2,5-furandicarboxylic acid and a method for purifying the same

Abstract

This invention discloses a method for purifying 2,5-furandicarboxylic acid (FDCA), belonging to the field of chemical technology. The purification method includes the following steps: crude 2,5-furandicarboxylic acid is subjected to alkali dissolution, oxidation, acidification, stirring, pulping, washing, and drying to obtain pure 2,5-furandicarboxylic acid. In the acidification crystallization process and the pulping and washing process, by selecting appropriate conditions such as the acidification reaction temperature, the oxygen content of the oxidation gas, the pulping and washing temperature, and the pulping and washing time, the purity of the obtained FDCA can reach 99.99%. Moreover, no organic solvents are used, meeting the requirements of polymerization-grade products. Furthermore, and more importantly, the FDCA product obtained by this invention has excellent particle characteristics, high flowability, and high bulk density, which is highly beneficial for downstream polymerization reactions and also facilitates the packaging and transportation of the FDCA product.

Description

Technical Field

[0001] This invention belongs to the field of chemical technology, specifically relating to 2,5-furandicarboxylic acid and its purification method. Background Technology

[0002] 2,5-Furfural (FDCA) is a promising basic material that can replace the petroleum-based monomer terephthalic acid (PX) in the polymerization of ethylene glycol to produce high-performance polyesters. FDCA can be obtained by oxidation of 5-hydroxymethylfurfural (5-HMF). However, due to incomplete oxidation of 5-HMF, oxidation intermediates are usually generated, such as 5-formyl-2-furanic acid (FFCA), 2,5-dicarboxyfuran (DFF), and 5-hydroxymethyl-2-furanic acid (HMFCA). Under normal circumstances, the oxidation of FFCA to FDCA is the rate-determining step, and the FDCA product obtained from the oxidation of 5-HMF will contain FFCA impurities. In addition, due to changes in oxidation conditions, FDCA may undergo decarboxylation during the reaction process to produce 2-furanic acid (FCA). These monoformic acid impurities (FFCA or FCA) can terminate the growth of polyester molecular chains in the polymerization reaction, affecting the degree of polymerization. In addition, FFCA can also form chromophores, which will result in an unsatisfactory color of polyester materials, affecting their application in the beverage and food industry. Therefore, it is essential to purify FDCA.

[0003] Patent CN115028610A discloses a purification process for 2,5-furandicarboxylic acid. This process includes mixing crude FDCA, a metal ion removal agent, and a recrystallization solvent; heating under an inert gas atmosphere to fully dissolve the FDCA; then cooling to crystallize, filtering, washing, and drying to obtain pre-purified FDCA; subsequently, under an inert gas atmosphere, dissolving the pre-purified FDCA in a solvent and performing a hydrogenation reaction in the presence of a hydrogenation catalyst and hydrogen gas; followed by cooling to crystallize, filtering, washing, and drying to obtain 2,5-furandicarboxylic acid. This method can achieve a pure FDCA yield of over 98% and a transmittance of 98.6%. However, it utilizes metal catalysts such as palladium-based, ruthenium-based, nickel-based, cobalt-based, platinum-based, and copper-based catalysts. During the hydrogenation reaction, the loss of the active components of the catalyst can lead to an increase in the metal ion content of the FDCA product, affecting its purity. Furthermore, due to the influence of the hydrogenation reaction conditions, new impurities, such as tetrahydrofuran-2,5-dicarboxylic acid, may be generated during the hydrogenation process, which will also reduce the purity of the FDCA product.

[0004] Patent CN116003354A reports a method for crystallizing and purifying 2,5-furandicarboxylic acid. The method involves dissolving crude FDCA in a mixed solvent of ethylene glycol ether and water by heating, followed by cooling and crystallization to obtain 2,5-furandicarboxylic acid crystals. The purity of the FDCA product can reach 99.9%, the recovery rate is 70.3%, and the decolorization rate is 100%. However, this process uses organic solvents such as ethylene glycol ether, which can result in solvent residue in the product, which is not conducive to downstream polymerization reactions.

