A process for the preparation of 2,5-furandicarboxylic acid by oxidation of 5-hydroxymethylfurfural catalyzed by a heterogeneous catalyst

Abstract

The application provides a method for preparing 2,5-furan dicarboxylic acid by oxidizing 5-hydroxymethylfurfural through a heterogeneous catalyst, which comprises the following steps: heating 5-hydroxymethylfurfural, a neutral carbonate and a manganese-based heterogeneous catalyst in a green solvent in an oxidizing atmosphere to obtain 2,5-furan dicarboxylic acid. Compared with the prior art, the application uses a cheap and easily available neutral carbonate as an additive, can effectively promote the preparation of 2,5-furan dicarboxylic acid by oxidizing 5-hydroxymethylfurfural under mild conditions, avoids the use of medium-strong alkali, greatly reduces the product purification difficulty and production cost, and can effectively prolong the service life of the catalyst, so that the method provided by the application has the advantages of cheap catalyst, mild reaction condition, low energy consumption, high product selectivity, few by-products and the like, is not only high in catalytic efficiency, but also can be recycled, is stable in recycling performance, is suitable for industrial production, and has a very wide application prospect.

Description

Technical Field

[0001] This invention belongs to the field of chemical synthesis technology, and particularly relates to a method for preparing 2,5-furandicarboxylic acid by catalytic oxidation of 5-hydroxymethylfurfural using a heterogeneous catalyst. Background Technology

[0002] Petroleum has been a crucial resource for human development since the 20th century. With dwindling oil reserves and increasing demand for petroleum products, the search for renewable alternatives to petroleum has garnered significant attention in recent years. Among numerous renewable and clean resources, biomass resources are particularly attractive. 5-Hydroxymethylfurfural (HMF or 5-HMF) is an important platform molecule that can be obtained on a large scale from biomass and can be converted into various high-value-added chemicals such as liquid fuels and other products. 5-HMF can be oxidized to 2,5-furandicarboxylic acid, and due to its similar structure and properties to terephthalic acid, it is considered a potential substitute for terephthalic acid as a raw material in polymer materials.

[0003] 2,5-Furfurandicarboxylic acid (FDCA) is stable and can be used to prepare polyesters, polyamides, and polyurethanes. Polyethylene furfurandicarboxylate (PEF) is considered an important polyester material to replace polyethylene terephthalate (PET).

[0004] Currently, the main method for preparing FDCA is the oxidative conversion of 5-hydroxymethylfurfural (5-HMF). However, the preparation process still suffers from problems such as harsh reaction conditions, expensive catalysts, unfriendly reaction conditions, and uncontrollable selectivity. Furthermore, the synthesis of FDCA generally requires moderately to strongly alkaline conditions, which leads to difficulties in product separation and purification in the later stages of the reaction, resulting in a significant increase in costs. Although some literature has reported HMF oxidation reactions under certain conditions, most involve noble metal catalysts and their supported alkaline supports. Moreover, the generated FDCA adheres to the catalyst surface, masking the reaction sites, leading to poor catalyst cycling performance under these conditions. Summary of the Invention

[0005] In view of this, the technical problem to be solved by the present invention is to provide a method for the oxidation of 5-hydroxymethylfurfural to prepare 2,5-furandicarboxylic acid by a heterogeneous catalyst with mild reaction conditions, low energy consumption, and high product selectivity.

[0006] This invention provides a method for preparing 2,5-furandicarboxylic acid by catalytic oxidation of 5-hydroxymethylfurfural using a heterogeneous catalyst, comprising the following steps:

[0007] S) In an oxidizing atmosphere, 5-hydroxymethylfurfural, neutral carbonate, and a manganese-based heterogeneous catalyst are heated in a green solvent to react and yield 2,5-furandicarboxylic acid.

[0008] Preferably, the neutral carbonate is selected from one or more of calcium carbonate, magnesium carbonate, zinc carbonate, and barium carbonate.

[0009] Preferably, the molar ratio of the neutral carbonate to 5-hydroxymethylfurfural is (1-20):1.

[0010] Preferably, the manganese-based heterogeneous catalyst is selected from one or more of MnO2, K-OMS-2 catalyst and metal-doped K-OMS-2 catalyst.

[0011] Preferably, the metal doped in the metal-doped K-OMS-2 catalyst is selected from one or more of Fe, Co, Ni, Al, Mg and V;

[0012] The molar amount of the doped metal in the metal-doped K-OMS-2 catalyst is 5% to 20% of the total molar amount of manganese.

