N° d’ordre: 308-96 Annee 1996

ECOLE DU PETROLE ET DES MOTEURS

UNIVERSITE CLAUDE BERNARD (LYON I)

THESE

PRESENTEE A L’UNIVERSITE CLAUDE BERNARD (LYON I)POUR L'DETENTION DU DIPLOME DE

DOCTORAT DE L’UNTVERSITE CLAUDE BERNARD (LYON I)EN GENIE DES PROCEDES

PAR

LOH KONG MING

Master of Science — University of Manchester Institute of Science and Technology (UK) Speciality “Petrochemicals and Hydrocarbon Chemistry"

Sujet de la these:

RECEIVED

0CT *51998

ETUDE DE LA COMPETITION D’ADSORPTION ENTRE LES COMPOSES OXYGENES ET LES HYDROCARBURES

SUR LES TAMIS MOLECULAIRES

\S ^

Soutenue le 29 novembre 1996 devant la commission d’examen:

B. BERNAUER RapporteurD. CLAUSSE RapporteurM. GAILLARDC. JALLUT S. JULLIAN J. LIETO President

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N° d’ordre: 308-96 AnnSe 1996

ECOLE DU PETROLE UNIVERSITE CLAUDE BERNARDET DES MOTEURS (LYON I)

THESE

PRESENTEE A L’UNTVERSITE CLAUDE BERNARD (LYON I)POUR L’OBTENTION DU DIPLOME DE

DOCTORAT DE L’UNIVERSITE CLAUDE BERNARD (LYON I)EN GENIE DES PROCEDES

PAR

LOH KONG MING

Master of Science - University of Manchester Institute of Science and Technology (UK) Speciality "Petrochemicals and Hydrocarbon Chemistry’’

Sujet de la thkse:

ETUDE DE LA COMPETITION D’ADSORPTION ENTRE LES COMPOSES OXYGENES ET LES HYDROCARBURES

SUR LES TAMIS MOLECULAIRES

Soutenue le 29 novembre 1996 devant la commission d’examen:

B. BERNAUER RapporteurD. CLAUSSE RapporteurM. GAILLARDC. JALLUT S. JULUANJ. LIETO President

Distributeur exclusifEditions Technip, 27 rue Ginoux, 75737 PARIS CEDEX 15

ACKNOWLEDGEMENT

I wish to express my heartfelt thanks and appreciation to the following who had in one way or the other made this work possible.

• Professor J. Lieto from the University of Claude Bernard (Lyon I) who had consented to be the President of the Examination Committee.

• Professor D. Clausse, Dr. J.F. Gaillard, Dr. C. Jallut and Dr. S. Jullian who had kindly agreed to be members of the Examination Committee.

• Staff of Petronas Research and Scientific Services Sen. Bhd. (PRSS) for their contribution towards this project.

• MTBE (Malaysia) Sdn. Bhd. for their assistance and support in the successful completion of this project.

• Staff of Institut Frangais du Petrole (IFP), especially Mr. A. Rojey, Dr. A. Deschamps, Dr. S. Jullian (who was my co-supervisor), Dr. A. Methivier, Mr. B. Tavitian and Mr. A. Barrou which had provided facilities, expert advice and technical support during the course of the work.

• Mr. Mohamad Nor Hashim, a staff of Process Technology Group, Petronas Research and Scientific Services Sdn. Bhd. who had assisted in collecting and analysing the products.

Petronas, PRSS Management and the French Government for the scholarship and encouragement.

TABLE OF CONTENTS

ACKNOWLEDGEMENT i

ABSTRACT in1. INTRODUCTION 1

2. BIBLIOGRAPHY 5

2.1. ADSORPTION 5

2.1.1. Definition 52.1.2. Adsorption Principles 52.1.3. Factors Affecting Adsorption 6

2.1.4. Industrial Adsorbents 6

2.1.5. Zeolites 8

2.1.6. Zeolite A 10

2.1.7. Zeolites X and Y 11

2.1.8. Pentasil Zeolite 11

2.1.9. Characteristics of Major Commercial Zeolites 12

2.1.10. Deactivation 13

2.1.11. Characteristics of the Adsorbate 142.2. ADSORPTION ISOTHERMS 15

2.2.1. Adsorption Isotherms From Solutions 152.2.2. Classification Of Adsorption Isotherm For Non 21

Electrolyte Binary Solution.2.2.3. Adsorption From Binary Solutions Of Substances Of 21

Limited Miscibility2.2.4. Adsorption from Multicomponent Solutions 22

2.2.5. Adsorption Isotherm Models 242.3. DYNAMIC MODELLING OF ADSORPTION COLUMNS 27

2.3.1. Flow modelling 272.3.2. Mass transfer between fluid and solid 29

2.4. PRINCIPLES OF COLON 303. EXPERIMENTAL 37

3.1. DETERMINATION OF THE ADSORPTION ISOTHERM OF 37A BINARY MIXTURE ON AN INDUSTRIAL ZEOLITE3.1.1. Description of the Isotherm Determination Apparatus 3 8

3.1.2. Experimental Procedure 393.1.3. Method of Calculation 43

TABLE OF CONTENTS

3.2. DETERMINATION OF BREAKTHROUGH CURVES OF A 46BINARY OR TERNARY MIXTURES USING COMMERCIAL MOLECULAR SIEVES3.2.1. Description of the Adsorption Breakthrough Curves 46

Determination Apparatus

3.2.2. Experimental Procedure 504. RESULTS AND DISCUSSION 54

4.1. ADSORPTION ISOTHERMS 544.1.1. Adsorption Isotherm of Methanol in n-Hexane 54

4.1.2. Adsorption Isotherm of 1 -Hexene in n-Hexane 614.1.3. Modelling of Isotherms 67

4.2. BREAKTHROUGH CURVES 68

4.2.1. Breakthrough Curves of Methanol or 1-Hexene in 68n-Hexane at Various Operating Conditions

4.2.2. Breakthrough Curves of Methanol and 1-Hexene in 85n-Hexane at Various Operating Conditions

4.3. MODELLING 994.3.1. Simulation of Elution Profile 99

5. CONCLUSION 1036. REFERENCES 141

APPENDICES

Appendix A GC calibration curve for methanol in n-hexane 105

Appendix B To calculate the concentration of adsorbate in the adsorbed and 106fluid phases (method A)

Appendix C To calculate the concentration of adsorbate in the adsorbed and 108fluid phases (method B)

Appendix D Photograph of experimental apparatus 113

Appendix E Sample data sheet of surface analysis 114Appendix F Data sheet of vapour phase adsorption 120Appendix G To calculate volume fractions 130

Appendix H Sample data sheet of simulation results 132

1 INTRODUCTION

The purpose for conducting the study is to investigate the application of molecular

sieves in removing methanol and other oxygenated compounds and to compare

simulated results using a proprietary Institut Francais du Petrole (IFF) computer

programme against experimental data.

Molecular sieves are crystalline aluminosilicates. They are similar to clays and

belonging to a class of minerals known as zeolites. For a long time, their main use

has been restricted to the remove of water from hydrocarbon fractions.

In recent years, the use of molecular sieves for other applications has been

developed particularly in the separation of oxygenated compounds (alcohols, ether,

etc) from hydrocarbon process streams.

With increasing gasoline demand and as a result of lead phase-out programs being

implemented in many countries, alternative octane enhancer such as Methyl

Tertiary Butyl Ether (MTBE) is increasingly being used. MTBE is synthesized

from isobutene and methanol in the presence of a strong acidic ion exchange resin

catalyst. A typical chemical MTBE reaction is as shown below.

CH3 ch3

HjC = C + CH3OH----- *-CH3- C - O -CH3

ch3 ch3

1

Generally, MTBE units are designed with two reactors in series. Most of the

etherification reaction is achieved at elevated temperature in the first reactor and

then partially finished in the second reactor with 90% of the isobutene conversion

taking place in the first and 50% conversion of the remaining isobutene in the

second. 99% conversion can be attained by installing a catalytic distillation

downstream of the second reactor where product MTBE is recovered in the

bottoms and unreacted C4 hydrocarbons and methanol are recovered overhead.

Unreacted methanol is recovered for recycle via a water wash of the C4-methanol

stream followed by a methanol-water distillation.

The near methanol-free C4 raffinate leaves the top of the distillation tower and goes

to the oxygenates remover tower. In the oxygenates removal tower, dimethyl

ether (DME), tertiary buthyl alcohol (TEA), MTBE and residual methanol are

separated from the C4-methanol raffinate stream. These components are

concentrated in the top of the tower and are drawn off with the light ends. The

product C4 raffinate leaves the tower bottom. A schematic flow diagram of a

conventional MTBE process is shown in Figure 1.

2

REACTION PRODUCT SEPARATION OXYGENATE REMOVAL

MeOHMETHANOLRECYCLER

1st 2nd Reactor Reactor

Water

OXYGENATEC4'S

C4'S

MTBE

Isobutylene Rich C4 Feed

MTBE MTBE WATER WASH OXYGENATEREACTORS COLUMN SYSTEM STRIPPER

Figure 1. Conventional MTBE process

REACTION METHANOL RECOVERY SYSTEM OXYGENATE REMOVAL SYSTEM

Isobutylene Rich 04 Stream

ADSORPTION

REGENERATION

METHANOLRECYCLE

MeOH

OXYGENATE FREE C4'S

SPENT REGENERATION FLUID

REGENERATIONFLUID

MTBEMTBE MTBE METHANOL

REACTORS COLUMN ADSORBERSOXYGENATEADSORBERS

Figure 2. UCC's raffinate treatment process

3

Instead of the water wash system, proprietary adsorption processes have been

developed by Union Carbide Corporation (UCC) which use molecular sieves to

adsorb the oxygenates. A schematic diagram of the UCC process is as given in

Figure 2. By using this scheme several advantages are achieved.

For the case of water wash and distillation, two costly towers, expensive ancillary

equipment (pumps, condensers, reboiler) are required. A purge is also required to

remove heavy components or corrosion products that may build up in the closed

extraction-fractionation loop creating potential disposal problems. Likewise during

the striping operation to remove oxygenates, in addition to high capital and utility

costs, the conventional oxygenate stripper often experiences excessive losses of

C4's in the overhead.

From the advantages shown above, it is obvious that a study of the competitive

adsorption between methanol, MTBE, C4 stream, DME, water, and TEA is useful

in understanding both the theoretical as well as the practical aspect of oxygenates

removal and it was the subject of our PhD work.

4

2 BIBLIOGRAPHY

2.1 ADSORPTION

2.1.1 Definition

Adsorption is a surface phenomenon which involves the separation of a substance

from one phase and its accumulation at the surface of another. The adsorbing

phase is termed the adsorbent and the adsorbed material at the surface is called the

adsorbate. Adsorption is differentiated from absorption, a process in which the

substance becomes distributed throughout the solid or liquid. Frequently, it is

difficult to distinguish which is more dominant since both processes can take place

simultaneously and hence the general term sorption is used to described them.

2.1.2 Adsorption Principles

Adsorption may be either a physical or a chemical process and in some cases both

occur simultaneously. Physical adsorption results from the relatively weak Van der

Waals forces comprising both the London dispersion forces and the classical

electrostatic forces (polarization, dipole and quadrupole interactions). Chemical

adsorption involves valency forces whereby a reaction takes place between the

adsorbent and an adsorbate resulting in the formation of a new compound.

Generally, physisorption is differentiated from chemisorption by the following

characteristic:

5

Physical Adsorption Chemisoption

Low heat of adsorption

* approximately equal to heat of

High heat of adsorption

• approximately equal to heat ofcondensation.

Reversible, non-activated and fast.

Monolayer or multilayer.

reaction.Irreversible, activated and slow.

Monolayer only.

2.1.3 Factors Affecting Adsorption

Basically, an adsorption system comprises of the adsorbate, the fluid phase, and the

adsorbent. The extent of adsorption relates to certain properties of the adsorption

system elements and also to conditions they are subjected to e.g. pressure,

temperature, feed velocity, etc.

For adsorbate, properties such as molecular size, molecular structure, polarity and

steric form have significant influence. For adsorbent, characteristics such as surface

area, the physicochemical nature of the surface, porosity and particle size are

important. The composition of the fluid phase in terms of competitive adsorption

can also interact greatly with adsorption capacity.

2.1.4 Industrial Adsorbents

In principle, all microporous materials can be used as adsorbents for purification

and separation. The microporous structure can be characterized by standard

techniques, the most important characteristic being surface area, pore volume and

6

For surface area determination, the most commonly used is the gas adsorption or

the Brunaur-Emmett-Teller (BET) method. Assuming liquid density and hexagonal

close-packing and given that the area of a N2 molecule to be 16.2 A2, the surface

area is taken as the area for monolayer coverage.

The total pore volume is usually determined by helium and mercury densities

displacements. Helium because of its small size and negligible adsorption, gives

total voids; whereas mercury, which do not penetrate into the pores at ambient

pressure gives interparticle voids. The difference between the both gives the total

pore volume.

The pore size distribution is measured by mercury porosimetry for pores larger

than 100 - 150A and by N2 desorption (or adsorption) for 10 - 250 A. For still

smaller pores, molecular sieving is used [1, 2, 3],

Various methods of determining the physical resistance of adsorbent to

degradation are available. Stirred Abrasion and Ro-Tap Abrasion are two such

examples.

Amongst the many types of material which exhibit adsorbent properties, four very

important and industrially used are activated carbon, molecular sieve carbon,

activated alumina and silica gel. However, another class of adsorbents which is

pore size distribution as well as mechanical properties such as bulk density, crush

strength, and attrition resistance.

7

gaining attention is zeolitic molecular sieves. This will be the subject of the present

study.

2.1.5 Zeolites

Zeolites are crystalline aluminosilicates of alkaline or alkaline earth and can be

represented stoichiometrically by

AW(A10),(Si02)y] zHzO

where x and y are integers, n is the valence of cation M and z is the number of

water molecules.

Structurally, zeolites framework consists of a three dimensional network of Si04

and A104 tetrahedra, joined together in various regular arrangements through

shared oxygen, to form an open crystal lattice containing pores of molecular

dimensions into which guest molecules can penetrate this is why they are known as

molecular sieve. Although pure analogs such as silicalite has been prepared, the

Si/Al ratio is commonly between one to five. Each aluminium atom present in the

structure would require an exchangeable cation to balance the negative charge on

the framework. By reducing the number of aluminium atom through substitution

with a silicon atom a systematic transition in adsorptive properties from the

aluminium-rich sieves, which have very high affinities for water and other polar

molecules, to the microporous silicas which are essentially hydrophobic and adsorb

n-paraffin in preference to water. Thus by varying the Si/Al ratio and cationic form,

8

11.3

A

it is possible to alter the adsorptive properties to achieve the selectivity required for

a specific separation.

Intracrystalline difiusivities are determined by the free diameters of the windows.

The size of the windows depends on the number and type of exchanged cations.

Sodalite which has six-membered oxygen ring has a free diameter of about 2.8 A

which allows small polar molecules such as H20 and NH3 to penetrate. Zeolite

with eight-membered oxygen including type A, chabazite and erionite have free

diameter of 4.2 A. Large port zeolites such as type X, Y, and mordenite having

twelve-membered oxygen rings have free diameters of 7 - 7.4 A. The pentasil

zeolites which include ZSM-5, ZSM-11, and silicalite are characterized by an

intermediate channel size formed by ten-membered oxygen rings falls around 5.7

A. Figure 3 provides some illustrated examples of the zeolites framework

w

Figure 3. Schematic representation showing framework structures of (a) zeolite A (b)zeolites X and Y, (c) erionite and (d) chabazite.

a

VIII

2.1.6 Zeolite A

Socialite units are made up with 24 tetrahedra which are arranged in six four-rings

(or square faces) and eight six-rings (or hexagonal-faces). An octahedral

arrangement of sodalite units joined by oxygen bridges through six square faces,

gives the zeolite A framework structure. This arrangement forms a large polyhedral

cage of free diameter of about 11.4 A with eight-membered oxygen windows. A

three dimensional isotropic channel structure constricted by eight-membered

oxygen rings is obtained by stacking these units in a cubic lattice. Zeolite A has a

Si/Al ratio closed to 1 with 12 univalent exchangeable cations per unit cell. Three

distinct cation sites are identified given by Type L, H, and HE as illustrated in Figure

4(a) Depending on the cation types, a 3A sieve is obtained with potassium and a

4A sieve with sodium. The 3A sieve is widely used for drying reactive

hydrocarbons such as olefins in view of its small pores, which exclude the larger

olefin molecules thus preventing reactions.

Figure 4. (a) type A (b) types X and Y

10

2.1.7 Zeolites X and Y

The framework structure of zeolites X and Y consists of an array of eight cages

containing a total of 192 A102 and Si02 tetrahedral units. Sodalite units are linked

via oxygen bridges through four of the eight hexagonal-faces in a tetrahedral

arrangement like carbon atoms in diamond. The resulting structure has a large

cavity or supercage with twelve-membered oxygen rings of free diameter around 7

- 8 A. Depending on the Si/Al ratio, a X zeolite has a ratio between 1-1.5 and a Y

between 1.5 - 3.0. Also the number of exchangeable univalent cations varies from

about 10-12 per cage for X to as low as 6 for high silica Y. The cation

distribution is much more complex with six different sites being identified. Through

ion-exchanged of the cation present, the adsorptive properties as well the

selectivity of zeolites X and Y could be improved.

2.1.8 Pentasil Zeolite

These zeolites have structures characteristic of stacking of double five-ring unit.

ZSM-5 and ZSM-11 are end members of a series of pentasils. Both ZSM-5 and

ZSM-11 have three-dimensional pore systems comprising 10- tetrahedron rings,

intermediate in size between the windows for zeolites A, X, and Y. Wide variation

in the Si/Al ratio is possible, however, typical value of a ZSM-5 zeolite is given in

Figure 5. They are characterized by 2 types of pore system, one consisting of

zig-zag channels of near circular cross-section and the other of straight channels

with elliptical cross-section as in the case of ZSM-11 structure. Adsorptive

properties are determined by the different framework structure and pore size.

11

Figure 5. Schematic diagram of the channel structures of (a) ZSM-5 and (b) ZSM-11 [4]

2.1.9 Characteristics of Major Commercial Zeolites

Table 1 gives the characteristics of some major commercial zeolite adsorbent in the

pelletized form.

Table 1. Characteristics of some major synthetic zeolite sorbents [5]Zeolite Type Major Cation Norminal

Aperture Size, ABulk Density,

kg/m3Water Capacity.

Wt °o

3 A (Linde) K 3 641 203 A (Davidson) K 3 737 21

4A (Linde) Na 4 657 22

4A (Davidson) Na 4 705 23

5 A (Linde) Ca 5 721 21.55 A (Davidson) Ca 5 705 21.7

10X (Linde) Ca 8 641 31.6

13X (Linde) Na 10 609 28.5

13X (Davision) Na 10 689 29.5

Table 2 gives a list of the molecular dimensions of some molecules which are

smaller than the apertures of the zeolite types. Separation of a mixture from the

12

different groups via molecular sieving is theoretically possible. However, in general

separation is normally based on different strengths of different equilibrium amounts

adsorbed rather than on molecular sieving.

