Carbon dioxide absorbent

Abstract

The present invention provides a carbon dioxide absorbent comprising a primary amine and a dialkylene glycol dialkyl ether or trialkylene glycol dialkyl ether. The carbon dioxide absorbent according to the present invention has an excellent carbon dioxide absorptivity, absorption rate and regeneration property.

Claims

1. A carbon dioxide absorbent comprising a primary amine represented by Chemical Formula 1 below and a dialkylene glycol dialkyl ether or trialkylene glycol dialkyl ether represented by Chemical Formula 2 below: ##STR00002## wherein, R.sub.1, R.sub.2, R.sub.3, R.sub.4 and R.sub.5 are each independently hydrogen or a C.sub.1-C.sub.4 alkyl group, at least one of R.sub.3, R.sub.4 and R.sub.5 is a C.sub.1-C.sub.4 alkyl group, R.sub.6 and R.sub.8 are each independently a C.sub.1-C.sub.4 alkyl group, R.sub.7 is hydrogen or methyl, m is an integer of 1 to 9, and n is an integer of 2 or 3; wherein an amount of the primary amine is 30 to 70% by weight based on a total amount of the absorbent.

2. The carbon dioxide absorbent of claim 1, wherein R.sub.1, R.sub.2, R.sub.3, R.sub.4 and R.sub.5 are each independently hydrogen, methyl, ethyl, propyl or butyl, at least one of R.sub.3, R.sub.4 and R.sub.5 is methyl, ethyl, propyl or butyl, R.sub.6 and R.sub.8 are each independently methyl, ethyl, propyl or butyl, and R.sub.7 is hydrogen or methyl.

3. The carbon dioxide absorbent of claim 1, wherein the primary amine represented by the Chemical Formula 1 is selected from the group consisting of 1,1,3,3-tetramethylbutylamine, 2-octylamine, 2-ethylhexylamine, 4-methyl-3-heptylamine, 2-methyl-3-heptylamine, 3-methyl-3-octylamine, 3-ethyl-2-heptylamine, 2-nonylamine, 3-nonylamine, 5-nonylamine, 3-methyl-3-nonylamine, 2-methyl-2-nonylamine, 3-undecylamine, 4-undecylamine, 2-dodecylamine, 3-dodecylamine, and 2-ethyl-1-dodecylamine.

4. The carbon dioxide absorbent of claim 1, wherein the dialkylene glycol dialkyl ether or trialkylene glycol dialkyl ether represented by Chemical Formula 2 is selected from the group consisting of diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol ethyl methyl ether, diethylene glycol dipropyl ether, diethylene glycol dibutyl ether, dipropylene glycol dimethyl ether, dipropylene glycol diethyl ether, dipropylene glycol ethyl methyl ether, dipropylene glycol dipropyl ether, dipropylene glycol dibutyl ether, triethylene glycol dimethyl ether, triethylene glycol diethyl ether, triethylene glycol dipropyl ether, triethylene glycol dibutyl ether, tripropylene glycol dimethyl ether, tripropylene glycol diethyl ether, tripropylene glycol dipropyl ether, and tripropylene glycol dibutyl ether.

5. The carbon dioxide absorbent of claim 1, wherein the amount of the dialkylene glycol dialkyl ether or trialkylene glycol dialkyl ether is 30 to 70% by weight based on the total amount of the absorbent.

6. The carbon dioxide absorbent of claim 1, further comprising water in an amount of 15% by weight or less based on the total amount of the absorbent.

7. A method of separating carbon dioxide from a gaseous mixture comprising the steps of (i) absorbing carbon dioxide using the carbon dioxide absorbent according to claim 1; and (ii) desorbing carbon dioxide absorbed in the carbon dioxide absorbent of (i).

8. The method of separating carbon dioxide of claim 7, wherein the absorption temperature in step (i) is in the range of 20 C. to 60 C.

9. The method of separating carbon dioxide of claim 7, wherein the absorption pressure in step (i) is in the range of atmospheric pressure to 20 atm.

10. The method of separating carbon dioxide of claim 7, wherein the desorption temperature in step (ii) is in the range of 80 C. to 140 C.

