Separation Of Ternary Mixtures Research Articles

Design and energy-saving strategy of sustainable pressure-swing distillation with thermally and electrically coupled intensification for separating ternary mixture with multiple azeotropes

The separation of ternary mixtures that form multiple azeotropes is frequently encountered in industry. Benefiting from the pressure-sensitive nature of the azeotropic mixture, the pressure-swing distillation (PSD) is promising to realise the separation without introducing foreign solvents. However, the wide application of PSD seems challenging from an energetic point of view. This work has developed a sustainable PSD process with thermally and electrically coupled intensification to decrease energy consumption, taking the separation of homogeneous acetonitrile/ethanol/water mixture as a demonstrating example. Two conventional PSD processes with different product sequences are designed through the ternary phase diagram and further optimised using the NSGA-II, considering multiple objectives, including total capital cost, total operating cost, and CO2 emissions. The optimal solution is selected by the TOPSIS analysis for each sequence and is then intensified with thermal heat integration and electricity-driven heat pump techniques. The results show that, in comparison to the non-heat-integrated PSD process, the proposed intensified design can dramatically reduce the total annual cost by up to 48%, simultaneously decreasing CO2 emissions by up to 60% and boosting energy efficiency. The present study can be of reference for designing a sustainable PSD process in ternary azeotropic separation.

Organic ternary mixture separation and purification using chromatography: Design, operation, and optimization

BackgroundFrom the improvement of raw material production and process, environmental friendliness has been silently packaged into commodities and integrated into society. Traditional batch chromatography methods are often used for separating succinic acid but incur large wastewater treatment costs and low efficiency. MethodsThe process design of simulated-moving-bed cascades (SMBC) for separating organic ternary mixture is proposed to address environmentally friendly raw material production methods with a more resource-saving process. Through dynamic modeling, numerical analysis, separation theory, and optimization methods, SMBC model is validated and scale-up by using Aspen Chromatography. FindingAccording to the adsorptivity and selectivity of different adsorbents, two scenarios of the SMBC for separating the organic ternary mixture of succinic acid, formic acid, and acetic acid are investigated. The results show that the SMBC using Amberchrom-CG300C and Reillex 425 resins could achieve the purity of each organic acid up to 96.8∼99.9%, and the corresponding recovery ratio is around 97.7∼99.9%.

ZIF-8 nanoplate/6FDA-DAM membrane for hydrogen extraction from propane dehydrogenation process

High-aspect ratio materials can enhance gas separation performance compared to low-aspect ratio materials when incorporated into a polymer matrix to form mixed matrix membranes (MMMs). However, the filler shape effect on various properties of MMMs was not thoroughly discussed. Herein, we fabricated a mixed matrix membrane with two different shapes of metal-organic framework (MOF) and examined the MOF filler shape effect on mechanical, thermal, and gas separation properties. Zeolitic imidazolate framework-8 nanoplates (NZIF-8) were synthesized by conversion method with an aspect ratio of 20. Isotropic ZIF-8 particles (IZIF-8) were also synthesized, and both fillers were hybridized with a 6FDA-DAM (PI) polymer. 20 wt% NZIF-8/PI membrane exhibited high mechanical properties of 0.282 GPa for hardness and 3.5 GPa for modulus, which is higher than that of IZIF-8/PI membranes. The membrane was stable in high temperatures which is comparable to the pristine PI membrane, showing long-term thermal stability at 300 °C. Furthermore, high aspect ratio fillers allowed significant enhancement in hydrogen separation performance, showing hydrogen permeability of around 1800 Barrer with hydrogen/propane selectivity of 260 at 20 wt% ZIF-8 nanoplate loading, which is much enhanced than the membrane with isotropic ZIF-8 particles. The separation performances were consistent in ternary mixture separation under different conditions. These highly stable and selective properties can be promising for hydrogen extraction from the propane dehydrogenation process.