Table 2. Molecular dimensions and zeolite aperture sizes [6]

Molecular size incr&zsfcg ~=

He. Nc, Ar. CO Kr.Xc C,H, SF.Oj, CH. uo-C»H,0

C,H. «-C,H„ CF,a," iso-CjH,,CH,OH

Size limit for CH.CN «-C,4Hle CF,C1 iso-C.H,,Ci- ind Bi- CH,NH, etc CHFCl, etc.mordcnitci and CH,Q c,H,a chq,levynite about CH.Br C,H,Br CHBr,here (3-8 A) CO, C.H.OH CHI,

Type 5--------------------------- C,H, C.H.NH, (CH,),CHOHcs, CH,a, lCH,),CHa

.CH,Br, n-C,F,Siae limit for Ni- CHF.G o-C.F.o

mordenite and Linde CHFr n-C,F,.sieve 4A about here tCHjIjNH 8,H.(5:4-0 A) CH,I

Type 4—---------------------- 3,H.Size limit for Ca-rich

chabazxtt Unde sieve5A. Ba-zrolite and{melinite about here(=4-9 Al

Type )--------------------------

Type 2-

Type I

(CH,),N C.H. Naphthalene 1.3. 5-tricthyl(C,H,),N C.H,CH, Quinoline benzeneC(CH,)4 C.H.ICH,), 6-decyl-1.2.

3.4-tctra-QCH,),a Cyclopentane hydro- I. 2. 3.4. 5. 6.QCH,),Br Cyclohexane naphthalene. 7. S. 13. 14. (5.C(CH,),OH Thiophene 2-butyl* I- 16-dccahydro-ca. Furan hexyl indan chryseneCBr. Pyridine C.F..CF,c,F,a. Dioianc

8*0^1*

Size limit for Lindesieve I0X about here

Size limit for Unde sieve 1JX about here MO A)

l"-C,F.),N

2.1.10 Deactivation

Coke formation or slow loss of crystallinity often result in adsorbent deactivation

involving either a loss of equilibrium capacity or an increase in mass transfer

resistance. When sieve is exposed to high temperature and high moisture during

thermal regeneration a slow and irreversible degradation of crystals structure may

occur as in the case of zeolite X which has limited hydrothermal stability. In the

case of zeolite A, under similar conditions, increase in mass transfer resistance

results in partial pore closure.

13

When reactive species such as olefins are present, they form polymeric compounds

which eventually become coke on thermal regeneration resulting in reduced

adsorbent capacity.

2.1.11 Characteristics of the Adsorbate

The physical and chemical character of an adsorbate have significant influence on

adsorption selectivity and rate . For a homologue series of organic molecules in an

aqueous system solubility decreases with increase in chain length due to

hydrophobicity of the hydrocarbon portion [7], A material which has low solubility

in water will have a higher tendency to concentrate on the adsorbent surface.

However, large molecular size could result in slow diffusion through the pore or

worse completely block the pore entrance.

In addition, the molecular form, be it ionic or neutral, branched or linear, has

significant impact on adsorption.

14

2.2 ADSORPTION ISOTHERMS

2.2.1 Adsorption Isotherms From Solutions

In contrast to gaseous phase adsorption, liquid phase adsorption involves the

formation of a compact layer on the adsorbent surface. As there are no vacancies in

the surface layer and the bulk solution, the number of molecules of a given

component may increase in the surface layer only by displacement of an equal

number of molecules of another component.

While the determination of the gaseous phase adsorption isotherm is a straight

forward procedure, liquid phase adsorption isotherm is a much more difficult,

hence some simplication have to be made.

In order to derive a relationship between adsorption at the solution/solid interface

and the solution composition, consider adsorption from a completely miscible

binary solution whose components are 1 and 2 on a homogeneous adsorbent

surface. At thermodynamic equilibrium :

111 = Hi , ti = U2 (1)

where Hi and H2 are the chemical potentials of the components 1 and 2

respectively, in the surface phase, and Hi and H2 are the corresponding potentials

in the bulk phase.

Given that |i, = H? +RT\nx(fi , equation 1 can be rewritten in the form :

p-i'1 +RTln xSfi = |ii +RT]nxlf1 (2)

15

H-2* +RT\nxs2f2 = p,® +RT\nx2f2 (3)

where {Xj’s and p®’* are the standard chemical potential of component 1 and 2 in

the surface phase, p.® and p® are those in the bulk phase, x[ and xi, and xs2 and

x2 ;/^and/i, and f2 and/2 are the mole fractions and activity coefficients of

component 1 and 2 in the surface and bulk phases.

Combining equations 2 and 3,

*1*2 _fif2 xix2 j\fi exp (4)

Denoting

c=f

K= exp 1RT Hi"' - 111

# = CK=a (5)

Given x£ = 1 - X* and x2 = 1 - xi

S _ Cttl _ 0=11 OOC1+X2 ! + («-!)*:, (6)

16

The above equation is often referred to as the individual adsorption isotherm of

component 1 from solution. The quantity a is known as the distribution coefficient

or distribution function. It depends on bulk phase composition.

Assuming both surface and bulk phases to be ideal and adsorption takes place on a

uniform adsorbent surface

C = 1 and K, = constant

which implies that

4*2*i4 = a = Ki

where K, is the adsorption equilibrium constant.

Hence,

c _ K\Xl 1

(7)

This equation, is widely used in studies of adsorption from solution.

Assuming adsorption from non ideal solution; C and a varies with x,

For all values of a; when x, —> 0 ; 1 + (a - 1) x, —M

17

Hence,

x\ = ax i

When x, = 1; 1 + (a - l)x, —> a

hence, x\ = Xi = 1

Case X

When component 1 is strongly adsorbed which implies that

- — Hi j » RT , hence K, » 1 and a » 1 for slight deviation of C from

unity.

Therefore,

s o%,xi ~ 1+0%, (9)

Case 2

When component 1 is weakly adsorbed which implies that, K,« 1, hence K, « 1

and a «1 for slight deviation of C from unity.

Therefore,

V5 *»!i-%, (10)

18

Case3

When both component 1 and 2 has approximately equal adsorbabilities which

implies that, K, ~ 1 and a is a function of K, and C. a can be greater than unity for

small values of x, and smaller than unity for larger values of x, or vice versa.

Cases 1, 2 and 3 can be graphically representated by curves 1, 2 and 3 in Figure 6.

x0s is given in mole fraction.

Figure 6. Individual adsorption isotherms from a binary solution : 1. positive adsorption, 2- negative adsorption, 3- limited adsorption, a - the adsorption azeotropic point.

Equation 6 can also be rewritten in terms of number of moles of the components

per gram of adsorbent in the surface solution. In this instance,

T\\ = l+(ay-l)*i (11)

2where J = is the coefficient of surface displacementTlm,l

Tj^ i and Tj^2 are the number of moles of component 1 and 2 at saturation.

19

The expression can also be rewritten in terms of excess adsorption (reduced

adsorption)

a(n) _ •n£,,iY(«-l)*i(l-*i) ^1 1 + (ay-l)%i (12)

or

(h) _ <i7(a-l)»i(l-*i)* 1 + (CCjf-l)*! (13)

where s being the specific surface area.

Depending on the value of a, all possible cases can be represented graphically by

curves 1,2, and 3 of Figure 7

Figure 7. Excess adsorption isotherms for a binary solution: 1- positive adsorption, 2- negative adsorption, 3 - limited adsorption, a - the adsorption azeotropic point.

20

2.2.2 Classification Of Adsorption Isotherm For Non Electrolyte Binary Solution.

The first classification of excess adsorption isotherm for binary mixture was made

by Ostwald and Izaguirre [8], Schay and Nagy [9, 10] subsequently proposed a

more detailed classification as shown in Figure 8.

Type 1 Type 2 Type 3

Type 5Type 4

Figure 8. Classification of excess adsorption isotherms for a binaiy solution

2.2.3 Adsorption From Binary Solutions Of Substances Of Limited Miscibility

The adsorption isotherms of binaiy solutions of liquids of limited miscibility often

have the shape shown in Figure 9. The adsorption increases rapidly as its solubility

limit is approached and tends asymptotically to a line parallel to the adsorption

axis. The rapid increase of adsorption at these concentrations indicates multilayer

adsorption. However, recent studies attribute this behavior to phase separation

which starts earlier than in bulk because of the effect of the porous structure of the

adsorbent, this process is therefore similar to the capillary condensation observed

in vapour adsorption.

21

35

30

E

0 0.5

C/Cn1.0

Figure 9. Excess adsorption isotherm of methanol on silica gel from n-heptane. [11]

2.2.4 Adsorption from Multicomponent Solutions

Adsorption from multicomponent solutions is a very complex process and presents

many difficulties. Oscik [12, 13] considered the thermodynamics of adsorption

from multicomponent systems. He derived an expression to calculate the mole

fraction of a given substance in the surface layers on the basis of its adsorption

isotherms from suitable binary solutions.

(14)

where n is the number of components in the multicomponent solution.

2.2.5 Adsorption Isotherm Models

Adsorption isotherm can be mathematically represented by an expression relating

the amount adsorbed q to the concentration c in the equilibrium fluid phase

such as q = f(c). This is a generalized adsorption isotherm model.

Although there exist a number of adsorption isotherm models of varying degree of

complexity, the most widely used are those of Langmuir (15), Freundlich (16) and

Langmuir-Freundlich (17). These isotherm equations are often used to predict the

amount adsorbed in a specific system . In the present study, only the Langmuir and

Langmuir-Freundlich isotherm models will be reviewed for the purpose of

simulating the experimental data.

a. Langmuir Model

The Langmuir model is based on the following assumptions:

• Molecules are adsorbed on a fixed number of localized sites.

• Each site can accommodate only one adsorbate molecule.

• All the sites are energetically equivalent.

• There is no adsorbed molecule-molecule interaction.

The adsorption isotherm expression is obtained by considering dynamic equilibrium

between the rates of adsorption and desorption.

For a pure substance,

23

(15)? _ kx Qm 1 +kx

where q is the quantity adsorbed.

qm is the quantity adsorbed at saturation,

k is the adsorption constant,

x is the molar fraction in the fluid phase.

For a multicomponent system,

(jj _ faQ™ l+'LkjXj

where i represents the component i.

b. Langmuir- Freundlich Model

This model was developed by Koble and Corrigan (17). It was derived from the

Langmuir and Freundlich expressions taking into consideration the heterogeneity

of surface sites.

(16)

For a pure substance,

9 _ kxa 1 +kxa

where a is an empirical coefficient.

For a multicomponent system, it gives :

(17)

24

(18)q{ _ kjxf‘ qm 1 +Z,kjXjJ

25

26

2.3 DYNAMICAL MODELLING OF ADSORPTION COLUMNS

The length of an adsorption column is generally much greater than its diameter so

that one can consider the fluid and solid concentration being only function of z, the

position along the column. There are three main phenomena to model in such

system:

- the flow of the fluid through the packed bed of adsorbent,

- the mass transfer between the fluid and the adsorbent

- the thermodynamical equilibrium properties.

The latter has already been treated in the previous chapter. We will focuss here on

flow modelling and mass transfer. The following discussion is based on reference

[23], the basical one in the adsorption domain.

2.3.1 Flow modelling

If the flowrate through the packed adsorbent is sufficently high, one can consider

that the flow is a plug flow but it is more convenient to take into account the axial

dispersion due to molecular diffusion and turbulent mixing.

One way to represent axial diffusion is to define an axial dispersion coefficient Da

such as the mass balance of component i is as follows :

r» d2C,- d(v-C,) dC,- , 1-SjT+~sT+lT+— (19)

27

where v is the fluid interstitial velocity

Q the fluid concentration

e,, the bed porosity, supposed to be uniform

q; the mean solid concentration of component i

^ the mean flux of i per unit of particle volume

Sometimes, v is approximative^ constant along the column : this is the case for

adsorption processes from liquids or when the adsorbable components

concentrations are sufficiently low (the so-called "trace system" in Ref. 23). If v is

not constant, its variation with z is calculated by using the global mass balance :

Ct- 1+^-2, t=0 (20)

where Ct = X, C, the total fluid concentration is supposed to be constant

Another way to model axial dispersion, which has been extensively used in

chromatography modelling [25], is to consider the bed void fraction as a serial

arrangement of Np perfectly mixed cells. If one consider that the interstitial velocity

or the volumetric flowrate are constant, the mass balance of component i over the

cell number j is :

g-cr'-C-ci+tV^+Fy.Tr (2i)

where Q is the fluid volumetric flowrate

Ft' and VJ are the bed voidage and solid volumes of cell j.

28

Generally, the cells are identical so that Vb' =Vb and Vp ~Vp . For high Peclet

number or if Np is sufficiently large, the plug flow with axial dispersion and the

cells in series models are equivalent.

2.3.2 Mass transfer between fluid and solid:

If the mass transfer efficiency is very high, one may consider that thermodynamical

equilibrium between solid and fluid is reached at each time and position in the

column. In this case q^q*, the solid concentration of the adsorbent at equilibrium

with the interstitial fluid.

If mass transfer efficiency has to be taken into account, one must consider the

different following step:

- mass transfer between the fluid and the surface of the pellets : one define an effective mass transfer coefficient A^such that:

= kf-a-(Ci~ C*) where a is the external surface area per unit particle volume

and C* is the fluid concentration of component i holding at the particle surface. It

is possible to evaluate kf by using correlation between non dimensional numbers.

-mass transfer inside the pellets : a pellet of zeolite is made of a great

number of very small crystals so that it may be seen as a porous media which

porosity is ep. Basically, one must describe mass transfer within the intercrystalline

macropores of the pellet and within the crystals. If Cpi is the concentration of

29

component i within the macropores and if the pellet is considered as a sphere, the

component i balance over the pellets leads to :

R2V j

BRdCpi l-£p dcci —+—'~ (22)

8c”where is the component i flux per unit of crystal volume between the macropores and the crystals, Cci is the mean concentration of component i in the

crystal, R is the radius within the pellet and Dp is the apparent diffusion coefficient

through the macropores.

8C~-In order to calculate -^r, one must solve the following mass balance over the

crystal:

J. 3C„r2 " dr 3r (23)

where Cd is the concentration of component i in the crystal, r is the radius within

the crystal and Dc is the diffusion coefficient through the microporous crystal.

The crystal surface is supposed to be at equilibrium in this so called bi-dispersed

model. Simplification occurs if one or another step is controlling the overall

process [23],

2.4 PRINCIPLES OF "COLON"

The simulation program "COLON" is an IFP propetary computer program

developped to simulate adsorption processes for the liquid phase separation of C8

aromatic isomers as orthoxylene, metaxylene and paraxylene [18]. This model can

be used to simulate breakthrough curves or SMB ( simulated moving bed)

30

processes. We will compare our experimental breakthrough curves to thoose given

by "COLON".

The "COLON" model is based on the following assumptions :

- the adsorbent repartition in the column is uniform

- the temperature is constant

- the liquid flowrate is constant

The liquid flow through the column is represented by a serial arrangement of Np

identical perfectly mixed cells and the thermodynamical equilibrium being supposed

instantaneous, each of these cells is in fact a theoretical plate.

The volume corresponding to each plate is divided in four zones:

- the fluid volume Vb corresponding to the bed voidage

- the fluid volume Vmp corresponding to the macro and mesoporous volume

of the pellet

- the volume Vgp corresponding to the microporous volume of the pellet or

the adsorbent capacity

- the solid volume

31

The mass balance over each cell number j for a component i is given by the

ordinary differential similar to equation (21). This equation is discretized according

to the time in order to solve it. If one choose a step time equal to the fluid mean

time residence 4+1 = hi the bed voidage of each cell, the component i mass

balance becomes:

X* ' % +^™Pi*' Vmp + Y*ijc'Vvp= Xfc+i' (P& + Vmp) + Xjt+i • Vpp (24)

where is the liquid volume fraction of component i in the cell j-1 at instant tk,

Xiijt+i is the liquid volume fraction of component i in the cell j at instant tj,+1

X?mpiJc is the macro-mesoporous volume fraction of component i in the cell j at instant tk

and F^+1 are the micropore volume fraction of component i at instant tj.

and tk+] respectively.

In the equation (24), it is supposed that only the liquid contained in the bed

voidage of the cell j-1 is flowing (see figure 10) and mixed with that contained in

the bed voidage as well as that contained in the macro mesoporores and that

adsorbed in the micropores of the cell j.

The equilibrium being supposed reached instantaneously, A^+1 and 7y.+1 are

related by the equilibrium condition. If one suppose that the relative selectivity of

each component i to a reference component 1 is constant, the equilibrium relation

is:

a,i = with z = 2, Nc (25)

The equation (24) and (25) coupled with one of the conditions :

NY.Xi = 1

32

N27, = 1

lead to a 2.NC non linear equation system allowing the calculation of the unknown

variables ^+1 and P^,+1 at each instant knowing the composition profile at instant

^k-

33

N etages theoriques

Xi Vri

Xpi Mnp

Yi Xfobolide

1 colonne 1 etage theorique

h<jV%£.

) —>

Deplacement du liquide interstitiel de l'etage n-1 vers l'etage n

Transition de l'etape de contact t-1 a l'etape de contact t

Mise en equilibre

Etape de contact t

’fiCrdOJg. sia

Apres equilibre

Etagen

Avant equilibre

X?

Xp-

Y"

Etage n

X?

Etage n-1 Etagen

36

3 EXPERIMENTAL

3.1 DETERMINATION OF THE ADSORPTION ISOTHERM OF A BINARY

MIXTURE ON AN INDUSTRIAL ZEOLITE

A commercial zeolitelSX similar to that in the MTBE plant was used during the

experiments. For practical convenience, methanol was used to represent the

oxygenate components and C6 hydrocarbon stream instead of C4's since it is easier

to handle and sourced. For either design purposes or for understanding the

adsorber behavior, it is necessary to acquire information on adsorption capacity. In

the present work, the adsorption isotherms of methanol-n-hexane and

1-hexene-n-hexane system at 313 K and 323 K were determined. For practical

reason, in addition to equilibrium, the adsorption rate must also be taken into

account. Two methods are available which have been termed "micro" and "macro".

In the micro approach, all major resistances encountered in the transfer of an

adsorbate from the bulk phase to the adsorption sites are evaluated and suitable

diffusion equation are applied. Generally this method is difficult and tedious to use

and will not be considered. Instead the "macro" approach in which the total

resistances is represented in the form of a breakthrough curve is preferred due to

its simplicity and practical applicability. Hence, in the present study, breakthrough

curves for a series of binary and ternary components were carried out.

The following describes the ancillary equipment and the procedure used in

carrying out the adsorption isotherm determination. Adsorption isotherm provides

information on the selectivity as well as the capacity of a particular

adsorbate-adsorbent system. Such information are prerequisite for the analysis and

37

design of an adsorption separation process. In carrying out the experiment, a

known weight of adsorbent is immersed in a solution of varying concentration in a

closed reactor. After a period of time and when adsorption equilibrium is

established, a sample of the equilibrium fluid is removed for analysis. From the

compositional analysis of the solution before and after equilibrium and the catalyst

weight, the adsorption isotherm can be determined.

3.1.1 Description of the Isotherm Determination Apparatus

The apparatus and chemicals used comprise of the followings :

• Reaction Cell

A schematic diagram of the reaction cell is given in Figure 12. It is constructed of

non-magnetic material except for the rotating blade mechanism which is made of

magnetic material. The cell consists of the following parts:

a) cell reservoir

It has a volume of 307 cm3 and can be isolated hermetically by an air-tight

cover. A 50 cm diameter cylindrical sieve is placed in the centre of the

reservoir in order to prevent molecular sieve which is distributed outside it

from contacting the rotating blade which may cause serious attrition of the

molecular sieves resulting in fines which is undesirable. To maintain constant

temperature, circulating fluids is passed between the concentric walls.

b) cover

It has four openings in the upper side for pressurising or vacuuming,

thermocouple pressure relief and sampling and addition of adsorbate/solvent.

38

Attached on the lower side is the rotating blade for agitation of the

adsorbate/ solvent,

c) Motor

The rotating blade is driven by an electric motor. Transmission between the

two shafts is through magnetic coupling thus allowing the contents to be

isolated from the outside

• Furnace

It is necessary to activate the molecular sieves before adsorption measurements

because of water adsorption. This is normally done in a quartz tube. The lower half

is filled with carborandum and the upper half is filled with molecular sieves. The

quartz tube was heated to 723 K with a constant purge of nitrogen admitted from

the bottom. Activation was carried out for 4 hours. Upon completion of the

activation, the molecular sieves were quickly transferred to an air-tight bottle and

stored in a glove box.

