Distillation Separation Research Articles

Exergy Load Distribution Analysis Applied to the Dehydration of Ethanol by Extractive Distillation

This study presents the analysis of the exergy load distribution in a separation process by extractive distillation for ethanol dehydration. The methodology carried out is divided into three parts: the calculation of the flow exergy considering the physical and chemical exergies of the distillation process; the calculation of the primary and transformed exergy contributions considering the consumed exergy; and finally, the overall process efficiency, which shows the real percentage of energy being used in the process. The simulation of an extractive distillation separation system is carried out using Aspen Plus®, from Aspen Tech Version 9. In general, heat transfer processes (heating or cooling) are the ones that generate the greatest exegetic destruction, which is why they must be the operations that must be optimized. As a result of our case study, the local exergy efficiency of the extractive distillation column is 13.80%, which is the operation with the greatest energy loss, and the overall exergy efficiency of the separation system is 30.67%. Then, in order to increase exergy efficiency, a sensitivity analysis is performed with the variation of the azeotrope feed, number of stages, reflux ratio, and solvent feed variation on ethanol purity to reach an overall efficiency of 33.53%. The purity of ethanol is classified as higher than that of the specified, 99.65%.

Effects of different hydrogen bond donors on the extraction of gasoline additive ethanol using deep eutectic solvents formed by choline chloride and dihydric alcohol or dicarboxylic acid as extractant

Ethanol is a common fuel additive, which can significantly improve the quality of fuel. In this work, the separation effect of n-heptane/ethanol system was explored for the first time by using different dihydric alcohol/dicarboxylic acid as H-Bond donor choline based deep eutectic solvents. The x-y phase diagrams of n-heptane/ethanol system with different solvents as entrainers were obtained by experiment. With the carbon chain of H-Bond donors getting longer, the separation effect of solvents on the separation system is better. The contribution of different H-Bond donors to the separation of n-heptane/ethanol system and their intermolecular interactions were explored by molecular simulations. This is because the interaction between solvents and ethanol increases with the growth of H-Bond donor carbon chain. However, the attraction of solvents to n-heptane has been very weak, and has not increased with the increase of H-Bond donor carbon chain. The extractive distillation separation process with solvents as extractant was developed, which proved that it was feasible to extract ethanol from n-heptane using deep eutectic solvents. This study provides a new idea for the recovery of fuel oil additive ethanol, and provides guidance for the development of new deep eutectic solvents.

Membrane distillation for separation and recovery of valuable compounds from anaerobic digestates

Digestate - the wet by-product of the anaerobic digestion (AD) of organic waste - is composed of a mixture of residual organic matter, microbial biomass and inorganic compounds. Although digestate is rich in nutrients, the occurrence of high levels of salinity and soluble ammoniacal nitrogen (N-NH4+) limits its direct exploitation as organic fertilizer and imposes a complex disposal.This study assesses at laboratory-scale the potential of Direct Contact Membrane Distillation (DCMD) for the separation of nutrients and the recovery of water from the liquid phase of the digestate produced by a digester that treats cattle manure and agricultural residues. Experimental tests, carried out at different feed temperature (50–70 °C) and initial pH (6–8.2) of the liquid digestate, aimed at investigating the effect of the operating conditions on the transmembrane flux of water vapor, the concentration of N-NH4+, P-PO3-, and Chemical Oxygen Demand (COD) in both permeate (also referred to as distillate) and retentate streams.For raw digestate, the initial transmembrane flux enhanced from 1.83 L·m−2·h−1 to 5.55 L·m−2·h−1, in response to increasing temperature gradient. Overall, the highest achieved water recovery factor was 40% at a feed temperature of 70 °C. The pH had a limited impact on the transmembrane flux, whereas notably affected the DCMD performance in terms of separation efficiency. In particular, a pH reduction from 8.2 (raw digestate) to 6 was able to completely avoid the transfer of N-NH4+ into the distillate. Compared to the concentration in the raw digestate, the reduction of COD and P-PO3- in the distillate was 99.0% and 99.9%, respectively. Regardless feed temperature, the performance of the process was subjected to a significant decline of evaporation rate due to occurrence of membrane fouling; however, cycles of cleaning with citric acid allowed to partially regenerate the membrane by removing the reversible cake of foulants accumulated on the surface. The results demonstrate an adequate performance of MD process for recovering water and nutrients, leading to a dehydrated fraction of the digestate phase that can be easily stored and used in agronomic practices.

