Journal of Environmental Treatment Techniques
2018, Volume 6, Issue 4, Pages: 74-80
J. Environ. Treat. Tech.
ISSN: 2309-1185
Journal weblink: http://www.jett.dormaj.com
Pilot-Scale Evaluation of CO2 Loading Capacity
in AMP Aqueous Solution beside the Improvers
HMDA-NH3 under a Series of Operational
Conditions
Amin Ale-Ebrahim Dehkordi1, Alireza Jahangiri*2 Amirreza Talaiekhozani3 A.Heidari
Semiromi4
1- Chemical Engineering Department, Jami Institute of Technology, Isfahan, Iran
2- Faculty of Engineering, Shahrekord University, Shahrekord, Iran
3- Department of Civil Engineering, Jami Institute of Technology, Isfahan, Iran
4-Chemical Engineering Department, Jami Institute of Technology, Isfahan, Iran
Received: 09/08/2018
Accepted: 01/12/2018
Published: 30/12/2018
Abstract
Nowadays, carbon dioxide removal has to be ingeniously managed because of its environmental and health effects. CO2 as a
heat-trapping greenhouse gas is pumped into the atmosphere through anthropogenic activities. This specific characteristic of CO2
gas not only adversely impacts the environment but also imposes noxious effects on human life. In spite of all the various and
potential scientific technics for CO2 removal, gas absorption using alkanolamines solvents has played a significant role in
industries in recent decades. In the present research, the equilibrium set up for measuring CO2 solubility in aqueous solvents was
assembled. CO2 loading data in aqueous Amp and Amp (3M) activated with HMDA and NH3 were assessed under the influence
of various operational conditions of CO2 partial pressures (8.44, 25.33, and 42.22kPa), temperatures (303, 313, and 323K) and
solvent concentrations of (0.5, 1.5 and 3M) for pure AMP and (0.4, 0.8 and 1.2M) for HMDA-NH3. The result showed that CO2
loading of AMP activated HMDA-NH3 increases with decreasing system temperature and increasing CO2 partial pressure.
Furthermore adding the HMDA solvent into the system increased CO2 loading before it followed a slight decrease while adding
NH3 decreased the amount. Concerning efficiency enhancement, it was comprehended that, HMDA could be considered among
promising improvers while NH3 as an additive beside AMP or as a based solvent, perform well in CO2 absorption process only
under specific operational condition.
Keywords: CO2 solubility, AMP, Ammonia (NH3), Loading
1 Introduction1
m [2]. To find a solution to this severe environmental
concern and to reduce the amplified greenhouse effects,
The anthropogenic increase of greenhouse gases
concentration in the atmosphere is stated to be the root
several CO2 removal methods have been designed after
cause of global warming. Among these greenhouse gases,
tremendous amounts of laboratory works. Some of them
include chemical absorption, physical absorption,
CO2 is believed to be highly responsible contributing to this
issue. The accumulation of CO2 in the air stems from
refrigerating methods, membrane separation and biological
diverse sources such as steel plants, cement industry and
absorption. However gas absorption using aqueous
alkanolamine solutions as a mature well-established
coal-fired power plants [1]. It is estimated that, if these
large emitters continue to release CO2 up into the
technology has proved both efficacious and viable among
others. Some of the most sought-after solutions in this
atmosphere, by the year 2100 the atmosphere may will
have loaded up to 570 ppm CO2. This will then increase the
category which have been exercised by many industry are
mean global temperature by 1.9 C and the sea level by 3.8
monoethanolamine (MEA), diethanoleamine (DEA), and
methyldiethanolamine
(MDEA). Owing to a recent
advancement in gas treating technology, a sterically
Corresponding author: Alireza Jahangiri, Tel.:
hindered amine 2-amino-2-methyl-1-propanol (AMP) has
989192672218; fax:
98
3814424438; E-mail address:
been proposed as a different class of chemical absorbent
jahangiri@eng.sku.ac.ir.
[3].
