A method for removing impurities from succinic acid

Abstract

The application discloses a method for removing impurities from succinic acid, which comprises the following steps: dissolving and diluting succinic acid, heating the succinic acid diluent to a temperature higher than room temperature, passing the succinic acid diluent through a preheated anion exchange resin column, collecting effluent with impurity content lower than 0.01%, and concentrating and crystallizing to obtain succinic acid. The method has the advantages of low impurity content in the obtained succinic acid, recyclable use of the resin, energy saving and environmental protection.

Description

TECHNICAL FIELD

[0001] The present application relates to the chemical industry, in particular, to a method for removing impurities from succinic acid. BACKGROUND

[0002] With the application of succinic acid no longer limited to intermediates, chemical raw materials, food additives, etc., but as the main raw material of biodegradable plastic-polybutylene succinate (PBS), the demand for succinic acid has increased dramatically. When succinic acid is produced by fermentation method, a small amount of impurities such as fumaric acid will be produced. Fumaric acid has similar physicochemical properties to succinic acid, and its solubility in water is low, which is easy to co-crystallize with succinic acid product. Moreover, once fumaric acid coexists with succinic acid product in solid product, it is difficult to remove by conventional means. How to remove a small amount of fumaric acid impurities in succinic acid to make the purity of succinic acid product higher and meet the product quality detection standard is a problem to be solved.

[0003] With the development of bioconversion method for producing succinic acid, it has become a research focus to obtain high-purity succinic acid from fermentation broth to meet the needs of different industries. Because a small amount of fumaric acid impurities will be produced in the process of producing succinic acid by fermentation method, traditional separation methods such as multiple recrystallization method, activated carbon adsorption method, and chemical methods such as calcium salt barium salt conversion method, ozone oxidation method, etc. cannot effectively remove fumaric acid in succinic acid.

[0004] Therefore, a more economical and effective method for removing impurities, especially fumaric acid, from succinic acid is needed. SUMMARY

[0005] In order to solve one of the above technical problems in the prior art, the present application provides a method for removing impurities from succinic acid.

[0006] The present application provides a method for removing impurities from succinic acid, comprising the following steps:

[0007] The succinic acid product is dissolved and diluted with pure water, the succinic acid diluent is heated to above room temperature, passed through a preheated anion exchange resin column, and the effluent with impurity content less than 0.01% is collected, concentrated and crystallized to obtain succinic acid.

[0008] The succinic acid product needs to be diluted with pure water to avoid introducing other impurities.

[0009] In some embodiments, the acidity of the succinic acid diluent is 10% to 15%, preferably the acidity is 10% to 12%.

[0010] The acidity is within the above range, and the solution is not easy to form a supersaturated state. If the acidity is too low, it will result in higher energy consumption in the subsequent process.

[0011] In some embodiments, the succinic acid dilution is heated to 40°C to 50°C, for example, to 40°C, 45°C, 48°C or 50°C.

[0012] Under the above temperature conditions, the resin offers less resistance to the feed solution, resulting in better flowability. Excessively high temperatures will affect the resin's lifespan.

[0013] In some embodiments, the anion exchange resin is preheated to 45°C to 50°C, for example, 45°C, 48°C or 50°C.

[0014] The resin is preheated before the feed solution is added, so that the heat exchange loss is not too great, and the above temperature is more conducive to the resin to carry out ion exchange.

[0015] In some embodiments, the succinic acid dilution is passed through the anion exchange resin column at a rate of 0.5 to 2.0 BV / h, for example, the flow rate can be 0.5 BV / h, 1.0 BV / h, 1.5 BV / h or 2.0 BV / h.

[0016] The above-mentioned flow rate can maximize the residence time of the liquid in the resin layer and improve the ion exchange rate of the resin.

[0017] In some embodiments, the anion exchange resin is a macroporous, weakly basic acrylic anion exchange resin.