[0013] Preferably, the mass ratio of the manganese-based heterogeneous catalyst to 5-hydroxymethylfurfural is 1:(1-100).

[0014] Preferably, the oxidizing atmosphere is air and / or oxygen;

[0015] The pressure of the oxidizing atmosphere is 0.1–60 MPa.

[0016] Preferably, the green solvent is water; the mass ratio of the green solvent to 5-hydroxymethylfurfural is 1:(0.001~0.1).

[0017] Preferably, the temperature of the heating reaction is 60℃ to 200℃; and the heating reaction time is 0.5 to 15 hours.

[0018] Preferably, after heating and reacting, the mixture is filtered, and the filter cake is used as a manganese-based heterogeneous catalyst to repeat the reaction in step S).

[0019] This invention provides a method for the oxidation of 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid using a heterogeneous catalyst, comprising the following steps: 5-hydroxymethylfurfural, a neutral carbonate, and a manganese-based heterogeneous catalyst are heated and reacted in a green solvent under an oxidizing atmosphere to obtain 2,5-furandicarboxylic acid. Compared with existing technologies, this invention uses inexpensive and readily available neutral carbonate as an additive, enabling effective promotion of the oxidation of 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid under mild conditions. This avoids the use of strong bases, significantly reducing product purification difficulty and production costs, and effectively extends catalyst life. The method provided by this invention has advantages such as inexpensive catalyst, mild reaction conditions, low energy consumption, high product selectivity, and few byproducts. It not only has high catalytic efficiency but also allows for catalyst recycling with stable performance, making it suitable for industrial production and possessing very broad application prospects. Attached Figure Description

[0020] Figure 1 Liquid chromatography of the reaction liquid product obtained in Example 16 of this invention;

[0021] Figure 2 The image shows the 1H NMR spectrum of 2,5-furandicarboxylic acid obtained in Example 16 of this invention. Detailed Implementation

[0022] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0023] This invention provides a method for preparing 2,5-furandicarboxylic acid by catalytic oxidation of 5-hydroxymethylfurfural using a heterogeneous catalyst, comprising the following steps: heating 5-hydroxymethylfurfural, neutral carbonate, and a manganese-based heterogeneous catalyst in a green solvent under an oxidizing atmosphere to obtain 2,5-furandicarboxylic acid.

[0024] This invention utilizes inexpensive and readily available neutral carbonates as additives to effectively promote the oxidation of 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid under mild conditions. This avoids the use of strong bases, significantly reducing the difficulty of product purification and production costs. It also effectively extends the catalyst's lifespan. The method provided by this invention has advantages such as inexpensive catalyst, mild reaction conditions, low energy consumption, high product selectivity, and few byproducts. Not only is the catalytic efficiency high, but the catalyst can also be recycled with stable performance, making it suitable for industrial production and possessing very broad application prospects.

[0025] In this invention, there are no special restrictions on the source of any raw materials; commercially available materials are sufficient.

[0026] In this invention, the neutral carbonate can be any neutral carbonate well known to those skilled in the art, and there are no special limitations. In this invention, it is preferred to include, but not limited to, one or more of calcium carbonate, magnesium carbonate, zinc carbonate and barium carbonate.

[0027] In this invention, the manganese-based heterogeneous catalyst is preferably one or more of MnO2, K-OMS-2 catalyst, and metal-doped K-OMS-2 catalyst; the metal doped in the metal-doped K-OMS-2 catalyst is preferably one or more of Fe, Co, Ni, Al, Mg, and V; the molar amount of the metal doped in the metal-doped K-OMS-2 catalyst is preferably 5% to 20% of the total molar amount of manganese; in the embodiments provided by this invention, the molar amount of the metal doped in the metal-doped K-OMS-2 catalyst is specifically 5%, 10%, 15%, or 20% of the total molar amount of manganese; the manganese-based heterogeneous catalyst can be prepared according to methods well known to those skilled in the art and is not particularly limited. In this invention, the K-OMS-2 catalyst is preferably prepared by the following method: mixing potassium permanganate solution and manganese sulfate solution, and adding concentrated... After adjusting the pH value with nitric acid, the reaction is heated to obtain the K-OMS-2 catalyst. The molar ratio of potassium permanganate to manganese sulfate is preferably 1:(1-2), more preferably 1:(1.3-1.8), and even more preferably 1:(1.3-1.5). The molar concentration of concentrated nitric acid is preferably 1-6 mol / L. The pH value is preferably adjusted to 1-7, more preferably 2-5. The heating temperature is preferably 90℃-150℃, more preferably 100℃-120℃, and even more preferably 110℃. The heating time is preferably 12-48 h, more preferably 18-24 h. After the heating reaction, the catalyst is preferably filtered, washed, and dried to obtain the K-OMS-2 catalyst. The washing is preferably performed using deionized water. The drying temperature is preferably 100℃-110℃, more preferably 105℃. The drying time is preferably 8-15 h, more preferably 10-12 h. The preparation method of the metal-doped K-OMS-2 catalyst is similar to that of the K-OMS-2 catalyst, except that a salt solution of the metal to be doped is added after adjusting the pH value.

