A method for purifying 2,5-furandicarboxylic acid

Abstract

The application discloses a kind of 2,5-furan dicarboxylic acid purification method, belong to organic chemical technology field, the method of the present application includes the following steps: (1) after crude 2,5-furan dicarboxylic acid and basic amine substance are carried out acid-base neutralization reaction, obtain mixed solution;The basic amine substance is selected from organic base and / or ammonia water;(2) after the mixed solution is filtered, water phase is collected after extraction, water phase is added to acid solution, so that furan dicarboxylic acid is precipitated under acidic conditions, and 2,5-furan dicarboxylic acid pure product is obtained after washing and drying.The method of the present application is simple and efficient, and the conditions are mild, without introducing additional metal elements or additional additives, by-products are easy to volatilize, so it is easy to remove, and 2,5-furan dicarboxylic acid pure product with low metal impurities and organic impurities can be prepared.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of organic chemical industry, and particularly relates to a purification method of 2,5-furan dicarboxylic acid. BACKGROUND

[0002] 2,5-furan dicarboxylic acid (FDCA) is a renewable biomass monomer, and its structure is similar to that of petroleum-based terephthalic acid (TPA), which can be used as an ideal substitute for TPA. Compared with renewable aliphatic polyesters such as polylactic acid (PLA), the rigid five-membered ring of FDCA enhances its thermal mechanical properties. FDCA-based polyesters have excellent gas barrier properties, and the barrier properties of water, carbon dioxide and oxygen can be several to tens of times higher than those of corresponding TPA-based polyesters, which shows the advantage of being used as packaging materials. Compared with TPA-based polyesters, the development of high-value-added FDCA-based polyesters can promote the transformation of the polyester industry.

[0003] At present, furan dicarboxylic acid is mainly prepared by oxidation of 5-hydroxymethylfurfural as raw material under alkaline conditions with a transition metal catalyst. The crude product contains incomplete oxidation or over-oxidation products, residual metal catalysts and impurities in the alkaline solution. These impurities will eventually affect the polymerization process and the molecular weight of the polymer, cause the product to yellow, and reduce the product performance.

[0004] Many studies have been conducted on the purification of furan dicarboxylic acid in the prior art, but some of the purification processes only consider organic impurities. For example, Chinese patent documents CN103965146A and CN109721577A only purify organic impurities, and high-purity furan dicarboxylic acid is obtained, but the metal impurities therein are not concerned. Generally, the prepared furan dicarboxylic acid contains not only organic impurities but also metal impurities, especially a considerable amount of metal impurities corresponding to the alkali used in the oxidation preparation under alkaline conditions.

[0005] Polymer-grade monomers (such as terephthalic acid) have certain requirements for metal impurity content, because metal impurities will affect the polymerization process and product color. At present, the influence of various impurities in FDCA on the performance of polymers has not been thoroughly studied, and no relevant industry standards have been introduced. Therefore, the preparation of 2,5-furan dicarboxylic acid with low metal content is of great significance for improving product performance and studying the influence of impurities on polymerization mechanism and polymer performance. Chinese patent document CN115028610A discloses that the crude 2,5-furan dicarboxylic acid is treated with a metal ion removal agent and intensive washing to remove the FDCA synthesis catalyst in the crude 2,5-furan dicarboxylic acid, thereby improving the efficiency of purifying 2,5-furan dicarboxylic acid by hydrogenation reaction, wherein the metal ion removal agent includes hydrobromic acid and / or ethylenediaminetetraacetic acid, but this method needs to use metal ion removal agents, recrystallization solvents and other additives. SUMMARY

[0006] The application provides a method for purifying 2,5-furan dicarboxylic acid, which is simple, efficient, mild and free of additional metal elements or additives, and can prepare 2,5-furan dicarboxylic acid with low metal impurities and organic impurities.

[0007] The specific technical solutions are as follows:

[0008] A method for purifying 2,5-furan dicarboxylic acid, comprising the following steps:

[0009] (1) performing acid-base neutralization reaction on crude 2,5-furan dicarboxylic acid and an alkaline amine substance to obtain a mixed solution; the alkaline amine substance is selected from organic bases and / or ammonia;

[0010] (2) filtering the mixed solution, collecting the aqueous phase by extraction, adding the aqueous phase into an acid solution, precipitating the furan dicarboxylic acid under acidic conditions, and washing and drying to obtain 2,5-furan dicarboxylic acid.

