Hydrophobically modified MOFs material containing perfluoroalkyl chain and application of hydrophobic modified MOFs material as catalyst in preparation of KA oil by catalyzing cyclohexane oxidation

Abstract

The invention relates to a hydrophobic modified MOFs (Metal-Organic Frameworks) material containing a perfluoroalkyl chain and application of the hydrophobic modified MOFs material as a catalyst in catalyzing cyclohexane oxidation to prepare KA oil. According to the hydrophobic modified MOFs material containing the perfluoroalkyl chain, MOFs with grafting active sites are used as a substrate, PSM functionalization is carried out on the MOFs and perfluorinated anhydride through a nucleophilic substitution reaction between acyloxy and amino, and the hydrophobic MOFs material containing the perfluoroalkyl chain is obtained. The prepared MOFs material has good hydrophobic performance, and can effectively improve the conversion rate of catalytic cyclohexane oxidation reaction and the selectivity of the product KA oil in a more environment-friendly manner.

Description

Technical Field

[0001] The present invention relates to the technical field of catalysts, and particularly relates to a perfluoroalkyl chain-containing hydrophobic modified MOFs material, a preparation method thereof, and an application as a catalyst in the oxidation of cyclohexane to KA oil. Background Art

[0002] The partial oxidation of hydrocarbons is an important process in chemical production. The selective aerobic oxidation of cyclohexane is one of the typical examples. Industrial production usually needs to be carried out under high temperature (120°C - 165°C) and high pressure (1 MPa - 2 MPa) conditions, obtaining a mixture of cyclohexanol (CyOH, A), cyclohexanone (Cy=O, K) (KA oil), and other complex substances. Among them, cyclohexanone can be further oxidized to adipic acid and caprolactam monomers, which are important raw materials for the extensive production of nylon-6 and nylon-66. In addition, cyclohexanone is also widely used in industries such as coatings, pesticides, dyes, and lubricants, and is an important petrochemical raw material.

[0003] Considering that KA oil is prone to deep oxidation, resulting in the formation of undesirable by-products, problems such as high raw material consumption, aggravated environmental pollution, low conversion rate and selectivity are caused, which is contradictory to the initially required high activation energy to activate the C-H bond. The selective oxidation of cyclohexane under mild and highly energy-saving conditions is one of the biggest problems in the petrochemical industry. Currently, many catalysts have been developed. However, the recoverability of homogeneous catalysts such as cobalt / manganese carboxylates is difficult, leading to high metal leaching. Therefore, it is very urgently needed to design a heterogeneous catalyst for selectively inserting a carbon-hydrogen bond to oxidize cyclohexane under mild conditions.

[0004] Metal-organic frameworks (MOFs) are a new type of crystalline porous material with an extended structure formed by the ordered combination of metal cations / clusters and organic building units. They are widely used in various fields such as battery gas separation and storage, vapor adsorption, catalysis, chemical sensing, and biomedical applications. The crystal arrangement is periodic and can be characterized by X-ray diffraction. The properties of active centers, their spatial network, the organic groups and positions regulated by the surrounding environment, and the overall pore structure can be controlled at the angstrom level. MOFs are regarded as efficient heterogeneous catalysts. However, most porous MOFs are moisture-sensitive or strongly hydrophilic, and surface wettability greatly affects the selectivity and conversion of the cyclohexane oxidation reaction. Fortunately, significant progress has been made in the preparation of hydrophobic MOFs and MOF-derived materials in the past few years. By changing the chemical composition to regulate the pore environment, the favorable non-covalent interactions between the framework surface and specific guest molecules can be maximally enhanced, showing unique advantages as catalysts for various reactions. So far, there are mainly two strategies for preparing hydrophobic MOFs, including the single synthesis method and the post-synthesis modification method (PSM). Studies have shown that cerium exhibits relatively excellent catalytic activity in the field of catalytic applications compared with other metals, but there are few reports on its hydrophobic MOFs.