[0018] Through extensive experimentation, the inventors unexpectedly discovered that impurities, particularly fumaric acid, can be removed from succinic acid using an adsorption method with resins possessing specific properties. By utilizing a specific anion exchange resin, impurities such as fumaric acid undergo ion exchange with the resin's active groups (e.g., -RSO3H), causing the impurities to be adsorbed onto the resin, thus achieving the effect of removing impurities from the succinic acid. The adsorbed fumaric acid impurities are then eluted off the resin using a regenerator for environmentally friendly treatment. The resin can be recycled through regeneration.

[0019] In some embodiments, the anion exchange resin is selected from D815 resin, D302 resin, LX-300C resin, D315 resin, and D301 resin.

[0020] In some embodiments, the anion exchange resin is used after pretreatment.

[0021] In some embodiments, the pretreatment involves treating with a 3%–5% NaOH solution and rinsing with pure water until the pH of the effluent reaches 6–7. Within this pH range, the reaction between succinic acid and NaOH can be minimized, thus avoiding any impact on the succinic acid product yield.

[0022] In some implementations, the impurity is primarily fumaric acid. Impurities may also include other miscellaneous acids, but their levels are very low and negligible, having little impact on the purity of the succinic acid product.

[0023] The beneficial effects of this invention are as follows:

[0024] The method of this invention involves heating a diluted succinic acid solution to above room temperature, passing it through a preheated anion exchange resin column, collecting the effluent with an impurity content of less than 0.01%, concentrating and crystallizing to obtain succinic acid. This invention monitors the elution process by detecting the content of fumaric acid impurities in the effluent solution. The succinic acid obtained by this method has extremely low impurity content, and the resin used can be regenerated and recycled, making it energy-saving and environmentally friendly.

[0025] This invention uses a specific anion exchange resin to remove impurities such as fumaric acid from succinic acid through adsorption. It features a short process route, simple operation, high product purity, recyclable resin, high extraction yield, energy saving and environmental protection. It solves the problem of removing fumaric acid from succinic acid and ensures that succinic acid produced by fermentation meets actual production requirements. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. The specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention in any way. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concepts of this disclosure. Such structures and techniques have also been described in many publications.

[0027] Definitions

[0028] Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly used in the field to which this invention pertains. For the purposes of interpreting this specification, the following definitions will apply, and where appropriate, terms used in the singular will also include the plural forms, and vice versa.

[0029] Unless the context clearly indicates otherwise, the terms “a” and “an” as used herein include plural references.

[0030] In this article, “BV” refers to the volume of one column-packed resin.

[0031] As used herein, the term "about" indicates a range of ±20% of the following value. In some embodiments, the term "about" indicates a range of ±10% of the following value. In some embodiments, the term "about" indicates a range of ±5% of the following value.

[0032] The term "acidity" as used in this article refers to the total amount of substances in water that can neutralize strong bases. Calculation method:

[0033] X = C * (V1 - V0) * 1000 / M

[0034] In the formula: C represents the NaOH concentration, V1-V0 represents the volume of alkali consumed in the titration, and M represents the relative molecular mass of the substance being titrated.

[0035] The term "direct titration" as used in this article refers to the direct titration method. The titrant can be NaOH solution of different concentrations.

[0036] The method for detecting succinic acid content is as follows: acid-base titration is used, with phenolphthalein as the indicator solution, and succinic acid sample is titrated with sodium hydroxide standard titration solution. The succinic acid content is calculated by the volume of sodium hydroxide standard titration solution consumed.

[0037] Reagents: Carbon dioxide-free water, sodium hydroxide standard titrant: c(NaOH)=0.5mol / L, phenolphthalein indicator: 10g / L.

[0038] Procedure: Weigh 1.0g of the sample to an accuracy of 0.001g, dissolve it in 50mL of carbon dioxide-free water, add 2 drops of phenolphthalein indicator, and titrate with sodium hydroxide standard solution until the solution turns pink and remains pink for 30s, which is the endpoint. Perform a blank test at the same time.

[0039] The method for detecting fumaric acid content is as follows: Using phenolphthalein as an indicator, the sample aqueous solution is titrated with a standard sodium hydroxide solution. Based on the volume of the standard sodium hydroxide solution used, the concentration of fumaric acid (C4H4H2O) is calculated. 10 The total acid content, calculated on a dry basis (O4), is the fumaric acid content.

