CARBON DIOXIDE ABSORBENT COMPRISING TRIAMINE

Abstract

The present invention relates to a carbon dioxide absorbent comprising a triamine, a diamine and a dialkylene glycol dialkyl ether or trialkylene glycol dialkyl ether. The carbon dioxide absorbent according to the present invention can improve the carbon dioxide absorption capacity, absorption rate, and regeneration performance thereof simultaneously by using the triamine as a main absorbent, the diamine as a rate enhancer, the dialkylene glycol dialkyl ether or trialkylene glycol dialkyl ether as a fine disproportionation agent and a regeneration promoter.

Claims

1. A carbon dioxide absorbent comprising: a triamine represented by the following chemical formula 1, a linear diamine represented by the following chemical formula 2 or a cyclodiamine represented by the following chemical formula 3 and a dialkylene glycol dialkyl ether or trialkylene glycol dialkyl ether represented by the following chemical formula 4: ##STR00002## wherein, R.sub.1, R.sub.2, R.sub.3 and R.sub.4 are each independently hydrogen or a C.sub.1-C.sub.4 alkyl group, R.sub.5 is hydrogen or a C.sub.1-C.sub.4 alkyl group, R.sub.6 and R.sub.7 are each independently hydrogen or a C.sub.1-C.sub.4 alkyl group, R.sub.8 is hydrogen, a C.sub.1-C.sub.4 alkyl group or a C.sub.1-C.sub.4 aminoalkyl group, R.sub.9, R.sub.10 and R.sub.11 are each independently hydrogen or a C.sub.1-C.sub.4 alkyl group, R.sub.12 and R.sub.13 are each independently a C.sub.1-C.sub.4 alkyl group, R.sub.14 is hydrogen or methyl, m is an integer of 2 or 3, n is an integer of 4 to 8, and p is an integer of 2 or 3.

2. The carbon dioxide absorbent according to claim 1, wherein R.sub.1, R.sub.2, R.sub.3 and R.sub.4 are each independently hydrogen, methyl or ethyl, R.sub.5 is hydrogen or methyl, R.sub.6 and R.sub.7 are each independently hydrogen, methyl or ethyl, R.sub.8 is hydrogen, methyl, ethyl, propyl, butyl or aminoethyl, R.sub.9, R.sub.10 and R.sub.11 are each independently hydrogen or methyl, R.sub.12 and R.sub.13 are each independently methyl, ethyl, propyl or butyl, and R.sub.14 is hydrogen or methyl.

3. The carbon dioxide absorbent according to claim 1, wherein the triamine represented by the chemical formula 1 is selected from the group consisting of 2,2′-iminobis(N,N-dimethylethylamine), 2,2′-iminobis(N,N-diethylethylamine), 3,3′-iminobis(N,N-dimethylpropylamine), 3,3′-iminobis(N,N-diethylpropylamine), 2,2′-iminobis(N,N′-dimethylethylamine), N,N-bis[2-(methylamino)ethyl]methylamine, N,N-bis[3-(methylamino)propyl]methylamine, N,N′-(iminobisethylene)bismethaneamine, and N,N′-(iminobispropylene]bismethaneamine.

4. The carbon dioxide absorbent according to claim 1, wherein the linear diamine represented by the chemical formula 2 is selected from the group consisting of 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane, 1,7-diaminoheptane, 1,8-diaminooctane, N,N-dimethyl-1,4-diaminobutane, N,N-diethyl-1,4-diaminobutane, N,N-dimethyl-1,5-diaminopentane, N,N-diethyl-1,5-diaminopentane, N,N-dimethyl-1,6-diaminohexane, N,N-diethyl-1,6-diaminohexane, N,N-dimethyl-1,7-diaminoheptane, N,N-diethyl-1,7-diaminoheptane, N,N-dimethyl-1,8-diaminooctane, and N,N-diethyl-1,8-diaminooctane.

5. The carbon dioxide absorbent according to claim 1, wherein the cyclodiamine represented by the chemical formula 3 is selected from the group consisting of piperazine, 1-methylpiperazine, 1-ethylpiperazine, 1-propylpiperazine, 1-isopropylpiperazine, 1-butylpiperazine, 2-methylpiperazine, 1,2-dimethylpiperazine, 1,5-dimethylpiperazine, 1,6-dimethylpiperazine, and N-(2-aminoethyl)piperazine.

