Catalyst for catalytic synthesis of 2,5-furan dicarboxylic acid in an alkali-free system and preparation method and application thereof

Abstract

This invention provides a catalyst for the alkali-free catalytic synthesis of 2,5-furandicarboxylic acid, its preparation method, and its application. The catalyst is Mnx / Beta, wherein the molar ratio of Si / Mn (x) is 20-200. The prepared Mnx / Beta catalyst can be used to catalyze the efficient oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA). Under mild conditions without the addition of strong alkali, the conversion rate of the HMF feedstock can reach up to 100%, and the selectivity and yield of the FDCA product can reach over 99.3%. This method involves simple catalyst preparation and environmentally friendly reaction conditions, and has significant industrial application prospects.

Description

Technical Field

[0001] This invention belongs to the field of molecular sieve catalyst preparation technology, specifically relating to a catalyst for the catalytic synthesis of 2,5-furandicarboxylic acid in an alkali-free system, its preparation method and application, and especially to a highly efficient Mn-supported Beta molecular sieve catalyst (Mnx / Beta) for catalytic oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA), its preparation method and application. Background Technology

[0002] With the increasing scarcity of fossil fuels and severe environmental pollution, humanity's dependence on liquid fossil fuels is growing, leading to environmental problems and declining energy reserves, which have become major global challenges. Therefore, the urgent task is to find green and renewable resources to replace traditional fossil fuels. Biomass is an ideal alternative with abundant reserves and wide availability. Lignocellulose is an important component of biomass, and 5-hydroxymethylfurfural (HMF) is a crucial platform compound in the conversion of lignocellulose. Through catalytic oxidation of HMF, a series of derivatives with significant application prospects can be prepared. Among them, 2,5-furandicarboxylic acid (FDCA) is listed by the U.S. Department of Energy as one of the 12 most important biomass-derived compounds. It possesses a conjugated carbon ring and diacid structure similar to petroleum-based terephthalic acid (PTA), and has broad substitution prospects in biodegradable plastics (such as PEF polyester), pharmaceuticals, and fine chemicals.

[0003] Currently, research on the catalytic oxidation of HMF to FDCA mainly focuses on noble metal catalytic systems (such as Pt, Au, Ru, Pd, etc.) and transition metal systems. However, existing processes for the catalytic oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA) generally have several limitations. First, the reaction conditions are harsh and dependent on strong bases. Most existing technologies operate in strong alkaline environments, such as NaOH and Na2CO3, to promote the formation of alcohol, aldehyde, and carboxylate groups. However, the use of strong bases not only easily triggers side reactions but also generates large amounts of saline wastewater, which can corrode the reactor, increasing production costs and environmental pressure. Second, existing processes often use oxygen as the oxygen source at high pressures, increasing the risk of industrial scale-up of the reactor. Third, many reactions use expensive noble metal catalysts, which are easily poisoned and deactivated by intermediate products during the reaction. Finally, many catalytic systems require high temperatures to achieve high HMF conversion rates, which also exacerbates the high-temperature thermal decomposition or rapid degradation of the biological substrate.

[0004] Chinese patent CN118812467B discloses a method for preparing 2,5-furandicarboxylic acid using fructose as a raw material. Although this method improves production efficiency, it requires a high amount of hydrogen bromide, which can easily cause severe corrosion to the production equipment.

[0005] Chinese patent CN118894822A discloses a method for preparing 2,5-furandicarboxylic acid by oxidizing 5-hydroxymethylfurfural. Although the conversion rate is improved, the process is cumbersome, requires a large amount of sulfuric acid and continuous oxygen supply, which poses a significant challenge to the reactor and subsequent separation.

[0006] Chinese patent CN113952951A discloses a Rh-intercalated ZnAl hydrotalcite catalyst. The disclosed actual reaction showed an HMF conversion rate of only 56.5% and an FDCA selectivity of 60.0%. Furthermore, it uses DMF as a solvent, which is not only detrimental to product recovery but also poses a certain toxicity risk to operators.

[0007] Chinese patent CN118679152A discloses a method for oxidizing hydroxymethylfurfural. This method requires the addition of a large amount of strong alkali during the reaction process, which not only increases the difficulty of subsequent separation and purification, but also hinders the extension of the service life of production equipment.

[0008] In summary, current oxidation catalysts reported in the literature or patents are characterized by cumbersome preparation steps, environmental unfriendliness, or the need for strong base assistance under oxidation reaction conditions, and generally low conversion rates and selectivity. Therefore, developing a heterogeneous catalyst with a simple preparation method, requiring no harsh strong base conditions, being environmentally friendly, and capable of achieving high HMF conversion and high FDCA selectivity is a key technical challenge that urgently needs to be solved in this field.

[0009] In recent years, molecular sieves have demonstrated significant advantages in heterogeneous catalysis due to their unique pore structure, high specific surface area, and tunable active sites (such as framework metals and acid-base centers). Furthermore, for the oxidation of 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid, using organic peroxides (such as tert-butylhydrogen peroxide and TBHP) as oxygen donors can provide highly efficient active oxygen species under mild pressure and in alkali-free systems, avoiding the rate-limiting problem of gas diffusion. Summary of the Invention

[0010] The technical problem to be solved: Addressing the current problems in the oxidation of HMF to FDCA, such as complex and expensive catalyst preparation, harsh reaction conditions (requiring strong bases, etc.), easy corrosion of equipment, and low selectivity of the target product, this invention provides a method for preparing a catalyst for the alkali-free catalytic synthesis of 2,5-furandicarboxylic acid and its application. This method employs a simple impregnation process, does not introduce environmentally unfriendly substances, and provides mild conditions in the subsequent HMF catalytic oxidation reaction, eliminating the need for additional strong bases. This achieves high conversion and high selectivity, laying the foundation for subsequent product separation.

[0011] Technical solution: A catalyst for the alkali-free synthesis of 2,5-furandicarboxylic acid, wherein the catalyst is a Mn-supported molecular sieve catalyst Mnx / Beta, and x ranges from 20 to 200 based on the Si / Mn molar ratio.

[0012] Preferably, the method for preparing the catalyst for the alkali-free system catalytic synthesis of 2,5-furandicarboxylic acid includes the following steps: S1. The silica-alumina type Beta molecular sieve is acid-treated, washed, and dried to obtain a deeply dealuminized Beta molecular sieve; S2. Mix the deeply dealuded Beta molecular sieve obtained in S1 with the Mn-based compound, and add deionized water to mix and stir. S3. The mixture obtained after stirring in S2 is subjected to rotary evaporation to remove the water introduced by impregnation; S4. The sample obtained in S3 is placed in an oven for drying to obtain the Mnx / Beta catalyst.

[0013] Preferably, the acid treatment in S1 is performed 1 to 3 times; and / or, The reagent used for acid treatment as described in S1 is one or more of concentrated hydrochloric acid, concentrated sulfuric acid, or concentrated nitric acid; and / or, The concentration of the reagent used for acid treatment as described in S1 is 6–11 mol / L; and / or, The mass ratio of the silica-alumina type Beta molecular sieve described in S1 to the reagent used for acid treatment is 1:30-50; The acid treatment in S1 is performed at a temperature of 80-140℃ for 8-24 hours; the drying temperature is 60-100℃ for 8-12 hours.

[0014] Preferably, the Mn-based compound in S2 is one or more of manganese nitrate trihydrate or manganese chloride; the molar ratio of SiO2 to the Mn-based compound in the deeply dealuded Beta molecular sieve is 1:0.005 to 0.05. Preferably, the amount of deionized water added in step S2 is 30-50 times the mass of the molecular sieve; the mixing and stirring time is 3-8 hours. Preferably, the temperature of rotary evaporation in S3 is 35-65°C, the time is 20-50 min, and the rotation speed is 35-65 rpm; Preferably, the drying temperature in step S4 is 60–100°C, and the drying time is 8–24 hours. Preferably, the Mnx / Beta catalyst is used in the catalytic oxidation of 5-hydroxymethylfurfural to prepare 2,5-furandicarboxylic acid.

[0015] Preferably, the method for preparing the Mnx / Beta catalyst in the catalytic oxidation of 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid includes the following steps: S11. Mix Mnx / Beta catalyst, 5-hydroxymethylfurfural, tert-butyl hydrogen peroxide and solvent and stir until homogeneous. Place the mixture in a sealed reaction vessel and carry out the oxidation reaction under self-pressure conditions. S12. After the oxidation reaction is complete, the reaction system is cooled to room temperature to obtain a crude reaction solution; S13. Perform solid-liquid separation on the crude reaction liquid to remove the Mnx / Beta catalyst solid and collect the filtrate; S14. The filtrate is concentrated, recrystallized, and dried to obtain pure 2,5-furandicarboxylic acid.

[0016] Preferably, in step S11, the Mnx / Beta catalyst is 30-90 mg, 5-hydroxymethylfurfural is 0.1-1 mmol, tert-butyl hydroperoxide is 2-14 mmol, and the solvent is 4-6 mL; the solvent is ethyl acetate; and / or, the stirring speed is 600-750 rpm; the reaction temperature is 30-90 °C, and the time is 2-12 h.

