vii
TABLE OF CONTENTS
CHAPTER
1
TITLE
PAGE
DECLARATION
ii
DEDICATION
iii
ACKNOWLEDGEMENTS
iv
ABSTRACT
v
ABSTRAK
vi
TABLE OF CONTENTS
vii
LIST OF TABLES
xiii
LIST OF FIGURES
xv
LIST OF ABBREVIATIONS
xx
LIST OF SYMBOLS
xxii
LIST OF APPENDICES
xxiv
INTRODUCTION
1
1.1
Research Background
1
1.2
Problem Statement
3
1.3
Aim of Objectives
5
viii
2
1.4
Scope of Research
5
1.5
Significance of Research
7
1.6
Limitation
7
1.7
Report Outline
8
1.8
Summary
8
LITERATURE REVIEW
9
2.1
9
2.2
2.3
2.4
Introduction
to Natural Gas
2.1.1 Composition of Natural Gas
10
2.1.2 Natural Gas Reserve in Malaysia
10
Carbon Dioxide in Natural Gas
12
2.2.1 Absorption
13
2.2.2 Membrane Separation
15
2.2.3 Adsorption
17
2.2.3.1 Adsorption Isotherm
20
2.2.3.2 Adsorbate-Adsorbent Interaction
22
Gas-Solid Adsorption Mechanism
24
2.3.1 Layer Formation
24
2.3.2 Micropore Filling
25
2.3.3 Pore Condensation or Capillary Condensation
27
Adsorbents
29
2.4.1 Activated Carbon and Carbon Molecular Sieve
30
ix
2.4.2 Zeolites
32
2.4.3 Aluminophosphate (AlPO-n) Molecular Sieve
36
2.4.4 Silicoaluminophosphate (SAPO-n) Molecular
Sieve
2.5
2.6
37
2.4.5 Activated Alumina
40
2.4.6 Silica Gel
41
2.4.7 Hydrotalcite-like Compounds
42
2.4.8 Metal Organic Framework (MOF)
43
2.4.9 Mesoporous Silica
45
Surface Modification
46
2.5.1 Ion Exchange
46
2.5.2 Cationic Treatment of Hydrotalcite (HTlc)
47
2.5.3 Chemical Modification of Porous Carbon
48
2.5.4 Functionalization Using Amine
49
Mechanism of Gas Separation Involving Extra
Framework Cation
50
2.6.1 Mechanism of Gas Adsorption in Different
Zeolite Framework
50
2.6.2 Mechanism of Gas Adsorption in Different
Zeolite Framework
2.7
3
Summary
52
54
MATERIALS AND METHODS
56
3.1
56
Introduction
x
3.2
3.3
3.4
Chemicals
56
3.2.1 Gases
57
Experimental Procedure
57
3.3.1 Ion Exchange Procedure
60
Characterization
61
3.4.1 X-Ray Diffraction (XRD) Analysis
61
3.4.2 Field Emission Scanning Electron
Microscopy (FESEM)
3.4.3 Fourier Transform Infrared Spectroscopy (FTIR)
62
63
3.4.4 Inductive Coupled Plasma-Optical
Emission Spectroscopy (ICP-OES)
3.4.5 Nitrogen Adsorption
3.5
3.6
64
65
3.4.5.1 Brunauer-Emmet-Teller (BET) Analysis
65
3.4.5.2 T-plot Method
66
3.4.5.3 Pore Size Distribution
67
3.4.5.3 Pore Volume
67
3.4.6 Thermogravimetric Analysis (TGA)
68
3.4.7 Differential Scanning Calorimetry (DSC)
69
Gas Adsorption Measurement
69
3.5.1 Isosteric Heat of Adsorption
76
Equilibrium Isotherm Equations
77
3.6.1 Langmuir Model
78
3.6.2 Freundlich Model
80
3.6.3 Sips Model
81
xi
4
3.7
Adsorbent Performance Evaluation
83
3.8
Summary
84
RESULTS AND DISCUSSION
85
4.1
Introduction
85
4.2
Properties of Cations Used in Ion Exchange
86
4.2.1 Introduction to Metal Cations
86
Characterization
87
4.3.1 X-Ray Diffrection (XRD) Analysis
88
4.3
4.3.2 Field Emission Scanning Electron Microscopy
(FESEM) Analysis
93
4.3.3 Fourier Transform Infrared Spectroscopy (FTIR)
Measurement
4.4
94
4.3.4 Elemental Composition
97
4.3.5 Nitrogen Adsorption Isotherm
98
4.3.6 Thermogravimetric Analysis (TGA)
103
4.3.7 Differential Scanning Calorimetry (DSC)
105
Adsorption Studies
106
4.4.1 Equilibrium Adsorption Isotherm Measuremet
107
4.4.2 Adsorption Capacity
117
4.4.3 Effect of Surface Area and Pore Volume on Gas
Adsorption
4.4.4 Effect of Crystallinity on Gas Adsorption
120
128
xii
4.5
Isosteric Heat of Adsorption
130
4.6
Equilibrium Adsorption Isotherm Models
135
4.6.1 Henry’s Constant
149
4.6.2 Adsorbent Performance Evaluation
150
Mechanism of CO2 and CH4 adsorption in Alkali Metal
Exchanged Na-SAPO-34 Zeolite
154
Summary
158
4.7
4.8
5
CONCLUSION AND RECOMMENDATIONS
159
5.1
Introduction
159
5.2
Conclusion
159
5.3
Recommendations for Future Work
161
REFERENCES
162
Appendices A-F
184-222
xiii
LIST OF TABLES
TABLE NO.
