DESCRIPTION
Title of Invention: AQUEOUS SOLUTION WHICH EFFICIENTLY ABSORBS
AND RECOVERS CARBON DIOXIDE IN EXHAUST GAS, AND METHOD FOR
RECOVERING CARBON DIOXIDE USING SAME
5
Technical Field
[OOOl]
The present invention relates to an aqueous solution
for absorbing and recovering CO2 contained in a gas, and a method
10 for efficiently absorbing and recovering COz contained in a gas by
using the aqueous solution.
Background Art
[0002]
15 In recent years, frequently occurring climate changes
and natural disasters, which are seemingly attributable to global
warming, have had a significant impact on agricultural production,
the living environment, energy consumption, and the like. The
global warming is believed to be due to the increase in
20 greenhouse gases, typically COZ, in the atmosphere, resulting from
intensive human industrial activities. Therefore, there is an
urgent demand for a measure to lower the atmospheric
concentrations of COZ .
[0003]
2 5 Major sources of COZ include thermal power plants,
boilers of factories, kilns of cement factories using coal, heavy
oil, natural gas, or the like, as a fuel, blast furnaces of
ironworks where iron oxide is reduced with coke, and
transportation equipment, such as automobiles, marine vessels,
30 aircraft, and the like, using gasoline, heavy oil, light oil or
the like, as a fuel. Except for transportation equipment, these
sources of COz are fixed facilities, and are expected to be easily
adapted to implementation measures for reducing C02 emissions into
the atmosphere.
-2-
[0004]
A wide variety of methods for recovering C02 from gases
exhausted from the above-mentioned sources have been studied, and
several methods are known.
5 [0005]
For example, a method for absorbing C02 by bringing an
aqueous solution of an alkanolamine into contact with a C02-
containing gas in an absorption tower is well known. Examples of
known alkanolamines include monoethanolamine (hereinafter,
10 sometimes referred to as "MEA"), diethanolamine (DEA),
triethanolamine (TEA), methyldiethanolamine (MDEA),
diisopropanolamine (DIPA), and diglycolamine (DGA) . MEA is
typically used.
[0006]
15 However, primary amines, such as MEA, are highly
corrosive to device materials, and therefore the use of an
aqueous solution of such an alkanolamine as a solution for
absorbing C02 requires the use of expensive, corrosion-resistant
steel, or requires lowering the concentration of the amine in the
20 absorbing solution. Further, although absorbed C02 is typically
released and recovered in a regeneration tower by heating the
solution to a temperature of about 120°C, this method ends up
consuming a large amount of energy for recovery per unit weight
of C02 because the use of the above-stated alkanolamines is
25 unsatisfactory in terms of the amount of absorbed CO2 in an
absorption tower and the amount of released COz in a regeneration
tower.
[0007]
At the present time, where the reduction of C02
30 emissions and the saving of energy and natural resources are
being sought, a significant amount of energy consumption for the
absorption and recovery of COZ is an obstructive factor to the
practical use of the aforementioned technique. Thus, a technique
for separating and recovering COz with less energy is desired.
35 [0008]
As an example of prior art techniques for separating
and recovering CO2 by using less energy, Patent Document 1
discloses a method for removing COz from a combustion exhaust gas
by bringing an aqueous solution of a so-called hindered amine,
5 which has a steric hindrance of alkyl groups or the like around
the amino group, into contact with a combustion exhaust gas at
atmospheric pressure to allow the aqueous solution to absorb C02.
[0009]
In Patent Document 1, 2-methylaminoethanol (hereinafter,
10 sometimes referred to as MAE) and 2-ethylaminoethanol
(hereinafter, sometimes referred to as EAE) are described as a
hindered amine, and 30 rut% aqueous solutions of MAE and EAE are
used in the Examples. Other examples of hindered amines, although
not used in the Examples, include amines, such as 2-
15 (isopropylamino)ethanol (hereinafter, sometimes referred to as
IPAE) .
