PhD work

Design and Synthesis of Functionalized Ligands for Adsorptive
Separation of CO2/N2 and CO2/CH4 Mixtures
Dr. Kalpesh Mohan Khot
Institute of Chemical Technology

Overview
Institute of Chemical Technology 2
1. Introduction
2. Aliphatic Ligand Functionalized Polystyrene Adsorbents for Separation of CO2 from
N2 and CH4
3. Heterocyclic Saturated Ligand Functionalized Polystyrene Adsorbents for
Separation of CO2 from N2 and CH4
4. Heterocyclic Unsaturated Five Member Ligand Functionalized Polystyrene
Adsorbents for Separation of CO2 from N2 and CH4
5. Heterocyclic Unsaturated Six Member Ligand Functionalized Polystyrene

Introduction

Greenhouse Gas Effect and Global Warming
Earth’s Atmospheric Gases
Non-green house gases
(e.g.- N2,O2) ~99%
Green house gases
(e.g.- H2O,CO2,CH4) ~1%

Technologies Used in CO2 Capture
CO2 capture technologies
Absorption Membrane Separation AdsorptionCryogenic distillation
Energy requirements: 330-340
kWh/ton CO2
(Environ. Prog., 2006, 25: 208 )
CO2 capture capacity
CO2 selectivity
Ease of regeneration
Pressure Swing Adsorption (PSA)
kWh/ton CO2
(Environ. Prog., 2006, 25: 208 )
kWh/ton CO2
(Environ. Prog., 2006, 25: 208 )
kWh/ton CO2
(Environ. Prog., 2006, 25: 208 )

Literature Reported Adsorbents for CO2 Capture
Adsorbent Surface
area
(m2/g)
Amine
loading
(mol/kg)
Temp
(K)
Adsorption
capacity
(mol/kg)
Adsorption
(mol
CO2/mol
amine)
Reference
Zeolite
β-Zeolite 574.0 - 303 1.80 - J. Nat. Gas Chem.,
2009, 18: 167.
13X (MEA) 14.9 8.20 348 1.11 0.14 Micropor. Mesopor. Mater.,
2009, 121: 84.
Activated
carbon
Pitch based AC
fibers OG-A7
907.0 - 298 0.70 - J. Colloid Interface Sci.,
2006, 298: 523.
NH3- AC 1323 - 309 1.73 - Appl. Surf. Sci. 2004, 225:
235.
Silica
SBA-15 (EDA) - 1.32 295 1.95 1.47 Ind. Eng. Chem. Res,
2005, 44: 3099.
SBA-15 (PEI) 13.0 0.83 348 2.88 3.47 Micropor. Mesopor. Mater.,
2008, 113: 31.
Metal Organic
Frameworks
Mg-MOF -74 1174.0 - 298 8.61 - J. Colloid Interface Sci.
2011, 353: 549.
Cu-MOF - - 298 0.70 - J. Colloid Interface Sci.,
2011, 357: 504.
Polymers
PMMA(MEA) 470.0 5.57 293 0.78 0.14 Ind. Eng. Chem. Res.,
2005, 44: 1542.
OC 1065 IER 26.2 6.69 323 2.50 0.37 Ind. Eng. Chem. Res.,
2012, 51: 6907.

Design of CO2 Selective Ligands
Objectives:
Tertiary ‘N’ atom based ligand on hydrophobic matrix
Presence of tertiary ‘N’ will avoid chemisorption
Covalent attachment to the matrix
Covalent attachment of the ligand will help in overcoming limitation of lack of
stability over repeated cycles
+ CO2
RNHCO2
-
RNH3
+
Low
temp
H2O
+ RNH2RNH3
+
HCO3
-
2 RNH2
2 RNH3
+ CO3
2-
pH
Carbonate
Bicarbonate
Carbamate
R3N + CO2 + H2O R3NH+
HCO3
-
Bicarbonate
Reaction of primary amine or secondary amine with CO2
Reaction of tertiary amine with CO2
Ref : J. Phys. Chem. 1981, 85: 3660.

