Methods and applications for the preparation of 2,5-furandicarboxylic acid by oxidation of 5-hydroxymethylfurfural.

Abstract

This invention discloses a method for preparing 2,5-furandicarboxylic acid by oxidizing 5-hydroxymethylfurfural and its application. The method includes: mixing 5-hydroxymethylfurfural, a first solvent, a first oxidant, and an inorganic acid to carry out an oxidation reaction to obtain the intermediate product 2,5-dicarboxyfuran; and mixing the intermediate product 2,5-dicarboxyfuran, a second solvent, an inorganic base, a catalyst, and a second oxidant to carry out an oxidation reaction to obtain 2,5-furandicarboxylic acid. Therefore, 5-hydroxymethylfurfural can be oxidized to 2,5-furandicarboxylic acid under mild conditions, achieving a high conversion rate of 5-hydroxymethylfurfural and a high yield of 2,5-furandicarboxylic acid.

Description

Technical Field

[0001] This invention belongs to the field of biomass chemical engineering, specifically relating to a method for preparing 2,5-furandicarboxylic acid by oxidation of 5-hydroxymethylfurfural and its application. Background Technology

[0002] Producing bio-based chemicals from biomass is an important pathway to achieving carbon neutrality. Among these, 2,5-furandicarboxylic acid (FDCA) is listed by the U.S. Department of Energy as one of 12 high-value-added bio-based chemicals, from which a variety of important chemicals can be derived. Its most important use is as a monomer in the polymerization of ethylene glycol to obtain polyethylene 2,5-furandicarboxylate (PEF). Compared with traditional polyethylene terephthalate (PET), PEF polyester materials have advantages such as better airtightness, thermoplasticity, and tensile strength, and are considered a major alternative to PET materials. Currently, FDCA synthesis routes can be divided into five categories based on raw materials: furfural acid, diethylene glycol, adipic acid, furan, and 5-hydroxymethylfurfural. These raw materials can be used to synthesize FDCA through redox and disproportionation reactions, but the oxidative conversion of 5-hydroxymethylfurfural (HMF) has the most promising prospects for industrial application.

[0003] While existing technologies for preparing FDCA using HMF oxidation have achieved relatively high HMF conversion and FDCA yield, they still have drawbacks such as requiring high temperature and high pressure conditions, making it difficult to achieve continuous, efficient, and stable industrial-scale production.

[0004] Therefore, existing methods for preparing FDCA by HMF oxidation need further improvement. Summary of the Invention

[0005] This invention aims to at least partially solve one of the technical problems in related technologies. Therefore, one object of this invention is to provide a method and application for the oxidation of 5-hydroxymethylfurfural (HMF) to prepare 2,5-furandicarboxylic acid (FDCA), which can achieve the oxidation of HMF to FDCA under mild conditions and has high HMF conversion rate and FDCA yield.

[0006] The first aspect of the present invention provides a method for preparing 2,5-furandicarboxylic acid by oxidation of 5-hydroxymethylfurfural, comprising: (1) mixing 5-hydroxymethylfurfural, a first solvent, a first oxidant and an inorganic acid to carry out an oxidation reaction to obtain an intermediate product 2,5-dicarboxyfuran; and (2) mixing the intermediate product 2,5-dicarboxyfuran, a second solvent, an inorganic base, a catalyst and a second oxidant to carry out an oxidation reaction to obtain 2,5-furandicarboxylic acid.

[0007] The oxidation of HMF to FDCA requires the oxidation of both the hydroxyl and aldehyde groups in HMF to carboxyl groups. Under acidic conditions, the hydroxyl groups are preferentially oxidized to the aldehyde groups, while under alkaline conditions, the aldehyde groups are preferentially oxidized to the carboxyl groups. The inventors discovered that by mixing 5-hydroxymethylfurfural, a first solvent, a first oxidant, and an inorganic acid, the oxidation reaction can be carried out in a homogeneous or well-mixed two-phase emulsion system, thus accelerating the reaction rate. Under acidic conditions, the first oxidant preferentially oxidizes the hydroxyl groups in HMF to the aldehyde groups, yielding a high-yield intermediate product, 2,5-dicarboxyfuran (DFF). The second oxidant, under the action of an inorganic base and a catalyst, oxidizes DFF to FDCA under alkaline conditions, achieving a high yield of FDCA and avoiding the use of high-temperature and high-pressure conditions.

[0008] Therefore, the method of the present invention can realize the preparation of FDCA by HMF oxidation under mild conditions, and has high HMF conversion rate and FDCA yield.

[0009] In addition, the method for preparing 2,5-furandicarboxylic acid by oxidation of 5-hydroxymethylfurfural according to the present invention also has the following technical features:

[0010] In some embodiments of the present invention, in step (1), the first oxidant includes at least one selected from ferric chloride, ferric nitrate, vanadium oxysulfate, ferric citrate, nitric acid, ferric phosphate, copper chloride, copper nitrate, cerium nitrate, and sodium metavanadate. This increases the yield of the intermediate product 2,5-diformylfuran, thereby increasing the yield of FDCA.

[0011] In some embodiments of the present invention, in step (1), the first oxidant is regenerated by extraction and regeneration treatment. This reduces raw material costs.

[0012] In some embodiments of the present invention, in step (1), the concentration of the first oxidant is 0.01 mol / L to 3 mol / L. This increases the yield of the intermediate product 2,5-dicarboxyfuran, and consequently increases the yield of FDCA.

[0013] In some embodiments of the present invention, the first solvent and the second solvent each independently comprise at least one selected from dimethyl sulfoxide, N,N-dimethylformamide, acetonitrile, methyl isobutyl ketone, water, isopropanol, toluene, and acetic acid. This improves the substrate concentration, the yield of the intermediate product 2,5-diformylfuran, and the HMF conversion rate in the HMF oxidation process for preparing FDCA.

