Reactive Distillation Research Articles

Design and optimization of reactive distillation for enhancing supercritical transesterification process to produce biodiesel

The present study explored the optimization of a reactive distillation column (RDC) for biodiesel production using supercritical transesterification (SCTE). The SCTE process at high pressure and temperature, is known for water-sensitive flexibility and catalyst-free operation, and has shown promising advantages in biodiesel production. The steady-state simulations were conducted using Aspen Plus, with two RDC configurations: RDC-1, employing a single feed of oil and methanol, and RDC-2, utilizing separate feeds. Surprisingly, high conversion rates were achieved at only 8.5 MPa pressure. The study aiming to identify an optimized RDC design, systematically examined the impact of design parameters such as reflux ratio, feed temperature, and the number of reactive stages on conversion and energy requirements. Internal column specifications and species flow through each stage were investigated to comprehend reaction and separation processes. Temperature analysis revealed that preheating to 380 °C significantly improved conversion and reduced reboiler heat duty. RDC-1, with 9 reactive stages, demonstrated greater conversion efficiency, while RDC-2, with 11 stages, exhibited better biodiesel separation. By optimizing reflux ratios, the study achieved remarkable conversions with enhanced methanol separation. Cost estimation revealed that RDC-1 promoted lower capital and operating costs, making it a preferred design and an efficient option for SCTE-based biodiesel production.

An alternative to methanol recovery from ternary mixture: Replacing extractive with reactive distillation for maximizing economical potential and resource recovery

This paper investigates the recovery of methanol from the propylene oxide (PO)/methanol/water mixture using reactive distillation (RD). The mixture presents a challenge due to the azeotrope formation between PO and methanol. To overcome this challenge, three RD scenarios, designated as Case 1, Case 2, and Case 3, are proposed. The primary principle underlying these cases is leveraging a reaction between PO and water, resulting in the production of propylene glycol (PG). This reaction consumes PO and thus eliminates the PO-methanol azeotrope, and reduces reboiler duty via the release of reaction heat. Case 1 utilizes one reactive distillation column (RDC) and one conventional distillation column (CDC) to recover methanol while reducing a quarter of the water content via the PO-water reaction. High purity methanol is obtained in the RDC distillate, while high purity PG is collected at the bottom of the CDC. Likewise, Case 2 follows the same approach as Case 1, with an additional PO stream to halve the water content. On the other hand, Case 3 employs a single RDC with a greater additional PO stream to react with all water content in the mixture, yielding high purity methanol at the distillate and PG at the bottom. These cases are simulated using Aspen Plus software, and their designs are optimized to minimize the total annual cost (TAC). The results are compared to a base case, represented by the side-stream extractive distillation (SSED) method. Cases 1, 2, and 3 demonstrate TAC reductions of 7.8 %, 27.7 %, and 60 %, respectively, compared to the base case. Additionally, the PG produced by the PO-water reaction presents opportunities for generating extra profit of 6.356 × 107 $ a−1, 7.248 × 107 $ a−1, and 8.98 × 107 $ a−1 in Cases 1, 2, and 3, respectively. Given the financial benefits observed in each case, these configurations may serve as attractive alternative methods for methanol recovery from the PO/methanol/water mixture.

Reactive distillation configuration for the production of ethyl acrylate

Esters of acrylic acid have many industrial applications, but existing industrial processes are not economical. Ethyl acrylate, a precursor to polymers and other chemicals is one of them. The existing method of production of ethyl acrylate by esterification of acrylic acid with ethanol using a homogeneous catalyst and reactor-distillation combination has limitation in terms of product purity, corrosion and existence of possible side reactions. The present work proposes a novel reactive distillation (RD) column configuration for ethyl acrylate production, with 99.99 % acrylic acid conversion and 99.99 % ethyl acrylate purity with no effluent stream. The proposed configuration is analyzed using Aspen Plus steady-state simulation software. Sequential iterative sensitivity analysis is performed to obtain all structural and operating parameters leading to a minimum Total Annual Cost (TAC). The result shows that, there is 10.8 % improvement in the purity of aqueous stream using RD configuration compared to existing method and the overall TAC of the process at desired conditions is 87.77 × 103 $/year.

