Preparation method of 2, 5-furandicarboxylic acid

Abstract

The invention discloses a preparation method of 2, 5-furandicarboxylic acid, and belongs to the technical field of chemical engineering. The invention relates to a preparation method of 2, 5-furandicarboxylic acid, which comprises the following steps: contacting a material containing 5-hydroxymethylfurfural with a catalyst and an oxygen source in a solvent for catalytic oxidation, and reacting at 80-100 DEG C for 2-6 hours to obtain 2, 5-furandicarboxylic acid, the catalyst is Pd / sulfur doped magnetic metal organic framework-PDA (Personal Digital Assistant). The sulfur-doped magnetic metal organic framework-PDA is used as a Pd carrier, a sulfur element and a nitrogen element are used as main active sites for anchoring palladium, and the adhesion of polydopamine enables palladium to be uniformly dispersed in the sulfur-doped magnetic metal organic framework-PDA, so that the catalytic activity of the catalyst is improved. And the magnetic catalyst is easy to recover, so that the economical efficiency of the catalyst is improved.

Description

Technical Field

[0001] The present invention relates to the chemical industry field, and particularly relates to a preparation method of 2,5-furandicarboxylic acid. Background Art

[0002] Due to the shortage of traditional petrochemical resources and the increasingly serious environmental problems, people have turned their attention to biomass materials that can be used to synthesize chemical raw materials. As an important dicarboxylic acid derived from biomass, 2,5-furandicarboxylic acid (FDCA) can be catalytically ring-opened to produce adipic acid, and adipic acid is an essential monomer of nylon 66. 2,5-Furandicarboxylic acid can also be polymerized with ethylene glycol, etc., and is applied to polyesters, polyurethanes, etc., and is expected to become a new bio-based material to replace terephthalic acid from existing petroleum sources.

[0003] The existing patent-reported preparation methods of 2,5-furandicarboxylic acid mainly include biological fermentation method, electrochemical method, chemical catalysis method, etc., among which the chemical catalysis method is the most efficient and has been studied the most. Patent CN111039906B provides a preparation method of 2,5-furandicarboxylic acid. In this patent, 5-hydroxymethylfurfural and a catalyst are placed in a mixed solution of water and an organic solvent, and a catalytic oxidation reaction is carried out to obtain the 2,5-furandicarboxylic acid; the catalyst includes a carrier and an active component supported on the carrier, and the component is selected from metals such as ruthenium, palladium, platinum, and rhodium; the carrier is selected from activated carbon, graphite, fullerene, graphene oxide, etc. The operation method of this patent is simple and the reaction conditions are mild, but the catalyst after the reaction is difficult to recycle, increasing the production cost and reducing the resource utilization efficiency. Summary of the Invention

[0004] The present invention provides a preparation method of 2,5-furandicarboxylic acid, which can solve the problems in the prior art that the catalyst is difficult to recycle, increasing the production cost and reducing the resource utilization efficiency.

[0005] The object of the present invention can be achieved by the following technical solutions:

[0006] A preparation method of 2,5-furandicarboxylic acid, comprising the following steps:

[0007] A material containing 5-hydroxymethylfurfural is contacted with a catalyst and an oxygen source in a solvent for catalytic oxidation, and the reaction is carried out at 80-100 °C for 2-6 h to obtain 2,5-furandicarboxylic acid; the catalyst is Pd / sulfur-doped magnetic metal-organic framework-PDA.

[0008] Further, the mass ratio of the material containing 5-hydroxymethylfurfural, the solvent, and the catalyst is 1:(30-50):(0.4-0.8).

[0009] Further, the oxygen source is air or oxygen.

[0010] Furthermore, the pressure for catalytic oxidation is 2 to 6 MPa.

[0011] Furthermore, the solvent is one or a mixture of more than one of deionized water, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, N-methylpyrrolidone, and tetrahydrofuran.

[0012] Furthermore, if the solvent is deionized water, the pH of the solution is 7 to 8.

