Method for linkage recovery of organic acid in aqueous organic acid solution

Abstract

Disclosed is a method for linkage recovery of an organic acid in an aqueous organic acid solution. The method comprises: mixing a solution with an organic acid concentration lower than 20 wt % with a specific extractant and then subjecting same to counter-current extraction so as to obtain an extract phase and a raffinate phase; and subjecting the extract phase together with a solution with an acid concentration higher than 70 wt % to an azeotropic rectification so as to recover an organic acid. When the concentration of the aqueous organic acid solution is 20 wt %-70 wt %, the aqueous organic acid solution is extracted and concentrated to make the concentration of the aqueous organic acid solution higher than 70 wt %.

Claims

1. A method for linkage recovery of an organic acid in an aqueous organic acid solution, comprising: mixing an aqueous organic acid solution with a concentration lower than 20 wt % and an extractant and then subjecting the mixture to countercurrent extraction to obtain an extract phase and a raffinate phase; providing an aqueous organic acid solution with a concentration ranging from 20 wt % to 70 wt % and extracting and concentrating the solution to provide an aqueous organic acid solution with a concentration higher than 70 wt %; and subjecting the extract phase and the aqueous organic acid solution with a concentration higher than 70 wt % to azeotropic rectification together to recover the organic acid; wherein a volume ratio of the aqueous organic acid solution with a concentration lower than 20 wt % to the extractant is 1:0.5-5; and wherein a volume ratio of the aqueous organic acid solution with a concentration higher than 70 wt % to the extract phase is 1: 1-5.

2. The method according to claim 1, wherein the extractant in the counter current extraction of the aqueous organic acid solution with a concentration lower than 20 wt % is any one selected from the group consisting of an ester extractant, an organic phosphorus extractant, an organic amine extractant, a ketone extractant, and a combination of at least two selected therefrom.

3. The method according to claim 2, wherein the organic acid is formic acid, and the extractant in the counter current extraction of the aqueous organic acid solution with a concentration lower than 20 wt % is the organic amine extractant and/or the organic phosphorus extractant, and wherein the mixture of the aqueous organic acid solution with a concentration lower than 20 wt % and the extractant further comprises a diluent.

4. The method according to claim 1, wherein the organic acid is acetic acid or propionic acid, and an extractant for extraction of the aqueous organic acid solution with a concentration ranging from 20 wt % to 70 wt % comprises any one selected from the group consisting of ethyl acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate, sec-butyl acetate, t-butyl acetate, ethyl n-valerate, glycerol acetate, and a combination of at least two selected therefrom.

5. The method according to claim 1, wherein the organic acid is formic acid, and the extractant for extraction of the aqueous organic acid solution with a concentration ranging from 20 wt % to 70 wt % is the same as the extractant for the countercurrent extraction.

6. The method according to claim 1, wherein an adsorbent is used for purifying the aqueous organic acid solution before the countercurrent extraction; a solid adsorbent is used for adsorbing organic acid in the raffinate phase, and the organic acid in the raffinate phase is recovered through heating and desorption while the adsorbent is regenerated.

7. The method according to claim 1, comprising: mixing an aqueous organic acid solution with a concentration lower than 20 wt % and an extractant at a volume ratio of 1:0.5-5 and then subjecting the mixture to countercurrent extraction under normal pressure at 20-25° C. to obtain an extract phase and a raffinate phase, wherein organic acid in the raffinate phase is adsorbed by a solid adsorbent, and the organic acid in the raffinate phase is recovered through heating and desorption while the adsorbent is regenerated; and the extract phase and the aqueous organic acid solution with a concentration higher than 70 wt % are mixed at a volume ratio of 1-5:1 and then subjected to azeotropic rectification to recover the organic acid.

8. The method of claim 1, wherein the countercurrent extraction is performed under normal pressure and at a temperature of 20 to 70° C.

9. The method of claim 1, wherein the extract phase comprises the extractant, the organic acid and water, and the raffinate phase comprises water, the extractant and the organic acid.

10. The method of claim 2, wherein the ester extractant comprises any one selected from the group consisting of ethyl acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate, sec-butyl acetate, t-butyl acetate, ethyl n-valerate, glycerol acetate, and a combination of at least two selected therefrom.

11. The method of claim 2, wherein the organic phosphorus extractant comprises trioctyl oxyphosphorus and/or tributyl phosphate.

12. The method of claim 2, wherein the organic amine extractant comprises any one selected from the group consisting of trioctylamine, primary amine N1923, tertiary amine N235, and a combination of at least two selected therefrom.

13. The method of claim 2, wherein the ketone extractant is cyclohexanone.

14. The method of claim 2, wherein the organic acid is acetic acid or propionic acid, and the extractant is any one selected from the group consisting of the organic phosphorus extractant, the organic amine extractant, the ester extractant, the ketone extractant, and a combination of at least two selected therefrom.

