Separation and purification method of succinic acid

Abstract

The invention discloses a separation and purification method of succinic acid, which comprises the following steps: (a) adding water into a mixed solution of succinic acid and a solvent to completely dissolve succinic acid; and (b) carrying out crystallization separation on the succinic acid mixed solution obtained in the step (a) to obtain succinic acid crystals. According to the method, more favorable crystallization conditions are provided for succinic acid crystallization by controlling the ratio of water to the solvent, the crystallization rate of succinic acid is increased, the production cost is reduced, the method is simple, and residual inorganic sodium salt and other impurities in succinic acid fermentation can be effectively separated.

Description

Technical Field

[0001] The invention relates to the field of chemical separation, and in particular to a method for separating and purifying succinic acid. Background Art

[0002] Succinic acid, also known as succinic acid, is one of the intermediate products in the tricarboxylic acid cycle. It is listed as one of the "12 bio-based platform compounds" by the U.S. Department of Energy and is considered to have the potential to replace petrochemical intermediates and become a new generation of bio-based chemical intermediates. Succinic acid can be used in the food processing industry as an acid modifier and stabilizer to improve food flavor. In the agricultural field, it can be used as a synthetic substrate for plant growth regulators to regulate the absorption of nutrients by plants and promote the growth of crops. It can also be used as a surfactant in manufacturing and descaling to improve cleaning power.

[0003] The fermentation method for producing succinic acid has achieved remarkable results, but due to the presence of a large amount of assorted acids, inorganic salts and other substances in the production process, the separation and purification of succinic acid has been difficult, and the extraction and purification process in the downstream currently accounts for 60% or more of the entire industrial production cost. At present, the process for separating succinic acid in the fermentation broth mainly includes liquid-liquid extraction, ammonium salt method, one-step crystallization method, ion exchange adsorption method, bipolar membrane electrodialysis method, etc. These methods all have some unavoidable shortcomings, such as the need to use expensive tertiary amine extractants for liquid-liquid extraction, the need for high-temperature cracking sulfate for ammonium salt method, which easily causes equipment corrosion, the long route of calcium salt method, which can produce a large amount of calcium sulfate waste residues, the low purity of the product obtained by the one-step crystallization method, the low recovery rate, the long crystallization time, the low effective exchange capacity of the resin of the ion exchange method, the large acid and alkali dosage, the easy loss of the membrane of the electrodialysis method, the high energy consumption, and the extremely low divalent ion content, which has obvious limitations.

[0004] The large amount of salty wastewater in the succinic acid separation process is a major difficulty that plagues the industry. The general desalination process is complicated, the equipment is severely corroded, the product purity is low or the yield is low, and the energy consumption is high, which greatly affects the advantages of bio-based succinic acid products, thereby limiting the market growth of bio-based succinic acid. In addition, in the existing literature, the purity of the succinic acid product obtained by one crystallization is low, and the pigment residue in the product is serious. Most high-purity succinic acid requires secondary crystallization or repeated melt crystallization processes. The yield of multiple crystallization products is low, and the crystallization time is long. Therefore, a process that shortens the crystallization time and improves the crystallization efficiency is urgently needed in industrial production to improve the shortcomings of the existing technology. Summary of the invention

[0005] In order to overcome the shortcomings of the prior art, the present invention provides a method for separating and purifying succinic acid, which can quickly remove inorganic salt solids in succinic acid crystals, has a high crystallization rate, and significantly improves the crystallization efficiency.

[0006] To achieve the purpose of the present invention, the present invention provides the following technical solutions:

[0007] A method for separating and purifying succinic acid comprises the following steps:

[0008] (a) adding a solvent and water to succinic acid to completely dissolve the succinic acid;

[0009] (b) subjecting the succinic acid mixed solution obtained in step (a) to crystallization separation to obtain succinic acid crystals.

[0010] Preferably, in step (a), the solvent is selected from one or a mixture of acetone, glycerol, methanol, ethanol or n-butanol.

[0011] In step (a), the volume ratio of the added water to the solvent is 1:4-1:8, preferably 1:5-1:7.