[0014] In some embodiments of the present invention, the first solvent and the second solvent each independently comprise water and / or methyl isobutyl ketone. This allows for further improvements in substrate concentration, yield of the intermediate product 2,5-dicarboxyfuran, and HMF conversion during the HMF oxidation process to FDCA.

[0015] In some embodiments of the present invention, the concentration of 5-hydroxymethylfurfural is 0.1 mol / L to 1 mol / L. This improves the substrate concentration, the yield of the intermediate product 2,5-dicarboxyfuran, and the HMF conversion rate in the HMF oxidation process for preparing FDCA.

[0016] In some embodiments of the present invention, in step (1), the molar ratio of 5-hydroxymethylfurfural to the first oxidant is 1-9:1-9. This improves the substrate concentration, the yield of the intermediate product 2,5-dicarboxyfuran, and the HMF conversion rate in the HMF oxidation process for preparing FDCA.

[0017] In some embodiments of the present invention, in step (1), the intermediate product 2,5-diformylfuran is obtained by extraction and distillation. This allows for a high extraction rate of the intermediate product.

[0018] In some embodiments of the present invention, the extractant used for the extraction of the intermediate product 2,5-dicarboxyfuran includes at least one selected from ethyl acetate, methyl isobutyl ketone, diethyl ether, and n-butanol. This allows for a high extraction rate of the intermediate product.

[0019] In some embodiments of the present invention, the extractant used for extracting the intermediate product 2,5-dicarboxyfuran is methyl isobutyl ketone. This can further improve the extraction rate of the intermediate product 2,5-dicarboxyfuran.

[0020] In some embodiments of the present invention, the volume ratio of the reaction mixture to the extractant in the extraction process is 1-9:1-9. This can further improve the extraction rate of the intermediate product 2,5-diformylfuran.

[0021] In some embodiments of the present invention, in step (2), the second oxidant includes at least one of hydrogen peroxide, air, and oxygen. Thus, the second oxidant is an inexpensive and clean oxidant, and the reduction products of the second oxidant can avoid contamination of the target product FDCA.

[0022] In some embodiments of the present invention, in step (2), the second oxidant is hydrogen peroxide, and the molar ratio of the second oxidant to the intermediate product 2,5-dicarboxyfuran is 1-30:1. This improves the conversion rate of the intermediate product 2,5-dicarboxyfuran and the yield of FDCA.

[0023] In some embodiments of the present invention, in step (2), the second oxidant is air or oxygen, and the reaction pressure is 0.1 MPa-2 MPa. This improves the conversion rate of the intermediate 2,5-diformylfuran and the yield of FDCA.

[0024] In some embodiments of the present invention, in step (2), the catalyst includes at least one selected from copper oxide, manganese dioxide, nickel oxide, silver oxide, cobalt oxide, iron oxide, iron(II,III) oxide, and cobalt(II,III) oxide. Therefore, using this type of catalyst can accelerate the reaction rate.

[0025] In some embodiments of the present invention, the catalyst in step (2) is silver oxide. Therefore, using silver oxide as a catalyst can further accelerate the reaction rate.

[0026] In some embodiments of the present invention, in step (2), the inorganic base includes at least one of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, and potassium bicarbonate. Thus, the intermediate product DFF is converted to FDCA under alkaline conditions, ensuring a high FDCA yield while avoiding the use of high temperature and high pressure conditions.

[0027] In some embodiments of the present invention, in step (2), the inorganic base includes at least one of sodium carbonate, potassium carbonate, sodium bicarbonate, and potassium bicarbonate. Thus, the intermediate product DFF is converted to FDCA under alkaline conditions, ensuring a high FDCA yield, while avoiding the use of high temperature and high pressure conditions.

[0028] In some embodiments of the present invention, in step (2), the concentration of the inorganic base is 0.001 mol / L to 6 mol / L. Thus, the intermediate product DFF is rapidly converted to FDCA under alkaline conditions, ensuring a high FDCA yield, and avoiding the use of high temperature and high pressure conditions.

[0029] In some embodiments of the present invention, in step (2), the concentration of the inorganic base is 0.01 mol / L-4 mol / L. Thus, the intermediate product DFF is rapidly converted to FDCA under alkaline conditions, ensuring a higher FDCA yield, while avoiding the use of high temperature and high pressure conditions.

[0030] In some embodiments of the present invention, in step (1), the conditions for the oxidation reaction include: a reaction temperature of 20°C-100°C; and / or a reaction time of 1 h-12 h. This increases the reaction rate and ensures a higher yield of the intermediate product 2,5-dicarboxyfuran, thereby increasing the yield of FDCA.

[0031] In some embodiments of the present invention, in step (1), the conditions for the oxidation reaction include: a reaction temperature of 40°C-60°C; and / or a reaction time of 4h-8h. This further improves the reaction rate and selectivity, and ensures a higher yield of the intermediate product 2,5-dicarboxyfuran, thereby further increasing the yield of FDCA.

[0032] In some embodiments of the present invention, in step (2), the conditions for the oxidation reaction include: a reaction temperature of 20°C-100°C; and / or a reaction time of 1 h-12 h. This improves the reaction rate and ensures a higher conversion rate of the intermediate product 2,5-dicarboxyfuran, thereby increasing the yield of FDCA.

[0033] In some embodiments of the present invention, in step (2), the conditions for the oxidation reaction include: a reaction temperature of 70°C-80°C; and / or a reaction time of 2h-4h. This further improves the reaction rate and selectivity and ensures a higher conversion rate of the intermediate product 2,5-dicarboxyfuran, thereby further increasing the yield of FDCA.

[0034] A second aspect of the present invention provides a polyethylene 2,5-furandicarboxylate (PEF), which is obtained by polymerizing ethylene glycol with 2,5-furandicarboxylic acid, which is prepared by the method described above, as a monomer.

