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DEVELOPMENT OF MODIFIED MCM-41

CATALYST SYSTEM TOWARDS EPOXIDATION OF

1-OCTENE AND METHYL OLEATE

SUHAILA BTE MOHAMED

FACULTY OF SCIENCE

UNIVERSITY OF MALAYA

KUALA LUMPUR

2012

DEVELOPMENT OF MODIFIED MCM-41

CATALYST SYSTEM TOWARDS EPOXIDATION OF

1-OCTENE AND METHYL OLEATE

SUHAILA BTE MOHAMED

DISSERTATION SUBMITTED IN FULFILMENT OF

THE REQUIREMENT FOR THE DEGREE

OF MASTER OF SCIENCE

DEPARTMENT OF CHEMISTRY

FACULTY OF SCIENCE

UNIVERSITY OF MALAYA

KUALA LUMPUR

2012

Declaration

I hereby declare that the work reported in this thesis is my own, unless specified and

acknowledged by quotation.

Suhaila Bte Mohamed

Matric No.: SGR030034

October, 2009

ABSTRACT

The discovery of mesoporous molecular sieves has created a tremendous interest in

the synthesis of these materials, particularly MCM-41 and its analogue, because of

their very high surface areas and possibility of precisely tuned pore sizes (20-100 Å).

These mesoporous materials have a wide range of potential applications starting

from selective adsorption to heterogeneous catalysis, particularly for bulky

molecules. Ti-MCM-41 has been widely developed as a catalyst for olefin

epoxidation because of the active sites of Ti can acts as a very reactive compound for

this reaction besides MCM-41 plays an important role as a support which is in the

mesopore range. The research done provides an optimal reaction condition for

epoxidation of Methyl Oleate using Ti-MCM-41 samples, based on the study of

epoxidation of model compound, 1-Octene. The optimized reaction conditions lead

to a maximum of epoxide selectivity and yield and also alkene conversion.

In this study, a series of mesoporous titanosilicate Ti-MCM-41 molecular sieves with

various Si/Ti ratios, 25, 55, 66, 80 and 100 have been hydrothermally synthesized at

100OC for 48 hours, using surfactant namely hexadecyl-trimethylammonium

bromide as template and tetramethylammonium hydroxide as mineralizer. Chemical

and physical properties of products obtained were characterized using powder X-ray

diffraction (XRD), FTIR spectroscopy, DRUV-visible spectroscopy, nitrogen

sorption measurements, differential thermal analysis (TGA-DTG), and scanning

electron microscopy (SEM). XRD analysis shows that Ti-MCM-41 is a

semicrystalline material with ordered mesoporous hexagonal structure which is

indicated by a reflection peak at 2θ in the range of 1.6˚ to 2.6˚. The crystallinity of

Ti-MCM-41 after calcinations was almost two-fold higher than that of the as-

synthesized one. Calcination in nitrogen leads to desorption of organic templates

from the pores of Ti-MCM-41 in contrast to template burning in air. The

crystallinity and surface area of Ti-MCM-41 both decrease with an increase of

titanium content. Nitrogen sorption measurements exhibit BET surface area of Ti-

MCM-41 are in the range of 880 m2g

-1 to 1075.163 m

2g

-1. Quite high BET surface

areas with isotherms of type IV of the samples are typical for hexagonal MCM-41

type ordered mesoporous materials. The results of XRD and FTIR show that the

solid products have the MCM-41 structure and contained only atomically dispersed

titanium, consistent with framework titanium in Ti-MCM-41. All of the materials

had a uniform pore size distribution which is around 3.0 nm. DRUV-visible analysis

shows that Ti-MCM-41 has two types of titanium species; one species is titanium

isolated tetrahedral which is active to catalyze epoxidation of alkenes and the other is

titanium isolated octahedral. Catalytic activities of Ti-MCM-41 were tested in the

epoxidation of 1-Octene and methyl oleate using tert-butyl hydroperoxide as

peroxide in a batch reactor. Catalyst with high titanium content (Si/Ti = 25) is prone

to deactivate due to high side compounds although at one hand, the hydrophobicity is

improved. The titanium sites in MCM-41 catalysts are buried on the silica walls,

being non-accessible to the reactants, thus lower the catalytic activity and turnover.

