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
Figure 4.8: XRD patterns of 55Ti-MCM-41 (calcined &
uncalcined).
103
Figure 4.9: XRD patterns of 66Ti-MCM-41 (calcined &
uncalcined).
103
Figure 4.10: XRD patterns of 80Ti-MCM-41 (calcined &
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 4.15: SEM images of sample 55Ti-MCM-41. 110
Figure 4.16: SEM images of sample 66Ti-MCM-41.
111
Figure 4.17: SEM images of sample 80Ti-MCM-41. 112
Figure 4.18: SEM images of sample 100Ti-MCM-41. 113
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
Figure 4.30: TGA-DTG curves of (a) as-synthesized (uncalcined)
66Ti-MCM-41 and (b) calcined 66Ti-MCM-41.
132
Figure 4.31: TGA-DTG curves of (a) as-synthesized (uncalcined)
80Ti-MCM-41 and (b) calcined 80Ti-MCM-41.
133
Figure 4.32: TGA-DTG curves of (a) as-synthesized (uncalcined)
100Ti-MCM-41 and (b) calcined 100Ti-MCM-41.
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
using Ti-MCM-41 sample.
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
using Ti-MCM-41 sample.
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