[0005] Patent CN114787140A discloses a heat treatment method for organic acids and purified 2,5-furandicarboxylic acid. The process includes the following steps: adding crude FDCA to an aqueous solution containing acetic acid, heat-treating at 140-200℃ for 5-240 min, then cooling to 20-80℃ to separate and obtain the FDCA product. This method can achieve removal rates of 83% and 75% for FDCA monomethyl ester (FDCA-Me) and 2-furandicarboxylic acid, respectively. This method utilizes acetic acid and carries out the purification process at high temperatures, which causes corrosion of the system and significant damage to the equipment. If corrosion-resistant equipment is used, this will increase investment costs. In addition, FDCA will undergo decarboxylation under high-temperature conditions, resulting in product loss.

[0006] Patent CN103965146A discloses a method for purifying furanyl dicarboxylic acid. This method involves dissolving the furanyl dicarboxylic acid to be purified in water through a salt formation reaction, filtering, acidifying the filtrate, filtering out the precipitated solid, washing, and drying to obtain high-purity furanyl dicarboxylic acid. Activated carbon is added during the alkali dissolution process. The adsorption of activated carbon can achieve the removal of impurities and decolorization. However, the adsorption of activated carbon is usually non-selective. It can adsorb furanyl dicarboxylate, thereby causing the loss of FDCA product and increasing the amount of solid waste.

[0007] FDCA products typically participate in downstream polymerization reactions in the form of solid particles. Therefore, the physical properties of FDCA, such as crystal morphology, size distribution, bulk density, and flowability, have a significant impact on the polymerization reaction. For example, low flowability of FDCA products can lead to uneven mixing of FDCA with other polymerization raw materials and catalysts, resulting in uneven reactant concentrations. This can negatively affect the polymerization time and the quality of the obtained polymer.

[0008] Patent CN116120264A discloses a method for controlling the particle size of 2,5-furandicarboxylic acid crystals. This method involves adding an additive to a raw material containing 2,5-furandicarboxylic acid, adjusting the type and content of the additive, and controlling process parameters such as crystallization temperature to obtain 2,5-furandicarboxylic acid crystals within a specific particle size range. However, this patent uses organic solvents, such as amide-based, pyrrolidone-based, and sulfoxide-based organic solvents, which can lead to residues of these organic solvents in the FDCA product, thus affecting product purity. Furthermore, the nucleating agent used in the patent is a metal compound; even if these nucleating agents are used at the ppm level, these metals can still remain in the product, affecting the purity of the polymerization-grade monomers. Summary of the Invention

[0009] The purpose of this invention is to provide 2,5-furandicarboxylic acid and its purification method to solve the problem of solvent, metal and other residues after purification of 2,5-furandicarboxylic acid.

[0010] The objective of this invention can be achieved through the following technical solutions:

[0011] A method for purifying 2,5-furandicarboxylic acid includes the following steps:

[0012] Step S1: Dissolve crude 2,5-furandicarboxylic acid in an alkaline aqueous solution to obtain an alkaline aqueous solution of 2,5-furandicarboxylic acid; 2,5-furandicarboxylic acid exists in the forms of 2,5-furandicarboxylic acid, 2,5-furandicarboxylic acid monocarboxylate, and / or 2,5-furandicarboxylate. This dissolution step involves the following reaction:

[0013]

[0014] Step S2: Add the above-obtained alkaline aqueous solution of 2,5-furandicarboxylic acid to a high-pressure reactor, and then oxidize the alkaline aqueous solution of 2,5-furandicarboxylic acid. After the oxidation treatment is completed, an oxidized solution is obtained.

[0015] Step S3: Add an acidic aqueous solution to the oxidizing solution for acidification treatment. 2,5-furandicarboxylic acid monocarboxylate and / or 2,5-furandicarboxylic acid dicarboxylate crystallize through the acidification reaction to form solid 2,5-furandicarboxylic acid, yielding a mixed solution. This acidification step involves the following reactions:

[0016]

[0017] Step S4: Filter the 2,5-furandicarboxylic acid solid obtained in step S3 to obtain 2,5-furandicarboxylic acid wet solid, and then add the wet solid to water for stirring, pulping and washing.

[0018] Step S5: After pulping and washing, filter to obtain pure wet 2,5-furandicarboxylic acid. Finally, dry the wet 2,5-furandicarboxylic acid to obtain pure 2,5-furandicarboxylic acid.

[0019] Furthermore, the alkaline aqueous solution is one or more of sodium hydroxide aqueous solution, sodium carbonate aqueous solution, potassium hydroxide aqueous solution, and potassium carbonate aqueous solution.

