Metal-organic frameworks, methods of making the same, and methods of hydrolyzing 2,5-dimethylfuran

Abstract

This invention relates to the field of catalysis, specifically to a metal-organic framework (MOF), its preparation method, and a method for hydrolyzing 2,5-dimethylfuran. The MOF comprises a polyoxometalate component, the contact angle between the MOF and water is greater than 80°, and the total acidity is 150-700 μmol·g. ‑1 The metal-organic framework provided by this invention contains polyoxometalate components and has a contact angle with water of more than 80°. It also exhibits a polyhedral morphology with an arbitrary edge length of not less than 3 μm. This characteristic gives the metal-organic framework unique acidic and hydrophobic properties, as well as excellent hydrolytic activity.

Description

Technical Field

[0001] This invention relates to the field of catalysis, specifically to a metal-organic framework and its preparation method, and a method for hydrolyzing 2,5-dimethylfuran. Background Technology

[0002] In the 21st century, biomass, a renewable resource, has received increasing attention due to its potential to replace non-renewable resources such as petroleum. Methods for utilizing natural biomass organic molecules are constantly being developed, and more and more biomass platform compounds are coming into focus.

[0003] 2,5-Hexanedione (HDO), as an important organic chemical intermediate, is widely used in pharmaceuticals, fragrances, pesticides, photographic chemicals, electroplating and painting. HDO is chemically reactive and, as an important biomass platform compound, is used in the production of many high-value fine chemicals, such as bio-based PX, MCPD, N-substituted pyrrole, N-substituted tetrahydropyrrole, and 2,5-dimethyltetrahydrofuran.

[0004] The current production routes for HDO mainly include: 1. Carbonation and decarboxylation of acetoacetate esters via hydrolysis; 2. Hydrogenation and hydrolysis of raw materials such as cellulose, sugars, and 5-hydroxymethylfurfural (HMF); 3. Preparation via catalytic conversion reactions of polyhydroxy compounds, including glycerol; and 4. Hydrolysis of 2,5-dimethylfuran. All four current synthesis methods have certain drawbacks, such as high catalyst and raw material costs, the need for acidic or alkaline conditions leading to severe equipment corrosion and safety concerns, or, for example, the acetoacetate coupling decarboxylation method with excessively high raw material costs and complex operation, hindering large-scale industrial production.

[0005] CN112979436A discloses a method for preparing HDO, namely, obtaining 2,5-hexanedione through carbon growth-wacker oxidation reaction under the action of catalyst and oxidant. However, this method requires the use of precious metals and the product is relatively complex and difficult to separate. Literature [Chemistryselect,2016,1(6):1252-1255] reports a method for obtaining 2,5-hexanedione through a two-phase system using sulfuric acid as a catalyst. However, this method has problems such as the difficulty in recovering the homogeneous acid catalyst, severe corrosion of equipment, and the generation of a large amount of acidic pollutants. CN105439836B discloses a method for preparing 2,5-hexanedione by solid acid molecular sieve catalysis. The method has the advantages of easy separation and no pollution. However, the molecular sieve catalyst used has a large water absorption capacity, the reaction conditions are relatively harsh, and the organic phase uses methyl isobutyl ketone with a high boiling point, which will cause problems such as high energy consumption in subsequent separation. Summary of the Invention

[0006] The purpose of this invention is to overcome the problems of difficult catalyst recovery, high catalyst cost, poor catalyst selectivity, and harsh catalytic reaction conditions in the preparation of 2,5-hexanedione in the prior art. This invention provides a metal-organic framework, its preparation method, and a method for hydrolyzing 2,5-dimethylfuran. The metal-organic framework has the characteristics of low cost, good stability and easy recovery, high selectivity for 2,5-hexanedione, and mild reaction conditions.

[0007] To achieve the above objectives, a first aspect of the present invention provides a metal-organic framework comprising a polyoxometalate component, wherein the contact angle between the metal-organic framework and water is greater than 80°, and the total acidity is 150-700 μmol·g. -1 It has a polyhedral shape and any edge length is not less than 3μm.

[0008] The second aspect of the present invention provides a method for preparing the metal-organic framework described in the first aspect, the method comprising the following steps: S1: a metal salt solution and an organic ligand solution are subjected to a first contact at a pH of 3-7, a polyoxometalate solution is added for a second contact, and after contact, crystallization, a first separation, and a first drying are performed to obtain a precursor; S2: under an inert atmosphere, the precursor and a hydrophobic component are subjected to a third contact in an organic solvent, followed by a second separation and a second drying.

[0009] A third aspect of the present invention provides a method for hydrolyzing 2,5-dimethylfuran, the method comprising: reacting 2,5-dimethylfuran with a catalyst in a composite solvent system containing water and an organic solvent, wherein the catalyst comprises the metal-organic framework described in the first aspect.

[0010] Through the above technical solution, the present invention has the following advantages:

[0011] The metal-organic framework provided by this invention contains a polyoxometalate component and has a water contact angle of over 80°, with a total acidity of 150-700 μmol·g. -1 Furthermore, the morphology is polyhedral with any edge length not less than 3 μm. Metal-organic frameworks with this characteristic possess unique acidic properties, hydrophobic properties, and excellent hydrolytic activity.

[0012] In the preparation method of the present invention, acid treatment, composite polyoxometalate (POMS), and hydrophobic treatment are used to work synergistically to give MOF unique structural features, acid content, and water contact angle characteristics.

[0013] The metal-organic framework (MOF) of this invention is applied to the hydrolysis of 2,5-dimethylfuran to prepare 2,5-hexanedione. The reactants react on the pores of the MOF surface. Silanization of the MOF increases the hydrophobicity of the pores surrounding the polyanions, forming hydrophobic channels. Therefore, small molecules diffuse rapidly through these channels after the reaction, minimizing the risk of self-polymerization and reduced product selectivity. After the reaction, the solid acid catalyst is easily separated from the reaction system by simple filtration, facilitating further separation of the subsequent products. Attached Figure Description

[0014] Figure 1 This is a scanning electron microscope (SEM) image of the hydrophobic MOF-1 from Example 1.

