isolation n-butane

RREEPPUUPPLLIICC OOFF IIRRAAQQ MMIINNIISSTTRRYY OOFF HHIIGGHHEERR EEDDUUCCAATTIIOONN AANNDD SSCCIIEENNTTIIFFIICC RREESSEEAARRCCHH UUNNIIVVEERRSSIITTYY OOFF TTEECCHHNNOOLLOOGGYY BBAAGGHHDDAADD-- IIRRAAQQ

IIMMPPRROOVVEEMMEENNTT OOFF CCAATTAALLYYSSTTSS FFOORR HHYYDDRROOIISSOOMMEERRIIZZAATTIIOONN OOFF IIRRAAQQII LLIIGGHHTT NNAAPPHHTTHHAA

A THESIS SUBMITED TO THE DEPARTMENT OF CHEMICAL

ENGINEERING OF THE UNIVERSITY OF TECHNOLOGY IN A PARTIAL FULFILMENT OF THE REQUIREMENTS FOR

THE DEGREE OF MASTER OF SCIENCE IN CHEMICAL ENGINEERING

BY Muayad Mohammed Hasan

B.Sc. in CHEMICAL ENGINEERING

March, 2010

قـالوا سبحانك ال علم لنـا إال ما علمتنـا إنك

أنت العليم الحكيم

العظيم صدق اهللا

)32(سورة البقرة االية

CERTIFICATE

We certify that we have read this thesis entitled "Improvement of Catalysts for

Hydroisomerization of Iraqi Light Naphtha" by Muayad Mohammed

Hasan and as on Examining Committee examined the student in its contents and

that in our opinion it meets the standard of a thesis for the degree of Master of

Science in Chemical Engineering.

Signature: Signature:

Asst. Prof. Dr. Khalid A. Sukkar Asst. Prof. Dr. Shahrazad R. Raouf

(Supervisor) (Chairman)

Date: / / 2010 Date: / / 2010

Signature: Signature:

Asst. Prof. Dr. Wadood T. Mohammed Asst. Prof. Dr. Saba A. Ghani

(Member) (Member)

Date: / / 2010 Date: / / 2010

Approved for the University of Technology – Baghdad

Signature:

Prof. Dr. Mumtaz A. Zablouk

Head of Chemical Engineering Department

Date: / / 2010

SUPERVISOR CERTIFICATION

I certify that this thesis entitled:- "Improvement of Catalysts for

Hydroisomerization of Iraqi Light Naphtha" Presented by Muayad

Mohammed Hasan, was prepared under my supervision in a partial fulfillment

of the requirements for the degree of Master of Science in Chemical Engineering

at the Chemical Engineering Department, University of Technology.

Signature:

Name: Asst. Prof. Dr. Khalid Ajmi Sukkar

(Supervisor)

Date: / / 2010

In view of the available recommendations I forward this thesis for debate by the

Examination Committee.

Signature:

Name: Asst. Prof. Dr. Khalid Ajmi Sukkar

Deputy Head of Department of Chemical Engineering

Date: / / 2010

CERTIFICATION

This is to certify that I have read the thesis titled "Improvement of

Hydroisomerization Process to Produce High Octane Gasoline using

Modified Catalysts" and corrected any grammatical mistake I found.

The thesis is therefore qualified for debate.

Signature:

Name:

Date: / / 2010

Acknowledgment

I

Acknowledgment

First of all praise be to god Who give me patience, strength and the most

important thing: faith to continue...

I wish to present my sincere appreciation with deep respect to my

supervisor Dr. Khalid Ajmee Sukkar for his helpful efforts and advice

during my work.

My great gratitude is due to the Head and the staff of Chemical

Engineering Department of the University of Technology for their help

and assistance in providing facilities throughout this work.

My respectful regards to Mr. Bushier Yosuf Sharhan for his kindness and helpful efforts to making the characterization of my work.

Finally my grateful thanks are due to my wife for her encouragement and

support.

Summary

II

Summary

In the presented work hydroisomerization of Iraqi light naphtha (produced in Al-

Dura Refinery) has been investigated to produce isomers. Three types of catalysts

were prepared Pt/HY, Pt/BaY, and Pt/Al2O3 with

0.5wt% by impregnation with

hexachloroplatinic acid.

The catalytic unit was constructed from stainless steel and designed to carry out the hydroisomerization process. The fixed bed reactor dimensions were O.D 3cm, I.D 2cm, and 21cm high. All experiments were made at atmospheric pressure and reaction temperature of 230, 250, 270, 290, and 310°C, WHSV 1.5, 3, and 4.5h-1, under constant H2

/HC mole ratio of 4.

The results show that the conversion of the main light naphtha components (n-pentane, n-hexane, 2-methylpentane, and 3-methylpentane) increases with increase in reaction temperature and decreases with increase in weight hour space velocity. Also, it was noted that the selectivity to isomers increase with Pt/HY, Pt/BaY catalysts at low temperature and decrease at high temperature, while with Pt/AlR2ROR3R catalyst the aromatics products increase with increase in reaction temperature. Pt/HY catalyst gives higher selective isomerization than Pt/BaY catalyst which is

(95%) and (89%) respectively at 270°C, and (1.5 hr P

-1P). While, Pt/AlR2ROR3R catalyst

gives 64.7% as total conversion where 18% as aromatic products. The total

conversion for Pt/HY and Pt/BaY were about 50%. The following sequence for

isomerization selectivity was concluded as:

Pt/HY > Pt/BaY > Pt/AlR2ROR3R

Summary

III

A kinetic model was derived based on the present work results. Then, the kinetic

parameters such as K1, K2, Ko

, and activation energy (E) are calculated depending

on the present experimental work results.

The results of model show that the values of apparent activation energy

vary within a range of 22 and 23 kJ/mol for n-pentane, 20 to 24 kJ/mol for

n-hexane, and 15 to 17 kJ/mol for 3mp isomerization reactions. On the

other hand, the model pointed the reactivity order behaves as follows.

3-methylpentane > n-hexane > n-pentane

Derive an equations which are calculating the reaction rate constants (k1 and k2

)

parameters as follows:

k1= [(1+ Є) Ln – Єx]

Ciso = CA° [1- exp (- k1t) - [exp(-kR1Rt) – exp(-kR2Rt)]

Contents

IV

CONTENTS

Pages Subject

I Acknowledgments

II Summary

IV

Contents

VIII

Nomenclature

CHAPTER ONE : INTRODUCTION

1 1. 1 Introduction

3 1. 2 Aims of the Work

CHAPTER TWO: LITERATURE SURVEY

4 2. 1 Scope

5 2. 2 Gasoline Fuel and its Specifications

9 2. 3 Hydroisomerization Process

14

16 17

2. 3. 1 Catalysts for Hydroisomerization Process 2.3.1.1 Alumina 2.3.1.2 Zeolite

20 2.4 Previous Work

Contents

V

27 2.5 Catalysts Preparation

28 2.5.1 Impregnation

30 2.5.2 Calcination

30 2.5.3 Reduction

31 2.6 Catalysts Characterization

32 2.6.1 X-ray Diffraction (XRD)

32 2.6.2 Surface Area

33 2.6.3 Scanning Electron Microscopy (SEM)

CHAPTER THREE: EXPERIMENTAL WORK

34 3.1 Materials

37 3.2 Preparation of Modified Zeolites by Ion Exchange

37 3.2.1 Preparation of Barium- Zeolite

37 3.2.2 Preparation of HY- Zeolite

38 3.3 Catalysts Preparation

38 3.3.1 Preparation of Pt/ BaY and Pt/HY

38 3.3.2 Preparation of Pt/ ALR2ROR3

39

42

45

3.4 Experimental Unit

3.5 Procedure

3.6 Catalysts Characterization

Contents

VI

45

45 45 45

3.6.1 X-Ray Diffraction Analysis

3.6.2 Surface Area

3.6.3 Scanning Electron Microscopy (SEM) 3.6.4 Energy Dispersive X-Ray (EDAX) Analysis

CHAPTER FOUR: KINETIC ANALYSIS

46 4.1 Introduction

48 4.2 Model Development

51 4.3 Reactor Model

CHAPTER FIVE: RESULTS AND DISCUSSION

56 5.1 Characterization of Catalysts

56 5.1.1 X-ray Diffraction

57 5.1.2 Scanning Electron Microscopy (SEM) Analysis

58 5.1.3 Energy Dispersive X-ray (EDAX) Analysis

60 5.1.4 Surface Area

61 5.2 Effect of Operating Conditions

61

61

66

5.2.1 Effect of Temperature

5.2.1.1 Effect of Temperature on Conversion of light naphtha

5.2.1.2 Effect of Temperature on Total Conversion of light naphtha and Selectivity

Contents

VII

75

78

82

5.2.2 Effects of WHSV

5.2.3 Effect of Time

5.3 Results of Kinetic Study

CHAPTER SIX: CONCLUSIONS AND

RECOMMENDATIONS

90 6. 1 Conclusions

91 6. 2 Recommendations

92 REFERENCES

106 APPENDIX A (Volume Percent of Components)

118 APPENDIX B (Concentration of Components)

121 APPENDIX C (Conversion of Light Naphtha)

123 APPENDIX D (Reaction Rate Constants)

125 APPENDIX E (Percentage Selectivity and Conversion)

126 APPENDIX F (Sample of Calculation)

Nomenclature

VIII

Nomenclature Units

Definition Symbols

gm-mol/lit Concentration of Normal

Paraffins at any Time CRA

gm-mol/lit Initial Concentration of

Normal Paraffins CRARP

o

gm-mol/lit Concentration of iso-Paraffins CRiso

gm-mol/lit Concentration of Olefin CRN

( - ) integration constant A

mole/gcat. hr rate of reaction -rRA

hr Time T

K Temperature T

K Initial Temperature TP

o

hrP

-1 Weight Hour Space Velocity WHSV

( - ) Pre-Exponential Factor kRo

hrP

-1 Rate Constant for Paraffins kR1R

hrP

-1 Rate Constant for Olefins kR2

kJ/mole Activation Energy E

mole/hr Molar Flow Rate of

Component A FRA

mole/hr

Initial Molar Flow Rate of

Component A FRARP

o

Nomenclature

IX

atm-lit/gm-mol-K Gas Constant R

cmP

3 Volume of Reactor VRA

( - ) Conversion RX

cm Length of Reactor Zt

( - )

Integration Step for the Reactor

Length ∆z

Nomenclature

X

Abbreviations

Research Octane Number RON

Motor Octane Number MON

Reid Vapor Pressure RVP

American Society for Testing Materials ASTM

Methyl Tertiary-Butyl Ether MTBE

Universal Oil Product Company UOP

Butane Isomerization Unit BUTAMER

Mordenite MOR

iso-Pentane i-CR5

n-Pentane CR5

n-Hexane CR6

2-Methylpentane 2MP

3-Methylpentane 3MP

2,2-Dimethylbutane 2,2DMB

2,3-Dimethylbutane 2,3DMB

2,2-Dimethylpentane 2,2DMP

2,4-Dimethylpentane 2,4DMP

Chapter One Introduction

1


1.1

Introduction

The interest in improving the efficiency of the automotive motors

encourages the formulation of new catalysts and the development of

processes for gasoline.

Due to the environmental restrictions a reduction in allowable of lead

compounds levels and toxic compounds such as aromatics, in particular

benzene, olefin, sulfur-containing components in automobile gasoline

were imposed, as a result it forced refineries to implement new octane

enhancement projects.

Considering that branched-chain alkanes posses the greatest octane

numbers, the normal alkane's hydroisomerization is one of the most

effective project decisions in a direction favoring the least initial

investment approach as opposed to the best overall payout. The use of

gasoline containing higher content of these compounds is one alternative

to obtain clean fuel with high antiknock characteristics.

In order to increase the gasoline octane number, major petroleum

refineries used different units such as catalytic reforming, cracking,

alkylation, oligomerization, polymerization and isomerization

(hydroisomerization) [Benadda et al., 2003, Nattaporn and James, 2007].

It is important to mention here that the petroleum industry is looking for

economical solutions to meet new regulatory specifications for producing

environmentally clean fuels. Most of the implemented legislations require


2

a reduction and a limitation on the concentration of benzene in the

gasoline pool. This has increased the demand for high performance C5

and C6

naphtha isomerization technology because of its ability to reduce

the benzene concentration in the gasoline pool while maintaining or

increasing the pool octane.

Light paraffin isomerization has been used historically to offset octane

loss from lead-phase out and to provide a cost-effective solution to

manage benzene in motor fuels. In the current refining environment,

isomerate octane can be used to offset octane loss from MTBE phase-out

[Anderson et al., 2004]. Therefore, the hydroisomerization of light

naphtha (C5-C6

fractions) is an industrially important process and is used

in the production of high octane gasoline blend stocks. The process

involves the transformation (with minimal cracking) of the low octane

normal (and less branched) paraffin components into the high octane

isomers with greater branching of the carbon chain [Ravishankar and

Sivasanker, 1996, Andreas, 2003, Rachid et al., 2006, María et al., 2008].

In Iraq there is no clear strategies to reduce the demand for leaded

gasoline and aromatics (Benzene). Therefore, the hydroisomerization

units are regarded a good solution and a good start point strategy in

direction of clean fuels.

The metal– acid bifunctional catalysts, such as alumina or zeolite

supported Pt catalysts, are used in hydroisomerization of light paraffins

(n-pentane and n-hexane). It shows high efficiency in the isomerization of

alkanes. The isomerization of pentane and hexane is successfully carried

out using noble metals such as Pt- or Pd- supported on Al2O3, mordenite,

beta zeolite, and silicon catalyst. However, difficulties are encountered

with hydrocarbons larger than heptane because the cracking reaction


3

becomes more significant over these isomerization catalysts as the chain

length increases. So, some modification and pretreatment processes are

required to increase the catalyst activity, selectivity and life time [Takeshi

et al., 2003, Ping et al., 2009].

The literature mentions many studies which were focused to investigate

the hydroisomerization of n-paraffins [Liu et al., 1996, Chica and Corma,

1999, Yunqi et al., 2004, Salwa et al., 2007]. Few investigations have

used light naphtha as a feedstock for the process. On the other hand, many

authors made a kinetic study on the hydroisomerization unit for n-hexane

and n-heptane [Runstraat et al., 1997, Annemieke et al., 1997, Franciscus,

2002, Toshio, 2004, Matthew, 2008]. But only few studies dealling with

the hydroisomerization of light naphtha were published [Holló et al.,

2002, Carsten, 2006].

1.2

The main aims of the present work are:

Aims of the Work

1- Preparation of modified zeolites (BaY and HY) by ion exchange

method.

2- Preparation of Pt/ BaY and Pt/HY by impregnation method.

3- Study the hydroisomerization of Iraqi light naphtha over

bifunctional zeolite catalysts and test of the prepared catalysts

activity and selectivity under different operating conditions of

temperature, and WHSV.

4- To make a mathematical model to describe the reaction kinetics of

the hydroisomerization process.

5- To estimate kinetics parameters under different operating conditions

depending on the results of present experimental work.

Chapter Two Literature Survey

4

Chapter Two

Literature Survey 2.1 UScope

The hydroisomerization of light paraffins is an important industrial process to

obtain branched alkanes which are used as octane boosters in gasoline. Thus,

isoparaffins are considered an alternative to the use of oxygenate and aromatic

compounds, whose maximum contents are subjected to strict regulations in

order to protect the environment [Holló et al., 2002, Satoshi, 2003, Rafael et al.,

2005].

Hydroisomerization reactions are generally carried out over bifunctional

catalysts, often containing platinum. The metal component aids in increasing

the rate of isomerization, besides lowering catalyst deactivation.

The interest in the isomerization process is heightened with the phase out of

tetraethyl lead in 1970's, following the phase out of leaded gasoline due to the

introduction of clean air act amendments of 1990 in the USA and similar

legislation in other countries. Aromatics and olefin react with NORXR emission to

form ozone, thus contributing to smog formation [Maloncy et al., 2005].

Therefore, in many plants refineries have to minimize benzene yield. In Europe,

the aromatics content is limited since 2005 to content 35 vol% instead of 42

vol% and benzene to approximately zero level [Liu et al., 1996, Goodarz et al.,

2008].

There are various approaches in petroleum refineries to obtain high octane

number components, which include processes of cracking, reforming and


5

isomerization. Catalytic cracking is the process for converting heavy oils into

more valuable gasoline and lighter products. The cracking process produces

carbon (coke) which remains on the catalyst particle and rapidly lowers its

activity. On the other hand, the catalytic naphtha reforming is the chemical

process which converts low octane compound in heavy naphtha to high-octane

gasoline components, without changing carbon numbers in the molecule. This

is achieved mainly by conversion of straight chain naphtha to iso-paraffins and

aromatics over a solid catalyst. The isomerisation (hydroisomerization) is the

chemical process which converts low octane compound in light naphtha to high

octane number components via rearrangement of the molecular structure of a

hydrocarbon without gain or loss of any of its components. [Ulla, 2003,

Northrop et al., 2007 ].