[0013] Furthermore, the preparation method of the catalyst is as follows:

[0014] A1. Preparation of sulfur-doped iron-based metal-organic framework: Add ferric chloride hexahydrate, terephthalic acid, and p-mercaptobenzoic acid to DMF, ultrasonicate for 15 - 30 min, then transfer to a reaction kettle, heat at 200 °C for 12 - 16 h, cool and then centrifuge, and dry the precipitate under vacuum at 80 °C for 8 - 10 h to obtain the sulfur-doped iron-based metal-organic framework;

[0015] Among them, the dosage ratio of ferric chloride hexahydrate, terephthalic acid, p-mercaptobenzoic acid, and DMF is 1.23 g : 4.05 g : 5.54 - 6.63 g : 90 mL.

[0016] In the above steps, iron ions are used as the metal center, and terephthalic acid and p-mercaptobenzoic acid are used as organic ligands. Using the solvothermal method, a sulfur-doped iron-based metal-organic framework is prepared. MOFs materials have an extremely high specific surface area, and this high specific surface area provides a large number of active sites, enabling the catalyst to come into contact with the reactants more fully, thereby improving the catalytic efficiency. Moreover, there are a large number of micropores and mesoporous structures inside the MOFs materials. These pores not only increase the specific surface area of the material but also contribute to the diffusion and transmission of the reactants, further improving the catalytic performance.

[0017] A2. Preparation of sulfur-doped magnetic metal-organic framework: Heat the sulfur-doped iron-based metal-organic framework in a nitrogen-filled tubular furnace at a rate of 4 - 5 °C / min to 700 - 750 °C, then keep it calcined at 700 - 750 °C for 6 - 8 h. After cooling to room temperature, take out the product, wash it 3 - 5 times with anhydrous ethanol and deionized water respectively, separate it with an external magnet and dry it to obtain the sulfur-doped magnetic metal-organic framework;

[0018] During the calcination process of the sulfur-doped iron-based metal-organic framework, it will transform into a carbon material with certain magnetism, and then the sulfur-doped magnetic metal-organic framework is obtained. The magnetic properties of the MOF make the catalyst easy to separate and recycle from the reaction system, improving the economy and sustainability of the catalyst.

[0019] A3. Preparation of the catalyst: Add sulfur-doped magnetic metal-organic framework into DMF and stir for 2 - 3 h to obtain a mixed solution; sequentially add dopamine hydrochloride, palladium nitrate dihydrate aqueous solution, Tris-HCl buffer solution with pH = 8.5, and deionized water into the mixed solution, ultrasonically stir for 20 - 24 h, perform suction filtration, vacuum dry at 60 - 70 °C for 12 - 14 h, and then reduce in a nitrogen atmosphere at 180 - 200 °C for 1 - 1.5 h with the nitrogen flow rate of 20 - 25 mL / min to obtain the catalyst.

[0020] Among them, the dosage ratio of the sulfur-doped magnetic metal-organic framework, DMF, dopamine hydrochloride, palladium nitrate dihydrate aqueous solution, Tris-HCl buffer solution, and deionized water is 1 g : 40 mL : 1 - 2 g : 1.2 mL : 200 mL : 50 mL; the mass fraction of the palladium nitrate dihydrate aqueous solution is 8 - 15 wt%.

[0021] The above steps mainly obtain the catalyst through one-pot hydrothermal synthesis using polydopamine as a reducing agent. The sulfur-doped magnetic metal-organic framework contains sulfur elements, and dopamine hydrochloride contains nitrogen elements. The sulfur elements and nitrogen elements can serve as the main active sites for anchoring palladium, enabling palladium to be uniformly dispersed in the sulfur-doped magnetic metal-organic framework - PDA, thereby improving the catalytic activity of the catalyst.