[0028] In an oxidizing atmosphere, 5-hydroxymethylfurfural, neutral carbonate, and a manganese-based heterogeneous catalyst are heated and reacted in a green solvent. In this invention, it is preferable to first mix 5-hydroxymethylfurfural, the manganese-based heterogeneous catalyst, the neutral carbonate, and the green solvent, then introduce an oxidizing atmosphere and heat the reaction. The mass ratio of the manganese-based heterogeneous catalyst to 5-hydroxymethylfurfural is preferably 1:(1-100), preferably 1:(1-50), even more preferably 1:(1-20), even more preferably 1:(1-10), even more preferably 1:(1-5), and most preferably 1:(1.2). 6~2.52); the molar ratio of the neutral carbonate to 5-hydroxymethylfurfural is preferably (1~20):1, more preferably (1~10):1, even more preferably (1~5):1, even more preferably (1~4):1, and most preferably (1~2):1; the oxidizing atmosphere can be any oxidizing atmosphere known to those skilled in the art, and there are no special limitations. In this invention, air and / or oxygen are preferred; the pressure of the oxidizing atmosphere is preferably 0.1~60MPa, more preferably 0.1~10MPa, even more preferably 0.1~5MPa, and even more preferably 0.5~ The pressure of the oxidizing atmosphere is 3 MPa, most preferably 1-3 MPa; in the embodiments provided by the present invention, the pressure of the oxidizing atmosphere is specifically 2 MPa, 1 MPa, 4 MPa or 0.1 MPa; the temperature of the heating reaction is preferably 60℃-200℃, more preferably 80℃-200℃, and even more preferably 100℃-200℃; in the embodiments provided by the present invention, the temperature of the heating reaction is specifically 100℃, 150℃ or 200℃; the time of the heating reaction is preferably 0.5-15 h, more preferably 3-15 h, and even more preferably 6-12 h; the heating reaction... The reaction should preferably be carried out under stirring conditions; the stirring speed is preferably 100-800 r / min, more preferably 300-800 r / min, even more preferably 400-600 r / min, and most preferably 500 r / min; the heating reaction is preferably carried out in a reactor, in which 5-hydroxymethylfurfural reacts with an oxygen source in the presence of a heterogeneous catalyst and a neutral additive to hydrogenate 2,5-furandicarboxylic acid in high yield; the reactor should be capable of realizing the catalytic oxidation reaction of 5-hydroxymethylfurfural in an oxidizing atmosphere, such as a reaction vessel or a high-pressure reaction vessel.

[0029] After heating and reacting, it is preferable to filter out the catalyst and unreacted neutral additives. After acidifying the filtrate, FDCA can be obtained by filtration. The catalyst and neutral additive filter cake can be directly added to the next reaction. Since the filtrate is neutral, only an equivalent amount of acid is needed for acidification. Compared with the use of conventional alkali, neutral carbonate additives can significantly reduce the amount of acid used, which is in line with the concept of green chemistry.

[0030] This invention uses 5-hydroxymethylfurfural as a raw material to efficiently obtain 2,5-furandicarboxylic acid under the action of a heterogeneous catalyst and a neutral additive. The catalyst has low oxygen pressure, abundant sources, is commercially available or easily synthesized, has high catalytic efficiency, and the catalyst can be reused. Furthermore, this invention uses water as a reaction solvent, which is green and environmentally friendly. Moreover, this invention uses a neutral additive to replace the alkaline environment commonly used in the reaction, which significantly reduces the requirements and costs of equipment.

[0031] To further illustrate the present invention, the following describes in detail, with reference to embodiments, a method for preparing 2,5-furandicarboxylic acid by catalytic oxidation of 5-hydroxymethylfurfural using a heterogeneous catalyst.

[0032] All reagents used in the following examples are commercially available.