[0020] Furthermore, the conditions for oxidation treatment include pure oxygen or an oxygen-containing gas plus an oxidizing catalyst.

[0021] Furthermore, the oxidizing catalyst is a palladium-based, ruthenium-based, manganese-based, cobalt-based, molybdenum-based, copper-based, or composite metal oxide catalyst.

[0022] Furthermore, the oxygen-containing gas is oxygen-enriched air with an oxygen content greater than 21%.

[0023] Furthermore, the acidic aqueous solution is an inorganic acid aqueous solution; the inorganic acid is one or more of hydrochloric acid, sulfuric acid, and nitric acid.

[0024] Furthermore, the pH value of the acidification reaction is ≤4; the acidification reaction temperature is in the range of 30-80℃.

[0025] Furthermore, the stirring, pulping, and washing temperature is within the range of 80-160℃ during the pulping and washing process, and the stirring, pulping, and washing time is 0.5-12 hours.

[0026] Furthermore, the stirring, pulping, and washing temperature is within the range of 100-160℃ during the pulping process, and the stirring, pulping, and washing time is 1-4 hours.

[0027] A 2,5-furandicarboxylic acid was purified by the above method. The 2,5-furandicarboxylic acid had a b-value of less than 5, an angle of repose of 32-45 degrees, and a bulk density of 0.58-0.82 g / mL.

[0028] The beneficial effects of this invention are:

[0029] This invention provides a purification method for 2,5-furandicarboxylic acid. Crude 2,5-furandicarboxylic acid is subjected to alkali dissolution, oxidation, acidification, stirring, pulping, washing, and drying to obtain pure 2,5-furandicarboxylic acid. The purity of FDCA obtained by this invention can reach 99.99%, and no organic solvents are used, which meets the requirements of polymerization-grade products. More importantly, the FDCA product obtained by this invention has excellent particle characteristics, high flowability and bulk density, which is very beneficial to downstream polymerization reactions and also to the packaging and transportation of FDCA products.

[0030] By selecting appropriate conditions such as acidification reaction temperature, oxygen content of the oxidation treatment gas, pulping and washing temperature, and pulping and washing time during the acidification reaction crystallization process and pulping and washing process, this invention can obtain FDCA with a purity of 99.99%. The b-value of the prepared FDCA particles measured by a colorimeter is <1, and the particles have better flowability (angle of repose can reach 32°). These improvements in solid particle characteristics are due to the fact that the FDCA crystal particles obtained by this method are mainly irregular granular. The particle characteristics of the FDCA product prepared by this invention are particularly beneficial to the downstream polymerization process. Attached Figure Description

[0031] The invention will now be further described with reference to the accompanying drawings.

[0032] Figure 1 This is the HPLC chromatogram of the crude FDCA used in this invention;

[0033] Figure 2 These are microscope images of FDCA particles obtained in Example 1 of this invention;

[0034] Figure 3 This is the HPLC chromatogram of the pure FDCA obtained in Example 1 of this invention;

[0035] Figure 4 This is the X-ray powder diffraction pattern of the FDCA crystal particles obtained in Example 1 of this invention;

[0036] Figure 5 This is a microscope image of FDCA particles obtained in Comparative Example 1 of this invention. Detailed Implementation

[0037] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0038] Test method:

[0039] 1. Crystal morphology of FDCA particles

[0040] Images were taken using a digital polarizing microscope that measures both transmission and reflection.

[0041] 2. Dispersion

[0042] The angle of repose of the particles was determined using the test method specified in GB / T 16913-2008.

[0043] 3. Bulk density

[0044] The bulk density of the particles was determined using the test method specified in GB / T 16913-2008.

[0045] 4. HPLC analysis

[0046] The purity of FDCA was analyzed using a Shimadzu LC-16 instrument with a C18 column and an ultraviolet detector at a wavelength of 264 nm. Mobile phase A was methanol, and mobile phase B was 0.1% phosphoric acid aqueous solution. The column temperature was maintained at 40℃, and 10 μL of sample was injected for analysis. The peak position of FDCA was around 15 min.

[0047] The purification process of the present invention is described in more detail below, and the features of the present invention are illustrated in conjunction with embodiments.

