Comparison of Adsorbent Behavior in Glucose/Fructose Separation by Simulated Moving Bed (SMB) Chromatography

Transcription

1 University of Twente Faculty of Chemical Technology Comparison of Adsorbent Behavior in Glucose/Fructose Separation by Simulated Moving Bed (SMB) Chromatography Authors: J. Blignaut K. Albataineh Y. Banat Z. Abu El-Rub Supervisor: Prof. dr. ir. Van der Haam. Enschede, 2001

2 Table of Contents Abstract Introduction i 1 1. The Principles of Simulated Moving Bed Chromatography Continuous counter current adsorption systems The simulated moving bed process The four-section SMB cascade 5 2. Modeling of SMB Column Equivalent counter-current model 8 3. Characteristics of Adsorbents and Modeling Results Ca2+ exchanged ion exchange Non-polar dealuminated Faujasite zeolite CaY zeolite Activated carbon Adsorbent behavior comparison Conclusions and Recommendations Conclusions Recommendations 26 References Nomenclature Appendices Appendix 1: Ca 2+ exchanged ion exchanger simulation 30 Appendix 2: Non-polar dealuminated FAU zeolite simulation 31 Appendix 3: CaY zeolite simulation 34

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4 Introduction The implementation of high-performance separation units constitutes a key stage in industrial development. Several chromatographic separation processes have been developed in the last years, proving this a technique of interest at an industrial scale. Chromatography is one of the few separation techniques that can separate a multicomponent mixture into nearly pure components in a single device, generally a column packed with a suitable sorbent. The degree of separation depends upon the length of the column and the differences in component affinities for the sorbent. Although batch chromatography is a relatively simple process offering operating flexibility, it suffers from a lot of difficulties like requirement of a large difference in the adsorptive selectivity of components and ineffectively use of adsorbent bed. In order to avoid all of theses disadvantages, continuous counter-current methods have been developed where mass transfer is maximized, thus a more efficient usage of the adsorbent is presented. However such processes have the difficulties involved in circulating a solid adsorbent. Liquid chromatography in simulated moving bed (SMB) allows us to overcome these difficulties. The simulated moving bed process is realized by connect a multiple column fixed bed system, with an appropriate sequence of column switching designed to simulate a counter flow system. Processes based on this concept have been developed for a number of commercially important separations of both aqueous and hydrocarbon systems in sugar and petrochemical industries, respectively. The separation of fructose-glucose mixtures in the production of high fructose syrup is generally carried out by simulated counter-current adsorption. The objective of this report is to compare the behavior of a simulated moving bed by using Ca +2 exchanged ion exchanger, CaY zeolite, non-polar dealuminized FAU zeolite and activated carbon. 1

5 This report consists of five chapters. Chapter one discusses the principles of simulated moving bed chromatography. A steady-state model of the simulated moving bed is derived in chapter two. Chapter three consists of the characteristics of the adsorbents and the results. Chapter four discusses the results. Finally conclusions and recommendations are presented in chapter five. Finally, We hope that you will find a plain and sufficient coverage concerning the subject at hand, a simple one as well. 2

6 Chapter One The Principles of Simulated Moving Bed Chromatography Chromatographic processes provide a powerful tool for the separation of multicomponent mixtures in which the components have different adsorption affinities, especially when, high yields and purities are required. Typical applications are found in the pharmaceutical industry and in the production of the fine chemicals. An industrially relevant system whose adsorption thermodynamics can be described by linear isotherms over a specific adsorbent is the fructose-glucose system [1]. In this area, the simulated moving bed (SMB) technology is becoming an important technique for large-scale continuous chromatographic separation processes. It provides the advantages of a continuous counter-current unit operation, while avoiding the technical problems of a true moving bed. The aim of this chapter is to present a clear explanation of how the SMB process operates. 1.1 Continuous counter-current adsorption systems For the bulk separation of liquid mixtures, continuous counter-current systems are preferred over batch system because they maximize the mass-transfer driving force. This advantage is particularly important for difficult separations where selectivity is not high and/or where mass-transfer rates are low. Ideally, a continuous counter-current system involves a bed of adsorbent moving downward in plug flow and the liquid mixture flowing upward in plug flow through the bed void space. Unfortunately, such a system has not been successfully developed because of problems of adsorbent attrition, liquid channelling, and non uniform flow of adsorbent particles. Successful commercial systems are based on a simulated counter-current system using a stationary bed. 3