[0040] Reagents: Carbon dioxide-free water, sodium hydroxide standard titrant: c(NaOH)=0.5mol / L, phenolphthalein indicator: 10g / L.

[0041] Weigh 1.0g of the sample to an accuracy of 0.0002g and place it in a 250mL Erlenmeyer flask. Add 100mL of water, heat to dissolve, and after cooling, add 3 drops of phenolphthalein indicator solution. Titrate with sodium hydroxide standard solution until the solution turns slightly pink and remains so for 30 seconds, which is the endpoint. Perform a blank test at the same time.

[0042] To distinguish between fumaric acid and succinic acid, the solution needs to be subjected to liquid chromatography, and the content of fumaric acid and succinic acid in the solution can be calculated through chromatographic separation.

[0043] The equipment involved in this invention can be conventional equipment well known in the art, including evaporators (such as rotary evaporators or multi-effect evaporators), jacketed glass columns, peristaltic pumps, etc. The above-mentioned equipment can be used individually or in combination.

[0044] The following embodiments are provided to aid in understanding the present invention. However, it should be understood that these embodiments are for illustrative purposes only and do not constitute any limitation. The actual scope of protection of the present invention is set forth in the claims. It should be understood that any modifications and changes can be made without departing from the spirit of the present invention.

[0045] Example 1

[0046] This embodiment provides a method for removing impurities from succinic acid, comprising the following steps:

[0047] 1. Succinic acid was diluted with pure water to a direct drop acidity of 10.38%, and a sample was taken for testing. The succinic acid content was 10.17%, and the fumaric acid content was 0.17%.

[0048] 2. Fill a 500mL jacketed glass column with D815 resin and circulate 45℃ hot water through the jacket to preheat the resin.

[0049] 3. After regenerating the resin with a 4% NaOH solution, rinse with pure water until the outlet pH is 6-7.

[0050] 4. Heat the succinic acid dilution to 50°C and pass it through the resin bed at a flow rate of 1 BV / h (450 mL / h).

[0051] 5. Collect samples once every 1 BV (450 mL) of material discharged from the outlet, and test the fumaric acid content. The results are shown in Table 1. Stop collecting when the fumaric acid content at the outlet reaches 0.01%, and combine the collected succinic acid solutions with a fumaric acid content below 0.01%.

[0052] Table 1. Discharge Volume and Fumaric Acid Content

[0053] Discharge volume / BV Fumaric acid content / % Discharge volume / BV Fumaric acid content / % 1 0 10 0 2 0 11 0.001 3 0 12 0.004 4 0 13 0.01 5 0 14 0.03 6 0 15 0.05 7 0 16 0.10 8 0 17 0.14 9 0 18 0.17

[0054] 6. The succinic acid solution that has passed through the resin column is concentrated, crystallized, separated, and dried to obtain the finished succinic acid product with a purity of 99.52%, which meets the quality standards.

[0055] Sampling and testing results show that D815 resin has a good adsorption effect on fumaric acid, effectively removing fumaric acid impurities from succinic acid. After 13 BV of feed into the resin column, the fumaric acid content at the column outlet reached 0.01%, gradually increasing to a level comparable to the fumaric acid content in the raw material, indicating that the resin column was saturated with fumaric acid. The resin can be regenerated and reused.

[0056] Example 2

[0057] This embodiment provides a method for removing impurities from succinic acid, comprising the following steps:

[0058] 1. Succinic acid was diluted with pure water to a direct drop acidity of 10.71%, and a sample was taken for testing. The succinic acid content was 10.22%, and the fumaric acid content was 0.27%.

[0059] 2. Fill a 500mL jacketed glass column with D815 resin and circulate 45℃ hot water through the jacket to preheat the resin.

[0060] 3. After regenerating the resin with a 4% NaOH solution, rinse with pure water until the outlet pH is 6-7.