TITLE
2.1
Composition of natural gas
2.2
Malaysia natural gas reserve and production as at
PAGE
10
1st January 2012
12
2.3
Characteristics of physical and chemical adsorption Process
18
2.4
Advantages and disadvantages of the current technologies and
methods for CO2 removal from gas streams
55
3.1
General chemicals used for synthesis and ion exchange
57
4.1
Properties of metal cations involved during ion exchange
87
4.2
Peak position and intensities of Na-SAPO-34, 1st stage K+ and
2nd stage K+ obtained from XRD data
4.3
90
Peak position and intensities of Na-SAPO-34, 1st Stage Li+ and
2nd stage Li+ obtained from XRD data
91
4.4
Relative crystallinity after ion exchange
92
4.5
Average particle size distribution
92
4.6
Infrared band positions of the prepared materials
97
4.7
Elemental composition of all the prepared materials
98
4.8
Surface area, pore size and pore volume analysis
101
4.9
Previous studies of CO2 and CH4 adsorption on some
xiv
adsorbents
4.10
119
Effect of crystallinity on CO2 adsorption at different
temperature
129
4.11
Effect of crystallinity on CH4 adsorption at 298 K
129
4.12
Isosteric heat of adsorption of CO2
132
4.13
Distance between CO2-cation interacting pair
135
4.14
Langmuir, Freundlich and Sips model parameters at
273 K for CO2
4.15
Langmuir, Freundlich and Sips model parameters at
298 K for CO2
4.16
4.21
4.22
4.23
4.24
137
Correlation coefficient and error function for Langmuir,
Freundlich and Sips model equations at 298 K for CO2
4.20
137
Correlation coefficient and error function for Langmuir,
Freundlich and Sips model equations at 273 K for CO2
4.19
137
Langmuir, Freundlich and Sips model parameters at
298 K for CH4
4.18
136
Langmuir, Freundlich and Sips model parameters at
323 K for CO2
4.17
136
138
Correlation coefficient and error function for Langmuir,
Freundlich and Sips model equations at 323 K for CO2
138
Correlation coefficient and error function for Langmuir,
Freundlich and Sips model equations at 298 K for CH4
139
Henry’s constant or product of Langmuir equilibrium
constants 𝐻𝐾 ≈ (𝑞𝑠 . 𝑏)
149
Adsorbent evaluation for a binary separation of CO2/CH4
in a PSA system at 298 K (𝑃𝐴𝑑𝑠 =101.3 KPa, 𝑃𝐷𝑒𝑠 ≈ 7 KPa)
152
Capacity of CO2 at adsorption and desorption conditions
(𝑃𝐴𝑑𝑠 =101.3 KPa, 𝑃𝐷𝑒𝑠 ≈ 7 KPa)
152
xv
LIST OF FIGURES
FIGURE NO.
