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Biobutanol is a green solvent commonly used as gasoline additive. In this study, it is proposed the separation of azeotropic mixtures of butanol and n‐butyl ether (DBE) using ionic liquids (ILs). Suitable anions [AC]− and [H2PO4]− were screened by COSMO‐RS, and the effect of carbon chain length on the separation effect was investigated using quantum chemical calculations. It was found that the anion was primarily responsible for the separation effect, which grew as the carbon chain grew. Molecular dynamics simulations were used to verify the separation performance of the selected ILs. The separation effect of ILs was further verified using vapor–liquid phase equilibrium (VLE) experiments. The extractive distillation process with [PrMIM][AC] as the extractant was investigated to demonstrate the feasibility of ILs for the separation of butanol and DBE. This study analyzes the whole process from microscopic mechanism of action, which provides new ideas for the separation of alcohol‐ether systems. [ABSTRACT FROM AUTHOR]

BACKGROUND: 2,2,3,3‐tetrafluoro‐1‐propanol (TFP) is a good solvent that is applied in the electronic industry. To recover TFP from its aqueous solution, conventional distillation cannot be adopted because TFP and water can form a minimum azeotrope. RESULTS: In this work, extractive distillation is applied to separate the azeotropic mixture of TFP and water using 1‐ethyl‐3‐methylimidazolium acetate ([EMIM][Ac]) as an entrainer. Based on the analysis of residual curve map, three processes are designed to separate the mixture. Extractive distillation processes (EDP) I and II consist of an extractive column and two flashes, and EDP III consists of an extractive column, a flash, and a stripper. For evaluating the three processes, total annual cost (TAC), CO2 emissions and global energy consumption (GEC) are considered into the objective function. CONCLUSION: The simulated results show that EDP III with an extractive column, a flash, and a stripper can provide better economic and environmental benefits. Water can be obtained from the extractive column with a molar purity of 99.7%. TFP can be separated from the top of the flash and stripper with a molar purity of 99.7%. Furthermore, the control structure with two‐point temperature for EDP III is explored and it shows good responses for the disturbances of feed flow rate and composition. [ABSTRACT FROM AUTHOR]

Extractive distillation is a common method to separate the mixture, which has the low relative volatility. Many solvents were screened to separate the mixture based on the experiment. Because the number of candidate solvents is high and the experiment is time-consuming. Quantitative structure property relationship was introduced to model and evaluate the relative volatility of isopropanol and water mixture. The model was developed based on genetic function approximation and 10 molecular descriptors were involved in using Material Studio software. The result indicated that the built model was sufficient for predicting the suitable solvent for isopropanol and water mixture. [ABSTRACT FROM AUTHOR]

BACKGROUND During the synthesis of isopropyl alcohol (IPA) by hydration of propylene, diisopropyl ether (DIPE) is usually produced as a by‐product. Because IPA and DIPE can form a binary homogeneous azeotrope with the minimum boiling temperature at atmospheric pressure, it is difficult to separate the binary mixture by simple distillation. RESULT: For separating the azeotrope IPA + DIPE, side‐stream extractive distillation column (SSED) and extractive dividing wall column (EDWC) processes with three entrainers [2‐methoxyethanol (2‐MEA), 2‐ethoxyethanol and propylene glycol ethyl ether (PGEE)] were simulated and optimized based on the minimal total annual cost (TAC). Moreover, CO2 emissions of the six sequences were calculated and the impact on the environment evaluated. CONCLUSIONS: The sequence of SSED with PGEE as entrainer can reduce TAC by ≤34.48%, but EDWC with PGEE can offer TAC reduction of ≤52.46%. The results demonstrate that the EDWC sequence with PGEE as entrainer is favourable for separating the binary azeotrope IPA + DIPE. © 2020 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

• Three ILs [Epy][NTf 2 ], [Bpy][NTf 2 ] and [Hpy][NTf 2 ] were used to extract TFE. • The LLE data of water + TFE + ILs were measured and correlated. • The interactions between the ILs and TFE was explored by QC calculations. 2,2,2-Trifluoroethanol (TFE) as an important fluorinated alcohol has been widely applied in industry. An aqueous solution containing TFE can be obtained during its production and applications. Because TFE and water can form an azeotrope, it is difficult to recover TFE by conventional distillation. To separate TFE and water by liquid-liquid extraction, three pyridyl ionic liquids (ILs), n -ethylpyridinium bis(trifluoromethyl sulfonyl)imide ([Epy][NTf 2 ]), n -butylpyridinium bis(trifluoromethyl sulfonyl)imide ([Bpy][NTf 2 ]) and n -hexylpyridinium bis(trifluoromethyl sulfonyl)imide ([Hpy][NTf 2 ]) were adopted as the extraction reagents. The liquid-liquid equilibrium data for (ILs + TFE + water) were measured at 101.3 kPa and 298.15 K. The separation ability of the three extractants was assessed by distribution coefficient and selectivity. The experimental data were regressed using the NRTL model. The results showed that IL [Epy][NTf 2 ] had a better ability to recover TFE from its aqueous solution compared to the other two ILs. The correlated results by the NRTL model agreed with the experimental data. Besides, the calculated values of bond length, interaction energy, electrostatic potential and reduced density gradient between the molecules of the ILs and TFE revealed the relation between the IL structures and their extraction performance, which can provide a route for designing a rational IL for separating the mixture of water and TFE. [Display omitted] [ABSTRACT FROM AUTHOR]