The best is to use catalysts with average amount of titanium (Si/Ti = 80). When

comparing between silylated and non-silylated samples, it was found that silylated

samples exhibit higher catalyst activity, and the conversion and TON increased three

times as compared to non-silylated samples. Silylation increases greatly the

hydrophobicity of Ti-MCM-41 catalysts and therefore, water concentration on the

surface of catalyst is reduced, and subsequent glycol formation which is one of the

side products is nearly avoided. Silylation also decreases the number of silanol

groups (and very probable Ti-OH groups) in the catalyst whereby these groups

posses a weak acid character, but strong enough to catalyze the undesired reaction of

oxirane ring opening.

ABSTRAK

Dengan penemuan pengayak molekular mesoporos menyedarkan perhatian yang

khusus diberikan kepada sintesis bahan ini terutamanya MCM-41 dan analognya

kerana sifat luas permukaannya yang tinggi dan kebolehan melaras saiz liang dengan

tepat (20-100 Å). Bahan mesoporos ini merangkumi bidang aplikasi yang luas dan

berpotensi besar bermula daripada sebagai penjerapan selektif sehingga kepada

mangkin heterogenous, khususnya bagi molekul bersaiz besar. Mangkin Ti-MCM-

41 telah banyak dikembangkan untuk tindak balas pengepoksidaan olefin disebabkan

sifat titanium yang reaktif bagi tindak balas ini manakala MCM-41 bertindak sebagai

penyokong yang bersifat mesoporos. Kajian ini menyediakan suatu keadaan tindak

balas yang optimum bagi tindak balas pengepoksidaan metil oleat menggunakan

sampel Ti-MCM-41 berdasarkan kepada kajian pengepoksidaan bahan model, 1-

oktena. Keadaan tindak balas optimum yang diperolehi terarah kepada peningkatan

secara maksimum di dalam keselektifan untuk hasil epoksida dan penukaran alkena.

Di dalam ujikaji ini, satu siri titanosilikat mesoporos, pengayak molekular Ti-MCM-

