Continuous Reactive Distillation Column Research Articles

Feasibility Study of Reactive Distillation for the Production of Propylene Glycol Monomethyl Ether Acetate through Transesterification

This paper aims to present the feasibility of conducting the transesterification of propylene glycol ether (PM) with methyl acetate (MeAc) in a reactive distillation (RD) column to improve the reaction conversion. The essential thermodynamic and reaction kinetic data of the reaction system were measured for the feasibility study. There is only one azeotrope, MeAc–MeOH, in the reaction system, and the NRTL model could describe well the thermodynamic behavior of this system. The transesterification of PM with MeAc is an endothermic reaction with activation energy E = 55.704 kJ·mol–1. The feasibility was analyzed by residue curve maps (RCM), showing that full conversion of PM could be realized by RD with a mole ratio of MeAc–PM larger than 2.882. The intensification effect was experimentally verified in a batch RD column. Finally, some important parameters are given through the conceptual design to develop a continuous RD column for the transesterification of PM with MeAc.

Application of Tin(II) Chloride Catalyst for High FFA Jatropha Oil Esterification in Continuous Reactive Distillation Column

The application of heterogeneous solid acid catalysts in biodiesel production has become popular and gained significant attention over the last few years. It is since these types of catalysts hold the benefits in terms of easy separation from the product, reusability of the catalyst, high selectivity of the reaction. They are also considered sustainable and powerful particularly in organic synthesis. This work studied the use of tin(II) chloride as solid Lewis acid catalyst to promote the esterification reaction of high Free Fatty Acid (FFA) jatropha oil in continuous reactive distillation column. To obtain the optimum condition, the influences of reaction time, molar ratio of the reactant, and catalyst were investigated. It was revealed that the optimum condition was achieved at the molar ratio of methanol to FFA at 1:60, catalyst concentration of 5%, and reaction temperature of 60°C with the reaction conversion of 90%. This result was significantly superior to the identical reaction performed using batch reactor. The esterification of high FFA jatropha oil using reactive distillation in the presence of tin(II) chloride provided higher conversion than that of Amberlyst-15 heterogeneous catalyst and was comparable to that of homogenous sulfuric acid catalyst, which showed 30 and 94.71% conversion, respectively. The esterification reaction of high FFA jatropha oil was subsequently followed by transesterification reaction for the completion of the biodiesel production. Transesterification was carried out at 60 °C, molar ratio of methanol to oil of 1:6, NaOH catalyst of 1%, and reaction time of one hour. The jatropha biodiesel product resulted from this two steps process could satisfy the ASTM and Indonesian biodiesel standard in terms of ester content (97.79 %), density, and viscosity.

Integration of Enzymatic Catalysts in a Continuous Reactive Distillation Column: Reaction Kinetics and Process Simulation

This work presents a feasibility study for an enzymatic reaction in a continuously operated reactive distillation column. As a model reaction, the transesterification of ethyl butyrate with n-butanol in the presence of lipase CALB was considered. For use in the distillation column, lipase CALB was immobilized by entrapment in a hydrophobic silica xerogel and introduced as granulate into the catalytic packing Katapak-SP-11. The reaction kinetics was experimentally determined for different concentration and temperature ranges and described by means of the Michaelis–Menten double-substrate kinetic model in combination with the Arrhenius model. With these kinetic data, process simulations were carried out with an Aspen Custom Modeler nonequilibrium-stage model validated for a DN50 pilot-scale column. The concentration of n-butanol in the reactive section was maintained low to decrease the inhibiting effects on the enzyme. For an optimized setup and operating conditions, conversion rates of more than 90% were achieved for n-butanol and 26% for ethyl butyrate. These results clearly demonstrate that lipase CALB can be applied in a continuously operated reactive distillation column.

Synthesis Acetylation of Glycerol Using Batch Reactor and Continuous Reactive Distillation Column

Biodiesel production from vegetable oil produces glycerol as by-product with the amount of about 10 wt% of its product. This excessive amount of glycerol needs to be converted into the higher valuable product. One of the prospective glycerol’s derivatives is triacetin, a good bio-additive as anti-knocking agent. The synthesis of triacetin from glycerol and acetic acid using sulfuric acid catalyst has been performed in batch and continuous process. In this work, triacetin was synthesized using batch reactor to give 96.30% of glycerol conversion and 20.50% of triacetin selectivity. Meanwhile, the production using continuous reactive distillation resulted in glycerol conversion of 98.51% and 8.84% of triacetin selectivity.