[0005] The above-mentioned viewpoints have prompted us to rationally design and prepare a heterogeneous MOF catalyst with excellent hydrophobicity, high activity, high stability, and environmental friendliness. Summary of the Invention

[0006] The technical solution of the present invention is as follows. A hydrophobic modified MOF material containing a perfluoroalkyl chain is prepared by using a MOF with grafting active sites as a substrate and performing PSM functionalization with perfluoroanhydride through the nucleophilic substitution reaction between an acyloxy group and an amino group to obtain a hydrophobic MOF material containing a perfluoroalkyl chain.

[0007] For the above-mentioned hydrophobic modified MOF material containing a perfluoroalkyl chain, the perfluoroanhydride is pentafluoropropionic anhydride or heptafluorobutyric anhydride.

[0008] For the preparation method of the above-mentioned hydrophobic modified MOF material containing a perfluoroalkyl chain, the MOF material is activated. Take the activated MOF material in a reaction flask, add acetonitrile, deionized water, and disperse it by ultrasonic wave. Then add perfluoroanhydride and stir the reaction under nitrogen protection. After cooling to room temperature, centrifuge and separate. The obtained product is washed several times with acetonitrile and dried overnight to obtain the product of the hydrophobic modified MOF material containing a perfluoroalkyl chain.

[0009] For the above-mentioned preparation method, the activation is carried out under vacuum conditions at 423K for 12h.

[0010] For the above-mentioned preparation method, the stirring reaction is carried out under constant temperature conditions at 80°C for 24h.

[0011] Use of the above-mentioned perfluoroalkyl chain-containing hydrophobically modified MOF material as a catalyst in the reaction of catalytic oxidation of cyclohexane to KA oil.

[0012] The above application uses the above-mentioned perfluoroalkyl chain-containing hydrophobically modified MOF material as a catalyst, and in the presence and absence of a solvent respectively, uses TBHP as an initiator and fills O2 as an oxidant to catalyze the oxidation of cyclohexane to KA oil.

[0013] The above application is carried out as follows: Using a 25 mL Schlenk tube as the reaction device, take cyclohexane, the activated perfluoroalkyl chain-containing hydrophobically modified MOF material as a catalyst, add acetonitrile or not add acetonitrile as a solvent, tert-butyl hydroperoxide TBHP as an initiator, seal it, introduce O2 gas into it, perform gas displacement three times repeatedly, and carry out heating and stirring reaction.

[0014] In the above application, the reaction time is 6 h - 14 h and the reaction temperature is 70 °C.

[0015] In the above application, catalyst: cyclohexane: TBHP = 0.01 mmol: 0.5 mL: 0.5 mL, or catalyst: acetonitrile: cyclohexane: TBHP = 0.01 mmol: 1 mL: 1 mL: 0.5 mL.

[0016] The beneficial effects of the present invention are as follows: The hydrophobically modified MOF material prepared by the present invention realizes efficient catalytic aerobic oxidation of cyclohexane to KA oil under mild conditions. The experimental results will provide new ideas and methods for the design and synthesis of hydrophobic MOF and its porous materials and the activation of C-H bond cleavage to achieve hydrocarbon oxidation under mild conditions. The raw materials of the present invention are easily available, the preparation process is simple and rapid, and the application catalytic conditions are green and environmentally friendly. Therefore, it has environmental-friendly catalytic research value and broad application potential. Description of the Drawings

[0017] Figure 1 It is the PXRD diffraction pattern of the hydrophobically modified MOF material of the present invention.

[0018] Figure 2 It is the FR-IT spectrum of the hydrophobically modified MOF material of the present invention.

[0019] Figure 3 It is the SEM map of the hydrophobically modified MOF material of the present invention.