7 1.2 The simulated moving bed process As mentioned earlier, most of the benefits of counter-current operations can be achieved without the problems associated with moving bed adsorbent by using a multiple column fixedbed system, with an appropriate sequence of column switching designed to simulate a counter flow system. The basic principle is illustrated in Figure (1.1). Figure (1.1) Schematic diagram showing the sequence of column switching in a SMB countercurrent adsorption system; the shading indicates the concentration profiles just prior to switching.[2] At each switch a fully regenerated column is added at the outlet of the adsorption side which is approaching breakthrough while the fully loaded column at the end of the adsorption side is switched to the outlet end of the regeneration train. In this way the adsorbent seems to be moving counter-currently to the fluid flow. With sufficiently small elemental beds switched with appropriate frequency such a system indeed becomes a perfect analogue of a counter-current flow system. 4

8 1.2.1 The four-section SMB cascade For fructose-glucose separation, there are two types of SMB cascades, the three-section SMB cascade and the four-section SMB cascade. In the three-section SMB, the adsorbent is contained in a number of identical columns connected in series through pneumatically controlled switch valves that also allow the introduction of feed or eluant or withdrawal of product between any pair of columns. At any given time one column is isolated from the cascade and purged with eluant. The more strongly adsorbed species (extract product) is recovered in the effluent from the purge column. To simulate counter-current flow the eluant inlet, feed, raffinate product and purge points are all advanced by one column in the direction of fluid flow at fixed time intervals. The separation of fructose-glucose mixtures by this method is relatively straightforward since adsorbents with reasonably high selectivity are available. There is therefore little difficulty in achieving a clean separation with a modest number of theoretical stages. With product purity specifications easily achievable the main economic consideration becomes the maintenance of adequate product concentration and minimization of dilution. In this respect the four-section SMB unit is superior to the three-section system and it is therefore adopted in virtually all largescale fructose-glucose separation processes. The four-section system shown in Figure (1.2) provides a more economical use of adsorbent than is possible with a three-section cascade. The system is similar to that of threesection SMB except that all columns are connected in series with no isolated purge column. The cascade is divided into four sections; section I between desorbent inlet and extract withdrawal, section II between extract and feed, section III between the feed and the raffinate withdrawal and section IV between raffinate and desorbent recirculation point. As in the three-section SMB system, by advancing the desorbent, extract, feed, raffinate and recirculation points at specified time intervals simulates counter-current flow by one column in the direction of the fluid flow. The basic features of the design and operation of such a system are discussed here with reference to the fructose-glucose separation. 5

9 Figure (1.2) Simulated counter-current system of valves and column elements showing arrangement for operation as four-section separation process[3]. In order to achieve separation of the feed components (F and G) in a system with an equilibrium selective adsorbent, if K F > K G it is necessary to fulfil the following flow conditions: Section IV γ F > 1.0, γ G > 1.0 Section III γ F > 1.0, γ G < 1.0 Section II γ F > 1.0, γ G < 1.0 Section I γ F < 1.0, γ G < 1.0 If one elects to satisfy all these constraints by the same margins (α > 1.0) this set of inequalities translates directly into a set of four simultaneous equations which define the flow ratios throughout the system: 6

10 Section IV (D-E+F-R)/S = K G /α (1.1) Section III (D-E+F)/S = K F /α (1.2) Section II (D-E)/S = K G /α (1.3) Section I D/S = K F α (1.4) It is evident that there is a trade-off between the number of stages and the desorbent flow rates since reducing the flow rate ratio (L/S) reduces the driving force for mass transfer and thus increasing the height of the column. Under the limiting condition of α near one, with an infinite number of stages, the extract and raffinate product concentrations may approach but can never exceed the concentration of the relevant components in the feed. This will always be true for an isothermal linear, uncoupled system. 7

