CN112441913B - Method for purifying adipic acid - Google Patents
Method for purifying adipic acid Download PDFInfo
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- CN112441913B CN112441913B CN201910829935.3A CN201910829935A CN112441913B CN 112441913 B CN112441913 B CN 112441913B CN 201910829935 A CN201910829935 A CN 201910829935A CN 112441913 B CN112441913 B CN 112441913B
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- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
- C07C51/42—Separation; Purification; Stabilisation; Use of additives
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Abstract
The invention relates to a method for refining adipic acid, which mainly solves the technical problem that the crystal particles of the adipic acid obtained by the existing refining method are small and easy to adsorb impurities, and adopts the method for refining the adipic acid, and comprises the following steps: (1) obtaining a crude adipic acid solution; (2) cooling and crystallizing; (3) carrying out solid-liquid separation to obtain refined adipic acid crystals; wherein, the solvent used by the crude adipic acid solution comprises an additive and water, the additive is alcohol or carboxylic acid, and the weight ratio of the additive to the water is 0.05-0.20, so that the technical problem is better solved.
Description
Technical Field
The present invention relates to a method for purifying adipic acid.
Background
Adipic acid (Adipic acid) is an important basic organic chemical raw material, and the largest application of the Adipic acid is to produce nylon 66 salt, and also can be used for producing polyurethane, a plasticizer, polyamide, synthetic leather, a lubricant and the like.
Generally, adipic acid is from the catalytic oxidation reaction of cyclohexane, cyclohexane is firstly catalytically oxidized into cyclohexanone and cyclohexanol, and the cyclohexanone and cyclohexanol are separated and refined and then continuously oxidized into adipic acid by nitric acid; or cyclohexane is directly air-oxidized to obtain adipic acid. The intermediate products and by-products of adipic acid, glutaric acid, succinic acid, cyclohexanone, cyclohexanol and the like in the oxidation product coexist. The prior art generally extracts crude adipic acid which is a main product in a synthetic fluid, and then refines and purifies the crude adipic acid to obtain refined adipic acid. The refining and purifying process generally comprises the steps of dissolving crude adipic acid by using a solvent, and then crystallizing, thickening, centrifugally separating and drying. The key point of adopting the crystallization separation mode to purify and prepare the refined adipic acid is to control the size and the particle size distribution of adipic acid crystal particles, fine particles are easy to coalesce and hide impurities in the mother liquor, and the fine particles are easy to absorb moisture and coalesce, so that the fine adipic acid crystal particles are not beneficial to transportation and use. The high-purity large-particle adipic acid crystal has good fluidity, is easy to dry and store, is suitable for being used as a high-quality polyester raw material, and has high added value of products, so that the development of the method and the equipment for preparing the large-particle adipic acid crystal with high efficiency and low cost has practical significance.
CN206103397U discloses an adipic acid purification and crystallization device, which is composed of 12 crystallization chambers matched with a seed crystal mixer, a surface condenser and a mixing condenser. Although the fine crystal quantity is allegedly controlled, the equipment is complex and high in cost.
CN102803197B discloses a method for preparing adipic acid crystal, which obtains high-purity adipic acid by grinding adipic acid crystal for recycling, increases the investment of external mechanical equipment, and damages the appearance of crystal particles, which is not beneficial to the growth of adipic acid crystal particles.
CN1296339C discloses a method for producing adipic acid crystals and the obtained crystals, which comprises treating the adipic acid crystals in a dry atmosphere to exchange moisture therein, or drying the adipic acid crystals with hygroscopic silica gel, wherein the method does not change the original crystal particle size, but reduces the water content of the product in a container, has long treatment time, needs an additional fixed bed or fluidized bed device, and cannot fundamentally solve the problem of moisture absorption and agglomeration of the adipic acid crystals again.
CN1359364A discloses a method for preparing adipic acid, which mainly uses a liquid matrix to treat crystallized adipic acid crystals so as to modify the shape of the crystals and obtain 50um-1000um small round particles with smooth surfaces. Although this method modifies the defects on the crystal surface, the defects occluded in the crystal are not removed.
CN1257880C discloses a method for refining adipic acid by recrystallizing crude adipic acid, wherein the crude adipic acid is decolorized, recrystallized and dried to obtain refined adipic acid, and the purity of the adipic acid is more than 99.7%.
CN106478404B discloses a large-scale industrial continuous production method of refined adipic acid, wherein the refining part comprises the steps of crystallizing and thickening a pretreated adipic acid solution, washing by a centrifugal machine, carrying out solid-liquid separation, dissolving activated carbon in hot water for adsorption, and finally carrying out a procedure of crystallizing, thickening and centrifugal drying of the refined adipic acid to obtain a refined adipic acid product.