[0015] Figure 2 The contact angle between the hydrophobic MOF-1 in Example 1 and water;

[0016] Figure 3 The N2- adsorption-desorption curve of hydrophobic MOF-1 in Example 1;

[0017] Figure 4 This is a scanning electron microscope (SEM) image of the hydrophobic MOF-2 in Example 2.

[0018] Figure 5 Scanning electron microscope (SEM) image of the hydrophobic MOF-1-1 in Comparative Example 1. Detailed Implementation

[0019] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0020] This invention provides a metal-organic framework comprising a polyoxometalate component, wherein the contact angle between the metal-organic framework and water is greater than 80°, and the total acidity is 150-700 μmol·g. -1 It has a polyhedral shape and any edge length is not less than 3μm.

[0021] The metal-organic framework provided by this invention contains a polyoxometalate component and has a water contact angle of over 80°, with a total acidity of 150-700 μmol·g. -1 Furthermore, the morphology is polyhedral with any edge length not less than 3 μm. Metal-organic frameworks with this characteristic possess unique acidic properties, hydrophobic properties, and excellent hydrolytic activity.

[0022] According to a preferred embodiment of the present invention, the contact angle between the metal-organic framework and water is 80-150°, preferably 80-120°. By adopting the aforementioned preferred embodiment, the catalytic activity of the material can be further improved.

[0023] According to a preferred embodiment of the present invention, the metal-organic framework comprises a hydrophobic component, which is loaded on the surface of the metal-organic framework.

[0024] In this invention, the range of selectable hydrophobic components is relatively wide, for example, they can be silane compounds and alkylamine compounds. According to a preferred embodiment of this invention, the hydrophobic component is a silane compound, preferably at least one of polydimethylsiloxane, hexadecyltrimethoxysilane, chlorosilane, dimethyldichlorosilane, phenyltrimethoxysilane, and diethoxydimethylsilane.

[0025] According to a preferred embodiment of the present invention, the metal-organic framework has a hexagonal cross-section and a crystal size of 3-20 μm.

[0026] According to a preferred embodiment of the present invention, the total acidity of the metal-organic framework is 200-600 μmol·g. -1 More preferably, 460-600 μmol·g -1 By adopting the aforementioned preferred scheme, the catalytic activity of the material can be further improved.

[0027] According to a preferred embodiment of the present invention, the total specific surface area of ​​the metal-organic framework is 400-900 m². 2 ·g -1 Preferably 650-900m 2 ·g -1 ; .

[0028] According to a preferred embodiment of the present invention, the external specific surface area of ​​the metal-organic framework is 40-100 m². 2 ·g -1 Preferably 55-100m 2 ·g -1 .

[0029] According to a preferred embodiment of the present invention, the total pore volume of the metal-organic framework is 0.3-1.0 cm³. 3 ·g -1 For example, it could be 0.3cm 3 ·g -1 0.4cm 3 ·g -1 0.5cm 3 ·g -1 0.6cm3 ·g -1 0.7cm 3 ·g -1 0.8cm 3 ·g -1 0.9cm 3 ·g -1 1.0cm 3 ·g -1 .

[0030] According to a preferred embodiment of the present invention, the micropore volume of the metal-organic framework is 0.1-0.6 cm³. 3 ·g -1 For example, it could be 0.1cm 3 ·g -1 0.2cm 3 ·g -1 0.3cm 3 ·g -1 0.4cm 3 ·g -1 0.5cm 3 ·g -1 0.6cm 3 ·g -1 .

[0031] In this invention, the range of polyoxometalates is relatively wide. According to a preferred embodiment of this invention, the polyoxometalate component is selected from H4SiW. 12 O 40 ·nH2O、H3PW 12 O 40 nH2O, H4SiMo 12 O 40 nH2O, H3PMo 12 O 40 nH2O and H3AsMo 12 O 40 At least one of nH2O. By adopting the aforementioned preferred scheme, the catalytic activity of the MOF material can be further improved.

[0032] In this invention, the metal element of the metal-organic framework can be a conventional choice in the art. According to a preferred embodiment of the invention, the metal element of the metal-organic framework is selected from at least one of Zr, Cr, Fe, Co, Ni, Cu, Ag, Zn and Al, preferably at least one of Cu, Zr, Zn and Zr.

[0033] In this invention, the organic ligands of the metal-organic framework can be selected from a wide range, such as imidazole ligands and / or carboxylic acid ligands commonly used in the art. In order to further improve the effect of this invention, the organic ligands of the metal-organic framework in this invention are carboxylic acid ligands.

[0034] According to a preferred embodiment of the present invention, the imidazole ligand is selected from at least one of imidazole, 2-methylimidazolium, 2-nitroimidazolium, and 2-nitroimidazolium derivatives.

[0035] According to a preferred embodiment of the present invention, the carboxylic acid ligand is selected from at least one of pyromellitic acid, terephthalic acid, 2-aminoterephthalic acid, phthalic acid, biphenyl-3,4,5-tricarboxylic acid, 1,4-naphthalenedicarboxylic acid, biphenyl dicarboxylic acid, and 3,3,5,5-biphenyltetracarboxylic acid.

[0036] This invention provides a method for preparing the aforementioned metal-organic framework, the method comprising the following steps:

[0037] S1: The metal salt solution and the organic ligand solution are first contacted at pH 3-7, and then a polyoxometalate solution is added for the second contact. After contact, crystallization, first separation and first drying are performed to obtain the precursor.

[0038] S2: Under an inert atmosphere, the precursor and hydrophobic component undergo a third contact, a second separation, and a second drying in an organic solvent.

[0039] In this invention, the metal salt solution is a solution obtained by dissolving the metal in water, and the ratio of solvent water to metal salt is 5-500 mL solvent water / 1.0 g metal salt.