• Glove box

A glove box was used to carry out the charging of the reaction cell in an inert

atmosphere.

• Gas Chromatograph

Analysis of samples taken from the reaction cell was effected by a Hewlett Parkard

HP 3890 Series II gas chromatograph equipped with a HP7673 automatic injector

and a HP 3365 chem station.

39

The conditions used are as follows:

Column : capillary (PONA)

Length : 50 m

Diameter : 0.2 mm

Stationary Phase : 0.5 pm cross-linked methyl silicone

Injector Temperature : 473 K

Detector Temperature : 523 K

Oven Temperature

313-333 K : 2 K/min

333-393 K : 15 K/min

Carrier Gas : He

Carrier Gas Flowrate : 30 ml/min

Hydrogen gas Flowrate : 30 ml/min

Air Flowrate : 200 ml/min

Split Ratio : 200:1

Detector Type : fid

• Solvents

a) Methanol

Brand: Aldrich Chemical Co. Ltd.

Grade: Technical

Purity: 99%

b) 1-Hexene

Brand: Aldrich Chemical Co. Ltd.

40

Grade: Technical

Purity: 97 %

c) n-Hexane

Brand: SDS

Grade: Spectrosol

Purity: 99 %

All solvents used for the experiments were dried using 3A molecular sieves.

Moisture content after drying was analysed using a Mitsubishi Moisture Meter

Model CA 06.

• Molecular Sieves

a) Type: 13 X

Form: beads

Diameter: 0.8 mm

Particle Size: 10 X 20 mesh

Bulk Density: 673.8 kg/m3

b) Type 5 A

Form: extrudates

Diameter: 1.6 mm

Particle Size: -

Bulk Density: 690-730 kg/m3

3.1.2 Experimental Procedure

All dehydrated solvents, molecular sieves, reaction cell, syringe, flask and sample

bottles were initially placed into the glove box where a weighing balance was

previously installed. About 10 g of molecular sieves were accurately weighed and

carefully distributed around the metallic cylindrical sieve with the aid of a small

polyethylene funnel. Next, 100 g of n-hexane was accurately weighed in a

volumetric flask, followed by an addition of about 0.5 g of methanol or 1-hexene.

The flask was stopped and shaken well. A small sample of about 3 cm3 was

removed into a small bottle. The flask was again weighed. The mixture was then

transferred into the reaction cell and the flask reweighed. The reaction cell was

closed and all lugs tightened. The cell was gently removed from the glove box so

as to prevent intrusion of the molecular sieves from passing the metallic sieve.

The reaction cell was installed onto the motor assembly. A circulating bath was

connected onto the inlet and the outlet. (Circulation bath has been previously

tumed-on and set to required temperature.) The thermocouple was connected to

the temperature indicator and the motor was switched on. The speed was slowly

increased to 200 r.p.m. with the speed controller. (Caution: Do not use excessive

speed or this may cause decoupling of the magnet driving the rotating blade.)

When the reaction cell has reached the desired temperature, the time was noted.

After 2 hours, a sample was taken with the aid of a previously weighed syringe

equipped with an 8 cm long needle. The syringe together with the sample was

weighed and thereafter a small portion of the content was transferred through a

syringe filter into a 2 cm3 vial with a septum cap. (This is to remove fines produced

during the adsorption stage, otherwise it may clog the automatic injector syringe of

the gas chromatograph). The vial was then crimped and its content analysed. In

42

order to analyze the amount of methanol or 1-hexene present in a sample, a

calibration curve for each was prepared (see Appendix A).

3.1.3 Method of Calculation

There are two methods for calculating the amount of adsorbate adsorbed on an

adsorbent depending wether the solvent is adsorbed or not. For methanol in

n-hexane, method A is used and it requires the use of the expressions:

/=nfmp

rrfm+rrfh

and

where q is the amount of methanol adsorbed per gram of molecular sieve.

f is the concentration of methanol (g/cm3) remaining in the solution.

A detailed derivation of the expression is given in Appendix B.

For 1-hexene in n-hexane, method A cannot be used because there is a competition

for the adsorption of the two species so method B has to be used and the

expressions are as given below:

Ta = ^j-{x°a-xa) and

Ta+M^xa A 1 —Xa + $bXa

43

where FA is the surface excess of the component A.

T]a is the amount of component A adsorbed.

A detailed derivation of the expressions are as given in Appendix C.

44

Motor Shaft

Sampling Point

Cover

Thermocouple

Circulating Water

Paddle Shaft

Metal Sieve

Molecular Sieves

Figure 12. Reaction cell

3.2 DETERMINATION OF BREAKTHROUGH CURVES OF A BINARY OR

TERNARY MIXTURES USING COMMERCIAL MOLECULAR SIEVES

The following describes the ancillary equipment and the procedure used in carrying

out the adsorption breakthrough curves determination. When the adsorbent in the

column is saturated the product will breakthrough with a sharp front. In reality, a

dispersed concentration front is observed due to the gradual change in

concentration as a result of axial dispersion and mass transfer resistance. A plot of

the effluent concentration with respect to the length of time or volume processed,

which is termed a breakthrough curve is useful in determining the effective life of

an adsorber bed. In determining the breakthrough curves, a known concentration

of contaminants (methanol, 1-hexene or both) is added to a feed (n-hexane). The

feed is then pumped through a column filled with a known quantity of adsorbent.

At the outlet, samples of effluent are collected at regular interval of time and

analyzed to determine their composition. From the plot of effluent concentration

against time or volume processed a breakthrough curve is obtained.

3.2.1 Description of the Adsorption Breakthrough Curves Determination

Apparatus

• Adsorber

An experimental set-up of the design shown in Figure 13 was constructed and a

photograph of which is given in Appendix D. It comprises the following :

a) Feedtank

The feedtank is constructed entirely of 316 stainless steel material. It is 236

mm in diameter and 549 mm in height with a holding capacity of 20 litres.

46

The cover is of an air-tight design with provision of a relief valve. The

feedtank is rated to withstand a maximum working pressure of 3.9 bars.

b) Metering Pump

The pump was supplied by LEWA. It has a modular design comprising of

drive, drive element, pumphead and manual metering adjustment. It has a

maximum pressure of 40 bars, delivering flowrates from 0-20 litres per hour.

The pumphead is of the plunger type.

c) Cryostat

A Lauda cryostat was used to preheat the feed to the working temperature.

d) Adsorption Column

The adsorption column is 1-meter in length with an outer diameter of 19.05

mm and wall thickness of 1.65 mm. It is made of 316L stainless steel.

e) Oven

A thermostatic heating oven was used to maintain the adsorption column/s at

the working temperature. This oven was supplied by BINDER.

f) Fittings and Valves

All fittings were of the Swagelock type with valves supplied by Whitey and

Nupro.

g) Instrumentation and Sensor

Temperature indicator and thermocouple were supplied by Pyromation while

47

pressure monitoring system was supplied by Mescon. The model used was

Series 500

• Gas Chromatograph

Analysis of samples taken from the outlet of the adsorption column/s was effected

by a Varian CX 3600 gas chromatograph equipped with a CX 8200 autosampler

and a Varian Star workstation.

The conditions used are as follows:

Column

Length

Diameter

Stationary Phase

capillary

60 m

0.25 mm

0.5 pm cross-linked dimethyl

polysiloxane

Injector Temperature : 523 K

Detector Temperature : 523 K

Oven Temperature

323-333 K : 2 K/min

333-393 K : 15 K/min

Carrier Gas : He

Carrier Gas Flowrate : 30 ml/min

Hydrogen Gas Flowrate: 3 0 ml/min

Air Flowrate : 200ml/min

Split Ratio

Detector Type

50:1

fid

• Furnace

It is necessary to activate the molecular sieve prior to adsorption. This is done by

programmed heating of the packed column to 723 K with a constant stripping of

48

nitrogen admitted from the bottom and circulating upflow. Activation was carried

out for 4 hours. Upon completion of the activation, the column was quickly closed

up with sealing caps.

• Solvents

a) Methanol

Brand: BDH

Grade: Technical

Purity : 99%

b) 1-Hexene

Brand: Merck

Grade: Technical

Purity : 96%

c) n-Hexane

Brand : Baker

Grade : Analysis

Purity : 99%

All solvents used for the experiments were dried using 3A molecular sieves.

Moisture content after drying was analysed using a Mitsubishi Moisture Meter

Model CA 06.

49

• Molecular Sieves

a) Type: 13X

Form: beads from Procatalyse

Diameter: 0.8 mm

Particle Size: 10 X 20 mesh

Bulk Density: 673.8 kg/m3

b) Type: 5A

Form: extrudates from Procatalyse

Diameter: 1.6 mm

Particle Size: -

Bulk Density: 690 - 730 kg/m3

3.2.2 Experimental Procedure

The empty adsorption column was initially weighed prior to packing with

molecular sieve. After packing, the filled tube was again weighed to obtain the

weight of molecular sieve used. The column was then transferred to a vertical

furnace where the molecular sieve was activated at 723 K in a slow stream of

nitrogen. After about 4 hours, the column was allowed to cool to room

temperature. Both ends of the column were capped and weighed. The weight loss

due to volatiles and moisture was noted.

The column was immediately transferred to an oven. It was connected to the

experimental set-up in the presence of a nitrogen stream to prevent intrusion of air

into the column. The outlet of the column was closed and the column was

pressurised to 3.5 bars and allowed to stand for 30 minutes in order to check for

leaks. When no leaks are detected, the oven was heated to the desired temperature.

50

At the same time, the metering pump was set to the required flowrate. A known

concentration of mixture (methanol in n hexane, 1-hexene in n-hexane or methanol

and 1-hexene in n-hexane) was prepared and loaded into the feedtank. The

feedtank was then weighed and the amount of feed in the tank was recorded. It

was then connected to the inlet of the metering pump via a flexible teflon tubing.

The return-line used was also made of teflon. The balance reading, temperature of

the inlet and outlet of the column and cryostat temperature at the start were

recorded. When the oven temperature has stabilised at the working temperature,

the metering pump and stopwatch were started simultaneously. At the sight of the

first drop of effluent emerging from the outlet, the time was noted. The rate of

flow at the outlet was measured. Samples of effluent were collected at selected

time intervals. In addition, the temperatures of the inlet and outlet of the column

and balance reading were recorded simultaneously. At the end of the run, the

balance reading after disconnecting the teflon lines was recorded.

For regeneration in-situ, all inlet and outlet valves were closed, on shutting down

the metering pump. The feedtank was disconnected and replaced with another

filled with a 45:55 ratio of 1-hexene in n-hexane mixture. The inlet to the column

was exchanged with the outlet and vice-versa.

The oven was then heated to 383 K and the cryostat was similarly heated to a

temperature which would provide an inlet temperature of 383 K. On reaching the

desired stabilised temperature, the metering pump was started, followed by the

opening of the inlet valve. The exit valve was slowly opened to allow an internal

51

pressure of 8 bars to be maintained. (This is to ensure that the feed remains in a

liquid state.)

Samples of effluent were collected at selected time intervals as done in the

adsorption stage. The run was continued for 100 minutes after which all inlet and

outlet valves were closed on shutting down the metering pump.

For the readsorption step, all lines were reconnected as in the adsorption stage and

the system run as per the adsorption procedure.

All the samples collected were analyzed and from the results obtained a

breakthrough curve was drawn.

52

TEMP.INDICATOR

-------- (\j)-

HEATER

WEIGHINGBALANCE

DRAIN

OVEN

SAMPLING

-----------^----

:V HEATER

WEIGHINGBALANCE

PRESSUREINDICATORDRAIN

SAMPLING

Figure 13. Schematic diagram of a pilot adsorption unit

4 RESULTS AND DISCUSSION

4.1 ADSORPTION ISOTHERMS

4.1.1 Adsorption Isotherm of Methanol in n-Hexane

The adsorption isotherms for methanol in n-hexane in 13X and 5A at 313 K and 323

K are given in Table 3 to 6 and are as shown in Figure 14 to 17. It can be seen that

all four isotherms exhibited Langmuir-type isotherms which has an initial steep slope

and then flattens into a plateau at saturation. The degree of steepness of the isotherm

curves at low concentration range represented near step-change behavior which

indicates an extremely favourable adsorption of the zeolites for methanol adsorbates.

The capacities of the zeolites were found to range from 0.22 to 0.23 g/g of zeolite.

The amount adsorbed was calculated based on the following expression:

While it is acknowledged that in view of their molecular size both methanol and

n-hexane can penetrate into either the 13X or 5A zeolites, the very strong interaction

between the methanol adsorbates with the zeolite due to the highly polar nature as

compared to n-hexane would allow the methanol molecules to be completely

adsorbed and hence displaced the n-hexane from the pores of the zeolite. Hence ,

direct calculation of the amount adsorbed without the need to determine the surface

excess is possible.

54

Studies carried out by P.Salvador et al. [20] on the adsorption of methanol vapour on

a sodium Y zeolite and a decationated zeolite at 293 K gave apparent capacities of

0.24 g/g of zeolite and 0.32 g/g of zeolite respectively. Total pore volumes of the

13X and 5A zeolite which were experimentally determined from nitrogen adsorption

( a sample data sheet is as given in Appendix E) and calculated using Dubinin's

method were found to be between 0.254 cm3/g and 0.209 cm3/g respectively. From

known density values of methanol, 0.7733 g/cm3 at 313 K and 0.7637 g/cm3 at 323

K, the calculated amount which can theoretically be adsorbed should be about 0.19 to

0.20 g/g of zeolite for 13X and 0.16 g/g of zeolite for 5A. Taking into account the

binder which may not have significant adsorption capacity, it may be even less. Both

values were found to be less than the experimentally determined amount. Adsorption

carried out at different temperatures does not seem to have a significant impact on

the capacity.

In order to validate the contribution of adsorption by binders, vapour phase

adsorptions of pure component on 13X and 5 A zeolites were carried out. Results of

the vapour phase adsorption are as given in Appendix F. The adsorption capacities

were found to be 0.21 g/g of 13X zeolite and 0.18 g/g of 5A zeolite at 313 K and

323 K which indicate that the binders may in someway contribute to the adsorption

capacity. A comparison of the adsorption capacity of 13X and 5A for methanol in

n-hexane at 313 K and 323 K is given in Table 7.

55

Table 3. Adsorption isotherm data of methanol in n-hexane at 313K (13X)

Methanol(g)

n-Hexane(g)

TotalSample

(g)Mass Fraction of Methanol

in Fliud After Adsorption

Methanol in Fluid After Adsorption

(g)

MolecularSieve

(g)

AmountAdsorbed

(g/g)FluidPhaseCone.(g/cm3)

nfu Cm n/m z q f

0.0000 0.0000 0.0000 0.000 0.000 0.0000 0.00 0.0000

0.5366 99.5756 100.1122 0.000 0.000 10.3606 0.05 0.0000

1.1234 98.8660 99.9894 0.000 0.000 10.3606 0.11 0.0000

1.6523 98.1472 99.7995 0.000 0.000 10.3606 0.16 0.0000

2.3202 97.3549 99.6751 0.023 0.022 10.3606 0.22 0.0001

2.9565 96.6725 99.6290 0.535 0.520 10.3606 0.24 0.0034

4.2921 95.8971 100.1892 1.970 1.927 10.3606 0.23 0.0127

4.7748 95.2069 99.9817 2.480 2.421 10.3606 0.23 0.0159

Table 4. Adsorption isotherm data of methanol in n-hexane at 323K (13X)

Methanol(g)

n-Hexane(g)

TotalSample

(g)

Mass Fraction of Methanol in

Fliud After Adsorption

Methanol in Fluid After Adsorption

(g)

MolecularSieve

(g)

AmountAdsorbed

(g/g)

FluidPhaseCone.(g/cm3)

™°m rr/u Cm n/m z q f

0.0000 0.0000 0.0000 0.000 0.000 0.0000 0.00 0.00000.1571 29.8247 29.9817 0.000 0.000 3.0339 0.05 0.00000.2933 28.8002 29.0932 0.000 0.000 2.9095 0.10 0.00000.4761 31.0147 31.4907 0.004 0.001 2.7687 0.17 0.00000.4661 22.5162 22.9822 0.026 0.006 2.3531 0.20 0.0002

0.6074 22.6474 23.2544 0.189 0.043 2.6232 0.22 0.0012

0.6672 21.3774 22.0444 0.441 0.095 2.6437 0.22 0.0028

56

Table 5. Adsorption isotherm data of methanol in n-hexane at 313K (5 A)

Methanol(g)

n-Hexane(g)

TotalSample

(g)

Mass Fraction of Methanol in

Fliud After Adsorption

Methanol in Fluid After Adsorption

(g)

MolecularSieve

(g)

AmountAdsorbed

(g/g)

FluidPhaseCone.(g/cm3)

m°m nfu Cm rrlm z q f

0.0000 0.0000 0.0000 0.000 0.000 0.0000 0.00 0.0000

0.1261 24.0790 24.2051 0.000 0.000 2.4874 0.05 0.0000

0.2767 26.0490 26.3257 0.000 0.000 2.6135 0.11 0.0000

0.4808 30.5816 31.0624 0.052 0.016 3.1155 0.15 0.0003

0.5496 25.8493 26.3989 0.192 0.050 2.6752 0.19 0.0012

0.5850 22.5637 23.1487 0.258 0.058 2.2568 0.23 0.0017

0.9453 30.2538 31.1991 0.988 0.302 3.1639 0.20 0.0063

0.8894 24.4998 25.3892 1.449 0.360 2.5390 0.21 0.0093

Table 6. Adsorption isotherm data of methanol in n-hexane at 323K (5A)

Methanol(g)

n-Hexane(g)

TotalSample

(g)

Mass Fraction of Methanol

in Fliud After Adsorption

Methanol in Fluid After Adsorption

(g)

MolecularSieve

(g)

AmountAdsorbed

(g/g)

FluidPhaseCone.(g/cm3)

™°m nfu Cm n/m z q f

0.0000 0.0000 0.0000 0.000 0.000 0.0000 0.00 0.0000

0.1270 24.0716 24.1986 0.000 0.000 2.4993 0.05 0.0000

0.2493 24.7045 24.9538 0.000 0.000 2.5342 0.10 0.0000

0.4371 27.6871 28.1242 0.015 0.004 2.8129 0.15 0.0001

0.5712 26.6420 27.2132 0.042 0.011 2.7666 0.20 0.0003

0.7660 29.6669 30.4329 0.102 0.030 3.1636 0.23 0.0006

0.7769 25.1365 25.9134 0.816 0.207 2.7139 0.21 0.0052

0.9922 27.1638 28.1560 1.463 0.403 2.8144 0.21 0.0093

Table 7. Comparison of zeolite capacity (methanol)

Temperature K 13X(g/g) 5A(g/g)

Experimental (liquid 313 0.23 0.21phase) 323 0.22 0.21

Calculation (using 313 0.20 0.16microporous volume) 323 0.19 0.16

Vapour Phase 313 0.21 0.18

323 0.21 0.18

It seems that the differences between the different sets of value may be due to

problems of calibration of chromatographic methods which introduce errors in the

57

way of calculating the amount of methanol adsorbed.