The most widely applied alkane isomerization catalysts are chlorinated alumina

supported platinum and zeolite supported Pt or Pd. Also there are many of

different catalysts in which the selectivity isomerization increases and the

cracking decreases [Rachid et al., 2006].

A comprehensive literature review is shown in this chapter to include: gasoline

specification, hydroisomerization process catalysts and characterization.

UGasoline Fuel and Its Specefications U 2.2 Gasoline is one of petroleum fuels that consists of 5 carbons to 11 carbons in

the hydrocarbon compounds. Actually, gasoline contains up to 500

hydrocarbons, either saturated or unsaturated hydrocarbons and other

compounds. Saturated hydrocarbon known as paraffin or alkane forms the

major component of low octane number gasoline. Unsaturated hydrocarbon

includes olefins or alkenes, isoparaffins or alkyl alkane, arenes or aromatics.


6

Other compounds consist of alcohols and ethers [Lovasic et al., 1990, Carey,

1992].

Although there are several important properties of gasoline, the three that have

the greatest effects on engine performance are the Reid vapor pressure, boiling

range, and antiknock characteristics.

The Reid vapor pressure (RVP) and boiling range of gasoline govern ease of

starting, engine warm-up, rate of acceleration, loss by crankcase dilution,

mileage economy, and tendency toward vapor lock. Engine warm-up time is

affected by the percent distilled at 158°F (70°C) and the 90% ASTM distillation

temperature. Warm-up is expressed in terms of the distance covered to develop

full power without excessive use of the choke. Crankcase dilution is controlled

by the 90% ASTM distillation temperature and is also a function of outside

temperature [Takao, 2003].

The octane number of the gasoline depends on the number of branch carbon

atoms and the length of carbon atom chain. Octane number is a ratio of n-

heptane to iso-octane part by volume and commercially is between 60:40 and

40:60. n-heptane has octane number of zero while iso-octane has octane number

of 100. Higher octane rating is obtained by decreasing normal alkanes while

increasing iso-alkanes and cyclic hydrocarbons. Although unsaturated

hydrocarbons have desirable octane rating, for example acetylene, benzene and

toluene, they are toxic and their content in the gasoline should be reduced.

The octane number represents the ability of gasoline to resist knocking during

combustion of the air-gasoline mixture in the engine cylinder. Gasoline must

have a number of the other properties in order to function properly and to avoid

damage to the environment [Antos et al., 1995, Tore et al., 2007].


7

Octane ratings in gasoline are conventionally boosted by addition of aromatic

and oxygenated compounds. However, as a result of increasingly stringent

environmental legislation, the content of these compounds in gasoline is being

restricted and thus industry has been forced to investigate alternative processes

to reach the required octane levels [Rafael et al., 2008].

There are several types of octane numbers for spark ignition engines with the

two determined by laboratory tests considered most common: those determined

by the ‘‘motor method’’ (MON) and those determined by the ‘‘research

method’’ (RON). Both methods use the same basic type of test engine but

operate under different conditions. The RON (ASTM D-908) represents the

performance during city driving when acceleration is relatively frequent, and

the MON (ASTM D-357) is a guide to engine performance on the highway or

under heavy load conditions.

The difference between the research and motor octane is an indicator of the

sensitivity of the performance of the fuel to the two types of driving conditions

and is known as the ‘‘sensitivity’’ of the fuel. On the other hand, the mean

average of RON and MON is named rating. [Chica et al., 2001, Goodarz et al.,

2008]. An overview of octane numbers of different hydrocarbons, given in

Table (2.1).

In the oil industry CR5R and CR6 Rparaffins are typically used in hydroisomerization

units to obtain high octane number components. Paraffins larger thanCR6R, such

as heptane are usually present in catalytic reforming feed streams and converted

into aromatic compounds [Maloncy et al., 2005] .


8

Table (2.1): Octane number for different hydrocarbons [Goodarz et al.,

2008].

Compound

MON

RON

n-butane 89.6 93.8

Iso-butane 97.5 98.6

n-pentane 62.6 61.7

Iso-pentane 90.3 92.3

n-hexane 26 24.8

2-methyl pentane 73.5 73.4

3-methyl pentane 74.3 74.5

2,3-dimethyl butane 94.3 94.6

n-heptane 0 0

2-methyl hexane 46.4 42.4

3-methyl hexane 55.8 52

3-ethyl pentane 69.3 65

2,2-dimethyl pentane 95.6 92.8



Iso-octane 100 100


9

UHydroisomerization ProcessU 2.3

One of the important targets in the petroleum industry is the production of

branched alkanes by skeletal isomerisation of n-alkanes using solid acid

catalysts. Environmental concerns are now promoting clean gasoline with high

research octane number (RON) and low content of aromatics such as benzene.

Isomerization of light straight run naphtha has the potential to satisfy these

requirements.

The isomerisation process is catalytic reactions that involve rearrangement of

the molecular structure of a hydrocarbon without gain or loss of any of its

components. This process uses light naphtha (CR5R-CR6R fractions) in the production

of high octane gasoline blend stocks. The process involves the transformation

(with minimal cracking) of low octane normal (and less branched) paraffin

components into high octane isomers with greater branching of the carbon

chain. These types of processes are usually accomplished by bifunctional

catalysts that have both metallic and acidic function [Ravishankar and

Sivasanker, 1996, Maha, 2007].

The refineries of petroleum in the world include hydroisomerization unit.

Figure (2.1) shows the position of hydroisomerization unit in a petroleum

refinery. It is important to mention here that many petroleum companies

designed hydroisomerization processes to produce high octane gasoline.


10

Fig. (2.1) Location of hydroizomerization process in a modern petroleum

refinery [Ivanov et al.,2002].


11

Figure (2.2) shows a representative flow scheme hydroisomerization unit for the

the Penex™ process which provides highly isomerized light naphtha products.

Figure (2.2) Penex Process Flow Scheme [Gary, 2001].

Figure (2.3) shows the other flow scheme hydroisomerization unit for the the

Penex DIH process. On the other hand, the Butamer™ process that is shown in

Figure (2.4) provides highly isomerized butane products.


12

Figure (2.3) Penex DIH Process [Mikhail et al., 2001].

Figure (2.4) The Butamer™ process [Mikhail et al., 2001].


13

The dual-functional catalysts used in these processes are platinum on chlorided-

alumina support. These types of catalysts offer the highest activity to take

advantage of higher thermodynamic equilibrium iso- to normal ratios

achievable at lower temperatures. In order to improve the performance of these

processes.

If the normal pentane in the reactor product is separated and recycled, the

product RON can be increased by about 3 numbers (83 to 86 RON) . If both

normal pentane and normal hexane are recycled the product clear RON can be

improved to about 87 to 90. Separation of the normals from the isomers can be

accomplished by fractionation or by vapor phase adsorption of the normals on a

molecular sieve bed. The adsorption process is well developed in several large

units.

On the other hand, it is important to mention here that the isomerization process

is called hydroisomerization because its reaction requires HR2R gas to prevent

deactivation of catalysts. In hydroisomerization process, some hydrocracking

occurs during the reactions resulting in a loss of gasoline and the production of

light gas. The amount of gas formed varies with the catalyst type and age and is

sometimes a significant economic factor. The light gas produced is typically in

the range of 1.0 to 4.0 wt% of the hydrocarbon feed to the reactor. The main

composition of these gases is methane, ethane and propane [Gary, 2001, Shi et

al., 2008].

Two types of hydroisomerization processes of alkanes were developed, having

different objectives and technologies [Satoshi, 2003]:

1. The isomerization of lower n-alkanes (CR5R-CR7R) for the production of high-

octane components and of n-CR4R to i-CR4R as feed for the production of

alkylate.


14

2. The isomerization of the n-alkanes contained in paraffinic oils in

order to produce a significant decrease in the freezing temperature

and thus eliminate the need for dewaxing.

2.3.1 Catalysts of Hydroisomerization Process The first hydroisomerization unit was introduced in 1953 by UOP, followed in

1965 by the first BP unit, while in 1970 the first Shell Co. hydro-isomerization

(HYSOMER) unit was started up. All these processes take place in the gas

phase on a fixed bed catalyst containing platinum on a solid carrier. In the late

1950s and early 1960s, chlorinated platinum loaded alumina was used as a

catalyst. The major advantage of this catalyst was its low temperature activity

(T< 200°C) due to its high acidity. However the catalysts were sensitive

towards water and oxygenates and in addition had corrosive properties.

Furthermore, chlorine addition during the reaction is necessary to guarantee

catalyst stability [Gary, 2001, Maciej et al., 2002, Yunqi et al., 2004].

In the Hysomer process zeolite based catalysts were used which had the major

advantage of resistance to feed impurities. Industrially applied zeolites used

today are Pt-containing, modified synthetic (large-port) mordernite e.g. HS10 of

UOP, or HYSOPAR from Süd- Chemie. As higher hydrogen to hydrocarbon

ratios are needed recycle compressors and separators are required for this

technology [Jens, 1982, Corma et al., 1995, Christian, 2005].

The isomerization of hydrocarbons < CR6R is currently carried out very

successfully using bifunctional supported platinum catalysts. However,

difficulties are encountered with hydrocarbons larger than hexane since the

cracking reactions become more significant over platinum catalysts as the chain

length increases [Cuong et al., 1995]. Catalysts used in state of the art


15

isomerization-cracking reactors are bifunctional. They have a metal function

providing de-hydrogenation and hydrogen activation properties that are usually

supplied by group VIII noble metals like Pt, Pd, Ni or Co. The acid function is

the support itself and some examples include acid zeolites, chlorided alumina

and amorphous silica alumina. Noble metals have a positive effect on the

activity and stability of the catalyst. However they have a low resistance to

poisoning by sulfur and nitrogen compounds present in the processed cuts

[Busto et al., 2008].

In order to prepare a suitable catalyst for hydroconversion of alkanes, good

balance between the metal and acid functions must be obtained. Rapid

molecular transfer between the metal and acid sites is necessary for selective

conversion of alkanes into desirable products [Vagif et al., 2003].

Two of the attractive features of zeolite are that the catalysts are tolerant of

contaminants and that they are regenerable. The chlorinated alumina catalysts

are very sensitive to contaminants such as water, carbon oxides, oxygenates,

and sulfur. Thus, feeds and hydrogen must be hydrotreated and dried to remove

water and sulfur. Furthermore, the chlorinated alumina catalysts require the

addition of organic chloride to the feed in order to maintain their activities. This

causes contamination in the waste gas of hydrogen chloride, a scrubber is

needed to remove such contamination [Satoshi, 2003].

The UOP BenSat process uses a commercially proven noble metal catalyst,

which has been used for many years for the production of petrochemical-grade

cyclohexane. The catalyst is selective and has no measurable side reactions.

Because no cracking occurs, no appreciable coke forms on the catalyst to

reduce activity. Sulfur contamination in the feed reduces catalyst activity, but

the effect is not permanent. Catalyst activity recovers when the sulfur is

removed from the system [Meyers, 2004].


16

2.3.1.1 Alumina Alumina or aluminum oxide (AlR2ROR3R) is a chemical compound with melting

point of about 2000°C and sp. gr. of about 4.0. It is insoluble in water and

organic liquids and very slightly soluble in strong acids and alkalies. Alumina

occurs in two crystalline forms. Alpha alumina is composed of colorless

hexagonal crystals with the properties given above; gamma alumina is

composed of minute colorless cubic crystals with sp. gr. of about 3.6 that are

transformed to the alpha form at high temperatures. Figure (2.5) shows the

shape of AlR2ROR3R [Ulla, 2003].

The most common form of crystalline alumina, α-aluminium oxide, is known as

corundum. If a trace of the element is present it appears red, it is known as

ruby, but all other colorations fall under the designation sapphire. The primitive

cell contains two formula units of aluminium oxide. The oxygen ions nearly

form a hexagonal close-packed structure with aluminium ions filling two-thirds

of the octahedral interstices.

Identifiers Aluminium oxide

Figure (2.5) The shape of aluminium oxide

http://www.answers.com/topic/corundum�

http://www.answers.com/topic/ruby�

http://www.answers.com/topic/sapphire�


17

Typical alumina characteristics include:

Good strength and stiffness

Good hardness and wear resistance

Good corrosion resistance

Good thermal stability

Excellent dielectric properties (from DC to GHz frequencies)

Low dielectric constant

Low loss tangent

2.3.1.2 Zeolite Zeolites are microporous crystalline solids with well-defined structures.

Generally they contain silicon, aluminium and oxygen in their framework and

cations, water and/or other molecules wthin their pores. Zeolites occur naturally

as minerals or synthetic, Figure (2.6) shows the shape of different types of

zeolites [Matthew, 2008].

Because of their unique porous properties, zeolites are used in a variety of

applications with a global market of several milliion tonnes per annum. In the

western world, major uses are in petrochemical cracking, ion-exchange (water

softening and purification), and in the separation and removal of gases and

solvents. Other applications are in agriculture, animal husbandry and

construction. They are often also referred to as molecular sieves [Danny, 2002].

Zeolites have the ability to act as catalysts for chemical reactions which take

place within the internal cavities. An important class of reactions is that

catalysed by hydrogen-exchanged zeolites, whose framework-bound protons

give rise to very high acidity. This is exploited in many organic reactions,

including crude oil cracking, isomerisation and fuel synthesis [Jirong, 1990].


18

Figure (2.6) Structures and dimensions of different types

of zeolite [Tirena, 2005].

Underpinning all these types of reaction is the unique microporous nature of

zeolites, where the shape and size of a particular pore system exert a steric

influence on the reaction, controlling the access of reactants and products. Thus

zeolites are often said to act as shape-selective catalysts. Increasingly, attention

has focused on fine-tuning the properties of zeolite catalysts in order to carry

out very specific syntheses of high-value chemicals e.g. pharmaceuticals and

cosmetics [Eisuke et al., 2005].

The following properties make zeolites attractive as catalysts, sorbents,

and ion-exchangers [Jirong, 1990, Liu et al., 1996, Danny, 2002].


19

(1) well-defined crystalline structure.

(2) high internal surface areas (>600 mP

2P/g).

(3) uniform pores with one or more discrete sizes.

(4) good thermal stability.

(5) highly acidic sites when ion is exchanged with protons.

(6) ability to sorb and concentrate hydrocarbons.

The tetrahedral arrangements of [SiOR4R]P

-4P and [AlOR4R]P

-5P coordination polyhedra

create numerous lattices where the oxygen atoms are shared with another unit

cell. The net negative charge is then balanced by cations (e.g. K P

+P or

NHR4RP

+P). Small recurring units can be defined for zeolites named, ‘secondary

building units [Tirena, 2005].

The primary building blocks of all zeolites are silicon Si P

+4P and

aluminum Al P

+3P cations that are surrounded by four oxygen anions O P

-2P.

This occurs in a way that periodic three dimensional framework

structures are formed, with net neutral SiOR2R and negatively charged

AlOR2R.

The negative framework charge is compensated by cation (often NaR

+R)

or by proton (HP

+P) that forms bond with negatively charged oxygen

anion of zeolite.

The secondary building blocks differ between different types of

zeolites. In the top line of Figure (2.6) the structure of a faujasite type

zeolite is shown. The secondary building block of this zeolite is a

sodalite cage, which consists of 24 tetrahedra in the geometrical form of

a cubo-octahedron. The sodalite cages are linked to each other via a

hexagonal prism.


20

2.4 UPrevious Work Numerous researchers which have dealt with hydroisomerization using

different types of catalysts as follows:

Diaz et al., [1983] studied the isomerization and hydrogenolysis of hexanes on

an alumina-supported Pt-Ru catalyst. On ruthenium/ alumina catalysts, no

isomer products were detected in CR6R hydrocarbon reactions.

Methylcyclopentane hydrogenolysis was selective as confirmed by the high 3-

methylpentane/n-hexane ratios. Isomerization reactions on Pt(9.6 at.%)-Ru (0.4

at.%)/AlR2ROR3R were studied between 220 and 300°C. Skeletal rearrangements

proceeded from 220°C where Pt is inactive for this type of reactions, Very low

apparent activation energies in isomerization reactions of Cs-labeled

hydrocarbons were found for selective and nonselective cyclic mechanisms: 2-

methylpentane 3- methylpentane and 2-methylpentane n-

hexane, respectively. The results were explained using a bimolecular kinetic

model which can take into account the phenomenon as an increase either in

hydrocarbon coverage or in hydrocarbon adsorption strength on the catalyst

surface.

Raouf, [1994] investigated hydroconversion (isomerization, cracking and

cyclization of n-heptane) using three types of a crystalline zeolites as supports.