74
Journal of Environmental Treatment Techniques
2018, Volume 6, Issue 4, Pages: 74-80
Due to several supremacies in absorption capacity,
of AMP
[8]. NH3 as an additive has several major
absorption rate, selectivity, degradation resistance and
dominances over amine solutions such as high CO2
regeneration energy over conventional alkanolamines it has
removal capacity, no degradation, less corrosion, low heat
been called a commercially attractive solvent
[4].
requirement for regeneration and the potential of capturing
Preliminary work on hindered amine solution
was
CO2, SO2 and NOx simultaneously [1]. In this regard,
conducted by A.K. Chakraborty et.al. Also pahlavanzadeh
experiments were carried out with different molar
and jahangiri were the priors to undertook the similar
compositions of AMP (.5, 1.5 and 3 M), AMP+HMDA
experiment with the introduced CO2 absorption set up
(3+.4, 3+.8 and 3+1.2M) and AMP+NH3 (3+1, 3+2 and
which showed good results [5]. Another study with AMP
3+3M) at three different temperatures of (303, 313, and
solvent was conducted by Anoar Ali Khan et.al to prove
323K) and CO2 partial pressures of
(8.44,
25.33, and
high loading capacity of this hindered amine
[1].
42.22Kpa). The loading capacities of CO2 in each blends of
Concerning efficiency enhancement, many researchers
AMP, AMP/NH3 and AMP/HMDA were calculated under
made a start on the utilization of blends of alkanolamines,
the mentioned operational conditions and the data were all
or an amine based improved solution in varying
registered.
concentration. They believed to produce absorbent with
intensified absorption characteristics [4]. In other word, by
2 Materials and Methods
this method it could bring together the advantages of each
In order to carry out the experiments, AMP, HMDA
amine to facilitate CO2 absorption process. For instance a
and NH3 solvents were purchased with purity of 95%, 99%
mixture of primary (MEA) and tertiary amine (MDEA)
and 25% respectively, supplied by Merck Company and a
could benefit from both a high absorption rate of MEA and
certain amount of distilled water for preparing aqueous
a high equilibrium capacity of MDEA [6]. In this field,
solution. CO2-N2 gas was prepared by SEPAHAN,
there exist several study to show the increasing interest in
industrial and medical gasses production, Company which
performing CO2 absorption experiment using amine
is located in ISFAHAN
mixtures. As an example Yuli Artanto et.al investigated
Laboratory Setup: In order to conduct the CO2 absorption
CO2 absorption in aqueous mixture of AMP and piperazine
process, equilibrium set up for measuring CO2 solubility in
(PZ) which showed good results compared to conventional
aqueous solvents was assembled which is illustrated in Fig.
MEA [7]. Won-Joon Choi et.al investigated CO2 absorption
1. This set up have several advantages over the
into aqueous AMP/HMDA and AMP/MDEA to show the
conventional static and flow apparatus which have been
high CO2 loading capacity and high absorption rate of
applied for several years to measure CO2 solubility data.
HMDA and MDEA additives [6].
The most important feature is the continuous contact of
The present research focuses on the use of amine blends
both phases during the experiment which practically occurs
which takes advantages of a hindered amine named AMP
in industrial processes. Since you could have precise data
with a higher equilibrium CO2 loading capacity in compare
for industrial designing.
to conventional amines. Aqueous HMDA and NH3 were
also used beside to compensate for the low absorption rate
Figure 1: The apparatus for measuring the solubility of gases in liquid (a:Spiral tube, b:Scalling burette, c:Monometre, d:Water
bath, e:Mercury Jack, f:Cell, g:Unloaded Solvent Container, h: Circulating Pump, i: CO2 Capsule, J:Loaded Solvent Collector,
K:H2O injector)
75
Journal of Environmental Treatment Techniques
2018, Volume 6, Issue 4, Pages: 74-80
The basic elements of the set up are as follows:
V
Equilibrium cell: It is designed to make an
n
(2)
equilibrium environment in which the equilibrium
solubility of CO2 in aqueous solvent solution could be
investigated. The water which enters the equilibrium
Determining the number of Solvent moles with the
cell adjust the temperature to begin the experiments.