11 Chapter Two Modelling of SMB adsorption column The problem of modeling the SMB process has attracted a great deal of attention of researchers. Different approaches have been used to simulate this process. These approaches are classified according whether the system is simulated directly or represented in terms of an equivalent true counter current system and whether the system is represented as a continuos flow or as a cascade of mixing cells [4]. The most widely used model to simulate the SMB process is called the equivalent counter-current model; this model is discussed in more details below Equivalent counter-current model Assuming plug flow of the solid and axially dispersed plug flow of the fluid, Ching et al. [4] have derived the following differential equation which describes the system dynamics, see Figure (2.1): Sq z+dz dz z Lc Figure (2.1): Differential element on the packed adsorbent 8

12 D L 2 c c 1 ε q c 1 ε q υ + ( ) u = + ( ) (2.1) 2 z z ε z t ε t Where, D L is the axial dispersion coefficient, c and q are liquid and solid phases concentrations respectively, υ and u are liquid and solid phases velocities respectively and ε is the bed porosity. The solid and liquid velocities can be estimated using the following equations: S u = (2.2) ( 1 ε ) A c L υ = (2.3) ε A c V S = (2.4) τ Where, S and L are solid and liquid flow rates respectively, V is column volume andτ is switch time. If a linear equilibrium relationship (q * = Kc) and a linear driving force mass transfer rate expression are assumed, at steady state [4]: dq dt dq = k( q * q) = k( Kc q) = u (2.5) dz Then eq. (2.1) becomes: D L d dz 2 2 dc 1 ε υ ( ) k( Kc q) = 0 (2.6) dz ε A steady state material balance between a plane z in the column and the inlet yields: ( o o 1 ε ) u( q q ) = ευ( c c ) (2.7) 9

13 Substitution of this mass balance into the differential equation for the column and applying Dankwerts boundary condition at the column fluid entrance (z = 0) and zero change of concentration flux at the column exit (z = L) leads to a formal solution for the concentration profile given by Ching et al. [4]. When the mass transfer resistance is negligible and dispersed flow prevails, the following equation gives the concentration at the outlet of each section as a function of inlet concentration [4]: c c o qo = ((1 ( γ 1) Kc 1 pe(1 γ ) o ) γe γq + Kc o o 1) (2.8) Ching et al. have shown that Pe number could be evaluated from the chromatographic velocity using [5]: Pe = νl/5(u + ν), where D L = νl/d L (2.9) Where the Peclet number Pe = νl/d L, γ = (1-ε)Ku/εν and L is the column height. For a four column counter current adsorptive fractionating column there are four such equations. In conjunction with four mass balances over each section and two additional mass balances at the feed point and over the fluid recircuilating stream. This gives ten equations that define the system and enable the evaluation of the ten unknowns (q o, q I, q II, q III, c o, c I, c II, c III, c IV, c - II ). 10

14 Chapter Three Characteristics of Adsorbents and Modeling Results 3.1 Ca 2+ Exchanged ion exchange Ca 2+ polystyrene resin is one of the most widely used adsorbent (fructose selective) in the separation of fructose-glucose mixtures for the production of high fructose syrup. The adsorption isotherms of fructose and glucose on Doulite C204 resin (Ca 2+ form) can be assumed linear and uncoupled (Ching et al. 87) with equilibrium constants equal at 30 o C to 0.88 and 0.5, respectively [8]. This resin has a particle diameter of 10 µm and gives a bed porosity of 0.4. Further properties of this resin can be supplied the manufacturer. In order to simulate the behavior of the SMB the mathematical model developed in chapter two has been used with α = 1.1. The flow rates of the solid and liquid in each section have been evaluated using equations (1.1) (1.4). Table (3.1) shows the flow rates in each section. After substituting the constants on the mathematical model, 10 algebraic equations have been generated, solution of these equation has been done using MathCad program, see appendix one. Figure (3.1) shows fructose and glucose recoveries as a function of volume, while Figure (3.2) shows typical concentration profile of fructose-glucose mixture over Doulite C204 resin. 11

