Catalytic Reactive Distillation Research Articles

Kinetic insights into energy-saving and low-carbon reactive distillation processes for the transesterification to dimethyl carbonate

Kinetic insights into energy-saving and low-carbon reactive distillation processes for the transesterification to dimethyl carbonate

Aspen Plus simulation and optimization of methyl acetate synthesis by catalytic reactive distillation

Aspen Plus simulation and optimization of methyl acetate synthesis by catalytic reactive distillation

Experimental studies of a continuous catalytic distillation column from startup to steady state for the production of methyl acetate

Abstract 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.

Process intensification in bio-jet fuel production: Design and control of a catalytic reactive distillation column for oligomerization

Process intensification in bio-jet fuel production: Design and control of a catalytic reactive distillation column for oligomerization

Simulation of a Steady‐State Continuous Catalytic Reactive Distillation Column by Using a Multiscale Capillary Model

AbstractA continuous packed‐bed catalytic reactive distillation column used to study the esterification of acetic acid with methanol to synthesize methyl acetate was modeled as a capillary monolith. The solid catalyst used for this study was Indion 180 ion‐exchange resin. The catalyst was immobilized in the column by using a structured packing equivalent to Katapak‐S. Experiments were performed under different operating conditions. To validate the experimental results, a capillary model was developed for the catalytic reactive distillation by combining a model based on evaporation rate with the pore diffusion model for the reaction kinetics at the catalyst‐particle scale. The model predictions for composition and temperature profiles along the length of the column were compared with the experimental data and found to be in good agreement.

Experimental and simulation studies of a continuous reactive distillation for an esterification process

Abstract Esterification of acetic acid and methanol to produce methyl acetate and water has been studied in a continuous packed bed catalytic reactive distillation column. Indion 180, an ion-exchange resin solid catalyst has loaded in an equivalent Katapak-S into the reactive section of the column. The experiments were conducted under different operating conditions of reboiler temperature, total feed flow rate of the reactants, methanol to acetic acid mole ratio, feed location of acetic acid and methanol with respect to reactive section, reflux ratio and catalyst amount to investigate the composition of distillate and reboiler respectively. The maximum methyl acetate composition and acetic acid conversion is obtained at reboiler temperature of 80 °C, reflux ratio of 2, total feed flow rate of 16.3 g/min, catalyst loading of 60 g and mole ratio of methanol to acetic acid is 1. From the experimental investigations, it is found that the composition of the methyl acetate in the distillate is 95% by mole at an optimized experimental condition. The experimental data has been compared with equilibrium and non-equilibrium model predictions and found that non-equilibrium model is able to predict the experimental data reasonably good. The calculated error from equilibrium model relative to experimental data is 4.71% and rate based model relative to experimental data is 0.61%. It is observed that the error is less in rate based model compared to equilibrium model.

Kinetics study and process simulation of reactive distillation for the synthesis of ε‐caprolactone

AbstractA novel three‐stage catalytic reactive distillation (RD) column integrated chemical reaction and distillation process for the continuous synthesis of ε‐caprolactone (ε‐CL) was proposed to overcome the disadvantages of previous batch processes. Reaction kinetics according to the two‐step indirect oxidation method was studied firstly, which was essential in reactor design and process optimization as well as lacking in the current literature. Kinetics models obtained by data fitting were tested by residual distribution and model statistics. And then, according to the thermodynamic characteristics and reaction kinetics of this process, a steady‐state simulation of RD column was carried out with the process simulator Aspen Plus. The influence of operation parameters was investigated on process performance. Under the optimal operating conditions, the conversion of cyclohexanone was 97%, and the mass fraction of ε‐CL in the bottom products was 62.31%. The simulation showed that RD column worked with excellent results in respect to conversion and product purity because of integrating the processes of chemical reaction and distillation.

A catalytic reactive distillation approach to high density polyethylene pyrolysis – Part 2 – Middle olefin production

