Carbon dioxide absorbent and method for absorbing and desorbing carbon dioxide

Abstract

A carbon dioxide absorbent is disclosed. The absorbent comprises organic amine, amino acid, and water, wherein said organic amine comprises tertiary amine and primary amine and/or secondary amine; and wherein amino acid is excess based on a stoichiometrical ratio of organic amine to amino acid in a reaction. A method for absorbing and desorbing carbon dioxide is further disclosed. In the absorbent system provided by the present disclosure, the conversion between primary (secondary) amine and (secondary) tertiary amine can be realized under the catalytic effect of amino acid with the changing of temperature, and carbon dioxide can be absorbed and desorbed effectively under a relatively low temperature.

Claims

1. A carbon dioxide absorbent for absorption of CO.sub.2 at a temperature range from 36 C. to 50 C., and desorption of CO.sub.2 at a temperature range from 91 C. to 104 C. comprising organic amine, amino acid, and water, wherein said organic amine comprises tertiary amine and at least one of primary amine and secondary amine; wherein the amino acid is excess based on a stoichiometrical ratio of the organic amine to the amino acid in a reaction; and wherein in said absorbent, a molar ratio of a total amount of the primary amine and the secondary amine to the amino acid is 1:(1.8-4.2).

2. The absorbent according to claim 1, wherein said primary amine is one or more selected from the group consisting of monoethanolamine, methyl monoethanolamine, 2-amino-2-methyl-1-propanol, -hydroxyethylenediamine, and 3-(methylamino)propylamine; and/or wherein said secondary amine is one or more selected from the group consisting of diethanolamine, tertiarybutylamineethoxyethanol (TBEE), piperazine and derivatives thereof, and morpholine and derivatives thereof.

3. The absorbent according to claim 1, wherein a molecular structural formula of said tertiary amine is: ##STR00003## wherein a number of C atom of R.sub.1, R.sub.2, or R.sub.3 ranges from 0 to 3; and wherein R.sub.1, R.sub.2, and R.sub.3 each is alkyl, hydroxyalkyl, or hydroxyl, and at least one of R.sub.1, R.sub.2, and R.sub.3 is hydroxyalkyl, or hydroxyl.

4. The absorbent according to claim 1, wherein said amino acid is one or more selected from the group consisting of the amino acid with the following molecular structural formula: ##STR00004## wherein a number of C atom of R1, R2, R3, or R4 ranges from 0 to 3, and R1, R2, R3, and R4 each is selected from the group consisting of hydrogen, alkyl, and hydroxyalkyl.

5. The absorbent according to claim 1, wherein based on a total weight of the absorbent, said absorbent comprises 10 wt % to 45 wt % amino acid, 5 wt % to 35 wt % the organic amine, and water as a balance.

6. The absorbent according to claim 1, wherein a molar ratio of the organic amine to the amino acid is 1:(1.1-3).

7. The absorbent according, to claim 6, wherein the molar ratio of the organic amine to the amino acid is 1:(1.1-2.4).

8. The absorbent according to claim 7, wherein the molar ratio of the organic amine to the amino acid is 1:(1.1-1.8).

9. The absorbent according to claim 1, wherein in said absorbent, a molar ratio of a total amount of the primary amine and the secondary amine to the amino acid is 1:(1.8-3.2).

10. The absorbent according to claim 9, wherein in said absorbent, a molar ratio of a total amount of the primary amine and the secondary amine to the amino acid is 1:(2-2.5).

11. The absorbent according to claim 1, wherein the organic amine is mixed amine of the primary amine and the tertiary amine.

