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Alírio E. Rodrigues - One of the best experts on this subject based on the ideXlab platform.
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Simulated moving bed reactor for p-xylene production: Modeling, simulation, and optimization
Chemical Engineering Science, 2020Co-Authors: Jonathan C. Gonçalves, Alexandre F. P. Ferreira, Alírio E. RodriguesAbstract:Abstract A Simulated Moving Bed Reactor (SMBR), comprising a homogeneous mixture of adsorbent and catalyst, can overcome the equilibrium constraints in the production of p-xylene (PX). In this proposal, toluene and benzene were respectively considered as desorbent in the process. The arrangement of columns and optimum operating conditions such as switching time and flow rates that lead to maximum p-xylene productivity and minimum desorbent consumption were determined. Several constraints, including maximum pressure drop per bed and purity, were considered. Additionally, the operating temperature was optimized for the first time taking into account the energy consumption within the associated distillation columns; the heat integration involving the distillation columns was also discussed. Finally, toluene showed better performance than benzene as desorbent. For the best case studied, the optimized temperature was 540 K. Moreover, an increase of about 25% in the recovery of PX, compared to the conventional Simulated Moving Bed, was obtained.
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Sorption-Enhanced Reaction With Simulated Moving Bed Reactor and PermSMBR Technologies
Sorption Enhancement of Chemical Processes, 2017Co-Authors: Dânia S. M. Constantino, Rui P. V. Faria, Alírio E. RodriguesAbstract:Abstract Two of the most recent and promising multifunctional reactors, the Simulated Moving Bed Reactor and the Simulated Moving Bed Membrane Reactor, for the synthesis of oxygenated compounds, were addressed focusing on the methodology for the development and implementation of these technologies based on experimental data and suitable mathematical models. Moreover, different case studies, involving acetals and esters, using the different reactor configurations were illustrated. The two types of reactors were compared under the same operating conditions and, after that, individually optimized in order to find the optimal operating conditions for which the maximum performance is achieved. The Simulated Moving Bed Reactor proved to be a very competitive process for the synthesis that involves equilibrium-limited reactions. This technology, which combines reaction with chromatographic separation, revealed a strong ability to increase the equilibrium conversion with high productivities and reasonable desorbent consumptions by the continuous removal of water through selective adsorption. However, diluted products are obtained and subsequent units for the products purification are required. Combining the Simulated Moving Bed Reactor with water-selective membranes, a new technology was generated, the Simulated Moving Bed Membrane Reactor also designated by PermSMBR. This recent concept that comprises reaction and two different separation techniques exhibited excellent performance for acetals and esters synthesis, even improving the previous reactor productivities with significant reduction on the desorbent demand. Furthermore, its dimensions can be reduced without affecting the productivity, leading to higher savings on the desorbent consumption and lower associated desorbent recovery costs.
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Gas-phase simulated moving bed: Propane/propylene separation on 13X zeolite
Journal of Chromatography A, 2015Co-Authors: Vanessa F.d. Martins, João C. Santos, Alexandre F. P. Ferreira, Ana M. Ribeiro, M.g. Plaza, José M. Loureiro, Alírio E. RodriguesAbstract:Abstract In the last years several studies were carried out in order to separate gas mixtures by SMB technology; however, this technology has never been implemented on an industrial scale. In the present work, a gas phase SMB bench unit was built and tested for the separation of propane and propylene mixtures, using 13X zeolite extrudates as adsorbent and isobutane as desorbent. Three experiments were performed to separate propane/propylene by gas phase SMB in the bench scale unit with a 4-2-2 configuration, i.e. , open loop circuit by suppressing section IV (desorbent regeneration followed by a recycle). Consequently, all the experiments were conducted using an external supply of pure isobutane as desorbent. Parameters such as switching time, extract and raffinate stream flow rates were changed to improve the efficiency of the process. Experimental results have shown that it is feasible to separate propylene from propane by gas phase SMB at a bench scale and that this process is a potential candidate to replace the conventional technologies for the propane/propylene separation. The performance parameters obtained are very promising for future development of this technology, since propylene was obtained in the extract stream with a purity of 99.93%, a recovery of 99.51%, and a productivity of 114.08 kg C 3 H 6 h − 1 m adsorbent − 3 . Propane was obtained in the raffinate stream with a purity of 98.10%, a recovery of 99.73% and a productivity of 30.42 kg C 3 H 8 h − 1 m adsorbent − 3 . The success of the above mentioned bench scale tests is a big step for the future implementation of this technology in a larger scale.