[0011] Optionally, the crude 2,5-furan dicarboxylic acid is prepared by using 5-hydroxymethylfurfural as a raw material and a metal catalyst for catalytic oxidation reaction (may contain 5-formylfuran-2-carboxylic acid which is not completely oxidized, furfurylic acid which is deeply oxidized, and metal ions from the catalyst, etc.), and the purity of the crude 2,5-furan dicarboxylic acid is more than 98% and the content of each metal element is less than 1000 ppm.

[0012] In the method, the 2,5-furan dicarboxylic acid is neutralized with a specific alkaline amine substance to generate furan dicarboxylic acid salt which is easily soluble in water, and can be separated from organic impurities and solid impurities which are not soluble in water by filtration, and the organic impurities which are slightly soluble in water can be further removed by extraction; under acidic conditions, the furan dicarboxylic acid salt solution precipitates 2,5-furan dicarboxylic acid which can be separated from metal elements in the aqueous solution; and the specific alkaline amine substance is selected to avoid introducing additional metal impurities, so that the content of metal elements in the 2,5-furan dicarboxylic acid can be further reduced.

[0013] Preferably, the molar ratio of the alkaline amine substance to the crude 2,5-furan dicarboxylic acid is 2:1 to 5:1.

[0014] Further preferably, in step (1), the crude 2,5-furan dicarboxylic acid is added to the alkaline amine substance, fully stirred, and stirred under heating conditions, the heating temperature is 40-80°C, and the reaction time is 0.5-5h.

[0015] Preferably, in step (2), the filtrate is extracted with an organic solvent, which includes at least one of trichloromethane, dichloromethane, ethyl acetate, and petroleum ether.

[0016] Preferably, in step (2), the collected aqueous phase is added dropwise into the acid solution under stirring at a rate of 0.5 s to 2 s per drop to prevent incomplete acidification caused by too fast dropping, thereby affecting the quality of the product.

[0017] Preferably, the acid solution is a hydrochloric acid solution and / or a sulfuric acid solution, and further preferably, the hydrochloric acid solution has a mass fraction of 10% to 36%, or the sulfuric acid solution has a mass fraction of 10% to 50%.

[0018] Preferably, the molar ratio of hydrogen ions contained in the acid substance in the acid solution in step (2) to hydroxyl ions contained in the basic amine substance in step (1) is 1.1:1 to 4:1.

[0019] The purity of the pure 2,5-furan dicarboxylic acid product is greater than or equal to 99.98%, and the content of metal elements is within 10 ppm, wherein the metal elements include at least one of sodium, potassium, iron, magnesium, and calcium.

[0020] Compared with the prior art, the present application has the following beneficial effects:

[0021] (1) In the prior art, the preparation of furan dicarboxylic acid with low metal content has not been concerned, and there is no report on the technical scheme of using a basic amine substance containing no metal elements to neutralize 2,5-furan dicarboxylic acid for metal impurity purification. The purification method of 2,5-furan dicarboxylic acid provided by the present application can prepare a pure 2,5-furan dicarboxylic acid product with a purity of more than 99.98% by only neutralizing 2,5-furan dicarboxylic acid with a basic amine substance to obtain an aqueous solution containing furan dicarboxylic acid salt, and filtering, extracting, and precipitating with an acid solution. The steps work together to ensure high purity and low metal content of the 2,5-furan dicarboxylic acid product.

[0022] (2) The process of the present application has mild and simple process conditions, does not introduce additional metal elements and does not need to add metal removal agents and other additional additives. The basic amine substance used contains no metal elements and is easy to volatilize. The by-product (such as ammonium chloride) is also easy to volatilize and decompose. The process is simple, efficient, and has good effect. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 The high-performance liquid chromatogram of the furan dicarboxylic acid product prepared in Example 1. DETAILED DESCRIPTION

[0024] The technical solutions of the present application will be further illustrated by specific embodiments. Those skilled in the art should understand that the embodiments are only used to help understand the present application and should not be regarded as specific limitations of the present application.