BACKGROUND: There is a special type of azeotrope in the chemical industry. The components can form homoazeotrope under atmospheric pressure and azeotropic temperature but show partial miscibility when the temperature decreases. A two‐column/decanter process was presented to separate the mixture. However, the energy consumption and the total annual cost are high. RESULTS: Based on the decanter temperature, the operating parameters of the conventional process and the modified process were optimized to achieve the minimum total annual cost (TAC). Through comparing the two processes, the minimum TAC of the latter one is 14.2% lower than that of the former one when the decanters of the two processes are at 10 °C. A control structure, which can efficiently control the modified process, was also explored and verified. CONCLUSION: For the conventional process and the modified process, the influences of the decanter temperature on the compositions of the layered liquid phases, the total reboiler duty of the columns, and the minimum TAC demonstrated that the decanter temperature has important impacts on energy cost and economy of the two processes. Furthermore, the modified process using two cooling media in combination can further reduce the TAC. © 2019 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Abstract Ternary extractive distillation is a green and sustainable separation process for the treatment of pharmaceutical wastewater containing methanol/acetonitrile and acetonitrile/water azeotropes that achieves the recovery of the acetonitrile and methanol solvents. A novel sequential iterative optimization methodology is proposed and the isovolatility curves of systems at different pressures are analyzed in this work to investigate the effect of the operating pressure on the ternary extractive distillation process. Four optimization procedures with different conditions of pressure and limits for the use of cold utilities were carried out. The optimization results showed that the optimal pressures of the first column and the third column are related to the top vapor that can be condensed by chiller water and cooling water, respectively, and the pressure of the second column is related to the effect of preheating on the third column. The ternary extractive distillation process with optimal operating pressure shows 60.1% energy cost savings and 47.0% total annual cost savings compared with the optimal process operating at atmospheric pressure. The proposed optimization method has the advantages of automatic optimization with a smaller number of simulator runs, providing a new solution for the simulator-based process optimization. The investigation of the operating pressure effect provides additional insight for the design and optimization of ternary extractive distillation. Highlights • A novel sequential iterative optimization methodology is proposed. • The methodology achieves optimization automatically with less computational time. • The process with optimum operating pressure can achieve 60.1% energy savings. • Determinants of pressures in different extractive distillation columns are different. [ABSTRACT FROM AUTHOR]

Abstract: BACKGROUND: Carbon dioxide and ethane easily form a binary azeotrope under liquefied conditions. An extractive distillation process for the separation of carbon dioxide and ethane using the ionic liquids [bmim][Tf2N], [emim][Tf2N] and [emim][EtSO4] as solvents was explored. The thermodynamic and physical property parameters of each ionic liquid and their thermo‐physical properties that correlated with the experimental data were used to create the ionic liquid components and conduct the process simulation. RESULT: Based on the analysis of its physical properties and relative volatilities, [emim][Tf2N] is the best option as a solvent for extractive distillation separation compared with other ionic liquids. Based on the sensitivity analysis optimization procedure, the minimum total annual cost, carbon dioxide emissions and thermodynamic efficiency were calculated. Compared with traditional extraction distillation, the total annual cost and carbon dioxide emissions of the process using [emim][Tf2N] as a solvent decreased by 62% and 31%, respectively. The thermodynamic efficiency (η) of the electricity generated from hydropower increase by 0.7%. CONCLUSION: The results show that an ionic liquid extractive distillation process using an ionic liquid as the entrainer performs better than a process using traditional organic solvents in terms of economics. Due to the non‐volatility of ionic liquids, a flash tank was used instead of a solvent recovery column to efficiently realize solvent recovery. © 2017 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

• A thermal coupled SSED sequence with intermediate and heavy entrainers is investigated. • The SSED is adopted to separate the binary mixture of acetone + n- heptane. • The SSED sequence with p -xylene can offer reduction of TAC and CO 2 emissions. An azeotropic mixture of acetone and n -heptane is commonly found in many pharmaceutical wastewaters. In this work, the separation of acetone / n -heptane was studied using intermediate- and high-boiling-point entrainers (benzene and p -xylene, respectively). To maximize the economic benefits and mitigate the economic and environmental impact of the separation process, traditional extractive distillation and side-stream extractive distillation processes were developed for different entrainers. The sequential iteration method was employed to optimize the extractive distillation process, with the total annual cost as the constraint objective. The results show that p -xylene can facilitate the separation of acetone / n- heptane, with high efficiency and low energy consumption, when using a double distillation column. Among the four separation processes developed, the p -xylene side-stream extractive distillation process delivers the best economic and environmental performance, with a total annual cost of 6.04 × 105 $/y and CO 2 emissions of 1114.66 kg/y. Compared to the case of traditional p -xylene extractive distillation and benzene side-stream extractive distillation processes, the total annual cost of the p -xylene side-stream extractive distillation process was reduced by 9.56% and 49.22%, respectively, while the corresponding CO 2 emissions were reduced by 15.71% and 48.85%. [Display omitted] [ABSTRACT FROM AUTHOR]

• Three ILs [Bmim][H 2 PO 4 ], [Emim][PF 6 ] and [Bmim][PF 6 ] were used to extract IPA. • The LLE data for IPAC + IPA + ILs were determined and correlated. • The interactions between the ILs and IPA were explored. • [Bmim][H 2 PO 4 ] is a suitable extractant to recover IPA from IPAC. During the production of isopropyl acetate (IPAC), a mixture of IPAC and isopropanol (IPA) can be produced. Because IPAC and IPA can form a minimum azeotropic mixture with the azeotropic temperature of 354.08 K, it is difficult to separate such a mixture. In this work, liquid-liquid extraction is considered to separate the mixture of IPAC and IPA. Herein, the liquid-liquid equilibrium (LLE) data was determined and correlated for the separation of IPAC and IPA. For separating IPAC and IPA by extraction, three ionic liquids (ILs) 1-ethyl-3-methyl-imidazolium hexafluorophosphate, 1‑butyl‑3-methyl-imidazolium hexafluorophosphate and 1‑butyl‑3-methyl-imidazolium dihydrogen phosphate were selected as extractants. The liquid-liquid equilibrium phase behavior of ternary mixtures (IPAC + IPA + ILs) at 298.15 K was investigated. The distribution functions of charge density and interaction energy were determined by the COSMO-SAC model and Dmol3 in Materials Studio, and the interactions between molecules were explored. The experimental data showed that the three ILs can extract IPA from the mixture of IPAC and IPA and the IL [Bmim][H 2 PO 4 ] has a better extraction ability compared to the other ILs. The measured LLE data were fitted using the NRTL model and the interaction parameters were regressed, which is a favor in separating the mixture for industrial practice. [Display omitted] [ABSTRACT FROM AUTHOR]

