Multicomponent Separation Research Articles

A Bioinspired Multicomponent Catalytic System for Converting Carbon Dioxide into Methanol Autocatalytically

<h2>Summary</h2> Nature utilizes multicomponent catalyst systems to convert simple, abundant starting materials into complex molecules that are essential for life. In contrast, synthetic chemical transformations rarely adopt this strategy because it is difficult to replicate the sophisticated supramolecular assemblies used by biology for active-site separation and substrate trafficking. Here, we describe a method for multicomponent catalyst separation that involves encapsulating transition-metal complexes in nanoporous materials called metal-organic frameworks. The multicomponent catalyst system was highly active for converting hydrogen and carbon dioxide to methanol, and it could be formulated to be readily recyclable. Moreover, we uncovered an autocatalytic feature that was possible only when we utilized the multicomponent catalyst strategy. These results open avenues for obtaining fuel from abundant and renewable resources.

Indices of Efficiency of Multicomponent Separation in Cascades with Assigned External Concentrations of the Target Component

Consideration has been given to the features of introducing indices of efficiency of cascades based on separation potentials of a multicomponent isotope mixture. Basic forms of potentials of two types have been presented, the first of which is dependent on just the concentration, and the second, through the inclusion of mass numbers of separation factors, ensures the independence of the separative power of separating elements of concentrations. On the basis of a computational experiment, the authors have selected potentials most adequately determining separation-efficiency indices for cascades that were optimized for the minimum criterion of the overall stream at assigned external concentrations of the target component.

Biomolecular Phase Separation: From Molecular Driving Forces to Macroscopic Properties.

Biological phase separation is known to be important for cellular organization, which has recently been extended to a new class of biomolecules that form liquid-like droplets coexisting with the surrounding cellular or extracellular environment. These droplets are termed membraneless organelles, as they lack a dividing lipid membrane, and are formed through liquid-liquid phase separation (LLPS). Elucidating the molecular determinants of phase separation is a critical challenge for the field, as we are still at the early stages of understanding how cells may promote and regulate functions that are driven by LLPS. In this review, we discuss the role that disorder, perturbations to molecular interactions resulting from sequence, posttranslational modifications, and various regulatory stimuli play on protein LLPS, with a particular focus on insights that may be obtained from simulation and theory. We finally discuss how these molecular driving forces alter multicomponent phase separation and selectivity.

Enhancing separation efficiency in European syngas industry by using zeolites

Syngas is traditionally used in industry for production of fuels in the kerosene, gasoline and diesel range via Fischer-Tropsch, for the manufacture of bulk chemicals like ammonia, methanol and dimethyl ether and for synthesis of a whole array of fine chemicals. The carbon monoxide/hydrogen ratio of the syngas is an important design variable to maximize production of these compounds. Therefore, the search of effective processes that enable said ratio adjustment as well as individual compound purification is an essential and ongoing effort for industry. In this work, we propose a development of a zeolite-based separation process to obtain carbon dioxide-neutral fuels and chemicals. The process designed is based on gas uptake and release, combining separation efficiency with low separation costs. Calculation of separation behavior has been done for mixtures generated by plasmolysis of CO2. Carbon dioxide dissociation into CO and O2 and as a result a mixture of carbon monoxide, oxygen and a residual carbon dioxide is obtained. Therefore, the purification of CO becomes necessary. Here we provide a purification process design based in multicomponent adsorption and separation in commercial available zeolites. The process identifies NaX and NaY as the most suitable zeolites for separation in a wide range of operating conditions.

Separation and concentration of bioactive phenolic compounds by solvent sublation using three-liquid-phase system

The present work investigated the SS performance with focus on the addition of second collecting phase to intensify the separation of vanillin and eugenol. First, experiments were performed with only n-octanol as the only collecting phase and the effects of solutes concentration and pH of the bottom phase were evaluated on the separation efficiency (E%). Then, the SS process was performed in a three-liquid-phase system formed by n-octanol/PEG 400/(NH4)2SO4 and the results were evaluated based on E%, distribution coefficient (D) and vanillin selectivity (RVAN/EUG) values. When compared to single component experiments, the presence of another solute had little effect on the E% values of vanillin and eugenol, regardless of the range of the initial concentration. Moreover, in SS with n-octanol/acetate buffer it was possible to reach the highest values of E% for vanillin (53.83%) and eugenol (85.37%) in experiments with pH equal to 4.5. On the other hand, the three-liquid-phase system achieved selectivity at least twice as high as two-liquid-phase systems and D values higher than 25 for vanillin in the PEG 400-rich phase. Thus, SS using three-liquid-phase system appears as an alternative to solve multicomponent separation problems involving bioactive compounds.

