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Glycerol carbonate (GC) can be produced from glycerol (GL), a low-value byproduct in the biodiesel industry. In this work, continuous processes of GC production via transesterification from crude GL and diethyl carbonate (DEC) were developed using Aspen Plus. Two cases were considered, and their process performances were compared. In Case I, a conventional design consisted of a continuously stirred tank reactor for the reaction section and a distillation column for the purification section. In Case II, a process intensification design consisted of a reactive distillation column that could accommodate both reaction and purification within a single column. In both cases, the process optimizations were carried out by connecting the process models in Aspen Plus to MATLAB, using the Genetic Algorithm as the optimizer. The results showed that Case II was superior to Case I in terms of energy utilization, CO2 emissions, and economics with the specific energy consumption of 1.92 kWh/kg of diethyl carbonate, % internal rate of return of 274, payback period of 1.44 years, and CO2 emissions of 0.26 kg CO2/kg DEC. Lastly, the proposed process in Case II was compared with the GC production using dimethyl carbonate (DMC). It was found that using DEC was superior to DMC due to easier separation and glycidol avoidance. [ABSTRACT FROM AUTHOR]

The excessive mineralization of organic molecules during anaerobic fermentation increases the availability of nitrogen and carbon. For this reason, the development of downstream processing technologies is required to better manage ammonia and carbon dioxide emissions during the storage and land application of the resulting soil organic amendment. The present work investigated classical distillation as a technology for valorizing ammoniacal nitrogen (NH4+-N) in anaerobic digestate. The results implied that the direct isolation of ammonium bicarbonate (NH4HCO3) was possible when applying the reactive distillation to the food waste digestate (FWD) with a high content of NH4+-N, while the addition of antifoam to the agrowaste digestate (AWD) was necessary to be able to produce an aqueous solution of NH4HCO3 as the distillate. The reason was that the extraction of NH4HCO3 from the AWD required a higher temperature (>95 °C) and duration (i.e., steady state in batch operation) than the recovery of the inorganic fertilizer from the FWD. The titration method, when applied to the depleted digestate, offered the quickest way of monitoring the reactive distillation because the buffer capacity of the distillate was much higher. The isolation of NH4HCO3 from the FWD was attained in a transient mode at a temperature below 90 °C (i.e., while heating up to reach the desired distillation temperature or cooling down once the batch distillation was finished). For the operating conditions to be regarded as techno-economically feasible, they should be attained in the anaerobic digestion plant by integrating the heat harvested from the engines, which convert the biogas into electricity. [ABSTRACT FROM AUTHOR]

Abstract Glycerol carbonate (GC) can be produced from glycerol (GL), a low-value byproduct in the biodiesel industry. In this work, continuous processes of GC production via transesterification from crude GL and diethyl carbonate (DEC) were developed using Aspen Plus. Two cases were considered, and their process performances were compared. In Case I, a conventional design consisted of a continuously stirred tank reactor for the reaction section and a distillation column for the purification section. In Case II, a process intensification design consisted of a reactive distillation column that could accommodate both reaction and purification within a single column. In both cases, the process optimizations were carried out by connecting the process models in Aspen Plus to MATLAB, using the Genetic Algorithm as the optimizer. The results showed that Case II was superior to Case I in terms of energy utilization, CO2 emissions, and economics with the specific energy consumption of 1.92 kWh/kg of diethyl carbonate, % internal rate of return of 274, payback period of 1.44 years, and CO2 emissions of 0.26 kg CO2/kg DEC. Lastly, the proposed process in Case II was compared with the GC production using dimethyl carbonate (DMC). It was found that using DEC was superior to DMC due to easier separation and glycidol avoidance.

The Z-alkene geometry is prevalent in various chemical compounds, including numerous building blocks, fine chemicals, and natural products. Unfortunately, established Mo, W, and Ru Z-selective catalysts lose their selectivity at high temperatures required for industrial processes like reactive distillation, which limits their synthetic applications. To address this issue, we develop a catalyst capable of providing Z-alkenes with high selectivity under harsh conditions. Our research reveals a dithiolate ligand that, stabilised by resonance, delivers high selectivity at temperatures up to 150 °C in concentrated mixtures. This distinguishes the dithioquinoxaline complex from existing Z-selective catalysts. Notably, this trait does not compromise the new catalyst's usability under classical conditions, matching the activity of known stereoretentive catalysts. Density Functional Theory calculations were employed to understand the reaction mechanism and selectivity, and to investigate the poisoning that the catalyst may undergo and how it competes with catalytic activity. Furthermore, the quinoxaline-based catalyst enables the valorisation of bio-sourced alkene feedstocks and the production of agricultural sex pheromones for pest control. The Z-alkene geometry is prevalent in various chemical compounds, but established Mo, W, and Ru Z-selective catalysts lose their selectivity at high temperatures, which limits their synthetic applications. Here, the authors develop a catalyst capable of providing Z-alkenes with high selectivity under harsh conditions. [ABSTRACT FROM AUTHOR]