[0033] Example 1: Preparation of heterogeneous catalyst K-OMS-2

[0034] A potassium permanganate solution (225 mL, 0.4 M) was added to a mixed solution of hydrated manganese sulfate (67.5 mL, 1.75 M) and concentrated nitric acid (6.8 mL). The resulting dark brown slurry was then heated at 110 °C. After reflux heating at 110 °C for 24 h, the slurry was filtered and washed with deionized water to remove the solvent. The resulting K-OMS-2 catalyst was obtained after drying in an oven at 105 °C for 12 h.

[0035] Example 2: Preparation of heterogeneous catalyst metal-doped K-OMS-2

[0036] Potassium permanganate solution (225 mL, 0.4 M) was added to a mixed solution of hydrated manganese sulfate aqueous solution (67.5 mL, 1.75 M) and concentrated nitric acid (6.8 mL). Then, 5%, 10%, 15%, and 20% molar amounts of Fe(NO3)3, Co(NO3)2, Ni(NO3)2, Al(NO3)3, Mg(NO3)2, and NaVO3 were added. The resulting dark brown slurry was then heated at 110 °C. After reflux heating at 110 °C for 24 h, the slurry was filtered and washed with deionized water to remove the solvent. After drying in a drying oven at 105 °C for 12 h, the heterogeneous catalyst metal-doped K-OMS-2 was obtained, designated as Fe-OMS-2, Co-OMS-2, Ni-OMS-2, Al-OMS-2, Mg-OMS-2, and V-OMS-2.

[0037] Examples 3-15

[0038] The heterogeneous catalyst was prepared according to the method of Example 2. The difference from Example 2 is that different types and amounts of metal ions were used to obtain doped heterogeneous catalysts with different metal types and metal contents.

[0039] Example 16

[0040] 126 mg of 5-hydroxymethylfurfural and 100 mg of K-OMS-2 were added to a 50 mL reactor, followed by calcium carbonate (one equivalent of 5-hydroxymethylfurfural) and 10 mL of water. After purging with oxygen five times, the mixture was heated to 150 °C under stirring at 500 r / min and kept at an oxygen pressure of 2 MPa for 12 h. The mixture was stirred continuously during the reaction and cooled to room temperature to obtain a reaction solution containing 2,5-furandicarboxylic acid.

[0041] The obtained reaction solution was sampled and diluted, and determined by high-performance liquid chromatography (HLPC). The HLPC analysis results from three repeated experiments showed that the FDCA yield was 67% and the conversion rate was 93%. The liquid product was analyzed using a Waters e2695 Infinity HPLC system equipped with a UV detector and a C18 column (250 mm × 4.6 mm × 5 μm). The mobile phase was a diluted CF3COOH solution (5 mM), and the flow rate was 0.6 mL / min. HLPC results are as follows: Figure 1 As shown.

[0042] The post-reaction processing steps are as follows: filter the reaction solution to remove the catalyst and unreacted calcium carbonate, adjust the pH of the liquid to 1, and a large amount of white solid will precipitate out. Filter the solution to obtain the white solid, which is 2,5-furandicarboxylic acid (FDCA).

[0043] The 2,5-furandicarboxylic acid obtained in Example 16 was analyzed using nuclear magnetic resonance (NMR), and its proton NMR spectrum was obtained, as shown below. Figure 2 As shown.

[0044] Example 17

[0045] 126 mg of 5-hydroxymethylfurfural and 100 mg of K-OMS-2 were added to a 50 mL reactor, followed by calcium carbonate in a molar ratio of 2 moles of 5-hydroxymethylfurfural, and finally 10 mL of water. After purging with oxygen five times, the mixture was heated to 150 °C under stirring at 500 rpm and held at an oxygen pressure of 2 MPa for 12 h with continuous stirring. After cooling to room temperature, a reaction solution containing 2,5-furandicarboxylic acid was obtained.

[0046] The obtained reaction solution was sampled and diluted, and determined by liquid chromatography (HLPC). The results of HLPC analysis of three repeated experiments showed that the FDCA yield was 72% and the conversion rate was 94%.

[0047] Example 18

[0048] 126 mg of 5-hydroxymethylfurfural and 100 mg of K-OMS-2 were added to a 50 mL reactor, followed by calcium carbonate in a molar ratio of 2 to 5-hydroxymethylfurfural, and finally 10 mL of water. After purging with oxygen five times, the mixture was heated to 100 °C under stirring at 500 rpm and held at an oxygen pressure of 2 MPa for 12 h with continuous stirring. After cooling to room temperature, a reaction solution containing 2,5-furandicarboxylic acid was obtained.

[0049] The obtained reaction solution was sampled and diluted, and determined by liquid chromatography (HLPC). The results of HLPC analysis of three repeated experiments showed that the FDCA yield was 34% and the conversion rate was 87%.