Novel side-reactor dividing wall column and reactive distillation process for enhanced electronic-grade propylene glycol monomethyl ether acetate production

The semiconductor industry is experiencing rapid growth and has become one of the largest sectors in the world. Propylene glycol monomethyl ether acetate (PGMEA) is prized for its exceptional properties and its ability to meet the stringent requirements as a solvent for electronic processing. This work aims to enhance the production of electronic-grade PGMEA through a practical and advanced intensified configuration. First, the kinetic reactor for propylene glycol monomethyl ether (PGME) synthesis has been modeled and pinpointed optimal operating conditions through sensitivity analysis. Subsequently, several process alternatives incorporating intensified techniques, such as the dividing wall column (DWC), pressure swing distillation (PSD), reactive DWC (RDWC), and side-reactor DWC (SR-DWC), have been investigated. These processes have been systematically designed and optimized through a sequential design procedure. Response surface methodology, a practical optimization method, has been employed to optimize the complex column's structure with the help of Aspen Plus and Minitab. Energy requirements and costs of all process alternatives were evaluated for a fair comparison. The SR-DWC-RD process has emerged as the most promising option, as it can save up to 11.5 % in energy requirements and 19.9 % in total annual costs. This practical design, complete with detailed optimal design parameters, presents significant opportunities for improving industrial PGMEA production.

Reactive distillation with inter-integrated vapor permeation for 1,3-Dioxolane production: Experiments, modeling, process analysis and design

To overcome the problem of difficult separation of the 1,3-dioxane (DOL)-H2O azeotrope in the production of DOL, a new high-integrated technology via reactive distillation (RD) with inter-integrated vapor permeation (VP) (abbreived as R-VP-D) was established. A series of R-VP-D experiments were conducted to find the effect of dedydration on reactant conversion and DOL content in the distillate. A two-dimensional VP module modeled by Aspen Custom Modeler (ACM) was combined with two RD modules in Aspen Plus to simulate the entire R-VP-D process, and the R-VP-D model was verified by experimental results. Then, by this model, systematic research on VP inserting position and membrane area on the reaction performance, reboiler and condenser duty, catalyst load, and TAC of the R-VP-D column was performed. The mechanism of how dehydration promotes reaction was explored. Finally, a new RD-VP-D technology for producing 99.9wt% DOL was designed and optimized. Two goals were achieved by inserting VP: obtaining a DOL-H2O mixture that crosses the azeotropic point in the distillate and improving reaction performance by removing by-product H2O. Under the optimal parameter, the energy consumption per unit product was reduced by 3.9% with less equipment, a simpler process, and less required land area compared with the RD with pressure swing distillation technology reported in the literature, and CO2 emissions were reduced by 4.0%. The reason why promotion effect is insignificant was explored, which is related to which of separation or reaction is the control step in RD process.

Biolubricant production from Indian mustard seed oil through ethyl biodiesel-2G precursor using K2CO3 as heterogeneous catalyst