Hydrogen isotopic water separation in membrane distillation through BN, MoS2 and their heterostructure membranes

The development and application of nuclear energy involves a challenging process of separating H2O/HTO to treat tritium-containing radioactive wastewater (HTO). Recently graphene oxide (GO)-based membrane distillation process has shown good performance for the separation of H2O/D2O used as a laboratory model research process for H2O/HTO separation, but further development of novel membrane materials or structures for membrane distillation process to give higher permeation flux or separation factor is still desirable. Here, boron nitride (BN) and molybdenum disulfide (MoS2) were investigated as membrane materials in the type of PTFE supported membrane, and PTFE/BN membrane showed higher permeation flux than PTFE/MoS2 and PTFE/GO membrane, and higher separation factor than PTFE/GO membrane that was higher than PTFE/MoS2 membrane. Furthermore, binary PTFE/BN/GO and PTFE/MoS2/GO heterostructure composite membranes were explored. The permeation flux of PTFE/BN/GO membrane was higher than that of PTFE/MoS2/GO and PTFE/GO/GO membrane. The separation factor of PTFE/BN/GO membrane was higher than that of PTFE/GO/GO membrane, which was higher than that of PTFE/MoS2/GO membrane. These results suggest that other 2D material- or heterostructure membranes can give performance comparable with or even better than GO membrane for the separation of H2O/D2O. This can guide for further exploration of novel materials or membrane structures for membrane distillation process with higher performance to provide a solution for the treatment of tritium-containing radioactive wastewater in the nuclear energy sector.

Silanization enabled superhydrophobic PTFE membrane with antiwetting and antifouling properties for robust membrane distillation

A superhydrophobic polytetrafluoroethylene (PTFE) membrane (water contact angle 158 ± 5o) was fabricated based on a commercial microporous membrane by surface silanization and fluorination. The engineered PTFE membrane was characterized by various techniques, including scanning electron microscopy, energy dispersive spectroscopy, X-ray photoelectron spectroscopy, laser scanning confocal microscopy, a liquid-liquid porometer, water vapor permeation and contact angle measurements. The prepared PTFE membrane showed a slightly decreased average pore size of 0.37 μm, and thus an increased penetrating pressure of 0.38 MPa compared with the pristine commercial membrane. The developed superhydrophobic PTFE membrane had a very low surface energy of 1 mJ/m2, only one third of that of the unmodified commercial membrane. The characterization and membrane distillation (MD) separation results showed that the superhydrophobic PTFE membrane had significantly enhanced antiwetting and antifouling performances compared with the pristine commercial membrane. The developed new PTFE membrane also displayed excellent antifouling, antiwetting and long-term stability during the treatment of real challenging landfill leachate of high salinity and high organics by MD. The fabricated PTFE membrane with simultaneously antiwetting and antifouling properties opens a new avenue for treating challenging waste liquids via MD. This study also provides an important strategy to develop superhydrophobic simultaneously antiwetting and antifouling membranes for stable long-term MD applications.

