Derivation of the equations for the new binary-mixture ECP method from the

Appendix 169

B. Derivation of the equations for the new binary-mixture ECP method from

170 Appendix

In the previous equations b1 and b2 are Langmuir isotherm parameters, t0 column hold-up time, tinj injection time and α2,1 = H2/H1 the selectivity (eq. (2.37)). Without going into detailed derivations (which are given e.g. in [11, 87]) the expressions for the used parameters r₁, γ and L_f,2 are briefly presented here. The parameter r₁ is the positive root of the following equation:

 

2

2,1 1 2b c^feedr1,2 2,1 1 2,1 1 1b c^feed b c2 2^feed r1,2 b c2 1^feed 0

        (A.27)

The two roots of this equation, r_1,2, can be therefore calculated as:



^{2,1 2,1 1 1 2 2}

 

^{2,1 2,1 1 1 2 2}



^{2 2,1 1 2 2 1}

1,2

2,1 1 2

1 1 4

2

feed feed feed feed feed feed

feed

b c b c b c b c b c b c

r b c

    



       

 (A.28)

The variable γ is expressed as a function of isotherm parameters and the already defined r1:

2,1 1 1 2

1 1 2

b r b b r b

  ^

 (A.29)

L_f,2 represents the loading factor calculated for the single second component:

2 2

,2 0

,2 0

feed inj f

R

b c t L  t t

 (A.30)

The times t_R⁰₁ and t⁰_R2 are retention times under linear conditions for components 1 and 2, and can be derived from the equation for Henry constant given in section 2.4 (eq. (2.36) and (2.1)), by taking into account the definition of phase ratio, F (eq. (2.7)):

 

0

,1 0 1 1

tR t H F (A.31)

 

0

,2 0 1 2

tR t H F (A.32)

By taking all the previous expressions, the equations that describe the ideal elution profile in the form t = f(c) can be derived.

From the equation (A.23) by implementing the definitions of the parameters t⁰_R1, Lf,2 and α2,1

we get the following expression for the retention time of the component 1 in the zone I (denoted as tR^I,1

 

c1 ):

Appendix 171

 

 

   

I

,1 1 0

2 1

2 2 2 1

0 1 0 2 2

0 2 0

1 1 2 1

1 1

2 1

1 1 1

1 1 1

R inj

feed inj

t c t t

H H

b c t H H

t H F t

t H F t

b c H H

H H b c

  

  

 

 

             

(A.33)

which after additional rearrangements becomes:

   

 

2 2 2 1

I

,1 1 0 0 1 2 2

1 1 2 2 1

0 2 1 1

2

1 1

feed inj

R inj

b c t H H

t c t t t H F

b c H H

t H F b c

H

 

 

  

          

(A.34)

The equation (A.34) represents the form that can be used for the binary-mixture ECP method and is repeated in Chapter 3 as eq. (3.8). When the retention time of the second arc of the component 1 (tR^II,1

 

c1 ), in the zone II, is expressed as a function of the concentration (c1) from eq. (A.24), we get the following:

 

^{0,1 0}

II

,1 1 0 2

2,1 2

1 1

2,1 1

1

R

R inj

t t

t c t t

c b b

r



 

   

  

 

  

  

 

(A.35)

By implementing the definitions of the parameters t_R⁰_,1, α2,1 and γ, we get the next equation (for the sake of simplicity the expression for r1 was not introduced here, as well as later in the equation for component 2 in the zone II):

   

   

0 1 0

II

,1 1 0 2

2 1 2

1 1

2 1 1 1 2 2 1 1

1 1 2

1 1

R inj

t H F t

t c t t

H H b

c b

H H b r b H H r

b r b

 

  

  

 

  

   



(A.36)

The final equation (equal to eq. (3.9) in Chapter 3) is:

 

 

1 2

0 1 1 1

2 II

,1 1 0 2

1 2 1

1 1 2 1 1

1 2

1

R inj

t H F b r H b t c t t H

H b c b r b b c

r H

  

 

 

  

 

    

 

(A.37)

172 Appendix

For the second component the expressions are derived in the same way. The retention time of the first arc, in the zone II (tR^II,2