A catalytic reactive distillation reactor, previously described, was improved to increase the production of middle and heavy hydrocarbons, to be used as feedstock or fuel in the viewpoint of a Circular Economy of plastics. The thermal and catalytic pyrolysis experiments were run using high density polyethylene (HDPE) under several experimental conditions, with a 1 % (w/w) of HZSM-5 for catalytic pyrolysis. Three different temperatures were tested in each case and the influence of the reaction time was evaluated at 500 °C and 430 °C for thermal pyrolysis and catalytic pyrolysis, respectively. Thermal pyrolysis of HDPE produced the higher amount of solid products (80 %wt. or higher) under the form of a waxy cream-colored material (wax) for all the experimental sets. For catalytic pyrolysis, the major product fraction was always liquid. The analysis of the liquid products showed that, for both thermal and catalytic pyrolysis, the products obtained were within the range of C5 to C11, with a higher yield on C8 and C9 in the case of thermal pyrolysis and on C6 and C7 for catalytic pyrolysis. The aim of this study was the development of an integrated reactor/separation system to increase the middle olefin production. It is possible with this reactor design to direct the pyrolysis of HDPE to the production of middle olefins that can be reused in the petrochemistry industry, as chemical feedstock, including in the production of new plastics.

Selective Synthesis of Ethyl Methyl Carbonate via Catalytic Reactive Distillation over Heterogeneous MgO/HZSM‐5

AbstractEthyl methyl carbonate is selective synthesized from dimethyl carbonate and ethanol via catalytic reactive distillation ( RD) over heterogeneous MgO/HZSM‐5. It is shown that 2.3%MgO/HZSM‐5 catalyst has high catalytic activity with 99.4% conversion of ethanol ( EtOH) and 98.1% selectivity to EMC, in a RD column. The prepared catalysts is characterized by XRD, SEM, N2 adsorption‐desorption CO2‐TPD and NH3‐TPD. The high performance of this catalyst is attributed to high basicity. According to the results of CO2‐TPD, this catalyst total basicity is 1.72 mmol/g. In order to optimize the catalytic reaction, the reaction conditions, such as amount of catalyst, reflux ratio and EtOH LHSV were studied.

A catalytic reactive distillation approach to high density polyethylene pyrolysis – Part 1 – Light olefin production

Abstract An integrated reactor/separation semi-batch catalytic pyrolysis reactor system, based on a distillation approach, was developed to produce gaseous hydrocarbons, to be used as feedstock or fuel in the perspective of a Circular Economy approach. This work intends to be a proof of concept and to test the operating conditions and performance of the reactor to control the molecular weight of the products. For that purpose, thermal and catalytic pyrolysis experiments were run using high density polyethylene (HDPE) under several experimental conditions. Different temperatures were used (400, 450 and 500 °C) for both thermal and catalytic pyrolysis, with 1% (w/w) of HZSM-5. The influence of the temperature of the coolant at the outlet of the reactor was also investigated for the catalytic degradation of the HDPE at 450 °C, providing a way to control the average molecular weight of the recovered products, which increased with increasing coolant temperature. The focus of the study was to develop an integrated reactor/separation system where only the lighter compounds produced could leave the reactor and thus direct the production to chemical feedstock to be reused in petrochemistry, including in the production of new plastics. The analysis of the volatile products indicated that, for both thermal and catalytic pyrolysis, the products obtained were within the range of C2 to C8. Higher amounts of C3 to C5 were formed, with a particular emphasis on olefins, with very high yields in the case of catalytic pyrolysis. The activity of the catalysts after use was also checked through the ARDT index (Ability to Reduce the Decomposition Temperature), with values for this index above 50% which indicate a good possibility for reuse of the catalyst.

Techno-economic modeling and optimization of catalytic reactive distillation for the esterification reactions in bio-oil upgradation

Abstract Equilibrium reactive distillation (RD) process simulation and economic evaluation were carried out for the esterification of complex mixtures of several fatty acids and water (representative of crude bio-oils) with n-butanol using Aspen PLUS process simulator and economic analyzer. Complete design and optimization were carried out using evolutionary techniques from simplest system to the most rigorous one with introduction of intermittent progressive complexity. Prior to distillation design, esterification reaction kinetics and binary/ternary interactions were analyzed using Aspen RGibbs reactor module and Property PLUS, respectively. Simple distillation column was designed and optimized to obtain the initial trial parameters to be used in RD simulation. UNIQUAC is used as base property method and reaction equilibria estimated by minimization of Gibbs free energy. Near atmospheric column pressure, reflux ratio of 0.95, distillate to feed ratio of 0.505 and total 18 stages were found to be optimum based on attainable reaction conversion, ester separation, heat duties, and capital and operating costs. The effects of n-butanol:acid feeding ratio and water percent in bio-oil and their relationship were also analyzed to predict n-butanol requirement. The results of this study, including the optimized parameters, could serve as design platforms for pyrolysis bio-oil upgradation to transportation fuels.