15. The method of claim 2, wherein the organic acid is butyric acid, and the extractant in the counter current extraction of the aqueous organic acid solution with a concentration lower than 20 wt % is the organic phosphorus extractant and/or is the organic amine extractant and the extractant further comprises a diluent.

16. The method of claim 3, wherein the diluent is a halogenated hydrocarbon and the volume ratio of the extractant to the diluent is 1-10:1.

17. The method of claim 15, wherein the diluent is a halogenated hydrocarbon and the volume ratio of the extractant to the diluent is 1-10:1.

Description

DETAILED DESCRIPTION

(1) For a better understanding of the present application, examples of the present application are listed below. Those skilled in the art should understand that the examples described herein are merely used for a better understanding of the present application and should not be construed as specific limitations to the present application.

(2) In specific examples of the present application, a packed tower with a packing height equivalent to a height of 25 theoretical plates is used for countercurrent extraction under normal pressure at 25° C., an azeotropic rectification tower with a packing height of 50 theoretical plates is used for azeotropic rectification, an extract phase obtained through the countercurrent extraction enters the azeotropic rectification tower from the 23rd plate, and an organic acid solution with a concentration higher than 70 wt % enters the azeotropic rectification tower from the 32nd plate.

(3) In Examples 1 to 5 of the present application, the volume ratio of the organic acid solution with a concentration lower than 20 wt % to the extractant is 1:2, the volume ratio of the organic acid solution with a concentration higher than 70 wt % to the extract phase is 1:3, and the extractant is trioctyl oxyphosphorus. The organic acid solution with a concentration lower than 20 wt % is simply referred to as a low-concentration aqueous organic acid solution, and the organic acid solution with a concentration higher than 70 wt % is simply referred to as a high-concentration aqueous organic acid solution. Concentrations of organic acid in the low-concentration aqueous organic acid solutions and high-concentration aqueous organic acid solutions are shown in Table 1. The organic acid is acetic acid.

(4) TABLE-US-00001 TABLE 1 Low-concentration High-concentration Aqueous Organic Acid Aqueous Organic Acid No. Solution/wt % Solution/wt % Example 1 2 95 Example 2 5 90 Example 3 10 85 Example 4 12 80 Example 5 15 75

(5) The volume ratios of the low-concentration aqueous organic acid solutions to the extractant (simply referred to as a volume ratio A) and the volume ratios of the high-concentration aqueous organic acid solutions to the extract phases (simply referred to as a volume ratio B) in Examples 6 to 10 are different from those in Example 5, and other conditions in Examples 6 to 10 are the same as those in Example 4. The volume ratio As and the volume ratio Bs in Examples 6 to 10 are shown in Table 2.

(6) TABLE-US-00002 TABLE 2 No. Volume Ratio A Volume Ratio B Example 6 .sup. 1:0.5 1:5 Example 7 1:1 1:4 Example 8 1:2 1:3 Example 9 1:3 1:2 Example 10 1:5 1:1

(7) The extractants used in Examples 11 to 15 are different from that in Example 5, and other conditions in Examples 11 to 15 are the same as those in Example 5. The extractants used in Examples 11 to 15 are shown in Table 3.

(8) TABLE-US-00003 TABLE 3 No. Extractant Example 11 Tributyl phosphate Example 12 Trioctylamine Example 13 Cyclohexanone Example 14 Trioctyl oxyphosphorus and trioctylamine (at a volume ratio of 1:1) Example 15 Trioctyl oxyphosphorus and tributyl phosphate (at a volume ratio of 1:1)

(9) In Examples 16 to 20, the high-concentration organic acid is obtained through extraction and concentration of the aqueous organic acid solution with a concentration ranging from 20 wt % to 70 wt %, and other conditions in Examples 16 to 20 are the same as those in Example 5. The organic acid concentrations and extractants selected for extraction and concentration are shown in Table 4.

(10) TABLE-US-00004 TABLE 4 Organic Acid No. Concentration/wt % Extractant Example 16 25 N-propyl acetate Example 17 30 Sec-butyl acetate Example 18 40 T-butyl acetate Example 19 50 Ethyl n-valerate Example 20 60 Ethyl acetate and sec-butyl acetate (at a volume ratio of 1:1)

(11) In Examples 21 to 25, the organic acid is formic acid; except for the selection of the extractant, the selection of the extractant for extraction and concentration, and that a diluent is added during the extraction of a low-concentration organic acid, other conditions are the same as those in Examples 16 to 20. The extractant is the same as the extractant for extraction and concentration. The selection of extractants and diluents is shown in Table 5.