TITLE
PAGE
2.1
Malaysian natural gas reserve
11
2.2
Possible reaction pathways of CO2 with amine during
absorption
14
2.3
Pore size distribution on a typical porous material
20
2.4
The IUPAC classification of adsorption isotherm
21
2.5
Multilayer formation in BET theory
25
2.6
Micropore filling mechanism
27
2.7
Adsorption-desorption isotherm of a pure gas in a single
mesopore of cylindrical shape
28
2.8
Pore or capillary condensation mechanism in mesopore
28
2.9
Schematic of template synthesis procedure of microporous
carbon using zeolite Y
32
2.10
Zeolite framework with alternating AlO4 and SiO4 tetrahedra
33
2.11
Schematic diagram of zeolite A type
34
2.12
Secondary Building Units (SUB’s) Found in Nanoporous
Materials with TO4 Tetrahedra
36
2.13
Mechanism of Si substitution in AlPO framework
37
2.14
SAPO-34 (Chabazite) framework with possible cation
locations
39
xvi
2.15
Structure of hydrotalcite compound
2.16
Some MOFs used for CO2 separation (a) MOF-5,
(b) MOF-177, (C) MOF-74 and (d) MOF-199
2.17
42
44
Possible schematic mechanistic pathways for the formation
of MCM-41: (1) Liquid crystal phase Initiated and
(2) Silicate anion initiated
2.18
A schematic diagram of CH4 molecule diffusion in the
presence of different sized cations
2.19
52
Schematic diagram illustrating gas diffusion inside different
zeolite structures
2.22
51
Electrostatic interaction between methane and ion exchanged
zeolite surface, M1 and M2 represents two different cations
2.21
50
A schematic diagram of adsorbate-adsorbent interaction
with different sized cations
2.20
46
53
Schematic diagram illustrating gas diffusion on different
zeolite structures
54
3.1
General synthesis procedure
58
3.2
ASAP 2020 Micromeritics instrument
70
3.3
Schematic diagram of the volumetric adsorption system
71
3.4
Schematic diagram showing the Langmuir adsorption model
79
3.5
Heterogeneous surface having non-equivalent adsorption sites
82
4.1
XRD pattern of synthesized Na-SAPO-34 and zhabazite
zeolite from IZA
4.2
XRD pattern: (a) Na-SAPO-34, (b) 1st stage K+ and
(c) 2nd stage K+
4.3
88
XRD pattern: (a) Na-SAPO-34, (b) 1st stage Li+ and
89
xvii
(c) 2nd stage Li+
89
4.4
FESEM monograph of the prepared materials
94
4.5
Fourier transform infrared spectroscopy (FTIR) patterns
of all the prepared Samples
96
4.6
Nitrogen adsorption isotherm on all the prepared samples
99
4.7
N2 adsorption-desorption isotherm at 77 K (a) Na-SAPO-34,
(b) 1st stage K+, (c) 2nd stage K+, (d) 1st stage Li+ and
(e) 2nd stage Li+
4.8
TGA curves: (a) Na-SAPO-34, 1st stage K+ and 2nd stage K+,
(b) Na-SAPO-34, 1st stage Li+ and 2nd Stage Li+
4.9
106
Equilibrium adsorption isotherm of Na-SAPO-34, 1st stage K+
and 2nd stage K+ at a) 273 K, b) 298 K and c) 323 K
4.11
104
DSC curves: (a) Na-SAPO-34, 1st stage K+ and 2nd stage K+,
(b) Na-SAPO-34, 1st stage Li+ and 2nd stage Li+
4.10
100
108
Equilibrium adsorption isotherm of Na-SAPO-34,
1st stage Li+ and 2nd stage Li+ at (a) 273 K, (b) 298 K
and (c), 323 K
4.12
109
Equilibrium adsorption isotherm of methane at 298 K on
(a) Na-SAPO-34, 1st stage K+ and 2nd stage K+ , b) Na-SAPO-34,
1st stage Li+ and 2nd stage Li+
4.13
Possible shielding effect experienced by Cations depending on
cation size during CO2 adsorption
4.14
4.16
112
Effect of temperature on CO2 adsorption at 273, 298 and
323 K on Na-SAPO-34, 1st stage K+ and 2nd stage K
4.15
110
113