Conceptual process design and process optimization of triple-column pressure-swing distillation for the separation of ternary mixtures embedding two azeotropes with different feed composition via thermodynamic insights and genetic algorithm

In this article, we take the tetrahydrofuran (THF)/ethanol (ETOH)/methanol (MeOH) as an example to investigate the process design of the triple-column pressure-swing distillation (TCPSD) for the separation of Serafimov’s class 2.0-2b mixtures with different feed composition. Two basic topology structures (TSI, TSII) and two separation sequences (SSI, SSII) are investigated, then, process optimization with total annual cost (TAC) as objective function is conducted via genetic algorithms. Heat integration (HI) is also applied to TCPSD. From a new perspective, the separation of THF/ETOH/MeOH can be regarded as the azeotropic distillation for THF/ETOH with MeOH as azeotropic agents based on thermodynamic features of Serafimov’s class 2.0-2b mixtures. The feasible topology structure and separation sequence of TCPSD for Serafimov’s class 2.0-2b mixtures depend on the feed composition and operating pressure. The feed composition is divided into three regions according to the concentration of methanol in azeotropic distillation column. The two critical points are azeotropic points at allowed minimum and maximum operating pressure. Especially, when feed composition is below azeotropic point at allowed minimum operating pressure, TSI is not feasible due to less MeOH as azeotropic agents. Furthermore, TCPSD combining pure azeotropic agents (ATPSD) can be developed based on this new insight. Then, two feed compositions are used to illustrate the detailed conceptual design of three topology structures as well as corresponding two separation sequences and their economic performance. The results show that when feed composition is 0.4ETOH/0.25THF/0.35MeOH, TSI and TSII are feasible, the best economical configurations without and with heat integration is TSII-SSII and TSII-SSII-HI. When feed composition is 0.4ETOH/0.4THF/0.2MeOH, TSII and ATPSD are feasible, the best economical configurations without and with heat integration is ATPSD-SSI and ATPSD-SSI-HI. Furthermore, ATPSD-SSI and ATPSD-SSI-HI have 18.28% and 19.38% TAC reduction than TSII-SSI and TSII-SSI-HI, respectively. In summary, feasible and the best economic topology structure and separation sequence of TCPSD for Serafimov’s class 2.0-2b mixtures depend on the feed composition and operating pressure. In addition, the proposed ATPSD shows good economic performance for Serafimov’s class 2.0-2b mixtures.

Dynamic Control Analysis of Internally Heat Integrated-Top Dividing Wall Column

Although The Dividing Wall Column (TDWC) with a top partition is an effective alternative for the separation of ternary mixtures dominated by the lightest component, it can be further intensified by introducing the Internal Heat Integration-The Dividing Wall Column (IHI-TDWC). However, strong internal mass and energy integration complicates the process dynamics and influences the system controllability. In the current work, a kind of decentralized temperature control scheme involving four temperature control loops is developed. The separation of the ternary mixture with methanol, ethanol, and n-propanol is chosen as an illustrative example to evaluate the controllability of the IHI-TDWC through open-loop and closed-loop dynamic process simulation. The results show that the IHI-TDWC keeps good rejection of the throughput and feed composition disturbances.

Sequential Separation of Linear, Mono-, and Di-Branched Hexane Isomers on a Robust Coordination Polymer with Nonbonding Flexibility.

Efficient separation of hexane isomers is a crucial process for upgrading gasoline. Herein, the sequential separation of linear, mono-, and di-branched hexane isomers by a robust stacked 1D coordination polymer termed as Mn-dhbq([Mn(dhbq)(H2 O)2 ],H2 dhbq = 2,5-dihydroxy-1,4-benzoquinone)is reported. The interchain space of the activated polymer is of optimal aperture size (5.58 Å) that could exclude 2,3-dimethylbutane, while the chain structure can discriminate n-hexane with high capacity (1.53mmol g-1 at 393 K, 6.67kPa) by high-density open metal sites (5.18mmol g-1 ). With the temperature- and adsorbate-dependent swelling of interchain spaces, the affinity between 3-methylpentane and Mn-dhbq can be deliberately controlled from sorption to exclusion, and thus a complete separation of ternary mixture can be achieved. Column breakthrough experiments confirm the excellent separation performance of Mn-dhbq. The ultrahigh stability and easy scalability further highlight the application prospect of Mn-dhbq for separation of hexane isomers.

