A modified copper-based metal-organic framework material, its preparation method, and its application in the catalytic oxidation rearrangement of cyclohexanone to prepare ε-caprolactone

Abstract

The present invention provides a modified copper-based metal-organic framework material, a preparation method thereof, and an application thereof in the catalytic oxidation rearrangement of cyclohexanone to prepare ε-caprolactone, belonging to the technical fields of material preparation and chemical engineering. The present invention combines the crystallization method and the post-synthesis modification method to replace the hydrogen atom of the meta-carbon-hydrogen bond of the benzene ring in the trimesic acid ligand with a halogen atom (Cl, Br or I), and prepares a halogen-modified copper-based metal-organic framework material and applies it to the catalytic Baeyer-Villiger oxidation rearrangement reaction of cyclohexanone to prepare ε-caprolactone in an oxygen-benzaldehyde system. The catalyst preparation conditions of the present invention are simple, the catalyst has high catalytic activity and excellent cyclic stability performance, and has high selectivity for caprolactone and high utilization rate of the sacrificial agent benzaldehyde in the reaction.

Description

Technical Field

[0001] The present invention relates to the technical fields of material preparation and chemical engineering, and particularly relates to a modified copper-based metal-organic framework material, a preparation method thereof, and an application thereof in the catalytic oxidation rearrangement of cyclohexanone to prepare ε-caprolactone. Background Art

[0002] As an important chemical intermediate, ε-caprolactone is mainly used for synthesizing polycaprolactone, polycaprolactone polyol, and polycaprolactone polyurethane. At present, the industrial production of ε-caprolactone mainly adopts the cyclohexanone Baeyer-Villiger (B-V) oxidation rearrangement process, and the oxidant used is peroxyacid (usually peracetic acid or peroxypropionic acid). In the industrial production process, the high-concentration hydrogen peroxide required for preparing peroxyacid, and peroxyacid itself have great potential safety hazards during storage, transportation, and reaction, and a certain amount of waste acid is also produced as a by-product.

[0003] Compared with peroxyacid, the cyclohexanone B-V oxidation rearrangement process using oxygen or air as the oxidant and aldehyde (usually benzaldehyde) as the sacrificial agent has the advantages of safe and easy availability of raw materials, mild reaction conditions, and high reaction selectivity. Patents CN102391238A, CN103467434A, CN103450144A, and CN104003971A use metal phthalocyanine and metal porphyrin as catalysts respectively, and the reaction conditions are mild, but they are limited by the high cost of catalyst use, and the catalysts also have the defects of poor stability and difficult recycling. Patent CN105237507A coats divalent copper magnetic nano-Fe3O4 spheres and TiO2-P25 on MCM-41 as the catalyst, and Patent CN104592192A uses copper chloride or supported copper chloride as the catalyst. Both can completely convert cyclohexanone in the catalytic reaction, but the preparation process of the high-performance catalysts involved is relatively complex, and limited by the weak oxidation ability of molecular oxygen, most catalysts need to have a large molar ratio of benzaldehyde to cyclohexanone in the feed to obtain a high ε-caprolactone yield, and the utilization efficiency of the sacrificial agent benzaldehyde is low. Summary of the Invention

[0004] The purpose of the present invention is to provide a modified copper-based metal-organic framework material, a preparation method thereof, and an application thereof in the catalytic oxidation rearrangement of cyclohexanone to prepare ε-caprolactone.

[0005] In order to achieve the above-mentioned invention purpose, the present invention provides the following technical solutions:

[0006] The present invention provides a preparation method of a modified copper-based metal-organic framework material, comprising the following steps:

[0007] Mix a copper metal salt, trimesic acid, and a first solvent, and carry out a crystallization reaction to obtain a copper-based metal-organic framework material;

[0008] The copper-based metal-organic framework material is calcined and activated to obtain the activated copper-based metal-organic framework material;

[0009] The activated copper-based metal-organic framework material, a modifier, and a second solvent are mixed to carry out a modification reaction to obtain a modified copper-based metal-organic framework material;

[0010] The modifier includes tetrabutylammonium chloride, ammonium chloride, tetrabutylammonium bromide, ammonium bromide, tetrabutylammonium iodide, or ammonium iodide, and the mass ratio of the copper-based metal-organic framework material to the modifier is 1:0.6 to 1; the temperature of the modification reaction is 25 to 60 °C, and the time is 20 to 28 h.

