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Novel distillation configurations continue to appear in the literature despite the predictions made many decades ago that distillation had attained the status of a mature and stagnant technology needing no further research and development. The driving force for improvement has traditionally been energy conservation, but political decisions related to environmental and sustainability issues have provided additional motivation for improving the efficiencies of chemical and petroleum processes. Since distillation columns require a large fraction of the total energy used in these processes, there is a significant incentive to improve process efficiency. An excellent example of this activity is a paper in which a conventional three-column extractive distillation configuration is compared with a novel two-column process that includes a single decanter. The chemical separation system is a ternary mixture of methanol, water and toluene, which is important in the pharmaceutical industry. The new configuration reduces total annual cost by 50%. The purpose of this paper is to propose a simple modification of the two-column configuration that reduces energy costs by an additional 14% by using two decanters in series operating at different temperatures. • A modified two-column configuration for separating a mixture of methanol, water and toluene is explored. • Using two decanters in series operating at different temperatures saves energy and capital costs. [ABSTRACT FROM AUTHOR]

This work explores the integration of dynamic simulation with the concept of protection layers to assess the dynamic safety of an extractive distillation operation. This particular study concentrates on the separation process of acetonitrile from water using ethylene glycol as the entrainer. It appraises the efficacy of different independent protection layers — ranging from basic process control systems, critical alarms, and operator interventions, to safety instrumented systems and pressure relief valves — against various potential risk scenarios. The study considers scenarios leading to overpressure situations, such as failures in the condenser system, surges in hot steam supply, or severe disturbances in feed. Using Aspen Dynamics for detailed dynamic simulation and safety evaluation, the study examines the response and effectiveness of each protection layer meticulously. It employs a scenario-based safety analysis to gauge the dynamic safety performance and the effectiveness of the protection layers. The research underscores the value of scenario analysis in grasping the dynamic responses of the distillation process and the spread of irregularities through the system. This understanding is crucial for estimating the process safety time and for crafting an efficient safety system. [Display omitted] • Dynamic rigorous simulation delves into the extractive distillation process. • Faults are categorized by protection layers for dynamic scenario simulation. • Analysis reveals condenser malfunctions as the main overpressure source. • Protection layers effectively mitigate these overpressure risks. [ABSTRACT FROM AUTHOR]

The extractive distillation is a commonly used method for the separation of azeotrope in the chemical industry. In this article, we investigate the safety issue of the extractive distillation process for targeted audience process engineers from the perspective of process safety. We conduct inherently safer design and multi-objective optimization of extractive distillation processes for the separation of methyl acetate/methanol via computer-aided molecular design, thermal hazard analysis, and multi-objective genetic algorithm. Firstly, the entrainers with good safety and separation performances are pre-screened by computer-aided molecular design (CAMD) based on flash point and entrainer selectivity. Then the entrainers with top-ranking separation performance are manually screened based on vapor-liquid equilibria. Next, the Pareto front solution is obtained by optimizing both safety and economic objective functions using a multi-objective genetic algorithm. Finally, the thermal hazard of the entrainer is also investigated via DSC (Differential scanning calorimetry) test. Finally, the optimization result and thermal hazard investigation demonstrate that 1,3-propanediol is inherently safer than dimethyl sulfoxide (DMSO) as a common entrainer in terms of not only a fire hazard but also a thermal hazard for the separation of methyl acetate/methanol mixture. The optimal TAC using 1,3-propanediol as an entrainer is 3.72% lower than that of dimethyl sulfoxide, and the corresponding GISI is 57.73% lower than that of dimethyl sulfoxide. As for DMSO, thermal decomposition can occur near its normal boiling point (189 ℃) and 1,3-propanediol, can be thermally stable over 330 ℃. [ABSTRACT FROM AUTHOR]

The separation of ternary azeotropes with a high content of one component using extractive distillation is energy intensive, and the introduction of preconcentration can significantly improve process economy. In this paper, the conventional three-column extractive distillation (TCED), four-column extractive distillation (FCED) with preconcentration, and three-column extractive distillation with integrated distillation column (TCED-IDC) are established and economically optimized to minimize the total annual cost (TAC) for recovering ethyl-acetate (EAc) and ethanol (EtOH) from wastewater containing a large amount of water. The preconcentration and solvent recovery functions can be integrated in IDC. Following that, the vapor recompression heat pump (VRHP) is introduced to further reduce energy consumption for the TCED-IDC process. The two VRHP-TCED-IDC processes are correspondingly designed. Simultaneously, the processes proposed are evaluated in terms of economy, energy consumption, environment and exergy destruction (4E analysis). The environmental analysis is performed via calculating Global Warming Potential (GWP) index using Life Cycle Assessment method. The two VRHP-TCED-IDC processes demonstrate superior performances with regard to 4E analysis. The most efficient VRHP-TCED-IDC process reduce over 32.0 %/16.0 %/6.8 % of TAC, 53.4 %/42.4 %/33.7 % of energy consumption, 62.0 %/53.0 %/45.9 % of GWP, and 49.7 %/35.7 %/29.3 % of exergy destruction compared to the TCED/FCED/TCED-IDC processes, respectively. • The separation of ternary azeotropes with one high-content component is studied. • The integration of preconcentration and solvent recovery functions is investigated. • Vapor recompressions heat pumps are introduced to reduce energy consumption. • Processes are evaluated using economic, energy, environmental, and exergy analyses. • The environmental analysis is preformed via Life Cycle Assessment method. [ABSTRACT FROM AUTHOR]

Cyclohexane and isopropyl alcohol are widely used in the chemical and pharmaceutical industries. There is a strong industrial need for the refinement of cyclohexane and isopropyl alcohol. In this study, the recovery of cyclohexane and isopropyl alcohol from wastewater was carried out sustainably and efficiently by extractive distillation. The suitability of ethylene glycol as entrainer was determined by relative volatility analysis. The process was optimized via multi-objective optimization, and the extractive distillation process obtained optimal parameters and process scheme. Finally, a comprehensive analysis was conducted to evaluate the economic, environmental and exergy efficiency of different process schemes. The results show that the extractive distillation coupled pervaporation technology has a 14.07% lower total annual cost than extractive distillation, and the pervaporation technology reduces gas emissions by 15.65% compared to the extractive distillation. This work explores the recovery of cyclohexane and isopropyl alcohol from wastewater by different process schemes, which has certain guiding significance for the sustainable and efficient separation of ternary azeotrope. [Display omitted] • Multi-objective optimization was used to obtain optimize parameters of process. • A pervaporation model of EG dehydration was established to realize solvent recovery. • The different energy saving intensification schemes were studied. • Detailed performance evaluation and analysis of process was done. [ABSTRACT FROM AUTHOR]

In the process of producing isopropanol (IPA) by direct hydration of propylene, a mixture of IPA, n-propanol (NPA) and H 2 O is formed. In order to obtain high purity IPA and NPA, extractive distillation technology can be used to separate these three components. In this paper, Based on the COSMO-RS model, 1-ethyl-3-methylimidazolium dicyandiamide ([EMIM][DCA]) was selected as the extractant for extractive distillation in ionic liquids. The extractive distillation process for the separation of IPA-NPA-H 2 O system with ethylene glycol (EG) or [EMIM][DCA] as extractant was designed and optimized by multi-objective genetic algorithm. Process simulation results show that the process using [EMIM][DCA] can reduce total annual cost by 44.635% and total gas emission by 29.873% compared with the traditional organic solvent EG as extractant. These results show that [EMIM][DCA] is a good extractant, which can reduce the gas emission and energy consumption of the distillation process. In addition, we further explored the separation mechanism of the system at the molecular level by analyzing the σ-curve and the intermolecular interaction energy. • Based on COSMO-RS model, [EMIM][DCA] was selected as extractant. • The reason why EG and [EMIM][DCA] can break the IPA-H 2 O azeotrope was revealed. • Optimized the extractive distillation process with EG or [EMIM][DCA] as entrainers. • [EMIM][DCA] can realize the energy saving and emission reduction. [ABSTRACT FROM AUTHOR]

