vii
TABLE OF CONTENT
CHAPTER
TITLE
DECLARATION
ii
DEDICATION
iii
ACKNOWLEDGEMENT
iv
ABSTRACT
v
ABSTRAK
vi
LIST OF TABLES
xii
LIST OF FIGURES
xiv
LIST OF ABBREVIATIONS
1
2
PAGE
xviii
LIST OF SYMBOLS
xxi
LIST OF APPENDICES
xxii
INTRODUCTION
1
1.1
Background of study
1
1.2
Problem statement
5
1.3
Objectives of Study
7
1.4
Scopes and limitations of Study
8
1.5
Significance of Study
9
1.6
Thesis Organization
11
LITERATURE REVIEW
13
2.1
General Gas Purification Process
13
2.1.1
Adsorption
14
2.1.2
Absorption
15
2.1.3
Cryogenics Gas Separation
17
2.2
Membrane Technology
17
2.2.1
17
Background of Membrane Technology
viii
2.3
2.4
2.5
2.6
2.7
2.2.2
Gas permeation theory in polymer membrane
19
2.2.3
Types of Polymeric Membrane
24
2.2.4
Limitations of Polymeric Membrane
27
2.2.4.1 Robeson Upperbound
27
2.2.4.2 Membrane plasticization
28
2.2.4.3 Operational Issues
30
Inorganic Membranes
31
2.3.1
Zeolite
32
2.3.2
Carbon Membrane (CM)
34
2.3.3
Silica
36
2.3.4
Carbon Nanotubes (CNT)
37
2.3.5
Metal-Organic Framework (MOF)
39
2.3.6
Limitations of Inorganic Membrane
41
Mixed Matrix Membrane (MMM)
42
2.4.1
Theory
42
2.4.2
Progress in MMM
44
2.4.3
Challenges in MMM
48
Zeolitic Imidazole Framework (ZIF)
52
2.5.1
54
ZIF-8
ZIF-8 as MMM‘s Filler
58
2.6.1
60
Challenges of ZIF-8 as filler
Overcoming ZIF-8 Limitations as Filler
63
2.7.1
Overcoming limitation during Synthesis
64
2.7.1.1 Solvothermal Synthesis
65
2.7.1.2 Microwave-assisted Synthesis
66
2.7.1.3 Aqueous Room Temperature System
Synthesis
2.7.1.4 Synthesis Parameters
2.7.2
66
68
2.7.1.4.1 Metal source
68
2.7.1.4.2 Inorganic Solvent
69
2.7.1.4.3 Additive and solution pH
70
2.7.1.4.4 Synthesis Temperature
71
2.7.1.4.6 Activation procedures
72
Overcoming MOF limitation via modification
73
ix
3
METHODOLOGY
82
3.1
Introduction
82
3.3
Material Selection
84
3.3.1
Polymer
84
3.3.2
Filler
85
Sample preparation
86
3.4.1
ZIF-8 Synthesis
86
3.4.1.1 Materials
86
3.4.1.2 Synthesis Procedure
86
Asymmetric Membrane Fabrication
88
3.4.2.1 Materials
88
3.4.2.2 Asymmetric Membrane Preparation
88
3.4.2.3 Coating Solution Preparation
90
3.4
3.4.2
3.5
Characterization Techniques
3.5.1
90
Field Emission Scanning Electron Microscopy
(FESEM)
3.5.2
3.6
4
91
Scanning Electron Microscopy with Energy
Disperse X-ray Spectrometer (SEM/EDX)
91
3.5.3
X-ray Diffraction (XRD) Analysis
91
3.5.4
Differential Scanning Calorimeter (DSC)
93
3.5.5
Thermogravimetric Analysis (TGA)
93
3.5.6
Nitrogen Adsorption-Desorption Analysis
93
3.5.7
Transmission Electron Microscopy (TEM)
94
3.5.8
Infrared (IR) Spectroscopy (FT-IR)
94
3.5.9
Nuclear Magnetic Resonance (NMR)
94
Gas Permeation Test
95
AQUEOUS ROOM TEMPERATURE SYNTHESIS OF
ZEOLITIC
WITH
IMIDAZOLE
VARIOUS
FRAMEWORK
8
CONCENTRATIONS
(ZIF-8)
OF
TRIETHYLAMINE
97
4.1
Introduction
97
4.2
Experimental
99
4.3
Results and Discussion
100
x
4.4
5
4.3.1
XRD analysis
100
4.3.2
TEM analysis
103
4.3.3
ATR-IR analysis
105
4.3.4
Thermo-gravimetric analysis
109
4.3.5
BET analysis
110