[0061] 4. Heat the succinic acid dilution to 50°C and pass it through the resin bed at a flow rate of 1 BV / h (450 mL / h).

[0062] 5. Collect samples once every 1 BV (450 mL) of material discharged from the outlet, and test the fumaric acid content. The results are shown in Table 2. Stop collecting when the fumaric acid content at the outlet reaches 0.01%, and combine the collected succinic acid solutions with a fumaric acid content below 0.01%.

[0063] Table 2. Discharge volume and fumaric acid content

[0064] Discharge volume / BV Fumaric acid content / % Discharge volume / BV Fumaric acid content / % 1 0 10 0 2 0 11 0 3 0 12 0.01 4 0 13 0.05 5 0 14 0.11 6 0 15 0.15 7 0 16 0.18 8 0 17 0.23

[0065] 6. The succinic acid solution that has passed through the resin column is concentrated, crystallized, separated, and dried to obtain the finished succinic acid product with a purity of 99.6%, which meets the quality standards.

[0066] Sampling and testing results show that D815 resin has a good adsorption effect on fumaric acid, effectively removing fumaric acid impurities from succinic acid. After 12 BV of feed into the resin column, the fumaric acid content at the column outlet reaches 0.01%, gradually increasing to a level comparable to the raw material's fumaric acid content. The resin can be regenerated and reused.

[0067] Example 3

[0068] This embodiment provides a method for removing impurities from succinic acid, comprising the following steps:

[0069] 1. Succinic acid was diluted with pure water to a direct drop acidity of 10.06%, and a sample was taken for testing. The succinic acid content was 9.69%, and the fumaric acid content was 0.24%.

[0070] 2. Fill a 500mL jacketed glass column with LX-300C resin and circulate 45℃ hot water through the jacket to preheat the resin.

[0071] 3. After regenerating the resin with a 4% NaOH solution, rinse with pure water until the outlet pH is 6-7.

[0072] 4. Heat the succinic acid dilution to 50°C and pass it through the resin bed at a flow rate of 1 BV / h (450 mL / h).

[0073] 5. Collect samples once every 1 BV (450 mL) of material discharged from the outlet, and test the fumaric acid content. The results are shown in Table 3. Stop collecting when the fumaric acid content at the outlet reaches 0.01%, and combine the collected succinic acid solutions with a fumaric acid content below 0.01%.

[0074] Table 3. Discharge volume and fumaric acid content

[0075] Discharge volume / BV Fumaric acid content / % Discharge volume / BV Fumaric acid content / % 1 0 15 0.008 2 0 16 0.01 3 0 17 / 4 0 18 0.02 5 0 19 / 6 0.006 20 / 7 0.006 21 0.04 8 0.006 22 0.05 9 0.007 23 0.12 10 0.007 24 0.14 11 0.007 25 0.20 12 / 26 0.24 13 / 27 / 14 / 28 /

[0076] Note: " / " in the table indicates that no sample was taken for testing.

[0077] 6. The succinic acid solution that has passed through the resin column is concentrated, crystallized, separated, and dried to obtain the finished succinic acid product with a purity of 99.58%, which meets the quality standards.

[0078] Sampling and testing results show that LX-300C resin has a good adsorption effect on fumaric acid, effectively removing fumaric acid impurities from succinic acid. After processing 16 BV of resin, the fumaric acid content at the resin column outlet reaches 0.01%, gradually increasing to a level comparable to that of the raw material. The resin can be regenerated and recycled.

[0079] Example 4

[0080] This embodiment provides a method for removing impurities from succinic acid, comprising the following steps:

[0081] 1. Succinic acid was diluted with pure water to a direct drop acidity of 10.06%, and a sample was taken for testing. The succinic acid content was 9.69%, and the fumaric acid content was 0.24%.

[0082] 2. Fill a 500mL jacketed glass column with D302 resin and circulate 45℃ hot water through the jacket to preheat the resin.

[0083] 3. After regenerating the resin with a 4% NaOH solution, rinse with pure water until the outlet pH is 6-7.

[0084] 4. Heat the succinic acid dilution to 50°C and pass it through the resin bed at a flow rate of 1 BV / h (450 mL / h).