[OOlO]
Patent Documents 2 to 6 disclose absorbing solutions
containing N,N,N1,N'-tetramethyl-1,3-butanediamine, or N,N,N',Nt-
20 tetramethylhexane-l,6-diamine, and methods for removing COz by
using the absorbing solutions.
Citation List
Patent Documents
25 [OOll]
Patent Document 1: Japanese Patent No. 2871334
Patent Document 2: JP2009-529420A
Patent Document 3: JP2010-110749A
Patent Document 4: JP2010-188336A
30 Patent Document 5: JP2010-201422A
Patent Document 6: JP2011-528993A
Summary of Invention
Technical Problem
35 [0012]
As noted above, a C02-absorbing solution that
consumes a small amount of energy and has low corrosiveness has
been desired for the separation and recovery of C02.
[00131
5 Accordingly, an object of the present invention is
to provide an aqueous solution and a method for not only highly
efficiently absorbing COz in a gas but also highly efficiently
releasing CO2 to recover high-purity COz with low energy
consumption. Specifically, an object of the present invention is
10 to provide an aqueous solution useful for recovering high-purity
CO2 by efficiently absorbing and releasing C02, namely, with a
large amount of CO2 absorption and release per unit amount of the
aqueous solution, while requiring low energy for releasing C02,
and to provide a method for absorbing and recovering COz using the
15 aqueous solution.
Solution to Problem
[00141
The present inventors conducted extensive research on
20 absorbing solutions capable of efficiently absorbing and
releasing C02 to recover high-purity COz. Consequently, the
inventors found that an aqueous solution containing an amino
alcohol compound represented by Formula 1 and an amine compound
represented by Formula 2 absorbs and releases a large amount of
25 C02 while exhibiting an excellent absorption rate, thereby
significantly increasing the amount of C02 recovered per unit
amount of absorbing solution in one cycle of absorption and
release, and that the recovery of C02 with lower energy
consumption becomes possible. Accordingly, the inventors
30 completed the present invention.
[00151
Specifically, the present invention is defined by the
following Items 1 to 5.
[00161
35 Item 1. An aqueous solution for absorbing and recovering carbon
dioxide from a carbon dioxide-containing gas, the aqueous
solution comprising an amino alcohol compound represented by
Formula 1 and an amine compound represented by Formula 2,
[0017]
5 [Chem. 11
Formula 1
[0018]
wherein R represents an alkyl group having 1 to 5 carbon atoms,
and n represents 1 or 2,
10 [0019]
[Chem. 21
[00201
wherein X represents -NR1R2; Y represents -NR3R4; R1, R2, R3 and
15 R4 may be the same or different, and each represents an alkyl
group having 1 to 3 carbon atoms; and m represents an integer of
3 to 7.
[0021]
Item 2. The aqueous solution according to Item 1 wherein the
20 amino alcohol compound and the amine compound have a total
concentration of 20 to 80% by weight; the amino alcohol compound
has a concentration of 10 to 70% by weight; and the amine
compound has a concentration of 1 to 50% by weight.
[0022]
25 Item 3. The aqueous solution according to Item 2 wherein the
amino alcohol compound has a concentration of 30 to 60% by
weight; and the amine compound has a concentration of 1 to 40% by
weight.
[0023]
Item 4. The aqueous solution according to any one of Items 1 to 3
wherein R of the amino alcohol compound represents an alkyl group
having 2 to 4 carbon atoms; and m of the amine compound
5 represents an integer of 5 to 7.
[0024]
Item 5. A method for absorbing and recovering carbon dioxide, the
method comprising the steps of:
(1) bringing the aqueous solution according to
10 any one of Items 1 to 4 into contact with a carbon dioxidecontaining
gas to absorb carbon dioxide from the gas; and
(2) heating the aqueous solution obtained in
step (1) containing absorbed carbon dioxide therein to release
the carbon dioxide, thereby recovering the carbon dioxide.