4.3.6 Comparison with literatures
111
Conclusion
115
PREPARATION OF ASYMMETRIC PSF/ZIF-8 MMM
USING HEAT TREATED ZIF-8 WITH DIFFERENT
PARTICLE SIZES FOR CO2/CH4 SEPARATION
116
5.1
Introduction
116
5.2
Experimental
119
5.2.2
ZIF-8 Synthesis and Heat Treatment
119
5.2.3
Asymmetric Flat Sheet Membrane Preparation
119
5.3
Results and Discussion
120
5.3.1
ZIF-8 Characterizations
120
5.3.1.1 XRD
120
5.3.1.2 Surface properties
123
5.3.1.3 Thermal properties
123
5.3.2
Membrane Characterizations
124
5.3.3
Gas separation performance
131
5.3.3.1 The influence of ZIF-8 particle size on
gas separation
132
5.3.3.2 The influence of heat treated ZIF-8 on
gas separation
134
5.3.3.3 Comparison with commercial ZIF-8 as
dispersed phase
5.3.4
5.4
6
Overall MMMs performance
Conclusion
136
137
140
INFLUENCE OF ZIF-8 LOADING ON ASYMMETRIC
PSF/ZIF-8 MMM FOR CO2/CH4 SEPARATION
141
6.1
141
Introduction
xi
6.2
6.3
6.4
7
Experimental
142
6.2.1
ZIF-8 Synthesis
142
6.2.2
Asymmetric Flat-sheet Membrane Preparation
142
Results and Discussion
143
6.3.1
Membrane Characterizations
143
6.3.2
Gas Permeation Test
149
6.3.3
Comparison with literatures
154
Conclusion
157
PREPARATION OF AMMONIA MODIFIED ZIF-8
ASYMMETRIC MMM FOR CO2/CH4 SEPARATION
158
7.1
Introduction
158
7.2
Experimental
160
7.2.1
ZIF-8 Synthesis
160
7.2.2
ZIF-8 modification
160
7.2.3
Asymmetric Flatsheet Membrane Preparation
162
7.3
Results and discussion
162
7.3.1
Characterization of virgin and modified ZIF-8
162
7.3.2
Membrane characterizations
170
7.3.2.1 Morphological study
170
7.3.2.2 Thermal stability
173
Gas Permeation Measurement
175
7.3.3
7.3.3.1 Influence of virgin and modified ZIF8s
7.4
8
175
3.3.2
Influence of filler loading
179
7.3.4
Comparison with literatures
180
Conclusion
184
CONCLUSION AND RECOMMENDATIONS
185
8.1
General Conclusion
185
8.2
Recommendations
187
REFERENCES
189
Appendices A-E
217-242
xii
LIST OF TABLES
TABLE NO.
2.1
TITLE
Principal Suppliers of Membrane Natural Gas Separation
Systems (Baker and Lokhandwala, 2008)
2.2
PAGE
18
General advantages and limitations of CO2 separation media
(Baker and Lokhandwala, 2008, Baker, 2012, Rufford et al.,
2012, Sanders et al., 2013)
2.3
23
Pure-gas permeability (Barrer) of widely used polymers
(Baker, 2012)
25
2.4
The CO2 separation performance of zeolites membranes
33
2.5
Overview of common CNT synthesis (Ismail et al., 2008)
38
2.6
Comparison of polymeric, inorganic, and MMM properties
(Ismail et al., 2009)
43
2.7
List of ZIFs and its topology (Rahul Banerjee et al., 2008)
52
2.8
Current progress in ZIF-8 MMM
60
2.9
List of commercialized MOFs from Sigma Aldrich® (viewed
on 25 September 2014)
62
2.10
Overview of common MOF synthesis
67
2.11
MOF modification strategies
77
3.1
Polysulfone (PSf) properties
84
3.2
ZIF-8 properties
85
3.3
Coating solution preparation composition
90
3.4
Simulated XRD for ZIF-8(SOD) (Park et al., 2006)
92
4.1
Composition of TEA/total mole ratio for ZIF-8 synthesis
99
4.2
Properties of prepared ZIF-8s.