58

Am

ount

Ads

orbe

d (cj

/g)

Am

ount

Ads

orbe

d (g/

g)

Figure 14. Amount of methanol adsorbedagainst fluid concentration (313 K) - 13X

Figure .15.. Amount of methanol adsorbed ' against fluid concentration (323 K) - 13X

. . i ■

0 0.0005 0.001 0.0015 0.002 0.0025 0.003Fluid Concentration (g/cm3)

59

Am

ount

Ads

orbe

d (g/

g)

Am

ount

Ads

orbe

d (g/

g)Figure 16. Amount of methanol adsorbedagainst fluid concentration (313 K) - 5A

0 0.002 0.004 0.006 0.008 0.01Fluid Concentration (g/cm3)

Figure 17. Amount of methanol adsorbed against fluid concentration (323 K) - 5A

0 0.002 0.004 0.006 0.008 0.01Fluid Concentration (g/cm3)

60

4.1.2 Adsorption Isotherm of 1-Hexene in n-Hexane

The adsorption isotherms for 1-hexene in n-hexane in 13X and 5A at 313 K and 323

K are given in Tables 8 to 11 and Figures 18 to 21. In this case, initial calculation

based on the expression used for methanol did not provide satisfactory results. It is

assumed that there is competitive adsorption of both 1-hexene and n-hexane in the

pores of the zeolite. Based on this assumption, a surface excess expression was used

to calculate the individual adsorption isotherm of 1-hexene in n-hexane at

temperatures of 313 K and 323 K as well as in the 13X and 5A zeolites. The

expression used was:

I"‘a +Mj}Xa

1 ~XA + $BXA

The total capacity of 1-hexene in n-hexane for 13X were found to be 0.19 g/g of

zeolite and 0.17 g/g of zeolite at 313 K and 323 K. Assuming that the micropore

volume of 13X to be 0.254 cm3 /g, the theoretical amount adsorbed calculated by

multiplying the volume with the density of 1-hexene at 313 K and 323 K would give

0.14 g/g of zeolite at both temperatures which again is not in agreement with

experimental results. This conflict between theoretical and experimental results may

again be resolved, if the binders are consider to have some adsorption capacity as

mentioned in the case of methanol in n-hexane, perhaps between 0.02-0.04 g/g of

zeolite X, this being the difference between the calculated and experimental.

For the case of 1-hexene in n-hexane adsorption in 5A zeolite, the capacity was

found to be 0.14 g/g of zeolite at 313 K and 323 K . Again assuming the micropore

volume as determined by nitrogen adsorption and Dubinin's calculation to be 0.209

61

cm3/g, the theoretical amount of 1-hexene adsorbed at saturation is 0.11 g/g of

zeolite at both temperatures. Here again the same situation of large differences

between theoretical and experimental values.

Similar adsorption study of binary mixture of olefin in alkane [21] on 13X zeolite in

vapour phase has shown preferential adsorption of olefin for all pressures.

Vapour phase adsorption of pure 1-hexene on the 13X and 5A zeolites provided

adsorption capacity of about 0.17 g/g of zeolite for 13X and 0.13 g/g for 5 A at 313

K and 323 K. A comparison of the adsorption capacity of 13X and 5 A for 1-hexene

in n-hexane at 313 K and 323 K is given in Table 12.

Table 8. Adsorption isotherm data of 1-hexene in n-hexane at 313K (13X)

Mixtures (g) Mol. Sieves (g)

GC Results Before

GC Results After

ActualBefore

ActualAfter

SurfaceExcess

AmountAdsorbed

ms z (wt%) (wt%) Xa r n0.0000 0.0000 0.000 0.000 0.000 0.000 0.000 0.000

27.3129 2.8820 4.053 3.646 5.014 4.510 0.048 0 055

20.3372 2.2662 9.017 7.962 10.010 8.839 0.105 0.120

26.6872 2.6989 18.242 17.068 20.032 18.743 0.127 0.159

26.8761 2.6848 29.846 28.695 29.997 28.877 0.112 0.161

26.4443 2.6226 37.086 36.027 40.020 38.877 0.115 0.182

22.0689 2.2010 49.342 48.261 50.109 49.011 0.110 0.194

21.1143 2.0938 56.300 55.387 59.739 58.770 0.098 0.199

25.6085 2.4399 66.117 65.428 69.650 68.924 0.076 0.195

28.1682 2.9257 77.536 76.982 80.152 79.579 0.055 0.192

25.3705 2.5122 86.804 86.431 89.952 89.565 0.040 0.193

62

Table 9. Adsorption isotherm data of 1-hexene in n-hexane at 323K (13X)

Mixtures (g)

ms

Mol. Sieves (g)

z

GC Results Before

(wt%)

GC Results After

(wt%)

ActualBefore

*5

ActualAfter

Xa

SurfaceExcess

r

AmountAdsorbed

n0.0000 0.0000 0.000 0.000 0.000 0.000 0.000 0.000

22.5740 2.5025 12.009 10.766 10.167 9.115 0.095 0.110

20.0340 1.6830 23.242 22.121 20.420 19.435 0.117 0.150

22.3922 2.8684 33.503 31.871 30.021 28.558 0.114 0.163

19.8268 2.3140 44.141 42.754 40.020 38.762 0.108 0.174

20.2598 2.9005 63.942 62.730 60.015 58.878 0.079 0.180

19.7246 2.7835 81.542 81.200 79.956 79.620 0.024 0.159

22.4226 2.8995 89.970 89.778 89.657 89.465 0.015 0.167

22.6041 2.7704 93.477 93.397 93.807 93.727 0.007 0.166

Table 10. Adsorption isotherm data of 1-hexene in n-hexane at 313K (5A)

Mixtures (g)

ms

Mol. Sieves (g)

z

GC Results Before

(wt%)

GC Results After

(wt%)

ActualBefore

A3

ActualAfter

A3

SurfaceExcess

r

AmountAdsorbed

h0.0000 0.0000 0.000 0.000 0.000 0.000 0.000 0.000

31.0737 3.1321 6.575 5.346 5.101 4.147 0.095 0.100

25.1991 2.5623 12.359 11.012 10.092 8.994 0.108 0.120

21.0237 2.1966 23.568 22.098 20.037 18.789 0.119 0.144

25.0752 2.5288 34.235 33.091 30.176 29.168 0.100 0.138

26.2476 2.6231 44.199 43.245 40.155 39.288 0.087 0.138

35.0638 3.5675 63.733 62.989 59.950 59.250 0.069 0.146

28.1562 2.7992 81.285 81.077 79.862 79.658 0.021 0.124

24.1001 2.4944 90.042 89.864 89.797 89.801 0.017 0.134

63

Table 11. Adsorption isotherm data of 1-hexene in n-hexane at 323K (5 A)

Mixtures (g) Mol. Sieves (g)

GC Results Before

GC Results After

ActualBefore

ActualAfter

SurfaceExcess

AmountAdsorbed

ms z (wt%) (wt%) Xa xA r h

0.0000 0.0000 0.000 0.000 0.000 0.000 0.000 0.000

25.9364 2.4949 6.260 4.919 5.124 4.026 0.114 0.119

27.2457 2.6743 12.126 10.695 10.000 8.820 0.120 0.132

29.2007 2.8911 23.185 21.643 20.024 18.692 0.135 0.159

25.2359 2.5588 33.858 32.644 30.056 28.977 0.106 0.144

25.2698 2.5945 43.723 42.690 39.892 38.950 0.092 0.142

23.2721 2.3991 63.533 62.697 59.859 59.071 0.076 0.153

24.6821 2.5259 81.358 81.058 80.000 79.703 0.029 0.133

27.9812 2.8174 89.912 89.640 89.877 89.604 0.027 0.143

27.1901 2.6543 94.141 94.032 94.837 94.727 0.011 0.134

Table 12. Comparison of zeolite capacity (1-hexene)

Temperature K 13X(g/g) 5A(g/g)

Experimental (in liquid 313 0.19 0.14phase) 323 0.17 0.14

Calculation (using 313 0.14 0.11microporous volume) 323 0.14 0.11

Vapour Phase (using 313 0.17 0.13thermogravimetry)

323 0.17 0.13

64

Figure 18. Amount of 1-hexene adsorbedagainst fluid concentration (313 K) - 13X

0 20 40 60 80 100Fluid Concentration (g/cm3)

Figure 19. Amount of 1-hexene adsorbed against fluid concentration (323 K) - 13X

' 0.25

Fluid Concentration (g/cm3)

65

Am

ount

Ads

orbe

d (g/

g)

Am

ounl

Ads

orbe

d WFigure 20. Amount of 1-hexene adsorbed-against fluid concentration (313 K) - 5A

Fluid Concentration (g/cm3)

Figure 21. Amount of 1-hexene adsorbed against fluid concentration (323 K) - 5A

Fluid Concentration (g/cm3)

66

4.1.3 Modelling of Isotherms

As mentioned in section 2.2.5, a modelling of the isotherms using the Langmuir and

Langmuir-Freundlich expressions was carried out using a version 3 curve fitting

software named Kaleidagraph running on a Macintosh II CX system 7.0. Curve

fitting was computed with the use of the Levenberg-Marquardt algorithm. The

results of the modelling are as shown in Figure 14 to 21 and the parameters k and a

obtained are as given in Table 13. From the figures it can be seen that both

expressions describe well the data points. For simplicity, the Langmuir expression

should be preferred since it involves only one parameter k, whereas the Langmuir

Freundlich requires knowledge of two parameters namely k and a . Furthermore the

variation of parameters k and a does not seem coherent so the Langmuir model is

more reliable to fit the data.

Table 13. Summary of Langmuir and Langmuir-Freundlich constants

Component Temperature

KZeolite Langmuir

k

Langmuir Freundlich

k aMethanol/n-Hexane 313 13X 2.20E4 6.82E3 0.8800MethanoL/n-Hexane 323 13X 5.21E4 9.68E9 2.1200

Methanol/n-Hexane 313 5A 1.99E4 2.09E3 0.7700

Methanol/n-Hexane 323 5A 1.90E4 1.50E5 1.2200

1-Hexene/n-Hexane 313 13X 4.03E4 1.70E-1 1.4100

1-Hexene/n-Hexane 323 13X 3.20E4 1.41E-2 2.2000

1-Hexene/n-Hexane 313 5A 7.17E4 2.61E-1 1.5700

1-Hexene/n-Hexane 323 5A 8.61E4 8.54E-2 2.8100

67

4.2 BREAKTHROUGH CURVES

4.2.1 Breakthrough Curves of Methanol in 1-Hexene or n-Hexane at Various

Operating Conditions

The breakthrough curves were measured at various inlet concentration C;

flowrates, temperatures and column length. The results are given respectively in

table 14 to 18 and figures to 26 for Methanol and in tables 19 to 21 and figures 27

to 29 for 1-hexene. The beds used here are made of one or three columns, each

being L0=100 cm long and filled with 191.6 cm3 of adsorbent. The elapsed time

represented in the processed volume V expressed in bed volume only for

convenience. Two points are taken from each curve in order to evaluate the

column efficiency. The breakthrough volume Vb is defined as the one

corresponding to 0.01% outlet concentration C0. The stoechiometric volume V^

is defined as the one corresponding to a 50% outlet concentration. These data are

given tables 22 and 23 for all experiments. One can see that the solute nature and

inlet concentration as well as the column length are the parameters having the most

influence on Vb and Vst0: this is to be expected since the mean position of the front

is a function of the bed fluid volume and thermodynamic equilibrium data (23). All

the experimental results are also represented on figure 30 and 31 respectively for

methanol and 1-hexene, using the following non dimensional variables : and j-r-.

This representation is more convenient to see the influence of the flowrate on the

more or less dispersed character of the curves.

68

The Van Demter plot is a better way to characterized this influence. In this plot,

one draw the HETP of the column versus the flowrate. The HETP is defined as

follows (23):

HETP = 4-£ r

with L the total column length, a and g respectively the first and second moments

correponding to the breakthrough curve. In (24) Villermaux gives a simple

graphical technique to estimate the ratio 2- from the step response of the system

when the impulse is nearly Gaussian. In our case, this leads to the following

relation, cy and g being expressed as processed volume instead of elapsed time :

HETP = 0,64 • n • U •

Where n is the number of L0 = 100 cm length columns (n=l or 3). HETP values are

given in table 22 and the corresponding Van Demter plot is represented on figure

32. One can see that for a given solute, the plot is similar to thoose classicaly

described (23) : the HETP reaches a minimum for a given flowrate. In our case, the

value of this flowrate seems to be independant of the solute. This conclusion must

be confirmes because ponts located on the left hand side of the minimum for

methanol are not avalaible. This minimum is reached for a flowrate of about 11

g/mn. If the HETP is taken as an optimization criteria, a flowrate of 11 g/mn is the

optimal one for the beds sudied here.

69

Table 14. Adsorption data of 0.56 wt % methanol in n-hexane on molecular sieves at

313 K and flowrate of 18.6 gram/min (1 column, 13X) - run no 1

Density @313 K (g/cm3), MeOH

n-C6

Density of Mixture (g/cm3)

Initial Concentration (wt %)

Pump Setting

Flow Rate (g/min)

Empty Bed Volume (cm3)

Weight of Catalyst (g)

0.7733

0.6425

0.6432

0.5610

0.5

18.6

191.6

131

Sample Time Bal. Rdg. Wt. Diff. Cum. Wt Bed Vol. Eff. Cone

No (min) (g) (g) (g) (wt%)Start 0.00 10822

1st Drop 4.84 10732 90 90 0.73 0.0002 10.32 10630 102 192 1.56 0.0003 2032 10427 203 395 3.21 0.0004 40.32 10083 344 739 6.00 0.0005 60.32 9677 406 1145 9.29 0.0006 7032 9475 202 1347 10.93 0.0007 80.32 9268 207 1554 12.61 0.0008 110.32 8688 580 2134 1732 0.0009 140.32 8122 566 2700 21.91 0.00010 16032 7762 360 3060 24.83 0.00011 176.32 7476 286 3346 27.15 0.05712 177.32 7458 18 3364 27.30 0.07213 17832 7443 15 3379 27.42 0.09514 17932 7424 19 3398 27.57 0.11315 18032 7408 16 3414 27.70 0.13416 183.32 7356 52 3466 28.12 0.22117 186.32 7303 53 3519 28.55 0.28918 189.32 7251 52 3571 28.98 0.34619 194.32 7163 88 3659 29.69 0.43020 199.32 7073 90 3749 30.42 0.486

21 204.32 6985 88 3837 31.14 0.52522 20932 6898 87 3924 31.84 0.56423 219.32 6722 176 4100 33.27 0.54924 239.32 6368 354 4454 36.14 0.546

70

Table 15 Adsorption data of 1.52 wt % methanol in n-hexane on molecular sieves at

313 K and flowrate of 19.5 gram/min (1 column, 13X) - run no 2

Density @ 313 K (gZcm3), MeOH

n-C6

Density of Mixture (g/cm3)

Initial Concentration (wt %)

Pump Setting

Flow Rate (g/min)

Empty Bed Volume (cm3)

Weight of Catalyst (g)

0.7733

0.6425

0.6445

1.5248

0.5

19.5

191.6

131

Sample Time Bal. Rdg. WtDiff. Cum. Wt Bed Vol. Eff. Cone

No (min) (g) (g) (g) (wt%)

Start 0.00 11128

1st Drop 4.62 11038 90 90 0.73 0 000

2 33.80 10469 569 659 5.34 0 000

3 53.80 10049 420 1079 8.74 0000

4 58.80 9959 90 1169 9.47 0000

5 63.80 9865 94 1263 10.23 0 009

6 67.80 9786 79 1342 10.87 0 489

7 68.80 9768 18 1360 11.01 0337

8 69.80 9750 18 1378 11.16 0 5~39 70.80 9731 19 1397 1131 071910 71.80 9712 19 1416 11.47 C a

11 72.80 9694 18 1434 11.61 0 Xftl12 74.80 9658 36 1470 11.90 1 041

13 76.80 9619 39 1509 12.22 1 1X514 79.80 9563 56 1565 12.67 1301

15 82.80 9504 59 1624 13.15 14:3

16 85.80 9445 59 1683 13.63 1 35517 90.80 9352 93 1776 14.38 13:8

18 95.80 9254 98 1874 15.18 1 495

19 105.80 9065 189 2063 16.71 1 510

71

Table 16 Adsorption data of 1.50 wt % methanol in n-hexane on molecular sieves at

313 K and flowrate of 41.0 gram/min (1 column, 13X) - run no 3

Density @313 K (g/cm3), MeOH

n-C6

Density of Mixture (g/cm3 )

Initial Concentration (wt %)

Pump Setting

Flow Rate (g/min)

Empty Bed Volume (cm3)

Weight of Catalyst (g)

0.7733

0.6425

0.6445

1.5009

1.5

41.0

191.6

131

Sample Time Bal. Rdg. WtDiff. Cum. Wt Bed Vol. EfF. Cone

No (min) (g) (g) (g) (wt%)

Start 0.00 8044

1st Drop 2.20 7954 90 90 0.73 0.000

2 9.27 7664 290 380 3.08 0.000

3 14.27 7452 212 592 4.79 0.000

4 19.27 7241 211 803 6.50 0.0005 24.27 7033 208 1011 8.19 0.000

6 26.27 6949 84 1095 8.87 0.000

7 28.27 6888 61 1156 9.36 0.015

8 29.27 6827 61 1217 9.86 0.087

9 30.27 6785 42 1259 10.20 0.233

10 31.27 6744 41 1300 10.53 0.388

11 32.27 6702 42 1342 10.87 0.534

12 33.27 6662 40 1382 11.19 0.627

13 34.27 6621 41 1423 11.52 0.710

14 35.27 6579 42 1465 11.86 0.847

15 36.27 6540 39 1504 12.18 0.916

16 38.27 6458 82 1586 12.84 1.089

17 40.27 6377 81 1667 13.50 1.170

18 42.27 6296 81 1748 14.16 1.277

19 44.27 6215 81 1829 14.81 1.340

20 47.27 6095 120 1949 15.78 1.414

21 50.27 5974 121 2070 16.76 1.462

22 53.27 5854 120 2190 17.73 1.488

23 59.27 5613 241 2431 19.69 1.499

72

Table 17 Adsorption data of 1.48 wt % methanol in n-hexane on molecular sieves at_____________313 K and flowrate of 31.0 gram/min (3 column, 13X) - run no 4________Density @313 K (g/cm3), MeOH

n-C6Density of Mixture (g/cm3)Initial Concentration (wt %)

Pump SettingFlow Rate (g/min)Empty Bed Volume (cm3)Weight of Catalyst (g)

0.77330.64250.64441.4800

1.531.0574.8384

Sample Time Bal. Rdg. WtDiffi Cum. Wt Bed Vol. EfE ConeNo (min) (8) (g) (g) (wt%)

Start 0.00 119701st Drop 8.71 11700 270 270 2.19 0.000

2 12.74 11575 125 395 3.21 0.0003 16.74 11450 125 520 4.20 0.000 .4 21.74 11294 156 676 5.49 0.0005 26.74 11138 156 832 6.75 0.0006 31.74 10981 157 989 8.01 0.0007 37.74 10795 186 1175 9.51 0.0008 38.74 10763 32 1207 9.78 0.0009 46.74 10515 248 1455 11.79 0.00010 56.74 10203 312 1767 14.31 0.00011 66.74 9894 309 2076 16.80 0.00012 76.74 9583 311 2387 19.32 0.00013 86.74 9272 311 2698 21.84 0.00014 91.74 9117 155 2853 23.10 0.00015 96.74 8964 153 3006 24.36 0.00016 101.74 8810 154 3160 25.59 0.00017 106.74 8655 155 3315 26.85 0.00018 111.74 8500 155 3470 28.11 0.00019 116.74 8346 154 3624 2934 0.00020 121.74 8191 155 3779 30.60 0.00021 123.74 8129 62 3841 31.11 0.00922 124.74 8098 31 3872 3135 0.03623 125.74 8067 31 3903 31.62 0.08124 126.74 8037 30 3933 31.86 0.15225 127.74 8006 31 3964 32.10 0.23326 128.74 7968 38 4002 32.40 0.36127 130.74 7913 55 4057 32.85 0.51628 132.74 7851 62 4119 33.36 0.69829 134.74 7789 62 4181 33.87 0.81830 136.74 7723 66 4247 34.41 0.94931 138.74 7666 57 4304 34.86 1.06232 140.74 7604 62 4366 3537 1.12533 142.74 7542 62 4428 35.85 1.21134 144.74 7481 61 4489 36.36 1.27135 146.74 7419 62 4551 36.87 1.33436 149.74 7326 93 4644 37.62 137037 152.74 7233 93 4737 3837 1.43538 156.74 7110 123 4860 39.36 1.46839 161.74 6956 154 5014 40.62 1.489