15 Table (3.1): Liquid and solid flow rates at each section. F = 8.314(L/min), E = 13.97(L/min), R = 11.47(L/min) and S = 33.25(L/min). Section Liquid flow Solid flow Solid velocity Liquid γ F γ G Pe rate(l/min) rate (L/min) (cm/min) velocity (cm/min) I II III IV Percentage recovery Fructose recovery Glucose recovery Column volume(m^3) Figure (3.1): Recoveries of fructose and glucose as a function of bed volume, T = 30 o C. 12

16 Concentration (g/l) Cf Cg Section Figure (3.2): Concentration profile of fructose- glucose mixture over Ca 2+ resin. (1,1,1,1) configuration. The recoveries of fructose and glucose are not function of bed volume only, but also function of the configuration of the bed (number of columns in each section). Table (3.2) gives fructose and glucose recoveries for different column arrangements. Table (3.2): Fructose and glucose recoveries for different columns arrangement A c = 0.68m 2, T = 30 o C, τ = 30.5 min, individual column height = 1.5 m. Configuration Packing height (m) Fructose recovery (%) Glucose recovery (%) 1,1,1, ,1,1, ,1,2, ,2,1, ,1,1, ,2,2, One of the crucial parameters that determine the efficiency of the adsorption column is the amount of energy needed to regenerate the solvent (water on this system). Table (3.3) shows the energy needed to evaporate water in order to have 25 wt % of sugar (fructose and glucose) in the product streams. 13

17 Table (3.3): Heat needed to regenerate the solvent as a function of columns configuration Individual column height = 1.5 m Configuration Energy needed to Energy needed to Total energy needed concentrate the raffinate concentrate the extract (kw) (kw) (kw) 1,1,1, ,1,1, ,1,2, ,2,1, ,1,1, ,2,2, Non-polar dealuminated faujasite zeolite The chromatographic separation of carbohydrates on zeolite was established on the industrial scale for more than 10 years [15]. The sugar interacts with zeolite by the complexation of the multivalent counterions on acidic zeolite sites [16]. Some recent studies showed that the chromatographic separation of the monosacariedes could be improved by using Y-zeolite containing less aluminum [17]. The hydrophobicity increases because of the reduction of the ionic sites, this is important since the carbohydrate molecule consists of hydrophobic and hydrophilic regions [18]. This interaction of ionic sites with the counterion of the fructose may describe why fructose is enriched in the zeolite pores while glucose is excluded. [18] The silica to aluminum ratio is increased during the dealumination procedure, leading to changes in the structure of zeolite. The FAU (Si/Al = 110, Na + form) zeolite used in the experimentation of C. Buttersack et al was produced with SiCl 4 treatment, Figure 3.3. [19]. 14

18 Figure 3.3. FAU zeolite framework. The crystal diameter of FAU zeolite is 6 µm, with a porosity of The absolute adsorption equilibrium constant was calculated by K = K E + e where e (FAU: e = ml/g) is the specific pore volume [19]. According to this relation the adsorption equilibrium constants at 25 C for glucose is ml/g and for fructose is ml/g [20]. The particle density (0.85 g/ml) of zeolite multiplied by the adsorption constant [21] gives a dimensionless adsorption constant for glucose (0.44) and fructose (1.12), respectively. The FAU zeolite adsorbent were evaluated according to a numerical simulation (Chapter 2) to determine the effect of the adsorbent on the purity, recovery and heat needed to regenerate the solvent to obtain 25 wt. % sugars. The liquid and solid flowrates of each section are given in 15