[0085] 5. Collect samples once every 1 BV (450 mL) of material discharged from the outlet, and test the fumaric acid content. The results are shown in Table 4. Stop collecting when the fumaric acid content at the outlet reaches 0.01%, and combine the collected succinic acid solutions with a fumaric acid content below 0.01%.

[0086] Table 4. Discharge Volume and Fumaric Acid Content

[0087] Discharge volume / BV Fumaric acid content / % Discharge volume / BV Fumaric acid content / % Discharge volume / BV Fumaric acid content / % 1 0 15 / 2 0 16 / 3 0 17 / 4 0 18 0.02 5 0 19 0.02 6 0.007 20 / 7 0.01 21 / 8 0.01 22 / 9 / 23 0.03 10 / 24 0.03 11 / 25 0.04 12 / 26 0.06 13 0.01 27 0.11 14 / 28 0.23

[0088] Note: " / " in the table indicates that no sample was taken for testing.

[0089] 6. The succinic acid solution that has passed through the resin column is concentrated, crystallized, separated, and dried to obtain the finished succinic acid product with a purity of 99.52%, which meets the quality standards.

[0090] Sampling and testing results show that D302 resin has a good adsorption effect on fumaric acid, and can remove fumaric acid impurities from succinic acid. After treating a resin volume of 7 BV, the fumaric acid content at the resin column outlet reaches 0.01%. After treating a resin volume of 13 BV, the fumaric acid content is still 0.01%, and then gradually increases to be comparable to the fumaric acid content of the raw material. The resin can be regenerated and recycled.

[0091] Examples 5-6 and Comparative Examples 1-3

[0092] The procedure was the same as in Example 1, except that the elution was performed under the conditions shown in Table 5.

[0093] Table 5. Feeding conditions and processing results

[0094]

[0095]

[0096] As shown in Table 5, the resin used in this invention has a good adsorption effect on fumaric acid under certain process conditions, and can effectively remove the fumaric acid impurity from succinic acid. After treating a certain volume of the feed solution, the fumaric acid content at the resin column outlet reaches 0.01%. Among them, resins D815 and LX300C have better treatment effects. In Comparative Examples 1-2, other resins were used for treatment. After treating a small amount of feed solution, the fumaric acid content at the resin column outlet quickly increased to 0.01%, indicating that the resin has a low adsorption effect on fumaric acid in the feed solution and poor impurity removal effect. In addition, even though Comparative Example 3 used a D815 resin column, the temperature of the succinic acid dilution solution and the resin temperature still affected the resin's impurity removal effect on fumaric acid. After treating a small amount of feed solution, the fumaric acid content in the effluent reached 0.01%.

[0097] Although the present invention has been described in detail above with general descriptions, specific embodiments, and experiments, some modifications or improvements can be made to it. The technical solutions of the present invention are not limited to the specific embodiments described above; all technical variations made based on the technical solutions of the present invention fall within the protection scope of the present invention.

Claims

1. A method for removing impurities from succinic acid, characterized in that, Includes the following steps: Succinic acid was dissolved and diluted. The diluted succinic acid solution was heated to 40℃~50℃ and passed through an anion exchange resin column preheated to 45℃~50℃. The effluent with impurity content of less than 0.01% was collected, concentrated, and crystallized to obtain succinic acid. The anion exchange resin is a macroporous, weakly basic acrylic anion exchange resin, selected from D815 resin, D302 resin and LX-300C resin; the impurity is fumaric acid.

2. The method according to claim 1, characterized in that, The acidity of the succinic acid dilution is 10%~15%.

3. The method according to claim 1, characterized in that, The diluted succinic acid solution is passed through the anion exchange resin column at a rate of 0.5~2.0 BV / h.

4. The method according to any one of claims 1-3, characterized in that, The anion exchange resin is used after pretreatment.

5. The method according to claim 4, characterized in that, The pretreatment involves using a 3% to 5% NaOH solution and rinsing with pure water until the pH of the effluent is 6 to 7.

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