CN114685261A - Refining method of long-chain dicarboxylic acid - Google Patents
Refining method of long-chain dicarboxylic acid Download PDFInfo
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- CN114685261A CN114685261A CN202011594447.8A CN202011594447A CN114685261A CN 114685261 A CN114685261 A CN 114685261A CN 202011594447 A CN202011594447 A CN 202011594447A CN 114685261 A CN114685261 A CN 114685261A
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- OFOBLEOULBTSOW-UHFFFAOYSA-N Malonic acid Chemical compound OC(=O)CC(O)=O OFOBLEOULBTSOW-UHFFFAOYSA-N 0.000 title claims abstract description 104
- 238000000034 method Methods 0.000 title claims abstract description 70
- 238000007670 refining Methods 0.000 title claims abstract description 29
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 claims abstract description 149
- 238000001816 cooling Methods 0.000 claims abstract description 98
- 239000013078 crystal Substances 0.000 claims abstract description 87
- 238000002425 crystallisation Methods 0.000 claims abstract description 81
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 81
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- 238000010438 heat treatment Methods 0.000 claims description 12
- 150000001991 dicarboxylic acids Chemical class 0.000 claims description 10
- 230000008859 change Effects 0.000 claims description 8
- 239000000706 filtrate Substances 0.000 claims description 8
- 238000000746 purification Methods 0.000 claims description 7
- 239000003463 adsorbent Substances 0.000 claims description 6
- 238000005352 clarification Methods 0.000 claims description 4
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- 238000005406 washing Methods 0.000 claims description 4
- 150000001298 alcohols Chemical class 0.000 claims description 2
- 150000001299 aldehydes Chemical class 0.000 claims description 2
- 239000007864 aqueous solution Substances 0.000 claims description 2
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- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 25
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- 229910052799 carbon Inorganic materials 0.000 description 15
- 238000004321 preservation Methods 0.000 description 11
- WMRCTEPOPAZMMN-UHFFFAOYSA-N 2-undecylpropanedioic acid Chemical compound CCCCCCCCCCCC(C(O)=O)C(O)=O WMRCTEPOPAZMMN-UHFFFAOYSA-N 0.000 description 10
- 239000011148 porous material Substances 0.000 description 9
- WNLVXSRACLAFOL-UHFFFAOYSA-N tetradeca-2,4-dienoic acid Chemical compound CCCCCCCCCC=CC=CC(O)=O WNLVXSRACLAFOL-UHFFFAOYSA-N 0.000 description 9
- RZUDZAJRBFRQLS-UHFFFAOYSA-N 2-dodecylpropanedioic acid Chemical compound CCCCCCCCCCCCC(C(O)=O)C(O)=O RZUDZAJRBFRQLS-UHFFFAOYSA-N 0.000 description 8
- 241001052560 Thallis Species 0.000 description 7
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- XBDQKXXYIPTUBI-UHFFFAOYSA-N dimethylselenoniopropionate Natural products CCC(O)=O XBDQKXXYIPTUBI-UHFFFAOYSA-N 0.000 description 2
- POULHZVOKOAJMA-UHFFFAOYSA-N dodecanoic acid Chemical compound CCCCCCCCCCCC(O)=O POULHZVOKOAJMA-UHFFFAOYSA-N 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 230000002349 favourable effect Effects 0.000 description 2
- BDAGIHXWWSANSR-UHFFFAOYSA-N formic acid Substances OC=O BDAGIHXWWSANSR-UHFFFAOYSA-N 0.000 description 2
- 238000011031 large-scale manufacturing process Methods 0.000 description 2
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- 229920000642 polymer Polymers 0.000 description 2
- 238000011085 pressure filtration Methods 0.000 description 2
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- 239000002994 raw material Substances 0.000 description 2
- 238000003828 vacuum filtration Methods 0.000 description 2
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- 208000032544 Cicatrix Diseases 0.000 description 1
- 239000004831 Hot glue Substances 0.000 description 1
- 239000005639 Lauric acid Substances 0.000 description 1
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 150000001335 aliphatic alkanes Chemical class 0.000 description 1
- 150000001413 amino acids Chemical class 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 description 1
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- 230000007547 defect Effects 0.000 description 1
- 230000007812 deficiency Effects 0.000 description 1
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- 125000001142 dicarboxylic acid group Chemical group 0.000 description 1
- 235000014113 dietary fatty acids Nutrition 0.000 description 1
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- 239000001963 growth medium Substances 0.000 description 1
- OOJGMLFHAQOYIL-UHFFFAOYSA-N hexadeca-2,4-dienoic acid Chemical compound CCCCCCCCCCCC=CC=CC(O)=O OOJGMLFHAQOYIL-UHFFFAOYSA-N 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
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- 229910017604 nitric acid Inorganic materials 0.000 description 1
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- 150000007523 nucleic acids Chemical class 0.000 description 1
- 102000039446 nucleic acids Human genes 0.000 description 1
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- 102000004169 proteins and genes Human genes 0.000 description 1
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- IUVKMZGDUIUOCP-BTNSXGMBSA-N quinbolone Chemical compound O([C@H]1CC[C@H]2[C@H]3[C@@H]([C@]4(C=CC(=O)C=C4CC3)C)CC[C@@]21C)C1=CCCC1 IUVKMZGDUIUOCP-BTNSXGMBSA-N 0.000 description 1
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- -1 tridecyl dicarboxylic acid Chemical compound 0.000 description 1
- 238000000108 ultra-filtration Methods 0.000 description 1
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
- C07C51/02—Preparation of carboxylic acids or their salts, halides or anhydrides from salts of carboxylic acids
-
- C—CHEMISTRY; METALLURGY
- 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
- C07C51/43—Separation; Purification; Stabilisation; Use of additives by change of the physical state, e.g. crystallisation
-
- C—CHEMISTRY; METALLURGY
- 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
- C07C51/47—Separation; Purification; Stabilisation; Use of additives by solid-liquid treatment; by chemisorption
Abstract
The invention provides a refining method of long-chain dicarboxylic acid, which comprises the processes of pretreatment, acidification, decoloration, crystallization and recrystallization, wherein the crystallization process adopts a mode of adding water into an acetic acid solution, the solubility of the long-chain dicarboxylic acid is reduced, the solution system is stimulated to form dicarboxylic acid microcrystals by local cooling, the trend of slowing down the temperature reduction speed is taken as a control index, and the crystallization control mode of temperature control and stirring control is combined to obtain the long-chain dicarboxylic acid crystals with larger particle size and uniformity. In the recrystallization process, a polar solvent which can dissolve the long-chain dicarboxylic acid easily is added in addition to water, so that the solubility of the long-chain dicarboxylic acid which is difficult to dissolve in water is increased, fine crystals or microcrystals are eliminated, the solid-liquid separation efficiency in the later period is improved, and the product quality is improved.