73

Table 18 Adsorption data of 1.49 wt % methanol in n-hexane on molecular sieves at323 K and flowrate of 31.2 gram/min (3 column, 13X) - run no 5

Density @ 323

Density ofMixt Initial Concentr Pump Setting Flow Rate (g/mi Empty Bed Voh Weight of Catal

EC (g/cm3 ), MeOH n-C6

ure (g/cm3) ation (wt %)

a)

ime (cm3) yst(g)

0.76370.63300.63491.4890

1.531.2

574.8384

Sample Time Bal. Rdg. WLDiff. Cum. Wt Bed Vol. EfF. ConeNo (min) (g) (g) (g) (wt%)Start 0.00 12482

1st Drop 8.65 12212 270 270 2.19 0.0002 10.22 12163 49 319 2.58 0.0003 17.22 11944 219 538 4.35 0.0004 37.22 11320 624 1162 9.42 0.0005 57.22 10697 623 1785 14.46 0.0006 77.22 10076 621 2406 19.50 0.0007 97.22 9453 623 3029 25.54 0.0008 107.22 9139 314 3343 27.09 00009 117.22 8827 312 3655 29.61 0.00010 119.22 8765 62 3717 30.12 0.00011 121.22 8703 62 3779 30.60 0 00012 122.22 8671 32 3811 30.87 001213 123.22 8640 31 3842 31.11 0 04$14 124.22 8609 31 3873 31.38 0 11015 125.22 8578 31 3904 31.62 0 20016 126.22 8547 31 3935 31.86 027217 127.22 8517 30 3965 32.10 0 39118 129.22 8453 64 4029 32.64 036719 131.22 8390 63 4092 33.15 0 78220 133.22 8329 61 4153 33.63 091321 135.22 8267 62 4215 31.14 1 05322 137.22 8204 63 4278 34.65 1 16123 140.22 8110 94 4372 35.40 1 28624 143.22 8017 93 4465 36.15 1 36725 146.22 7923 94 4559 36.93 1 43226 149.22 7830 93 4652 37.68 1 51927 152.22 7736 94 4746 38.43 1 46228 155.22 7642 94 4840 39.21 1 45629 158.22 7548 94 4934 39.96 1 54330 161.22 7454 94 5028 40.71 1 54031 164.22 7361 93 5121 41.49 1 52532 167.22 7267 94 5215 42.24 1 52233 170.22 7171 96 5311 43.02 1 55534 173.22 7080 91 5402 43.74 1 52835 176.22 6987 93 5495 44.52 1 52836 179.22 6893 94 5589 45.27 1 49537 182.22 6800 93 5682 46.02 1.50738 187.22 6645 155 5837 47.28 1.27439 192.22 6489 156 5993 48.54 1.51940 197.22 6332 157 6150 49.80 1.03241 202.22 6176 156 6306 51.06 1.54342 207.22 6019 157 6463 52.35 1.43843 217.22 5703 316 6779 54.90 1.52544 222.22 5544 159 6938 56.19 1.197

74

Table 19 Adsorption data of 1.51 wt % 1-hexene in n-hexane on

molecular sieves at 313 K and flowrate of 8.7 gram/min (1

column, 13X) - run no la

Density @ 313 K (g/cm3), 1C-6 ' n-C6

Density of Mixture (g/cm3)Initial Concentration (wt %)Pump SettingFlow Rate (g/min)Empty Bed Volume (cm3)Weight of Catalyst (g)

0.65290.64250.64271.5082

0.58.7

191.6131

Sample Time Bal. Rdg. WtDiff. Cum. Wt. Bed Vol. Eff. ConeNo (min) (g) (g) (g) (wt%)Start 0.00 9202

1st Drop 10.34 9112 90 90 0.73 0.0002 10.92 9107 5 95 0.77 0.0003 11.92 9097 10 105 0.85 0.0004 13.92 9079 18 123 1.00 0.0055 14.92 9071 8 131 1.06 0.0096 15.92 9062 9 140 1.14 0.0157 16.92 9053 9 149 1.21 0.0248 18.92 9035 18 167 1.36 0.0429 20.92 9018 17 184 1.49 0.06710 22.92 9001 17 201 1.63 0.10311 24.92 8983 18 219 1.78 0.14412 27.92 8957 26 245 1.99 0.23813 30.92 8931 26 271 2.20 0.33314 33.92 8905 26 297 2.41 0.47615 36.92 8879 26 323 2.62 0.58516 39.92 8853 26 349 2.83 0.73617 42.92 8827 26 375 3.05 0.88818 47.92 8783 44 419 3.40 1.10919 52.92 8739 44 463 3.76 130720 57.92 8696 43 506 4.11 1.40621 63.92 8643 53 559 4.54 1.46522 68.92 8600 43 602 4.89 1.49523 73.92 8557 43 645 5.24 1.51924 78.92 8514 43 688 5.59 1.54225 83.92 8471 43 731 5.94 1.543

75

Table 20. Adsorption data of 1.51 wt % 1-hexene in n-hexane on

molecular sieves at 313 K and flowrate of 10.9 gram/min (3

column, 13X) - run no 2a

Density @313 KCg/cm3), 1-C6 n-C6

Density of Mixture (g/cm3)Initial Concentration (wt %)Pump SettingFlow Rate (g/min)Empty Bed Volume (cm3 )Weight of Catalyst (g)

0.62900.64250.64271.5092

0.510.9

574.8384

Sample Time Bal. Rdg. WtDiff. Cum. WL Bed Vol. EfE ConeNo (min) (g) (g) (g) (wt%)

Start 0.00 114521st Drop 24.77 11182 270 270 2.19 0.000

2 26.97 11158 24 294 2.40 0.0003 29.97 11132 26 320 2.61 0.0004 33.97 11097 35 355 2.88 0.0005 35.97 11080 17 372 3.03 0.0006 38.97 11055 25 397 3.21 0.0007 41.97 11029 26 423 3.45 0.0008 44.97 11004 25 448 3.63 0.0009 47.97 10977 27 475 3.87 0.00010 50.97 10952 25 500 4.05 0.00011 53.97 10927 25 525 4.26 0.00012 56.97 10902 25 550 4.47 0.00013 58.97 10885 17 567 4.59 0.00214 59.97 10876 9 576 4.68 0.00215 61.97 10859 17 593 4.83 0.00216 66.97 10815 44 637 5.16 0.00317 71.97 10774 41 678 5.52 0.00318 76.97 10731 43 721 5.85 0.00319 81.97 10688 43 764 6.21 0.00420 86.97 10647 41 805 6.54 0.00521 91.97 10605 42 847 6.87 0.00422 96.97 10561 44 891 7.23 0.00723 101.97 10520 41 932 7.56 0.00724 106.97 10478 42 974 7.92 0.00825 111.97 10438 40 1014 8.22 0.00926 121.97 10359 79 1093 8.88 0.01627 131.97 10277 82 1175 9.54 0.03328 141.97 10198 79 1254 10.17 0.07229 151.97 10117 81 1335 10.83 0.15830 161.97 10018 99 1434 11.64 0.43931 171.97 9887 131 1565 12.72 0.92732 181.97 9752 135 1700 13.80 1.27033 191.97 9615 137 1837 14.91 1.44034 201.97 9477 138 1975 16.05 1.52435 211.97 9336 141 2116 17.19 1.53936 221.97 9196 140 2256 18.33 1.54437 231.97 9053 143 2399 19.47 1.556

1 38 241.97 8910 143 2542 20.64 1.556

76

SampleNo

Time(min)

Bai. Rdg.(g)

WtDiffi(g)

Cum. WL(g)

Bed Vol. E£E Cone (wt%)

39 251.97 8768 142 2684 21.81 1.55440 261.97 8628 140 2824 22.92 1.55441 281.97 8384 244 3068 24.90 1.540

Table 21. Adsorption data of 1.50 wt % 1-hexene in n-hexane on

molecular sieves at 323 K and flowrate of 13.7 gram/min (1

column, 13X) - run no 3a

Density @ 323 K (g/cm3), 1-C6n-C6

Density of Mixture (g/cm3)Initial Concentration (wt %)Pump SettingFlow Rate (g/min)Empty Bed Volume (cm3)Weight of Catalyst (g)

0.65290.64250.63321.5023

0.513.7

191.6131

Sample Time Bal. Rdg. Wt. Diff. Cum. Wt Bed Vol. Eff. ConeNo (min) (g) (g) (g) (wt%)Start 0.00 9096

1st Drop 6.57 9006 90 90 0.74 0.0002 8.18 8984 22 112 0.92 0.0003 9.18 8975 9 121 1.00 0.0004 10.18 8965 10 131 1.08 0.0005 11.18 8957 8 139 1.15 0.0006 12.18 8948 9 148 1.22 0.0107 14.18 8931 17 165 136 0.0198 16.18 8912 19 184 1.52 0.0389 18.18 8895 17 201 1.66 0.06210 20.18 8877 18 219 1.81 0.09411 22.18 8860 17 236 1.95 0.13712 24.18 8842 18 254 2.09 0.19013 26.18 8823 19 273 2.25 0.25914 28.18 8803 20 293 2.42 034015 30.18 8781 22 315 2.60 0.46116 33.18 8739 42 357 2.94 0.70217 36.18 8691 48 405 334 0.94118 39.18 8643 48 453 3.73 1.11619 44.18 8566 77 530 4.37 131020 49.18 8488 78 608 5.01 1.40121 54.18 8410 78 686 5.65 1.47822 59.18 8334 76 762 6.28 1.51723 64.18 8255 79 841 6.93 1.54224 69.18 8173 82 923 7.61 1.54425 79.18 8011 162 1085 8.94 1.533

77

Table 22. Breakthrough curves for methanol

Run No Pump SetFlowrate

g/min

Cone, wt %

Temp. K Column Stoi. Bed Vol.

Processed(MeOH)

Break­through

Point(MeOH)

HETPcm

1 0.5 19.0 0.5 313 1 28.50 26.89 0,20

2 0.5 19.5 1.5 313 1 11.37 10.23 0,64

3 1.5 41.0 1.5 313 1 11.62 9.20 2,774 1.5 31.0 1.5 313 3 33.54 31.11 1,005 1.5 31.2 1.5 323 3 33.06 30.84 0,87

Table 23. Breakthrough curves for 1-hexene

Run No Pump SetFlowrate

g/min

Cone, wt %

Temp. K Column Stoi. Bed Vol.

Processed(1-Hexene

)

Break­through

Point(1-Hexene

)

HETPcm

la 0.5 8.9 1.5 313 1 2.86 1.07 25,0

2a 0.5 10.9 1.5 313 3 12.33 8.31 20,4

3a 0.5 13.7 1.5 323 1 3.02 1.22 22,73

0.5 -

Bed Volume

Figure 22. Breakthrough curve of methanol effluent concentration against

bed volume processed (run no 1)

78

Effl

uent

Conc

entr

atio

n (w

t%)

^ E

fflue

nt Co

ncen

trat

ion (

wt%

)2

1.5

0.5

-B- -49-10

Bed Volume15 20

igure23. Breakthrough curve of methanol effluent concentration against

bed volume processed (run no 2)

1.4 -

1.2 -

■E—El-

Bed Volume

Figure 24. Breakthrough curve of methanol effluent concentration against

bed volume processed (run no 3)

79

Efflu

ent C

once

ntra

tion (

wt%

) ^

Efflu

ent C

once

ntra

tion (

wt%

)1.6

Bed Volume

25. Breakthrough curve of methanol effluent concentration against

bed volume processed (run no 4)

Bed Volume

Figure 26. Breakthrough curve of methanol effluent concentration against

bed volume processed (run no 5)

80

Effl

uent

Conc

entr

atio

n (w

t%)

0.5 -

Bed Volume

Figure 27. Breakthrough curve of 1-hexene effluent concentration against

bed volume processed - run la

Bed Volume

Figure 28 Breakthrough curve of 1-hexene effluent concentration against

bed volume processed - run 2a

81

Effl

uent

Conc

entr

atio

n (w

t%)

Bed Volume

Figure 29. Breakthrough curve of 1-hexene effluent concentration against

bed volume processed - run 3 a

82

Nor

mal

ized

conc

entr

atio

n

' 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0

Bed volume at stoichiometry

Figure 30 Comparison of normalized breakthrough profiles of methanol in n-hexan

Nor

mal

ized

conc

entr

atio

n

Bed volume at stoichiometry

Figure 31. Comparison of normalized breakthrough profiles of 1-hexene in n-hexane

4.2.3 Breakthrough Curves of Methanol and 1-Hexene in n-Hexane at Various

Operating Conditions

The breakthrough curves determination for methanol and 1-hexene in n-hexane

were carried out at different flowrates, temperatures and adsorbents. The results

obtained are as given in Table 24 to 27 and is illustrated in Figures 33 to 36. A

summary of the operating conditions used are as given in Table 28. From the data,

it can be seen that the breakthrough points obtained for run nos lb, 2b and 3b were

36.09, 31.44 and 33.48 bed volumes processed respectively. The increased in

flowrates from 12. lg/min to 32.6 g/min which is about 2.7 times resulted in a 2.61

reduction in bed volume processed for methanol. 1-hexene which was initially

adsorbed together with n-hexane was eventually displaced by methanol which is

more polar, resulting in an early breakthrough of 1-hexene.

A change in temperature from 313 K (run no 2b) to 323 K (run no 3b) results in an

improvement in 2.04 bed volumes processed which is not in agreement with known

behavior i.e. higher temperature normally results in an earlier breakthrough.

However, if experimental errors were to be taken into considerations, the

difference was not significant.

Finally, a comparison of the effect of adsorbent type was carried out. Run no 3b

carried out with a 13X zeolite was compared with run no 4b which used a 5A

zeolite. The breakthrough points were found to be 33.48 and 26.55 bed volumes

processed respectively. The reduction in bed volume processed was expected

since 5A zeolite has a lower capacity for methanol compared to 13X as determined

earlier in the adsorption isotherm. If a reduction factor of 0.21/0.22 = 0.95 was

85

offered by the 5 A due to the smaller aperature size of the window. Desorption and

readsorption runs were carried out in both cases. Desorption was carried out at

383 K using a 45:55 ratio of 1-hexene to n-hexane for 100 minutes , followed by

readsorption. A typical desorption curve is as shown in Table 29 and Figure 37.

The readsorption breakthroughs for run no 3b and 4b are shown in Tables 30 and

31 and illustrated in Figures 38 and 39. The breakthrough points were found to be

7.95 and 5.43 bed volumes processed indicating a serious reduction in processing

capacities by about 76.3 % and 79.5 % respectively.

used, the amount of bed volume processed for 5A should be 31.81 instead of

26.55. The differences could be attributed to higher mass transfer resistance

Table 24. Adsorption data of 1.48 wt % methanol and 1.49 wt% 1-hexene inn-hexane on molecular sieves at 323 K and flowrate of 12.1 gram/min (3 column, 13X) - run no lb____________________________________

Density @ 323 K (g/cm3), MeOH

1-C6n-C6

Density of Mixture (g/cm3)Initial Concentration MeOH (wt %)Initial Concentration 1-C6 (wt %)

Pump Setting

Flow Rate (g/min)Empty Bed Volume (cm3)

Weight of Catalyst (g)

0.7637

0.64300.63300.6351

1.48301.5118

0.5

12.1574.8384

Sample Time Bal. Rdg. Wt. Diff. Cum. Wt. Bed Vol. Eff. Cone Eff. Cone1C6 MeOH

No (min) (g) (g) (g) (wt%) (wt%)Start 0.00 12614

1st Drop 22.31 12344 270 270 2.00 0.000 0.0002 23.55 12329 15 285 2.34 0.000 0.0003 30.55 12267 62 347 2.85 0.000 0.0004 42.55 12151 116 463 3.81 0.000 0.0005 57.55 11998 153 616 5.07 0.000 0.0006 61.55 11954 44 660 5.43 0.000 0.0007 65.55 11909 45 705 5.79 0.000 0.0008 69.55 11864 45 750 6.15 0.002 0.0009 73.55 11818 46 ■ 796 6.54 0.007 0.00010 78.55 11763 55 851 6.99 0.023 0.00011 83.55 11703 60 911 7.50 0.053 0.00012 88.55 11637 66 977 8.04 0.200 0.000

86

Sample

No

Time

(min)

Bal. Rdg.

(g)

WtDiff.