[0012] Preferably, the concentration of succinic acid in step (a) is 350-450 g / L, preferably 350-400 g / L, and heating and stirring are performed to completely dissolve the succinic acid.

[0013] Preferably, the heating temperature in step (a) is 50-80° C. and the stirring speed is 200-400 rpm.

[0014] Preferably, in step (a), a solvent is added to the succinic acid crystals and mixed evenly to dissolve the succinic acid, and insoluble matter is removed by solid-liquid separation to obtain a mixed solution of succinic acid and the solvent.

[0015] Preferably, the succinic acid in step (a) is succinic acid containing an inorganic salt, preferably containing an inorganic sodium salt.

[0016] Preferably, the succinic acid in step (a) is succinic acid crystallized during a succinic acid fermentation process.

[0017] Among them, after adding a solvent to the succinic acid crystals containing inorganic salts and stirring to mix, the inorganic salts insoluble in the solvent and / or impurities such as pigments and proteins that are difficult to dissolve in the solvent can be removed by common solid-liquid separation methods (centrifugation or filtration), and then water is added.

[0018] Preferably, the inorganic salt may be sodium salt such as sodium carbonate, sodium sulfate, etc.

[0019] Preferably, after adding the solvent, stirring is required at room temperature or 20-30° C. for 1-3 h. This process is carried out at low temperature for a short time in order to avoid or reduce side reactions such as esterification and prevent the generation of new impurities.

[0020] Preferably, the amount of the solvent in step (a) is 10 to 30 times the total mass of succinic acid and the inorganic salt crystals contained in succinic acid.

[0021] The separated inorganic sodium salt solid can be directly reused in the fermentation stage after drying.

[0022] The succinic acid crystals obtained by crystallization are dried to obtain high-purity succinic acid crystals.

[0023] Preferably, the crystallization method is cooling crystallization, the crystallization temperature is 10-25° C., and the crystallization time is 2-5 hours.

[0024] The inorganic salt solid obtained by separation can be recycled to the succinic acid fermentation stage after preparing a solution, wherein the concentration of the inorganic salt is in the range of 10-100 g / L, preferably 30-60 g / L.

[0025] Preferably, the succinic acid crystals are dried by oven drying or freeze drying, and after drying, crystals with a purity greater than 99.8% can be obtained.

[0026] The beneficial effects of the present invention are:

[0027] (1) In the fermentation process of succinic acid, inorganic salts are added, mainly inorganic sodium salts, which are easily precipitated together with succinic acid during crystallization, affecting the purity of succinic acid. The solvent of the present invention can selectively precipitate inorganic salts and other insoluble impurities, and the inorganic salts are separated by solid-liquid separation. The separation and purification method is simple and easy to operate.

[0028] (2) The inventors unexpectedly discovered that the mixture of the solvent of the present invention and water in a certain proportion is beneficial to the crystallization of succinic acid, which can significantly shorten the crystallization time and improve the crystallization efficiency.

[0029] (3) In the process of adding solvent to remove inorganic salts, a short time and low temperature are used, and the negative catalyst effect of inorganic sodium salt is used to prevent side reactions such as esterification from occurring during the desalting process, thereby obtaining high-purity succinic acid crystals.

[0030] (4) The inorganic salts separated in the present invention can be recycled to the fermentation stage, thereby reducing the cost of fermentation and treatment of inorganic salt waste. DETAILED DESCRIPTION

[0031] The technical solution of the present invention is further described below in conjunction with specific embodiments, but the present technical invention is not limited thereto. The scope of the present application includes the claims and the specification, and is not limited to the implementation scheme in the embodiments.

[0032] Unless otherwise specified, the reagents used in the present invention are all common commercial products. Sulfuric acid was purchased from Tianjin Komiou Chemical Reagent Co., Ltd.; methanol was purchased from Xilong Chemical Co., Ltd.; ethanol was purchased from Xilong Chemical Co., Ltd.; and activated carbon was purchased from Aladdin.