Biodiesel is a sustainable and renewable fuel generated from renewable resources, including vegetable oil or animal fats. It is thought to be a non-toxic fuel that degrades gradually and causes no harm to the environment. In the present study, a non-conventional supercritical method for industrial biodiesel production is investigated. The non-conventional method refers to a single-step interesterification reaction between triglycerides and methyl acetate resulting in methyl esters of fatty acids and triacetin as a secondary product. Process flowsheet modeling, using CHEMCAD chemical engineering software, was used as an investigation tool. The production capacity was set to 25,000 kg/h biodiesel. Methyl acetate requested in the biodiesel production is produced from methanol esterification with acetic acid using an intensified reactive distillation unit. Methanol, in turn, is obtained using synthetic gas derived from biomass as a raw material, the process representing a new method at the industrial level to solve problems related to the energy that is required, storage and disposal of residual materials, and pollution through the release of pollutants into the air. The methanol synthesis process is similar to the one based on natural gas, consisting of three main steps, namely: (i) synthesis gas production, followed by (ii) methanol production, and (iii) methanol purification. Acetic acid is an essential chemical product, generated in the proposed approach by a sustainable method with low energy consumption and low air emissions, more exactly methanol carbonylation. All the processes previously mentioned: (i) biodiesel production, (ii) methyl acetate production, (iii) acetic acid production, and (iv) methanol production were modeled and simulated, leading to the desired biodiesel productivity (e.g., 25,000 kg/h) with the obtained purity being higher than 99%. Relevant discussions regarding the design assumptions used, the simulation and validation results, as well as other technical issues (i.e., electricity and thermal energy consumption) for the system being simulated, are provided, leading to the conclusion that the proposed route is well suited for the desired application and can deliver significant results. The simulation outcomes have provided confidence in the feasibility and effectiveness of the chosen process design, making it a viable option for further development and implementation. [ABSTRACT FROM AUTHOR]

Hydrogen energy, as a clean, renewable, and high-calorific energy carrier, has garnered significant attention globally. Among various hydrogen production methods, the thermochemical iodine–sulfur (I-S) cycle is considered the most promising due to its high efficiency and adaptability for large-scale industrial applications. This study focuses on the distillation characteristics of the HIx (HI–I2–H2O) solution within the I-S cycle, which is crucial for achieving the high-concentration HI necessary for efficient hydrogen production. Previous methods, including phosphoric acid extraction–distillation and reactive distillation, have addressed azeotrope issues but introduced complexities and equipment demands. This research constructs a hypo-azeotropic HIx solution distillation experimental system and uses the Aspen Plus v14 software to optimize distillation parameters. By analyzing the effects of feed stage, reflux ratio, and feed temperature, the study provides essential data for improving distillation efficiency and supports the scale-up of I-S cycle technology. The findings indicate that optimal distillation is achieved with a feed position at 1/3 column height, a reflux ratio of 1.4, and a feed temperature near the boiling point, enhancing the feasibility of industrial hydrogen production via the I-S cycle. [ABSTRACT FROM AUTHOR]

Biodiesel, known as a renewable fuel, is an environmentally friendly energy source derived from animal and vegetable oils, as well as recycled oil. Despite this, the current advancements in biodiesel technology face challenges in fully replacing petrochemical diesel, primarily due to the non-green catalytic synthesis and high production cost associated with biodiesel. Ionic liquids containing strong Lewis acids or Brønsted acids have been highlighted as a novel class of environmentally friendly solvents and catalysts, showing green and effective catalytic potential in the synthesis of biodiesel via transesterification. In another aspect, reactive distillation technology could facilitate continuous forward reactions catalyzed by ionic liquids by swiftly removing reaction products from the reaction zone, offering advantages in improving the production efficiency, energy consumption, and cost reduction. From this perspective, we discuss the synthesis of biodiesel catalyzed by ionic liquids, supported ionic liquids, amphiphilic ionic liquids, and amphiphilic supported ionic liquids. The focus is on the process for synthesizing biodiesel through catalytic distillation. We emphasize the potential role of the lipophilic group in the ionic liquid catalyst, promoting the mutual solubility of the reactant triglyceride with methanol or ethanol. This enhancement might facilitate contact between the reactants and improve the catalytic efficiency of transesterification. Additionally, we propose several methods to improve the efficiency of biodiesel synthesis catalyzed by ionic liquid catalysts and suggest appropriate reactive distillation processes for biodiesel production. [ABSTRACT FROM AUTHOR]