Multicomponent gas separation and purification using advanced 2D carbonaceous nanomaterials.

Multicomponent gas separation and purification is an important pre- or post-processing step in industry. Herein, we employed a multiscale computational approach to investigate the possibility of multicomponent low-weight gas (H2, O2, N2, CO2, CH4) separation and purification using novel porous 2D carbonaceous nanomaterials, namely Graphdiyne (GD), Graphenylene (GN), and Rhombic-Graphyne (RG). The dispersion-corrected plane-wave density functional theory (DFT) calculation combined with the Climbing Image Nudged Elastic Band (CI-NEB) method was employed to study the gas/membrane interaction energy and diffusion barrier of different gases passing through the geometrically optimized membranes. The results from CI-NEB calculations were then fitted to the Morse potential function to construct a bridge between quantum mechanics calculations and non-equilibrium molecular dynamics (NEMD) simulation. The selectivity of each membrane for all binary mixtures was calculated using the estimated diffusion energy barriers based on the Arrhenius equation. Finally, a series of extensive NEMD simulations were carried out to evaluate the real word and time dependent separation process. According to the results, CH4 molecules can be completely separated from the other gases using a GD membrane, O2 molecules from CH4, N2, and CO2 by a GN membrane, and H2 molecules from all other gases using a RG membrane.

Some Aspects of Deriving Multicomponent Separation Potential

The initial postulates and mistakes of the existing theory of potential of multicomponent isotope separation have been analyzed. It is shown that problems of deriving the separation potential of a multicomponent mixture are caused by the absence of a correct definition of a stage (separating element) for a cascade. Two variants of the definition of a stage are presented, and the relationship of these definitions with the expression for the separation potential of a multicomponent mixture are demonstrated.

Optimal configuration of ternary distillation columns using heat integration with external heat exchangers

The subject of energy saving in distillation column sequencing is of critical importance. Heat integration in a multicomponent separation can be industrialized by saving considerable energy and cost. In this work, external heat-integrated distillation column with external heat exchanger has been studied and the annual cost function has been optimized using Genetic Algorithm. Introducing the layout and binary matrices enabled the investigation of all possible locations for the heat exchanger arrangement successfully. Moreover, exchangers heat loads and compressors pressure, have also been considered as optimization variables. Benzene, toluene, xylene and n-alkanes, separations have been studied as case studies. It has been demonstrated that the proposed optimization method in the alkane separation case decreased the total annual cost by 22.6% in comparison with the proposed thermally coupled distillation sequence columns. The heat integration of external heat exchangers in an external heat-integrated distillation column configuration and the proposed dived-wall column resulted in decreasing the total annual cost by 17% and 39% respectively, in comparison with conventional distillation columns.

Mechanistic insights into selective adsorption and separation of multi-component anionic dyes using magnetic zeolite imidazolate framework-67 composites

The development of highly efficient magnetic adsorbents, especially those aimed at adsorption and separation of multi-component dyes, is one of the new challenges in the water treatment field. In this study, zeolite imidazolate frameworks-67 (ZIF-67) loaded on magnetic nanoparticles named MZIF-67 composites was synthesized and applied to adsorption and separation of anionic dyes mixture. Direct blue 86 (DB-86) and methyl orange (MO) were selected as model contaminants. The most intriguing feature is that MZIF-67 can successfully separate DB-86 from mixed dye molecules in aqueous solution with high effectivity and selectivity, even for DB-86 molecule with a large size. The satisfactory adsorption and separation properties (adsorption capacity, equilibrium time, adaptability to solution changes and rapid magnetic separation) indicated MZIF-67 as an efficient adsorbent. Furthermore, the MZIF-67 before and after adsorption was carefully characterized by X-ray photoelectron spectroscopy (XPS) spectra which proved the main mechanism of MZIF-67 adsorption toward anionic dyes: ZIF-67 surface provided large number of uncoordinated cobalt sites bonding with hydroxide derived from water (Co–OH) and subsequently formed complex with anionic dyes under hydrogen bonding, accompanied by the electrostatic interaction between positively charged ZIF-67 and the anionic sulfonate group. This work is expected to provide insight mechanisms of MZIF-67 adsorption toward anionic dyes and offer promising magnetic ZIFs for multi-component system separation.

