained NRTL model parameters to predict the solid-liquid phase equilibrium of the binary acid in the ternary solvent system.Which is determine the adipic acid,glutaric acid and succinic acid under normal pressure in the temperature range of288.45K-335.95 K,then omparing the experimental data of binary acid in propionic acid+?-caprolactone+water system and binary acid in propionic acid+cyclohexane+water system,the relative average deviations of the data are 1.99% and 3.32% respectively.It shows that the partial theoretical thermodynamic model NRTL equation has predictability in the solid-liquid equilibrium system of propionic acid-cyclohexane oxidation reaction with different composition and temperature.3.Using dynamic laser method to measure the solid-liquid phase equilibrium data of adipic acid,glutaric acid and succinic acid in various alcohol solvents(methanol,ethanol,n-propanol,isopropanol,n-butanol,isobutanol,tert-butanol,n-octanol)at normal pressure within the temperature range of 273.00K-358.55 K.The Apelblat model,?h model and NRTL model are correlated to the experimental data,and a series of model parameters of solid-liquid equilibrium are obtained.The results of the Akaike Information Criterion(AIC)analysis screened the best models for each system.The results are as follows: For adipic acid in isobutanol,glutaric acid in tert-butanol,succinic acid in n-propanol,isopropanol,n-butanol,the Apelblat model is the most suitable of the three models.For adipic acid in n-butanol and glutaric acid in isopropanol,the ?h model is the most suitable model among the three models.For adipic acid in methanol,ethanol,n-propanol,isopropanol,tert-butanol,n-octanol,glutaric acid in methanol,ethanol,n-propanol,n-butanol,isobutanol,n-octanol and succinic acid in methanol,ethanol,isobutanol,tert-butanol,n-octanol results,the NRTL model is the most suitable model of the three models.4.Using the dynamic laser method,the solid-liquid phase equilibrium data of adipic acid,glutaric acid and succinic acid in other five common organic extractants at atmospheric pressure were measured within 286.25K-358.75 K,and the experimental data were subjected to the Apelblat model,the ?h model,and the NRTL model,and the corresponding relative average deviations are 0.76%,1.30%,and 0.84% respectively,at same time a series of model parameters for solid-liquid equilibrium are obtained.The results of the Akaike Information Criterion(AIC)analysis screened the best models for each system.The results are as follows:For adipic acid in N,N-dimethylformamide and 1-methyl-2-pyrrolidone,glutaric acid in N,N-dimethy-lformamide and dimethyl sulfoxide neutralize,succinic acid in N,N-dimethylformamide,N,N-dimethylacetamide,dimethyl sulfoxide and sulfolane,the Apelblat model is the most suitable of the three models.For adipic acid in N,N-dimethylacetamide and dimethyl sulfoxide,glutaric acid in 1-methyl-2-pyrrolidone and sulfolane,and succinic acid in 1-methyl-2-pyrrolidone,the ?h model is the most suitable of the three models.For the results of adipic acid in sulfolane and glutaric acid in N,N-dimethylacetamide,the NRTL model is the most suitable of the three models.5.By comparing the experimental data of three dibasic acids at the same temperature and solvent composition,it is found that the solubility of glutaric acid with an odd number of carbon atoms is greater than that of adipic acid and succinic acid with an even number of carbon atoms,there is a phenomenon of solubility "parity effect".In addition,the thermodynamic functions(dissolution enthalpy,entropy,Gibbs energy)were obtained from the SLE data by calculating the van't Hoff equation.