Methylformate from CO2: an integrated process combining catalytic hydrogenation and reactive distillation

Catalyst immobilization in decane and repetitive hydrogenation of CO2 to HCOOH-amine with subsequent reactive distillation of the resulting methanolic solution.

Novel Catalytic Reactive Distillation Processes for a Sustainable Chemical Industry

Reactive distillation (RD) is a great process intensification concept taking advantage of the synergy created when combining (catalyzed) reaction and separation into a single unit, which allows the concurrent production and removal of products. This feat improves the productivity and selectivity, reduces the energy usage, eliminates the need for solvents, and leads to highly-efficient systems with improved sustainability metrics (e.g. less waste and emissions). This paper provides an overview of the key features of RD processes, with emphasis on novel catalytic/reactive distillation processes that can make a difference at large scale and pave the way for a more sustainable chemical process industry that is more profitable, safer and less polluting. These examples include the production of: acrylic and methacrylic monomers, unsaturated polyesters resins, di-alkyl ethers, fatty esters, as well as other short alkyl esters (e.g. by enzymatic reactive distillation). The main drivers for such new RD applications are: economical (large reduction of costs and energy use), environmental (lower CO2 emissions, no or reduced waste) and social (improved safety and health due to lower reactive content, reduced footprint and run away sensitivity). Hence RD technology strongly contributes to all three pillars of sustainability in the chemical process industry. Nonetheless, the potential of RD technology has not been fully tapped yet, and there is still undergoing research to improve it further by various means: e.g. ultrasound or microwave assisted RD, use of high-gravity fields (HiGee), internally heat integration, cyclic operation, or coupling RD with other operations such as membrane separations.

Biodiesel production in a reactive distillation column catalyzed by heterogeneous potassium catalyst

Biodiesel is a bio-based fuel synthesized from a renewable feedstocks, such as vegetable oils or animal fats. Conventionally, it is made through transesterificating oils where the process involves catalyst and alcohol to be reacted in batch reactor. The most common catalyst for biodiesel production is homogeneous liquid catalyst. These catalytic systems, however, are difficult on separating the final product and suffer from environmental problems because they are hazardous, caustic and hygroscopic. In order to eliminate the problems, we develop potassium loaded on activated carbon (K/AC) as heterogeneous solid catalyst. Heterogeneous solid catalyst is easily regenerated, leading to more secure, lower in cost, and more environmentally friendly. The purpose of this study is to demonstrate a process using catalytic reactive distillation column applied to biodiesel production from palm oil. Reactive distillation is the simultaneous process implementing reaction and separation process in a single column. This method presents several advantages such as increasing conversion, improving selectivity, reducing catalyst requirement, and avoidance azeotrope mixture. Reaction temperature (varied from 50 to 60 °C) and methanol-palm oil molar ratio (varied from 4:1 to 8:1) were optimized to find the highest conversion in 4 hours. The higher reaction temperature accelerated the reaction rate, resulting higher conversion of oil into methyl ester. Meanwhile, the higher methanol-palm oil molar ratio affected slightly differences in reaction conversion. Reaction temperature should be limited to the boiling point of methanol to avoid the lower reaction rate causing by vaporization. Moreover, the methanol-palm oil molar ratio was also controlled by the availability of active site in the catalyst surface. Thus, the highest conversion of triglyceride, 0.8269, was obtained at temperature of 60 °C and methanol-palm oil molar ratio of 6:1. It has proven that the continuous RD posses an enhanced performance on the biodiesel production, compared to batch reactor.

Catalytic Reactive Distillation for the Esterification Process: Experimental and Simulation

Catalytic Reactive Distillation for the Esterification Process: Experimental and Simulation

Optimization studies on a continuous catalytic reactive distillation column for methyl acetate production with response surface methodology

Abstract Esterification of acetic acid with methanol to produce methyl acetate has been studied in a continuous packed bed catalytic reactive distillation column. A novel solid catalyst Indion 180 ion exchange resin was used. The response surface methodology (RSM) technique based on central composite design (CCD) optimization method was used to design the experiments. Experiments were performed under different operating conditions of reboiler temperature, reflux ratio, total feed flow rate, methanol to acetic acid mole ratio, feed locations of acetic acid and methanol with respect to reactive zone and their effect on the conversion of acetic acid as well as on compositions of distillate and bottom products. Based on experimental data and central composite design, a regression model has been developed. The model correlates the purity of methyl acetate in the distillate and six most significant independent variables. From the statistical tests it has been established that the model truly represents the experimental data. There is a good agreement between optimum conditions for methyl acetate concentration in the distillate, predicted by model and experimental data. The comparison of the experimental results with the simulation results from equilibrium stage-wise model compared and found that there is good agreement between them.

