A method for purifying succinic acid and reducing sulfate content in succinic acid

Abstract

The present invention discloses a method for purifying succinic acid and reducing the sulfate content in the acid, comprising the steps of dissolution, flocculation adsorption, salting-out crystallization, re-dissolution, adsorption on a basic anion exchange resin, and crystallization. Compared with the prior art, the technical solution of the present invention achieves a product purity greater than 99.8%, a sulfate ion content less than 0.005%, a high overall yield, high product purity, a simple technical solution, and no need for heavy metal barium ions. The resulting product can be used in most application fields and has broad market application value.

Description

Technical Field

[0001] The present invention relates to a method for purifying succinic acid, in particular to a method for purifying succinic acid and reducing the sulfate content in the succinic acid. Background Art

[0002] Succinic acid, commonly known as succinic acid, is a dicarboxylic acid that appears as colorless crystals with a sour taste. It is soluble in water, ethanol, and ether, but insoluble in chloroform and dichloromethane. Succinic acid is primarily used in the preparation of five-membered heterocyclic compounds. Succinic acid (including its salts) is used in the food industry in soybean paste, soy sauce, sake, seasonings for ham, sausage, and aquatic products. Succinic acid can be used as a preservative, ion chelator, surfactant, and in lubricants, additives, and elastomers. It also has applications in the pharmaceutical industry.

[0003] There are numerous industrial production methods, including oxidation, hydrogenation, acrylic acid carbonyl synthesis, electrolysis, acetylene synthesis, and fermentation. In the oxidation method, paraffin wax is deeply oxidized to produce a mixture of various carboxylic acids. Succinic acid is then separated through steam distillation and crystallization. In the hydrogenation method, maleic anhydride or fumaric acid is hydrogenated over a catalyst to produce succinic acid, which is then separated to obtain the finished product. The catalyst is nickel or a precious metal, and the reaction temperature is approximately 130-140°C. In the acrylic acid carbonyl synthesis method, acrylic acid and carbon monoxide react over a catalyst to produce succinic acid. This method has not yet been industrialized. In the electrolysis method, phthalic anhydride is electrolyzed with sulfuric acid and water in a ratio of 1:0.5:4 in a ceramic electrolytic cell to produce succinic acid. The raw materials for electrolysis are maleic acid or maleic anhydride. Dilute sulfuric acid is used as the cathode and anode liquids, separated by a cationic membrane. Both the cathode and anode are generally made of lead plates, and the electrolysis is usually performed in a plate-and-frame electrolytic cell. The acetylene method involves the reaction of acetylene with carbon monoxide and water in an acidic medium in the presence of a catalyst to produce succinic acid. Fermentation. Compared to traditional chemical methods, microbial fermentation offers numerous advantages in producing succinic acid: competitive production costs; utilization of renewable agricultural resources, including carbon dioxide, as feedstock, eliminating reliance on petrochemical feedstocks; and reduced environmental pollution associated with chemical synthesis processes. Currently, the main synthesis methods are electrolysis and fermentation.

[0004] The electrolysis method has obvious advantages in industrial applications and is more environmentally friendly. However, the sulfate content in the product obtained by the electrolysis method is too high and difficult to remove, which affects the application of succinic acid in high-end fields and limits its all-round development. The purpose of the present invention is to purify the succinic acid product obtained industrially, improve its purity, and significantly reduce the sulfate content in the product. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for purifying succinic acid and reducing the sulfate content in succinic acid, thereby improving the purity of the succinic acid (succinic acid) product, reducing the sulfate content in succinic acid, and expanding the application of succinic acid, especially in high-end fields.

[0006] To achieve the above object, the method for purifying succinic acid and reducing the sulfate content in succinic acid of the present invention comprises the following steps:

[0007] (1) Add deionized water to a reactor, introduce nitrogen, maintain a nitrogen atmosphere in the reactor, heat to 50-60° C., then add crude succinic acid, stir and dissolve to obtain a succinic acid aqueous solution;

[0008] (2) adding the succinic acid aqueous solution obtained in step (1) to a 0.05% cationic polyacrylamide solution, slowly stirring for 10 to 15 minutes, allowing the mixture to stand, and filtering to obtain a filtrate;

[0009] (3) Slowly adding an inorganic salt to the filtrate obtained in step (2), while cooling to 20-25° C., salting out and crystallizing to precipitate succinic acid solid;

[0010] (4) washing the succinic acid solid obtained in step (3) and dissolving it again to obtain a succinic acid aqueous solution;

[0011] (5) passing the succinic acid aqueous solution obtained in step (4) through an activated alkaline anion exchange resin to obtain a resin purified solution;

[0012] (6) Cooling the purified resin solution obtained in step (5) to 0-5°C for crystallization, washing, and drying to obtain a succinic acid product.