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From molecules to processes: Molecular simulations applied to the design of simulated moving bed for ethane/ethylene separation
Canadian Journal of Chemical Engineering, 2013Co-Authors: Miguel A. Granato, Vanessa F.d. Martins, João C. Santos, Miguel Jorge, Alírio E. RodriguesAbstract:This paper presents results of a modelling study on the separation of ethane/ethylene mixture by selective adsorption on zeolite 13X in a simulated moving bed (SMB) unit. Propane and n-butane are evaluated as desorbent candidates. The study encompasses molecular simulation calculations for determination of adsorption parameters, whose results will then be used in a mathematical model for evaluating the performance of an SMB unit. This work is entirely done in silico, by using available force field parameters for the molecular simulations part and reliable mathematical models for the SMB part. Experimental data are solely used for comparison with the molecular simulation results, which are subsequently expanded to calculate adsorption properties for separating the mixtures, without further experimental work. The separation regions of an SMB unit operating with zeolite 13X for ethane/ethylene separation, using propane and n-butane as Desorbents, were obtained by simulation at 110 kPa and at four different temperatures: 298, 323, 348 and 373 K. For each desorbent, an operating point was selected, and the size of the required unit was presented for the complete separation of the two components of the mixture.
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Green Fuel Production Using the PermSMBR Technology
Industrial & Engineering Chemistry Research, 2011Co-Authors: Carla Pereira, Viviana M. T. M. Silva, Alírio E. RodriguesAbstract:The production of the green fuel acetaldehyde dibutylacetal (1,1-dibutoxyethane, DBE) was implemented by means of a new hybrid technology, the Simulated Moving Bed Membrane Reactor (PermSMBR), which consists in a Simulated Moving Bed Reactor (SMBR) integrated with membranes. The PermSMBR and SMBR processes performances were numerically evaluated and compared. The new hybrid technology proved to be a very efficient process for DBE production, leading to a productivity of 70.77 kgDBE·Lresin-1·day-1 with a desorbent consumption of 0.33 Ln-Butanol/kgDBE, which corresponds to a productivity enhancement of 31% and a desorbent consumption reduction of 88% when compared with the SMBR technology.
Phillip C. Wankat - One of the best experts on this subject based on the ideXlab platform.
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Standing wave design of a four-zone thermal SMB fractionator and concentrator (4-zone TSMB-FC) for linear systems
Adsorption, 2014Co-Authors: Nicholas Soepriatna, Nienhwa Linda Wang, Phillip C. WankatAbstract:For a dilute feed, a four-zone SMB with temperature gradient (4-zone TSMB-FC) can fractionate and simultaneously concentrate two solutes. Optimization of the operating parameters for this system, which include four zone flow rates and port switching time, is a major challenge because of the five variables. Initial choice of the variables using the triangle theory followed by a systematic search using rate model simulations is time-consuming. In this study, the SWD developed previously for isothermal systems is modified for the first time for a 4-zone TSMB-FC. The optimum operating parameters are determined with the new method. Only linear isotherm systems with significant mass transfer resistances are considered. For a dilute feed, a 4-zone SMB-FC can produce pure desorbent, in addition to extract and raffinate products with high purities. For the separation of p -xylene and toluene with silica gel in the temperature range from 0 to 80 °C, the enrichment factor in the linear region can be as high as 80 fold for an extract purity of 99.99 % and tenfold for raffinate purity of 99.8 %, while withdrawing the desorbent at a desorbent to feed flow rate ratio of 0.53 and 0.78, respectively.