[0033] Preparation of mixed crystals of succinic acid and sodium sulfate to be separated and purified: Filter the succinic acid fermentation broth through a filter membrane to remove the bacteria and insoluble granular substances in the fermentation broth to obtain a fermentation clear liquid. Add activated carbon to the fermentation clear liquid for decolorization to obtain a decolorized liquid. Under stirring conditions, slowly add 85% sulfuric acid by volume to the decolorized liquid and adjust the pH to 2.0. Use a rotary evaporator to concentrate the decolorized liquid, cool the concentrated liquid at 10°C overnight, and use suction filtration to separate the solid and liquid to obtain mixed crystals of succinic acid and sodium sulfate.

[0034] Example 1

[0035] Add 20 times the mass of ethanol solution to the mixed crystals of succinic acid and sodium sulfate, stir at 30°C for about 3h, centrifuge the mixture at 8000rpm for 10min, and collect the clear liquid and inorganic salt solid respectively. The clear liquid is rotary evaporated at 30°C to remove part of the solvent, and ultrapure water is added thereto at a volume ratio of 1:6 between water and solvent to make the concentration of succinic acid about 360g / L, and heated and stirred at 60°C (stirring speed is 350rpm) to dissolve until the feed liquid is clear and transparent. Pour the dissolved liquid into a crystallization bottle, crystallize at 20°C for 5h, and separate the succinic acid crystals by suction filtration after the crystallization. The succinic acid crystals can be freeze-dried to obtain a high-purity product. The purity of the succinic acid crystals is 99.8% as determined by HPLC. Ultrapure water is added to the inorganic salt solid to prepare an inorganic salt solution with a concentration of 50g / L, which is reused in the fermentation process.

[0036] Example 2

[0037] Add 30 times the mass of acetone solution to the mixed crystals of succinic acid and sodium sulfate, stir at 20°C for about 1h, centrifuge the mixture at 8000rpm for 10min, and collect the clear liquid and inorganic salt solids respectively. The clear liquid is rotary evaporated at 35°C to remove part of the solvent, and ultrapure water is added thereto at a volume ratio of 1:5 between water and solvent to make the concentration of succinic acid about 380g / L, and heated and stirred at 70°C (stirring speed is 250rpm) to dissolve until the feed liquid is clear and transparent. Pour the dissolved liquid into a crystallization bottle, crystallize at 25°C for 2h, and separate the succinic acid crystals by suction filtration after the crystallization is completed. The succinic acid crystals can be freeze-dried to obtain a high-purity product. The purity of the succinic acid crystals is 99.4% as determined by HPLC. Ultrapure water is added to the inorganic salt solid to prepare an inorganic salt solution with a concentration of 60g / L, which is reused in the fermentation process.

[0038] Example 3

[0039] Add 15 times the mass of glycerol solution to the mixed crystals of succinic acid and sodium sulfate, stir at 30°C for about 2h, centrifuge the mixture at 8000rpm for 10min, and collect the clear liquid and inorganic salt solids respectively. The clear liquid is rotary evaporated at 30°C to remove part of the solvent, and ultrapure water is added thereto at a volume ratio of 1:8 between water and solvent to make the succinic acid concentration about 350g / L, and heated and stirred at 60°C (stirring speed is 300rpm) to dissolve until the feed liquid is clear and transparent. Pour the dissolved liquid into a crystallization bottle, crystallize at 10°C for 4h, and separate the succinic acid crystals by suction filtration after the crystallization. The succinic acid crystals can be freeze-dried to obtain a high-purity product. The purity of the succinic acid crystals is 99.5% as determined by HPLC. Ultrapure water is added to the inorganic salt solid to prepare an inorganic salt solution with a concentration of 80g / L, which is then reused in the fermentation process.