Description
Technical Field
The invention relates to a method for refining long-chain dicarboxylic acid, in particular to a method for refining long-chain dicarboxylic acid in biological fermentation liquor.
Background
The long-chain dicarboxylic acid has two terminal carboxyl groups, so that the long-chain dicarboxylic acid is an important monomer raw material for synthesizing polymers such as high-performance engineering plastics, high-grade hot melt adhesives and the like.
Long chain dicarboxylic acids are metabolites of microbial fermentation. The fermentation liquor has complex composition, contains organic and inorganic substances such as microbial cells, cell fragments, culture media, proteins, amino acids, sugars, nucleic acids, lipids and the like, and the types and the contents of impurities change continuously along with time and conditions, which all bring challenges for refining to obtain polymer-grade products.
Solvent recrystallization is a common technique for refining high-quality chemicals at present. The product prepared by the method has the advantages of high purity, good quality, capability of meeting the requirements of polymer grade and the like. The general technical process comprises the following steps: mixing the solvent and the crude raw material, dissolving, adsorbing impurities, crystallizing and the like. The polymer-grade long-chain dicarboxylic acid product is also produced by adopting a solvent recrystallization method, the industry mainly adopts a recrystallization refining method taking acetic acid as a solvent, and the process flow comprises the following steps: dissolving crude long-chain dicarboxylic acid with acetic acid, adsorbing with activated carbon, crystallizing, and the like. In the implementation process of the refining process, part of impurities in the crude long-chain dicarboxylic acid are adsorbed by activated carbon, and part of impurities are dissolved in a solvent in the crystallization process. However, the presently disclosed acetic acid process patents suffer from a number of deficiencies, particularly in the feasibility of implementing crystallization control processes. In the patent of disclosing acetic acid and the like as solvent for refining long-chain dicarboxylic acid, for example, in the patent of CN 201010160266.4, clear solution of dibasic acid is put into a primary crystallizing tank, cooled to 75-85 ℃, kept for 1-2 hours and then cooled to 25-35 ℃. In the process of crystallization, seed crystals are not added for temperature reduction crystallization control. The long-chain dicarboxylic acid is difficult to spontaneously generate crystal nuclei in an acetic acid solution, and induced crystallization needs to be carried out under the action of an external source. In the cooling crystallization process, when crystal nuclei do not exist as attachment of crystal growth, crystals preferentially grow on a cooling interface, finally, long-chain dicarboxylic acid forms thick crystal scale on the inner wall of a crystallizer, so that the cooling heat transfer efficiency is low, crystals obtained in the cooling crystallization process without crystal seeds are different in size, and when massive crystal scale falls off under the stirring effect, pipelines are blocked, and the subsequent solid-liquid separation and production stability are affected. In the patent of CN201711410722.4, 0.1-1% of refined long-chain dicarboxylic acid is added as seed crystal in the crystallization process for induced cooling crystallization. However, the operation process is difficult to be effectively implemented, because the seed crystal is fine powder, when the seed crystal is added into a crystallization tank which is used for containing high-temperature acetic acid and has micro positive pressure to be crystallized, the powder seed crystal is easy to be blown out by acetic acid steam with positive pressure, and the powder seed crystal is easy to be soaked and agglomerated by acetic acid to block a feed inlet, thereby bringing uncertainty and operation danger for crystallization control.
In the patent disclosed in the above-mentioned patent for recrystallization refining of long-chain dicarboxylic acid from acetic acid as a solvent, regarding the crystallization process control, only in a wide temperature range, seed crystals are added or not added, the temperature is maintained, and then the temperature is directly lowered or the temperature is lowered in stages for crystallization, and there is no method for controlling crystallization which is easy to implement and has a relatively precise control, which is disadvantageous in the reproducibility and reproducibility of the production process and the product quality. As is well known to those skilled in the art, the crystallization process control is a key technology for refining long-chain dicarboxylic acid by using acetic acid solvent, and in order to obtain an ideal crystallization state, seed crystals need to be added at a proper time, namely when the long-chain dicarboxylic acid in the acetic acid solution is supersaturated, the seed crystals are added, the seed crystals are dissolved and cannot perform the function of inducing crystallization, and when the seed crystals are added too late, a large amount of crystal nuclei are easily generated in a system, so that fine crystals are agglomerated to form needle-shaped or sheet-shaped crystals, and the product purity and the subsequent filtering and drying processes are affected. In large-scale production, the addition of seed crystals to control the crystallization process is difficult to operate, the solvent and the solute need to be accurately metered, and expensive detection equipment is needed to analyze and judge the seed crystal addition time, so that the cost is increased, and the production efficiency is reduced. And crystallization without seeding is obviously disadvantageous for large-scale production.