Design and control of extraction combined with extractive distillation for separation isopropanol-butanol-ethanol-water with organic Rankine cycle

The high-purity isopropanol butanol ethanol (IBE) mixture is a highly efficient gasoline additive that can be directly used without further separation. The product of isopropanol-butanol-ethanol fermentation contains a large amount of water, and a large amount of energy will be consumed in the purification process. In this paper, the separation IBE process is systematically studied from the aspects of process optimization, energy recovery and process control. The operation parameters of extraction combined with extractive distillation (E-ED) are optimized by a multi-objective genetic algorithm. Then, the pinch point technique is used to analyze the energy usage of the optimized process, and the maximum heat recovery heat integration scheme is obtained. Compared with the optimized process, the low pressure steam consumption of the heat integration process is reduced by 100%, the cooling water consumption is saved by 58.80%, and the TAC is reduced by 35.95%. In view of massive waste heat in the heat integration of the extraction combined with extractive distillation (E-ED-HI) process, a new configuration combining the E-ED-HI and organic Rankine cycle (E-ED-HI-ORC) is further proposed. The organic Rankine cycle using R600a can further reduce TAC by 8.88% based on the HI-E-ED process. Finally, the control scheme of E-ED process is proposed. The performance of the control scheme is examined with ±10% disturbance of the feed flow rate and composition change, and the results show that the process of extractive distillation and separation of IBE has good controllability.

Inherent flexibility design strategy of extractive distillation for binary azeotropic separation

The steady-state design and control studies of extractive distillation (ED) for azeotropic separation has received significant interest in the recent years. These studies however are usually conducted sequentially where the steady-state design is first developed followed by conducting the control analysis. In contrast to existing studies, this work incorporated the operational flexibility into the steady-state design of the ED so that any external fluctuations can be accounted in the early stage of the design. Two case studies are used to exemplify the inherent flexibility design strategy, i.e., the IPA dehydration using dimethyl sulfoxide (DMSO) and ethylene glycol (EG) as entrainer. Each case study is optimized using two different objective function individually, i.e., the total annual cost (TAC) and the flexibility index (FI). Optimizing both cases using TAC as objective function provides a lower TAC relative to the base case, which aligned with existing studies. In contrast, optimizing both cases using FI enables a greater operational flexibility, but such benefit is always accompanied by the increase in the TAC. During the FI optimization, four different uncertainties are considered, i.e., A, B, C, and D, with a combination of ± 20% feed flowrate and IPA feed concentration. For both cases, the operational flexibility limitation was found to lie in the direction of vertex D when the system is experiencing an increase in feed flowrate and a decrease in IPA feed composition. Overall, it was found that using EG provides 2.3 times better operational flexibility in comparison to that using DMSO, as indicated by the higher FI, while using DMSO provides a lower TAC by about 9%. Here, it was also found that using EG provides a lower trade-off in an increase in TAC over using DMSO, when the FI is incorporated into the steady-state design of the ED.

FT-NIR online detection performance improvement and evaluation for 2,6-dimethylphenol purity

In this paper, Fourier transform near-infrared (FT-NIR) spectroscopy was used to online detect the 2,6-dimethylphenol(2,6-DMP) purity of different rectifying columns in the distillation separation process. Considering the similarity of spectral data between different columns, transfer learning could be introduced to improve the online detection performance of 2,6-DMP purity by reusing the spectral data from other columns. Furthermore, in order to analyze the effect of the quantity and quality of the FT-NIR spectra on the detection accuracy, the influence function was used to construct the quantitative relationship between the detection accuracy and the spectral information to be transferred. The effectiveness of the approach was analyzed on the FT-NIR spectral datasets from the distillation purification process in the 2,6-DMP monomer separation section. By transferring more favorable spectral data to avoid negative transfer, the detection accuracy will be obviously increased.