2. Aliphatic Ligand Functionalized Polystyrene Adsorbents for Separation of CO2
from CH4 and N2

Synthesis and Characterization
Cl
HN
CH2CH2OH
CH2CH2OH
Diethanolamine
n
N
CH2CH2OH
CH2CH2OH
n
N
CH3
CH3
n
PS-DMA
DMF, 363 K
PS-DEA
Chloromethylated polystyrene
FTIR Characterization
PS-DEA PS-DMA
CMPS PS-DEA PS-DMA
Ligand loading
(mol/kg)
- 2.8 3.2
BET surface are
(m2/g)
28 21 28

Equilibrium Adsorption Studies
Gravimetric Method

Atmospheric Pressure Equilibrium Adsorption
CO2
0
0.1
0.2
0.3
0 200 400 600 800
CO2adsorbed(mol/kg)
Times (sec)
CMPS
PS-DEA
PS-DMA
CO2 equilibrium capacity (mol/kg)
CMPS PS-DEA PS-DMA
0.16 0.20 0.25
303 K

High Pressure Equilibrium Adsorption Studies at 303 K
CO2 CH4
Dual Mode sorption Parameter
0
10
20
30
40
50
60
70
80
90
100
0 10 20 30 40
q(CO2adsorbed(cc/g)atSTP)
Pressure(atm)
CMPS
PS-DEA
PS-DMA
0
0.5
1
1.5
2
2.5
3
0 5 10
q(CH4adsorbed(cc/g)atSTP)
Pressure(atm)
CMPS
PS-DEA
PS-DMA
Adsorbent kD
(cm3(STP)/g poly/atm)
CH
’
(cm3(STP)/g poly)
b
(atm-1)
Adsorption capacity
(mol/kg)
CO2 CH4 CO2 CH4 CO2 CH4 CO2 CH4
CMPS 1.29 0.09 40.95 2.10 0.17 1.26 3.86 0.12
PS-DEA 0.43 0.11 81.61 1.10 0.23 0.17 1.16 0.08
PS-DMA 0.92 0.09 30.22 1.66 0.41 0.18 2.06 0.08
bP
bPC
PkC H
D


1
'
*(CO2 (Tb=216 K, Tc=304 K), CH4 (Tb=112 K, Tc=190 K), N2 (Tb=77 K, Tc=126 K))
* Nat. Mater., 2011,10: 372.

20:80 40:60
50:50
Ideal Adsorbed Solution Theory (IAST) Selectivity for CO2/CH4
0
20
40
60
2 4 6 8 10
Sads(CO2/CH4)
Pressure (atm)
CMPS
PS-DEA
PS-DMA
0
20
40
60
2 4 6 8 10
Sads(CO2/CH4)
Pressure (atm)
CMPS
PS-DEA
PS-DMA
0
20
40
2 4 6 8 10
Sads(CO2/CH4)
Pressure (atm)
CMPS
PS-DEA
PS-DMA













2
1
2
1
2,1
y
y
x
x
S ads

FTIR Characterization of Post CO2 Sorbed Adsorbents
CO O CO O CO O
v1 v2 v3
(1388 cm-1)
Symmetric stretching
Raman active
(666 cm-1)
Bending
IR active
(2349 cm-1)
Asymmetric stretching
IR active
CMPS PS-DEA PS-DMA
CMPS PS-DEA PS-DMA
2347 cm-1 2348 cm-1 2348 cm-1

Pulse Chromatography Studies
Conc(kg/m3)
Time (sec)
N2
CH4
CO2
Column length (mm) 1500
Column diameter (mm) 6
Average weight of adsorbent (g) 20
Detector TCD
Carrier gas H2

