Catalytic Distillation Process Research Articles

Feasibility Analysis for the Direct Hydration of 1-Octene in a Catalytic Distillation Process Using Residual Curve Maps

The very useful organic solvent 2-octanol is widely employed in the industry, and the direct hydration of olefins is an important method for its production. However, a slow transfer rate during a reaction due to the poor mutual solubility of the reactants is a problem; a cosolvent can be used to solve it. In this study, the feasibility of using the direct hydration of 1-octene via a catalytic distillation process using 1,4-dioxane as a cosolvent was investigated. First, the COSMOtherm program was used to identify and screen many typical cosolvents. Subsequently, the kinetics of the direct hydration reaction of 1-octene using 1,4-dioxane as a cosolvent and an HZSM-5 molecular sieve as the catalyst were determined experimentally. Finally, kinetic and thermodynamic models were utilized to create non-reactive and reactive residual curve maps to assess the feasibility of proceeding with the reaction. Applying a suitable Damköhler number (Da) value and the residual curve changes demonstrated that proceeding with the process was reasonable and feasible. For 0 < Da < 0.03, the reaction kinetics drove the process and 2-octanol was produced via a reaction distillation column procedure. Lastly, two conceptual design processes for the synthesis process of 2-octanol catalytic distillation were proposed and the related analysis carried out.

Investigation on catalytic distillation for ethyl acetate production with different catalytic packing structures

Here, the performances of tea-bag catalytic packing (TBP) and supported catalytic packing (SCP) in the reaction distillation of ethyl acetate were designed and compared. There are significant differences in the distribution of efficiency factor and reaction rate between them. The results can provide a theoretical reference for the design of reactive distillation. The catalytic packing is the core component of the catalytic distillation, and how the catalyst exists in the packing has significant influence on the process. To investigate the effect of catalyst packings on the catalytic distillation process, the classical ethyl acetate reactive distillation system was utilized, and a supported catalytic packing (SCP) was prepared in comparison with the conventional tea-bag catalytic packing (TBP). Laboratory scale experiments showed that the ethyl acetate conversion of the SCP was superior to the TBP at a low catalyst loading. The effects of reaction kinetics, mass transfer performance and actual catalytic efficiency of the packings on this process were regarded as reasons and studied by combining the experiments and numerical simulation. Results suggested that the relatively immediate “ in-situ separation” caused by the rapid reaction kinetics and better mass transfer performance of SCP may be a main reason for the difference of the conversion.

Experimental investigations of the production of methyl acetate in batch catalytic distillation process in the presence of Indion 180

Experimental investigations of the production of methyl acetate in batch catalytic distillation process in the presence of Indion 180

A multi-scale and multi-objective optimization strategy for catalytic distillation process

This work aims to establishing a multi-scale and multi-objective optimization strategy for the catalytic distillation process. Firstly, the catalyst layer efficiency factor correlation that embraces the influence of the catalyst layer structure was obtained and then coupled with the process simulation to establish a multi-scale model for the catalytic distillation process. On this basis, genetic algorithm was employed to realize the multi-objective optimization. The hydrolysis process of methyl acetate in the reactive dividing wall column was investigated. The equipment parameters and operational conditions of the catalytic distillation column, and the structure parameters of the catalyst layer are optimized simultaneously. The results indicated that the minima of the total annual cost, the gas emission cost and the exergy loss decrease by 19.26%, 23.11% and 67.27%, respectively, by comparing with the counterparts obtained from the single-factor sensitivity analysis. Furthermore, the catalyst cost decreases by 30.88% per year.

Integration of catalytic wet peroxidation and membrane distillation processes for olive mill wastewater treatment and water recovery

The degradation of organic matter present in olive mill wastewater (OMW) and the recovery of water were studied by the integration of catalytic wet peroxidation (CWPO) and direct contact membrane distillation (DCMD) for the first time. The oxidation step was performed in a fixed–bed reactor (FBR) working in continuous mode (pH0 = 4.0 ± 0.2, 60 °C, Q = 0.75 mL/min, [H2O2]/[COD]feed = 2.3 ± 0.1 gH2O2/gO2). Samples of OMW diluted by 5–and 7.5–fold were used (OMW–5× and OMW–7.5×, respectively), corresponding to inlet chemical oxygen demand (COD) values of 3562 ± 68 and 2335 ± 54 mg/L, total phenolic content (TPh)of177 ± 17 and 143 ± 7 mgGAeq/L, and total organic carbon (TOC) of 1258 ± 63 and 842 ± 45 mg/L, respectively. The FBR was loaded with 2.0 g of a Fe–activated carbon derived–catalyst, prepared by using olive stones as the precursor, in line with a circular economy model approach. The catalyst was selected based on the activity and stability towards polyphenolic synthetic solutions shown in previous works of the team, while actual OMW samples were used in this work. CWPO–treated samples of OMW allowed the operation of the DCMD unit at higher fluxes than with the analogous untreated ones, also showing higher rejections of organic matter from the feed solution upon DCMD, highlighting the beneficial effect of this novel configuration. Using a pre-treated sample of OMW–7.5× as feed solution (Q = 100 mL/min, Tpermeate≈18 °C, Tfeed≈66 °C), the produced permeate water stream presented several parameters well–below the legislated thresholds required for direct discharge for crops irrigation, including total suspended solids (TSS < 10 mg/L), TPh (<0.01 mgGAeq/L), biochemical oxygen demand (BOD5 < 40 mg/L), and dissolved Fe (<0.06 mg/L). Moreover, the resulting concentrated OMW–retentate streams could be recirculated to the FBR and maintain the same removal efficiencies obtained previously, despite the increased initial organic loadings of the retentate after DCMD.