[0050] Example 19

[0051] 126 mg of 5-hydroxymethylfurfural and 200 mg of K-OMS-2 were added to a 50 mL reactor, followed by calcium carbonate in an amount equal to 1 molar of 5-hydroxymethylfurfural, and finally 10 mL of water. After purging with oxygen five times, the mixture was heated to 150 °C under stirring at 500 rpm and held at an oxygen pressure of 1 MPa for 12 h with continuous stirring. After cooling to room temperature, a reaction solution containing 2,5-furandicarboxylic acid was obtained.

[0052] The obtained reaction solution was sampled and diluted, and determined by liquid chromatography (HLPC). The results of HLPC analysis of three repeated experiments showed that the FDCA yield was 70% and the conversion rate was 93%.

[0053] Example 20

[0054] 126 mg of 5-hydroxymethylfurfural and 100 mg of K-OMS-2 were added to a 50 mL reactor, followed by calcium carbonate in a molar ratio equal to that of 5-hydroxymethylfurfural, and finally 10 mL of water. After purging with oxygen five times, the mixture was heated to 150 °C under stirring at 500 rpm and held at an oxygen pressure of 1 MPa for 6 h with continuous stirring. After cooling to room temperature, a reaction solution containing 2,5-furandicarboxylic acid was obtained.

[0055] The obtained reaction solution was sampled and diluted, and determined by liquid chromatography (HLPC). The results of HLPC analysis of three repeated experiments showed that the FDCA yield was 38% and the conversion rate was 80%.

[0056] Example 21

[0057] 126 mg of 5-hydroxymethylfurfural and 100 mg of K-OMS-2 were added to a 50 mL reactor, followed by calcium carbonate in a molar ratio equal to that of 5-hydroxymethylfurfural, and finally 10 mL of water. After purging with oxygen five times, the mixture was heated to 150 °C under stirring at 500 rpm and held at an oxygen pressure of 4 MPa for 6 hours with continuous stirring. After cooling to room temperature, a reaction solution containing 2,5-furandicarboxylic acid was obtained.

[0058] The obtained reaction solution was sampled and diluted, and determined by liquid chromatography (HLPC). The results of HLPC analysis of three repeated experiments showed that the FDCA yield was 70% and the conversion rate was 92%.

[0059] Example 22

[0060] 126 mg of 5-hydroxymethylfurfural and 100 mg of K-OMS-2 were added to a 50 mL reactor, followed by calcium carbonate in a molar ratio equal to that of 5-hydroxymethylfurfural, and finally 10 mL of water. After purging with oxygen five times, the mixture was heated to 200 °C under stirring at 500 rpm and held at an oxygen pressure of 1 MPa for 6 h with continuous stirring. After cooling to room temperature, a reaction solution containing 2,5-furandicarboxylic acid was obtained.

[0061] The obtained reaction solution was sampled and diluted, and determined by liquid chromatography (HLPC). The results of HLPC analysis of three repeated experiments showed that the FDCA yield was 43% and the conversion rate was 99%.

[0062] Example 23

[0063] 126 mg of 5-hydroxymethylfurfural and 50 mg of K-OMS-2 were added to a 50 mL reactor, followed by calcium carbonate in a molar ratio equal to that of 5-hydroxymethylfurfural, and finally 10 mL of water. After purging with oxygen five times, the mixture was heated to 150 °C under stirring at 500 rpm and held at an oxygen pressure of 1 MPa for 6 hours with continuous stirring. After cooling to room temperature, a reaction solution containing 2,5-furandicarboxylic acid was obtained.

[0064] The obtained reaction solution was sampled and diluted, and determined by liquid chromatography (HLPC). The results of HLPC analysis of three repeated experiments showed that the FDCA yield was 53% and the conversion rate was 81%.

[0065] Example 24

[0066] 126 mg of 5-hydroxymethylfurfural and 100 mg of K-OMS-2 were added to a 50 mL reactor, followed by calcium carbonate in a molar ratio equal to that of 5-hydroxymethylfurfural, and finally 10 mL of water. After purging with oxygen five times, the mixture was heated to 150 °C under stirring at 500 rpm and an oxygen pressure of 0.1 MPa, and the reaction was maintained at this temperature for 6 h with continuous stirring. After cooling to room temperature, a reaction solution containing 2,5-furandicarboxylic acid was obtained.

[0067] The obtained reaction solution was sampled and diluted, and determined by liquid chromatography (HLPC). The results of HLPC analysis of three repeated experiments showed that the FDCA yield was 25% and the conversion rate was 67%.