Pulse Chromatographic Studies
CMPS PS-DEA
PS-DMA
Ref: Heer, P. K. K. S. Engineering analysis of
renewable energy and chemical resources.
Ph.D. Thesis. Institute of Chemical
Technology, 2014.
0.0
0.1
0.2
50 150 250 350 450 550
Conc(kg/m3)
Time (sec)
0.0
0.1
0.2
50 100 150 200 250 300 350 400 450
Conc(kg/m3)
Time (sec)
◊ CO2 ∆ CH4 Ο N2
0
0.1
0.2
50 150 250 350 450
Conc(kg/m3)
Time (sec)

PS-DMA
CO2 CH4 N2
PS-DEA
CO2 CH4 N2
0
200
400
600
800
1000
0 0.2 0.4 0.6
σ2L/2μ2ν(sec)(CO2)
1/ν2 (s2/m2)
0
10000
20000
30000
40000
0 0.5
σ2L/2μ2ν(sec)(CH4)
1/ν2 (s2/m2)
0
10000
20000
30000
40000
50000
60000
0 0.2 0.4 0.6
σ2L/2μ2ν(sec)(N2)
1/ν2 (s2/m2)
0
200
400
600
800
1000
0 0.5
1/ν2 (s2/m2)
0
20000
40000
60000
80000
0 0.5
1/ν2 (s2/m2)
0
40000
80000
120000
160000
0 0.5
1/ν2 (s2/m2)
Mass Transfer Resistance
◊ 308K □ 318K Δ 328K × 338K ○ 348K
)(
)1(
.
2 22
2
cpf
L
v
D
v
L









CMPS
CO2 CH4 N2
0
100
200
0 0.2 0.4 0.6
1/ν2 (s2/m2)
0
1000
2000
3000
0 0.1 0.2 0.3 0.4 0.5 0.6
1/ν2 (s2/m2)
0
10000
20000
30000
0 0.5
1/ν2 (s2/m2)
Mass Transfer Resistance
◊ 308K □ 318K Δ 328K × 338K ○ 348K

Equilibrium Adsorption Constant
CO2 CH4
N2
1
10
100
2.8 2.9 3 3.1 3.2 3.3
K(mol/kg/atm)×102
1/T (K-1) ×103
CMPS
PS-DEA
PS-DMA
1
10
2.8 2.9 3 3.1 3.2 3.3
K(mol/kg/atm)×103
1/T (K-1) ×103
CMPS
PS-DEA
PS-DMA
2
20
2.8 2.9 3 3.1 3.2 3.3
K(mol/kg/atm)×103
1/T (K-1) ×103
CMPS
PS-DEA
PS-DMA

Equilibrium Separation Factor
CO2
/N2 CO2
/CH4
CH4
/N2
0
5
10
15
20
25
30
35
2.8 2.9 3 3.1 3.2 3.3
αCO2/N2
1/T (K-1) ×103
CMPS
PS-DEA
PS-DMA
0
1
2
3
4
5
6
7
8
9
10
2.8 2.9 3 3.1 3.2 3.3
αCO2/CH4
1/T (K-1) ×103
CMPS
PS-DEA
PS-DMA
1.0
2.0
3.0
4.0
2.8 2.9 3 3.1 3.2 3.3
αCH4/N2
1/T (K-1) ×103
CMPS
PS-DEA
PS-DMA
B
A
BAei
K
K
/,


3. Heterocyclic Saturated Ligand Functionalized Polystyrene Adsorbents for
Separation of CO2 from N2 and CH4

PS-Piperdine PS-Piperazine
Ligand loading (mol/kg) 2.04 2.08
BET surface are
(m2/g)
26 26
Cl
N
N
CH3
Chloromethylated polystyrene n
n
NHN CH3
HN
N
PS-Piperdine
n
Piperidine
PS-PiperazineN-methyl piperazine
DMF, 363K
DMF, 363K

CO2
0
0.1
0.2
0.3
0.4
0.5
0 200 400 600 800
CO2adsorbed(mol/kg)
Times (sec)
PS-Piperidine
PS-Piperazine
CO2 equilibrium capacity
(mol/kg)
0.39 0.42
303 K