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Optimized design of recycle chromatography to isolate intermediate retained solutes in ternary mixtures: Langmuir isotherm systems
Journal of Chromatography A, 2009Co-Authors: Phillip C. WankatAbstract:Abstract Batch chromatography with a recycle stream is a popular and simple technique to separate a single target component in a complex mixture with moderate operating conditions. Design of recycle chromatography depends on the retention behaviors of the mixture components. In this work, four nucleosides were considered as solutes. Feed concentration and recycle methods were optimized to isolate only the intermediate retained solute in ternary and pseudo-ternary mixtures. Two recycle methods introduced in our previous work for linear isotherms, the desorbent and feed recycle methods, were compared in terms of productivity and desorbent to feed ratio, D/F, with various feed concentrations for competitive Langmuir isotherm systems. The simulation results show that the target (intermediate retained solute) was separated with over 99.76% purity and 99.88% yield. Productivity of the feed recycle method was increased by up to 162% and D/F was decreased by up to 59% compared to the desorbent recycle method. For the separation of nucleosides, recycle chromatography was compared to eight column simulated moving bed (SMB) cascades with a recycle stream and D/F of the SMB cascades was 58% lower than D/F of recycle chromatography at the same productivity. However, recycle chromatography is much simpler.
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Comparison of Recycle Chromatography and Simulated Moving Bed for Pseudobinary Separations
Industrial & Engineering Chemistry Research, 2009Co-Authors: Phillip C. WankatAbstract:The simulated moving bed (SMB) process has been extensively used in industrial separations for binary and pseudobinary separations. The SMB has been reported to have higher productivity and requires less desorbent than batch chromatography; however, in pseudobinary separations these advantages are dependent on the difference of adsorption behaviors of the nontarget components. In this research, the performance of batch chromatography with a single recycle stream was compared to SMB processes for pseudobinary separations of ternary nucleosides, a model system with competitive Langmuir isotherms. To compare the performances of SMB and recycle batch chromatography, detailed dynamic simulations of each process were performed with optimized operating conditions. The desorbent to feed ratio, D/F, of recycle chromatography was at least 2 times smaller than that of a four-column SMB process for most retained solute separations. For one case of least retained solute separation (2′-deoxycytidine/2′-deoxythymidine/2...
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Separation of Concentrated Binary Gases by Hybrid Pressure-Swing Adsorption/Simulated-Moving Bed Processes
Industrial & Engineering Chemistry Research, 2009Co-Authors: Kyle P. Kostroski, Phillip C. WankatAbstract:Stripping-type PSA (S-PSA) is a commonly used gas separation process for purification of the light component. Rectifying-type PSA (R-PSA), although not commonly used, is a gas separation process for purifying predominately the heavy component. Because S-PSA and R-PSA each tend to favor the production of a single product, these processes are typically not used for complete binary separation. On the other hand, the gas-phase simulated-moving bed (SMB) is capable of achieving complete binary separation; however, its commercial application has been stymied by the need for carrier gas/desorbent recovery and unfavorable economics. In this work, S-PSA and R-PSA are combined with a two-zone SMB to develop S-PSA/SMB and R-PSA/SMB hybrid processes and these processes are integrated into combination-type C-PSA/SMB processes. Combining PSA and SMB eliminates the carrier gas/desorbent by taking advantage of gas expansion and by using both light and heavy purge streams. Separation of H2 and CH4 mixtures with Zeolite 5A...
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Separation of Dilute Binary Gases by Simulated-Moving Bed with Pressure-Swing Assist: SMB/PSA Processes
Industrial & Engineering Chemistry Research, 2008Co-Authors: Kyle P. Kostroski, Phillip C. WankatAbstract:Hybrid simulated-moving bed/pressure-swing adsorption (SMB/PSA) cycles are developed to achieve the relatively difficult separation of dilute enantiomeric enflurane in a nitrogen carrier gas. SMB/PSA decreases molar desorbent requirements by taking advantage of gas expansion at low pressure and the desorbent (carrier gas) present in the dilute feed. The most practical SMB/PSA configuration is a pair of two-zone SMB/PSA trains operating 180° out of phase to form a continuous (1,1)−(1,1) SMB/PSA process. With no additional nitrogen carrier gas (D/F = 0), the (1,1)−(1,1) SMB/PSA produced products having a maximum average purity of ∼86% and a maximum average recovery of ∼86%. By manipulating the recycle ratio (RR) and the bed purge ratio (BPR) at D/F = 0, either the raffinate or extract product could be produced with purity greater than or equal to 95%. To produce purer products simultaneously, pure nitrogen was added as desorbent. A maximum average purity of 99% and a maximum average recovery of 99% were att...