15
Advantageous Effects of Invention
[0025]
The separation and recovery of C02 with the use of the
aqueous solution according to the present invention enables an
20 increase in the amount of CO2 recovered per cycle of C02
absorption and release, and requires less energy for separation
and recovery of C02 per unit weight of the aqueous solution,
thereby efficiently recovering high-purity COE with low energy
consumption. Furthermore, this leads to a decrease in the amount
25 of circulation flow throughout the absorption-release cycle,
thereby making it possible to downsize the absorption tower,
release tower, and other associated devices.
[0026]
MEA, which is widely used, is highly corrosive to
30 carbon steel, and is believed to become more corrosive
particularly at high concentrations. On the other hand, the
aqueous solution used in the present invention is less corrosive,
and is advantageous in that it does not require the use of
expensive, high-grade, corrosion-resistant steel.
Description of Embodiments
[0027]
The following describes the present invention in detail.
[00281
5 Aqueous Solution for Absorbing and Recovering Carbon Dioxide
The aqueous solution for absorbing and recovering C02
from a COz-containing gas according to the present invention
contains an amino alcohol compound represented by Formula 1 and
an amine compound represented by Formula 2,
10 [0029]
[Chem. 31
[0030]
wherein R represents an alkyl group having 1 to 5 carbon atoms,
15 and n represents 1 or 2,
[0031]
[Chem. 41
" W Y
Formula 2
[00321
20 wherein X represents -NRlR2; Y represents -NR3R4; R1, R2, R3 and
R4 may be the same or different, and each represents an alkyl
group having 1 to 3 carbon atoms; and m represents an integer of
3 to 7.
[0033]
2 5 The alkyl group having 1 to 5 carbon atoms may be
linear or branched, and examples thereof include methyl, ethyl,
n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, n-pentyl, and
isopentyl. Preferably, R is an alkyl group having 2 to 4 carbon
atoms, and examples thereof include ethyl, n-propyl, isopropyl,
n-butyl, and isobutyl, with isopropyl, n-butyl, and isobutyl
being more preferable.
[0034]
The alkyl group having 1 to 3 carbon atoms may be
5 linear or branched, and examples thereof include methyl, ethyl,
n-propyl, and isopropyl. Preferably, R1, R2, R3, and R4 are
methyl or ethyl.
[0035]
Preferably, m is 5 to 7, with 5 being more preferable.
10 [0036]
Examples of the amino alcohol compound represented by
Formula 1 include N-ethylethanolamine, N-n-propylethanolamine, Nisopropylethanolamine,
N-n-butylethanolamine, Nisobutylethanolamine,
3-ethylamino-1-propanol, 3-n-propylamino-l-
15 propanol, 3-isopropylamino-1-propanol, 3-n-butylamino-1-propanol,
and 3-isobutylamino-1-propanol. These can be used in industrial
applications.
[00371
Examples of the amine compound represented by Formula 2
20 include N,N,N',Nt-tetramethyl-l,4-butanediamine, N,N,N',N1-
tetramethyl-1,5-pentanediamine, N,N,N',N1-tetramethyl-1,6-
hexanediamine, N,N,N1,N'-tetramethyl-1,8-octanediamine,
N,N,N1,N'-tetraethyl-1,4-butanediamine, N,N,N',N1-tetraethyl-1,5-
pentanediamine, N,N,N',N1-tetraethyl-1,6-hexanediamine, and
25 N,N,N1,N'-tetraethyl-l,8-octanediamine. These can be used in
industrial applications.
[0038]
The amino alcohol compound represented by Formula 1 and
the amine compound represented by Formula 2 preferably have a
30 total concentration of 20 to 80% by weight; the amino alcohol
compound represented by Formula 1 preferably has a concentration
of 10 to 70% by weight; and the amine compound represented by
Formula 2 preferably has a concentration of 1 to 50% by weight.
The amino alcohol compound represented by Formula 1 more
35 preferably has a concentration of 30 to 60% by weight, and the
amine compound represented by Formula 2 more preferably has a
concentration of 1 to 40% by weight.