[0017] Beneficial effects: Compared with the prior art, the present invention has the following significant beneficial effects: 1. Simple and environmentally friendly preparation process: This invention uses a simple impregnation and loading method to prepare molecular sieve catalysts. The entire process does not require harsh conditions such as high temperature and high pressure, and effectively avoids the introduction of toxic and environmentally unfriendly substances. 2. Mild oxidation reaction conditions and avoidance of equipment corrosion: When the prepared catalyst is applied to the HMF oxidation to FDCA reaction, a green solvent and oxidant (hydrogen peroxide tert-butanol) are used. The system does not require the addition of strong bases or corrosive strong acids (such as hydrogen bromide), which greatly protects the production equipment and reduces the difficulty of separation and purification. 3. Extremely high catalytic activity and selectivity: By precisely loading Mn into a deeply dealulated Beta molecular sieve, the abundant silanol groups in the molecular sieve are utilized to react with Mn. 2+The chemical interactions between the two produce highly dispersed isolated Si-O-Mn species, which efficiently activate the tert-butyl peroxide oxidant via electron transfer. The released highly reactive oxygen species (superoxide radicals and hydroxyl radicals) act on the reaction substrate HMF. Furthermore, the reaction is carried out under mild, alkali-free conditions, which inhibits side reactions such as polymerization of reactants or intermediates. This results in high conversion and high selectivity of HMF to FDCA. Under optimal conditions, the HMF conversion can reach up to 100%, and the selectivity and yield of FDCA can reach over 99.3%. 4. Excellent cycle stability: The supported catalyst of this invention is easy to recover by centrifugation and retains excellent catalytic activity after multiple cycles, which significantly reduces the potential cost of industrial applications. Attached Figure Description

[0018] Figure 1 The X-ray diffraction (XRD) pattern of the Mn50 / Beta molecular sieve catalyst prepared in Example 1 of this invention; Figure 2 The image shows the Mn 2p X-ray photoelectron spectroscopy (XPS) spectrum of the Mn50 / Beta molecular sieve catalyst prepared in Example 1 of this invention. Figure 3 The image shows an electron microscope (SEM) image of the Mn50 / Beta molecular sieve catalyst prepared in Example 1 of this invention. Figure 4 The N2 adsorption-desorption isotherm and pore size distribution diagram are shown for the Mn50 / Beta molecular sieve catalyst prepared in Example 1 of this invention. Detailed Implementation

[0019] The specific embodiments of the present invention will be further described in detail below with reference to the examples. The detailed description of the following examples is only used to illustrate the technical solutions of the present invention and is not intended to limit the scope of protection of the present invention. That is, the present invention is not limited to the specific embodiments described in the examples, and covers any modifications, substitutions and improvements to the raw materials and means without departing from the spirit of the present invention.

[0020] It should be noted that, unless otherwise specified, the embodiments and features described in the embodiments of the present invention can be combined with each other. The raw materials and equipment used in the following embodiments and experimental examples are all commercially available products. The silicon-aluminum type Beta molecular sieve was purchased from Tianjin Nanhua Catalyst Co., Ltd., and the molar ratio of SiO2 / Al2O3 was approximately 25.

[0021] Example 1 In this example, the Mn-supported molecular sieve catalyst is Mnx / Beta, and the Si / Mn molar ratio x is 50. The preparation method of the supported Mn-based molecular sieve catalyst in this example includes the following steps: S1. Weigh 5g of silica-alumina type Beta molecular sieve into a 250mL round-bottom flask, add 150g of commercially available 6mol / L concentrated nitric acid for acid washing, place the round-bottom flask in an oil bath, adjust the temperature to 130℃, and then treat the Beta molecular sieve in concentrated nitric acid for 12h. This process is repeated twice. After reflux, cool to room temperature, filter, dry at 80℃ for 8h, and finally calcine at 550℃ for 6h in a muffle furnace to obtain a deeply dealuminized Beta molecular sieve, named Beta-DA. S2. Weigh 0.08g of the Beta-DA molecular sieve prepared in S1, place it in a 25mL round-bottom flask, then add manganese nitrate trihydrate and mix, and add deionized water at a mass ratio of 30 times that of the Beta-DA molecular sieve and stir for 3-8h. S3. After stirring in step S2, remove moisture by rotary evaporation at 45℃, and then dry in an oven at 80℃ for 8 hours to obtain Mn50 / Beta molecular sieve.

[0022] The XRD pattern, XPS pattern, SEM image, N2 adsorption-desorption isotherm curve, and pore size distribution of the Mn50 / Beta molecular sieve catalyst prepared in this embodiment are shown in the figures below. Figure 1 , Figure 2 , Figure 3 and Figure 4 As shown in Table 1.

[0023] Table 1. Pore Information for Mn50 / Beta Mn50 / Beta 443 0.41 0.16 0.25

[0024] from Figure 1 It can be seen that the prepared molecular sieve exhibits a distinct Beta topology and high crystallinity, indicating that the acid treatment and loading processes did not disrupt the molecular sieve framework structure. Furthermore, no Mn-related diffraction peaks were observed; since the catalyst did not undergo a high-temperature calcination step during preparation, Mn mainly exists in the molecular sieve in an ionic state. Figure 2 Mn 2p XPS analysis revealed that the Mn50 / Beta samples primarily exhibited Mn-attributable characteristics at 642.5 eV and 654.1 eV. 2+ 2p 3 / 2 and 2p 1 / 2 Photoelectrons; the above results indicate that Mn species are mainly Mn 2+ The form is highly dispersed in the molecular sieve support; from Figure 3 It can be seen that the Mn50 / Beta molecular sieve catalyst exhibits irregular particle shape, with a particle size distribution in the range of 50-150 nm; from Figure 4It can be seen that Mn50 / Beta exhibits a typical type I isotherm and an H4 type hysteresis loop, and simultaneously possesses micropores and mesopores, with the mesopores originating from the accumulation between nanoparticles; Table 1 shows that the specific surface area of ​​Mn50 / Beta is 443 mg. 3 g -1 The micropore volume is 0.16 cm³. 3 g -1 The mesopore volume is 0.25 mg. 3 g -1 .

[0025] Example 2 This embodiment tests the application of the Mn50 / Beta molecular sieve catalyst prepared in Example 1 in the efficient catalytic oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA). The specific reaction procedure was as follows: 5 mL of ethyl acetate as solvent, 6 mmol of tert-butanol peroxide (as oxidant), 0.0252 g of 5-hydroxymethylfurfural (HMF), and 70 mg of the Mn50 / Beta catalyst prepared in Example 1 were added to a 25 mL round-bottom flask. After the mixture was thoroughly mixed, it was placed in an oil bath and reacted at 80 °C with a stirring speed of 600 rpm for 6 h. After the reaction was completed, a sample was taken and the solid-liquid mixture was separated to obtain the filtrate. Liquid chromatography analysis was performed, and the filtrate was concentrated, recrystallized, and dried to obtain the 2,5-furandicarboxylic acid product.

[0026] Example 3 This embodiment tests the application of the Mn50 / Beta molecular sieve catalyst prepared in Example 1 in the efficient catalytic oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA). The specific reaction procedure was as follows: 5 mL of ethyl acetate as solvent, 6 mmol of tert-butanol hydrogen peroxide (as oxidant), 0.0252 g of 5-hydroxymethylfurfural (HMF), and 70 mg of the Mn50 / Beta catalyst prepared in Example 1 were added to a 25 mL round-bottom flask. After the mixture was thoroughly mixed, it was placed in an oil bath and reacted at 80 °C with a stirring speed of 700 rpm for 6 h. After the reaction was completed, a sample was taken and the solid-liquid mixture was separated to obtain the filtrate. Liquid chromatography analysis was performed, and the filtrate was concentrated, recrystallized, and dried to obtain the 2,5-furandicarboxylic acid product.

[0027] Example 4 This embodiment tests the application of the Mn50 / Beta molecular sieve catalyst prepared in Example 1 in the efficient catalytic oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA). The specific reaction procedure was as follows: 5 mL of ethyl acetate as solvent, 6 mmol of tert-butanol hydrogen peroxide (as oxidant), 0.0252 g of 5-hydroxymethylfurfural (HMF), and 70 mg of the Mn50 / Beta catalyst prepared in Example 1 were added to a 25 mL round-bottom flask. After the mixture was thoroughly mixed, it was placed in an oil bath and reacted at 80 °C with a stirring speed of 750 rpm for 6 h. After the reaction was completed, a sample was taken and the solid-liquid mixture was separated to obtain the filtrate. Liquid chromatography analysis was performed, and the filtrate was concentrated, recrystallized, and dried to obtain the 2,5-furandicarboxylic acid product.

[0028] Comparative Example 1 This comparative example tests the application of the Mn50 / Beta molecular sieve catalyst prepared in Example 1 in the efficient catalytic oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA). The specific reaction procedure was as follows: 5 mL of ethyl acetate as solvent, 6 mmol of tert-butanol hydrogen peroxide (as oxidant), 0.0252 g of 5-hydroxymethylfurfural (HMF), and 70 mg of the Mn50 / Beta catalyst prepared in Example 1 were added to a 25 mL round-bottom flask. After the mixture was thoroughly mixed, it was placed in an oil bath and reacted at 80 °C with a stirring speed of 300 rpm for 6 h. After the reaction was completed, a sample was taken and the solid-liquid mixture was separated to obtain the filtrate. Liquid chromatography analysis was performed, and the filtrate was concentrated, recrystallized, and dried to obtain the 2,5-furandicarboxylic acid product.