[0035] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0036] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0037] Figure 1 This is a flowchart of a method for preparing 2,5-furandicarboxylic acid by oxidation of 5-hydroxymethylfurfural according to one embodiment of the present invention.

[0038] Figure 2 This is a flowchart illustrating one embodiment of the present invention.

[0039] Figure labels: 1-First-stage oxidation reactor; 2-Extraction tower; 3-Evaporator; 4-Regenerator; 5-Second-stage oxidation reactor; 6-Separation and purification unit. Detailed Implementation

[0040] The embodiments of the present invention are described in detail below, and are intended to explain the present invention, but should not be construed as limiting the present invention.

[0041] The first aspect of the present invention provides a method for preparing 2,5-furandicarboxylic acid by oxidation of 5-hydroxymethylfurfural, according to embodiments of the present invention, with reference to Figure 1 The method includes:

[0042] S100: An oxidation reaction is carried out by mixing 5-hydroxymethylfurfural, a first solvent, a first oxidizing agent, and an inorganic acid.

[0043] In this step, the oxidation reaction is accelerated by mixing 5-hydroxymethylfurfural, a first solvent, a first oxidant, and an inorganic acid, allowing the oxidation reaction to proceed in a homogeneous or well-mixed two-phase emulsion system. Under acidic conditions, the first oxidant preferentially oxidizes the hydroxyl groups in HMF to aldehyde groups, yielding a high-yield intermediate product, 2,5-dicarboxyfuran (DFF). Therefore, a high-yield intermediate product, 2,5-dicarboxyfuran, can be obtained using HMF oxidation under mild conditions.

[0044] In some embodiments of the present invention, in S100, the first oxidant includes at least one selected from ferric chloride, ferric nitrate, vanadium oxysulfate, ferric citrate, nitric acid, ferric phosphate, copper chloride, copper nitrate, cerium nitrate, and sodium metavanadate. This increases the yield of the intermediate product 2,5-diformylfuran, thereby increasing the yield of FDCA.

[0045] In some embodiments of the present invention, in S100, the first oxidant may be vanadium oxysulfate, which is obtained by reacting vanadium pentoxide with sulfuric acid.

[0046] In some embodiments of the present invention, in S100, the first oxidant is regenerated through extraction and regeneration treatment. Specifically: 5-hydroxymethylfurfural, a first solvent, a first oxidant, and an inorganic acid are mixed; 5-hydroxymethylfurfural undergoes an oxidation reaction under the action of the first oxidant to obtain a reaction mixture; the obtained reaction mixture is extracted to obtain an extract and a raffinate; the obtained raffinate is regenerated to regenerate the first oxidant. The regeneration of the first oxidant uses an oxidant with a higher redox potential than the first oxidant itself. Using a regenerable first oxidant for HMF oxidation can reduce costs and increase the yield of intermediate products.

[0047] In some embodiments of the present invention, in S100, the concentration of the first oxidant is 0.01 mol / L to 3 mol / L. For example, it can be 0.01 mol / L, 0.05 mol / L, 0.1 mol / L, 0.5 mol / L, 1.0 mol / L, 1.5 mol / L, 2.0 mol / L, 2.5 mol / L, 3.0 mol / L, etc. By controlling the concentration of the first oxidant within the above range, the inventors are able to increase the yield of the intermediate product 2,5-dicarboxyfuran, and thus increase the yield of FDCA. It should be noted that the concentration of the first oxidant refers to its concentration in the reaction system.

[0048] In some embodiments of the present invention, in S100, the first solvent includes at least one selected from dimethyl sulfoxide, N,N-dimethylformamide, acetonitrile, methyl isobutyl ketone, water, isopropanol, toluene, and acetic acid. The first solvent exhibits good solubility and stability for HMF, is not oxidized by the first oxidant used, and allows the formed intermediate product 2,5-diformylfuran to be extracted in situ into the solvent, reducing its residence time in the aqueous phase and minimizing intermediate product loss. Therefore, the substrate concentration, yield of the intermediate product 2,5-diformylfuran, and HMF conversion rate can be improved during the oxidation of HMF to prepare FDCA.

[0049] In some embodiments of the present invention, in S100, the first solvent comprises water and / or methyl isobutyl ketone. This allows for further improvement in the substrate concentration, the yield of the intermediate product 2,5-dicarboxyfuran, and the HMF conversion rate during the HMF oxidation process to FDCA.

[0050] In some embodiments of the present invention, in S100, the concentration of 5-hydroxymethylfurfural is 0.1 mol / L-1 mol / L, for example, 0.1 mol / L, 0.5 mol / L, 1.0 mol / L, etc. Therefore, by controlling the concentration of the reaction substrate HMF within the above range, the inventors can avoid side reactions such as degradation of HMF and DFF, achieve a high concentration of HMF substrate oxidation conversion, and have a high HMF conversion rate. It should be noted that the concentration of 5-hydroxymethylfurfural refers to the concentration of 5-hydroxymethylfurfural in the reaction system, not the concentration of the 5-hydroxymethylfurfural raw material.

[0051] In some embodiments of the present invention, in S100, the molar ratio of 5-hydroxymethylfurfural to the first oxidant is 1-9:1-9, for example, it can be 1:1, 1:5, 1:9, 5:1, 5:9, 9:1, 9:5, etc. Therefore, by controlling the molar ratio of the reaction substrate HMF to the first oxidant within the above range, the inventors can avoid side reactions such as ring-opening between HMF and DFF, and can improve the yield of the intermediate product 2,5-dicarboxyfuran, thereby improving the yield of FDCA.