12. A carbon dioxide absorbent for absorption of CO.sub.2 at a temperature range from 36 C. to 50 C., and desorption of CO.sub.2 at a temperature range from 91 C. to 104 C., comprising organic amine, amino acid, and water, wherein said organic amine is mixed amine of tertiary amine and at least one of primary amine and secondary amine, and a molar ratio of a total amount of the primary amine and the secondary amine to the amino acid is 1:(1.8-3.2); and wherein said primary amine is at least one selected from the group consisting of 2-amino-2-methyl-1-propanol, monoethanolamine, and 3-(methylamino)propylamine, said secondary amine is tertiarybutylamineethoxyethanol (TBEE), said tertiary amine is at least one selected from the group consisting of N-methyldiethanolamine, triethanolamine, and 2-(diisopropylamino)ethanol, and said amino acid is at least one selected from the group consisting of alanine, aminoacetic acid, and serine.

13. A method for absorbing and desorbing carbon dioxide, comprising the following steps: a) dissolving organic amine and amino acid into water to obtain absorbent, wherein the amino acid is excess based on a stoichiometrical ratio of the organic amine to the amino acid in a reaction, wherein said organic amine comprises tertiary amine and at least one of primary amine and secondary amine; and wherein in said absorbent, a molar ratio of a total amount of the primary amine and the secondary amine to the amino acid is 1:(1.8-4.2); b) heating the absorbent and keeping the absorbent under an absorption temperature at a temperature range from 36 C. to 50 C., and adding gas sample containing carbon dioxide to a bottom of the absorbent, so that carbon dioxide is absorbed by the absorbent; and c) heating the solution with carbon dioxide absorbed therein under stirring and keeping the solution under a desorption temperature at a temperature range from 91 C. to 104 C., so that the carbon dioxide absorbed therein is desorbed and the absorbent is regenerated.

14. The method according to claim 13, wherein said primary amine is one or more selected from the group consisting of monoethanolamine, methyl monoethanolamine, 2-amino-2-methyl-1-propanol, -hydroxyethylenediamine, and 3-(methylamino)propylamine; and/or wherein said secondary amine is one or more selected from the group consisting of diethanolamine, tertiarybutylamineethoxyethanol (TBEE), piperazine, and morpholine; and/or wherein, a molecular structural formula of said tertiary amine is: ##STR00005## wherein a number of C atom of R.sub.1, R.sub.2, or R.sub.3 ranges from 0 to 3, R.sub.1, R.sub.2, and R.sub.3 each is alkyl, hydroxyalkyl, or hydroxyl, and at least one of R.sub.1, R.sub.2, and R.sub.3 is hydroxyalkyl, or hydroxyl; and wherein said amino acid is one or more selected from the group consisting of the amino acid with the following molecular structural formula: ##STR00006## wherein a number of C atom of R1, R2, R3, or R4 ranges from 0 to 3, and R1, R2, R3, and R4 each is selected from the group consisting of hydrogen, alkyl, and hydroxyalkyl.

15. The method according to claim 13, wherein a molar ratio of the organic amine to the amino acid is 1:(1.1-3).

16. The method according to claim 13, wherein in said absorbent, a molar ratio of a total amount of the primary amine and the secondary amine to the amino acid is 1:(1.8-3.2).

17. The method according, to claim 13, wherein in step b), a flow-rate of the gas sample containing carbon dioxide, calculated in terms of carbon dioxide, ranges from 60 ml/min to 120 ml/min.

18. The method according to claim 13, wherein a flow-rate of the gas sample containing carbon dioxide, calculated in terms of carbon dioxide, ranges from 70 ml/min to 100 ml/min.

Description

DETAILED DESCRIPTION OF THE EMBODIMENTS

(1) The present disclosure will be illustrated hereinafter in combination with specific examples. However, it can be understood that, the scope of the present disclosure is not limited by the examples disclosed herein.