Recent advances in biogas purifying technologies: Process design and economic considerations

Biogas is a promising renewable energy source that is produced from biowaste and can potentially replace conventional energy resources. The economic value of biogas, which is primarily comprised of CH4, CO2, and other impurities (e.g. H2S, and N2) can be increased by upgrading and purification. This study presents the techno-economic feasibility of the cryogenic biogas upgrading process (CBioUP) based on product purities, biomethane selling prices and different refrigeration systems over 25 years of lifetime. The proposed CBioUPs is comprised of compression, refrigeration, and separation sections. Compressed biogas was liquefied in two refrigeration systems (propane pre-cooled mixed refrigerants and optimized cascade technologies) followed by a distillation separation unit. CBioUP proved its flexibility in terms of the number of distillation columns to produce low-grade CH4 (≈94.58 mol%), high-grade CH4 (≈97.13 mol%), and liquid CO2 by-product. The process's robustness to varying biogas feed composition revealed higher CO2 content would necessitate additional duty and/or equipment to enhance separation efficiency, whereas a CH4 content of ≥70% generated biomethane with a purity >99.6 mol% even in a single distillation column. CBioUP demonstrated its suitability for producing different grades of CH4 with a promising net present value (NPV) of $28.3 and $30.9 billion for low/high-grade biomethane.

Process synthesis of intensified extractive distillation for recycling organics material from wastewater

Acetonitrile and 1,4-dioxane are significant organic compounds, which are widely used in many chemical production processes. However, some pharmaceutical or chemical factories discharge large amounts of organic wastewater containing acetonitrile and 1,4-dioxane. For dealing with this special multi-azeotrope system, it is necessary to design a dehydration extractive distillation separation scheme. Thus, an extractive distillation process with dehydration column (BFED) and an innovative extractive distillation process with an integrated column (CTED) which can function as dehydration column and extractant recovery column were proposed. For the sake of reducing energy consumption, three improved processes with direct steam injection, heat integration and heat pump were exploited. The proposed processes are comprehensively evaluated by total energy consumption and economic demand, CO2 emissions and exergy analysis. As a result, the heat pump assisted CTED process can reduce 26.86% of the total annual cost, 40.61% of energy consumption, 40.71% of CO2 emission and 44.82% of exergy destruction, respectively, compared with the BFED process.

Porcupine quills-like-structures containing smart PVDF/chitosan hybrids for anti-fouling membrane applications and removal of hazardous VOCs

The separation materials with enhanced transport and separation in membrane distillation (MD) and antifouling features were generated. The membranes were systematically characterized to understand how the covalent modification process, i.e., silanization and functionalization with chitosan, impacts the membrane performance. The material modification was done by the biomimicry of desert beetle (Stenocara gracilipes) armor and porcupine quills. The hydrophobic-hydrophilic structure of beetle armor was mimicked with the application of PVDF membrane as a hydrophobic surface and chitosan (CS) as hydrophilic nodes. By changing the experimental protocol, unique quill-like structure morphology was generated. The introduction of pristine and partially hydrophobized chitosan increased roughness significantly from 70 nm to 386 nm and 440 nm, causing contact angle improvement from 114.6° to 157.4° and 168.2°, respectively. Four times increment of transport was observed after adding CS. MD membranes with superior wetting resistance (critical surface tension ca. 20 mN m−1) were created by combining hierarchically structured membranes with re-entrant texture. The selection of fluorine-free modifiers allows the synthesis of environmentally friendly membranes and reduces the problem of bioaccumulation and acute toxicity occurring with long-chain fluorinated modifiers. Materials were tested in the air gap membrane distillation (AGMD) to remove hazardous volatile organic compounds from water. Data were analyzed by applying Hansen’s Solubility Parameters. Membranes were also applied for raw apple juice dewatering with fouling study during the osmotic MD process.

Economic, environmental, and exergy analysis of an efficient separation process for recovering low-carbon alcohol from wastewater