CN106905139A discloses a high-purity adipic acid extraction process, which comprises the steps of dissolving crude adipic acid in absolute ethyl alcohol, decoloring by using activated carbon, filtering, adding deionized water to evaporate part of ethanol-water azeotrope, stirring for crystallization, centrifuging to dry, and drying in vacuum to obtain high-purity adipic acid.
Disclosure of Invention
The invention aims to solve the problems that crystal particles obtained by refining and crystallizing adipic acid in the prior art are small, uneven in distribution and easy to have poor moisture absorption and fluidity, and the quality and feeding are affected.
The purpose of the invention is realized by the following technical scheme:
a method for purifying adipic acid, comprising:
(1) Obtaining a crude adipic acid solution;
(2) Cooling and crystallizing;
(3) Carrying out solid-liquid separation to obtain refined adipic acid crystals;
wherein the solvent used by the crude adipic acid solution comprises an additive and water, the additive is alcohol or carboxylic acid, and the weight ratio of the additive to the water is 0.05-0.25.
Due to the adoption of the technical scheme, compared with the prior art, the invention has the beneficial effects that: because the additive changes the property of the fluid, the growth of crystal particles is promoted, the average size of adipic acid crystals is improved, the purity of the refined adipic acid product can be improved, the degree of adsorbing environmental impurities in the storage process of the refined adipic acid product is reduced, and a better technical effect is achieved.
We have found that when the amount of the additive is increased to result in a weight ratio of the additive to water higher than the upper limit of the range of 0.05 to 0.25, the effect becomes worse as the amount of the additive is increased, such as the effect of the additive to increase the crystal size of adipic acid has been hardly seen when the weight ratio of the additive to water is 1. Of course, when the amount of the additive is too small to be below the lower limit of the range of 0.05 to 0.20 in terms of the weight ratio of the additive to water, the effect of the additive on increasing the crystal size of adipic acid becomes less pronounced due to the reduction in the amount.
In the above-mentioned embodiments, non-limiting examples of the weight ratio of the additive to water may be 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.20, 0.21, 0.22, 0.23, 0.24, and the like.
In the above-mentioned embodiment, the weight ratio of the additive to water is more preferably 0.05 to 0.20.
In the above-mentioned embodiment, the alcohol as the additive is preferably C 1 ～C 3 The alcohol of (1).
In the above-mentioned embodiment, the alcohol as the additive is preferably a monohydric alcohol.
In the above technical solution, the alcohol is preferably at least one selected from the group consisting of methanol, ethanol, propanol and isopropanol.
In the above embodiment, the carboxylic acid as the additive is preferably C 2 ～C 3 A monocarboxylic acid of (2).
In the above technical solution, the carboxylic acid is preferably acetic acid and/or propionic acid.
In the above technical solution, the mass ratio of the crude adipic acid to water in the crude adipic acid solution is preferably 0.2 to 0.75. For example, but not limited to, the crude adipic acid solution has a crude adipic acid to water mass ratio of 0.25, 0.30, 0.35, 0.40, 0.45, 0.50, 0.55, 0.60, 0.65, 0.70, and the like.
In the above technical scheme, the temperature of the crude adipic acid solution in the step (1) is preferably 50 to 80 ℃, such as but not limited to 55 ℃,60 ℃, 65 ℃, 70 ℃, 75 ℃ and the like.
In the above technical solution, the crystallization temperature in the step (2) is preferably 10 to 30 ℃. For example, but not limited to, the crystallization temperature in step (2) may be 11 ℃, 12 ℃, 13 ℃, 14 ℃, 15 ℃, 16 ℃, 17 ℃, 18 ℃, 19 ℃, 20 ℃, 21 ℃, 22 ℃, 23 ℃, 24 ℃, 25 ℃, 26 ℃, 27 ℃, 28 ℃, 29 ℃ and the like.
In the above technical scheme, the step (2) can be freely selected to add or not add seed crystals, and those skilled in the art know that the addition of seed crystals is more beneficial to the crystallization.