[0040] In this invention, the organic ligand solution is a solution obtained by dissolving the organic ligand in an organic solvent, such as at least one selected from N,N-dimethylformamide, N,N-dimethylacetamide, tetrahydrofuran, methanol, ethanol, propanol, butanol, n-butanol, and isopropanol.

[0041] In this invention, the polyoxometalate solution is a solution obtained by dissolving the polyoxometalate in an organic solvent, such as at least one selected from N,N-dimethylformamide, N,N-dimethylacetamide, tetrahydrofuran, methanol, ethanol, propanol, butanol, n-butanol, and isopropanol.

[0042] In this invention, the pH is controlled by a pH adjuster, which is a conventional weak acid and / or moderately strong acid in the art. According to a preferred embodiment of the invention, the acid is selected from at least one of H3PO4, H2C2O4, HCOOH, CH3COOH, and HSiO. By adopting the aforementioned preferred scheme, the active adsorption sites on the surface of the metal-organic framework can be further increased or more defect cavities can be created, thereby further improving the catalytic activity of the material.

[0043] According to a preferred embodiment of the present invention, the organic solvent in step S2 is selected from at least one of tetrahydrofuran, toluene, acetone, methyl isobutyl ketone, dichlorotoluene, and dichloromethane.

[0044] According to a preferred embodiment of the present invention, the inert atmosphere is at least one of nitrogen, helium, and argon.

[0045] According to a preferred embodiment of the present invention, the method includes a cooling step before the first separation and / or the second separation; and / or a washing step after the first separation and / or the second separation.

[0046] In this invention, there are no particular limitations on the conditions for the first contact, the second contact, the third contact, crystallization, cooling, separation, washing, and drying.

[0047] According to a preferred embodiment of the present invention, the conditions for the first contact include a temperature of 25-85°C, preferably 30-70°C.

[0048] In this invention, the first contact time is determined based on the contact temperature, as long as the reaction is complete. For example, the first contact time is 0.5-6 hours, preferably 1-3 hours.

[0049] In this invention, the first contact can be carried out under stirring conditions, typically with a stirring speed of 100-900 r / min.

[0050] According to a preferred embodiment of the present invention, the conditions for the first contact include: the molar ratio of the metal salt to the organic ligand is 1:(0.2-5).

[0051] According to a preferred embodiment of the present invention, the conditions for the second contact include a temperature of 25-85°C, preferably 30-70°C.

[0052] In this invention, the second contact time is determined according to the contact temperature, as long as the reaction is complete. For example, the first contact time is 0.5-6 hours, preferably 1-3 hours.

[0053] In this invention, the second contact can be carried out under stirring conditions, typically at a stirring speed of 100-900 r / min.

[0054] According to a preferred embodiment of the present invention, the conditions for the second contact include: the molar ratio of the metal salt to the polyoxometalate is (5-150):1.

[0055] According to a preferred embodiment of the present invention, the crystallization conditions include a temperature of 60-250°C, preferably 80-200°C.

[0056] According to a preferred embodiment of the present invention, the crystallization conditions include a time of 3-48 hours, preferably 15-30 hours.

[0057] In this invention, the crystallization can be carried out under stirring conditions, typically at a stirring speed of 100-600 r / min.

[0058] According to a preferred embodiment of the present invention, the conditions for the third contact include: a temperature of 80-200°C, preferably 100-200°C.

[0059] According to a preferred embodiment of the present invention, the conditions for the third contact include: a time of 3-48 hours, preferably 5-24 hours.

[0060] According to a preferred embodiment of the present invention, the conditions for the third contact include: the molar concentration of the hydrophobic component in the organic solvent is 0.1-100 mmol / L.

[0061] According to a preferred embodiment of the present invention, the conditions for the third contact include: the volume / mass ratio of the organic solvent to the precursor is (50-800) mL:1g, preferably (50-500) mL:1g.

[0062] According to a preferred embodiment of the present invention, the drying temperature of the first drying stage is 30-200°C; optionally, the first drying is carried out in two stages, with a temperature difference of 30-120°C between the two stages. For example, the temperature of the first stage is 75°C and the time is 4 hours, and the drying temperature of the second stage is 180°C and the time is 12 hours.

[0063] According to a preferred embodiment of the present invention, the temperature of the second drying is 30-180°C.

[0064] This invention provides a method for the hydrolysis of 2,5-dimethylfuran, the method comprising: reacting 2,5-dimethylfuran with a catalyst in a composite solvent system containing water and an organic solvent, wherein the catalyst comprises the metal-organic framework described in this invention.

[0065] According to a preferred embodiment of the present invention, the organic solvent in the composite solvent system is a weakly polar solvent, preferably selected from at least one of toluene, methyl isobutyl ketone, cyclohexane, ethyl acetate, and tetrahydrofuran.

[0066] According to a preferred embodiment of the present invention, the composite solvent system contains a salt, preferably selected from at least one of NaCl, Na2SO4, KCl, and K2SO.

[0067] According to a preferred embodiment of the present invention, the volume ratio of water to organic solvent in the composite solvent system is 0.05-2:1, preferably 0.08-0.3; the mass ratio of salt to water is 0.05-10:1.

[0068] According to a preferred embodiment of the present invention, the conditions for the contact reaction include: a reaction temperature of 100-220°C, preferably 120-200°C.

[0069] According to a preferred embodiment of the present invention, the conditions for the contact reaction include: a reaction time of 1-24 hours, preferably 4-16 hours.

[0070] In this invention, the contact reaction can be carried out under stirring conditions, typically at a stirring speed of 200-1000 r / min, preferably 400-800 r / min.

[0071] According to a preferred embodiment of the present invention, the conditions for the contact reaction include: a mass ratio of 2,5-dimethylfuran to catalyst of 0.5-10:1, preferably 1-8:1.

[0072] The present invention will be described in detail below through examples. In the following examples, the raw materials are all commercially available products.