Effect of temperature on CO2 adsorption at 273, 298 and
323 K: (a) Na-SAPO-34, 1st stage Li+ and 2nd stage Li+
114
Effect of cation size on CH4 adsorption
116
xviii
4.17
Adsorption capacity on the prepared materials
(a) CO2 adsorption capacity at 273, 298 and 323 K and,
(b) CH4 adsorption at 298 K
4.18
Effect of BET surface area on CO2 adsorption on the
prepared materials: (a) 273, (b) 298 and, (c) 323 K
4.19
121
Effect of micropore surface area on CO2 adsorption on the
prepared materials: (a) 273, (b) 298 and, (c) 323 K
4.20
118
122
Effect of surface area on CH4 adsorption on the prepared
materials at 298 K: a) BET Surface Area,
b) Micropore surface area
4.21
Effect of micropore volume on CO2 adsorption on the prepared
materials: (a) 273, (b) 298 and, (c) 323 K
4.22
127
Effect of pore volume on CH4 adsorption on the prepared
materials at 298 K
4.23
125
128
Isosteric heat of adsorption as a function of loading:
(a) Na-SAPO-34, 1st stage K+ and 2nd stage K+,
(b) Na-SAPO-34, 1st stage Li+ and 2nd stage Li+
131
4.24
Multilayer type adsorption on a heterogeneous Surface
141
4.25
Model fits with experimental data for CO2 on Na-SAPO-34 at
different temperatures, (a) 273, (b) 298 K and (c) 323 K
4.26
Model fits with experimental data for CO2 on 1st stage K+ at
different temperatures, (a) 273, (b) 298 K and (c) 323K
4.27
145
Model fits with experimental data for CO2 on 1st stage Li+ at
different temperatures, (a) 273, (b) 298 K and (c) 323K
4.29
144
Model fits with experimental data for CO2 on 2nd stage K+ at
different temperatures, (a) 273, (b) 298 K and (c) 323K
4.28
143
146
Model fits with experimental data for CO2 on 2nd stage Li+ at
different temperatures, (a) 273, (b) 298 K and (c) 323K
147
xix
4.30
Model fits with experimental data for CH4 at 298 K on the
prepared materials, (a) Na-SAPO-34, (b) 1st stage K+,
(c) 2nd stage K+, d) 1st stage Li+ and e) 2nd stage Li+.
4.31
148
Adsorption-desorption isotherm of CO2 and CH4 at
298 K, (a) Na-SAPO-34, (b) 1st stage K+, (c) 2nd stage K+,
(d) 1st stage Li+, (e) 2nd stage Li+
151
4.32
Effect of cation size and mobility on gas adsorption
155
4.33
Proposed mechanistic adsorption model of CO2 and CH4
on alkali metal ion exchanged Na-SAPO-34 zeolite
4.34
156
Proposed mechanism of the separation of CO2 from
its mixture with CH4 in Na-SAPO-34 structure
157
xx
LIST OF ABBREVIATIONS
Al
-
Aluminium
Ar
-
Argon
ALPO-n
-
Aluminophosphate
Al2O3
-
Aluminium oxide
Al2O3.3H2O
-
Bauxite
BDDT
-
Brunauer, Deming, Deming and Teller
BET
-
Brunauer, Emmette and Teller
CH4
-
Methane
C2H6
-
Ethane
C3H8
-
Propane
C4H10
-
Butane
CHA
-
Chabazite
CO2
-
Carbon dioxide
Cs
-
Cesium
D-A
-
Dubinin and Astakhov
DEA
-
Diethanolamine
DSC
-
Differential scanning calorimetry
FESEM
-
Field emission scanning electron microscopy
Fr
-
Francium
FTIR
-
Fourier transform infrared spectroscopy
H2S
-
Hydrogen sulfide
He
-
Helium
HK-CY
-
Horvath and Kawazoe-Cheng and Yang
HTlcs
-
Hydrotalcite-like compounds
ICP-OES
-
Inductive coupled plasma-optical emission
spectroscopy
IR
-
Infrared
xxi
IUPAC
-
Internation Union of Pure and Appled Chemistry
K+
-
Potassium cation
KBr
-
Potassium bromide
L+
-
Lithium cation
LNG
-
Liquefied natural gas
M+
-
Monovalent cation
M2+
-
Divalent cation
M3+
-
Trivalent cation
MDEA
-
Methyl diethanolamine
MOF
-
Metal organic framework
Na+
-
Sodium cation
Na-SAPO-34
Sodium-silicoaluminophosphate-34 zeolite
N2
-
Nitrogen
N2O
-
Nitrous oxide