A novel time-varying neural network (TVNN) architecture incorporating time dependency explicitly, proposed recently, for modeling nonlinear non-stationary dynamic systems is further developed in the present study to extend it to multi-input multi-output (MIMO) systems, and two configurations are proposed to represent dynamics of multivariable batch chemical processes. The first model (TVNN-multi-input single-output (MISO) model) consists of an input layer with M inputs representing the past samples of process inputs and outputs, a hidden layer with polynomial activation function, and a second hidden layer of L neurons acted upon by an explicitly time-dependent modulation function, which are combined to result in the output layer with a single output. This model is developed for each output in the MIMO system. In the second model (TVNN-MIMO model), multiple outputs are incorporated in the output layer. Back-propagation learning algorithm is formulated for the proposed neural network structures to determine the weights for each network configuration. The modeling capability of these networks is evaluated by employing it to represent the dynamics of a reactive batch distillation column for an esterification reaction. The results show that both the proposed neural networks configurations represent each composition of the reactive batch distillation dynamics accurately. Further, both the TVNNs exhibited better performance than time-independent networks trained using the same configuration. Both the TVNN configurations resulted in comparable performance, while the TVNN-MIMO model is more compact and requires less number of parameters. The present study illustrates that the proposed approach can be applied to represent dynamics of any batch/semi-batch process. [ABSTRACT FROM AUTHOR]

Reactive 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). [ABSTRACT FROM AUTHOR]

This work presents a superstructure for maximizing the annual profit of biodiesel production with Advanced Interactive Multidimensional Modeling System (AIMMS). The novelty features are the combination of pinch-based heat integration with a wide range of biodiesel feedstocks and the application of superstructure to evaluate the effect of uncertainties on the optimized design. The case study is a pilot refinery with the infeed capacity of 8000 tonnes feedstock per year. The biodiesel production route from tallow with reactive distillation technology and a heterogeneous acid catalyst has the highest total annual profit of 3.5 million USDs. The heating and cooling utilities can be reduced by 30 % with the heat integration. The result from the sensitivity analysis shows that the biodiesel and feedstock prices, and the production capacity have the most pronounced effects. From technical assessment, the reactive distillation process is the best choice for biodiesel production from different feedstocks. [ABSTRACT FROM AUTHOR]

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).

Micro-distillation is one of the unit operation technologies that are looking toward innovation through on-site and on-demand production system. In this study, a simple structure microdistillator consisting of some plates was applied to reactive distillation, and its potential was investigated. As a target reaction, the heterogeneous esterification between acetic acid and methanol using a solid acid catalyst was employed. The effects of feedstock supply rate, feedstock composition, and device temperature on operation stability and conversion were examined. By controlling the feedstock supply rate and temperature properly, a stable operation with a conversion of approximately 100% was successfully achieved. The amount of methyl acetate produced per weight of catalyst was greater in the reactive distillation using a microdistillator than in the batch reaction, soon after the start of the reaction. Thus, it was demonstrated that the reactive distillation using a microdistillator was able to achieve highly efficient reactions with short reaction time and small amounts of catalyst. [ABSTRACT FROM AUTHOR]

Conventional dimethyl maleate (DMM) synthesis relies on the use of sulfuric acid as a catalyst which requires water washing and produces a large amount of wastewater that harms the environment. The use of this method is expensive since it involves numerous processes such as neutralization of sulfuric acid, washing with water, distillation etc. and the yield of dimethyl maleate is not very high. Reactive distillation integrates the two important industrial processes such as reaction and distillation into a single unit which shortens the overall process, reduces capital and operating costs, and maintains the reaction in a forward direction to enhance the conversion of maleic anhydride by continuously removing of the products. In this work, simulation study based on experimental investigation of reactive distillation process for the synthesis of dimethyl maleate was carried out using Aspen Plus V11. DZH strong cation exchange resin was used as catalyst for esterification reaction of maleic anhydride with methanol. A reactive section of column was packed with Katapak SP type packing loaded with DZH catalyst while non-reactive sections consist of wire gauze packing. In order to describe a reactive distillation process for synthesis of dimethyl maleate, RAD-FRAC equilibrium stage model was employed. The NRTL activity model and RK equation of state model were selected to describe vapor-liquid equilibrium of the system. The reliability of the developed simulated model was verified by validating the simulation results with the experimental ones. The effect of various design and operating parameters on the conversion of maleic anhydride and purity of dimethyl maleate has been studied. It was found that the optimal condition for RD, were as follow: total number of theoretical stages 17, rectifying stages 3, reactive stages 7, stripping stages 5, reflux ratio 0.25, operating pressure 0.1 MPa, reboiler duty 250 Cal/Sec, feed mole ratio 1:5. Under optimized condition the water formed as a results of esterification reaction was constantly removed from the reactive section of the column to maintain reaction balance, the conversion of maleic anhydride was 99.95 %, purity of dimethyl maleate achieved was 0.997 and the reactive distillation process was feasible to produce dimethyl maleate without any wastewater. [ABSTRACT FROM AUTHOR]