 

c2 ) resulting from eq. (A.25) is:

   

 

0

,2 0

II

,2 2 0 2

2 2 2,1 1 2 1

1

R

R inj

t t

t c t t

b c b c r





   

  (A.38)

By introducing the expressions for γ, t_R⁰_,2 and α2,1, this equation becomes:

 



^{2 1}



^{1 1 2} 0



2



0

II 1 1 2

,2 2 0 2

2 1 2 1 2 2

1

1

1

R inj

H H b r b

t H F t

b r b

t c t t

H b c r

b c H

    

   

 

 

 

 

(A.39)

 

 

1 1 2

0 2 2

1 II

,2 2 0 2

2 1 2 1

1 1 2 2 2

1

1

R inj

b r H

t H F b

t c t t H

H b c r b r b b c

H

 

  

 

  

 

    

 

(A.40)

The previous equation is the final expression for tR^II,2

 

c2 and is equal to eq. (3.10). The time function of the component 2 in the zone III (tR^III,2

 

c2 ), derived from eq. (A.26) is:

   

0

,2 0

III

,2 2 0 2

1 2 2 R

R inj

t t

t c t t

b c

   

 ^(A.41)

With the definition of t_R⁰_,2 the next equations are obtained:

   

 

0 2 0

III

,2 2 0 2

2 2

1

R inj 1

t H F t

t c t t

b c

 

  

 ^(A.42)

   

III 0 2

,2 2 0 2

1 2 2

R inj

t H F

t c t t

b c

  

 (A.43)

The last expression is the one used for the binary-mixture ECP for determining the adsorption isotherm of the second component. This equation is shown also in Chapter 3 as eq. (3.11).

List of symbols

Latin symbols

A Parameter in the van Deemter equation that shows the eddy diffusion contribution

ap External surface area of the particles

B Parameter in the van Deemter equation that shows the effects of longitudinal diffusion

b Langmuir isotherm parameter which depends on the adsorption energy

b₀ Constant parameter in the Langmuir isotherm model, when parameter b depends on temperature

C Total concentration

c Concentration in the mobile phase

C Parameter in the van Deemter equation that shows the mass transfer kinetics c⁰ Initial concentration

C_A,1 Concentration of the first component on the front side of the second shock in the analytical solution of the ideal model of chromatography

CB,2 Concentration of the component 2 plateau in the analytical solution of the ideal model of chromatography

c^calc Calculated concentration

c^eq Equilibrium concentration in the mobile phase (Frontal analysis) c^exp Experimental concentration

CF Calibration factor c_feed Feed concentration

c^init Initial concentration in the mobile phase (Frontal analysis)

C_M,1 Maximum concentration of the component 1 in the analytical solution of the ideal model of chromatography

C_M,2 Maximum concentration of the second component in the analytical solution of the ideal model of chromatography

CM’,1 Concentration of the first component on the rear side of the second shock in the analytical solution of the ideal model of chromatography

cmax Maximal mobile phase concentration of a peak cp Stagnant mobile phase concentration

C_pg Gas heat capacity

Cps Solid (adsorbent) heat capacity d Column inner diameter

Dapp Apparent dispersion coefficient

174 List of symbols

Deff Effective diffusion coefficient in porous media DL Axial dispersion coefficient

Dmol Molecular diffusion coefficient d_p Particle diameter

Dp Pore diffusion coefficient Ds Surface diffusion coefficient ee Enantiomeric excess

F Phase ratio

H Henry constant

ΔH Isosteric heat of adsorption h Overall heat transfer coefficient HEPT Height equivalent to a theoretical plate i Solute i = 1,2,…, n

j James-Martin compressibility factor J Diffusion flux

ke Mass transfer coefficient from fluid to particle KL Thermal dispersion coefficient

km Mass transfer resistance

L Column length

L(test) Length of the test capture column

Lf,2 Loading factor calculated for the single second component M Molar mass of the solute (in kg/mol)

m_ads Adsorbent mass m_coll Collected mass m_feed Feed mass

m_z Dimensionless flowrate ratios (m_z) for each SMB zone (z = I, II, II, IV) n Number of components

ncycles Number of cycles

nelut Number of the elution profiles ni Amount of a component (i) ninj Number of injections

ninj(test) Number of injections that can be “parked” into a test capture column np Number of points