In the above technical solution, the content of adipic acid in the crude adipic acid is preferably at least 85% by weight in step (1). When the amount of impurities in the crude adipic acid is too large, the purification by crystallization is uneconomical, and it is proposed that the adipic acid content in the crude adipic acid is preferably at least 85% by the method of the present invention. The method of the invention has no practical and/or theoretical limit on the content of the adipic acid in the crude adipic acid, and can infinitely approach 100 percent. The effect of the method of the present invention to improve the crystal size of adipic acid can be clearly seen when the content of adipic acid in the crude adipic acid is in the range of at least 85 mass%. As a general rule, the skilled person understands that as the content of adipic acid in the crude adipic acid increases, the efforts to try to increase the purity become increasingly difficult, and the present invention is no exception. However, there is a tendency for the additive to water weight ratio to be 0.05 to 0.25 relative to water and additive, or other proportions of water and additive mixture, to increase purity.
In the above technical scheme, the solid-liquid separation may be centrifugation and/or filtration.
In the technical scheme, D50 of the fine adipic acid crystal obtained in the step (3) measured by a laser particle size method is at least 1000 microns. For example, but not limited to, a D50 of 1000 to 5000 microns, and non-limiting examples of values within this range include 1200 microns, 1400 microns, 1600 microns, 1800 microns, 2000 microns, 2200 microns, 2400 microns, 2600 microns, 2800 microns, 3000 microns, 3200 microns, 3400 microns, 3600 microns, 3800 microns, 4000 microns, 4200 microns, 4400 microns, 4600 microns, 4800 microns, and the like.
The average size of the adipic acid crystal particles was determined by a laser particle size method, in particular by dispersing a 10g sample of adipic acid in 100ml of soybean oil using a Mastersizer 2000 model laser particle sizer from malvern, uk, the main evaluation criterion being the average particle size D50 (the particle size corresponding to a cumulative volume fraction of 50%).
The purity of the adipic acid is determined by a high performance liquid chromatography method, in particular by HPLC of Agilent in the United states.
The present invention is further illustrated by the following examples, which are not intended to limit the scope of the invention.
Detailed Description
[ example 1 ] A method for producing a polycarbonate
Taking water, acetic acid and crude adipic acid solid (the mass content of adipic acid in the crude adipic acid is 90.52%), uniformly stirring and heating to 60 ℃ to dissolve to obtain a crude adipic acid solution, wherein the weight ratio of the crude adipic acid to the water in the crude adipic acid solution is 0.40, and the weight ratio of the acetic acid to the water in the crude adipic acid solution is 0.10.
Crystallizing the crude adipic acid solution at 20 ℃ for 40 minutes, performing centrifugal separation, and performing vacuum drying at 60 ℃ for 3 hours to obtain refined adipic acid with the purity of 99.99%.
The D50 size of the adipic acid crystal particles measured by laser granulometry was 2200 microns.
The main experimental conditions and experimental results are listed in table 1 for convenience of comparison.
[ example 2 ]
Taking water, methanol and crude adipic acid solid (the mass content of adipic acid in the crude adipic acid is 85.17%), uniformly stirring and heating to 50 ℃ to dissolve to obtain a crude adipic acid solution, wherein the weight ratio of the crude adipic acid to the water in the crude adipic acid solution is 0.20, and the weight ratio of the methanol to the water in the crude adipic acid solution is 0.05.
Crystallizing the crude adipic acid solution at 15 ℃ for 40 minutes, performing centrifugal separation, and performing vacuum drying at 60 ℃ for 3 hours to obtain refined adipic acid, wherein the purity of the refined adipic acid is 99.95%.
The D50 size of the adipic acid crystal particles measured by a laser particle size method is 1698 microns.
The main experimental conditions and experimental results are listed in table 1 for convenience of comparison.
[ example 3 ]
Taking water, ethanol and a crude adipic acid solid (the mass content of adipic acid in the crude adipic acid is 95.28%), uniformly stirring and heating to 65 ℃ to dissolve to obtain a crude adipic acid solution, wherein the weight ratio of the crude adipic acid to the water in the crude adipic acid solution is 0.50, and the weight ratio of the ethanol to the water in the crude adipic acid solution is 0.20.
Crystallizing the crude adipic acid solution at 25 ℃ for 40 minutes, performing centrifugal separation, and performing vacuum drying at 60 ℃ for 3 hours to obtain refined adipic acid with the purity of 99.98%.
The D50 size of adipic acid crystal particles was 4025 microns as determined by laser granulometry.
The main experimental conditions and experimental results are listed in table 1 for convenience of comparison.
[ example 4 ] A method for producing a polycarbonate
Taking water, propanol and crude adipic acid solid (the mass content of adipic acid in the crude adipic acid is 85.17%), uniformly stirring and heating to 70 ℃ to dissolve to obtain a crude adipic acid solution, wherein the weight ratio of the crude adipic acid to the water in the crude adipic acid solution is 0.60, and the weight ratio of the propanol to the water is 0.15.