104
4.3
Current progress in ZIF-8 synthesis
113
xiii
5.1
Sample abbreviations
119
5.2
Properties of the prepared ZIF-8s
122
5.3
CO2 and CH4 permeance for neat PSf and PSf/ZIF-8s
membranes
5.4
131
Comparison of synthesized and commercial ZIF-8 as
dispersed phase
136
6.1
The amount of ZIF-8 loading into the PSf matrix
143
6.2
CO2 and CH4 permeance of prepared membranes
150
6.3
Comparison between polymer/ZIF-8
156
7.1
ZIF-8 modifications parameters
161
7.2
The surface properties of pure and modified ZIF-8
165
7.3
Glass transitional temperature of prepared membranes
175
7.4
Gas permeation performance of neat PSf and MMM*
177
7.5
Gas separation performance comparison of reported virgin
ZIF-8-based MMMs and this work
183
xiv
LIST OF FIGURES
FIGURE NO.
2.1
TITLE
PAGE
(a) Illustration of gas sorption in glassy polymers according
to dual-sorption model (Baker, 2004) (b) Solubility
coefficient in glassy polymers at different pressure according
to dual-mode sorption model
2.2
20
Cost comparison between DEA amine, optimized MDEA and
membrane processing for a 60 MMSCFD feed stream with
various carbon dioxide concentrations (Noble and Stern,
1995)
2.3
Robeson trade-off limit between gas permeability and gas
pair selectivity (Robeson, 2008)
2.4
28
Generic permeation behaviour of glassy polymer (Ismail and
Lorna, 2003)
2.5
24
30
Comparison of CO2/CH4 separation selectivity versus CO2
permeability for polymeric membranes and SAPO-34
membranes (S. Li et al., 2006a)
2.6
34
Schematic representations of the general classification of
porous solids and a typical construction procedure of a MOF
(J.R. Li et al., 2012)
2.7
39
Schematic of a mixed matrix membrane (MMM) (Tai-Shung
Chung et al., 2007)
43
2.8
Morphological diagram of MMM
50
2.9
The ZIF-8 simulation cell (left) and a closer view of the
relevant 6-membered window openings (right) (Hertäg et al.,
2011)
55
xv
2.10
(a) TGA curve of the as-synthesized samples, (b) XRD
patterns of the as-synthesized samples treated at different
temperatures and time, (c) photographs of the corresponding
samples with the specific thermal treatments (Pan et al.,
2011a)
2.11
56
The PXRD patterns for ZIF-8 samples measured during
chemical stability tests. (a) In refluxing benzene at 80°C for
up to 7 days. (b) In refluxing methanol at 65°C for up to 7
days. (c) In refluxing water at 100°C for up to 7 days. (d) In
refluxing aqueous NaOH solution for up to 1 day (Park et al.,
2006)
2.12
57
The gas separation performance of Matrimid®/ZIF-8 a) H2,
CO2 and O2, b) N2 and CH4, and c) gas pair selectivity (Qilei
Song et al., 2012)
2.13
62
XRD pattern of typical reaction mixture of MOF-5 (gray),
under basic conditions (blue); under acidic condition (red)
(Biemmi et al., 2009)
71
3.1
Experimental approach
83
3.2
Schematic diagram in synthesizing ZIF-8
87
3.3
Flat sheet membrane preparation via dry/wet phase inversion
89
3.4
Flat sheet membrane gas permeation setup
96
4.1
XRD pattern of ZIF-8 with different TEA concentration with
comparison with literature (Pan et al., 2011a)
4.2
101
Unknown component partially forms for sample A7: (a)
visible through naked, and characterized via (b) ATR-IR, (c)
XRD and (d) 1H NMR.
4.3
103
TEM images for sample: (a) A4, (b) A5, (c) A6, and (d) A7
with its size distribution (red line represent Gaussian fit).
105
4.4
ATR-IR spectrum of synthesized ZIF-8s.
107
4.5
The schematic illustration shows the influence of TEA
concentration on ZIF-8 formation.