Biolubricants are sustainable alternatives to mineral lubricants and offer environmental, economic and social benefits, including the possibility of producing bioproducts on-farm. Previous research showed that Indian mustard seed oil (IMSO) could be converted into biolubricants by double transesterification using potassium hydroxide as a homogeneous catalyst. The objective of this work was to study the effectiveness of the heterogeneous catalyst potassium bicarbonate (K2CO3) for the conversion of IMSO into biolubricant using an ethyl biodiesel precursor in a double transesterification-based process. The first transesterification reaction aimed to convert IMSO into ethyl biodiesel (IMSOEEs) by conducting the ethanolysis under various operating conditions to optimize the process. The optimal operating conditions obtained were: 78 °C, 1.01 bar, 4 wt% K2CO3, ethanol to oil molar ratio of 8, and a reaction time of 60 min (with addition of 25 wt% recycled glycerol at 60 min to improve demixing). The second transesterification reaction converted IMSOEEs into biolubricants through reactive distillation with 2-ethylhexanol (2 EH) under the following optimized operating conditions: 100 °C, 0.05 bar, 4 wt% K2CO3, 2 EH to IMSOEEs molar ratio of 4, and a reaction time of 120 min. Both ethyl biodiesel and biolubricant were produced with very satisfactory purity (≥96 wt%), thus meeting the expected functional properties.

1,3-Dioxolane production via reactive distillation combined with vapor permeation: Experiments and modelling

To overcome the problem of difficult separation of the 1,3-dioxane (DOL)–H2O azeotrope in the production of DOL, a new process via reactive distillation (RD) combined with vapor permeation (VP) was established. The reliability of the RD model has been reported in the literature. The VP membrane used an Aspen Custom Modeler (ACM) self-built model, with the permeation parameters of H2O, DOL, and formaldehyde (FA) in the membrane flux equation fitted through the H2O-DOL-FA dehydration experiments by NaA zeolite membrane. The results showed that the relative error between the mass of H2O in a series of permeates in experiments and simulated by the VP model was mainly within 20%, and R2 is 0.94. For DOL and FA, which have very small permeation, the value was within 50%, implying the reliability of the VP model. On this basis, a two-dimensional VP model was established. Finally, a new RD-VP-D process for producing DOL was designed. The VP was used to overcome the azeotropic point of DOL and H2O by dehydration. Then 99.9 wt% DOL can be obtained at the bottom of the subsequent DOL purification column, with DOL- H2O azeotrope at the top recycled back to the VP membrane. The effects of the degree of VP dehydration and column pressure on membrane area, reboiler duty, and TAC were investigated, meanwhile introducing a new concept: logarithmic mean partial-pressure difference (LMPD). Under the optimal parameter, TAC was reduced by 20.0% compared with the process reported in the literature, and CO2 emissions were reduced by 35.8%.

Performance analysis of reactive-extractive distillation for multi-azeotropic mixture based on the relationship between economy and conversion rate

The synthesis and purification of ethyl acrylate are of great importance in studying the coupling performance of reaction and separation. In this manuscript, reactive extractive distillation (RED), immiscible-assisted reactive extractive distillation (IRED), and high conversion rate process (HCP) were comprehensively studied. The conceptual design by quaternary phase diagram was demonstrated. The optimal extractant was selected based on relative volatility and quantum chemistry. Multi-objective algorithm was used to minimize gas emissions and total annual cost (TAC). Based on economic, environmental and profit etc., the RED, IRED, and HCP were evaluated. The results show that the TAC, gas emissions, exergy loss, energy consumption, and profit of IRED were decreased by more than 25 %, 21 %, 12 %, 14 %, and 26 % compared to RED. Besides, the profit of the IRED is better than that of the HCP, which indicates that higher conversion rate of the reaction cannot represent better economy of the reactive distillation process.

Process Modelling and Simulation of Reactive Distillation for the Synthesis of High Purity Mono Ethylene Glycol

Process Modelling and Simulation of Reactive Distillation for the Synthesis of High Purity Mono Ethylene Glycol

Artificial neural networks strategy to analyze the magnetohydrodynamics Casson-Maxwell nanofluid flow through the cone and disc system space