volume, density and molecular mass of the solvent, the
Spiral tube: There exist number of turns which is
number of solvent moles consumed is calculated from the
constant. In these turns the liquid and vapor phase
following equation:
come into contacts with each other to begin absorption
process. The solute and the solvent decide the
Vd
parameters such as number of turns, the slope and the
n
(3)
diameter of the tube. While the solubility of the gas
M
w
increases, the number turns should be increased and
the slope should be decreased to guarantee the
In this regard, V is the solvent volume in milliliters, d is
equilibrium condition between the solvent and the
the solvent density in grams per ml, and MW is the solvent
solute at the end of the spiral tube.
molecular mass in grams per mole. The number of moles
Scaling Burette: A scaling burette is a requisite
consumed from each of the solvents is obtained by the
device in order to estimate the volume of the dissolved
following equation:
gas into the solvent and also to maintain the gas in
the set up. This burette is connected to the spiral tube
at the top and to an internal valve at the bottom. The
Vd
n
(4)
valve is in connection with a CO2 capsule and a
t
M
mercury vessel. The mercury vessel is located on a
w
moving platform so as to adjust the level of the
solution in the monometer.
That nt is the number of total molecules consumed for
Manometer: A manometer is constructed at the
solvent mixtures, in which:
bottom of the spiral tube. It is needed to show the
pressure disagreement in the set up. The manometer is
n
joint to the spiral tube from one end and is opened to
d
x
d
(5)
i
i
the atmosphere from the other end.
i
Water bath: A water bath is applied in the process in
n
order to supply the water to the equilibrium cell at an
M
x
(M
)
(6)
adjusted temperature. This will provide for the
w
i
w
i
temperature at which the experiments are considered
i
to be performed.
Circulating pump: This device is used to circulate
In these equations, xi, di and (MW)i are the solvent (i)
the water which is supplied from the bath into and out
mole fraction in the composition, the solvent (i) density,
of the equilibrium cell.
and the molecular mass of the solvent (i). The following
Solvent container: Solvent container is used to inject
equation is used to calculate the mole of each solvent
the certain amount of solvent into the system at a
consumed:
constant rate.
CO2
loading calculations: To obtain CO2 loading, tests are
n
c n
(7)
needed to measure the amount of CO2 gas dissolved in a
i
i
t
certain amount of solvent. In each experiment, the amount
of CO2 dissolved during the test is obtained by reading on
By calculating the amount of CO2 moles and the
the burette. Then, using a proper equation of state, with
amount of solvent moles according to equations above, the
having the pressure and temperature of the experiment, the
amount of α which stands for CO2 loading could be
volume of the gas is converted to the number of dissolved
obtained by the following equation:
moles. Because the total pressure at which the set up works
is approximately 1 atmosphere, the ideal gas equation of
mol
CO
2
state is used. Molar volume of the gas could be obtained
(8)
exp
from equation 1.
mol
solvent
P  R T
(1)
Laboratory data related to CO2 loading in AMP + H2O
+ CO2 system: In Table 1, CO2 loadings are calculated
After calculating the molar volume of the gas dissolved
according to equation. The calculations were performed
in the test conditions, given the fact that during the test the
under different operational conditions in AMP
volume of the gas is also determined based on the change
concentrations of (.5, 1.5 and 3M), temperature (303, 313,
in the height of the surface of the mercury, the amount of
and 323K) and CO2 partial pressure
(8.44,
25.33, and
CO2 moles can be obtained according to equation 2.
42.22kPa). According to the data which are presented in
table 1, Figure 1 displays CO2 loading capacity of pure
AMP under the mentioned operational conditions.
76
Journal of Environmental Treatment Techniques
2018, Volume 6, Issue 4, Pages: 74-80
Laboratory data related to CO2 loading in AMP + H2O
(8.44, 25.33, and 42.22kPa). According to the data which
+ CO2 + HMDA system: In Table 2, CO2 loadings are
are presented in table 2, Figure 2 displays the effects of
calculated according to equation. The calculations were
HMDA additive into AMP (3M) under
the
mentioned
performed under different operational conditions in
operational conditions.