[00391
If desired, the aqueous solution according to the
5 present invention may contain a stabilizer (e.g., an antioxidant)
to ensure the chemical or physical stability of the aqueous
solution, or an inhibitor (e.g., a corrosion inhibitor) to
prevent the deterioration of the materials of devices and
equipment in which the aqueous solution of the present invention
10 isused.
[0040]
The amino alcohol compound represented by Formula 1 and
the amine compound represented by Formula 2 are commercially
available, or are produced by knorm methods.
15 [0041]
Examples of the C02-containing gas include: exhaust
gases from thermal power plants, boilers of factories, kilns of
cement factories using coal, heavy oil, natural gas or the like
as a fuel, blast furnaces of ironworks where iron oxide is
20 reduced with coke, converter furnaces of steel mills where carbon
in pig iron is combusted to produce steel, integrated coal
gasification combined cycle facilities, and the like; raw natural
gases; and reformed gases. The gases typically have a
concentration of C02 in the range of about 5 to 30 vol%, and
25 particularly about 6 to 25 ~01%. When the concentration of C02 is
within such a range, the effect of the present invention is
advantageously produced. The CO2-containing gas may contain, in
addition to C02, gases such as water vapor, CO, HzS, COS, SO2, NO2,
hydrogen, and the like.
30 [0042]
Method for Absorbing and Recovering Carbon Dioxide
The method for absorbing and recovering COz according
to the present invention includes the following steps:
(1) bringing the above-described aqueous solution into contact
35 with a CO2-containing gas to absorb COz from the gas; and
(2) heating the aqueous solution obtained in step (1) containing
absorbed COz therein to release and recover COz.
[00431
Step of Absorbing Carbon Dioxide
5 The method according to the present invention includes
the step of bringing the above-described aqueous solution into
contact with a CO2-containing gas to absorb COr from the gas. The
met.hod for bringing the aqueous solution of the present invention
into contact with a COZ-containing gas to absorb COz is not
10 particularly limited. Examples include a method comprising
bubbling a COZ-containing gas in the aqueous solution to absorb
C02, a method comprising mist-spraying the aqueous solution over a
COz-containing gas stream (misting or spraying method), or a
method comprising bringing the aqueous solution into
15 countercurrent contact with a COz-containing gas in an absorption
tower that contains a porcelain or metal mesh filler.
[00441
A COz-containing gas is absorbed into the aqueous
solution at a temperature typically in the range of from room
20 temperature to 60°C, preferably 50°C or less, and more preferably
in the range of about 20 to 45'C. The lower the temperature, the
larger the absorption amount. However, how far the temperature
should be lowered is determined in accordance with the gas
temperature of the exhaust gas, the heat recovery target, or the
25 like. Carbon dioxide is typically absorbed at atmospheric
pressure. Although it is possible to increase the pressure to a
higher level in order to improve the absorption capacity, it is
preferable to effect absorption at atmospheric pressure to
suppress the energy consumption required for compression.
30 [00451
The COz-containing gas is the same as the
aforementioned gas.
[00461
Step of Releasing Carbon Dioxide
35 The method according to the present invention includes
the step of heating the aqueous solution obtained in the step of
absorbing C02 to thereby release and recover CO2.
[00411
Examples of methods for recovering pure or high-
5 concentration C02 by releasing C02 from an aqueous solution
containing absorbed C02therein include a method comprising
heating and boiling the aqueous solution in a vessel as in
distillation, and a method comprising heating the aqueous
solution in a plate distillation column, spray tower, or release
10 tower containing a porcelain or metal mesh filler to increase the
liquid contact interface. CO2 is thereby liberated and released
from bicarbonate ions.