Dynamic control of a pressure-swing-distillationprocess for separationof azeotropic mixture of tetrahydrofuran and methanol is explored.The pressure-swing-distillation processes involved with no, partial,and full heat integration are simulated using Aspen Plus Dynamics.The influences of the selection of the sensitive temperature stagein the low-pressure column on the dynamic responses in the pressure-swingdistillation with different heat integration were investigated. Theresults indicate that a suitable temperature control stage in thelow-pressure column is crucial to achieve efficient control of theprocess. In addition, more time is needed to reach the quality specificationsunder feed disturbances for both components when heat integrationis added in the distillation sequence. [ABSTRACT FROM AUTHOR]

A processoptimization is carried out to separate binary azeotropicmixtures of tetrahydrofuran and methanol by pressure-swing distillationaccording to the pressure-sensitive property of the binary system.Rigorous steady-state simulation that is based on the minimizationof the total annual cost for partially and fully heat-integrated pressure-swing-distillationprocesses is implemented on Aspen Plus following the sequential iterativeoptimization procedure. The feasible sequence of high pressure andlow pressure of two columns in the pressure-swing-distillation processand the suitable heat integration scheme are both determined by thefeed composition. [ABSTRACT FROM AUTHOR]

• DCBS-R process was designed to separate the azeotrope. • TAC and CO 2 emissions were analyzed based on the multi-objective optimization. • TAC and CO 2 emissions reduced by 7.1% and 30.2% with partial heat integration. Batch distillation is widely employed in the fine chemical industry because of its operational flexibility. The mixture of n-heptane and isobutanol exhibits a special azeotropic phenomenon by which it changes from a minimum-boiling azeotrope to a maximum-boiling one with increasing pressure. However, the traditional double column batch rectifier and double column batch stripper processes cannot separate the mixture efficiently. Therefore, the double-column batch stripper–rectifier (DCBS-R) process was designed to obtain high-purity products, based on the azeotropic phenomenon. Further, control structures are explored to achieve stability, and the final purities of the separated products are over 99.9%. Each batch of raw materials is 100 kmol, and the expected annual production capacity is 800 batches. Additionally, a precooler of the low-pressure column (LPC) is introduced to reduce the exergy destruction by exergy analysis. The equipment cost and CO 2 emissions are analyzed afterward to optimize the process, based on the multi-objective optimization method. Further, the number of stages and the pressure of the columns are optimized. The optimal obtained total annual cost (TAC) and CO 2 emissions of the DCBS-R process are 2.26 × 105 $/y and 4.92 × 105 kg/y, respectively. The partial heat integration is studied to further improve the process performance, thus obtaining TAC and CO 2 emissions of 2.22 × 105 $/y and 3.80 × 105 kg/y, which are 7.1% and 22.76% lower than the values obtained from the optimal process, respectively. [ABSTRACT FROM AUTHOR]

Isopropyl alcohol (IPA) and diisopropyl ether (DIPE) are widely used as biofuel additives in fuel processing. When IPA is produced by propylene hydration, a by-product IPA and DIPE is made. Since the existence of azeotropic point formed between IPA and DIPE, the separation of the azeotrope is achieved using special distillation technologies in industry, which requires high energy consumption. Liquid-liquid extraction was used to separate the mixture due to its energy saving in this work. Three imidazolium-based ionic liquids (ILs) 1-butyl-3-methylimidazolium thiocyanate ([BMIM]SCN), 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([BMIM]NTf 2) and 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM]BF 4) were synthesized as the extractants. The influence of extraction time, extraction temperature, mass ratio of mixture (IPA + DIPE) to ILs and the initial content of IPA in the mixture (IPA + DIPE) on the extraction performance of ILs were studied. The optimal extraction conditions were determined using the response surface method (RSM). The results showed that the IL [BMIM]SCN had better extraction capacity for separation of the mixture (IPA + DIPE). The interactions between molecules were investigated by quantum chemical calculations. Finally, a conceptual separation process is designed to separate the mixture, which can provide a helpful technology to purify the biofuel additives. • Three ILs [BMIM]SCN, [BMIM]NTf 2 and [BMIM]BF 4 were synthesized as extractants to separate mixture (IPA + DIPE). • The extraction performance of the ILs was assessed and the optimal conditions were determined by RSM. • The interactions between IPA and the ILs were analyzed by quantum chemical calculations. • A separation process for purification of IPA and DIPE is proposed with [BMIM]SCN as the extractant. [ABSTRACT FROM AUTHOR]

• A new distillation process for purifying MMA from azeotrope is proposed. • The feasibility of separation are assessed using ternary phase diagram analysis. • Extractive distillation and pressure-swing distillation are coupled for new process. • Heat integrated extractive pressure-swing distillation is used to save more energy. • Evaluate the processes from the economy, environment, energy and exergy. Methyl methacrylate is a new polymer material monomer, which is often used in the manufacture of plexiglass, and has very high industrial application value. Producing high purity methyl methacrylate requires a clean and effective separation process. In this work, an efficient separation method of methyl methacrylate/water/methanol azeotrope based on pressure swing distillation coupled extractive distillation is established. The best entrainer in terms of both environmental impact and effectiveness is chosen by examining the impact of relative volatility. The feasibility of pressure swing distillation and the best separation order are determined by ternary phase diagram analysis. A multi-objective optimization method is used to optimize the three designed processes, targeting gas emissions and total annual costs, thereby obtaining the best process plans and parameters. On this basis, the optimal thermal integration design of the three processes is carried out. The analysis of the four processes is conducted from the viewpoints of the energy, economy, environment and exergy. The findings demonstrate that the pressure swing extractive distillation process when combined can significantly increase economy and lessen mixture separation difficulty. Compared with the traditional process, the total annual cost, gas emission and energy loss are reduced by 8.20%, 10.46%, 11.69%, and the effective energy utilization rate is 50.31%. The development of this process is of great significance for the recovery of wastewater containing methyl methacrylate and methanol and the separation of high-purity methyl methacrylate. [ABSTRACT FROM AUTHOR]