Integration of Catalytic Wet Peroxidation and Membrane Distillation Processes for Olive Mill Wastewater Treatment and Water Recovery

Integration of Catalytic Wet Peroxidation and Membrane Distillation Processes for Olive Mill Wastewater Treatment and Water Recovery

Reactive separation processes applied to biodiesel production from residual oils and fats: Design, optimization and techno-economic assessment of routes using solid catalysts

Three solid acid-catalyzed (SAC) processes for biodiesel production from residual oil and fats (ROFs) with HWSi/Al2O3 as catalyst were designed and optimized using Aspen Plus: simultaneous esterification, transesterification, and methanol separation based on catalytic distillation (CD) (process A) and catalytic absorption (CA) (process B), where CA has not yet been investigated in these conditions; and hydro-esterification industrial process using CD (process C1). For the first time, processes A, B and C based on SAC route were optimized and compared regarding to techno-economic and environmental aspects. Processes A and B were the most economically and eco-friendly options. Compared to process B, process A was the best option due to simpler flowsheet. Process A2 presented 25.6, 60.1, 4.6, 8.6, 52.6 and 62.8% lower capital, utilities (Cutil), operation, total annualized (TAC), waste treatment (Cwaste) and CO2 emission costs than process C1. A global optimization developed for process A saved 430 k$/year on TAC. After a heat integration, process B presented 4.9 and 10.8% lower Cutil and Cwaste than process A. Process A was also designed for FFA levels of 5–25 wt%, where the biodiesel break-even price remained competitive (0.48–0.75 $/kg) with diesel price.

Efficient Synthesis of Isobutylene Dimerization by Catalytic Distillation with Advanced Heat-Integrated Technology

For the purpose of resolving issues of high production costs due to targeting intermediate products from tandem reaction systems in the isobutylene (IB) dimerization process with tert-butanol as a polymerization inhibitor, a potentially sustainable catalytic distillation (CD) process is proposed as the base case for efficient continuous diisobutylene production in this paper. This study covers the extensive design of the novel CD process with 99 wt % diisobutylene and 90 wt % oligomers as the final products, using a simulation-based optimization framework on the simulator Aspen Plus with a FORTRAN subroutine of Langmuir–Hinshelwood model for kinetics. Furthermore, the advanced heat-integrated manufacturing process by exploiting catalytic dividing wall distillation and double-effect catalytic distillation with/without vapor-recompressed heat pump (DECD-VRHP) technologies achieves a total reduction in energy and cost, compared to the base case with rigorous optimal CD. The results showed that the DECD-VRHP scheme performs better with the largest total annual cost saving of about 34% among the heat-integrated schemes compared with the CD process. Overall results demonstrate that the DECD-VRHP technology is a promising approach for the synthesis of IB dimerization.

Toward sustainable and eco-efficient novel catalytic distillation process for production of solketal using seepage catalytic packing internal

The initial aim of this paper is to dramatically improve the post-treatment stage of biodiesel production, which converts problematic glycerol to solketal (SK), by introduction of an eco-efficient integrated reactive and dividing wall distillation process. To overcome the chemical equilibrium limitations and the long post-treatment process with the high energy consumption and waste water emission, this study provides the potentially, sustainable and novel reactive distillation (RD) process for cleanly catalytic synthesis of SK, taking into account costs and environmental impact. The ketalization kinetics experiments were carried out to provide a basis for subsequent experiments and simulations. A reliable model was established for further RD technological design and validated by the pilot-scale experiments. Through sensitivity analysis, the effects of multiplex parameters in RD process were determined. The advanced intensification of SK production by reactive dividing wall column (RDWC) achieves reduction in energy, total annual cost (TAC) and CO2 emissions of 13.9 %, 18.2 % and 16.4 % (as oil resources), respectively, compared to the optimal SK production by RD process. This proposed technology is also compared with the conventional industrial route of ketalization with 18.7 % energy saving.