[0022] Advantages of the present invention:

[0023] 1. The present invention uses Pd / sulfur-doped magnetic metal-organic framework - PDA as a catalyst to catalyze the oxidation of 5-hydroxymethylfurfural to produce 2,5-furandicarboxylic acid; the sulfur-doped magnetic metal-organic framework material has an extremely high specific surface area, and this high specific surface area provides a large number of active sites, enabling the catalyst to come into contact with the reactants more fully, thereby improving the catalytic efficiency. Moreover, there are a large number of micropores and mesoporous structures inside the sulfur-doped magnetic metal-organic framework material. These pores not only increase the specific surface area of the material but also contribute to the diffusion and transport of the reactants, further improving the catalytic performance; as a carrier of Pd, the sulfur-doped magnetic metal-organic framework - PDA, with sulfur elements and nitrogen elements as the main active sites for anchoring palladium and the adhesiveness of polydopamine, can make palladium uniformly dispersed in the sulfur-doped magnetic metal-organic framework - PDA, improving the catalytic activity of the catalyst.

[0024] 2. The catalyst used in the present invention not only has excellent catalytic performance but also is easy to recycle, improving the economy of the catalyst and reducing the loss of the catalyst, thereby improving the overall catalytic efficiency. Specific embodiments

[0025] The following details the specific embodiments of the present invention, but it should be understood that the protection scope of the present invention is not limited by the specific embodiments.

[0026] Example 1

[0027] This example provides a method for preparing 2,5-furandicarboxylic acid, which includes the following steps:

[0028] Weigh 1 g of the material containing 5-hydroxymethylfurfural, 0.4 g of the catalyst, and 30 mL of deionized water. Add sodium hydroxide alkaline solution to make the pH of the solution 7 - 8. Seal the reaction kettle, turn on the stirrer. After three times of oxidation replacement, start heating up, and make the oxygen react at a constant pressure of 2 MPa and 80 °C for 2 h to obtain 2,5-furandicarboxylic acid.

[0029] The preparation method of the catalyst is as follows:

[0030] A1. Prepare sulfur-doped iron-based metal-organic framework: Add 1.23 g of ferric chloride hexahydrate, 4.05 g of terephthalic acid, and 5.54 g of p-mercaptobenzoic acid to 90 mL of DMF. After ultrasonic treatment for 15 min, transfer it to a reaction kettle and heat it at 200 °C for 12 h. After cooling, centrifuge and separate, and dry the precipitate in vacuum at 80 °C for 8 h to obtain sulfur-doped iron-based metal-organic framework;

[0031] A2. Prepare sulfur-doped magnetic metal-organic framework: Heat the sulfur-doped iron-based metal-organic framework in a nitrogen-filled tubular furnace at a rate of 4 °C / min to 700 °C, then keep it calcined at 700 °C for 6 h. After cooling to room temperature, take out the product, wash it 3 times with anhydrous ethanol and deionized water respectively, separate it with an external magnet and dry it to obtain sulfur-doped magnetic metal-organic framework;

[0032] A3. Prepare the catalyst: Add 1 g of sulfur-doped magnetic metal-organic framework to 40 mL of DMF and stir for 2 h to obtain a mixed solution; add 1 g of dopamine hydrochloride, 1.2 mL of an aqueous solution of palladium nitrate dihydrate with a mass fraction of 8 wt%, 200 mL of Tris-HCl buffer solution with pH = 8.5, and 50 mL of deionized water to the mixed solution in sequence, stir ultrasonically for 20 h, filter by suction, dry it in vacuum at 60 °C for 12 h, and then reduce it in a nitrogen atmosphere at 180 °C for 1 h with a nitrogen flow rate of 20 mL / min to obtain the catalyst.

[0033] Example 2

[0034] This example provides a method for preparing 2,5-furandicarboxylic acid, which includes the following steps:

[0035] Weigh 1 g of the material containing 5-hydroxymethylfurfural, 0.5 g of the catalyst, and 40 mL of deionized water. Add sodium hydroxide alkaline solution to make the pH of the solution 7 - 8. Seal the reaction kettle, turn on the stirrer. After three times of oxidation replacement, start heating up, and make the oxygen react at a constant pressure of 4 MPa and 90 °C for 4 h to obtain 2,5-furandicarboxylic acid.