Extractive distillation separation is a continuous and effective process for the separation of industrial wastewater components. In this study, a method to recover high-purity ethanol and isopropanol from industrial wastewater via extractive distillation has been proposed. Three enhanced energy-saving processes were developed to reduce the economic costs and environmental impact of distillation processes. The process operation parameters with the best economic performance were obtained based on a sequential iterative optimization method with the total annual cost as the objective function. Results show that, thermally coupled technology can effectively reduce the economic cost. Compared with the conventional extractive distillation process, the total annual cost of the thermally coupled extractive distillation process was the lowest, accounting to a reduction of 33.14%. The heat recovery rate of the heat pump-assisted thermally coupled extractive distillation process was the highest (1979 kW), and the total energy consumption was the lowest (5762.4 kW). The gas emission (2432.72 kg/Y), GWP (1246.42 kg CO2-Eq), AP (2.23 kg SO2-Eq), HTP inf (38.66 kg DCB-Eq), Eco tox (20.04 CTUe), and exergy loss (20.73%) of the heat pump-assisted thermally coupled extractive distillation process were the lowest. This work has important guiding significance for the efficient recovery of low-carbon alcohols from industrial wastewater and promoting cleaner production in the chemical industry.

Recent progress on hybrid reactive-extractive distillation for azeotropic separation: A short review

The reactive-extractive distillation (RED) has the advantages of combining the beneficial features of both reaction and separation processes. Relative to the conventional reactive or extractive distillation-based processes, the RED is also less energy intensive as it relies on the reaction heat produced for the subsequent separation process. Therefore, the application of RED for ternary azeotropic separation has become the subject of popular interest, as evident by the increasing number of publications since 2020. This review paper is the first that puts together, in a chronological manner, all the existing studies on the RED to date, starting from the initial three column reactive-extractive distillation (TCRED) to the most recent dividing wall reactive-extractive distillation (DW-RED), for ternary azeotropic separation, so that the rapid progress in this area is summarised and any existing gaps in these studies become easier to identify for future work. The last part of this review provides three potential areas for future work, i.e. analysis of the sustainability of RED, combination of different process intensification strategies to improve the energy efficiency and separation performance, and further exploration on the control studies for the RED.

Design and optimization of organic Rankine cycle using different working fluids for recovering waste heat in reaction-separation process of cumene synthesis

Reaction and distillation separation processes are two indispensable operating units in the chemical industry. However, a large amount of waste heat can be produced due to the presence of the reaction and distillation processes with high-temperature nature. Thus, it is of great significance to improve the economic performances of the reaction-separation processes via recovering waste heat. In the work, the recovery of waste heat from different heat sources in the reaction and distillation processes using the organic Rankine cycle (ORC) system with different working fluids is investigated taking the cumene synthesis process as an example. First, two streams with higher temperature and larger flowrates from the reaction section and distillation section are determined as the driving heat sources, while the conceptual design of the ORC system assisted reaction-separation process is completed. And then, the operation parameters of the ORC system with two heat sources and eight working fluids including R113, R123, R245ca, R245fa, R600, R600a, R601, and R601a selected by heuristic rules are optimized, aiming to maximize the annual net economic revenues (NER) using the genetic algorithm. Following, the corresponding exergy analysis of the ORC schemes driven by two heat sources with different working fluids is performed. The results illustrate that the heat of heat sources from both reaction section and separation section should be utilized since the ORC system with mentioned eight working fluids can produce positive NER, and the stream from the reaction section is more suitable as the driving heat source of the ORC system compared to that from the distillation section due to higher temperature, greater flowrates, and the coexistence of both latent heat and sensible heat. Overall, working fluids R113 and R123 are the worthiest of consideration among mentioned eight working fluids in terms of NER produced and the thermodynamic efficiency (η) of the corresponding ORC system. However, the environmental damage factors of the working fluids R113 and R123 are not preferred compared to other working fluids. Comprehensively considering economic, environmental, and thermodynamic performances, R601 are the preferred working fluid to perform the recovery of waste heat from the cumene synthesis process using the ORC system. The corresponding NER are 17.98 × 104$/a and 1.90 × 104$/a, which are 9.78% and 5.00% lower than that of the ORC system using the most economic working fluid R113, and at least 8.44% (R601a) and 2.70% (R123) higher than that of the ORC system using other working fluids for two heat sources, respectively. The η of the ORC system with R601 as working fluid can reach 17.73% and 11.15% for two heat sources, respectively, are slightly lower than that of the ORC system using R113 (19.41%) and R123 (11.49%) as working fluids.