[0011] Preferably, the copper metal salt includes one or more of copper nitrate trihydrate, copper sulfate, copper acetate, and copper chloride; the molar ratio of the copper metal salt to trimesic acid in the feeding is 1:1 to 3:1;

[0012] The first solvent includes one or more of N,N-dimethylformamide, methanol, ethanol, and water.

[0013] Preferably, the temperature of the crystallization reaction is 80 to 120 °C, and the time is 12 to 24 h.

[0014] Preferably, the temperature of the calcination activation is 150 to 200 °C, and the time is 8 to 16 h.

[0015] Preferably, the second solvent includes methanol, ethanol, or water.

[0016] The present invention provides a modified copper-based metal-organic framework material prepared by the above preparation method.

[0017] The present invention provides an application of the above modified copper-based metal-organic framework material in the catalytic oxidation rearrangement of cyclohexanone to prepare ε-caprolactone. The method of the application includes the following steps: benzaldehyde, cyclohexanone, the modified copper-based metal-organic framework material, and an organic solvent are mixed, oxygen or air is introduced, and an oxidation reaction is carried out to obtain ε-caprolactone.

[0018] Preferably, the molar ratio of benzaldehyde to cyclohexanone in the feeding is 0.5 to 2.5:1; the organic solvent includes 1,2-dichloroethane, 1,4-dioxane, acetonitrile, or ethyl acetate.

[0019] Preferably, the pressure of the oxygen or air is 0.2 to 0.6 MPa; the temperature of the oxidation reaction is 40 to 70 °C, and the time is 4 to 9 h.

[0020] Advantages of the present invention:

[0021] The present invention mixes a copper metal salt, trimesic acid, and a first solvent, and obtains a copper-based metal-organic framework material through a crystallization reaction; then, it continues to calcine and activate the obtained material, mixes the activated copper-based metal-organic framework material, a halogen-containing modifier, and a second solvent, and conducts a modification reaction to obtain a modified copper-based metal-organic framework material.

[0022] In the present invention, hydrogen atoms on the meta-carbon of the benzene ring in the trimesic acid ligand are replaced by halogens (Cl, Br, I), causing local charge delocalization of the ligand, changing the charge distribution of the active center Cu in the copper-based metal-organic framework material, and increasing the proportion of Cu + / Cu 2+ in the material, thereby enhancing the strength and quantity of its Lewis acid sites, which is beneficial to the activation of cyclohexanone and the highly selective formation of ε-caprolactone in the catalytic reaction. Compared with the prior art, the modified copper-based metal-organic framework material prepared by the present invention as a catalyst has excellent catalytic activity and cycle stability, significantly improves the utilization efficiency of the sacrificial agent benzaldehyde in the catalytic reaction, and the catalyst preparation method is simple, having application prospects. Description of the Drawings

[0023] Figure 1 In [the figure], a is the electron microscope image of Br-HKUST-1 obtained in Example 1, Figure 1 in [the figure], b is the element distribution map of Br-HKUST-1 obtained in Example 1, Figure 1 in [the figure], c is the Br element distribution map of Br-HKUST-1 obtained in Example 1, Figure 1 in [the figure], d is the Cu element distribution map of Br-HKUST-1 obtained in Example 1, Figure 1 in [the figure], e is the O element distribution map of Br-HKUST-1 obtained in Example 1, Figure 1 in [the figure], f is the C element distribution map of Br-HKUST-1 obtained in Example 1;

[0024] Figure 2 In [the figure], (a) is the XPS full spectrum of Br-HKUST-1 obtained in Example 1 and HKUST-1 obtained in Comparative Example 1, Figure 2 in [the figure], (b) is the C1s spectrum of Br-HKUST-1 in Example 1 and HKUST-1 in Comparative Example 1, Figure 2 in [the figure], (c) is the O1s spectrum of Br-HKUST-1 in Example 1 and HKUST-1 in Comparative Example 1, Figure 2 in [the figure], (d) is the Cu 2p spectrum of Br-HKUST-1 in Example 1 and HKUST-1 in Comparative Example 1. Detailed Embodiments