[0036] The preparation method of the catalyst is as follows:

[0037] A1. Preparation of sulfur-doped iron-based metal-organic framework: Add 1.23 g of ferric chloride hexahydrate, 4.05 g of terephthalic acid, and 6.63 g of thiol terephthalic acid into 90 mL of DMF. After ultrasonic treatment for 25 min, transfer it to a reaction kettle and heat it at 200 °C for 14 h. After cooling, perform centrifugal separation, and vacuum-dry the precipitate at 80 °C for 9 h to obtain the sulfur-doped iron-based metal-organic framework;

[0038] A2. Preparation of sulfur-doped magnetic metal-organic framework: Heat the sulfur-doped iron-based metal-organic framework in a nitrogen-filled tube furnace at a rate of 5 °C / min to 750 °C, then keep it calcined at 750 °C for 7 h. After cooling to room temperature, take out the product, wash it 4 times with absolute ethanol and deionized water respectively, separate it with an external magnet and dry it to obtain the sulfur-doped magnetic metal-organic framework;

[0039] A3. Preparation of the catalyst: Add 1 g of the sulfur-doped magnetic metal-organic framework into 40 mL of DMF and stir for 3 h to obtain a mixed solution; sequentially add 1.5 g of hydrochloric acid dopamine, 1.2 mL of an aqueous solution of palladium nitrate dihydrate with a mass fraction of 12 wt%, 200 mL of Tris-HCl buffer solution with pH = 8.5, and 50 mL of deionized water into the mixed solution, perform ultrasonic stirring for 24 h, perform suction filtration, vacuum-dry at 60 °C for 14 h, and then reduce it in a nitrogen atmosphere at 200 °C for 1.5 h with a nitrogen flow rate of 20 mL / min to obtain the catalyst.

[0040] Example 3

[0041] This example provides a preparation method of 2,5-furandicarboxylic acid, including the following steps:

[0042] Weigh 1 g of the material containing 5-hydroxymethylfurfural, 0.6 g of the catalyst, and 50 mL of deionized water, add sodium hydroxide alkaline solution to make the solution pH = 7 - 8, seal the reaction kettle, turn on the stirring, after three times of oxidation replacement, start to heat up, and make the oxygen react at a constant pressure of 6 MPa and 100 °C for 6 h to obtain 2,5-furandicarboxylic acid.

[0043] The preparation method of the catalyst is as follows:

[0044] A1. Preparation of sulfur-doped iron-based metal-organic framework: Add 1.23 g of ferric chloride hexahydrate, 4.05 g of terephthalic acid, and 6.63 g of thiol terephthalic acid into 90 mL of DMF. After ultrasonic treatment for 30 min, transfer it to a reaction kettle and heat it at 200 °C for 12 - 16 h. After cooling, perform centrifugal separation, and vacuum-dry the precipitate at 80 °C for 10 h to obtain the sulfur-doped iron-based metal-organic framework;

[0045] A2. Preparation of sulfur-doped magnetic metal-organic framework: Heat the sulfur-doped iron-based metal-organic framework in a nitrogen-filled tubular furnace at a rate of 5 °C / min to 750 °C, then maintain the calcination at 750 °C for 8 h. After cooling to room temperature, take out the product, wash it 5 times with anhydrous ethanol and deionized water respectively, separate it with an external magnet and dry it to obtain the sulfur-doped magnetic metal-organic framework;

[0046] A3. Preparation of catalyst: Add 1 g of sulfur-doped magnetic metal-organic framework to 40 mL of DMF and stir for 3 h to obtain a mixed solution; sequentially add 2 g of hydrochloric acid dopamine, 1.2 mL of an aqueous solution of palladium nitrate dihydrate with a mass fraction of 15 wt%, 200 mL of Tris-HCl buffer solution with pH = 8.5, and 50 mL of deionized water to the mixed solution, stir ultrasonically for 24 h, filter by suction, dry under vacuum at 70 °C for 14 h, and then reduce it in a nitrogen atmosphere at 200 °C for 1.5 h with a nitrogen flow rate of 25 mL / min to obtain the catalyst.