[0029] Table 2 Catalytic performance of catalysts at different reaction speeds 600 99.8 84.9 84.9 700 99.9 89.1 89.0 750 99.8 89.3 89.2 300 15.9 8.2 1.3

[0030] As shown in Table 2, the FDCA yield of the Mn50 / Beta catalyst prepared in this invention increases slightly from 600 to 700 rpm with increasing rotation speed. After increasing to 750 rpm, it remains basically unchanged. At 300 rpm, the conversion rate and selectivity are much lower than at 600-75 rpm, indicating that the influence of external diffusion on catalytic performance is basically eliminated at a rotation speed of 700 rpm. The preferred reaction speed is 700 rpm.

[0031] Example 5 This embodiment tests the application of the Mn50 / Beta molecular sieve catalyst prepared in Example 1 in the efficient catalytic oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA). The specific reaction procedure was as follows: 30 mg Mn50 / Beta, 5 mL ethyl acetate as solvent, 6 mmol tert-butanol hydrogen peroxide (as oxidant), and 0.0252 g 5-hydroxymethylfurfural (HMF) were added to a 25 mL round-bottom flask. After thorough mixing, the mixture was placed in an oil bath and reacted at 80 °C under self-pressure with a stirring speed of 700 rpm for 6 hours. After the reaction was completed, a sample was taken and the solid-liquid mixture was separated to obtain the filtrate. Liquid chromatography analysis was performed, and the filtrate was concentrated, recrystallized, and dried to obtain the 2,5-furandicarboxylic acid product.

[0032] Example 6

[0033] This embodiment tests the application of the Mn50 / Beta molecular sieve catalyst prepared in Example 1 in the efficient catalytic oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA). The specific reaction procedure was as follows: 50 mg Mn50 / Beta, 5 mL ethyl acetate as solvent, 6 mmol tert-butanol hydrogen peroxide (as oxidant), and 0.0252 g 5-hydroxymethylfurfural (HMF) were added to a 25 mL round-bottom flask. After thorough mixing, the mixture was placed in an oil bath and reacted at 80 °C under self-pressure with a stirring speed of 700 rpm for 6 hours. After the reaction was completed, a sample was taken and the solid-liquid mixture was separated to obtain the filtrate. Liquid chromatography analysis was performed, and the filtrate was concentrated, recrystallized, and dried to obtain the 2,5-furandicarboxylic acid product.

[0034] Example 7

[0035] This embodiment tests the application of the Mn50 / Beta molecular sieve catalyst prepared in Example 1 in the efficient catalytic oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA). The specific reaction procedure was as follows: 90 mg Mn50 / Beta, 5 mL ethyl acetate as solvent, 6 mmol tert-butanol hydrogen peroxide (as oxidant), and 0.0252 g 5-hydroxymethylfurfural (HMF) were added to a 25 mL round-bottom flask. After thorough mixing, the mixture was placed in an oil bath and reacted at 80 °C under self-pressure with stirring at 700 rpm for 6 hours. After the reaction was completed, a sample was taken and the solid-liquid mixture was separated to obtain the filtrate. Liquid chromatography analysis was performed, and the filtrate was concentrated, recrystallized, and dried to obtain the 2,5-furandicarboxylic acid product.

[0036] Comparative Example 2 This embodiment tests the application of the Mn50 / Beta molecular sieve catalyst prepared in Example 1 in the efficient catalytic oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA). The specific reaction procedure was as follows: 10 mg Mn50 / Beta, 5 mL ethyl acetate as solvent, 6 mmol hydrogen peroxide tert-butanol (as oxidant), and 0.0252 g 5-hydroxymethylfurfural (HMF) were added to a 25 mL round-bottom flask. After the mixture was thoroughly mixed, it was placed in an oil bath and reacted at 80 °C under self-pressure with a stirring speed of 700 rpm for 6 h. After the reaction was completed, a sample was taken and the solid-liquid mixture was separated to obtain the filtrate. The filtrate was analyzed by liquid chromatography, concentrated, recrystallized, and dried to obtain the 2,5-furandicarboxylic acid product.

[0037] Table 3 Catalytic performance of molecular sieve catalysts with different catalyst dosages 30 99.9 54.5 54.5 50 99.4 83.5 83.0 90 99.8 86.6 86.4 10 64.8 12.0 7.8 As can be seen from Tables 3 and 2, with the increase of catalyst dosage, 5-hydroxymethylfurfural is basically completely converted, and the selectivity of 2,5-furandicarboxylic acid first increases and then tends to stabilize. Considering yield and economy, the preferred catalyst dosage is 70 mg.

[0038] Example 8

[0039] This embodiment tests the application of the Mn50 / Beta molecular sieve catalyst prepared in Example 1 in the efficient catalytic oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA). The specific reaction procedure was as follows: 5 mL of ethyl acetate as solvent, 2 mmol of tert-butanol peroxide (as oxidant), 0.0252 g of 5-hydroxymethylfurfural (HMF), and 70 mg of the Mn50 / Beta catalyst prepared in Example 1 were added to a 25 mL round-bottom flask. After the mixture was thoroughly mixed, it was placed in an oil bath and reacted at 80 °C with a stirring speed of 700 rpm for 6 h. After the reaction was completed, a sample was taken and the solid-liquid mixture was separated to obtain the filtrate. Liquid chromatography analysis was performed, and the filtrate was concentrated, recrystallized, and dried to obtain the 2,5-furandicarboxylic acid product.

[0040] Example 9

[0041] This embodiment tests the application of the Mn50 / Beta molecular sieve catalyst prepared in Example 1 in the efficient catalytic oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA). The specific reaction procedure was as follows: 5 mL of ethyl acetate as solvent, 4 mmol of tert-butanol peroxide (as oxidant), 0.0252 g of 5-hydroxymethylfurfural (HMF), and 70 mg of the Mn50 / Beta catalyst prepared in Example 1 were added to a 25 mL round-bottom flask. After the mixture was thoroughly mixed, it was placed in an oil bath and reacted at 80 °C with a stirring speed of 700 rpm for 6 h. After the reaction was completed, a sample was taken and the solid-liquid mixture was separated to obtain the filtrate. Liquid chromatography analysis was performed, and the filtrate was concentrated, recrystallized, and dried to obtain the 2,5-furandicarboxylic acid product.

[0042] Example 10

[0043] This embodiment tests the application of the Mn50 / Beta molecular sieve catalyst prepared in Example 1 in the efficient catalytic oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA). The specific reaction procedure was as follows: 5 mL of ethyl acetate as solvent, 8 mmol of tert-butanol peroxide (as oxidant), 0.0252 g of 5-hydroxymethylfurfural (HMF), and 70 mg of the Mn50 / Beta catalyst prepared in Example 1 were added to a 25 mL round-bottom flask. After the mixture was thoroughly mixed, it was placed in an oil bath and reacted at 80 °C with a stirring speed of 700 rpm for 6 h. After the reaction was completed, a sample was taken and the solid-liquid mixture was separated to obtain the filtrate. Liquid chromatography analysis was performed, and the filtrate was concentrated, recrystallized, and dried to obtain the 2,5-furandicarboxylic acid product.

[0044] Example 11

[0045] This embodiment tests the application of the Mn50 / Beta molecular sieve catalyst prepared in Example 1 in the efficient catalytic oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA). The specific reaction procedure was as follows: 5 mL of ethyl acetate as solvent, 10 mmol of tert-butanol hydrogen peroxide (as oxidant), 0.0252 g of 5-hydroxymethylfurfural (HMF), and 70 mg of the Mn50 / Beta catalyst prepared in Example 1 were added to a 25 mL round-bottom flask. After the mixture was thoroughly mixed, it was placed in an oil bath and reacted at 80 °C with a stirring speed of 700 rpm for 6 h. After the reaction was completed, a sample was taken and the solid-liquid mixture was separated to obtain the filtrate. Liquid chromatography analysis was performed, and the filtrate was concentrated, recrystallized, and dried to obtain the 2,5-furandicarboxylic acid product.

[0046] Example 12

[0047] This embodiment tests the application of the Mn50 / Beta molecular sieve catalyst prepared in Example 1 in the efficient catalytic oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA). The specific reaction procedure was as follows: 5 mL of ethyl acetate as solvent, 14 mmol of tert-butanol hydrogen peroxide (as oxidant), 0.0252 g of 5-hydroxymethylfurfural (HMF), and 70 mg of the Mn50 / Beta catalyst prepared in Example 1 were added to a 25 mL round-bottom flask. After the mixture was thoroughly mixed, it was placed in an oil bath and reacted at 80 °C with a stirring speed of 700 rpm for 6 h. After the reaction was completed, a sample was taken and the solid-liquid mixture was separated to obtain the filtrate. Liquid chromatography analysis was performed, and the filtrate was concentrated, recrystallized, and dried to obtain the 2,5-furandicarboxylic acid product.