[0025] The present invention provides a preparation method of a modified copper-based metal-organic framework material, including the following steps:

[0026] Mix a copper metal salt, trimesic acid, and a first solvent, and conduct a crystallization reaction to obtain a copper-based metal-organic framework material;

[0027] Calcine and activate the copper-based metal-organic framework material to obtain an activated copper-based metal-organic framework material;

[0028] Mix the activated copper-based metal-organic framework material, a modifier, and a second solvent, and conduct a modification reaction to obtain a modified copper-based metal-organic framework material;

[0029] The modifier includes tetrabutylammonium chloride, ammonium chloride, tetrabutylammonium bromide, ammonium bromide, tetrabutylammonium iodide, or ammonium iodide. The mass ratio of the copper-based metal-organic framework material to the modifier is 1:0.6 - 1; the temperature of the modification reaction is 25 - 60 °C, and the time is 20 - 28 h.

[0030] Preferably, in the present invention, weigh a copper metal salt and trimesic acid, add them to the first solvent respectively, stir until completely dissolved to obtain a copper salt solution and a trimesic acid solution, mix the two solutions, transfer them to a hydrothermal reactor, and conduct a crystallization reaction to obtain a copper-based metal-organic framework material.

[0031] In the present invention, the copper metal salt preferably includes one or more of copper nitrate trihydrate, copper sulfate, copper acetate, and copper chloride, and more preferably includes copper sulfate; the molar ratio of the copper metal salt to trimesic acid in the feed is preferably 1:1 - 3:1, and more preferably 2:1 - 3:1.

[0032] In the present invention, the first solvent preferably includes one or more of N,N-dimethylformamide, methanol, ethanol, and water, and more preferably includes N,N-dimethylformamide or methanol; the volume of the first solvent in the present invention is not specifically limited and can be adjusted according to requirements.

[0033] In the present invention, the temperature of the crystallization reaction is preferably 80 - 120 °C, more preferably 90 - 100 °C, the time is preferably 12 - 24 h, and more preferably 16 - 20 h.

[0034] After the crystallization reaction is completed, preferably, wait for it to cool to room temperature, centrifuge the obtained solid product, wash it alternately with water and ethanol, and then dry it to obtain a copper-based metal-organic framework material (denoted as HKUST-1); the number of times of alternate washing in the present invention is not specifically limited, and preferably 3 times in the examples of the present invention.

[0035] In the present invention, the drying temperature is preferably 80 - 100 °C, more preferably 85 - 90 °C.

[0036] The present invention preferably places the copper-based metal-organic framework material in an open crucible bowl and calcines and activates it in a muffle furnace to obtain the activated metal-organic framework material.

[0037] In the present invention, the temperature of the calcination activation is preferably 150-200 °C, more preferably 175-180 °C, and the time is preferably 8-16 h, more preferably 12-16 h; the purpose of calcining and activating the copper-based metal-organic framework material is to remove the residual solvent molecules and unreacted organic ligands in the pores.

[0038] The present invention preferably cools the activated copper-based metal-organic framework material to room temperature, quickly transfers it to a 100 mL flat-bottom flask, adds it together with a modifier to a second solvent and stirs. After mixing evenly, a modification reaction is carried out to obtain a modified copper-based metal-organic framework material;

[0039] The modifier includes tetrabutylammonium chloride, ammonium chloride, tetrabutylammonium bromide, ammonium bromide, tetrabutylammonium iodide or ammonium iodide, and the mass ratio of the copper-based metal-organic framework material to the modifier is 1:0.6-1; the temperature of the modification reaction is 25-60 °C, and the time is 20-28 h.

[0040] In the present invention, the modifier preferably includes tetrabutylammonium chloride, ammonium chloride, tetrabutylammonium bromide, ammonium bromide, tetrabutylammonium iodide or ammonium iodide, more preferably includes tetrabutylammonium bromide; the mass ratio of the copper-based metal-organic framework material to the modifier is 1:0.6-1, more preferably 1:0.8-1.