[0052] In some embodiments of the present invention, in S100, the intermediate product 2,5-dicarboxyfuran is obtained by extraction and distillation. Specifically: 5-hydroxymethylfurfural, a first solvent, a first oxidant, and an inorganic acid are mixed; 5-hydroxymethylfurfural undergoes an oxidation reaction under the action of the first oxidant to obtain a reaction mixture; the obtained reaction mixture is extracted to obtain an extract and a raffinate; the obtained extract is distilled to recover the extractant and obtain the intermediate product 2,5-dicarboxyfuran. The distillation is carried out under reduced pressure and low temperature to avoid side reactions such as self-condensation polymerization of the intermediate product 2,5-dicarboxyfuran at higher temperatures. This improves the yield of the intermediate product 2,5-dicarboxyfuran, thereby increasing the yield of FDCA.

[0053] According to one embodiment of the present invention, in S100, after the intermediate product 2,5-dicarboxyfuran is extracted, the solvent phase containing DFF after extraction can be directly used for the second oxidation reaction.

[0054] In some embodiments of the present invention, the extractant used for the extraction of the intermediate product 2,5-dicarboxyfuran includes at least one selected from ethyl acetate, methyl isobutyl ketone, diethyl ether, and n-butanol. This allows for a high extraction rate of the intermediate product.

[0055] In some embodiments of the present invention, the extractant used for extracting the intermediate product 2,5-dicarboxyfuran is methyl isobutyl ketone. This can further improve the extraction rate of the intermediate product 2,5-dicarboxyfuran.

[0056] In some embodiments of the present invention, the volume ratio of the reaction mixture to the extractant in the extraction process is 1-9:9-1, for example, it can be 1:1, 1:5, 1:9, 5:1, 5:9, 9:1, 9:5, etc. This can further improve the extraction rate of the intermediate product 2,5-diformylfuran.

[0057] In some embodiments of the present invention, in S100, the conditions of the oxidation reaction include: a reaction temperature of 20°C-100°C; and / or a reaction time of 1 h-12 h. Therefore, by controlling the reaction temperature and / or reaction time within the above ranges, the present invention can improve the reaction rate and ensure a high yield of the intermediate product 2,5-dicarboxyfuran, thereby improving the yield of FDCA.

[0058] In some embodiments of the present invention, in S100, the conditions for the oxidation reaction include: a reaction temperature of 40°C-60°C; and / or a reaction time of 4h-8h. For example, in S100, the conditions for the oxidation reaction can be a reaction temperature of 50°C and a reaction time of 8h. This can further improve the yield of the intermediate product 2,5-dicarboxyfuran and the yield of FDCA.

[0059] S200: The intermediate product 2,5-dicarboxyfuran, a second solvent, an inorganic base, a catalyst, and a second oxidant are mixed to carry out an oxidation reaction.

[0060] In this step, the intermediate product 2,5-dicarboxyfuran, a second solvent, an inorganic base, a catalyst, and a second oxidant are mixed and subjected to an oxidation reaction. The intermediate product 2,5-dicarboxyfuran (DFF) is oxidized to FDCA under alkaline conditions, yielding a high FDCA yield and avoiding the use of high temperature and high pressure conditions. Therefore, FDCA can be prepared by oxidation using HMF under mild conditions, with high HMF conversion and FDCA yield.

[0061] In some embodiments of the present invention, in S200, the second oxidant includes at least one of hydrogen peroxide, air, and oxygen. Thus, the second oxidant is an inexpensive and clean oxidant and can avoid contamination of the target product FDCA by the reduction products of the second oxidant.

[0062] In some embodiments of the present invention, in S200, the second oxidant is hydrogen peroxide, and the molar ratio of the second oxidant to the intermediate product 2,5-dicarboxyfuran is 1-30:1, for example, 1:1, 5:1, 10:1, 15:1, 20:1, 25:1, 30:1, etc. This improves the conversion rate of the intermediate product 2,5-dicarboxyfuran and the yield of FDCA.

[0063] In some embodiments of the present invention, in S200, the second oxidant is air or oxygen, and the reaction pressure is 0.1 MPa-2 MPa, for example, 0.1 MPa, 0.5 MPa, 1.0 MPa, 1.5 MPa, 2.0 MPa, etc. This improves the conversion rate of the intermediate product 2,5-diformylfuran and the yield of FDCA.

[0064] In some embodiments of the present invention, in S200, the catalyst includes at least one selected from copper oxide, manganese dioxide, nickel oxide, silver oxide, cobalt oxide, iron oxide, iron(II,III) oxide, and cobalt(II,III) oxide. While the oxidant is thermodynamically feasible to oxidize the intermediate product to FDCA, the kinetic rate is slow. Therefore, a catalyst is needed to lower the activation energy and increase the reaction rate. Thus, using this type of catalyst can accelerate the reaction process.

[0065] In some embodiments of the present invention, in step S200, the catalyst is silver oxide. Therefore, using this type of catalyst can further accelerate the reaction process.

[0066] In some embodiments of the present invention, in S200, the inorganic base includes at least one selected from sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, and potassium bicarbonate. Thus, the intermediate product DFF is converted to FDCA under alkaline conditions, ensuring a high FDCA yield while avoiding the use of high temperature and high pressure conditions.

[0067] In some embodiments of the present invention, in S200, the inorganic base includes at least one selected from sodium carbonate, potassium carbonate, sodium bicarbonate, and potassium bicarbonate. Thus, the intermediate product DFF is converted to FDCA under alkaline conditions, ensuring a higher FDCA yield while avoiding the use of high temperature and high pressure conditions.

[0068] In some embodiments of the present invention, in S200, the concentration of the inorganic base is 0.001 mol / L to 6 mol / L. By controlling the concentration of the inorganic base within the above range, the present invention can reduce the residence time of the intermediate product 2,5-dicarboxyfuran in the system, reduce the occurrence of side reactions, and avoid the use of high temperature and high pressure conditions. It should be noted that the concentration of the inorganic base refers to the concentration in the aqueous phase.