Incorporating sustainability metrics into the design of economically viable and environmentally responsible processes is crucial for achieving overall sustainability. Reactive distillation has been widely studied in this context, but studies on extractive distillation have been limited, particularly in ternary azeotropic separation. This study aims to address this gap by integrating green sustainability metrics into extractive distillation through multi-objective optimization, considering economic, environmental, and safety indicators simultaneously. The results showed that our approach resulted in greater sustainability improvements compared to a sequential approach, where optimization was initially based on economic objectives with the environmental and safety aspects evaluated subsequently. The optimized configurations for ethanol, tetrahydrofuran, and methanol separation using three column extractive distillation and four column extractive distillation in this work showed significant sustainability improvements compared to their base cases. Specifically, three column extractive distillation outperformed four column extractive distillation in energy, economic, environmental, and safety performance by 18%, 4%, 8%, and 18%, respectively. • Incorporation of sustainability metrics for design of extractive distillation (ED). • Multi-objective optimization (MOO) involving economic, environmental, and safety. • Result comparison with MOO using capital and operational cost as objective function. • Result comparison against sequential approach for sustainability evaluation. • Present approach provides better sustainability relative to a sequential approach. [ABSTRACT FROM AUTHOR]

In the chemical and petrochemical industries, an azeotropic mixture of acetone/methanol/butanone/tert-butanol needs to be separated for high-purity products. Following a previous work in which an energy-saving process composed of two extractive dividing-wall columns (EDWCs) was developed for the quaternary system, this paper focuses on the issue of dynamic control for this process. Several control strategies in combined with temperature control, temperature-difference control and composition control are established to maintain the purity of all products in the face of disturbances in feed flow and feed composition. Dynamic simulations demonstrate that a conventional temperature control structure provides very poor control while a control strategy that used three-temperature-difference control for both EDWCs is the most effective. • An effective control strategy is proposed for two extractive dividing-wall columns process of quaternary azeotropic mixtures. • Multiple temperature differences controls are designed to control the process. • A variety of feed disturbances are used to test control strategies. [ABSTRACT FROM AUTHOR]

The efficient separation of azeotropes is of great significance for the effective recovery and utilization of chemical raw materials and environmental protection. This study investigated the separation efficiency and mechanism of deep eutectic solvents (DESs) with different combinations and ratios of hydrogen bond acceptors (HBA) and hydrogen bond donors (HBD) for cyclohexane/ethanol azeotropic systems. Through vapor-liquid phase equilibrium experiments, the effects of different DESs and different HBD: HBA molar ratios as solvents on the phase behavior of cyclohexane/ethanol azeotropic system were studied, and different combinations and molar ratios of DESs with the best separation performance were obtained. The effective separation of azeotropes by DESs is primarily due to the stronger molecular surface electrostatic potential of ethanol compared to that of cyclohexane, which results in a stronger interaction between the DESs and ethanol. Finally, through process simulations, a cyclohexane/ethanol extractive distillation separation process using a DES as the main solvent was established. The results showed that the separation effect of DESs increased with the increase of the interaction force between DESs and ethanol, achieving efficient recovery of chemical raw materials. This study established a safe and efficient separation process using DESs, which is of great significance for environmental protection and the development of safety processes. [ABSTRACT FROM AUTHOR]

This work investigates an efficient and sustainable process for recovering n-propyl acetate and n-propanol from wastewater via extractive distillation coupled with pervaporation (PV). The selection of potential extractants is based on the equilibrium data between the system and the extractants in vapor-liquid phase. For the ternary extractive distillation process, we optimize it using the Non-Dominated Sorting Genetic Algorithm II with the objectives of minimizing the total annual cost and gas emissions. The PV model is integrated with the distillation process to enhance solvent recovery, while an energy-efficient scheme combined with heat integration technology and heat pump improves separation efficiency. Economic, environmental and exergy analyses are conducted to evaluate feasibility, revealing that coupling extractive distillation with PV enhances economic and environmental benefits compared to basic processes. The combination of heat pump assisted heat integration technology further improves the economy performance, environmental protection and thermodynamic efficiency, and the process selection needs to be balanced according to the actual industry. [ABSTRACT FROM AUTHOR]

Sec-butyl alcohol (SBA), a common chemical intermediate, is used as an anti-emulsion, dye dispersant, industrial detergent, and raw material to produce methyl ethyl ketone. To further reduce the energy consumption and production cost of the hydrolysis of sec-butyl acetate (SBAC) to SBA, a reactive distillation coupled with extractive distillation using a mixed entrainers process was proposed in this study. Based on the relative volatility curve and quantum chemical calculations, EG and DMSO were selected as potential entrainers. Based on the total annual production cost, the appropriate ratio of mixed solvent is obtained (EG: DMSO = 9:1). The thermal coupling distillation technology is introduced into the proposed process to achieve energy-saving further. The results showed that the thermodynamic efficiency of the thermal coupling process using mixed entrainers increased by 18.02%, the total annual cost is saved by 15.18%, and CO 2 emissions were reduced by 391.82 kg/h compared to the process using single DMSO entrainers process. [Display omitted] • Quantum chemical calculation and VLE data were used to screen mixed extractants. • Combination of mixed extractant and thermal coupling process can effectively save energy. • The thermodynamic efficiency of the novel process can be improved by 18.02%. [ABSTRACT FROM AUTHOR]

In order to effectively separate complex azeotropic mixtures, it is crucial to consider economic, environmental, and safety factors during the process design and optimization. This study presents a systematic approach to separate a ternary azeotropic mixture of tetrahydrofuran, methanol, and water by employing multi-objective optimization and multi-criteria decision making. Two energy-efficient configurations, i.e., double-column reactive extractive distillation and reactive-extractive dividing wall column, are proposed by integrating reaction and extractive distillation in a single unit. The developed processes are then optimized using a multi-objective particle swarm optimization algorithm, considering the aforementioned factors. Finally, a multi-criteria decision making technique is applied to rank the Pareto frontier solutions obtained from the optimization process, using a combination of gray relational analysis and entropy weight method. Compared to the base case, the double-column reactive extractive distillation process exhibits a significant reduction in total annual cost (59.39 %) and CO 2 emissions (61.75 %). Through comprehensive evaluation, the double-column reactive extractive distillation process is found to be the most effective separation solution among the proposed and existing processes. This systematic approach can be extended to other complex aqueous azeotropic systems for their design, optimization, and decision making. [Display omitted] • A systematic approach for separating complex azeotropic mixtures is proposed. • Two intensified reactive-extractive distillation schemes are developed. • The developed processes are optimized via MOPSO algorithm. • The GRA combined with entropy weight is used for multi-criteria decision making. [ABSTRACT FROM AUTHOR]