19 Table (3.4) : Liquid and solid flow rates at each section F = 8.314(L/min), E = (L/min), R = 9.59 (L/min) and S = (L/min) Section Liquid flow Solid flow Solid velocity Liquid γ F γ G Pe rate(l/min) rate (L/min) (cm/min) velocity (cm/min) I II III IV The recovery and purity of extract and raffinate respectively are represented in Figure 3.4 at different adsorbent volumes Fructose-Recovery E-Purity Glucose-Recovery R-Purity Volume adsorbent (m^3) Figure 3.4. Adsorbent effect on purity and recovery. The recovery in both the extract and raffinate of fructose and glucose tend to level after 92%. The purity of glucose increased from 0.86 to 0.92 corresponding to a 50% increase in adsorbent volume, while fructose increased from 0.83 to These values are further reflected in the heat required to concentrate the extract and raffinate to 25-wt% of Fructose and Glucose respectively, see Figure (3.5). This figure shows a definite decline in the heat required in extract (E-Q) and raffinate (R-Q) respectively, corresponding to the increase in concentration. 16

20 Heat for Vaporization (kw) Volume adsorbent (m^3) E-Q R-Q Figure 3.4. Adsorbent effect on vaporization heat required. The concentration profile at 90 % recovery of extract and raffinate is given in Figure 3.5. The extract (E) is withdrawn at column 4, feed (F) at column 7 and raffinate (R) at column C (g/l) Fructose Glucose Columns Figure 3.5. Concentration profile. 17

21 3.3 CaY zeolite A CaY synthetic zeolite (UOP Process) is widely used in the separation of fructoseglucose mixture due to its fructose selectivity. CaY zeolite is prepared from a standard NaY sample (Si/Al 2.2) by repeated ion exchange with CaCl 2. It has been shown that the CaX zeolite has no selectivity between fructose and glucose, where as the selectivity and capacity of the CaY zeolite is similar to the Ca 2+ resins [9]. Figure (3.6) shows a schematic of Y zeolite. The pore structure of Y zeolite is very open, the constructions being twelve-membered oxygen rings with free diameter ~ 7.5 A o. Molecules with diameters up to 8.5 A o can penetrate these channels with little steric hindrance. The nature of the cation can have a profound effect on the adsorption equilibria in these materials [10]. Figure 3.6. A schematic of CaY zeolite [2]. For the CaY zeolite, it has been shown that the equilibrium relationship remains essentially linear even up to relatively high concentrations (~50 % wt.) [10]. The dimensionless equilibrium constants of glucose and fructose at 29 o C are 0.38 and 0.78 respectively. This adsorbent has an average particle diameter of 1.5 mm with a bed voidage (porosity) of 0.41 [9]. 18

22 A MathCad program is used to simulate the model described in chapter two, see appendix three. The effect of the amount of used adsorbent on purity and recovery of extract and raffinate is shown in Figure (3.7). It is found that purity and recovery of both raffinate and extract are function of amount of adsorbent used and the columns configuration. 98 (%) Adsorbent Volume (m^3) Fructose-Recovery E-Purity Glucose-Recovery R-Purity Figure 3.7. Amount of adsorbent effect on extract and raffinate purity and recovery. For the system of configuration (4,3,3,2) a total volume of 4.24 m 3 adsorbent is needed. The concentration profile of this configuration is shown in Figure (3.8), while glucose and fructose at purity and recovery shown in Table (3.5). Table (3.5): Recovery and purity of the system configuration (4,3,3,2) Property Extract Raffinate Purity (%) Recovery (%)

23 C (g/l) C-G C-F Column Number Figure (3.8): Fructose and glucose concentration profiles Table (3.6) shows a summary of the flowrates and the parameters in each section of the system. In order to concentrate the fructose in extract and the glucose in the raffinate to a concentration equal to that of the feed (25 % wt.) about 235 kw is required. Table (3.6): Summary of the flowrates and parameters in each section of the system. F = 8.29 l/min, E = l/min, R = l/min and S = l/min. Section L S u v γ F γ G Pe (l/min) (l/min) (cm/min) (cm/min) I II III IV