A novel method to prepare asymmetric amine ethers is reported. Tertiary amine alcohol hydrogen sulfate intermediates are prepared through a reactive distillation process, followed by the transesterification process to afford eventually asymmetric amine ethers. Experiments and DFT calculations revealed the essential roles the sulfate group plays in the highly selective monoesterification process. This clean method is tolerant towards various functional groups with good yields under mild condition, which is obviously superior compared to the conventional processes. [ABSTRACT FROM AUTHOR]

In an effort to synthesize chemically recyclable thermoplastic elastomers, a redox‐switchable catalytic system was developed to synthesize triblock copolymers containing stiff poly(lactic acid) (PLA) end blocks and a flexible poly(tetrahydrofuran‐co‐cyclohexene oxide) (poly(THF‐co‐CHO) copolymer as the mid‐block. The orthogonal reactivity induced by changing the oxidation state of the iron‐based catalyst enabled the synthesis of the triblock copolymers in a single reaction flask from a mixture of monomers. The triblock copolymers demonstrated improved flexibility compared to poly(l‐lactic acid) (PLLA) and thermomechanical properties that resemble thermoplastic elastomers, including a rubbery plateau in the range of −60 to 40 °C. The triblock copolymers containing a higher percentage of THF versus CHO were more flexible, and a blend of triblock copolymers containing PLLA and poly(d‐lactic acid) (PDLA) end‐blocks resulted in a stereocomplex that further increased polymer flexibility. Besides the low cost of lactide and THF, the sustainability of this new class of triblock copolymers was also supported by their depolymerization, which was achieved by exposing the copolymers sequentially to FeCl3 and ZnCl2/PEG under reactive distillation conditions. [ABSTRACT FROM AUTHOR]

Esterification of acetic acid with methanol to produce methyl acetate and water has been studied in a continuous packed bed catalytic reactive distillation. The key challenge is the startup method of the experiments fora continuous reactive distillation as well as reactive zone height selection. In the present study, the effect of various operating conditions on the methyl acetate composition (mole fraction) is studied. Indion 180 ion-exchange resin solid catalyst is used in the reactive zone. The catalyst is immobilized by using a novel equivalent Katapak-S in the reactive section. Experiments were performed under different operating conditions to find the high purity methyl acetate product in the distillation. The experiments were performed for various conditions like total feed flow rate, reboiler temperature, reflux ratio, methanol to acetic acid mole ratio and catalyst loading with the time. The experiments were carried out till the system reaches to the steady state under different conditions. The maximum methyl acetate concentration is obtained at 80 °C reboiler temperature, 2.01 reflux ratio, 16.3 g/min flow rate, 60 g catalyst loading and 1 mol ratio of methanol to acetic acid. The highest purity of methyl acetate obtained under optimal condition is 95 % by mole. [ABSTRACT FROM AUTHOR]

In the traditional production of acetic esters, water generated in the esterification reaction can form azeotropes with the ester or the unreacted alcohol, which requires subsequent multi-step distillation or extraction to purify the esters. A large number of intermediate streams in the separation process need to consume a lot of steam to obtain high-purity acetic esters, resulting in a high total energy consumption. In this review, a new extraction separation and purification technology, namely the salting-out effect for the purification of acetic esters, was summarized. Different salting-out agents were used to reduce the concentration of water/alcohols in the ester phase and increase the selectivity coefficient of esters to minimize energy consumption. The scaled particle theory provides a clear guideline for the baseline on the separation goal of the alkyl acetate/alcohol/water systems. Extractive distillation, reactive distillation, azeotropic distillation, pervaporation, adsorption, salting-out assisted distillation, and hybrid salting-out-distillation were compared to assess their advantages and disadvantages. Energy-saving production and separation of acetic esters can be achieved with the hybrid salting-out-distillation process because the salting-out agents are cheap, non-toxic, and non-volatile, and the salting-out process can be conducted at room temperature. [ABSTRACT FROM AUTHOR]

In this work, a partial heat-integrated reactive distillation process was studied to yield n-propyl acetate. To optimize the operating parameters of two distinct processes, the sequential iteration optimization method was employed. The heat exchanger network (HEN) is an effective approach for the heat-integrated design of a distillation process. Compared with the conventional reactive distillation process, the total annual cost, CO2 emissions and total energy consumption of the partial heat-integrated reactive distillation process decreased by 20.7%, 31.1%, and 32.2%, respectively. The thermodynamic efficiencies of reactive distillation process and partial heatintegrated reactive distillation process were 4.33% and 9.86%, respectively. The significance of this paper is crucial in guiding the process of partial heatintegrated reactive distillation for the production of n-propyl acetate. [ABSTRACT FROM AUTHOR]