AMP+HMDA concentrations of (3+.4, 3+1.8 and 3+1.2),
temperature (303, 313, and 323K) and CO2 partial pressure
Table 1: CO2 loading in AMP+H2O+CO2 system
AMP Concentration
Temp
M
K
Exp
P
8.44
kPa
P
25.33kPa
P
42.22
kPa
CO
2
CO
2
CO
2
AMP (0.5M)
303
0.0207
0.1243
0.3107
AMP (0.5M)
313
0.0160
0.0722
0.2005
AMP (0.5M)
323
0.0078
0.0466
0.1166
AMP (1.5M)
303
0.0096
0.0495
0.1581
AMP (1.5M)
313
0.0080
0.0399
0.1261
AMP (1.5M)
323
0.0052
0.0232
0.0903
AMP (3M)
303
0.0062
0.0329
0.0960
AMP (3M)
313
0.0040
0.0279
0.0797
AMP (3M)
323
0.0026
0.0212
0.0643
8.44
25.33
42.22
CO2 Partial Pressures (kPa)
0.35
0.3107
0.3
0.25
0.2
0.2005
0.1581
0.15
0.1243
0.1261
0.1166
0.1
0.096
0.0903
0.0722
0.0797
0.0643
0.05
0.0466
0.0495
0.0399
0.0329
0.0207
0.0232
0.0279
0.0212
0.016
0.0078
0.0096
0.008
0
0.0052
0.0062
0.004
0.0026
303
313
323
303
313
323
303
313
323
0.5
0.5
0.5
1.5
1.5
1.5
3
3
3
AMP Concentrations (M)-Temperatuares (K)
Figure 1: The influence of operational conditions on CO2 loading in different AMP Concentrations of (0.5, 1 and 3M)
Table 2: CO2 loading in AMP+HMDA+H2O+CO2 system
AMP Concentration
Temp
Exp
M
K
P
8.44
kPa
P
25.33kPa
P
42.22
kPa
CO
2
CO
2
CO
2
AMP(3M)+HMDA(0.4M)
303
0.011
0.052
0.0105
AMP(3M)+HMDA(0.4M)
313
0.009
0.042
0.096
AMP(3M)+HMDA(0.4M)
323
0.007
0.037
0.079
AMP(3M)+HMDA(0.8M)
303
0.001
0.052
0.099
AMP(3M)+HMDA(0.8M)
313
0.009
0.044
0.088
AMP(3M)+HMDA(0.8M)
323
0.007
0.039
0.073
AMP(3M)+HMDA(1.2M)
303
0.010
0.048
0.099
AMP(3M)+HMDA(1.2M)
313
0.009
0.041
0.089
AMP(3M)+HMDA(1.2M)
323
0.007
0.037
0.073
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Journal of Environmental Treatment Techniques
2018, Volume 6, Issue 4, Pages: 74-80
Laboratory data related to CO2 loading in AMP+NH3 +
reason, CO2 loading decreases with increase in
H2O + CO2 system: In Table
3, CO2 loadings are
concentration, which has been observed in previous
calculated according to equation. The calculations were
researches conducted by pure AMP to confirm the accuracy
performed under different operational conditions in
of the matter[5]. According to Figure 2 HMDA additive
AMP+NH3 concentrations of
(3+1,
3+2 and
3+3M),
into AMP
(3M) made an upward trend toward an
temperature (303, 313, and 323K) and CO2 partial pressure
enhancement in CO2 loading capacity especially at higher
(8.44, 25.33, and 42.22kPa). According to the data which
CO2 partial pressures, however it was applied in low
are presented in table 3, Figure 3 displays the effects of
concentrations. For aqueous NH3 According to Figure 3, it
NH3 additive into AMP
(3M) under the mentioned
was found that, no improvement has obtained during the
operational conditions.
