Feasibility of reactive chromatography for the production of 2-phenyl ethyl acetate

Reactive chromatography is a novel process intensification option when the progress of a reaction is hampered by reversibility (e.g., esterification and acetalization). In this work, we study its feasibility for the production of 2-phenyl ethyl acetate (PEAct) by esterification of 2-phenyl ethyl alcohol with acetic acid using Amberlyst-15 as a catalyst/adsorbent. The reaction kinetics is investigated in a laboratory batch reactor by varying various parameters such as agitation speed, temperature, feed molar ratio, catalyst loading, and particle size, and a Langmuir Hinshelwood kinetic model is proposed. The reaction is then studied in a fixed-bed chromatographic reactor (FBCR). Non-reactive binary adsorption experiments are performed in the same setup to estimate the corresponding parameters of the Langmuir adsorption isotherm. The experimentally observed reactive breakthrough curves in FBCR reveal that RC is a promising process option for the production of PEAct. Furthermore, it is shown that the FBCR model, which uses kinetics and isotherms developed in this work, explains the reactive breakthrough curves and the regeneration performance reasonably well. The work reported here forms a base for the design of a simulated moving-bed reactor that may be used for large-scale production.     

Study on the enzymatic hydrolysis of racemic methyl ibuprofen ester

The hydrolysis of racemic methyl ibuprofen ester in the presence of lipase from Candida rugosa was investigated in shake flasks. Experiments were performed to study the effect of temperature, pH and shaking speed on the reaction rate. Different hydrophobic co‐solvents were screened for the highest reaction rate and the presence of enzyme inhibition by substrate and products was examined. A kinetic expression was then proposed to describe the reaction. Kinetic parameters were determined for the optimum operating conditions and the proposed model was verified with the experimental results. Next, this reaction was scaled up to a fed batch stirred tank reactor. Batch reactor and fed batch reactor configurations were compared for better conversions. The effects of aqueous phase hold‐up, substrate concentration and feed flow rate on the conversion of the reaction were also studied. Higher conversions were obtained in a fed batch reactor when compared with the batch reactor. In the fed batch reactor, increased conversions were observed with lower feed flowrates and high aqueous phase hold‐up. © 2001 Society of Chemical Industry     

Continuous simultaneous saccharification and fermentation of raw starch in a membrane reactor

A kinetic model for simultaneous saccharification and fermentation (SSF) of raw starch is proposed. The model includes the effect of ethanol on an active site for saccharification and the decay of a raw starch affinity site. The kinetic parameters were determined by using the experimental results of a batch saccharification and a long-term repeated-batch SSF of raw sweet potato starch. From analysis of the experimental results it is concluded that two subsites took part in ethanol inhibition, and that the inactivation of the raw starch affinity site was induced by adsorption of glucoamylase onto raw starch. The proposed kinetic model successfully predicted the progress of continuous SSF in a membrane reactor.     

Synthesis of butyl acrylate in a fixed‐bed adsorptive reactor over Amberlyst 15

The butyl acrylate synthesis from the esterification reaction of acrylic acid with 1‐butanol in a fixed‐bed adsorptive reactor packed with Amberlyst 15 ion exchange resin was evaluated. Adsorption experiments were carried out with nonreactive pairs at two temperatures (323 and 363 K). The experimental results were used to obtain multicomponent adsorption equilibrium isotherms of Langmuir type. Reactive adsorption experiments using different feed molar ratios and flow rates were performed, at 363 K, and used to validate a mathematical model developed to describe the dynamic behavior of the fixed‐bed adsorptive reactor for the butyl acrylate synthesis. Due to the simultaneous reaction and separation steps, it was possible to obtain a butyl acrylate maximum concentration 38% higher than the equilibrium concentration (for an equimolar reactants ratio solution as feed at a flow rate of 0.9 mL min^?1 and 363 K) showing that sorption‐enhanced reaction technologies are very promising for butyl acrylate synthesis. © 2014 American Institute of Chemical Engineers AIChE J, 61: 1263–1274, 2015     

Synthesis of the Biofuel Additive 1,1‐Diethoxybutane in a Fixed‐Bed Column with Amberlyst‐15 Wet

The synthesis of 1,1‐diethoxybutane (DEB) through the acetalization reaction between ethanol and butyraldehyde was studied in a fixed‐bed adsorptive reactor packed with Amberlyst‐15 wet. The miscibilities of reactants and water were evaluated and breakthrough experiments with nonreactive pairs of ethanol‐water and ethanol‐DEB were performed. The parameters of the isotherms were fitted by a Langmuir competitive model. Synthesis of the acetal was carried out with mixtures of ethanol and butyraldehyde at different molar ratios. The dynamic behavior of the fixed‐bed adsorptive reactor was described by a mathematical model developed taking into account the reaction kinetics, adsorption mechanisms, mass transfer resistances, and velocity variations.     