[00481
C02 is released at a solution temperature of typically
15 70°C or more, preferably 80°C or more, and more preferably about
90 to 120°C. The higher the temperature, the larger the
absorption amount; however, an increase in temperature results in
an increase in energy necessary for heating the absorbing
solution. Therefore, the temperature is determined in accordance
20 with the gas temperature during the process, the heat recovery
target, or the like. The amine aqueous solution from which C02
has been released is again sent to the C02-absorbing step to
recycle it. During this period, the heat applied in the C02-
releasing step is effectively used in the recycling process to
25 increase the temperature of an aqueous solution that is to be
sent to the CO2-releasing step through heat exchange, thereby
resulting in the reduction of energy consumption in the entire
recovery process.
[0049]
30 The thus recovered C02 has a purity of typically 99
vol% or more, which means that it is extremely pure and can be
used in the chemical industry or food industry. Further, the
recovered COz can also be stored underground for EOR (Enhanced Oil
Recovery) or CCS, which are presently being considered for
35 practical use.
Examples
[0050]
The following Examples describe the present invention
5 in detail. However, the present invention is not limited to the
Examples.
[0051]
Example 1
A glass-made gas washing bottle was immersed into a
10 constant temperature water bath whose liquid temperature was set
at 40°C. This bottle was filled with 50 g of an aqueous solution
containing 50 wt% of 2-(isopropylamino)ethanol (IPAE,
manufactured by Tokyo Chemical Industry Co., Ltd.) and 10 wt% of
N,N,N1,N ' -tetramethyl-l,6-hexanediamine (TMHA, manufactured by
15 Tokyo Chemical Industry Co., Ltd.). Into the aqueous solution, a
gas mixture of 20 vol% of carbon dioxide and 80 vol% of nitrogen
was introduced at a rate of 0.7 L/min at atmospheric pressure
through a glass filter having a pore size of 100 pm and a
diameter of 13 mm to disperse the gas in the form of bubbles and
20 effect absorption for 60 minutes.
[0052]
The COz concentration in the gas was continuously
measured at the inlet and outlet of the absorbing solution using
an infrared carbon dioxide meter (HORIBA GAS ANALYZER VA-3000),
25 and the amount of absorbed C02 was determined from the difference
in the flow amount of C02 between the inlet and the outlet. Where
necessary, the amount of inorganic carbon in the absorbing
solution was measured with a total organic carbon analyzer for
gas chromatography (SHIMADZU TOC-VCSH), and compared with the
30 value obtained by using the infrared carbon dioxide meter. The
saturated absorption amount is defined as the amount of COz
absorbed until the COz concentration at the outlet of the
absorbing solution became equal to that at the inlet. Because the
absorption rate varies depending on the absorption amount, the
35 absorption rate at the time point at which C02 was absorbed in an
amount equal to 1/2 of the saturated absorption amount was
measured and compared. Subsequently, the temperature of the
solution was increased to 70°C over a few minutes in the same gas
stream, and the amount of released C02 was measured for 60 minutes
5 under the same conditions.
[0053]
The quantity of heat generation was determined by
diffusing at 40°C a predetermined amount of C02 into one of the
reactors of two absorption devices of the same shape, each of
10 which was equipped with a stirrer, and measuring, during this
period, the difference in the quantity of generated heat between
the two reactors using a differential calorimeter (DRC Evolution
manufactured by SETARAM).
[0054]
15 Examples 2 to 5
Following the procedure of Example 1 and using an
aqueous solution containing IPAE and TMHA at the concentrations
shown in Table 1 in place of the aqueous solution containing 50
r.rt% of IPAE and 10 tit% of TMHA, the saturated absorption amount,
20 absorption rate, quantity of heat generation, and released amount
of C02 were measured.
LO0551
Example 6
Following the procedure of Example 1 and using an
25 aqueous solution containing 3-isopropylamino-1-propanol (IPAP)
and TMHA at the concentrations shown in Table 1 in place of the
aqueous solution containing 50 wt% of IPAE and 10 wt% of TMHA,
the saturated absorption amount, absorption rate, quantity of
heat generation, and released amount of COz were measured.