In the disclosed patents on the purification of long-chain dicarboxylic acids using acetic acid or the like as a solvent, no solution is proposed to eliminate or reduce the crystallites and the fine crystals in the subsequent step of the crystallization of the long-chain dicarboxylic acid. Patent CN 201010160266.4 discloses that the crystallized material is put into a high-temperature water crystallizing tank, the temperature is controlled to be 70-100 ℃, and the refined product is obtained through heat preservation, temperature reduction, centrifugal separation and drying. Patent CN201711410722.4 discloses that in a centrifuge, a long-chain dicarboxylic acid crystalline material is first rinsed with acetic acid, then with water, then slurried with deionized water, then sent to a water washing tank, added with room temperature deionized water for stirring and washing, and finally subjected to centrifugal filtration and drying to obtain a refined product. Those skilled in the art will appreciate that the size of the crystallized particles is related to the concentration of the solute, the long chain dibasic acid is gradually precipitated during the cooling crystallization process, the concentration of the solute in the solvent is gradually reduced, the particle size of the later precipitated crystals is gradually reduced until microcrystals or fine crystals are formed, and the fine crystals and the microcrystals formed by the collision between the crystals are increased during the crystallization stirring process and the material conveying process after the crystallization. Since the long-chain dicarboxylic acid is a very insoluble substance in water (e.g., lauric acid has a solubility in water of 0.007g/100 g), even if the long-chain dicarboxylic acid is suspended again in water, the micro-crystals or fine-crystals cannot be eliminated. Because the surface area of the microcrystal or the fine crystal is larger, the quantity of adsorbed impurities is increased to influence the product quality, a dust recovery filter screen of a dryer is extremely easy to block during drying to influence the production stability, or even the microcrystal penetrates through the filter screen to cause product loss, and meanwhile, because the product dust is more, the long-chain dicarboxylic acid powder is easy to generate electrostatic accumulation in the drying and packaging process and the conveying process, and the dust explosion is easy to cause safety risks.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a refining method of long-chain dicarboxylic acid, which optimizes the crystallization process and recrystallization of the dicarboxylic acid, so that the crystallization is easier to control, the crystallization effect is stable, and the difficulty of the crystallization and recrystallization operations is reduced.
The molecular general formula of the long-chain dicarboxylic acid is C8-C18nH2n-2O4Wherein n is 8-18, and is a metabolite produced by fermentation of carbon sources such as alkane or fatty acid by microorganisms.
As is well known to those skilled in the art, the long chain dicarboxylic acid solvent recrystallization process involves: the main processes of dissolving crude long-chain dicarboxylic acid by acetic acid, adsorbing by activated carbon and crystallizing, wherein the dissolving and the adsorbing by activated carbon are conventional operation processes, the control of the crystallizing process is a key technology of the process, and the step is not only required to obtain cleaner products, but also required to be easy to implement the control operation. The inventor unexpectedly discovers in research that a certain amount of water is added into the system at a certain speed in the process of cooling, when the temperature cooling speed of the solution system is reduced, tiny long-chain dicarboxylic acid crystal nuclei appear in the acetic acid solution, and at the moment, an inflection point appears in the temperature of the system, the temperature reduction range is small, and the temperature is prone to increase. The inventor adds acetic acid solution into water flow to initiate crystal nucleus, slows down the mark as crystal nucleus appearance and key parameters of crystal growth control at a temperature rate, combines heat preservation and program cooling control measures, establishes a crystallization control method which is easy to operate and realize, obtains long-chain dicarboxylic acid particle crystals reaching a polymerization level, and has higher crystallization yield than a crystallization process without water. Compared with the prior art, the method has the advantages of controllable implementation, no crystal scale generation, higher crystallization yield, product meeting the polymerization requirement and the like.
In order to achieve the purpose, the technical scheme of the invention is as follows:
a method for refining long-chain dicarboxylic acid, comprising the steps of:
I. pretreating the fermentation broth, and removing solids to obtain a filtrate containing long-chain dicarboxylic acid salt;
II. Adding acid into the long-chain dicarboxylic acid salt filtrate to convert the long-chain dicarboxylic acid salt into long-chain dicarboxylic acid and completely separate out the long-chain dicarboxylic acid salt from the aqueous solution, and filtering to obtain a long-chain dicarboxylic acid filter cake;
III, adding acetic acid into the long-chain dicarboxylic acid filter cake, heating to dissolve the long-chain dicarboxylic acid, and filtering for clarification; adding an adsorbent into the filtrate to remove solid matters, so as to obtain an acetic acid solution in which the long-chain dicarboxylic acid is dissolved;
IV, cooling the acetic acid solution obtained in the step III to 70-75 ℃, then closing a crystallization temperature control facility, beginning to add water into the solution system at a constant speed, controlling the cooling speed of the solution to be 0.2-1 ℃/min, preferably 0.2-0.8 ℃/min, more preferably 0.4-0.6 ℃/min, stopping adding water when the current later cooling speed change is more than or equal to 0.1 ℃/min and preferably the front and back cooling speed change is more than or equal to 0.05 ℃/min in the continuous water adding process, keeping the temperature, and then continuously cooling to crystallize the long-chain dicarboxylic acid; carrying out solid-liquid separation to obtain long-chain dicarboxylic acid crystals;
v, adding the long-chain dicarboxylic acid crystals into water again, adding a polar solvent which can easily dissolve the long-chain dicarboxylic acid into the mixed system, heating for washing, keeping the temperature, cooling, and performing solid-liquid separation and drying to obtain a fine long-chain dicarboxylic acid product.
Furthermore, in the step IV, when the cooling speed of the solution is more than or equal to 0.5 ℃/min after the water is added, the water is preferably stopped when the cooling speed is reduced to less than 0.5 ℃/min and the change of the front and back cooling speed is more than or equal to 0.1 ℃/min, and the change of the front and back cooling speed is more than or equal to 0.05 ℃/min.
Further, the heat preservation time after the water addition is stopped in the step IV is 30-60 min, so that the microcrystal in the system grows up.
Further, the stirring is kept in the heat preservation process in the step IV, as a more specific implementation mode, the stirring rotating speed of the system is less than or equal to 50 revolutions per minute, the microcrystal is suspended at a proper rotating speed to be beneficial to crystal growing, and the shearing force generated by an overhigh rotating speed is easy to damage the crystal to form more crystal nuclei, so that the growth of the microcrystal is not beneficial.