[0025] The specific techniques or conditions not specified in the following examples and comparative examples can be carried out according to the techniques or conditions described in the literature in the art or according to the product instructions. The reagents or instruments not specified by the manufacturer are conventional products that can be commercially available or can be prepared by the prior art.

[0026] Example 1

[0027] (1) 3 mol of commercially available crude 2,5-furan dicarboxylic acid (purity 99%, sodium content about 400 ppm, potassium content about 100 ppm, calcium content about 80 ppm, magnesium content about 60 ppm, iron content about 20 ppm) and 400 g of 28% ammonia water were sequentially added to a round-bottom flask, stirred for 30 min, heated to 80°C and continued to stir for 1 hour to make it fully dissolved and neutralized, and remove part of the excess ammonia monohydrate to obtain a mixed solution containing ammonium furandicarboxylate;

[0028] (2) The mixed solution was filtered, and the filtrate was transferred to a 2000 ml separatory funnel, extracted with chloroform three times, then washed with petroleum ether once, and the aqueous phase was transferred to a constant pressure dropping funnel. 860 g of 36% hydrochloric acid solution was weighed in a round-bottom flask, and the aqueous phase was slowly added to the hydrochloric acid solution at a rate of 1 drop per second under stirring to acidify the solution, so that the furandicarboxylic acid was precipitated under acidic conditions. The obtained solid precipitate was further washed with deionized water for 3 times, dried in an oven, and 2,5-furan dicarboxylic acid was obtained.

[0029] Test results show that the purity of the 2,5-furan dicarboxylic acid product obtained in this embodiment is 99.98%, and the high performance liquid chromatogram is as shown in Figure 1 The contents of sodium, potassium, calcium, magnesium and iron are controlled within 10 ppm.

[0030] Example 2

[0031] (1) 3 mol of commercially available crude 2,5-furan dicarboxylic acid (purity 99%, sodium content 400 ppm or so, potassium content 100 ppm or so, calcium content 80 ppm or so, magnesium content 60 ppm or so, iron content 20 ppm or so) and 400 g of 28% ammonia water were sequentially added to a round-bottom flask, fully stirred for 30 min, heated to 80°C and continuously stirred for 1 h to fully dissolve and undergo neutralization reaction, and remove part of the excess monohydrate ammonia to obtain a mixed solution containing ammonium furandicarboxylate;

[0032] (2) The mixed solution was filtered, the filtrate was transferred to a 2000 ml separatory funnel, extracted with chloroform three times, then washed with petroleum ether once, the aqueous phase was transferred to a constant pressure dropping funnel, 860 g of 36% hydrochloric acid solution was weighed in a round-bottom flask, and the aqueous phase was slowly added to the hydrochloric acid solution at a rate of 1 drop per second under stirring to perform acidification treatment, so that the furandicarboxylic acid was precipitated under acidic conditions, the obtained solid precipitate was further washed with deionized water for 6 times, dried in an oven, and 2,5-furan dicarboxylic acid pure product was obtained.

[0033] It was found by testing that the purity of the 2,5-furan dicarboxylic acid pure product prepared in this embodiment was 100%, and the contents of sodium, potassium, calcium, magnesium and iron were controlled within 6 ppm.

[0034] Example 3

[0035] (1) 3 mol of commercially available crude 2,5-furan dicarboxylic acid (purity 98%, sodium content 600 ppm or so, potassium, calcium and magnesium content 80 ppm or so, iron content 50 ppm or so) and 400 g of 28% ammonia water were sequentially added to a round-bottom flask, fully stirred for 30 min, heated to 80°C and continuously stirred for 1 h to fully dissolve and undergo neutralization reaction, and remove part of the excess monohydrate ammonia to obtain a mixed solution containing ammonium furandicarboxylate;

[0036] (2) The mixed solution was filtered, the filtrate was transferred to a 2000 ml separatory funnel, extracted with chloroform three times, then washed with petroleum ether once, the aqueous phase was transferred to a constant pressure dropping funnel, 860 g of 36% hydrochloric acid solution was weighed in a round-bottom flask, and the aqueous phase was slowly added to the hydrochloric acid solution at a rate of 1 drop per second under stirring to perform acidification treatment, so that the furandicarboxylic acid was precipitated under acidic conditions, the obtained solid precipitate was further washed with deionized water for 6 times, dried in an oven, and 2,5-furan dicarboxylic acid pure product was obtained.