[0073] The N-substituted pyrrole compounds in the reaction products were qualitatively and quantitatively analyzed by gas chromatography-mass spectrometry (GC-MS), and the conversion rate of soluble carbohydrates in the products was analyzed by high-performance liquid chromatography (HPLC). The GC-MS system was an Agilent 7890A (Agilent Technologies, Inc.), with an HP-5 nonpolar capillary column (30 m, 0.53 mm). The gas chromatograph was an Agilent 7890B, with a flame ionization detector (FID), and an SE-54 capillary column (30 m, 0.53 mm). HPLC analysis was performed using an Agilent 1200 system with a SHODEX SC1011 sugar column (8 × 300 mm).

[0074] In this invention, the contact angle measuring instrument is a DSA100 from KRUSS GmbH, Germany. The angle θ between the tangent line drawn from the gas-liquid-solid interface at the point of contact between the gas, liquid, and solid phases and the solid-liquid boundary line passing through this contact point is the contact angle of the liquid on the solid surface. When the gas is air, the solid is a modified MOF material, and the liquid is water, the measured contact angle is the contact angle between the modified MOF material and water. A larger contact angle indicates better relative hydrophobicity of the modified MOF catalyst.

[0075] In this invention, scanning electron microscope (SEM) images of the samples were taken using a Hitachi S-4800II scanning electron microscope. The instrument's accelerating voltage was 15 kV, and all samples underwent chrome plating before analysis.

[0076] In this invention, the instruments and methods for testing the average pore size, specific surface area, and pore volume of the samples are as follows: Physical adsorption using nitrogen gas was performed at -196℃ using a 3H-2000PM2 physical adsorption instrument to analyze the pore structure characteristics of each adsorbent material sample. The initial degassing conditions were: degassing at 150℃ for 6 hours. After obtaining the adsorption isotherm of nitrogen on the sample, the specific surface area was calculated using the BET (Brunauer-Emmett-Teller) method, and the pore volume and pore size distribution were calculated using the BJH (Barrett-Joyner-Halenda) method.

[0077] In this invention, the acid content of the sample was determined using an Altamira AMI-3300 instrument with NH3-TPD chemical adsorption-desorption curve. Before the test, the sample was activated at 200℃ for 1 h, ammonia was adsorbed at 100℃ for 20 min, and then desorption was detected at 100-350℃. The acid content was calculated by peak division of Gaussian distribution and baseline adjustment.

[0078] The conversion formula for furan compounds, using 2,5-dimethylfuran as a substrate, is as follows:

[0079] Conversion rate of 2,5-dimethylfuran % = (molar amount of 2,5-dimethylfuran participating in the reaction) / (molar amount of 2,5-dimethylfuran substrate) × 100%.

[0080] The formula for calculating the yield of the product 2,5-hexanedione, using 2,5-dimethylfuran as a substrate, is as follows:

[0081] Yield % of product 2,5-hexanedione = (molar amount of 2,5-hexanedione produced in the reaction) / (molar amount of reaction substrate 2,5-dimethylfuran) × 100%.

[0082] Selectivity % of product 2,5-hexanedione = (molar amount of 2,5-hexanedione produced in the reaction) / (molar amount of 2,5-dimethylfuran reacted) × 100%.

[0083] Example 1

[0084] Weigh 2.0 g of copper nitrate trihydrate and dissolve it in 80 mL of deionized water to obtain solution A. Weigh 1.6 g of trimesic acid and dissolve it in 40 mL of LMF and 40 mL of ethanol. Stir thoroughly for 30 min to obtain solution B. Weigh H3PW... 12 O 40 0.2 g of 5H₂O was thoroughly stirred to form solution C. Solution A was then added dropwise to solution B at a rate of 1 ml / min while maintaining high-speed stirring. After the addition was complete, acetic acid was added dropwise until the pH of the solution reached approximately 4.5, yielding suspension D. Solution C was then added dropwise to suspension D at a rate of 0.5 ml / min. The entire system was then transferred to a crystallization vessel and crystallized at 100°C for 22 hours.

[0085] After crystallization, the mixture was cooled to room temperature, centrifuged to remove the mother liquor, and washed several times with ethanol. Drying was carried out in two stages: the first stage was at 75℃ for 4 hours, and the second stage was at 180℃ for 12 hours, yielding MOF-1 after drying.

[0086] Weigh 1.5 g of the prepared MOF-1 and place it in 150 mL of toluene. Then add phenyltrimethoxysilane to make its molar concentration 2 mM. Stir at 120 °C for 10 h under N2 atmosphere. Then centrifuge the suspension and wash it three times with toluene. Finally, dry it under vacuum at 150 °C for 12 h to obtain hydrophobic MOF-1.

[0087] SEM images of hydrophobic MOF-1 samples are shown below. Figure 1 As shown, the crystal form is polyhedral, with any edge length not less than 3 μm and a hexagonal cross-section. The total acid content of the sample is 533 μmol·g. -1 The contact angle between the sample and water was 113.7°. Figure 2 As shown. The N2- adsorption-desorption curves of the samples are shown in the figure. Figure 3 The pore structure data are shown in Table 1.

[0088] Example 2

[0089] Weigh 2.0 g of copper nitrate trihydrate and dissolve it in 80 mL of deionized water to obtain solution A. Weigh 1.6 g of trimesic acid and dissolve it in 40 mL of LMF and 40 mL of ethanol. Stir thoroughly for 30 min to obtain solution B. Weigh H3PW... 12 O 400.2 g of 5H₂O was thoroughly stirred to form solution C. Solution A was then added dropwise to solution B at 50°C, with a dropping rate controlled at 1 ml / min, while maintaining high-speed stirring. After the addition was complete, acetic acid was added dropwise until the pH of the solution was approximately 4, yielding suspension D. Solution C was then added dropwise to suspension D, with a dropping rate controlled at 0.5 ml / min. The entire system was then transferred to a crystallization vessel and crystallized at 100°C for 22 hours.