Combined processes in chemical industry are of current increasing interest, since they present a feasible solution for capital and operating expenses optimization. Multiplicities, which are specific to combined processes, cause certain control and design difficulties, thus, parametric sensitivity analysis and defining the range of existing multiplicities are the necessary part of the sustainable design and development of the combined process. Parametric and design optimization is the way of decreasing capital and operational costs. The paper discusses optimization of the design and operating parameters of an ethyl-tert-butyl ether synthesis reactive distillation column. The research aims to perform a parametric sensitivity analysis and explore existent multiple steady states of the process. The areas of multiple steady states are established, the optimal column design is developed, the optimal operation modes are determined. The procedure suggested in the study is universally applicable for design and optimization of other reactive distillation processes. [ABSTRACT FROM AUTHOR]

Reactive distillation (RD) combines chemical reactions and separation in a single unit essential to equilibrium-limited reactions. This new technique encompasses multiple advantages over traditional processes, including lower operating costs, increased thermal energy efficiency, high product selectivity, high purity percentage, and lower environmental impact. This paper provided an overview of the features, industrial applications, and industrial perspective of advanced reactive distillation technologies (ARDTs). This study focused on five under-development ARDTs: reactive dividing wall column (R-DWC), reactive high-gravity distillation (R-HiGee), reactive heat-integrated distillation column (R-HIDiC), catalytic cyclic distillation (CCD), and membrane-assisted reactive distillation (MA-RD). The primary drivers for new RD applications are reduced number of vessels, reduced residence time and holdup volume, increased mass and heat transfer, overcoming azeotropes, and prefractionation or impurity removal. ARDT's potential has yet to be studied, and research remains active to improve it further by investigating other RD technologies, simulation, and optimization techniques. [ABSTRACT FROM AUTHOR]

A novel methodology for the techno-economic assessment of Reactive Distillation (RD) is presented. The developed methodology benchmarks reactive distillation (RD) to a conventional reactor + distillation train flowsheet (R+D) on a cost-optimized basis, with the optimization being performed on the process unit level (reactor sizing, number of stages, feed point(s)) and the internals level (reactive tray design). This methodology is applied to the ideal quaternary system A + B ↔ C + D with the conventional boiling point order of T C < T A < T B < T D (α AD = 4, α BD = 2, α CD = 8). From this pool of data, a regime map of RD vs. R+D is established in which the attractive regions of either flowsheet option are identified in terms of the chemical reaction rate and chemical equilibrium. It is found that RD can arise as the cost optimal option for a large range of residence time requirements by virtue of overcoming the external recycle requirements of R+D. This is achieved through optimized reactive tray design. Contrary to conventional distillation design practices, it was found that the preferred use of bubble-cap trays over sieve trays to allow elevated weir heights and designing the column diameter below 80% of flooding become relevant design choices when accommodating high liquid holdup. • Framework to perform techno-economic evaluation of Reactive Distillation with emphasis on cost of high residence time. • Optimized reactive tray design leads to significantly different designs than for conventional distillation. • Benchmarking shows potential for Reactive Distillation for equilibrium limited reaction, even at high residence time. [ABSTRACT FROM AUTHOR]

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

In this study, multi-objective optimization of reactive dividing wall column is presented. Production of methyl acetate from acetic acid and methanol is taken as case study. Machine learning approach is introduced in this work by means of artificial neural network and genetic algorithm. Required data generation, input and output variable fixation to model neural network is done from the sensitivity analysis. Based on the dataset, neural network model is trained by Lavenberg–Marquardt algorithm and predict purity and TAC of column with high accuracy. Further parametric constrained optimization of systems has been done using multi-objective genetic algorithm and set of pareto optimal solution is generated. Based on gray relational analysis, best optimal point found out. After optimization the system gives significant reduction on TAC and enhancement in purity. Results shows reactive dividing wall column reduces total annual cost around 17.77%. All the results in present work is validated with exiting literature and also cross validated with ASPEN plus. [ABSTRACT FROM AUTHOR]

This study aimed to design energy-efficient systems for reactive distillation to simultaneously produce methyl tert-butyl ether (MTBE) and ethyl tert-butyl ether (ETBE) from mixed feeds of methanol and ethanol. In this work, two new designs are proposed. One is the individual production of each ether, involving two reactive distillation columns after feed alcohol separation, while the other for the co-production of both ethers in a single reactive distillation column without the alcohol separation. Rigorous simulations of the two proposed systems were conducted with varying ratios of the two alcohols in actual process streams. When the methanol feeding was dominant, the co-production system exhibited better performance than the individual ether production system. This was due to the lower temperatures inside the alcohol separation column, resulting in a lower relative volatility of methanol and increasing the heat duty in the alcohol separation column. However, when the amount of ethanol was higher than that of methanol, the individual production system outperformed the co-production system. This was attributed to the unfavorable reaction equilibrium of ETBE production, leading to a high internal flowrate in the co-production reactive distillation column. The external heat integration of each design can bring further reduction in energy consumption and CO2 emissions, but the results follow the same dependence on the feed alcohol ratio. [ABSTRACT FROM AUTHOR]