NTP Number of theoretical plates (NTP) OF Objective function

Pads Adsorption step pressure (high pressure in the pressure swing adsorption process) Pdes Desorption step pressure (low pressure in the pressure swing adsorption process)

List of symbols 175

Pdrop Pressure drop

Pi Partial pressure of a component (i) Pin Inlet pressure

P_out Outlet pressure

PR Normalized productivity, given as amount per cycle time and adsorbent volume PR* Productivity given as amount per cycle time

PU Purity

Q Volumetric flowrate

q* Equilibrium concentration in the stationary phase

q₀ Saturation capacity of the stationary phase (Langmuir isotherm parameter)

Q_eluent Flowrate in the eluent stream

q^eq Equilibrium concentration in the stationary phase (Frontal analysis) Qextract Flowrate in the extract stream

Qfeed Flowrate in the feed stream

q^init Initial concentration in the stationary phase (Frontal analysis) QI-QIV Flowrates in the zones I-IV of SMB

Qm Mass flowrate

qmax Stationary phase concentration in equilibrium with the maximal mobile phase concentration of a peak

Qraffinate Flowrate in the raffinate stream

Qsolid Virtual solid phase flow in SMB

r Radial coordinate R Universal gas constant

r1,2 Variable used in the analytical solution of the ideal model of chromatography Rb Column (bed) radius

RE Recovery or yield Rp Particle radius

T Temperature

t Time coordinate

Δt Interval between the ending and starting cut time

t₀ Column hold-up time (dead time) i.e. the retention time of a non-adsorbing species

Δt0 Hold-up time of the section of the column required for one injection t_ads Adsorption step time

tads-s,1 Time when the first component start eluting during the adsorption step of a PSA

process

tads-s,2 Time when the second component start eluting during the adsorption step of a PSA process

176 List of symbols

tB End of the component 2 concentration plateau in the analytical solution of the ideal model of chromatography

tblow Blowdown step time tBT Breakthrough time t^calc Calculated time

tcycle Cycle time

Tdes Desorption temperature t_des Desorption step time

tdes-e,1 Time when the first component completely leaves the column during the

desorption step of a PSA process

tdes-e,2 Time when the second component completely leaves the column during the desorption step of a PSA process

tdiff Duration of the diffusion process

te,1 End of the first component band, ending cut time of the component 1 (complete elution of the component 1)

t_e,2 End of the second component band, ending cut time of the component 2 (complete elution of the component 2)

t^exp Experimentally measured time T_feed Feed temperature

t_inj Injection time

tpress Pressurization step time

tR Retention time

0

tR Retention time under linear conditions

tR,1 Retention time of the first shock in the analytical solution of the ideal model of chromatography

 

I ,1 1

tR c Retention time function for the first component in the zone I of the elution profile for the analytical solution of the ideal model of chromatography

 

II ,1 1

tR c Retention time function for the first component in the zone II of the elution profile for the analytical solution of the ideal model of chromatography

t_R,2 Retention time of the second shock in the analytical solution of the ideal model of chromatography

 

II ,2 2

tR c Retention time function for the second component in the zone II of the elution profile for the analytical solution of the ideal model of chromatography

 

III ,2 2

tR c Retention time function for the second component in the zone III of the elution profile for the analytical solution of the ideal model of chromatography

ts,1 Starting cut time of the component 1 (start of the elution of component 1) ts,2 Starting cut time of the component 2 (start of the elution of component 2)

tshift Time between port shifts in SMB

tstep Step time (duration of a step in the process) Twall Column wall temperature

List of symbols 177

u Interstitial linear mobile phase velocity u0 Superficial mobile phase velocity udes Desorption velocity

u_feed Feed velocity

V Column total volume

V₀ Total void volume of the column, available for the fluid phase Vads Adsorbent volume

V_f Total void volume of the column, available for the fluid phase V_feed Feed volume

V_g Gaseous mixture volume

ΔVid Volume of the column segment needed for storing one injection for the ideal case including only convection and no molecular diffusion

