Succinic acid composition as well as preparation method and application thereof

Abstract

The invention provides a succinic acid composition as well as a preparation method and application thereof. The succinic acid composition comprises a combination of succinic acid and fumaric acid, and the mass content of the fumaric acid in the succinic acid composition is 10-200 ppm. The succinic acid composition provided by the invention is a biomass source and contains succinic acid and a specific content of fumaric acid, and by controlling the content of fumaric acid in the succinic acid composition, the succinic acid composition has obviously improved storage stability and long storage life, and is suitable for industrial production. And after long-term storage, the excellent quality of high succinic acid purity and low impurity content can still be maintained. The succinic acid composition is used for polyester synthesis, can effectively inhibit polymerization side reaction, improves polymerization efficiency, and obtains a high-yield and high-quality polyester product.

Description

Technical Field

[0001] The present invention belongs to the technical field of biochemistry, and particularly relates to a succinic acid composition, a preparation method thereof, and an application thereof. Background Art

[0002] Succinic acid, also known as amber acid, is a colorless crystal, and its important uses include the preparation of five-membered heterocyclic compounds, alkyd resins, biodegradable plastic polybutylene succinate (PBS), etc. Succinic acid can be obtained by chemical synthesis methods, such as catalytic reduction of maleic acid to obtain succinic acid, hydrolysis of succinonitrile to prepare succinic acid, and production of succinic acid from butane through maleic anhydride; it can also be obtained by microbial fermentation. Currently, the sales volume of industrial-grade succinic acid exceeds 15,000 tons, and most of it is produced by chemical synthesis methods. Only the succinic acid in the food market is produced by fermentation.

[0003] Since the chemical synthesis method of succinic acid is affected by the price of petroleum, it has a high cost, and the preparation process is prone to environmental pollution, which does not meet the requirements of current sustainable development. The microbial fermentation method can make full use of renewable resources and has a high conversion rate, and is considered an environmentally friendly, efficient, and green method for producing succinic acid, and has attracted much attention in recent years.

[0004] In the microbial fermentation method, suitable succinic acid-producing strains are used, and succinic acid is synthesized through the metabolic process in which the strains utilize renewable resources such as sugars. Common strains include Anaerobiospirillum succiniciproducens, Actinobacillus succinogenes, Escherichia coli, Corynebacterium glutamicum, Mannheimia succiniciproducens, etc. Research shows that the metabolic acid-producing pathways of succinic acid-producing strains include three categories: (1) the reductive tricarboxylic acid pathway for synthesizing succinic acid, which is the main pathway for strains to synthesize succinic acid under anaerobic conditions; (2) the aerobic tricarboxylic acid cycle pathway. Under aerobic conditions, oxaloacetate and acetyl coenzyme A are first catalyzed into citrate in the mitochondria, and then succinic acid is generated through multiple oxidation reactions; (3) the glyoxylate cycle pathway. Acetyl coenzyme A and oxaloacetate condense to form citrate under the action of citrate synthase, and then isocitrate is formed through the catalysis of aconitase; subsequently, isocitrate lyase decomposes isocitrate into succinic acid and glyoxylate; the generated glyoxylate combines with another molecule of acetyl coenzyme A under the action of malate synthase to form malic acid, and then oxaloacetate is generated for the next round of glyoxylate cycle. From the perspective of the metabolic acid-producing pathway, no matter which synthesis pathway, by-products of organic acids such as formic acid, acetic acid, citric acid, and malic acid are inevitably generated while producing succinic acid; moreover, the sugar substances used as the carbon source of the culture medium will also remain in the fermentation broth; in the purification process of the succinic acid fermentation broth, it is difficult to remove the miscellaneous acids and residual sugars, and they will remain in the final succinic acid product as impurities, and these impurities will affect the synthesis efficiency of subsequent PBS and the performance of the polyester.

[0005] In recent years, with the rapid development of the synthesis technology of biodegradable polyester PBS, the quality of succinic acid as a polymerization monomer has been paid more and more attention. Impurities such as heterologous acids and residual sugars in succinic acid not only affect the efficiency of the polymerization reaction and bring side reactions, etc., but may also affect the hue of the polymer, and may also reduce the molecular weight of the polymer, affect the molecular weight distribution or increase the degree of branching of the molecular chain, thus having a greater impact on the synthesis process and product physical properties of biodegradable polyester. In addition to the impurities brought by the preparation process affecting the product quality, the storage stability of succinic acid products is poor, easy to absorb moisture, and is sensitive to light, temperature and humidity. After long-term storage, problems such as caking, decomposition and denaturation are likely to occur, resulting in a decline in product quality and affecting the application of succinic acid products in polyester synthesis.

[0006] Therefore, developing succinic acid products with high purity, good storage stability and good quality to meet the application requirements in fields such as polyester synthesis is an urgent problem to be solved in this field. Summary of the Invention

[0007] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a succinic acid composition, its preparation method and application. By controlling the fumaric acid content in the succinic acid composition, the succinic acid composition has better storage stability, high purity of succinic acid and low impurity content. When it is applied to polyester synthesis, it can effectively inhibit side reactions, improve the polymerization efficiency and obtain polyester products with excellent performance.

[0008] To achieve this purpose, the present invention adopts the following technical solutions:

[0009] In the first aspect, the present invention provides a succinic acid composition, which includes a combination of succinic acid and fumaric acid, and the mass content of fumaric acid in the succinic acid composition is 10-200 ppm.

[0010] The succinic acid composition provided by the present invention is of biomass origin, contains succinic acid and a specific content of fumaric acid. The fumaric acid has good antibacterial and mildew-proof effects, and as one of the solid acids with the strongest sour taste, it has a low absorption rate. By controlling the fumaric acid content in the succinic acid composition, the succinic acid composition has significantly improved storage stability, extended storage period, and still maintains the excellent quality of high purity of succinic acid and low impurity content after long-term storage. The succinic acid composition is used for polyester synthesis, can effectively inhibit polymerization side reactions, improve the polymerization efficiency, and obtain polyester products with high yield and good quality.

[0011] The following are the preferred technical solutions of the present invention, but do not limit the technical solutions provided by the present invention. Through the following preferred technical solutions, the purpose and beneficial effects of the present invention can be better achieved and realized.

[0012] In the present invention, the term "ppm" represents parts per million, and 1 ppm represents one in a million.

[0013] The mass content of fumaric acid in the succinic acid composition is 10 - 200 ppm, for example, it can be 15 ppm, 20 ppm, 30 ppm, 40 ppm, 50 ppm, 60 ppm, 70 ppm, 80 ppm, 90 ppm, 100 ppm, 120 ppm, 150 ppm, 160 ppm, 180 ppm or 190 ppm, as well as the specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the above range. Preferably, it is 20 - 100 ppm, and more preferably 20 - 60 ppm.

