Method for preparing furandicarboxylic acid through catalytic oxidation of 5-hydroxymethylfurfural by using imidazole-based porous organic matter polymer catalyst

Abstract

The invention discloses a method for preparing furandicarboxylic acid through efficient catalytic oxidation of 5-hydroxymethylfurfural based on an imidazolyl porous organic polymer catalyst. The method comprises the following steps: firstly, rapidly synthesizing an imidazolyl porous organic polymer as a functional carrier under the assistance of an acidic ionic liquid catalyst and a cross-linking agent, then loading an active metal salt component, and carrying out high-temperature reduction treatment to obtain the metal catalyst with a porous structure. The catalyst has excellent catalytic performance in the oxidation reaction of 5-hydroxymethylfurfural, and the conversion rate and the selectivity both reach 85% or above. Compared with a traditional heterogeneous catalytic system, the catalyst is high in thermal stability, can maintain structural integrity under reaction conditions, can effectively inhibit a metal component dissolution phenomenon, is long in service life, can obtain high conversion rate and selectivity without additionally adding an alkali auxiliary agent, can effectively avoid equipment damage and subsequent maintenance, and is suitable for industrial production. Excellent industrial application prospects are shown.

Description

Technical Field

[0001] This invention relates to the field of chemical engineering, specifically to a method for preparing furanyl dicarboxylic acid by catalytic oxidation of 5-hydroxymethylfurfural using an imidazole-based porous organic polymer catalyst. Background Technology

[0002] 5-Hydroxymethylfurfural (5-HMF), serving as a pivotal platform molecule connecting biomass resources and fine chemicals, can be directionally synthesized through a triple synergistic catalytic mechanism of acid-catalyzed hydrolysis-isomerization-dehydration of biomass components such as cellulose and hemicellulose. Its selective oxidation product, 2,5-furandicarboxylic acid (FDCA), possesses both a rigid furan ring skeleton and an active carboxylic acid functional group, making it a key monomer for constructing bio-based polyethylene furanate (PEF). This bio-based polyester shares similar molecular topology with petroleum-based polyethylene terephthalate (PET), demonstrating significant potential to replace traditional petrochemical products in the packaging materials field. Currently, global annual PET production reaches 70 million tons; even if FDCA only partially replaces PTA, it will represent a huge emerging market. Therefore, developing efficient 5-HMF oxidation technology for FDCA preparation is of great significance for promoting the entire PEF industry chain.

[0003] Currently, the main technical pathways for the selective oxidation of 5-HMF to FDCA include three major systems: stoichiometric oxidation, homogeneous catalysis, and heterogeneous catalysis. In stoichiometric oxidation, strong oxidizing agents such as KMnO4, N2O4, and concentrated nitric acid are commonly used. While these systems are simple, they have significant drawbacks: strong acid / oxidizing media cause severe corrosion to reaction equipment, and reaction byproducts include heavy metal ions and nitrogen oxides, which are environmental pollutants and do not meet the requirements of green chemistry development, thus severely limiting their industrial application. In the field of homogeneous catalysis, catalytic systems composed of Co(OAc)2Mn(OAc)2Br- and Co(OAc)2Zn(OAc)2Br- achieve the oxidative conversion of HMF in molecular oxygen or air atmospheres. However, these homogeneous catalytic systems face multiple technical bottlenecks: the yield of the target product FDCA is generally low; complex metal salt separation processes are required after the reaction; bromide additives cause serious environmental pollution problems; and bromine-containing acidic waste liquid corrodes the reaction vessel materials. Compared to the aforementioned technical approaches, heterogeneous catalytic systems exhibit significant technical advantages: among them, supported heterogeneous catalysis has advantages such as easy product separation, reusable catalysts, and high catalytic efficiency, but it often faces problems such as varying degrees of loss of active components and insufficient activity of active centers. The selection of the support is crucial to solving these problems.

[0004] Imidazole-based porous organic polymers, as catalyst supports, possess advantages such as high specific surface area, unique nitrogen coordination structure, and π-conjugated framework. Their uniformly distributed nitrogen atoms activate the active sites of metal oxides and reduce the loss of active components during the reaction, thereby achieving atomic-level dispersion and stabilization of the metal active sites. However, the current synthesis process of imidazole-based porous organic polymers is time-consuming, typically requiring 1-3 days to complete. Therefore, exploring a method for the rapid and efficient preparation of imidazole-based support materials is particularly crucial and urgent. Summary of the Invention

[0005] To address the technical challenge of efficiently catalytically oxidizing 5-hydroxymethylfurfural to furanyldicarboxylic acid, this invention rapidly and efficiently prepares an imidazole-based porous organic polymer. Active components such as palladium and platinum are then supported on this polymer framework via a wet impregnation method. Following drying and calcination, a supported metal catalyst with high activity and stability is obtained. Under the action of this catalyst, the conversion rate of 5-hydroxymethylfurfural and the selectivity for furanyldicarboxylic acid can both reach over 85%.