11. The method of separating carbon dioxide of claim 7, wherein the desorption pressure in step (ii) is in the range of atmospheric pressure to 2 atm.

12. A carbon dioxide absorbent comprising a primary amine represented by Chemical Formula 1 below and a dialkylene glycol dialkyl ether or trialkylene glycol dialkyl ether represented by Chemical Formula 2 below: ##STR00003## wherein, R.sub.1, R.sub.2, R.sub.3, R.sub.4 and R.sub.5 are each independently hydrogen or a C.sub.1-C.sub.4 alkyl group, at least one of R.sub.3, R.sub.4 and R.sub.5 is a C.sub.1-C.sub.4 alkyl group, R.sub.6 and R.sub.8 are each independently a C.sub.1-C.sub.4 alkyl group, R.sub.7 is hydrogen or methyl, m is an integer of 1 to 9, and n is an integer of 2 or 3, wherein the primary amine represented by the Chemical Formula 1 is selected from the group consisting of 1,1,3,3-tetramethylbutylamine, 2-octylamine, 2-ethylhexylamine, 4-methyl-3-heptylamine, 2-methyl-3-heptylamine, 3-methyl-3-octylamine, 3-ethyl-2-heptylamine, 2-nonylamine, 3-nonylamine, 5-nonylamine, 3-methyl-3-nonylamine, 2-methyl-2-nonylamine, 3-undecylamine, 4-undecylamine, 2-dodecylamine, 3-dodecylamine, and 2-ethyl-1-dodecylamine.

13. The carbon dioxide absorbent of claim 12, further comprising water in an amount of 15% by weight or less based on the total amount of the absorbent.

14. A carbon dioxide absorbent comprising a primary amine represented by Chemical Formula 1 below and a dialkylene glycol dialkyl ether or trialkylene glycol dialkyl ether represented by Chemical Formula 2 below: ##STR00004## wherein, R.sub.1, R.sub.2, R.sub.3, R.sub.4 and R.sub.5 are each independently hydrogen or a C.sub.1-C.sub.4 alkyl group, at least one of R.sub.3, R.sub.4 and R.sub.5 is a C.sub.1-C.sub.4 alkyl group, R.sub.6 and R.sub.8 are each independently a C.sub.1-C.sub.4 alkyl group, R.sub.7 is hydrogen or methyl, m is an integer of 1 to 9, and n is an integer of 2 or 3, wherein the amount of the dialkylene glycol dialkyl ether or trialkylene glycol dialkyl ether is 30 to 70% by weight based on the total amount of the absorbent.

15. The carbon dioxide absorbent of claim 14, further comprising water in an amount of 15% by weight or less based on the total amount of the absorbent.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 shows a schematic diagram of an experimental apparatus for absorption and desorption of carbon dioxide.

DETAILED DESCRIPTION OF THE EMBODIMENTS

(2) Hereinafter, the present invention will be described in more detail by way of Examples. However, these Examples are given for illustrative purposes only, and the scope of the invention is not intended to be limited by these Examples.

(3) Experimental Apparatus and Process for Carbon Dioxide Absorption

(4) The experiment on carbon dioxide absorption performance was conducted using the apparatus of FIG. 1. The apparatus of FIG. 1 consisted of a 60 mL glass reactor for high pressure (R1) equipped with a thermometer (T2), a pressure transducer (P1) for high pressure (0 to 70 atm), a 75 mL carbon dioxide storage cylinder (S2) equipped with a thermometer (T1) and a stirrer (1), and it was installed in a thermostatic chamber in order to measure the carbon dioxide absorptivity at a predetermined temperature. In addition, a carbon dioxide supply container (S1) and a pressure gauge (P2) were installed on the exterior of the thermostatic chamber.

(5) A predetermined amount of an absorbent and a magnet rod were added together in the absorption reactor (R1) of FIG. 1, and the weight of the reactor was measured. Then, the reactor was transferred to a constant temperature oven, and the temperature inside the reactor was maintained at 40 C. Subsequently, a valve (V4) connected to the absorption reactor (R1) was closed, and carbon dioxide of 50 atm was added to the storage cylinder (S2), then the equilibrium pressure and temperature were recorded. Then, the stirring of the absorption reactor (R1) was stopped, and the pressure of the absorption reactor (R1) was kept constant by using the valve (V4) and a pressure regulator. Thereafter, the pressure and temperature of the storage cylinder (S2) were recorded at the equilibrium state, and the pressure and temperature of S2 were recorded every 1 minute after initiation of stirring, then the change in the weight of the absorption reactor (R1) was measured after 30 minutes.