[0041] In the present invention, the second solvent preferably includes methanol, ethanol or water, more preferably includes methanol; the present invention does not make special limitations on the volume of the second solvent, as long as the modification reaction can proceed smoothly.

[0042] In the present invention, the temperature of the stirring is preferably 25-100 °C, more preferably 25-60 °C, and the time is preferably 24 h.

[0043] In the present invention, the temperature of the modification reaction is preferably 25-60 °C, more preferably 30-50 °C, and the time is preferably 20-28 h, more preferably 24 h.

[0044] After the modification reaction is completed, the present invention preferably carries out vacuum filtration on the product obtained from the modification reaction. The separated solid product is washed alternately with water and ethanol and then dried in vacuum to obtain the modified copper-based metal-organic framework material; the present invention does not make special limitations on the number of alternate washings, and it is preferably 3 times in the examples of the present invention.

[0045] In the present invention, the temperature of the vacuum drying is preferably 70-90 °C, more preferably 80-90 °C, the time is preferably 20-28 h, and more preferably 24 h.

[0046] The present invention provides a modified copper-based metal-organic framework material prepared by the above preparation method.

[0047] The present invention provides an application of the above modified copper-based metal-organic framework material in the catalytic oxidation rearrangement of cyclohexanone to prepare ε-caprolactone. The method of the application includes the following steps: mixing benzaldehyde, cyclohexanone, the modified copper-based metal-organic framework material with an organic solvent, introducing oxygen or air, and performing an oxidation reaction to obtain ε-caprolactone.

[0048] In the present invention, the molar ratio of the charged benzaldehyde to cyclohexanone is preferably 0.5-2.5:1, more preferably 2:1.

[0049] In the present invention, the organic solvent preferably includes 1,2-dichloroethane, 1,4-dioxane, acetonitrile or ethyl acetate, and more preferably includes 1,2-dichloroethane.

[0050] In the present invention, the pressure of the oxygen or air is preferably 0.2-0.6 MPa, more preferably 0.2-0.4 MPa.

[0051] In the present invention, the temperature of the oxidation reaction is preferably 40-70 °C, more preferably 55-65 °C, the time is preferably 4-9 h, and more preferably 5-7 h.

[0052] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the protection scope of the present invention. Example 1

[0053] Weigh 2.51 g of copper sulfate and add it to 48 mL of methanol, stir and dissolve at room temperature to obtain a copper sulfate solution; weigh 1.72 g of trimesic acid and add it to 48 mL of N,N-dimethylformamide, stir and dissolve at room temperature to obtain a trimesic acid solution;

[0054] Mix the copper sulfate solution and the trimesic acid solution, transfer them to a hydrothermal reactor, place the hydrothermal reactor in an oven at 90 °C for 16 h for crystallization reaction. After the reaction is completed, wait for it to cool to room temperature. The obtained solid product is centrifuged, washed alternately with water and absolute ethanol 3 times, and then placed in an oven at 85 °C for drying for later use to obtain a modified copper-based metal-organic framework material (denoted as HKUST-1 material);

[0055] Weigh 0.5 g of HKUST-1 material, place it in an open crucible bowl, and calcine and activate it in a muffle furnace at 150 °C for 12 h;

[0056] After drying is completed, cool it to room temperature. Quickly transfer the activated HKUST-1 material to a 100 mL flat-bottom flask, mix it with 30 mL of methanol and 0.30 g of tetrabutylammonium bromide, stir at 25 °C for 24 h to carry out the modification reaction. After the reaction is completed, filter the obtained product under reduced pressure, wash it alternately with absolute ethanol and water 3 times, dry it in a vacuum at 70 °C for 24 h, weigh it for standby, and obtain the modified copper-based metal-organic framework material (denoted as Br-HKUST-1). Example 2

[0057] Weigh 3.14 g of copper acetate and add it to 48 mL of N,N-dimethylformamide, stir and dissolve it at room temperature to obtain a copper acetate solution; weigh 1.72 g of trimesic acid and add it to 48 mL of ethanol, stir and dissolve it at room temperature to obtain a trimesic acid solution;