[0006] According to the present invention, the imidazole-based porous organic polymer-supported metal catalyst can be prepared by the following method, comprising the following steps: (1) Synthesize imidazole-based porous organic polymer carriers with the assistance of crosslinking agents.

[0007] (2) The metal catalyst supported by imidazole porous organic polymer is obtained by loading active metal salt and reducing it at high temperature.

[0008] (3) Under the action of a catalyst, molecular oxygen is used as an oxidant to efficiently catalyze the oxidation of 5-hydroxymethylfurfural to furanyl dicarboxylic acid.

[0009] According to the present invention, the method uses an imidazole-based porous organic polymer as a support, and obtains a metal catalyst supported on the imidazole-based porous organic polymer by post-loading an active metal salt component and reducing it at high temperature.

[0010] According to the present invention, it is characterized by being prepared according to the following steps: Carbonyl monomers and amino monomers were added to an organic solvent, along with a catalyst. The mixture was then subjected to an ultrasonic-microwave reaction at 130-180℃ for 6-12 hours under anaerobic conditions with the aid of a crosslinking agent. After the reaction was completed, imidazole-based porous organic polymers were obtained by filtration, washing, Soxhlet extraction, and vacuum drying.

[0011] According to the present invention, the organic solvent is one or more of 1,4-dioxane, mesitylene, n-butanol, N,N-dimethylformamide, acetonitrile, and tetrahydrofuran.

[0012] According to the present invention, the carbonyl monomer is pyrene-4,5,9,10-tetraone or 2,7-dibromo-pyrene-4,5,9,10-tetraone.

[0013] According to the present invention, the amino monomer is 1,2,4,5-phenyltetramine hydrochloride or [1,1'-biphenyl]-3,3',4,4'-tetramine.

[0014] According to the present invention, the catalyst is an acidic ionic liquid catalyst, including [BMIM][B(HSO4)4], [OMIM][B(HSO4)4], B(HSO4)3, [BSO3Py]HSO4 or [BSO3Py]ClO4.

[0015] According to the present invention, the crosslinking agent is one or more of formaldehyde, glyoxal, glutaraldehyde and paraformaldehyde.

[0016] According to the present invention, the molar mass ratio of the carbonyl monomer to the amino monomer is 1:1, and the crosslinking agent accounts for 0.1-5% of the molar amount of the aldehyde monomer.

[0017] According to the present invention, the active center can be introduced through the following steps: 1) The prepared imidazole-based porous organic polymer was uniformly dispersed in an ethanol solvent containing a metal salt, and heated at 60-100 °C. o Stir overnight at C, then sonicate for 1-2 hours.

[0018] 2) After completion, the solvent is removed by rotary evaporation, and the product is dried overnight in an oven at 100°C. Then, the polymer precursor loaded with metal salt is placed in a tube furnace and heated to 400-500°C at a heating rate of 1-5°C / min under a hydrogen atmosphere. The temperature is maintained for 2-4 h to carry out reduction treatment and obtain the imidazole-based polymer catalyst.

[0019] According to the present invention, the metal salt includes one or more of chloroplatinic acid, palladium chloride, palladium nitrate, manganese acetate, and cobalt acetate.

[0020] According to the present invention, the catalyst can be used in the oxidation of 5-hydroxymethylfurfural to prepare furanyl dicarboxylic acid.

[0021] According to the present invention, the reaction for the oxidation of 5-hydroxymethylfurfural to prepare furanyl dicarboxylic acid is carried out at a temperature of 90-130°C, a reaction time of 0.5-12 h, an oxygen pressure of 0.5-2.0 MPa, and a catalyst dosage of 0.1-100% of the mass of the substrate 5-hydroxymethylfurfural.

[0022] According to the present invention, the oxidant is oxygen or air, and the oxidant is added by bubbling.

[0023] The beneficial effects of this invention are: (1) This invention creatively uses acidic ionic liquid as a catalyst and introduces crosslinking agent to catalyze the polymerization reaction, shortening the polymerization time of aldehyde monomer and amino monomer to less than 6 hours, thereby improving the efficiency of imidazole polymer carrier synthesis.

[0024] (2) Acidic ionic liquid catalysts are almost non-volatile, which reduces the environmental pollution and equipment corrosion caused by the volatilization of traditional inorganic acids (such as sulfuric acid and hydrochloric acid) during the reaction. In addition, acidic ionic liquids are easy to recover and recycle after the reaction, which can significantly reduce production costs and waste generation. This recyclability is in line with the principles of green chemistry.