A new process for the synthesis of ethyl methyl carbonate through reactive extractive distillation was proposed to address the difficulties in separating azeotropic mixtures and the excessive formation of byproduct (diethyl carbonate) in the production of ethyl methyl carbonate via reactive distillation. Using Aspen Plus software, the effect of the extractant (diethyl carbonate) on the vapor-liquid equilibrium of the system was first investigated. Then the reactive extractive distillation column was simulated to study the effects of the number of theoretical plates in the reaction section, the number of theoretical plates in the extraction section, the feeding position, entrainer ratio, and reflux ratio on the reactive extractive distillation process. Under the optimized process parameters, the molar fraction of dimethyl carbonate at the top of the reactive extractive distillation column was reduced to 0.49%, and the single conversion of dimethyl carbonate, selectivity of ethyl methyl carbonate, and ethyl methyl carbonate yield reached 83.5%, 99.9% and 83.4% respectively. Finally, a process for the reactive extractive distillation was designed with the objective function of total annual cost, achieving process parameters that meet the production requirements. It was found by comparison that the reactive extractive distillation process exhibits better economic performance than conventional reactive distillation processes when the added value of 1 t of ethyl methyl carbonate is 145.50 CNY higher than that of diethyl carbonate. [ABSTRACT FROM AUTHOR]

Waste crude glycerol from the production of biodiesel could be used as a raw material for a product with added value. The purpose of this research was to assess the technical and economic aspects of the production process for glycerol carbonate. An innovative multi-functional reactive distillation (RD) was designed to beyond the augmentation of chemical reactions through product separation. It also encompasses the evaporation of water from the purified crude glycerol. A high purity of 99.999% and good chemical performances of 93.20% glycerol conversion and 93.13% yield of glycerol carbonate were obtained. The net present value (NPV), payback period (PP), and internal rate of return (IRR) are 5,480,000 USD, 5.69 years, and 20.9%, respectively. The sensitivity analysis revealed that the costs of raw materials and the main product have a significant impact on both NPV and PP. To increase the process profitability, the price of crude glycerol should be less than 0.44 USD/kg and the price of glycerol carbonate should be more than 3.15 UDS/kg. This finding suggests that using crude glycerol as a by-product of biodiesel synthesis is an excellent option for developing new, higher-value products, making a significant contribution to zero-waste principles and the circular economy.

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

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

The conceptual design and engineering of an integrated catalytic reactor requires a thorough understanding of the prevailing mechanisms and phenomena to ensure a safe operation while achieving desirable efficiency and product yields. The necessity and importance of these requirements are demonstrated in this investigation in the case of novel membrane-assisted reactors tailored for CO2 hydrogenation. Firstly, a carbon molecular sieve membrane was developed for simultaneous separation of CO2 from a hot post-combustion CO2-rich stream, followed by directing it along a packed-bed of hybrid CuO-ZnO/ZSM5 catalysts to react with hydrogen and produce DiMethyl Ether (DME). The generated water is removed from the catalytic bed by permeation through the membrane which enables reaction equilibrium shift towards more CO2-conversion. Extra process intensification was achieved using a membrane-assisted reactive distillation reactor, where similarly several such parallel membranes were erected inside a catalytic bed to form a reactive-distillation column. This provides the opportunity for a synchronized separation of CO2 and water by a membrane, mixing the educts (i.e., hydrogen and CO2) and controlling the reaction along the catalytic bed while distilling the products (i.e., methanol, water and DME) through the catalyst loaded column. The hybrid catalyst and carbon molecular sieve membrane were developed using the synthesis methods and proved experimentally to be among the most efficient compared to the state-of-the-art. In this context, selective permeation of the membrane and selective catalytic conversion of hybrid catalysts under the targeted operating temperature range of 200–260 °C and 10–20 bar pressure were studied. For the membrane, the obtained high flux of selective CO2-permeation was beyond the Robeson upper bound. Moreover, in the hybrid catalytic structure, a combined methanol and DME yield of 15% was secured. Detailed results of catalyst and membrane synthesis and characterization along with catalyst test and membrane permeation tests are reported in this paper. The performance of various configurations of integrated catalytic and separation systems was studied through an experimentally supported simulation along with the systematic analysis of the conceptual design and operation of such reactive distillation. Focusing on the subnano-/micro-meter scale, the performance of sequential reactions while considering the interaction of the involved catalytic materials on the overall performance of the hybrid catalyst structure was studied. On the same scale, the mechanism of separation through membrane pores was analyzed. Moreover, looking at the micro-/milli-meter scale in the vicinity of the catalyst and membrane, the impacts of equilibrium shift and the in-situ separation of CO2 and steam were analyzed, respectively. Finally, at the macro-scale separation of components, the impacts of established temperature, pressure and concentration profiles along the reactive distillation column were analyzed. The desired characteristics of the integrated membrane reactor at different scales could be identified in this manner. [ABSTRACT FROM AUTHOR]