Reclamation of mixed refrigerants can effectively reduce high global warming potential (GWP) fluorinated gases (F-gases) emissions. Two organic liquids (OLs), Dimethylformamide (DMF) and N, N-Dimethylacetamide (DMAC), were proposed to explore the possibility of separating high GWP and near-azeotropic mixture R410A (50 wt% R32 (difluoromethane) + 50 wt% R125 (pentafluoroethane)) by absorption. Solubilities of R125 in DMF and DMAC were measured from 283.15 to 333.15 K and well correlated with the five-parameter non-random two-liquid (NRTL) activity coefficient model. Ideal selectivity for R32 + R125 of DMAC were higher than that of DMF. Five ionic liquids (ILs) and DMAC on the Pareto front showed good overall performance (integration of capacity and selectivity) for separating R410A, and in the area below the Pareto front, the overall performances of the other solvents were not as good as those from the Pareto front. Subsequently, based on DMAC, 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF 6 ]), 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide ([EMIM][Tf 2 N]) and 1-ethyl-3-methylimidazolium thiocyanate ([EMIM][SCN]), the extractive distillation processes for R410A separation were simulated and evaluated in Aspen Plus. Results showed DMAC was a suitable choice of extractant nowadays due to the lower viscosity and consumption than ILs and the mature corresponding R410A separation process. ILs may be the mainstream extractant for R410A separation in the future, once the price of some ILs such as [BMIM][PF 6 ] can be reduced to $30/kg, the separation process using ILs as extractants will cost less than that of DMAC. Heat pump technology can be further applied for energy integration in the corresponding process of ILs with high ideal selectivity such as [EMIM][SCN]. Thermodynamic and economic analysis of OLs and ILs could provide the key information for the separation of commercial refrigerant R410A, which can also be used as a benchmark to screen more efficient extractants. [Display omitted] • DMF and DMAC were developed for extractive distillation separation of R410A. • The preferential absorption of R125 in DMAC and DMF was found. • DMAC was a suitable extractant due to the lower viscosity and consumption than ILs. • ILs may be the mainstream extractant once the price of ILs can be reduced to $30/kg. [ABSTRACT FROM AUTHOR]

A correlation model was explored and established for the first time, linking the properties of entrainers to the process economics of extractive distillation separation for ternary azeotropes. Firstly, the extraction process of ternary azeotrope (methyl tert-butyl ether/ethanol (EtOH)/water) with common entrainers was optimized using a multi-objective optimization method based on a genetic algorithm. The optimal process parameters were obtained, and dimethyl sulfolone emerged as the best entrainer for the system. An economic correlation model was developed using machine learning to link the properties of entrainers and total annual cost (TAC). The model exhibited a determination coefficient of 0.993 and a single percentage error of less than 2% for each data set, indicating a significant fitting degree and prediction accuracy. The feasibility of selecting the optimal entrainer and calculating the economic benefit of the model was verified through another ternary azeotrope system (i.e., tetrahydrofuran/EtOH/water). The model provides valuable insights into energy savings and entrainer screening in extractive distillation. Additionally, the influence of the heat integration process with different entrainers on the economic benefit was analyzed, and the optimum entrainer changed to glycerol after the heat integration process. This finding suggests that determining the optimum entrainer should consider the possible heat integration process design. Finally, the relationship between the intermolecular interaction mechanism and separation effect was revealed through quantum chemical calculations. [ABSTRACT FROM AUTHOR]

Considerable effort is currently being put towards process intensification to design more sustainable and energy-efficient processes. Hybrid distillation-membrane processes are prime examples of such intensified processes. In this work, different strategies are presented for how to handle the complexity of the membrane network of the hybrid process in terms of initialisation and convergence for simulation and optimisation. A superstructure approach for optimisation of membrane networks within hybrid processes is presented and verified. The energy consumption and economic performance of a hybrid distillation-pervaporation process, as well as that of the corresponding extractive distillation process, to separate a minimum-boiling azeotropic mixture are compared for different feed compositions. The impact of membrane properties and cost is also briefly considered. The results show that the total heat duty for the hybrid process is always lower than that of the extractive process for the system considered, confirming that the hybrid process is more energy efficient. In terms of total annualised cost, however, the hybrid process is found to be more economically attractive at lower feed compositions, while the extractive process is preferred for higher compositions. [Display omitted] • Superstructure design and optimisation of hybrid distillation-membrane processes. • Simultaneous optimisation of membrane network and distillation column. • Comparison between hybrid process and extractive distillation process. • Evaluation based on feed compositions and key membrane parameters. [ABSTRACT FROM AUTHOR]

A combination of molecular modelling and experiments was conducted to study the separation of acrylic acid and propionic acid through extractive distillation with polar aprotic entrainers. It was found that acrylic acid and propionic acid can be efficiently separated through extractive distillation with a polar aprotic entrainer, resulting in the entrainment of acrylic acid and making propionic acid the most volatile compound. Vapour-liquid equilibrium experiments were conducted with 25 wt% acrylic acid, 25 wt% propionic, and 50% wt% entrainer. Dimethyl sulfoxide (DMSO) was found to induce the highest relative volatility of 1.56 at 25 mbar, which agrees well with the predicted value of 1.66 using the simulation software COSMO-RS. The difference in pKa (ΔpKa = 0.63) between acrylic acid and propionic acid is the main cause for the enhanced relative volatility. The corresponding difference in hydrogen bonding strength was calculated using COSMO-RS to result in ΔE = 1.8 kJ/mol at 25 °C between acrylic acid and propionic acid with the total mixture. When dodecane was selected as an entrainer, acrylic acid became the most volatile compound instead of propionic acid. This is explained by the fact that propionic acid has two extra hydrogen atoms available to have a Van der Waals interaction with the carbon atoms of dodecane. The difference in total Van der Waals interaction between the two carboxylic acids in the mixture with dodecane is 1.34 kJ/mol at 25 °C. This difference results in a relative volatility of 0.91, which is too small to be exploited in a distillation process, and it was concluded that for this mixture, DMSO was the best entrainer in the study. [Display omitted] ● Acrylic acid and propionic acid were separated by extractive distillation (ED). ● COSMO-RS and Spartan calculations predicted and explained relative volatilities. ● The ΔpKa of 0.63 is sufficient for entrainers to induce relative volatility in ED. ● DMSO induced a relative volatility of 1.56 at 25 mbar using 50 wt% entrainer. ● Alkanes reverse the relative volatility to 0.9. [ABSTRACT FROM AUTHOR]

Aiming at achieving the high-purity recovery of ethanol (EtOH) and tert-butanol (TBA) from industrial waste with low carbon emission, the processes intensified by hybrid reactive distillation combined with pressure-swing distillation (PSD) and extractive distillation (ED) are proposed in this work. The optimum procedure of the sequential iterative method is applied to select an optimal pressure for these hybrid reactive distillation processes. From the economic and environmental impact perspective, the results indicated that the reactive-extractive-/pressure-swing hybrid distillation has significant economic and environmental advantages. The REPDC-REPC (reactive-extractive-/pressure-swing hybrid distillation) process is the most potential and competitive, saving 56.47% TAC and reducing 69.23% CO 2 emissions, and has 67.51% thermodynamic efficiency, minor exergy destruction, and most enormous total exergy efficiency. Meanwhile, the work also demonstrates that the operating pressure of the column plays an important role, which positively affects the energy saving of the recovery process. [ABSTRACT FROM AUTHOR]

Energy-saving extractive distillation for separating ethanol and 1,4-dioxane from the industrial effluent is proposed. From the point of COSMO-SAC model and thermodynamic insights, appropriate entrainer is screened. Ethylene glycol (EG) is chosen in direct extractive distillation process. Subsequently, it is observed that increasing the pressure can make the azeotropic point of ethanol and 1,4-dioxane disappear. Thus, both EG and dimethyl sulfoxide (DMSO) are used as entrainers in indirect extractive distillation (IED) process. The entropy generation of different sections of each column is analyzed. And then, heat integration and heat pump technologies are used to reduce more energy consumption. The comparison results show that the total annual cost (TAC), total energy consumption, CO 2 emissions and entropy generation of IED process with DMSO as entrainer (IED-DMSO) is smaller than those processes with EG as entrainer. The IED-DMSO process in combination with heat integration performs best, the TAC is reduced by 41.96%, energy consumption is reduced by 50.28%, CO 2 emissions is decreased by 50.28% and entropy generation is decreased by 57.46% comparison with the IED-EG process. [ABSTRACT FROM AUTHOR]