[0020] Figure 4 It is the XPS spectrum of the hydrophobically modified MOF material of the present invention, where a is the elemental content spectrum and b is Ce

[0021] 3D spectrum. Spectrum c is the C1s spectrum of Ce-UiO-66-NH2, spectrum d is the O1s spectrum of Ce-UiO-66-NH2, spectrum e is the F1s spectrum of Ce-UiO-66-NH2, and spectrum f is the N1s spectrum of Ce-UiO-66-NH2.

[0022] Spectrum f is the N1s spectrum of Ce-UiO-66-NH2.

[0023] Figure 5 is the N2 adsorption-desorption isotherm curve of the hydrophobic modified MOFs material of the present invention.

[0024] Figure 6 is the contact angle test diagram of the hydrophobic modified MOFs material of the present invention.

[0025] Figure 7 is the schematic diagram of the reaction of the hydrophobic modified MOFs material of the present invention for catalytic oxidation of cyclohexane to KA oil.

[0026] Figure 8 is the change of the conversion rate of the hydrophobic modified MOFs material of the present invention for catalytic oxidation of cyclohexane without solvent and the selectivity of KA oil obtained with the reaction time.

[0027] Figure 9 is the schematic diagram for comparing the recycling performance of the hydrophobic modified MOFs material of the present invention as a catalyst. Detailed implementation mode

[0028] Example 1 Hydrophobic modified MOFs material

[0029] The reaction formula is as follows:

[0030]

[0031] (I) The preparation method is as follows:

[0032] 1. Prepare the initial MOFs material (Ce-UiO-66-NH2).

[0033] According to the reported method for the rapid preparation of Ce-UiO-66-NH2, dissolve (NH4)2Ce(NO3)6 (0.9 g, 1.698 mmol) in a beaker containing 9 mL of water (23 °C, solution 1); dissolve H2BDC-NH2 (0.9 g, 4.968 mmol) in a beaker containing DMF (solution 2). Use an ultrasonic bath (240 W) to ultrasonically treat solutions 1 and 2 for 20 min to obtain a transparent solution. A third solution, solution 3: Add 90 mL of deionized water to a three-necked flask and heat it to 55 °C in an oil bath. Mix 18 mL of acetic acid and 6 mL of potassium hydroxide (10 M) and then add them; stir for five minutes, and then add solutions 1 and 2 simultaneously. Immediately, a brown precipitate appears. Continuously stir for twenty minutes. The color of the precipitate of Ce-BDC-NH2 is dark brown, and the yield is 58%. Let the mixture stand to room temperature, resulting in stratification. Pour off the supernatant and centrifuge (8000 rpm for 1 minute) to separate the precipitate. Wash the solid product with acetone 3 times and dry it overnight in air at 85 °C.

[0034] 2. Preparation of hydrophobic modified MOFs materials (Ce-UiO-66-F5, Ce-UiO-66-F7).

[0035] 1) Preparation of Ce-UiO-66-F5

[0036] The above-mentioned initial MOFs material is activated under vacuum conditions at 423 K for 12 h. Take 512 mg of the above-activated MOFs in a reaction flask, add 17.5 mL of acetonitrile and 2.5 mL of deionized water, disperse ultrasonically, add 232.5 μL of pentafluoropropionic anhydride, and under nitrogen protection, place it in an oil bath at 80 °C and stir at a constant temperature for 24 h. After cooling to room temperature, centrifuge and separate. Wash the obtained product with acetonitrile several times and dry it overnight under vacuum at 80 °C to obtain the product Ce-UIO-66-F5.

[0037] 2) Preparation of Ce-UiO-66-F7

[0038] The above-mentioned initial MOFs material is activated under vacuum conditions at 423 K for 12 h. Take 512 mg of the above-activated MOFs in a reaction flask, add 17.5 mL of acetonitrile and 2.5 mL of deionized water, disperse ultrasonically, add 307.5 μl of heptafluorobutyric anhydride, and under nitrogen protection, place it in an oil bath at 80 °C and stir at a constant temperature for 24 h. After cooling to room temperature, centrifuge and separate. Wash the obtained product with acetonitrile several times and dry it overnight under vacuum at 80 °C to obtain the product Ce-UiO-66-F7.