High Pressure Equilibrium Adsorption Studies
CO2 CH4
0
10
20
30
40
50
60
70
80
0 10 20 30 40
Pressure(atm)
PS-Piperdine
PS-Piperazine
0
0.5
1
1.5
2
2.5
0 5 10
Pressure(atm)
PS-Piperdine
PS-Piperazine
Adsorbent kD
(cm3(STP)/g poly /atm)
CH
’
(cm3(STP)/g poly)
b
(atm-1)
Adsorption capacity
(mol/kg)
PS-Piperdine 0.04 0.07 86.66 1.40 0.07 0.31 2.92 0.09
PS-Piperazine 0.82 0.11 39.25 1.04 0.22 1.61 3.08 0.10
bP
bPC
PkC H
D


1
'

20:80 40:60
50:50
IAST Selectivity for CO2/CH4
0
20
40
60
2 4 6 8 10
Sads(CO2/CH4)
Pressure (atm)
PS-Piperidine
PS-Piperazine
0
20
40
60
2 4 6 8 10
Sads(CO2/CH4)
Pressure (atm)
PS-Piperidine
PS-Piperazine
0
20
40
60
1 3 5 7 9
Sads(CO2/CH4)
Pressure (atm)
PS-Piperidine
PS-Piperazine

2340 cm-1 2336 cm-1

◊ CO2 ∆ CH4 Ο N2
0
0.1
0.2
50 150 250 350 450
Conc(kg/m3)
Time (sec)
0.0E+00
4.0E-03
8.0E-03
1.2E-02
0 100 200 300 400 500
Conc(kg/m3)
Time (sec)
Ref: Heer, P. K. K. S. Engineering analysis of renewable energy and chemical resources. Ph.D.
Thesis. Institute of Chemical Technology, 2014.

CO2 CH4
N2
4
2.8 2.9 3 3.1 3.2 3.3
K(mol/kg/atm)×103
1/T (K-1) ×103
PS-Piperidine
PS-Piperazine
1
2.8 2.9 3 3.1 3.2 3.3
K(mol/kg/atm)×103
1/T (K-1) ×103
PS-Piperidine
PS-Piperazine
2
20
2.8 2.9 3 3.1 3.2 3.3
K(mol/kg/atm)×102
1/T (K-1) ×103
PS-Piperdine
PS-Piperazine

CO2
/N2 CO2
/CH4
CH4
/N2
0
1
1
2
2
3
3
4
4
5
2.8 2.9 3 3.1 3.2 3.3
αCH4/N2
1/T (K-1) ×103
PS-Piperdine
PS-Piperazine
0
2
4
6
8
10
12
2.8 2.9 3 3.1 3.2 3.3
αCO2/CH4
1/T (K-1) ×103
PS-Piperidine
Ps-Piperazine
0
5
10
15
20
25
30
35
40
45
50
2.8 2.9 3 3.1 3.2 3.3
αCO2/N2
1/T (K-1) ×103
PS-Piperdine
PS-Piperazine
B
A
BAei
K
K
/,


4. Heterocyclic Unsaturated Five Member Ligand Functionalized Polystyrene

PS-Pyrrole PS-Imidazole
Ligand Loading
(mol/kg)
1.98 1.55
BET surface are
(m2/g)
28 31Cl
N
N
PS-Imidazole
n
n
N
N
H
N
H
N
n
PS-PyrrolePyrrole
Imidazole
DMF, 363 K
DMF, 363 K

CO2
(mol/kg)
0.42 0.46
303 K
0
0.1
0.2
0.3
0.4
0.5
0 200 400 600 800
CO2adsorbed(mol/kg)
Times (sec)
PS-Pyrrole
PS-Imidazole

CO2 CH4
0
10
20
30
40
50
60
70
80
90
0 10 20 30 40
Pressure(atm)
PS-Pyrrole
PS-Imidazole
0
0.5
1
1.5
2
2.5
3
0 5 10
Pressure(atm)
PS-Pyrrole
PS-Imidazole
Adsorbent kD
CH
’
(cm3(STP)/g poly)
b
(atm-1)
Adsorption capacity
(mol/kg)
PS-Pyrrole 0.24 0.07 76.30 1.43 0.09 0.61 3.12 0.10
PS-Imidazole 1.22 0.11 38.51 1.68 0.25 0.74 3.71 0.11
bP
bPC
PkC H
D