[0048] Comparative Example 3 This embodiment tests the application of the Mn50 / Beta molecular sieve catalyst prepared in Example 1 in the efficient catalytic oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA). The specific reaction procedure was as follows: 5 mL of ethyl acetate as solvent, 1 mmol of tert-butanol hydrogen peroxide (as oxidant), 0.0252 g of 5-hydroxymethylfurfural (HMF), and 70 mg of the Mn50 / Beta catalyst prepared in Example 1 were added to a 25 mL round-bottom flask. After the mixture was thoroughly mixed, it was placed in an oil bath and reacted at 80 °C with a stirring speed of 700 rpm for 6 h. After the reaction was completed, a sample was taken and the solid-liquid mixture was separated to obtain the filtrate. Liquid chromatography analysis was performed, and the filtrate was concentrated, recrystallized, and dried to obtain the 2,5-furandicarboxylic acid product.

[0049] Table 4 Catalytic performance of catalysts at different amounts of tert-butanol peroxide 2 99.6 51.7 51.5 4 99.3 88.3 87.8 8 99.6 70.6 70.4 10 99.3 67.1 66.6 14 99.6 34.5 34.4 1 35.8 5.3 1.9 As shown in Tables 4 and 2, the FDCA yield of the Mn50 / Beta catalyst prepared in this invention initially increases to 89.0% with increasing amounts of tert-butanol hydrogen peroxide, then gradually decreases. The preferred amount of tert-butanol hydrogen peroxide used in the reaction is 6 mmol. Meanwhile, outside the scope of protection, the conversion and yield at 1 mmol TBHP are significantly lower than those in the range of 2-14 mmol TBHP.

[0050] Example 13

[0051] This embodiment tests the application of the Mn50 / Beta molecular sieve catalyst prepared in Example 1 in the efficient catalytic oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA). The specific reaction procedure was as follows: 5 mL of ethyl acetate as solvent, 6 mmol of tert-butanol peroxide (as oxidant), 0.0252 g of 5-hydroxymethylfurfural (HMF), and 70 mg of the Mn50 / Beta catalyst prepared in Example 1 were added to a 25 mL round-bottom flask. After the mixture was thoroughly mixed, it was placed in an oil bath and reacted at 75 °C with a stirring speed of 700 rpm for 6 h. After the reaction was completed, a sample was taken and the solid-liquid mixture was separated to obtain the filtrate. Liquid chromatography analysis was performed, and the filtrate was concentrated, recrystallized, and dried to obtain the 2,5-furandicarboxylic acid product.

[0052] Example 14

[0053] This embodiment tests the application of the Mn50 / Beta molecular sieve catalyst prepared in Example 1 in the efficient catalytic oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA). The specific reaction procedure was as follows: 5 mL of ethyl acetate as solvent, 6 mmol of tert-butanol hydrogen peroxide (as oxidant), 0.0252 g of 5-hydroxymethylfurfural (HMF), and 70 mg of the Mn50 / Beta catalyst prepared in Example 1 were added to a 25 mL round-bottom flask. After the mixture was thoroughly mixed, it was placed in an oil bath and reacted at 85 °C with a stirring speed of 700 rpm for 6 h. After the reaction was completed, a sample was taken and the solid-liquid mixture was separated to obtain the filtrate. Liquid chromatography analysis was performed, and the filtrate was concentrated, recrystallized, and dried to obtain the 2,5-furandicarboxylic acid product.

[0054] Example 15

[0055] This embodiment tests the application of the Mn50 / Beta molecular sieve catalyst prepared in Example 1 in the efficient catalytic oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA). The specific reaction procedure was as follows: 5 mL of ethyl acetate as solvent, 6 mmol of tert-butanol hydrogen peroxide (as oxidant), 0.0252 g of 5-hydroxymethylfurfural (HMF), and 70 mg of the Mn50 / Beta catalyst prepared in Example 1 were added to a 25 mL round-bottom flask. After the mixture was thoroughly mixed, it was placed in an oil bath and reacted at 90 °C with a stirring speed of 700 rpm for 6 h. After the reaction was completed, a sample was taken and the solid-liquid mixture was separated to obtain the filtrate. Liquid chromatography analysis was performed, and the filtrate was concentrated, recrystallized, and dried to obtain the 2,5-furandicarboxylic acid product.

[0056] Comparative Example 4 This comparative example tests the application of the Mn50 / Beta molecular sieve catalyst prepared in Example 1 in the efficient catalytic oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA). The specific reaction procedure was as follows: 5 mL of ethyl acetate as solvent, 6 mmol of tert-butanol peroxide (as oxidant), 0.0252 g of 5-hydroxymethylfurfural (HMF), and 70 mg of the Mn50 / Beta catalyst prepared in Example 1 were added to a 25 mL round-bottom flask. After the mixture was thoroughly mixed, it was placed in an oil bath and reacted at 40 °C with a stirring speed of 700 rpm for 6 h. After the reaction was completed, a sample was taken and the solid-liquid mixture was separated to obtain the filtrate. Liquid chromatography analysis was performed, and the filtrate was concentrated, recrystallized, and dried to obtain the 2,5-furandicarboxylic acid product.

[0057] Table 5 Catalytic performance of molecular sieve catalysts at different reaction temperatures 75 99.3 56.5 56.1 85 99.8 88.9 88.9 90 99.8 85.5 85.5 40 32.1 8.6 2.8 As can be seen from Tables 5 and 2, the conversion rate of 5-hydroxymethylfurfural does not change significantly with increasing reaction temperature, but the selectivity of 2,5-furandicarboxylic acid first increases and then decreases. Considering the yield and reaction energy consumption, the preferred reaction temperature is 80℃.

[0058] Example 16

[0059] This embodiment tests the application of the Mn50 / Beta molecular sieve catalyst prepared in Example 1 in the efficient catalytic oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA). The specific reaction procedure was as follows: 5 mL of ethyl acetate as solvent, 6 mmol of tert-butanol hydrogen peroxide (as oxidant), 0.0252 g of 5-hydroxymethylfurfural (HMF), and 70 mg of the Mn50 / Beta catalyst prepared in Example 1 were added to a 25 mL round-bottom flask. After the mixture was thoroughly mixed, it was placed in an oil bath and reacted at 80 °C with a stirring speed of 700 rpm for 2 h. After the reaction was completed, a sample was taken and the solid-liquid mixture was separated to obtain the filtrate. Liquid chromatography analysis was performed, and the filtrate was concentrated, recrystallized, and dried to obtain the 2,5-furandicarboxylic acid product.

[0060] Example 17

[0061] This embodiment tests the application of the Mn50 / Beta molecular sieve catalyst prepared in Example 1 in the efficient catalytic oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA). The specific reaction procedure was as follows: 5 mL of ethyl acetate as solvent, 6 mmol of tert-butanol peroxide (as oxidant), 0.0252 g of 5-hydroxymethylfurfural (HMF), and 70 mg of the Mn50 / Beta catalyst prepared in Example 1 were added to a 25 mL round-bottom flask. After the mixture was thoroughly mixed, it was placed in an oil bath and reacted at 80 °C with a stirring speed of 700 rpm for 4 h. After the reaction was completed, a sample was taken and the solid-liquid mixture was separated to obtain the filtrate. Liquid chromatography analysis was performed, and the filtrate was concentrated, recrystallized, and dried to obtain the 2,5-furandicarboxylic acid product.

[0062] Example 18

[0063] This embodiment tests the application of the Mn50 / Beta molecular sieve catalyst prepared in Example 1 in the efficient catalytic oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA). The specific reaction procedure was as follows: 5 mL of ethyl acetate as solvent, 6 mmol of tert-butanol hydrogen peroxide (as oxidant), 0.0252 g of 5-hydroxymethylfurfural (HMF), and 70 mg of the Mn50 / Beta catalyst prepared in Example 1 were added to a 25 mL round-bottom flask. After the mixture was thoroughly mixed, it was placed in an oil bath and reacted at 80 °C with a stirring speed of 700 rpm for 9 h. After the reaction was completed, a sample was taken and the solid-liquid mixture was separated to obtain the filtrate. Liquid chromatography analysis was performed, and the filtrate was concentrated, recrystallized, and dried to obtain the 2,5-furandicarboxylic acid product.

[0064] Example 19

[0065] This embodiment tests the application of the Mn50 / Beta molecular sieve catalyst prepared in Example 1 in the efficient catalytic oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA). The specific reaction procedure was as follows: 5 mL of ethyl acetate as solvent, 6 mmol of tert-butanol hydrogen peroxide (as oxidant), 0.0252 g of 5-hydroxymethylfurfural (HMF), and 70 mg of the Mn50 / Beta catalyst prepared in Example 1 were added to a 25 mL round-bottom flask. After the mixture was thoroughly mixed, it was placed in an oil bath and reacted at 80 °C with a stirring speed of 700 rpm for 12 h. After the reaction was completed, a sample was taken and the solid-liquid mixture was separated to obtain the filtrate. Liquid chromatography analysis was performed, and the filtrate was concentrated, recrystallized, and dried to obtain the 2,5-furandicarboxylic acid product.