As a new gasoline additive, methyl tertiary amyl ether (TAME) can improve the antiknock performance and quality of gasoline. This study uses an energy-saving process for separating TAME/methanol (MeOH)/H 2 O by pressure-swing extractive distillation with different entrainers based on multi-objective optimization and 4E analysis. The 1entrainers are screened by the difference in relative volatility of components under different entrainer conditions, and the electrostatic potential of the molecular surface of the system and entrainers are analyzed. Multi-objective optimization of the pressure swing extractive distillation process with 5 different entrainers is carried out based on the generation non-dominated sorting genetic algorithm (NSGA-Ⅱ) optimization scheme, and the Pareto frontier is optimized by the minimum distance method. The results indicate that the extraction schemes of 1,3-propanediol (PDO) and dimethyl sulfoxide (DMSO) have excellent economic and environmental benefits through comprehensive analysis. As an effective means of process intensification, the application of heat pump technology can further reduce process costs and environmental pollution. The coefficient of heating performance (COP) is used to find the most suitable pairing route for heat pump-assisted processes, achieving the goal of reducing gas emissions and energy use. Then, different processes are evaluated in terms of economy, energy consumption, environment, and exergy loss. The results show that the process intensification scheme based on heat pump technology can effectively improve the economic and environmental benefits of the process, reducing the annual total cost (TAC) and gas emissions by 9.19% and 23.55%, respectively. This study provides the selection and reference for azeotrope separation of TAME and recycling of wastewater. [ABSTRACT FROM AUTHOR]

• Rational functions were trained as VLE surrogate models with thermodynamic consistency. • Superstructure-based extractive distillation process synthesis was solved within a few seconds. • A multi-level solvent screening was performed for ethylbenzene/styrene separation. • C 2 H 2 Br 4 was found to reduce cost by 27.9 % compared to the benchmark sulfolane. When designing extractive distillation processes, using selectivity and capacity at infinite dilution alone is hard to identify the real optimal solvent with minimal process cost. To overcome this problem, a new process-driven solvent screening approach is developed. As simple and reliable surrogate models, rational functions (algebraic fractions such that the numerator and the denominator are polynomials) and multivariate polynomials (a subset of rational functions) are trained to interpolate vapor–liquid equilibria with thermodynamic consistency. The surrogate models can directly be embedded into superstructure-based extractive distillation process design to obtain optimal solutions within a few seconds. This enables to evaluate the real process performance of numerous solvents efficiently. Incorporating the accelerated process design strategy, a multi-level solvent screening framework is proposed and exemplified for the separation of a close-boiling mixture ethylbenzene/styrene. The solvent C 2 H 2 Br 4 ultimately enables a cost reduction of 27.9 % compared to the industrially used benchmark solvent sulfolane. [ABSTRACT FROM AUTHOR]

We integrate equilibrium and rate-based models to formulate a hybrid optimization scheme for designing an ionic liquid-based extractive distillation process for mixed-refrigerant separation. The equilibrium model assumes vapor–liquid equilibrium at each stage but challenges arise with low-volatility, high-viscosity solvents, which drive the system away from equilibrium. The rate-based approach considers mass and heat transfer rates, giving more accurate representation. We compare the two models for separating R-410A, an azeotropic mixture of R-32 and R-125, using [EMIM][SCN] ionic liquid as entrainer. Analyzing over 4300 simulations with various dimensionality reduction and topological analysis techniques, we find that predictions from the two models exhibit similar trends, but the overestimation in equilibrium-based purities sometimes leads to infeasible process designs. The proposed optimization algorithm thus combines the strengths of the two models to locate feasible and optimal designs. • Comparison of equilibrium and rate-based models for solvent-based gas separation. • Model similarity analysis using PCA, distance metrics, and Euler Characteristic. • Equilibrium models overestimate model predictions but capture trends of rate-based models. • Hybrid optimization using both models with new constraint refinement and update rules. [ABSTRACT FROM AUTHOR]

• Novel and energy-saving heat pump assisted extractive distillation processes are designed to separate EA-HEP azeotrope. • The σ-profile analyzes the intermolecular interaction at the molecular level. • The sequential iteration method is used to optimize the processes and get the minimum TAC. • The TAC, energy consumption and CO 2 emission of HPED-WITH process decreases by 16.78 %, 28.14 % and 41.83 %, respectively. In the pharmaceutical and fine chemical industries, azeotropic mixtures like ethyl acetate (EA) and n-hexane (HEP) are produced. Effective separation and purification are essential for recycling resources and protecting the environment. This study investigates the design and optimization of energy-efficient extractive distillation processes for separating EA and HEP. N-methylpyrrolidone (NMP) and p-xylene (PX) were selected as extractants. Their effectiveness was validated through vapor liquid equilibrium (VLE) studies, and their interaction mechanisms were clarified using σ-profile analysis. Extractive distillation processes using NMP and PX as extractants (ED-NMP and ED-PX) were developed and evaluated based on total annual cost (TAC), energy consumption, and CO 2 emissions. The results showed that the ED-PX process outperformed the ED-NMP process. Additionally, integrating a heat pump with an overhead steam preheater further enhanced all performance metrics, reducing TAC, energy consumption, and CO 2 emissions by 16.78 %, 28.12 %, and 41.83 %, respectively. This study provides valuable insights for the separation and purification of EA and HEP. [ABSTRACT FROM AUTHOR]

• A novel cryogenic distillation-based CO 2 capture method in LNG process is proposed. • The azeotropic characteristics of CO 2 -C 2 H 6 is utilized to avoid CO 2 freeze-out. • The proposed process can remove up to 17 % of CO 2 to less than 50 ppm. • The integrated "LNG + C 2 H 6 recovery + CO 2 removal" minimizes energy consumption. • The exergy efficiency of the system is higher than 50%. Cryogenic CO 2 capture technique is superior to other CO 2 capture methods in terms of potential environmental protection, because it uses no chemical solvent or membrane materials that need regular replacement. However, the freezing problem of CO 2 makes it difficult to achieve CO 2 capture through simple gas–liquid separation, and the existing cryogenic CO 2 capture techniques often require a specially designed separation equipment. In addition, cryogenic CO 2 capture is generally considered a method with high energy consumption due to the need for refrigeration. This study proposes a cryogenic distillation-based CO 2 capture method for natural gas with high ethane content, such as shale gas and oilfield associated gas. This method utilizes the azeotropic characteristics of CO 2 and ethane to avoid CO 2 freeze-out and the energy consumption for CO 2 capture is minimized through process integration with natural gas liquefaction and ethane recovery. The proposed system uses the propane precooled mixed refrigerant process to provide the required refrigeration, and it is simulated in Aspen HYSYS and optimized by a combined method of a genetic algorithm and sequential optimization. The results show that the proposed process can remove up to 17 mol% of CO 2 to less than 50 ppm. With extractive distillation, 99.50 % of the ethane in the feed gas is recovered with a purity of 99.50 mol%. The optimal results corresponding to the maximum allowable CO 2 content to avoid its freeze-out (with a solubility margin of 500 ppm) show that when ethane content is 2–20 mol%, the specific power consumption of the system is about 0.43 kWh/Nm3(NG) with an exergy efficiency higher than 50 %. The proposed process achieves energy-saving and efficient CO 2 capture method for natural gas with high ethane content. [ABSTRACT FROM AUTHOR]