30 [00561
Examples 7 to 9
Following the procedure of Example 1 and using an
aqueous solution containing IPAP and TMHA at the concentrations
shown in Table 1 in place of the aqueous solution containing 50
35 wt% of IPAE and 10 tit% of TMHA, the saturated absorption amount,
absorption rate, and released amount of CO2 were measured.
[0057]
Examples 10 to 12
Following the procedure of Example 1 and using an
5 aqueous solution containing 2-ethylamino-1-ethanol (EAE) and TMHA
at the concentrations shown in Table 1 in place of the aqueous
solution containing 50 wt% of IPAE and 10 rqt% of TMHA, the
saturated absorption amount, absorption rate, and released amount
of CO2 were measured.
10 [0058]
EAE is readily available commercially and is
inexpensive as compared with IPAE; thus, EAE is advantageous in
terms of the cost of absorbing solutions. As is apparent from the
comparison with Comparative Examples 8 and 9, even when using EAE,
15 the addition of the amine compound according to the present
invention significantly increases the amount of C02 released,
which is a very important property of absorbing solutions.
[0059]
Examples 13 to 15
2 0 Folloriing the procedure of Example 1 and using an
aqueous solution containing IPAE and N,N,N',N1-tetramethyl-l,4-
butanediamine (TMBA, manufactured by Tokyo Chemical Industry Co.,
Ltd.) in place of the aqueous solution containing IPAE and TMHA,
the saturated absorption amount and released amount of CO* were
25 measured. The results revealed that the saturated absorption
amount and released amount of COz per unit amount of the absorbing
solution were improved as compared with the use of an aqueous
solution containing only IPAE.
[00601
30 Comparative Examples 1 to 3
Following the procedure of Example 1 and using aqueous
solutions individually containing 30, 55, and 60 wt% of IPAE only
in place of the aqueous solution containing 50 wt% of IPAE and 10
wt% of TMHA, the saturated absorption amount, absorption rate,
35 quantity of heat generation, and released amount of COZ were
measured.
[00611
Comparative Example 4
Folloruing the procedure of Example 1 and using an
5 aqueous solution containing 52 rut% of IPAE and 3 wt% of
piperazine (PZ) in place of the aqueous solution containing 50
wt% of IPAE and 10 !it% of TMHA, the saturated absorption amount,
absorption rate, quantity of heat generation, and released amount
of CO2 were measured.
10 [00621
Comparative Examples 5 and 6
Following the procedure of Example 1 and using aqueous
solutions individually containing 30 wt% and 50 wt% of TMHA in
place of the aqueous solution containing 50 wt% of IPAE and 10
15 wt% of TMHA, the saturated absorption amount, absorption rate,
quantity of heat generation, and released amount of C02 were
measured.
LO0631
Comparative Example 7
2 0 Following the procedure of Example 1 and using an
aqueous solution containing 30 \it% of IPAP in place of the
aqueous solution containing 50 rut% of IPAP and 10 wt% of TMHA,
the saturated absorption amount, and released amount of C02 were
measured.
25 [0064]
Comparative Examples 8 and 9
Following the procedure of Example 1 and using aqueous
solutions individually containing 30 wt% and 54 wt% of EAE in
place. of the aqueous solution containing 50 wt% of EAE and 10 wt%
30 of TMHA, the saturated absorption amount, and released amount of
COz were measured.
[0065]
Table 1 shows the results of Examples 1 to 15 and
Comparative Examples of 1 to 9. The symbol "%" used in Table 1
35 denotes "wt%."
Composition of Aqueous Solution
(by Weight)
CO, Absorption Performance
at 40°C
C02 Release
performance
[0067]
Results of Example 1
The saturated absorption amount of COz was 156 g per kg
of the aqueous solution at a temperature of 40°C. The released
5 amount of COz was 91 g per kg of the absorbing solution at a
temperature of 70°C. The recovered COz had a purity of 99.8%.