[0048] The raw material used in process step S1 of this invention is crude FDCA, which is prepared by catalytic oxidation of 5-hydroxymethylfurfural. This oxidation process can be divided into homogeneous oxidation or heterogeneous oxidation. The former includes catalytic oxidation using Co / Mn / Br as a catalyst, while the latter includes catalytic oxidation using heterogeneous catalysts such as ruthenium-based, manganese-based, and cobalt-based catalysts. Due to incomplete oxidation, related impurities are generated. The resulting crude FDCA is shown in the HPLC analysis chromatogram. Figure 1 As shown. The alkaline solution used in step S1 can be prepared by mixing an alkaline solid with an aqueous solution. The alkaline solid can be one or more of the following: sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, and potassium bicarbonate. Sodium hydroxide is preferred. Ammonia water can also be used as the alkaline solution in step S1. Yongzhao Zhang et al. reported the solubility of FDCA in water in J. Chem. Eng. Data 2018, 63, 5, 1316-1324. Even at 90°C, 100g of water can only dissolve about 0.96g of FDCA. However, through step S1 of this invention, 100g of alkaline aqueous solution can dissolve more than 20g of FDCA, which is very beneficial for improving production efficiency.

[0049] In step S2 of this invention, an oxygen-containing gas is used to oxidize the FDCA solution obtained in step S1. This oxidation process can remove colorimetric impurities from the crude FDCA product. The oxygen-containing gas can be air, preferably oxygen-enriched air with an oxygen content greater than 21%, more preferably greater than 50%, and most preferably pure oxygen gas. It should be noted that an oxidizing catalyst can be used in the oxidation process. The catalyst can be palladium-based, ruthenium-based, manganese-based, cobalt-based, molybdenum-based, copper-based, or composite metal oxide catalysts. It should be particularly noted that when pure oxygen gas is used as the oxidizing gas, the effect of impurity removal and decolorization can be achieved without a catalyst.

[0050] In step S3 of this invention, the oxidized solution obtained in step S2 is acidified using an acidic aqueous solution. This process is an acidification reaction crystallization process, which can further purify FDCA. The acid used in step S3 can be an inorganic acid or an organic acid. The inorganic acid can be selected from hydrochloric acid, sulfuric acid, nitric acid, or phosphoric acid. The organic acid can be a saturated organic acid with 2 to 4 carbon atoms, with hydrochloric acid being preferred. Controlling the acidification reaction temperature in step S3 is necessary. The acidification temperature is in the range of 30-80℃, preferably between 50-80℃. The amount of acidic aqueous solution can be adjusted according to the pH value of the system. The pH value of the acidification reaction system can be selected to be less than 4, preferably less than 2.

[0051] In step S4 of this invention, pulping the solid obtained in step S3 is essential. As is well known, pulping can purify the product. By selecting appropriate pulping conditions, the physical properties of FDCA crystal particles can be improved. This improvement is highly beneficial for downstream polymerization applications. The FDCA particles obtained by this invention achieve excellent results when mixed with alkylene glycols. According to the inventors, due to the aging effect of Ostwald, the number of fine, fragmented FDCA particles gradually decreases, while the number of large-diameter FDCA particles gradually increases. Furthermore, due to the stirring action, the collisions between FDCA particles and the friction between the particles and the stirring paddle and the inner wall of the equipment further improve the characteristics of the FDCA particles. The temperature of the pulping process can be selected in the range of 80-160℃, preferably 100-160℃, and optimally 120-160℃; the pulping time can be selected in the range of 0.5-12h, preferably 1-10h, and optimally 1-4h.

[0052] Example 1

[0053] Weigh 100g of crude FDCA and add 500g of sodium hydroxide aqueous solution to completely dissolve it. Then, add 1g of ruthenium-carbon catalyst containing 5% active component to the FDCA sodium hydroxide aqueous solution, introduce pure oxygen gas, set the pressure to 1 MPa, and the temperature to 130℃, and perform oxidation treatment for 1 hour under stirring. After the oxidation time is completed, filter to obtain an oxidation liquid. Heat the oxidation liquid to 80℃, and then add hydrochloric acid aqueous solution to the oxidation liquid to make the pH value of the acidification reaction system to 1. At this time, a large amount of FDCA solid will precipitate. Cool to room temperature and filter to obtain FDCA wet filter cake. Then, add 500g of water to the FDCA wet filter cake, and then heat to 160℃ for washing for 4 hours. After washing, cool the system temperature to room temperature, filter to obtain FDCA wet filter cake, and dry to obtain pure FDCA. Analysis of the pure product showed that the purity of FDCA was 99.993%, the angle of repose was 32 degrees, the bulk density was 0.82 g / mL, and the b-value was 0.64 according to colorimeter analysis.