A multi-scale approach to optimize vapor-liquid mass transfer layer in structured catalytic packing

In order to implement the multi-scale model to optimize the structure of vapor-liquid mass transfer layer, vapor and liquid mass transfer coefficients that embrace the effects of structure parameters of mass transfer layer should be obtained in advance. In the study, the influences of four structure parameters on mass transfer performance were studied by the tracer method. Moreover, the corresponding mass transfer coefficients were correlated. By comparing with the experimental data of different types of structured catalytic packings, it has been found that the correlations exhibit good universality. Furthermore, the correlations were applied to the non-equilibrium model for the hydrolysis of methyl acetate (MA), so as to investigate the influences of four structure parameters on catalytic distillation process. The results indicated that wavy height and the area ratio of mass transfer layer to catalyst layer have more significant influences on the conversion of MA than inclined angle and base length.

Rigorous Dynamic Simulation of Cryogenic Distillation of Hydrogen Isotopologues in the Fuel Cycle of a Thermonuclear Reactor Based on UV Flash

Operation of the fuel cycle of a thermonuclear fusion reactor naturally leads to accumulation of surplus protium, but in some cases it can also lead to accumulation of surplus deuterium. Both surplus protium and deuterium have to be separated, detritiated, and discharged to the environment, normally passing a final detritiation stage based on either the liquid phase catalytic exchange or water distillation process. The concept of a multicolumn cryogenic distillation (CD) system capable of discharging a time-varying surplus of deuterium is presented in this paper. A model of a CD column based on a UV (internal energy U – volume V) flash formulation and equation of state (EOS) thermodynamic model for hydrogen isotopologue mixtures is also presented at the principal step to a comprehensive model of the isotope separation system. Although fundamental for constant volume systems, the UV formulation of the thermodynamic state has not been widely used in transient simulations; in particular, for distillation dynamics modeling, other approaches are much more common. At the same time, in helium cryogenics the UV formulation has gained wide usage in large-scale dynamic simulations. It is known from the literature that a UV formulation of the distillation problem is very challenging for a numerically stable implementation. To cope with this situation, we present our findings on the sources of numerical instabilities and approaches.

Batch Reactive Distillation in Bromodifluoroacetic Acid Synthesis Technology

A catalytic distillation process reacting in a column bottom was experimentally studied for the transesterification of methyl and ethyl esters of bromodifluoroacetic acid with trifluoroacetic acid. Sulfuric acid was used as a catalyst. Experiments were performed at different column bottom heat duties. As a result of the experiments, we had bromodifluoroacetic acid with a purity above 97.0 mol % at a product yield of 87.4%.

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.

Synthesis of n-Amyl Acetate in a Pilot Plant Catalytic Distillation Column with Seepage Catalytic Packing Internal

The n-amyl acetate synthesis from the esterification reaction of acetic acid and n-amyl alcohol in a pilot plant catalytic distillation column with a decanter was evaluated. A novel catalytic packing, seepage catalytic packing internal (SCPI), is applied in this study. Catalytic distillation experiments using different feed molar ratios and feed modes at different column pressures were performed to validate an equilibrium stage model developed to investigate the influence of operation parameters on the performance of the catalytic distillation process. The results from experimental runs and simulations clearly indicate that it is important to the performance of catalytic distillation process to adjust the composition and temperature profiles along the reaction zone. The studies also showed that the integration of a reactive distillation column with a decanter is considered a potential candidate to produce amyl acetate. With proper operation parameters (operating pressure of 20–22 kPa and mixed feeding mod...

Optimization of process-specific catalytic packing in catalytic distillation process: A multi-scale strategy

A novel two-way coupling multi-scale model was proposed to investigate the catalytic distillation process. In the model, a microscopic model that focuses on the reactive performance of structure catalytic packing was used to calculate actual rate for catalytic distillation process, which is the basic parameter for process simulation. Furthermore, the traditional process simulation was used to provide proper boundary conditions for microscopic model. In order to validate the multi-scale model, heterogeneously catalyzed hydrolysis of methyl acetate was employed asa test system. The simulated final conversions of methyl acetate and catalyst layer efficiency factors were in good agreement with experimental results. The results indicated that as the equivalent diameter of catalyst layer decreases from 25.4mm to 8.1mm, the catalyst layer efficiency factor rises to 200% approximately. This study could provide a theoretical guide for the optimization of catalytic packing structure.