[0066] Comparative Example 5 This embodiment tests the application of the Mn50 / Beta molecular sieve catalyst prepared in Example 1 in the efficient catalytic oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA). The specific reaction procedure was as follows: 5 mL of ethyl acetate as solvent, 6 mmol of tert-butanol peroxide (as oxidant), 0.0252 g of 5-hydroxymethylfurfural (HMF), and 70 mg of the Mn50 / Beta catalyst prepared in Example 1 were added to a 25 mL round-bottom flask. After the mixture was thoroughly mixed, it was placed in an oil bath and reacted at 80 °C with a stirring speed of 700 rpm for 0.5 h. After the reaction was completed, a sample was taken and the solid and liquid phases were separated to obtain the filtrate. Liquid chromatography analysis was performed, and the filtrate was concentrated, recrystallized, and dried to obtain the 2,5-furandicarboxylic acid product.

[0067] Table 6 Catalytic performance of molecular sieve catalysts at different reaction times 2 35.8 1.7 0.6 4 99.7 41.6 41.5 9 99.9 93.3 93.3 12 100.0 99.3 99.3 0.5 9.6 3.0 0.3 As shown in Tables 6 and 2, with the extension of reaction time, the conversion rate of 5-hydroxymethylfurfural increases sharply compared to reaction times of 2h, 4h, 6h, 9h, and 12h. The selectivity of 2,5-furandicarboxylic acid initially increases and then stabilizes. Meanwhile, at a reaction time of 0.5h, both the conversion rate and yield are at relatively low levels. Considering both yield and reaction energy consumption, a reaction time of 12h is preferred.

[0068] Example 20

[0069] The experiment was conducted using the optimal reaction conditions of 70 mg catalyst, 80 °C, and 6 h as described in Example 3. After the reaction, the reaction solution was centrifuged, and the solid catalyst at the bottom was collected and then dried at 80 °C for 12 h to obtain the recovered catalyst. The recovered catalyst was then added back into the same reaction system, and the above reaction and recovery steps were repeated twice to evaluate the catalyst's recyclability.

[0070] Example 21

[0071] The experiment was conducted using the optimal reaction conditions of 70 mg catalyst, 80 °C, and 6 h as described in Example 3. After the reaction, the reaction solution was centrifuged, and the solid catalyst at the bottom was collected and then dried at 80 °C for 12 h to obtain the recovered catalyst. The recovered catalyst was then added back into the same reaction system, and the above reaction and recovery steps were repeated three times. The recyclability of the catalyst was evaluated.

[0072] Example 22

[0073] The experiment was conducted using the optimal reaction conditions of 70 mg catalyst, 80 °C, and 6 h as described in Example 3. After the reaction, the reaction solution was centrifuged, and the solid catalyst at the bottom was collected and then dried at 80 °C for 12 h to obtain the recovered catalyst. The recovered catalyst was then added back into the same reaction system, and the above reaction and recovery steps were repeated four times. The recyclability of the catalyst was evaluated.

[0074] Comparative Example 6 The experiment was conducted using the optimal reaction conditions of 70 mg catalyst, 80 °C, and 6 h as described in Example 3. After the reaction, the reaction solution was centrifuged, and the solid catalyst at the bottom was collected and then dried at 80 °C for 12 h to obtain the recovered catalyst. The recovered catalyst was then added back into the same reaction system, and the above reaction and recovery steps were repeated 5 times. The recycling performance of the catalyst was evaluated.

[0075] Comparative Example 7 The experiment was conducted using the optimal reaction conditions of 70 mg catalyst, 80 °C, and 6 h as described in Example 3. After the reaction, the reaction solution was centrifuged, and the solid catalyst at the bottom was collected and then dried at 80 °C for 12 h to obtain the recovered catalyst. The recovered catalyst was then added back into the same reaction system, and the above reaction and recovery steps were repeated 6 times. After the 5th time, the catalyst was calcined in air at 250 °C for 5 h to remove the carbon deposits on the catalyst. The recyclability of the catalyst was evaluated.

[0076] Table 7. Catalyst Recycling Performance 2 99.9 88.6 88.6 3 99.9 86.5 86.5 4 99.9 85.8 85.8 5 99.9 69.8 69.8 6 99.9 88.3 88.2 As shown in Tables 7 and 2, the conversion rate and selectivity of the Mn50 / Beta catalyst prepared in this invention did not decrease significantly after four cycles. However, the selectivity of the product dropped sharply to 69.8% after the fifth cycle, which may be due to coking on the catalyst. After removing the coking by high-temperature calcination, the catalytic activity was basically restored to the initial activity, demonstrating its excellent structural stability and industrial application potential.

[0077] Comparative Example 8 In this example, the Mn-supported molecular sieve catalyst is Mnx / Beta, and the Si / Mn molar ratio x is 50. The preparation method of the supported Mn-based molecular sieve catalyst in this example includes the following steps: S1. Weigh 5g of silica-alumina type Beta molecular sieve into a 250mL round-bottom flask, add 150g of commercially available 6mol / L concentrated nitric acid for acid washing, place the round-bottom flask in an oil bath, adjust the temperature to 130℃ and treat the Beta molecular sieve in concentrated nitric acid for 12h, repeat this process twice; after reflux, cool to room temperature, filter, dry at 80℃ for 8h, and finally calcine in a muffle furnace at 550℃ for 6h to obtain deeply dealuminized Beta molecular sieve, named Beta-DA. S2. Weigh 0.07g of the Beta-DA molecular sieve prepared in S1 and place it in a 25mL round-bottom flask. Then add manganese nitrate trihydrate and mix. Add deionized water at a mass ratio of 30 times that of the molecular sieve and stir for 3-8 hours. After stirring, rotary evaporate and dry at 45℃ using conventional methods. Then dry in an oven at 80℃ for 8 hours to obtain Mn50 / Beta molecular sieve.

[0078] The reaction system and feed amount were the same as in Example 3. The catalytic performance of rotary evaporation and conventional drying was evaluated, and the results are shown in Table 8.

[0079] Table 8 Catalytic performance under rotary evaporation and non-rotary evaporation conditions during catalyst loading. Rotary steam 99.4 89.1 89.0 Conventional drying 99.0 51.1 51.0 As shown in Tables 8 and 2, the catalytic effect of the catalyst obtained by low-temperature rotary evaporation after catalyst impregnation treatment is significantly higher than that of the conventionally dried catalyst. During static drying at 80°C, moisture evaporation causes manganese ions to migrate to the outer surface of the molecular sieve, almost reaching the entire surface, affecting dispersibility and clogging the pores on the molecular sieve surface. During low-temperature rotary evaporation, the reduced pressure environment of rotation accelerates the removal rate of impregnated moisture, breaks the thermodynamic gradient, and allows manganese ions to be stably dispersed and anchored on the deeply dealulated Beta molecular sieve support.

[0080] Example 23

[0081] In this example, the Mn-supported molecular sieve catalyst is Mnx / Beta, and the Si / Mn molar ratio x is 30. The preparation method of the supported Mn-based molecular sieve catalyst in this example includes the following steps: S1. Weigh 5g of silica-alumina type Beta molecular sieve into a 250mL round-bottom flask, add 150g of commercially available 6mol / L concentrated nitric acid for acid washing, place the round-bottom flask in an oil bath, adjust the temperature to 130℃ and treat the Beta molecular sieve in concentrated nitric acid for 12h, repeat this process twice; after reflux, cool to room temperature, filter, dry at 80℃ for 8h, and finally calcine in a muffle furnace at 550℃ for 6h to obtain deeply dealuminized Beta molecular sieve, named Beta-DA. S2. Weigh 0.07g of the Beta-DA molecular sieve prepared in S1 and place it in a 25mL round-bottom flask. Then add manganese nitrate trihydrate and mix. Add deionized water at a mass ratio of 30 times that of the molecular sieve and stir for 3-8 hours. After stirring, remove the water by rotary evaporation at 45℃ and then dry in an oven at 80℃ for 8 hours to obtain molecular sieves with different Mn contents.

[0082] The reaction system and feed amount are the same as in Example 3. The catalytic performance of different Mn contents is evaluated.

[0083] Example 24

[0084] In this example, the Mn-supported molecular sieve catalyst is Mnx / Beta, and the Si / Mn molar ratio x is 100. The preparation method of the supported Mn-based molecular sieve catalyst in this example includes the following steps: S1. Weigh 5g of silica-alumina type Beta molecular sieve into a 250mL round-bottom flask, add 150g of commercially available 6mol / L concentrated nitric acid for acid washing, place the round-bottom flask in an oil bath, adjust the temperature to 130℃ and treat the Beta molecular sieve in concentrated nitric acid for 12h, repeat this process twice; after reflux, cool to room temperature, filter, dry at 80℃ for 8h, and finally calcine in a muffle furnace at 550℃ for 6h to obtain deeply dealuminized Beta molecular sieve, named Beta-DA. S2. Weigh 0.07g of the Beta-DA molecular sieve prepared in S1 and place it in a 25mL round-bottom flask. Then add manganese nitrate trihydrate and mix. Add deionized water at a mass ratio of 30 times that of the molecular sieve and stir for 3-8 hours. After stirring, remove the water by rotary evaporation at 45℃ and then dry in an oven at 80℃ for 8 hours to obtain molecular sieves with different Mn contents. The reaction system and feed amount are the same as in Example 3. The catalytic performance of different Mn contents is evaluated.