6. The carbon dioxide absorbent according to claim 1, wherein the dialkylene glycol dialkyl ether or trialkylene glycol dialkyl ether represented by the chemical formula 4 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.

7. The carbon dioxide absorbent according to claim 1, wherein the amount of the triamine is 10 to 70% by weight based on the total amount of the absorbent.

8. The carbon dioxide absorbent according to claim 1, wherein the amount of the linear diamine or cyclodiamine is 1 to 30% by weight based on the total amount of the absorbent.

9. The carbon dioxide absorbent according to claim 1, wherein the amount of the dialkylene glycol dialkyl ether or trialkylene glycol dialkyl ether is 5 to 40% by weight based on the total amount of the absorbent.

10. The carbon dioxide absorbent according to claim 1, wherein the carbon dioxide absorbent is used by being dissolved in water.

11. The carbon dioxide absorbent according to claim 10, wherein the amount of water is 10 to 70% by weight based on the total amount of the absorbent.

12. A separation method of carbon dioxide from a gas mixture, which comprises the steps of: (i) absorbing carbon dioxide by using the carbon dioxide absorbent according to claim 1; and (ii) separating the absorbed carbon dioxide from the carbon dioxide absorbent.

13. The separation method according to claim 12, wherein the absorption temperature in step (i) is in the range of 10° C. to 60° C.

14. The separation method according to claim 12, wherein the absorption pressure in step (i) is in the range of normal pressure to 30 atm.

15. The separation method according to claim 12, wherein the separation temperature in step (ii) is in the range of 70° C. to 140° C.

16. The separation method according to claim 12, wherein the separation pressure in step (ii) is in the range of normal pressure to 2 atm.

Description

BRIEF DESCRIPTION OF DRAWING

[0050] FIG. 1 is a schematic view illustrating an example of a device for carbon dioxide absorption and separation tests.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0051] Hereinafter, the invention is described more fully with reference to illustrative embodiments and the accompanying drawings. However, it would be obvious to those skilled in the art that the embodiments are merely illustrative for explanation of the present invention, and the scope of the present invention is not limited thereto.

[0052] Device and Process for Carbon Dioxide Absorption Tests

[0053] Tests on the carbon dioxide absorption capacity were conducted by using the device illustrated in FIG. 1. The device illustrated in FIG. 1 includes a 60 ml stainless steel absorption reactor R1 equipped with a thermometer T2, a pressure transducer for high pressure (0 to 70 atm) P1, a 75 ml carbon dioxide storage cylinder S2 equipped with a thermometer T1, and a stirrer 1, and is installed in an isothermal oven to measure the carbon dioxide absorption capacity at a constant temperature. Further, a carbon dioxide supply cylinder S1 and a manometer P2 are installed on the outside of the isothermal oven.

[0054] After weighing the entire weight of the absorption reactor R1 into which a certain amount of absorbent was put along with a magnet bar, the absorption reactor was stirred at 60° C. for one hour to be dried under vacuum, and then the temperature was reduced to 40° C. so that the absorption reactor and the isothermal oven were maintained at a constant temperature. After closing a valve V4 connected to the absorption reactor R1, carbon dioxide at a constant pressure (e.g., 10 to 50 atm) was put into the storage cylinder S2, and the pressure and temperature in equilibrium were recorded. Then, after the stirring of the absorption reactor R1 was stopped and the pressure of the absorption reactor R1 was maintained at a constant pressure by using the valve V4 and a pressure regulator, the pressure and temperature of the storage cylinder S2 in equilibrium were recorded, and then the stirring was started. After one hour, the final pressure and temperature (equilibrium values) were recorded, and a change in the weight of the absorption reactor R1 was measured.

[0055] Further, during a separation test, after closing the valve V4 and increasing the temperature of the absorption reactor R1 to 70° C. to 140° C., the valve V4, a valve V5 and a valve V6 were opened, and 20 ml/min of nitrogen was introduced to the absorption reactor R1 to separate carbon dioxide. Then, the temperature was reduced to room temperature, and a change in the weight before and after the separation was measured.