This paper investigates the selective oligomerization of isobutene in mixed C4 using ethanol as an inhibitor. The effects of ethanol/isobutene, reaction temperature, and reaction space velocity on isobutene oligomerization were examined using two β molecular sieve catalysts. The results indicate that the optimal reaction conditions, at the same calcination temperature, are as follows: The mass ratio of ethanol to isobutylene is 20%, the reaction pressure is 1 MPa, the reaction temperature is 65°C, the reaction space velocity is 2 h−1, the dimerization product C8 has fewer types, and the selectivity can reach over 15%. After adding ethanol, there is a significant inhibitory effect on n‐butene. Furthermore, we used reactive distillation technology to simulate isobutene oligomerization. By optimizing the sensitivity of the tower's operating conditions, we obtained the optimal operational parameters of the tower. Under optimal operating conditions, the conversion rate of isobutene can reach over 80%. The mass fraction of C8 in the oligomerization product accounted for 57.44%, C12 accounted for 8.29%, and ETBE accounted for 34.23%. The reactive distillation technology can improve product selectivity. [ABSTRACT FROM AUTHOR]

As a novel study, esterification of acetic acid with methanol has been studied in a simple batch reactive distillation apparatus to produce methyl acetate as main product and water as byproduct. Novel solid catalyst named Indion 180 has been used in this esterification process. The product methyl acetate can be distilled out in two ways namely sequential and simultaneous reactive distillation. In the simple distillation batch process, first the reaction is carried out till the equilibrium with total reflux of vapours, and then distillation is carried out where the vapours are condensed and collected separately with zero reflux. In the second case, simultaneous reaction and distillation processes are carried out. During these experiments, the dynamics of bubble point temperature of the reboiler is recorded and analyzed. From the experimental results it is found that the maximum purity of methyl acetate in instantaneous distillate of reaction followed by distillation and simultaneous reaction and distillation are 0.847 and 0.782, respectively, as analyzed by gas chromatography. From these studies it is found that a batch distillation apparatus itself can be used in certain way to produce the desired product for the case of methyl acetate production by monitoring the temperature regime of the reboiler. [ABSTRACT FROM AUTHOR]

This work is a kinetic study on liquid phase esterification between acetic acid and isoamyl alcohol using Amberlyst-70 as catalyst. There are not scientific papers with fitted kinetic models for this esterification system using this catalyst. Experiments were carried out in a laboratory batch reactor at controlled temperature conditions. Molar feed ratio (between 2 and 0.5), temperature (between 353.15 K and 383.15 K) and catalyst load (between 0.5 wt% and 2.0 wt%) were the manipulated experimental conditions. Measured composition profiles were used to fit the parameters for three versions of the pseudohomogeneous model (PHM) that differ in their activity model. At the end, a PHM model based on molar fractions is recommended to explain composition changes due to the esterification reaction. Calculated values for activation energy and chemical equilibrium constant are E = 43 kJ/mol and K E = 5.22, respectively. In accordance with the Weisz-Prater criterion, intraparticle mass transport effects were appreciable in experimental kinetic tests due mainly to the particle size used (0.363 mm). In order to take into account diffusional effects, the effectiveness factor was calculated using the Maxwell-Stephan equations. Therefore, adjusted models are the intrinsic kinetics and they can be used to simulate and design reactors and reactive distillation operations. [Display omitted] • Intraparticle mass transfer effects were modelled with the Maxwell – Stefan equations. • Diffusional effects are definitively important at the scale of industrial units. • From a kinetic view it is recommended to use acetic acid in excess. • Intraparticle diffusion intensity increases with isoamyl alcohol concentration. • Kinetic model fitted can be used to design and simulate reactive distillation units. [ABSTRACT FROM AUTHOR]

In the present study, dynamic modeling, optimal operation and control of a reactive batch distillation process is illustrated based on experimental and simulation studies using methyl acetate production case study. An equilibrium stage model, incorporating non-ideal VLE and start-up region of heating, is developed based on data generated on an experimental unit by identifying five input parameters representing uncertainties. The optimal control problem is solved using genetic algorithm, considering the objective function identified on the basis of trend analysis using the developed dynamic model, to find the optimal reflux ratio, heat input to the reboiler, and mole ratio of methanol to acetic acid in the initial reaction mixture. Open-loop and closed-loop implementations clearly illustrate the improved performance with respect to the quantity of methyl acetate in the distillate product with a reasonably high conversion and product purity within reasonably short batch duration, illustrating the successful optimal control implementation experimentally. [Display omitted] • Dynamic model for methyl acetate production in RBD unit is developed from cold start. • 5 uncertainty parameters are identified based on open-loop and closed-loop operation. • Objective function is chosen by trend analysis with respect to independent variables. • Optimal input variables and set point profiles are determined by genetic algorithm. • Optimal policies are implemented through open-loop and closed-loop experimentation. [ABSTRACT FROM AUTHOR]