The Casson-Maxwell model is particularly useful for studying viscoplastic fluids or fluids with yield stress, making it applicable to various engineering applications, including extrusion processes, coating applications, and biomedical fluid dynamics. Casson-Maxwell fluid flow enhances mass transfer rates due to the combined effects of non-Newtonian viscosity and viscoelastic behavior. This is particularly useful in processes where mass transfer limitations play a significant role, such as in multiphase reactions or reactive distillation systems. In the context of the above applications the present model, is the combination of Casson- Maxwell fluids that flow through the varying gap of the spinning cone and disk system (CDS) for the heat transfer enhancement. The magnetic field is also imposed in the upright direction to the flow field. The solution of the transform equations has been obtained through artificial neural networks (ANN). The skin friction, heat transfer rate, and comparative analysis have been done. The Casson-Maxwell parameters that depend on the viscoelastic behavior and high viscosity term, causes the fluid to slow down and tends to store the temperature, for a long time as compared to traditional fluids. The radial component of velocity decreases due to the increase in magnetic field. The relative error of the reference and targeted dates is calculated to demonstrate the best precision efficiency of ANN, with a range of 10−3 to 10−4.

Optimal design and operation of reactive distillation systems and reactive dividing wall systems with pressure swing distillation and hybrid distillation-pervaporation

Process intensification is essential in exploring more energy-efficient processes, and key examples related to fluid separations are reactive distillation and hybrid distillation-pervaporation processes. This work will consider the reaction and separation of a general quaternary reactive system with a minimum boiling binary azeotrope AC, in a reactive distillation column where, given the thermodynamics limitations, further downstream separation is required. Low and high chemical equilibrium is considered for the reaction. For the downstream purification, both pressure swing distillation and a hybrid distillation-pervaporation process are considered. For each of the structures, their intensified equivalent dividing wall structures are also considered, including a hybrid reactive dividing wall system. It is shown that reactive distillation followed by a hybrid distillation-pervaporation system can save up to 24% energy compared to reactive distillation with pressure swing separation, and that the dividing wall column counterpart structures have lower production-based total annualised costs than the corresponding base systems.

A Study of ZSM-5 Molecular Sieve Shaping for an Innovative Cyclohexene Hydration Process

The development of the zeolite molecular sieves (ZSM-5) molding technique is essential for the cyclohexene hydration reaction distillation process in both industrial and research settings. The reactive distillation process can solve many of the drawbacks associated with the existing technique of manufacturing cyclohexanol via cyclohexene hydration, such as high catalyst digestibility, low conversion rate, and operational challenges. This study developed a series of molded ZSM-5 catalysts with various binder types and contents were constructed. The suggested pseudo-boehmite and hydroxypropyl methylcellulose were chosen as binders for extrusion molding of ZSM-5. The effects of binders on the strength reliability were investigated by strength tests and statistical analysis of the Weibull function. The effects of binders on the physical structure, acidity, and catalytic performance of ZSM-5 were investigated by X-ray diffraction, scanning electron microscopy, physical adsorption of N2, and desorption of NH3. The findings demonstrate that the addition of binder has no effect on ZSM-5's crystal structure. The experiment's results showed that the molded catalyst could be used for the hydration process with over 95% selectivity and a yield of 10.45% cyclohexanol. Copyright © 2024 by Authors, Published by BCREC Publishing Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Covalently assembling multi-dimensional carbon-based nanoclay composites via ionic liquid linkers into PVA membrane for molecular separation

The application of membrane-based separation technology in purifying azeotropic solutions plays a crucial role in minimizing energy consumption during reactive distillation. The strategic integration of multi-dimensional structural composites within mixed matrix membranes (MMMs), characterized by a robust framework and efficient molecular transport channels, poses challenges but demonstrates significant potential for advancing the development of high-performance membrane fabrication. Herein, we proposed a novel strategy to covalently assemble halloysite nanotubes (HNTs) and graphene oxide (GO) using ionic liquids (ILs) as linkers. When incorporated into the polyvinyl alcohol (PVA) matrix, the ILs@HNTs@GO (IHGO) composites exhibit excellent interfacial compatibility, and ILs also enhanced the composite’s selective transfer ability to water molecules. The optimal separation performance for pervaporation dehydration from a ternary solution was respectively 2.57 (selectivity) and 1.74 (permeability) times higher than those of the pristine PVA membrane. The structural stability of the MMMs and their separation mechanism has been comprehensively validated by adjusting the content of GO in IHGO composites and conducting simulations. This study holds significant theoretical and practical implications for organic compounds purification, while simultaneously paving new avenues for the fabrication of structurally robust and high-performance MMMs with optimal filler effectiveness.