Temperature-swing molecular exclusion separation of hexane isomers in robust MOFs with double-accessible open metal sites

The separation of hexane isomer mixtures into their individual components is one of the most important while challenging industrial process to produce high-octane gasoline. Herein robust M(pz)[Ni(CN)4], termed MpzNi (M = Co, Ni, pz = pyrazine) that can realize efficient separation of ternary mixtures into the pure, individual components. As optimal pore channels with double-accessible open metal sites providing the adsorbate-dependent affinity differences for molecular exclusion behavior via temperature programming, CopzNi reached optimum performance with not only exceptional selectivity of linear/monobranched alkanes and monobranched/dibranched alkanes, but also notably higher adsorption capacity than those of the previously reported adsorbents. Breakthrough experiments with equimolar ternary C6 alkane isomers and binary branched mixtures confirmed CopzNi can highly capture n-hexane and 2-methylpentane from their mixtures. The excellent separation efficiency, lower-energy regeneration, scalability, recyclability as well as high stability render the CopzNi a benchmark candidate for implementation in the current separation processes.

Energy and exergy analysis of a stacked complex sequence and alternatives for ternary distillation

Detailed energy and exergy analyses are conducted for a stacked complex sequence (SCS) and alternatives for a ternary zeotropic distillation problem. Multi-objective optimizations are performed using both cost and thermodynamic efficiency as objective functions. The results show that while a dividing-wall column (DWC) offers a significant improvement in both cost and thermodynamic efficiency compared to a conventional sequence, the SCS performs better by every metric considered and at every point on the Pareto front of cost and thermodynamic efficiency. These results suggest that SCSs deserve serious consideration as an alternative to thermally coupled or DWC configurations for the separation of ternary mixtures.

Effect of Entrainer Thermodynamic Properties on the Separation of Ternary Mixtures Containing Two Minimum Boiling Azeotropes by Extractive Distillation

Effect of Entrainer Thermodynamic Properties on the Separation of Ternary Mixtures Containing Two Minimum Boiling Azeotropes by Extractive Distillation

Novel design of lubricant-type vacuum distillation process for lube base oils production from hydrocracking tail oil

Dividing-wall columns (DWCs) are widely used in the separation of ternary mixtures, but rarely seen in the separation of petroleum fractions. This work develops two novel and energy-efficient designs of lubricant-type vacuum distillation process (LVDP) for the separation of hydroisomerization fractions (HIF) of a hydrocracking tail oil (HTO). First, the HTO hydroisomerization reaction is investigated in an experimental fixed-bed reactor to achieve the optimum liquid HIF by analyzing the impact of the operating conditions. A LVDP used for HIF separation is proposed and optimized. Subsequently, two thermal coupling intensified technologies, including side-stream (SC) and dividing-wall column (DWC), are combined with the LVDP to develop side-stream vacuum distillation process (SC-LVDP) and dividing-wall column vacuum distillation process (DWC-LVDP). The performance of LVDP, SC-LVDP, and DWC-LVDP are evaluated in terms of energy consumption, capital cost, total annual cost, product yields, and stripping steam consumption. The results demonstrates that the intensified processes, SC-LVDP and DWC-LVDP significantly decreases the energy consumption and capital cost compared with LVDP. DWC-LVDP further decreases in capital cost due to the removal of the side stripper and narrows the overlap between the third lube oils and fourth lube oils. This study attempts to combine DWC structure into the separation of petroleum fractions, and the proposed approach and the results presented provide an incentive for the industrial implementation of high-quality utilization of HTO through intensified LVDP.

Computational Screening of Metal-Organic Frameworks for Ethylene Purification from Ethane/Ethylene/Acetylene Mixture.

Identification of high-performing sorbent materials is the key step in developing energy-efficient adsorptive separation processes for ethylene production. In this work, a computational screening of metal-organic frameworks (MOFs) for the purification of ethylene from the ternary ethane/ethylene/acetylene mixture under thermodynamic equilibrium conditions is conducted. Modified evaluation metrics are proposed for an efficient description of the performance of MOFs for the ternary mixture separation. Two different separation schemes are proposed and potential MOF adsorbents are identified accordingly. Finally, the relationships between the MOF structural characteristics and its adsorption properties are discussed, which can provide valuable information for optimal MOF design.