Furthermore, the temperature reduction rate of the continuous temperature reduction in the step IV is 7-15 ℃/h, the temperature of the crystallization end point is less than or equal to 20 ℃, the long-chain dicarboxylic acid crystals are in a regular shape, and are not needle-shaped and other fine crystals, so that the subsequent solid-liquid separation operation and the improvement of the product quality are facilitated.
Further, the temperature of water added into the system in the step IV is 7-25 ℃, and the water is deionized water, distilled water or desalted water.
Further, the water is added in the step IV in a manner selected from at least one of feeding, spraying and misting.
Further, in the step IV, the solid-liquid separation is to separate the long-chain dicarboxylic acid crystal from the acetic acid solution by adopting filtering equipment such as centrifugation, pressure, vacuum and the like to obtain the crystal, and the acetic acid solution and a small amount of the long-chain dicarboxylic acid dissolved in the acetic acid solution are recycled.
Further, the crystallization temperature control facility in the step IV refers to equipment applied to crystallization temperature control in the prior art, and is preferably a cooling jacket.
Further, the step IV also comprises a step of adding long-chain dicarboxylic acid seed crystals into the crystallization system, and the addition is preferably stopped before the water addition. The addition amount of the long-chain dicarboxylic acid seed crystals is 0.1-1% of the total amount of long-chain dicarboxylic acid in a crystallization system, preferably 0.1-0.8% of the total amount of long-chain dicarboxylic acid in the crystallization system, and more preferably 0.1-0.5% of the total amount of long-chain dicarboxylic acid in the crystallization system. The crystallization control process of adding water is assisted by adding the seed crystal, so that the crystallization control effect is more stable.
Further, in step V, the long-chain dicarboxylic acid crystals are re-added to water in an amount of 1 times or more, preferably 2 times or more, and more preferably 3 times or more, by weight of the long-chain dicarboxylic acid crystals.
Further, in the step V, the polar solvent in which the long-chain dicarboxylic acid is easily soluble is at least one selected from alcohols, organic acids, esters, ketones, and aldehyde solvents, and preferably acetic acid.
Further, the amount of the polar solvent which is easily soluble in the long-chain dicarboxylic acid in the step V is 1 to 15% by volume of the mixed system formed by the long-chain dicarboxylic acid crystals and water.
Further, in the step V, the temperature is raised to ensure that the heating temperature of the solution is more than or equal to 50 ℃, and preferably 70-100 ℃.
Further, the heat preservation time in the step V is 30-60 min.
And furthermore, in the step V, a program cooling control mode is adopted for cooling, the cooling range is 7-15 ℃/h, and the dissolved long-chain dicarboxylic acid is recrystallized into large particles to be separated out.
Furthermore, the temperature reduction end point in the step V is less than or equal to 20 ℃. And then separating the long-chain dicarboxylic acid crystals from the solution by adopting solid-liquid separation modes such as centrifugation, pressure filtration, vacuum filtration and the like to obtain a wet long-chain dicarboxylic acid product, and drying in a dryer to obtain a fine long-chain dicarboxylic acid product.
Further, in the above method, the pretreatment in step I is to perform solid-liquid separation of solid matters such as bacteria and liquid by using solid-liquid separation equipment and means in the prior art, specifically, flocculation settling, centrifugal filtration, pressure filtration, vacuum filtration, microfiltration, ultrafiltration, and the like.
Further, the fermentation liquid terminated in the step I is a metabolite obtained by microbial fermentation, wherein the long-chain dicarboxylic acid contained in the fermentation liquid has a molecular general formula of CnH2n-2O4Wherein n is 8-18, and can be single long-chain dicarboxylic acid or mixed long-chain dicarboxylic acid.
The acidification in step II can be carried out by methods conventional in the art. Specifically, the pH value of acidification is 2.0-4.0. The acid used for acidification may be any concentration of H2SO4、HNO3、HCl、H3PO4Formic acid, acetic acid or propionic acid, etc. The long-chain dicarboxylic acid obtained by filtering can be directly mixed and dissolved with acetic acid or dried and then mixed and dissolved with the acetic acid.
Further, the amount of acetic acid used in step III is preferably 200% or more by weight of the cake of long-chain dicarboxylic acid.
Further, in the filtration and clarification in the step III, a filter having an aperture of not more than 5 μm is used, preferably an aperture of not more than 0.22 μm is used, and more preferably an aperture of not more than 0.1 μm is used. The inventor finds that the crude dicarboxylic acid is dissolved in an acetic acid solvent, insoluble solid exists in a solution system, the clarity is poor, pore channels of adsorbents such as activated carbon can be blocked, and adsorption and removal of impurities and pigments are not facilitated. In the prior art, the dissolving and the adsorption processes are coupled, and a filtering and clarifying step is rarely adopted before adsorption, so that the adsorption and the removal of impurities and pigments are not facilitated. Through the step of filtering and clarifying, the solution can be further clarified, so that the adsorption efficiency of the subsequent adsorbent is higher, and the quality of the obtained refined dicarboxylic acid is better.
Further, the adsorbent in the step III is selected from adsorbents commonly used in the industry, preferably activated carbon, and the using amount of the activated carbon is 0.1-4.0% of the total amount of the long-chain dicarboxylic acid. The adsorption temperature is more than or equal to 65 ℃, and is preferably 10-30 ℃ higher than the temperature of dissolving the long-chain dicarboxylic acid in the acetic acid.
Further, the solid-liquid mixed solution after adsorption treatment in the step III is subjected to solid-liquid separation and clarification in a graded filtration mode. In a more specific embodiment, a filter medium with a pore size of 10 to 50 μm is used to filter and remove solid matters such as activated carbon to obtain a first-stage filtrate, and a filter medium with a pore size of 0.2 to 1 μm is used to remove the remaining solid matters to obtain a clear and colorless second-stage filtrate.