Examples 1 to 9

[0056] 30 g of an aqueous solution absorbent having a weight ratio of triamine/diamine/dialkylene glycol dialkyl ether or trialkylene glycol dialkyl ether/water of 30/5/15/50 shown in Table 1 below was added to the absorption reactor R1 illustrated in FIG. 1, and then carbon dioxide absorption tests were performed while maintaining the temperature of the isothermal oven at 40° C. After stirring of the absorption reactor R1 was stopped, the pressure of the absorption reactor R1 was maintained at 1 atm by using the valve V4 and a pressure regulator, and the pressure of the storage cylinder S2 maintained in equilibrium was recorded, and then the stirring was started again. After one hour, the final pressure was recorded, and the amount of carbon dioxide absorbed per mole of amine was calculated from the difference.

[0057] In the case of the separation and carbon dioxide reabsorption tests, after closing the valve (V4) and raising the temperature of the absorption reactor (R1) to 100° C., the valve (V4), the valve (V5) and the valve (V6) were opened, and carbon dioxide was separated for 1 hour while introducing 20 ml/min of nitrogen to the absorption reactor (R1), and then the tests of reabsorbing carbon dioxide at 40° C. were carried out. Further, in order to ensure the accuracy of the measurement, the weight change of the absorption reactor (R1) was measured before and after absorption and separation tests, and the results are shown in Table 1 below as the cyclic capacity (mole number of carbon dioxide absorbed per mole of amine at the time of reabsorbing carbon dioxide after separation).

TABLE-US-00001 TABLE 1 Absorbent components Dialkylene glycol dialkyl ether or CO.sub.2 absorption Cyclic capacity trialkylene glycol capacity (mole of (mole of CO.sub.2/ Example triamine diamine dialkyl ether CO.sub.2/mole of amine) mole of amine) 1 3,3′-iminobis(N,N- Piperazine diethylene glycol 1.69 1.59 dimethylpropylamine) diethyl ether 2 2,2′-iminobis(N,N- 1,4-diamino butane diethylene glycol 1.67 1.54 dimethylethylamine) dimethyl ether 3 2,2′-iminobis(N,N- 1,6-diamino hexane dipropylene glycol 1.54 1.38 diethylethylamine) dimethyl ether 4 3,3′-iminobis(N,N- 1,8-diamino octane triethylene glycol 1.68 1.48 dimethylpropylamine) dimethyl ether 5 N,N-bis[3-(methyl- N,N-dimethyl- diethylene glycol 1.57 1.53 amino)propyl]methylamine 1,6-diamino hexane dibutyl ether 6 N,N′- 1-methylpiperazine tripropylene glycol 1.62 1.55 (iminobispropylene)bis- dipropyl ether methaneamine 7 3,3′-iminobis(N,N- 2-methylpiperazine diethylene glycol 1.55 1.47 dimethylpropylamine) ethyl metyl ether 8 3,3′-iminobis(N,N- N-(2-aminoethyl)piperazine diethylene glycol 1.65 1.57 dimethylpropylamine) dipropyl ether 9 3,3′-iminobis(N,N- 1,2-dimethylpiperazine tripropylene glycol 1.55 1.50 dimethylpropylamine) diethyl ether

Examples 10 to 13

[0058] Carbon dioxide absorption tests were carried out in the same manner as in Example 1: by using an absorbent having the same composition as in Example 1; and by varying the absorption temperature while fixing the carbon dioxide pressure at 1 atm. The results are shown in Table 2 below.

TABLE-US-00002 TABLE 2 Absorption CO.sub.2 absorption Cyclic capacity temperature capacity (mole of (mole of CO.sub.2/ Example (° C.) CO.sub.2/mole of amine) mole of amine) 10 10 1.83 1.67 11 30 1.72 1.61 12 50 1.44 1.33 13 60 1.12 1.04

Examples 14 to 17

[0059] Carbon dioxide absorption tests were carried out in the same manner as in Example 1: by using an absorbent having the same composition as in Example 1; and by varying the absorption pressure while fixing the temperature at 40° C. The results are shown in Table 3 below.