[0037] The purity of the 2,5-furan dicarboxylic acid product prepared in this embodiment is 99.98%, and the content of metal elements such as sodium, potassium, calcium, magnesium and iron is controlled within 10 ppm.

[0038] Example 4

[0039] (1) 3 mol of commercially available crude 2,5-furan dicarboxylic acid (purity 99%, sodium content about 400 ppm, potassium content about 100 ppm, calcium content about 80 ppm, magnesium content about 60 ppm, and iron content about 20 ppm) was sequentially added to a round-bottom flask with 400 g of 28% ammonia water, and after fully stirring for 30 min, it was heated to 40°C and continuously stirred for 5 hours to fully dissolve and undergo neutralization reaction, and part of the excess monohydrate ammonia was removed to obtain a mixed solution containing ammonium furandicarboxylate;

[0040] (2) The mixed solution was filtered, and the filtrate was transferred to a 2000 ml separatory funnel, extracted with chloroform three times, and then washed with petroleum ether once. The aqueous phase was transferred to a constant-pressure dropping funnel, and 860 g of 36% hydrochloric acid solution was weighed in a round-bottom flask. Under stirring conditions, the aqueous phase was slowly added to the hydrochloric acid solution at a rate of 1 drop per second for acidification treatment, so that the furandicarboxylic acid was precipitated under acidic conditions. The obtained solid precipitate was further washed with deionized water three times, dried in an oven, and 2,5-furan dicarboxylic acid product was obtained.

[0041] The purity of the 2,5-furan dicarboxylic acid product prepared in this embodiment is 100%, and the content of metal elements such as sodium, potassium, calcium, magnesium and iron is controlled within 10 ppm.

[0042] Example 5

[0043] (1) 3 mol of commercially available crude 2,5-furan dicarboxylic acid (purity 99%, sodium content about 400 ppm, calcium content about 100 ppm, magnesium content about 80 ppm, potassium content about 70 ppm, and iron content about 30 ppm) was sequentially added to a round-bottom flask with 400 g of 28% ammonia water, and after fully stirring for 30 min, it was heated to 80°C and continuously stirred for 1 hour to fully dissolve and undergo neutralization reaction, and part of the excess monohydrate ammonia was removed to obtain a mixed solution containing ammonium furandicarboxylate;

[0044] (2) The resulting mixed solution is filtered, the filtrate is transferred to a 2000 ml separation funnel, extracted with chloroform three times, then washed with petroleum ether once, the aqueous phase is transferred to a constant pressure dropping funnel, 860 g of a 36% hydrochloric acid solution is weighed in a round bottom flask, the aqueous phase is slowly added to the hydrochloric acid solution at a rate of two seconds per drop under stirring to perform acidification treatment, furandicarboxylic acid is precipitated under acidic conditions, the resulting solid precipitate is further washed with deionized water three times, dried in an oven, and a pure product of 2,5-furandicarboxylic acid is obtained.

[0045] Tests show that the purity of the pure product of 2,5-furandicarboxylic acid prepared in this embodiment is 100%, and the content of metal elements such as sodium, potassium, calcium, magnesium and iron is controlled within 10 ppm.

[0046] Example 6

[0047] (1) 3 mol of commercially available crude 2,5-furandicarboxylic acid (purity 99%, sodium content about 400 ppm, calcium content about 100 ppm, magnesium content about 80 ppm, potassium content about 70 ppm, and iron content about 30 ppm) and 400 g of 28% ammonia water are sequentially added to a round bottom flask, stirred for 30 min, heated to 80°C and continue to stir for 1 hour to make it fully dissolved and neutralized, and remove part of the excess ammonia monohydrate to obtain a mixed solution containing ammonium furandicarboxylate;

[0048] (2) The resulting mixed solution is filtered, the filtrate is transferred to a 2000 ml separation funnel, extracted with chloroform three times, then washed with petroleum ether once, the aqueous phase is transferred to a constant pressure dropping funnel, 860 g of a 36% hydrochloric acid solution is weighed in a round bottom flask, the aqueous phase is slowly added to the hydrochloric acid solution at a rate of two seconds per drop under stirring to perform acidification treatment, furandicarboxylic acid is precipitated under acidic conditions, the resulting solid precipitate is further washed with deionized water three times, dried in an oven, and a pure product of 2,5-furandicarboxylic acid is obtained.