[0014] By controlling and optimizing the mass content of fumaric acid, the succinic acid composition of the present invention has both a high succinic acid content (high purity), low impurity content, excellent storage stability and a longer shelf life; if it does not contain fumaric acid or the content is too low, it cannot play the role of extending the shelf life of the succinic acid composition, resulting in poor storage performance of the succinic acid composition and being prone to deterioration after long-term storage; if the fumaric acid content is too high, side reactions are likely to occur during the synthesis of polyester, affecting the preparation efficiency, yield and quality of polyester.

[0015] Preferably, the mass content of succinic acid in the succinic acid composition is ≥99.75%, for example, it can be 99.78%, 99.8%, 99.82%, 99.85%, 99.88%, 99.9%, 99.92%, 99.93%, 99.94%, 99.95%, 99.96%, 99.97%, 99.98%, 99.99% or 99.999%, as well as the specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the above range. Further preferably, it is 99.78% - 99.99%.

[0016] Preferably, the succinic acid composition further includes water.

[0017] Preferably, the mass content of water in the succinic acid composition is 300 - 3000 ppm, for example, it can be 300 ppm, 500 ppm, 800 ppm, 1000 ppm, 1200 ppm, 1500 ppm, 1800 ppm, 2000 ppm, 2200 ppm, 2500 ppm or 2800 ppm, as well as the specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the above range.

[0018] Preferably, the content of the ignition residue of the succinic acid composition is 20-100 ppm. For example, it can be 25 ppm, 30 ppm, 35 ppm, 40 ppm, 45 ppm, 50 ppm, 55 ppm, 60 ppm, 65 ppm, 70 ppm, 75 ppm, 80 ppm, 85 ppm, 90 ppm or 95 ppm, as well as the specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the range.

[0019] Preferably, other organic acids are also included in the succinic acid composition; "other organic acids" refers to organic acids different from succinic acid and different from fumaric acid.

[0020] Preferably, the other organic acids include any one or a combination of at least two of formic acid, acetic acid, and lactic acid.

[0021] Preferably, the mass content of other organic acids in the succinic acid composition is ≤200 ppm. For example, it can be 0, 0.0001 ppm, 0.0005 ppm, 0.001 ppm, 0.005 ppm, 0.01 ppm, 0.05 ppm, 0.1 ppm, 0.5 ppm, 1 ppm, 2 ppm, 5 ppm, 8 ppm, 10 ppm, 20 ppm, 30 ppm, 40 ppm, 50 ppm, 60 ppm, 80 ppm, 100 ppm, 120 ppm, 150 ppm, 180 ppm or 190 ppm, as well as the specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the range. Further preferably, it is ≤100 ppm, and more preferably ≤10 ppm.

[0022] Preferably, the succinic acid composition also includes saccharide compounds.

[0023] Preferably, the saccharide compounds include glucose and / or maltose.

[0024] Preferably, the mass content of the saccharide compounds in the succinic acid composition is ≤5 ppm. For example, it can be 0, 0.0001 ppm, 0.0005 ppm, 0.001 ppm, 0.005 ppm, 0.01 ppm, 0.05 ppm, 0.08 ppm, 0.1 ppm, 0.2 ppm, 0.3 ppm, 0.5 ppm, 0.8 ppm, 1 ppm, 1.5 ppm, 2 ppm, 2.5 ppm, 3 ppm, 3.5 ppm, 4 ppm or 4.5 ppm, as well as the specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the range.

[0025] Preferably, the melting point of the succinic acid composition is 185 - 188 °C, and it can be, for example, 185.5 °C, 186 °C, 186.5 °C, 187 °C or 187.5 °C, as well as specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list all the specific point values included in the range.

[0026] Exemplarily, the contents of succinic acid, fumaric acid, other organic acids, and saccharide compounds in the succinic acid composition can be measured by high performance liquid chromatography (HPLC).

[0027] Preferably, the measurement is carried out using a high performance liquid chromatograph (HPLC, Thermo Fisher Vanquish core). The chromatographic conditions of HPLC are as follows: use a Rio - Rad type chromatographic column, the injection volume is 30 μL, the mobile phase is 10 mmol / L dilute sulfuric acid, the flow rate is 0.5 mL / min, and the elution gradient is isocratic elution; the column temperature is 40 °C, and the detector wavelength is 410 nm.

[0028] Exemplarily, the melting point, content of incineration residue, and water content of the succinic acid composition can be measured by the method in GB / T34686 - 2017.

[0029] In a second aspect, the present invention provides a preparation method of the succinic acid composition as described in the first aspect. The preparation method includes:

[0030] Inoculate the seed liquid of Actinobacillus succinogenes into a culture medium for anaerobic fermentation to obtain a fermentation broth;

[0031] Filter the fermentation broth, and subject the obtained filtrate to purification treatment to obtain the succinic acid composition.

[0032] Preferably, the inoculation amount of the seed liquid is 1 - 10%, and it can be, for example, 2%, 3%, 4%, 5%, 6%, 7%, 8% or 9%, as well as specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list all the specific point values included in the range.

[0033] In the present invention, the term "inoculation amount" refers to the volume percentage of the seed liquid relative to the culture medium.

[0034] Preferably, the culture medium includes a combination of a carbon source, a nitrogen source, and inorganic salts.

[0035] Preferably, the carbon source includes sugar, and more preferably glucose.

[0036] Preferably, the nitrogen source includes an organic nitrogen source, and more preferably any one or a combination of at least two of yeast powder, peptone, and fish meal.

[0037] Preferably, the inorganic salt includes any one or a combination of at least two of NaHCO3, NaH2PO4, K2HPO4, CaCl2, and MgCl2.

[0038] Preferably, the dissolved oxygen content in the anaerobic fermentation is 0 - 0.5%, for example, it can be 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, or 0.45%, as well as specific point values between the above point values. Due to space limitations and for the sake of simplicity, the specific point values included in the scope of the present invention are not exhaustively listed herein.

[0039] It should be noted that the term "dissolved oxygen content" refers to the volume percentage of oxygen in the fermentation broth.

[0040] Preferably, the anaerobic fermentation is carried out under stirring conditions.

[0041] Preferably, the stirring speed of the anaerobic fermentation is 100 - 500 r / min, for example, it can be 120 r / min, 150 r / min, 180 r / min, 200 r / min, 220 r / min, 240 r / min, 250 r / min, 260 r / min, 270 r / min, 280 r / min, 290 r / min, 300 r / min, 320 r / min, 350 r / min, 380 r / min, 400 r / min, 420 r / min, 450 r / min, or 480 r / min, as well as specific point values between the above point values. Due to space limitations and for the sake of simplicity, the specific point values included in the scope of the present invention are not exhaustively listed herein. Further preferably, it is 200 - 300 r / min.

[0042] Preferably, the pH value of the anaerobic fermentation is 6.0 - 8.0, for example, it can be 6.2, 6.5, 6.6, 6.8, 7.0, 7.2, 7.4, 7.5, 7.6, or 7.8, as well as specific point values between the above point values. Due to space limitations and for the sake of simplicity, the specific point values included in the scope of the present invention are not exhaustively listed herein.

[0043] As a preferred technical solution of the present invention, a basic neutralizing agent is added to the system during the anaerobic fermentation to make the pH value of the anaerobic fermentation 6.0 - 8.0.