[0085] Example 25

[0086] In this example, the Mn-supported molecular sieve catalyst is Mnx / Beta, and the Si / Mn molar ratio x is 150. The preparation method of the supported Mn-based molecular sieve catalyst in this example includes the following steps: S1. Weigh 5g of silica-alumina type Beta molecular sieve into a 250mL round-bottom flask, add 150g of commercially available 6mol / L concentrated nitric acid for acid washing, place the round-bottom flask in an oil bath, adjust the temperature to 130℃ and treat the Beta molecular sieve in concentrated nitric acid for 12h, repeat this process twice; after reflux, cool to room temperature, filter, dry at 80℃ for 8h, and finally calcine in a muffle furnace at 550℃ for 6h to obtain deeply dealuminized Beta molecular sieve, named Beta-DA. S2. Weigh 0.07g of the Beta-DA molecular sieve prepared in S1 and place it in a 25mL round-bottom flask. Then add manganese nitrate trihydrate and mix. Add deionized water at a mass ratio of 30 times that of the molecular sieve and stir for 3-8 hours. After stirring, remove the water by rotary evaporation at 45℃ and then dry in an oven at 80℃ for 8 hours to obtain molecular sieves with different Mn contents.

[0087] The reaction system and feed amount are the same as in Example 3. The catalytic performance of different Mn contents is evaluated.

[0088] Example 26

[0089] In this example, the Mn-supported molecular sieve catalyst is Mnx / Beta, and the Si / Mn molar ratio x is 200. The preparation method of the supported Mn-based molecular sieve catalyst in this example includes the following steps: S1. Weigh 5g of silica-alumina type Beta molecular sieve into a 250mL round-bottom flask, add 150g of commercially available 6mol / L concentrated nitric acid for acid washing, place the round-bottom flask in an oil bath, adjust the temperature to 130℃ and treat the Beta molecular sieve in concentrated nitric acid for 12h, repeat this process twice; after reflux, cool to room temperature, filter, dry at 80℃ for 8h, and finally calcine in a muffle furnace at 550℃ for 6h to obtain deeply dealuminized Beta molecular sieve, named Beta-DA. S2. Weigh 0.07g of the Beta-DA molecular sieve prepared in S1 and place it in a 25mL round-bottom flask. Then add manganese nitrate trihydrate and mix. Add deionized water at a mass ratio of 30 times that of the molecular sieve and stir for 3-8 hours. After stirring, remove the water by rotary evaporation at 45℃ and then dry in an oven at 80℃ for 8 hours to obtain molecular sieves with different Mn contents.

[0090] The reaction system and feed amount are the same as in Example 3. The catalytic performance of different Mn contents is evaluated.

[0091] Comparative Example 9 The Mn-supported molecular sieve catalyst in this comparative example is Mnx / Beta, with a Si / Mn molar ratio x of 400; The preparation method of the supported Mn-based molecular sieve catalyst in this example includes the following steps: S1. Weigh 5g of silica-alumina type Beta molecular sieve into a 250mL round-bottom flask, add 150g of commercially available 6mol / L concentrated nitric acid for acid washing, place the round-bottom flask in an oil bath, adjust the temperature to 130℃ and treat the Beta molecular sieve in concentrated nitric acid for 12h, repeat this process twice; after reflux, cool to room temperature, filter, dry at 80℃ for 8h, and finally calcine in a muffle furnace at 550℃ for 6h to obtain deeply dealuminized Beta molecular sieve, named Beta-DA. S2. Weigh 0.07g of the Beta-DA molecular sieve prepared in S1 and place it in a 25mL round-bottom flask. Then add manganese nitrate trihydrate and mix. Add deionized water at a mass ratio of 30 times that of the molecular sieve and stir for 3-8 hours. After stirring, remove the water by rotary evaporation at 45℃ and then dry in an oven at 80℃ for 8 hours to obtain molecular sieves with different Mn contents.

[0092] The reaction system and feed amount are the same as in Example 3. The catalytic performance of different Mn contents is evaluated.

[0093] Table 9 Catalytic performance of molecular sieve catalysts with different Mn contents Mn30 / Beta 99.9 69.2 69.1 Mn100 / Beta 99.3 33.7 33.4 Mn150 / Beta 98.2 25.2 24.8 Mn200 / Beta 98.9 23.5 23.2 Mn400 / Beta 63.2 5.3 3.3 As can be seen from Tables 9 and 2, the yield of FDCA first increases with the increase of the silicon-manganese ratio of the molecular sieve, reaching the optimal level when the Mn50 / Beta catalyst is increased. Subsequently, the yield decreases significantly with further increases. This demonstrates both the catalytic effect of Mn species and the fact that excessive Mn may block the molecular sieve channels and affect the catalytic effect.

[0094] Comparative Example 10 The difference between this comparative example and Example 1 is that Mn was replaced with Nb in the example, resulting in Nb50 / Beta. This comparative example utilizes the molecular sieve catalyst from the example for the efficient catalytic oxidation of 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid. Specifically, 5 mL of ethyl acetate, 6 mmol of tert-butanol peroxide, 0.0252 g of 5-hydroxymethylfurfural, and 70 mg of the catalyst prepared in this comparative example were added to a 25 mL round-bottom flask. The mixture was thoroughly mixed and reacted under pressure at 80 °C and 700 rpm for 6 hours in an oil bath.

[0095] Comparative Example 11 The difference between this comparative example and Example 1 is that Mn was replaced with Mo in the example, resulting in Mo50 / Beta. This comparative example utilizes the molecular sieve catalyst from the example for the efficient catalytic oxidation of 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid. Specifically, 5 mL of ethyl acetate, 6 mmol of tert-butanol peroxide, 0.0252 g of 5-hydroxymethylfurfural, and 70 mg of the catalyst prepared in this comparative example were added to a 25 mL round-bottom flask. The mixture was thoroughly mixed and reacted under pressure at 80 °C and 700 rpm for 6 hours in an oil bath.

[0096] Comparative Example 12 The difference between this comparative example and Example 1 is that Mn was replaced with Co in the example, resulting in Co50 / Beta. This comparative example utilizes the molecular sieve catalyst from the example for the efficient catalytic oxidation of 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid. Specifically, 5 mL of ethyl acetate, 6 mmol of tert-butanol peroxide, 0.0252 g of 5-hydroxymethylfurfural, and 70 mg of the catalyst prepared in this comparative example were added to a 25 mL round-bottom flask. The mixture was thoroughly mixed and reacted under pressure at 80 °C and 700 rpm for 6 hours in an oil bath.

[0097] Comparative Example 13 The difference between this comparative example and Example 1 is that Mn was replaced with Ta in the example, resulting in Ta50 / Beta. This comparative example utilizes the molecular sieve catalyst from the example for the efficient catalytic oxidation of 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid. Specifically, 5 mL of ethyl acetate, 6 mmol of tert-butanol peroxide, 0.0252 g of 5-hydroxymethylfurfural, and 70 mg of the catalyst prepared in this comparative example were added to a 25 mL round-bottom flask. The mixture was thoroughly mixed and reacted under pressure at 80 °C and 700 rpm for 6 hours in an oil bath.

[0098] Comparative Example 14 The difference between this comparative example and Example 1 is that Mn was replaced with V in the example, resulting in V50 / Beta. This comparative example utilizes the molecular sieve catalyst from the example for the efficient catalytic oxidation of 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid. Specifically, 5 mL of ethyl acetate, 6 mmol of tert-butanol peroxide, 0.0252 g of 5-hydroxymethylfurfural, and 70 mg of the catalyst prepared in this comparative example were added to a 25 mL round-bottom flask. The mixture was thoroughly mixed and reacted under pressure at 80 °C and 700 rpm for 6 hours in an oil bath.

[0099] Table 10 Reaction performance of different catalysts Nb50 / Beta 76.8 1.4 1.0 Mo50 / Beta 99.1 47.8 47.4 Co50 / Beta 99.5 62.3 62.0 Ta50 / Beta 92.6 8.2 7.6 V50 / Beta 99.9 56.9 56.1 As can be seen from Tables 10 and 2, the molecular sieve catalysts with the introduction of Mn species exhibited significant catalytic effects.

[0100] Comparative Example 15 The difference between this comparative example and Example 1 is that in the example, the Beta topological molecular sieve was replaced with the MWW topological structure to obtain Mn50 / MWW. This comparative example uses the example molecular sieve catalyst for the efficient catalytic oxidation of 5-hydroxymethylfurfural to prepare 2,5-furandicarboxylic acid. Specifically, 5 mL of ethyl acetate, 6 mmol of hydrogen peroxide tert-butanol, 0.0252 g of 5-hydroxymethylfurfural, and 70 mg of the catalyst prepared in this comparative example were added to a 25 mL round-bottom flask. After thorough mixing, the mixture was reacted under pressure at 80 °C and 700 rpm in an oil bath for 6 hours with stirring.