Multicomponent adsorptive separation of CO2, CO, CH4, N2, and H2 over core-shell zeolite-5A@MOF-74 composite adsorbents

With the aim of developing more efficient H2 purification adsorbents, we demonstrated the application of novel hybrid nanocomposites comprising of zeolite 5A and MOF-74 with core-shell structure in purification of H2 from SMR off-gas streams, in the first part of this investigation [14]. Through equilibrium adsorption measurements, it was shown that zeolite-5A@MOF-74 with weight ratio of 5:95 exhibited 20–30% increase in CO2, CO, CH4, and N2 uptake than the bare MOF, as a result of its higher surface area and pore volume. In this work, dynamic adsorption performance of zeolite-5A@MOF-74 in H2 purification process was evaluated through binary and multicomponent breakthrough measurements at various pressures. Moreover, high-pressure adsorption isotherms (up to 20 bar) were used to estimate the theoretical selectivity values for (CO2+CO+CH4)/H2 for comparison with actual selectivities estimated from breakthrough profiles. At 20 bar and room temperature, the composite exhibited equilibrium capacities of 13.8, 8.0, 7.7, and 6.7 mmol/g for CO2, CO, CH4, and H2, respectively which were higher than those of the parent adsorbents. Moreover, multicomponent breakthrough results showed that the selectivity for (CO2 + CO + CH4)/H2 over the composite adsorbent is higher than that over the parent MOF-74 and zeolite 5A materials across all pressures. The total mass transfer coefficients estimated from breakthrough simulations ranged from 6.22 × 10−2, 4.73 × 10−2, and 3.29 × 10−2 s−1 for H2 to 9.23 × 10−5, 7.6 × 10−5, and 6.61 × 10−5 s−1 for CO2, for zeolite-5A@MOF-74, MOF-74, and zeolite 5A, respectively at 1 bar, with the coefficients slightly decreasing as total pressure increased to 15 bar.

Computational fluid dynamic (CFD) simulation of a cuboid packed-bed chromatography device

Flow non-uniformity is a major problem with process chromatography columns which typically have small bed height to diameter ratios. In recent publications, we have proposed box-shaped or cuboid packed-bed devices as efficient alternative to process columns for carrying out high-resolution chromatographic separations. Cuboid packed-bed devices show superior performance in terms of number of theoretical plates, peak width, and peak resolution in multicomponent separations. This paper attempts to explain this based on computational fluid dynamic (CFD) simulations of a cuboid packed-bed device and its equivalent column, i.e. having the same bed height and area of cross-section, and packed with the same chromatographic media. The radial velocity in the column headers decreased very rapidly from the axis to the periphery resulting in significant variation in average velocity along the different flow paths within the column. By contrast, the velocity decreased linearly in the top channel and increased linearly in the bottom channel of a cuboid packed-bed device, resulting in significantly lower variation in the average velocity. Simulated flow-through peaks obtained with the cuboid packed-bed device using dextran as a macromolecular and sodium chloride as a low molecular weight tracer were significantly sharper and more symmetric. Experimental results were in good agreement with those obtained by simulation. Overall, the superior performance of the cuboid packed-bed device could be primarily attributed to the narrower solute residence time distribution resulting from greater flow uniformity.

Separation of nadolol racemates by high pH reversed-phase preparative chromatography

The separation of nadolol racemates under high pH reversed-phase preparative chromatography is presented for the first time.Three Waters C18 adsorbents (XBridge, Shield and XSelect) are compared for the separation of nadolol racemates using ethanol:water:diethylamine solvent mixtures. Experimental and simulation results are presented to compare the separation performances at preparative scale using both the fixed-bed and the simulated moving bed operations.The Waters XBridge C18 adsorbent and an ethanol:water:diethylamine solvent mixture are selected as a good option for the separation of nadolol racemates. The validated methodology allows the separation of a multicomponent nadolol feed mixture composed by four stereoisomers into two pure racemates (two pairs of enantiomers). This work introduces the potential of using an initial achiral separation step in the global strategy for the complete multicomponent separation of the four nadolol stereoisomers.