Nienhwa Linda Wang - One of the best experts on this subject based on the ideXlab platform.
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Standing wave design of a four-zone thermal SMB fractionator and concentrator (4-zone TSMB-FC) for linear systems
Adsorption, 2014Co-Authors: Nicholas Soepriatna, Nienhwa Linda Wang, Phillip C. WankatAbstract:For a dilute feed, a four-zone SMB with temperature gradient (4-zone TSMB-FC) can fractionate and simultaneously concentrate two solutes. Optimization of the operating parameters for this system, which include four zone flow rates and port switching time, is a major challenge because of the five variables. Initial choice of the variables using the triangle theory followed by a systematic search using rate model simulations is time-consuming. In this study, the SWD developed previously for isothermal systems is modified for the first time for a 4-zone TSMB-FC. The optimum operating parameters are determined with the new method. Only linear isotherm systems with significant mass transfer resistances are considered. For a dilute feed, a 4-zone SMB-FC can produce pure desorbent, in addition to extract and raffinate products with high purities. For the separation of p -xylene and toluene with silica gel in the temperature range from 0 to 80 °C, the enrichment factor in the linear region can be as high as 80 fold for an extract purity of 99.99 % and tenfold for raffinate purity of 99.8 %, while withdrawing the desorbent at a desorbent to feed flow rate ratio of 0.53 and 0.78, respectively.
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Optimization of productivity in solvent gradient simulated moving bed for paclitaxel purification
Process Biochemistry, 2008Co-Authors: Nienhwa Linda WangAbstract:Abstract The isocratic and solvent gradient SMBs for paclitaxel purification were optimized to maximize productivity under constraints of product purities and zone flow rate. The solvent composition in the feed and in the desorbent, zone flow rates, and switching time were optimized using non-dominated sorting genetic algorithm with elitism and jumping genes (NSGA-II-JG) and rate model simulations. The highest productivity is achieved using the highest solvent concentration in the desorbent and the lowest solvent concentration in the feed. The optimal solvent gradient SMB was found to have 11-fold of the productivity and 21% of the desorbent requirement, compared to the optimal isocratic SMB. The productivities of the optimal isocratic SMBs were limited by mass-transfer efficiency (or column efficiency). By contrast, the productivities of the optimal gradient SMBs were limited by zone flow rate constraint. The productivity of the optimal solvent gradient SMB without any zone flow rate constraint is 17-fold that of the optimal isocratic SMB. If the gradient SMB had a relatively small difference in ethanol concentration in the adsorption and desorption zones, the highest flow rate occurred in zone I, as in a conventional isocratic SMB. By contrast, if the gradient SMB had a sufficiently large solvent gradient, the highest flow rate occurred in zone III.
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standing wave design of tandem smb for linear multicomponent systems
Aiche Journal, 2002Co-Authors: Benjamin J Hritzko, Robert J Wooley, Nienhwa Linda WangAbstract:The standing-wave design was extended to achieve any desired split of mixtures containing three or more components in a single-ring and a tandem two-ring simulated moving bed (SMB). Mass-transfer effects were considered in the design for nonideal systems. The separation of a four-component mixture of glucose, xylose, acetic acid and sulfuric acid was chosen to illustrate the design method. Rate-model simulations confirmed that the standing-wave design method could guarantee high purity and high yield. If all the components in a ternary mixture need to be recovered with high purity and high yield, the easier separation should be performed in the first ring of a tandem SMB to achieve the lowest desorbent consumption and the highest product concentration. If only the intermediate component needs to be recovered in high purity, one of the impurities should be allowed to distribute between the two product ports in the first ring to achieve a lower desorbent consumption and a higher product concentration. These strategies also apply to the separation of a mixture containing more than three components.