[0047] Example 4

[0048] The difference between this example and Example 3 is that:

[0049] The addition amount of the catalyst is 0.7 g, and the other raw materials and steps are the same as those in Example 3.

[0050] Example 5

[0051] The difference between this example and Example 3 is that:

[0052] The addition amount of the catalyst is 0.8 g, and the other raw materials and steps are the same as those in Example 3.

[0053] Comparative Example 1

[0054] The difference between this comparative example and Example 1 is that polydopamine is omitted, and the specific steps are as follows:

[0055] The preparation method of the catalyst is:

[0056] A1. Preparation of sulfur-doped iron-based metal-organic framework: Add 1.23 g of ferric chloride hexahydrate, 4.05 g of terephthalic acid, and 5.54 g of p-mercaptobenzoic acid to 90 mL of DMF, ultrasonicate for 15 min and then transfer to a reaction kettle, heat at 200 °C for 12 h, cool and centrifuge to separate, and dry the precipitate under vacuum at 80 °C for 8 h to obtain the sulfur-doped iron-based metal-organic framework;

[0057] A2. Preparation of sulfur-doped magnetic metal-organic framework: Heat the sulfur-doped iron-based metal-organic framework in a nitrogen-filled tube furnace at a rate of 5 °C / min to 750 °C, then maintain the calcination at 750 °C for 6 h. After cooling to room temperature, take out the product, wash it three times with anhydrous ethanol and deionized water respectively, separate it with an external magnet and dry it to obtain the sulfur-doped magnetic metal-organic framework;

[0058] A3. Preparation of catalyst: Add 1 g of sulfur-doped magnetic metal-organic framework into 40 mL of DMF and stir for 2 h to obtain a mixed solution; add 1.2 mL of an aqueous solution of palladium nitrate dihydrate with a mass fraction of 8 wt% into the mixed solution, ultrasonically stir for 24 h, filter by suction, vacuum dry at 60 °C for 12 h, then dropwise add 11.8 mL of 0.05 mol / L NaBH4 ethanol solution within 20 min, and continue to vigorously stir the suspension in an ice-water bath for 4 h. After the reaction, centrifuge to collect the solid powder, wash it with ethanol and vacuum dry at 70 °C to obtain the catalyst.

[0059] The remaining raw materials and steps are the same as those in Example 1.

[0060] Comparative Example 2

[0061] The difference between this comparative example and Example 1 is that polydopamine and p-mercaptobenzoic acid are omitted. The specific steps are as follows:

[0062] A1. Preparation of iron-based metal-organic framework: Add 1.23 g of ferric chloride hexahydrate and 4.05 g of terephthalic acid into 90 mL of DMF, ultrasonically stir for 15 min and then transfer it to a reaction kettle, heat it at 200 °C for 12 h, cool it and centrifuge to separate, and vacuum dry the precipitate at 80 °C for 8 h to obtain the iron-based metal-organic framework;

[0063] A2. Preparation of magnetic metal-organic framework: Heat the sulfur-doped iron-based metal-organic framework in a nitrogen-filled tube furnace at a rate of 5 °C / min to 750 °C, then maintain the calcination at 750 °C for 6 h. After cooling to room temperature, take out the product, wash it three times with anhydrous ethanol and deionized water respectively, separate it with an external magnet and dry it to obtain the magnetic metal-organic framework;

[0064] A3. Preparation of catalyst: Add 1 g of magnetic metal-organic framework into 40 mL of DMF and stir for 2 h to obtain a mixed solution; add 1.2 mL of an aqueous solution of palladium nitrate dihydrate with a mass fraction of 8 wt% into the mixed solution, ultrasonically stir for 24 h, filter by suction, vacuum dry at 60 °C for 12 h, then dropwise add 11.8 mL of 0.05 mol / L NaBH4 ethanol solution within 20 min, and continue to vigorously stir the suspension in an ice-water bath for 4 h. After the reaction, centrifuge to collect the solid powder, wash it with ethanol and vacuum dry at 70 °C to obtain the catalyst.