[0068] Example 25

[0069] 126 mg of 5-hydroxymethylfurfural and 100 mg of 10% Co-OMS-2 were added to a 50 mL reactor, followed by calcium carbonate in an amount equal to the molar volume of 5-hydroxymethylfurfural, and finally 10 mL of water. After purging with oxygen five times, the mixture was heated to 150 °C under stirring at 500 rpm and held at an oxygen pressure of 2 MPa for 12 h with continuous stirring. After cooling to room temperature, a reaction solution containing 2,5-furandicarboxylic acid was obtained.

[0070] The obtained reaction solution was sampled and diluted, and determined by liquid chromatography (HLPC). The results of HLPC analysis of three repeated experiments showed that the FDCA yield was 95% and the conversion rate was 99%.

[0071] Example 26

[0072] 126 mg of 5-hydroxymethylfurfural and 100 mg of 10% Co-OMS-2 were added to a 50 mL reactor, followed by calcium carbonate in a molar ratio of 2 moles of 5-hydroxymethylfurfural, and finally 10 mL of water. After purging with oxygen five times, the mixture was heated to 150 °C under stirring at 500 rpm and held at an oxygen pressure of 2 MPa for 12 h with continuous stirring. After cooling to room temperature, a reaction solution containing 2,5-furandicarboxylic acid was obtained.

[0073] The obtained reaction solution was sampled and diluted, and determined by liquid chromatography (HLPC). The results of HLPC analysis of three repeated experiments showed that the FDCA yield was 96% and the conversion rate was 99%.

[0074] Example 27

[0075] 126 mg of 5-hydroxymethylfurfural and 100 mg of 10% Co-OMS-2 were added to a 50 mL reactor, followed by calcium carbonate in a molar ratio equal to that of 5-hydroxymethylfurfural, and finally 10 mL of water. After purging with oxygen five times, the mixture was heated to 100 °C under stirring at 500 rpm and held at an oxygen pressure of 2 MPa for 12 h with continuous stirring. After cooling to room temperature, a reaction solution containing 2,5-furandicarboxylic acid was obtained.

[0076] The obtained reaction solution was sampled and diluted, and determined by liquid chromatography (HLPC). The results of HLPC analysis of three repeated experiments showed that the FDCA yield was 56% and the conversion rate was 82%.

[0077] Example 28

[0078] 126 mg of 5-hydroxymethylfurfural and 100 mg of 10% Co-OMS-2 were added to a 50 mL reactor, followed by calcium carbonate in a molar ratio equal to that of 5-hydroxymethylfurfural, and finally 10 mL of water. After purging with oxygen five times, the mixture was heated to 150 °C under stirring at 500 rpm and held at an oxygen pressure of 2 MPa for 6 h with continuous stirring. After cooling to room temperature, a reaction solution containing 2,5-furandicarboxylic acid was obtained.

[0079] The obtained reaction solution was sampled and diluted, and determined by liquid chromatography (HLPC). The results of HLPC analysis of three repeated experiments showed that the FDCA yield was 62% and the conversion rate was 91%.

[0080] Example 29

[0081] 126 mg of 5-hydroxymethylfurfural and 100 mg of 5% Co-OMS-2 were added to a 50 mL reactor, followed by calcium carbonate in a molar ratio equal to that of 5-hydroxymethylfurfural, and finally 10 mL of water. After purging with oxygen five times, the mixture was heated to 150 °C under stirring at 500 rpm and held at an oxygen pressure of 2 MPa for 12 h with continuous stirring. After cooling to room temperature, a reaction solution containing 2,5-furandicarboxylic acid was obtained.

[0082] The obtained reaction solution was sampled and diluted, and determined by liquid chromatography (HLPC). The results of HLPC analysis of three repeated experiments showed that the FDCA yield was 82% and the conversion rate was 99%.

[0083] Example 30

[0084] 126 mg of 5-hydroxymethylfurfural and 100 mg of 15% Co-OMS-2 were added to a 50 mL reactor, followed by calcium carbonate in a molar ratio equal to that of 5-hydroxymethylfurfural, and finally 10 mL of water. After purging with oxygen five times, the mixture was heated to 150 °C under stirring at 500 rpm and held at an oxygen pressure of 2 MPa for 12 h with continuous stirring. After cooling to room temperature, a reaction solution containing 2,5-furandicarboxylic acid was obtained.

[0085] The obtained reaction solution was sampled and diluted, and determined by liquid chromatography (HLPC). The results of HLPC analysis of three repeated experiments showed that the FDCA yield was 95% and the conversion rate was 99%.