It was noted platinum supported zeolite catalyst vary in their activity and

selectivity towards n-heptane hydroconversion. Support types were found to

behave differently when impregnated with hexachloroplatinic acid. Applying

HR2RPtClR6R on acidic decationized and cationic zeolite type Y produce most active

catalyst toward isomerization at lower temperature and for hydrocrackingat

higher temperature. On the other hand, applying HR2RPtClR6 Ron zeolite type X

produce an active catalyst. The isomerizing activity is, however, lower than Y

type with moderate hydroisomerization and hydrocracking selectivity. While


21

for A type produces an active catalyst with low isomerizayion activity and a

higher cracking ability. catalytic activity of all types of Pt-zeolite catalysts

strongly depends on the Si/Al ratio. The order of the catalytic activity for the

catalysts is type Y > type X > Y type A.

Ravishankar and Sivasanker [1996] studied the hydroisomerization of n-hexane

was carried out at atmospheric pressure in the temperature range 473-573 K

over Pt-MCM-22. The influence of Pt content, the SiOR2R/A1R2ROR3R ratio of

thezeolite and the reaction parameters on the isomerization efficiency of the

catalyst was investigated. The optimum Pt content for the reaction was found to

be around 0.5 wt.%. At a constant Pt content of 0.5 wt.%, increasing the A1

content of the zeolite increased the catalytic activities and

isomerization/cracking ratios. The studies suggest that the reaction proceeds by

a bifunctional mechanism. Preliminary activity comparisons between Pt-H-

MCM-22, Pt-H-β and Pt-Hmordenite are reported.

Chica and Corma, [1999] tested The hydroisomerization of n-heptane to

dibranched and tribranched products for producing high octane gasoline has

been studied using unidirectional 12 Membered Ring (MR) zeolites with

different pore diameters, and zeolites with other pore topologies including one

with connected 12×10MRpores and two tridirectional 12 MR zeolites. Besides

the pore topology, the crystallite size of the zeolite was seen to be of paramount

importance for improving activity and selectivity. In a second part of the work,

a Light Straight Run naphtha including n-pentane and n-hexane and another

feed containing n-pentane, n-hexane, and n-heptane have been successfully

isomerized using a nanocrystalline Beta (BEA) zeolite. This can be a favorable

alternative to the commercial zeolite catalyst based on mordenite (MOR),

especially when n-heptane is present in the feed. They found, that with


22

increasing of reaction temperature within the range 240-380 P

ºPC, the conversion

of n-parafins increased. Also, the results clearly show that regardless of the

zeolite used the reactivity follows the order n-heptane> n-hexane> n-pentane.

Mordenite cracks n-heptane products very quickly, giving low selectivities to

branched products. While a larger unidirectional pore zeolite (SSZ-24) gives

better results than H-mordenite, the 12 MR tridirectional zeolites are the best

catalysts for the branching isomerization of n-heptane, owing to the faster

diffusion rates of reactants and products through the micropores. The zeolite

crystal size has been found to be of paramount importance, because the catalytic

activity and selectivity of a nanocrystalline Beta zeolite was better than that of

Beta zeolites with larger crystallites.

Shuguang et al., [2000] investigated the hydroisomerization of normal

hexadecane using three Pt/WOR3R/ZrOR2R catalysts prepared by different methods.

They found that preparation of the catalyst by impregnation with HR2RPtClR6R.6HR2RO

solution and another calcinations at 500°C results in a highly active and

selective platinum-promoted tungstate-modified zirconia catalyst

(Pt/WOR3R/ZrOR2R) for the hydroisomerization of n-hexadecane. The optimum

range of tungsten loading to achieve high isomerization selectivity at high n-

hexadecane conversion is between 6.5 and 8 wt%.

Falco et al. [2000] studied the effect of platinum concentration on tungsten

oxide-promoted zirconia over the catalytic activity for n-hexane isomerization

was studied. Catalysts were prepared by impregnation of tungsten oxide

promoted zirconia reaching up to 1.50% platinum, followed by calcination at

500℃. The n-hexane reaction was studied at 200℃, 5.9 bar, WHSV 4 and HR2R:

n-hexane (molar) ratio 7. It was found that catalytic activity and stability

increase for platinum concentrations above 0.05% because of higher hydrogen


23

availability at the surface, measured as a function of the methylcyclopentane/CR6R

isomers ratio. Further increments in platinum concentration do not produce

important modifications in catalytic activity or hydrogen availability.

Srikant and Panagiotis, [2003] used Pt/H-ZSM-12 as a catalyst for the

hydroisomerization of CR5R–CR7R n-alkanes and simultaneous saturation of benzene.

The performance of a Pt/H-ZSM-12 catalyst was compared with a Pt/H-beta

and a Pt/H-mordenite catalysts having a similar Si/Al ratio. It was concluded

that both the paraffin conversion and benzene conversion activity of all the

three catalysts remain stable even in the presence of sulfur. However, the results

showed that the conversion levels over the Pt/H-ZSM-12 and Pt/H-Mor catalyst

are lower compared to the levels obtained in the absence of sulfur at the same

temperature.

Abbass [2004], studied the transformation of n-hexane over

0.5wt%Pt/HY-Zeolite at 250-325˚C and WHSV=1.6hr P

-1P. The pressure

and hydrogen to feed mole ratio were kept constant at 1 bar and 2,

respectively. He use three type of promoter to study the activity of

isomerization catalyst Sn, Ni and Ti .The comparison between prepared

catalysts shows that the total isomer yield during the process with Sn-

Pt/HY-Zeolite catalyst was higher than the others and the total isomer

yield reach 63.95% vol. He found that adding a 0.5 wt% of W and Zr to

Sn-Pt/HY-zeolite catalyst obtains co-metal promoters catalysts, and the

total isomer yield reached to 81.14% vol. and 79.07% vol. respectively.

The results show that the co-metal promoters enhanced the yield of the

product more than that obtained by other types of promoters

Wong et al., [2005] Skeletal isomerization of npentane over Pt/HZSM5 and

Pt/WP/HZSM5 has been studied. Platinum (Pt) and Tungstophosphoric acid


24

(WP) have been immobilized on protonated ZSM5 by impregnation method

followed by calcinations at 823K. The state of WP on the zeolite surface was

characterized by XRD, FTIR, pyridine adsorption FTIR, TG/DTA and BET

surface area techniques. Catalytic testing in npentane isomerization was

performed in a continuous flow microreactor at 523K under hydrogen flow.

Prior to the reaction, catalyst was treated by heating at 573K under oxygen (30

min), nitrogen (10 min) and hydrogen (180 min) flow. Both of Pt/HZSM5 and

Pt/WP/HZSM5 shows high conversion of npentane and stable catalysts towards

the deactivation compare to those of HZSM5. Although, Pt/HZSM5 and

Pt/WP/HZSM5 exhibit high catalytic activity, Pt/WP/HZSM5 catalyzed the

isomerization of npentane more selectively compare to those of Pt/HZSM5due

to the presence of a strong acid.

Jafar et al., [2006] investigated CR5R-CR6R isomerization in light straight run

gasoline over platinum/mordenite zeolite. They studied effects of hydrogen

partial pressure on catalyst activity and n-paraffins conversions at T=260°C and

P=7-7.3 bar. They concluded that the activity increases with relatively sharp

slope for n-pentane, n-hexane and n-heptane which show the positive effect of

hydrogen on decreasing deactivation. The behavior of the curves in the

mentioned pressure range shows that the activity is constant while increasing

PHR2R. At T=270°C it seems as if the deactivation phenomenon takes place in

the pressure less than PHR2R. Also, at this temperature and while PHR2R>8.5, the

activity decreases evidently. By increasing the temperature, the slop of the

initial activity curve decreases but activity reduction is more evident in higher

pressures.

Rachid et al. [2006] investigated the present work is an evaluation of 1 wt.%

Pd/sulfated zirconium pillared montmorillonite catalyst in the

hydroisomerization reaction of two mfractions of light naphtha composed


25

mainly of CR5R and CR6R paraffins (feeds 1 and 2). Catalyst activity test was carried

out in a fixed-bed flow reactor at reaction temperature of 300 8C, under

atmospheric hydrogen pressure and weight hourly space velocity of 0.825 h P

-1P.

The reaction products showed high isomer and cyclane selectivity.

Monobranched and multibranched isomers were formed as well as C5 and C6

cyclane products. After the catalytic reaction, the total amount of benzene and

cyclohexane decreased by 30% for the ‘‘feed 1’’ and by 40% for the ‘‘feed 2’’

leading to methylcyclopentane formation in the products. A long-term

performance test catalyst for the two light naphtha fractions was also performed

and we observed an improving of the research octane number (RON) by 15–17

for, respectively, feeds 1 and 2.

Rachid et al., [2006] the present work is an evaluation of 1 wt.% Pd/sulfated

zirconium pillared montmorillonite catalyst in the hydroisomerization reaction

of two fractions of light naphtha composed mainly of CR5R and CR6R paraffins

(feeds 1 and 2). Catalyst activity test was carried out in a fixed-bed flow reactor

at reaction temperature of 300 8C, under atmospheric hydrogen pressure and

weight hourly space velocity of 0.825 h P

-1P. The reaction products showed high

isomer and cyclane selectivity. Monobranched and multibranched isomers were

formed as well as CR5R and CR6R cyclane products. After the catalytic reaction, the

total amount of benzene and cyclohexane decreased by 30% for the ‘‘feed 1’’

and by 40% for the ‘‘feed 2’’ leading to methylcyclopentane formation in the

products. A long-term performance test catalyst for the two light naphtha

fractions was also performed and we observed an improving of the research

octane number (RON) by 15–17 for, respectively, feeds 1 and 2.

Hadi [2007], studied the transformation of n-hexane over 0.3wt%

Pt/HY-zeolite, 0.5wt% Pt/HY-zeolite, 1wt% Pt/HY-zeolite and


26

0.3wt%Pt/Zr/W/HY-zeolite catalysts at 240-270˚C and LHSV=1-3hr P

-1P.

The pressure and hydrogen to feed mole ratio were kept atmospheric

and 1-4, respectively. She concluded that the n-hexane conversion

increases with increasing temperature, decreasing LHSV and increasing

Pt content. Also isomerization rate is independent of the Pt loading this

lead to the conclusion that dehydrogenation step is not rate limiting.

The effect of the PRH2R and PRnC6R orders on the overall reaction rate was

also studied by the author. She conclude that the value of hydrogen

order varies between -0.388 to -0.342, while the values of n-hexane

order were 0.262 to 0.219. The values of ERact, isomR were also obtained

and found to be equal to 119.7 kJ/mole.

Hadi also study the n-Hexane conversion enhancement by adding TCE

and by co-impregnation with Zr and W using 0.3wt%Pt/HY-zeolite

catalyst, and found that by adding 435ppm of TCE a 49.5mol.%

conversion was achieved at LHSV 1 h P

-1P, temperature 270°C and HR2R/nCR6R

mole ratio= 4, while the conversion was 32.4mol.% on

0.3wt%Pt/Zr/W/HY-zeolite at the same condition.

María et al. [2008] studied Three different distillatednaphthas streamsprovided

by REPSOLYPF, being formed by n-paraffins, iso-paraffins, aromatics and

naphthenes, were isomerized using an agglomerated catalyst based on beta

zeolite.Methane and ethane were not observed as final products revealing that

hydrogenolysis did not contribute to the cracking reaction. The highest overall

paraffin conversion value was obtained when feed A was introduced to the

process, due to its high molar composition of linear paraffins. It was observed

the presence of aromatic compounds (benzene and toluene) in the three feeds. A

total hydrogenation of benzene was achieved, keeping the rest of the aromatic


27

compounds under the limit imposed by legislation. Different naphthenic

compounds were obtained as a result of the hydrogenation of aromatic ones.

Goodarz et al. [2008] investigated two types of beta zeolites, different amounts

of platinum (0.2%, 0.5% and 1.2%) were loaded on the protonated form of

zeolite by incipient wet impregnation method applying hexachloroplatinic acid

in 0.2N Cl P

-P progressive ion solutions. Catalytic hydroisomerization reactions

were carried out at atmospheric pressure in a fixed bed reactor with vertical

placing and downward flow at three different temperatures, various WHSV

(weight hourly space velocity) and n-HR2R/n-HC (molar hydrogen/hydrocarbon)

ratio. Increase in Si/Al ratio in zeolites structures from 11.7 to 24.5 promoted

selectivity and yield. It was found that optimum platinum content depends on

the Si/Al ratio (zeolite acidity) in catalysts. Monobranched to dibranched

isomers ratio were correlated with a linear function of n-heptane conversion.

Such a correlation was found to be valid for various Si/Al ratios, metal content,

processing temperature and pressure, WHSV and hydrogen to hydrocarbon

ratio. Increase in WHSV, decreased n-heptane conversion, but enhanced

isomers selectivity. On the other hand, increasing the ratio of hydrogen to

hydrocarbon in the feed decreased conversion, while promoted isomers

selectivity.

2.5 UCatalysts Preperation A typical catalyst comprises one or more catalytically active components

supported on a catalyst support. Typically, the catalytically active components

are metals and/or metal-containing compounds. The support materials are

generally high surface area materials with specific pore volumes and


28

distribution [Lovasic et al., 1990, Raouf 1994, Novaro et al., 2000, Ramze,

2008].

Various methods for depositing catalytically active components on catalyst

supports are known, the catalyst support may be impregnated with an aqueous

solution of the catalytically active components. The impregnated support may

then be dried and calcined. The catalytically active component may also be

deposited onto the catalyst support by precipitation, a catalyst support is first

impregnated in an aqueous solution of a noble metal. The metal is then

precipitated on to the support by contacting the impregnated support with an

aqueous solution of an alkali metal salt [Iker, 2004].

Many factors influence catalysts preparation, such as solution concentration,

contact time, washing, temperature and method of reduction. Figure (2.7)

illustrates the general procedure for catalysts preparation [Shuguang et al.,

2000, Sergio et al., 2005].

2.5.1 Impregnation The manner in which a metal is introduced to a support will influence its

dispersion as well as the nature of the metal-support interaction. Supported

catalysts with low concentration of metal are generally prepared by

impregnation (or in some cases by ion exchanging). The choice of precursor salt

is made both for its solubility in water, and preferred solvent, and for its ability

to disperse throughout the support. Impregnation of pore supported catalyst is

achieved by filling the pores of support with solution of active species of metal

salt from which solvent is evaporated. The concentration of the metal content

can be increased by successive impregnation with intermediate precipitation

and thermal activation to isolubilize the supported species [Jensen et al., 1997,

Shuguang et al., 2000].


29

Figure (2.7): Typical arrangement of the catalysts

preparation [Anderson, 1975]

Impregnation with interaction occurs when the solute to be deposited

establishes a bond with the surface of the support at the time of wetting. Such

interaction results in a near-atomic dispersion of the active species precursor.

The interaction can be an ion exchange, an adsorption, or a chemical reaction

since ion exchanges occur much more frequently than the others [Lepage,

1987].


30

2.5.2 Calcination Calcination means any thermal treatment carried out with the purpose of

decomposing precursor compounds (usually with the evolution of gaseous

product) and / or allowing solid-state reactions to occur among different catalyst

components and / or making the catalyst sinter. The calcination temperature is

usually not lower than that of operation at the industrial plant [Thomas, 2004].

The type of calcination is assumed to be calcination in air, typically at a

temperature higher than the anticipated temperatures of the catalytic reaction

and catalyst regeneration.

The objectives of calcination are to obtain:

1- A well determined structure for the active agents or supports.

2- The parallel adjustment of the texture with respect to the surface and pore

volume.

3- A good mechanical resistance if it does not already exist

Among the various types of chemical or physico-chemical transformations that

occur during calcination, the following are the most important:

A- The creation of a generally macroporous texture through decomposition

and volatilization of substances previously added to the solid at the

moment of its shaping.

B- Modifications of texture through sintering: small crystals or particles will

turn into bigger ones.

C- Modifications of structure through sintering.

2.5.3 Reduction Reduction process is the final step in activation of supported metal catalyst,

which consists of the transformation of the metal precursor compound or its

oxide into the metallic state (metal atoms, small metal clusters).


31

Reduction involves reaction where the initiation process proceeds at distinct

sites (potential centers) on the surface of solid, followed by propagation of the

reaction zone from such a center through the solid, until complete conversion is

achieved upon contact of a metal oxide with hydrogen, oxygen ions are created.

The reaction process of oxides and halides can be represented by the following

equations [Vanden and Rijnten, 1979, Anderson et al., 1984]

MOR(s)R + HR2 RMR(s)R + HR2ROR(g) 2MXR(s)R +HR2(g) R2MR(s)R +2HXR(g) There are many factors affecting the reduction step, calcination of the deposited

precursor might cause several transformation and solid state reaction. Water

vapor inhibits reduction by blocking nucleus forming sites.

2.6 UCatalysts CharacterizationU Characterization of the catalyst is a predominate step in every catalyst study and

at every stage of the catalyst development. Critical parameters are measured not

only to check the effectiveness of each operation but also to provide

specification for future products. Characterization might be studied or

controlled in terms of support properties, metal dispersion and location and

surface morphology [Tirena, 2005].

