adsorption competition study between oxygenated …
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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
DISCLAIMER
Portions of this document may be illegible electronic image products. Images are produced from the best available originaldocument.
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
-116
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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
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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