[0058] Mix the copper acetate solution and the trimesic acid solution, transfer them to a hydrothermal kettle, place the hydrothermal kettle in an oven at 100 °C for 20 h to carry out the crystallization reaction. After the reaction is completed, wait for it to cool to room temperature. The obtained solid product is centrifuged, washed alternately with water and absolute ethanol 3 times, and then placed in an oven at 90 °C for drying for standby to obtain the HKUST-1 material;

[0059] Weigh 0.5 g of HKUST-1 material, place it in an open crucible bowl, and calcine and activate it in a muffle furnace at 175 °C for 12 h;

[0060] After drying is completed, cool it to room temperature. Quickly transfer the activated HKUST-1 material to a 100 mL flat-bottom flask, mix it with 30 mL of ethanol and 0.40 g of ammonium iodide, stir at 60 °C for 24 h to carry out the modification reaction. After the reaction is completed, filter the obtained product under reduced pressure, wash it alternately with absolute ethanol and water 3 times, dry it in a vacuum at 80 °C for 24 h, weigh it for standby, and obtain the modified copper-based metal-organic framework material (denoted as I-HKUST-1). Example 3

[0061] Weigh 2.11 g of copper chloride and add it to 48 mL of water, stir and dissolve it at room temperature to obtain a copper chloride solution; weigh 1.72 g of trimesic acid and add it to 48 mL of methanol, stir and dissolve it at room temperature to obtain a trimesic acid solution;

[0062] Mix the copper chloride solution and the trimesic acid solution, transfer them to a hydrothermal kettle, place the hydrothermal kettle in an oven at 120 °C for 24 h to carry out the crystallization reaction. After the reaction is completed, wait for it to cool to room temperature. The obtained solid product is centrifuged, washed alternately with water and absolute ethanol 3 times, and then placed in an oven at 100 °C for drying for standby to obtain the HKUST-1 material;

[0063] Weigh 0.5 g of HKUST-1 material, place it in an open crucible bowl, and calcine and activate it in a muffle furnace at 200 °C for 12 h;

[0064] After drying, cool it to room temperature. Quickly transfer the activated HKUST-1 material to a 100 mL flat-bottom flask, mix it with 30 mL of water and 0.40 g of ammonium chloride, stir at 40 °C for 24 h for the modification reaction. After the reaction, filter the obtained product under reduced pressure, wash it alternately with ethanol and water 3 times, and dry it in a vacuum at 90 °C for 24 h. Weigh and reserve it to obtain the modified copper-based metal-organic framework material (denoted as Cl-HKUST-1). Example 4

[0065] Weigh 3.8 g of copper nitrate trihydrate and add it to 48 mL of water. Stir and dissolve it at room temperature to obtain a copper nitrate solution; weigh 1.72 g of trimesic acid and add it to 48 mL of absolute ethanol. Stir and dissolve it at room temperature to obtain a trimesic acid solution;

[0066] Mix the copper nitrate solution and the trimesic acid solution, transfer them to a hydrothermal reactor, place the hydrothermal reactor in an oven at 80 °C and keep it for 12 h for the crystallization reaction. After the reaction, wait for it to cool to room temperature. The obtained solid product is centrifuged, washed alternately with water and absolute ethanol 3 times, and then dried in an oven at 80 °C to obtain HKUST-1 material;

[0067] Weigh 0.5 g of HKUST-1 material, place it in an open crucible bowl, and calcine and activate it in a muffle furnace at 180 °C for 12 h;

[0068] After drying, cool it to room temperature. Quickly transfer the activated HKUST-1 material to a 100 mL flat-bottom flask, mix it with 30 mL of methanol and 0.40 g of ammonium bromide, stir at 25 °C for 24 h for the modification reaction. After the reaction, separate the solid, wash it alternately with absolute ethanol and water 3 times, and dry it in a vacuum at 70 °C for 24 h to obtain the modified copper-based metal-organic framework material, denoted as Br-HKUST-1(0.8:1), where 0.8:1 is the mass ratio of HKUST-1 material to ammonium bromide. Example 5

[0069] The difference from Example 4 is only that:

[0070] The feeding amount of ammonium bromide is changed from 0.40 g to 0.25 g; Br-HKUST-1(0.5:1) is obtained.