V_inj Injected volume V_p Total particle volume V_pore Total pore volume VR Retention volume

Vs Volume of the solid phase w1/2 Peak width at its half-height

Δxdiff Additional width on each side of the peak due to molecular diffusion

Δxdiff,end Additional peak-width due to molecular diffusion behind the firstly "parked"

injection (in the capture column)

Δxid Length of the column segment needed for storing one injection for the ideal case including only convection and no molecular diffusion

ΔxMTZ Width of the mass transfer zone due to molecular diffusion

Δx_real Length of the column segment needed for storing one injection for the real case including convection and molecular diffusion

y Mole fraction

ydes Mole fraction in the desorption mixture y_feed Mole fraction in the feed

z Space coordinate

Greek symbols

α Separation factor (selectivity)

γ Variable used in the analytical solution of the ideal model of chromatography ε Total column porosity

εe External porosity

178 List of symbols

εi Internal porosity εp Particle porosity μg Gas viscosity

ρ_b Bed density

ρg Bulk gas density ρp Particle density τ Tortuosity factor

Subscripts

Superscripts

cap Capture column

GC Corrected parameters used in the gas chromatography sep Separation column

Abbreviations

CD Cyclodexrin

ECP Elution by characteristic point

EDM Equilibrium-dispersive model of chromatography GC Gas chromatography

GRM General rate model of chromatography HPLC High performance liquid chromatography IM Ideal model of chromatography

LC Liquid chromatography LDF Linear driving force model ads Adsorption

des Desorption

l Larger column

R R-enantiomer

S S-enantiomer

s Smaller column

List of symbols 179

PSA Pressure swing adsorption

PVSA Pressure-vacuum swing adsorption SFC Supercritical fluid chromatography SMB Simulated moving bed

TDM Transport-dispersive model of chromatography TTBB 1,3,5-tri-tert-butylbenzene

VSA Vacuum swing adsorption

List of Tables

Table 2.1. Different models used for describing a chromatographic process with the effects that they take into account. ... 15 Table 2.2. Characteristics of the most commonly used methods for determination of adsorption

isotherms. ... 23 Table 2.3. An example of boundary conditions for the 4-step PSA shown in Figure 2.13. Here

pressurization is applied to the feed mixture of the same content as in the adsorption step. ... 40 Table 5.1. Some of the chemical and physical properties of bicalutamide. ... 74 Table 5.2. Some of the chemical and physical properties of isoflurane and desflurane. ... 76 Table 5.3. Overview of the previous publications on enantioseparation of the fluorinated

anaesthetics: The used separation processes are listed followed by indications if experiments, modelling and simulations were performed (the sign “” stands for the performed actions and “-“ for the non-performed ones). ... 79 Table 5.4. Selected characteristics of α-, β- and γ-cyclodextrins. ... 80 Table 5.5. Overview of the previous publications on enantioseparation of the fluorinated

anaesthetics: Applied stationary and mobile phases are shown. ... 81 Table 5.6. Overview of the previous publications on enantioseparation of the fluorinated

anaesthetics: Indicated if thermodynamic parameters and process performance characteristics were determined and calculated (the sign “” stands for the determined parameters and “-“ for the non-determined ones)... 84 Table 6.1. Experimental data for bicalutamide injections (S-enantiomer – component 1,

R-enantiomer – component 2). ... 88 Table 6.2. Experimental data for isoflurane and desflurane injections provided from SPP1570

Subproject II [14]. ... 93 Table 6.3. Calculated parameters for isoflurane and desflurane (S-enantiomer – component 1

and R-enantiomer – component 2) using the small injection amounts, based on mean retention times. ... 94 Table 7.1. Data used for the simulation study to evaluate the binary-mixture ECP method.