• Energy, economic and environmental analysis is used to evaluate the four processes. • Hybrid processes combining extractive distillation and pervaporation is used to separate ternary mixture. • Compared with TCED process, EDPV process can achieve 46.47 % CO2 reduction. Ethyl acetate is a vital chemical raw material and is usually produced by esterification in industry. But this reaction can produce multiazeotrope mixtures of ethyl acetate/ethanol/water. In this work, triple column pressure-swing distillation process with and without heat integration and hybrid processes combining extractive distillation and pervaporation are proposed to separate a mixture of ethyl acetate/ethanol/water. Furthermore, the three processes are comprehensively compared with the triple-column extractive distillation process. Based on minimization of the total annual cost, the parameters of the all processes are optimized. The triple-column extractive distillation process has the greatest economic advantage. Additionally, the performances of the all processes in environmental protection and energy efficiency are evaluated. The energy efficiency of the combined extractive distillation and pervaporation unit process is relatively low, but its environmental impact is the lowest among the four processes. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel and energy-saving reactive pressure-swing distillation process was designed for separating the THF-methanol-water mixture. • Energy consumption was greatly reduced by multi-objective genetic algorithm and heat-integrated optimization. • The total annual cost of the designed two heat integration processes for the RPSD-B was greatly reduced, i.e., 45.9% and 52.2%, respectively. • The water in THF-methanol-water was fully utilized to react with ethylene oxide to generate by-product EG. The low-energy and low-cost process development and design has always been a hot topic and challenge in separating azeotropic systems in the world. In this paper, a novel, energy-saving reactive pressure-swing distillation (RPSD) was, for the first time, designed for separating the ternary mixture of tetrahydrofuran (THF)-methanol–water. In the reactive distillation column, the process of reacting water with ethylene oxide to produce ethylene glycol for the first time was used to separate THF-methanol–water mixture, then the residual mixtures were separated by two pressure-swing distillation columns. Two feasible RPSD separation processes were investigated in terms of thermodynamic modeling and T-xy phase diagram analysis to achieve optimal separation sequence. The two designed separation processes were optimized by a multi-objective genetic algorithm and heat integration to maximize economic benefit. Results demonstrated that, compared to the conventional pressure-swing distillation process, the total annual cost of the designed two heat-integrated processes based on the RPSD-B process were greatly reduced, i.e., 45.9% and 52.2%, respectively. This paper has important guiding significance for the separation and purification of multicomponent azeotropes. [ABSTRACT FROM AUTHOR]

Diethoxymethane, toluene, ethanol are important organic solvents with excellent performance and are widely used in the industrial fields. In this study, extractive distillation with mixed extractants was used to separate the mixture. The separation process of diethoxymethane, toluene and ethanol azeotrope system with different extractant agents was designed. The multi-objective optimization was carried out with the objective of total annual cost and gas emission, and the optimal process parameters were obtained by coordinating the two objectives. Based on the best extractive distillation process with mixed extractants, the intensification of process was performed by adding heat pump and heat integration technology, to improve the economy and energy consumption of the process. By comparing the results of economic, environmental and exergy efficiency analysis calculations, it was found that the intensification of the heat integration technology was better than the intensification of the heat pump. As for the intensification effect of heat integration technology saved about 5.5% more economical than primary mixed extractants process, the gas emission had been reduced by about 14.8% in terms of environment, and exergy loss decreased by 33.8%. This study provides theoretical guidance for the design and optimization of extractive distillation processes using the mixed extractants. • The energy saving intensification of MIXED strategy was studied. • The mixed extractants extractive distillation method was proposed. • Multi-objective optimization is used to optimize parameters of processes. • HIED process had excellent energy saving and environmental performance. [ABSTRACT FROM AUTHOR]

• The appropriate entrainers were screened using the COSMO-SAC model. • The VLE data for TFP + NMP/NMF/DMF were measured at 101.3 kPa. • The VLE data were correlated by the NRTL, Wilson and UNIQUAC models. • The interaction mechanism and effect of the entrainers were explored. For separating the azeotrope of 2, 2, 3, 3-tetrafluoro-1-propanol (TFP) and water by extractive distillation, N -methyl pyrrolidone (NMP), N -methyl formamide (NMF) and N , N -dimethyl formamide (DMF) were selected as entrainers using the COSMO-SAC model based on solvent capacity. And the charge density surface of entrainers and each component in the azeotrope system were calculated. The vapour-liquid equilibrium (VLE) data for the mixtures (TFP + NMP), (TFP + NMF) and (TFP + DMF) were measured by a modified Rose-type recirculating still at the pressure 101.3 kPa. The thermodynamic consistency for the VLE data was validated using the Herington and van Ness methods. The VLE data were correlated with NRTL, Wilson and UNIQUAC models, and the interaction parameters of thermodynamic models were fitted. Meanwhile, the effect of the entrainers on the VLE for TFP and water was explored. Compared with NMF and DMF, NMP was adopted as the suitable entrainer for separation of the azeotropic mixture TFP and water by extractive distillation. [ABSTRACT FROM AUTHOR]

• Double azeotrpic system of ternary mixture is separated by PSBD process. • PSBD integrated with quasi-continuous process was developed and analyzed. • Control scheme was explored to keep the separated components at high-purity level. Two pressure-swing batch distillation processes, which are double-column batch stripper process and its integration with quasi-continuous process named triple-column process, were designed and investigated to separate the tetrahydrofuran/methanol/water ternary system. There are two azeotropes in the system and previous studies about batch distillation to separate such mixtures are insufficient. Based on the residue curve maps, the feasibility of the processes was analyzed. Control structures were explored to implement efficient separation and ensure the safety and stability of the process. The minimum total annual cost was used to optimize the processes. The double-column batch stripper process can separate the tetrahydrofuran and water well but the methanol purity is only 99.4 mol%. To improve the separation effect, a third column was integrated in the batch distillation process to separate the methanol/water mixture directly. The new triple-column process has the characteristics of batch distillation and continuous distillation. The results show that the minimum TAC of double-column batch stripper process is 147,815 $/y which is a little lower than that of triple-column process by only 3.2%. The final compositions of tetrahydrofuran and water are same in the two processes, which are 99.9 mol% for water and 99.85 mol% for tetrahydrofuran, but the methanol purity is different. The methanol is 99.4 mol% in the double-column process while 99.9 mol% in the triple-column process. The improved methanol purity reflects the high separation efficiency and it is beneficial for the environmental protection. [ABSTRACT FROM AUTHOR]