[0013] Preferably, the purity of the crude succinic acid in step (1) is 85-98%, and the sulfate content is 0.5-2%.

[0014] Preferably, the inorganic salt in step (3) is at least one of sodium dihydrogen phosphate and sodium phosphate.

[0015] Preferably, the washing liquid used in the washing process in step (4) and step (6) is deionized water at 2-8°C.

[0016] Preferably, the basic anion exchange resin in step (5) is a strong basic anion exchange resin or a weak basic anion exchange resin, preferably a strong basic anion exchange resin.

[0017] Preferably, in the step (5), the sulfate ion content of the resin purification liquid is detected in real time, and the detection method is ion chromatography.

[0018] Preferably, the succinic acid product obtained in step (6) has a purity greater than 99.8% and a sulfate ion content less than 0.005%.

[0019] Preferably, the crystallization mother liquor in step (6) can be used to dissolve the crude product in step (1) to improve the overall yield.

[0020] Preferably, the weight of the inorganic salt in step (3) is 30-40% of the weight of the crude succinic acid.

[0021] The method of the present invention can remove fine solid particles and part of sulfate in the crude product through flocculation and adsorption of a 0.05% cationic polyacrylamide solution; through the salting-out crystallization step, the purity of the crude product can be significantly improved and the sulfate content can be significantly reduced; by adding inorganic salts and utilizing the synergistic effect of ions, the yield of the succinic acid precipitation crystallization step can be higher, the sulfate removal rate can be higher, and the crystallization purity can be guaranteed at the same time; through adsorption by alkaline anion exchange resin, the small amount of sulfate remaining in the crude product can be adsorbed to obtain a high-quality succinic acid product; the crystallization mother liquor is reused to improve the recrystallization yield. Different crystallization processes and temperatures are used in steps (3) and (5), and the sulfate content in the crude product is efficiently removed while taking into account the yield.

[0022] The inorganic salt used in the salting-out crystallization of the present invention can be reused after evaporation and crystallization, and the alkaline anion exchange resin can be used multiple times after regeneration.

[0023] Compared with the prior art, the technical solution of the present invention has a product purity of more than 99.8%, a sulfate ion content of less than 0.005%, a high total yield, high product purity, a simple technical solution, and no need for heavy metal barium ions. The prepared product can be used in most application fields and has wide market application value. DETAILED DESCRIPTION

[0024] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0025] It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0026] Example 1

[0027] A method for purifying succinic acid and reducing the sulfate content in succinic acid comprises the following steps:

[0028] (1) Add 1 ton of deionized water to a reactor, introduce nitrogen gas, maintain a nitrogen atmosphere in the reactor, heat to 50-60° C., then add 235 kg of crude succinic acid, stir and dissolve to obtain a succinic acid aqueous solution, wherein the crude succinic acid has a purity of 86% and a sulfate content of 1.8%;

[0029] (2) adding the succinic acid aqueous solution obtained in step (1) to 20 L of a 0.05% cationic polyacrylamide solution, slowly stirring for 10 to 15 minutes, allowing to stand, and filtering to obtain a filtrate;

[0030] (3) Slowly adding 75 kg of sodium phosphate to the filtrate obtained in step (2), while cooling to 20-22° C., salting out and crystallizing to precipitate succinic acid solid;

[0031] (4) washing the succinic acid solid obtained in step (3) with 3° C. deionized water and then dissolving it again to obtain a succinic acid aqueous solution;

[0032] (5) passing the succinic acid aqueous solution obtained in step (4) through an activated strong basic anion exchange resin to obtain a resin purified solution, and detecting the sulfate content of the effluent in real time by ion chromatography;

[0033] (6) Cooling the purified resin solution obtained in step (5) to 0-5°C for crystallization, washing, and drying to obtain a succinic acid product, wherein the crystallization mother liquor can be used to dissolve the crude product in step (1).