These data do not originate from any experimental system and therefore the substances are denoted as hypothetical. ... 100 Table 7.2. Competitive Langmuir adsorption isotherm parameters of the hypothetic substances

(simulation study, NTP = 1500): Comparison of the original data used for the simulation and those determined by the binary-mixture ECP method using three different combinations of the larger data sequences, defined in the previous text. ... 103 Table 7.3. Competitive Langmuir adsorption isotherm parameters of the hypothetic substances

(simulation study, NTP = 1500): Comparison of the original data used for the simulation and those determined with the binary-mixture ECP method using three different combinations of the smaller data sequences, defined in the previous text. ... 104 Table 7.4. Competitive Langmuir adsorption isotherm parameters of the hypothetic substances

(simulation study): Comparison of the original data used for the simulation and those determined with the binary-mixture ECP method using elution profiles generated by simulations with different number of theoretical plates (NTP). ... 106 Table 7.5. Adsorption isotherm parameters of bicalutamide, isoflurane and desflurane

enantiomers determined using the binary-mixture ECP method. ... 108 Table 7.6. Competitive Langmuir adsorption isotherm (eq. (2.33)) parameters of bicalutamide

enantiomers at 25 ᵒC determined with the peak-fitting method. ... 111

182 List of Tables

Table 7.7. Competitive Langmuir adsorption isotherm parameters of isoflurane and desflurane enantiomers at 28 ᵒC determined by the peak-fitting method. ... 113 Table 8.1. Process performance characteristics (productivity - PR, recovery - RE and purity -

PU) of bicalutamide enantiomers (S-enantiomer – component 1 and R-enantiomer – component 2) for three typical cases: touching bands (recovery of both components is close to 100 % i.e. 1), when the maximal productivity of S- enantiomer is achieved and when the maximal productivity of R-enantiomer is achieved. ... 122 Table 8.2. Process performance characteristics (productivity - PR, recovery - RE and purity -

PU) of isoflurane enantiomers (S-enantiomer – component 1 and R-enantiomer – component 2) for three typical cases: touching bands (recovery of both components is close to 100 % i.e. 1), when the maximal productivity of S- enantiomer is achieved and when the maximal productivity of R-enantiomer is achieved. ... 126 Table 8.3. Process performance characteristics (productivity - PR, recovery - RE and purity -

PU) of desflurane enantiomers (S-enantiomer – component 1 and R-enantiomer – component 2) for three typical cases: touching bands (recovery of both components is close to 100 % i.e. 1), when the maximal productivity of S- enantiomer is achieved and when the maximal productivity of R-enantiomer is achieved. ... 126 Table 8.4. Comparison of process performance parameters of S- (component 1) and

R-enantiomer (component 2) of isoflurane achieved in this work (batch GC when maximal production of S-enantiomer was obtained) and the examples from the literature where the same chiral selector was used (three batch GC processes and one GC-SMB). The values for the case done in this thesis are extracted from Table 8.2. ... 130 Table 8.5. Comparison of process performance parameters of S- (component 1) and

R-enantiomer (component 2) of desflurane achieved in this work (batch GC when maximal production of S-enantiomer was obtained) and the example available in the literature (batch GC process). The values for the case done in this thesis are extracted from Table 8.3. ... 130 Table 8.6. Scale-up results for bicalutamide enantiomers obtained from eq. (4.17) and by

performing simulations with the data for the larger-scale columns. The operation and performance parameters are presented for the three examined column sizes (referred as small, intermediate and large). ... 132 Table 8.7. Scale-up results for isoflurane enantiomers obtained from eq. (4.17) and by

performing simulations with the data for the larger-scale columns. The operation and performance parameters are presented for the three examined column sizes (referred as small, intermediate and large). ... 133 Table 8.8. Scale-up results for desflurane enantiomers obtained from eq. (4.17) and by

performing simulations with the data for the larger-scale columns. The operation and performance parameters are presented for the three examined column sizes (referred as small, intermediate and large). ... 134 Table 8.9. Data of the scale-up validation procedure for isoflurane and desflurane (shown in

Figure 8.17 and Figure 8.18). Presented are the volumetric flowrates (Q) and injected volumes (Vinj) for the small column, while for the intermediate and large column the values, which are required according to the scale-up rule (eq. (4.17)), are compared to those applied in the experiments carried out in Subproject II. ... 136 Table 8.10. Parameters of the Langmuir adsorption isotherms of desflurane racemic mixture at

