1
Solvent Development
for CO2 Capture
Ugochukwu E. Aronu and Hallvard F. Svendsen
Norwegian University of Science and Technology (NTNU)
Trondheim, NORWAY
J, 2008 U
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Outline
• Research Plan Overview
• CO2 Capture Amine Solvent Review
• Structure – pKa Relationship
• VLE Experiment
• Summary
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Research Plan Overview

Review of CO2 capture solvents
-Properties of an ideal solvent
-Suggested/Future amine solvents

Screening Tests
- Amine systems will be screened for absorption capacity and absorption rate

VLE Experiments
-VLE experiment on selected system
-Thermodynamic model of VLE results

Kinetics Experiments
- Rate determination
- Kinetics model

Physicochemical Properties Determination
-pKa, Solubility, Viscousity, Activity Coefficient, Density

Simulations-HSYS
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Objective
Objective of this project is to develop solvent(s) that
will be able to meet considerably the present and/or
future requirements of an ideal solvent for carbon
dioxde capture.
Some of the key requirements of the solvent(s) include:







High absorption capacity
High absorption rate
Low regeneration energy
Chemically stable
Non-corrosive
Cheap
Environmentally friendly
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CO2 Capture Solvents Review
• Ideal Solvent Properties of Interest
Here we look at the desired properties of an ideal solvent and how
such property is related to CO2 capture process
- Dissociation Constant (pKa)
- Solubility
- Degradation
- Foaming
- Reaction Kinetics
- Toxicity/Environmental properties
• Solvent Collection
– Commercial Solvent
– Single Solvent
– Blended Solvent
- Heat of reaction
- Molecular weight
- Corrosion
- Vapour Pressure
- Cost
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Commercial Amine Processes & Solvents
Amine Process/Solvent
Developer
Solvent Composition
Cansolv® CO2 capture System
(Absorbent DC 101TM)
Cansolv Technologies Inc.
Tertiary amine and promoter
mixture
Flour Daniel Econamine FGSM
process
Dow Chemical and Union
Carbide
30wt% MEA with inhibitor
Kansai-Mitsubishi proprietary
Carbon Dioxide Recovery
Process (KM-CDR) KS-1
Mitsubishi Heavy Industries
(MHI) Ltd and Kansai Electric
Power Co., Ltd
Hindered amine and promoter
mixture
BASF activated
methyldiethanolamine (aMDEA)
BASF
MDEA mixture with accelerator,
Piperazine
Kerr-McGee/ABB Lummus Crest
Technology
Kerr-McGee
15-20wt% MEA without
inhibitors
UCARSOLTM AP 800 Series
Dow Chemical Company
Accelerated MDEA
(MDEA/Piperazine mixture)
ADIP-X Technology
Shell Global Solution
Accelerated MDEA
(MDEA/Piperazine mixture)
Just CatchTM
Aker Kvaerner
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Some Single Amine Solvents
Name
Monoethanolamine
2-Ethylaminoethanol
Monomethylethanolamine
Methyldiethanolamine
2-Butylaminoethanol
N-Aminoethylethanolamine
Piperazine
Ammonia
Methylamine
Ethylamine
Dimethylamine