The results revealed that the saturated absorption amount and
released amount per unit amount of the absorbing solution were
significantly larger than those of Comparative Example 1. Thus,
10 the performance of the absorbing solution of the present
invention was recognized.
[0068]
Results of Comparative Examples 1 to 3
The absorption rate was high at a low concentration of
15 30 wt%; however, a significant decrease in the absorption rate
was observed at a concentration of 60 wt%. All of the solutions
of Comparative Examples 1 to 3 exhibited a lower saturated
absorption amount and released amount than those of Examples 1 to
5.
20 [0069]
Results of Comparative Example 4
Piperazine is known as a reaction activator for the
absorption of C02 by using an alkanolamine aqueous solution, and
exerts an improving effect on the saturated absorption amount and
25 absorption rate. The results shown in Table 1 reveal that the
solutions of Examples 1 to 5 are advantageous in terms of the
released amount.
[00701
Results of Comparative Examples 5 and 6
3 0 The aqueous solutions containing only TMHA did not
exert a sufficient effect on the released amount at a
concentration of 30 wt%. The absorption rate was considerably
decreased at a concentration of 50 wt%. The results shown in
Table 1 reveal that the solutions of the Examples were
35 advantageous.
[00711
Results of Comparative Example 7
The released amount was smaller than that of Examples 6
to 9.
5 [00721
Results of Comparative Examples 8 and 9
The solutions of Comparative Examples 8 and 9 both
exhibited smaller released amounts than those of Examples 10 to
12.
10 [0073]
Test Example 1
The aqueous solution of Example 1 was tested for
corrosion of an SS400 metal test piece. The test was conducted
using a Hastelloy autoclave under a COz-saturated atmosphere at
15 130°C for 48 hours. As a result, the corrosion caused by the
aqueous solution of Example 1 on the SS400 was total corrosion,
and the calculated corrosion rate was 0.13 mm/year. The results
revealed that the aqueous solution of Example 1 is slightly
corrosive.
2 0
-19-
CLAIMS
[Claim 11
An aqueous solution for absorbing and recovering carbon
5 dioxide from a carbon dioxide-containing gas, the aqueous
solution comprising an amino alcohol compound represented by
Formula 1 and an arnine compound represented by Formula 2,
[Chem. 11
Formula 1
R
10
wherein R represents an alkyl group having 1 to 5 carbon atoms,
and n represents 1 or 2,
[Chem. 21
" W Y
Formula 2
15
wherein X represents -NRlR2; Y represents -NR3R4; R l , R2, R3 and
R4 may be the same or different, and each represents an alkyl
group having 1 to 3 carbon atoms; and m represents an integer of
3 to 7.
2 0
[Claim 21
The aqueous solution according to Claim 1 wherein the
amino alcohol compound and the amine compound have a total
concentration of 20 to 80% by weight; the amino alcohol compound
25 has a concentration of 10 to 70% by weight; and the amine
compound has a concentration of 1 to 50% by weight.
The aqueous solution according to Claim 2 wherein the
amino alcohol compound has a concentration of 30 to 60% by
weight; and the amine compound has a concentration of 1 to 40% by
weight.
5
[Claim 41
The aqueous solution according to Claim 1 wherein R of
the amino alcohol compound represents an alkyl group having 2 to
4 carbon atoms; and m of the amine compound represents an integer
10 of 5 to 7.
[Claim 51
A method for absorbing and recovering carbon dioxide,
the method comprising the steps of:
15 (1) bringing the aqueous solution according to
Claim 1 into contact with a carbon dioxide-containing gas to
absorb carbon dioxide from the gas; and
(2) heating the aqueous solution obtained in
step (1) containing absorbed carbon dioxide therein to release
20 the carbon dioxide, thereby recovering the carbon dioxide.
Dated this 1 1/07/2014
[RANJNA MEHTA-DUTT]
OF REIvFRY & SAGAR
ATTORNEY FOR THE APPLdCANT[S]
-21-