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Chromatographic separation plays a pivotal role in the manufacturing of chemical products and biopharmaceuticals. This technique exploits differences in distribution between stationary and mobile phases to separate mixtures, impacting final product quality. Simulated moving bed (SMB) technology, recognized for its continuous feed, enhances efficiency and increases production capacity while reducing solvent and water consumption. Despite its complexity in controlling variables like flow rates and valve switching times, traditional control theories fall short. This study introduces an intelligent fuzzy controller resembling an approximate neural network (NN) for SMB control. Simulation results demonstrate the controller's effectiveness in achieving desirable outcomes for the SMB system. [ABSTRACT FROM AUTHOR]

Because of high efficiency and cleanness, the simulated moving bed (SMB) is the most important technology in chromatographic separation. SMB system, which contains several sectors of flow rate, the switching time of valves and many other possible influencing variables, is complex, highly sensitive and difficult to control. This paper proposes adjusted fuzzy control; the adjusted fuzzy controller is applied to the SMB system to control the separation concentration by establishing a variable direction correction formula. Compared with the traditional fuzzy controller, the adjusted fuzzy controller does not need to analyze the dynamic direction of the control force in advance, moreover, the control accuracy is high and the fluctuation is small for SMB system. [ABSTRACT FROM AUTHOR]

Highlights: [•] A low computation time is a key need for optimization of SMB systems. [•] A method is presented for the simulation of a separation column. [•] The method shows to be much faster than other ones for the same accuracy. [•] Simulations were compared to experimental data showing a good agreement. [Copyright &y& Elsevier]

Abstract: This work addresses optimization of an improved single-column chromatographic (ISCC) process for the separation of guaifenesin enantiomers. Conventional feed injection and fraction collection systems have been replaced with customized components facilitating simultaneous separation and online monitoring with the ultimate objective of application of an optimizing controller. Injection volume, cycle time, desorbent flow rate, feed concentration, and three cut intervals are considered as decision variables. A multi-objective optimization technique based on genetic algorithm (GA) is adopted to achieve maximum productivity and minimum desorbent requirement in the region constrained by product specifications and hardware limitations. The optimization results along with the contribution of decision variables are discussed using Pareto fronts that identify non-dominated solutions. Optimization results of a similar simulated moving bed process have also been included to facilitate comparison with a continuous chromatographic process. [Copyright &y& Elsevier]

Abstract: We present here a mechanistic view of adsorption processes for separation of gas mixtures. The moving-bed adsorber (abandoned due to practical difficulties) is shown to offer orders of magnitude higher productivity than the conventional pressure swing adsorption (PSA) and yields ‘perfect separation’. To realize its potential in fixed beds, simulated moving bed (SMB) with pressure or thermal swing and 3-bed and 4-bed PSAs that emulate moving-bed adsorbers have been proposed. Based on their characteristics of phase equilibria and separating agents employed, a classification of adsorption processes has been proposed as ‘absorption like’, ‘distillation like’ and ‘chromatographic’ processes, which provides insight into these processes and a rational basis for their design. The mechanism of separation in moving bed, SMB and the conventional PSA are shown to be similar to that of either absorption or distillation. On the other hand, the duplex, molecular-gate and rapid PSAs are shown to share the same separation mechanism that is akin to heat-transfer mechanism in heat regenerators. Subtle but significant differences in the role of ‘reflux’ in absorption-like and distillation-like processes and their implications in process design have been highlighted. Though process intensification in molecular-gate PSA and duplex PSA is modest compared to the SMB, they appear to hold promise since they are based on a proven technology. Their adaptability for absorption and extraction using immobilized solvent has been presented. [Copyright &y& Elsevier]

Abstract: In this work, we investigate the potential of a MOF porous material, Cu-BTC in combination with cyclic adsorption processes (vacuum swing adsorption, VSA, and simulated moving bed, SMB) for the separation of propylene/propane mixture. A gravimetric method has been used to measure the adsorption isotherms of propylene, propane and isobutane onto Cu-BTC extrudates over a temperature range from 323 to 373K and pressures up to 500kPa. These were complemented by experimental characterization of the Cu-BTC material using XRD and SEM-EDS techniques. Whereas the separation and its kinetics were studied by breakthrough experiments on a column packed with the Cu-BTC material in the extruded form at 373K. The Cu-BTC extrudates are selective towards propylene, highlighting the potential of this material for the separation of propane and propylene mixtures by PSA process. Furthermore, in a range of temperatures and pressures, the affinity of Cu-BTC for isobutane was observed to be intermediate to that of propane and propylene which suggest that isobutane is a promising desorbent in SMB processes for propane/propylene separations. [Copyright &y& Elsevier]

In this work, the Outlet Stream Swing (OSS) non-conventional operation technique is compared with a classical Simulated Moving Bed (SMB) unit, for the separation of a racemic mixture of guaifenesin. A methodic approach, based on the complete separation and regeneration regions, is used to evaluate the performance of the OSS extract-raffinate, as well as the OSS raffinate-extract, operating strategies with the classical SMB in terms of purity, productivity and eluent consumption requirements. The variants of the OSS technique: OSS extract-0 and OSS raffinate-0 are presented, simulated, and used not only to introduce more simplistic OSS modes of operation, but also to better understand the influence of specific OSS operating parameters. The experimental validation of OSS extract-0, operated by means of the FlexSMB-LSRE® unit, is also presented as part of this work, demonstrating the potential, as limitations, of such operating techniques. [ABSTRACT FROM AUTHOR]