• Energy-saving extractive distillation for separating dimethyl carbonate/methanol presented. • O-Xylene is selected as suitable entrainer for its relative low boiling point, price, and toxicity. • A lab-scale extractive distillation is modeled, analyzed, validated and further be scale-upped. • The optimized extractive distillation offers marked economic benefit and CO 2 emission reduction. The pressure-swing distillation traditionally used in the industry for separating dimethyl carbonate/methanol (DMC/MeOH) commonly suffers from high energy consumption and challenges in achieving high-purity separation due to the existence of pinch zone. Hence, energy-saving extractive distillation system is explored to achieve the high-purity separation of DMC/MeOH azeotrope. With the analyses of isovolatility and residue curve maps based on Wilson model calibrated by vapor–liquid equilibrium experimental data, an extractive distillation process using O-Xylene (OX) as the most suitable entrainer were modeled and experimentally validated. Furthermore, design, optimization, and comparison of an extractive distillation process and a pressure-swing distillation process for producing 10000 t DMC/a are investigated. It is demonstrated that the extractive distillation process presents significant economic and emission advantage, specifically with 34.66 % and 26.95 % reductions in operating cost (OC) and in total annual cost (TAC) respectively, as well as 42.53 % reduction in CO 2 emissions. This work should provide a feasible and promising approach to energy saving, low-carbon, and high-purity separation of DMC/MeOH azeotrope. [ABSTRACT FROM AUTHOR]

• Heat pump-assisted (reactive) dividing-wall column for propionic acid recovery. • Cost-effective and energy-efficient recovery of carboxylic acids from fermentation. • Large-scale downstream processing of propionic, acetic and succinic acid. Propionic acid is a valuable platform chemical that is usually produced via fossil routes. As these are energy-intensive and eco-unfriendly processes, fermentative production of propionic acid is becoming more attractive. However, the complex downstream processing (due to low achievable product concentrations, high water content, presence of by-products and thermodynamic constraints), presents a potential barrier to scale-up this technology. This original research proposes a novel intensified large-scale (production capacity of ∼ 20 ktonne/y) process for the final recovery of propionic acid after the initial biomass and counterion removal. Vacuum distillation steps ensure the recovery of a high-purity succinic acid product (>99.9 wt%) and a water stream that may be recycled to the fermentation to reduce the fresh water requirements. The main unit that follows is a highly integrated heat pump-assisted dividing-wall column (DWC), which allows the effective separation of propionic (>99.9 wt%) and acetic acid (99.4 wt%) products. Alternatively, it can serve as a reactive DWC that performs the esterification and separation of methyl propionate (99.8 wt%), methyl acetate (91.0 wt%) as higher added value products, and water by-product. If needed, extractive distillation can be implemented additionally to recover methyl acetate at higher purity (99.9 wt%). Overall, both options are proven to be economically interesting (recovery costs of 0.399 – 0.469 $/kg considering the product price of 1.349 – 1.802 $/kg) and environmentally attractive (3.206 – 3.678 kW th h/kg). [ABSTRACT FROM AUTHOR]

• Synthesized three DESs (DES1, DES2, DES3) for TBA-water separation. • Established a thermodynamic properties database for the DESs. • Quantum chemical analysis showed strong hydrogen bonding as key to breaking the azeotrope. • DES3-ED process reduced TAC by 40.16 %, showing economic feasibility. Tert-butanol (TBA) is a crucial solvent in the chemical and pharmaceutical industries. However, an azeotrope forms with water during its production process, making separation via traditional distillation methods challenging. This study employed the COSMO-Segment Activity Coefficient (COSMO-SAC) model to screen deep eutectic solvents (DESs) for the separation of the TBA-water azeotrope via extractive distillation (ED). Three DESs were selected and prepared: DES1 (tetraethylammonium chloride (TEAC): acetamide (1:2 M ratio)), DES2 (TEAC: ethylene glycol (EG) (1:2 M ratio)), and DES3 (TEAC: imidazole: EG (1:2:1 M ratio)). Vapor-liquid equilibrium (VLE) data for the TBA-water-DES systems were measured at 101.3 kPa. The results indicated that at 20 % (mole fraction) DES, all DESs disrupted the azeotrope, with DES3 proving the most effective. The Non-Random Two-Liquid (NRTL) model accurately fitted the experimental data. Quantum chemical analysis showed stronger interactions between the DES and water compared to TBA, leading to the disruption of the azeotrope. Process optimization of DES3-ED, using total annual cost (TAC) as the objective function, revealed significantly better economic performance compared to the conventional EG-ED process. [ABSTRACT FROM AUTHOR]

Research and development of environmentally friendly processes that can generate significant profits has always been a focus of attention in pharmaceutical and chemical fields. In this study, a novel reactive-extractive pressure-swing distillation (REPSD) process was designed to separate tetrahydrofuran (THF)-methanol-water (TMW) ternary azeotropic mixtures. Ethylene oxide (EO) is reacted with water to form ethylene glycol (EG) in a reactive distillation (RD) column, which removes the water from the mixture. Then, the THF-methanol (TM) mixture is separated by extractive distillation (ED) and pressure-swing distillation (PSD). A multi-objective genetic algorithm (MUOGA) with total annual cost (TAC) and total capital cost (TCC) as objective functions, along with heat integration techniques were used to optimise the designed REPSD process. Optimal operating conditions to achieve maximum economic benefits were obtained for the process. Subsequently, the environmental benefits of the process were evaluated. The results showed that the proposed REPSD with heat integration can significantly reduce the TAC and CO 2 emissions by 29.1 and 26.9 %, respectively, compared to existing optimal heat integration extractive distillation (HIED) processes. This study provides a new perspective on the separation and purification of ternary azeotropic mixtures. [Display omitted] • A novel and energy-saving REPSD process for the separation of THF-methanol-water mixtures was designed. • The water was removed by reacting with EO for obtaining the valuable by-product EG. • The designed REPSD processes were optimised through multi-objective genetic algorithm and heat integration. • The TAC and CO 2 emissions were significantly reduced by 29.1 % and 26.9 %, respectively. [ABSTRACT FROM AUTHOR]

[Display omitted] • Propose three reactive distillation-based processes to separate Serafimov's class 2.0–2b mixtures containing methanol/methyl acetate. • Methyl acetate transesterification eliminates methyl acetate and coproduces high-value products. • Integrate extractive/pre-separation distillation and reactive distillation. • Two-column pre-separation-reactive distillation is preferred. • Use parallel genetic algorithms to optimize processes. The treatment of waste streams is an important research topic for the sustainable development of chemical process. Recently, reactive distillation-based (RD) processes with ethylene oxide hydrolysis have been developed to separate water-containing azeotropic mixtures. To separate Serafimov's class 2.0–2b mixtures containing methanol/methyl acetate, a methyl acetate transesterification reaction between propylene glycol monomethyl ether is introduced to convert methyl acetate to methanol and coproduce produce propylene glycol monomethyl ether acetate as advanced solvents. Three-column reactive-extractive distillation (TCRED) and extractive-reactive distillation (TCERD), and double-column pre-separation-reactive distillation (DCPSRD) processes, are proposed. Then, we use a parallel genetic algorithm to optimize processes to maximize total net revenue. The case study is methanol/methyl acetate/ethyl acetate. Though TCRED is not suitable due to the occurrence of ethyl acetate transesterification reactions, to compare economic performances of three RD-based processes, TCRED is regarded as a pseudo process. The total net revenue of three RD-based processes is relatively larger than (∼20 % increase) that of the conventional extractive distillation process. Compared with TCRED process, TCERD and DCPSRD can achieve $582336 and $1045995 increase in TNR, 27.43 % and 49.99 % TAC reduction, respectively. In summary, proposed RD-based processes are promising to separate Serafimov's class 2.0–2b mixtures containing methanol/methyl acetate, especially TCRED and DCPSRD. [ABSTRACT FROM AUTHOR]