24 3.4 Activated carbon Carbonaceous materials have been known for long time to provide adsorptive properties. Now, activated carbons are used widely in industrial applications, which include decolourizing sugar solutions, personnel protection, solvent recovery, volatile organic compound control, hydrogen purification, and water treatment. Activated carbons compromise elementary microcrystallites stacked in random orientation and are made by the thermal decomposition of various carbonaceous materials followed by an activation process. There are two types of activation processes, gas activation or chemical activation. The surface of an activated carbon adsorbent is essentially non-polar but surface oxidation may cause some slight polarity to occur. Surface oxidation can be created, if required, by heating in air around 300C o or by chemical treatment with nitric acid or hydrogen peroxide. In general, activated carbons are hydrophobic and organophilic and therefore they are used extensively for adsorbing compounds of low polarity in water treatment, decolourization, solvent recovery and air purification applications. Till now there are no published information about activated carbon as an adsorbent in the separation of fructose-glucose mixture. This may be due to the complications arising from nonlinearity of the equilibrium isotherms of this system or due to low selectivity at high concentration The equilibrium isotherms for glucose and fructose have been studied by Abe et al.[1] at a temperature of 25 C o, they determined the Freundlich s adsorption constants of glucose and fructose from aqueous solutions onto an activated carbon at low concentrations (up to 600 mg/l). It was found that glucose is the more strongly adsorbed than fructose. The adsorption isotherms were approximated by the Fruendlich equation and it was found that for glucose, the relation between the equilibrium concentration (mg/l) and the amount adsorbed (mg/g) could be represented by: 21

25 q G =0.1851c (3.1) And that of fructose: q F = c (3.2) These relations can t be used in the model described in chapter two, so linearization of these isotherms have been done, the linearized forms of these equations are given in the next two relations: q G = 32.5c (3.3) q F = 21.75c (3.4) Where c is the equilibrium concentration (g/l) and q is the amount adsorbed (g/l adsorbent), based on particle density of 700 kg/m 3 [2]. The mathematical model derived in chapter two has been applied and simulated (using K F of 32.5,K G of and α of 1.1. To study the effects of the amount of adsorbent and the configurations of the columns on the purity, recovery and heat duty required to concentrate the output extract (glucose-rich) and raffinate (fructose-rich) to 25 wt%. Mass balance results model parameters for each section are shown in Table (3.7): Table (3.7) Mass balance results, and model parameters at a feed of 8.3 L/min and cross sectional area of the bed of 0.78 m 2. Section Liquid flow Solid flow Solid Liquid γ F γ G Pe rate(l/min) rate (L/min) velocity (cm/min) velocity (cm/min) I II III IV

26 Figure (3.9) represents the concentration profiles for one of the configurations at which 92% purity of extract and raffinate can be achieved Concentration (g/l) Fructose Glucose Number of columns Figure (3.9) The concentration profiles at 92% purity of extract and raffinate with 91% recovery of extract and 93% recovery of raffinate. The recovery and the purity of both extract and raffinate can be improved by increasing the amount of adsorbent in each column and by changing the configurations. Recovery and impurity of 97% can be achieved using m 3 activated carbon. Table (3.8) contains recovery and purity of glucose and fructose at several amounts of adsorbent. Table (3.8) Purity and recovery of extract and raffinate at different amount of adsorbent. Extract Purity Raffinate Purity Recovery of G in extract Recovery of F in raffinate Volume of adsorbent (m 3 ) It is noticed that the amount of heat required for concentrating sugar is constant for the same adsorbent and adsorption conditions, which is about 555 kw in this case. Figure (3.10) explains the effect of amount of adsorbent on the purity of glucose and fructose. 23

27 Purity Extract purity Raffinate purity Amount of adsorbent (m 3 ) Figure (3.10): The effects of amount of adsorbent on the purity of extract and raffinate. 3.5 Adsorbents behaviour comparison Table (3.9) compares the performance of the used adsorbents in terms of purity, recovery, volume of adsorbent and energy required for the water recovery system. It is shown that dealuminated FAU zeolite and activated carbon give the minimum volume while the CaY zeolite gives the higher volume. If both recovery and energy requirement are considered as comparison criteria, then the FAU zeolite is the most efficient adsorbent for fructose-glucose separation. If results reliability is considered, activated carbon is the least. The results of activated carbon have been generated using K values valid at low concentrations. 24