Gas Chromatography in Technology of High-Purity Noble Gases

The article presents the classification of the gas stream contaminant types in noble gas enrichment and purification units. For the safe and efficient system operation, it is necessary to choose the right method of multicomponent mixture separation and the optimal corresponding equipment operating parameters, also to offer a method to verify the absence of the undesirable contaminant in the gas stream. The methods to control the obtaining of required noble gas purity during cryogenic rectification are indicated. Application of various gas analysis methods is necessary to obtain high purity (up to 99.9999%) gases: gas chromatography, mass spectrometry, and their combination. The effect of the state of various components of a gas chromatograph on the analysis result are discussed. Recommendations are provided for noble gas analysis methodology, including the conditions for the determination of trace impurities. The article presents examples of practical application of gas chromatography to control the processes of noble gas enrichment and purification, using the example of production of pure xenon.

Direct Simulation of Ternary Mixture Separation in a ZIF‐8 Membrane at Molecular Scale

AbstractSeparation of H2 in a ZIF‐8 membrane from a syngas mixture composed of CO2, H2, and N2 at 300 K and 35 atm is simulated with the concentration gradient driven molecular dynamics (CGD‐MD) method. Steady‐state fluxes are computed to predict the H2 selectivity of the ZIF‐8 membrane using four different flexible force fields developed for ZIF‐8. The permselectivities predicted by the CGD‐MD method are compared with those obtained from the grand canonical Monte Carlo+equilibrium molecular dynamics (GCMC+EMD) approach, which is based on the solution‐diffusion model and widely used to predict permselectivities for mixture separations. The permselectivities obtained by using the CGD‐MD method accurately predict that ZIF‐8 is H2 selective over CO2 and N2. On the other hand, permselectivities predicted with the GCMC+EMD approach are found to be incorrect, that is, ZIF‐8 not selective for H2. The study suggests that a reliable non‐equilibrium molecular dynamics approach should be employed in order to obtain accurate predictions for the permselectivity of a membrane for a multicomponent mixture separation process which happens at moderate or high pressure conditions.

A Strategy for Quality Control of Vespa magnifica (Smith) Venom Based on HPLC Fingerprint Analysis and Multi-Component Separation Combined with Quantitative Analysis

As a folk medicine of the Jingpo minority in Yunnan province, the venom of Vespa magnifica has been commonly used for the treatment of rheumatoid arthritis. Quality standardization of the wasp venom is a necessary step for its pharmaceutical research and development. To control the quality of the wasp venom, a method based on high-performance liquid chromatography (HPLC) was developed for chemical fingerprint analysis. In the chromatographic fingerprinting, chemometrics procedures, including similarity analysis (SA), hierarchical clustering analysis (HCA), and principal component analysis (PCA), were applied to classify 134 batches (S1–S134) of wasp venom from different origins. The HPLC fingerprint method displayed good precision (Relative standard deviation, RSD < 0.27%), stability (in 16 h, RSD < 0.34%), and repeatability (RSD < 1.00%). Simultaneously, four compounds (VMS1, VMS2, VMS3, and VMS4) in the wasp venom were purified and identified. VMS1 was 5-hydroxytryptamine, and the other compounds were three peptides that were sequenced as follows: Gly–Arg–Pro–Hyp–Gly–Phe–Ser–Pro–Phe–Arg–Ile–Asp–NH2 (VMS2), Ile–Asn–Leu–Lys–Ala–Ile–Ala–Ala–Leu–Ala–Lys–Lys–Leu–Leu–NH2 (VMS3), and Phe–Leu–Pro–Ile–Ile–Gly–Lys–Leu–Leu–Ser–Gly–Leu–Leu–NH2 (VMS4). The quantifications for these components were 110.2 mg/g, 26.9 mg/g, 216.3 mg/g, and 58.0 mg/g, respectively. The results of this work indicated that the combination of the chemical fingerprint and quantitative analysis offers a reasonable way to evaluate the quality of wasp venom.

ENERGY AND EXERGETIC EVALUATION OF THE MULTICOMPONENT SEPARATION OF PETROCHEMICAL NAPHTHA IN FALLING FILM DISTILLATION COLUMNS

Abstract Multicomponent separation of synthetic petrochemical naphtha (hexane, cyclohexane, toluene and xylene) was carried out in a falling film distillation sequence with heat supply using a vapor chamber (thermosyphon). Tests were carried out by varying feed flow rate and temperatures of the feed and the vapor chamber in two ways of heat supply: isothermal and with a vapor chamber temperature profile. Regarding the distillation behavior of the multicomponent separation with the proposed falling film column, it was verified that the lower values of the studied variables and the profile temperature mode promoted the best results for hexane recuperation. With an indirect sequence of three columns, hexane mass fraction in the top column increases to the value of 0.82. Higher thermodynamic efficiency was found for two columns of the sequence in comparison with the conventional ones. This behavior is related to smaller energy consumption, showing a total energy reduction of 12% compared to the same separation performed in a conventional unit. Energy and exergetic efficiency values were higher than 95% and 85% in the three columns used. These analyses demonstrated that the falling film separation proposal is an energy efficient arrangement and could be considered for multicomponent separation.