In general, the quality of any catalyst is determined by a number of factors,

such as activity, selectivity for certain product, and stability. These parameters

are themselves functions of pretreatment conditions of the catalyst preparation

and reaction conditions. The interpretation of catalytic performance through the

mechanism of catalytic action depends on the study of the intrinsic chemical

and physical characteristics of the solid and a recognition of correlations


32

between some of these characteristics and catalytic performance [Sergio et

al., 2005]. Table (2.4) offer presents the general physcochemical properties of

catalysts and methods of measuring them.

2.6.1 X-ray Diffraction (XRD)

X-ray diffraction is a technique to identify the crystallinity of catalysts. This

technique is based on the knowledge that each compound in catalyst has a

different diffraction pattern. The crystallinity can be determined by comparing

the intensity of a number of particular peaks to the intensity of the same peaks

obtained by standard samples [Marı´a et al., 1997, Benitez et al., 2006].

The diffraction pattern is plotted based on the intensity of the diffracted beams.

These beams represent a map of reciprocal lattice parameter, known as Miller

index (hkl) as a function of 2θ, which satisfies Bragg equation:

nλ = 2d sin θ -------------------------(2.1)

where n is an integer number, λ is the wavelength of the beam d is interplanar

spacing and θ is a diffraction angle. Equation (2.1) is obtained from Bragg

diffraction as shown in Figure (2.8).

2.6.2 Surface Area In practice, the surface area is calculated from the Brunauer-Emmett-Teller

(BET) equation based on the physical adsorption of an inert gas at constant

temperature, usually nitrogen at the temperature of liquid nitrogen. The

principle of measurement consists in determining the point when a mono-

molecular layer of gas covers the surface of the catalyst [Antonio et al., 2006].


33

Figure (2.8) Bragg diffraction [Tirena, 2005].

2.6.3 Scanning Electron Microscopy (SEM)

Scanning electron microscopy is an extremely powerful technique for obtaining

information on the morphology and structural characteristics of catalysts. There

are some advantages in this technique, which are great depth of focus, the

possibility of direct observation of external form of real objects, and the ability

to switch over a wide range of magnification, so as to zoom down to fine detail

on some part identified in position on the whole object [Shuguang et al., 2000].

Chapter Three Experimental Work

34

Chapter Three

Experimental Work

3.1 UMaterials

In the present work, different materials and compounds are used as

follows:

• Iraqi-Light-Naphtha

Iraqi light-naphtha is used as a feedstock in the present investigation. It was

supplied by Al-Dura Refinery (Baghdad). Table (3.1) shows the specifications

of Iraqi-light naphtha.

• Hydrogen

Hydrogen gas was obtained from Al-Mansour Factory/Baghdad with

a high purity of (99.9%).

• Zeolite

NaY-zeolite was supplied from Zeolyst International UWE Ohlrogge (VF)

as an extrudate (2mm×4mm). The chemical analysis of this zeolite was done

by the General Establishment of Geological Survey and Mining, and the

results are shown in Table (3.2).

• Alumina Alumina support (γ-AlR2ROR3R) with spherical shape and average size of 3mm

was supplied by FLUKA AG company.

• Hexachloroplatinic Acid

Hexachloroplatinic acid (HR2RPtClR6R.6HR2RO) was supplied by REIDEL- DE

HAEN AG SEELZE -HANNOVER chemicals Ltd.This hexachloroplatinic

acid contains 40 wt% of Pt and has a molecular weight of 517.92 g/mol. On


35

the other hand, other chemicals used such as Barium Chloride (BaClR2R),

Ammonium Chloride (NHR4RCl) and Hydrochloric acid (HCl) were supplied

from FLUKA AG Company.

In the present work the Iraqi light naphtha are used as a feedstock in

hydroisomerization process to produce high octane gasoline. Table (3.3)

shows the chemical composition of light naphtha. It is important to mention

here that the main products of hydroisomerization process are i-pentane, 2,2-

DMB, and 2,3-DMB.

Table (3. 1) The propetries of Iraqi light naphtha.

Property Data

Sp.gr. at 15.6℃ 0.702

API 80.5

Distillation I.B.P. 5 Vol.% distillated 10 Vol.% distillated 20 Vol.% distillated 30 Vol.% distillated 40 Vol.% distillated 50 Vol.% distillated 60 Vol.% distillated 70 Vol.% distillated 80 Vol.% distillated 90 Vol.% distillated 95 Vol.% distillated E.B.P. Total distillate Total recovery residue Loss

37℃ 42℃ 48℃ 52℃ 56℃ 60℃ 65℃ 68℃ 76℃ 82℃ 86℃ 92℃ 124℃ 96 Vol.% 0.7 Vol.% 3.3 Vol.%

Octane Number 68.2

Sulfur Content < 3ppm (Desulfurized)

Kinematic Viscosity at 25℃ 5.4 10P

-7 PmP

2P/s


36

Table (3.2): Chemical composition of zeolite

Table (3.3) The composition of Iraqi light naphtha.

Compound SiOR2 ALR2ROR3 NaR2RO CaO FeR2ROR3 MgO TiOR2 L.O.I

Percentage 45.85 20.50 12.00 0.140 0.060 0.120 0.010 19.14

Composition Vol.%

n-Butane 0.20

iso-Pentane 3.80

n-Pentane 15.27

2,2DMB 7.20

2,3DMB 7.98

2MP 12.47

3MP 10.50

n-Hexane 12.74

2,2DMP 3.37

Cyclohexane 2.87

2,4DMP 5.65

Methylcyclopentane 3.34

Benzene 3.88

n-Heptane 1.85

Toluene 2.47

CR7RP

+ 3.14


37

3.2 UPreparation of Modified Zeolites by Ion Exchange: 3.2.1 Preparation of Barium- Zeolite: BaY form was prepared by ion exchanging of the parent zeolite NaY with

(3N) barium chloride solution. Thus, 36.642 gm of barium chloride in 100

ml distilled water was contacted with 20 gm of zeolite with stirring for 1 hr

at 50℃. The batch of zeolite was left in the solution for 72 hr at 25 . The

exchanged barium zeolite was then filtered off, washed with deionized water

to be free of chloride ions and dried at 110℃ over night. The dried samples

were then calcined at 550℃ for 5 hr in the presence of OR2R. Then the

temperature was increased to 550 ℃ at a rate of 10°C/min. The chemical

analysis showed that a 82% of Na was exchanged by Ba in zeolite Y. It was

done by the General Establishment of Geological Survey and Mining.

3.2.2 Preparation of HY- Zeolite: HY form was prepared by ion exchanging of the parent NaY zeolite with

(3N) ammonium chloride solution. Thus, 16.047 gm of ammonium chloride

in 100 ml distilled water was contacted with 20 gm of zeolite with stirring

for 1 hr at 50℃. The batch of zeolite was left in the solution for 72 hr at

25℃. The exchanged ammonium zeolite were then filtered off, washed with

deionized water to be free of chloride ions and dried at 110℃ over night.

The dried samples was then calcined at 500℃ for 7 hr in presence of OR2R.

Then the temperature was increased to 500 ℃ at a rate of 10°C/min. The

chemical analysis showed that a 87% of Na was exchanged by ammonium

chloride to form HY. It was done by the General Establishment of

Geological Survey and Mining


38

3.3 UCatalysts Preparation 3.3.1 Preparation of Pt/ BaY and Pt/HY The barium and hydrogen exchanged zeolites were loaded with 0.5 wt % Pt

by impregnation with aqueous solution of hexachloroplatinc acid

(HR2RPtClR6R.6HR2RO). The platinum content of the catalyst was calculated from

the weight of the support and the amount of the metal in impregnation

solution.

Thus, 0.25 gm of hexachloroplatinc acid (40 wt % Pt) was dissolved in 25 ml

of distilled water. Then the solution was added for 20 gm of the zeolite

sample as drop wise with mixing for 2 hr at 25℃. The mixture was left at

room temperature for 24 hr, it was stirred intermediately during this time.

The mixture was then slowly evaporated to dryness over a period of 8 hr by

heating on a heat mantle. The resulting catalyst was dried in air at 110℃ for

additional 24 hr. Then the dried catalyst was calcined at 400 ℃ for 3 hr and

reduced with hydrogen at 350℃ for 2 hr [Satoshi, 2003, Goodarz, 2008,

Dhanapalan et al., 2008].

The prepared catalysts at this time is called Pt/BaY and Pt/HY. 3.3.2 Preparation of Pt/ ALR2ROR3 The γ-AlR2ROR3R (spherical shape with an average size of 3mm) was loaded with

0.5 wt % Pt by impregnation with aqueous solution of hexachloroplatinc acid

(40% Pt). Thus, 0.25 gm of hexachloroplatinc acid (40 wt % Pt) was

dissolved in 25 ml of distilled water. Then, the solution was added 20 gm of

γ-AlR2ROR3R sample as drop wise with mixing for 4 hr at 25℃. The mixture was

left at room temperature for 24 hr, The mixture was stirred intermediately

during this time. The resulting catalyst was dried in air at 110℃ for

additional 24 hr. Then, the dried catalyst was calcined at 400℃ for 3 hr and

reduced with hydrogen at 350℃ for 3 hr.


39

3.4 UExperimental Unit U The experiments were carried out in a continuous catalytic unit. Figure (3.1)

shows the general view of pilot plant for light naphtha hydroisomerization

process, and Figure (3.2) shows a schematic diagram of the apparatus. The

reaction was carried out in catalytic fixed bed tubular reactor, which is made

of stainless steel. The reactor dimensions were 2cm internal diameter, 3cm

external diameter and 21cm height (reactor volume 66 cmP

3P). The reactor was

charged for each experiment with 20g of catalyst located in the middle zone,

while, the upper and lower zones were filled with glass beads.

The reactor was heated and controlled automatically using an electrical

furnace type Heraeushan (Germany) with maximum temperature of 1000 P

°PC,

it was possible to measure the temperature of the catalyst bed using

calibrated thermocouple sensor type K (iron-constantan) inserted into the

middle of the catalyst bed in order to measure and the control reaction

temperature.

The reactor was fitted with accurate means for control of pressure, gas and

liquid flow rate. The liquid (light naphtha) was pumped with a dosing pump

type Prominent (Beta/4- Germany). The liquid hydrocarbons were stored in a

QVF storage tank with capacity of 2000cmP

3P. The liquid flow was passed

through calibrated burette of 52cmP

3P.


40

Figu

re (3

.1):

Gen

eral

vie

w o

f pilo

t pla

nt fo

r lig

ht n

apht

ha h

ydro

isom

eriz

atio

n pr

oces

s.


41

Figu

re (3

.2):

Sch

emat

ic d

iagr

am o

f the

exp

erim

enta

l app

arat

us.


42

3.5 UProcedure

Twenty grams of fresh catalyst was charged into the middle zone of the

reactor. Iraqi light naphtha was fed to the dosing pump from a glass burette

supplied from a feed tank. Feed was pumped at atmospheric pressure. The

hydrogen gas flow to the unit was controlled by a calibrated gas hydrogen

flowmeter. Downstream pressure was controlled with a back pressure valve.

The hydrogen gas before it passed to the reactor passed through molecular

sieve (5A) type to remove any impurities or moisture. The hydrogen gas was

mixed with hydrocarbon before the reactor inlet. The mixture was preheated

before entering the reactor to 150 P

°PC, and then passed through the catalyst

bed.

The performance of catalysts was tested under different operating

temperatures of (230, 250, 270, 290, and P

P310 P

°PC). The hydrogen to

hydrocarbon molar ratio was kept constant at 4. The weight hourly space

velocities (WHSV) was (1.5, 3, and 4.5hr P

-1P). All types of catalysts were

activated in the catalytic reactor before each run for 2 hr in a flow of

hydrogen. A pre-test period of one hour was used before each run to adjust

the feed rates and temperature to the desired values.

The reaction products was cooled by cooling system and collected in the

separator in order to separate the non-condensed gases from the top of the

separator and the condensed liquid hydrocarbons from bottom of the

separator. Then, the products samples were analyzed using Gas

Chromatograph type Shumids 2014 GC using flame ionization detector

(FID). The column dimensions are 0.22mm internal diameter and length 25m

and film thickness 0.2μm. The analyses were carried out under the

conditions shown in Table (3.3), and the retentions time for the


43

hydrocarbons are shown in Table (3.4). It is important to mention here that,

the calibration of gas chromatography was carried by injection the same

amount of a standard into the Gas Chromatography.

Table (3.3): Gas chromatograph analysis conditions

Temperature program for the column

Initial temperature 50 °C

Final temperature 120 °C

Hold time 5 min

Rate of temperature 5 °C/min

Total time 20 min

Other variables

Pressure at the inlet column 1atm

Pressure of hydrogen 55 KPa

Injection temperature 180 °C

Pressure of carrier gas NR2 5 atm

Linear velocity 31.3 cm/min

Split ratio 100


44

Table (3.4): Retention times of hydrocarbons in the catalytic

isomerization of light naphtha reaction.

Components Retention times (Sec)

iso-pentane 1.676

n-pentane 1.724

2,2- dimethyl butane 1.924

2,3- dimethyl butane 1.927

2-methylpentane 1.954

3-methelpentane 1.994

n-hexane 2.037

2,2-dimethelpentane 2.580

Cyclohexane 2.699

2,4-dimethelpentane 2.815

Methylcyclpentane 2.983

Benzene 3.096

n-heptane 3.212

Toluene 4.884


45

3.6 UCatalysts Characterization 3.6.1 X-Ray Diffraction Analysis. X-Ray diffraction analysis was done in the Lab of University of Manchester

in United Kendom. Analysis was carried out using Phillips X" Pert Pro PW

3719 X-ray diffractometer with Cu KαR1R and Cu KαR2 Rradiation source

(λ=1.54056 Å and 1.54439 Å) respectively. Slits width 1/8 and 1/4 have

been applied. Tension=40 kV, Current=30 mA. The range of angles scanned

was (0 to 80) on 2θ.

3.6.2 Surface Area and Pore Volume

The catalysts surface areas and pore volume were determined using (BET)

method, the apparatus used was Micromeritics ASAP 2400 located in

Petroleum Research Center / Ministry of Oil (Baghdad).

The surface area and pore volume of the catalysts was determined by

measuring the volume of nitrogen gas adsorbed at the liquid nitrogen

temperature (- 196 °C). The volume of gas adsorbed was measured from the

pressure decrease that results from the adsorption of a dose of known volume

of gas.

3.6.3 Scanning Electron Microscopy (SEM) Scanning electron microscopy (SEM) measurements were carried out using a

Phillips SEM equipped with a XL30 Field Emission Gun, available at the

Lab of University of Manchester in UK.

3.6.4 Energy Dispersive X-Ray (EDAX) Analysis The modified zeolite catalyst was subjected to the EDAX analyzer that was

done in the Lab of University of Manchester in United Kendom and

connected with the SEM to measure the composition of the zeolite.

Chapter Four Kinetic Analysis

46

Chapter Four

Kinetic Analysis

4.1 Introduction The main aim of the present study is to analyze the kinetics of hydroisomerization

process by assessing the effect of reaction time and reaction temperature on the

performance of the catalysts. The process feed involves light naphtha which

contains many reactions. Therefore, the hydroisomerization reaction has three

stages as follows: [Sergio et al., 2003, Antonio et al., 2006, Pitz et al., 2007,

Marios et al., 2009]:

1- Adsorption of n- paraffin molecule on dehydrogenation- hydrogenation site

followed by dehydrogenation to n- olefins.

2- Desorption of n- olefin from the dehydrogenation sites and diffusion to a

skeletal rearranged site, which converts n- olefin into iso- olefin.

3- Hydrogenation of iso- olefin into iso- paraffin molecule.

In general, the hydroisomerization of n- paraffin can occur through the bifunctional

scheme shown below:

n-Paraffin n-Olefin i- Olefin i- Parffin


47

The hydroisomerization process of light naphtha is regarded as one of the

complex chemical reactions network, where such types of reactions take on a

metal and acid sites of catalysts [Antonio et al., 2006, Eric et al., 2007 ].

Therefore, the mathematical modeling of the hydroisomerization process is a

very important tool in petroleum refining industries. It translates experimental

data into parameters used as the basis of commercial reactor process optimaization.

In the hydroisomerization of alkanes it is supposed that the alkane is

dehydrogenated to an alkene on the metal site. The alkene is then protonated on the

acid site to a carbenium ion, which is subsequently isomerized to a branched

carbenium ion. The branched carbenium ion gives the proton back to the acid site,

the resulting branched alkene is hydrogenated on the metallic site. The branched

alkane is formed, and can be desorbed from the catalyst surface. The reaction

mechanism scheme is shown in Figure (4.1) [Franciscus, 2002, Maha, 2007,

Matthew, 2008].

Figure (4.1) The general reactions mechanism for isomerization of n-alkane [Franciscus, 2002].


48

4.2 Model Development In developing the model of the catalytic hydroisomerization kinetic the following

assumptions are taken into account:

1. The system is isothermal and in steady state operation with first order

reactions.