4.6
108
Thermal stability of prepared ZIF-8s: (a) weight loss profile
of ZIF-8 and (b) XRD pattern of Sample A6 heated in open
air at elevated temperature.
110
xvi
5.1
Comparison of XRD patterns for ZIF-8s prepared (a) at
various TEA loadings and (b) after heat treatment.
121
5.2
TEM images of (a) Z100 (b), Z300, and (c) Z500
122
5.3
TGA curve of as-synthesized and heat-treated ZIF-8
124
5.4
TGA curves of prepared membranes
126
5.5
Influence of different filler properties on glass transition
temperature (Tg) of prepared membranes
5.6
Mechanical stability of prepared membranes. (a) Tensile
strength (MPa) and (b) elongation at break (%)
5.7
126
128
Cross-sectional morphology of as-synthesized ZIF-8 MMM,
with a) Neat PSf, b) M100, and c) M300 (Red circle indicates
the presence of ZIF-8 cluster).
5.8
129
Cross-sectional morphology of heat-treated ZIF-8 MMM,
with a) M100a, and b) M300a (Red circle indicates the
presence of ZIF-8 cluster).
5.9
EDX analysis on cross-sectional morphology of a) neat PSf
membrane, and b) M100a
5.10
130
130
The contribution of different ZIF-8 particle size on membrane
performance a) relative CO2 permeance, and b) relative
CO2/CH4 selectivity
134
5.11
The morphological diagram of PSf/ZIF-8
138
5.12
Illustration of gas permeation through (a) as-synthesized ZIF8 (b) heat-treated ZIF-8 and (c) different ZIF-8 particle sizes
139
6.1
XRD peaks of M5.0, M7.0, M10.0 and pure ZIF-8
144
6.2
Cross sectional images of membrane prepared at ZIF-8
loading of a) 0wt%, b) 0.5wt%, c) 1.0wt%, d) 5.0wt%, and e)
10wt%. Red arrows represent the agglomeration of ZIF-8
particles within the porous substructure.
6.3
146
EDX analysis of cross sectional morphology of a) M0.5, and
b) M1.0. The element Zn (red dot) represents the ZIF-8
particle in membrane
6.4
6.5
147
Tensile strength and elongation at break of prepared
membranes
148
TGA curves of prepared membranes
149
xvii
6.6
Illustration of gas permeation across different ZIF-8 loading
in asymmetric membrane
153
6.7
Morphological diagram of prepared PSf/ZIF-8 MMMs
153
6.8
Morphological diagram of polymer/ZIF-8 MMMs for
CO2/CH4 separation
155
7.1
ZIF-8 modification procedure
161
7.2
X-ray diffraction of modified ZIF-8s
163
7.3
Full range FTIR analysis of virgin and modified ZIF-8
166
7.4
FTIR absorbance at a) aliphatic C–N stretch (1250-1020cm1
), b) N–H bend (1650-1580cm-1), and c) N–H stretch (3400-
3250cm-1)
167
7.5
TGA curves of virgin and modified ZIF-8s
169
7.6
Idealized crystal structure of amine-modified ZIF-8 (adapted
from Liu et al. (2013)). The NH2-ZIF-8 represent the –NH2
attached on single side of C=C, while (NH2)2-ZIF-8 represent
the –NH2 group attached on both side of C=C in imidazole
linkers.
7.7
Cross-sectional membrane morphology of a) neat PSf, and b)
M0
7.8
171
Cross-sectional membrane morphology of a)M25a, b) M25b,
and c) M25c
7.9
169
172
Cross-sectional membrane morphology of a)M50a, b) M50b,
and c) M50c
173
7.10
TGA curve of prepared membranes
174
7.11
Gas separation performance of the prepared membranes with
i) CO2 permeance and ii) ideal CO2/CH4 selectivity. a), b),
and c) denotes respective membranes as described in Table
7.1
178
7.12
Separation performance of M25c at different filler loadings
179
7.13
Skin layer thickness of a) neat PSf membrane, and b) M25c
181
7.14
Robeson upperbound plot of polymer/ZIF-8 MMMs reported
in the literature, with neat PSf membrane and M25c prepared
in this study (open symbol represents the neat membrane for
the respective MMMs).