absorption process while NH3 was added to AMP system
under the same operational conditions. In order to justify
3 Results and Discussion
the behavior of ammonia solvent, Several Previous works
Experiments were carried out under the mentioned
on CO2 absorption using aqueous ammonia were studied. It
operational conditions. According to the Figures 1, 2, and
was understood that, aqueous ammonia in CO2 absorption
3, it was comprehended that for pure AMP, AMP+NH3 and
process has its best performance while it is applied in
AMP+HMDA, CO2 loading increased with a reduction in
temperatures below 10C. In a case where the temperature
exceeds, Figure 3, ammonia evaporation may occur as a
temperature and an increase in CO2 partial pressures. By
increasing AMP concentration, CO2 loading decreased. In
result which leads to solvent loss during the experiments.
practice, during the absorption process with pure AMP, the
Furthermore, In order to cope with solvent loss during the
absorption process, some researchers have recommended
increase in CO2 mole numbers in the solvent is not as well
as the increase in AMP solvent moles when increasing the
the use of metal additives like Zn, Cu, Ni, and Me into the
concentration. According to equation 8, the denominator
aqueous ammonia [9, 10].
increase is much more than the numerator increase. For this
8.44
25.33
42.22
CO2 Partial Pressures (kPa)
0.12
0.1
0.099
0.099
0.096
0.096
0.088
0.089
0.08
0.0797
0.079
0.073
0.073
0.0643
0.06
0.052
0.052
0.048
0.04
0.042
0.044
0.041
0.037
0.039
0.037
0.0329
0.0279
0.02
0.0212
0.0105
0.009
0.009
0.01
0.009
0.007
0.007
0.007
0
0.0062 0.004 0.0026
0.001
303
313
323
303
313
323
303
313
323
303
313
323
0
0
0
0.4
0.4
0.4
0.8
0.8
0.8
1.2
1.2
1.2
AMP+HMDA Concentrations (M)-Temperatures (K)
Figure 2: The influence of adding the improver (HMDA) in concentrations of (0.4, 0.8 and 1.2M) into AMP (3M) under variable operational
conditions
Table 3: CO2 loading in AMP+NH3+H2O+CO2 system
AMP Concentration
Temp
Exp
M
K
P
8.44
kPa
P
25.33kPa
P
42.22
kPa
CO
2
CO
2
CO
2
AMP(3M)+NH3(0.4M)
303
0.0010
0.0209
0.0499
AMP(3M)+NH3(0.4M)
313
0.0007
0.0181
0.0435
AMP(3M)+NH3(0.4M)
323
0.0002
0.0161
0.0398
AMP(3M)+NH3(0.8M)
303
0.0010
0.0150
0.0351
AMP(3M)+NH3(0.8M)
313
0.0006
0.0131
0.0307
AMP(3M)+NH3(0.8M)
323
0.0003
0.0117
0.0282
AMP(3M)+NH3(1.2M)
303
0.0010
0.0120
0.0291
AMP(3M)+NH3(1.2M)
313
0.0007
0.0105
0.0263
AMP(3M)+NH3(1.2M)
323
0.0003
0.0094
0.0237
78
Journal of Environmental Treatment Techniques
2018, Volume 6, Issue 4, Pages: 74-80
8.44
25.33
42.22
CO2 Partial Pressures (kPa)
0.1
0.09
0.09
0.08
0.079
0.07
0.064
0.06
0.05
0.049
0.043
0.04
0.039
0.035
0.03
0.032
0.027
0.03
0.028
0.029
0.026
0.023
0.02
0.021
0.02
0.018
0.016
0.015
0.01
0.013
0.011
0.012
0.01
0.009
0.006
0.004
0
0.002
0.001
0.0007
0.0002
0.001
0.0006
0.0003
0.001
0.0007
0.0003
303
313
323
303
313
323
303
313
323
303
313
323
0
0
0
0.4
0.4
0.4
0.8
0.8
0.8
1.2
1.2
1.2
AMP+NH3 Concentrations (M)-Temperatures (K)
Figure 3: The influence of adding the improver (NH3) in concentrations of (0.4, 0.8 and 1.2M) into AMP (3M) under variable
operational conditions
42.22
42.22
CO2 partial pressure (kPa)
303
313
323
303
313
323
303
313
323
303
313
323
0
0
0
0.4
0.4
0.4
0.8
0.8
0.8
1.2
1.2
1.2
AMP+HMDA
AMP (3M) ACTIVATED NH3-HMDA
AMP+NH3
Figure 4: Experimental CO2 loading of the mixed AMP+HMDA in comparison with AMP+NH3
4 Conclusion
consideration for CO2 loading calculation which caused a
In the present research CO2 absorption by pure AMP
drop in the amount.