[0071] Comparative Example 1

[0072] Weigh 3.8 g of copper nitrate trihydrate and add it to 48 mL of water. Stir and dissolve it at room temperature to obtain a copper nitrate solution; weigh 1.72 g of trimesic acid and add it to 48 mL of absolute ethanol. Stir and dissolve it at room temperature to obtain a trimesic acid solution.

[0073] Mix the copper nitrate solution and the trimesic acid solution, transfer them to a hydrothermal reactor, and place the hydrothermal reactor in an 80 °C oven for 12 h to carry out the crystallization reaction.

[0074] After the crystallization reaction is completed, wait for it to cool to room temperature. The obtained solid product is centrifuged, washed alternately with water and absolute ethanol 3 times, and then placed in an 80 °C oven for drying for later use to obtain a copper-based metal-organic framework material (HKUST-1).

[0075] Characterization and performance testing

[0076] 1. Observe the Br-HKUST-1 obtained in Example 1 using a transmission electron microscope. The results are shown in Figure 1 .

[0077] As Figure 1 shown in a, it can be observed that Br-HKUST-1 has a regular octahedral morphology structure; Figure 1 b in is the element distribution map of Br-HKUST-1 obtained in Example 1. Figure 1 c in, Figure 1 d in, Figure 1 e in and Figure 1 f in are respectively the Br element distribution map, Cu element distribution map, O element distribution map, and C element distribution map of Br-HKUST-1 obtained in Example 1. It can be clearly observed that the Br, Cu, O, and C elements are evenly distributed.

[0078] 2. Use X-ray photoelectron spectroscopy to scan Br-HKUST-1 obtained in Example 1 and HKUST-1 obtained in Comparative Example 1 to obtain Figure 2 (a) in. After carbon charge correction and peak fitting, obtain Figure 2 (b) in, Figure 2 (c) in and Figure 2 (d) in.

[0079] As Figure 2 (a) shown, both Br-HKUST-1 and HKUST-1 contain C, O, and Cu elements; as Figure 2 (b) shown, compared with HKUST-1, the center of the C1s characteristic peak of Br-HKUST-1 shifts towards the lower binding energy direction. Substituting the hydrogen atom of the meta-carbon-hydrogen bond in the benzene ring of the ligand (trimesic acid) with a halogen (Br) causes local charge delocalization of the ligand; as Figure 2As shown in Fig. (c), the proportion of the peak area of M-O (metal-oxygen bond) in Br-HKUST-1 decreases, indicating that the local charge delocalization of the ligand weakens the strength of the metal-oxygen bond; as Figure 2 shown in Fig. (d), substituting the hydrogen atom of the meta-carbon-hydrogen bond of the benzene ring in the ligand (trimesic acid) with a halogen (Br) causes local charge delocalization of the ligand, weakens the strength of the metal-oxygen bond, changes the charge distribution of the active center Cu in the copper-based metal-organic framework material, and increases the proportion of Cu + / Cu 2+ in the material.

[0080] 3. Test Example 1:

[0081] Add 25 mg of the catalysts obtained in Examples 1 to 3 and Comparative Example 1, 2 mmol of cyclohexanone, 2 mmol (1.0 equivalent) of benzaldehyde, and 5 mL of 1,2-dichloroethane into a micro high-pressure reactor respectively, and carry out the Baeyer-Villiger oxidation rearrangement reaction of cyclohexanone under the conditions of 50 °C, 6 h, and 0.3 MPa O2. After the reaction is completed, cool it to room temperature, centrifuge the reaction product to separate the catalyst, and collect the reaction solution.

[0082] Use gas chromatography to quantitatively analyze the contents of each component in the product, and calculate the conversion rate of cyclohexanone, the selectivity of ε-caprolactone, the conversion rate of benzaldehyde, and the aldehyde utilization rate under different catalysts. The aldehyde utilization rate is calculated by dividing the molar amount of ε-caprolactone generated by the molar amount of benzaldehyde consumed. The results are shown in Table 1.

[0083]

[0084] Combined with Table 1, Examples 1 to 3 and Comparative Example 1, it can be seen that the copper-based metal-organic framework materials modified by halogens (Cl, Br, I) significantly improve the selectivity of ε-caprolactone and the utilization rate of benzaldehyde compared with those before modification, and the modification effect of Br is relatively the best.