(g)

Cum. Wt

(g)

Bed Vol. Eff. Cone 1C6

(wt%)

Eff. Cone MeOH

(wt%)13 93.55 11573 64 1041 8.55 0.544 0.00014 98.55 11509 64 1105 9.09 0.856 0.00015 103.55 11446 63 1168 9.60 1.194 0.00016 108.55 11384 62 1230 10.11 1.468 0.00017 113.55 11322 62 1292 10.62 1.663 0.00018 118.55 11261 61 1353 11.13 1.777 0.00019 123.55 11199 62 1415 11.58 1.845 0.00020 128.55 11134 65 1480 12.15 1.889 0.00021 138.55 11013 121 1601 13.17 1.886 0.00022 143.55 10951 62 1663 13.68 1.889 0.00023 153.55 10826 125 1788 14.70 1.874 0.00024 158.55 10764 62 1850 15.21 1.888 0.00025 173.55 10578 186 2036 16.74 1.913 0.00026 183.55 10454 124 2160 17.76 1.924 0.00027 203.55 10207 247 2407 19.77 1.948 0.00028 213.55 10084 123 2530 20.79 1.958 0.00029 223.55 9959 125 2655 21.81 1.956 0.00030 243.55 9710 249 2904 23.85 1.935 0.000

31 263.55 9463 247 3151 25.89 1.916 0.00032 283.55 9214 249 3400 27.93 1.910 0.00033 303.55 8969 245 3645 29.94 1.864 0.00034 323.55 8725 244 3889 31.95 1.885 0.00035 343.55 8479 246 4135 33.99 1.833 0.00036 363.55 8231 248 4383 36.03 1.800 0.00037 369.55 8156 75 4458 36.63 1.715 0.09538 371.55 8132 24 4482 36.84 1.704 0.19139 373.55 8107 25 4507 37.05 1.688 0.29840 375.55 8082 25 4532 37.23 1.654 0.43041 378.55 8045 37 4569 37.56 1.604 0.59742 381.55 8007 38 4607 37.86 1.590 0.85643 384.55 7971 36 4643 38.16 1.559 1.05944 387.55 7935 36 4679 38.46 1.541 1.21745 390.55 7898 37 4716 38.76 1.530 1.27446 393.55 7861 37 4753 39.06 1.518 1.14047 397.55 7812 49 4802 39.45 1.512 1.25948 401.55 7762 50 4852 39.87 1.509 133449 405.55 7713 49 4901 40.29 1.513 1.46850 409.55 7664 49 4950 40.68 1.514 138551 413.55 7615 49 4999 41.07 1.505 1.61152 418.55 7553 62 5061 41.58 1.515 1.65353 423.55 7491 62 5123 42.09 1.512 1.420

54 433.55 7368 123 5246 43.11 1.515 1.522

55 443.55 7246 122 5368 44.10 1.506 1.656

87

Table 25. Adsorption data of 1.52 wt % methanol and 1.49 wt% 1-hexene inn-hexane on molecular sieves at 313 K and flowrate of 31.5 gram/min(3 column, 13X) - run no 2b

Density @ 313 K (g/cm3), MeOH1-C6n-C6

Density of Mixture (g/cm3)Initial Concentration MeOH (wt %)Initial Concentration 1-C6 (wt %)Pump SettingFlow Rate (g/min)Empty Bed Volume (cm3)Weight of Catalyst (g)

0.77330.65290.64250.64461.52481.4896

1.531.5

574.8384

Sample Time Bal. Rdg. Wt. Dig. Cum. Wt Bed Vol. Eff. Cone Eff. Cone

No (min) (g) (g) (g)

1C6

(wt%)MeOH

(wt%)Start

1st Drop0.008.57

1227612006 270 270 2.19 0.000 0.000

2 9.04 11991 15 285 231 0.000 0.0003 11.04 11930 61 346 2.79 0.003 0.0004 13.04 11867 63 409 3.30 0.005 0.0005 15.04 11805 62 471 3.81 0.011 0.0006 17.04 11741 64 535 4.32 0.020 0.0007 19.04 11675 66 601 < 4.86 0.044 0.0008 22.04 11584 91 692 5.61 0.109 0.0009 25.04 11490 94 786 6.36 0.225 0.00010 28.04 11396 94 880 7.14 0.535 0.00011 31.04 11301 95 975 7.89 0.760 0.00012 35.04 11176 125 1100 8.91 1.050 0.00013 39.04 11050 126 1226 9.93 1.303 0.00014 43.04 10924 126 1352 10.95 1.495 0.00015 47.04 10799 125 1477 11.97 1.637 0.00016 52.04 10641 158 1635 13.23 1.757 0.00017 57.04 10484 157 1792 14.52 1.830 0.00018 67.04 10170 314 2106 17.04 1.911 0.00019 77.04 9857 313 2419 19.59 1.955 0.00020 87.04 9540 317 2736 22.14 1.931 0.00021 97.04 9224 316 3052 24.72 1.929 0.00022 107.04 8909 315 3367 27.27 1.889 0.00023 117.04 8591 318 3685 29.85 1.838 0.00024 123.04 8404 187 3872 31.35 1.788 0.00625 124.04 8372 32 3904 31.62 1.772 0.01826 125.04 8340 32 3936 31.86 1.757 0.06327 126.04 8309 31 3967 32.13 1.735 0.14028 127.04 8277 32 3999 32.37 1.715 0.25429 129.04 8214 63 4062 32.88 1.677 0.48330 131.04 8151 63 4125 33.39 1.646 0.69231 133.04 8088 63 4188 33.90 1.613 0.85932 135.04 8025 63 4251 34.41 1.586 1.00933 137.04 7961 64 4315 34.95 1.570 1.12534 140.04 7866 95 4410 35.70 1.541 1.26235 143.07 7771 95 4505 36.48 1.522 1.37036 146.04 7676 95 4600 37.26 1.507 1.43837 149.04 7581 95 4695 38.01 1.504 1.48638 152.04 7486 95 4790 38.79 1.494 1.52839 157.04 7327 159 4949 40.08 1.494 1.55540 162.04 7169 158 5107 41.34 1.493 1.56741 167.04 7011 158 5265 42.63 1.494 1.56442 172.04 6851 160 5425 43.92 1.490 1.55843 177.04 6691 160 5585 45.21 1.495 1.555

88

Table 26. Adsorption data of 1.49 wt % methanol and 1.50 wt% 1-hexene in n-hexane onmolecular sieves at 323 K and flowrate of 32.6 gram/min (3 column, 13X) -run no 3b

Density @ 323 K (gZcm3), MeOH1-C6n-C6

Density of Mixture (g/cm3)Initial Concentration MeOH (wt %)Initial Concentration 1-C6 (wt %)Pump SettingFlow Rate (g/min)Empty Bed Volume (cm3)Weight of Catalyst (g)

0.76370.64300.63300.63511.48901.5014

1.532.6574.8384

Sample Time Bal. Rdg. Wt. Diff. Cum. Wt Bed Vol. Eff. Cone Eff. Cone1C6 MeOH

No (min) GO (g) fe) (wt%) (wt%)Start 0.00 13309

1st Drop 8.28 13039 270 270 2.22 0.010 0.0002 9.42 13002 37 307 2.52 0.008 0.0003 11.42 12939 63 370 3.03 0.015 0.0004 13.42 12876 63 433 3.36 0.012 0.0005 15.42 12813 63 496 4.08 0.025 0.0006 17.42 12750 63 559 4.59 0.041 0.0007 19.42 12687 63 622 5.10 0.069 0.0008 22.42 12593 94 716 5.88 0.159 0.0009 25.42 12498 95 811 6.66 0.307 0.00010 28.42 12404 94 905 7.44 0.597 0.00011 31.42 12309 95 1000 8.22 0.843 0.00012 35.42 12183 126 1126 9.24 1.168 0.00013 39.42 12057 126 1252 10.29 1.434 0.00014 43.42 11931 126 1378 1131 1.615 0.00015 47.42 11806 125 1503 12.36 1.732 0.00016 52.42 11649 157 1660 13.65 1.823 0.00017 57.42 11491 158 1818 14.94 1.859 0.00018 67.42 11177 314 2132 17.52 1.886 0.00019 77.42 10857 320 2452 20.16 1.917 0.00020 87.42 10545 312 2764 22.71 1.893 0.00021 97.42 10226 319 3083 25.35 1.907 0.00022 107.42 9903 323 3406 27.99 1.857 0.00023 117.42 9577 326 3732 30.66 1.833 0.00024 127.42 9249 328 4060 33.36 1.784 0.00325 128.42 9216 33 4093 33.63 1.772 0.02126 129.42 9182 34 4127 33.93 1.759 0.08127 130.42 9150 32 4159 34.17 1.737 0.17928 131.42 9116 34 4193 34.47 1.716 0.29829 133.42 9050 66 4259 35.01 1.681 0.51630 135.42 8983 67 4326 35.55 1.649 0.71331 137.42 8916 67 4393 36.09 1.619 0.89232 140.42 8815 101 4494 36.93 1.584 1.05933 143.42 8714 101 4595 37.77 1.556 1.21734 146.42 8613 101 4696 38.58 1.532 1.33735 149.42 8512 101 4797 39.42 1.515 1.39936 152.42 8410 102 4899 40.26 1.512 1.44437 155.42 8308 102 5001 41.10 1.505 1.49538 158.42 8206 102 5103 41.94 1.504 1.53739 161.42 8104 102 5205 42.78 1.505 1.51640 164.42 8002 102 5307 43.62 1.505 1.50141 167.42 7900 102 5409 44.46 1.503 1.48942 172.42 7728 172 5581 45.87 1.506 1.50443 177.42 7557 171 5752 47.28 1.503 1.52244 182.42 7385 172 5924 48.69 1.504 1.54045 187.42 7213 172 6096 50.10 1.504 1.48646 192.42 7040 173 6269 51.51 1.505 1.45947 197.42 6868 172 6441 52.92 1.504 1.432

89

Table 27. Adsorption data of 1.49 wt% methanol and 1.49 wt% 1 -hexene in n-hexane on molecular sieves at 323 K and flowrate of 30.9 gram/min (3 columns, 5A) - run no 4b

Density @ 323 K (g/cm3 ), MeOH

1-C 6

n-C6

Density of Mixture (g/cm3)

Initial Concentration MeOH (wt %)

Initial Concentration 1-C6 (wt %)

Pump Setting

Flow Rate (g/min)

Empty Bed Volume (cm3)

Weight of Catalyst (g)

0.7637

0.6430

0.6330

0.6351

1.4860

1.4915

1.5

30.9

574.8

395

Sample Time Bal. Rdg. Wt. Diff. Cum. Wt Bed Vol. E£f. Cone EfF. Cone1C6 MeOH

No (min) (g) (g) (g) (wt%) (wt%)

Start 0.00 11816

1st Drop 8.74 11546 270 270 2.22 0.000 0.000

2 10.61 11488 58 328 2.70 0.001 0.000

3 12.61 11424 64 392 3.22 0.003 0.000

4 14.61 11368 56 448 3.68 0.006 0.000

5 16.61 11308 60 508 4.17 0.012 0.000

6 18.61 11249 59 567 4.66 0.019 0.000

7 20.61 11190 59 626 5.14 0.031 0.000

8 22.61 11132 58 684 5.62 0.046 0.000

9 24.61 11070 62 746 6.13 0.067 0.000

10 27.61 10981 89 835 6.86 0.117 0.000

11 30.61 10894 87 922 7.58 0.176 0.000

12 33.61 10806 88 1010 8.30 0.267 0.000

13 37.61 10688 118 1128 9.27 0.427 0.000

14 41.61 10569 119 1247 10.25 0.580 0.000

15 46.61 10414 155 1402 11.52 0.473 0.000

16 51.61 10263 151 1553 12.76 0.889 0.000

17 56.61 10111 152 1705 14.01 1.159 0.000

18 66.61 9810 301 2006 16.49 1.488 0.000

19 76.61 9508 302 2308 18.97 1.665 0.000

20 86.61 9204 304 2612 21.47 1.738 0.000

21 96.61 8902 302 2914 23.95 1.794 0.000

22 106.61 8592 310 3224 26.49 1.849 0.006

23 110.61 8469 123 3347 27.51 1.837 0.093

90

Sample Time Bal. Rdg. WtDiff. Cum. Wt. Bed Vol. Eff. Cone 1C6

EfF. Cone MeOH

No (min) (g) (g) (g) (wt%) (wt%)

25 112.61 8406 31 3410 28.02 1.824 0.167

26 113.61 8375 31 3441 28.28 1.813 0.203

27 114.61 8344 31 3472 28.53 1.811 0.248

28 115.61 8313 31 3503 28.79 1.801 0.280

29 116.61 8281 32 3535 29.05 1.796 0.313

30 118.61 8220 61 3596 29.55 1.754 0.361

31 120.61 8155 65 3661 30.09 1.739 0.439

32 122.61 8092 63 3724 30.60 1.753 0.570

33 124.61 8028 64 3788 31.13 1.739 0.606

34 126.61 7967 61 3849 31.63 1.724 0.627

35 129.61 7872 95 3944 32.41 1.702 0.746

36 132.61 7778 94 4038 33.18 1.685 0.788

37 135.61 7683 95 4133 33.96 1.664 0.818

38 138.61 7589 94 4227 34.74 1.647 0.901

39 142.61 7462 127 4354 35.78 1.628 1.071

40 146.61 7338 124 4478 36.80 1.608 1.056

41 150.61 7213 125 4603 37.83 1.587 1.110

42 154.61 7087 126 4729 38.86 1.573 1.155

43 158.61 6962 125 4854 39.89 1.556 1.197

44 162.61 6836 126 4980 40.93 1.538 1.235

45 166.61 6708 128 5108 41.98 1.548 1.301

46 171.61 6549 159 5267 43.28 1.537 1.334

47 176.61 6389 160 5427 44.60 1.527 1.426

48 181.61 6226 163 5590 45.94 1.532 1.343

49 186.61 6063 163 5753 47.28 1.512 1.337

50 191.61 5900 163 5916 48.62 1.515 1.379

51 196.61 5735 165 6081 49.97 1.523 1313

Table 28. Bed volume processed of methanol-1 -hexene-n-hexane at various operating conditions

Run No Pump Set Flowrateg/min

Cone, wt % Temp. K Column Stoi. Bed Vol. Processed (MeOH)

BreakthroughPoint

(MeOH)lb 1.5 12.1 I.5/1.5 323 3 37.74 36.092b 1.5 31.5 1.5/1.5 313 3 33.60 31.44

3b 1.5 32.6 1.5/1.5 323 3 35.76 33.48

4b 1.5 30.9 1.5/1.5 323 3 32.37 26.55

91

Effl

uent

Conc

entr

atio

n (w

t%)

^ E

fflue

nt Co

ncen

trat

ion (

wt%

)

1-Hexene Methanol0.5 -

fe^xccocorjxoxooc>o-ck>oo-o—4—e—e—&

Bed Volume

igure 33. Breakthrough curves of methanol-1 -hexene in n-hexane - ran no lb

1-Hexene Methanol0.5 -

■0—0 10—0—$■

Bed Volume

Figure 34. Breakthrough curves of methanol-1 -hexene in n-hexane -ran no 2b

92

Effl

uent

Conc

entr

atio

n (w

t%)

^ Ef

fluen

t Con

cent

ratio

n (w

t%)

2.5

1.5

0.5 - 1-Hexene

'0 0 0 -C-' 0—^30

Bed Volume60

igure 35. Breakthrough curves of methanol-1 -hexene in n-hexane - run no 3b

Methanol1-Hexene

Bed Volume

Figure 36. Breakthrough curves of methanol-l-hexene in n-hexane -run no 4b

93

Table 29 Desorption data of 1.49 wt % methanol and 1.50 wt% 1-hexene inn-hexane on molecular sieves at 383 K and flowrate of 28.2 gram/min(3 column, 13X) - run no 3b

Density @383 K (g/cm3 ), 1-C6n-C6

Density of Mixture (g/cm3)Initial Concentration MeOH (wt %)Initial Concentration 1-C6 (wt %)Pump SettingFlow Rate (g/min)Empty Bed Volume (cm3)Weight of Catalyst (g)

0.56270.55610.5591

45.000055.0000

1.528.2574.8384

Sample Time Bal. Rdg. WtDiff. Cum. Wt. Bed Vol. EfF. Cone EfF. Cone1C6 MeOH

No (min) (g) (g) (g) (wt%) (wt%)Start 0.00 8901

1st Drop 1.08 8866 35 35 0.33 1.528 1.2382 2.00 8840 26 61 0.57 1.510 1.2833 3.00 8813 27 88 0.82 1.511 1.7434 4.00 8786 27 115 1.07 1.517 2.1845 5.00 8758 28 143 133 1.520 2.0386 6.00 8731 27 170 1.59 1.517 2.0657 7.00 8704 27 197 1.84 1.516 2.1168 8.00 8677 27 224 2.09 1.510 2.0959 10.00 8622 55 279 2.60 1.526 2.04110 12.00 8566 56 335 3.13 7.117 2.04111 14.00 8511 55 390 3.64 33.853 2.82312 16.00 8456 55 445 4.15 42.990 2.18713 18.00 8400 56 501 4.68 43.930 1.51314 20.00 8342 58 559 5.22 44.002 1.20015 22.00 8287 55 614 5.73 44.063 1.08916 24.00 8230 57 671 6.26 44.100 1.161

•17 26.00 8173 57 728 6.80 44.265 0.66518 28.00 8116 57 785 7.33 44.294 0.57619 30.00 8058 58 843 7.87 44.361 0.50720 32.00 8001 57 900 8.40 44.440 0.44521 34.00 7943 58 958 8.94 44.412 0.40322 36.00 7887 56 1014 9.47 44.077 0.35523 38.00 7830 57 1071 10.00 44.439 0.34024 40.00 7774 56 1127 10.52 44.381 0.31625 42.00 7716 58 1185 11.06 44.443 0.30426 44.00 7659 57 1242 11.59 44.487 0.29527 46.00 7602 57 1299 12.13 44385 0.28328 48.00 7545 57 1356 12.66 44.479 0.27529 50.00 7488 57 1413 13.19 44.505 0.26330 55.00 7346 142 1555 14.52 44.380 0.23931 60.00 7204 142 1697 15.84 44.530 0.22432 65.00 7061 143 1840 17.18 44.402 0.21533 70.00 6921 140 1980 18.48 44.502 0.20634 75.00 6781 140 2120 19.79 44.519 0.20035 80.00 6640 141 2261 21.11 44.566 0.19736 85.00 6500 140 2401 22.41 44.493 0.19137 90.00 6359 141 2542 23.73 44.534 0.18538 95.00 6218 141 2683 25.05 44.487 0.17939 100.00 6077 141 2824 26.36 44.583 0.170

94

Table 30. Readsorption data of 1.49 wt % methanol and 1.50 wt%1-hexene in n-hexane on molecular sieves at 323 K and flow rate of 37.9 gram/min ( column, 13X) - run no 3b___________

Density @ 323 K (g/cm3), MeOH1-C6n-C6

Density of Mixture (g/cm3)Initial Concentration MeOH (wt %)Initial Concentration 1-C6 (wt %)Pump Setting

Flow Rate (g/min)

Empty Bed Volume (cm3)

Weight of Catalyst (g)

0.76370.64300.63300.63501.47111.4896

1.5

37.9

574.8

384Sample Time Bal. Rdg. Wt. Dig Cum. Wt Bed Vol. Elf. Cone Eff Cone

1C6 MeOHNo (min) (g) (g) (a (wt%) (wt%)Start 0.00 8137

1st Drop 0.10 8129 8 8 0.07 44363 0.1612 1.00 8098 31 39 0.32 43.143 0.1193 2.00 8057 41 80 0.66 43.730 0.0544 3.00 8014 43 123 1.01 43.199 0.0395 4.00 7972 42 165 1.36 43.715 0.0336 5.00 7932 40 205 1.68 43.473 0.0307 6.00 7893 39 244 2.01 43.527 0.0278 8.00 7816 77 321 2.64 25.291 0.0669 10.00 7738 78 399 3.28 8311 0.01510 12.00 7663 75 474 3.90 3.539 0.01211 14.00 7588 75 549 4.52 2.258 0.01212 16.00 7514 74 623 5.12 1.893 0.00913 18.00 7439 75 698 5.74 1.762 0.00914 20.00 7364 75 773 6.35 1.717 0.00915 22.00 7289 75 848 6.97 1.727 0.00916 24.00 7216 73 921 7.57 1.691 0.00917 25.00 7178 38 959 7.86 1.676 0.00918 27.00 7105 73 1032 8.48 1.633 0.01819 28.00 7068 37 1069 8.78 1.620 0.09020 29.00 7030 38 1107 9.10 1.602 0.23021 30.00 6993 37 1144 9.40 1.581 0.40322 32.00 6918 75 1219 10.02 1.558 0.83323 34.00 6843 75 1294 10.63 1.539 1.13424 36.00 6770 73 1367 11.23 1.531 1.20025 38.00 6695 75 1442 11.85 1.530 1.41526 40.00 6621 74 1516 12.46 1.522 1.43227 43.00 6508 113 1629 13.39 1.518 1.71028 46.00 6399 109 1738 14.28 1.519 1.54629 49.00 6284 115 1853 15.23 1.517 1.54030 52.00 6173 111 1964 16.14 1.514 1.64731 56.00 6022 151 2115 17.38 1.510 1.55232 60.00 5871 151 2266 18.62 1.507 1.54933 65.00 5681 190 2456 20.18 1.503 1.55234 70.00 5486 195 •2651 21.79 1.500 1.504

95

Table 31. Readsorption data of 1.49 wt % methanol and 1.49 wt%1-hexene in n-hexane on molecular sieves at 323K and flowrate of 37.1 gram/min (3 column, 5A) - run no 4b

Density @ 323 K (g/cm3), MeOH1-C6n-C6

Density of Mixture (g/cm3)Initial Concentration MeOH (wt %)Initial Concentration 1-C6 (wt %)Pump SettingFlow Rate (g/min)Empty Bed Volume (cm3 )Weight of Catalyst (g)