28 Table (3.9): Comparison of the behavior of the four adsorbents Adsorbent Type Fructose Recovery (%) Glucose Recovery (%) Adsorbent Volume (m 3 ) Energy Consumption (kw) Ca 2+ exchanged ion exchanger Non-polar dealuminated FAU zeolite CaY zeolite Activated carbon

29 Chapter Four Conclusions and Recommendations 4.1 Conclusions The adsorbent that gives the minimum adsorbent volume are ranked in the following order: Non-polar dealuminated FAU zeolite > activated carbon > Ca 2+ exchanged ion exchanger > CaY zeolite The adsorbent that gives the minimum energy requirement are ranked in the following order: Non-polar dealuminated FAU zeolite > CaY zeolite > Ca 2+ exchanged ion exchanger > Activated carbon. Activated carbon cannot be compared to the others due to non-linearity of adsorption isotherms and extrapolation to high concentration. SMB technology can be used to separate fructose-glucose aqueous mixtures up to high purity. Column configuration plays a basic rule on the degree of separation. The higher the ratio between the equilibrium constants of the solutes, the better separation that could be achieved. 4.2 Recommendations Further efforts have to be done to study the adsorption isotherms of fructose-glucose mixture over activated carbon at high concentrations. For the lowest amount of adsorbent and energy consumption; non-polar dealuminated FAU zeolite is recommended to be used. In order to have more reliable results, mass transfer resistance should be taken into account. Further studies have to be done on FAU zeolite adsorbent for fructose-glucose separation. 26

30 References 1. G. Dunnebier, I. Weirich and K. U. Klatt, Chemical Engineering Science, 1998, 53 (14), , 2. Barry Crittenden and W. John Thomas, Adsorption Technology and Design, Butterworth- Heinemann, Douglas M.Ruthven and C. B. Ching, Counter-Current and Simulated Counter-Current Adsorption Separation Processes, Chemical Engineering Science, 44(5), D. Ruthven and C. Ching, Chemical Engineering Science, 1989, 44, D. Ruthven and C. Ching, Chemical Engineering Science, 1985, 40, C. Ching, D. Ruthven and K. Hidajat, Chemical Engineering Science, 1985, 40, C. Ching and D. Ruthven, Chemical Engineering Science, 1986, 41, C. Ching, C. Ho and K. Hidajat, Chemical Engineering Science, 1987, 42, Cecilia Ho, et al., Ind. Eng. Chem. Res. 1987,26, K. Hashimoto, et al., J. Chem. Eng. Jpn. 1983,16, Julius Scherzer, Octane-Enhancing Zeolitic FCC Catalysts: Scientific and Technical aspects, 1990, Marcel Dekker Inc.: New York and Basel. 12. R. A., Le Febre, High-Silica Zeolites and their Use as Catalyst in Organic Chemistry, Ph. D. Thesis,1989, the Netherlands. 13. Abe and K. Hayashi, Adsorption of Saccharides Aqueous Solution onto Activated Carbon, Caron, 21(3) Barry Crittenden and W. John Thomas, Adsorption Technology and Design, Butterworth- Heinemann, Johnson, J.A.; Oroskar, A.R. Stud. Surf. Sci. Catal. 1989, 46, Sherman, J.D.; Chao, C.C. Stud. Surf. Catal. 1986, 28, Kulprathiapanja, S. U.S. Patent 5,000, Yano, Y.; Tanaka, K.; Doi, Y.; Janado, M. J. Solution Chem. 1988, 17, Buttersack, C., Wach W. & Buchholz K., J. Phys. Chem. 1993, 97,

31 20. Buttersack, C., Fornefett I., Mahrholtz J. & Buchholz K. Progress in Zeolite and Micropous Materials, 1997, 105, Yang H., Ping Z., Niu G., Jiang H. & Long Y., Langmuir 1997, 13, Lin Y.S. & Ma Y.H., Stud Surf. Sci. Catal. 1989, 84,