[0085] 4. Test Example 2:

[0086] Add 25 mg of the catalysts obtained in Examples 1 to 3, 2 mmol of cyclohexanone, 2 mmol (1.0 equivalent) of benzaldehyde, and 5 mL of 1,2-dichloroethane into a micro high-pressure reactor respectively, and carry out the Baeyer-Villiger oxidation rearrangement reaction of cyclohexanone under different oxidation reaction conditions. After the reaction is completed, cool it to room temperature, centrifuge the reaction product to separate the catalyst, and collect the reaction solution.

[0087] The content of each component in the product was quantitatively analyzed by gas chromatography, and the conversion rate of cyclohexanone, the selectivity of ε-caprolactone, the conversion rate of benzaldehyde and the aldehyde utilization rate of the reaction under different oxidation reaction conditions were calculated. The results are shown in Table 2.

[0088]

[0089] As can be seen from Table 2, the halogen (Cl, Br, I)-modified copper-based metal-organic framework materials have good reaction performance and benzaldehyde utilization rate when applied to the Baeyer-Villiger oxidation rearrangement reaction of cyclohexanone. The increase of temperature, time and reaction pressure is beneficial to the improvement of the conversion rate of cyclohexanone.

[0090] 5. Test Example 3:

[0091] 25 mg of the Br-HKUST-1(0.8:1) catalyst obtained in Example 4 and the Br-HKUST-1(0.5:1) catalyst obtained in Example 5, 2 mmol of cyclohexanone, 2 mmol (1.0 equivalent) of benzaldehyde and 5 mL of 1,2-dichloroethane were respectively added into a micro high-pressure reactor, and the Baeyer-Villiger oxidation rearrangement reaction of cyclohexanone was carried out under the conditions of 50 °C, 6 h and 0.3 MPa O2. After the reaction, it was cooled to room temperature, the reaction product was centrifuged to separate the catalyst, and the reaction solution was collected.

[0092] The content of each component in the product was quantitatively analyzed by gas chromatography, and the conversion rate of cyclohexanone, the selectivity of ε-caprolactone, the conversion rate of benzaldehyde and the aldehyde utilization rate of the reaction with different bromine-modified copper-based metal-organic framework materials as catalysts were calculated. The results are shown in Table 3.

[0093]

[0094] As can be seen from Table 3, the reaction efficiency and product selectivity of the oxidation reaction under the action of the Br-HKUST-1(0.8:1) catalyst are better than those of the Br-HKUST-1(0.5:1) catalyst. The conversion rate of cyclohexanone is 72.9%, the selectivity of ε-caprolactone is 94.8%, the conversion rate of benzaldehyde is 90.1%, and the aldehyde utilization rate reaches 0.77.

[0095] 6. Test Example 4:

[0096] 25 mg of the Br-HKUST-1(0.8:1) catalyst obtained in Example 4, 2 mmol of cyclohexanone, different molar amounts of benzaldehyde, and 5 mL of 1,2-dichloroethane were respectively added to a micro high-pressure reactor, and the Baeyer-Villiger oxidation rearrangement reaction of cyclohexanone was carried out under the oxidation reaction conditions of 55 °C, 6 h, and 0.3 MPa O₂. After the reaction, it was cooled to room temperature, the reaction product was centrifuged to separate the catalyst, and the reaction solution was collected.

[0097] The contents of each component in the product were quantitatively analyzed by gas chromatography, and the conversion rate of cyclohexanone, the selectivity of ε-caprolactone, the conversion rate of benzaldehyde, and the aldehyde utilization rate of the reaction under different molar amounts of benzaldehyde were calculated. The results are shown in Table 4.

[0098]

[0099] As can be seen from Table 4, when using the bromine-modified copper-based metal-organic framework material as the catalyst, at a low aldehyde-ketone stoichiometric ratio (0.5 - 1.5), the reaction has a high aldehyde utilization rate (0.6 - 1); when the aldehyde-ketone stoichiometric ratio is greater than or equal to 2, cyclohexanone can be completely converted and the yield of ε-caprolactone reaches more than 90%.