Biodiesel is touted to be an alternative to the fossil fuels as it is conducive to the environment. This investigation proposes a control framework to produce biodiesel in a reactive distillation column via a transesterification process. To extract quality product, the temperature profile must be maintained along the column as per the requirements. However, constant interactions among the products inside the column disturb the temperature profile and consequently the product quality. Therefore, this investigation treats the process as a single input and single output system, where in the process interactions are modelled as disturbances. A model predictive controller (MPC) is designed for the proposed system to ensure product quality. The MPC parameters must be selected appropriately to ensure optimal performance. In this regard, to tune the MPC parameters optimally, we use two evolutionary algorithms namely, the real coded genetic algorithm (RGA) and the bio-geography based optimization algorithm (BBO). The results indicate the proposed control strategy provides offset free set point tracking when compared to the multivariable control strategy employed using the MPC algorithm. Among the two evolutionary controllers used for tuning the MPC parameters, the RGA MPC controller provides a satisfactory performance. [ABSTRACT FROM AUTHOR]

Continuous reactive distillation is one of the optimized methods for synthesis of C1-C6 esters industrially. The products of the reaction are difficult to be obtained in their pure states due to the presence of azeotropes in the system. The theme of the current work is to highlight the thermodynamic nature of the each C1-C6 alcohol/ester/water system independently and investigate the possible alternatives implemented for pure separation of ester and water. This work comprehensively reports reactive distillation study for continuous synthesis of C1-C6 esters and separation strategies implemented for alcohol/ester/water system in a compiled form. Presence of the azeotropes within the system components helps us in defining the feasible separation schemes to be applied in continuous study. Current work reports a systematic thermodynamic analysis of C1-C6 alcohol/esters/water mixture with help of residue curve map to investigate the complexity of the mixture and alternate configurations/ schemes implemented in continuous reactive distillation technology for enhanced conversion and purity of product streams.

Methyl carbonate (EMC) and Diethyl carbonate (DEC), as excellent solvents for lithium-ion electrolytes, are synthesized by transesterification, and consecutive reaction seriously complicate optimization and control issues. Process synthesis, parameters optimization and advanced control are crucial points that should be addressed for this ill-conditioned and highly nonlinear system, which is the motivation and novelty of present work. With single-objective and multi-objective genetic algorithm, intensified processes for EMC and DEC production were optimized respectively with heterogeneous catalyst. And reactive dividing wall column achieved 23% and 13% total annualized cost reductions compared with reactive distillation for two target carbonates. Based on optimal steady-state solution, intelligent fuzzy logic and model predictive control of EMC and DEC production is conducted to clarify their respective strengths in intensified process with consecutive reaction. Sequential optimization for parameters of FLC was carried out with Integral of Squared Error (ISE) as objective. Finally, control performance of FLC and LPMC are compared with that under PID control, and results show that overshoot and transition time under FLC and LMPC are obviously mitigated, along with evident reduction in ISE. [Display omitted] • Process intensification realized for high-purity EMC and DEC production by embedding heterogeneous RD and RDWC. • Optimization carried out with effective single or multi objective genetic algorithm. • Intelligent fuzzy logic control and model predictive control developed for series intensified processes. • FLC and MPC shows superiority for controlling ill-conditioned system with high nonlinearity. [ABSTRACT FROM AUTHOR]

Reactive Dividing Wall Column (RDWC) modelling has attracted significant attention in recent years because simulations of processes containing such columns have demonstrated the potential for significant savings in energy and capital cost. Most modelling of these columns involves decomposing RDWCs into a thermodynamically equivalent flowsheet of reactive and non-reactive column sections in a sequential modular process simulation package. Such simulations of (R)DWCs can be time consuming to create and difficult to converge. It has been suggested that equation-oriented solvers can have superior numerical performance. Here, we use a CAPE-OPEN compliant equation-based parallel column model (PCM) that enables the rapid modelling of an RDWC as a single self-contained unit. Some conventionally modelled RDWCs from the literature are reproduced with the PCM to demonstrate its validity and excellent numerical performance. The ease and rapidity with which different RDWC configurations can be created is a significant advantage of our PCM. [Display omitted] • We describe an equation-oriented rate-based parallel column model for reactive distillation in Dividing Wall Columns. • The model can simulate DWCs of arbitrary configuration. • Model is easy to set up and rapid in execution. • Model is in excellent agreement with results of prior work. [ABSTRACT FROM AUTHOR]