A periodic separating reactor for propene metathesis

Periodic product separation and regeneration of sorbent were accomplished in a novel reactor application through pressurisation, adsorption, blowdown and purge steps. The switching from sorption to reaction to regeneration was accomplished in a two-bed sorption/reaction apparatus. Models developed for the mass and momentum transfer in the catalyst bed and sorber were solved using orthogonal collocation within the method of lines. The effects of operating conditions and cycle configurations on performance were assessed. The results from dynamic experiments with propene metathesis to produce ethene and 2-butene in a fixed-bed catalytic reactor were in agreement with model predictions, demonstrating that conversion and product quality can be enhanced by periodic cycling reactors. Further, the separation of the products help reduce the downstream processing costs of exit mixtures, enabling utilisation of reactant through recycling and improved product handling at subsequent stages. The efficacy of the periodic separating reactor in terms of product purity, conversion, recovery, yield and productivity were demonstrated for obtaining ethene by propene metathesis.     

Reaction kinetics and modelling of the gold catalysed glycerol oxidation

The kinetics of the glycerol oxidation using a carbon supported gold catalyst was studied experimentally in a batch reactor at oxygen pressures up to 10 bar and at temperatures from 25 to 100 °C. The influence of the mass transfer on the reaction was estimated and confirmed with theoretical calculations. A kinetic model has been proposed on the basis of a Langmuir-Hinshelwood mechanism for the experiments carried out in the kinetic regime and the kinetic parameters (reaction rate and adsorption constants as well as activation energies) were calculated.     

Kinetics of phenol oxidation in a trickle bed reactor over active carbon catalyst

The wet air oxidation of phenol over a commercial active carbon catalyst was studied in a trickle bed reactor (TBR) in the temperature and oxygen partial pressure ranges of 120–160 °C and 0.1–0.2 MPa, respectively. The performance of the active carbon was compared in terms of phenol and COD destruction. The weight change of active carbon due to reaction was also measured. Finally, oxic phenol adsorption isotherms were assessed in batch conditions at 25, 125 and 160 °C. In order to use the conversion data obtained from the TBR for a kinetic study, special care was taken to check the kinetic control in the TBR experiments. Several kinetic models including power law or Langmuir–Hinshelwood expressions were considered to describe the catalytic oxidation of phenol over active carbon. The simple power law model with first order dependence on both phenol and oxygen concentration predicted satisfactorily the experimental data not only over the entire range of operating conditions studied, but also outside its validity range. Copyright © 2005 Society of Chemical Industry     

Synthesis and purification of anthraquinone in a multifunctional reactor

In the present paper the reaction of 2-benzoylbenzoic acid dehydration has been studied in the presence of different catalysts by using a batch reactor for screening the best catalysts and a pseudo-continuous multifunctional reactor for determining catalysts productivity, reaction yields, catalysts deactivation and regeneration on the previously selected catalysts that are acid bentonite, Y- and β-zeolites. This last reactor works also as evaporator and condenser for separating and collecting produced anthraquinone at a high level of purity, while water continuously formed evaporates in the atmosphere.

A kinetic model with vapour–liquid partition and catalyst deactivation has been used to interpret the experimental runs. The liquid reacting mixture showed strong non-ideality favouring the evaporation and collection of pure anthraquinone.     

Modeling of the enantioselective hydrogenation of 1-phenyl-1,2-propanedione over Pt/Al2O3 catalyst

A kinetic model was developed for the enantioselective hydrogenation of 1-phenyl-1,2-propanedione based on parallel racemic and enantioselective routes in the presence of cinchonidine. The Langmuir–Hinshelwood type of competitive adsorption approach was used in the model, which was combined with a batch reactor model. The proposed model could sufficiently describe the observed kinetic results.     