(6) Further, for the desorption experiment, the valve (V4) was closed, and the temperature of the absorption reactor (R1) was raised to 80 to 140 C. Then, the valve (V4), a valve (V5) and a valve (V6) were opened, and the carbon dioxide was desorbed for 30 minutes while supplying the absorption reactor (R1) with nitrogen at 20 ml/min from the N.sub.2 storage cylinder S3. Thereafter, the temperature was lowered to room temperature, and the change in the weight before and after desorption was measured.

EXAMPLES 1-9

(7) 30 g of a non-aqueous absorbent having a weight ratio of the primary amine/dialkylene glycol dialkyl in the following Table 1 of 55/45 was filled into ether or trialkylene glycol dialkyl ether disclosed the absorption reactor (R1) of FIG. 1, and the temperature of the reactor was fixed at 40 C., thereby carrying out the carbon dioxide absorption experiment. The stirring of the absorption reactor (R1) was stopped, and the pressure of the storage cylinder (S2) at the equilibrium state was recorded while maintaining the pressure of the absorption reactor (R1) at 1 atm using the valve (V4) and the pressure regulator. Then, the stirring was again initiated, and the change in the pressure of the storage cylinder (S2) was recorded up to 30 minutes at an interval of 1 minute, and the amount of carbon dioxide absorption was calculated therefrom. Further, in order to ensure the accuracy of the experiment, the weight of the reactor before and after the absorption was measured to obtain the amount of carbon dioxide absorption.

(8) The desorption and carbon dioxide reabsorptivity experiment was carried out in the following manner: the valve (V4) was closed, and the temperature of the absorption reactor (R1) was raised to 100 C. Then, the valve (V4), the valve (V5) and the valve (V6) were opened, and carbon dioxide was desorbed for 30 minutes while supplying the absorption reactor (R1) with nitrogen at 20 ml/min. Then, carbon dioxide was reabsorbed at 40 C. Further, in order to ensure the accuracy of the measurements, the change in the weight of the absorption reactor (R1) before and after the absorption and desorption experiments. The results are shown in Table 1 below as the carbon dioxide absorptivity (g CO.sub.2/Kg absorbent), the carbon dioxide reabsorptivity (g CO.sub.2/Kg absorbent) during carbon dioxide reabsorption after desorption, and the regeneration rate (reabsorptivity after desorption/initial absorptivity).

(9) TABLE-US-00001 TABLE 1 CO.sub.2 CO.sub.2 Component of absorbent absorptivity reabsorptivity Regeneration Primary Dialkyl (g CO.sub.2/Kg (g CO.sub.2/Kg rate Examples amine ether absorbent) absorbent) (%) 1 2- diethylene 110 107 97 octylamine glycol diethyl ether 2 4-methyl-3- dipropylene 107 100 93 heptylamine glycol dimethyl ether 3 1,1,3,3- diethylene 103 95 98 tetramethyl glycol butylamine dibutyl ether 4 2- diethylene 112 110 98 ethylhexylamine glycol diethyl ether 5 3-methyl-3- triethylene 109 106 97 octylamine glycol dimethyl ether 6 2- tripropylene 104 96 92 nonylamine glycol dipropyl ether 7 3- diethylene 107 102 95 nonylamine glycol ethyl methyl ether 8 3- diethylene 102 97 95 undecylamine glycol dipropyl ether 9 2-ethyl-1- tripropylene 105 104 98 dodecylamine glycol diethyl ether

EXAMPLES 10-13

(10) The carbon dioxide absorption experiment was carried out in the same manner as in Example 1 by using the same absorbent as in Example 1, while fixing the pressure of carbon dioxide at 1 atm and changing the absorption temperature. The results are shown in Table 2 below.