Simulation of Tert-Butyl Alcohol Forming Process by Slurry Catalytic Distillation with Custom Kinetic Program

Producing tert-butyl alcohol (TBA) by slurry catalytic distillation is a green new technology. In order to provide reference data for this production process, this paper applied advanced simulation software Aspen to simulate and optimize the slurry catalytic distillation process of producing TBA. And the kinetics equation of isobutylene hydration which is catalyzed by cation exchange resin in continuous stirred tank reactor (CSTR) is used to display the reaction process. Appropriate theoretical plate number of rectifying section, reaction section and stripping section, reflux ratio and liquid hold-up are obtained by the analog computation. Under this process condition, the conversion rate of isobutylene is 82.53%; the mole fraction of TBA in the bottom discharging is 82.5%.

Optimal design and plantwide control of novel processes for di‐n‐pentyl ether production

AbstractBACKGROUNDDi‐n‐pentyl ether (DNPE) is a good candidate for diesel fuel formulations due to its blending cetane number, good cold flow properties and effectiveness in reducing diesel exhaust emissions, particulates and smokes. However, novel processes are required in order to drive the production costs down and to increase the efficiency at industrial scale.RESULTSThe dehydration of 1‐pentanol to yield DNPE is catalyzed by thermally stable resins, such as Amberlyst 70 which has high activity and selectivity at temperatures up to 190 °C. Two process options are proposed for a plant capacity of 26.5 ktpy: a reaction–separation–recycle (R–S–R) system based on an adiabatic tubular reactor and a catalytic distillation process. Both processes were optimized in terms of total annual costs (481 and 523 k$ year−1), leading to specific energy requirements of 225 and 256 kWh ton−1 DNPE, respectively. The controllability was assessed by dynamic simulation performed in Aspen Dynamics.CONCLUSIONCompared with the membrane reactor reported earlier, the new DNPE process alternatives (i.e. conventional reaction–separation–recycle system and catalytic distillation) are better process candidates, requiring simpler units leading to much smaller investment costs, while also having good controllability. © 2015 Society of Chemical Industry

Sensitivity and economic analysis of a catalytic distillation process for alkylation desulfurization of fluid catalytic cracking (FCC) gasoline

ABSTRACTBACKGROUNDThe issues of gasoline desulfurization are becoming more important because the regulated sulfur limits are being set lower and lower. Among the new desulfurization technologies, the olefin alkylation of thiophenic sulfur (OATS) process is more attractive than hydrodesulfurization because of its mild operating conditions and low loss of octane number. In this work, a sensitivity analysis and an economic analysis of a catalytic distillation process for alkylation desulfurization of fluid catalytic cracking (FCC) gasoline are presented. The objective is to evaluate the effects of various design and operating parameters on the OATS process by using a realistic FCC gasoline fraction.RESULTSA sensitivity analysis performed for operating pressure, reflux ratio, bottom flow rate, feed conditions, number of separate stages, number of reactive stages, catalyst weight, feed location, reactive zone position, and an economic analysis based on total annual costs (TAC) for these variables were studied.CONCLUSIONThe results show the qualitative environmental and economic effect of several design variables and operating conditions on the OATS process and provide a direction to the further design. In addition, more attention should be paid to feed flow rate control. © 2014 Society of Chemical Industry

Catalytic cyclic distillation – A novel process intensification approach in reactive separations

Cyclic distillation uses a periodic operation mode that leads to key benefits, such as increased column throughput, lower energy requirements and much higher separation performance. By integrating chemical reactions with cyclic distillation, a novel process intensification approach is possible – catalytic cyclic distillation – which outperforms classic reactive distillation.This paper is the first to describe the catalytic cyclic distillation process and to develop a rigorous mathematical model. By means of a case study involving a simple reaction system, the model is used to demonstrate the key benefits of this operation mode. In addition, the synthesis of dimethyl ether by catalytic cyclic distillation is considered, for which a design algorithm is suggested. Investigation of the column behavior reveals the coexistence of two periodic states, one of them being unstable.

A method for modeling a catalytic distillation process based on seepage catalytic packing internal

A method for the modeling of a seepage catalytic packing internal (SCPI) in a catalytic distillation column was developed and applied to the simulation of a catalytic distillation (CD) process. Based on the structure of the internal, rigorous mathematical models consisting of differential algebraic equations were developed to predict the temperature and composition profiles in the CD column. Based on the gPROMS platform, the gPROMS language was used to compile three modules, one for the reaction and the other two modules for hydrodynamic calculations and heat and mass transport calculations. In addition, a graphical user interface (GUI) design and the corresponding port design were implemented for each unit module to clearly represent the flow-sheet of the catalytic distillation process. According to the characteristics of the model, a new approach was proposed to avoid convergence difficulties and to improve the stability of the calculations. This approach was demonstrated to be an efficient method, which can reduce the simulation time and still accurately predict the results. Mathematical models and corresponding programs of reaction, separation, and the flow-sheet of CD process were validated. The simulated results were in good agreement with the experimental results, indicating that the simulation methods established in this paper are feasible. Furthermore, the gPROMS is a reliable and suitable technique for studying the catalytic distillation process of SCPI.