Multi-objective optimization and comparison of the entrainer-assisted pressure-swing distillation and extractive distillation separation sequences for separating a pressure-insensitive binary azeotrope

Pressure-insensitive azeotropes are often encountered in chemical production. Entrainer-assisted pressure-swing distillation (EAPSD) is a special pressure-swing distillation showing promising performance in separating pressure-insensitive azeotropes. However, few studies have been reported on this method. In this work, the comparison between the EAPSD with tetrahydrofuran as pressure-sensitive entrainer and extractive distillation (ED) with dimethyl sulfoxide as solvent in separating water/isopropanol azeotrope is performed to explore the performance of EAPSD. Different EAPSD sequences, low-high sequence (LHS) and high-low sequence (HLS), are designed with different product sequences. A strategy considering the possibility of both partial and full heat integration is used to reduce capital cost and energy consumption. Multi-objective genetic algorithm is applied to achieve the optimal performance. The results show that the heat-integrated HLS sequence has lower total annual cost (TAC) by 7.04% and lower CO2 emission (CDE) by 4.27% than LHS, while ED process has lower TAC and CDE by 51.80% and 36.96% than the optimal EAPSD process.

Energy-efficient separation of propylene/propane by introducing a tailor-made ionic liquid solvent

In the petrochemical industry, the separation of propylene/propane is usually paid much attention due to its high energy-consuming and environmental challenges. In this work, an energy-efficient extractive distillation (ED) separation process of propylene/propane is proposed by introducing a tailor-made ionic liquid (IL) solvent. The structure optimization of ILs is performed with a novel design objective in the computer-aided ionic liquid design (CAILD) method. By solving a formulated CAILD-based mixed-integer nonlinear programming (MINLP) problem, the ethylimidazolium ethyl sulfate ([C2IM][EtSO4]) is identified as the best IL solvent. The separation performance of [C2IM][EtSO4] in the ED process of propylene/propane is then evaluated through rigorous process simulation in Aspen Plus. For comparison, the conventional separation process of propane/propylene is also simulated and optimized. Based on the optimized operations, in-depth energy and economic assessment are conducted for an industrial-scale separation of propane/propylene in a Chinese refining industry. Remarkably, the [C2IM][EtSO4]-based ED process has 68.9% energy savings and 74.7% cost reduction when compared to the conventional process.

Mechanism analysis of solvent selectivity and energy-saving optimization in vapor recompression-assisted extractive distillation for separation of binary azeotrope

Octane and p-xylene are common components in crude gasoline, so their separation process is very important in petroleum industry. The azeotrope and near azeotrope are often separated by extractive distillation in industry, which can realize the recovery and utilization of resources. In this work, the vapor–liquid equilibrium experiment was used to obtain the vapor–liquid equilibrium properties of the difficult separation system, and on this basis, the solvent extraction mechanism was studied. The mechanism of solvent separation plays a guiding role in selecting suitable solvents for industrial separation. The interaction energy, bond length and charge density distribution of p-xylene with solvent are calculated by quantum chemistry method. The quantum chemistry calculation results and experiment results showed that N-formylmorpholine is the best solvent among the alternative solvents in the work. This work provides an effective and complete solvent screening process from phase equilibrium experiments to quantum chemical calculation. An extractive distillation simulation process with N-formylmorpholine as solvent is designed to separate octane and p-xylene. In addition, the feasibility and effectiveness of the intensified vapor recompression assisted extraction distillation are also discussed. In the extractive distillation process, the vapor recompression-assisted extraction distillation process is globally optimal. Compared with basic process, the total annual cost can be reduced by 43.2%. This study provides theoretical guidance for extractive distillation separation technology and solvent selection.