Example 1

(2) Alanine (0.25 mol), N-methyldiethanolamine (0.1 mol), and 2-amino-2-methyl-1-propanol (0.12 mol) are dissolved in deionized water (150 ml), and the absorbent mixed solution can be obtained. The above mixed solution is put into a four-necked flask with a mixer (150 rpm) and a thermometer, and the temperature of the solution in the flask is maintained at 40 C. under oil-bath heating. Carbon dioxide with a concentration of 99.9% is added to a bottom of the solution at a flow-rate of 70 ml/min. The solution is measured continuously with a wet corrosion-proof flow meter, and thus an absorption volume of carbon dioxide can be calculated. After the absorption experiment is completed, the desorption experiment is performed. That is, the above solution with carbon dioxide absorbed therein is heated and maintained at 100 C. under stirring with a speed of 150 rpm. The solution is measured continuously with a wet corrosion-proof flow meter, and thus a desorption ratio of carbon dioxide can be calculated. The experimental results are shown in Table 1 and Table 2, wherein Table 1 shows the amount of carbon dioxide absorbed in each liter of absorbent solution with the increasing of absorption time, and Table 2 shows the amount of residual carbon dioxide in each liter of absorbent solution with the increasing of desorption time.

Example 2

(3) Aminoacetic acid (0.25 mol), N-methyldiethanolamine (0.14 mol), and monoethanolamine (0.08 mol) are dissolved in deionized water (150 ml), and the absorbent mixed solution can be obtained. The above mixed solution is put into a four-necked flask with a mixer (150 rpm) and a thermometer, and the temperature of the solution in the flask is maintained at 40 C. under oil-bath heating. Carbon dioxide with a concentration of 99.9% is added to a bottom of the solution at a flow-rate of 70 ml/min. The solution is measured continuously with a wet corrosion-proof flow meter, and thus an absorption volume of carbon dioxide can be calculated. After the absorption experiment is completed, the desorption experiment is performed. That is, the above solution with carbon dioxide absorbed therein is heated and maintained at 100 C. under stirring with a speed of 150 rpm. The solution is measured continuously with a wet corrosion-proof flow meter, and thus a desorption ratio of carbon dioxide can be calculated. The experimental results are shown in Table 1 and Table 2.

Example 3

(4) Serine (0.25 mol), N-methyldiethanolamine (0.12 mol), and monoethanolamine (0.1 mol) are dissolved in deionized water (150 ml), and the absorbent mixed solution can be obtained. The above mixed solution is put into a four-necked flask with a mixer (150 rpm) and a thermometer, and the temperature of the solution in the flask is maintained at 40 C. under oil-bath heating. Carbon dioxide with a concentration of 99.9% is added to a bottom of the solution at a flow-rate of 70 ml/min. The solution is measured continuously with a wet corrosion-proof flow meter, and thus an absorption volume of carbon dioxide can be calculated. After the absorption experiment is completed, the desorption experiment is performed. That is, the above solution with carbon dioxide absorbed therein is heated and maintained at 100 C. under stirring with a speed of 150 rpm. The solution is measured continuously with a wet corrosion-proof flow meter, and thus a desorption ratio of carbon dioxide can be calculated. The experimental results are shown in Table 1 and Table 2.

Example 4

(5) Aminoacetic acid (0.25 mol), N-methyldiethanolamine (0.1 mol), and 3-(methylamino)propylamine (0.06 mol) are dissolved in deionized water (150 ml), and the absorbent mixed solution can be obtained. The above mixed solution is put into a four-necked flask with a mixer (150 rpm) and a thermometer, and the temperature of the solution in the flask is maintained at 40 C. under oil-bath heating. Carbon dioxide with a concentration of 99.9% is added to a bottom of the solution at a flow-rate of 70 ml/min. The solution is measured continuously with a wet corrosion-proof flow meter, and thus an absorption volume of carbon dioxide can be calculated. After the absorption experiment is completed, the desorption experiment is performed. That is, the above solution with carbon dioxide absorbed therein is heated and maintained at 100 C. under stirring with a speed of 150 rpm. The solution is measured continuously with a wet corrosion-proof flow meter, and thus a desorption ratio of carbon dioxide can be calculated. The experimental results are shown in Table 1 and Table 2.