Enhanced reaction extraction distillation via multi-objective optimization and 4E analysis for sustainable recovery of organic compounds from wastewater

Resource utilization and sustainable treatment of wastewater, which can achieve efficient energy utilization and environmental protection, have received hot social attention. Tetrahydrofuran and methanol are the two most common substances in pharmaceutical wastewater. It is very necessary to explore the wastewater treatment process containing these two substances. In this study, extractive distillation and reactive distillation were proposed to effectively separate the tetrahydrofuran-methanol-water component of pharmaceutical wastewater. To further reduce energy consumption, two strengthening processes, double-column reactive-extractive distillation and reactive-extractive dividing wall column distillation were designed. Taking the minimum operating and equipment cost as the objective function, the processes were optimized by using the multi-objective genetic optimization algorithm to obtain the best process parameters. Four processes were evaluated in terms of total annual cost, energy consumption, gas emissions and thermodynamic efficiency. Compared to the traditional three-column extractive distillation process, the above-mentioned four aspects of the reactive-extractive dividing wall column process was reduced by 40.63%, 43.13%, 43.14% and 17.71%, respectively. The reactive-extractive dividing wall column distillation process is of great significance for the efficient purification of valuable organic matter in wastewater and environmental protection.

Development of novel hybrid pre-separation/extractive reactive distillation processes for the separation of methanol/methyl acetate/ethyl acetate

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.

ENHANCING ESSENTIAL OIL YIELD: UTILIZING INTERNAL CHOPPER IN STEAM DISTILLATION

The objective of this study is to validate a novel method for chopping essential raw materials. To achieve this, we employed a distillation reactor equipped with an internal chopping module to enhance both the quantity and quality of Champaca essential oil production. Our experiments involved three variations of pre-distillation treatment: no chopping, chopping inside the reactor, and chopping outside the reactor. The distilled oil was subsequently analyzed using GC-MS. These three chopping methods resulted in varying amounts of linalool compounds. Unchopped essential materials yielded 6.54% linalool compounds, while internal chopping produced 32.33%, and external chopping resulted in 7.40% linalool compounds. The internal chopping method proved to be the most effective in increasing linalool compound content. Consequently, we can conclude that chopping materials within the distillation reactor during the steam distillation process significantly enhances the main compound's content.

Novel dynamic control structure of reactive distillation process for isopropanol production via transesterification

Due to the complicated interaction between reaction and separation in a column, it was inherently challenging to design a control structure for the reaction distillation process. In this research, the control structures of the hybrid reactive distillation process combining pressure-swing distillation (RDC-HDC) and its thermal coupling (RDWC-HDC) processes, were explored for producing isopropanol (IPA) by isopropyl acetate (IPAC) with methanol (MeOH) transesterification. The control performances of only temperature control and temperature difference control schemes for RDC-HDC process were first investigated. The research results displayed that double temperature control (CS3) and temperature difference control schemes (CS4–1, CS4–2 and CS5) for the RDC-HDC process could shorten the maximum transient deviation, amplitude of oscillations and setting time in face with ±20% throughout and ±5% feed composition disturbances. To further improve control characteristics and make control structures concise, a novel control strategy (CS6) by a proportional controller adjusted by reverse action of an IPAC component controller in 34 trays for keeping IPAC composition at a certain range in the RDC-HDC process was developed based on the closed loop analysis before and after disturbance. The application of the innovative control structures (CST4) to the RDWC-HDC process was equally feasible in face of ±10% throughout and ±5% feed composition disturbances. The analysis of integral of squared error (ISE) indicated that a novel control strategy (CS6 and CST4) had better robustness and dynamic performance. These studies contributed to the development of controllability for hybrid reactive distillation processes to produce chemicals for reaction and separation.