[0054] See the obtained microscopic images of FDCA particles. Figure 2 As shown;

[0055] The HPLC chromatogram of the obtained pure FDCA is shown in the figure. Figure 3 As shown;

[0056] The X-ray powder diffraction pattern of the obtained FDCA crystal particles is shown in the reference. Figure 4 As shown.

[0057] Example 2

[0058] Example 1 was repeated; the difference being that no catalyst was added to the FDCA sodium hydroxide aqueous solution, and pure oxygen gas was introduced for oxidation treatment. The obtained pure FDCA was analyzed, and the purity of FDCA was 99.991%, the angle of repose was 33 degrees, the bulk density was 0.81 g / mL, and the b-value was 0.66 according to colorimeter analysis.

[0059] Example 3

[0060] Example 1 was repeated; the difference being that oxygen-enriched air with an oxygen content of 50% was introduced for oxidation treatment. The obtained pure FDCA was analyzed, and the purity of FDCA was 99.94%, the angle of repose was 34 degrees, the bulk density was 0.78 g / mL, and the b-value was 1.32 according to colorimeter analysis.

[0061] Example 4

[0062] Example 1 was repeated; the difference being that air was introduced for oxidation treatment. The obtained pure FDCA was analyzed, and the purity of FDCA was 99.92%, the angle of repose was 33 degrees, the bulk density was 0.84 g / mL, and the b-value was 2.43 according to colorimeter analysis.

[0063] Example 5

[0064] Example 1 was repeated; the difference being that the pulping and washing temperature was 80°C. The obtained pure FDCA was analyzed, and the purity of FDCA was 99.95%, the angle of repose was 45 degrees, the bulk density was 0.58 g / mL, and the b-value was 0.92 according to the colorimeter analysis.

[0065] Example 6

[0066] Example 1 was repeated; the difference being that the pulping and washing time was 0.5 h. The obtained pure FDCA was analyzed, and the purity of FDCA was 99.98%, the angle of repose was 39 degrees, the bulk density was 0.61 g / mL, and the b-value was 0.71 according to the colorimeter analysis.

[0067] Example 7

[0068] Example 1 was repeated; the difference being that the acidification reaction temperature was 30°C. The obtained pure FDCA was analyzed, and the purity of FDCA was 99.91%, the angle of repose was 36 degrees, the bulk density was 0.71 g / mL, and the b-value was 1.01 according to the colorimeter analysis.

[0069] Comparative Example 1

[0070] 100g of crude FDCA was weighed and 500g of sodium hydroxide aqueous solution was added to completely dissolve it. Then, hydrochloric acid aqueous solution was added to the alkaline FDCA aqueous solution at 30℃ to acidify the system to pH 1. A large amount of FDCA solid precipitated out, which was then filtered to obtain a wet FDCA filter cake. 500g of water was added to the wet FDCA filter cake, and the mixture was washed at 25℃ for 4 hours. After washing, the wet FDCA filter cake was filtered again and dried to obtain pure FDCA. Analysis of the pure product showed a purity of 98.87%, an angle of repose of 55 degrees, a bulk density of 0.34g / mL, and a b-value of 7.81 according to colorimetry. Microscopic images of the obtained FDCA particles are available for reference. Figure 5 As shown.

[0071] Comparative Example 2

[0072] 100g of crude FDCA was weighed and 500g of sodium hydroxide aqueous solution was added to completely dissolve it. Then, hydrochloric acid aqueous solution was added to the alkaline FDCA aqueous solution at 80℃ to acidify the system to pH 1. A large amount of FDCA solid precipitated out during this process. The precipitated solid was then filtered to obtain a wet FDCA filter cake. 500g of water was added to the wet filter cake, and the mixture was washed at 25℃ for 4 hours. After washing, the wet filter cake was filtered again and dried to obtain pure FDCA. Analysis of the pure FDCA showed a purity of 99.84%, an angle of repose of 53 degrees, a bulk density of 0.36g / mL, and a b-value of 5.27 according to colorimeter analysis.