2. The reaction is carried out in the gas phase with constant physical properties

and without pressure drop.

3. The temperature and concentration gradients in the radial direction can be

neglected.

The objective of kinetic study is to construct from the experimental results of the

process, a mathematical formulation that can be used to predict the kinetic

parameters of the hydroisomerization process. Therefore, the main aim of the

present work is to estimate the reaction parameters (reaction rate constant,

activation energy and pre-exponential factor) depending on the experimental work

results under real isomerization conditions.

In present work, it is suggested kinetic model for the reactions of

hydroisomerizayion for light naphtha (n-paraffin) can be considered by the

following scheme depending on the present model assumptions which can be

formulated to the following equations:

Figure (4.1) The suggested reactions of light naphtha isomerization of the present work.


49

Let CRAR denotes the mole fraction of n-paraffin present at any time t,

CRN R the mole fraction of n-olefin, CRisoR the mole fraction of i-paraffin.

Then, the mole balance can be formulated mathematically as follows:

--------------------------------(4.2)R

-------------------------------(4.3)

By integration of equation (4.2) CRAR = CRARP

°P at t= 0 we get

CRAR = CRARP

° Pexp (- kR1Rt) -------------------------------------

(4.4)

Substituting the equation (4.4) in equation (4.3) yield:

= kR1RCRARP

° Pexp (- kR1Rt) - kR2RCRN R--------------------------------------

(4.5)R

Rearrangement of equation (4.5) gives:

= kR1RCRA

= kR1RCRAR-kR2RCRN


50

R R+R RkR2RCRN R= kR1RCRARP

° Pexp (- kR1Rt)

This is a linear first order differential equation as follows:

+ Py =Q where P = kR2 R, Q = kR1RCRARP

° Pexp (- kR1Rt)

Then, can be solving this differential equation as follows:

yρ = Q dx + c where ρ integration factor which can be calculated from:

ρ =

where integration factor is exp (kR2Rt).

Then by integrate of differential equation will give:

exp (kR2R-kR1R) t + A ----------------------------------(4.6) CRNR exp (kR2Rt) =

where A is the integration constant, and it can be determined using the following

conditions:

t = 0 , CRNR = 0 Thus :

--------------------------------- (4.7)

Then:

CRNR exp (kR2Rt) = [exp (kR2R-kR1R)t – 1]. Then

A = -


51

CRNR = [exp(-kR1Rt) – exp(-kR2Rt)] -----------------------------------(4.8)

But, all products come from initial n-paraffin in the light naphtha feed, then, CRAR° = CRAR + CRNR + CRisoR -----------------------------------(4.9)

Then substituting the equations (4.4) and (4.8) in equation (4.9), will give:

CRAR° = CRARP

° Pexp (- kR1Rt) + [exp(-kR1Rt) – exp(-kR2Rt)] + CRiso R-------(4.10)

Rearrangement of equation (4.10) gives:

CRisoR = CRAR° - CRARP

° Pexp (- kR1Rt) - [exp(-kR1Rt) – exp(-kR2Rt)]

-------(4.11)

4.3 Reactor Model To develop a reaction model for an integral reactor, a material balance is made

over the cross section of a very short segment of the tubular catalyst bed, as shown

in Figure (4.2):

CRisoR = CRAR° [1- exp (- kR1Rt) - [exp(-kR1Rt) – exp(-kR2Rt)]


52

Figure (4.2) Segment of packed bed reactor.

A stady- state mole balance on reactant P gives:

[ flow rate] – [flow rate] + [ rate of ] = [ rate of ] in out generation accumulation Then, the resulting equation is:-

R RVRAR (-rRAR)=0 [Mole Balance] -----------(4.12) FRAR

FRAR

Z+∆Z Z


53

0, the differential material balance reduces to :- As: ∆Z

AA r

dVdF

−= -------------------------------------------------------- (4.13)

For a flow system, FA has previously been given in terms of the entering

molar flow rate FA and the conversion X:

----------------------------------(4.14)

Substituting equation (4.13) into (4.12), gives differential form of the design

equation for a plug flow reactor:

-----------------------------------(4.15) = rA FAP

ο

Integration with the limit V=0 when X=0 gives:

------------------------------- (4.16)

But, the rate of reaction for first order is:

First order reaction --------------------------------(4.17)

Substituting equation (4.17) in equation (4.16), will give:

- FAP

οP X FA= FAP

ο

V= FAP

οP

rA= k1 CA


54

----------------------------(4.18) V= FAP

οP

----------------------------(4.19) CA= CA◦

----------------------------(4.20) V=

By integration will give

[(1+ є)Ln – Єx] ---------------------------(4.21) V=

k1= [(1+ є)Ln – Єx] ------------------------------(4.22)

From equation (4.22), the values of k1 are calculated for any component

From Arrhenius equation plot Ln k1 vs 1/T, the slope represents –E/RT to

calculate the activity energy (E) and the intercept represents Ln k◦ as shown in

Figure (4.3).

Lnk1=Ln k◦ - -----------------------------(4.23)

Substitute values of k1 in equation (4.11) to calculate values of k2 .


55

Figure (4.3) The relationship between Lnk1 vs 1/T using

Arrhenius equation.

Chapter Five Results & Discussion

56


5.1 UCharacterization of Catalysts

5.1.1 X-ray Diffraction

X-ray diffraction analysis was used to determine the crystalline structure

of Y zeolite on 2θ scale. From this pattern different phases and average

crystalline sizes were determined, as shown in Figure (5.1). These results

clearly point to standard specification of Y zeolite [Novaro et al., 2000].

From the point of view of analysis, this step of characterization will give

us real identification of used zeolite specification and its crystalline

structure.

Figure (5.1): XRD spectrum of the Na/Y catalyst.


57

5.1.2 Scanning Electron Microscopy (SEM) Analysis

Scanning electron microscopy (SEM) was used to determine the morphology and

average crystallite size of the catalysts. Figures (5.2) and (5.3) show the SEM

monograph of Pt/HY and Pt/BaY respectively. As can be seen, platinum particles

were homogeneously distributed, where the white spots represent a platinum

particles and black zone represent the supported, with the average diameter of the

Pt/HY catalyst is 4µm, while for Pt/BaY catalyst is 3.5µm. These results are in

accord with that the faujasite crystallite size range (2 -5)µm. SEM is used ensue

good impregnation of active component.

Figure (5.2): A SEM-picture of Pt/HY 0.5 wt% Pt catalyst used in pilot experiments.


58

Figure (5.3): A SEM-picture of monograph Pt/BaY.

5.1.3 Energy Dispersive X-ray (EDAX) Analysis

Figure (5.4) shows the EDAX of the Y zeolite. This test is equipped with

SEM measurements.The pattern of the analysis indicates that the zeolite

composition is in accord with standard Y zeolite and agrees well with X-

ray diffraction measurement of Figure (5.1) for the same catalyst type

[Novaro et al., 2000, Somyod et al., 2004].


59

Figure (5.4): Energy Dispersive X-ray (EDAX) of zeolite NaY.

Also, from Figure (5.4) it is clear that the Si and Al are the main

components of zeolite structure where the Si/Al ratio is equal to

approximately 1.58. This ratio is calculated depending on the composition

measurement inside the zeolite structure and pores at different positions in

the structure. Such measurements give more accurate results for Si/Al

ratio.


60

5.1.4 Surface Area

Surface areas of catalysts were determined by phisorption method (BET). The

results of surface area tests tabulated in Table (5.1). It is noted, the platinum

/zeolite catalysts give the highest values of the surface area and pore volume as

compared with the platinum/alumina catalyst. It is seen there that high surface area

and large pore volume Pt/BaY and Pt/HY catalysts are more selective to isomers

than Pt/Al2O3

catalyst which have low surface area and pore volume.

Table (5.1) Physical characteristics of the catalysts.

Catalysts Surface Area m2 Pore Volume cm/gm 3/gm

Pt/Al2O 288.86 3 0.3307

Pt/BaY 421.3 0.65

Pt/HY 425 0.67


61

5.2 The hydroisomerization process is affected by different parameters such as catalyst

type, WHSV, and reaction temperature.

Effect of Operating Conditions

5.2.1 Effect of Temperature

5.2.1.1 Effect of Temperature on Conversion of Light Naphtha

Figures (5.5) to (5.13) and Appendix C show the effect of temperarure on

conversion of light naphtha For the catalysts examined (Pt/BaY, Pt/HY,

and Pt/Al2O3). It can be seen that (n-pentane, n-hexane, 2MP, 3MP) are

the most common. From the general behavior of these figures, it was noted

that with increasing of reaction temperature within the range 230-310ºC,

the conversion of light naphtha increased, that is due to the increasing of

sites that can be contribute in the reaction when the temperature increases.

It was concluded that the catalytic activity of different catalysts for

hydroisomerization of light naphtha decreases in the following order:

Pt/Al2O3 > Pt/HY > Pt/BaY, as an example, the conversion of light

naphtha using 0.5wt% Pt/Al2O3 and WHSV of 1.5h-1 increases from

31.2% at 230ºC to 64.7% at 310º

C. These results are in agreement with the

works of Ravishankar and Sivasanker [1996], Chica and Corma, [1999],

Rachid et al. [2006].


62

Figure (5.5): Influence of reaction temperature on conversion ■n-C6 , ♦n-C5

, ▲Total, ●3MP, ×2MP.

Figure (5.6): Influence of reaction temperature on conversion ■ n-C6 , ♦ n-C5



63



Figure (5.8): Influence of reaction temperature on conversion ■ n-C6 , ♦ n-C5 , ▲Total, ●3MP, ×2MP.


64






65



Figure (5.12): Influence of reaction temperature on conversion ■ n-C6 , ♦ n-C5 , ▲Total, ●3MP, ×2MP.


66



5.2.1.2 Effect of Temperature on Total Conversion of Light Naphtha and Selectivity

Figures (5.14) to (5.22) and appendix A show the effect of reaction

temperature on the conversion of light naphtha and hydroisomerization

selectivity toward branched isomers hydrocarbons over different catalysts

and WHSV. According to the results of G.C. analysis, the isomerization of

light naphtha leads to the formation of mainly mono-branched and di-

branched molecules. Also, a very small amount of aromatic products is

detected. It was noted that, the total conversion of light naphtha for all

types of catalysts is increased with increase in reaction temperature. At

reaction temperatures of 230, 250, 270℃ for Pt/BaY and Pt/HY catalysts,

the selectivity to isomers is increased with no aromatics (51, 74, and 89)


67

for Pt/BaY and (63,81, and 95) for Pt/HY, while, at 290 and 310℃

selectivity to isomers is decreased and with formation of few aromatics

products (67 and 46) for Pt/BaY and (89 and 73) for Pt/HY. On the other

hand, for Pt/AlR2ROR3R catalyst it was found as temperature increase, the

selectivity to isomerization reaction decreases gradually because of

creating of more and more aromatic products. It shows that for Pt/AlR2ROR3R

catalyst at 230℃ is the best temperature of increasing isomerization

selectivity. It is important to mention here that for hydroisomerization

process over Pt/AlR2ROR3R catalyst it is necessary to use low temperatures in

order to get good results of isomerization selectivity and to prevent

aromatic formation. This is in agreement with the investigation of [Falco

et al. [2000], and María et al. [2008].

Moreover, it is important to say that the aromatization of alkanes must be avoided

because of new regulations requiring the reduction of aromatic compounds because

of their detrimental environmental effects. The environmental concerns have

prompted legislation to limit the amount of total aromatics, particularly benzene, in

gasoline. The specifications allow no more than 35% (v/v) of aromatic

compounds. The reduction of aromatics will have a negative impact on gasoline

octane ratings. To satisfy the environmental specifications, the total hydrogenation

of benzene could be achieved, keeping the rest of the aromatic compounds under

the limit imposed by legislation [Chica et al., 2001, Marı´a et al., 2005].

On the other hand, the acidity of the catalyst has a major influence on the

hydroisomerization and hydrocracking yields. The pore opening of the molecular

sieve can also have a major effect on the selectivity of these catalysts. If the pore

opening is small enough to restrict the larger iso-paraffins from reacting at the

acidic sites inside the pore, the catalyst will show good selectivity for converting n-


68

paraffins. Therefore, the ideal catalyst for selective hydroisomerization of n-

paraffins should have both selectivity for isomerization, which comes from the

proper balance of acidity and hydrogenation activity, and selectivity for reacting

only with n-paraffins, which comes from the size of the pore openings of the

molecular sieve used. [Deldari, 2005, Christian, 2005].

Figure (5.14): Influence of reaction temperature on Vol.% ♦ Aromatic , ■ Isomer

, ▲Conversion.


69


, ▲Conversion.


, ▲Conversion.


70


, ▲Conversion.


, ▲Conversion.


71


, ▲Conversion.


, ▲Conversion.


72


, ▲Conversion.


, ▲Conversion.


73

The same results also show that the Pt/HY catalyst is the most suitable catalyst for

hydroisomerization process because it reduces the aromatic content with high

selectivity toward isomers. It was concluded that the Pt/HY catalyst is more active

than Pt/BaY because it gives high conversion and selectivity to hydroisomerization

reaction as shown in Figures (5.23) to (5.25). On the other hand, Pt/Al2O3

catalyst

is the most active for light naphtha conversion at 230℃. But, under reaction

temperature greater than 230℃ the reaction selectivity goes toward aromatic and

hydrocracking products. Therefore, according to these results the optimum

reaction temperature for isomerization is at 270℃ for all catalysts where such

temperature gives the highest catalyst selectivity toward isomers. On the other

hand, it is indicated that the Pt/HY catalyst gives higher selectivity toward isomers

than Pt/BaY. This is attributed to the effect of cation type that forms the final

catalyst, because the hydrogen atom is larger than the barium atom and its high

acidity.

Figure (5.23): Influence of reaction temperature on isomerization selectivity ♦ Pt/BaY, ■ Pt/HY , ▲Pt/Al2O3

.


74


.


.


75

5.2.2 Effects of WHSV Figures (5.26) to (5.30) show the effects of WHSV on light naphtha conversion

for different catalysts at different reaction temperatures. According to many

references [Goodarz et al., 2008, Ping et al. 2009] the WHSV is a very important

factor that determines the performance of hydroisomerization process of light

naphtha. The WHSV was varied by changing the flow of liquid hydrocarbon feed

and H2 gas so that the molar ratio of hydrogen to hydrocarbon remained

unchanged at a value of 4. This value represents the best ratio for isomerization

reaction [Novaro et al., 2000, Ivanov et al., 2002, Rafael et al., 2008]. It was noted

that the conversion of the light naphtha decreases with increase in WHSV. The

results show, that when WHSV equal 1.5hr-1 gives the highest conversion for all

catalyst types. While, at 4.5hr-1

value of WHSV gives the lowest conversion.

Therefore, it is concluded that there is a inverse relationship between conversion

and WHSV, where the increase in WHSV decreases the residence time, which

leads to a plenty of contact time of feedstock with the catalyst inside reactor, and

the latter means effective conversion for n-paraffins. This is in agreement with the

explanation of Goodarz et al. [2008].


76

Figure (5.26): Effect of WHSV on light naphtha conversion ♦ Pt/BaY, ■ Pt/HY, ▲Pt/Al2O3

.

Figure (5.27): Effect of WHSV on light naphtha conversion ♦ Pt/BaY, ■ Pt/HY, ▲Pt/Al2O3.


77


.


.


78


.

5.2.3 Effect of Time

Figures (5.31) to (5.35) illustrate the change in conversion with time in the light

naphtha conversion into various products over Pt/HY catalyst at (230 to 310℃),

WHSV (1.5hr P

-1P) and atmospheric pressure. These figures are regarded as samples

for groups of figures of the change in conversion with time for Pt/BaY, Pt/HY, and

Pt/AlR2ROR3R catalysts at (230 to 310℃),WHSV (1.5 to 4.5hr P

-1P) at atmospheric

pressure which have the same behavior for the all catalyst types. The major

reaction products are iso- pentane, 2,2- DMB, and 2,3-DMB. Additionally, there

is another component that has low percentage in light naphtha and has not a clear

effect on conversion of hydroisomerization process and yield distribution, such as,

the methylcyclopentane fraction which increases while the cyclohexane and

benzene fractions decrease [Rashed et al., 2006].


79

The results indicate that the catalysts have high activity at initial period. It is

noted, that the conversion of light naphtha increases with increase in time, while,

the selectivity of isomerization decreases with time. This conclusion is based on

catalyst deactivation because of formation of coke precursors over the acid sites.

Catalyst deactivation is a result of a number of unwanted chemical and physical

changes. The three major categories of deactivation mechanisms are sintering,

poisoning, and coke formation or fouling. They may occur separately or in

combination, but the net effect is always the removal of active sites from the

catalytic surface. On the other hand, fouling (coking) formation is the most

important type of catalyst deactivation in hydroisonerization process . The

catalytic coke is gradually formed on both metal and supports by different

mechanisms. When the operation is extended, the coke precursors will

predominantly accumulate on the supports and continually polymerize through

acid catalyzed reactions [Novaro et al., 2000, Andreas, 2003, Khalid et al., 2007].