TABLE-US-00003 TABLE 3 CO.sub.2 Absorption Cyclic capacity Absorption capacity (mole of (mole of CO.sub.2/ Example pressure (atm) CO.sub.2/mole of amine) mole of amine) 14 2 1.75 1.66 15 5 1.84 1.70 16 10 1.91 1.82 17 30 1.98 1.85

Examples 18 to 21

[0060] Carbon dioxide absorption tests were carried out in the same manner as in Example 1: by changing the amount of water while fixing weight % of triamine/diamine/diethylene glycol diethyl ether at 60/10/30, the temperature at 40° C. and the pressure at 1 atm. The results are shown in Table 4 below. As the amount of water was decreased, the amount of carbon dioxide absorbed per mole of amine was reduced. The reason for this is considered that an increased amount of amine leads to an increase in the viscosity of an absorbent solution, thereby limiting delivery of materials.

TABLE-US-00004 TABLE 4 CO.sub.2 absorption Cyclic capacity Content of capacity (mole of (mole of CO.sub.2/ Example water (wt %) CO.sub.2/mole of amine) mole of amine) 18 10 1.34 1.13 19 30 1.54 1.38 20 60 1.75 1.66 21 70 1.81 1.73

Examples 22 to 30

[0061] Carbon dioxide absorption tests were carried out in the same manner as in Example 1: by varying the composition (weight %) of triamine (A) as a main absorbent, diamine (B) as a rate enhancer and diethylene glycol diethyl ether (C) as a fine disproportionation agent while fixing the amount of water in the absorbent at 50 weight %, the absorption temperature at 40° C. and the absorption pressure at 1 atm. The results are shown in Table 5 below.

TABLE-US-00005 TABLE 5 Absorbent Composition CO.sub.2 absorption Cyclic capacity (wt %) capacity (mole of (mole of CO.sub.2/ Example A B C CO.sub.2/mole of amine) mole of amine) 22 40 5 5 1.77 1.65 23 30 10 10 1.57 1.38 24 30 3 17 1.68 1.61 25 30 15 5 1.35 1.18 26 25 1 24 1.84 1.79 27 25 5 20 1.63 1.55 28 25 10 15 1.45 1.26 29 10 30 10 1.21 1.07 30 14 1 35 1.89 1.83

Examples 31 to 39

[0062] Changes in cyclic capacity according to changes in the separation temperature and pressure were measured while fixing the composition of the absorbent and the absorption temperature (40° C.) in Example 1. The results are shown in Table 6 below.

TABLE-US-00006 TABLE 6 Separation Separation CO.sub.2 absorption Cyclic capacity Exam- temperature pressure capacity (mole of (mole of CO.sub.2/ ple (° C.) (atm) CO.sub.2/mole of amine) mole of amine) 31 70 1 1.69 0.98 32 80 1 1.69 1.15 33 90 1 1.69 1.32 34 100 2 1.69 1.61 35 110 1 1.69 1.67 36 110 2 1.69 1.68 37 120 1 1.69 1.69 38 130 1 1.69 1.69 39 140 1 1.69 1.69

Comparative Example 1

[0063] The separation test was performed in the same manner as in Example 1 by absorbing carbon dioxide at 1 atm and 40° C. by using an aqueous solution containing 50% by weight of monoethanolamine as an absorbent, and separating the absorbed carbon dioxide at normal pressure and 100° C. As a result, the carbon dioxide absorption capacity was 0.55 mol of carbon dioxide per mole of monoethanolamine; however, when carbon dioxide was reabsorbed after separation at 100° C., the cyclic capacity was confirmed that carbon dioxide was absorbed only by 0.19 mol per 1 mol of monoethanolamine and the absorption capacity of the monoethanolamine aqueous solution was reduced by about 65.5%.

DESCRIPTION OF REFERENCE NUMERALS

[0064] R1: absorption reactor [0065] S1: CO.sub.2 supply container [0066] S2: CO.sub.2 storage cylinder [0067] P1: Pressure transducer for high pressure [0068] PR1, PR2: Pressure regulator [0069] T1, T2: Thermometer [0070] V1 to V6: Valve [0071] 1: Stirrer