Example 5

(6) Serine (0.25 mol), N-methyldiethanolamine (0.12 mol), and tertiarybutylamineethoxyethanol (TBEE) (0.08 mol) are dissolved in deionized water (150 ml), and the absorbent mixed solution can be obtained. The above mixed solution is put into a four-necked flask with a mixer (150 rpm) and a thermometer, and the temperature of the solution in the flask is maintained at 40 C. under oil-bath heating. Carbon dioxide with a concentration of 99.9% is added to a bottom of the solution at a flow-rate of 70 ml/min. The solution is measured continuously with a wet corrosion-proof flow meter, and thus an absorption volume of carbon dioxide can be calculated. After the absorption experiment is completed, the desorption experiment is performed. That is, the above solution with carbon dioxide absorbed therein is heated and maintained at 100 C. under stirring with a speed of 150 rpm. The solution is measured continuously with a wet corrosion-proof flow meter, and thus a desorption ratio of carbon dioxide can be calculated. The experimental results are shown in Table 1 and Table 2.

Example 6

(7) Serine (0.27 mol), 2-(diisopropylamino)ethanol (0.1 mol), and 3-(methylamino)propylamine (0.06 mol) are dissolved in deionized water (150 ml), and the absorbent mixed solution can be obtained. The above mixed solution is put into a four-necked flask with a mixer (150 rpm) and a thermometer, and the temperature of the solution in the flask is maintained at 32 C. under oil-bath heating. Carbon dioxide with a concentration of 99.9% is added to a bottom of the solution at a flow-rate of 90 ml/min. The solution is measured continuously with a wet corrosion-proof flow meter, and thus an absorption volume of carbon dioxide can be calculated. After the absorption experiment is completed, the desorption experiment is performed. That is, the above solution with carbon dioxide absorbed therein is heated and maintained at 98 C. under stirring with a speed of 150 rpm. The solution is measured continuously with a wet corrosion-proof flow meter, and thus a desorption ratio of carbon dioxide can be calculated. The experimental results are shown in Table 1 and Table 2.

Example 7

(8) Aminoacetic acid (0.28 mol), N-methyldiethanolamine (0.1 mol), monoethanolamine (0.07 mol), and piperazine (0.05 mol) are dissolved in deionized water (150 ml), and the absorbent mixed solution can be obtained. The above mixed solution is put into a four-necked flask with a mixer (160 rpm) and a thermometer, and the temperature of the solution in the flask is maintained at 50 C. under oil-bath heating. Carbon dioxide with a concentration of 99.9% is added to a bottom of the solution at a flow-rate of 80 ml/min. The solution is measured continuously with a wet corrosion-proof flow meter, and thus an absorption volume of carbon dioxide can be calculated. After the absorption experiment is completed, the desorption experiment is performed. That is, the above solution with carbon dioxide absorbed therein is heated and maintained at 104 C. under stirring with a speed of 150 rpm. The solution is measured continuously with a wet corrosion-proof flow meter, and thus a desorption ratio of carbon dioxide can be calculated. The experimental results are shown in Table 1 and Table 2.

Example 8

(9) The operation steps of the present example are basically the same as those of example 1, and the difference thereof only lies in that, in the present example, carbon dioxide with a concentration of 99.9% is substituted with coal-burning flue gas sample with a volume concentration of carbon dioxide of about 10%, and the sample is added to a bottom of the solution at a flow-rate of 700 ml/min. The experimental results are shown in Table 1 and Table 2.

Reference Example 1

(10) Monoethanolamine (MEA) solution (150 ml, 1.47 mol/L) is put into a four-necked flask with a mixer (150 rpm) and a thermometer, and the temperature of the solution in the flask is maintained at 40 C. under oil-bath heating. Carbon dioxide with a concentration of 99.9% is added to a bottom of the solution at a flow-rate of 70 ml/min. The solution is measured continuously with a wet corrosion-proof flow meter, and thus an absorption volume of carbon dioxide can be calculated. After the absorption experiment is completed, the desorption experiment is performed. That is, the above solution with carbon dioxide absorbed therein is heated and maintained at 100 C. under stirring with a speed of 150 rpm. The solution is measured continuously with a wet corrosion-proof flow meter, and thus a desorption ratio of carbon dioxide can be calculated. The experimental results are shown in Table 1 and Table 2.