[0044] Preferably, the basic neutralizing agent includes any one or a combination of at least two of sodium hydroxide, sodium carbonate, magnesium carbonate, magnesium chloride, calcium carbonate, and calcium chloride.

[0045] Preferably, the temperature of the anaerobic fermentation is 33 - 45°C, for example, it can be 34°C, 35°C, 36°C, 37°C, 38°C, 39°C, 40°C, 41°C, 42°C, 43°C or 44°C, as well as the specific point values between the above point values. Due to space limitations and for the sake of brevity, the present invention does not exhaustively list the specific point values included in the above range.

[0046] Preferably, the time of the anaerobic fermentation is 48 - 72 h, for example, it can be 50 h, 52 h, 55 h, 58 h, 60 h, 62 h, 65 h, 68 h, 70 h or 71 h, as well as the specific point values between the above point values. Due to space limitations and for the sake of brevity, the present invention does not exhaustively list the specific point values included in the above range.

[0047] Preferably, the filtration method includes any one or a combination of at least two of microfiltration, ultrafiltration, nanofiltration or reverse osmosis.

[0048] Preferably, the pore size of the filter membrane used for microfiltration is 0.1 - 10 μm, for example, it can be 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm or 9 μm, as well as the specific point values between the above point values. Due to space limitations and for the sake of brevity, the present invention does not exhaustively list the specific point values included in the above range.

[0049] Preferably, the pore size of the filter membrane used for nanofiltration is 10 - 100 nm, for example, it can be 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm or 90 nm, as well as the specific point values between the above point values. Due to space limitations and for the sake of brevity, the present invention does not exhaustively list the specific point values included in the above range.

[0050] Preferably, the pore size of the filter membrane used for ultrafiltration is 20 - 80 nm, for example, it can be 25 nm, 30 nm, 35 nm, 40 nm, 45 nm, 50 nm, 55 nm, 60 nm, 65 nm, 70 nm or 75 nm, as well as the specific point values between the above point values. Due to space limitations and for the sake of brevity, the present invention does not exhaustively list the specific point values included in the above range.

[0051] Preferably, the concentration multiple of the filtration is 10 - 30 times, for example, it can be 12 times, 15 times, 18 times, 20 times, 22 times, 25 times or 28 times, as well as the specific point values between the above point values. Due to space limitations and for the sake of brevity, the present invention does not exhaustively list the specific point values included in the above range.

[0052] Preferably, the filtration temperature is 40-60°C, for example, it can be 42°C, 45°C, 48°C, 50°C, 52°C, 55°C or 58°C, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0053] Preferably, the purification treatment comprises ion exchange, decolorization, concentration and crystallization performed in sequence to obtain a crude product; the crude product is redissolved and recrystallized at least once to obtain the succinic acid composition; the redissolution solvent comprises a combination of water and an organic solvent, and the organic solvent comprises an ether solvent and / or a ketone solvent.

[0054] As a preferred technical solution of the present invention, a fermentation broth containing succinic acid is obtained by anaerobic fermentation, and then a purification method including filtration, ion exchange treatment, decolorization, concentration and crystallization is designed to separate impurities and succinic acid, and obtain a crude product with high purity; the crude product is then redissolved in a specific solvent and then recrystallized; since the solubility of fumaric acid in the organic solvent is poor, and other impurities such as organic acids and sugars have excellent solubility in organic solvents, the redissolution-recrystallization process can effectively remove other organic acids and sugar impurities, and the content of fumaric acid can be regulated to 10-200ppm as defined in the present invention, to obtain the succinic acid composition.

[0055] It should be noted that "redissolution-recrystallization" includes sequential re-dissolution and recrystallization, which is a combination, that is, one re-dissolution-recrystallization means that the crude product is re-dissolved in a solvent, and then recrystallized to obtain crystals; a second re-dissolution-recrystallization means that the crude product is re-dissolved in a solvent, and then recrystallized to obtain crystals, and then the crystals are re-dissolved in a solvent, and then recrystallized to obtain crystals again, completing two re-dissolution-recrystallizations; and so on.

[0056] Preferably, the ion exchange comprises cation exchange and anion exchange performed sequentially.

[0057] In the present invention, the cation exchange resin is preferably a strong acid cation exchange resin, and further preferably a macroporous strong acid cation exchange resin, wherein the exchange group includes a sulfonic acid group, and the matrix resin includes a styrene-based polymer and / or an acrylic polymer. The macroporous strong acid cation exchange resin can be obtained through commercial channels, and illustratively includes but is not limited to: D001 type cation exchange resin, 001×7 cation exchange resin, ZG C180 type cation exchange resin.

[0058] Optionally, the cation exchange resin includes a macroporous strong acid cation exchange resin.

[0059] In the present invention, the anion exchange resin is preferably a weakly basic anion exchange resin, more preferably a macroporous weakly basic anion exchange resin, and the exchange groups therein include any one or a combination of at least two of primary amine groups, secondary amine groups, and tertiary amine groups, and the matrix resin includes styrene-based polymers and / or acrylic polymers. The macroporous weakly basic anion exchange resin can be obtained through commercial channels, and exemplarily includes but is not limited to: D301 anion exchange resin, WA-30 anion exchange resin, IRA-94 anion exchange resin, J-18 anion exchange resin.

[0060] Optionally, the anion exchange resin includes a macroporous weakly basic anion exchange resin.

[0061] Preferably, the decolorizing agent used for decolorization includes any one or a combination of at least two of activated carbon, clay, and adsorption resin, and more preferably activated carbon.

[0062] Preferably, the activated carbon includes granular activated carbon and / or powdered activated carbon.

[0063] Optionally, the packing density of the granular activated carbon is 0.4 - 0.5 g / cm 3 ; the particle size of the powdered activated carbon is 0.2 - 0.5 mm.

[0064] Preferably, the temperature of the decolorization is 50 - 60 °C, for example, it can be 51 °C, 52 °C, 53 °C, 54 °C, 55 °C, 56 °C, 57 °C, 58 °C, or 59 °C, as well as the specific point values between the above point values. Due to space limitations and for the sake of brevity, the present invention does not exhaustively list the specific point values included in the above range.

[0065] Preferably, the time of the decolorization is 30 - 60 min, for example, it can be 32 min, 35 min, 38 min, 40 min, 42 min, 45 min, 48 min, 50 min, 52 min, 55 min, or 58 min, as well as the specific point values between the above point values. Due to space limitations and for the sake of brevity, the present invention does not exhaustively list the specific point values included in the above range.

[0066] Preferably, the light transmittance of the decolorized solution obtained by the decolorization is ≥ 96%, for example, it can be 96.2%, 96.5%, 96.8%, 97%, 97.2%, 97.5%, 97.8%, 98%, 98.2%, 98.5%, or 99%, as well as the specific point values between the above point values. Due to space limitations and for the sake of brevity, the present invention does not exhaustively list the specific point values included in the above range.

[0067] Exemplarily, the light transmittance of the decolorized solution can be measured by an ultraviolet-visible spectrophotometer.