• Salt-based deep eutectic solvents were tested for separating the azeotrope of acetonitrile and water. • VLE data for the acetonitrile + water + salt-based DESs system were accurately described by NRTL model. • Effect of salt-based DESs on the VLE of (acetonitrile + H 2 O) system were uncovered. • The extractive distillation separation processes using salt-based DESs as entrainer were developed by Aspen Plus. • Thermodynamic efficiency, total annual cost and CO 2 emissions, are utilized to evaluate the extractive distillation processes. Salt-based deep eutectic solvents (DESs) have been proposed in this work for the separation of the azeotrope of acetonitrile and water (H 2 O). The vapor–liquid equilibrium experiments indicated that (ChCl:U:CaCl 2) 1:2:0.36 exhibits an higher selectivity among all of the entrainers investigated and eliminates the azeotropic point of acetonitrile and water mixture. Moreover, the calculated values by NRTL model coincide well with the experimental data for the systems (acetonitrile + H 2 O + (ChCl:U:CaCl 2) 1:2:0.36). Based on the thermodynamic study, the conceptual process design was established to evaluate the competitiveness of the suggested entrainers for the separation of acetonitrile and water. It was determined that the thermodynamic efficiency (η) in the extractive distillation (ED) process utilizing the new salt-based DESs entrainers increases 60.31 % compared with the benchmark entrainer ethylene glycol (EG). Conversely, the ED process using (ChCl:U:CaCl 2) 1:2:0.36) entrainer can reduce the total annual cost (TAC) by about 7.81 % and the CO 2 emissions (E CO2) by 14.74 %. The ED process using (ChCl:U:CaCl 2) 1:2:0.36) as entrainer shows the high energy efficiency, low economy cost and low CO 2 emissions with a great industrial application prospect when compared to the bench marked process. [ABSTRACT FROM AUTHOR]

The effective separation of ethyl acetate (EAC)/isopropanol(IPA)/water azeotrope from industrial wastewater significantly reduces environmental risks and recycling resources. An azeotrope separation technique was proposed, combining ionic liquid mixed entrainer and dividing wall column extractive distillation (DWC-ED). The selectivity and solubility of 225 ionic liquids were calculated based on the COSMO-RS model. The molecular polarity of EAC, IPA, H 2 O, dimethyl sulfoxide (DMSO), and [EMIM][AC] was studied, and 1-ethyl-3-methylimidazolium acetate ([EMIM][AC]) was determined as the best solvent. In addition, the interaction mechanism between [EMIM][AC] (or DMSO) and EAC/IPA/H 2 O was studied using the quantum chemistry (QC) theory. Independent gradient model (IGM), interaction energy, and atoms in molecules (AIM) analysis showed that hydrogen bonds and vdW forces were formed between [AC]− anion and H 2 O/IPA/EAC, and the interaction energy was gradually weakened, which significantly improved the performance of extractive distillation process. The results showed that the total annual cost (TAC) and energy consumption of IL-based mixed solvent extractive distillation were reduced by 36.04 % and 37.72 %, respectively, compared to the single DMSO extractive distillation process. The TAC and energy consumption of the DWC-ED process were 44.61 % and 51.43 % lower than the benchmark processes. [ABSTRACT FROM AUTHOR]

• Recovering 2-Methoxyethanol from wastewater has environmental and economic benefits. • Mixed solvents based on ionic liquids are used for extractive distillation. • The interaction mechanism is analyzed from the microscopic perspective. • Research process strengthening technology to save energy and reduce consumption. • The processes are considered from economic, environmental, and exergy. 2-Methoxyethanol is an important solvent with wide application prospects. Recovering 2-Methoxyethanol from wastewater has significant environmental and economic benefits. In this work, quantum chemistry methods are used to calculate the surface electrostatic potential, mutual penetration analysis, and reduced density gradient-independent gradient model of solvents and azeotrope. From the perspective of the mechanism of action, suitable extractants are selected. With the minimum total annual cost as the goal, the splendid process parameters and the excellent ratio of mixed solvents (30 % 1-ethyl-3-methylimidazole acetate + 70 % N, N-dimethyl acetamide) are acquired. Moreover, two reinforcing processes for energy saving and consumption reduction are also researched. All processes are appraised from three aspects: economy, environment and exergy. The results show that the total annual cost and gas emission of mixed solvent extraction distillation are reduced by 26.79 % and 35.45 %, respectively, compared with the process with NMP as an entrainer. Compared with the process with [EMIM][AC] as an entrainer, the total annual cost and gas emissions are reduced by 44.99 % and 25.04 %, respectively. Relative to mixed solvent, the total annual cost and gas emissions of the heat pump combined with mixed solvent extractive distillation technology decreased by 6.77 % and 21.78 % respectively, while that of the heat integration process decreased via 9.93 % and 12.30 % respectively. From the point of view of environmental sustainability, the process effect combined with the heat pump is better, and from the point of view of economic benefits, the heat integration process has better performance. This study reveals the intrinsic relationship between the structure of mixed solvents and explores the intensification of the process, which provides a theoretical basis for the industrial separation of 2-Methoxyethanol/water azeotrope. [ABSTRACT FROM AUTHOR]

To efficiently recover dipropyl ether/isopropanol from wastewater, realizing resource recycling and clean production, a viable solution for extractive distillation with mixed solvent (Glycerin: [EMIM][SCN] = 0.254: 0.746) was proposed. Quantitative and qualitative methods were used to screen solvents. Based on COSMO-RS, the selectivity of species in 352 ILs was calculated. The interaction relationship between the microscopic molecular structure and separation performance was researched, and the process mechanism of solvents separating the ether-containing ternary azeotropes was revealed. The use of genetic algorithms for multi-objective optimization determined the splendid process parameters. The scheme was evaluated in terms of economic benefits, environmental impact, and exergy losses. Compared with the pressure swing extractive distillation of a single solvent, the total annual cost and gas emission of the technology using mixed entrainers decreased sharply. Combined with Heat-integrated can realize the low-cost recovery of dipropyl ether/isopropanol from wastewater, which has a guiding role in the industrial separation of ternary azeotrope. • Separation dipropyl ether/isopropanol from wastewater used mixed entrainer based on ionic liquids. • Quantitative and qualitative methods were used to screen ionic liquids and organic entrainers. • Revealed the separation mechanism of ether containing ternary azeotropes. • The scheme was evaluated in terms of multiple performance. • Researched process intensification to save energy and reduce consumption. [ABSTRACT FROM AUTHOR]

• Phase diagram analysis and conventional separation methods is integrated to propose feasible process improvements. • A novel "Dehydration-Butanol-Extraction four-column Distillation" (DBE-4CD) process is proposed for the efficient separation of biobutanol and IE gasoline additives. • Sensitivity analysis is conducted on the DBE-4CD process to analyze the impact of key parameters on heat load to enhance energy efficiency. • Dividing-Wall column thermally coupled distillation is applied to establish the Azeotrope dividing wall-extractive three-column distillation (ADE-3CD) process, further optimizing energy efficiency. • The proposed ADE-3CD process performs best in energy saving and product recovery rates. To address the downstream processing challenges of the IBE (isopropanol-butanol-ethanol) system and obtain biobutanol products with a mass fraction of 0.9999, as well as obtain a mass fraction of 0.99975 for the IE (isopropanol-Ethanol) mixture product as a gasoline additive, this study proposes a four-column distillation process termed "Dehydration-Butanol-Extractive Four Column Distillation" (DBE-4CD). With the heat load as the optimization target, the DBE-4CD process was optimized to determine the optimal operating parameters. Based on the optimized process and considering the energy-saving potential of the dividing wall column, an "Azeotropic Dividing Wall-Extractive Three Column Distillation" (ADE-3CD) process was subsequently proposed to further enhance energy efficiency and reduce consumption. Compared to both conventional literature process and the DBE-4CD process, the total load of the ADE-3CD process decreased to 7433.5 kW, representing reductions of 20.35% and 10.11%, respectively. Additionally, the mass recovery rates of butanol and the IE mixture reached 99.90% and 99.64%, respectively, exceeding those of the conventional literature process, which were 99.11% and 99.18%. [ABSTRACT FROM AUTHOR]