41 dengan pelbagai nisbah mol Si/Ti 25, 55, 66, 80 dan 100 disintesis secara

hidroterma pada suhu 100OC selama 48 jam, menggunakan surfaktan seperti

heksadesiltrimetilammonium bromida sebagai templat dan tetrametilammonium

hidroksida sebagai bahan mineral. Sifat kimia dan fizikal mangkin terbentuk

dicirikan menggunakan teknik seperti pembelauan sinar-X (XRD), spektroskopi

FTIR, spektroskopi DRUV-vis, ukuran penjerapan/ penyerapan nitrogen, analisis

terma pembezaan (TGA-DTG) dan mikroskopi imbasan elektron (SEM). Analisis

XRD menunjukkan Ti-MCM-41 yang dihasilkan bersifat semi-kristal dengan aturan

struktur heksagonal mesoporos seperti yang ditunjukkan oleh puncak pembelauan

pada sudut 2 antara 1.6˚ hingga 2.6˚. Mangkin Ti-MCM-41 selepas pengkalsinan

menunjukkan penghabluran dua kali ganda lebih tinggi berbanding mangkin tanpa

pengkalsinan. Ini disebabkan pengkalsinan di dalam nitrogen dapat mengeluarkan

templat organik yang terdapat di dalam liang Ti-MCM-41 sementara pembakaran

templat berlaku di dalam udara semasa proses pengkalsinan. Pembentukan hablur

dan luas permukaan berkurang dengan penambahan kandungan titanium. Daripada

ukuran penjerapan/ penyerapan nitrogen, luas permukaan Ti-MCM-41 adalah dalam

julat 880 m2g

-1 to 1075 m

2g

-1. Sampel menunjukkan luas permukaan BET yang agak

tinggi dengan isoterma jenis IV, merupakan parameter biasa bagi unsur aturan

mesoporos jenis MCM-41 heksagonal. Keputusan XRD dan FTIR menunjukkan

pepejal yang terhasil mengandungi struktur MCM-41 dan juga titanium terlarut

secara atomik, selari dengan kerangka titanium di dalam Ti-MCM-41. Kesemua

sampel mempunyai penyerakan saiz liang yang seragam iaitu dalam lingkungan 3.0

nm. Analisis DRUV-visible menunjukkan Ti-MCM-41 mempunyai dua spesis

titanium; iaitu titanium terisolasi secara tetrahedral yang aktif di dalam tindak balas

pengepoksidaan alkena dan titanium terisolasi secara oktahedral. Aktiviti

pemangkinan Ti-MCM-41 ditentukan di dalam tindak balas pengepoksidaan 1-

oktena dan metil oleat di dalam reaktor sekumpul dengan menggunakan tert-butil

hidroperoksida sebagai agen peroksida. Mangkin dengan kandungan titanium yang

tinggi (Si/Ti = 25) cenderung untuk mengalami penyahaktifan, akibat pertambahan

produk sampingan walaupun pada masa yang sama, sifat kehidrofobikan diperbaiki.

Kawasan titanium di dalam mangkin MCM-41 tertanam pada dinding silika,

menyebabkan ia tidak dapat bertindak balas dengan reaktan, seterusnya

merendahkan aktiviti pemangkinan. Komposisi titanium terbaik ialah menggunakan

kuantiti titanium yang sederhana (Si/Ti = 80). Apabila membandingkan sampel yang

tersililat dan tidak tersililat, didapati sampel yang tersililat menunjukkan peningkatan

sebanyak tiga kali ganda aktiviti pemangkinan berbanding sampel yang tidak

tersililat. Pensililan sangat membantu meningkatkan sifat kehidrofobikan mangkin

Ti-MCM-41 kesan daripada pengurangan kepekatan air pada permukaan mangkin

dan seterusnya menghindar penghasilan glikol yang merupakan salah satu produk

sampingan. Proses pensililan dapat mengurangkan jumlah kumpulan silanol di

dalam mangkin (besar kemungkinan kumpulan Ti-OH) yang mana kumpulan ini

memiliki ciri-ciri asid lemah, tetapi cukup kuat untuk menjadi pemangkin bagi

tindak balas pembukaan gelang oksiran yang tidak diperlukan pada peringkat ini.

ACKNOWLEDGEMENT

I owe a great deal to the Almighty Allah for being my shepherd and my source of

strength throughout this research study. This work was developed between May

2003 till February 2005 at Combinatorial Technology and Catalysis Centre

(COMBICAT), University of Malaya plus Instituto Tecnologica Qiumica (ITQ),

UPV-CSIC, Spain.

While I take full responsibility of this thesis, I have received invaluable help from a

number of people.

My particular thanks are due to my supervisor, whom also the Head of COMBICAT

Programme, Associate Prof. Dr. Sharifah Bee Abdul Hamid, for her intelligent,

insightful, generous and support throughout this research effort, which enabled me

to finish this thesis and make my stay in Valencia, Spain one of the most rewarding

in my life.

Special thanks to Prof. Dr. Avelino Corma Canos, the Head of ITQ for having given

me the opportunity to carry out my master work in his well recognized institute, ITQ

for nine months. I’m much indebted to him; his guidance was invaluable in the

development and completion of this work.

I am also deeply in debt with Dr. Surina Ismail, R & D Manager of COMBICAT UM

for her valuable comments and suggestions on my thesis work and commitment to

solve technical, analytical and other work-related problems.

Then to Marcelo Domine; your supports, comments during a number of sessions of

consultation gave me a very useful suggestion that led to the successful solution of

problems pertaining to this study.