Compared with the prior art, the invention has the following advantages:
(1) in the refining method, the method of adding water into the acetic acid solution is adopted in the crystallization step, the solubility of the long-chain dicarboxylic acid is reduced, the solution system is stimulated to form dicarboxylic acid microcrystals by locally reducing the temperature, and the crystallization control mode of controlling the temperature and stirring is combined to obtain the long-chain dicarboxylic acid crystals with larger particle size and uniformity by taking the trend of slowing down the temperature reduction speed as a control index. Compared with the mode of adding seed crystal to induce crystallization in the prior art, the mode of adding water to control crystallization has the advantages of good medium fluidity, easy flow addition, easy realization of operation, easy back mixing with acetic acid solution, easy uniform distribution nucleation in a system and crystal formation on the basis. Meanwhile, the cooling capacity brought by water enables the cooling speed of the crystallization system to be higher, so that the phenomenon that crystallization is out of control because crystallization scars are formed on the wall of the crystallization tank jacket due to cooling to influence the cooling speed is prevented. The crystallization process is simple and convenient to control, and has practical application value.
(2) In the refining method, in the recrystallization step, a polar solvent which is easy to dissolve long-chain dicarboxylic acid is additionally added in addition to water, so that the solubility of the long-chain dicarboxylic acid which is difficult to dissolve in water is increased, the dissolution of microcrystals adhered to the surface of a crystal is promoted, the dissolution of crystal powder generated in the solid-liquid separation and conveying processes of the crystal is promoted, the further growth of the dicarboxylic acid microcrystals or fine crystals in water into large-particle crystals is promoted, and the fine crystals or microcrystals are eliminated; the recrystallization process is favorable for improving the solid-liquid separation efficiency in the later period, is favorable for eliminating tiny crystals so as to improve the product quality, and simultaneously, due to the addition of the polar solvent which is easy to dissolve the long-chain dicarboxylic acid, the dissolution of impurities which are chemically bonded with the long-chain dicarboxylic acid and physically adsorbed in water is promoted, and the quality of the dicarboxylic acid product is improved.
(3) By the refining method, the long-chain dicarboxylic acid is separated from impurities more thoroughly, the product is white in color and luster, and has practical application value, the purity of the obtained product is more than 99.5%, the total nitrogen content is less than 20ppm, and the requirements of downstream polymerization application can be met.
Additional features and advantages of the invention will be set forth in the detailed description which follows.
Detailed Description
The following non-limiting examples are presented to enable those of ordinary skill in the art to more fully understand the present invention and are not intended to limit the invention in any way.
The following examples and comparative examples respectively show the technical scheme of the present invention and the purification method of long chain dicarboxylic acid in the prior art:
example 1
I. Filtering the fermentation liquor containing deca-carbo-carboxylic acid to remove solid impurities such as thalli;
II. Adding sulfuric acid into the product I to separate out deca-carbo-xylic acid, and filtering to obtain a crude deca-carbo-carboxylic acid filter cake;
III, adding 50 liters of acetic acid into a 100L dissolving kettle, adding 25kg of deca-dicarboxylic acid crude product, heating to 83 ℃, keeping the temperature and stirring for 20min to fully dissolve the dibasic acid, clarifying the solution by a 0.1-micron pore size filter, and then feeding the solution into a decoloring kettle. Adding 0.25kg of active carbon into a decoloring kettle, uniformly stirring, adsorbing for 30 minutes at 82 ℃, allowing a decoloring solution to pass through a 10-micron filter and a 0.2-micron filter in sequence, and allowing a deca-dicarboxylic acid solution to enter a crystallization kettle.
And IV, starting a cooling system of the crystallization kettle, cooling the solution to be crystallized to 72 ℃ under stirring, closing the cooling system, adding 20 ℃ desalted water at a constant speed in a flowing manner, controlling the cooling rate of the system to be 0.6 ℃/min, reducing the temperature of the system along with the constant speed in the flowing manner, beginning to separate out the deca-dicarboxylic acid with the reduction of the solubility, discharging a small amount of heat, reducing the temperature drop in the kettle, continuing to add water in the flowing manner, continuing to separate out the deca-dicarboxylic acid, closing a desalted water flow electromagnetic valve when the temperature drop in the kettle is reduced from 0.5 ℃/min to 0.4 ℃/min, starting a heat preservation mode, controlling the stirring speed, preserving the heat for 30min, starting the cooling system, starting a program to cool, controlling the cooling amplitude to be 8 ℃/h, and finally cooling to be 20 ℃. And (3) carrying out solid-liquid separation on the crystallization liquid, wherein the deca-carbon carboxylic acid crystals are in regular particles, the separation operation is convenient, the filtering speed is high, the water content is low, and the deca-carbon carboxylic acid crystal filter cake is obtained.
V, conveying the filter cake to a recrystallization tank, adding 50L of desalted water into the recrystallization tank, adding 6L of acetic acid, keeping the temperature at 50 ℃, stirring for 40 revolutions per minute, preserving heat for 60min, starting a program to cool, controlling the cooling amplitude at 8 ℃/h, and cooling to 20 ℃. And (4) carrying out solid-liquid separation to obtain a deca-carbon dicarboxylic acid wet filter cake, and drying by using a dryer to obtain the refined deca-carbon dicarboxylic acid. The quality indexes of the refined deca-carbolic acid products are shown in Table 1.
Example 2
I. Filtering the fermentation liquor containing the dodecacarbolic acid to remove solid impurities such as thalli and the like;
II. Adding sulfuric acid into the product I to separate out the dodecacarbolic acid, and filtering to obtain a crude dodecacarbolic acid filter cake;
III, putting 55 liters of acetic acid into a 100L dissolving kettle, adding 25kg of crude dodecanedicarboxylic acid, heating to 87 ℃, keeping the temperature and stirring for 20min to fully dissolve the dibasic acid, and clarifying the solution through a 0.1-micron pore filter and then entering a decoloring kettle. Adding 0.4kg of active carbon into a decoloring kettle, uniformly stirring, adsorbing at 84 ℃ for 30 minutes, passing a decoloring solution through a 10-micron filter and a 0.2-micron filter in sequence, and feeding a dodecanedicarboxylic acid solution into a crystallization kettle.