[0090] After crystallization, the mixture was cooled to room temperature, centrifuged to remove the mother liquor, and washed several times with ethanol. Drying was carried out in two stages: the first stage was at 75℃ for 4 hours, and the second stage was at 180℃ for 12 hours. MOF-2 was obtained after vacuum drying.

[0091] Weigh 1.5 g of the prepared MOF-2 and place it in 150 mL of toluene. Add chlorosilane to make the molar concentration 5 mM and stir at 120 °C for 10 h under N2 atmosphere. Then centrifuge the suspension and wash it three times with toluene. Finally, dry it under vacuum at 150 °C for 12 h to obtain hydrophobic MOF-2.

[0092] SEM images of hydrophobic MOF-2 are shown below. Figure 4 As shown, any edge length is not less than 3 μm, and the cross-section is hexagonal. The total acid content of the sample is 470 μmol·g. -1 The contact angle between the sample and water was 110.3°. The pore structure data of the sample are shown in Table 1.

[0093] Example 3

[0094] 2.0 g of copper nitrate trihydrate was dissolved in 80 mL of deionized water to obtain solution A. 1.6 g of trimesic acid was added to 40 mL of LMF and 40 mL of ethanol and stirred thoroughly for 30 min to obtain solution B. H4SiW was then added... 12 O 40 0.2g of solution A was stirred thoroughly to form solution C. Solution A was then added dropwise to solution B at 50°C, with the addition rate controlled at 1 ml / min, while maintaining high-speed stirring. After the addition was complete, acetic acid was added dropwise until the pH of the solution was approximately 3.5, yielding suspension D. Solution C was then added dropwise to suspension D. Finally, solution C was added dropwise to suspension D, with the addition rate controlled at 0.5 ml / min. The entire system was then transferred to a crystallization vessel and crystallized at 120°C for 22 hours.

[0095] After crystallization, the mixture was cooled to room temperature, centrifuged to remove the mother liquor, and washed several times with ethanol. Drying was carried out in two stages: the first stage was at 75℃ for 4 hours, and the second stage was at 180℃ for 12 hours. MOF-3 was obtained after vacuum drying.

[0096] Weigh 1.5 g of the prepared MOF-3 and place it in 150 mL of toluene. Then add phenyltrimethoxysilane to make the molar concentration 2 mM and stir at 120 °C for 10 h under N2 atmosphere. Then centrifuge the suspension and wash it three times with toluene. Finally, dry it under vacuum at 150 °C for 12 h to obtain hydrophobic MOF-3.

[0097] SEM of hydrophobic MOF-3 samples and Figure 1 Similarly, all edges have a length not less than 3 μm, and the cross-section is hexagonal. The total acid content of the sample is 492 μmol·g. -1 The contact angle between the sample and water was 110°. The pore structure data of the sample are shown in Table 1.

[0098] Example 4

[0099] Same as Example 1, except that other octadecaneamines were used as the hydrophobic component, and the SEM images of the hydrophobic MOF-4 sample were compared with those of Example 1. Figure 1 Similarly, the cross-section is hexagonal. The total acid content of the sample is 450 μmol·g. -1 The contact angle between the sample and water was 105.5°. Pore structure data are shown in Table 1.

[0100] Example 5

[0101] Same as Example 1, except that H4GeW is used. 12 O 40 ·nH2O, as a polyoxometalate, was observed by SEM of the hydrophobic MOF-5 sample. Figure 1 Similarly, the sample has an arbitrary edge length of not less than 3 μm and a hexagonal cross-section. The total acid content of the sample is 431 μmol·g. -1 The contact angle between the sample and water was 98.7°. Pore structure data are shown in Table 1.

[0102] Example 6

[0103] Same as Example 1, except that imidazole was used as the ligand, and the total acidity of the hydrophobic MOF-6 sample was 395 μmol·g. -1 The contact angle between the sample and water was 93.1°. Pore structure data are shown in Table 1.

[0104] Table 1

[0105]

[0106] Examples 7-12

[0107] Using 2,5-dimethylfuran as a substrate, 0.3 g of the hydrophobic MOF from Examples 1-6 above, 1.0 g of 2,5-dimethylfuran, 10 g of methyl isobutyl ketone, and 2.0 g of saturated sodium chloride aqueous solution were added to a high-pressure reactor equipped with a stirrer. Nitrogen gas at 1 MPa was introduced to prevent the organic solvent from boiling. The temperature was raised to the preset temperature using a programmed heating mantle, and then stirred magnetically. The reaction was carried out at 160 °C for 10 h. The conversion rate of 2,5-dimethylfuran and the yield of the target product 2,5-hexanedione were analyzed and are shown in Table 2.

[0108] Table 2

[0109]

[0110] Example 13

[0111] Using 2,5-dimethylfuran as a substrate and methyl isobutyl ketone and water as solvents, 0.6 g of the hydrophobic MOF-1 from Example 1, 1.0 g of 2,5-dimethylfuran, 10 g of methyl isobutyl ketone, and 2.0 g of saturated sodium chloride aqueous solution were added to a high-pressure reactor equipped with a stirrer. Nitrogen gas at 1 MPa was introduced to prevent the organic solvent from boiling. The temperature was raised to the preset temperature using a programmed heating mantle, and then stirred magnetically. The reaction was carried out at 160 °C for 10 h. The conversion rate of 2,5-dimethylfuran and the yield of the target product 2,5-hexanedione were analyzed and are shown in Table 3.

[0112] Example 14

[0113] Using 2,5-dimethylfuran as a substrate and methyl isobutyl ketone and water as solvents, 0.1 g of the hydrophobic MOF-1 from Example 1, 1.0 g of 2,5-dimethylfuran, 10 g of methyl isobutyl ketone, and 2.0 g of saturated sodium chloride aqueous solution were added to a high-pressure reactor equipped with a stirrer. Nitrogen gas at 1 MPa was introduced to prevent the organic solvent from boiling. The temperature was raised to the preset temperature using a programmed heating mantle, and then stirred magnetically. The reaction was carried out at 160 °C for 10 h. The conversion rate of 2,5-dimethylfuran and the yield of the target product 2,5-hexanedione were analyzed and are shown in Table 3.