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Standing‐wave design of tandem SMB for linear multicomponent systems
Aiche Journal, 2002Co-Authors: Benjamin J Hritzko, Robert J Wooley, Nienhwa Linda WangAbstract:The standing-wave design was extended to achieve any desired split of mixtures containing three or more components in a single-ring and a tandem two-ring simulated moving bed (SMB). Mass-transfer effects were considered in the design for nonideal systems. The separation of a four-component mixture of glucose, xylose, acetic acid and sulfuric acid was chosen to illustrate the design method. Rate-model simulations confirmed that the standing-wave design method could guarantee high purity and high yield. If all the components in a ternary mixture need to be recovered with high purity and high yield, the easier separation should be performed in the first ring of a tandem SMB to achieve the lowest desorbent consumption and the highest product concentration. If only the intermediate component needs to be recovered in high purity, one of the impurities should be allowed to distribute between the two product ports in the first ring to achieve a lower desorbent consumption and a higher product concentration. These strategies also apply to the separation of a mixture containing more than three components.
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Optimization of throughput and desorbent consumption in simulated moving-bed chromatography for paclitaxel purification.
Journal of Chromatography A, 1999Co-Authors: Dan Wu, Zidu Ma, Nienhwa Linda WangAbstract:In simulated moving-bed (SMB) applications, throughput and desorbent consumption are two key factors that control process cost. For a given adsorbent volume and product purity requirements, throughput and desorbent consumption depend on desorbent composition, column configuration, column length to diameter ratio, and adsorbent particle size. In this study, these design parameters are systematically examined for paclitaxel purification. The results show that if adsorbent particle size, column dimensions and column configuration are fixed, the higher the product purity required, the lower the throughput. If product purity and yield are fixed, the larger the solute migration speed ratio, the higher the throughput, and the lower the desorbent consumption. If total bed volume and product purities are fixed, the longer the separation zones, the higher the throughput, but the higher the desorbent flow-rate. An intermediate configuration gives the minimum desorbent consumption. If there are no limits on pressure drop or zone flow-rate, the larger the column length to diameter ratio, the smaller the adsorbent particle size, the higher the throughput, and the lower the desorbent consumption. If the maximum zone flow-rate is controlled by the pressure drop limit and not by the standing waves requirement, the longer the columns, the lower the zone flow-rates and the lower the throughput. For 150-μm adsorbent particles and a maximum zone flow-rate of 300 ml/min, a design with optimal throughput and desorbent consumption is found for paclitaxel purification.
Miguel A. Granato - One of the best experts on this subject based on the ideXlab platform.
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From molecules to processes: Molecular simulations applied to the design of simulated moving bed for ethane/ethylene separation
Canadian Journal of Chemical Engineering, 2013Co-Authors: Miguel A. Granato, Vanessa F.d. Martins, João C. Santos, Miguel Jorge, Alírio E. RodriguesAbstract:This paper presents results of a modelling study on the separation of ethane/ethylene mixture by selective adsorption on zeolite 13X in a simulated moving bed (SMB) unit. Propane and n-butane are evaluated as desorbent candidates. The study encompasses molecular simulation calculations for determination of adsorption parameters, whose results will then be used in a mathematical model for evaluating the performance of an SMB unit. This work is entirely done in silico, by using available force field parameters for the molecular simulations part and reliable mathematical models for the SMB part. Experimental data are solely used for comparison with the molecular simulation results, which are subsequently expanded to calculate adsorption properties for separating the mixtures, without further experimental work. The separation regions of an SMB unit operating with zeolite 13X for ethane/ethylene separation, using propane and n-butane as Desorbents, were obtained by simulation at 110 kPa and at four different temperatures: 298, 323, 348 and 373 K. For each desorbent, an operating point was selected, and the size of the required unit was presented for the complete separation of the two components of the mixture.