吸附反应器的动态特性—非瞬时竞争吸附的影响

针对可逆催化反应Ａ－Ｂ＋Ｃ、各组分非瞬时Ｌａｎｇｍｕｉｒ吸附的情况，研究了固定床吸附反应器的动态特性，着重分析多组分非时竞争吸附的影响。对反应物阶跃输入时，吸附反应器的出口浓度响应进行了模拟分析，模拟结果预示，在一定的参数条件下，动态操作的吸附反应器有较高的反应转化率、高的产物和反应物分离度、而且产物Ｂ和Ｃ之间也能同时得到高度分离。另外，给出了Ｂ和Ｃ分离的条件及定性评价其分离程度的判据。     

Novel batch reactor design for the adsorption of arsenate on chitosan

BACKGROUND: The sorption of arsenate, a poison of acute toxicity found in natural waters, onto chitosan, a biosorbent derived from waste seafood shells has been studied. A batch adsorber design model was developed to determine how much chitosan adsorbent is required to reduce the arsenate concentration in solutions to the WHO standard of 10 µg L^?1. RESULTS: A series of batch kinetic experiments has been carried out at different initial pH values. The initial arsenate sorption appears to be completed after 30 min, however, a steady reversible reaction takes place resulting in the desorption of arsenate over 48 h. These phenomena in the batch kinetic data have been correlated simultaneously using the newly developed pseudo‐first order reversible model. Two batch reactor design models have been developed and compared. The first model is a conventional approach based on the equilibrium isotherm capacity equation. A second batch adsorption reactor design is based on the principle of contacting time required, t_max, for the chitosan to achieve its maximum adsorption capacity, q_max. The practical outcome from the second batch adsorber model results in a saving in adsorbent mass per batch of approximately 39.4%, 96.2% and 92.3% chitosan adsorbent at pH conditions of 3.5, 4.0 and 5.0, respectively. CONCLUSION: The adsorbent cost and handling costs are reduced in the second batch adsorber model. There is also a significant savings in the batch turnaround time required in the batch adsorber design when the design is based on the maximum adsorption capacity rather than the equilibrium adsorption capacity. Copyright © 2010 Society of Chemical Industry     

2-氧代-4-苯基丁酸乙酯不对称加氢滴流床反应器模型

研究了滴流床反应器中2-氧代-4-苯基丁酸乙酯在10,11-二氢辛可尼定修饰的Pt/A l2O3作用下不对称催化加氢反应特征,实验在4个不同催化床层中进行。考虑催化剂部分润湿和静、动持液量,结合复杂的传质和反应过程,建立了不对称催化加氢滴流床反应器模型。在本征动力学研究的基础上,用模型模拟了滴流床中反应物和产物沿反应器轴向的浓度分布,并对不同操作条件下不对称加氢反应的转化率和光学收率进行了预测,与实验数据比较一致,表明此反应器模型对非均相不对称催化反应的工程化有重要的指导意义。     

Modeling and simulation of simulated countercurrent moving bed chromatographic reactor for oxidative coupling of methane

Oxidative coupling of methane (OCM) is a reaction of industrial importance but per pass equilibrium conversion and product yield in a single reaction column is severely low. The simulated countercurrent moving bed chromatographic reactor (SCMCR) has been reported to significantly improve the methane conversion and C₂-product yield. This paper addresses the mathematical modeling of a five section SCMCR for OCM, which is particularly important for understanding the operation of this SCMCR system. In order to obtain the various process parameters, a realistic and rigorous kinetics was adopted in reactors for OCM and subsequently a kinetic model was developed which can best describe the associated kinetics of OCM in SCMCR. Adsorption isotherm parameters were then derived based on the experimental breakthrough curves acquired using single adsorption column. The proposed mathematical model demonstrated extremely good predictions of the experimental results. Finally, effects of operating parameters, such as switching time, methane/oxygen feed ratio, raffinate flow rate, eluent flow rate, etc., on the behavior of the SCMCR were studied systematically.     

Model study of the direct causticization reaction between sodium trititanate and sodium carbonate

The solid state reaction between sodium tri‐titanate and sodium carbonate, forming mainly sodium pentatitanate, was investigated. Experiments were carried out in a micro‐differential reactor made of quartz glass at various temperatures between 800°C and 880°C and in a pilot fluidized bed reactor operated in a semi‐batch mode. In the former reactor, basic kinetic data was obtained by measuring the release of carbon dioxide. Different kinetic models were considered to describe the conversion, such as the Valensi‐Carter model for diffusion controlled reaction rates and the phase‐boundary model for first‐order reaction kinetics. Furthermore, a model that included both diffusion in the solid material and the chemical kinetics was derived. This model described the experimental data obtained in the micro‐differential reactor very well. However, for the fluidized bed experiments, these different kinetic models did not accurately describe the experimental data. Therefore, an improved model was developed, which also took into account the time taken for the reactants to achieve physical contact. This model gave good agreement with the experimental data.     