Reference Example 2

(11) In the present example, except that the amount of alanine is changed into 0.1 mol, other experimental conditions and operation steps are the same as those of example 1. The experimental results are shown in Table 1 and Table 2.

Reference Example 3

(12) In the present example, except that the amount of serine is changed into 0.1 mol, other experimental conditions and operation steps are the same as those of example 6. The experimental results are shown in Table 1 and Table 2.

(13) TABLE-US-00001 TABLE 1 CO.sub.2 absorption situations Absorption time Time 20 min 40 min 1 h 5 h Solution CO.sub.2 CO.sub.2 CO.sub.2 CO.sub.2 L/L solution L/L solution L/L solution L/L solution Example 1 1.81 3.59 5.01 19.56 Example 2 2.08 3.89 5.08 19.98 Example 3 2.10 4.04 5.38 19.09 Example 4 2.11 4.10 5.53 20.43 Example 5 2.29 4.34 5.23 20.11 Example 6 1.94 3.68 5.44 19.78 Example 7 2.40 4.65 5.66 21.04 Example 8 1.66 3.49 4.99 19.06 Reference 1.89 3.77 5.16 17.44 example 1 Reference 1.86 3.47 5.10 19.77 example 2 Reference 2.01 3.89 5.74 19.97 example 3

(14) TABLE-US-00002 TABLE 2 CO.sub.2 desorption situations Desorption time Time Before desorption 5 min 10 min 20 min 40 min 1 h Solution CO.sub.2 CO.sub.2 CO.sub.2 CO.sub.2 CO.sub.2 CO.sub.2 L/L L/L L/L L/L L/L L/L solution solution solution solution solution solution Example 1 19.56 14.77 10.1 7.57 5.44 3.97 Example 2 19.98 15.02 11.23 8.27 6.45 4.57 Example 3 19.09 15.23 11.15 8.57 6.30 4.27 Example 4 20.43 15.48 11.43 8.87 6.75 4.45 Example 5 20.11 14.99 10.34 7.98 5.67 4.05 Example 6 19.78 16.58 12.43 9.43 7.78 6.03 Example 7 21.04 12.32 7.43 5.12 4.1 3.23 Example 8 19.06 14.22 10.00 7.43 5.21 3.37 Reference 17.44 14.05 10.81 8.98 7.98 7.53 example 1 Reference 19.77 17.77 15.10 13.57 11.94 10.77 example 2 Reference 19.97 17.13 14.43 11.48 10.08 9.83 example 3

(15) It can be seen from the above examples and reference examples as well as the experimental results as shown in Tables 1 and 2 that, the absorption ability of the carbon dioxide absorbent provided by the present disclosure is better than MEA. In particular, the absorption capacity can be improved by 13% at least. In addition, under the same conditions, the desorption ability thereof far exceeds MEA, and the desorption ratio can be improved by about 47% (as shown in example 1). As shown by the experimental results of reference examples 2 and 3, when the amount of amino acid is not excess, the desorption ability of the absorbent is apparently poor. The absorbent provided by the present disclosure shows good absorption and desorption performance when used for absorbing and desorbing carbon dioxide in the coal-burning flue gas (as shown in example 8).

(16) The present disclosure is illustrated in detail hereinabove. However, it is obvious for those skilled in the art to make amendments within the spirit and scope of the present disclosure. In addition, it can be understood that, different aspects recited in the present disclosure, different parts of the specific examples, and different technical features disclosed herein can be combined or interchanged totally or partly. In the above specific examples, the examples which refer to another example can be combined with other examples in a reasonable manner, which can be understood by those skilled in the art. Moreover, it can be understood by those skilled in the art that, the above description only shows specific examples, but not used for limiting the present disclosure.