[0040] Example 4

[0041] Add 20 times the mass of acetone and n-butanol (volume ratio 1:1) solution to the mixed crystals of succinic acid and sodium sulfate, stir at 23°C for about 1.5h, centrifuge the mixed solution at 8000rpm for 10min, and collect the clear liquid and inorganic salt solid respectively. The clear liquid is rotary evaporated at 30°C to remove part of the solvent, and ultrapure water is added thereto at a volume ratio of 1:4 between water and solvent to make the succinic acid concentration about 450g / L, and heat and stir at 80°C (stirring speed is 250rpm) to dissolve until the feed liquid is clear and transparent. Pour the dissolved liquid into a crystallization bottle, crystallize at 15°C for 3h, and separate the succinic acid crystals by suction filtration after the crystallization. The succinic acid crystals can be obtained by freeze-drying to obtain a high-purity product. The purity of the succinic acid crystals is 99.7% as determined by HPLC. Ultrapure water is added to the inorganic salt solid to prepare an inorganic salt solution with a concentration of 100g / L, which is then reused in the fermentation process.

[0042] Example 5

[0043] Add 25 times the mass of n-butanol and glycerol (volume ratio 1:1) solution to the mixed crystals of succinic acid and sodium sulfate, stir at 28°C for about 2.5h, centrifuge the mixture at 8000rpm for 10min, and collect the clear liquid and inorganic salt solids respectively. The clear liquid is rotary evaporated at 50°C to remove part of the solvent, and ultrapure water is added thereto at a volume ratio of water to solvent of 1:7 to make the succinic acid concentration about 300g / L, and heat and stir at 60°C (stirring speed is 300rpm) to dissolve until the feed liquid is clear and transparent. Pour the dissolved liquid into a crystallization bottle, crystallize at 25°C for 4.5h, and separate the succinic acid crystals by suction filtration after the crystallization. The succinic acid crystals can be obtained by freeze-drying to obtain a high-purity product. The purity of the succinic acid crystals is 99.2% as determined by HPLC. Ultrapure water is added to the inorganic salt solid to prepare an inorganic salt solution with a concentration of 10g / L, which is reused in the fermentation process.

[0044] Example 6

[0045] Add 10 times the mass of ethanol and n-butanol (volume ratio 1:1) solution to the mixed crystals of succinic acid and sodium sulfate, stir at 25°C for about 2h, centrifuge the mixed solution at 8000rpm for 10min, and collect the clear liquid and inorganic salt solids respectively. The clear liquid is rotary evaporated at 22°C to remove part of the solvent, and ultrapure water is added thereto at a volume ratio of 1:5 between water and solvent to make the succinic acid concentration about 400g / L, and heated and stirred at 75°C (stirring speed is 250rpm) to dissolve until the feed liquid is clear and transparent. Pour the dissolved liquid into a crystallization bottle, crystallize at 5°C for 3.5h, and separate the succinic acid crystals by suction filtration after the crystallization is completed. The succinic acid crystals can be obtained by freeze-drying to obtain a high-purity product. The purity of the succinic acid crystals is 99.5% as determined by HPLC. Ultrapure water is added to the inorganic salt solid to prepare an inorganic salt solution with a concentration of 30g / L, which is reused in the fermentation process.

[0046] Example 7

[0047] Add a mixed solution of ethanol and n-butanol (volume ratio 1:1) to the aqueous solution of succinic acid, wherein the total mass of ethanol and n-butanol is 6 times the mass of water, and heat and stir at 60°C (stirring speed is 250rpm) to dissolve until the liquid is clear and transparent. Pour the dissolved liquid into a crystallization bottle and crystallize at 5°C for 5h. After the crystallization is completed, separate the succinic acid crystals by suction filtration. After freeze-drying, the succinic acid crystals can be obtained with high purity. The purity of the succinic acid crystals is 99.3% as determined by HPLC.

[0048] Comparative Example 1

[0049] Add 20 times the mass of ethanol solution to the mixed crystals of succinic acid and sodium sulfate, stir at 30°C for about 3h, centrifuge the mixed solution at 8000rpm for 10min, and collect the clear liquid and inorganic salt solid respectively. The clear liquid is rotary evaporated at 30°C to completely remove the solvent to obtain succinic acid solid. Ultrapure water is added to the solid to make the succinic acid concentration about 360g / L, and heated and stirred at 60°C to dissolve until the feed liquid is clear and transparent. Pour the dissolved liquid into a crystallization bottle and crystallize at 20°C for 24h. After the crystallization is completed, the succinic acid crystals are separated by suction filtration. The succinic acid crystals can be obtained by freeze-drying. The purity of the succinic acid crystals is 99.6% by HPLC. Ultrapure water is added to the inorganic salt solid to prepare an inorganic salt solution with a concentration of 50g / L, which is reused in the fermentation process.