• PGEE was selected as extractant to separate the mixture of IPA + DIPE + NPA. • The charge density surface and the interaction energies were calculated to explore the interaction mechanism. • The VLE data for the systems IPA + PGEE, DIPE + PGEE and NPA + PGEE were measured and correlated. • An extractive distillation process for separating the mixture IPA + DIPE + NPA was proposed. For separation of the mixture {isopropyl alcohol (IPA) + diisopropyl ether (DIPE) + n-propanol (NPA)} by extractive distillation, propylene glycol ethyl ether (PGEE) was used as an entrainer based on selectivity since isopropyl alcohol + diisopropyl ether can an azeotrope. To explore the interaction mechanism between the entrainer PGEE and the components in the mixture, the charge density surface (σ-profiles) and the interaction energies were calculated based on the COSMO-SAC model and Dmol3, which could provide theoretical insight into interactions at the molecular level. Then, the data of isobaric vapour-liquid equilibrium (VLE) for (IPA + PGEE), (DIPE + PGEE) and (NPA + PGEE) systems were measured at 101.3 kPa. The NRTL, UNIQUAC and Wilson equations were applied to correlate the measured VLE data, and the thermodynamic model parameters for the binary systems were obtained by fitting the VLE data, which is helpful for the simulation and optimization of the separation process. [ABSTRACT FROM AUTHOR]

Highlights • The entrainers p -xylene, butyl propionate and isobutyl acetate were selected. • The VLE data for (DMC + entrainers) and (ethanol + isobutyl acetate) were measured. • The measured VLE data were correlated by the NRTL, UNIQUAC and Wilson models. • The extractive distillation process for separating DMC and ethanol was proposed. Abstract Dimethyl carbonate and ethanol can form an azeotrope with the minimum boiling point. To separate the azeotrope (dimethyl carbonate + ethanol) by extractive distillation, p -xylene, butyl propionate, and isobutyl acetate were chosen as entrainers, and the isobaric vapour-liquid equilibrium (VLE) data for the binary systems of (dimethyl carbonate + p -xylene), (dimethyl carbonate + butyl propionate), (dimethyl carbonate + isobutyl acetate) and (ethanol + isobutyl acetate) were measured at 101.3 kPa using a modified Rose type recirculating still. The thermodynamic consistency of the VLE experimental data for the four binary mixtures was tested by the Herington and van Ness methods. Furthermore, the measured VLE data were correlated by the NRTL, UNIQUAC and Wilson thermodynamic models and the binary interaction parameters of the three models were regressed. Based above, an extractive distillation process with the entrainer of p -xylene was proposed and simulated to separate the azeotrope (dimethyl carbonate + ethanol). [ABSTRACT FROM AUTHOR]

• Found the optimal control structure for extractive distillation with two solvents. • Using the ISE to judge the measure of dynamic control. • Dynamic control performance can be a way to assess the reliable of QSPR. Extractive distillation is a common method to separate the mixture which has the low relative volatility, such as acetone and tetrahydrofuran mixture. Because the number of candidate solvents is high and the experiment is time-consuming, the selection method of solvent is important. In our previous work, quantitative structure property relationship was introduced to model and evaluate the relative volatility of acetone and tetrahydrofuran mixture. The flowsheet of extractive distillation was set up and the total annual cost was calculated with n-Octane and butyl ether as new and former solvent, respectively. Except the mathematical verification, we think that the dynamic control of the configuration of extractive distillation can also be a method to evaluate the feasibility of the built model. In this paper, we studied the dynamic control for extractive distillation with n-Octane and butyl ether as solvent and the integral of squared error was calculated for purity of two products. The results show that some indexes for n-Octane as solvent are better than that for butyl ether as solvent. The dynamic control performance is consistent with the results of economical and can be a way to judge the reliability of quantitative structure property relationship. [ABSTRACT FROM AUTHOR]

Allyl alcohol and water can form an azeotrope with the minimum boiling point. To separate the azeotrope of allyl alcohol and water by salt distillation, three salts calcium chloride, calcium nitrate and magnesium nitrate were selected to break the azeotrope. The vapor-liquid equilibrium (VLE) data for the systems allyl alcohol + water, allyl alcohol + water + calcium nitrate, allyl alcohol + water + calcium chloride and allyl alcohol + water + magnesium nitrate were measured at pressure of 101.3 kPa. The results indicated that the relative volatility of allyl alcohol to water increased by adding the salts at the molar fraction of allyl alcohol higher than 0.2. With increasing the concentrations of the salts, the azeotropic point of the system allyl alcohol + water moved. When the concentrations of calcium chloride and magnesium nitrate were 0.10, 0.15, respectively, the azeotropic point was broken. The effect of salts on the azeotropic point of the system allyl alcohol + water follows the order: calcium chloride > magnesium nitrate > calcium nitrate. Moreover, the experimental VLE data were correlated by the NRTL model. All the root-mean-square deviations for the temperature ( T ) and the mole fraction of the vapor phase ( y 1 ) between the measured and calculated data were less than 0.26 K and 0.005, respectively. Meanwhile, the binary interaction parameters of the NRTL model were regressed. [ABSTRACT FROM AUTHOR]

• 1. Three ILs [BMIM]SCN, [BMIM]DCA and [BMIM]NTf 2 were synthesized to extract IPA. • 2. The LLE data for the ternary mixtures DIPE + IPA + ILs were determined and correlated. • 3. The interactions between IPA and the ILs [BMIM]SCN / [BMIM]DCA / [BMIM]NTf 2 were explored. During production of isopropyl alcohol (IPA) by propylene hydration, a mixture of diisopropyl ether (DIPE) and IPA is obtained as a byproduct. Because DIPE and IPA have similar boiling points, an azeotrope can be formed. It is not feasible to separate the mixture (DIPE + IPA) using conventional distillation technology. In this work, the mixture (DIPE + IPA) was separated by liquid–liquid extraction and three imidazolium based ionic liquids (ILs) with different anions including 1-butyl-3-methylimidazolium thiocyanate ([BMIM]SCN), 1-butyl-3-methylimidazolium dicyanamide ([BMIM]DCA) and 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([BMIM]NTf 2) were selected as the extractants. The effect of the ILs on liquid–liquid phase behavior for the ternary systems (DIPE + IPA + ILs) was discussed. Partition ratio (P) and selectivity (S) were calculated to assess the extraction ability of the ILs. The NRTL thermodynamic model was used to correlate the experimental data. The interactions between the ILs and (DIPE / IPA) were explored by analyzing electrostatic potentials, hydrogen bond length and reduced density gradient, which can help to design the ILs with reasonable structures for separating such azeotropic mixtures. [ABSTRACT FROM AUTHOR]