0.76370.64300.63300.63511.48601.4955

1.5

37.1574.8395

Sample Time Bal. Rdg. Wt. Dig. Cum. Wt Bed Vol. Eff. Cone 1C6 Eff. ConeMeOH

No (min) (g) fe) (g) (cm3) (wt%) (wt%)Start 0.00 11404

1st Drop 0.18 11381 23 23 0.19 44.025 0.1102 1.00 11368 13 36 0.30 43.600 0.0363 2.00 11332 36 72 0.59 43.700 0.0034 3.00 11297 35 107 0.88 42.655 0 0035 4.00 11260 37 144 1.18 43.432 0 0036 5.00 11224 36 180 1.48 43.280 0 0037 6.00 11188 36 216 1.78 42.757 00068 8.00 11115 73 289 2.37 35.340 0 0039 10.00 11041 74 363 2.98 12.235 0 00610 12.00 10967 74 437 3.59 4.591 000011 14.00 10894 73 510 4.19 2.435 0 00312 16.00 10820 74 584 4.80 1.875 0 00313 18.00 10748 72 656 5.39 1.701 000614 20.00 10672 76 732 6.02 1.646 0 15815 22.00 10600 72 804 6.61 1.608 0 42'16 23.00 10563 37 841 6.91 1.614 0 65617 24.00 10526 37 878 7.22 1.596 0 68018 25.00 10488 38 916 7.53 1.581 081819 26.00 10452 36 952 7.82 1.578 0 94920 27.00 10414 38 990 8.14 1.572 0 98521 28.00 10377 37 1027 8.44 1.569 1 09822 29.00 10340 37 1064 8.74 1.564 1 17623 30.00 10303 37 1101 9.05 1.571 1 28024 32.00 10230 73 1174 9.65 1.571 1 40225 34.00 10156 74 1248 10.26 1.558 1 37926 36.00 10082 74 1322 10.86 1.554 1 41727 38.00 10009 73 1395 11.46 1.551 1 44728 40.00 9934 75 1470 12.08 1.543 148329 43.00 9823 111 1581 12.99 1.533 1.51330 46.00 9711 112 1693 13.91 1.532 1.43231 49.00 9598 113 1806 14.84 1.532 1.42932 52.00 9486 112 1918 15.76 1.533 1.48933 56.00 9338 148 2066 16.98 1.524 1.46234 60.00 9188 150 2216 18.21 1.525 1.47435 65.00 9001 187 2403 19.75 1.523 1.49236 70.00 8810 191 2594 21.32 1.513 1.507

96

Bed Volume

Figure 37. Typical desorption curve of methanol-1-hexene in n-hexane using 45:55 1-hexene - n-hexane eluant

- 1.5

Bed Volume

Figure 38. Readsorption curve of methanol-l-hexene in n-hexane (13X) -run no 3b

97

Efflu

ent C

once

ntra

tion M

eOH

(wt%

) Ef

fluen

t Con

cent

ratio

n MeO

H (w

t%)

1

O 30

c 20

u 10

Bed Volume

Figure 39. Readsorption curve of methanol-1-hexene in n-hexane (5A) - run no 4b

98

4.3 MODELLING

4.3.1 Simulation of Elution Profile

As discussed in Section 2.3, an IFP proprietary computer programme "COLON"

was used to simulate the breakthrough profile of the methanol in n-hexane and

1-hexene in n-hexane mixture. In so doing, a number of parameters such as the

interstitial void volume fraction, Vv; macro-meso volume fraction , Vm;

microporous volume fraction, V^; and solid volume fraction, Vs need to be

determined. These values were obtained from pore volume and density data

determined by nitrogen adsorption and mercury porosimetry, the method of

calculation of which is as given in Appendix G. The values obtained for the 13X

zeolites are as follows:

interstitial void volume fraction, Vv = 0.34

macro-mesoporous volume fraction, Vm = 0.19

microporous volume fraction, Vg =0.17

solid volume fraction, Vs = 0.30

In addition, the programme requires knowledge of binary selectivity and number of

theoretical plates. Both these values were estimated. For binary selectivity, a low

value was selected in view of its very favourable adsorption of methanol in

n-hexane and for the number of theoretical plates, it was estimated from

knowledge of flowrate versus height equivalent per theoretical plate graph (hetp)

based on a 0.7 cm internal diameter column. The hetp found was 2 cm/theoretical

99

plate and the number of plates determined was 50 for a 100 cm length bed. This

has to be scaled up for a 1.56 cm internal diameter column bed. The expression

used was:

50 x j = 10 theoretical plates

Another method of estimating the number of theoretical plate is the use of the

graph of § versus theoretical plates as given Figure 40 [22], where — is the

slope at 0.5 normalized concentration of the breakthrough curve. An R value of 0

was used in view of the favourable isotherm. From the two values obtained, the

number of theoretical plates can be read off the absissa. Other information required

by the programme were volume fraction of eluant (n-hexane), volume fraction of

charge, number of injection steps, number of contact stages and type of adsorption

isotherm (Langmuir or Langmuir-Freundlich).

a

■ 0.5

100 200Figure 40. Midheight slope for pore-diffusion controlled breakthrough as a

function of separation factor R and NTU.

A simulated breathrough curve was carried out for run no 2 using 10 theoretical

plates and selectivity of 0.02 and a typical printout is as given in Appendix H.

100

From the data obtained in column 2, which is reported in no of contact stages, the

values was converted into bed volume for each contact stage using the following

factor:

_ Bed volume Mcroporous volume fractiona °r theoretical plates X 191.6

Subsequently, the breakthrough curves for both the experimental as well as the

simulated data were plotted and are as shown in Figure 41. Although the simulated

profile matches that of the experimental profile, it did not provide an accurate bed

volume processed. The stoichiometric bed volume processed as determined from

experiment was 11.37 whereas the simulated curve gave value of about 6.69. This

translate into a 41.2% reduction of bed volume processed which is far from

satisfactory.

A similar simulation was carried out for 1-hexene in n-hexane (run no 6) using 8

theoretical plates and selectivity of 0.02. The experimental curve as well as the

simulated curve are as illustrated in Figure 42. It can be seen that in this case that

the profiles differ slightly, while the bed volume processed were quite close. Values

of 2.86 and 2.97 bed volume processed for experimental and simulated were

respectively obtained.

It was mentioned earlier that the simulator was originally written for xylene

separation for which it worked well but somehow did not provide satisfactory

prediction when applied to methanol in n-hexane.

101

Nor

mal

ized

conc

entr

atio

n

Simulated Experimental

.... immlittinntlmiMMiln...... ..I.nmmlmimulmminl.mi.m

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 11.0 12.0 13.0 14.0 15.0 16.0 17.0 18.0

Figure 41. Comparison of simulated and experimental breakthrough curves of methanol in n-hexane - run no. 2

Simulated Experimental

tlmlimt.tiiltimtinliii ,,, I ,,,,,,,,, I L) i iinlnni

Bed volume

Figure 42. Comparison of simulated and experimental breakthrough curves of 1-hexene in n-hexane - run no. 6

102

5 CONCLUSION

In the design of an adsorber or understanding the adsorber behavior, it is necessary to

acquire information on adsorption equilibrium and rate. For this purpose, the

adsorption isotherms of methanol in n-hexane and 1-hexene in n-hexane were

determined. The capacity of methanol in n-hexane at 313 K and 323 K in 13X was

found to be 0.23 and 0.22 g/g and in 5A, 0.21 g/g for both temperatures. In the case

of 1-hexene in n-hexane, the capacity was found to be 0.19 g/g and 0.17 g/g

respectively. All the isotherms exhibited Langmuir-type pattern with methanol

exhibiting near-step change behavior indicating an extremely favourable adsorption.

Modelling of the isotherm data was carried out using the Langmuir and

Langmuir-Freundlich expressions. Both models fitted the experimental data well.

However, the Langmuir model is preferred expression in view of its simplicity and it

involves only one parameter, k

The "macro" approach in which the total resistances is represented in the form of a

breakthrough curve necessitate a number of breakthrough experiments to be carried

out at various conditions. The various parameters studied were concentration,

flowrate, column length, temperature and zeolite type. It was observed in the case of

methanol in n-hexane that there were small differences in the profiles when

concentration, column length and temperature were varied. However, variation in

flowrate caused the profile to be more dispersed. For the case of 1-hexene in

n-hexane some differences in the breakthrough profiles were noted. This may be due

to experimental difficulties in controlling the flowrates at the start of the experiment

rather than inherent adsorption behavior. In the 3-component system

103

to methanol. Readsorption under various conditions showed marked reduction in the

amount of feed processed.

Breakthrough curves simulated using the "COLON" computer programme which is

based on an estimation of selectivity and theoretical plates predicted reasonably well

in terms of bed volume processed for the 1-hexene in n-hexane system. However, it

failed for the methanol in n-hexane system. To predict better the results, it is believed

that the numerical analysis needs to be refined.

(1-hexene-methanol-n-hexane), 1-hexene breakthrough was much earlier compared

104

Act

ual (

wt/w

t%)

Appendix A

GC calibration curve for methanol in n-hexane

Y - MO + Ml *x + M8*xe + M9*xs

2.1102-0.76470.15288

l M t I

0 0.5 1 1.5 2 2.5 ... 3GC (wt/wt%)

GC calibration curve for 1-hexene in n-hexane

y = -0.32342 + 1.0244% R= 0.99994 -

0 .20 40 60 80 100GC Results (wt/wt%)

105";

To Calculate the Concentration of Adsorbate in the Adsorbed and Fluid Phases

Appendix B

(Method A)

Let,

We know,

f f fmm + m ^ — rrif

f f fmm — mt x Cm

By substituting equation (2) into equation (1), we have,

f f f fmt x cm + mh = mt

Given,

mh = mt (1 - cm)

By rearranging equation (4),

m\ = ----- I h-T

1 — Cm

By substituting equation (5) into equation (2), we have,

mm =f f

mh Cm

1 — Cm

(1)

(2)

(3)

(4)

(5)

(6)

Amount of methanol adsorbed per gram of molecular sieve is given by,

Q mm — mmz (7)

Concentration of methanol (g/cm3) remaining in the solution,

f = mmPmfm (8)

+ m

106

where /77m mass of methanol in the fluid phase (g).

mh " mass of n-hexane in the fluid phase (g).

rrft total mass of the fluid phase (g).

m% initial mass of methanol before adsorption (g).

of mass fraction of methanol in the fluid phase (g).

p density of fluid(g/cm3).

z amount of molecular sieves(g).

107

Appendix C

To Calculate the Concentration of Adsorbate in the Adsorbed and Fluid Phases (Method B)

Surface Excess

Consider a binary mixture A and B which are adsorbed on a molecular sieve. The surface

excess of A and B is given by,

rA = ^ X - xaJ (1)

r6 = ^ X (XB - *b) (2)

Hence,

rA + r ms xD - Z

- xa) + (xg - Xg)(3)

= ^ X [*S + Xg - XA - xg] (4)

The amount of adsorbate adsorbed on a molecular sieve is given by,

T(A =mA " mA

(5)

TIB =mB - mB

(6)

where m^, mB, ma, and mg are respectively the masses of A and B in the initial and

final mixture.

.. 108

Given,

XAmAmt

and

x0B XB

mBmt

where mf = m°A + m°B

mt = itia + itiq

We know by manipulation,

rA r\AxB ~ t\BxA (7)

Consider,

a) at saturation

Vp = t\ava + t\avb

1 M + M Vp VpVA VB

where Vp = adsorbent micropore volume

Va = molar volume of A

(8)

(9)

109

Vg = molar volume of B

b) Gurvistch rule

Gurvistch rule states that the number of moles of A (or B) adsorbed at saturation is equal to

the micropore volume of the adsorbent divided by the molar volume of A (or B).

VPVA

VpVB (10)

1 JTA + na(ii)

To change to molar mass, multiply the numerator and denominator by the respective molar

mass.

TIA mA 'Hb MB

nf ma i|af Mb

1 (12)

where mA = mass of A adsorbed = - m a

mB = mass of B adsorbed = mB - mg

mA = molar mass of A

mg = molar mass of B

110

c) The hypothesis that in a gaseous phase, the amount adsorbed is equal to that of the liquid

phase at saturation.

. Ma = Mmf

M9B Mm sat

B

/ /. _ ^B

M9a M9 (13)

where = concentration of A in the gaseous phase at saturation and

M9B = concentration of B in tha gaseous phase at saturation.

d) Also,

TlA =muA - mA m,

(14)

•ns =mB - mB m B (15)

By substituting equations (14) and (15) into equation (13),

1 =A ZHB

MB

i = m + m z M9A m%

(16)

111

Finally, the individual isotherm can be written as,

IIF Ta + M9bxa1 - XA + &BXA

ns =rB + m%xB

1 - xb + &AXB

u o mbwhere (3 g = °

ma' ^ " Mg

112

113

Appendix E

ANALYSE : 18571 DATE : 4 May 1984

SAMPLE NAME : org b ma1 ays

USER NAME : jol'iao

4p„n TVoj

PNTFHPNTR- SAMPL E-MERC DRY

WEIGHT* 102.2 100

PNTR NUMBER = I 15 THETA = 1 4 0 . 0 000PNTR WEIGHT = 71.0282 G GAMMA = 485 . 0000PNTR VOLUME = 2.8500 CC MERCURY DENSITY = 1 5 < -< =.PNTR CONSTANT* 1 0.0 0 0 0 MICRO L? EQUILIBRATION = < ri fififmSTEM VOLUME = . 580 0 CC HP EQUILIBRATION = .0000

SAMPLE WEIGHT* . 5 9 0 9 G INITIAL PRESSURE ; . 8 5 80SAMPLE WEIGHT* 71.4171 G

G/CCSECSEC

INTRUSION (PRESSURISATION) DATA SUMMARY

TOTAL INTRUSION VOLUME(V)= TOTAL PORE AREA(A) =MEDIAN PORE DIAMETER(VOLUME) MEDIAN PORE DIAMETER(AREA)= AVERAGE PORE DI AMETE.R( 4 V/A ) = BULK DENSITY*SKELETAL DENS ITY*

24.0289 SO-M/G.2578 MICROMETERS .0128 MICROMETERS .0522 MICROMETERS

1.0455 G/CC 1.5500 G/CC

^'C AP I LLARY = 52.2 588 Vf>rr= 0,53

ANALYSE : DATE :

1*5714 May i*v,4

Echan t i 11 on : org b .nalays

Deman.tieur ' : j u 11 i a nPane eromeere: 115

PRESSURE PORE INTRUSION PORE MEANPS IA DIAMETER VOLUME SURFACE DIAMETER UV

MICRO_M cc/g SQ-.M/G MICRO_M

i .6 1 3 4.7 15 5 fi fifififi 0.0000 134.7155 0.00002.7 73.3314 fl l"l f 1 fI fi 0.0 0 0 0 107.2734 0.00003 .5 61.5342 M . fl fl fl fl fi . 0 fi fi fi 70.7075 0.00005.3 <6 s < % fi 0.0 0 0 0 0.0 0 0 0 45.0556 0.00003 . S 24.4337 fl fl fl fl fl 0.0000 30.5134 0.0000

1 1 . S 13.5314 fl fl fl fi fl 0.0 0 0 0 21.5376 0.000017.5 12.3163 fl flflflfl 0.00 00 15.4431 0.000020 . i 10.7256 fl fl fl fl fl 0.0000 1 1 .5202 0.00002 4.0 3.3310 fl flflflfl fl flflflfl 3.3523 0.00003 0.3 6.3756 fl flflflfl 0.0000 7.3753 0.00003 0.3 7.1137 fl fl fl fl fl 0.0 0 0 0 7.0446 0.000040. S 5.5030 fl flflflfl 0.0 0 0 0 6.2113 0.0000S3.3 3.1103 0.0000 0.0000 4.2036 0.000033.3 2.1533 0.0 0 0 0 0.0 0 0 0 2.6350 0.0000

1 2 S . 5 1.7053 . 0013 .0026 1.3313 .0013134.0 1.17M . 0 0 3 3 . 0055 1.4577 .0026257. a . 3374 .012 5 .0454 1 . 0 0 4 4 .00503 S 1 . 1 .53 63 .0 334 .1551 .7172 .02565 3 0.3 .3711 . 1 0 3 6 .7272 . 4540 .065 2332.3 .2643 . 1535 1.3757 . 3077 .0455

1130.5 . 1320 . 1323 1.5270 .2154 .02341733.3 . 1207 . 2 03 3 2.6356 .1516 .02 652536.1 . 0 35 0 . 225 1 3.2227 . 1025 .01533523.0 .0611 .2 373 3.3333 .0750 .01255353.3 . 0 3 63 . 2534 5.6063 . 0433 .02 053533.0 .0251 .2763 7.5210 . 0305 . 01 73

11437.4 .0137 .2565 3.7575 .0215 .010217466.3 .012 3 . 2355 12.0313 .0155 .005024334.1 . 0037 < flfl K 14.0403 .0105 .005134331.7 .0062 . 3057 16.5004 .0074 .005157065.3 . 0 0 3 3 . 3 035 13.5564 . 0050 . 00 3553262.5 . 00 3 6 . 3 1 34 24.0263 .0057 .003543741.3 . 0043 .3147 25.2216 .004 3 .001320536.5 .0105 .3 155 25.5562 .0077 .001310167.4 .0212 .3121 24.3163 .0155 - .00355225.7 .0412 . 3 05 7 24.0575 .0312 -.00642473.3 .0571 .2516 23.2207 .0642 -.0141

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ESSRI N*:185711

COURSE DE DUBININ

Volume DUBININ 254 co/g

(LOG(F ESSRI N* i185711

SETAHAMTAGFig.: Echant: ORG 13X Methanol02-11-95 R ORG Methanol dlff temperature ads (40) t - Id "c -if* — l <>

Masse: 43. qe mgS' o' I- o*u. If*

Atm: heliumCtn: quartz

SETAHAHTABFig.: Echant: Tamib ORG 0 13X Methanol ads (50)14-11-95 R ads (50) Methanol diff temperature

Masse: 44.39 mg Atm: helium"Ctn: quartz

SETARAM Fig.: Echant: ORG B 13X 1 Hexene Masse:43.57 mg Atm: heliumTAG 09-11-95 P: ORG b 13X (40) ads diff temperature Ctn: quartz

EMPERATURE (C)

U. Tfi

TEMPS; (b) -1025000200005000 1500010000

i uijii

Echant: ORG B 13X nHexane 40degre Masse: 43.80 mg Atm: heliumSETAHAMTAG 26-10-95 P: ads 40 nHexane diff temperature c-10"*- -'5*c - io°^ - v io^-u^c-) ctn: quartzEMPERATURE (C) TG (mg)

TEMPS (s) L105000 10000 15000 20000 25000

SETARAMTAG

Fig.: Echant: TAMIS PROCAT Methanol06-11-95 P: PROCAT Methanol (40) ads diff temperature

Masse: 44.76 mg Atm: heliumCtn: quartz

Fig.: Echant: ads 50 degre16-11-95 P: TAMIS PROCAT methanol diff temperature

Masse: 45.06 mg Atm: heliumCtn: quartz

SETARAMTAG

TEMPERATURE (C) TG (mg)

260

TG •TEMPS ;(8)

25000 : j L5000 10000 15000 20000

Masse: 45.02 mg Atm:; heliumCtn: quartz

Fig.: Echant: PROCAT 5A 1 Hexene10-11-95 P: PROCAT 5A (40) ads diff temperature

SETARAMTAG

TEMPERATURE (C)

TEMPS (s) .i —A5000 10000 15000 20000 25000

SETABAMTAG

Fig.: Echant: PROCAT 5A nHexane 40degre ^ Masse: 44.95 mg27-10-95 P: ads 40 nHexane diff temperature -\»*c q* ;Te iC-c

Atm: heliumCtn: quartz

DSA11: [THOMASM] PS AT .DAT ; 2 13-NOV-1995 16:01 Page

For METHANOLThe Vapor Pressure can be calculated as follows:

VP in Pa = exp(A + B/T + C*ln(T) + D*T**E)Where: T = Temperature in Kelvin

A = 1.0993E+02 B = -7.4713E+03 C = -1.3988E+01D = 1.5281E—02 E = 1.0000E+00

In the range: 175.47 K to 512.58 K ( -97.7 C to 239.4 C)Range is extrapolated Quality code: 2 Source file status: N

References used in regression: 30 3

For METHANOLThe following Vapor Pressure values have been calculated:

TEMP in C VALUE in bar-20.0 - 9.722E-03-15.0 1.413E-02-10.0 2.022E-02-5.0 2.847E-02

0.0 3.952E-025.0 5.410E-02

10.0 7.314E-0215.0 9.767E-0220.0 1.290E-0125.0 1.685E-0130.0 2.178E-01

For 1-HEXENEThe Vapor Pressure can be calculated as follows:

VP in Pa = exp(A + B/T + C*ln(T) + D*T**E)Where: T = Temperature in Kelvin

A = 8.1911E+01 B = -6.0377E+03 C = -9.1784E+00D = 8.4689E-06 E = 2.0000E+00

In the range: 133.39 K to 504.03 K ( -139.8 C to 230.8 C)Range is extrapolated Quality code: 2 Source file status: B

References used in regression: 239

For 1-HEXENEThe following Vapor Pressure values have been calculated:

TEMP in C VALUE in bar-20.0 2.474E-02-15.0 3.352E-02-10.0 4.481E-02-5.0 5.914E-02

0.0 7.712E-025.0 9.942E-02

10.0 1.268E-0115.0 1.602E-0120.0 2.004E-0125.0 2.485E-0130.0 3.056E-01

For n-HEXANEThe Vapor Pressure can be calculated as follows:

VP in Pa = exp(A + B/T + C*ln(T) + d*T**E)Where: T = Temperature in Kelvin

A = 1.6547E+02 B = -8.3533E+03 C = -2.3927E+01D = 2.9496E-02 E = 1.0000E+00

In the range: 177.84 K to 507.43 K ( -95.4 C to 234.2 C)Range is experimental Quality code: 3 Source file status: B

References used in regression: 777 69 778 782 779 780781 47

For n-HEXANE■The following Vapor Pressure

TEMP in C VALUE in bar -20.0 1.865E-02-15.0 2.565E-02

values have been calculated:

13-NOV-1995 16:01 Page 2DSA11: [THOMASM] PSAT. DAT ; 2 -

-10.0 3.473E-02'--5.0 4.636E-02

0.0 6.107E-025.0 7.945E-02

10.0 1.022E-0115.0 1.299E-0120.0 1.636E-0125.0 2.039E-0130.0 2.520E-01

129

Appendix G

To Calculate Volume Fractions

Given,

Weight of zeolite 131 g

Volume of zeolite bed 191.6 cm3

Solid density 2.31 g/cm3

Dubinin volume 0.254 cm3/g

Grain density

To calculate,

1.04 g/cm3

Solid volume weight of zeolite

solid density

1312.31

= 56.7 cm3

Microporous volume = weight of zeolite x Dubinin volume

= 131x0.254

= 33.3 cm"

Macro-mesoporous volume = zeolite specific volume - microporous volume - solid volume

weight of zeolite . , , ,~ ... - microporous volume - solid volume

gram density

=tH-56-7-33-3

= 36.0 cm3

Interstitial volume =: total zeolite bed volume - solid volume -microporous volume - macro-mesoporous volume

= 191.6-56.7-33.3 -36.0

= 65.6 cm3

130

Therefore, the respective volume fractions are:

Solid volume fraction = 0.30

Microporous volume fraction = 0.17

Macro-mesoporous volume fraction = 0.19

Interstitial volume fraction = 0.34

131

__DSA341 [P5091.E5091018.TA.VXTIAN]l.,-2 22-DBC-1995 10:37 Page

0.34a 0.19b 0.17©21d0.999997e O.OOOOOlf 0.000001% O-OOOOOlt,0.995298, 0.0047 j 0.000001% 0.0000011'2500m2500nOq

!p 100 q- 10 Or.

250 0.99999 0.00000 0.00000 0.00000 i.ooooo251 0.99999 0.00000 0.00000 0.00000 1.00000252 0.99999 0.00001 0.00000 0.00000 1.00000253 0.99999 0.00001 0.00000 0.00000 1.00000254 0.99999 0.00001 0.00000 0.00000 1.00000255 0.99999 0.00001 0.00000 0.00000 1.00000256 0.99999 0.00001 0.00000 0.00000 1.00000257 0 ooooq 0.00001 0.00000 0.00000 1.00000258 0.99999 0.00001 0.00000 0.00000 1.00000259 0.99999 0.00001 . 0.00000 0.00000 1.00000260 0.99999 0.00001 0.00000 0.00000 1.00000261 0.99999 0.00001 0.00000 0.00000 1.00000262 0.99999 0.00001 0.00000 0.00000 1.00000263 0.99999 0.00001 0.00000 0.00000 1.000002 64 0.99999 0.00001 0.00000 0.00000 1.00000265 0.99999 0.00001 0.00000 0.00000 1.00000266 0.99999 0.00001 0.00000 0.00000 1.00000257 0.99999 0.00001 0.00000 0.00000 1.00000258 0.99999 0.00001 0.00000 0.00000 1.00000269 0.99999 0.00001 0.00000 0.00000 1.00000270 0.99999 0.00001 0.00000 0.00000 1.00000271 0.99999 0.00001 0.00000 0.00000 1.00000272 0.99999 0.00001 0.00000 0.00000 1.00000273 0.99999 0.00001 0.00000 • 0.00000 1.00000'74 0.99998 0.00001 0.00000 0.00000 1.00000275 0.99998 0.00001 0.00000 0.00000 1.00000275 0.99998 0.00001 0.00000 0.00000 1.00000

/ / 0.99993 0.00002 0.00000 0.00000 1.00000J / o 0.99998 0.00002 0.00000 0.00000 1.00000279 0.99998 0.00002 0.00000 0.00000 1.00000280 0.99998 0.00002 0.00000 0.00000 1.00000231 0.99998 0.00002 0.00000 0.00000 1.00000282 0.99998 0.00002 0.00000 0.00000 1.00000

0.99993 0.00002 0.00000 0.00000 1.00000284 0.99993 0.00002 0.00000 0.00000 1.00000235 0.99998 0.00002 0.00000 0.00000 1.00000236 0.99998 0.00002 0.00000 0.00000 1.00000287 0.99997 0.00002 0.00000 0.00000 1.00000238 0.99997 0.00002 0.00000 0.00000 1.00000289 0.99997 0.00003 0.00000 0.00000 1.00000290 0.99997 0.00003 0.00000 0.00000 1.00000291 0.99997 0.00003 0.00000 0.00000 1.00000292 0.99997 0.00003 0.00000 0.00000 1.00000293 0.99997 0.00003 0.00000 0.00000 1.00000294 0.99997 0.00003 0.00000 0.00000 1.00000295 0.99997 0.00003 0.00000 0.00000 1.00000296 0.99996 0.00003 0.00000 0.00000 1.00000297 0.99996 0.00004 0.00000 0.00000 1.00000298 0.99996 0.00004 0.00000 0.00000 1.00000299 0.99996 0.00004 0.00000 0.00000 1.00000300 0.99996 0.00004 0.00000 0.00000 1.00000301 0.99996 0.00004 0.00000 0.00000 1.00000302 0.99996 0.00004 0.00000 0.00000 1.00000303 0.99995 0.00004 0.00000 0.00000 1.00000304 0.99995 0.00005 0.00000 0.00000 1.00000305 0.99995 0.00005 0.00000 0.00000 1.00000306 0.99995 0.00005 0.00000 0.00000 1.00000

i.Appendix H .

Page 2_DSA34:[P5091.E5091018.TAVITIAN]1.;2 22-DEC-1995 10:37

307 0.99995 0.00005 0.00000 0.00000 1.00000303 0.99994 0.00005 0.00000 0.00000 1.00000309 0.99994 0.00006 0.00000 0.00000 1.00000310 0.99994 0.00006 0.00000 0.00000 1.00000311 0.99994 0.00006 0.00000 0.00000 1.00000312 0.99994 0.00006 0.00000 0.00000 1.00000313 0.99993 0.00007 0.00000 0.00000 1.00000314 0.99993 0.00007 0.00000 0.00000 1.00000315 0.99993 0.00007 0.00000 0.00000 1.00000316 0.99993 0.00007 0.00000 0.00000 1.00000317 0.99992 0.00003 0.00000 0.00000 1.00000313 0.99992 0.00003 0.00000 0.00000 1.00000319 0.99992 0.00008 0.00000 0.00000 1.00000320 0.9999.1 0.00008 0.00000 0.00000 1.00000321 0.99991 0.00009 0.00000 0.00000 1.00000322 0.99991 0.00009 0.00000 0.00000 1.00000323 0.99990 0.00009 0.00000 0.00000 1.00000324 0.99990 0.00010 0.00000 0.00000 1.00000325 0.99990 0.00010 0.00000 0.00000 1.00000325 0.99939 0.00010 0.00000 0.00000 1.00000327 0.99989 0.00011 0.00000 0.00000 1.00000328 0.99989 0.00011 0.00000 0.00000 1.00000329 0.99983 0.00012 0.00000 0.00000 1.00000330 0.99988 0.00012 0.00000 0.00000 1.00000331 0.99937 0.00012 0.00000 0.00000 1.00000332 0.99937 0.00013 0.00000 0.00000 1.00000333 0.99987 0.00013 0.00000 0.00000 1.00000334 0.99936 0.00014 0.00000 0.00000 1.00000335 0.99986 0.00014 0.00000 0.00000 1.00000335 0.99935 0.00015 0.00000 0.00000 1.000003 37 0.99985 0.00015 0.00000 0.00000 1.00000i Jo 0.99984 0.00015 0.00000 0.00000 1.000003 39 0.99984 0.00016 0.00000 0.00000 1.00000340 C. 99983 0.00017 0.00000 0.00000 1.00000341 0.99983 0.00017 0.00000 0.00000 1.00000342 0.99982 0.00018 0.00000 0.00000 1.00000

. QQQ32 0.00018 0.00000 0.00000 1.00000344 3.99981 0.00019 0.00000 0.00000 1.00000345 0.99980 0.00019 0.00000 0.00000 1.00000;-4o 0.99980 0.00020 0.00000 0.00000 1.00000347 0.99979 0.00021 0.00000 0.00000 1.00000v 4b 0.99978 0.00021 0.00000 0.00000 1.00000349 0.99978 0.00022 0.00000 0.00000 1.00000

0.99977 0.00023 0.00000 0.00000 1.000000.99976 0.00023 0.00000 0.00000 1.00000

352 0.99976 0.00024 0.00000 0.00000 1.00000353 0.99975 0.00025 0.00000 0.00000 1.000003 54 0.99974 0.00025 0.00000 0.00000 1.00000355 0.99973 0.00026 0.00000 0.00000 1.00000355 0.99973 0.00027 0.00000 0.00000 1.00000357 0.99972 0.00028 0.00000 0.00000 1.00000358 0.99971 0.00029 0.00000 0.00000 1.00000359 0.99970 0.00030 0.00000 0.00000 1.00000360 0.99969 0.00031 0.00000 0.00000 1.00000351 0.99963 0.00031 0.00000 0.00000 1.00000362 0.99967 0.00032 0.00000 0.00000 1.00000363 0.99967 0.00033 0.00000 0.00000 1.00000364 0.99966 0.00034 0.00000 0.00000 1.00000365 0.99965 0.00035 0.00000 0.00000 1.00000366 0.99964 0.00036 0.00000 0.00000 1.00000367 0.99963 0.00037 0.00000 0.00000 1.00000368 0.99962 0.00038 0.00000 0.00000 1.00000369 0.99960 0.00039 0.00000 0.00000 1.00000370 0.99959 0.03040 0.00000 0.00000 1.00000371 0.99953 0.00042 0.00000 0.00000 1.00000372 0.99957 0.00043 0.00000 0.00000 1.00000

133

_DSA34:[P5091.E5091018.TAVITIAN]1. ;2 22-DEC-1995 10:37 Page

373 0.99956 0.00044 0.00000 0.00000 1.00000374 0.99955 0.00045 0.00000 0.00000 1.00000375 0.99954 0.00046 0.00000 0.00000 1.00000376 0.99952 0.00047 0.00000 0.00000 1.00000377 0.99951 0.00049 0.00000 0.00000 1.00000378 0.99950 0.00050 0.00000 0.00000 1.00000379 0.99948 0.00051 0.00000 0.00000 1.00000380 0.99947 0.00053 0.00000 0.00000 1.00000381 0.99946 0.00054 0.00000 0.00000 1.00000382 0.99944 0.00055 0.00000 O.OO'OOO 1.00000383 0.99943 0.00057 0.00000 0.00000 1.00000384 0.99942 0.00058 0.00000 0.00000 1.00000385 0.99940 0.00060 0.00000 0.00000 1.00000386 0.99939 0.00061 0.00000 0.00000 1.00000387 0.99937 0.00063 0.00000 0.00000 1.00000388 0.99936 0.00064 0.00000 0.00000 1.00000389 0.99934 0.00066 0.00000 0.00000 1.00000390 0.99932 0.00067 0.00000 0.00000 1.00000391 0.99931 0.00069 0.00000 0.00000 1.00000392 0.99929 0.00071 0.00000 0.00000 1.00000393 0.99927 0.00072 0.00000 0.00000 1.00000394 0.99926 0.00074 0.00000 0.00000 1.00000395 0.99924 0.00076 0.00000 0.00000 ' 1.00000396 0.99922 0.00078 0.00000 0.00000 1.00000397 0.99920 0.00079 0.00000 0.00000 1.00000398 0.99919 0.00081 0.00000 0.00000 1.00000399 0.99917 0.00083 0.00000 0.00000 1.00000400 0.99915 0.00085 0.00000 0.00000 1.00000401 0.99913 0.00087 0.00000 0.00000 1.00000402 0.99911 0.00089 0.00000 0.00000 1.00000403 0.99909 0.00091 0.00000 0.00000 1.00000404 0.99907 0.00093 0.00000 0.00000 1.00000405 0.99905 0.00095 0.00000 0.00000 1.00000406 0.99903 0.00097 0.00000 0.00000 1.00000407 0.99901 0.00099 0.00000 0.00000 1.00000408 0.99899 0.00101 0.00000 0.00000 1.00000409 0.99897 0.00103 0.00000 0.00000 1.00000410 0.99894 0.00105 0.00000 0.00000 1.00000411 0.99892 0.00108 0.00000 0.00000 1.00000412 0.99890 0.00110 0.00000 0.00000 1.00000413 0.99888 0.00112 0.00000 0.00000 1.00000414 0.99886 0.00114 0.00000 0.00000 1.00000415 0.99833 0.00117 0.00000 0.00000 1.00000416 0.99831 0.00119 0.00000 0.00000 1.00000417 0.99879 0.00121 0.00000 0.00000 1.00000413 0.99876 0.00124 0.00000 0.00000 1.00000419 0.99874 0.00126 0.00000 0.00000 1.00000420 0.99871 0.00128 0.00000 0.00000 1.00000421 0.99869 0.00131 0.00000 0.00000 1.00000422 0.99866 0.00133 0.00000 0.00000 1.00000423 0.99864 0.00136 0.00000 0.00000 1.00000424 0.99861 0.00138 0.00000 0.00000 1.00000425 0.99859 0.00141 0.00000 0.00000 1.00000426 0.99856 0.00144 0.00000 0.00000 1.00000427 0.99854 0.00146 0.00000 0.00000 1.00000428 0.99851 0.00149 0.00000 0.00000 1.00000429 0.99348 0.00151 0.00000 0.00000 1.00000430 0.99346 0.00154 0.00000 0.00000 1.00000431 0.99843 0.00157 0.00000 0.00000 1.00000432 0.99840 0.00159 0.00000 0.00000 1.00000433 0.99838 0.00162 0.00000 0.00000 1.00000434 0.99835 0.00165 0.00000 0.00000 1.00000435 0.99832 0.00168 0.00000 0.00000 1.00000436 0.99329 0.00170 0.00000 0.00000 1.00000437 0.99827 0.00173 0.00000 0.00000 1.00000438 0.99824 0.00176 0.00000 0.00000 1.00000

134 '

* I *_DSA34:[P5091.E5091018-TAVITIAN]1.;2 22-DEC-1995 10:37 Page

439 0.99821- 0.00179440 0.99818 0.00132441 0.99815 0.00184442 0.99813 0.00137443 0.99310 0.00190444 0.99807 0.00193445 0.99804 0.00196446 0.99801 0.00199447 0.99793 0.00202448 0.99795 0.00205449 0.99792 0.00207450 0.99789 0.00210451 0.99786 0.00213452 0.99784 0.00216453 0.99781 0.00219454 0.99778 0.00222455 0.99775 0.00225456 0.99772 0.00228457 0.99759 0.00231453 0.99755 0.00234459 0.99753 0.00237450 0.99760 0.00240461 0.99757 0.00243462 0.99754 0.00246463 0.99751 0.00249464 0.99748 0.00252455 0.99745 0.00255465 0.99742 0.00257467 0.99739 0.00260458 0.99737 0.00263459 0.99734 0.00266470 0.99731 0.00269471 0.99728 0.00272472 0.99725 0.00275473 0.99722 0.00278474 0.99719 0.00280475 0.99717 0.00283476 0.99714 0.00286477 0.99711 0.00239478 0.99708 0.00292479 0.99705 0.00294480 0.99703 0.00297481 0.99700 0.00300482 0.99597 0.00302483 0.99595 0.00305484 0.99692 0.00308485 0.99589 0.00310486 0.99537 0.00313487 0.99584 0.00316488 0.99582 0.00313489 0.99679 0.00321490 0.99676 0.00323491 0.99674 0.00326492 0.99671 0.00323493 0.99669 0.00331494 0.99667 0.00333495 0.99664 0.00336496 0.99662 0.00333497 0.99659 0.00340498 0.99657 0.00343499 0.99655 0.00345500 0.99652 0.00347501 0.99650 0.00350502 0.99648 0.00352503 0.99646 0.00354504 0.99644 0.00356

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138

22-DEC-1995 10:37 Page 8JDS A3 4: [P5091.E5091018.TAVITIAN]!.;2

703 0.99530 0.00469 0.00000 0.00000704 0.99530 0.00469 0.00000 0.00000705 0.99530 0.00469 0.00000 0.00000706 0.99530 0.00469 0.00000 0.00000707 0.99530 0.00469 0.00000 0.00000703 0.99530 0.00469 0.00000 0.00000709 0.99530 0.00469 0.00000 0.00000710 0.99530 0.00470 0.00000 0.00000711 0.99530 0.00470 0.00000 0.00000712 0.99530 0.00470 0.00000 0.00000713 0.99530 0.00470 0.00000 0.00000

1.000001.000001.000001.000001.000001.000001.000001.000001.000001.000001.00000

.139

Note

a

b

c

d

e

f

g

h

i

j

k

I

m

n

o

P

q

r

Interstitial volume fraction

macro-mesoporous volume fraction

microporous volume fraction

no of theoretical plates (estimated)

eluent volume fraction of component 1 (n-hexane)

eluent volume fraction of component 2 (dummy)

eluent volume fraction of component 3 (dummy)

eluent volume fraction of component 4 (dummy)

feed volume fraction of component 1 (n-hexane)

feed volume fraction of component 2 (methanol)

feed volume fraction of component 3 (dummy)

feed volume fraction of component 4 (dummy)

no of injection steps

no of simulation steps

method type (0 - Langmuir, 1 - Langmuir-Freundlich)

selectivity (j/i)

selectivity (k/i)

selectivity (1/i)

140

6. REFERENCES

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142