(12) TABLE-US-00005 TABLE 5 Volume Ratio of the Diluent to the No. Diluent Extractant Extractant Example 21 Chloroform Primary amine N1923 10:1  Example 22 1,1,2-Trichloroethane Tertiary amine N235 8:1 Example 23 Chloroform Tributyl phosphate 5:1 Example 24 1,1,2-Trichloroethane Tributyl phosphate 2:1 Example 25 Chloroform and 1,1,2- Primary amine N1923 1:1 trichloroethane and tertiary amine N235 (at a volume ratio of 1:1) (at a volume ratio of 1:1)

(13) In Comparative Examples 1 to 5, concentrations of the organic acid in the low-concentration aqueous organic acid solutions are different from that in Example 5, and other conditions are the same as those in Example 5. In Comparative Examples 6 to 10, concentrations of the organic acid in the high-concentration aqueous organic acid solutions are different from that in Example 5, and other conditions are the same as those in Example 4. In Comparative Examples 11 to 15, concentrations of the organic acid in the low-concentration aqueous organic acid solutions and the high-concentration aqueous organic acid solutions are different from those in Example 5, and other conditions are the same as those in Example 5. The concentrations of the organic acid in the low-concentration aqueous organic acid solutions and the high-concentration aqueous organic acid solutions in Comparative Examples 1 to 5 are shown in the following Table 4. The concentrations of the organic acid in the low-concentration aqueous organic acid solutions and the high-concentration aqueous organic acid solutions in Comparative Examples 6 to 10 are shown in the following Table 5. The concentrations of the organic acid in the low-concentration aqueous organic acid solutions and the high-concentration aqueous organic acid solutions in Comparative Examples 11 to 15 are shown in the following Table 6.

(14) TABLE-US-00006 TABLE 4 Low-concentration High-concentration Aqueous Organic Acid Aqueous Organic Acid No. Solution/wt % Solution/wt % Comparative 25 75 Example 1 Comparative 30 75 Example 2 Comparative 35 75 Example 3 Comparative 40 75 Example 4 Comparative 45 75 Example 5

(15) TABLE-US-00007 TABLE 5 Low-concentration High-concentration Aqueous Organic Acid Aqueous Organic Acid No. Solution/wt % Solution/wt % Comparative 15 68 Example 6 Comparative 10 65 Example 7 Comparative 15 60 Example 8 Comparative 15 55 Example 9 Comparative 15 50 Example 10

(16) TABLE-US-00008 TABLE 6 Low-concentration High-concentration Aqueous Organic Acid Aqueous Organic Acid No. Solution/wt % Solution/wt % Comparative 25 68 Example 11 Comparative 30 65 Example 12 Comparative 35 60 Example 13 Comparative 40 55 Example 14 Comparative 45 50 Example 15

(17) The organic acid in Examples 1 to 20 and Comparative Examples 1 to 15 is acetic acid. The purities and the extraction rates of the organic acid obtained in Examples 1 to 20 and Comparative Examples 1 to 15 are characterized, and results are shown in the following Table 6.

(18) TABLE-US-00009 TABLE 6 Purity of Extraction Rate of No. Acetic Acid/% Acetic Acid/% Example 1 98.0 98 Example 2 98.5 97 Example 3 97.8 97 Example 4 98.4 98 Example 5 99.0 96 Example 6 96.0 96 Example 7 96.5 97 Example 8 98.0 97 Example 9 97.5 98 Example 10 96.0 96 Example 11 97.0 97 Example 12 96.3 98 Example 13 97.5 98 Example 14 98.4 97 Example 15 99.0 98 Example 16 96.5 98 Example 17 98.2 97 Example 18 97.5 99 Example 19 99.1 97 Example 20 98.3 98 Comparative Example 1 78 81 Comparative Example 2 80 83 Comparative Example 3 84 80 Comparative Example 4 76 79 Comparative Example 5 81 84 Comparative Example 6 81 76 Comparative Example 7 74 72 Comparative Example 8 71 77 Comparative Example 9 82 74 Comparative Example 10 79 74 Comparative Example 11 75 75 Comparative Example 12 84 79 Comparative Example 13 82 80 Comparative Example 14 76 71 Comparative Example 15 77 74

(19) The purities and the extraction rates of formic acid obtained in Examples 21 to 25 are characterized, and results are shown in the following Table 7.

(20) TABLE-US-00010 TABLE 7 Purity of Extraction Rate of No. Formic Acid/% Formic Acid/% Example 21 95.6 95 Example 22 98.8 96 Example 23 96.0 94 Example 24 97.5 98 Example 25 95.7 95

(21) As can be seen from test results in Table 1, when the organic acid is directly extracted from a low-concentration organic acid solution with a concentration greater than 20 wt % and/or a high-concentration organic acid solution with a concentration less than 70 wt %, the extraction rate of the organic acid and the purity of the organic acid are both lower than those of the organic acid extracted by the method of the present application.

(22) The applicant has stated that although the detailed process equipment and flows of the present application are described through the examples described above, the present application is not limited to the detailed process equipment and flows described above, which means that the implementation of the present application does not necessarily depend on the detailed process equipment and flows described above.