[0114] Example 15

[0115] Using 2,5-dimethylfuran as a substrate and methyl isobutyl ketone and water as solvents, 0.3 g of the hydrophobic MOF-1 from Example 1, 1.0 g of 2,5-dimethylfuran, 10 g of methyl isobutyl ketone, and 4.0 g of saturated sodium chloride aqueous solution were added to a high-pressure reactor equipped with a stirrer. Nitrogen gas at 1 MPa was introduced to prevent the organic solvent from boiling. The temperature was raised to the preset temperature using a programmed heating mantle, and then stirred magnetically. The reaction was carried out at 160 °C for 10 h. The conversion rate of 2,5-dimethylfuran and the yield of the target product 2,5-hexanedione were analyzed and are shown in Table 3.

[0116] Example 16

[0117] Using 2,5-dimethylfuran as a substrate and methyl isobutyl ketone and water as solvents, 0.3 g of the hydrophobic MOF-1 from Example 1, 1.0 g of 2,5-dimethylfuran, 10 g of methyl isobutyl ketone, and 2.0 g of saturated sodium chloride aqueous solution were added to a stirred high-pressure reactor. Nitrogen gas at 1 MPa was introduced to prevent boiling of the organic solvent. The temperature was raised to the preset temperature using a programmed heating mantle, and then stirred magnetically. The reaction was carried out at 180 °C for 10 h. The conversion rate of 2,5-dimethylfuran and the yield of the target product 2,5-hexanedione were analyzed and are shown in Table 3.

[0118] Example 17

[0119] Using 2,5-dimethylfuran as a substrate and methyl isobutyl ketone and water as solvents, 0.3 g of the hydrophobic MOF-1 from Example 1, 1.0 g of 2,5-dimethylfuran, 10 g of methyl isobutyl ketone, and 2.0 g of saturated sodium chloride aqueous solution were added to a high-pressure reactor equipped with a stirrer. Nitrogen gas at 1 MPa was introduced to prevent the organic solvent from boiling. The temperature was raised to the preset temperature using a programmed heating mantle, and then stirred magnetically. The reaction was carried out at 160 °C for 15 h. The conversion rate of 2,5-dimethylfuran and the yield of the target product 2,5-hexanedione were analyzed and are shown in Table 3.

[0120] Example 18

[0121] Using 2,5-dimethylfuran as the substrate and tetrahydrofuran (THF) and water as solvents, 0.3 g of the hydrophobic MOF-1 from Example 1, 1.0 g of 2,5-dimethylfuran, 10 g of tetrahydrofuran, and 2.0 g of saturated sodium chloride aqueous solution were added to a stirred high-pressure reactor. Nitrogen gas at 1 MPa was introduced to prevent boiling of the organic solvent. The temperature was raised to the preset temperature using a programmed heating mantle, and then stirred magnetically. The reaction was carried out at 160 °C for 10 h. The conversion rate of 2,5-dimethylfuran and the yield of the target product 2,5-hexanedione were analyzed and are shown in Table 3.

[0122] Example 19

[0123] Using 2,5-dimethylfuran as the substrate and tetrahydrofuran and water as solvents, 0.3 g of the hydrophobic MOF-1 from Example 1, 1.0 g of 2,5-dimethylfuran, 10 g of tetrahydrofuran, and 4.0 g of saturated sodium chloride aqueous solution were added to a high-pressure reactor equipped with a stirrer. Nitrogen gas at 1 MPa was introduced to prevent the organic solvent from boiling. The temperature was raised to the preset temperature using a programmed heating mantle, and then stirred magnetically. The reaction was carried out at 160 °C for 10 h. The conversion rate of 2,5-dimethylfuran and the yield of the target product 2,5-hexanedione were analyzed and are shown in Table 3.

[0124] Example 20

[0125] Using 2,5-dimethylfuran as the substrate and tetrahydrofuran and water as solvents, 0.3 g of the hydrophobic MOF-1 from Example 1, 1.0 g of 2,5-dimethylfuran, 10 g of tetrahydrofuran, and 1.0 g of saturated sodium chloride aqueous solution were added to a high-pressure reactor equipped with a stirrer. Nitrogen gas at 1 MPa was introduced to prevent the organic solvent from boiling. The temperature was raised to the preset temperature using a programmed heating mantle, and then stirred magnetically. The reaction was carried out at 160 °C for 10 h. The conversion rate of 2,5-dimethylfuran and the yield of the target product 2,5-hexanedione were analyzed and are shown in Table 3.

[0126] Table 3

[0127]

[0128] Example 21

[0129] Using 2,5-dimethylfuran as a substrate and methyl isobutyl ketone (MIBK) and water as solvents, 0.3 g of the hydrophobic MOF from Example 1 above, 1.0 g of 2,5-dimethylfuran, 10 g of methyl isobutyl ketone, and 2.0 g of deionized water were added to a high-pressure reactor equipped with a stirrer. Nitrogen gas at 1 MPa was introduced to prevent boiling of the organic solvent. The temperature was raised to the preset temperature using a programmed heating mantle, and then stirred magnetically. The reaction was carried out at 160 °C for 10 h. Analysis of the reaction solution showed that the conversion rate of 2,5-dimethylfuran was 75%, and the yield of 2,5-hexanedione was 70%.

[0130] Comparative Example 1

[0131] Same as Example 1, except that acetic acid was added to bring the pH to 2 to obtain MOF-1-1.

[0132] Weigh 1.5 g of the prepared MOF-1-1 and place it in 150 mL of toluene. Then add phenyltrimethoxysilane to make the molar concentration 2 mM and stir at 120 °C for 10 h under N2 atmosphere. Then centrifuge the suspension and wash it three times with toluene. Finally, dry it under vacuum at 150 °C for 12 h to obtain hydrophobic MOF-1-1.