10 ᵒC on the non-selective controlled porous glass beads (prepared by the research groups of Prof. Enke, Leipzig University and Prof. Fröba, University of Hamburg) used as adsorbent in the capture columns (data obtained from the parallel SPP1570 Subproject II). ... 138 Table 8.11. Parameters of the capture columns required for storing at least one gram of

desflurane enantiomers: Calculated column length (L^cap), its volume (V^cap) and adsorbent amount (Vadscap

) together with the needed additional parameters (notation given in the text) for the three capture columns (I, II and III) used to collect desflurane fractions after

List of Tables 183

the separation process. The volumetric flowrate (160.7 ml/min) and the diameter (1.66 cm) of all the three columns is equal to those of the large separation column. The number of the cycles to be stored in each of the columns is 52. The cycle time is 11.7 min. ... 139 Table 8.12. The times when elution of the components starts during the adsorption step of the

PSA process (tads-s,1 and tads-s,2) and when the components exit the column during the desorption step (tdes-e,1 and tdes-e,2). The values are given as time intervals from the start of the corresponding step until elution (as explained in the text above). Flowrate is 541.5 ml/min for isoflurane and 160.7 ml/min for desflurane, temperature 28 ᵒC, high pressure 500 kPa. ... 141 Table 8.13. Parameters selected for the PSA simulations of the isoflurane and desflurane

enantioseparation. The other data are the same as for the batch GC systems (Table 6.2 and Table 6.3). ... 142 Table 8.14. Process performance characteristics for the 4-step PSA separation of isoflurane and

desflurane enantiomers at two different adsorption pressures. The other operating parameters are given in Table 8.13. The comparison of the PSA to the batch GC process with 1 microliter injection of racemic mixture is also presented... 147

List of Figures

Figure 1.1. Spatial representation of molecules of enantiomers: C - chiral centre (mostly carbon atom), 1,2,3,4 - different groups attached to the centre. ... 2 Figure 1.2. Determination of R- and S- configuration of enantiomers. The arrows around the

molecules show the direction of decreasing priority (from 1 to 3) of the groups attached to the chiral centre (C). ... 2 Figure 1.3. Some of the ways to produce single enantiomers (R and S represent single target

enantiomers, R2 and S2 are intermediate enantiomers, and X and Y include one or more starting non-chiral substance(s))... 3 Figure 1.4. Chromatographic separation of a binary mixture. At the column inlet the narrow

rectangular pulse of the mixture is injected resulting at the outlet in dispersed peaks of the two separated substances. ... 4 Figure 1.5. Schematic overview of the study presented in this thesis, including the investigated

substances and processes performed for their analysis and chromatographic separation. ... 8 Figure 2.1. A typical chromatogram of a binary mixture with marked retention times of both

components (tR1 – for the first eluting component and tR2 – for the second eluting component) and the dead time (t0). ... 12 Figure 2.2. Scheme of a chromatographic column with marked different volumes used for

defining porosity... 13 Figure 2.3. Van Deemter curve (denoted as Total curve) with effects of single terms used in van

Deemter equation (2.12). ... 14 Figure 2.4. Most typical shapes of adsorption isotherms. In the first figure the most often

encountered Langmuir-type isotherm is shown. ... 21 Figure 2.5. Adsorption step in frontal analysis. Adsorbed amount corresponds to the integral in

eq. (2.38). The term tBT represents the breakthrough time. ... 25 Figure 2.6. Typical curve recorded when applying perturbation method for single component

adsorption isotherm determination. ... 26 Figure 2.7. Example of column inlet (dashed line) and outlet (solid line) concentration change

analysed by nonlinear frequency response method in order to calculate the adsorption isotherm parameters. ... 26 Figure 2.8. Elution profiles for different feed concentrations used for determination of

adsorption isotherms with peak maxima method. ... 28 Figure 2.9. Process of isotherm parameter determination using peak-fitting method. The

diagram shows the large number of recorded iterations before reaching the shape of the original experimental peak. ... 28 Figure 2.10. Representation of a 4-zone SMB process with two columns in each zone and

marked direction of the mobile-phase flow. The dashed arrows show the discrete shifting of the port positions. ... 30 Figure 2.11. SMB triangle diagram with defined separation regions (where pure both

components, only pure raffinate, pure extract, or no pure substances can be collected) for linear isotherm range. H1 and H2 represent the Henry constants of the first and second eluting component, respectively, while mII and mIII are dimensionless flowrate ratios in the zones II and III, respectively. ... 31 Figure 2.12. Representation of pressure and temperature swing on the adsorption isotherm

diagram. P and T represent the pressure and the temperature, and the subscripts ads and