[0068] Preferably, the concentration method includes evaporation concentration.

[0069] Preferably, the temperature for concentration is 60 - 80°C, for example, it can be 62°C, 65°C, 68°C, 70°C, 72°C, 75°C or 78°C, as well as specific point values between the above point values. Due to space limitations and for the sake of brevity, the present invention does not exhaustively list the specific point values included in the above range.

[0070] Preferably, the system pressure for concentration is 10 - 40 kPa, for example, it can be 12 kPa, 15 kPa, 18 kPa, 20 kPa, 22 kPa, 25 kPa, 28 kPa, 30 kPa, 32 kPa, 35 kPa or 38 kPa, as well as specific point values between the above point values. Due to space limitations and for the sake of brevity, the present invention does not exhaustively list the specific point values included in the above range.

[0071] Preferably, the concentration multiple is 2 - 10 times, for example, it can be 2.5 times, 3 times, 3.5 times, 4 times, 4.5 times, 5 times, 5.5 times, 6 times, 6.5 times, 7 times, 7.5 times, 8 times, 8.5 times, 9 times or 9.5 times, as well as specific point values between the above point values. Due to space limitations and for the sake of brevity, the present invention does not exhaustively list the specific point values included in the above range.

[0072] Preferably, the temperature for crystallization is 10 - 30°C, for example, it can be 12°C, 15°C, 18°C, 20°C, 22°C, 25°C or 28°C, as well as specific point values between the above point values. Due to space limitations and for the sake of brevity, the present invention does not exhaustively list the specific point values included in the above range.

[0073] Preferably, the system pressure for crystallization is 60 - 80 kPa, for example, it can be 62 kPa, 65 kPa, 68 kPa, 70 kPa, 72 kPa, 75 kPa or 78 kPa, as well as specific point values between the above point values. Due to space limitations and for the sake of brevity, the present invention does not exhaustively list the specific point values included in the above range.

[0074] Preferably, after crystallization, a drying step is further included.

[0075] Preferably, the temperature for drying is 75 - 85°C, for example, it can be 76°C, 78°C, 80°C, 82°C or 84°C, as well as specific point values between the above point values. Due to space limitations and for the sake of brevity, the present invention does not exhaustively list the specific point values included in the above range.

[0076] Preferably, the crude product is subjected to n times of redissolution-recrystallization, where n is an integer from 1 to 10, such as 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10, and more preferably n is an integer from 2 to 8; considering the comprehensive purification effect and production efficiency, n is more preferably from 3 to 6.

[0077] Preferably, the organic solvent includes ether and / or acetone.

[0078] Preferably, the mass content of the organic solvent in the solvent for each redissolution is independently 5%-30%, for example, it can be 6%, 8%, 10%, 12%, 15%, 18%, 20%, 22%, 25% or 28%, as well as the specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the range.

[0079] Preferably, the crude product is subjected to n times of redissolution-recrystallization, where n is an integer from 2 to 10; the mass content of the organic solvent in the solvent for the nth redissolution ≤ the mass content of the organic solvent in the solvent for the (n - 1)th redissolution.

[0080] As a preferred technical solution of the present invention, as the multiple redissolution-recrystallization progresses, the mass content of the organic solvent in the solvent used for redissolution decreases, which can further optimize the removal effect of other organic acids and saccharide compounds, while controlling the fumaric acid content to 18 - 100 ppm and obtaining a higher succinic acid yield.

[0081] Preferably, the temperature for each redissolution is independently 60 - 80°C, for example, it can be 62°C, 65°C, 68°C, 70°C, 72°C, 75°C or 78°C, as well as the specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the range.

[0082] Preferably, the time for each redissolution is independently 2 - 10 h, for example, it can be 2.5 h, 3 h, 3.5 h, 4 h, 4.5 h, 5 h, 5.5 h, 6 h, 6.5 h, 7 h, 7.5 h, 8 h, 8.5 h, 9 h or 9.5 h, as well as the specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the range.

[0083] Preferably, the temperature for each recrystallization is independently 10 - 30°C, for example, it can be 12°C, 15°C, 18°C, 20°C, 22°C, 25°C or 28°C, as well as the specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the range.

[0084] Preferably, the system pressure for each recrystallization is independently 60 - 80 kPa, for example, it can be 62 kPa, 65 kPa, 68 kPa, 70 kPa, 72 kPa, 75 kPa or 78 kPa, as well as the specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the range.

[0085] Preferably, after each recrystallization, a drying step is further included.

[0086] Preferably, the temperature for each drying is independently 75 - 85 °C, for example, it can be 76 °C, 78 °C, 80 °C, 82 °C or 84 °C, as well as the specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the range.

[0087] In a preferred technical solution, the preparation method of the succinic acid composition includes the following steps:

[0088] (1) Inoculate the seed liquid of Actinobacillus succinogenes into a culture medium at an inoculation amount of 1 - 10% for anaerobic fermentation. The anaerobic fermentation is carried out under the conditions of a stirring speed of 150 - 350 r / min, a pH value of 6.0 - 8.0, a temperature of 33 - 45 °C, and a time of 48 - 72 h to obtain a fermentation broth;

[0089] (2) Filter the fermentation broth, and the obtained filtrate is successively subjected to cation exchange, anion exchange, decolorization, concentration, crystallization and drying to obtain a crude product;

[0090] Among them, the temperature for decolorization is 50 - 60 °C, the time is 30 - 60 min, so that the light transmittance of the obtained decolorized liquid ≥ 96%;

[0091] The temperature for concentration is 60 - 80 °C, the system pressure is 10 - 40 kPa, and the concentration multiple is 2 - 10 times;

[0092] The temperature for crystallization is 10 - 30 °C, and the system pressure is 60 - 80 kPa;

[0093] The temperature for drying is 75 - 85 °C;

[0094] (3) Subject the crude product to n times of redissolution - recrystallization, where n is an integer from 2 to 10, to obtain the succinic acid composition;

[0095] The solvent for each redissolution includes a combination of water and an organic solvent, where the mass content of the organic solvent is independently an organic solvent, and the mass content of the organic solvent in the solvent for the nth redissolution ≤ the mass content of the organic solvent in the solvent for the (n - 1)th redissolution; the organic solvent includes ether and / or acetone;

[0096] Each temperature of the reconstitution is independently 60 - 80°C, and each time is independently 2 - 10 h;

[0097] Each temperature of the recrystallization is independently 10 - 30°C, and each system pressure is independently 60 - 80 kPa.

[0098] In a third aspect, the present invention provides an application of the succinic acid composition as described in the first aspect in the preparation of five - membered heterocyclic compounds or polyesters.

[0099] Exemplarily, the five - membered heterocyclic compound includes succinic anhydride (i.e., butanedioic anhydride) or succinimide.

[0100] Preferably, the polyester includes poly(butylene succinate) (PBS) or alkyd resin.