Analysis of a discontinuously operated chromatographic reactor

The principle of a discontinuously operated chromatographic reactor was studied experimentally and theoretically. The heterogeneously catalysed hydrolysis of methyl formate was chosen as a model reaction. An acidic ion exchange resin was used as catalyst and adsorbent. The relevant adsorption equilibrium constants were available from a previous study. In this work the reaction rates were quantified on the basis of batch reactor experiments. Subsequently, systematic experiments were carried out using a fixed bed. The influence of temperature, residence time, feed concentration and cycle time on the reactor performance was studied. It was attempted to analyse the observations using a simplified pseudo-homogeneous cell model. Since the model was found to be capable of describing the reactor behaviour over a wide parameter range, it was applied to perform extensive parametric calculations. Besides the achievable conversion other objective functions such as recoveries and production rates were also analysed. From the results obtained a few generally applicable rules to evaluate the potential of discontinuously operated chromatographic reactors could be derived.     

Palladium supported on filamentous active carbon as effective catalyst for liquid-phase hydrogenation of 2-butyne-1,4-diol to 2-butene-1,4-diol

Structured palladium catalysts suitable for three-phase reactions have been developed based on woven fabrics of active carbon fibres (ACF) as the catalytic supports. The Pd/ACF were tested in liquid-phase hydrogenation of 2-butyne-1,4-diol showing a selectivity towards 2-butene-1,4-diol up to 97% at conversions up to 80%. The catalyst multiple reuse with stable activity/selectivity in a batch reactor was also demonstrated. The reaction kinetics was studied and the main kinetic parameters were obtained. Assuming a Langmuir-Hinshelwood kinetics and a weak hydrogen adsorption a suitable kinetic model was developed consistent with the experimental data.     

Modeling and simulation of the sequencing batch reactor at a full‐scale municipal wastewater treatment plant

In this work, we attempted to modify the Activated Sludge Model No.3 and to simulate the performance of a full‐scale sequencing batch reactor (SBR) plant for municipal wastewater treatment. The long‐term dynamic data from the continuous operation of this SBR plant were simulated. The influent wastewater composition was characterized using batch measurements. After incorporating all the relevant processes, the sensitivity of the stoichiometric and kinetic coefficients for the model was thoroughly analyzed prior to the model calibration. The modified model was calibrated and validated with the data from both batch‐ and full‐scale experiments. Model predictions were compared with routine data in terms of chemical oxygen demand, NH₄⁺‐N and mixed liquid volatile suspended solids in the SBR, combined with batch experimental data under different conditions. The model predictions match the experimental results well, demonstrating that the model is appropriate to simulate the performance of a full‐scale wastewater treatment plant even operated under perturbation conditions. © 2009 American Institute of Chemical Engineers AIChE J, 2009     

Reactive Polymers in Mercury Removal from Electrolytic Brine

Abstract

The adsorption of mercury from concentrated aqueous solutions and chlor-alkali industry brine on the reactive polymers has been studied. The investigations were performed in the batch and column systems. The batch experiments were carried out to assess mercury ion exchange adsorption isotherms and adsorptive capacity. The effects of agitation time and pH were investigated. On the basis of dynamic experiment results, mercury concentration in the effluent obtained from the column against the flow rate of brine through the bed was deduced and the effective and total capacities were calculated. The regeneration of the spent resins was also investigated.     

Establishment and solution of eight-lump kinetic model for FCC gasoline secondary reaction using particle swarm optimization

An eight-lump kinetic model contained 21 kinetic parameters was proposed to describe the secondary reaction process of fluid catalytic cracking (FCC) gasoline. The model was solved by hybrid particle-swarm optimization (HPSO) which incorporated evolutionary strategies and the simulated annealing method into particle swarm optimization (PSO). A series of experiments were carried out in a riser reactor over an improved Y zeolite catalyst with different temperatures, catalyst to oil ratios and vapor residence times. The product distribution was obtained to estimate the 21 kinetic parameters of model; the calculated results obtained using the HPSO algorithm agreed well with the experimental results.