[0039] The structure of the superhydrophobic modified MOFs material synthesized in the present invention is as Figures 1-6 shown. The MOF-F xThe morphology of the material shows no obvious change compared with that of the initial MOF.

[0040] The test was carried out using an X-ray diffractometer, and the test results are as Figure 1 shown. In Figure 1 Ce-UiO-66-NH2 and Ce-UiO-66-F5 after grafting with hydrophobic perfluoroalkyl groups, and the structure of Ce-UiO-66-F7 did not change.

[0041] The test was carried out using a Fourier transform infrared spectrometer, and the test results are as Figure 2 shown. FT-IR spectral analysis shows that the stretching bands of N-H and C=O in BDC-NH2 appear at 1660 cm -1 and 3470 cm -1 nearby, and the stretching and bending peaks of the amino group are observed at 3360 cm -1 and 1576 cm -1 . Compared with the initial Ce-UiO-66-NH2, a new characteristic absorption peak appears near 1220 cm -1 for the hydrophobic modified MOFs material, corresponding to the C-N bond of the amide unit. It can be concluded from the FT-IR spectrum that it is feasible to prepare hydrophobic MOF-F x materials by grafting perfluoroalkyl chains on the surface of MOF materials.

[0042] As Figure 3 shown, the SEM images of Ce-UiO-66-NH2, Ce-UiO-66-F5, and Ce-UiO-66-F7 are respectively shown. It can be clearly seen that the morphology of the MOFs material is consistent with the initial MOF size before and after grafting perfluoroalkyl chains, and the modification has no effect on the morphology of the material.

[0043] As Figure 4 shown, XPS tests were used to study the surface chemical composition and elemental chemical state of MOFs before and after hydrophobic modification. It can be seen from the elemental content spectrum (a) that all three MOFs contain four elements: C, N, O, and Ce. Peaks of the F element appear at 688.40 eV and 688.75 eV for Ce-UiO-66-F5 and Ce-UiO-66-F7 respectively, and the elemental contents are 2.54% and 4.40% respectively, which confirms the purity of the samples. It can be observed from the Ce 3d spectrum in Figure (b) that Ce has two valence states. Among them, the XPS spectra in the Ce(IV) 3d 5 / 2 and 3d 3 / 2 regions are divided into 6 components and belong to the formation of Ce(IV) oxygen clusters, which appear between 883 and 917.20 eV; Ce(III) 3d 5 / 2 and 3d 3 / 2The peak was observed between 881.10 eV and 904.28 eV. The C 1s spectrum of Ce-UiO-66-NH2 in Fig. (c) shows three spectral components, corresponding to C═C, C-NH2, and O-C═O groups at 284.80 eV, 285.99 eV, and 288.55 eV respectively, and Ce-UiO-66-F x (x = 5, 7) materials did not show obvious peak shifts. In the O 1s region in Fig. (d), the Ce-O, O-C═O, and -OH groups in the materials correspond to 529.82 eV, 531.18 eV, and 531.78 eV respectively. As shown in Fig. (e), the F 1s spectrum appears at 689.2 eV, and this peak comes from the -F5 and -F7 groups in MOF-F x , proving that the perfluoroalkyl chains were successfully grafted onto the Ce-UiO-66-NH2 framework. Fig. (f) shows the peaks in the N 1s region of the material, which can be divided into three peaks after fitting. The binding energies of 398.75 eV and 399.16 eV belong to the C-N and -NH2 groups in the material respectively. During the grafting of perfluoroalkyl chains with different lengths, due to the conversion of some amino groups and the formation of amide units, the corresponding -NH2 peak shifted slightly, and new N 1s fitting peaks appeared near 401.5 eV