The article describes a procedure for separating chiral mixtures in real simulated moving bed (SMB) technology and presents a new flexible unit, the FlexSMB-LSRE. An extended SMB separation methodology was applied which considers different unit design particularities and a measures to compensate either dead volumes switching time asymmetries or delay in order to be able to separate a racemic mixture of guaifenesin with product purities higher than 98% and productivity of 23 g enantiomer/dm³CPS day in the lab-scale.

A gradient SMB model is used to analyze the separation performance of proteins in a step-wise salt gradient ion-exchange simulated moving bed (IE-SMB) for the nonlinear adsorption equilibrium isotherms. The strategy of the selection of salt gradient in IE-SMB chromatography is discussed based on the adsorption equilibrium isotherms of both BSA and myoglobin on Q-Sepharose FF anion exchanger in the pH 8 Tris buffer. The separation region is used to select the flow rates in the salt gradient IE-SMB chromatography for the separation of proteins. The separation region is calculated by the gradient SMB model where both the mass transfer resistance in the ion exchangers and axial liquid dispersion in columns are taken into account. Some strategies are suggested for the selections of salt gradient and flow rates in the IE-SMB chromatography with open loop configuration for two cases: (a) binary separation of proteins with the requirement of the complete recovery from extract stream and raffinate stream; and (b) protein purification from a stream with some impurities. [ABSTRACT FROM AUTHOR]

A new simulated moving bed (SMB) operation technique is introduced, the outlet streams swing (OSS), based on the dynamic collection of fronts from the equivalent true moving bed (TMB). This new assumption improves the product outlet purities, when compared with the classic operating mode, as a consequence of an increased separation between collection fronts and the contaminating ones. The strategy is dynamic and discontinuous, a collection front expansion is performed in zone 1 and/or 4, obtained by the violation of the classic respective design constraints during a first step and contraction during the second step using at least the classic design operating parameter for zones 1 and 4. Another non-conventional technique, the MultiFeed (MF) SMB operation, is simulated and analyzed here as a solo technique as well as a powerful modelling technique for the particular case of inner sections Varicol® (only the zones 2 and 3 have variable number of columns). [ABSTRACT FROM AUTHOR]

Analogs, recycled chromatography systems that mimic SMBs, for both a cascade of two four‐zone SMBs and five‐zone SMBs performing ternary separations are designed and analyzed. The basic Analog consists of one column and several mixed tanks equal to the number of columns in the mimicked SMB. Analogs with mixed tanks give lower purities than the SMBs because of mixing in the tanks. For example, the five‐zone SMB with one column per zone achieved a purity index (PI) of 88.3, while the Analog with five mixed tanks has a PI of 83.4. If the tanks are divided into smaller tanks the purity improves, and for the Analog to be the five‐zone SMB using 10 tanks the PI was 85.4. Analogs with a single unmixed reservoir were also designed for a cascade of two four‐zone SMBs with one column per zone. This reservoir reduces the mixing and improves the separation. For example, a cascade of two four‐SMBs with one column per zone achieved a PI of 86.7; the Analog to this SMB with 8 mixed tanks achieved a PI of 82.9, while the Analog with an unmixed reservoir achieved a PI of 84.6. [ABSTRACT FROM AUTHOR]

Simulated Moving Bed or SMB chromatography is a continuous adsorption technique that increases throughput, purity and yield relative to batch chromatography. SMB utilizes a series of columns with periodically moving inlet and outlet ports. This technique has been applied for the production of petrochemicals and sugars, and to a limited extent, pharmaceuticals. The recent surge in SMB research has led to various novel SMB schemes or configurations. This review presents a survey and comparison of SMB schemes and equipment, specifically SMB valve designs, which are needed to implement the various schemes. Illustrated examples include SMBs with three, four, five, eight, nine, or twelve zones, Varicol scheme, Japan Organo process, fast startup and shutdown, and online decoupled regeneration. The SMB valve designs reviewed are classified into central and distributed valves designs, which include two-way-valve designs and rotary-valve designs. We also present a novel SMB design, the Versatile SMB or V-SMB, which can implement all the novel schemes by using a one-rotary-valve-per-column design. Select-Trapping valves are used to interrupt the stream between the columns and to act as a junction that allows streams to be partially or totally added or removed, or to flow through to the next column. The streams can also be redirected to another SMB zone. Compared to other SMB valve designs, the V-SMB:(1) can be configured for open-loop, multi-zone and zone bypass operation;(2) does not require a carousel for column rotation;(3) does not contribute to product contamination;(4) allows independent port switchings, which is required for certain schemes;(5) allows additional columns to be added easily; and,(6) requires only constant speed pumps. The V-SMB has successfully purified enantiomers, sugars, organic acids, an antibiotic, and biosynthetic human insulin. [ABSTRACT FROM AUTHOR]