Not forgetting Maite Navarro, for her supervision and comments on the synthesis

work.

I’m also grateful to Manolo, Pedro and Christina for their generous help and

participation related to high-throughput system. I also thank Jose Gaona for

providing me the apparatus needed for my reaction during my nine months in ITQ.

I appreciate financial aid for this research from the IRPA RM8 Strategic Research

supported by Ministry of Science, Technology and Innovation ( MOSTI ).

My thanks to all individuals who by one way or another, have contributed to the

realization of this thesis; to all the other personal of COMBICAT and ITQ for their

technical advise and service, analyzing samples for nitrogen adsorption, XRD, IR,

UV-Vis, TGA, GC and GC-MS, for their fruitful professional discussions and for

making my work as pleasant as it was.

Then it is my parents; Thanks for your availability. Mum and dad, you owe my

thanks for having unconditional trust and faith in me. Thanks also for your

encouragement and prayers. May Allah bless you.

To my husband; Sham, thanks for your trust, patience and concern; your sense of

humour made my study enjoyable.

xi

TABLE OF CONTENTS

Page

ABSTRACT iii

ABSTRAK

vi

ACKNOWLEDGEMENT ix

TABLE OF CONTENTS xi

LIST OF FIGURES xv

LIST OF TABLES xxiv

CHAPTER 1 GENERAL INTRODUCTION AND SCOPE OF THESIS

1

1.1 Catalytic Epoxidation 1

1.2 Industrially Used Catalysts 5

1.3 Commercial Review 10

1.4 Objective of Thesis

1.5 Scope of Thesis

19

20

CHAPTER 2 LITERATURE REVIEW

2.1 Review on Ti-MCM-41 Catalyst 23

2.2 Model Compounds 33

2.2.1 1-Hexene 34

2.2.2 1-Octene 35

xii

2.3 Epoxidation of Vegetable Oils 38

2.3.1 Methyl Oleate (Palm Oil) 39

CHAPTER 3 METHODOLOGY

3.1 Synthesis of Ti-MCM-41 43

3.1.1 Synthesis of Non-Silylated Ti-MCM-41 44

3.1.2 Synthesis of Silylated Ti-MCM-41 50

3.2 Reaction 53

3.2.1 Reaction Set-up 54

3.2.2 Materials 55

3.2.3 Procedure 56

3.3 Characterization Techniques 59

3.3.1 Nitrogen Physisorption(BET) 61

3.3.2 X-Ray Powder Diffraction(XRD) Analysis 67

3.3.3 Scanning Electron Microscope(SEM) and Energy

Dispersive X-ray Analysis (EDX) Analysis

71

3.3.4 Thermal-Gravimetric(TGA) Analysis and

Differential Scanning Calorimetric(DSC) Analysis

76

3.3.5 Ultraviolet Visible (UV-Vis) Absorption

Spectroscopy

81

3.3.6 Fourier Transform Infrared(FTIR) 85

xiii

CHAPTER 4 RESULTS AND DISCUSSION

4.1 Process Based on Utilizing Non-Silylated Ti-MCM-41 88

4.1.1 Characterization of Non-Silylated Sample 89

(a) BET 89

(b) XRD 97

(c) SEM/EDX 106

(d) TGA/DSC 122

(e) UV-Visible 136

(f) FTIR 141

4.1.2 Reactions of Model Compound: 1-Octene 146

(a) Effect of Si/Ti Ratio 153

(b) Effect of Temperature 163

(c) Effect of Molar Ratio 168

4.1.3 Process Optimization for Reaction with Methyl

Oleate

171

4.2 Process Based on Utilizing Silylated Ti-MCM-41 174

4.2.1 Effect of Degree of Silylation 182

CHAPTER 5 CONCLUSION

185

APPENDIX 194

BIBLIOGRAPHY 206

xv

LIST OF FIGURES

Page

Figure 1.1: Schematic representation of the epoxidation of an

alkene.