[0133] SEM image of sample hydrophobic MOF-1-1 is shown below Figure 5 As shown, the material exhibits a sheet-like morphology. The total acid content of the sample is 558 μmol·g. -1 The hydrophobic angle of the sample is approximately 108.2°.

[0134] Using 2,5-dimethylfuran as a substrate and methyl isobutyl ketone (MIBK) and water as solvents, 0.3 g of the above-mentioned hydrophobic MOF-1-1, 1.0 g of 2,5-dimethylfuran, 10 g of methyl isobutyl ketone, and 2.0 g of saturated sodium chloride aqueous solution were added to a stirred high-pressure reactor. Nitrogen gas was introduced at 1 MPa to prevent boiling of the organic solvent. The temperature was raised to the preset temperature using a programmed heating mantle, and the reactor was stirred magnetically. The reaction was carried out at 160 °C for 10 h. Analysis of the reaction solution showed that the conversion rate of 2,5-dimethylfuran was 43%, and the yield of the target product, 2,5-hexanedione, was 36%.

[0135] Comparative Example 2

[0136] Same as Example 1, except that no hydrophobic agent was added, resulting in MOF-1-2.

[0137] The total acid content of the sample was 480 μmol·g -1 When the hydrophobic angle test is performed, the water droplets are quickly absorbed by the sample, indicating that the sample is hydrophilic.

[0138] Using 2,5-dimethylfuran as a substrate and methyl isobutyl ketone (MIBK) and water as solvents, 0.3 g of the above MOF-1-2, 1.0 g of 2,5-dimethylfuran, 10 g of methyl isobutyl ketone, and 2.0 g of saturated sodium chloride aqueous solution were added to a stirred high-pressure reactor. Nitrogen gas was introduced at 1 MPa to prevent boiling of the organic solvent. The temperature was raised to the preset temperature using a programmed heating mantle, and the reactor was stirred magnetically. The reaction was carried out at 160 °C for 10 h. Analysis of the reaction solution showed that the conversion of 2,5-dimethylfuran was 61%, and the yield of the target product, 2,5-hexanedione, was 52%.

[0139] Comparative Example 3

[0140] Same as Example 1, except that acetic acid was not added to obtain MOF-1-3.

[0141] The total acid content of the sample was 130 μmol·g. -1The contact angle between the sample and water is 90°.

[0142] Using 2,5-dimethylfuran as a substrate and methyl isobutyl ketone (MIBK) and water as solvents, 0.3 g of the above MOF-1-3, 1.0 g of 2,5-dimethylfuran, 10 g of methyl isobutyl ketone, and 2.0 g of saturated sodium chloride aqueous solution were added to a stirred high-pressure reactor. Nitrogen gas was introduced at 1 MPa to prevent boiling of the organic solvent. The temperature was raised to the preset temperature using a programmed heating mantle, and the reactor was stirred magnetically. The reaction was carried out at 160 °C for 10 h. Analysis of the reaction solution showed that the conversion of 2,5-dimethylfuran was 55%, and the yield of the target product, 2,5-hexanedione, was 51%.

[0143] Comparative Example 4

[0144] Same as Example 1, except that H3PW is not added. 12 O 40 5H2O yields MOF-1-3.

[0145] The total acid content of the sample was 105 μmol·g -1 The contact angle between the sample and water was 83°.

[0146] Using 2,5-dimethylfuran as a substrate and methyl isobutyl ketone (MIBK) and water as solvents, 0.3 g of the above MOF-1-4, 1.0 g of 2,5-dimethylfuran, 10 g of methyl isobutyl ketone, and 2.0 g of saturated sodium chloride aqueous solution were added to a stirred high-pressure reactor. Nitrogen gas was introduced at 1 MPa to prevent boiling of the organic solvent. The temperature was raised to the preset temperature using a programmed heating mantle, and the reactor was stirred magnetically. The reaction was carried out at 160 °C for 10 h. Analysis of the reaction solution showed that the conversion rate of 2,5-dimethylfuran was 43%, and the yield of the target product, 2,5-hexanedione, was 40%.

[0147] Comparative Example 5

[0148] 2.0 g of copper nitrate trihydrate was dissolved in 80 mL of deionized water to obtain solution A. 1.6 g of trimesic acid was weighed into 40 mL of LMF and 40 mL of ethanol and stirred thoroughly for 30 min to obtain solution B. The above system was then transferred to a crystallization vessel and crystallized at 100 °C for 22 h.

[0149] After crystallization, the mixture was cooled to room temperature, centrifuged to remove the mother liquor, and washed several times with ethanol. Drying was carried out in two stages: the first stage was at 75℃ for 4 hours, and the second stage was at 180℃ for 12 hours, yielding MOF-1-5 after drying.

[0150] The total acidity of sample MOF-1-5 was 89 μmol·g. -1When the hydrophobic angle test is performed, the water droplets are quickly absorbed by the sample, indicating that the sample is hydrophilic.

[0151] Using 2,5-dimethylfuran as a substrate and methyl isobutyl ketone (MIBK) and water as solvents, 0.3 g of the above MOF-1-5, 1.0 g of 2,5-dimethylfuran, 10 g of methyl isobutyl ketone, and 2.0 g of saturated sodium chloride aqueous solution were added to a stirred high-pressure reactor. Nitrogen gas was introduced at 1 MPa to prevent boiling of the organic solvent. The temperature was raised to the preset temperature using a programmed heating mantle, and the reactor was stirred magnetically. The reaction was carried out at 160 °C for 10 h. Analysis of the reaction solution showed that the conversion rate of 2,5-dimethylfuran was 25%, and the yield of the target product, 2,5-hexanedione, was 18%.