[0050] Comparative Example 2

[0051] Add 20 times the mass of ethanol solution to the mixed crystals of succinic acid and sodium sulfate, stir at 30°C for about 3h, centrifuge the mixed solution at 8000rpm for 10min, and collect the clear liquid and inorganic salt solid respectively. The clear liquid is rotary evaporated at 30°C to remove part of the solvent, so that the concentration of succinic acid is about 360g / L, and heated and stirred at 60°C to dissolve until the feed liquid is clear and transparent. Pour the dissolved liquid into a crystallization bottle and crystallize at 20°C for 10h. After the crystallization is completed, the succinic acid crystals are separated by suction filtration. The succinic acid crystals can be freeze-dried to obtain a high-purity product. The purity of the succinic acid crystals is 92.5% as determined by HPLC. Ultrapure water is added to the inorganic salt solid to prepare an inorganic salt solution with a concentration of 50g / L, which is reused in the fermentation process.

[0052] Comparative Example 3

[0053] The fermentation broth with a succinic acid content of about 85g / L was filtered through a microfiltration membrane with a membrane pore size of 500nm to remove the bacteria and insoluble granular substances in the fermentation broth to obtain a fermentation clear liquid. Under stirring conditions at 200rpm, 85% sulfuric acid was slowly added to the fermentation clear liquid to adjust the pH to 2.0. Activated carbon with a mass volume ratio of 0.5% was added to the acidified liquid, and the mixture was stirred and decolorized at 80℃ for 3h to obtain a decolorized liquid. The decolorized liquid was concentrated by a rotary evaporator at 70℃ to a succinic acid content of 360g / L. The concentrated solution was cooled and crystallized at 10℃ for 4h, and a mixed crystal of succinic acid and sodium sulfate was obtained by suction filtration. An aqueous solution 20 times the mass of the mixed crystals of succinic acid and sodium sulfate was added to the mixed crystals, and the solid was collected after low-temperature centrifugation. Ultrapure water 4 times the mass of the solid was added to the solid, and it was heated and dissolved at 60℃. The dissolved liquid was poured into a crystallization bottle and crystallized at 20°C for 15 hours. Succinic acid crystals were obtained by suction filtration. The succinic acid crystals were freeze-dried to obtain high-purity products. The purity of the succinic acid crystals was 72.3% as determined by HPLC. Ultrapure water was added to the inorganic salt solid to prepare an inorganic salt solution with a concentration of 50 g / L, which was then reused in the fermentation process.

[0054] Comparative Example 4

[0055] Add 20 times the mass of ethanol solution to the mixed crystals of succinic acid and sodium sulfate, stir at 30°C for about 3h, centrifuge the mixed solution at 8000rpm for 10min, and collect the clear liquid and inorganic salt solids respectively. The clear liquid is rotary evaporated at 30°C to remove part of the solvent, and ultrapure water is added thereto at a volume ratio of 1:3 between water and solvent to make the concentration of succinic acid about 360g / L, and heated and stirred at 60°C (stirring speed is 350rpm) to dissolve until the feed liquid is clear and transparent. Pour the dissolved liquid into a crystallization bottle, crystallize at 20°C for 5h, and separate the succinic acid crystals by suction filtration after the crystallization. The succinic acid crystals can be freeze-dried to obtain a high-purity product. The purity of the succinic acid crystals is 93.2% as determined by HPLC. Ultrapure water is added to the inorganic salt solid to prepare an inorganic salt solution with a concentration of 50g / L, which is reused in the fermentation process.