• COSMO-SAC model was used to screen hydrogen bond acceptors of deep eutectic solvents. • LLE data of ethanol + IPA + Choline-based DESs systems were measured. • The NRTL model was applied to correlate the studied system. • MD simulation was used to analyze the molecular mechanism of LLE. The production of diclofenac salt involves an azeotropic system consisting of ethanol and isopropyl acetate (IPAc). Owing to their simple preparation, low cost, and non-volatility, deep eutectic solvents (DESs) have attracted considerable attention in the field of azeotrope separation. The σ profiles were constructed using a conductor-like shielding model, and the hydrogen-bonding ability between several common hydrogen-bond acceptors (HBAs) and hetero-azeotropic systems was analyzed. To prepare the three types of DESs, choline chloride (ChCl) was selected as the HBA, while ethylene glycol, urea, and glycerol were selected as the hydrogen-bond donors (HBDs). The liquid–liquid equilibrium (LLE) experimental data of the IPAc, ethanol, and synthetic DES systems were then measured at 101.3 kPa and 298.15 K. The accuracy of the experimental data was verified by correlating the data with the Othmer–Tobias and Hand equations, and the NRTL model was used to fit the experimental results. According to the distribution (D) and selectivity (S) coefficients, ethanol had the highest affinity for the ChCl–ethylene glycol DES, and the experimental data and the molecular dynamics (MD) simulations data were well correlated. The interaction energy, spatial distribution functions (SDFs), radial distribution functions (RDFs), and self-diffusion coefficients were calculated using MD simulations to elucidate the extraction mechanism. The MD simulation results showed that the interaction between the HBA in the DESs and ethanol was dominant in the separation, whereas the interaction of the HBD in the DESs with ethanol played an auxiliary role. Based on the experimental and simulation results, the feasibility and effectiveness of the azeotropic system for the DES separation of ethanol and IPAc were verified, which is important for the sustainable utilization of resources. [ABSTRACT FROM AUTHOR]

Acetonitrile/methanol/benzene mixture forms more than one different azeotropes and its triangular diagram presents several distillation boundaries at atmospheric pressure. A process named as triple column pressure-swing distillation (TCPSD) was proposed to separate this complex ternary system. The feasibility of the process was confirmed using residue curve maps and rigorous steady-state simulations were implemented on Aspen Plus. On basis of minimum total annual cost, several operating parameters were optimized by pressure-swing optimization software using the sequential iterative optimization procedure and the economics of TCPSD were compared with four different separation configurations. The results demonstrated that the A-M-B separation configuration was the most optimal column sequence in global optimization to separate acetonitrile/methanol/benzene azeotropic mixture using TCPSD. TCPSD may arouse the interest of researchers in various fields and can assist engineers to select the optimal separating process. [ABSTRACT FROM AUTHOR]

A procedure is suggested to separating a minimum-boiling azeotrope of toluene and ethanol via heat integration pressure swing distillation (PSD), and an optimized separation configuration is obtained via taking the minimization of the total annual cost (TAC) as an objective function. The result demonstrates that PSD with heat integration is more economical than conventional PSD without heat integration. Based on steady-state simulation results, several control structures were explored using Aspen Dynamics. The results indicate that the composition/temperature cascade control structure and the pressure-compensated temperature control of a PSD process with partial heat integration with stage 21 selected as the control stage in the low pressure column can handle disturbances well. As for the PSD with full heat integration, stage 20 of the low pressure column can act as the control stage because of its more efficient controllability under feed flow rate and feed composition disturbances. [ABSTRACT FROM AUTHOR]

[Display omitted] • Two Pyridine-based ILs [EAPy][NTf 2 ] and [OHPy][NTf 2 ] were used to extract TFP. • The extraction capacity of [EAPy][NTf 2 ] and [OHPy][NTf 2 ] was evaluated. • The intermolecular interactions between the ILs and TFP / water were explored. • [EAPy][NTf 2 ] is a suitable extractant to recover TFP from its aqueous mixture. 2,2,3,3-Tetrafluoro-1-propanol (TFP) is benign solvent and applied in electronic industry. To recover TFP from its aqueous solution by liquid–liquid extraction, in this work, two pyridine-based ionic liquids (ILs) 1-ethyl acetate-pyridine bis(trifluoromethane)sulfonimide ([EAPy][NTf 2 ]) and 1-hydroxyethyl-pyridine bis(trifluoromethane)sulfonimide ([OHPy][NTf 2 ]) were adopted as extractants. The ILs [EAPy][NTf 2 ] and [OHPy][NTf 2 ] were synthesized and characterized. The extraction performance of the prepared ILs for extracting TFP from its aqueous solution was explored by changing extraction temperature, extraction time and mass ratio of IL to TFP solution. The extraction efficiency of [EAPy][NTf 2 ] and [OHPy][NTf 2 ] was 90.24% and 88.45% with the mass ratio of IL to TFP solution of 1.0 and extraction time of 10 min at 298.15 K. The intermolecular interaction was investigated by quantum chemistry calculations and molecular dynamics simulations. The results indicated that O atom of the IL anion formed strong hydrogen bond with H atom of TFP. In addition, the functional groups on the cations of the ILs showed the van der Waals (vdW) interaction between the ILs and TFP. [ABSTRACT FROM AUTHOR]

Exploring the process of cost-effective and efficient technology to separate ternary aqueous azeotropic systems has become essential research in chemistry and materials science. Traditional distillation technology and promising membrane technology occupy an irreplaceable position in wastewater treatment. However, single separation technology for the separation of azeotropic systems has disadvantages. To better meet the industrial practical needs of different azeotropic compositions in each process of rapeseed oil production, the separation performance and economic cost of single extractive distillation and an extractive distillation coupled pervaporation process for ternary azeotropic systems with different feed compositions were studied. Environmentally friendly and effective solvents were selected as extractants in the extractive distillation process from two aspects: selectivity and biological toxicity. Sequential iterative optimization algorithms were used to optimize the process with the ratio of water to the total amount of cyclohexane and isopropanol ranging from 1:9 to 9:1, considering cost as the evaluation index. The results showed that the cost of the processes increases significantly with increasing water content in the feed composition. Because the flux and selectivity of the membrane module were considerably affected by temperature when the water content was less than 0.4, the integrated process was more economical; otherwise, the extractive distillation process was more economical when the water content was greater than 0.4. [Display omitted] • The potential extractant was selected based on infinite dilution selectivity and toxicity. • The influence of different feed compositions on the process economy was explored. • Sequential iterative algorithm was used for the coupled process. • The composition has an impact on economic performance. [ABSTRACT FROM AUTHOR]