Intensified hybrid reactive-extractive distillation process for the separation of water-containing ternary mixtures

• Process intensification for separating water-containing ternary azeotropic mixtures. • Combine reactive distillation and extractive distillation into one column. • Systematic VLE analysis helps to screen for feasible ternary systems. • Three ternary systems including: TBA/EtOH/water, THF/EtOH/water, and ACN/IPA/water. • Significant reduction in total annual cost is achieved in all applications. Separation of ternary mixture is a challenging task if multiple azeotropes exist among the components, and special distillation techniques should be adopted. For water-containing ternary mixtures with multiple azeotropes, a dehydrating agent, ethylene oxide (EO), can be used to consume water with the production of ethylene glycol (EG) as the product, which can be utilized as entrainer for separating the remaining two components. In this work, systematic thermodynamic analysis was conducted to screen for the feasible ternary systems. After conducting suggested analysis without needing of rigorous process simulation, tert -butyl alcohol (TBA)/ethanol (EtOH)/water, tetrahydrofuran (THF)/EtOH/water and acetonitrile (ACN)/isopropyl alcohol (IPA)/water mixtures were chosen to be suitable for this application. Within the scope of using dehydrating agent, a process configuration of triple column reactive-extractive distillation (TCRED) is developed for three different ternary systems. Subsequently, an intensified process configuration - double column reactive-extractive distillation (DCRED), which combines both functions of reactive distillation and extractive distillation in a single unit, is constructed to significantly reduce capital cost and energy consumption. With the application of further energy-saving schemes in the systems, total annual cost and total operating cost of the final proposed design flowsheets can be considerably saved compared to respective separation systems recently published in open literature.

Process design and multi-objective optimization for separation of ternary mixtures with double azeotropes via integrated quasi-continuous pressure-swing batch distillation

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%.

Pressure-swing distillation process for separating ternary azeotropic mixture of acidic aqueous solution

The separation of ternary mixture of acidic aqueous solution is difficult due to presence of both binary and ternary azeotropes that generate distillation boundaries. In this work, a pressure-swing distillation process for separating the mixture was investigated. Three variants of pressure swing distillation process were therefore proposed. The operating pressure of each distillation column was chosen on the basis of the location of the feed composition in the distillation regions. The sensitivity analysis of the operating parameters of each separation process was carried out to determine the best operating conditions to reach higher purity for the three products (i.e., 99.9 mol.%). It has been found that formic acid and water present in the ternary mixture with high content can be separated twice as a distillate product with total molar recovery ratio of about 90%. In addition, the energy consumed to separate water was higher than that required to recover formic acid.

A selective organosilica membrane for ethyl acetate dehydration by pervaporation

AbstractOrganosilica bis(triethoxysilyl) ethane (BTESE) membranes were explored for pervaporation dehydration of binary and ternary mixtures of ethyl acetate (EA) by undiluted sol coating combined with flash firing. Three BTESE membranes (M1, M2, and M3) were fabricated on macroporous supports by varying BTESE concentrations (0.5, 2.5, and 5 wt% BTESE, respectively) in polymer sols. The membranes were characterized by DLS, SEM, FTIR, XRD, contact angle, AFM, and pervaporation performance to discuss the effect of the BTESE contents in the polymer sol on the formation and dehydration performance of resulting organosilica membranes. It was found that 5 wt% loading of BTESE led to a highly selective membrane for dehydration of EA/H2O mixture. Among the synthesized membranes, M3 delivered flux of 0.84 ± 0.05 kg.m−2.h−1 with a selectivity of >10,000 for EA/H2O mixture (98/2 wt%) at 60°C. The time course of pervaporation dehydration for the EA/H2O mixture (95/5 wt%) confirms the stability of BTESE membrane in the investigated time period of 120 h. Further, the membrane exhibited excellent selectivity larger than 10,000 for separation of ternary mixtures (90/2/8 wt%) of ethyl acetate/ethanol/water and n‐propyl acetate/isopropanol/water respectively, the composition of which is similar to the top product of the distillation column used in the industrial esterification process. The best separation performance and excellent acid stability of BTESE membranes in this study suggest that the simple synthesis protocol of undiluted sol coating and flash firing will provide a cost‐effective, quick, and efficient synthesis route for practical membrane based applications.

Sequential two-column batch distillation processes for separation of ternary mixture containing three binary minimum boiling point homoazeotropes

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.