[0101] Comparative Example 16 The difference between this comparative example and Example 1 is that in the example, the Beta topological molecular sieve was replaced with the MOR topological structure to obtain Mn50 / MOR. This comparative example uses the example molecular sieve catalyst for the efficient catalytic oxidation of 5-hydroxymethylfurfural to prepare 2,5-furandicarboxylic acid. Specifically, 5 mL of ethyl acetate, 6 mmol of tert-butanol peroxide, 0.0252 g of 5-hydroxymethylfurfural, and 70 mg of the catalyst prepared in this comparative example were added to a 25 mL round-bottom flask. The mixture was thoroughly mixed and reacted under pressure at 80 °C and 700 rpm for 6 hours in an oil bath.

[0102] Comparative Example 17 The difference between this comparative example and Example 1 is that in the example, the Beta topological molecular sieve was replaced with a Y topological structure to obtain Mn50 / Y. This comparative example uses the example molecular sieve catalyst for the efficient catalytic oxidation of 5-hydroxymethylfurfural to prepare 2,5-furandicarboxylic acid. Specifically, 5 mL of ethyl acetate, 6 mmol of hydrogen peroxide tert-butanol, 0.0252 g of 5-hydroxymethylfurfural, and 70 mg of the catalyst prepared in this comparative example were added to a 25 mL round-bottom flask. The mixture was thoroughly mixed and reacted under pressure at 80 °C and 700 rpm for 6 hours in an oil bath.

[0103] Table 11 Reaction performance of different catalysts Mn50 / MWW 98.8 27.5 27.2 Mn50 / MOR 98.2 57.9 56.9 Mn50 / Y 98.7 85.4 84.3 As can be seen from Tables 11 and 2, the Mn molecular sieves using the Beta support exhibited excellent catalytic performance in both yields.

[0104] Comparative Example 18 The difference between this comparative example and Example 1 is that in Example 1, Mn50 / Beta was obtained by calcining at 550°C for 3 hours; in this comparative example, the molecular sieve catalyst from the example is used for the efficient catalytic oxidation of 5-hydroxymethylfurfural to prepare 2,5-furandicarboxylic acid. Specifically, 5 mL of ethyl acetate, 6 mmol of hydrogen peroxide tert-butanol, 0.0252 g of 5-hydroxymethylfurfural, and 70 mg of the catalyst prepared in this comparative example are added to a 25 mL round-bottom flask. After thorough mixing, the mixture is reacted under pressure at 80°C and 700 rpm in an oil bath for 6 hours with stirring.

[0105] Comparative Example 19 The difference between this comparative example and Example 1 is that, in Comparative 17, Mn50 / Y was obtained by calcining at 550℃ for 3 hours; in this comparative example, the molecular sieve catalyst from the example is used for the efficient catalytic oxidation of 5-hydroxymethylfurfural to prepare 2,5-furandicarboxylic acid. Specifically, 5 mL of ethyl acetate, 6 mmol of hydrogen peroxide tert-butanol, 0.0252 g of 5-hydroxymethylfurfural, and 70 mL of the catalyst prepared in this comparative example are added to a 25 mL round-bottom flask. After thorough mixing, the mixture is reacted under pressure at 80℃ and 700 rpm for 6 hours in an oil bath.

[0106] Table 12 Reaction performance of different catalysts Mn50 / Y 98.7 85.4 84.3 Mn50 / Beta roasting 99.3 56.7 56.3 Mn50 / Y calcination 98.8 37.5 37.0 A comparison of Tables 12, 11, and 2 shows that the yield of the catalyst decreased significantly after high-temperature calcination. The calcination process affected the dispersion of Mn species, and the resulting Mn clusters blocked the molecular sieve channels, thus impacting catalytic performance. Therefore, it is preferable to use Mn50 / Beta without undergoing high-temperature calcination at 550℃.

[0107] Example 27

[0108] The difference between this embodiment and Example 1 lies in the concentration of nitric acid used in the Beta molecular sieve support in the preparation method of the supported Mn-based molecular sieve catalyst in this embodiment, which includes the following steps: S1. Weigh 5g of silica-alumina type Beta molecular sieve into a 250mL round-bottom flask, add 150g of 14mol / L concentrated nitric acid for acid washing, place the round-bottom flask in an oil bath, adjust the temperature to 130℃ and treat the Beta molecular sieve in concentrated nitric acid for 12h, repeat this process twice; after reflux, cool to room temperature, filter, dry at 80℃ for 8h, and finally calcine in a muffle furnace at 550℃ for 6h to obtain deeply dealuminized Beta molecular sieve, named Beta-DA. S2. Weigh 0.07g of the Beta-DA molecular sieve prepared in S1 and place it in a 25mL round-bottom flask. Then add manganese nitrate trihydrate and mix. Add deionized water at a mass ratio of 30 times that of the molecular sieve and stir for 3-8 hours. After stirring, remove the water by rotary evaporation at 45℃ and then dry in an oven at 80℃ for 8 hours to obtain Mn50 / Beta molecular sieves with different acid concentrations for preparing Beta supports.

[0109] The reaction system and feed amount are the same as in Example 3. The catalytic performance of the carrier treated with different acid concentrations is evaluated.

[0110] Comparative Example 20 The difference between this comparative example and Example 1 lies in the concentration of nitric acid used in the Beta molecular sieve support used in the preparation method of the supported Mn-based molecular sieve catalyst in this example, which includes the following steps: S1. Weigh 5g of silica-alumina type Beta molecular sieve into a 250mL round-bottom flask, add 150g of 1mol / L concentrated nitric acid for acid washing, place the round-bottom flask in an oil bath, adjust the temperature to 130℃, and treat the Beta molecular sieve in concentrated nitric acid for 12h. Repeat this process twice. After reflux, cool to room temperature, filter, dry at 80℃ for 8h, and finally calcine in a muffle furnace at 550℃ for 6h to obtain a deeply dealuminized Beta molecular sieve, named Beta-DA. S2. Weigh 0.07g of the Beta-DA molecular sieve prepared in S1 and place it in a 25mL round-bottom flask. Then add manganese nitrate trihydrate and mix. Add deionized water at a mass ratio of 30 times that of the molecular sieve and stir for 3-8 hours. After stirring, remove the water by rotary evaporation at 45℃ and then dry in an oven at 80℃ for 8 hours to obtain Mn50 / Beta molecular sieves with different acid concentrations for preparing Beta supports.

[0111] The reaction system and feed amount are the same as in Example 3. The catalytic performance of the carrier treated with different acid concentrations is evaluated.

[0112] Comparative Example 21 The difference between this comparative example and Example 1 lies in the concentration of nitric acid used in the Beta molecular sieve support used in the preparation method of the supported Mn-based molecular sieve catalyst in this example, which includes the following steps: S1. Weigh 5g of silica-alumina type Beta molecular sieve into a 250mL round-bottom flask, add 150g of 2mol / L concentrated nitric acid for acid washing, place the round-bottom flask in an oil bath, adjust the temperature to 130℃, and treat the Beta molecular sieve in concentrated nitric acid for 12h. Repeat this process twice. After reflux, cool to room temperature, filter, dry at 80℃ for 8h, and finally calcine in a muffle furnace at 550℃ for 6h to obtain a deeply dealuminized Beta molecular sieve, named Beta-DA. S2. Weigh 0.07g of the Beta-DA molecular sieve prepared in S1 and place it in a 25mL round-bottom flask. Then add manganese nitrate trihydrate and mix. Add deionized water at a mass ratio of 30 times that of the molecular sieve and stir for 3-8 hours. After stirring, remove the water by rotary evaporation at 45℃ and then dry in an oven at 80℃ for 8 hours to obtain Mn50 / Beta molecular sieves with different acid concentrations for preparing Beta supports.

[0113] The reaction system and feed amount are the same as in Example 3. The catalytic performance of the carrier treated with different acid concentrations is evaluated.

[0114] Table 13 Catalytic performance of the support treated with different acid concentrations 1 68.6 3.5 2.4 2 73.6 4.3 3.2 14 99.9 90.3 90.2 As shown in Tables 13 and 2, when the Beta catalyst support was treated with different concentrations of concentrated nitric acid in the early stages, the conversion, selectivity, and yield of supports treated with 1 mol / L and 2 mol / L concentrated nitric acid were significantly lower than those treated with 6 mol / L in the catalytic oxidation of 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid. Furthermore, increasing the concentrated nitric acid concentration to 14 mol / L did not significantly increase the conversion, selectivity, or yield. The high concentration of nitric acid ensured the dealumination effect of the Beta molecular sieve support, providing a suitable anchorage for Mn in the silanol groups. 2+ The prerequisite is provided: 6 mol / L concentrated nitric acid is preferred as the concentration of concentrated nitric acid used for beta carrier dealuminization.