(11) TABLE-US-00002 TABLE 2 CO.sub.2 CO.sub.2 Absorption absorptivity reabsorptivity Regeneration temperature (g CO.sub.2/Kg (g CO.sub.2/Kg rate Examples ( C.) absorbent) absorbent) (%) 10 20 117 112 96 11 30 114 109 96 12 50 105 105 100 13 60 96 96 100

EXAMPLES 14-17

(12) The carbon dioxide absorption experiment was carried out in the same manner as in Example 1 by using the same absorbent as in Example 1, while fixing the temperature at 40 C. and changing the absorption pressure. The results are shown in Table 3 below.

(13) TABLE-US-00003 TABLE 3 CO.sub.2 CO.sub.2 Absorption absorptivity reabsorptivity Regeneration pressure (g CO.sub.2/Kg (g CO.sub.2/Kg rate Examples (atmosphere) absorbent) absorbent) (%) 14 2 115 113 98 15 5 121 119 98 16 10 130 129 99 17 20 133 132 99

EXAMPLES 18-24

(14) The carbon dioxide absorption experiment was carried out in the same manner as in Example 1 while changing the % by weight of primary amine/diethylene glycol diethyl ether, and fixing the temperature at 40 C. and the pressure at 1 atm. The results are shown in Table 4 below.

(15) TABLE-US-00004 TABLE 4 Primary CO.sub.2 CO.sub.2 amine/diether absorptivity reabsorptivity composition (g CO.sub.2/Kg (g CO.sub.2/Kg Regeneration Examples (wt %) absorbent) absorbent) rate (%) 18 20/80 41 41 100 19 30/70 62 62 100 20 40/60 84 83 99 21 50/50 102 100 98 22 60/40 121 115 95 23 65/35 126 120 95 24 70/30 131 124 95

EXAMPLES 25-27

(16) The carbon dioxide absorption experiment was carried out by setting the weight of 2-octylamine to 65% as in Example 23, while changing the weight ratio of water to glycol diethyl ether under the condition in which glycol diethyl ether was present. The results are shown in Table 5 below.

(17) TABLE-US-00005 TABLE 5 CO.sub.2 CO.sub.2 Water/ether absorptivity reabsorptivity composition (g CO.sub.2/Kg (g CO.sub.2/Kg Regeneration Examples (wt %) absorbent) absorbent) rate (%) 25 5/30 128 128 100 26 10/25 130 129 100 27 15/20 132 132 100

EXAMPLES 28-36

(18) The change in the regeneration rate in accordance with the change in the desorption temperature and pressure was measured, while fixing the composition of absorbent and the absorption temperature (40 C.) as in Example 1. The results are shown in Table 6 below.

(19) TABLE-US-00006 TABLE 6 CO.sub.2 CO.sub.2 Desorption Desorption absorptivity reabsorptivity Regeneration temperature pressure (g CO.sub.2/Kg (g CO.sub.2/Kg rate Examples ( C.) (atm) absorbent) absorbent) (%) 28 80 1 110 75 68 29 90 1 110 97 88 30 100 2 110 108 98 31 110 2 110 110 100 32 120 1 110 110 100 33 130 2 110 110 100 34 140 1 110 110 100 35 110 1 110 110 100 36 120 2 110 110 100

COMPARATIVE EXAMPLE 1

(20) An experiment in which carbon dioxide was absorbed at 1 atm and 40 C. using an aqueous solution containing 30% by weight of monoethanolamine as absorbent, and then desorbed at 100 C. under atmospheric pressure was carried out in the same manner as in Example 1. As a result, the carbon dioxide absorptivity was 125 g per 1 kg of absorbent. However, when carbon dioxide was reabsorbed after desorption at 100 C., the carbon dioxide absorptivity was 43 g, confirming that the regeneration rate was only 34.4%.

DESCRIPTION OF REFERENCE NUMERALS

(21) R1: Absorption reactor S1: CO.sub.2 supply container S2: CO.sub.2 storage cylinder S3: N.sub.2 storage cylinder P1: Pressure transducer for high pressure PR1, PR2: Pressure regulator T1, T2: Thermometer V1 V6: Valve 1: Stirrer