[0065] The remaining raw materials and steps are the same as those in Example 1.

[0066] Comparative Example 3

[0067] Compared with Example 1, the difference in this comparative example is that the addition amount of the catalyst is 0.3 g, and the remaining raw materials and steps are the same as those in Example 1.

[0068] Comparative Example 4

[0069] Compared with Example 5, the difference in this comparative example is that the addition amount of the catalyst is 0.9 g, and the remaining raw materials and steps are the same as those in Example 5.

[0070] Perform performance tests on Examples 1 - 5 and Comparative Examples 1 - 4. The test items are as follows:

[0071] I. Conversion rate and yield tests: Both 5 - hydroxymethylfurfural and 2,5 - furandicarboxylic acid are detected using Waters 2695 and 2489 liquid chromatographs, and external standard method is used for quantification. The calculation formula for the conversion rate of 5 - hydroxymethylfurfural is as follows: Conversion rate = (moles of 5 - hydroxymethylfurfural before reaction - moles of remaining 5 - hydroxymethylfurfural after reaction) / moles of 5 - hydroxymethylfurfural before reaction × 100%; The calculation formula for the yield of 2,5 - furandicarboxylic acid is as follows: Yield = moles of 2,5 - furandicarboxylic acid generated in the reaction / moles of 5 - hydroxymethylfurfural before reaction × 100%. The test results are shown in Table 1.

[0072] II. Recycling performance test: The catalyst used in Example 1 is recovered and collected using a magnet. After the recovered catalyst is repeatedly washed with water and ethanol for multiple times, it is reduced and calcined at 400 °C for regeneration to obtain the recovered catalyst. Test the conversion rate of 5 - hydroxymethylfurfural and the yield of 2,5 - furandicarboxylic acid after 1 - 5 cycles. The test items are shown in Table 2.

[0073] Table 1

[0074] Project Conversion rate / % Yield / % Example 1 98.8 91.5 Example 2 99.1 91.8 Example 3 99.3 92.3 Example 4 99.6 92.6 Example 5 99.7 92.7 Comparative Example 1 97.6 89.2 Comparative Example 2 90.5 81.4 Comparative Example 3 98.1 90.6 Comparative Example 4 99.4 92.5

[0075] As can be seen from Table 1, the catalytic efficiency of the catalysts in Examples 1 - 5 is significantly higher than that in Comparative Examples 1 - 4. In Comparative Example 1, no polydopamine is contained, and both the conversion rate and the yield are lower than those in Example 1, indicating that nitrogen elements can serve as the main active sites for anchoring palladium and the adhesiveness of polydopamine can evenly disperse palladium in sulfur-doped magnetic metal-organic framework-PDA, improving the catalytic activity of the catalyst. In Comparative Example 2, no sulfur element and nitrogen element are contained, and both the conversion rate and the yield are lower than those in Example 1, indicating that sulfur-doped magnetic metal-organic framework-PDA as the carrier of Pd, the sulfur element and nitrogen element therein can serve as the main active sites for anchoring palladium, making palladium evenly disperse in sulfur-doped magnetic metal-organic framework-PDA, improving the catalytic activity of the catalyst. The catalyst addition amounts in Comparative Examples 3 and 4 are respectively lower and higher than those in Example 1 and Example 5, and their catalytic efficiencies are respectively lower than those in Example 1 and Example 5, indicating that too much or too little catalyst addition amount is not conducive to improving the catalytic efficiency, and the catalyst addition amount of the present invention is the optimal amount.

[0076] Table 2

[0077] Number of cycles Conversion rate / % Yield / % 1 98.8 91.3 2 98.4 90.8 3 97.7 88.4 4 97.0 87.8 5 96.5 86.5

[0078] It can be concluded from Table 2 that the catalyst prepared by the present invention still has a high conversion rate and yield after being recycled five times and can be recycled.