[0115] Example 28

[0116] The difference between this embodiment and Example 1 lies in the acid treatment time of the Beta molecular sieve support in the preparation method of the supported Mn-based molecular sieve catalyst in this embodiment, which includes the following steps: S1. Weigh 5g of silica-alumina type Beta molecular sieve into a 250mL round-bottom flask, add 150g of 6mol / L concentrated nitric acid for acid washing, place the round-bottom flask in an oil bath, adjust the temperature to 130℃, and treat the Beta molecular sieve in concentrated nitric acid for 24h. Repeat this process twice. After reflux, cool to room temperature, filter, dry at 80℃ for 8h, and finally calcine in a muffle furnace at 550℃ for 6h to obtain a deeply dealuminized Beta molecular sieve, named Beta-DA. S2. Weigh 0.07g of the Beta-DA molecular sieve prepared in S1 and place it in a 25mL round-bottom flask. Then add manganese nitrate trihydrate and mix. Add deionized water at a mass ratio of 30 times that of the molecular sieve and stir for 3-8 hours. After stirring, remove the water by rotary evaporation at 45℃ and then dry in an oven at 80℃ for 8 hours to obtain Mn50 / Beta molecular sieves with different acid treatment times for preparing Beta support.

[0117] The reaction system and feed amount are the same as in Example 3. The catalytic performance of the catalyst under different acid treatment times is evaluated.

[0118] Comparative Example 22 The difference between this comparative example and Example 1 lies in the different acid treatment time of the Beta molecular sieve support in the preparation method of the supported Mn-based molecular sieve catalyst in this example, including the following steps: S1. Weigh 5g of silica-alumina type Beta molecular sieve into a 250mL round-bottom flask, add 150g of 6mol / L concentrated nitric acid for acid washing, place the round-bottom flask in an oil bath, adjust the temperature to 130℃, and treat the Beta molecular sieve in concentrated nitric acid for 1h. Repeat this process twice. After reflux, cool to room temperature, filter, dry at 80℃ for 8h, and finally calcine in a muffle furnace at 550℃ for 6h to obtain a deeply dealuminized Beta molecular sieve, named Beta-DA. S2. Weigh 0.07g of the Beta-DA molecular sieve prepared in S1 and place it in a 25mL round-bottom flask. Then add manganese nitrate trihydrate and mix. Add deionized water at a mass ratio of 30 times that of the molecular sieve and stir for 3-8 hours. After stirring, remove the water by rotary evaporation at 45℃ and then dry in an oven at 80℃ for 8 hours to obtain Mn50 / Beta molecular sieves with different acid treatment times for preparing Beta support.

[0119] The reaction system and feed amount are the same as in Example 3. The catalytic performance of the catalyst under different acid treatment times is evaluated.

[0120] Comparative Example 23 The difference between this comparative example and Example 1 lies in the different acid treatment time of the Beta molecular sieve support in the preparation method of the supported Mn-based molecular sieve catalyst in this example, including the following steps: S1. Weigh 5g of silica-alumina type Beta molecular sieve into a 250mL round-bottom flask, add 150g of 6mol / L concentrated nitric acid for acid washing, place the round-bottom flask in an oil bath, adjust the temperature to 130℃, and treat the Beta molecular sieve in concentrated nitric acid for 6h. Repeat this process twice. After reflux, cool to room temperature, filter, dry at 80℃ for 8h, and finally calcine in a muffle furnace at 550℃ for 6h to obtain a deeply dealuminized Beta molecular sieve, named Beta-DA. S2. Weigh 0.07g of the Beta-DA molecular sieve prepared in S1 and place it in a 25mL round-bottom flask. Then add manganese nitrate trihydrate and mix. Add deionized water at a mass ratio of 30 times that of the molecular sieve and stir for 3-8 hours. After stirring, remove the water by rotary evaporation at 45℃ and then dry in an oven at 80℃ for 8 hours to obtain Mn50 / Beta molecular sieves with different acid treatment times for preparing Beta support.

[0121] The reaction system and feed amount are the same as in Example 3. The catalytic performance of the catalyst under different acid treatment times is evaluated.

[0122] Table 14 Reaction performance of catalysts with different acid treatment times 1 74.0 3.2 2.4 6 91.5 54.3 49.7 24 99.4 88.1 87.6 As can be seen from Tables 14 and 2, the Mn50 / Beta catalysts prepared by the Beta catalyst support with different acid treatment times (1h, 6h, 12h, and 24h single acid treatment) showed an initial increase in conversion rate followed by stabilization in the catalytic oxidation of 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid. The selectivity and yield increased significantly with acid treatment times of 1h, 6h, and 12h, while the selectivity and yield stabilized with acid treatment time of 24h, ensuring excellent dealumination effect. Therefore, 12h is the preferred single acid treatment time.

[0123] In summary, this invention achieves efficient catalytic oxidation of 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid by loading Mn onto a Beta molecular sieve catalyst via an impregnation method. Comparative examples demonstrate that the preparation method in Example 3 constitutes a specific combination of process parameters and produces a synergistic effect. The experiments show that the conversion rate of 5-hydroxymethylfurfural can reach up to 100%, and the yield of 2,5-furandicarboxylic acid can reach 99.3%.

[0124] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A catalyst for the alkali-free synthesis of 2,5-furandicarboxylic acid, characterized in that: The catalyst is a Mn-supported molecular sieve catalyst Mnx / Beta, wherein x ranges from 20 to 200 based on the Si / Mn molar ratio.

2. The method for preparing the catalyst for the alkali-free synthesis of 2,5-furandicarboxylic acid according to claim 1, characterized in that, Includes the following steps: S1. The silica-alumina type Beta molecular sieve is acid-treated, washed, and dried to obtain a deeply dealuminized Beta molecular sieve; S2. Mix the deeply dealuded Beta molecular sieve obtained in S1 with the Mn-based compound, and add deionized water to mix and stir. S3. The mixture obtained after stirring in S2 is subjected to rotary evaporation to remove the water introduced by impregnation; S4. The sample obtained in S3 is placed in an oven for drying to obtain the Mnx / Beta catalyst.

3. The method for preparing the catalyst for the alkali-free system catalytic synthesis of 2,5-furandicarboxylic acid according to claim 2, characterized in that: The acid treatment in S1 is performed 1 to 3 times; and / or, The reagent used for acid treatment as described in S1 is one or more of concentrated hydrochloric acid, concentrated sulfuric acid, or concentrated nitric acid; and / or, The concentration of the reagent used for acid treatment as described in S1 is 6–14 mol / L; and / or, The mass ratio of the silica-alumina type Beta molecular sieve described in S1 to the reagent used for acid treatment is 1:30-50; The acid treatment in S1 is performed at a temperature of 80-140℃ for 12-24 hours; the drying temperature is 60-100℃ for 8-12 hours.

4. The method for preparing the catalyst for the alkali-free synthesis of 2,5-furandicarboxylic acid according to claim 2, characterized in that: The Mn-based compound in S2 is one or more of manganese nitrate trihydrate or manganese chloride; the molar ratio of SiO2 to the Mn-based compound in the deeply dealuded Beta molecular sieve is 1:0.005 to 0.

05.

5. The method for preparing the catalyst for the alkali-free system catalytic synthesis of 2,5-furandicarboxylic acid according to claim 2, characterized in that: The amount of deionized water added in S2 is 30-50 times the mass of the molecular sieve; the mixing and stirring time is 3-8 hours.

6. The method for preparing the catalyst for the alkali-free synthesis of 2,5-furandicarboxylic acid according to claim 2, characterized in that: In step S3, the rotary evaporation temperature is 35–65°C, the time is 20–50 min, and the rotation speed is 35–65 rpm.

7. The method for preparing the catalyst for the alkali-free synthesis of 2,5-furandicarboxylic acid according to claim 2, characterized in that: The drying temperature in S4 is 60–100°C, and the drying time is 8–24 hours.

8. The application of the catalyst according to claim 1 in the catalytic oxidation of 5-hydroxymethylfurfural to prepare 2,5-furandicarboxylic acid.

9. The application of the catalyst according to claim 8 in the catalytic oxidation of 5-hydroxymethylfurfural to prepare 2,5-furandicarboxylic acid, characterized in that, Includes the following steps: S11. Mix Mnx / Beta catalyst, 5-hydroxymethylfurfural, tert-butyl hydrogen peroxide and solvent and stir until homogeneous. Place the mixture in a sealed reaction vessel and carry out the oxidation reaction under self-pressure conditions. S12. After the oxidation reaction is complete, the reaction system is cooled to room temperature to obtain a crude reaction solution; S13. Perform solid-liquid separation on the crude reaction liquid to remove the Mnx / Beta catalyst solid and collect the filtrate; S14. The filtrate is concentrated, recrystallized, and dried to obtain pure 2,5-furandicarboxylic acid.

10. The application of the catalyst according to claim 9 in the catalytic oxidation of 5-hydroxymethylfurfural to prepare 2,5-furandicarboxylic acid, characterized in that: In step S11, the Mnx / Beta catalyst is 30-90 mg, 5-hydroxymethylfurfural is 0.1-1 mmol, tert-butyl hydroperoxide is 2-14 mmol, and the solvent is 4-6 mL; the solvent is ethyl acetate; and / or, The stirring speed is 600~750 rpm; the reaction temperature is 70~90℃, and the time is 2~12 h.

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