[0101] Exemplarily, the preparation method of the poly(butylene succinate) includes the following steps: subjecting the succinic acid composition and 1,4 - butanediol to an esterification reaction to obtain an esterified product; and subjecting the esterified product to a polycondensation reaction to obtain the poly(butylene succinate).

[0102] Preferably, the molar ratio of the succinic acid composition to 1,4 - butanediol is 1:(1.2 - 1.6), for example, it can be 1:1.22, 1:1.25, 1:1.28, 1:1.3, 1:1.32, 1:1.35, 1:1.38, 1:1.4, 1:1.42, 1:1.45, 1:1.48, 1:1.5, 1:1.52, 1:1.55 or 1:1.58, etc.

[0103] Preferably, the temperature of the esterification reaction is 150 - 170°C, for example, it can be 152°C, 154°C, 155°C, 156°C, 158°C, 170°C, 172°C, 174°C, 175°C, 176°C or 178°C, etc.

[0104] Preferably, the time of the esterification reaction is 2 - 4 h, for example, it can be 2.2 h, 2.5 h, 2.8 h, 3 h, 3.2 h, 3.5 h or 3.8 h, etc.

[0105] Preferably, the polycondensation reaction is carried out in the presence of a catalyst, and the catalyst preferably includes a titanate catalyst, and more preferably any one or a combination of at least two of tetramethyl titanate, tetraethyl titanate, tetra - isopropyl titanate, tetra - n - butyl titanate, and tetra - isooctyl titanate.

[0106] Preferably, based on the total mass of the succinic acid composition and 1,4-butanediol being 100%, the dosage of the catalyst is such that the mass of Ti element is 50 - 200 ppm, for example, it can be 60 ppm, 80 ppm, 100 ppm, 120 ppm, 140 ppm, 150 ppm, 160 ppm or 180 ppm, etc.

[0107] Preferably, the polycondensation reaction includes a prepolymerization reaction and a final polymerization reaction that are carried out sequentially.

[0108] Preferably, the temperature of the prepolymerization reaction is 180 - 260 °C, for example, it can be 185 °C, 190 °C, 195 °C, 200 °C, 205 °C, 210 °C, 215 °C, 220 °C, 225 °C, 230 °C or 235 °C, as well as the specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the range.

[0109] Preferably, the pressure of the prepolymerization reaction is 1 - 5 kPa, for example, it can be 1.5 kPa, 2 kPa, 2.5 kPa, 3 kPa, 3.5 kPa, 4 kPa or 4.5 kPa, as well as the specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the range.

[0110] Preferably, the time of the prepolymerization reaction is 0.5 - 4 h, for example, it can be 1 h, 1.2 h, 1.5 h, 1.8 h, 2 h, 2.2 h, 2.5 h, 2.8 h, 3 h or 3.5 h, as well as the specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the range.

[0111] Preferably, the temperature of the final polymerization reaction is 220 - 260 °C, for example, it can be 222 °C, 225 °C, 228 °C, 230 °C, 232 °C, 235 °C, 238 °C, 240 °C, 242 °C, 245 °C, 248 °C, 250 °C, 252 °C, 255 °C or 258 °C, as well as the specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the range.

[0112] Preferably, the pressure of the final polymerization reaction is 10 - 100 Pa, for example, it can be 20 Pa, 25 Pa, 30 Pa, 35 Pa, 40 Pa, 45 Pa, 50 Pa, 55 Pa, 60 Pa, 65 Pa, 70 Pa, 75 Pa, 80 Pa, 85 Pa, 90 Pa or 95 Pa, as well as the specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the range.

[0113] Preferably, the time of the final polymerization reaction is 1 - 6 h, for example, it can be 1.5 h, 2 h, 2.2 h, 2.5 h, 2.8 h, 3 h, 3.2 h, 3.5 h, 3.8 h, 4 h, 4.2 h, 4.5 h, 4.8 h, 5 h, 5.2 h, 5.5 h or 5.8 h, etc.

[0114] Preferably, after the final polymerization reaction is completed, it further includes a step of extrusion granulation to obtain granular polybutylene succinate.

[0115] Compared with the prior art, the present invention has the following beneficial effects:

[0116] The succinic acid composition provided by the present invention is of biomass origin, which contains succinic acid and a specific content of fumaric acid. Through the compounding of fumaric acid and succinic acid, the succinic acid composition has significantly improved storage stability, a long storage period, and still maintains excellent qualities of high succinic acid purity and low impurity content after long-term storage. The succinic acid composition is used for polyester synthesis, can effectively inhibit polymerization side reactions, improve polymerization efficiency, obtain polyester products with high yield and high quality, and especially endow the polyester products with excellent solvent resistance. Specific Embodiments

[0117] The technical solutions of the present invention will be further described below through specific embodiments. Those skilled in the art should understand that the embodiments are only for helping to understand the present invention and should not be regarded as specific limitations on the present invention.

[0118] As used herein, the terms "comprising", "including", "having", "containing" or any other variation thereof are intended to cover non-exclusive inclusion. For example, a composition, step, method, article or device containing the listed elements is not necessarily limited to those elements, but may also include other elements not expressly listed or elements inherent to such composition, step, method, article or device.

[0119] In the following specific embodiments of the present invention, each component for preparing the culture medium and various reagents for filtrate purification treatment are commercially available chemicals; Actinobacillus succinogenes is a commercially available strain. The cation exchange resin is a commercially available macroporous strong acid cation exchange resin, specifically the ZG C180 type cation exchange resin (Ningbo Zhengguang Resin Co., Ltd.); the anion exchange resin is a commercially available macroporous weak base anion exchange resin, specifically the J-18 type anion exchange resin (Ningbo Zhengguang Resin Co., Ltd.).

[0120] The specific component information of some materials is as follows:

[0121] (1) Seed culture medium, with the following components: glucose 12 g / L, yeast powder 8 g / L, corn steep liquor 3 g / L, NaHCO3 3 g / L, NaH2PO4 8 g / L, K2HPO4 2.5 g / L, and the solvent is water.

[0122] (2) Fermentation medium, with the following components: glucose 90 g / L, peptone 15 g / L, potassium dihydrogen phosphate 2 g / L, sodium bicarbonate 2 g / L, calcium chloride 0.5 g / L, magnesium chloride 0.3 g / L, and the solvent is water.

[0123] In the following specific embodiments of the present invention, the water content, ignition residue content, and melting point of the succinic acid composition are all tested by the methods in Standard GB / T 34686-2017; the test methods for the contents of succinic acid, fumaric acid, other organic acids, saccharide compounds, and the shelf life in the succinic acid composition are as follows:

[0124] (1) Test for the contents of succinic acid, fumaric acid, other organic acids, and saccharide compounds: Test by a high performance liquid chromatograph (HPLC, Thermo Fisher Vanquish core). The HPLC is equipped with an autosampler, a quaternary gradient pump, and a refractive index detector. The sample to be tested is prepared into a 10 g / L aqueous solution. The chromatographic conditions are as follows: Use a Rio-Rad type chromatographic column, the mobile phase is 10 mmol / L dilute sulfuric acid, isocratic elution, the detection wavelength is 410 nm, the column temperature is 40 °C, and the contents of fumaric acid, other organic acids, and saccharide compounds are obtained through the chromatogram.