[0069] In some embodiments of the present invention, in step S200, the concentration of the inorganic base is 0.01 mol / L to 4 mol / L. For example, in step S200, the concentration of the inorganic base can be 0.01 mol / L, 0.05 mol / L, 0.1 mol / L, 0.5 mol / L, 1.0 mol / L, 2.0 mol / L, 3.0 mol / L, 4.0 mol / L, etc.

[0070] Therefore, the intermediate product DFF can be converted into FDCA under alkaline conditions, ensuring a higher FDCA yield, while avoiding the use of high temperature and high pressure conditions.

[0071] In some embodiments of the present invention, in S200, the conditions of the oxidation reaction include: a reaction temperature of 20°C-100°C; and / or a reaction time of 1 h-12 h. Therefore, by controlling the reaction temperature and / or reaction time within the above ranges, the present invention can improve the reaction rate and ensure a high conversion rate of the intermediate product 2,5-dicarboxyfuran, thereby increasing the yield of FDCA.

[0072] In some embodiments of the present invention, in S200, the conditions for the oxidation reaction include: a reaction temperature of 70°C-80°C; and / or a reaction time of 2h-4h. For example, in S200, the conditions for the oxidation reaction can be a reaction temperature of 80°C and a reaction time of 2h. Therefore, by controlling the reaction temperature and / or reaction time within the above ranges, the present invention can further improve the reaction rate and ensure a higher conversion rate of the intermediate product 2,5-dicarboxyfuran, thereby further improving the yield of FDCA.

[0073] A second aspect of the present invention provides a polyethylene 2,5-furandicarboxylate (PEF), which is obtained by polymerizing ethylene glycol with 2,5-furandicarboxylic acid, which is prepared by the method described above, as a monomer.

[0074] The present invention will now be described with reference to specific embodiments. It should be noted that these embodiments are merely descriptive and do not limit the present invention in any way.

[0075] In the following examples, the conversion rate of 5-hydroxymethylfurfural (HMF), the yield of the intermediate product 2,5-dicarboxyfuran (DFF), and the yield of 2,5-furandicarboxylic acid (FDCA) were calculated using the following formulas.

[0076] HMF conversion rate (%) = (1 - molar amount of HMF in the product / initial molar amount of HMF) × 100%

[0077] DFF yield (%) = (Molar amount of DFF in the product / Initial molar amount of HMF) × 100%

[0078] FDCA yield (%) = (Molar amount of FDCA in the product / Initial molar amount of HMF) × 100%

[0079] Example

[0080] This invention illustrates the method for preparing FDCA from 5-hydroxymethylfurfural.

[0081] Example 1

[0082] 3 mmol of 5-hydroxymethylfurfural (HMF) was dissolved in 50 mL of water, and 18 mmol of vanadium oxysulfate and 80 mmol of sulfuric acid were added to react. After reacting at room temperature for 12 h, a reaction mixture was obtained. The mixture was extracted to obtain an intermediate product. 1 mmol of the intermediate product, 2 mmol of sodium bicarbonate, and 0.1 g of silver oxide were added to 20 mL of water, and oxygen was continuously bubbled through at 0.1 MPa. After reacting at 80 °C for 4 h, FDCA was obtained.

[0083] 3 mmol of 5-hydroxymethylfurfural was dissolved in 50 ml of water, and 18 mmol of ferric chloride and 80 mmol of sulfuric acid were added to react the mixture. After reacting at 70 °C for 12 h, a reaction mixture was obtained. The mixture was extracted to obtain an intermediate product. 1 mmol of the intermediate product, 2 mmol of sodium bicarbonate, and 0.1 g of silver oxide were added to 20 ml of water, and oxygen was continuously bubbled through at 0.1 MPa. After reacting at 80 °C for 4 h, FDCA was obtained.

[0084] 3 mmol of 5-hydroxymethylfurfural was dissolved in 50 ml of water, and 18 mmol of ferric nitrate and 80 mmol of sulfuric acid were added to react the mixture. After reacting at 70 °C for 12 h, a reaction mixture was obtained. The mixture was extracted to obtain an intermediate product. 1 mmol of the intermediate product, 2 mmol of sodium bicarbonate, and 0.1 g of silver oxide were added to 20 ml of water, and oxygen was continuously bubbled through at 0.1 MPa. After reacting at 80 °C for 4 h, FDCA was obtained.

[0085] 3 mmol of 5-hydroxymethylfurfural was dissolved in 50 ml of water, and 18 mmol of nitric acid and 80 mmol of sulfuric acid were added to react the mixture. After reacting at 50 °C for 12 h, a reaction mixture was obtained. The mixture was extracted to obtain an intermediate product. 1 mmol of the intermediate product, 2 mmol of sodium bicarbonate, and 0.1 g of silver oxide were added to 20 ml of water, and oxygen was continuously bubbled through at 0.1 MPa. After reacting at 80 °C for 4 h, FDCA was obtained.

[0086] 3 mmol of 5-hydroxymethylfurfural was dissolved in 50 ml of water, and 18 mmol of copper nitrate and 80 mmol of sulfuric acid were added. The reaction was carried out at 80 °C for 12 h to obtain a reaction mixture. The mixture was extracted to obtain an intermediate product. 1 mmol of the intermediate product, 2 mmol of sodium bicarbonate, and 0.1 g of silver oxide were added to 20 ml of water, and oxygen was continuously bubbled through at 0.1 MPa. The reaction was carried out at 80 °C for 4 h to obtain FDCA.