[0086] Example 31

[0087] 126 mg of 5-hydroxymethylfurfural and 100 mg of 20% Co-OMS-2 were added to a 50 mL reactor, followed by calcium carbonate in a molar ratio equal to that of 5-hydroxymethylfurfural, and finally 10 mL of water. After purging with oxygen five times, the mixture was heated to 150 °C under stirring at 500 rpm and held at an oxygen pressure of 2 MPa for 12 h with continuous stirring. After cooling to room temperature, a reaction solution containing 2,5-furandicarboxylic acid was obtained.

[0088] The obtained reaction solution was sampled and diluted, and determined by liquid chromatography (HLPC). The results of HLPC analysis of three repeated experiments showed that the FDCA yield was 95% and the conversion rate was 99%.

[0089] Example 32

[0090] 126 mg of 5-hydroxymethylfurfural and 100 mg of 10% Fe-OMS-2 were added to a 50 mL reactor, followed by calcium carbonate in an amount equal to 1 molar of 5-hydroxymethylfurfural, and finally 10 mL of water. After purging with oxygen five times, the mixture was heated to 150 °C under stirring at 500 rpm and held at an oxygen pressure of 2 MPa for 12 h with continuous stirring. After cooling to room temperature, a reaction solution containing 2,5-furandicarboxylic acid was obtained.

[0091] The obtained reaction solution was sampled and diluted, and determined by liquid chromatography (HLPC). The results of HLPC analysis of three repeated experiments showed that the FDCA yield was 69% and the conversion rate was 84%.

[0092] Example 33

[0093] 126 mg of 5-hydroxymethylfurfural and 100 mg of 10% Ni-OMS-2 were added to a 50 mL reactor, followed by calcium carbonate in a molar ratio equal to that of 5-hydroxymethylfurfural, and finally 10 mL of water. After purging with oxygen five times, the mixture was heated to 150 °C under stirring at 500 rpm and held at an oxygen pressure of 2 MPa for 12 h with continuous stirring. After cooling to room temperature, a reaction solution containing 2,5-furandicarboxylic acid was obtained.

[0094] The obtained reaction solution was sampled and diluted, and determined by liquid chromatography (HLPC). The results of HLPC analysis of three repeated experiments showed that the FDCA yield was 73% and the conversion rate was 90%.

[0095] Example 34

[0096] 126 mg of 5-hydroxymethylfurfural and 100 mg of 10% Al-OMS-2 were added to a 50 mL reactor, followed by calcium carbonate in an amount equal to 1 molar of 5-hydroxymethylfurfural, and finally 10 mL of water. After purging with oxygen five times, the mixture was heated to 150 °C under stirring at 500 rpm and held at an oxygen pressure of 2 MPa for 12 h with continuous stirring. After cooling to room temperature, a reaction solution containing 2,5-furandicarboxylic acid was obtained.

[0097] The obtained reaction solution was sampled and diluted, and determined by liquid chromatography (HLPC). The results of HLPC analysis of three repeated experiments showed that the FDCA yield was 70% and the conversion rate was 91%.

[0098] Example 35

[0099] 126 mg of 5-hydroxymethylfurfural and 100 mg of 10% W-OMS-2 were added to a 50 mL reactor, followed by calcium carbonate in an amount equal to 1 molar of 5-hydroxymethylfurfural, and finally 10 mL of water. After purging with oxygen five times, the mixture was heated to 150 °C under stirring at 500 rpm and held at an oxygen pressure of 2 MPa for 12 h with continuous stirring. After cooling to room temperature, a reaction solution containing 2,5-furandicarboxylic acid was obtained.

[0100] The obtained reaction solution was sampled and diluted, and determined by liquid chromatography (HLPC). The results of HLPC analysis of three repeated experiments showed that the FDCA yield was 77% and the conversion rate was 99%.

[0101] Example 36

[0102] 126 mg of 5-hydroxymethylfurfural and 100 mg of 10% Mg-OMS-2 were added to a 50 mL reactor, followed by calcium carbonate (one equivalent of 5-hydroxymethylfurfural) and 10 mL of water. After purging with oxygen five times, the mixture was heated to 150 °C with stirring at 500 rpm and held at an oxygen pressure of 2 MPa for 12 h with continuous stirring. After cooling to room temperature, a reaction solution containing 2,5-furandicarboxylic acid was obtained.

[0103] The obtained reaction solution was sampled and diluted, and determined by liquid chromatography (HLPC). The results of HLPC analysis of three repeated experiments showed that the FDCA yield was 65% and the conversion rate was 86%.