80

Figure (5.31) Effect of time on conversion and selectivity for hydroisomerization of light naphtha ♦ n-C5, ■n-C6, ▲3MP, ×i-C5

, +2,2-DMP, ●2,3DMP.

Figure (5.32) Effect of time on conversion and selectivity for hydroisomerization of light naphtha ♦ n-C5, ■n-C6 ▲3MP, ×i-C5

, +2,2-DMP, ●2,3DMP.


81


, +2,2-DMP, ●2,3DMP.


, +2,2-DMP, ●2,3DMP.


82


, +2,2-DMP, ●2,3DMP.

5.3

According to our approach that shown in chapter 4 in which explained the kinetic

behavior of hydroisomerization process of light naphtha as shown in Figure (4.1).

The present study has calculate the kinetic parameters such as K

Results of Kinetic Study

1, K2, Ko

, and

activation energy (E) depending on present experimental work results.

n-Paraffin Olefin iso-Paraffin


83

The classical mechanism proceeds via an olefin intermediate that is formed

through a dehydrogenation step on the metal site. As the olefin concentration under

hydroisomerization conditions is rather low, due to the equilibrium position of the

strongly endothermic dehydrogenation step, it has to be guaranteed that a sufficient

number of olefins is present to be converted to form a carbon on the acidic sites of

zeolite which is rather low as well. It was observed that the rate for the

isomerization reaction strongly depends on the chain length of the involved

alkanes. The longer the chain length, the more stabilized the associated carbenium

ion and the faster the isomerization reaction [Sergio et al., 2003, Christian, 2005].

The activation energies of the isomerization reaction was determined over the

temperature of 230, 250, 270, 290, and 310℃ at a atmospheric pressure and a

WHSV of 1.5, 3, and 4.5h-1 for conversion levels of up to15% where a linear

correlation between the logarithmic isomerization of reaction rate constant (Lnk1)

and the inverse temperature (1/T) is observed as shown in Figures (5.36) to (5.44),

where the slope represents the (-E/R) and the intercepts represent the pre-

exponential factor (Lnko

). The apparent activation energies for the different

catalysts are in the range between (15 – 24 kJ/mol) and are given in the summary

of the characterization data in Table (5.2) which are calculated from Arrhenius

equation. It is noted, that there are a simple differences among its value. In general,

the values of apparent activation energies are small and that the reduction values

indicate the selectivity of hydroisomerization.

Ln k1=Ln ko - Arrhenius equation


84

On the other hand, the reaction rate constant (k1

) can be calculated via equation

(4.22) as follows:

Also, in our approach that is given shown in chapter 4, the equation which

describes the behavior of hydroisomerization process of light naphtha is derived.

Also, the reaction rate constant (k2

) parameter can be calculated from this equation

as follows. The results of the kinetic parameters tabulated in Appendix D.

Table (5.2) Apparent activation energies (kJ/mol) for C5, C6

, and 3MP.

Catalysts n-C n-C5 3MP 6

Pt/BaY 22 21 15

Pt/HY 23 20 16

Pt/Al2O 22 3 24 17

k1= [(1+ Є) Ln – Єx]

Ciso = CA° [1- exp (- k1t) - [exp(-kR1Rt) – exp(-kR2Rt)]


85

Figure (5.36) Arrhenius plot ♦WHSV=1.5hr-1, ■WHSV=3hr-1, ▲WHSV=4.5hr-1

.

Figure (5.37) Arrhenius plot ♦WHSV=1.5hr-1, ■WHSV=3hr-1, ▲WHSV=4.5hr-1.


86


.


.


87


.



88


.



89


Chapter Six Conclusions & Recommendations

90

Chapter Six

Conclusions & Recommendations

6.1 ConclusionsThe following major conclusions can be drawn from the present study:

1. The hydroisomerization of Iraqi light naphtha was carried out to give high

selectivity toward isomers. Therefore, the results of the present work can be

applicable to the design of hydroisomerization unit in Iraq.

2. The results show that the best operating temperature for the

hydroisomerization process (with high selectivity toward isomerization) is

270°C.

3. The results obtained in this work show high selectivity with Pt/HY and

Pt/BaY catalysts, while, Pt/Al2O3

Pt/HY > Pt/BaY > Pt/Al

has the low selectivity to the isomers.

Therefore, the prepared catalysts follows the following sequence: 2O3

which, are 95%, 89%, and 30% respectively.

4. The total conversion of light naphtha was achieved to be 64.7% over

Pt/Al2O3 catalyst at 310℃ and WHSV1.5hr-1

Pt/Al

, with high aromatic formation,

while, at the same conditions with Pt/HY and Pt/BaY catalysts it was 52 %,

50% respectively. Therefore, the following sequence for the catalysts

conversion is concluded at 310℃: 2O3 > Pt/HY > Pt/BaY

Chapter Six Conclusions & Recommendations

91

and this sequence applicable for all temperatures range.

5. In the present work, a kinetic model was developed to describe the

hydroisomerization of light naphtha. This model was developed depending

on our experimental data results and approach. Then, the kinetic parameters

(k°, k1, and E) are estimated, while, k2

can be calculated from the derived

equation as follows:

6. It was observed that the values of apparent activation energy for

hydroisomerization of light naphtha (n-pentane, n-hexane, and 3MP) over

the prepared catalyst takes the following order:

E of 3MP < E of n-Hexane < E of n-Pentane

7. The conversion of light naphtha and selectivity of hydroisomerization

increase with a decrease in WHSV. 1.5hr-1

is the best which give high rate of

isomers.

6-2

1- The investigation can be extended to study the influence of varying the

pressure on activity and selectivity.

Recommendetions

2- An extension of theoretical work can be done by assuming a higher order of

reaction rate for hydroisomerization reactions (not first order).

Ci-P = CP° [1- exp (- k1t) - [exp(-kR1Rt) – exp(-kR2Rt)]

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Appendix A

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Appendix A

The volume percent of component in product Table(A1) The volume percent of component in product

using Pt/Ba-Y Zeolite(WHSV=1.5h-1

)

Volume%

Tim

e m

in.

Tem

per

ature

℃

2-4 DMP

2-2DMP

2-3 DMB

2-2DMB

n-C6

3-MP

2-MP

n-C5

i-C5

6.86

4.25

9.49

8.69

14.6

9.31

11.20

14.25

5.49

60

230

6.77

4.20

9.43

8.65

14.5

9.17

11.18

14.18

5.32

90

6.75

4.20

9.38

8.51

14.3

9.11

11.10

14.06

5.24

120

6.75

4.15

9.33

8.38

14.2

9.0

11.00

13.85

5.11

150

6.94

4.32

10.14

9.86

13.77

9.10

10.91

14.00

7.25

60

250

6.88

4.25

10.10

9.82

13.63

9.00

10.89

13.81

7.15

90

6.84

4.18

9.96

9.77

13.28

8.81

10.55

13.77

7.00

120

6.70

4.18

9.88

9.75

13.00

8.62

10.42

13.70

6.87

150

7.17

5.56

11.25

10.12

12.21

8.70

9.90

11.72

9.22

60

270

7.15

5.48

11.18

10.10

12.17

8.49

9.87

11.53

9.14

90

7.13

5.45

11.15

10.07

11.95

8.31

9.38

11.38

8.09

120

7.12

5.38

11.11

9.95

11.91

8..24

9.31

11.21

8.94

150

7.15

5.55

11.18

9.84

11.54

8.28

9.30

11.15

9.00

60

290

7.08

5.43

11.11

9.73

11.52

8.17

9.25

11.08

8.97

90

6.95

5.38

10.96

9.68

11.42

7.96

9.23

10.85

8.89

120

6.81

5.15

10.87

9.35

10.87

7.88

9.19

10.75

8.70

150

6.83

5.21

10.66

9.85

11.32

8.44

8.79

10.22

8.93

60

310

6.79

5.18

10.45

9.71

10.87

8.14

8.50

10.13

8.85

90

6.77

5.14

10.22

9.54

10.61

7.87

8.45

10.87

8.41

120

6.49

5.08

9.88

9.45

10.42

7.65

8.23

10.67

8.33

150

Appendix A

107

Table(A2) The volume percent of component in product

using Pt/Ba-Y Zeolite (WHSV=3h-1

)

Component Vol.%

Tim

e m

in.

Tem

per

ature

℃

2-4 DMP

2-2DMP

2-3 DMB

2-2DMB

n-C6

3-MP

2-MP

n-C5

i-C5

6.15

3.95

9.12

8.00

15

9.57

11.86

14.73

5.20

60

230

6.11

3.94

9.00

7.98

14.94

9.51

11.79

14.70

5.17

90

5.95

3.90

8.95

7.95

14.80

9.43

11.75

14.66

5.05

120

5.89

3.76

8.91

7.86

14.61

9.41

11.63

14.57

4.97

150

6.25

4.27

9.82

8.79

14.73

9.28

11.49

14.29

6.51

60

250

6.18

4.25

9.80

8.70

14.54

9.17

11.35

14.25

6.48

90

6.15

4.16

9.75

8.68

14.46

9.00

11.25

14.18

6.36

120

6.00

4.00

9.61

8.62

14.37

8.91

11.19

14.00

6.27

150

6.65

5.21

10.64

9.34

14.26

9.17

11.00

14

7.53

60

270

6.63

5.15

10.60

9.33

14.15

9.15

10.84

13.93

7.49

90

6.60

4.97

10.68

9.28

14.00

9.00

10.76

13.85

7.45

120

6.45

4.81

10.59

9.22

13.77

8.72

10.51

13.76

7.35

150

6.55

4.98

10.31

9.24

13.81

8.93

10.78

13.88

7.23

60

290

6.45

4.94

10.25

9.15

13.61

8.82

10.44

13.78

7.15

90

6.37

4.86

10.16

8.88

13.53

8.77

10.33

13.53

7.14

120

6.28

4.82

10.00

8.73

13.50

8.66

10.00

13.18

6.89

150

6.36

4.76

10.17

7.95

13.21

8.83

9.64

13.32

6.89

60

310

6.25

4.67

10.15

7.90

13.00

8.80

9.60

13.16

6.86

90

6.13

4.62

9.93

7.81

12.97

8.73

9.52

12.87

6.73

120

5.97

4.60

9.66

7.72

12.83

8.68

9.33

12.55

6.62

150

Appendix A

108


using Pt/Ba-Y Zeolite(WHSV=4.5h-1

)

Component Vol.%

Tim

e m

in.

Tem

per

ature

℃

2-4 DMP

2-2DMP

2-3 DMB

2-2DMB

n-C6

3-MP

2-MP

n-C5

i-C5

5.78

3.65

8.45

7.43

15.61

10.20

12.00

15

4.50

0

230 5.76

3.64

8.42

7.37

15.59

10.08

11.90

14.8

4.46

15

5.71

3.59

8.37

7.32

15.45

9.91

11.89

14.6

4.40

30

5.68

3.57

8.34

7.31

15.36

9.85

11.67

14.5

4.35

5.95

4.18

9.61

7.87

15.20

9.87

11.70

14.70

4.81

0

250 5.89

4.00

9.55

7.69

14.84

9.82

11.62

14.60

4.77

15

5.85

3.88

9.54

7.65

14.73

9.76

11.55

14.45

4.63

30

5.79

3.83

9.33

7.64

14.66

9.53

11.31

14.38

4.43

6.65

5.00

10.70

8.97

14.86

9.83

11.35

14

5.59

0

270 6.63

4.95

10.68

8.96

14.65

9.62

11.12

13.84

5.55

15

6.60

4.87

10.64

8.91

14.61

9.53

10.84

13.75

5.54

30

5.96

4.79

10.51

8.83

14.50

9.47

10.64

13.69

5.47

6.61

4.88

10.42

8.94

14.53

9.55

10.79

13.92

5.23

0

290 6.60

4.84

10.33

8.83

14.21

9.35

10.63

13.88

5.15

15

5.85

4.61

10.25

8.78

14.13

9.16

10.27

13.73

5.06

30

5.77

4.58

10.12

8.56

13.91

8.94

10.18

13.33

5.00

6.57

4.66

10.17

8.22

13.83

9.31

10.23

13.42

5.17

310

6.45

4.57

9.89

8.00

13.65

9.15

10.17

13.25

4.98

6.30

4.40

9.75

7.81

13.25

8.90

9.87

13.10

4.94

6.25

4.33

9.55

7.66

13.00

8.75

9.45

12.96

4.72

Appendix A

109


using Pt/H-Y Zeolite(WHSV=1.5h-1

)

Component Vol.%

Tim

e m

in.

Tem

per

ature

℃

2-4 DMP

2-2DMP

2-3DMB

2-2DMB

n-C6

3-MP

2-MP

n-C5

i-C5

7.00

4.67

10.37

10.00

13.23

9.00

10.70

12.75

7.56

60

230

6.97

4.65

10.33

9.94

13.15

8.88

10.69

12.70

7.50

90

6.88

4.65

10.32

9.90

12.97

8.79

10.65

12.62

7.48

120

6.79

4.60

10.22

9.78

12.80

8.76

10.45

12.44

7.45

150

6.85

4.80

11.65

10.65

12.65

8.75

10.52

11.00

8.65

60

250

6.80

4.79

11.60

10.60

12.63

8.70

10.50

10.61

8.59

90

6.81

4.73

11.59

10.59

12.18

8.51

10.44

10.55

8.55

120

6.76

4.70

11.56

10.55

11.87

8.43

10.40

10.40

8.54

150

8.10

6.22

13.18

11.12

11.10

8.70

9.75

8.71

9.22

60

270

7.95

6.20

13.15

11.11

11.00

8.44

9.70

8.34

9.19

90

7.87

6.14

13.10

11.00

10.91

8.39

9.40

8.33

9.12

120

7.80

6.00

12.96

10.97

10.60

8..00

9.15

8.25

9.11

150

8.00

5.98

12.87

10.76

9.95

8.18

9.12

8.60

9.77

60

290

7.88

5.96

12.45

10.75

9.91

8.13

9.10

8.47

9.68

90

7.84

5.95

12.32

10.69

9.88

7.92

9.00

8.37

9.65

120

7.81

5.90

12.25

10.49

9.56

7.89

9.00

8.13

9.63

150

7.62

5.70

12.66

10.45

9.33

8.10

8.60

8.48

9.55

60

310

7.55

5.65

12.44

10.33

9.12

7.90

8.47

8.45

9.46

90

7.43

5.59

12.42

10.30

9.00

7.81

8.45

8.36

9.41

120

7.40

5.58

12.30

10.18

8.88

7.50

8.19

8.22

9.40

150

Appendix A

110


using Pt/HY Zeolite(WHSV=3h-1

)

Component Vol.%

Tim

e m

in.

Tem

per

ature

℃

2-4 DMP

2-2DMP

2-3 DMB

2-2DMB

n-C6

3-MP

2-MP

n-C5

i-C5

6.25

4.00

10.77

9.00

13.55

9.49

11.34

13.33

6.00

0

230 6.24

3.98

10.75

8.98

13.48

9.45

11.25

13.10

5.98

15

6.20

3.98

10.70

8.97

13.40

9.35

11.11

12.85

5.93

30

6.18

3.95

10.55

8.89

13.32

9.30

10.97

12.70

5.93

6.33

4.60

11.00

9.80

13.37

9.09

11.22

13.00

7.44

0

250 6.33

4.56

10.89

8.76

13.34

8.96

11.10

12.75

7.38

15

6.32

4.49

10.79

9.75

13.29

8.87

10.65

12.66

7.37

30

6.16

4.47

10.75

9.60

13.11

8.81

10.48

12.50

7.29

7.00

5.44

12.26

10.54

13.00

9.00

11.00

10.00

8.66

0

270 6.94

5.43

12.16

10.48

12.85

9.95

10.66

9.93

8.64

15

6.91

5.40

12.08

10.40

12.66

8.74

10.45

9.86

8.60

30

6.85

5.33

11.90

10.40

12.45

8.70

10.00

9.79

8.55

6.75

5.37

11.89

10.33

12.65

8.50

10.27

9.84

8.60

0

290 6.74

5.25

11.85

10.27

12.50

8.46

10.14

9.83

8.45

15

6.66

5.14

11.78

10.15

12.44

8.35

10.00

9.33

8.44

30

6.62

5.11

11.70

10.10

12.39

8.29

9.76

9.20

8.32

6.69

5.34

11.57

10.14

12.00

8.33

9.84

9.36

8.36

310

6.65

5.33

11.55

10.00

12.77

8.20

9.44

9.16

8.30

6.60

5.26

11.47

9.88

11.45

9.12

9.23

8.88

8.23

5.54

6.20

11.44

9.82

11.19

8.80

9.12

8.80

8.13

Appendix A

111


using Pt/H-Y Zeolite(WHSV=4.5h-1

)

Component Vol.%

Tim

e m

in.