Ne
-
Neon
O2
-
Oxygen
OH
-
Hydroxyl group
P2O5
-
Phophorous pentoxide
P/VSA
-
Pressure/vacuum swing adsorption
PSD
-
Pore size distribution
Rb
-
Rubium
SAPO
-
Silicoaluminophosphate
SBU
-
Secondary building units
SERP
-
Sorption enhanced reaction process
SiO2
-
Silicon dioxide
Sr3+
-
Strontium cation
TEA
-
Triethanolamine
TETA
-
Triethylenetetramine
TGA
-
Thermogravimetric analysis
TSA
-
Temperature swing adsorption
Tscf
-
Trillion standard cubic feet
Xe
-
Xenon
xxii
LIST OF SYMBOLS
−𝛷
-
Sorbate-sorbent interaction energy
−∆𝐺
-
Free energy change
𝑃
-
Pressure
𝑃0
-
Saturation pressure
𝑃⁄𝑃0
-
Relative pressure
𝑅
-
Universal gas constant
𝑉
-
Physical volume of container
𝛷𝐷
-
Dispersion energy
𝛷𝑅
-
Repulsion energy
𝛷𝑃
-
Polarization energy
𝛷𝐹µ
-
Field-dipole interaction energy
𝛷𝐹𝑄
-
Field-gradient quadruple interaction energy
𝛷𝑆𝑃
-
Adsorbate-adsorbate interaction energy
𝜃
-
Surface coverage
𝑞
-
Quantity of gas adsorbed
𝑞𝑚
-
Quantity of gas adsorbed when the entire surface is
covered with a monolayer
𝐶
-
BET constant
𝑊
-
Quantity of gas adsorbed at relative pressure
𝑊0
-
Limiting micropore volume
𝛽
-
Affinity constant
𝐷𝑝
-
Particle size
𝐵
-
Dimensionless factor equal to 0.94
𝜆
-
X-Ray wavelength
𝛽
-
Line broadening at half the maximum intensity
𝜃𝐵
-
Bragg angle
xxiii
𝐾
-
Avagadro’s number
𝑁𝑎
-
Number of atoms per unit area of adsorbate
𝑁𝐴
-
Number of moles per unit area of adsorbate
𝐴𝑎
-
Constants in the Lennard-Jones potential for the
adsorbent
𝐴𝐴
-
Constant in the Lennard-Jones potential for the
adsorbate
𝑙
-
Distance between two nuclei of two layers
𝑑
-
Diameter of the adsorbed molecule
𝑉0
-
Limiting micropore volume
𝑛𝐷𝐴
-
Dubinin-Astakhov parameter
𝑛
-
Number of moles of a gas
𝑉𝑚
-
Manifold volume
𝑉𝑠
-
Reference volume
𝑉𝑣
-
Void volume of sample
𝑃𝑚
-
Manifold pressure
𝑇𝑚
-
Manifold temperature
𝑉𝑣𝑓
-
Free space volume
𝑉𝑑
-
Total volume of the adsorptive dosed
𝑞𝑠𝑡
-
Isoteric heat of adsorption
𝑏
-
Langmuir constant
𝑞𝑠
-
Maximum amount adsorbed
𝐻𝐾
-
Henry’s constant
𝑛𝐹
-
Heterogeniety parameter in the Freundlinch equation
𝑛𝑠
-
Heterogeneity parameter in the Sips equation
𝑦
-
Data point
𝑦𝑚𝑒𝑎𝑛
-
Average value of 𝑦 data
𝑑𝑓
-
Degree of freedom
∆𝑁1
-
Working capacity
𝑅 (%)
-
Regenerability
𝛼1,2
-
Selectivity
xxiv
LIST OF APPENDICES
APPENDIX
A
TITLE
PAGE
Carbon dioxide and methane equilibrium adsorption
tabular data report
184
B1
Isoster plots of all the prepared materials
190
B2
Heat of adsorption tabular report
195
C
Linear plots of Langmuir model for Carbon dioxide
on all the prepared materials at different temperature
D
Linear Plots of Langmuir model for methane on all the
prepared materials at 298 K
E
205
Carbon dioxide equilibrium adsorption and model data
fittings for 2nd stage K+
G4
202
Carbon dioxide equilibrium adsorption and model data
fittings for 1st stage K+
G3
201
Carbon dioxide equilibrium adsorption and model data
fittings for Na-SAPO-34
G2
200
Linear Plots of Freundlich model for methane on all the
prepared materials at 298 K
G1
199
Linear Plots of Freundlich model for carbon dioxide on
all the prepared materials at different temperature
F
198
Carbon dioxide equilibrium adsorption and model data
208
xxv
fittings for 1st stage Li+
G5
G6
H
211
Carbon dioxide equilibrium adsorption and model data
fittings for 2nd stage Li+
214
Methane experimental and model data fittings on all the
prepared materials
217
PUBLICATIONS
222