Process Dynamic and Control for Nonconventional Column/Rectifier Configuration with Aspen Hysys v10.0

Nonconventional column/rectifier configuration is the new alternate design for the sequence multicomponent separation of three or more products. It can accomplish an efficient energy. There are two columns, the first is the rectifier and the second is the main, the vapor sidestream is taken out from the location under the feed tray of the main column then fed to the rectifier column and the liquid that from the bottom of the rectifier column is turned back to the main column. In order to completely understand the dynamic behavior of complex process of this configuration, process dynamic and control of it has to be studied intensively. The implementation of it is demethanizer and deethanizer column. The configuration has been simulated for dynamic by using Aspen Hysys v10.0. The results show that the graph of rejecting disturbance from all controllers of the main column need more attention especially for inventory control i.e. level controller for reflux drum, sump level reboiler and pressure controller for condenser. The overshoot for level controller of reflux drum of main column is 10% from set points. The better algorithm of tuning is required. The results of this studied could provide guidance for composition controller of this configuration.

Differentiation of Various Snake Bile Derived from Different Genus by High-Performance Thin-Layer Chromatography Coupled with Quadrupole Time-of-Flight Mass Spectrometry.

Background: Snake bile originates from nearly 20 species from three families (Elapidae, Colubridae, and Viperidae). However, the components of various snake bile were not compared with one another. Objecive: The aim of the study was to develop a TLC-MS method for differentiation of various snake bile derived from a different genus. Method: As a type of traditional identification method for Chinese herbs, TLC has considerable advantages as a multicomponent separation system. Results: In this paper, TLC was used to separate the components in snake bile. It was found that the snake bile from Colubridae family and Cobra species is different from the others using TLC. The molecular formulas of the bands were elucidated with TLC coupled with quadrupole-time-of-flight-MS by the TLC-MS interface. Two bands on the plate were identified with the reference substance, and the other three bands were analyzed by the TLC-MS method without the reference substance. The corresponding molecular formulas of these bands were given according to accurate molecular weights. Conclusions: The results from this study indicate that the proposed method is reliable, and it has been successfully applied to the identification of snake bile samples.

Single-Phase Instability in Non-Premixed Flames Under Liquid Rocket Engine Relevant Conditions

Under rocket-relevant conditions, real-gas effects and thermodynamic nonidealities are prominent features of the flow field. Experimental investigations indicate that phase separation can occur, depending on the operating conditions and on the involved species in the multicomponent flow. During the past decades, several research groups in the rocket combustion community have addressed this topic. In this contribution, a high-fidelity thermodynamic framework comprising real-gas and multicomponent phase-separation effects is employed to investigate liquid-oxygen/methane and liquid-oxygen/hydrogen flames at high pressure. A thorough introduction and discussion on multicomponent phase separation are conducted. The model is validated with experimental data and incorporated in a reacting flow computational fluid dynamics code. Using one-dimensional counterflow diffusion flames, the thermodynamic states and processes are discussed. Both real-gas and phase-separation effects are present and quantified in terms of derived properties. Finally, the method is applied in a three-dimensional Large-Eddy Simulation of a single-element reference test case, and the results are compared to experimental data.

Global optimization of multicomponent distillation configurations: Global minimization of total cost for multicomponent mixture separations

We introduce a global optimization framework for determining the minimum cost required to distill any ideal or near-ideal multicomponent mixture into its individual constituents using a sequence of columns. This new framework extends the Global Minimization Algorithm (GMA) previously introduced by Nallasivam et al. (2016); and we refer to the new framework as the Global Minimization Algorithm for Cost (GMAC). GMAC guarantees global optimality by formulating a nonlinear program (NLP) for each and every distillation configuration in the search space and solving it using global optimization solvers. The case study presented in this work not only demonstrates the need for developing such an algorithm, but also shows the flexibility and effectiveness of GMAC, which enables process engineers to design and retrofit energy efficient and cost-effective distillation configurations.