Tem

per

ature

℃

2-4 DMP

2-2DMP

2-3 DMB

2-2DMB

n-C6

3-MP

2-MP

n-C5

i-C5

5.80

3.68

8.60

7.45

15.42

10.00

11.34

14.84

4.80

0

230 5.79

3.66

8.59

7.44

15.33

9.88

11.30

14.66

4.76

15

5.74

3.62

8.53

7.41

15.25

9.82

11.17

14.56

4.75

30

5.73

3.59

8.44

7.36

15.17

9.66

11.10

14.35

4.68

6.00

4.18

9.82

8.00

15.17

9.71

11.11

14.45

4.91

0

250 5.95

4.10

9.78

7.89

14.74

9.63

10.92

14.44

4.89

15

5.91

4.00

9.78

7.87

14.64

9.45

10.85

14.31

4.83

30

5.90

4.00

9.65

7.77

14.54

9.34

10.79

14.30

4.76

6.85

5.14

10.77

9.18

14.75

9.55

11.00

13.77

5.80

0

270 6.83

5.12

10.76

9.16

14.61

9.47

10.88

13.74

5.79

15

6.83

5.09

10.70

9.11

14.57

9.38

10.76

13.62

5.74

30

6.70

5.10

10.67

9.10

14.43

9.27

10.55

13.49

5.69

6.79

5.00

10.60

9.12

14.53

9.51

10.56

13.62

5.73

0

290 6.67

4.93

10.57

9.06

14.40

9.24

10.34

13.57

5.70

15

6.61

4.92

10.55

8.98

14.00

9.10

10.12

13.50

5.63

30

6.57

4.75

10.49

8.87

13.80

8.78

10.00

13.30

5.50

6.74

4.70

10.48

8.93

13.73

9.20

10.22

13.37

5.48

310

6.70

4.69

10.40

8.85

13.60

9.15

9.97

13.16

5.44

6.65

4.69

10.33

8.81

13.19

8.60

9.77

13.00

5.38

6.53

4.50

10.20

8.67

13.00

8.33

9.33

12.90

5.22

Appendix A

112


using Pt/Al2O3(WHSV=1.5h-1

)

Component Vol.%

Tim

e m

in.

Tem

per

ature

℃

Tolu.

Benz.

2-4 DMP

2-

2DMP

2-3DMB

2-

2DMB

n-C6

3-MP

2-MP

n-C5

i-C5

3.44

3.78

7.56

5.84

11.14

9.97

12.68

9.78

10.30

11.75

6.33

0

230

3.12

3.77

7.45

5.80

10.85

9.75

12.67

9.77

10.27

11.71

6.15

15

3.12

3.65

7.38

5.78

10.62

9.74

12.60

9.74

10.22

11.69

5.89

30

3.10

3.45

7.35

5.70

10.55

9.74

12.56

9.66

10.17

11.56

5.85

4.5

4.95

7.44

5.27

10.87

9.41

10.87

9.60

10.26

8.00

5.45

0

250

4.29

4.93

7.39

5.22

10.67

9.00

10.82

9.59

10.15

7.54

5.12

15

4.26

4.88

7.38

5.20

10.61

8.87

10.65

9.35

9.97

7.53

5.10

30

4.23

4.85

7.33

5.18

10.44

8.66

10.33

9.11

9.92

7.47

5.08

6.47

5.80

7.37

5.16

10.22

9.22

9.80

9.35

10.17

6.90

5.33

0

270

6.37

5.78

7.34

5.08

10.19

8.97

9.71

9.29

10.00

6.79

5.25

15

6.29

5.75

7.23

4.95

9.98

8.57

9.45

9.15

9.89

6.76

5.12

30

6.18

5.73

7.18

4.88

9.84

8.23

9.32

8..97

9.76

6.55

5.00

9.21

7.57

6.86

5.00

9.76

8.57

8.54

8.83

9.83

6.86

5.11

0

290

9.13

7.46

6.78

4.93

9.54

8.28

8.44

8.79

9.75

6.72

4.94

15

9.10

7.42

6.66

4.88

9.52

7.98

8.36

8.65

9.60

6.64

4.88

30

8.97

7.34

6.45

4.85

9.48

7.90

8.18

8.46

9.58

6.44

4.80

10.00

7.80

6.32

4.87

9.42

8.44

7.35

8.72

9.65

5.98 4.80

310

9.81

7.74

6.25

4.78

9.36

8.21

7.21

8.64

9.58

5.97 4.75

9.72

7.65

6.15

4.74

9.30

8.13

6.93

8.53

9.45

5.84 4.63

9.44

7.62

6.11

4.68

9.28

8.00

6.74

8.49

9.36

5.33 4.55

Appendix A

113


using Pt/Al2O3(WHSV=3h-1

)

Component Vol.%

Tim

e m

in.

Tem

per

ature

℃

Tolu.

Benz.

2-4 DMP

2-2 DMP

2-3DMB

2-2DMB

n-C6

3-MP

2-MP

n-C5

i-C5

3.32

3.18

7.38

5.61

10.87

9.45

13.32

9.88

11.22

12.90

5.89

0

230

3.28

3.15

7.36

5.60

10.54

9.39

13.26

9.86

11.17

12.84

5.88

15

3.16

3.15

7.36

5.55

10.46

9.34

13.12

9.82

11.09

12.80

5.79

30

3.11

3.12

7.25

5.49

10.39

9.33

13.00

9.80

10.92

12.66

5.55

5.20

4.79

7.35

5.00

10.65

9.38 11.15

9.65

10.88

10.23

5.65

0

250

5.11

4.64

7.38

4.93

10.59

9.17 11.08

9.57

10.84

10.14

5.60

15

5.09

4.50

7.33

4.91

10.51

8.55 10.95

9.55

10.77

10.11

5.47

30

4.98

4.50

7.29

4.86

10.42

8.43 10.87

9.49

10.68

9.98

5.37

6.54

4.84

7.28

4.98

10.10

8.96 11.00

9.46

10.63

8.34

5.22

0

270

6.22

4.67

7.27

4.96

10.00

8.86

10.78

9.34

10.57

8.32

5.13

15

6.13

4.57

7.25

4.89

9.87

8.63

10.65

9.33

10.48

8.25

4.96

30

6.00

4.44

7.00

4.81

9.79

8.60

10.49

9..20

10.25

8.19

4.89

8.98

5.57

6.70

4.90

9.66

8.38

9.74

9.40

10.33

8.45

5.15

0

290

8.86

5.54

6.65

4.83

9.48

8.19

9.61

9.24

10.26

8.44

5.08

15

8.42

5.50

6.52

4.81

9.37

8.17

9.55

9.11

10.13

8.38

4.93

30

8.33

5.40

6.41

4.77

9.22

8.05

9.42

9.00

10.10

8.34

4.86

9.00

6.34

6.48

4.75

9.31

7.97

9.10

9.23

10.25

7.98 4.90

310

9.10

6.25

6.43

4.73

9.25

7.95

8.85

9.19

10.17

7.86 4.85

9.12

6.19

6.42

4.69

9.12

7.85

8.78

8.88

9.95

7.80 4.73

9.23

6.16

6.28

4.50

8.95

7.77

8.75

8.65

9.90

7.72 4.68

Appendix A

114


using Pt/Al2O3(WHSV=4.5h-1

)

Component Vol.%

Tim

e m

in.

Tem

per

ature

℃

Tolu.

Benz.

2-4 DMP

2-2 DMP

2-

3DMB

2-

2DMB

n-C6

3-MP

2-MP

n-C5

i-C5

3.22

3.15

7.12

5.45

8.98

8.20

13.80

10.20

11.80

13.10

5.39

0

230

3.20

3.12

6.94

5.31

8.98

8.10

13.77

10.10

11.77

13.00

5.20

15

3.16

3.11

6.86

5.30

8.88

8.00

13.67 9.96

11.67

12.97

5.00

30

3.14 3.11 6.79 5.22 8.76 7.95 13.60 9.87 11.50

12.95 500

4.80

4.49

6.97

4.88

8.87

8.10

13.00 10.00 11.60

11.65

5.16

0

250

4.77

4.44

6.85

4.76

8.68

8.00

12.88

9.88

11.53

11.44

5.12

15

4.69

4.30

6.84

4.72

8.54

7.89

12.60

9.85

11.36

11.37

4.98

30

4.61 4.18 6.82 4.68 8.43 7.85 12.43 9.83 11.24

11.15 4.96

7.54

4.64

7.92

4.68

8.78

8.00

12.36 9.89 11.30

10.32

5.10

0

270

7.44

4.60

6.77

4.56

8.63

7.87

12.20

9.84

11.24

10.29

5.00

15

7.23

4.53

6.68

4.51

8.57

7.66

12.10

9.76

11.18

10.19

4.87

30

7.12 4.43 6.67 4.47 8.34 7.54 12.00 9.74 10.92

10.25 4.65

8.66

4.71

6.44

4.50

8.22

7.84

11.00

9.65

11.00

10.15

5.00

0

290

8.58

4.62

6.35

4.47

8.12

7.70

10.85

9.59

10.93

9.89

4.80

15

8.42

4.50

6.31

4.40

7.98

7.65

10.78

9.48

10.89

9.76

4.77

30

8.35 4.46 6.22 4.31 7.92 7.58 10.60 9.41 10.77

9.69 4.59

8.87 5.87 6.12 4.47 7.86 7.76 10.88 9.30 10.87

9.78 4.78

310

8.76 5.78 6.10 4.35 7.77 7.64 10.82 9.23 10.78

9.73 4.60

8.72 5.69 6.09 4.25 7.73 7.59 10.72 9.18 10.63

9.65 4.35

8.53 5.65 6.00 4.13 7.66 7.40 10.65 9.00 10.57

9.45 4.22

Appendix A

115

Table(A10) The average volume percent of component in product

using Pt/BaY.

WHSV=1.5hr-1

T℃

C7+

2,4DMP 2,2DMP 2,3DMB 2,2DMB 3MP 2MP n-C6 n-C5 i-C5

14.04 6.50 4.20 10.40 10.55 9.14 11.12 14.40 14.08 5.29 230

13.65 6.84 4.23 10.80 10.60 8.88 10.69 13.42 13.84 7.05 250

13.82 7.14 5.46 11.20 11.36 8.43 9.61 12.06 12.46 8.82 270

17.42 7.00 5.37 11.13 10.65 8.07 9.24 11.33 10.95 8.69 290

20.41 6.72 5.15 10.80 10.51 8.02 8.49 10.80 9.97 8.63 310

WHSV=3hr-1 T℃

15.36 6.02 3.88 9.99 8.94 9.48 11.75 14.83 14.66 5.09 230

15.70 6.30 4.17 10.74 9.69 9.09 11.32 14.52 14.18 6.40 250

13.53 6.58 5.03 11.42 10.29 9.01 10.77 14.04 13.88 7.45 270

16.07 6.41 4.90 10.15 9.00 8.79 10.38 13.61 13.59 7.10 290

20.26 6.15 4.66 9.97 7.84 8.76 9.52 13.00 12.97 6.87 310

WHSV=4.5hr-1 T℃

16.39 5.73 3.61 9.39 8.37 10.01 11.86 15.50 14.72 4.42 230

15.62 5.87 3.97 10.50 8.71 9.74 11.55 14.85 14.53 4.66 250

14.23 6.61 4.90 10.40 9.00 9.61 10.98 14.65 13.82 5.53 270

15.86 6.55 4.77 10.28 8.77 9.25 10.46 14.19 13.71 5.11 290

20.86 6.38 4.49 9.84 7.92 9.02 9.93 13.43 13.18 4.95 310

Appendix A

116


using Pt/HY.

WHSV=1.5hr-1

T℃

C7+

2,4DMP 2,2DMP 2,3DMB 2,2DMB 3MP 2MP n-C6 n-C5 i-C5

13.76 6.91 4.64 11.31 10.90 8.85 11.21 13.90 13.62 5.49 230

15.16 7.39 4.75 12.00 11.10 8.59 10.46 13.33 11.64 7.58 250

14.37 7.93 6.14 12.10 11.70 8.38 10.19 10.90 9.40 8.89 270

15.05 7.88 5.94 12.07 11.67 8.03 9.07 10.82 9.39 8.68 290

17.75 7.50 5.63 12.00 11.51 7.92 8.92 10.78 9.39 8.60 310

WHSV=3hr-1 T℃

14.95 6.21 3.97 10.69 9.96 9.39 11.16 14.42 14.00 5.25 230

13.50 6.60 4.53 10.85 10.13 8.93 10.86 14.23 13.72 7.37 250

13.22 6.89 4.65 11.10 10.45 8.84 10.61 13.74 11.89 8.61

270

16.92 6.69 4.51 10.80 10.21 8.40 10.08 13.39 10.55 8.45 290

19.07 6.62 4.45 10.50 10.00 8.11 9.80 13.15 10.05 8.25 310

WHSV=4.5hr-1 T℃

15.07 5.75 3.63 9.54 8.41 9.84 11.22 15.29 14.60 4.90 230

14.70 6.10 4.07 10.75 8.88 9.53 10.91 14.77 14.37 5.84 250

13.19 6.80 5.11 10.85 9.30 9.41 10.79 14.59 13.65 6.75 270

16.18 6.66 4.90 10.55 9.00 9.15 10.25 13.48 13.19 6.64 290

18.16 6.64 4.64 10.27 8.81 8.82 9.82 13.38 13.10 6.36 310

Appendix A

117


using Pt/Al2O3.

WHSV=1.5hr-1

T℃

C7+ Tolu. Benz. 2,4DMP 2,2DMP 2,3DMB 2,2DMB 3MP 2MP n-C6 n-C5 i-C5

8.06 3.19 4.66 7.43 5.78 10.79 9.78 9.73 10.24 12.62 11.67 6.05 230

9.85 6.34 6.90 7.38 5.21 10.64 8.98 8.68 9.55 11.66 10.63 5.18 250

9.28 9.23 8.77 7.28 5.02 10.05 8.74 8.66 9.48 10.57 8.75 5.17 270

9.94 12.35 10.44 6.69 4.91 9.57 8.18 8.50 9.44 8.38 6.67 4.93 290

9.16 14.74 12.70 6.20 4.76 9.34 8.06 8.36 9.17 7.05 5.78 4.68 310

WHSV=3hr-1 T℃

7.24 3.31 3.94 7.33 5.56 10.56 9.37 9.84 11.10 13.17 12.80 5.78 230

9.66 6.09 6.60 7.32 4.92 10.54 8.88 9.56 10.79 11.01 10.11 5.52 250

7.35 9.22 8.63 7.20 4.91 9.94 8.76 9.33 10.48 10.73 8.40 5.05 270

7.61 11.64 9.50 6.57 4.83 9.43 8.19 9.18 10.20 9.58 8.27 5.00 290

7.00 13.11 11.23 6.40 4.66 9.15 7.91 8.98 10.06 8.87 7.84 4.79 310

WHSV=4.5hr-1 T℃

10.15 3.18 3.91 6.92 5.32 8.90 8.06 10.03 11.68 13.71 13.00 5.14 230

10.26 5.71 5.35 6.86 4.76 8.63 7.96 9.89 11.43 12.72 11.40 5.03 250

7.19 8.33 8.55 6.76 4.55 8.58 7.76 9.81 11.16 12.16 10.26 4.89 270

8.55 10.50 8.57 6.33 4.42 8.06 7.69 9.53 10.89 10.80 9.87 4.79 290

8.82 10.71 10.00 6.07 4.29 7.75 7.59 9.17 10.71 10.76 9.65 4.48 310

Appendix B

118

Appendix B The concentration (C×10P

-3P) of light naphtha.

Table (B1): The concentration of components in products using catalyst Pt/ BaY.

WHSV=1.5hrP

-1

T℃ 2,4DMP 2,2DMP 2,3DMB 2,2DMB 3MP 2MP n-CR6 n-CR5 i-CR5

1.57 0.97 2.52 2.46 2.21 2.69 3.49 3.41 1.28 230

1.59 0.98 2.56 2.47 2.07 2.49 3.12 3.22 1.64 250

1.60 1.22 2.73 2.55 1.89 2.15 2.70 2.79 1.98 270

1.51 1.16 2.60 2.36 1.74 2.00 2.45 2.37 1.92 290

1.40 1.07 2.36 2.19 1.67 1.77 2.25 2.08 1.80 310

WHSV=3hrP

-1 T℃

1.45 0.94 2.42 2.16 2.29 2.84 3.59 3.55 1.23 230

1.46 0.97 2.50 2.25 2.11 2.63 3.38 3.30 1.49 250

1.47 1.12 2.56 2.31 2.02 2.41 3.15 3.11 1.67 270

1.38 1.06 2.19 1.94 1.90 2.24 2.94 2.94 1.53 290

1.28 0.97 2.08 1.63 1.83 1.99 2.71 2.71 1.43 310

WHSV=4.5hrP

-1 T℃

1.38 0.87 2.27 2.02 2.42 2.87 3.75 3.56 1.07 230

1.39 0.92 2.44 2.03 2.27 2.69 3.46 3.38 1.08 250

1.48 1.10 2.61 2.10 2.15 2.46 3.29 3.10 1.24 270

1.41 1.03 2.22 1.89 2.00 2.26 3.07 2.96 1.10 290

1.33 0.93 2.05 1.65 1.88 2.07 2.80 2.75 1.03 310

Appendix B

119

Table (B2): The concentration of components in products using catalyst Pt/ HY.