Optimization and eco-efficiency analysis of extractive distillation processes with different solvents for separating the ternary mixture embedding two azeotropes

The selection of feasible solvent is of great significance for separating azeotropes via extractive distillation since various solvents can cause different product orders, flowsheet structures, and eco-efficiencies of extractive distillation processes. Limited efforts are focused on the effect of various solvents on the separation of ternary mixtures embedding two azeotropes, especially for the design of the extractive dividing-wall column separation configurations. To fill the research gap, the separation of azeotropic mixtures embedding two azeotropes is investigated using extractive distillation method with various solvents through taking the methyl acetate/ethyl acetate/methanol mixture as an example. First, the theoretical thermodynamic feasibility of four solvents including ethylene glycol, dimethyl sulfoxide, chlorobenzene, and aniline is explored. The individual light-heavy component orders are determined through the thermodynamic insights including the construction of the pseudo binary vapor–liquid phase equilibrium diagrams and overall phase diagrams with residue curves and iso-volatility curves after adding solvents, while are further verified using σ-profiles from microscopic mechanism. Second, the conceptual design of the extractive distillation flowsheets including conventional extractive distillation and extractive dividing-wall column separation configurations with individual solvents is performed. The effects of various solvents on the flowsheet structures and product orders are analyzed. Afterwards, the extractive distillation flowsheets are simulated and optimized economically to minimize the total annual costs through the genetic algorithm, except for the solvent ethylene glycol due to the unfeasibility of realistic simulation. The eco-efficiency analysis is performed via quantifying the Eco-Indicator 99 and thermodynamic performances as well as economic costs. The results indicate that the extractive distillation processes with dimethyl sulfoxide or chlorobenzene as solvent can show a certain degree of advantage compared with that using aniline as solvent in terms of eco-efficiency. The optimal separation configuration is the extractive dividing-wall column containing two dividing-walls with CB as solvent, and its Eco-efficiency Comparison Index increased to 80.54% compared to the worst scheme that is the extractive dividing-wall column containing one dividing-wall with AN as solvent.

Energy-efficient separation design of diisopropylether/isopropanol/water system having three distillation regions and liquid-liquid envelope

This work mainly focus on providing an energy-efficient design scheme for the separation of ternary mixture containing diisopropyl ether, isopropanol and water. The residue curve maps of this mixture is very complex, including: three binary azeotropes, one ternary azeotrope, three distillation regions and liquid–liquid envelope. With the preference of not adding foreign component into this separation, a new energy-efficient design flowsheet is proposed in this paper making use of natural liquid–liquid separation in a decanter together with varying operating pressure to expand the operating distillation region for the respective column. This design flowsheet can further be heat-integrated to combine a condenser of one column with partial heat input of a reboiler of another column and also add a feed-effluent heat exchanger to preheat the feed of one column. By comparing the economic performance of the proposed design flowsheet with that of a design flowsheet published in a recent paper, significant savings in total annual cost of 42.9% and in annual operating cost of 48.1% can be realized by our proposed design flowsheet.

Vapor recompressed dividing-wall distillation columns: Structure and performance

Abstract Due to the topological structure of double columns and multiple separating sections in dividing-wall distillation columns (DWDCs), the development of vapor recompressed dividing-wall distillation columns (DWDC-VRHPs) represents a challenging issue with great complexities and tediousness. For the separations of light-component dominated and wide boiling-point ternary mixtures, because the purification of the light-component from the intermediate- and heavy-components incurs the primary energy dissipation, the application of vapor recompressed heat pumps (VRHP) should be aimed to reduce the irreversibility and this leads to the generation of the optimum topological structures of the DWDC-VRHPs, i.e., a DWDC plus a two-stage VRHP. The first-stage VRHP is to preheat feed, not only taking the advantages of the small temperature elevation available but also favoring the mass transfer between the vapor and liquid phases through feed splitting. The second-stage VRHP is to reduce further separation irreversibility. The philosophy can be applied to any DWDCs no matter where the dividing wall locates. Two case studies on the separations of ternary mixtures of benzene, toluene, and o-xylene and n-pentane, n-hexane, and n-heptane demonstrate the economic optimality of the proposed DWDC-VRHPs and reveal the inherent interplay between internal and external process integration.

Highly proficient extraction separation of thorium(IV) from sulfuric acid solution using N-n-decylaniline: real sample analysis

Herein we have developed solvent extraction method for thorium(IV) with 0.15 M N-n decylaniline in xylene from 0.5 M H2SO4. Physicochemical parameters like acid concentration, amine concentration, equilibrium time, phase ratio, diluent, loading capacity to name a few were optimized for the quantitative extraction of thorium(IV). The back-extraction of thorium(IV) from organic phase was done with 0.1 M nitric acid and determined complexometrically. To extend the utility of this method, binary and ternary mixture separation, extraction of thorium(IV) from monazite sand and gas mantle are also investigated.