[0087] 3 mmol of 5-hydroxymethylfurfural was dissolved in 50 ml of water, and 18 mmol of cerium nitrate and 80 mmol of sulfuric acid were added. The reaction was carried out at 40 °C for 12 h to obtain a reaction mixture. The mixture was extracted to obtain an intermediate product. 1 mmol of the intermediate product, 2 mmol of sodium bicarbonate, and 0.1 g of silver oxide were added to 20 ml of water, and oxygen was continuously bubbled through at 0.1 MPa. The reaction was carried out at 80 °C for 4 h, followed by separation and purification to obtain FDCA.

[0088] 3 mmol of 5-hydroxymethylfurfural was dissolved in 50 ml of water, and 18 mmol of sodium metavanadate and 80 mmol of sulfuric acid were added. The reaction was carried out at 60 °C for 12 h to obtain a reaction mixture. The mixture was extracted to obtain an intermediate product. 1 mmol of the intermediate product, 2 mmol of sodium bicarbonate, and 0.1 g of silver oxide were added to 20 ml of water, and oxygen was continuously bubbled through at 0.1 MPa. The reaction was carried out at 80 °C for 4 h, followed by separation and purification to obtain FDCA.

[0089] After each reaction was completed, samples were taken for testing to determine the HMF conversion rate, intermediate product yield, and FDCA yield. The results are shown in Table 1.

[0090] Table 1. Effect of the primary oxidant on the catalytic oxidation performance of HMF

[0091] First oxidizing agent HMF conversion rate (%) DFF yield (%) FDCA yield (%) Ferric chloride 90.53 70.21 67.41 Ferric nitrate 100.00 75.28 72.27 Vanadium oxysulfate 95.64 91.56 87.90 Nitric acid 100.00 42.73 41.02 Copper nitrate 95.86 67.54 64.84 Cerium nitrate 100.00 79.50 76.32 Sodium metavanadate 98.68 53.24 51.11

[0092] Example 2

[0093] 0.5 mmol of 5-hydroxymethylfurfural (HMF) was dissolved in 50 mL of water, and 18 mmol of vanadium sulfate and 80 mmol of sulfuric acid were added to react. After reacting at room temperature for 12 h, a reaction mixture was obtained. The mixture was extracted to obtain an intermediate product. 1 mmol of the intermediate product, 2 mmol of sodium bicarbonate, and 0.1 g of silver oxide were added to water, and oxygen was continuously bubbled through at 0.1 MPa. The mixture was reacted at 80 °C for 4 h, followed by separation and purification to obtain FDCA.

[0094] 5 mmol of 5-hydroxymethylfurfural (HMF) was dissolved in 50 ml of water, and 18 mmol of vanadium oxysulfate and 80 mmol of sulfuric acid were added to react. After reacting at room temperature for 12 h, a reaction mixture was obtained. The mixture was extracted to obtain an intermediate product. 1 mmol of the intermediate product, 2 mmol of sodium bicarbonate, and 0.1 g of silver oxide were added to water, and oxygen was continuously bubbled through at 0.1 MPa. The mixture was reacted at 80 °C for 4 h, followed by separation and purification to obtain FDCA.

[0095] 50 mmol of 5-hydroxymethylfurfural (HMF) was dissolved in 50 ml of water, and 100 mmol of vanadium oxysulfate and 400 mmol of sulfuric acid were added to react. After reacting at room temperature for 12 h, a reaction mixture was obtained. The mixture was extracted to obtain an intermediate product. 1 mmol of the intermediate product, 2 mmol of sodium bicarbonate, and 0.1 g of silver oxide were added to water, and oxygen was continuously bubbled through at 0.1 MPa. The mixture was reacted at 80 °C for 4 h, followed by separation and purification to obtain FDCA.

[0096] After each reaction was completed, samples were taken for testing to determine the HMF conversion rate, intermediate product yield, and FDCA yield. The results are shown in Table 2.

[0097] Table 2. Effects of HMF concentration on synthetic intermediates and FDCA

[0098] HMF concentration (mol / L) HMF conversion rate (%) DFF yield (%) FDCA yield (%) 0.01 100.00 92.33 88.64 0.1 91.22 90.08 86.48 1 88.03 87.52 84.02 3 60.35 71.02 62.16

[0099] Example 3

[0100] 6 mmol HMF, 18 mmol vanadium oxysulfate, and 80 mmol sulfuric acid were dissolved in 50 ml of water and reacted at 40 °C, 60 °C, and 80 °C. Samples were taken at 2 h, 4 h, and 8 h to detect the intermediate product. 1 mmol of the intermediate product, 2 mmol sodium bicarbonate, and 0.1 g silver oxide were reacted at 80 °C for 4 h with oxygen continuously bubbled through, yielding FDCA. The results are shown in Table 3.

[0101] Table 3 Effects of reaction conditions on HMF synthesis intermediates and FDCA

[0102]

[0103]

[0104] Example 4

[0105] 24 mmol HMF was dissolved in 200 ml of water, and 72 mmol of vanadium oxysulfate and 320 mmol of sulfuric acid were added to react the mixture. After reacting at 60 °C for 8 h, a reaction mixture was obtained. The mixture was extracted with ethyl acetate at a volume ratio of 1:1 to the reaction mixture to obtain an intermediate product. 1 mmol of the intermediate product, 2 mmol of sodium bicarbonate, and 0.1 g of silver oxide were added to water, and oxygen was continuously bubbled through at 0.1 MPa. After reacting at 80 °C for 4 h, FDCA was obtained. After the reaction was completed, samples were taken for analysis, and the results are shown in Table 4.

[0106] 24 mmol HMF was dissolved in 200 ml of water, and 72 mmol of vanadium oxysulfate and 320 mmol of sulfuric acid were added to react the mixture. After reacting at 60 °C for 8 h, a reaction mixture was obtained. The mixture was extracted with methyl isobutyl ketone at a volume ratio of 1:1 to the reaction mixture to obtain an intermediate product. 1 mmol of the intermediate product, 2 mmol of sodium bicarbonate, and 0.1 g of silver oxide were added to water, and oxygen was continuously bubbled through at 0.1 MPa. After reacting at 80 °C for 4 h, FDCA was obtained. After the reaction was completed, samples were taken for analysis, and the results are shown in Table 4.