1
'

20:80 40:60
50:50
0
20
40
60
2 4 6 8 10
Sads(CO2/CH4)
Pressure (atm)
PS-Pyrrole
PS-
Imidazole
0
20
40
60
2 4 6 8 10
Sads(CO2/CH4)
Pressure (atm)
PS-Pyrrole
PS-Imidazole
0
20
40
60
1 3 5 7 9
Sads(CO2/CH4)
Pressure (atm)
PS-Pyrrole
PS-Imidazole

2337 cm-1 2335 cm-1

◊ CO2 ∆ CH4 Ο N2
0
0.1
0.2
50 250 450 650 850 1050 1250
Conc(kg/m3) Time (sec)
0.0E+00
4.0E-03
8.0E-03
1.2E-02
0 200 400 600 800 1000
Conc(kg/m3)
Time (sec)

CO2 CH4
N2
1
10
100
2.8 2.9 3 3.1 3.2 3.3
K(mol/kg/atm)×102
1/T (K-1) ×103
PS-Pyrrole
PS-Imidazole
1
10
2.8 2.9 3 3.1 3.2 3.3
K(mol/kg/atm)×103
1/T (K-1) ×103
PS-Pyrrole
PS-Imidazole
2
20
2.8 2.9 3 3.1 3.2 3.3
K(mol/kg/atm)×103
1/T (K-1) ×103
PS-Pyrrole
PS-Imidazole

CO2
/N2 CO2
/CH4
CH4
/N2
0
10
20
30
40
50
60
2.8 2.9 3 3.1 3.2 3.3
αCO2/N2
1/T (K-1) ×103
PS-Pyrrole
PS-Imidazole
0
2
4
6
8
10
12
14
2.8 2.9 3 3.1 3.2 3.3
αCO2/CH4
1/T (K-1) ×103
PS-Pyrrole
PS-Imidazole
0
1
1
2
2
3
3
4
4
5
2.8 2.9 3 3.1 3.2 3.3
αCH4/N2
1/T (K-1) ×103
PS-Pyrrole
PS-Imidazole

5. Heterocyclic Unsaturated Six Member Ligand Functionalized Polystyrene

Synthesis
PS-HM PS-CA PS-MP PS-BIMP
Ligand Loading
(mol/kg)
- 1.62 1.92 1.52
BET surface are
(m2/g)
29 27 30 31
Cl
n
POCl3
N
COOH
Cl Cl N
H
N+
N
COOH
N
N
N
N
N
HO
N
O
n
4-hydroxymethyl Pyridine PS-MP
O
NHO OH
O
n
PS-HM PS-CA
N
COOH
OH OH
2,6-Bis-imidazol-1-yl-pyridine-4-carboxylic acid
PS-BIMP
n
N
N
N
N
N
OO
(BIMP)
HO
NHO OH
O
Citrazinic acid
n
OH
H3CO
O
DMF, 358 K
CH3COOK H2NNH2
Acetoxymethyl resin
DMF, 403 K
DMF, 403 K
DMF, 403 K

Mass Characterization
2,6-Dichloropyridine-4-Carboxylic Acid 2,6-Bis-Imidazo-1-yl-Pyridine-4-Carboxylic acid
192
174156
146
210
238
256

NMR Characterization
2,6-Dichloropyridine-4-Carboxylic Acid 2,6-Bis-Imidazo-1-yl-Pyridine-4-Carboxylic acid
1H
13C

PS-CA PS-MP
PS-BIMP

(mol/kg)
PS-HM PS-CA
0.15 0.43
PS-MP PS-BIMP
0.55 0.73
303 K
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0 200 400 600 800
CO2adsorbed(mol/kg)
Times (sec)
PS-HM
PS-CA
PS-MP
PS-BIMP
CO2