182
xviii
LIST OF ABBREVIATIONS
2-MeIM
-
2-methylimidazole
AIPO
-
Aluminophosphate zeolite
ATR-IR
-
Attenuated total reflectance infrared spectroscopy
BDA
-
Benzene-1,4-dicarboxylic acid
BET
-
Brunauer–Emmett–Teller surface area
BTC
-
Benzene-1,3,5-tricarboxylic acid
BTDA
-
3,3‘-4,4‘-benzophenone tetracarboxylic dianhydride
CA
-
Cellulose acetate
CM
-
Carbon membrane
CMS
-
Carbon molecular sieve
CNT
-
Carbon nanotube
CSD
-
CO2 supercritical drying
CTA
-
Cellulose triacetate
CVD
-
Chemical vapour deposition
DAPI
-
Diaminophenylindane
DDR
-
Deca-dodecasil 3R
DEA
-
Diethanolamine
DEF
-
Diethylformamide
DMF
-
Dimethylformamaide
DMSO
-
Dimethyl sulfoxide
DSC
-
Differential scanning calorimeter
EDX
-
Energy dispersion X-ray spectrometer
FAU
-
Faujasite-type zeolite
FESEM
-
Field emission scanning electron microscopy
HKUST
-
Hong Kong University of Science and Technology
MCMB
-
Mesocarbon microbeads
MDEA
-
Methylethanolamine
xix
MEA
-
Monoethanolamines
MIL
-
Matériauxs de l‘Institut Lavoisier
MMM
-
Mixed-matrix membrane
MMSCFD
-
Million metric standard cubic feet per day
MOF
-
Metal-organic framework
MSS
-
Mesoporous silica sphere
MWCNT
-
Multiwall carbon nanotube
NMP
-
N,N-methylpyrrolidone
NMR
-
Nuclear magnetic resonance
PBI
-
Polybenzimidazole
PDMS
-
Polydimethylsiloxane
PE
-
Polyethylene
PEBAX
-
Polyether block polyamide
PI
-
Polyimide
PIM
-
Polymer of intrinsic microporosity
PMPS
-
Polymethylphenylsiloxane
PP
-
Polypropylene
PPEES
-
Poly(1,4-phenylene ether-ether-sulfone)
PSA
-
Pressure swing adsorption
PSf
-
Polysulfone
PVDF
-
Polyvinylidenefluoride
PXRD
-
Powder X-ray diffraction
SAPO
-
silico-alumino-phosphate
SBU
-
Secondary building unit
SEM
-
Scanning electron microscopy
SSZ
-
Aluminosilicate
SWCNT
-
Single-wall carbon nanotube
TEA
-
Triethylamine
TEM
-
Transmission electron microscopy
TGA
-
Thermal gravimetric analysis
THF
-
Tetrahydrofurane
TSA
-
Temperature swing adsorption
VOC
-
Volatile organic compounds
XRD
-
X-ray diffraction
xx
ZIF
-
Zeolitic imidazole framework
ZSM
-
Zeolite socony mobil
xxi
LIST OF SYMBOLS
Å
-
Angstroms
A
-
Membrane effective area
b
-
Langmuir‘s affinity constant
C
-
Total sorption capacity
CD
-
Henry‘s sorption parameter
CH
-
Saturation sorption concentration
d
-
Distance of atoms in crystal lattice at different plane
DD
-
Gas diffusivity on Henry site
DH
-
Gas diffusivity on Langmuir site
Di
-
Diffusivity coefficient of gas i
ẟ
-
Chemical shift scales in NMR
K
-
Combination of sorption parameters
KD
-
Henry‘s law constant
Pc
-
Critical pressure
Pi
-
Permeability of gas i
PPlasticization
-
Plasticization pressure
Qi
-
Volumetric flowrate of gas i
Si
-
Solubility coefficient of gas i
Tc
-
Critical temperature
Tg
-
Glass transitional temperature
Tbp
-
Boiling point temperature
α
-
Gas pair selectivity
β
-
Beta cages
Δp
-
Transmembrane pressure difference
θ
-
Diffraction angle
λ
-
Wavelength of x-ray radiation
xxii
LIST OF APPENDICES
APPENDIX
TITLE
PAGE
A
List of Publications
217
B
Progress In MMM
219
C
Crystal Size Estimation
229
D
Size Distribution of Prepared ZIF-8
236
E
Miller Indices of Prepared ZIF-8
240