32 Nomenclature Symbol Definition Unit A Cross-sectional area of the column m2 c Fluid phase concentration of sorbate g/l c o Value of c at z = 0 g/l D Desorbent flow rate l/min D L Axial dispersion coefficient - E Extract flow rate l/min F Feed flow rate l/min K Adsorption equilibrium constant based on particle volume l/min l Length (of individual column of section) m L Liquid flow rate l/min q Sorbate concentration in adsorbed phase (particle volume basis) g/l S Hypothetical adsorbent recirculation rate in equivalent countercurrent l/min system u Hypothetical solid velocity m/min v Hypothetical liquid intestitial velocity in counter-current model m/min z Distance measured from bed inlet m Z z/l fractional distance - Pe vl/d L - Separation factor - γ (1-ε )Ku/ εv - ε Bed voidage - τ Switch time min 29

33 Appendix one x.01 y.5 z 1 t.8 i.1 l.5 f.8 r.9 m 2.5 n.9 given l i. 1 1 x.88. i x i f l y 1 l y.88. l r 10. m. 1 1 z.88. m z m n r t 1 r t.88. r y x.97.( l i) z y.55.( f l) m f t z ( r m) x t.454.( n r) i n rev find( x, y, z, t, i, l, f, r, m, n) rev = Mathcad program to solve for Fructose concentration across the SMB column for Ca 2+ (2,2,1,1, configuration) adsorbent, the table gives the result of this simulation. 30

34 Appendix two 2.1. Fructose x :=.01 y :=.5 z:= 1 t :=.8 i :=.1 l :=.5 f :=.8 r :=.9 p := 2.5 n :=.9 Given x l i i x i f l y 1 l + y 1.12 l z r p p z p n r t r + 1 t 1.12 r

35 2.2. Glucose x :=.01 y :=.5 z:= 1 t :=.8 i :=.1 l :=.5 f :=.8 r :=.9 p := 2.5 n :=.9 Given x l i i x i f l y 1 l + y.44 l z r p p z p n r t r + 1 t.44 r

36 y x l ( i) z y f ( l) f p t z r ( p) x t n ( r) n i rev := Find( x, y, z, t, i, l, f, r, p, n) q0 q1 q2 rev = co c1 c2 c3 ( c2) q c4 33

37 Appendix three MOLECULAR SEPARATION CaY SMB MODEL * Definition of Symbols: Conentration of sugar in adsorbent and solvent (g/l): Co = a, C1 = b, C2 = c, C2' = d, C3 = e, C4 = f, qo = j, q1 = h, q2 = i, q3 = g Input and Output flow rates (l/min): feed := 8.29 S := D := R := E := System Configuration: (4,3,3,2) Length of Section (cm) L1=180 L2=135 L3=135 L4=90 Col Diam=100 cm Col Length = 45 cm Total volume = 4.24 m^3 The system model consists of 10 equations and 10 unknowns 1- Modeling of Fructose KF=0.78 γ1 = 0.909, γ2 = 1.865, γ3 = 1.10, γ4 = 2.26 Initial Guess: a :=

38 b := 100 c := 100 d := 100 e := 100 f := 100 g := 100 h := 100 i := 100 j := 100 Given j b a j a a c b h h.78 b + b 1 0 i e 10d i.78 d + d 1 0 f e g g e e h j ( b a) i h ( c b) g i +.709( e d) j g ( f e) d f.59 c a Fructose modeling vec := Find( a, b, c, d, e, f, j, h, i, g)

39 vec = recovery := vec 1 recovery = (%) 2- Modeling of Glucose KG=0.38 γ1=0.443, γ2=.909, γ3=.536, γ4=1.101 Initial Guess: a := 100 b := 120 c := 200 d := 100 e := 100 f := 100 j := 100 h := 100 i := 100 g :=.008 Given b a j j a a h c b h.38 b + b

40 i e d i.38 d + d 1 0 g f e g e e h j ( b a) i h ( c b) g i +.709( e d) j g ( f e) d f.59 c a vec := Find( a, b, c, d, e, f, j, h, i, g) vec = recovery :=.4061 vec 4 recovery = (%)

41 38