[0049] Tests show that the purity of the pure product of 2,5-furandicarboxylic acid prepared in this embodiment is 100%, and the content of metal elements such as sodium, potassium, calcium, magnesium and iron is controlled within 10 ppm.

[0050] Example 7

[0051] (1) 3 mol of commercially available crude furandicarboxylic acid (purity 99%, sodium element content about 400 ppm, potassium element content about 100 ppm, calcium element content about 80 ppm, magnesium element content about 60 ppm, iron element content about 20 ppm) and 400 g of 28% ammonia water were sequentially added to a round-bottom flask, fully stirred for 30 min, heated to 80°C and continuously stirred for 1 h to make it fully dissolved to occur neutralization reaction, and remove part of the excess ammonia monohydrate to obtain a mixed solution containing ammonium furandicarboxylate;

[0052] (2) The mixed solution was filtered, the filtrate was transferred to a 2000 ml separation funnel, extracted with dichloromethane three times, then washed with petroleum ether once, the aqueous phase was transferred to a constant pressure dropping funnel, 860 g of 36% hydrochloric acid solution was weighed in a round-bottom flask, and the aqueous phase was slowly added to the hydrochloric acid solution at a rate of 1 drop per second under stirring to perform acidification treatment, so that furandicarboxylic acid was precipitated under acidic conditions, the obtained solid precipitate was further washed with deionized water three times, dried in an oven, and 2,5-furandicarboxylic acid pure product was obtained.

[0053] It was found by testing that the purity of the 2,5-furandicarboxylic acid pure product prepared in this embodiment was 99.98%, and the metal element contents of sodium, potassium, calcium, magnesium and iron were controlled within 10 ppm.

[0054] Example 8

[0055] (1) 3 mol of commercially available crude furandicarboxylic acid (purity 99%, sodium element content about 400 ppm, potassium element content about 100 ppm, calcium element content about 80 ppm, magnesium element content about 60 ppm, iron element content about 20 ppm) and 6.6 mol of ethylamine were sequentially added to a round-bottom flask, fully stirred for 30 min, heated to 80°C and continuously stirred for 1 h to make it fully dissolved to occur neutralization reaction, and remove part of the excess ethylamine to obtain a salt solution containing furandicarboxylic acid and ethylamine;

[0056] (2) The mixed solution was filtered, the filtrate was transferred to a 2000 ml separation funnel, extracted with dichloromethane three times, then washed with petroleum ether once, the aqueous phase was transferred to a constant pressure dropping funnel, 860 g of 36% hydrochloric acid solution was weighed in a round-bottom flask, and the aqueous phase was slowly added to the hydrochloric acid solution at a rate of 1 drop per second under stirring to perform acidification treatment, so that furandicarboxylic acid was precipitated under acidic conditions, the obtained solid precipitate was further washed with deionized water three times, dried in an oven, and 2,5-furandicarboxylic acid pure product was obtained.

[0057] The purity of the 2,5-furan dicarboxylic acid product prepared in this example is 99.98%, and the content of metal elements such as sodium, potassium, calcium, magnesium and iron is controlled within 10 ppm.

[0058] Comparative Example 1

[0059] The difference between this comparative example and Example 1 is that the reaction temperature in step (1) is 15°C, and the other steps and parameters are the same. The reaction is slower at the lower temperature, and part of the solid remains in the mixed solution in step (1), which is detected to be undissolved ammonium furan dicarboxylate, and more aqueous ammonia remains in the solution.

[0060] The purity of the 2,5-furan dicarboxylic acid product prepared in this example is 99.99%, and the content of metal elements such as sodium, potassium, calcium, magnesium and iron is controlled within 10 ppm. Compared with Example 1, the yield is lower, and more aqueous ammonia remains in the solution, which consumes more acid and causes waste.