Trimethylamine
Piperidine
Morpholine
Pyrrolidine
2,2,6,6-Tetramethyl-4-piperidinol
1-amino-2-propanol
2-amino-2-methylpropanol
Diethanolamine
Diisopropanolamine
N-n- butylethanolamine
Triethanolamine
1,3-propanediamine
2-(2-aminoethoxy)ethanol
2-(diethylamino)ethanol
2-(diisopropylamino)ethanol
2-(tert-butylamino)ethanol
Ethylenediamine
2-Amino-2-Methyl-1,3-Propanediol
CAS NO
141435
110736
109831
105599
111751
111411
110850
7664417
74895
75047
124403
75503
110894
110918
123751
2403885
78966
124685
111422
110974
36386739
102716
109762
929066
100378
96800
4620706
107153
115695
Name
CAS NO
2-Amino-2-Ethyl-1,3-Propanediol
N-(2-aminoethyl)-1,3-propanediamine
1,8-p -menthanediamine
2-piperidineethanol
2-amino-2-methylpropionic acid
2-amino-2-methyl-1-propanol
1-amino-1-cyclopentanecarboxylic acid
1-amino-1-cyclohexanecarboxylic acid
2-amino-2-phenylpropionic acid
Pipecolinic acid
2-amino-2-hdroxymethyl-1,3-propanediol
Tetraethylenepentamine
Bis(3-(dimethylamino)propyl)amine
Quinuclidine
2-Piperidinemethanol
2-Ethoxyethanol
tertiarybutylaminoethanol
Diethylmonoethanolamine
2-methyl-3-hydroxy piperidine
3-amino-3-methyl-1-butanol
2-amino-2-methyl-1-butanol
3-amino-3-methyl-2-pentanol
1-methyl-3-hydroxypiperidine
dimethylethanolamine
3-amino-1,2-propanediol
Diethylenetriamine
Triethylenetetramine
Tetraethylenepentamine
hexamethylenediamine
115708
13531527
80524
1484840
62577
124685
52528
21121379
565071
535751
77861
112572
6711484
100765
3433372
110805
4620706
100378
916083288
42514501
10196302
164656820
3554743
108010
616308
111400
112243
112572
124094
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Structure - pKa Relationship
Chain Length Effect
CAS
Registry
No.
Molecular
Formula
Monoethanolamine (MEA)
141-43-5
C2H7NO
3-amino-1-propanol (MPA)
156-87-6
C3H9NO
4-amino-1-butanol
13325-10-5
C4H11NO
5-amino-1-pentanol
2508-29-4
C5H13NO
Ethylenediamine (EDA)
107-15-3
C2H8N2
1,3-propanediamine
109-76-2
C3H10N2
1,4- diaminobutane
110-60-1
C4H12N2
1,5-Pentanediamine
462-94-2
C5H14N2
hexamethylenediamine (HMDA)
124-09-4
C6H16N2
Name
Structural Formula
Type
pKa**
pKa* 25 C Calculated
25oC
o
Primary Amines
Primary Alkanolamines
NH2
OH
NH2
OH
NH2
OH
NH2
OH
p
9.5
9.16±0.10
p
9.96
9.91±0.10
p
10.38
@ 20oC
10.32±0.10
p
10.46
@ 23oC
10.47±0.10
p(2)
pK1 = 9.92
pK2 = 6.86
9.89±0.10
p(2)
pK1 =10.55
10.43±0.10
pK2 = 8.88
p(2)
pK1 = 10.8
pK2 = 9.63
p(2)
pK1 = 10.05
10.85±0.10
pK2 = 10.93
p(2)
pK1 = 11.02
10.92±0.10
pK2 = 10.24
Primary Diamines
H2N
NH2
NH2
NH2
NH2
NH2
NH2
NH2
NH2
NH2
10.68±0.10
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Structure - pKa relationship
Multifunctional Amine Group Effect
Name
1,4-Butanediamine
CAS
Registry
No.
Molecular
Formula
110-60-1
C4H12N2
Structural Formula
Type
NH2
p(2)
pK1 = 10.8
pK2 = 9.63
10.68±0.10
p(2), s
pK1 = 9.94
pK2 = 9.13
pK3 = 4.34
10.16±0.10
NH2
Diethylenetriamine(DETA)
111-40-0
C4H13N3
NH
NH2
1,5-Pentanediamine
N-(2-aminoethyl)-1,3propanediamine (AEPDA)
462-94-2
C5H14N2
13531-52-7
C5H15N3
Hexamethylenediamine (HMDA)