[0125] (2) Shelf life: Place the succinic acid composition to be tested in a ton bag (plastic inner membrane + woven bag), store it in the dark, store it under the conditions of 50% air humidity and room temperature, test its water content (using the method in GB / T 34686-2017) every 1 month, and observe whether there are phenomena such as caking, peculiar smell, and deterioration; when any one of the situations of water content > 1000 ppm, caking, peculiar smell, and deterioration occurs, record the storage time, which is the time that the succinic acid composition can be stably stored.

[0126] Example 1

[0127] A succinic acid composition and its preparation method, the preparation method includes the following steps:

[0128] (1) Preparation of seed liquid:

[0129] Inoculate a single colony of Actinobacillus succinogenes on the plate into the sterilized seed culture medium, and culture it in an incubator at 34 °C for 12 h to obtain the seed liquid.

[0130] (2) Preparation of fermentation broth:

[0131] Add the fermentation medium to a 5 L fermenter. After sterilization, inoculate the seed liquid obtained in step (1) into the medium at an inoculation amount of 10% for anaerobic fermentation. Monitor the pH value during the fermentation process and control the pH value at 6.5 by introducing a sodium carbonate solution (the mass concentration of sodium carbonate is 5%); the temperature of anaerobic fermentation is 35 °C, the dissolved oxygen content is 0.05%, the rotation speed is 280 r / min, and anaerobic fermentation is carried out for 48 h to obtain a fermentation broth.

[0132] (3) Filtration and purification:

[0133] Filter the fermentation broth obtained in step (2) (temperature is 45 °C): first carry out microfiltration (the pore size of the filter membrane is 5 μm), and then carry out nanofiltration on the filtrate (the pore size of the filter membrane is 80 nm), and collect the filtrate;

[0134] The filtrate is successively passed through cation exchange and anion exchange to obtain a permeate;

[0135] Use activated carbon to decolorize the permeate. The temperature of decolorization is 50 °C, the time is 45 min, and the light transmittance of the obtained decolorized liquid is 96%;

[0136] Carry out evaporation and concentration on the decolorized liquid. The temperature is 65 °C, the system pressure is 20 kPa, and the concentration multiple is 4 times to obtain a concentrated liquid;

[0137] Carry out crystallization on the concentrated liquid at 20 °C and a system pressure of 60 kPa, collect the solid and dry it at 75 °C to obtain a crude product;

[0138] (4) Re-dissolution - recrystallization

[0139] Carry out 4 times of re-dissolution - recrystallization on the crude product. The solvent for each re-dissolution is a combination of water and acetone. The mass contents of acetone in the solvents for the 1st - 4th re-dissolutions are 30%, 20%, 20%, and 10% respectively; the temperature for each re-dissolution is 65 °C, and the time is 3 h; the temperature for each recrystallization is 10 °C, the system pressure is 70 kPa, and the obtained solid is dried at 80 °C to obtain the succinic acid composition, and its component information is shown in Table 1.

[0140] Example 2

[0141] A succinic acid composition and a preparation method thereof. The preparation method includes the following steps:

[0142] (1) Preparation of seed liquid:

[0143] Inoculate a single colony of Actinobacillus succinogenes on the plate into the sterilized seed medium and culture it in an incubator at 35 °C for 10 h to obtain a seed liquid.

[0144] (2) Preparation of fermentation broth:

[0145] Add the fermentation medium into a 5 L fermenter. After sterilization, inoculate the seed liquid obtained in step (1) into the medium at an inoculation amount of 8% for anaerobic fermentation. During the fermentation process, monitor the pH value and control the pH value at 6.8 by introducing sodium carbonate solution. The temperature of anaerobic fermentation is 37 °C, the dissolved oxygen content is 0.1%, and the rotation speed is 300 r / min. After 56 h of anaerobic fermentation, a fermentation broth is obtained.

[0146] (3) Filtration and purification:

[0147] Ultrafilter the fermentation broth obtained in step (2) at 40 °C (the pore size of the filter membrane is 50 nm), and collect the filtrate;

[0148] The said filtrate successively undergoes cation exchange and anion exchange to obtain a permeate;

[0149] Use an adsorption resin to decolorize the said permeate. The temperature for decolorization is 55 °C and the time is 60 min. The light transmittance of the obtained decolorized liquid is 96.5%;

[0150] Concentrate the said decolorized liquid by evaporation at 75 °C, with the system pressure being 30 kPa and the concentration multiple being 6 times to obtain a concentrated liquid;

[0151] Crystallize the said concentrated liquid at 30 °C and a system pressure of 75 kPa, collect the solid and dry it at 80 °C to obtain a crude product;

[0152] (4) Re-dissolution - recrystallization

[0153] Perform 5 times of re-dissolution - recrystallization on the crude product. The solvent for each re-dissolution is a combination of water and ether. The mass contents of ether in the solvents for the 1st - 5th re-dissolutions are 25%, 25%, 20%, 20%, and 10% respectively; the temperature for each re-dissolution is 60 °C and the time is 2 h; the temperature for each recrystallization is 15 °C and the system pressure is 60 kPa. Dry the obtained solid at 80 °C to obtain the succinic acid composition, and its component information is shown in Table 1.

[0154] Example 3

[0155] A succinic acid composition and its preparation method, the difference from Example 1 is only that the method of re-dissolution - recrystallization in step (4) is different, specifically as follows:

[0156] The crude product was subjected to 6 times of redissolution-recrystallization. The solvent for each redissolution was a combination of water and ether. The mass contents of ether in the solvents for the 1st - 6th redissolutions were 30%, 30%, 20%, 20%, 10%, and 10% respectively; the temperature for each redissolution was 70 °C and the time was 2 h; the temperature for each recrystallization was 15 °C and the system pressure was 70 kPa. The obtained solid was dried at 80 °C to obtain the succinic acid composition, and its component information is shown in Table 1.

[0157] Example 4

[0158] A succinic acid composition and its preparation method, the difference from Example 1 is only that the method of redissolution-recrystallization in step (4) is different, specifically:

[0159] The crude product was subjected to 3 times of redissolution-recrystallization. The solvent for each redissolution was a combination of water and acetone. The mass contents of acetone in the solvents for the 1st - 3rd redissolutions were 30%, 20%, and 10% respectively; the temperature for each redissolution was 70 °C and the time was 5 h; the temperature for each recrystallization was 12 °C and the system pressure was 70 kPa. The obtained solid was dried at 80 °C to obtain the succinic acid composition, and its component information is shown in Table 1.

[0160] Example 5

[0161] A succinic acid composition and its preparation method, the difference from Example 1 is only that the method of redissolution-recrystallization in step (4) is different, specifically:

[0162] The crude product was subjected to 4 times of redissolution-recrystallization. The solvent for each redissolution was a combination of water and acetone. The mass contents of acetone in the solvents for the 1st - 4th redissolutions were 30%, 25%, 20%, and 10% respectively; the temperature for each redissolution was 70 °C and the time was 2 h; the temperature for each recrystallization was 20 °C and the system pressure was 70 kPa. The obtained solid was dried at 80 °C to obtain the succinic acid composition, and its component information is shown in Table 1.