Crystallizing the crude adipic acid solution at 30 ℃ for 40 minutes, performing centrifugal separation, and performing vacuum drying at 60 ℃ for 3 hours to obtain refined adipic acid with the purity of 99.99%.
The D50 size of adipic acid crystal particles measured by a laser particle size method is 2192 microns.
The main experimental conditions and experimental results are listed in table 1 for convenience of comparison.
[ example 5 ] A method for producing a polycarbonate
Taking water, propionic acid and a crude adipic acid solid (the mass content of adipic acid in the crude adipic acid is 99.41%), uniformly stirring and heating to 55 ℃ to dissolve to obtain a crude adipic acid solution, wherein the weight ratio of the crude adipic acid to water in the crude adipic acid solution is 0.30, and the weight ratio of propionic acid to water in the crude adipic acid solution is 0.20.
Crystallizing the crude adipic acid solution at 15 ℃ for 40 minutes, performing centrifugal separation, and performing vacuum drying at 60 ℃ for 3 hours to obtain refined adipic acid with the purity of 99.97%.
The D50 size of the adipic acid crystal particles was 3107 microns as determined by laser granulometry.
The main experimental conditions and experimental results are listed in table 1 for convenience of comparison.
[ example 6 ]
Taking water, ethanol and crude adipic acid solid (the mass content of adipic acid in the crude adipic acid is 90.52%), uniformly stirring and heating to 75 ℃ to dissolve to obtain a crude adipic acid solution, wherein the weight ratio of the crude adipic acid to the water in the crude adipic acid solution is 0.70, and the weight ratio of the ethanol to the water in the crude adipic acid solution is 0.15.
Crystallizing the crude adipic acid solution at 15 ℃ for 40 minutes, performing centrifugal separation, and performing vacuum drying at 60 ℃ for 3 hours to obtain refined adipic acid with the purity of 99.98%.
The D50 size of the adipic acid crystal particles was 1025 μm as measured by laser granulometry.
The main experimental conditions and experimental results are listed in table 1 for convenience of comparison.
[ example 7 ] A method for producing a polycarbonate
Taking water, acetic acid and crude adipic acid solid (the mass content of adipic acid in the crude adipic acid is 99.41%), uniformly stirring and heating to 80 ℃ to dissolve to obtain a crude adipic acid solution, wherein the weight ratio of the crude adipic acid to the water in the crude adipic acid solution is 0.75, and the weight ratio of the acetic acid to the water is 0.20.
Crystallizing the crude adipic acid solution at 10 ℃ for 40 minutes, performing centrifugal separation, and performing vacuum drying at 60 ℃ for 3 hours to obtain refined adipic acid, wherein the purity of the refined adipic acid is 99.98%.
The D50 size of the adipic acid crystal particles measured by a laser particle size method was 2002. Mu.m.
The main experimental conditions and experimental results are listed in table 1 for convenience of comparison.
[ COMPARATIVE EXAMPLE 1 ]
The main difference from the above examples 1 to 7 is that the crystallization solvent uses only water and no additive, specifically:
taking water and crude adipic acid solid (the purity of adipic acid is 90.52%), uniformly stirring, heating to 60 ℃ to dissolve to obtain a crude adipic acid solution, wherein the weight ratio of the crude adipic acid to the water in the crude adipic acid solution is 0.40, crystallizing the crude adipic acid solution at 20 ℃ for 40 minutes, centrifuging, and drying in vacuum at 60 ℃ for 3 hours to obtain fine adipic acid, and the purity of the fine adipic acid is 99.51%.
The D50 size of the adipic acid crystal particles was 412 microns as determined by laser granulometry.
The main experimental conditions and experimental results are listed in table 1 for convenience of comparison.
[ COMPARATIVE EXAMPLE 2 ]
The main difference from the above examples 1 to 7 is that the crystallization solvent is acetic acid only, specifically:
taking acetic acid and crude adipic acid solid (the purity of adipic acid is 90.52%), uniformly stirring, heating to 60 ℃ and dissolving to obtain a crude adipic acid solution, wherein the weight ratio of the crude adipic acid to the acetic acid in the crude adipic acid solution is 0.36, crystallizing the crude adipic acid solution for 40 minutes at 20 ℃, performing centrifugal separation, and performing vacuum drying at 60 ℃ for 3 hours to obtain refined adipic acid, wherein the purity of the refined adipic acid is 99.62%.
The D50 size of the adipic acid crystal particles measured by a laser granulometry method was 507. Mu.m.