124-09-4
C6H16N2
N-(3-aminopropyl)-1,3propanediamine
56-18-8
C6H17N3
Triethylenetetramine (TETA)
NH2
NH2
NH2
C6H18N4
pK1 = 10.05
10.85±0.10
pK2 = 10.93
p(2), s
NH
NH2
NH
NH2
p(2)
pK1 = 11.02
10.92±0.10
pK2 = 10.24
p(2), s
pK1 = 10.65
pK2 = 9.57 10.71±0.10
pK3 = 7.72
NH2
NH
NH
10.17±0.10
NH2
NH2
NH2
112-24-3
p(2)
NH2
pKa**
pKa* 25 C Calculated
25oC
o
NH2
p(2), s(2)
pK1 = 9.92
pK2 = 9.20
pK3 = 6.67
pK4 = 3.32
10.05±0.19
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Structure - pKa relationship
Alkyl Group Effect
CAS
Registry
No.
Molecular
Formula
Trimethylamine
75-50-3
C3H9N
Triethylamine
121-44-8
C6H15N
Name
Structural Formula
Type
pKa**
Calculated
pKa* 25 C
25oC
o
Tertiary amine
N
t
9.80
9.75±0.28
t
10.75
10.62±0.25
t
10.66
9.99±0.50
t
9.23
8.88±0.28
t
9.75
9.79±0.25
N
Tripropylamine
102-69-2
C9H21N
N
Tertiary alkanolamine
dimethylethanolamine (DMEA)
108-01-0
C4H11NO
N
OH
2-(diethylamino)ethanol (DEAE)
100-37-8
C6H15NO
N
OH
3-(diethylamino)-1-propanol
622-93-5
C7 H17NO
N
1-(diethylamino)-2-propanol
4402-32-8
t
10.13±0.25
t
10.27±0.25
OH
C7H17NO
N
OH
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Structure - pKa Relationship
Hydroxyl Group Effect-Primary Alkanolamine
CAS
Registry
No.
Molecular
Formula
2-amino-2-methylpropanol
(AMP)
124-68-5
C4H11NO
2-amino-1-butanol
96-20-8
Name
Structural Formula
Type
pKa**
Calculated
pKa* 25 C
25oC
o
Primary Alkanolamines
NH2
p,(SH)
9.72
9.20±0.25
OH
OH
C4H11NO
p
9.67 @ 20oC 9.27±0.10
p
9.62 @ 20oC 9.18±0.10
NH2
Monoisopropanolamine
(MIPA)
2-Amino-2-Methyl-1,3Propanediol (AMPD)
OH
78-96-6
C3H9NO
H2N
NH2
115-69-5
C4H11NO2
HO
OH
p,(SH)
8.80
8.90±0.29
p,(SH)
8.80
8.86±0.29
p,(SH)
8.07
7.78±0.29
HO
2-Amino-2-Ethyl-1,3Propanediol
(AEPD)
115-70-8
C5H13NO2
HO
NH2
NH2
2-amino-2-hdroxymethyl-1,3propanediol
(AHPD)
77-86-1
C4H11NO3
HO
OH
HO
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VG14
Safety Valve
VLE Apparatus
VP1
VP2
VG17
TI
N2 or CO2
VG7
P
T
Gas Pump 2
VG15
VG3
GS3
VG1
GS2
GS1
VG2
VG6
VG16
VG4
VG5
VG13
P
T
Cooler
VG8
Gas Pump 1
FT
VG9
CO2
Analyzer
Equilibrium Cell
LS2
CO2
LS1
Hygromete
r
Gear Pump
FI
VG12
Oil Bath
Amine solution
VG10
MF
C
2
P
T
VG11
MF
C
1
N2
TI
VL2
VL1
Feed Pump
Cooler
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VLE Test Result
VLE 30wt% MEA 40oC
100000.0
10000.0
PCO2(kPa)
1000.0
Loadingfresh
100.0
Jou, et. al (1995)
Loadingtitration
10.0
Sholeh
1.0
Shen and Li (1992)
0.1
0.0
0.0
0.0
0.2
0.4
0.6
Loading(molCO2/molMEA)
0.8
1.0
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Summary
• Several amines solvents have been suggested for CO2 Capture
• It appears there is relationship between amines structures and
their pKa value
• Effort is to explain this relationship using electron donation and
withdrawal through bonds and solvation effect
• To know the benefit that could be derived from this relationship
in CO2 capture process, particularly in solvent selection
• VLE Experiments continues
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Thank You