CO2 CH4
Adsorbent kD
CH
’
(cm3(STP)/g poly)
b
(atm-1)
Adsorption capacity
(mol/kg)
PS-BIMP 1.20 0.06 40.84 2.20 0.34 0.45 3.78 0.12
PS-MP 1.25 0.06 34.96 2.10 0.38 0.45 3.75 0.11
PS-CA 0.94 0.10 43.71 3.56 0.25 0.17 3.51 0.10
PS-HM 0.78 0.06 67.94 2.01 0.08 0.98 3.80 0.12
bP
bPC
PkC H
D


1
'
0
10
20
30
40
50
60
70
80
90
100
0 10 20 30 40
Pressure(atm)
PS-HM
PS-CA
PS- MP
PS-BIMP
0
0.5
1
1.5
2
2.5
3
0 2 4 6 8 10
Pressure(atm)
PS-HM
PS-CA
PS- MP
PS-BIMP

20:80 40:60
50:50
0
20
40
60
80
100
2 4 6 8 10
Sads(CO2/CH4)
Pressure (atm)
PS-HM
PS-CA
PS-MP
PS-BIMP
0
20
40
60
80
100
120
2 4 6 8 10
Sads(CO2/CH4)
Pressure (atm)
PS-HM
PS-CA
PS-MP
PS-BIMP
0
20
40
60
80
100
120
1 3 5 7 9
Sads(CO2/CH4)
Pressure (atm)
PS-HM
PS-CA
PS-MP
PS-BIMP

PS-HM PS-CA
PS-MP PS-BIMP
PS-HM PS-CA PS-MP PS-BIMP
2348 2336 2331 2329

PS-HM PS-CA
PS-MP PS-BIMP
◊ CO2 ∆ CH4 Ο N2
0.0E+00
4.0E-03
8.0E-03
1.2E-02
0 100 200 300 400 500 600 700
Conc(kg/m3)
Time (sec)
0.0E+00
4.0E-03
8.0E-03
1.2E-02
0 200 400 600 800 1000 1200
Conc(kg/m3)
Time (sec)
0.0E+00
4.0E-03
8.0E-03
1.2E-02
0 500 1000 1500 2000
Conc(kg/m3)
Time (sec)
0.0E+00
4.0E-03
8.0E-03
1.2E-02
0 500 1000 1500 2000
Conc(kg/m3)
Time (sec)

CO2 CH4
N2
2
20
2.8 2.9 3 3.1 3.2 3.3
K(mol/kg/atm)×103
1/T (K-1) ×103
PS-HM
PS-CA
PS-MP
PS-BIMP
1
10
2.8 2.9 3 3.1 3.2 3.3
K(mol/kg/atm)×103
1/T (K-1) ×103
PS-HM
PS-CA
PS-MP
PS-BIMP
1
10
100
2.8 2.9 3 3.1 3.2 3.3
K(mol/kg/atm)×102
1/T (K-1) ×103
PS-HM
PS-CA
PS-MP
PS-BIMP

CO2
/N2 CO2
/CH4
CH4
/N2
0
1
2
3
4
5
6
2.8 2.9 3 3.1 3.2 3.3
αCH4/N2
1/T (K-1) ×103
PS-HM
PS-CA
PS-MP
PS-BIMP
0
2
4
6
8
10
12
14
16
18
2.8 2.9 3 3.1 3.2 3.3
αCO2/CH4
1/T (K-1) ×103
PS-HM
PS-CA
PS-MP
PS-BIMP
0
10
20
30
40
50
60
70
80
90
2.8 2.9 3 3.1 3.2 3.3
αCO2/N2
1/T (K-1) ×103
PS-HM
PS-CA
PS-MP
PS-BIMP