[0163] Example 6

[0164] A succinic acid composition and its preparation method, the difference from Example 2 is only that the method of redissolution-recrystallization in step (4) is different, specifically:

[0165] The crude product was subjected to 6 times of redissolution-recrystallization. The solvents for the 1st - 3rd redissolutions were combinations of water and acetone, with the mass contents of acetone being 28%, 25%, and 20% respectively; the solvents for the 4th - 6th redissolutions were combinations of water and ether, with the mass contents of ether being 15%, 10%, and 8% respectively; the temperature for each redissolution was 60 °C and the time was 2 h; the temperature for each recrystallization was 15 °C and the system pressure was 70 kPa. The obtained solid was dried at 80 °C to obtain the succinic acid composition, and its component information is shown in Table 1.

[0166] Example 7

[0167] A succinic acid composition and its preparation method, the difference from Example 1 is only that the method of redissolution-recrystallization in step (4) is different, specifically:

[0168] The crude product was subjected to 2 times of redissolution-recrystallization. The solvent for each redissolution was a combination of water and acetone. The mass contents of acetone in the solvents for the 1st - 2nd redissolutions were 30% and 20% respectively; the temperature for each redissolution was 65 °C and the time was 3 h; the temperature for each recrystallization was 10 °C and the system pressure was 70 kPa. The obtained solid was dried at 80 °C to obtain the succinic acid composition, and its component information is shown in Table 1.

[0169] Example 8

[0170] A succinic acid composition and its preparation method, the difference from Example 1 is only that the method of redissolution-recrystallization in step (4) is different, specifically:

[0171] The crude product was subjected to 1 time of redissolution-recrystallization. The solvent for redissolution was a combination of water and acetone, with the mass content of acetone being 30%. The temperature for redissolution was 65 °C and the time was 3 h; the temperature for each recrystallization was 10 °C and the system pressure was 70 kPa. The obtained solid was dried at 80 °C to obtain the succinic acid composition, and its component information is shown in Table 2.

[0172] Example 9

[0173] A succinic acid composition and its preparation method, the difference from Example 1 is only that the method of redissolution-recrystallization in step (4) is different, specifically:

[0174] The crude product was subjected to 4 times of redissolution-recrystallization. The solvent for each redissolution was a combination of water and acetone, with the mass content of acetone being 30% in each case; the temperature for each redissolution was 65 °C and the time was 3 h; the temperature for each recrystallization was 10 °C and the system pressure was 70 kPa. The obtained solid was dried at 80 °C to obtain the succinic acid composition, and its component information is shown in Table 2.

[0175] Example 10

[0176] A succinic acid composition and its preparation method, the difference from Example 1 is only that the method of re-dissolution and recrystallization in step (4) is different, specifically:

[0177] The crude product is subjected to 4 times of re-dissolution and recrystallization. The solvent for each re-dissolution is a combination of water and acetone, and the mass content of acetone is 10% each time; the temperature for each re-dissolution is 65 °C and the time is 3 h; the temperature for each recrystallization is 10 °C, the system pressure is 70 kPa, and the obtained solid is dried at 80 °C to obtain the succinic acid composition, and its component information is shown in Table 2.

[0178] Comparative Example 1

[0179] A succinic acid composition and its preparation method, the difference from Example 1 is only that step (4) only performs 1 time of re-dissolution and recrystallization, the solvent for re-dissolution is water, and other parameters are the same as those in Example 1 to obtain the succinic acid composition, and its component information is shown in Table 2.

[0180] Comparative Example 2

[0181] A succinic acid composition and its preparation method, the difference from Example 1 is only that the method of re-dissolution and recrystallization in step (4) is different, specifically:

[0182] The crude product is subjected to 12 times of re-dissolution and recrystallization. The solvent for each re-dissolution is a combination of water and acetone, and the mass content of acetone in the solvent for the 1st - 12th re-dissolutions is 30%, 30%, 30%, 20%, 20%, 20%, 10%, 10%, 10%, 5%, 5%, 5% respectively; the temperature for each re-dissolution is 65 °C and the time is 3 h; the temperature for each recrystallization is 10 °C, the system pressure is 70 kPa, and the obtained solid is dried at 80 °C to obtain the succinic acid composition, and its component information is shown in Table 2.

[0183] Table 1

[0184]

[0185]

[0186] Table 2

[0187] Example 8 Example 9 Example 10 Comparative Example 1 Comparative Example 2 Succinic acid (%) 99.78 99.81 99.79 99.80 99.78 Fumaric acid (ppm) 82.1 68.7 75.2 226.3 8.5 Other organic acids (ppm) 9.4 6.2 8.1 106.1 0.78 Carbohydrate compounds (ppm) 3.81 0.95 2.19 9.15 0.12 Water (ppm) 851 691 851 715 791 Ignition residue content (ppm) 82 75 85 76 84 Melting point (°C) 185 186 186 186 186 Shelf life ≥ half a year ≥ half a year ≥ half a year ≥ half a year 3 months

[0188] According to the data in Table 1 and Table 2, in the succinic acid composition provided by the present invention, the content of succinic acid is ≥99.78%, the mass content of fumaric acid is 20 - 80 ppm, the water content is ≤1000 ppm, the mass content of other organic acids is ≤10 ppm. The succinic acid has high purity, low impurity content, the content of ignition residue is ≤85 ppm, and has good storage stability, can be stably stored for more than half a year, and will not have problems such as caking, rising water content, deterioration, peculiar smell, etc., and the shelf life is extended. The said succinic acid composition is used for preparing polyester, and can effectively inhibit the polymerization side reaction and improve the polymerization efficiency.

[0189] According to the data in Table 2, it can be known that the content of fumaric acid in the succinic acid composition of Comparative Example 1 is too high. Although its shelf life is relatively long, it will cause more side reactions in downstream applications, affecting the production efficiency and quality of downstream products; the content of fumaric acid in the succinic acid composition of Comparative Example 2 is extremely low, resulting in poor storage stability and easy deterioration.

[0190] The following are exemplary application examples of the succinic acid composition of the present invention for preparing polybutylene succinate (PBS). In the following specific embodiments of the present invention, the reagents whose preparation methods are not specified are all conventional commercially available chemicals.

[0191] Application Examples 1 - 10

[0192] The preparation method of PBS includes the following steps: Mix the succinic acid composition (from Examples 1 - 10 respectively) with 1,4 - butanediol (purity ≥99.7%, purchased from Liaoning Jinfasheng Biotechnology Co., Ltd.) in a molar ratio of 1:1.4, carry out an esterification reaction at 160°C for 3 h to obtain an esterified product; then use tetrabutyl titanate as a catalyst, and the catalyst dosage is such that the mass of Ti element is 80 ppm (calculated based on the total mass of the succinic acid composition and 1,4 - butanediol being 100%), carry out a prepolymerization reaction at 220°C and 5 kPa for 3 h to obtain a prepolymer; continue to react at 230°C and 20 Pa for 4 h, and extrude and pelletize to obtain the polymerization product PBS.