[0025] (3) Compared with traditional silica, activated carbon and alumina supports, this imidazole-based porous organic polymer support has a higher specific surface area and a stronger active metal anchoring ability. In addition, nitrogen atoms in the imidazole-based porous organic polymer framework can interact with metals and use the electron transfer effect to regulate the electronic state of the active center, thereby changing its electron density and achieving the purpose of activation. Furthermore, the interaction between nitrogen atoms and metals can also stabilize the active metals, thus achieving both high activity and stability of the catalyst. (4) The catalyst of the present invention can achieve high conversion rate and selectivity without the need for additional alkali additives in the whole reaction process, which can effectively avoid equipment damage and subsequent maintenance, and reduce the difficulty of subsequent product separation; the reaction conditions are mild, which can reduce the difficulty and risk factor in process operation, thereby expanding the application range. Attached Figure Description

[0026] Figure 1 The figure shows the nitrogen adsorption-desorption curves for material A. Detailed Implementation

[0027] The method provided by the present invention will be described in detail below with reference to embodiments, but this does not limit the present invention in any way.

[0028] Example 1: Preparation of Material A (1) Weigh 2.62 g of pyrene-4,5,9,10-tetraone and 1.75 g of 1,2,4,5-phenyltetramine tetrahydrochloride and place them in a pressure-resistant glass tube. Add 15 mL of dioxane and 5 mL of mesitylene to the tube, then add 0.35 g of [BSO3Py]HSO4, followed by 0.01 g of glyoxal. After mixing evenly, freeze the reaction material into a solid under liquid nitrogen, evacuate to a vacuum, and then thaw until the reaction material is liquid. Repeat this process three times. After the above three freezing-evacuation-thawing cycles, keep the pressure-resistant tube in a vacuum state, seal the tube, and then place it in an oven at 130°C for 8 hours. After the reaction is completed, filter and collect the solid. Wash it three times each with DMF, water, and dichloromethane, and then transfer it to a Soxhlet extractor and wash it with THF for 48 hours. Dry it under vacuum at 100°C to obtain an imidazole-based porous organic polymer.

[0029] (2) Weigh 0.8 g of imidazole-based porous organic polymer and disperse it in 10 ml of ethanol. Add 175 mg of chloroplatinic acid hexahydrate, stir overnight at 60°C, and then sonicate for 2 h. (3) After impregnation, the solvent is removed by rotary evaporation, and the material is dried overnight in an oven at 100°C. Then it is reduced at 500°C for 4 hours in a hydrogen atmosphere to obtain material A.

[0030] Porosity study: Approximately 80 mg of sample was weighed and activated at 120℃ for 12 hours. The nitrogen adsorption-desorption isotherm at 77 K was then measured using a gas adsorption analyzer. The nitrogen adsorption-desorption isotherm is shown in the attached figure. The results indicate that... P / P In the low pressure range of 0 < 0.1, the isothermal adsorption curve shows a certain increase because N2 rapidly occupies the microporous structure in the polymer at pressures of 0.2 < P / P Within a pressure range of 0 < 0.8, the isothermal adsorption curve rises with increasing pressure, indicating the presence of a mesoporous structure in the polymer. P / P In the high-pressure range of 0 > 0.8, the polymer exhibits hysteresis loops. This is because N2 undergoes capillary condensation in the mesopores. At the same time, the isothermal adsorption line rises sharply with increasing pressure, indicating the presence of a macroporous structure.

[0031] Example 2: Preparation of Material B The preparation method of material B is the same as that of material A, except that the catalyst is [BSO3Py]ClO4.

[0032] Example 3 Preparation of Material C The preparation method of material C is the same as that of material A, except that the carbonyl monomer is 2,7-dibromo-pyrene-4,5,9,10-tetraone and the amino monomer is [1,1'-biphenyl]-3,3',4,4'-tetraamine.

[0033] Example 4: Preparation of Material D The preparation method of material D is the same as that of material A, except that the crosslinking agent is paraformaldehyde.

[0034] Example 5: Preparation of Material E The preparation method of material E is the same as that of material A, except that the metal salt is Mn(CH3COO)2 and the loading (wt%) is 3.0.

[0035] Example 6 Preparation of Material F The preparation method of material F is the same as that of material A, except that the catalyst is aluminum trichloride (1 mL of 1 mol / L aluminum trichloride aqueous solution).

[0036] Example 7 Preparation of Material G The preparation method of material G is the same as that of material A, except that acetic acid aqueous solution is used as the main catalyst and aluminum trichloride is used as the co-catalyst (2.5 mL of 3 mol / L acetic acid aqueous solution and 1 mL of 1 mol / L aluminum trichloride aqueous solution).