[0061] Comparative Example 2

[0062] The difference between this comparative example and Example 1 is that the heating and stirring reaction time in step (1) is 12 h, and the other steps and parameters are the same. The purity of the 2,5-furan dicarboxylic acid product prepared in this example is 100%, and the content of metal elements such as sodium, potassium, calcium, magnesium and iron is controlled within 10 ppm. Compared with Example 1, the impurity content does not decrease significantly, and additional time and energy are wasted.

[0063] Comparative Example 3

[0064] The difference between this comparative example and Example 1 is that the basic substance added in step (1) is sodium hydroxide, and the other steps and parameters are the same. The purity of the 2,5-furan dicarboxylic acid product prepared in this example is 100%, and the content of metal elements such as potassium, calcium, magnesium and iron is controlled within 10 ppm, and the content of sodium element is 60 ppm. Compared with Example 1, the content of sodium element is significantly increased.

[0065] Comparative Example 4

[0066] The difference between this comparative example and Example 1 is that the aqueous phase is added to the hydrochloric acid solution at one time in step (2), and the other steps and parameters are the same. The content of metal elements such as potassium, calcium, magnesium and iron in the 2,5-furan dicarboxylic acid product prepared in this example is controlled within 10 ppm, and the content of sodium element is 20 ppm. However, it is found that the furan dicarboxylate is not completely acidified, and part of the ammonium furan dicarboxylate remains in the product.

[0067] Comparative Example 5

[0068] The present comparative example is compared with example 1, the only difference is that the mass fraction of hydrochloric acid in step (2) is 5%, and the rest of the steps and parameters are the same. It is detected that the content of sodium, potassium, calcium, magnesium, iron and other metal elements of 2,5-furan dicarboxylic acid prepared in the present comparative example is controlled within 10 ppm. However, it is found that the furan dicarboxylic acid salt is not completely acidified, and the product still contains part of ammonium furan dicarboxylate.

[0069] The above examples have described the technical solutions of the present application in detail, and it should be understood that the above description is only a specific embodiment of the present application and is not used to limit the present application. Any modification, supplement or similar replacement within the principle range of the present application should be included in the protection scope of the present application.

Claims

1. A method for purifying 2,5-furan dicarboxylic acid, characterized by, The method comprises the following steps: (1) performing acid-base neutralization reaction of crude 2,5-furan dicarboxylic acid and basic amine substance to obtain a mixed solution; the basic amine substance is selected from organic base and / or ammonia water, and the organic base is ethylamine; (2) filtering and extracting the mixed solution to collect the aqueous phase, then adding the aqueous phase into an acid solution to make furan dicarboxylic acid precipitate under acidic conditions, and washing and drying to obtain pure 2,5-furan dicarboxylic acid; The crude 2,5-furan dicarboxylic acid is prepared by catalytic oxidation reaction of 5-hydroxymethylfurfural as raw material and using a metal catalyst; In step (1), the crude 2,5-furan dicarboxylic acid is added into the basic amine substance, fully stirred, and stirred and reacted under heating condition, the heating temperature is 40-80 DEG C, and the reaction time is 0.5-5 h; In step (2), the filtrate is extracted by using an organic solvent, and the organic solvent comprises at least one of trichloromethane, dichloromethane, ethyl acetate and petroleum ether; In step (2), the collected aqueous phase is added into the acid solution drop by drop under stirring condition at a speed of 0.5-2 s per drop for acidification treatment; the acid solution is hydrochloric acid with a mass fraction of 10-36% or sulfuric acid with a mass fraction of 10-50%; The molar ratio of hydrogen ions contained in the acid substance in the acid solution in step (2) to hydroxyl ions contained in the basic amine substance in step (1) is 1.1:1-4:1; The purity of the pure 2,5-furan dicarboxylic acid is greater than or equal to 99.98%, and the content of metal elements is within 10 ppm, wherein the metal elements comprise at least one of sodium, potassium, iron, magnesium and calcium.

2. The method for purifying 2,5-furan dicarboxylic acid according to claim 1, characterized by, The purity of the crude 2,5-furan dicarboxylic acid is greater than 98%.

3. The method of purifying 2,5-furan dicarboxylic acid according to claim 1, characterized by, The molar ratio of the basic amine substance to the crude 2,5-furan dicarboxylic acid is 2:1-5:1.

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