[0044] The adsorption and desorption isotherms of the three MOFs before and after perfluoroalkyl chain grafting are as Figure 5 shown. The BET surface areas of Ce-UiO-66-NH2, Ce-UiO-66-F5, and Ce-UiO-66-F7 are 234 m 2 ·g -1 , 193 m 2 ·g -1 , and 182 m 2 ·g -1 respectively

[0045] As Figure 6 shown, the wettability of the hydrophobic modified MOFs (Ce-UiO-66-F5, Ce-UiO-66-F7) was evaluated by CA contact angle measurement. The water contact angle of Ce-UiO-66-NH2 is about 41.7°, the water contact angle of Ce-UiO-66-F5 is about 95.7°, and the water contact angle of Ce-UiO-66-F7 is about 111.2°. It can be concluded that after perfluoroalkyl chain grafting treatment, the CA contact angles of the two MOF-F x (x = 5, 7) materials both exceed 90°, and according to the definition, the two MOF-F x (x = 5, 7) materials have hydrophobic properties

[0046] Example 2: Catalytic oxidation of cyclohexane to KA oil using perfluoroalkyl chain-containing hydrophobic modified MOFs materials

[0047] Using the hydrophobic modified MOFs material prepared in Example 1 as a catalyst, the oxidation of cyclohexane to KA oil was catalyzed.

[0048] The method is as follows:

[0049] 1) When there is a solvent, the method is as follows:

[0050] First, the prepared catalyst was dried and activated under reduced pressure at 423 K for 12 h to remove solvent molecules such as residual DMF and acetonitrile on the surface of MOFs. The activated catalyst (0.01 mmol), acetonitrile (1 mL), cyclohexane (0.5 mL), and TBHP (0.5 mL) were successively introduced into a 25 ml Schlenk tube. O2 gas was introduced into it, and gas displacement was carried out three times repeatedly to make the entire reaction system filled with O2 gas, and the reaction was heated and stirred at 70 °C for the corresponding time. After the reaction was completed, centrifugal separation was carried out, 30 μl of the supernatant was taken, diluted with 30 μl of MeOH, and 0.4 μl of chlorobenzene was used as an internal standard, and the reaction yield was detected by gas chromatography.

[0051] 2) When there is no solvent, the method is as follows:

[0052] First, the prepared catalyst was dried and activated under reduced pressure at 423 K for 10 h to remove solvent molecules such as residual DMF and acetonitrile on the surface of MOFs. The activated catalyst (0.01 mmol), cyclohexane (0.5 mL), and TBHP (0.5 mL) were successively introduced into a 25 mL Schlenk tube. O2 gas was introduced into it, and gas displacement was carried out three times repeatedly to make the entire reaction system filled with O2 gas, and the reaction was heated and stirred at 70 °C for the corresponding time. After the reaction was completed, centrifugal separation was carried out, 30 μl of the supernatant was taken, diluted with 30 μl of MeOH, and 0.4 μl of chlorobenzene was used as an internal standard, and the reaction yield was detected by gas chromatography. The results are shown in Table 1 and Figures 7-8 as follows.

[0053] Table 1: Catalytic oxidation of cyclohexane to KA oil using two hydrophobic modified MOFs materials and the substrate material

[0054]

[0055] As shown in Table 1, under the conditions of 70 °C, 1 MPa O2 pressure, and 0.5 mL TBHP as the initiator, we used Ce-UiO-66-NH2, Ce-UiO-66-F5, and Ce-UiO-66-F7 as heterogeneous catalysts to catalyze the oxidation of cyclohexane to KA oil under mild conditions. From the results, it can be seen that the catalytic performance of the hydrophobic modified MOFs after grafting with perfluoroalkyl chains (when 1 mL of acetonitrile was used as the solvent, the cyclohexane conversion and KA oil selectivity were 4.34% and 76.89% for Ce-UiO-66-F5, respectively; 8.93% and 72.6% for Ce-UiO-66-F7, respectively. When there was no solvent, the cyclohexane conversion and KA oil selectivity were 9.93% and 89.64% for Ce-UiO-66-F5, respectively; 11.02% and 85.57% for Ce-UiO-66-F7, respectively) were better than those of the original initial MOF (when 1 mL of acetonitrile was used as the solvent, the cyclohexane conversion and KA oil selectivity were 2.99% and 65.72% for Ce-UiO-66-NH2, respectively; when there was no solvent, the cyclohexane conversion and KA oil selectivity were 1.97% and 83.62% for Ce-UiO-66-NH2, respectively). This confirmed that the catalytic performance of the MOF was improved after hydrophobic modification. At the same time, after hydrophobic modification, the conversion rate and KA oil selectivity were more efficient under solvent-free conditions, which could effectively reduce energy consumption.