[0079] The above-disclosed are only several specific embodiments of the present invention. However, the embodiments of the present invention are not limited thereto, and any changes that can be thought of by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. A method for preparing 2,5-furandicarboxylic acid, characterized in that, It includes the following steps: Contact the material containing 5-hydroxymethylfurfural with a catalyst and an oxygen source in a solvent for catalytic oxidation, react at 80-100 °C for 2-6 h to obtain 2,5-furandicarboxylic acid; the catalyst is Pd / sulfur-doped magnetic metal-organic framework-PDA.

2. The preparation method of 2,5-furandicarboxylic acid according to claim 1, characterized in that, The mass ratio of the material containing 5-hydroxymethylfurfural, the solvent, and the catalyst is 1:(30-50):(0.4-0.8).

3. The preparation method of 2,5-furandicarboxylic acid according to claim 1, characterized in that, The oxygen source is air or oxygen.

4. The preparation method of 2,5-furandicarboxylic acid according to claim 1, characterized in that, The pressure of the catalytic oxidation is 2-6 MPa.

5. The preparation method of 2,5-furandicarboxylic acid according to claim 1, characterized in that, The solvent is one or a mixture of deionized water, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, N-methylpyrrolidone, and tetrahydrofuran.

6. The preparation method of 2,5-furandicarboxylic acid according to claim 1, wherein If the solvent is deionized water, the pH of the solution is 7-8.

7. A method for preparing 2,5-furandicarboxylic acid according to claim 1, characterized in that, The preparation method of the catalyst is as follows: A1. Prepare sulfur-doped iron-based metal-organic framework: Add ferric chloride hexahydrate, terephthalic acid, and p-mercaptobenzoic acid to DMF, ultrasonicate for 15-30 min and then transfer to a reaction kettle, heat at 200 °C for 12-16 h, cool and then centrifuge to separate, and dry the precipitate under vacuum at 80 °C for 8-10 h to obtain sulfur-doped iron-based metal-organic framework; A2. Prepare sulfur-doped magnetic metal-organic framework: Heat the sulfur-doped iron-based metal-organic framework in a nitrogen-filled tube furnace at a rate of 4-5 °C / min to 700-750 °C, then keep it calcined at 700-750 °C for 6-8 h, take out the product after cooling to room temperature, wash it with absolute ethanol and deionized water 3-5 times respectively, separate with an external magnet and dry to obtain sulfur-doped magnetic metal-organic framework; A3. Prepare the catalyst: Add the sulfur-doped magnetic metal-organic framework to DMF and stir for 2-3 h to obtain a mixed solution; add hydrochloric acid dopamine, palladium nitrate dihydrate aqueous solution, Tris-HCl buffer solution with pH = 8.5, and deionized water to the mixed solution in sequence, ultrasonically stir for 20-24 h, filter by suction, dry under vacuum at 60-70 °C for 12-14 h, and then reduce it in a nitrogen atmosphere at 180-200 °C for 1-1.5 h, and the flow rate of nitrogen is 20-25 mL / min to obtain the catalyst.

8. A method for preparing 2,5-furandicarboxylic acid according to claim 7, characterized in that, In step A1, the dosage ratio of ferric chloride hexahydrate, terephthalic acid, p-mercaptobenzoic acid, and DMF is 1.23 g:4.05 g:5.54-6.63 g:90 mL.

9. A method for preparing 2,5-furandicarboxylic acid according to claim 7, characterized in that, In step A3, the dosage ratio of the sulfur-doped magnetic metal-organic framework, DMF, hydrochloric acid dopamine, palladium nitrate dihydrate aqueous solution, Tris-HCl buffer solution, and deionized water is 1 g:40 mL:1-2 g:1.2 mL:200 mL:50 mL.

10. A method for preparing 2,5-furandicarboxylic acid according to claim 7, characterized in that, In step A3, the mass fraction of the palladium nitrate dihydrate aqueous solution is 8-15 wt%.