1

Figure 1.2: Peroxo versus Oxometal Pathways in Catalytic

Epoxidation Reaction.

3

Figure 1.3: Alkene epoxidation catalyzed by a four coordinated

Ti(IV) site.

5

Figure 1.4: The Mn-TMTACN catalyzed epoxidation.

8

Figure 1.5: The tungsten catalyzed epoxidation. 9

Figure 1.6: Structure of DGEBA resin. 15

Figure 1.7: Curing mechanism of Epoxy resins. 16

Figure 2.1: Mesoporous structure of M41S (i) MCM-41 (ii)

MCM-48 (iii) MCM-50.

24

Figure 2.2: Compilation of characterization techniques. 24

Figure 2.3: Number of publications on ordered mesoporous

materials as found by Chemical Abstracts on

Compact Disks.(CA an CD) of the American

Chemical Society using different keywords

(MCM-41 or FSM-16 or SBA-15 or mesoporous

materials or ordered mesoporous oxides or ordered

mesoporous materials).

26

Figure 2.4: Liquid crystal templating mechanism proposed for

the formation of MCM-41: (A) liquid crystal phase

initiated and (B) silicate anion initated.

29

Figure 2.5: : Silicate rod assembly proposed for the formation of

MCM-41; (1) and (2) involve the random ordering of

rod-like micelles and interaction with silicate

species; (3) represents the spontaneous packing of

the rods and (4) is the remaining condensation

of silicate species upon final heating of the

organic/inorganic composites.

30

xvi

Figure 2.6: Bronsted acid sites. 31

Figure 2.7: Formation of Ti(IV) tetrahedron sites onto silica

walls

.

32

Figure 2.8: Chemical structure of 1-hexene. 34

Figure 2.9: Proposed model of TS-1 loaded with sulfated

zirconia for transformation of 1-octene to 1,2-

epoxyoctane and 1,2-octanediol.

38

Figure 2.10: Proposed mechanism for epoxidation of methyl

oleate to epoxide as main product and ketone and

hydroxyl esters as by-products. Reaction condition:

C=C / TBHP = 4 : 1, catalyst = 0.5 g, wt. % of Ti =

1.68 %, time = 7 hrs.

41

Figure 3.1: Synthesis Procedure of Ti-MCM-41. 45

Figure 3.2: Teflon and Stainless Steel Autoclaves.

47

Figure 3.3: Autoclaves Oven.

47

Figure 3.4: Calcination Reactor.

48

Figure 3.5: Calcination programme for Ti-MCM-41 catalyst.

49

Figure 3.6: Basic Reflux Set-up. 54

Figure 3.7: Catalytic Experiments of Ti-MCM-41. 57

Figure 3.8: Nitrogen physisorption instrument. 63

Figure 3.9: The IUPAC classification of adsorption isotherms. 65

Figure 3.10: X-ray Diffraction.

68

Figure 3.11: Bragg reflection of X-rays from parallel planes of

atoms.

69

Figure 3.12: SEM/EDX to determine material morphology,

surface elemental composition, elemental mapping

72

xvii

and in-situ experimentation.

Figure 3.13: Thermal Gravimetric Analysis.

77

Figure 3.14: Differential Scanning Calorimeter for determination

of melting points, phase change temperatures and

chemical reaction temperature.

79

Figure 3.15: Possible electronic transitions of π, σ and n electrons. 82

Figure 3.16: Interaction of powder sample with light.

83

Figure 4.1: Nitrogen adsorption-desorption isotherms of MCM-

41.

90

Figure 4.2: Nitrogen adsorption-desorption isotherms for parent

MCM-41 sample and various Si/Ti ratio.

93

Figure 4.3: Pore size distribution for parent MCM-41 sample

and various Si/Ti ratio.

94

Figure 4.4: X-ray diffractogram of MCM-41 showing four

reflections, which can be assigned to the hexagonal

lattice of the mesoporous material.The (100),(110)

and (200) reflections are well resolved. (Radiation

used: Co K 1, with = 0.1788970 nm).