[0056] In addition, since cyclohexane is hydrophobic, after the MOF material is hydrophobically modified, the low-polar hydrophobic environment near the Ce active site is more conducive to the local adsorption of non-polar cyclohexane, increasing its surface roughness and reducing the surface free energy. This can enhance the aggregation and contact of the catalyst with the substrate, accelerating the efficiency of substrate conversion, and to a certain extent, facilitating the over-oxidation of the reaction products cyclohexanol and cyclohexanone. In addition, through the experimental results, it was found that Ce-UiO-66-F7 showed the best catalytic activity, probably because the hydrophobic property of Ce-UIO-66-F7 was better than that of the other two materials.

[0057] Table 2 Variation of the catalytic oxidation of cyclohexane by hydrophobically modified MOF materials with the amount of substance and reaction temperature

[0058]

[0059] As shown in Table 2, we selected Ce-UiO-66-F7 as the catalyst to study the amount of catalytic substance and reaction temperature of this reaction. We used the method of controlling variables. With other reaction conditions remaining the same, the amounts of the catalyst were set to 0.005 mmol, 0.01 mmol, and 0.015 mmol. As the amount of the catalyst increased, the conversion rate of cyclohexane showed a trend of first increasing and then decreasing. The decrease when 0.015 mmol was added might be due to excessive agglomeration of the catalyst. Also, with other reaction conditions remaining the same, the temperatures were set to 60 °C, 70 °C, and 80 °C. From the two aspects of the conversion rate of cyclohexane and the selectivity of KA oil, we could clearly obtain that 70 °C was the optimal reaction temperature.

[0060] Secondly, we studied the reaction time of the catalyst for this reaction. First, under the condition of no solvent added, 0.01 mmol of the catalyst catalyzed this reaction under the same conditions. As the time was 6 h, 8 h, 10 h, 12 h, and 14 h, the conversion rates of cyclohexane catalyzed by the three catalysts showed a trend of first increasing and then decreasing. The optimal reaction time was 10 h, at which the conversion rate of cyclohexane was the highest. After 10 h, it might be due to the increase in the oxidation rate of KA oil and the decrease in the generation rate. The selectivity of KA oil of the catalyst Ce-UiO-66-NH2 was the highest at 10 h. The selectivity of KA oil corresponding to the catalyst Ce-UiO-66-F5 changed little with the reaction time and was slightly greater than that at other reaction times at 10 h. The selectivity of KA oil of the catalyst Ce-UiO-66-F7 showed a trend of first decreasing and then increasing with the increase of time, and the overall relative change was small. According to the above two aspects of analysis, it could be concluded that 10 h was the optimal reaction time for the three Ce-MOFs.

[0061] Generally speaking, the modified samples showed significantly ideal hydrophobicity compared with the parent Ce-UiO-66-NH2. The low-polarity hydrophobic environment near the Ce active sites was more conducive to the local adsorption of non-polar cyclohexane, effectively avoiding the common incompatibility phenomena in the traditional solvothermal synthesis process. All modified Ce-UiO-66-NH2 showed excellent activity in the selective aerobic oxidation of cyclohexane under mild (70 °C, 0.1 MPa) and solvent-free conditions. Compared with before modification, the conversion rate increased by five times, from 1.97% to 11.02%, exceeding the conversion rate in the industry (about 5%), and the selectivity of KA oil reached more than 85%. Compared with the traditional catalytic method, this method is more green and low-energy, environmentally friendly, can effectively reduce energy consumption, and avoid polluting the environment.