Selective hydrogenation and separation of C3 stream by thermally coupled reactive distillation

In this paper, a novel process for C3 stream selective hydrogenation in ethylene plant is proposed. The proposed process combines the propylene catalytic reactive distillation for the hydrogenation with the column of depropanization to achieve a thermally coupled distillation column configuration. In the proposed process, the reactive distillation improves the selectivity of the hydrogenation reaction with a lower investment cost for the equipment and the thermal coupling of the distillation columns, which leads to a dividing wall column (DWC), increases energy efficiency of the system. The feasibility of the proposed process is tested by rigorous simulation employing AspenPlus™ software. Optimization on decision variables employing particle swarm optimization (PSO) algorithm is also performed based on the process simulation. The results show that, on the premise of the product yield and purity (propylene mole fraction: 99.60%), the reactive distillation process can save 2.84% total annual cost (TAC) comparing to the conventional reaction-and-distillation process, and the thermally coupled reactive distillation can save 27.88% TAC than the traditional reaction-and-distillation process.

Sulfated zirconia as a robust superacid catalyst for multiproduct fatty acid esterification

Sulfated zirconia catalysts obtained by employing chlorosulfuric acid show significantly higher activity in the esterification of fatty acids with different alcohols compared with catalysts made using sulfuric acid. The superior performance results from higher sulfur content, larger pores and stronger acid sites. These catalysts are robust and do not leach out sulfonic groups. Catalyst performance depends strongly on the sulfation reagent and the calcination conditions of the intermediate zirconium hydroxide. A series of kinetic experiments was carried out with lauric acid and various alcohols (methanol, 2-ethylhexanol, propanols and butanols). The new catalysts are ca. five times faster when using primary alcohols independent of the alcohol chain length. When using secondary and tertiary alcohols the reaction rate drops considerably. This is explained by a linear free energy relationship of substituent reactivity. The kinetic investigation shows that chlorosulfated zirconia is suitable as a multiproduct catalyst for manufacturing fatty esters, by employing a catalytic reactive distillation process.

Heat-integrated reactive distillation process for synthesis of fatty esters

Catalytic reactive distillation (RD) offers novel opportunities for manufacturing fatty acid alkyl esters involved in specialty chemicals and at a larger scale in biodiesel. The integration of reaction and separation into one RD unit, corroborated with the use of a heterogeneous catalyst, provides major benefits such as low capital investment and operating costs. This work presents a novel heat-integrated process based on reactive distillation that aims to reduce furthermore the energy requirements for biodiesel production, leading to competitive operating costs. Despite the high degree of integration, the process is well controllable using an efficient control structure proposed in this work. Rigorous simulations embedding experimental results were performed using computer aided process engineering tools, such as AspenTech Aspen Plus and Aspen Dynamics. The RD column was simulated using the rigorous RADFRAC unit with RateSep (rate-based) model, and explicitly considering three phase balances. Steady-state and dynamic simulation results are given for a plant producing 10 ktpy fatty acid methyl esters (FAME) from methanol and waste vegetable oil with high free fatty acids (FFA) content, using sulfated zirconia as green catalyst. The heat-integrated RD process eliminates all conventional catalyst related operations, efficiently uses the raw materials and the reactor volume offering complete conversion of the fatty acids and allowing significant energy savings. Remarkably, compared to previously reported RD processes, the energy requirements of this process are about 45% lower – only 108.8 kW h/ton biodiesel – while the capital investment cost remains the same as no additional equipment is required.

Catalytic reactive distillation process development for 1,1 diethoxy butane production from renewable sources

Some acetals can be produced from renewable resources (bioalcohols) and seem to be good candidates for different applications such as oxygenated diesel additives. In the present case the production of 1,1 diethoxy butane from bioethanol and butanal is presented. Butanal can be obtained from biobutanol following a partial oxidation or a dehydrogenation process. In this paper innovative process development about the synthesis of the mentioned acetal including catalytic reactive distillation experimental and simulation results will be presented and discussed. Katapak SP modules containing Amberlyst 47 resin were used as structured catalytic packings. This reactive system allowed reaching higher conversions than the equilibrium ones at the same temperatures. All the experimental data gathered allowed to tune a simulation model for the reactive distillation operation which showed a fairly good behavior in order to perform initial 1,1 diethoxy butane production process design studies.