Comparison of adsorbents of current studies

CMPS
PS-HM
PS-DEA
PS-DMA
PS-Piperdine
PS-Piperazine
PS-Pyrrole
PS-CA
PS-Imidazole
PS-MP
PS-BIMP
Comparison of Functionalized Polystyrene Adsorbents
0
10
20
30
40
50
60
70
80
90
2.8 3 3.2 3.4
αCO2/N2
1/T (K-1) ×103
CMPS
PS-DEA
PS-DMA
PS-Piperdine
PS-Piperazine
PS-Pyrrole
PS-Imidazole
PS-HM
PS-CA
PS-MP
PS-BIMP
4
6
8
10
12
14
16
18
2.8 3 3.2 3.4
αCO2/CH4
1/T (K-1) ×103
CMPS
PS-DEA
PS-DMA
PS-Piperidine
Ps-Piperazine
PS-Pyrrole
PS-Imidazole
PS-HM
PS-CA
PS-MP
PS-BIMP
CO2
/N2
CO2
/CH4

Comparison of Equilibrium Adsorption Capacity with Literature
Adsorbent
Amine
loading
Temp
Atmospheric pressure
equilibrium adsorption
capacity
High pressure equilibrium
adsorption capacity De
×1011
(m2
/sec-1
)
Reference
(mol/kg) (K)
CO2 adsorbed CO2 adsorbed
/mol of amine
CO2 CH4
(mol/kg) (mol/kg) (mol/kg)
PS-BIMP 1.52 303 0.73 0.48 3.78 0.120 1.49
Present work
PS-MP 1.92 303 0.55 0.29 3.75 0.114 1.54
PS-Imidazole 1.55 303 0.46 0.29 3.71 0.110 1.45
PS-CA 1.62 303 0.43 0.26 3.51 0.104 1.55
PS-Pyrrole 1.98 303 0.42 0.21 3.12 0.097 1.41
PS-Piperazine 2.08 303 0.42 0.20 3.08 0.095 1.44
PS-Piperdine 2.04 303 0.39 0.19 2.92 0.091 1.48
PS-DMA 3.20 303 0.25 0.08 2.06 0.082 1.46
PS-DEA 2.80 303 0.20 0.07 1.16 0.079 1.43
PS-HM - 303 0.15 - 3.80 0.118 1.45
CMPS - 303 0.16 - 3.86 0.120 1.52
OC 1065 IER 6.69 323 2.50 0.37 - -
Ind. Eng. Chem. Res.,
2012 , 51: 6907
PMMA(MEA) 5.57
293
0.78 0.14 - - Ind. Eng. Chem. Res.,
2005, 44: 1542.1.07 0.24 - -PMMA(DEA) 4.47
β- Zeolite
(MEA 40 wt %)
6.56 303 0.77 0.12 - -
J. Nat. Gas Chem.,
2009, 18 :167
Silicalite -
303
- - - - 0.09
J. Colloid Interface Sci.,
2007,313:12NaY - - - - - 0.00004
4A zeolite -
303
- - - -
0.00004
Adsorption,
2004,10: 111
CaX - - - - - 0.02
13X - 313 - - - - 0.0006
Micropor. Mesopor. Mat.
2012,158: 219.

Comparison of CO2 capture Efficiency with Literature
Method Adsorbent
Surface
area
(m2/g)
Amine
loading
Temp
Atmospheric pressure
equilibrium adsorption capacity
Reference
(mol/kg) (K)
CO2 adsorbed CO2 adsorbed
/mol of amine(mol/kg)
Adsorption
PS-BIMP 31 1.52 303 0.73 0.48
Present work
PS-MP 30 1.92 303 0.55 0.29
PS-Imidazole 31 1.55 303 0.46 0.29
PS-CA 27 1.62 303 0.43 0.26
PS-Pyrrole 28 1.98 303 0.42 0.21
PS-Piperazine 26 2.08 303 0.42 0.20
PS-Piperdine 26 2.04 303 0.39 0.19
PS-DMA 28 3.20 303 0.25 0.08
PS-DEA 21 2.80 303 0.20 0.07
PS-HM 29 - 303 0.15 -
CMPS 28 - 303 0.16 -
Absorption
MEA (30%) - 313 - 0.47
Bull. Korean Chem. Soc.
2013, 34: 783
DEA (30%) - 313 - 0.50
TEA (30%) - 313 - 0.27
DEA /MDEA
(80:20)
- 313 - 0.61
Ind. Eng. Chem. Res.,
2013, 3: 12-23