[0034] Example 2

[0035] A method for purifying succinic acid and reducing the sulfate content in succinic acid comprises the following steps:

[0036] (1) Add 1 ton of deionized water to a reactor, introduce nitrogen gas, maintain a nitrogen atmosphere in the reactor, heat to 50-60° C., then add 200 kg of crude succinic acid, stir and dissolve to obtain a succinic acid aqueous solution, wherein the crude succinic acid has a purity of 94% and a sulfate content of 0.6%;

[0037] (2) adding the succinic acid aqueous solution obtained in step (1) to 20 L of a 0.05% cationic polyacrylamide solution, slowly stirring for 10 to 15 minutes, allowing to stand, and filtering to obtain a filtrate;

[0038] (3) Slowly adding 80 kg of sodium phosphate to the filtrate obtained in step (2), while cooling to 23-25° C., salting out and crystallizing to precipitate succinic acid solid;

[0039] (4) washing the succinic acid solid obtained in step (3) with 7° C. deionized water and then dissolving it again to obtain a succinic acid aqueous solution;

[0040] (5) passing the succinic acid aqueous solution obtained in step (4) through an activated weakly basic anion exchange resin to obtain a resin purified solution, and detecting the sulfate content of the effluent in real time by ion chromatography;

[0041] (6) Cooling the purified resin solution obtained in step (5) to 0-5°C for crystallization, washing, and drying to obtain a succinic acid product, wherein the crystallization mother liquor can be used to dissolve the crude product in step (1).

[0042] Example 3

[0043] A method for purifying succinic acid and reducing the sulfate content in succinic acid comprises the following steps:

[0044] (1) Add 1 ton of deionized water to a reactor, introduce nitrogen gas, maintain a nitrogen atmosphere in the reactor, heat to 50-60° C., then add 215 kg of crude succinic acid, stir and dissolve to obtain a succinic acid aqueous solution, wherein the crude succinic acid has a purity of 93% and a sulfate content of 1.0%;

[0045] (2) adding the succinic acid aqueous solution obtained in step (1) to 30 L of a 0.05% cationic polyacrylamide solution, slowly stirring for 10 to 15 minutes, allowing to stand, and filtering to obtain a filtrate;

[0046] (3) Slowly adding 74 kg of sodium dihydrogen phosphate to the filtrate obtained in step (2), while cooling to 21-23° C., salting out and crystallizing to precipitate succinic acid solid;

[0047] (4) washing the succinic acid solid obtained in step (3) with 5° C. deionized water and then dissolving it again to obtain a succinic acid aqueous solution;

[0048] (5) passing the succinic acid aqueous solution obtained in step (4) through an activated weakly basic anion exchange resin to obtain a resin purified solution, and detecting the sulfate content of the effluent in real time by ion chromatography;

[0049] (6) Cooling the purified resin solution obtained in step (5) to 0-5°C for crystallization, washing, and drying to obtain a succinic acid product, wherein the crystallization mother liquor can be used to dissolve the crude product in step (1).

[0050] Example 4

[0051] A method for purifying succinic acid and reducing the sulfate content in succinic acid comprises the following steps:

[0052] (1) Add 1 ton of deionized water to a reactor, introduce nitrogen gas, maintain a nitrogen atmosphere in the reactor, heat to 50-60° C., then add 210 kg of crude succinic acid, stir and dissolve to obtain a succinic acid aqueous solution, wherein the crude succinic acid has a purity of 93% and a sulfate content of 0.6%;

[0053] (2) adding the succinic acid aqueous solution obtained in step (1) to 20 L of a 0.05% cationic polyacrylamide solution, slowly stirring for 10 to 15 minutes, allowing to stand, and filtering to obtain a filtrate;

[0054] (3) Slowly adding 80 kg of a mixture of sodium phosphate and sodium dihydrogen phosphate to the filtrate obtained in step (2), while cooling to 20-22° C., salting out and crystallizing to precipitate succinic acid solid;

[0055] (4) washing the succinic acid solid obtained in step (3) with 2° C. deionized water and then dissolving it again to obtain a succinic acid aqueous solution;

[0056] (5) passing the succinic acid aqueous solution obtained in step (4) through an activated strong basic anion exchange resin to obtain a resin purified solution, and detecting the sulfate content of the effluent in real time by ion chromatography;

[0057] (6) Cooling the purified resin solution obtained in step (5) to 0-5°C for crystallization, washing, and drying to obtain a succinic acid product, wherein the crystallization mother liquor can be used to dissolve the crude product in step (1).