The main experimental conditions and experimental results are listed in table 1 for convenience of comparison.
[ COMPARATIVE EXAMPLE 3 ]
Taking water, acetic acid and crude adipic acid solid (the mass content of adipic acid in the crude adipic acid is 90.52%), uniformly stirring and heating to 60 ℃ to dissolve to obtain a crude adipic acid solution, wherein the weight ratio of the crude adipic acid to the water in the crude adipic acid solution is 0.40, and the weight ratio of the acetic acid to the water is 1.00.
Crystallizing the crude adipic acid solution at 20 ℃ for 40 minutes, performing centrifugal separation, and performing vacuum drying at 60 ℃ for 3 hours to obtain refined adipic acid, wherein the purity of the refined adipic acid is 99.73%.
The D50 size of adipic acid crystal particles measured by a laser particle size method was 703 μm.
The main experimental conditions and experimental results are listed in table 1 for convenience of comparison.
For comparison, the main process conditions and experimental results are listed in table 1. While the particular process for enlarging solid particles of adipic acid proposed by the present invention has been described in terms of preferred embodiments, it will be apparent to those skilled in the art that the techniques of the present invention may be practiced with modification, or with appropriate modification and combination, of the structures and methods of preparation described herein without departing from the spirit, scope, or concept of the invention. It is expressly intended that all such similar substitutes and modifications apparent to those skilled in the art are deemed to be within the spirit, scope and content of the invention.
TABLE 1
Claims (9)
1. A method for purifying adipic acid, comprising:
(1) Obtaining a crude adipic acid solution;
(2) Cooling and crystallizing;
(3) Carrying out solid-liquid separation to obtain refined adipic acid crystals;
wherein the solvent used by the crude adipic acid solution comprises an additive and water, the additive is alcohol, and the weight ratio of the additive to the water is 0.05-0.25;
the alcohol as additive is C 1 ～C 3 The alcohol of (1).
2. A purification process according to claim 1, wherein the alcohol as an additive is a monohydric alcohol.
3. The method according to claim 2, wherein the alcohol is at least one selected from the group consisting of methanol, ethanol, propanol and isopropanol.
4. The purification process as claimed in claim 1, wherein the mass ratio of adipic acid to water in said crude adipic acid solution is 0.20 to 0.75.
5. The method according to claim 1, wherein the temperature of the crude adipic acid solution in the step (1) is 50 to 80 ℃.
6. The purification process as claimed in claim 1, wherein the crystallization temperature in the step (2) is 10 to 30 ℃.
7. A purification process as claimed in claim 1, wherein said adipic acid is contained in the crude adipic acid in an amount of at least 85% by weight in step (1).
8. The method according to claim 1, wherein the solid-liquid separation is centrifugation and/or filtration.
9. The purification process as claimed in claim 1, wherein the purified adipic acid crystals obtained in the step (3) have a D50 of at least 1000 μm as measured by a laser particle size method.
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB791957A (en) * | 1953-08-27 | 1958-03-19 | Du Pont | Adipic acid crystallization |
| GB989437A (en) * | 1961-02-16 | 1965-04-14 | Halcon International Inc | A process for the purification of adipic acid |
| CN1323288A (en) * | 1998-09-14 | 2001-11-21 | 罗狄亚纤维与树脂中间体公司 | Method for crystallising carboxylic acid |
| CN106810442A (en) * | 2016-12-26 | 2017-06-09 | 河南神马尼龙化工有限责任公司 | A kind of production method of high-quality adipic acid |
| CN106905139A (en) * | 2017-02-20 | 2017-06-30 | 苏州博洋化学股份有限公司 | A kind of high-purity adipic acid extraction process |
-
2019
- 2019-09-04 CN CN201910829935.3A patent/CN112441913B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB791957A (en) * | 1953-08-27 | 1958-03-19 | Du Pont | Adipic acid crystallization |
| GB989437A (en) * | 1961-02-16 | 1965-04-14 | Halcon International Inc | A process for the purification of adipic acid |
| CN1323288A (en) * | 1998-09-14 | 2001-11-21 | 罗狄亚纤维与树脂中间体公司 | Method for crystallising carboxylic acid |
| CN106810442A (en) * | 2016-12-26 | 2017-06-09 | 河南神马尼龙化工有限责任公司 | A kind of production method of high-quality adipic acid |
| CN106905139A (en) * | 2017-02-20 | 2017-06-30 | 苏州博洋化学股份有限公司 | A kind of high-purity adipic acid extraction process |
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