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Potential Desorbents for Propane/Propylene Separation by Gas Phase Simulated Moving Bed: A Molecular Simulation Study
Industrial & Engineering Chemistry Research, 2010Co-Authors: Miguel A. Granato, Thijs J. H. Vlugt, Alírio E. RodriguesAbstract:This paper is focused on using molecular simulation as a tool to guide the choice of desorbent for the separation propane/propylene by simulated moving bed (SMB) processes. Equilibrium adsorption isotherms of n-butane and neopentane on zeolite 13X and adsorption equilibria of binary mixtures of each one of these adsorbates with propane and with propylene were obtained by molecular simulation, in a predictive screening of an adequate desorbent for the separation of propane/propylene by the SMB technology. Comparisons of experimental isotherms with grand canonical Monte Carlo simulations in zeolite 13X showed that the results of n-butane are in excellent agreement with reported simulations and experimental data. The carbon−cation interactions for the quaternary carbon atom of neopentane were established and validated through determination of adsorption properties of binary mixtures of neopentane with propane and with propylene. The lack of experimental data of neopentane adsorption motivated the present stu...
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potential Desorbents for propane propylene separation by gas phase simulated moving bed a molecular simulation study
Industrial & Engineering Chemistry Research, 2010Co-Authors: Miguel A. Granato, Thijs J. H. Vlugt, Alírio E. RodriguesAbstract:This paper is focused on using molecular simulation as a tool to guide the choice of desorbent for the separation propane/propylene by simulated moving bed (SMB) processes. Equilibrium adsorption isotherms of n-butane and neopentane on zeolite 13X and adsorption equilibria of binary mixtures of each one of these adsorbates with propane and with propylene were obtained by molecular simulation, in a predictive screening of an adequate desorbent for the separation of propane/propylene by the SMB technology. Comparisons of experimental isotherms with grand canonical Monte Carlo simulations in zeolite 13X showed that the results of n-butane are in excellent agreement with reported simulations and experimental data. The carbon−cation interactions for the quaternary carbon atom of neopentane were established and validated through determination of adsorption properties of binary mixtures of neopentane with propane and with propylene. The lack of experimental data of neopentane adsorption motivated the present stu...
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adsorption of propane propylene and isobutane on a metal organic framework molecular simulation and experiment
Chemical Engineering Science, 2009Co-Authors: Nabil Lamia, Miguel A. Granato, Miguel Jorge, Hubert Chevreau, Alírio E. RodriguesAbstract:The separation of propane/propylene mixtures is the most energy-intensive operation practiced in the petrochemical industry. Adsorptive processes are currently viewed as a promising alternative to cryogenic distillation for the separation of these mixtures. In this paper, we explore the possibility of using a new metal-organic framework material, CuBTC, in adsorptive separation processes, particularly in a simulated moving bed (SMB) context using isobutane as a potential desorbent. A gravimetric method has been used to measure the adsorption equilibrium isotherms of propylene, propane and isobutane onto a commercial CuBTC powder over a temperature range from 323 to 423K and pressures up to 100kPa. These were complemented by a detailed experimental characterization of the structure of CuBTC using XRD and SEM techniques. Comparison of experimental isotherms with grand canonical Monte Carlo simulations in CuBTC showed that propane adsorption occurs preferentially in small octahedral pockets, while isobutame is excluded from these pockets due to its bulky structure. Propylene was seen to interact strongly with unsaturated metal sites, due to specific pi-Cu bonds. These interactions significantly enhance the affinity of this MOF for unsaturated hydrocarbons. Furthermore, in a range of temperatures and pressures, the affinity of CuBTC for isobutane is intermediate to that of propane and propylene. Our results suggest that CuBTC-isobutane is a very promising adsorbent-desorbent pair for use in SMB processes for propane/propylene separations.