[0056] Comparative Example 5

[0057] Add 20 times the mass of ethanol solution to the mixed crystals of succinic acid and sodium sulfate, stir at 30°C for about 3h, centrifuge the mixed solution at 8000rpm for 10min, and collect the clear liquid and inorganic salt solid respectively. The clear liquid is rotary evaporated at 30°C to remove part of the solvent, and ultrapure water is added thereto at a volume ratio of 1:10 between water and solvent to make the concentration of succinic acid about 360g / L, and heat and stir at 60°C (stirring speed is 350rpm) to dissolve until the feed liquid is clear and transparent. Pour the dissolved liquid into a crystallization bottle, crystallize at 20°C for 5h, and separate the succinic acid crystals by suction filtration after the crystallization is completed. The succinic acid crystals can be freeze-dried to obtain a high-purity product. The purity of the succinic acid crystals is 94.5% as determined by HPLC. Ultrapure water is added to the inorganic salt solid to prepare an inorganic salt solution with a concentration of 50g / L, which is reused in the fermentation process.

[0058] Comparative Example 6

[0059] Add 20 times the mass of ethanol solution to the mixed crystals of succinic acid and sodium sulfate, stir at 30°C for about 3h, centrifuge the mixed solution at 8000rpm for 10min, and collect the clear liquid and inorganic salt solid respectively. The clear liquid is rotary evaporated at 30°C to completely remove the solvent to obtain succinic acid solid. Ultrapure water is added to the solid to make the succinic acid concentration about 360g / L, and heated and stirred at 60°C to dissolve until the feed liquid is clear and transparent. Pour the dissolved liquid into a crystallization bottle, crystallize at 20°C for 5h, and separate the succinic acid crystals by suction filtration after the crystallization. The succinic acid crystals can be obtained by freeze-drying. The purity of the succinic acid crystals is 99.1% by HPLC. The crystals are irregular in shape, small in particle size, more broken crystals, and the yield is significantly low. Ultrapure water is added to the inorganic salt solid to prepare an inorganic salt solution with a concentration of 50g / L, which is reused in the fermentation process.

Claims

1. A method for separating and purifying succinic acid, characterized in that: The following steps are involved: (a) adding a solvent and water to succinic acid to completely dissolve the succinic acid; (b) subjecting the succinic acid mixed solution obtained in step (a) to crystallization separation to obtain succinic acid crystals.

2. The separation and purification method according to claim 1, characterized in that: In step (a), the solvent is selected from one or a mixture of acetone, glycerol, methanol, ethanol or n-butanol; Preferably, in step (a), the volume ratio of the added water to the solvent is 1:4-1:8, preferably 1:5-1:

7.

3. The separation and purification method according to claim 1 or 2, characterized in that: In step (a), the concentration of succinic acid is 350-450 g / L, preferably 350-400 g / L, and heating and stirring are performed to completely dissolve the succinic acid; Preferably, the heating temperature in step (a) is 50-80° C. and the stirring speed is 200-400 rpm.

4. The separation and purification method according to any one of claims 1 to 3, characterized in that: In step (a), the succinic acid is succinic acid containing an inorganic salt, preferably an inorganic sodium salt; Preferably, a solvent is first added to the succinic acid crystals containing inorganic salts, and the mixture is stirred and mixed, and inorganic salts insoluble in the solvent and / or pigments and protein impurities that are poorly soluble in the solvent are removed by solid-liquid separation, and then water is added; Preferably, after adding the solvent, stirring is carried out at 20-30° C. for 1-3 hours; Preferably, the inorganic salt is sodium carbonate or sodium sulfate; Preferably, the succinic acid in step (a) is succinic acid crystallized during a succinic acid fermentation process.

5. The separation and purification method according to any one of claims 1 to 4, characterized in that: The amount of the solvent in step (a) is 10 to 30 times the total mass of succinic acid and the inorganic salt crystals contained in succinic acid.

6. The separation and purification method according to any one of claims 1 to 5, characterized in that: The crystallization method is cooling crystallization, the crystallization temperature is 10-25°C, and the crystallization time is 2-5h.