And IV, starting a cooling system of the crystallization kettle, cooling the solution to be crystallized to 73 ℃ under stirring, closing the cooling system, adding desalted water of 20 ℃ at a constant speed in a flowing manner, controlling the cooling rate of the system to be 0.6 ℃/min, reducing the cooling rate along with the adding of the desalted water at the constant speed, closing a desalted water flow adding electromagnetic valve when the temperature in the kettle is reduced from 0.4 ℃/min to 0.3 ℃/min, starting a heat preservation mode, controlling the stirring speed, preserving the temperature for 30min, starting the cooling system, starting a program to cool, controlling the cooling amplitude to be 10 ℃/h, and finally cooling to 20 ℃. And (4) carrying out solid-liquid separation on the crystallization liquid, wherein the deca-dicarbonyl carboxylic acid crystals are in regular particles, and the separation operation is convenient, so that a dodeca-dicarbonyl carboxylic acid crystal filter cake is obtained.
V, conveying the filter cake to a recrystallization tank, adding 60L of desalted water into the recrystallization tank, adding 5L of acetic acid, keeping the temperature at 75 ℃, stirring for 40 revolutions per minute, preserving the temperature for 60min, starting a program to cool, controlling the cooling amplitude at 10 ℃/h, and cooling to 20 ℃. And (4) carrying out solid-liquid separation to obtain a dodecacarbolic acid wet filter cake, and drying by using a dryer to obtain the refined dodecacarbolic acid. The quality indexes of the refined dodecanedicarboxylic acid products are shown in Table 1.
Example 3
I. Filtering the fermentation liquor containing the tridecanedicarboxylic acid to remove solid impurities such as thalli and the like;
II. Adding sulfuric acid into the product I to separate out the tridecanedicarboxylic acid, and filtering to obtain a coarse product of a tridecanedicarboxylic acid filter cake;
III, adding 53 liters of acetic acid into a 100L dissolving kettle, adding 23kg of a tridecanedicarboxylic acid crude product, heating to 83 ℃, keeping the temperature and stirring to fully dissolve the dibasic acid, and clarifying the solution through a 0.1 mu m pore size filter and then entering a decoloring kettle. Adding 0.3kg of active carbon into a decoloring kettle, uniformly stirring, adsorbing at 78 ℃ for 30 minutes, passing a decoloring solution through a 10-micron filter and a 0.2-micron filter in sequence, and feeding a tridecanedicarboxylic acid solution into a crystallization kettle.
And IV, starting a cooling system of the crystallization kettle, cooling the solution to be crystallized to 72 ℃ under stirring, closing the cooling system, adding desalted water of 15 ℃ at a constant speed in a flowing manner, controlling the cooling rate of the system to be 0.5 ℃/min, reducing the cooling rate along with the adding of the desalted water at the constant speed, closing a desalted water flow adding electromagnetic valve when the temperature in the kettle is reduced to 0.2 ℃/min from 0.3 ℃/min, starting a heat preservation mode, controlling the stirring speed, preserving the heat for 50min, starting the cooling system, starting a program to cool, controlling the cooling amplitude to be 10 ℃/h, and finally cooling to 20 ℃. And (4) carrying out solid-liquid separation on the crystallization liquid, wherein the deca-carbon dicarboxylic acid crystals are in regular particles, and the separation operation is convenient, so that a tridecyl dicarboxylic acid crystal filter cake is obtained.
V, conveying the filter cake to a recrystallization tank, adding 55L of desalted water into the recrystallization tank, adding 8L of acetic acid, maintaining the temperature at 65 ℃, stirring at 40 revolutions per minute, keeping the temperature for 60min, starting a program to cool, controlling the cooling amplitude at 10 ℃/h, and cooling to 20 ℃. And (4) carrying out solid-liquid separation to obtain a tridecanedicarboxylic acid wet filter cake, and drying by using a dryer to obtain refined tridecanedicarboxylic acid. The quality indexes of the refined tridecanedicarboxylic acid products are shown in Table 1.
Example 4
I. Filtering the fermentation liquor containing the tetradecadienoic acid to remove solid impurities such as thalli and the like;
II. Adding sulfuric acid into the product I to separate out tetradecadienoic acid, and filtering to obtain a crude tetradecadienoic acid filter cake;
III, adding 55 liters of acetic acid into a 100L dissolving kettle, adding 26kg of crude tetradecadienoic acid, heating to 90 ℃, keeping the temperature and stirring to fully dissolve the dibasic acid, and clarifying the solution through a 0.1-micron pore filter and then feeding the solution into a decoloring kettle. Adding 0.2kg of active carbon into a decoloring kettle, uniformly stirring, adsorbing at 87 ℃ for 30 minutes, passing a decoloring solution through a 10-micron filter and a 0.2-micron filter in sequence, and feeding a tetradecadienoic acid solution into a crystallization kettle.
And IV, starting a cooling system of the crystallization kettle, cooling the solution to be crystallized to 75 ℃ under stirring, closing the cooling system, adding desalted water of 20 ℃ at a constant speed in a flowing manner, controlling the cooling rate of the system to be 0.4 ℃/min, reducing the cooling rate along with the adding of the desalted water at the constant speed, closing a desalted water flow adding electromagnetic valve when the temperature in the kettle is reduced to 0.1 ℃/min from 0.2 ℃/min, starting a heat preservation mode, controlling the stirring speed, preserving the heat for 40min, starting the cooling system, starting a program to cool, controlling the cooling amplitude to be 12 ℃/h, and finally cooling to 20 ℃. And (4) carrying out solid-liquid separation on the crystallization liquid, wherein the deca-carbon carboxylic acid crystals are regular particles, and the separation operation is convenient, so that a tetradecadienoic acid crystal filter cake is obtained.
V, conveying the filter cake to a recrystallization tank, adding 60L of desalted water into the recrystallization tank, adding 11L of acetic acid, keeping the temperature at 80 ℃, stirring for 40 revolutions per minute, preserving the temperature for 60min, starting a program to cool, controlling the cooling amplitude at 12 ℃/h, and cooling to 20 ℃. And (4) carrying out solid-liquid separation to obtain a tetradecadienoic acid wet filter cake, and drying by using a dryer to obtain the refined tetradecadienoic acid. The quality indexes of the refined tetradecadienoic acid products are shown in Table 1.