[0107] 24 mmol HMF was dissolved in 200 ml of water, and 72 mmol of vanadium oxysulfate and 320 mmol of sulfuric acid were added to react the mixture. After reacting at 60 °C for 8 h, a reaction mixture was obtained. The mixture was extracted with diethyl ether at a volume ratio of 1:1 to the reaction mixture to obtain an intermediate product. 1 mmol of the intermediate product, 2 mmol of sodium bicarbonate, and 0.1 g of silver oxide were added to water, and oxygen was continuously bubbled through at 0.1 MPa. After reacting at 80 °C for 4 h, FDCA was obtained. After the reaction was completed, samples were taken for analysis, and the results are shown in Table 4.

[0108] 24 mmol HMF was dissolved in 200 ml of water, and 72 mmol of vanadium oxysulfate and 320 mmol of sulfuric acid were added to react the mixture. After reacting at 60 °C for 8 h, a reaction mixture was obtained. The mixture was extracted with n-butanol at a volume ratio of 1:1 to the reaction mixture to obtain an intermediate product. 1 mmol of the intermediate product, 2 mmol of sodium bicarbonate, and 0.1 g of silver oxide were added to water, and oxygen was continuously bubbled through at 0.1 MPa. After reacting at 80 °C for 4 h, FDCA was obtained. After the reaction was completed, samples were taken for analysis, and the results are shown in Table 4.

[0109] Table 4 Effect of different extractants

[0110] Extractant HMF conversion rate (%) DFF yield (%) DFF extraction rate (%) FDCA yield (%) Ethyl acetate 100.00 92.46 79.65 67.96 Methyl isobutyl ketone 100.00 92.46 85.64 76.02 Diethyl ether 100.00 92.46 65.18 57.85 n-Butanol 100.00 92.46 68.54 60.84

[0111] Example 5

[0112] The procedure was carried out in accordance with Example 4, except that the volume ratio of the extractant to the reaction mixture in Example 4 was changed from 1:1 to 4:1. Samples were taken and tested, and the HMF conversion rate, intermediate product yield, intermediate product extraction rate and FDCA yield were measured. The results are shown in Table 5.

[0113] Table 5 Effect of different extractant dosages

[0114] Extractant HMF conversion rate (%) DFF yield (%) DFF extraction rate (%) FDCA yield (%) Ethyl acetate 100.00 92.46 85.64 76.02 Methyl isobutyl ketone 100.00 92.46 92.85 82.42 Diethyl ether 100.00 92.46 93.37 82.88 n-Butanol 100.00 92.46 95.86 85.09

[0115] Example 6

[0116] 3 mmol of 5-hydroxymethylfurfural (HMF) was dissolved in 50 ml of water, and 18 mmol of vanadium oxysulfate and 80 mmol of sulfuric acid were added to react. After reacting at room temperature for 12 h, a reaction mixture was obtained. The mixture was extracted to obtain an intermediate product. 1 mmol of the intermediate product and 2 mmol of sodium bicarbonate were dissolved in 40 ml of water, and 0.1 g of silver oxide was added. Oxygen was continuously bubbled through the mixture at 0.1 MPa, and the reaction was carried out at 80 °C for 3 h. Samples were taken for analysis, and the conversion rate of 5-hydroxymethylfurfural was calculated to be 100%, the yield of the intermediate product was 92.51%, and the yield of FDCA was 84.18%.

[0117] Example 7

[0118] 3 mmol of 5-hydroxymethylfurfural (HMF) was dissolved in 50 ml of water, and 18 mmol of vanadium oxysulfate and 80 mmol of sulfuric acid were added to react. After reacting at room temperature for 12 h, a reaction mixture was obtained. The mixture was then extracted to obtain the intermediate product. 2 mmol of sodium bicarbonate was dissolved in 20 ml of water, and 0.1 g of silver oxide was added. 1 mmol of the intermediate product was dissolved in 20 ml of methyl isobutyl ketone. The two solutions were mixed, and oxygen was continuously bubbled through them. The reaction was carried out at 80 °C for 3 h, and samples were taken for analysis. The conversion rate of 5-hydroxymethylfurfural was calculated to be 100%, the yield of the intermediate product was 92.51%, and the yield of FDCA was 89.73%.

[0119] Example 8

[0120] Example 8 was carried out in the same manner as Example 7, except that 2 mmol of sodium bicarbonate in Example 7 was replaced with 2 mmol of potassium bicarbonate. The conversion rate of 5-hydroxymethylfurfural was 100%, the yield of intermediate product was 92.51%, and the yield of FDCA was 90.13%.

[0121] Example 9

[0122] This invention is used to illustrate the method for producing FDCA by HMF oxidation.