• The separation of MEK/IPA/n-heptane by triple column pressure-swing distillation is studied. • The heat integration scheme and dynamic control strategy of triple column pressure-swing distillation are studied. • The full heat integration process has good ISE value and minimum TAC. In this paper, an economical and robust triple column pressure-swing distillation (TCPSD) process for the separation of butanone/isopropanol/n-heptane (MEK/IPA/n-heptane) ternary azeotrope is studied. The pressure sensibility of MEK/IPA/n-heptane is qualitatively analyzed by residue curve map (RCM), which demonstrated that the economical design for separating the ternary mixture via TCPSD is feasible. The TCPSD process was optimized by the minimum total annual cost (TAC) by using the sequential iterative algorithm, meanwhile, the heat integration is investigated to reduce the energy consumption. The results showed that the partial heat integration can reduce TAC by 11.89%, and the full heat integration can reduce TAC by 39.97% by parameter optimization. The dynamic control strategies that can resist 20% of feed disturbances were proposed for the conventional process, partial heat integration and full heat integration, respectively. The designed and optimized full heat integration scheme is found to be an optimal scheme with good anti-disturbance performance and the best economic performance. This study provides a new train of thought for the separation of MEK/IPA/n-heptane and has meaningful practical application value. [Display omitted] [ABSTRACT FROM AUTHOR]

A ternary mixture of diisopropyl ether, isopropanol and water exists in the production process of isopropanol. Ensuring the clean separation of this mixture is of great significance for the clean production of isopropanol from both economy and environment. However, there are three binary and one ternary minimum boiling point homogeneous azeotropes in this system, which complicate the clean production of isopropanol. In this study, with the aid of the hydration reaction of ethylene oxide, clean separation of a ternary mixture of diisopropyl ether–isopropanol–water was realized. Three separation processes—reaction–pressure swing distillation, reaction–extractive distillation and reaction–dividing wall extractive distillation—were proposed. These processes were optimized based on the sequential iterative algorithm, with the minimum total annual cost as the objective. Reaction-pressure swing distillation had the best economic performance, reaction-extractive distillation followed, and reaction-dividing wall extractive distillation performed the worst. The carbon dioxide, sulfur dioxide, and nitrogen oxide emissions of the three processes were calculated based on the optimization results. Reaction-pressure swing distillation had the lowest emissions, followed by reaction-dividing wall extractive distillation. However, reaction-extractive distillation had the highest emissions. The exergy analysis of distillation units and exchanger was performed, and the results showed that reaction-pressure swing distillation had the best exergy performance. Reaction-pressure swing distillation was better than reaction-extractive distillation and reaction-dividing wall extractive distillation in terms of economy, environment, and thermodynamic efficiency. This study provides an original idea for the clean separation of diisopropyl ether-isopropanol-water azeotropes. Process design and intensification for the separation of ternary multi-azeotropes system via special distillation coupled with reaction. [Display omitted] • Reaction strengthens the separation process of ternary multi-azeotropes. • Reaction product can be used as a valuable product and as separation entrainer. • Three processes are comprehensively evaluated from environment, economy and exergy. • Pressure swing distillation is more advantageous on economy, environment and exergy. [ABSTRACT FROM AUTHOR]

• Ternary mixture with double azeotropes was separated by pressure-swing batch distillation. • Integrated quasi-continuous triple-column process was further proposed and analyzed. • Multi-objective optimization algorithm was adopted to realize the optimization of process. • Thermal integration technology was used to further reduce energy consumption. An multivessel double-column pressure-swing batch distillation process and a triple-column integrated quasi-continuous distillation process were designed to separate ternary mixtures with double azeotropes of ethyl acetate-methanol-water. The process feasibility was analyzed based on ternary phase diagram. Based on a production capacity of 100 kmol/batch, the corresponding control strategy was proposed to achieve the effective separation of the mixture. Taking the minimum total annual cost as the objective function, the process parameters of the double-column process were optimized to determine the optimal operating pressure. Exergy loss of distillation column was calculated to evaluate the thermodynamic performance of the process. To further improve the separation efficiency of the process, a third column was integrated in the double-column batch distillation process to separate the methanol-water mixture directly. Combined with sequential iterative optimization sequence and multi-objective optimization algorithm, the triple-column process parameters were optimized, and the trade-off between equipment cost and carbon dioxide was realized. Thermal integration technology was adopted to further reduce the energy consumption of the triple-column process. The results show that the carbon dioxide emissions and total annual cost of the double-column process are 1.323 × 106 kg/y and 2.107 × 105 $/y. The purity of ethyl acetate and water was 99.9 mol%. While the purity of methanol was 99.5 mol%. The total annual cost and emission of the triple-column process were 1.993% and 1.890% higher than that of the double-column process, respectively, but the methanol purity was further improved to 99.9 mol%. Compared with the double-column process, the total annual cost and carbon dioxide emissions of the triple-column process with thermal integration technology were reduced by 1.281% and 17.337%. [ABSTRACT FROM AUTHOR]