Biodiesel Yield Assessment in Continuous-Flow Reactors Using Batch Reactor Conditions

Fatty acid methyl esters derived from renewable sources such as vegetable oils has gained importance nowadays as an alternative fuel for diesel engines. The present study is aimed to produce biodiesel from non-edible oil (Karanja oil of Indian origin) both in batch and continuous reactors. The purpose of the study is the comparison of Karanja biodiesel production with different reactor types under variable reaction characteristics. Therefore, two types of continuous reactors were used: helical tube reactor and reactive distillation (RD) column. Experiments were carried out to obtain suitable operating parameters in batch- and continuous-flow reactors. For batch reactor, suitable operating conditions obtained are: 7:1 methanol-to-oil molar ratio, 0.8% (by weight of oil) catalyst (KOH), 65°C reaction temperature, and 1-h reaction time, at which the maximum yield obtained is 96%. In continuous helical tube reactor, maximum yield of 92.6% was obtained at 6.6 mL/min of flow rate at the same operating conditions of batch reactor. In continuous RD column, maximum yield of biodiesel 96.6% was obtained at the same operating conditions except methanol-to-oil molar ratio (5:1) because of recycling of methanol into the column. The residence times in the helical tube reactor and RD column were 4 and 8 min, respectively, as compared to 1 h in the batch reactor for almost the same yield.

Pilot-scale experimental validation of unsaturated polyesters synthesis by reactive distillation

Reactive distillation (RD) is an integrated operation combining both reaction and separation, thus improving the productivity and selectivity, reducing the energy usage, eliminating the need for solvents and leading to intensified highly-efficient systems. In previous work, we performed the conceptual design and modeling of a reactive distillation process for synthesis of unsaturated polyesters. The simulation results of our previous work clearly demonstrated that reactive distillation is a promising alternative for the polyesters synthesis.This paper presents our pilot scale experimental validation work on the proposed RD process for polyester synthesis. Two configurations are investigated: (1) a RD column alone and (2) a RD column coupled with a pre-reactor. For the first configuration, we demonstrated that mostly monoesters are formed in the RD column, due to the short residence time at pilot scale. Since the combination of a RD column with pre-reactor allows sufficient residence time also at pilot scale, we demonstrated that polyesters are formed in the RD column. The extended rate-based model developed previously was used to simulate the pilot plant RD column. The model adequately predicts and describes the experimental data obtained from the pilot plant. Moreover, the product specification of the polyester produced in the continuous RD column was compared with the polyester product manufactured at industrial scale. Remarkably, it was found that the product specifications of the polyester produced in the RD column is comparable to that of the polyester produced in industry.

Transacetalization of Glycerol with Methylal by Reactive Distillation

The applicability of reactive distillation (RD) for the transacetalization of glycerol with methylal in the presence of Amberlyst-15 is studied by experiments and simulation. On the basis of the batch kinetic runs a pseudohomogeneous kinetic model is proposed. The experiments are performed on a continuous reactive distillation column and are compared with the predictions of the equilibrium stage model. Various feasible configurations of reactive distillation are identified and the experimentally validated simulator is used to investigate the effect of different design and operating parameters such as number of rectifying stages, stripping stages, feed mole ratio, reboiler duty, etc. on the performance in each case. The RD process alternatives and the conventional process of reaction followed by distillation are compared.

Process Simulation and Design of Reactive Distillation Column

This paper presents a systematic study on the homogeneously catalyzed reactive distillation (RD) process operated in both batch and continuous mode for the synthesis of ethyl acetate. In the first part, the fundamental model has been developed incorporating the reaction term within the model structure of the nonreactive distillation process. In case of batch rectifier, the process operation is simulated at the startup phase under total reflux condition for reaching the steady state. The open-loop process dynamics are also examined running the batch process at production phase under partial reflux condition.The concerned batch rectifier has the ability to provide high purity product. On the other hand, the continuous RD column exampled at the beginning of the second part produces relatively low quality product. In the present study, an attempt has been made to configure a feasible continuous column with improved product quality. In order to propose a RD setup, several simulation experiments have been performed for sensitivity analysis. An interesting phenomenon, the input multiplicity, is observed for both the batch as well as continuous column.