98

Figure 4.5: X-ray diffraction patterns of calcined Ti-MCM-41

samples; change of XRD pattern with Si/Ti ratios.

99

Figure 4.6: X-ray diffraction patterns of uncalcined Ti-MCM-41

samples; change of XRD pattern with Si/Ti ratios.

99

Figure 4.7: XRD patterns of 25Ti-MCM-41 (calcined &

uncalcined).

102


uncalcined).

103


uncalcined).

103


uncalcined).

104

xviii

Figure 4.11: XRD patterns of 100Ti-MCM-41 ( calcined &

uncalcined ).

104

Figure 4.12: Scanning electron micrographs of calcined Ti-MCM-

41 having different types of particle morphology : (a)

worm type and (b) hexagonal type.

106

Figure 4.13: Scanning electron micrographs of calcined Ti-MCM-

41 samples having different types of particle

morphology : (a) winding worm type, (b) hexagonal

type and (c) unique hexagonal rod type.

108

Figure 4.14: SEM images of sample 25Ti-MCM-41. 109


Figure 4.16: SEM images of sample 66Ti-MCM-41.

111



Figure 4.19: EDX analysis of sample 25Ti-MCM-41. 115

Figure 4.20: EDX analysis of sample 55TiMCM-41. 116

Figure 4.21: EDX analysis of sample 66Ti-MCM-41. 117

Figure 4.22.i: EDX analysis of sample 80Ti-MCM-41. 118

Figure 4.22.ii: EDX analysis of sample 80Ti-MCM-41. 119

Figure 4.23.i: EDX analysis of sample 100Ti-MCM-41. 120

Figure 4.23.ii: EDX analysis of sample 100Ti-MCM-41. 121

Figure 4.24: DTG-DTA-TGA temperature profile.

122

Figure 4.25: Thermogram of sample 100Ti-MCM-41 126

Figure 4.26: The TGA-DTA traces of as-synthesized 25Ti-MCM-

41.

127

xix

Figure 4.27: The TGA-DTA traces of as-synthesized 66Ti-MCM-

41.

127

Figure 4.28: The TGA-DTA traces of as-synthesized 100Ti-

MCM-41.

128

Figure 4.29: TGA-DTG curves of (a) as-synthesized (uncalcined)

25Ti-MCM-41 and (b) calcined 25Ti-MCM-41.

131



132



133



134

Figure 4.33: Diffuse reflectance UV-Vis spectra of calcined and

uncalcined Ti-MCM-41 samples.

139

Figure 4.34: Diffuse reflectance UV-Vis spectra of calcined Ti-

MCM-41 samples.

139

Figure 4.35: Diffuse reflectance UV-Vis spectra of uncalcined Ti-

MCM-41 samples.

140

Figure 4.36: Diffuse reflectance UV-Vis spectra of the highest

intensity of calcined and uncalcined (66Ti-MCM-

41), medium intensity (100Ti-MCM-41) of calcined

and uncalcined and the lowest intensity (25Ti-

MCM-41) of calcined and uncalcined Ti-MCM-41

samples.

140

xx

Figure 4.37: IR spectra in the framework and the hydroxyl

vibration region of calcined (a) MCM-41 (b) 100Ti-

MCM-41 (c) 80Ti-MCM-41 (d) 66Ti-MCM-41 and

(e) 25Ti-MCM-41.

142

Figure 4.38: Possible mechanism of 1-octene epoxidation with

tert-butyl hydroperoxide (TBHP) as oxidant by Ti-

MCM-41. The desired product is 1,2-epoxyoctane,

and the potential side products are 1,2-octanediol, 2-

octene-1-ol and 2-octanone.

148

Figure 4.39: Different cyclic Ti-species active for epoxidation

reactions.

150

Figure 4.40: Catalytic performance of Ti-MCM-41 samples in the

epoxidation reaction of 1-octene with TBHP at 60 oC

with different Ti wt. % loadings.