Conceptual methods for synthesis of reactive distillation processes: recent developments and perspectives

AbstractReactive distillation (RD) is a process intensification technique that offers major advantages over conventional technologies by enabling the integration of reaction and separation into a single apparatus. This integration introduces and exploits complex interaction between mass transfer, chemical reaction and hydrodynamics within an RD column; however, these complexities can hinder the adoption of RD by industry. Many approaches have been developed by the scientific community to advance understanding and to expedite the initialization of RD design at the conceptual level. This paper critically discusses recent developments in conceptual methods for synthesizing RD processes. This review paper is the first to consider the range of available approaches for assessing the technical feasibility, controllability, economic viability, and sustainability of RD units by taking into account various configurations in which RD is treated as a new unit operation, and as part of process synthesis in a different way of designing processes based on functions. The review also addresses complex configurations, such as advanced RD technologies. Special attention is paid to process modeling and simulation as well as to education. Knowledge gaps to be filled by further research are indicated. © 2024 The Authors. Journal of Chemical Technology and Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry (SCI).

Isolation of ammonium bicarbonate by reactive distillation of food waste digestate liquor

Distillation is among the best techniques for management of ammoniacal nitrogen in anaerobic digestate; however, the suitability of the conventional system is neglected in favor of using more advanced setups. This investigation proves the reliability of the classical batch distillation apparatus for high throughput separation of solid crystals of ammonium bicarbonate from food waste digestate (FWD) liquor. Three replicates were carried out: 80 g of FWD liquor with a content of 50 g/L NH4HCO3 was processed for 7.5 h under minimum heating power (<60 °C) and 200 rpm to avoid excessive foam formation. After performing the reactive distillation, 81 % of NH4HCO3 was recovered as white solid crystals at the top of the distillation still. Although the distillation provided a solid material with the same structure and composition as those of the reagent-grade NH4HCO3, the stability of the isolated inorganic fertilizer was poorer, and it could lead to pollution swapping.

Biobased propylene glycol production in a sugarcane biorefinery through lactic acid, glycerol, or sorbitol: A techno-economic and environmental evaluation of intermediates and downstream processing methods

Propylene glycol (PG) is a versatile chemical which can be produced by direct fermentation of sugars or through intermediates like lactic acid (LA), glycerol and sorbitol. Few studies have examined producing PG from different intermediates in terms of economic feasibility. In this study, seven process scenarios were assessed in a biorefinery annexed to an existing sugar mill. Aspen simulations were developed for each scenario as the basis for mass and energy balances, techno-economic, and environmental evaluations. Scenario 1 (LA intermediate) had the lowest minimum selling price (MSP) of 1991 US$t−1 and greenhouse gas (GHG) emissions of 1.24 kgCO2/kgPG which was the best intermediate investigated. Scenario 2a-2d (glycerol intermediate) was used to offer insights on the economic benefits of different design changes to the process. Scenario 2a investigates the use of reactive distillation as opposed to normal distillation in the other scenarios. Scenario 2c and 2d offer insights on the purchasing of green hydrogen as an alternative to producing onsite and effect of increased hydrogen ratios respectively. The MSP for the scenarios ranged from 2121–2863 US$.t−1 and GHG emissions of 0.8–2.2 kgCO2/kgPG. Scenario 3 (sorbitol intermediate) had the poorest performance with an MSP of 2751 US$t−1 and GHG emissions of 2.22 kgCO2/kgPG. Scenario 4 (combined first and second-generation feed) had an MSP of 2065 US$t−1 and 1.04 kgCO2/kgPG for GHG.