Solid-liquid And Liquid-liquid Equilibria In The Oxidation Of Cyclohexane To Adipic Acid

The oxidation of cyclohexane to adipic acid is a gas-liquid-solid three-phase reaction process.During the oxidation process, acetic acid is the solvent. Adipic acid is the target product, and thereare many by-products, such as glutaric acid, succinic acid, cyclohexanone, cyclohexanol, water andso on. The phase equilibrium data of this reaction system is essential in understanding the formationmechanism and macrodynamics of the product deeply, controlling the reaction conversion andselectivity and determining the operating conditions of solvent recovery and solid-liquid separation.In this paper, we made a study of eight main products (including adipic acid, glutaric acid, succinicacid, cyclohexanone, cyclohexanol, acetic acid and water), and then the LLE and solubilities SLEdata of these products were measured and fitted in detail. The specific contents are as follows:1. Considering the special analytical system, we optimize and perfect the analytical method.Gas phase chromatography (GC) was used to analyze cyclohexane, cyclohexanol, cyclohexanoneand acetic acid. Reverse phase high performance liquid chromatograghy (RP-HPLC) was used toanalyze adipic acid, glutaric acid, succinic acid and monacid. Titrimetry was used to analyze waterand Cyclohexyl hydrogen peroxide. After all, working curves were drawn, and quantitative analysismethod was built.2. The LLE data for four ternary systems (water+cyclohexane+acetic acid, water+cyclohexane+cyclohexanol, water+cyclohexane+cyclohexanone, water+cyclohexanol+cyclohexanone) was measured at atmospheric pressure and (303.2~333.2) K. The solubilities ofadipic acid, glutaric acid, succinic acid in binary acetic acid+water and acetic acid+cyclohexanesolvent mixtures were measured at atmospheric pressure and (303.2~343.2) K.3. The LLE data for four ternary systems (water+cyclohexane+acetic acid, water+cyclohexane+cyclohexanol, water+cyclohexane+cyclohexanone, water+cyclohexanol+cyclohexanone) have been fitted using thermodynamic model. By comparing the deviation betweenNRTL model and UNIQUAC model, NRTL model was used for the thermodynamic model fitting.7binary interaction parameters of NRTL model (water+cyclohexane, water+acetic acid, water+cyclohexanol, water+cyclohexanone, cyclohexane+cyclohexanol, cyclohexane+cyclohexanone,cyclohexanol+cyclohexanone) were obtained. The fitting results show that the average relativedeviation between the experiment data and fitted data was1.22%. So we can see that NRTL modelcan be used to fitting the LLE data of these ternary systems, and these binary interaction parametersof NRTL model can be used in the simulation and calculation of liquid-liquid equilibrium process.4. The SLE data of adipic acid, glutaric acid, succinic acid in binary acetic acid+water and acetic acid+cyclohexane solvent mixtures have been fitted using NRTL model with some binaryinteraction parameters obtained from the LLE data.8binary interaction parameters obtained ofNRTL model (water+adipic acid, water+glutaric acid, water+succinic acid, acetic acid+adipicacid, acetic acid+glutaric acid, acetic acid+succinic acid, cyclohexane+adipic acid, cyclohexane+succinic acid) was obtained. The fitting results show that the average relative deviation betweenthe experiment data and fitted data was3.46%. So we can see that NRTL model can be used tofitting the solubilities of these ternary systems, and these binary interaction parameters of NRTLmodel can be used in the simulation and calculation of solid-liquid equilibrium process.Finally, a summary was made, which looked forward to the further application of the resultsachieved and broached some problems in this paper.