[0123] Reference Appendix Figure 212 mmol HMF and 36 mmol vanadium oxysulfate were dissolved in 100 ml of water, and 160 mmol sulfuric acid was added simultaneously. The mixture was reacted in the first-step oxidation reactor 1 at 60 °C for 8 h to obtain a reaction solution. The reaction solution was then extracted in extraction tower 2 using methyl isobutyl ketone as the extractant, with a volume ratio of extractant to reaction solution of 1:1, yielding an extract phase and a raffinate phase. The extracted phase was added to evaporator 3 for vacuum evaporation and low-temperature crystallization to recover the extractant and obtain the intermediate product 2,5-dicarboxyfuran. The raffinate phase was added to regeneration reactor 4 and regenerated at 100 °C using oxygen as the oxidant. In the second-step oxidation reactor 5, the obtained intermediate product 2,5-dicarboxyfuran was dissolved in 200 ml of methyl isobutyl ketone, and 24 mmol sodium bicarbonate was dissolved in 200 ml of water. The two solutions were mixed, and 1 g of silver oxide was added. Oxygen was continuously introduced, and the mixture was reacted at 80 °C for 4 h. The solid catalyst and a filtrate containing 2,5-furandicarboxylate were obtained by filtration in the separation and purification unit 6. Sulfuric acid was added to the filtrate to make the solution acidic, and FDCA precipitated out. The solution was filtered to obtain crude FDCA. The crude FDCA was dissolved in boiling water and filtered while hot to obtain an FDCA solution. After cooling and crystallization, the FDCA product was obtained. This process was repeated three times to obtain the purified FDCA product. In this process, the yield of the intermediate product 2,5-dicarboxyfuran in the first oxidation reaction was 92%, the extraction rate of the intermediate product 2,5-dicarboxyfuran was 99.93%, the total yield of FDCA after the second oxidation reaction was 89%, and the purity of the purified FDCA product was 99.91%. The above results show that the method provided by the present invention can produce FDCA using HMF as a raw material under mild conditions and is easy to scale up.

[0124] Comparative Example 1

[0125] 2 mmol of 5-hydroxymethylfurfural and 4 mmol of sodium bicarbonate were dissolved in 40 ml of water, 0.1 g of silver oxide was added, and oxygen was continuously introduced at 0.1 MPa. After reacting at 80 °C for 4 h, samples were taken for testing. The conversion rate of 5-hydroxymethylfurfural was calculated to be 100%, and the yield of FDCA was 1.32%.

[0126] As can be seen from the above embodiments and comparative examples, the method for preparing FDCA by HMF oxidation according to the present invention can achieve the preparation of FDCA by HMF oxidation under mild conditions, and has a high HMF conversion rate and FDCA yield.

[0127] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0128] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A process for the production of 2,5-furandicarboxylic acid by oxidation of 5-hydroxymethylfurfural, characterized in that, Comprising: (1) mixing 5-hydroxymethylfurfural, a first solvent, a first oxidizing agent, and an inorganic acid to perform an oxidation reaction to obtain an intermediate product 2,5-diformylfuran; the first oxidizing agent comprises at least one of ferric chloride, ferric nitrate, vanadyl sulfate, ferric citrate, nitric acid, ferric phosphate, copper chloride, copper nitrate, cerium nitrate, and sodium metavanadate; (2) mixing the intermediate product 2,5-diformylfuran, a second solvent, an inorganic base, a catalyst, and a second oxidizing agent to perform an oxidation reaction to obtain 2,5-furan dicarboxylic acid; the second oxidizing agent comprises at least one of hydrogen peroxide, air, and oxygen; and the catalyst is silver oxide.

2. The method according to claim 1, wherein: in step (1), the first oxidizing agent is regenerated by extraction and regeneration treatment.

3. The method of claim 1, wherein, in step (1), the concentration of the first oxidizing agent is 0.01 mol / L-3 mol / L.

4. The method of claim 1, wherein, the first solvent and the second solvent each independently comprises at least one of dimethyl sulfoxide, N,N-dimethylformamide, acetonitrile, methyl isobutyl ketone, water, isopropyl alcohol, toluene, and acetic acid.

5. The method of claim 4, wherein, the first solvent and the second solvent each independently is water, and / or methyl isobutyl ketone.

6. The method of claim 1, wherein, in step (1), the concentration of the 5-hydroxymethylfurfural is 0.1 mol / L-1 mol / L.

7. The method of claim 1, wherein, in step (1), the molar ratio of the 5-hydroxymethylfurfural to the first oxidizing agent is 1-9:1-9.

8. The method of claim 1, wherein, in step (1), the intermediate product 2,5-diformylfuran is obtained by extraction and distillation.

9. The method of claim 1, wherein, the extractant used for the extraction of the intermediate product 2,5-diformylfuran comprises at least one of ethyl acetate, methyl isobutyl ketone, diethyl ether, and n-butanol.

10. The method of claim 9, wherein, the extractant used for the extraction of the intermediate product 2,5-diformylfuran is methyl isobutyl ketone.

11. The method of claim 1, wherein, in the extraction treatment of the intermediate product 2,5-diformylfuran, the volume ratio of the reaction mixture to the extractant is 1-9:1-9.

12. The method of claim 1, wherein, the second oxidizing agent is air or oxygen, and the reaction pressure is 0.1 Mpa-2 Mpa.

13. The method of claim 1, wherein, in step (2), the inorganic base comprises at least one of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, and potassium bicarbonate.

14. The method of claim 13, wherein, the inorganic base is at least one of sodium carbonate, potassium carbonate, sodium bicarbonate, and potassium bicarbonate.

15. The method of claim 1, wherein, in step (2), the concentration of the inorganic base is 0.001 mol / L-6 mol / L.

16. The method of claim 15, wherein, in step (2), the concentration of the inorganic base is 0.01 mol / L-4 mol / L.

17. The method of claim 1, wherein, in step (1), the conditions of the oxidation reaction comprise a reaction temperature of 20℃-100℃, and / or a reaction time of 1h-12h.

18. The method of claim 1, wherein, in step (1), the conditions of the oxidation reaction comprise a reaction temperature of 40℃-60℃, and / or a reaction time of 4h-8h.

19. The method of claim 1, wherein, in step (2), the conditions of the oxidation reaction comprise a reaction temperature of 20℃-100℃, and / or a reaction time of 1h-12h.

20. The method of claim 1, wherein, In step (2), the conditions of the oxidation reaction include: the reaction temperature is 70-80 °C; and / or, the reaction time is 2-4 h. In step (2), the conditions of the oxidation reaction include: the reaction temperature is 70-80 °C; and / or, the reaction time is 2-4 h.

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