Economic and environmental comparison of different processes for separating ternary mixtures with three binary minimum boiling point homoazeotropes by double column batch distillation. [Display omitted] • Double column batch distillation was used to separate ternary mixture with three binary azeotropes. • The three processes were compared from angle of economy and environment. • The heat integration of batch distillation process was considered. • The process theoretical feasibility was analyzed based on the phase diagram. Based on the continuous two columns distillation technology, it is difficult to separate the ternary mixture of n-hexane/ethanol/butanone, which contains three binary minimum boiling point homoazeotropes. Through analyzing characteristics of batch distillation and the phase behavior, it is feasible to achieve high purity separation of this kind of complex mixture by two-column batch distillation. Three sequential two-column batch distillation processes including Process A (Double columns with series operation), Process B (Double columns with parallel-then series operation) and Process C (Single column-then double columns process) were designed and analyzed in this work. The processes were evaluated and optimized from the aspects of economy and environment. In terms of economy, environment impacts and operating time, Process B is prior to Process A and Process C. Based on the thermodynamic analysis of the column, the heat integration problem of Process B is considered, which includes a self-preheating scheme at first step, and a heat exchange scheme in which high-pressure column top vapor provide part of the heat to low-pressure column bottom at second step. Compared with the unimproved Process B, the operating cost of the improved Process B can be reduced by 28% and TAC can be reduced by 3% at step 1. The operating cost of the improved Process B can be reduced by 30% at step 2. [ABSTRACT FROM AUTHOR]

• 1-chlorobutane and butyl propanoate are selected as entrainers. • The VLE data for n -hexane/acetone + entrainers were measured. • The measured VLE data were correlated by the Wilson, UNIQUAC and NRTL models. • The suitable entrainers were explored by relative volatility and x - y diagram. Acetone and n -heptane are widely applied in pharmaceutical industry as benign solvents and are observed in the wastewater. Because acetone and n -hexane can form an azeotropic mixture, it is impossible to recover acetone and n -heptane with high purity from the wastewater using conventional distillation. In this research, for separating the azeotrope (acetone + n -heptane) by homogeneous extractive distillation, 1-chlorobutane and butyl propanoate were chosen as the intermediate and heavy boiling entrainers. The isobaric vapour-liquid equilibrium (VLE) behaviour for the three binary systems (acetone + 1-chlorobutane), (butyl propanoate + acetone) and (n -heptane + butyl propanoate) were reported at 101.3 kPa. The values of the excess Gibbs energy ( G E) were calculated to explore the nonideal of the systems. The thermodynamic consistency of the determined VLE values was checked by the van Ness and Herington tests. In addition, the determined VLE data were fitted by the UNIQUAC, Wilson, and NRTL models. The parameters of those models were regressed, which are helpful for simulating the separation process with the intermediate and heavy boiling entrainers by extractive distillation. [ABSTRACT FROM AUTHOR]

• The entrainers were explored by selectivity, relative volatility and x - y diagram. • Butyl propanoate and butyl butanoate were selected as entrainers. • The VLE data for n -hexane/cyclohexane + entrainers were measured. • The measured VLE data were correlated by the Wilson, UNIQUAC and NRTL models. For synthesis of ethyl propionate with ethanol and propionic acid as raw materials, n -hexane and cyclohexane are usually used as water-carrying agents. However, ethanol can form the minimum boiling azeotropic mixtures with n -hexane and cyclohexane. For separating the binary azeotropic mixtures (ethanol + n -hexane) and (ethanol + cyclohexane) by extractive distillation, in this work, the suitable entrainers were explored by selectivity and relative volatility, and the influence of the selected entrainers on the azeotropic system phase behaviour was analyzed. Based on the selection results, butyl propanoate and butyl butanoate were adopted as the entainers. The vapour-liquid equilibrium (VLE) data for the four binary mixtures (n -hexane + butyl propanoate), (n -hexane + butyl butanoate), (cyclohexane + butyl propanoate) and (cyclohexane + butyl butanoate) were investigated. Furthermore, the VLE data was validated using the van Ness and Herington tests. Also, the experimental data was fitted by the Wilson, UNIQUAC and NRTL models. The binary interaction parameters were optimized for the separation process design and simulation. [ABSTRACT FROM AUTHOR]

• p -Xylene and butyl butyrate were selected to separate ethyl acetate + n -heptane. • The VLE data for the systems (ethyl acetate/ n -heptane + solvents) were measured. • The measured VLE data were correlated by the NRTL, UNIQUAC and Wilson models. Since ethyl acetate and n -heptane can form the lowest azeotropic mixture, p -xylene and butyl butyrate were selected as extracting agents to separate the azeotrope (ethyl acetate + n -heptane) using extractive distillation. The binary isobaric vapour-liquid equilibrium (VLE) data for the binary systems (ethyl acetate + p -xylene), (ethyl acetate + butyl butyrate) and (n -heptane + butyl butyrate) were determined at 101.3 kPa using a Rose-Williams still. The measured experimental data were checked by the van Ness method and Herington test. Besides, the determined VLE data were fitted by the NRTL, UNIQUAC and Wilson thermodynamic models. The calculated root-mean-square deviation values of the temperature and vapour phase mole fraction are no more than 0.19 K and 0.0053, respectively. The results showed that three thermodynamic models can be used to correlate the determined experimental data for the three binary systems. Meanwhile, the binary interaction parameters for the three thermodynamic models were optimized, which are a great help for the optimization and simulation of separating the azeotropic mixture (ethyl acetate + n -heptane). [ABSTRACT FROM AUTHOR]

Isopropyl alcohol and ethyl acetate can be used to produce degradable and renewable fuel. Since isopropyl alcohol + ethyl acetate can form an azeotropic mixture, it is a tough task to separate the binary mixture by general distillation. In this work, extractive distillation process with N, N-dimethylformamide and dimethyl sulfoxide as entrainers was adopted to separate this azeotrope. The binary and ternary vapor-liquid equilibrium data for (isopropyl alcohol + N, N-dimethylformamide), (ethyl acetate + dimethyl sulfoxide), (isopropyl alcohol + ethyl acetate + N, N-dimethylformamide) and (isopropyl alcohol + ethyl acetate + dimethyl sulfoxide) were determined under 101.3 kPa. Meanwhile, the interaction energies between the molecules were calculated to provide the theoretical insight into the separation of the azeotrope of (EA + IPA) by the entrainers. In addition, the NRTL, UNIQUAC and Wilson models were used to fit the determined binary VLE data. The ternary VLE data for (isopropyl alcohol + ethyl acetate + N, N-dimethylformamide) and (isopropyl alcohol + ethyl acetate + dimethyl sulfoxide) were predicted using the NRTL, UNIQUAC and Wilson models with the parameters regressed from the experimental data. [ABSTRACT FROM AUTHOR]