[0104] Example 37

[0105] 126 mg of 5-hydroxymethylfurfural and 100 mg of 10% V-OMS-2 were added to a 50 mL reactor, followed by calcium carbonate (one equivalent of 5-hydroxymethylfurfural) and 10 mL of water. After purging with oxygen five times, the mixture was heated to 150 °C with stirring at 500 rpm and an oxygen pressure of 2 MPa, and the reaction was maintained at this temperature for 12 h with continuous stirring. After cooling to room temperature, a reaction solution containing 2,5-furandicarboxylic acid was obtained.

[0106] The obtained reaction solution was sampled and diluted, and determined by liquid chromatography (HLPC). The results of HLPC analysis of three repeated experiments showed that the FDCA yield was 72% and the conversion rate was 88%.

[0107] Example 38

[0108] 126 mg of 5-hydroxymethylfurfural and 100 mg of 10% Co-OMS-2 were added to a 50 mL reactor, followed by calcium carbonate (2 equivalents of 5-hydroxymethylfurfural) and 10 mL of water. After purging with oxygen five times, the mixture was heated to 150 °C and held at an oxygen pressure of 2 MPa with stirring at 500 rpm for 12 h, with continuous stirring throughout the reaction. After cooling to room temperature, a reaction solution containing 2,5-furandicarboxylic acid was obtained.

[0109] The reaction solution was filtered, and the filter cake was placed in a reaction vessel with 1 equivalent of calcium carbonate added. The reaction was carried out under the same conditions. The FDCA yield was tested, and the FDCA conversion was 100% after 10 cycles, with yields of 96%, 95%, 95%, 94%, 95%, 93%, 93%, 91%, 92%, and 92%, respectively.

[0110] The preferred reaction conditions in this invention are as follows: reaction temperature of 100-200℃, neutral additive molar amount of 1-4 times HMF, hydrogen pressure of 0.1-4 MPa, and reaction time of 6-12 h; 2,5-furandicarboxylic acid product can be prepared with high conversion rate and yield.

[0111] The heterogeneous catalyst provided by this invention efficiently catalyzes the reaction of 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid, exhibiting high catalytic activity and selectivity. The catalyst used in this invention is simple, environmentally friendly, and highly efficient, better meeting the needs of industrial applications. More importantly, this method avoids the use of alkaline auxiliaries such as sodium carbonate and sodium hydroxide, greatly reducing the requirements for reaction equipment. Furthermore, the use of inexpensive calcium carbonate as a substitute further reduces costs. This method is suitable for industrial production and has a very broad application prospect.

[0112] The above embodiments are merely illustrative of the method and core ideas of this invention. It should be noted that those skilled in the art can make various improvements and modifications to this invention without departing from its principles, and these improvements and modifications also fall within the scope of protection of the claims of this invention.

Claims

1. A process for the oxidation of 5-hydroxymethylfurfural to 2,5-furan dicarboxylic acid catalyzed by a heterogeneous catalyst, characterized in that, The method comprises the following steps: S) heating 5-hydroxymethylfurfural, a neutral carbonate and a manganese-based heterogeneous catalyst in a green solvent in an oxidative atmosphere to obtain 2,5-furan dicarboxylic acid; The green solvent is water; The neutral carbonate is selected from calcium carbonate; The manganese-based heterogeneous catalyst is selected from one or more of K-OMS-2 catalyst and metal-doped K-OMS-2 catalyst; The metal-doped K-OMS-2 catalyst is doped with one or more of Fe, Co, Ni, Al, Mg and V; The molar amount of the metal doped in the metal-doped K-OMS-2 catalyst is 5% to 20% of the total molar amount of manganese elements; The heating reaction temperature is 100°C to 200°C; The pressure of the oxidative atmosphere is 1 to 4 MPa.

2. The method of claim 1, wherein, The molar ratio of the neutral carbonate to 5-hydroxymethylfurfural is (1-20):

1.

3. The method of claim 1, wherein, The mass ratio of the manganese-based heterogeneous catalyst to 5-hydroxymethylfurfural is 1:(1-100).

4. The method of claim 1, wherein, The oxidative atmosphere is air and / or oxygen.

5. The method of claim 1, wherein, The mass ratio of the green solvent to 5-hydroxymethylfurfural is 1:(0.001-0.1).

6. The method of claim 1, wherein, The heating reaction time is 0.5 to 15 h.

7. The method of claim 1, wherein, After the heating reaction, filtration is performed, and the filter cake is used as the manganese-based heterogeneous catalyst for the reaction of step S).

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