[0062] As Figure 9As shown, the recyclability of Ce-UiO-66-NH2 and hydrophobic Ce-UiO-66-F5 and Ce-UiO-66-F7 materials after perfluoroalkyl chain grafting treatment as catalysts, with cyclohexane (0.5 mL) as the substrate, under an O2 atmosphere at 70 °C and with 0.5 mL TBHP as the initiator, was investigated. After the reaction was completed, the remaining catalyst was recovered by centrifugation, washed several times with MeOH and dried, and then vacuum-activated at 150 °C for 12 h before the next cycle experiment, as Figure 9 shown. After three cycles of experiments, the catalytic activities of the prepared hydrophobic Ce-UiO-66-F5 and Ce-UiO-66-F7 showed almost no loss. The cycle experiments confirmed that the MOF materials had excellent cycle performance and stability before and after perfluoroalkyl chain hydrophobic modification.

Claims

1. Hydrophobically modified MOFs material containing perfluoroalkyl chains, characterized in that: Using MOFs with grafting active sites as the substrate, PSM functionalization was carried out with perfluoroanhydride via the nucleophilic substitution reaction between acyloxy and amino groups to obtain hydrophobic MOF materials containing perfluoroalkyl chains.

2. The perfluoroalkyl chain-containing hydrophobically modified MOFs material according to claim 1, characterized in that: The perfluoroanhydride is pentafluoropropionic anhydride or heptafluorobutyric anhydride.

3. The method for preparing the perfluoroalkyl chain-containing hydrophobically modified MOFs material according to claim 1 or 2, characterized in that: The MOFs material is activated, and the activated MOFs material is put into a reaction bottle, acetonitrile and deionized water are added, and ultrasonic dispersion is performed, and perfluoroanhydride is added. Under nitrogen protection, the reaction is stirred, and after cooling to room temperature, centrifugal separation is performed. The obtained product is washed with acetonitrile several times and dried overnight to obtain a product containing a perfluoroalkyl chain hydrophobically modified MOFs material.

4. The preparation method according to claim 3, characterized in that: The activation is carried out under vacuum conditions at 423K for 12 hours.

5. The preparation method according to claim 3, characterized in that: The stirring reaction is carried out at a constant temperature of 80° C. for 24 hours.

6. Use of the perfluoroalkyl chain-containing hydrophobically modified MOFs material according to claim 1 or 2 as a catalyst in the catalytic oxidation of cyclohexane to produce KA oil.

7. The use according to claim 6, characterized in that: The hydrophobically modified MOFs material containing perfluoroalkyl chains as claimed in claim 1 or 2 is used as a catalyst, and TBHP is used as an initiator and O2 is charged as an oxidant to catalyze the oxidation of cyclohexane to produce KA oil in the presence or absence of a solvent.

8. The use according to claim 7, characterized in that: The method is as follows: use a 25mL Schlenk tube as a reaction device, take cyclohexane, activated perfluoroalkyl chain-containing hydrophobically modified MOFs material as a catalyst, add acetonitrile or no acetonitrile as a solvent, tert-butyl hydroperoxide TBHP as an initiator, seal it, pass O2 gas into it, repeat gas replacement three times, and heat and stir the reaction.

9. The use according to claim 8, characterized in that: The reaction time is 6h-14h, and the reaction temperature is 70°C.

10. The use according to claim 8, characterized in that: catalyst: Cyclohexane: TBHP = 0.01 mmol: 0.5 mL: 0.5 mL, or, catalyst: acetonitrile: cyclohexane: TBHP = 0.01 mmol: 1 mL: 1 mL: 0.5 mL.

Images