Adsorbent
Temp
(K)
ΔH
(kj/mol)
K0
(mol/kg/atm) ×107
Reference
αCO2-CH4 αCO2-N2 αCH4-N2 CO2 CH4 N2 CO2 CH4 N2
PS-BIMP 308 17.1 83.3 4.9 38.1 26.3 17.9 2.0 12.3 67.2
PS-MP 308 15.9 69.1 4.3 37.4 27.9 20.8 2.0 5.6 20.7
PS-Imidazole 308 12.8 53.9 4.2 37.6 29.3 18.1 1.4 2.9 52.1
PS-CA 308 12.1 48.1 3.9 38.8 25.4 18.2 0.7 12.4 51.3
PS-Pyrrole 308 45.1 12.0 3.8 37.4 26.4 20.2 1.2 7.8 22.2
PS-Piperazine 308 10.4 43.1 4.1 38.1 29.3 15.6 0.6 2.0 102.0 Present work
PS-Piperdine 308 10.3 41.4 4.0 37.6 25.7 20.3 0.7 8.1 16.3
PS-DMA 308 9.0 30.6 3.4 37.2 29.4 21.1 0.7 1.5 11.3
PS-DEA 308 6.9 24.9 3.6 33.9 29.1 17.8 1.7 1.5 36.2
PS-HM 308 7.1 26.1 3.4 33.4 28.0 21.6 1.9 2.2 7.4
CMPS 308 7.6 25.9 3.4 33.7 28.1 17.5 1.6 2.0 34.6
β-Zeolite
(40%MEA)
303 7.7 25.7 3.3 - - - - - -
J. Nat. Gas Chem.,
2009, 18: 167
MOF-5 298 15.5 17.5 1.1 - - - - - - Environ. Sci. Technol.,
2010,44: 1820MOF-117 298 4.4 17.7 4.0 - - - - - -
ZSM-5 313 1.7 5.4 3.3 - - - - - -
Sep. Purif. Technol.,
2003,33: 199
BILP 1 298 7.0 36.0 - - - - - -
- Chem. Mater. 23
(2011) 1650-1653.
MPI 3 273 10.0 41.0 - - - - - - -
Macromolecules 46
(2013) 3058-3066.
Comparison of Equilibrium separation Factor with Literature

Summary
 Heterocyclic ligand functionalized polystyrene showed enhanced equilibrium capacity and
separation factor over aliphatic ligand functionalized adsorbents due to presence of steric
hindrance in the latter.
 Amongst heterocyclic ligand functionalized adsorbents planar unsaturated ligand functionalized
adsorbents showed higher equilibrium uptake and selectivity for CO2 due to strong Lewis acid-
Lewis base interaction and weak intermolecular hydrogen bonding when compared to the saturated
heterocyclic ligand functionalized polystyrene.
 The six member pyridine based ‘BIMP’ functionalized polystyrene adsorbent having multiple
interaction sites for CO2 showed best equilibrium adsorption capacity and separation factor for
CO2/N2 and CO2/CH4 system over other adsorbents. The deficiency of electronic charge on ‘N’ atom
of citrazinic acid due to the presence of proximal phenolic group leads to its weaker interaction
with CO2 as compared to PS-BIMP, PS-MP and PS-Imidazole.
 Lewis-acid-Lewis base interaction of CO2 with CO2-phile is more dominating over weak
intermolecular ‘H’ bonding of ‘O’ atom of CO2 with proton attached to a group (eg. –OH) or carbon
at ‘α’ positions of electron donating CO2-phile.
 Presence of covalently attached tertiary ‘N’ atom ensures strong CO2-pilicity with regeneration of
adsorbents was achieved by pressure swing and overcomes the limitation of lack of stability over
repeated cycles.

PhD work

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