Example 5
I. Filtering the fermentation liquor containing the pentadecacarbo-carboxylic acid, and removing solid impurities such as thalli and the like;
II. Adding sulfuric acid into the product I to separate out pentadecacarbo-carboxylic acid, and filtering to obtain a pentadecacarbo-carboxylic acid filter cake crude product;
and III, adding 60 liters of acetic acid into a 100L dissolving kettle, adding 25kg of crude pentadecacarbodicarboxylic acid, heating to 86 ℃, keeping the temperature and stirring to fully dissolve the dibasic acid, and clarifying the solution by a 0.1-micron pore filter and then feeding the solution into a decoloring kettle. Adding 0.3kg of activated carbon into a decoloring kettle, uniformly stirring, adsorbing at 80-85 ℃ for 30 minutes, allowing a decoloring solution to pass through a 10-micron filter and a 0.2-micron filter in sequence, and allowing a pentadecadienecarboxylic acid solution to enter a crystallization kettle.
And IV, starting a cooling system of the crystallization kettle, cooling the solution to be crystallized to 74 ℃ under stirring, closing the cooling system, adding desalted water of 20 ℃ at a constant speed in a flowing manner, controlling the cooling rate of the system to be 0.6 ℃/min, reducing the cooling rate along with the adding of the desalted water at the constant speed, closing a desalted water flow adding electromagnetic valve when the temperature in the kettle is reduced from 0.5 ℃/min to 0.2 ℃/min, starting a heat preservation mode, controlling the stirring speed, preserving the heat for 60min, starting the cooling system, starting a program to cool, controlling the cooling amplitude to be 10 ℃/h, and finally cooling to 20 ℃. And (4) carrying out solid-liquid separation on the crystallization liquid, wherein the deca-carbon carboxylic acid crystals are in regular particles, and the separation operation is convenient, so that a pentadeca-carbon carboxylic acid crystal filter cake is obtained.
V, conveying the filter cake to a recrystallization tank, adding 60L of desalted water into the recrystallization tank, adding 9L of acetic acid, keeping the temperature at 83 ℃, stirring for 40 revolutions per minute, preserving the temperature for 60min, starting a program to cool, controlling the cooling amplitude at 10 ℃/h, and cooling to 20 ℃. And (4) carrying out solid-liquid separation to obtain a pentadecacarbolic acid wet filter cake, and drying by using a dryer to obtain the refined pentadecacarbolic acid. The quality indexes of the refined pentadecacarbodicarboxylic acid products are shown in Table 1.
Example 6
I. Filtering the fermentation liquor containing the dodecacarbolic acid to remove solid impurities such as thalli and the like;
II. Adding sulfuric acid into the product I to separate out the dodecacarbolic acid, and filtering to obtain a crude dodecacarbolic acid filter cake;
III, putting 55 liters of acetic acid into a 100L dissolving kettle, adding 25kg of crude dodecanedicarboxylic acid, heating to 87 ℃, keeping the temperature and stirring for 20min to fully dissolve the dibasic acid, and clarifying the solution through a 0.1-micron pore filter and then entering a decoloring kettle. Adding 0.4kg of active carbon into a decoloring kettle, uniformly stirring, adsorbing at 84 ℃ for 30 minutes, passing a decoloring solution through a 10-micron filter and a 0.2-micron filter in sequence, and feeding a dodecanedicarboxylic acid solution into a crystallization kettle.
And IV, starting a cooling system of the crystallization kettle, cooling the solution to be crystallized to 73 ℃ under stirring, closing the cooling system, adding 20 ℃ desalted water at a constant speed in a flowing manner, controlling the cooling rate of the system to be 0.6 ℃/min, adding desalted water along with the constant speed in the flowing manner, reducing the cooling rate, adding 50g of dodecacarboncarboxylic acid seed crystal when the temperature in the kettle is reduced to 0.3 ℃/min from 0.4 ℃/min, closing the desalted water flowing and adding electromagnetic valve, starting a heat preservation mode, controlling the stirring speed, preserving the heat for 30min, opening the cooling system, starting a program to cool, controlling the cooling amplitude to be 10 ℃/h, and finally cooling to 20 ℃. And (4) carrying out solid-liquid separation on the crystallization liquid, wherein the deca-dicarbonyl carboxylic acid crystals are in regular particles, and the separation operation is convenient, so that a dodeca-dicarbonyl carboxylic acid crystal filter cake is obtained.
V, conveying the filter cake to a recrystallization tank, adding 60L of desalted water into the recrystallization tank, adding 5L of acetic acid, keeping the temperature at 75 ℃, stirring for 40 revolutions per minute, preserving the temperature for 60min, starting a program to cool, controlling the cooling amplitude at 10 ℃/h, and cooling to 20 ℃. And (4) carrying out solid-liquid separation to obtain a dodecacarbolic acid wet filter cake, and drying by using a dryer to obtain the refined dodecacarbolic acid. The quality indexes of the refined dodecanedicarboxylic acid products are shown in Table 1.
Comparative example 1
I. Filtering the fermentation liquor containing the dodecacarbolic acid to remove solid impurities such as thalli and the like;
II. Adding sulfuric acid into the product I to separate out the dodecacarbolic acid, and filtering to obtain a crude dodecacarbolic acid filter cake;
and III, putting 55 liters of acetic acid into a 100L dissolving kettle, adding 25kg of crude dodecanedicarboxylic acid, heating to 87 ℃, keeping the temperature and stirring for 20min to fully dissolve the dibasic acid, and feeding the dibasic acid into a decoloring kettle. Adding 0.4kg of active carbon into a decoloring kettle, uniformly stirring, adsorbing at 84 ℃ for 30 minutes, passing a decoloring solution through a 10-micron filter and a 0.2-micron filter in sequence, and feeding a dodecanedicarboxylic acid solution into a crystallization kettle.