153

Figure 4.41: Selectivity to epoxide against 1-octene conversion at

60oC and a 1-octene: TBHP molar ratio of 4:1 on Ti-

MCM-41.

154

Figure 4.42: Effect of titanium contents towards selectivity to

epoxide.

156

Figure 4.43: Effect of titanium contents towards conversion of 1-

octene.

157

Figure 4.44: Effect of titanium contents towards selectivity to

epoxide with time.

158

Figure 4.45: Effect of titanium content on 1,2-epoxyoctane yield. 159

xxi

Figure 4.46: Influence of varying amount of titanium.

160

Figure 4.47: Effect of temperature on conversion and selectivity

during the epoxidation of 1-octene with Ti-MCM-41

sample. C=C / TBHP = 4 : 1, catalyst = 0.5 g, wt. %

of Ti = 1.68 % and 1.24 % , time = 7 hrs.

163

Figure 4.48: Effect of reaction temperature on the epoxidation of

1-octene. Reaction conditions: Catalyst 66Ti-MCM-

41 (1.68 wt% of Ti with respect to 1-octene); C=C /

TBHP = 4 : 1; reaction time = 7 hrs.

165

Figure 4.49: Effect of reaction temperature on the selectivity

towards epoxide. Reaction conditions: Catalyst 66Ti-

MCM-41 (1.68 wt% of Ti with respect to 1-octene);

C=C / TBHP = 4 : 1; reaction time = 7 hrs.

165

Figure 4.50: Effect of reaction temperature on the epoxidation of

1-octene. Reaction conditions: Catalyst 80Ti-MCM-

41 (1.24 wt% of Ti with respect to 1-octene); C=C /

TBHP = 4 : 1; reaction time = 7 hrs.

166

Figure 4.51: Effect of reaction temperature on the selectivity

towards epoxide. Reaction conditions: Catalyst 80Ti-

MCM-41 (1.24 wt% of Ti with respect to 1-octene);

C=C / TBHP = 4 : 1; reaction time = 7 hrs.

166

Figure 4.52: Effect of 1-octene to TBHP molar ratios on the

epoxidation of 1-octene. Reaction conditions:

168

xxii

Temperature = 60 OC; wt. % of Ti = 1.68 % and 1.24

%, time = 7 hrs.

Figure 4.53: Selectivity to epoxide vs 1-octene conversion at 60

oC for different 1-C8H16: TBHP molar ratio of 3:1,

4:1& 5:1 on 66Ti-MCM-41.

169

Figure 4.54: Selectivity to epoxide vs 1-octene conversion at 60

oC for different 1-C8H16: TBHP molar ratio of 3:1,

4:1& 5:1 on 80Ti-MCM-41.

170

Figure 4.55: Proposed mechanism of epoxidation of methyl oleate

to epoxide. Reaction condition: C=C / TBHP = 4 : 1,

catalyst = 0.5 g, wt. % of Ti = 1.68 %, time = 7 hrs.

172

Figure 4.56: Proposed surface reaction to enhance hydrophobicity

of MCM-41 by silylation of the surface silanols (Si-

OH).

176

Figure 4.57: Catalytic Performance of various silylated Ti-MCM-

41 towards epoxidation of methyl oleate at T=60 oC.

177

Figure 4.58: Selectivity to epoxide vs methyl oleate conversion

using silyated and non-silyated 66Ti-MCM-41 and

80Ti-MCM-41.

178

Figure 4.59: Commercial catalyst vs 80-Ti-MCM-41 silylated 178

xxiii

catalyst at T=60oC. X is methyl oleate conversion; S

is epoxide selectivity.

Figure 4.60: Commercial catalyst vs 80-Ti-MCM-41 silylated

catalyst at T=70oC.

180

Figure 4.61: Commercial catalyst vs 66Ti-MCM-41 and 80-Ti-

MCM-41 silylated catalyst at T=70oC towards

epoxidation of methyl oleate.