[0152] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A metal-organic framework, characterized in that, The metal-organic framework comprises a polyoxometalate component and a hydrophobic component supported on its surface, wherein the hydrophobic component is a silane compound; the contact angle between the metal-organic framework and water is 80-150°, and the total acidity is 200-600 µmol•g. -1 The morphology is polyhedral, with any edge length not less than 3μm, and the cross section of the metal-organic framework is hexagonal; The polyoxometalate component is selected from H4SiW 12 O 40 •nH2O, H3PW 12 O 40 •nH2O, H4SiMo 12 O 40 •nH2O, H3PMo 12 O 40 •nH2O and H3AsMo 12 O 40 At least one of the following: • nH2O.

2. The metal-organic framework according to claim 1, wherein, The contact angle between the metal-organic framework and water is 80-120°.

3. The metal-organic framework according to claim 1 or 2, wherein, The hydrophobic component is at least one of polydimethylsiloxane, hexadecyltrimethoxysilane, chlorosilane, dimethyldichlorosilane, phenyltrimethoxysilane, and diethoxydimethylsilane.

4. The metal-organic framework according to claim 1 or 2, wherein, The crystal size of the metal-organic framework is 3-20µm; and / or The total specific surface area of ​​the metal-organic framework is 400-900 m². 2 •g -1 ; and / or The specific surface area of ​​the metal-organic framework is 40-100 m². 2 •g -1 ; and / or The total pore volume of the metal-organic framework is 0.3-1.0 cm³. 3 •g -1 ; and / or The micropore volume of the metal-organic framework is 0.1-0.6 cm³. 3 •g -1 .

5. The metal-organic framework according to claim 4, wherein, The total specific surface area of ​​the metal-organic framework is 650-900 m². 2 •g -1 ; and / or The specific surface area of ​​the metal-organic framework is 55-100 m². 2 •g -1 .

6. The metal-organic framework according to claim 1 or 2, wherein, The metal-organic framework contains a metal element selected from at least one of Zr, Cr, Fe, Co, Ni, Cu, Ag, Zn, and Al; and / or The organic ligands of the metal-organic framework are carboxylic acid ligands.

7. The metal-organic framework according to claim 6, wherein, The metal-organic framework is composed of at least one of Cu, Zr, Zn, and Zr; and / or The organic ligand of the metal-organic framework is selected from at least one of pyromellitic acid, terephthalic acid, 2-aminoterephthalic acid, phthalic acid, biphenyl-3,4,5-tricarboxylic acid, 1,4-naphthalenedicarboxylic acid, biphenyl dicarboxylic acid, and 3,3,5,5-biphenyltetracarboxylic acid.

8. The method for preparing the metal-organic framework according to any one of claims 1-7, characterized in that, The preparation method includes the following steps: S1: The metal salt solution and the organic ligand solution are first contacted at pH 3-7, and then a polyoxometalate solution is added for the second contact. After contact, crystallization, first separation and first drying are performed to obtain the precursor. S2: Under an inert atmosphere, the precursor and hydrophobic component undergo a third contact, a second separation, and a second drying in an organic solvent.

9. The preparation method according to claim 8, wherein, The pH is controlled by a pH adjuster selected from at least one of H3PO4, H2C2O4, HCOOH, and CH3COOH; and / or The organic solvent mentioned in step S2 is selected from at least one of tetrahydrofuran, toluene, acetone, methyl isobutyl ketone, dichlorotoluene, and dichloromethane.

10. The preparation method according to claim 8 or 9, wherein, The conditions for the first contact include: a temperature of 25-85°C; and / or a molar ratio of the metal salt to the organic ligand of 1:(0.2-5); and / or The conditions for the second contact include: a temperature of 25-85°C; and / or a molar ratio of the metal salt to the polyoxometalate of (5-150):1; and / or The crystallization conditions include: a temperature of 60-250℃; and / or a time of 3-48h; and / or The conditions for the third contact include: a temperature of 80-200℃; and / or a time of 3-48h; and / or a molar concentration of the hydrophobic component in the organic solvent of 0.1-100mmol / L; and / or a volume / mass ratio of the organic solvent to the precursor of (50-800)mL:1g.

11. The preparation method according to claim 10, wherein, The conditions for the first contact include: a temperature of 30-70°C; and / or The conditions for the second contact include: a temperature of 30-70°C; and / or The crystallization conditions include: a temperature of 80-200℃; and / or a time of 15-30 hours; and / or The conditions for the third contact include: a temperature of 100-200℃; and / or a time of 5-24 hours; and / or The volume / mass ratio of organic solvent to precursor is (50-500) mL:1g.

12. A method for hydrolyzing 2,5-dimethylfuran, characterized in that, The method includes: reacting 2,5-dimethylfuran with a catalyst in a composite solvent system containing water and an organic solvent. The catalyst comprises a metal-organic framework as described in any one of claims 1-7.

13. The method according to claim 12, wherein, The organic solvent in the composite solvent system is a weakly polar solvent; and / or The composite solvent system contains a salt; and / or The volume ratio of water to organic solvent in the composite solvent system is 0.05-2:1; the mass ratio of salt to water is 0.05-10:

1.

14. The method according to claim 13, wherein, The organic solvent in the composite solvent system is at least one selected from toluene, methyl isobutyl ketone, cyclohexane, ethyl acetate, and tetrahydrofuran; and / or The composite solvent system contains at least one of NaCl, Na₂SO₄, KCl, and K₂SO₄; and / or The volume ratio of water to organic solvent in the composite solvent system is 0.08-0.3:

1.

15. The method according to claim 12 or 13, wherein, The conditions for the contact reaction include: The reaction temperature is 100-220℃; and / or The reaction time is 1-24 hours; and / or The mass ratio of 2,5-dimethylfuran to the catalyst is 0.5-10:

1.

16. The method according to claim 15, wherein, The conditions for the contact reaction include: The reaction temperature is 120-200℃; and / or The reaction time is 4-16 hours; and / or The mass ratio of 2,5-dimethylfuran to the catalyst is 1-8:1.

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