[0037] Example 8 30 mg of any one of the synthesized catalysts A-7, 1.2 g of HMF, and 10 ml of acetonitrile were added to a high-pressure reactor. The reaction was carried out at 120 °C and 1.0 MPa of oxygen for 6 h. After the reaction was completed and cooled to room temperature, the mixture was analyzed by HPLC.

[0038] In catalyst A: the HMF conversion rate is 95%, and the selectivity for furanyl dicarboxylic acid is 91.2%.

[0039] In catalyst B: the HMF conversion rate is 91%, and the selectivity for furanyl dicarboxylic acid is 89.8%.

[0040] In catalyst C, the HMF conversion rate is 89%, and the selectivity for furanyl dicarboxylic acid is 90%.

[0041] In catalyst D: the HMF conversion rate is 92%, and the selectivity for furanyl dicarboxylic acid is 88%.

[0042] In catalyst E: HMF conversion rate is 85%, and the selectivity for furanyl dicarboxylic acid is 86%.

[0043] In catalyst F: the HMF conversion rate is 76%, and the selectivity for furanyl dicarboxylic acid is 77%.

[0044] In catalyst G: HMF conversion rate is 80%, and the selectivity for furanyl dicarboxylic acid is 82%.

Claims

1. A method for preparing furanyl dicarboxylic acid by catalytic oxidation of 5-hydroxymethylfurfural using an imidazole-based porous organic polymer catalyst, characterized in that, Includes the following steps: (1) Synthesis of imidazole-based porous organic polymer carriers with the assistance of crosslinking agents; (2) The metal catalyst supported by the imidazole porous organic polymer was obtained by loading the active metal salt and reducing it at high temperature; (3) Under the action of a catalyst, molecular oxygen is used as an oxidant to efficiently catalyze the oxidation of 5-hydroxymethylfurfural to furanyl dicarboxylic acid.

2. The method according to claim 1, characterized in that, The imidazole-based porous organic polymer support was prepared according to the following steps: Carbonyl monomers and amino monomers were added to an organic solvent, along with a catalyst. The mixture was then subjected to an ultrasonic-microwave reaction at 130-180℃ for 6-12 hours under anaerobic conditions with the aid of a crosslinking agent. After the reaction was completed, imidazole-based porous organic polymers were obtained by filtration, washing, Soxhlet extraction, and vacuum drying.

3. The method according to claim 2, characterized in that, The organic solvent is one or more of 1,4-dioxane, mesitylene, n-butanol, N,N-dimethylformamide, acetonitrile, and tetrahydrofuran.

4. The method according to claim 2, characterized in that, The carbonyl monomer is pyrene-4,5,9,10-tetraone or 2,7-dibromo-pyrene-4,5,9,10-tetraone; the amino monomer is 1,2,4,5-phenyltetramine hydrochloride or [1,1'-biphenyl]-3,3',4,4'-tetramine; the molar mass ratio of the carbonyl monomer to the amino monomer is 1:

1.

5. The method according to claim 2, characterized in that, The catalyst is an acidic ionic liquid catalyst, including [BMIM][B(HSO4)4], [OMIM][B(HSO4)4], B(HSO4)3, [BSO3Py]HSO4 or [BSO3Py]ClO4.

6. The method according to claim 2, characterized in that, The crosslinking agent is one or more of formaldehyde, glyoxal, glutaraldehyde and paraformaldehyde, and the crosslinking agent accounts for 0.1-5% of the molar amount of the aldehyde monomer.

7. The method according to claim 2, characterized in that, The metal catalyst supported on imidazole-based porous organic polymers was prepared via the following steps: 1) The prepared imidazole-based porous organic polymer was uniformly dispersed in an ethanol solvent containing a metal salt, and heated at 60-100 °C. o Stirring at C overnight, followed by sonication for 1-2 hours; 2) After completion, the solvent is removed by rotary evaporation, and the product is dried overnight in an oven at 100°C. Then, the polymer precursor loaded with metal salt is placed in a tube furnace and heated to 400-500°C at a heating rate of 1-5°C / min under a hydrogen atmosphere. The temperature is maintained for 2-4 h to carry out reduction treatment and obtain the imidazole-based polymer catalyst.

8. The method according to claim 2, characterized in that, The metal salts mentioned include one or more of chloroplatinic acid, palladium chloride, palladium nitrate, manganese acetate, and cobalt acetate.

9. The method according to claim 1, characterized in that, The reaction for the oxidation of 5-hydroxymethylfurfural to prepare furanyl dicarboxylic acid is carried out at a temperature of 90-130℃, a reaction time of 0.5-12 h, an oxygen pressure of 0.5-2.0 MPa, and a catalyst dosage of 0.1-100% of the mass of the substrate 5-hydroxymethylfurfural.

10. The method according to claim 9, characterized in that: The oxidant is oxygen or air, and the oxidant is added by bubbling.

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