181

Figure 4.62: Commercial catalyst vs 66Ti-MCM-41 and 80-Ti-

MCM-41 non-silylated catalyst at T=70oC towards

epoxidation of methyl oleate.

181

Figure 4.63: Selectivity to epoxide vs methyl oleate conversion

using various degree of silyated 66Ti-MCM-41 and

80Ti-MCM-41 samples.

183

Figure B.1: GC calibration curve

195

Figure C.1: Chromatogram of epoxidation of 1-octene with

TBHP using Ti-MCM-41 sample.

197

Figure D.1: Fragmentation patterns in the mass spectra of 1-

octene in the epoxidation of 1-octene with TBHP

using Ti-MCM-41 sample.

198

Figure D.2: Fragmentation patterns in the mass spectra of tert-

butyl hydroperoxide (TBHP) in the epoxidation of 1-

octene with TBHP using Ti-MCM-41 sample.

199

Figure D.3: Fragmentation patterns in the mass spectra of Di-

tert-butyl peroxide (DTBP) in the epoxidation of 1-

octene with TBHP using Ti-MCM-41 sample.

200

Figure D.4: Fragmentation patterns in the mass spectra of 1,2-

epoxyoctane in the epoxidation of 1-octene with

TBHP using Ti-MCM-41 sample.

201

Figure D.5: Fragmentation patterns in the mass spectra of nonane

as internal standard in the epoxidation of 1-octene

202

xxiv

with TBHP using Ti-MCM-41 sample.

Figure D.6: Fragmentation patterns in the mass spectra of octane-

1,2-diol in the epoxidation of 1-octene with TBHP


203

Figure D.7: Fragmentation patterns in the mass spectra of octen-

3-ol in the epoxidation of 1-octene with TBHP using

Ti-MCM-41 sample.

204

Figure D.8: Fragmentation patterns in the mass spectra of octan-

2-one in the epoxidation of 1-octene with TBHP


205

xxiv

LIST OF TABLES

Page

Table 1.1 : Advantages and Disadvantages of Homogeneous and

Heterogeneous Catalysis.

4

Table 1.2 : Characteristic features of Shell’s epoxidation catalyst

compared with Titanium Silicalite 1.

4

Table 3.1 : List of Chemical Used in Synthesis of Ti-MCM-41.

44

Table 3.2 : Chemical Composition of the Synthesis Mixtures.

46

Table 3.3 : Additional Chemicals Used in the Synthesis of

Silylated Ti-MCM-41.

50

Table 3.4 : SiMe3/SiO2 molar ratios employed for Surface

Modification of Ti-MCM-41 Catalyst.

51

Table 3.5 : List of Chemicals Used in Catalytic Experiment.

55

Table 3.6 : List of GC Standards Used.

55

Table 3.7 : Compilation of characterization techniques. 60

Table 3.8 : Characterization methods applied to cornfirm the

presence of framework.

61

Table 3.9 : Information contained in the powder diffractogram. 67

Table 4.1 : Textural properties of the studied materials.

95

Table 4.2 : Lattice contraction of Ti-MCM-41 at various Si/Ti

ratios.

100

Table 4.3 : Thermogravimetric results for Ti-MCM-41 samples.

123

Table 4.4 : Thermogravimetric results for 100Ti-MCM-41

sample.

125

Table 4.5 : Band assignments in the IR spectra of MCM-41 and

Ti-MCM-41.

145

xxv

Table 4.6 : Varying Si/Ti ratio for the epoxidation of 1-octene using

Ti-MCM-41 as catalyst and TBHP as oxidants.

161

Table 4.7 : Varying Si/Ti ratio for the epoxidation of methyl oleate

using Ti-MCM-41 as catalyst and TBHP as oxidants.

Conditions: TBHP/oleate = 1:1 mol/mol, temp. = 70 °C.

173

Table 6.1 : Summary of textural properties and catalytic

performance of the studied materials.

188

Table A.1 : GC Method Development 194

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