This perspective paper features the process intensification (PI) application for advanced distillation-based processes. Starting with the historical background of generic PI, we subsequently narrow down the discussion to extractive distillation (ED), reactive distillation (RD), and hybrid reactive-extractive distillation (RED). We categorize the existing PI techniques onto internal and external intensification, where the former does not involve altering the distillation configuration while the latter does. Instead of deliberating the technical aspects, we explicitly highlight the contribution of PI applied to ED, RD, and RED towards societal impact covering energy, economic, environmental, control, and safety perspectives. The future perspectives of PI are discussed in the last section, covering the development of hybrid PI technologies, exploring the energy efficiency of different PI configurations, prioritizing PI beyond energy by considering some other sustainability aspects, and linking PI with the ever-increasing Industry 4.0 applications. • Historical application of PI of conventional distillation. • Extension of PI to advanced distillation processes covering ED, RD, RED. • Categorization of internal and external PI techniques. • Contribution of PI to sustainability and societal impact. • Future perspectives of PI applied to ED, RD, and RED. [ABSTRACT FROM AUTHOR]

Designs of extractive distillation systems for ethanol-water separation using ionic liquids as entrainers are presented. Distillation sequences that integrate the extractive column with five options for ionic liquid recovery were designed. Two types of ionic liquids, namely, 1-butyl-3-methylimidazolium chloride [BMIM](Cl)] and 1-ethyl-3-methylimidazolium tetrafluoroborate [EMIM](BF₄)], were considered. Once initial designs were obtained, simulations using the Aspen Plus environment were conducted to identify the operating conditions of the separation sequences that minimize energy consumption. The designs were tested under two levels of IL flows, one with the minimum flow required for the separation and another one with the flows that minimized the total annual cost of the extractive column. From the total of 20 design options, it was found that the most energy efficient design was based on a low flow of [BMIM(Cl)] as entrainer, with an extractive column followed by a desorption column and a membrane unit for IL recovery. [Display omitted] • Ionic liquids have been recently considered for extractive distillation systems. • Design of extractive distillation systems with ionic liquids as entrainers is shown. • Particular attention is given to options for ionic liquid recovery systems. • Integrated extractive distillation plus ionic liquid recovery systems are examined. • As a result, energy-efficient integrated structures are detected. [ABSTRACT FROM AUTHOR]

For the purpose of recycling resource and cleaner production, the extractive distillation schemes with different ionic liquids as extractants are proposed to separate ethyl acetate and methanol. In fact, the evaluation of extractants should not just focus on the separation effect, the effectiveness for the recovery of extractants which has a great influence on the overall benefits of extractive distillation process also need to be paid more attention, especially for the ionic liquids (ILs). On the basis of the VLE diagram, σ-Profiles, and interaction energy based on molecular dynamics, the separation effects of the selected extractant are following the order of 1-ethyl-3-methylimidazolium acetate ([EMIM][OAc]) > 1-ethyl-3-methylimidazolium diethyl phosphate ([EMIM][DEP]) > dimethyl sulfoxide (DMSO). However, the decomposition temperature of [EMIM][DEP] is much higher than that of [EMIM][OAc], which leads to the better effectiveness for extractant recovery. Then, several recovery configurations are explored owing to different decomposition temperature of selected ILs. The result shows that the heat integration assisted the process with [EMIM][DEP] as extractant which utilizes two-stage evaporators extractant recovery configuration has a better performance than other processes and can reduce 35.07% of TAC, 37.59% of energy consumption and 37.36% of gas emission compared with conventional extractive distillation process with DMSO as extractant [ABSTRACT FROM AUTHOR]

One of the most common techniques for separating azeotropes and close-boiling mixtures is extractive distillation, where the relative volatility of the components to be separated is altered by adding an entrainer. In recent years, deep eutectic solvents have emerged as a new class of entrainers in extractive distillation. Similar to the related class of ionic liquids, deep eutectic solvents combine the high separation capability of solid salts with the simple handling of liquids, additionally exhibiting low to negligible vapour pressures and non-flammability. Compared to ionic liquids, deep eutectic solvents offer advantages in terms of toxicity issues but also solvent costs. In this review, the current state of research regarding deep eutectic solvents in extractive distillation spanning from vapour-liquid-equilibrium measurements and thermodynamic modelling of the corresponding systems to general entrainer feasibility considerations and process simulations is presented and critically evaluated. Additionally, future prospects and comments on unresolved issues are provided. [Display omitted] • Deep eutectic solvents can be used as azeotrope breakers in extractive distillation. • For thermodynamic modelling activity coefficient models like NRTL frequently used. • Higher separation performance than conventional solvents. • Significant reduction in energy demand for extractive distillation process. [ABSTRACT FROM AUTHOR]

Ethyl tert -butyl ether is a green gasoline additive that enhances fuel efficiency and can play an essential role in improving fuel performance. This study explored the separation of wastewater containing ethyl tert -butyl ether and ethanol by changing the pressure and adding reactions based on extractive distillation, using the synergistic effect of the entrainer, pressure, and chemical reaction. By utilizing coupling technology and process intensification concepts, developed a comprehensive series of intensified processes that have clarified the interaction mechanisms between the extractive distillation process (EDP), pressure swing extractive distillation process (PSEDP), and reactive extractive distillation process (REDP). Studying the separation and purification mechanisms of products and intermediates during the reaction process provides theoretical and practical support for optimizing chemical processes. Comparative analysis showed that the reactive extraction pressure swing distillation process (REPSDP) had preeminent economic and environmental benefits. The total annual cost of PSEDP, REDP, and REPSDP was reduced by 5.88 %, 1.68 %, and 10.08 %, respectively, compared with EDP. The gas emissions of PSEDP, REDP, REPSDP, and REPSDP with heat integration process (HI-REPSDP) are all lower than those of EDP. HI-REPSDP saves 47.59 % of gas emissions compared to EDP, highlighting its environmental benefits. HI-REPSDP has the best energy efficiency, reducing energy consumption by 47.58 % compared to EDP, significantly improving the energy utilization rate. It was found that the introduction of heat integration technology had a significant improvement effect. This research has crucial theoretical and practical value and provides guidance and reference for achieving a clean and efficient production process. [ABSTRACT FROM AUTHOR]

[Display omitted] The separation of the ternary azeotrope system is still a topic worth studying. An effective method based on a mixed ionic liquids (ILs) extractant was proposed and applied to the separation of isopropanol (IPA), n-hexane (NH) and water (H 2 O) systems. Firstly, the organic solvent and ILs with better separation effects for the two components of the ternary azeotropic system were screened out by relative volatility calculation, quantum chemistry and molecular dynamics calculation. Based on the synergistic effect of dimethyl sulfoxide (DMSO) and 1-ethyl-3-methylimidazolium thiocyanate ([EMIMSCN]), a mixed ILs extractant was designed. It was then applied to three extractive distillation (ED) processes. Aiming at the minimum total process cost and gas emission, an optimization strategy was designed to achieve multi-objective optimization of process flow, the optimal composition and dosage of the mixed extractant were determined. The process results showed that the total annual cost (TAC) and gas emissions from mixed extractive distillation (MED) were 795406.85 $/y and 1536.84 kg/y, and the process energy consumption was 1987.99 kW. Compared with the ED process with DMSO as an extractant, the MED process can save 40.05 % TAC and reduce 30.39 % gas emission and energy consumption. The mixed extractant was carefully studied, and the addition of ILs was analyzed to increase the relative volatility between IPA and H 2 O separated by the extractant. The sensitivity analysis of the key variables of the MED process was carried out. The results show that the feed position of the extractant has the greatest influence on the objective function. Finally, the MED and the mixed extractive distillation under reduced pressure (RPMED) process were intensified, and the heat pump coupled thermal integrated Heat-integrated mixed extractive distillation (HPH-MED) process was determined to be the best process based on environmental pollution and energy consumption considerations. The TAC of the process is 767298.474 $/y, the gas emission is 753.84 kg/y, and the energy consumption of the process is 975.13 kW. Compared with the MED process, TAC is reduced by 3.53 %, and total gas emissions and energy consumption are reduced by 50.95 %. [ABSTRACT FROM AUTHOR]