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Adsorption Equilibrium of Isobutane and 1-Butene in Zeolite 13X by Molecular Simulation
Industrial & Engineering Chemistry Research, 2008Co-Authors: Miguel A. Granato, Nabil Lamia, Thijs J. H. Vlugt, Alírio E. RodriguesAbstract:Propane−propylene separation is usually done by cryogenic distillation, one of the most energy consuming processes in the chemical industry. Alternative technologies are simulated moving bed (SMB) and vacuum swing adsorption (VSA). In the context of propane−propylene separation by SMB, the choice of suitable Desorbents is a key issue. Recent experimental studies on isobutane and 1-butene as Desorbents to operate a propane−propylene separation with an SMB, using zeolite 13X as solid adsorbent, motivated the present work. In this paper, the single component adsorption isotherms of isobutane and 1-butene and X−Y diagrams of binary mixtures of the Desorbents with propane and propylene in zeolite 13X are computed using a configurational-bias Monte Carlo (CBMC) technique for a temperature range from 333 to 393 K and pressures up to 150 kPa. The interactions between the tertiary sp3 carbon (CH), the sodium cations, and all other atoms of the studied systems have been determined, since no data for these interacti...
Massimo Morbidelli - One of the best experts on this subject based on the ideXlab platform.
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chromatographic reactors with reactive Desorbents
Industrial & Engineering Chemistry Research, 2006Co-Authors: D Gelosa, Andrea Sliepcevich, Massimo MorbidelliAbstract:The possibility of introducing, as a desorbent in a chromatographic reactor, a reactive desorbent that removes the most strongly retained component by chemical reaction and not by purely physical desorption has been investigated. The principle is demonstrated in the case of the esterification of glycerol with acetic acid using a mixture of acetic acid and acetic anhydride as the desorbent and a polymeric acidic resin as the stationary phase. It is shown that reacting the most strongly retained component, water, with acetic anhydride allows for a significant improvement in the column regeneration process, thus improving the process performance in terms of both productivity and desorbent requirements.
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Robust design of countercurrent adsorption separation processes: 4. Desorbent in the feed
Aiche Journal, 2004Co-Authors: Marco Mazzotti, Giuseppe Storti, Massimo MorbidelliAbstract:In many instances of practical interest, countercurrent adsorption separations operate on feed streams containing not only the components to be separated but also some desorbent. Criteria for the optimal and robust design and operation of these units are developed by extending previous treatments developed for desorbent-free feedstreams. The effect of the presence of some desorbent (weak, intermediate, or strong) on the location and robustness of the region of complete separation in the operating parameter space is discussed.
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Optimal design of multicomponent countercurrent adsorption separation processes involving nonlinear equilibria
Chemical Engineering Science, 2001Co-Authors: Giuseppe Storti, Sergio Carrà, Maurizio Masi, Massimo MorbidelliAbstract:Abstract A simple model, based on equilibrium theory, for simulating countercurrent adsorption separation processed involving multiple components and nonlinear equilibrium has been developed. The reliability of this model has been tested by comparison with a detailed model in the context of the separation process for the aromatic fraction C 8 by adsorption on zeolites. Based on this model, a simple and accurate procedure has been developed for designing optimal separation units, where adsorbent and desorbent requirements are minimized while enrichments of both extract and the raffinate are maximized. The emphasis has been placed on the role of the desorbent and the effect of the physical state of the fluid, i.e. vapor or liquid phase operation.
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Robust design of countercurrent adsorption separation processes: 2. Multicomponent systems
Aiche Journal, 1994Co-Authors: Marco Mazzotti, Giuseppe Storti, Massimo MorbidelliAbstract:The adsorption separation of a multicomponent mixture in a four-section countercurrent separation unit is analyzed. A procedure for the optimal and robust design of the unit is developed in the frame of equilibrium theory, where adsorption equilibria are described through the constant selectivity stoichiometric model, while mass-transfer resistances and axial dispersion are neglected. A set of conditions obtained defines a region in the operating parameters space where the unit achieves complete separation. In the case of binary separations, with a desorbent having any adsorptivity with respect to the components to be separated, the boundaries of this region are obtained explicitly. In the general multicomponent case, a numerical procedure is needed. An approximate shortcut method devised allows to obtain explicit and reliable relationships for estimating the boundaries of the exact region. The results provide a very convenient tool not only to analyze the role of the desorbent in determining the separation performance, but to find both optimal and robust operating conditions. Comparison between model predictions and experimental data assesses the reliability and accuracy of the theoretical findings.