And IV, starting a cooling system of the crystallization kettle, adding 200g of dodecanedicarboxylic acid with the purity of more than 99.8 percent as seed crystals when the temperature of the crystallization solution is reduced to 73 ℃ under stirring, controlling the stirring speed to be 40r/min, controlling the temperature in the crystallization kettle to be 75 ℃, then naturally reducing the temperature to 68 ℃, starting the cooling system, and controlling the cooling speed to finally reduce the temperature to 20 ℃. And (4) carrying out solid-liquid separation on the crystallization liquid, wherein the crystallization is irregular crystallization agglomerates, so that the moisture content of a filter cake obtained by filtering is higher, and the dodecacarbolic acid crystal filter cake is obtained.
V, conveying the filter cake to a recrystallization tank, adding 60L of desalted water into the recrystallization tank, keeping the temperature at 90 ℃, stirring for 40r/min, preserving the temperature for 120min, starting a program to cool, and cooling to 30 ℃. And (4) carrying out solid-liquid separation to obtain a dodecacarbolic acid wet filter cake, and drying by using a dryer to obtain the refined dodecacarbolic acid. The quality indexes of the refined dodecanedicarboxylic acid products are shown in Table 1.
Table 1.
Claims (17)
1. A method for refining long-chain dicarboxylic acid, comprising the steps of:
I. pretreating the fermentation broth, and removing solids to obtain a filtrate containing long-chain dicarboxylic acid salt;
II. Adding acid into the long-chain dicarboxylic acid salt filtrate to convert the long-chain dicarboxylic acid salt into long-chain dicarboxylic acid and completely separate out the long-chain dicarboxylic acid salt from the aqueous solution, and filtering to obtain a long-chain dicarboxylic acid filter cake;
III, adding acetic acid into the long-chain dicarboxylic acid filter cake, heating to dissolve the long-chain dicarboxylic acid, and filtering for clarification; adding an adsorbent into the filtrate to remove solid matters, so as to obtain an acetic acid solution in which the long-chain dicarboxylic acid is dissolved;
IV, cooling the acetic acid solution obtained in the step III to 70-75 ℃, closing a crystallization temperature control facility, starting to add water into the solution system at a constant speed, controlling the cooling speed of the solution to be 0.2-1 ℃/min, preferably 0.2-0.8 ℃/min, more preferably 0.4-0.6 ℃/min, stopping adding water when the current rear cooling speed change is more than or equal to 0.1 ℃/min and preferably the front and rear cooling speed change is more than or equal to 0.05 ℃/min in the continuous water adding process, preserving heat, and then continuously cooling to crystallize the long-chain dicarboxylic acid; carrying out solid-liquid separation to obtain long-chain dicarboxylic acid crystals;
v, adding the long-chain dicarboxylic acid crystals into water again, adding a polar solvent which can easily dissolve the long-chain dicarboxylic acid into the mixed system, heating for washing, keeping the temperature, cooling, and performing solid-liquid separation and drying to obtain a fine long-chain dicarboxylic acid product.
2. The refining method of claim 1, wherein in step IV, when the cooling rate of the solution is not less than 0.5 ℃/min after the water addition is started, the water addition is stopped when the cooling rate is decreased to less than 0.5 ℃/min and the change of the cooling rate before and after the water addition is not less than 0.1 ℃/min.
3. The refining method according to claim 1, wherein the holding time after the water addition is stopped in step IV is 30 to 60 min.
4. The refining method of claim 1, wherein the stirring is maintained during the maintaining step in step IV, and the stirring speed of the system is less than or equal to 50 rpm.
5. The refining method of claim 1, wherein the temperature reduction rate of the temperature reduction in step IV is 7-15 ℃/h, and the temperature of the crystallization end point is less than or equal to 20 ℃.
6. The refining method according to claim 1, wherein the temperature of water added to the system in the step IV is 7 to 25 ℃, and the water is deionized water, distilled water or desalted water.
7. The refining method of claim 1, wherein the water is added in step IV by at least one selected from the group consisting of feeding, spraying and misting.
8. The purification process as claimed in claim 1, wherein the step IV further comprises a step of adding a seed crystal of the long-chain dicarboxylic acid to the crystallization system before stopping the addition of water.
9. The refining method according to claim 8, wherein the amount of the seed crystals added is 0.1 to 1% by weight based on the total amount of the long-chain dicarboxylic acid in the crystallization system.
10. The purification process according to claim 1, wherein the long-chain dicarboxylic acid crystals are newly added to water in an amount of 1 times or more by weight of the long-chain dicarboxylic acid crystals in step V.
11. The purification process according to claim 1, wherein the polar solvent which readily dissolves the long-chain dicarboxylic acid in the step V is at least one solvent selected from the group consisting of alcohols, organic acids, esters, ketones and aldehydes.
12. The purification method according to claim 11, wherein the polar solvent in which the long-chain dicarboxylic acid is easily soluble is acetic acid.
13. The purification process according to claim 11 or 12, wherein the amount of the polar solvent which readily dissolves the long-chain dicarboxylic acid in the step V is 1 to 15% by volume based on the volume of the mixed system of the long-chain dicarboxylic acid crystals and water.
14. The refining method according to claim 1, wherein the temperature in step V is raised to a temperature of 50 ℃ or higher.
15. The refining method according to claim 1, wherein the heat-retaining time in step V is 30 to 60 min.
16. The refining method as claimed in claim 1, wherein the temperature reduction in step V is controlled by program temperature reduction, the temperature reduction range is 7-15 ℃/h, and the temperature reduction end point is less than or equal to 20 ℃.
17. The refining process according to claim 1, wherein the amount of acetic acid used in step III is 200% or more by weight of the cake of long-chain dicarboxylic acid.
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| 龚俊波 等: "长链二元酸的水相反应结晶过程研究", 《天津大学学报(自然科学与工程技术版)》, vol. 51, no. 8, 31 August 2018 (2018-08-31), pages 2 * |
| 龚俊波;朱明河;张辉;尹秋响;: "长链二元酸的水相反应结晶过程研究", 天津大学学报(自然科学与工程技术版), no. 08, 23 July 2018 (2018-07-23), pages 2 * |
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