Recovery of Acetic Acid from Aqueous Solutions by Reactive Distillation

The recovery of acetic acid by reactive distillation through esterification with methanol in the presence of ion-exchange resin as a catalyst has been investigated in detail. A kinetic expression that is valid under the conditions that prevail in a continuous reactive distillation column has been developed. The insensitivity of reaction rate to catalyst loading under certain conditions has been addressed. The recovery as high as 80% was realized experimentally for the feed concentration of 30% (w/w) in a laboratory column. Various alternative scenarios such as effect of reboiler duty, feed flow rate, and feed composition were covered in the experiments. The equilibrium stage model for reactive distillation predicts the performance well in agreement with the experimental results. The effect of changing various design and operating parameters, over a wide range, was also studied through simulation. The model predicts close to quantitative recovery (∼100%) with a properly designed column. Some feasible alternative configurations for a complete recovery system have been suggested.

Simultaneous kinetic resolution of chiral propylene oxide and propylene glycol in a continuous reactive distillation column

Traditionally kinetic resolutions are conducted by batch processing to recover one of the desired enantiomers of the racemate, while the product formed by the resolution is discarded due to its low purity. However, chiral materials are economically valuable and simultaneously conducting the reaction and separation, using reactive distillation, allows for both a reactant enantiomer and a product enantiomer to be recovered in high enantiomeric excess and yield. A feasible design of a continuous reactive distillation column is presented which performs a simultaneous kinetic resolution of racemic propylene oxide to produce both enantiomerically-pure propylene oxide and propylene glycol.

Transesterification of methyl myristate in a continuous reactive distillation column: simulation and experiment

The transesterification of methyl myristate with isopropanol to methanol and isopropyl myristate is presented. This reactive system is suitable for reactive distillation and is used for the investigation carried out in this paper. A simulation model for the steady state and dynamic simulation of the reactive distillation processes was developed. For the validation of this model experiments were carried out. Based on dimensioning calculations, a 6 meter high reactive distillation column (0.1 m i.d.) with 22 bubble cap trays and a total liquid holdup of about 10 litres was constructed and built up. The stationary results obtained from the column show a good comparison between the simulated and the experimental concentration and temperature profiles. The experimentally determined dynamic time constants and sensitivities of the temperature profile of the column could be reproduced very well by the simulation tool developed. Untersuchung zur Methylmyristat-Synthese in einer Reaktivkolonne: Simulation und Experimente Die Umesterung von Methylmyristat mit Isopropanol zu Methanol und Isopropylmyristat wird vorgestellt. Es handelt sich dabei um eine Reaktion, die für die Reaktivrektifikation geeignet ist und die bei den hier durchgeführten Untersuchungen eingesetzt wird. Ein Simulationsmodell zur stationären und dynamischen Simulation der Reaktivrektifikation wurde entwickelt. Zur Validierung dieses Modells wurden Experimente durchgeführt. Auf der Grundlage der Dimensionierungsrechnungen wurde eine ca. 6 Meter hohe Reaktionskolonne mit 22 Glockenböden und einem flüssigen Gesamtholdup von ca. 10 Litern konstruiert. Stationär stellten sich gute Übereinstimmungen zwischen dem simulierten und dem experimentellen Temperatur- und Konzentrationsprofil ein. Auch dynamisch konnten die Zeitkonstanten und Sensitivitäten der Temperaturen in der Kolonne nach einem Sprung im Rücklauf in die Kolonne gut abgebildet werden.

Acetalization of ethylene glycol with formaldehyde using cation-exchange resins as catalysts: batch versus reactive distillation

1,3-Dioxolane was prepared from ethylene glycol and formaldehyde in the presence of a cation-exchange resin. The reaction was studied in batch mode, semi-batch reactive distillation mode and in a continuous reactive distillation column. A pseudohomogeneous model explains the batch kinetics. Higher than 98% conversion of formaldehyde was achieved in semi-batch reactive distillation. Recovery of ethylene glycol from aqueous solutions via reaction With solid paraformaldehyde in a semi-batch reactive distillation mode was also studied.

Reaction of ethanol and formaldehyde: use of versatile cation-exchange resins as catalyst in batch reactors and reactive distillation columns

Diethoxymethane was prepared in batch mode as well as in continuous Reactive Distillation Column (RDC) from ethanol and aqueous formaldehyde in the presence of a macroporous cation-exchange resin Indion-130. The batch reaction was studied for the effect of catalyst loading, mole ratio, concentration, temperature, etc. A pseudo homogeneous model was used to explain the batch kinetics and the kinetic parameters were evaluated. In the case of RDC, the effect of various parameters such as residence time, reflux ratio, mole ratio, feed concentration, feed configuration, etc. on the conversion and product purity was studied and evaluated.