WHSV=1.5hrP

-1

T℃ 2,4DMP 2,2DMP 2,3DMB 2,2DMB 3MP 2MP n-CR6 n-CR5 i-CR5

1.67 1.12 2.74 2.64 2.14 2.72 3.37 3.30 1.33 230

1.72 1.10 2.79 2.68 2.00 2.43 3.10 2.71 1.76 250

1.78 1.37 3.57 2.93 1.88 2.29 2.44 2.11 2.39 270

1.70 1.28 3.13 2.74 1.73 1.96 2.34 2.03 2.09 290

1.56 1.17 2.80 2.57 1.63 1.76 2.10 1.96 1.97 310

WHSV=3hrP

-1 T℃

1.50 0.96 2.42 2.41 2.27 2.70 3.49 3.39 1.27 230

1.53 1.05 2.52 2.36 2.08 2.53 3.31 3.19 1.71 250

1.54 1.21 2.71 2.34 1.98 2.38 3.08 2.67 1.93 270

1.44 1.12 2.55 2.21 1.81 2.18 2.90 2.28 1.83 290

1.38 1.07 2.40 2.07 1.69 1.96 2.63 2.10 1.72 310

WHSV=4.5hrP

-1 T℃

1.39 0.88 2.31 2.03 2.38 2.72 3.70 3.53 1.18 230

1.42 0.94 2.50 2.07 2.22 2.54 3.44 3.35 1.36 250

1.52 1.14 2.63 2.08 2.11 2.42 3.27 3.06 1.51 270

1.44 1.06 2.28 1.94 1.98 2.22 3.07 2.92 1.43 290

1.38 0.97 2.14 1.84 1.84 2.05 2.79 2.74 1.33 310

Appendix B

120

Table (B3): The concentration of components in products using catalyst Pt/ AlR2ROR3R.

WHSV=1.5hrP

-1

T℃ Tolu. Benz. 2,4DMP 2,2DMP 2,3DMB 2,2DMB 3MP 2MP n-CR6 n-CR5 i-CR5

0.77 0.88 1.80 1.40 2.61 1.37 2.35 2.48 3.05 2.82 1.46 230

1.01 0.90 1.72 1.21 2.48 2.09 2.02 2.22 2.48 1.77 1.20 250

1.39 1.07 1.63 1.12 2.25 1.96 1.72 1.95 2.15 1.51 1.16 270

2.09 1.67 1.50 1.10 2.14 1.83 1.62 1.89 1.88 1.49 1.10 290

2.03 1.61 1.29 0.99 1.95 1.68 1.54 1.70 1.47 1.20 0.97 310

WHSV=3hrP

-1 T℃

0.80 0.95 1.77 1.34 2.56 2.27 2.38 2.69 3.19 3.10 1.40 230

1.18 1.07 1.70 1.14 2.45 2.07 2.22 2.51 2.56 2.35 1.28 250

1.39 1.03 1.61 1.10 2.23 1.96 2.09 2.35 2.40 1.88 1.13 270

1.87 1.19 1.42 1.04 2.04 1.77 1.98 2.20 2.07 1.79 1.08 290

1.90 1.30 1.33 0.97 1.91 1.65 1.87 2.10 1.85 1.63 1.00 310

WHSV=4.5hrP

-1 T℃

0.77 0.94 1.67 1.28 2.15 1.95 2.43 2.83 3.32 3.15 1.24 230

1.09 1.01 1.59 1.10 2.01 1.85 2.30 2.66 2.96 2.65 1.17 250

1.19 1.02 1.51 1.02 1.92 1.74 2.20 2.50 2.73 2.30 1.09 270

1.62 0.98 1.37 0.95 1.74 1.66 2.06 2.35 2.33 2.13 1.03 290

1.82 1.20 1.26 0.89 1.62 1.58 1.91 2.24 2.25 2.01 0.93 310

Appendix C

121

Appendix C The conversion percent of light naphtha.

Table(C1) The Conversion percent of light naphtha using Pt/BaY

Conversion %

Tem

pera

ture

℃

WHSV=4.5 hr P

-1 WHSV=3 hr P

-1 WHSV=1.5 hr P

-1

Total 3MP 2MP n-CR6

n-CR5 Total 3MP 2MP n-

CR6 n-CR5 Total 3MP 2MP n-

CR6 n-CR5

18.9 19.8 20.0 17.2 19.0 21.0 24.1 20.8 20.7 19.3 24.0 26.8 25.0 22.9 22.5 230

24.0 24.8 25.0 23.6 23.1 26.5 30.1 26.7 25.3 25.0 29.8 31.4 30.6 31.1 26.8 250

29.2 29.8 31.4 27.3 29.5 31.2 33.1 32.8 30.4 29.3 40.0 37.6 40.1 40.3 41.5 270

33.7 33.7 37.0 32.2 32.7 35.5 37.0 37.6 35.0 33.1 44.9 42.3 44.2 45.9 46.1 290

38.8 37.3 42.3 38.1 37.5 40.5 39.3 44.5 40.1 38.4 50.0 44.7 50.6 50.3 52.7 310

Appendix C

122

Table(C2) The conversion percent of light naphtha using Pt/HY.

Conversion % Te

mpe

ratu

re

℃

WHSV=4.5 hr P

-1 WHSV=3 hr P

-1 WHSV=1.5 hr P

-1

Total 3MP 2MP n-CR6 n-CR5 Total 3MP 2MP n-CR6 n-CR5 Total 3MP 2MP n-CR6 n-CR5

20.6 21.1 24.2 18.3 19.7 23.7 24.8 24.7 22.9 22.9 26.5 29.1 24.2 24.9 25.0 230

25.6 26.4 29.2 24.0 23.8 28.5 31.1 29.5 26.9 27.5 34.1 33.7 32.3 31.5 38.4 250

30.1 30.1 32.5 27.8 30.4 34.9 34.4 33.7 32.0 39.3 44.9 37.7 36.0 46.1 52.0 270

34.4 34.4 38.1 32.2 33.6 40.9 40.0 39.2 35.9 48.1 48.1 42.7 39.5 48.3 53.8 290

39.3 39.0 42.8 38.4 37.7 46.0 44.0 45.4 41.9 52.2 52.0 46.0 43.3 53.6 55.4 310

Table(C3) The conversion percent of light naphtha using Pt/AlR2ROR3R.

Conversion %

Tem

pera

ture

℃

WHSV=4.5 hr P

-1 WHSV=3 hr P

-1 WHSV=1.5 hr P

-1

Total 3MP 2MP n-CR6 n-CR5 Total 3MP 2MP n-CR6 n-CR5 Total 3MP 2MP n-CR6 n-CR5

25.5 19.5 21.1 26.7 28.4 27.4 21.1 25.0 27.5 29.5 31.2 22.1 30.9 33.6 35.9 230

33.8 23.8 25.9 34.6 39.7 40.3 26.4 30.0 43.4 46.5 47.5 33.1 38.1 45.2 59.7 250

39.4 27.1 30.3 39.7 47.7 46.6 30.7 34.5 47.0 57.2 54.9 43.0 45.6 52.5 65.6 270

45.4 31.7 34.5 48.5 51.5 51.1 34.4 38.7 54.3 59.3 58.2 46.3 47.3 58.4 66.1 290

48.3 36.7 37.6 50.3 54.3 55.2 38.0 41.5 59.1 62.9 64.7 49.0 52.6 67.5 72.7 310

Appendix D

123

Appendix D

Table (D1):The reaction rate constant for n-pentane, n-hexane,

and 3MP at WHSV of 1.5hr P

-1P over Pt/BaY and Pt/HY catalysts.

n-pentane

Temperature℃

Pt/HY Pt/BaY

kR2 kR1 kR2 kR1

0.198 0.179 0.200 0.159 230

0.310 0.287 0.400 0.187 250

0.511 0.413 0.350 0.329 270

0.360 0.419 0.318 0.338 290

0.300 0.422 0.250 0.392 310

n-Hexane

1.0 0.182 0.258 0.156 230

0.775 0.231 0.400 0.228 250

1.8 0.364 0.388 0.304 270

0.658 0.375 0.215 0.349 290

0.330 0.422 0.09 0.384 310

3MP

2.3 0.219 0.370 0.198 230

2.0 0.251 0.680 0.230 250

2.87 0.282 0.735 0.278 270

3.5 0.316 0.400 0.313 290

0.761 0.350 0.122 0.325 310

Appendix D

124

Table (D2):The pre-exponential (kRoR) factor for n-pentane, n-hexane, and 3MP at WHSV of 1.5hrP

-1P over Pt/BaY and Pt/HY

catalysts.

3MP n-hexane n-pentane Catalysts

0.227 0.179 0.259 Pt/BaY

0.386 0.275 0.272 Pt/HY

Appendix E

125

Appendix E

Table (E1): The percentage selectivity and conversion products.

Pt/Ba-Y

Tem

pera

ture

℃

WHSV=4.5hrP

-1 WHSV=3hrP

-1 WHSV=1.5hrP

-1

Conversion Isomers Aromatic Conversion Isomers

Aromatic Conversion Isomers Aromatic

18.9 19 0.69 21.0 33 0 24.0 51 0 230

24.0 31 0 26.5 49 0 29.8 74 0 250

29.2 42 0 31.2 75 0 40.0 89 0 270

33.7 32 0.16 35.5 45 0.37 44.9 67 1.72 290

38.8 17 5.16 40.5 44 4.56 50.0 46 4.71 310

Pt/H-Y ℃ T

20.6 25 0 23.7 46 0 26.5 63 0 230

25.6 44 0 28.5 69 0 34.1 81 0 250

30.1 60 0 34.9 84 0 44.9 95 0 270

34.4 44 0.48 40.9 61 1.22 48.1 89 0 290

39.3 35 2.46 46.0 50 3.37 52.0 73 2.05 310

Pt/ALR2ROR3 ℃ T

25.5 0.17 0.74 27.4 43 0.9 31.2 48 1.5 230

33.8 0 3.71 40.3 17 5.34 47.5 26 6.89 250

39.4 0 10.53 46.6 .18 11.5 54.9 12 11.65 270

45.4 0 12.72 51.1 0 14.79 58.2 0.11 16.44 290

48.3 0 14.36 55.2 0 18 64.7 0.08 21.09 310

Appendix F Sample of Calculation

126

Appendix F

Sample of Calculation

1. Calculation of amount of H2PtCl6

in each catalyst samples :

0.5% Wt of Pt must be added to each sample catalysts

0.5 100

w=20 (0.5/100) = 0.1 g of Pt

w 20

but H2PtCl6

contain 40% of Pt

WH2PtCl6 = 0.1/0.4 = 0.25 g of H2PtCl

6

2-

Calculation of amount of Ba (in BaY catalyst

wt (gm)= N × eq. wt × V/1000

wt (gm)= 3 × 122.14 × 100/1000

wt (gm)= 36.642 gm


127

3-Calculation of amount of H as (NH4

wt (gm)= 3 × 53.49 × 100/1000

Cl) in HY catalyst

wt (gm)= 16.047 gm

4-

Calculation of the conversion of the light naphtha (X).

X =

CAo = × yA

C

o

A = × y

Where P Pressure, (atmospheric pressure)

A

R Gas Constant, 0.0821 atm-liter/g-mole-K

yAo

y

Initial Mole Fraction of n- Paraffin

A

T

Mole Fraction of n- Paraffin at any Time o

T Second Temperature at any Time

Initial Temperature

5-Calculation of the reaction rate constants (k1, k2

).

A- The calculation of the reaction rate constant (k1) can be achieved according to equation (4.22)


128

k1= [(1+ є)Ln – Єx] ------------------------------(4.22)

where X Percentage Conversion

FAo:

V: Volume of Reactor cm

Mass Flow Rate gm/hr

3

B- The calculation of the reaction rate constant (k2

) can be achieved according to equation (4.11) by trial and error.

Ciso = CA° [1- exp (- k1t) - [exp(-k1t) – exp(-k2

t)]

6-

According to equation (4.23) the calculation of the apparent

activation energy may be achieved by plotting Lnk

Calculation of the apparent activation energy (E).

1

Lnk

vs. 1/T as shown

in Figures (5.36) to (5.44).

1=Ln k◦ - -----------------------------(4.23)

Where the slope is represent –E/R, the intercept is represent pre-exponential factor (ko

where R Gas Constant 8.314 joules/g-mole-K

).

الخالصة

النتاج األيزومرات ) في مصفى الدورة المنتجة(البحث ازمرة مادة النفثا الخفيفة العراقية عملية تضمن ت

Pt/AlR2ROR3 هي خالل العملية تم تحضير ثالثة عوامل مساعدة. قابلة والتي لها عدد اوكتاني عاليمال

%0.5 .وزنا من البالتين والمحضر بطريقة الترطيب Pt/BaY, Pt/HY , وية على نسبة والحا

مصنوع من مادة تم اجـــــراء التجارب في منظومة مختبريــــــة تحتوي على مفاعل ذو حشــــــــــوة ثابتة

سم 3سم والقطر الخارجي 2القطر الداخلي للمفاعل . األستيل المقاوم للصدأ والمصمم لعملية األزمرة

، 250، 230وبدرجـــات حرارة حت الضغط الجوي األعتياديتالتجارب جميع تمت. سم 21واألرتفاع

Pساعة 4.5و 3، 1.5 وزنية م وباستخدام سرع فراغية˚310و 290، 270

-1P ثابتة مولية ةوبنســـب

.4 النفثا الخفيفةللهيدروجين الى

، البنتان األعتيادي(تي تعاني عملية التحول هي أظهرت النتائج بان المركبات الرئيسية في النفثا الخفيفة ال

والتي تزداد بزيادة درجة حرارة التفاعل وتقليل السرع) مثيل بنتان 3و ، مثيل بنتان 2، الهكسان األعتيادي

تزداد عمليات التحولاأليزومرات الناتجة من وتشير نتائج التحليل بان . والمحمل عليهما البالتين الفراغية

. كعوامل مساعدة Pt/BaY, Pt/HYعند درجات الحرارة المنخفضة و بوجود

بينما نالحظ المركبات األروماتية في النواتج تزداد بزيادة درجة حرارة التفاعل وبوجود األلومينا كعامل .مساعد

اكبر من % 95اعطى انتقائية باتجاه األزمرة وهي Pt/HY من خالل النتائج بان العامل المساعد نالحظ

تحت نفس الظروف من% 89والتي كانت Pt/BaY األنتقائية التي حصلنا عليها باستخدام العامل المساعد

ساعة1.5وسرعة فراغية م ˚270درجة حرارة من جانب اخر تم الحصول على اعلى نسبة تحول. P

-1

كانت .%18 حيث تشكل نسبة المواد األروماتية منها حوالي %64.7مساعد وهي باستخدام األلومينا كعامل

% .50تقريبا Pt/BaY, Pt/HYنسبة التحول الكلي للعوامل المساعدة

:كما يلي األنتقائيةالكفاءة بأتجاه ترتيب العوامل المساعدة حسب يكون

Pt/HY > Pt/BaY > Pt/AlR2ROR3R

من خالل الميكانيكية المقترحة باألعتماد على الميكانيكية الكالسيكية في عمليات تم دراسة حركية التفاعالت األزمرة ومن خاللها تم حساب المتغيرات kR1R, kR2R, kRoR, E . باألعتماد على النتائج العملية )

)

، األعتيادي بنتانمول بالنسبة لل/كيلوجول 23و 22تتراوح بين بانها تم دراسة قيم طاقات التنشيط و وجدت

3الى ال مول بالنسبة/كيلوجول 17و 15و بين ، مول بالنسبة للهكسان األعتيادي /كيلوجول 24و 20و بين

أللكانات األعتيادية المستخدمة في هذه الدراسة تسير كما ل درجة التفاعليةالى ان كما تشير النتائج، مثيل بنتان

:يلي

3-methylpentane > n-hexane > n-pentane

باألعتماد على الميكانيكية المقترحة ومن خالل النتائج العملية التي تم الحصول عليها في تم اشتقاق معادلتين :من خاللهما وكما يلي ) kR1R, kR2R (ثوابت معدل التفاعل حيث تم حساب ، عملية األزمرة

kR1R= [(1+ Є) Ln – Єx]

CRisoR = CRA°R [1- exp (- kR1Rt) - [exp(-kR1Rt) – exp(-kR2Rt)]

isolation n-butane

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