and AMP activated NH3-HMDA was studied under various
operational conditions. HMDA additive increased CO2
References
loading capacity of pure AMP while adding aqueous NH3
[1] A.A. Khan, G.N. Halder, A.K. Saha, Experimental
to AMP did nothing to enhance the amount. In fact
investigation of sorption characteristics of capturing
inappropriate selection of the operational temperature range
carbon dioxide into piperazine activated aqueous
2-
higher than the optimum amount, led to ammonia loss
amino-2-methyl-1-propanol solution in a packed
during the CO2 absorption process. That meant that no NH3
column, International Journal of Greenhouse Gas
was introduced into the system while it had been taken into
Control, 44 (2016) 217-226.
79
Journal of Environmental Treatment Techniques
2018, Volume 6, Issue 4, Pages: 74-80
[2] A. Uma Maheswari, K. Palanivelu, Absorption of
absorption into aqueous AMP/HMDA, AMP/MDEA,
carbon dioxide in alkanolamine and vegetable oil
and AMP/piperazine solutions, Green Chemistry,
9
mixture and isolation of 2-amino-2-methyl-1-propanol
(2007) 594-598.
carbamate, Journal of CO2 Utilization, 6 (2014) 45-52.
[7] Y. Artanto, J. Jansen, P. Pearson, G. Puxty, A. Cottrell,
[3] A. Jahangiri, H. Pahlavanzadeh, A. Mohammadi, The
E. Meuleman, P. Feron, Pilot-scale evaluation of
modeling of CO2 removal from a gas mixture by 2-
AMP/PZ to capture CO 2 from flue gas of an Australian
amino-2-methyl-1-propanol (AMP) using the modified
brown coal-fired power station, International journal of
Kent Eisenberg model, Petroleum Science and
Greenhouse Gas control, 20 (2014) 189-195.
Technology, 32 (2014) 1104-1113.
[8] S.-B. Jeon, H.-D. Lee, M.-K. Kang, J.-H. Cho, J.-B.
[4] W.-J. Choi, B.-M. Min, B.-H. Shon, J.-B. Seo, K.-J. Oh,
Seo, K.-J. Oh, Effect of adding ammonia to amine
Characteristics of absorption/regeneration of CO 2-SO
solutions for CO
2 capture and mass transfer
2 binary systems into aqueous AMP+ ammonia
performance: AMP-NH 3 and MDEA-NH 3, Journal of
solutions, Journal of Industrial and Engineering
the Taiwan Institute of Chemical Engineers, 44 (2013)
Chemistry, 15 (2009) 635-640.
1003-1009.
[5] H. Pahlavanzadeh, S. Nourani, M. Saber, Experimental
[9] K. Li, H. Yu, M. Tade, P. Feron, Theoretical and
analysis and modeling of CO 2 solubility in AMP (2-
experimental study of NH 3 suppression by addition of
amino-2-methyl-1-propanol) at low CO
2 partial
Me (II) ions (Ni, Cu and Zn) in an ammonia-based CO 2
pressure using the models of Deshmukh-Mather and the
capture process, International Journal of Greenhouse
artificial neural network, The Journal of Chemical
Gas Control, 24 (2014) 54-63.
Thermodynamics, 43 (2011) 1775-1783.
[10] N. Dave, T. Do, G. Puxty, R. Rowland, P. Feron, M.
[6] W.-J. Choi, K.-C. Cho, S.-S. Lee, J.-G. Shim, H.-R.
Attalla, CO2 capture by aqueous amines and aqueous
Hwang, S.-W. Park, K.-J. Oh, Removal of carbon
ammonia-A Comparison, Energy Procedia, 1 (2009)
dioxide by absorption into blended amines: kinetics of
949-954.
80