186 List of Figures

des stand for adsorption and desorption process. The asterisk (*) shows the value of the stationary phase concentration in equilibrium with the mobile phase pressure. ... 32 Figure 2.13. Demonstration of four steps (pressurization, adsorption or feed, blowdown or

depressurization and desorption or regeneration) for a 1-column PSA. The up- and down-arrows (↑ and ↓) show that the pressure is increasing or decreasing, respectively. The thin arrows at column inlet and outlet show the flow direction, while the thick ones represent the sequence of the process steps. ... 34 Figure 2.14. Pressure change in a 4-step PSA process. The increase and decrease of the pressure

in the pressurization and blowdown step are represented by simplifies linear functions. ... 34 Figure 2.15. Skarstrom cycle representation (1 and 2 in the inlet and outlet streams stand for the

first and second eluted component that are contained in the corresponding streams). ... 35 Figure 2.16. Example of a typical four-step VSA cycle for a process with one column. ... 36 Figure 2.17. PSA process showing the direction of z-coordinate (with marked z = 0 and z = L

positions). ... 41 Figure 3.1. Schematic representation of direct methods (simulation of a chromatogram by

knowing the adsorption isotherm) and inverse methods (estimation of adsorption isotherm from the recorded chromatogram). ... 44 Figure 3.2. An example of elution profile (one component, Langmuir-type isotherm) that can be

used for the elution by characteristic point method. ... 45 Figure 3.3. Schematic representation of the solution of the ideal model of chromatography for

pulse injection of a binary mixture with Langmuir isotherms. Three separation zones (I, II and III) explained in the previous text are marked. The symbols used for defining the specific concentration and time points are given in the upcoming paragraphs. ... 47 Figure 3.4. Elution profiles with indicated parts for which the analytical expressions –

equations (3.8)-(3.11) – are derived (in the form of time as a function of concentration) and marked segments that are used for application of the binary-mixture ECP method (dash-dotted-line ellipses): a) Ideal profile characteristic for the very efficient columns (with more than 10,000 theoretical plates); b) More realistic profile, typical for less efficient columns. ... 50 Figure 3.5. Three examples of binary-mixture elution profiles resulting from different injected

volumes: a) Very small injection amount, which provides almost complete separation of the components and gives the profile that could only be used for providing the single component information; b) Proper injection amount for determining the competitive isotherms of both components with peak-fitting method; c) Too large injection amount that cannot provide correct data for the first eluting component. ... 52 Figure 4.1. Trade-off between productivity, purity and recovery to provide the optimal process

performance. ... 56 Figure 4.2. Representation of a binary-mixture elution profile with defined cycle time and the

cut times (ts – starting cut time , and te – ending cut time), between which the pure substances (C. 1 – first and C. 2 – second eluted component) can be collected. ... 58 Figure 4.3. Representation of the scale-up procedure when the same column length (L) is kept

and the diameter (d) is increased. Accordingly, the volumetric flowrate through the column (Q) and the injected amount (mfeed) have to be increased as well. ... 60 Figure 4.4. Schematically presented complete coupled production unit. It consists of one

separation column and three capture columns for storing the three fractions resulting from the separation process. Here the inlet mixture is a racemate containing the E1 and E2 enantiomers. ... 63 Figure 4.5. Procedure of capturing the three fractions (pure component 1, mixed fraction and

pure component 2) which are resulting from the separation. For the separation column the outlet stream is presented, while for the capture columns I, II and III the inlet streams are depicted. The dash-dotted lines represent the cut times that separate the collected fractions

Im Dokument Contributions to develop enantioselective chromatographic processes (Seite 179-200)