Features of distillation separation of multicomponent mixtures

Objectives. To improve the process of developing energy-efficient flowsheets for the distillation separation of multicomponent aqueous and organic mixtures based on a comprehensive study of the phase diagram structures, including those in the presence of additional selective substances.Methods. Thermodynamic-topological analysis of phase diagrams; modeling of phase equilibria in the AspenTech software package using the equations of local compositions: Non-Random Two Liquid and Wilson; computational experiment to determine the column parameters for separation flowsheets of model and real mixtures of various nature.Results. The fractionation conditions of the origin multicomponent mixture due to the use of sharp distillation, pre-splitting process, extractive distillation with individual and binary separating agents were revealed. The columns operation parameters and the energy consumption of the separation flowsheets ensuring the achievement of the required product quality with minimal energy consumption were determined.Conclusions. Using the original methods developed by the authors earlier and based on the generalization of the results obtained, new approaches to the synthesis of energy-efficient multicomponent mixtures separation flowsheets were proposed. The provisions that form the methodological basis for the development of flowsheets for the separation of multicomponent mixtures and supplement the standard flowsheet synthesis plan with new procedures were formulated.

Performance improvement potential of integrated process of urea‐adduction and distillation for separation of 1‐octene from F–T synthetic products

AbstractBACKGROUNDC8 α‐olefins are regarded as top value‐added compounds from Fischer–Tropsch (F−T) products. However, the separation of purified C8 α‐olefins has proven to be a daunting challenge owing to their relative volatility. As the traditional methods for C8 α‐olefins purification are energy‐ and capital cost‐intensive, an efficient method for the separation of n‐hydrocarbons and iso‐hydrocarbons will provide a valuable and more sustainable alternative to address these challenges.RESULTSIn the urea‐adduction method, the purity of 1‐octene was increased from 96.02 to 98.04 wt%, and the yield was 93.62 %, which broke the limitation of traditional distillation on the purification of 1‐octene. By combining the urea‐adduction method and distillation, a promising and energy‐efficient integrated separation process was proposed. First, it recovers C8 n‐hydrocarbons through adduction reactions. Second, 1‐octene and n‐octane are separated with integrated distillation technology. The results indicated that this process can be utilized to recover 1‐octene from the C8 fraction of F–T synthetic products with a recovery yield of 93.6 % and an increase in purity from 65.6 to 98.7 wt%. As shown in Fig. 6(b), process modeling demonstrates that it trims energy consumption to 50.1% and total TAC to 55.1% in comparison with the traditional separation process.CONCLUSIONIt was found that the integrated process can produce high‐purity 1‐octene, indicating that the integration process demonstrates clear potential advantages, such as reducing energy consumption and increasing economic value. This approach can be adopted on an industrial scale. © 2022 Society of Chemical Industry (SCI).

Impact of process configuration on energy consumption and membrane area in hybrid separation process using olefin-selective zeolite membrane

Light olefins, such as ethylene and propylene, are industrially produced in mixtures with paraffin, such as ethane and propane, and are generally separated from mixtures via distillation. Since distillation separation processes, especially for separating propylene–propane mixtures, have the largest energy consumption compared to other separation processes, more efficient separation processes are necessary. In this study, two hybrids of distillation and membrane-separation processes (Cases 1 and 2) were designed for separating a propane/propylene mixture: Case 1 includes single-stage membrane separation before the propylene–propane distillation column, and Case 2 is a configuration using two-stage membrane separation instead of the propylene–propane distillation column. The Ag-FAU and Ag-BEA zeolite membranes, where preferentially adsorbed olefins fill the pores, inhibiting paraffin permeance, were used in the separation processes. To evaluate separation performance, two indicators, i.e., energy consumption and membrane area were calculated via simulation. Furthermore, the operating condition in Case 2 was modified by utilizing the characteristics of the Ag-FAU membrane in Case 3, where a mixture of ethane and propane was obtained in the retentate stream. These results were compared with the distillation process as a benchmark, and the advantages of these hybrid separation processes were discussed.