[0073] Comparative Example 3

[0074] 100g of crude FDCA was weighed and 500g of sodium hydroxide aqueous solution was added to completely dissolve it. Then, hydrochloric acid aqueous solution was added to the alkaline FDCA aqueous solution at 30℃ to acidify the system to pH 1. A large amount of FDCA solid precipitated out during this process. The precipitated solid was then filtered to obtain a wet FDCA filter cake. 500g of water was added to the wet filter cake, and the mixture was washed at 160℃ for 4 hours. After washing, the wet filter cake was filtered again and dried to obtain pure FDCA. Analysis of the pure product showed a purity of 99.53%, an angle of repose of 34 degrees, a bulk density of 0.79 g / mL, and a b-value of 6.23 according to colorimeter analysis.

[0075] Comparative Example 4

[0076] 100g of crude FDCA was weighed and dissolved completely in 500g of sodium hydroxide aqueous solution. Then, 1g of ruthenium-carbon catalyst containing 5% active component was added to the alkaline FDCA aqueous solution. Pure oxygen gas was introduced, and the pressure was set at 1 MPa and the temperature at 130℃. Oxidation was carried out for 1 hour under stirring. After the oxidation time, the solution was filtered to obtain an oxidized liquid. Subsequently, hydrochloric acid aqueous solution was added to the alkaline FDCA aqueous solution at 30℃ to make the pH of the acidification reaction system 1. At this time, a large amount of FDCA solid precipitated out. The solution was cooled to room temperature and filtered to obtain a wet FDCA filter cake. 500g of water was then added to the wet FDCA filter cake, and the mixture was washed at 25℃ for 4 hours. After washing, the wet FDCA filter cake was filtered and dried to obtain pure FDCA. Analysis of the pure product showed that the purity of FDCA was 99.96%, the angle of repose was 54 degrees, the bulk density was 0.35 g / mL, and the b-value was 0.87 according to colorimeter analysis.

[0077] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0078] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for purifying 2,5-furandicarboxylic acid, characterized in that, Includes the following steps: Step S1: Dissolve crude 2,5-furandicarboxylic acid in an alkaline aqueous solution to obtain an alkaline aqueous solution of 2,5-furandicarboxylic acid. Step S2: Oxidize the alkaline aqueous solution of 2,5-furandicarboxylic acid to obtain an oxidized solution after the oxidation process is complete. Step S3: Add an acidic aqueous solution to the oxidation solution for acidification treatment to generate solid 2,5-furandicarboxylic acid, and obtain a mixed solution; the pH value of the acidification treatment is ≤4; the acidification treatment temperature is in the range of 30-80℃. Step S4: Filter the mixture obtained in step S3 to obtain 2,5-furandicarboxylic acid wet solid. Then add the wet solid to water for stirring, pulping and washing. The stirring, pulping and washing temperature is within the range of 100-160℃, and the stirring, pulping and washing time is 1-4 hours. Step S5: After pulping and washing, filter to obtain pure wet 2,5-furandicarboxylic acid. Finally, dry the wet 2,5-furandicarboxylic acid to obtain pure 2,5-furandicarboxylic acid.

2. The purification method for 2,5-furandicarboxylic acid according to claim 1, characterized in that, The alkaline aqueous solution is one or more of sodium hydroxide aqueous solution, sodium carbonate aqueous solution, potassium hydroxide aqueous solution, and potassium carbonate aqueous solution.

3. The purification method for 2,5-furandicarboxylic acid according to claim 1, characterized in that, The conditions for oxidation treatment include pure oxygen or oxygen-containing gas + oxidizing catalyst.

4. The purification method for 2,5-furandicarboxylic acid according to claim 3, characterized in that, The oxidizing catalyst is a palladium-based, ruthenium-based, manganese-based, cobalt-based, molybdenum-based, copper-based, or composite metal oxide catalyst.

5. The purification method for 2,5-furandicarboxylic acid according to claim 3, characterized in that, The oxygen-containing gas is oxygen-enriched air with an oxygen content greater than 21%.

6. The purification method for 2,5-furandicarboxylic acid according to claim 1, characterized in that, The acidic aqueous solution is an inorganic acid aqueous solution; the inorganic acid is one or more of hydrochloric acid, sulfuric acid, and nitric acid.

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