[0058] Comparative Example 1

[0059] The difference between this embodiment and embodiment 4 is that 80 kg of the mixture of sodium phosphate and sodium dihydrogen phosphate is not added in step (3).

[0060] The rest is the same as in Example 4 and will not be described in detail.

[0061] Comparative Example 2

[0062] The difference between this embodiment and embodiment 4 is that step (5) is reduced.

[0063] The rest is the same as in Example 4 and will not be described in detail.

[0064] Performance Testing

[0065] Table 1 Comparison of performance indicators of products prepared by the present invention

[0066]

[0067] Note: The data in the above table are measured in accordance with GB / T 34686-2017, among which sulfate ion is determined by ion chromatography or the above-mentioned national standard method.

[0068] It can be seen from the data in the above table that the performance of the succinic acid products prepared in Examples 1 to 4 of the present invention are all better than the national standard premium products, especially the sulfate ion content, which is significantly lower than the national standard premium products; since Comparative Example 1 does not adopt the salting-out crystallization method, the product yield is significantly reduced and some performance indicators are lower than the national standard premium products, and the sulfate content is significantly increased compared with Example 4; since Comparative Example 2 does not adopt ion exchange resin adsorption, the yield is equivalent, but the sulfate content is significantly increased compared with Example 4.

[0069] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. All equivalent structural transformations made by using the present invention specification under the concept of the present invention, or direct / indirect application in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A method for purifying succinic acid and reducing the sulfate content in succinic acid, characterized in that: The following steps are involved: (1) Add deionized water to the reactor, introduce nitrogen, maintain the nitrogen atmosphere in the reactor, heat to 50-60°C, then add crude succinic acid, stir and dissolve to obtain a succinic acid aqueous solution; (2) adding 0.05% cationic polyacrylamide solution to the succinic acid aqueous solution obtained in step (1), slowly stirring for 10 to 15 minutes, allowing to stand, and filtering to obtain a filtrate; (3) Slowly adding an inorganic salt to the filtrate obtained in step (2) while cooling to 20-25°C to allow salting out and crystallization to precipitate succinic acid solid; (4) washing the succinic acid solid obtained in step (3) and dissolving it again to obtain a succinic acid aqueous solution; (5) passing the succinic acid aqueous solution obtained in step (4) through an activated alkaline anion exchange resin to obtain a resin purified solution; (6) Cooling the purified resin solution obtained in step (5) to 0-5°C for crystallization, washing, and drying to obtain a succinic acid product; The purity of the crude succinic acid in step (1) is 85-98%, and the sulfate content is 0.5-2%; The inorganic salt in step (3) is at least one of sodium dihydrogen phosphate and sodium phosphate.

2. The method for purifying succinic acid and reducing the sulfate content in succinic acid according to claim 1, characterized in that: The washing liquid used in the washing process in step (4) and step (6) is 2-8°C deionized water.

3. The method for purifying succinic acid and reducing the sulfate content in succinic acid according to claim 1, characterized in that: The alkaline anion exchange resin in step (5) is a strongly basic anion exchange resin or a weakly basic anion exchange resin.

4. The method for purifying succinic acid and reducing the sulfate content in succinic acid according to claim 1, characterized in that: In the step (5), the sulfate ion content of the resin purification liquid is detected in real time, and the detection method is ion chromatography.

5. The method for purifying succinic acid and reducing the sulfate content in succinic acid according to claim 1, characterized in that: The succinic acid product obtained in step (6) has a purity greater than 99.8% and a sulfate ion content less than 0.005%.

6. The method for purifying succinic acid and reducing the sulfate content in succinic acid according to claim 1, characterized in that: The crystallization mother liquor in step (6) is used to dissolve the crude product in step (1) to improve the overall yield.

7. The method for purifying succinic acid and reducing the sulfate content in succinic acid according to claim 1, characterized in that: The weight of the inorganic salt in step (3) is 30-40% of the weight of the crude succinic acid.

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