[0193] Comparative Examples 1 - 2

[0194] The preparation method of PBS includes the following steps: Mix the succinic acid composition (from Comparative Examples 1 - 2) with 1,4 - butanediol (purity ≥99.7%, purchased from Liaoning Jinfasheng Biotechnology Co., Ltd.) in a molar ratio of 1:1.4, carry out an esterification reaction at 160°C for 3 h to obtain an esterified product; then use tetrabutyl titanate as a catalyst, and the catalyst dosage is such that the mass of Ti element is 80 ppm (calculated based on the total mass of the succinic acid composition and 1,4 - butanediol being 100%), carry out a prepolymerization reaction at 220°C and 5 kPa for 4 h to obtain a prepolymer; continue to react at 230°C and 20 Pa for 6 h, and extrude and pelletize to obtain the polymerization product PBS.

[0195] The PBS prepared in Application Examples 1-10 and Comparative Examples 1-2 was subjected to the following performance tests:

[0196] The tensile strength of the PBS to be tested was measured according to the method in Standard GB / T 1040.1-2018 to obtain the test value before soaking; then the sample was soaked in tetrahydrofuran (THF) for 72 h, and after drying, the tensile strength was measured according to the same method to obtain the test value after soaking; the retention rate of the tensile strength before and after soaking in the solvent was calculated (100% × test value after soaking / test value before soaking). The data are shown in Table 3:

[0197] Table 3

[0198]

[0199] According to the test data in Table 3, preparing PBS using the succinic acid composition provided in Embodiments 1-10 of the present invention helps to improve the crosslinking degree of the PBS molecular chain, making the PBS in Application Examples 1-10 have better solvent resistance, and its retention rate of tensile strength after soaking in THF for 72 h ≥ 63%. The content of fumaric acid in the succinic acid composition used in Comparative Example 1 is too high. On the one hand, it causes a certain degree of damage to the continuity of the PBS resin molecular chain. This structural damage makes the molecular chain more easily attacked by solvent molecules when the material is soaked in THF, thus reducing the retention rate of tensile strength; on the other hand, the high content of fumaric acid will reduce the crystallinity of PBS, thereby reducing the toughness of the material and affecting the retention rate of tensile strength. The content of fumaric acid in the succinic acid composition used in Comparative Example 2 is insufficient, and its molecular structure is too regular. The molecular weight arrangement of the synthesized PBS resin is too tight, resulting in local stress concentration, and the mechanical properties of the prepared PBS after soaking in organic solvents are significantly attenuated, and the solvent resistance is poor.

[0200] The applicant declares that the present invention uses the above embodiments to illustrate the succinic acid composition, its preparation method and application of the present invention, but the present invention is not limited to the above embodiments, that is, it does not mean that the present invention must rely on the above embodiments to be implemented. Those skilled in the art should understand that any improvement of the present invention, the equivalent replacement of each raw material of the product of the present invention, the addition of auxiliary components, the selection of specific methods, etc. all fall within the protection scope and the disclosure scope of the present invention.

Claims

1. A succinic acid composition, characterized in that The succinic acid composition comprises a combination of succinic acid and fumaric acid, and the mass content of fumaric acid in the succinic acid composition is 10-200 ppm.

2. The succinic acid composition according to claim 1, characterized in that The mass content of fumaric acid in the succinic acid composition is 20-100 ppm; Preferably, the mass content of succinic acid in the succinic acid composition is ≥99.75%, more preferably 99.8%-99.99%.

3. The succinic acid composition according to claim 1, characterized in that The succinic acid composition further includes water; Preferably, the mass content of water in the succinic acid composition is 300-3000 ppm; Preferably, the succinic acid composition has an ignition residue content of 20-100 ppm.

4. The succinic acid composition according to claim 1, characterized in that The succinic acid composition further includes other organic acids, and the other organic acids include any one of formic acid, acetic acid, and lactic acid, or a combination of at least two thereof; Preferably, the mass content of other organic acids in the succinic acid composition is ≤200 ppm, more preferably ≤100 ppm; Preferably, the succinic acid composition further comprises a sugar compound; Preferably, the carbohydrate compound comprises glucose and / or maltose; Preferably, the mass content of sugar compounds in the succinic acid composition is ≤5 ppm.

5. A method for preparing a succinic acid composition according to any one of claims 1 to 4, characterized in that: The preparation method comprises: The seed liquid of Actinobacillus succinici is inoculated into the culture medium for anaerobic fermentation to obtain a fermentation liquid; The fermentation liquid is filtered, and the obtained filtrate is purified to obtain the succinic acid composition.

6. The preparation method according to claim 5, characterized in that: The pH value of the anaerobic fermentation is 6.0-8.0; Preferably, the temperature of the anaerobic fermentation is 33-45°C and the time is 48-72h.

7. The preparation method according to claim 5, characterized in that: The filtration method includes any one of microfiltration, ultrafiltration, nanofiltration or reverse osmosis, or a combination of at least two thereof; Preferably, the purification treatment comprises ion exchange, decolorization, concentration and crystallization performed in sequence to obtain a crude product; the crude product is redissolved and recrystallized at least once to obtain the succinic acid composition; the redissolved solvent comprises a combination of water and an organic solvent, and the organic solvent comprises an ether solvent and / or a ketone solvent; Preferably, the ion exchange comprises cation exchange and anion exchange performed sequentially; Preferably, the decolorizing agent used for decolorization includes any one of activated carbon, white clay, and adsorption resin, or a combination of at least two thereof; Preferably, the decolorization temperature is 50-60°C and the time is 30-60min; Preferably, the concentration temperature is 60-80°C and the system pressure is 10-40kPa; Preferably, the concentration multiple is 2-10 times; Preferably, the crystallization temperature is 10-30°C and the system pressure is 60-80 kPa.

8. The preparation method according to claim 7, characterized in that: The crude product is subjected to n times of redissolution-recrystallization, where n is an integer of 1-10, preferably n is an integer of 2-8; Preferably, the organic solvent comprises ether and / or acetone; Preferably, the mass content of the organic solvent in each re-dissolving solvent is independently 5%-30%; Preferably, the crude product is redissolved and recrystallized n times, where n is an integer of 2-10; the mass content of the organic solvent in the solvent of the nth redissolution is ≤ the mass content of the organic solvent in the solvent of the n-1th redissolution; Preferably, the temperature of each re-dissolution is independently 60-80°C; Preferably, the time for each reconstitution is independently 2-10 hours; Preferably, the temperature of each recrystallization is independently 10-30°C; Preferably, the system pressure of each recrystallization is independently 60-80 kPa.

9. Use of the succinic acid composition according to any one of claims 1 to 4 in the preparation of a five-membered heterocyclic compound or polyester.

10. The use according to claim 9, characterized in that: The polyester includes polybutylene succinate or an alkyd resin.

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