[0100] 7. Test Example 5:

[0101] 25 mg of the Br-HKUST-1(0.8:1) catalyst obtained in Example 4, 2 mmol of cyclohexanone, 2 mmol (1.0 equivalent) of benzaldehyde, and 5 mL of 1,2-dichloroethane were added to a micro high-pressure reactor, and the Baeyer-Villiger oxidation rearrangement reaction of cyclohexanone was carried out cyclically under the conditions of 50 °C, 6 h, and 0.3 MPa O₂ for the catalyst cycle stability test. After the reaction, it was cooled to room temperature, the reaction product was centrifuged to separate the catalyst, and the reaction solution was collected.

[0102] The contents of each component in the product were quantitatively analyzed by gas chromatography, and the conversion rate of cyclohexanone, the selectivity of ε-caprolactone, the conversion rate of benzaldehyde, and the aldehyde utilization rate of the reaction under different cycle numbers were calculated. The results are shown in Table 5.

[0103]

[0104] As can be seen from Table 5, the modified copper-based metal-organic framework material in the present invention has good cycle stability when applied to the catalytic Baeyer-Villiger oxidation rearrangement of cyclohexanone to prepare ε-caprolactone.

[0105] As can be seen from the above embodiments and test examples, the present invention provides a modified copper-based metal-organic framework material. After being modified with halogens (Cl, Br, I), the selectivity of ε-caprolactone and the utilization rate of benzaldehyde are significantly improved. Among them, the bromine-modified catalyst has the best effect, and the feeding amount ratio of the copper-based metal-organic framework material to the halogen-containing modifier is preferably 0.6 to 1:1. The modified copper-based metal-organic framework material obtained by the present invention has excellent catalytic activity and cyclic stability as a catalyst, and significantly improves the utilization efficiency of the sacrificial agent benzaldehyde in the catalytic reaction.

[0106] The above description is only a preferred embodiment of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. Application of a modified copper-based metal-organic framework material in the catalytic oxidation rearrangement of cyclohexanone to prepare ε-caprolactone, characterized in that, The method of the application includes the following steps: mixing benzaldehyde, cyclohexanone, the modified copper-based metal-organic framework material with an organic solvent, introducing oxygen or air, and carrying out an oxidation reaction to obtain ε-caprolactone; The preparation method of the modified copper-based metal-organic framework material includes the following steps: Mixing a copper metal salt, trimesic acid, and a first solvent, and carrying out a crystallization reaction to obtain a copper-based metal-organic framework material; Calcining and activating the copper-based metal-organic framework material to obtain an activated copper-based metal-organic framework material; Mixing the activated copper-based metal-organic framework material, a modifier, and a second solvent, and carrying out a modification reaction to obtain a modified copper-based metal-organic framework material; The modifier includes tetrabutylammonium chloride, ammonium chloride, tetrabutylammonium bromide, ammonium bromide, tetrabutylammonium iodide, or ammonium iodide. The mass ratio of the copper-based metal-organic framework material to the modifier is 1:0.6 - 1; the temperature of the modification reaction is 25 - 60 °C, and the time is 20 - 28 h.

2. The application according to claim 1, wherein The copper metal salt includes one or more of copper nitrate trihydrate, copper sulfate, copper acetate, and copper chloride; the molar ratio of the copper metal salt to trimesic acid in the feed is 1:1 - 3:1; The first solvent includes one or more of N,N-dimethylformamide, methanol, ethanol, and water.

3. The application according to claim 1, characterized in that The temperature of the crystallization reaction is 80 - 120 °C, and the time is 12 - 24 h.

4. The application according to claim 1, wherein The temperature of the calcination activation is 150 - 200 °C, and the time is 8 - 16 h.

5. The application according to claim 1, wherein The second solvent includes methanol, ethanol, or water.

6. The application according to claim 1, characterized in that, The molar ratio of benzaldehyde to cyclohexanone in the feed is 0.5 - 2.5:1; the organic solvent includes 1,2-dichloroethane, 1,4-dioxane, acetonitrile, or ethyl acetate.

7. The application according to claim 6, characterized in that The pressure of the oxygen or air is 0.2 - 0.6 MPa; the temperature of the oxidation reaction is 40 - 70 °C, and the time is 4 - 9 h.

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