[Display omitted] • Proposes a mixed solvent with a 6:4 ratio of methyl salicylate to [BMIM][NTf 2 ]. • Analyzes synergistic effects of thermodynamics and kinetics. • Compares transfer efficiency and TAC across four process configurations. • Direct extractive distillation outperforms indirect sequences. • Mixed solvent enhances transfer efficiency and reduces TAC versus pure solvents. The low selectivity of traditional organic solvents and the limited mass transfer efficiency caused by the high viscosity of ionic liquids (ILs) pose challenges in separating of dimethyl carbonate (DMC)/methanol/water mixtures. Therefore, a novel mixed solvent is proposed with a mass ratio of methyl salicylate to 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide of 6:4. The synergistic effects of thermodynamic, kinetic, and economic performance using the mixed solvent are investigated. Comparisons of overall efficiency and total annual cost (TAC) for four process configurations using direct and indirect extractive distillation sequences to produce industrial and battery-grade DMC products are conducted. The results indicate that direct extractive distillation outperforms the indirect sequence, reducing TAC by 6.1–14.3 % for producing industrial-grade DMC and 6.6–15.8 % for battery-grade DMC. Additionally, using mixed solvents in direct extractive distillation is more effective than using pure solvents, enhancing mass transfer coefficients by 2.8–20.9 % for industrial-grade DMC and 1.8–17.8 % for battery-grade DMC. This approach also reduces TAC by 3.2–3.6 % for industrial-grade DMC and 4.7–5.7 % for battery-grade DMC. [ABSTRACT FROM AUTHOR]

Tetrahydrofuran (THF) and methanol (MeOH) are commonly used raw materials and reagents in the chemical industry, but the azeotropic phenomenon between the two components makes it challenging to achieve high-purity separation. This study separated THF/MeOH/H 2 O mixtures by heat-integrated extractive distillation using an ionic liquid-based mixed entrainer (ILME). The dimethyl sulfoxide (DMSO) was determined by relative volatility analysis, and IL [EMIM][AC] was screened from 240 ionic liquids according to the COSMOtherm 2021 software. The separation mechanism was investigated at the molecular level (i.e., IGM analysis, polarisation charge density (σ-profile), electrostatic potential (ESP), interaction energy, and quantum chemical theory), which demonstrated that the rationality and strength of the interaction between the entrainer and the separated system were conducive for the separation to proceed. Single DMSO, ILME indirect extractive distillation (IED) and direct extractive distillation (DED) were designed and optimized, and further heat-integrated optimization (HI-DED) was performed on the ILME direct extractive distillation process. The results showed that HI-DED reduced the average annual total energy consumption, energy utilization and CO 2 emissions by 23.23%, 26.24% and 26.24%, respectively, compared to the conventional direct extraction distillation process. The HI-DED process using ILME significantly reduces economic, energy consumption and CO 2 emissions compared to conventional extractive distillation and has great potential for industrial applications. [ABSTRACT FROM AUTHOR]

It is of great significance and necessity to develop a sustainable and efficient separation scheme of butanone (MEK), ethanol (EtOH), and water, which are usually formed during the cinepazide maleate synthesis process. To the best of our knowledge, the systematic separation of this ternary multi-azeotropic mixture remains comparatively less studied, compounded by the significant challenges posed by its intricate composition comprising four azeotropes and three distillation boundaries. Therefore, a systematic approach by integrating the process design, multi-objective optimization, and multi-criteria decision-making (MCDM) methods was proposed to achieve the sustainable separation. Initially, three separation schemes, i.e., triple-column extractive distillation (TCED), double-column reactive extractive distillation (DCRED), and side stream intensified double-column reactive extractive distillation (SS-DCRED), were mainly explored via the thermodynamic and kinetic analysis. Subsequently, the multi-objective particle swarm optimization (MOPSO) algorithm was employed to optimize the process based on three objectives namely the total annual cost (TAC), CO 2 emissions, and process route index (PRI). Finally, an efficient MCDM method combining CRITIC and TOPSIS was employed to rank the Pareto front solutions of the corresponding process design. Based on the comparison results, the optimal TCED process exhibits the lowest PRI with a decrease of 50.61% and 55.06% compared to that of the SS-DCRED and the DCRED, respectively. It also shows the best performance simultaneously considering economic, environmental, and safety criteria. Of note, the SS-DCRED separation process exhibited the lowest TAC, with a decrease of 60.67% and 11.45% compared to that of the TCED and the DCRED, respectively. [ABSTRACT FROM AUTHOR]

This study reported a conceptual design of dimethyl carbonate/methanol (DMC/MET) separation via an azeotropic distillation (AD) process with water as the entrainer. Water can form a minimum azeotrope with DMC, stripping DMC from MET via a distillation column. Meanwhile, the liquid–liquid equilibrium can lift the DMC fraction from the azeotropic composition to a much higher level with a decanter. It enables the subsequent distillation column to produce pure DMC. The techno-economic analysis after process optimization demonstrated that the total annualized cost (TAC) of the AD process is 13.8 % lower than the conventional extractive distillation (ED) process. Subsequently, heat integration and double-effect distillation were introduced to further increase the energy efficiency. The improved AD process is also superior to the improved ED process (31.7 % energy cost and 4.1 % TAC saved). Moreover, the moderate temperature of the reboilers of the AD process with water as the entrainer further elevates its superiority since industrial waste heat can be applied in this case. [ABSTRACT FROM AUTHOR]

Methyl tert -butyl ether (MTBE) is an important chemical raw material and fuel additive commonly used in the chemical industry and can form minimum boiling azeotrope with methanol (MeOH). In this article, extractive distillation processes with common-extractant (diethylene glycol, DG), counter-extractant (chlorobenzene, CB) and ionic liquid ([MIM][HSO 4 ]) for the separation of MTBE and MeOH binary azeotrope are investigated simultaneously for the first time. Moreover, five quantum chemical calculation methods of σ-profiles, electrostatic potential, interaction energy, Hirshfeld surface and weak interaction are used simultaneously for the first time to reveal the extractive distillation mechanism of different extractants in detail. Finally, three extractive distillation processes (CED-IL, CED-DG, CED-CB) are established and optimized with total annual costs (TAC) and CO 2 emissions as objectives. Their performances are comprehensively compared from the aspects of economy, environment, energy, exergy and inherent safety under the optimal conditions. The results demonstrate that, in comparison to the CED-DG process, the CED-IL process reduces TAC by 31.0%, total energy consumption (TEC) and gas emissions by 27.7%, process route index (PRI) by 36.4% and increase thermodynamic efficiency by 46.4%, while the CED-CB process increases TAC by 29.1%, TEC and gas emissions by 23.2%, PRI by 22.1% and reduce thermodynamic efficiency by 11.4%. [ABSTRACT FROM AUTHOR]