A method for catalytic oxidation of cyclic olefins

Abstract

This disclosure relates to a method for the catalytic oxidation of cyclic olefins, comprising: contacting cyclic olefins and an oxidant in the presence of a catalyst containing modified nano-carbon-based materials to carry out an oxidation reaction; wherein the modified nano-carbon-based materials are prepared by a method comprising the following steps: (1) placing a graphite rod in a mixture containing starch and water, and electrolyzing it to obtain an electrolyzed starch mixture; (2) removing the solid material from the electrolyzed starch mixture, and then calcining it at 600-1500°C for 1-12 hours in an oxygen-free atmosphere to obtain calcined nano-carbon-based materials; (3) subjecting the calcined nano-carbon-based materials to hydrothermal modification under alkaline conditions. This method can achieve the catalytic oxidation of cyclic olefins under mild conditions and obtain high feed conversion rate and product selectivity.

Description

Technical Field

[0001] This disclosure relates to a method for the catalytic oxidation of cyclic olefins. Background Technology

[0002] Carbon-based materials include carbon nanotubes, activated carbon, graphite, graphene, fullerenes, carbon nanofibers, and nanodiamonds. Scientific research on nanocarbon catalysis began in the 1990s. Studies have shown that the surface chemical properties of nanocarbon materials (mainly carbon nanotubes and graphene) can be flexibly controlled. Functional groups containing oxygen, nitrogen, and other heteroatoms can be modified on their surfaces to impart certain acid-base properties and redox capabilities, thus enabling their direct use as catalyst materials. Researching and developing new catalytic materials related to carbon nanotubes and other nanocarbon materials, and expanding their applications in petrochemicals, fine chemicals, and other fields, has profound theoretical significance and enormous potential application prospects. Summary of the Invention

[0003] The purpose of this disclosure is to provide a method for the catalytic oxidation of cyclic olefins using nano-carbon-based materials as catalysts. This method can achieve the catalytic oxidation of cyclic olefins under mild conditions and obtain high feed conversion and product selectivity.

[0004] To achieve the above objectives, this disclosure provides a method for the catalytic oxidation of cyclic olefins, the method comprising: contacting cyclic olefins and an oxidant in the presence of a catalyst containing modified nano-carbon-based materials to carry out an oxidation reaction;

[0005] The modified carbon nanomaterial is prepared by a method comprising the following steps:

[0006] (1) Place the graphite rod in a mixture containing starch and water, and electrolyze to obtain an electrolyzed starch mixture;

[0007] (2) Take out the solid material from the electrolyzed starch mixture, and then calcine it at 600-1500℃ for 1-12h in an oxygen-free atmosphere to obtain the calcined nano-carbon-based material.

[0008] (3) The calcined nano-carbon-based material is hydrothermally modified under alkaline conditions.

[0009] Optionally, the modified carbon nanomaterial has an average particle size of 20-500 nm.

[0010] Optionally, in step (1), in the mixture containing starch and water, the weight ratio of starch to water is 1:(1-10);

[0011] The electrolysis conditions include: a voltage of 5-30V and a time of 2-10 days.

[0012] Optionally, in step (1), the mixture containing starch and water contains an ammonia source;

[0013] The ammonia source is selected from one or more of ammonia water, urea and hydrazine hydrate;

[0014] Optionally, in the mixture, the weight ratio of the starch to the ammonia source (calculated as a nitrogen-containing compound) is 100:(0.1-500), preferably 100:(5-200).

[0015] Optionally, step (2) includes: removing the solid material from the electrolyzed starch mixture and then calcining it in an oxygen-free atmosphere containing ammonia.

[0016] The calcination conditions include: a temperature of 800-1200℃, a time of 2-8 hours, and a pressure of 0.1-0.5 MPa;

[0017] Optionally, in the ammonia-containing anaerobic atmosphere, the molar fraction of ammonia is 0.1-10 mol%, preferably 0.6-5 mol%.

[0018] Optionally, step (3) includes: mixing the calcined nano-carbon-based material with an alkaline aqueous solution, and then performing the hydrothermal modification;

[0019] The weight ratio of the calcined nano-carbon-based material to water is 1:(1-10);

[0020] The conditions for hydrothermal modification include: a time of 2-24 hours and a temperature of 100-200℃.

[0021] Optionally, the alkaline aqueous solution is an aqueous solution containing an inorganic base;

[0022] The aqueous solution containing inorganic bases includes one or more of sodium hydroxide aqueous solution, potassium hydroxide aqueous solution, calcium hydroxide aqueous solution and ammonia solution;

[0023] Optionally, in the aqueous solution containing the inorganic base, the concentration of the inorganic base is 0.1-20% by weight, preferably 0.5-10% by weight.

[0024] Optionally, the conditions for the oxidation reaction include: a temperature of 30-150℃, a time of 0.1-12h, and a pressure of 0.1-5.0MPa;

[0025] The molar ratio of the cyclic olefin to the oxidant is 1:(0.1-10).

[0026] Optionally, the oxidant is hydrogen peroxide and / or organic peroxide, preferably hydrogen peroxide;

[0027] The cyclic olefin is one or more of substituted or unsubstituted monocyclic olefins of C6-C12 and substituted or unsubstituted bicyclic olefins of C8-C16.

[0028] The substituents in the substituted monocyclic olefin may be the same as or different from the substituents in the substituted bicyclic olefin, and each is independently selected from one or more of halogens and alkyl groups having 1-5 carbon atoms.

[0029] Optionally, the oxidation reaction is carried out in the presence of a solvent, which is one of C1-C6 saturated monohydric alcohols, C3-C6 ketones and C2-C6 nitriles, or a combination of two or three of them.

[0030] Optionally, the solvent is methanol, ethanol, isopropanol, acetone, butanone, or acetonitrile, or a combination of two or three of them.

[0031] Optionally, based on 100 mL of the cyclic olefin, and calculated based on the modified nano-carbon-based material contained in the catalyst, the amount of the catalyst is 20-2000 mg, preferably 50-200 mg.

[0032] Optionally, the weight hourly space velocity of the cycloolefin is 0.1-100 h⁻¹. -1 Preferably 0.5-50h -1 .

[0033] Through the above technical solution, the method disclosed herein electrolyzes an aqueous mixture containing starch, and then calcines the resulting solid under an oxygen-free atmosphere and performs hydrothermal modification under alkaline conditions to obtain modified nano-carbon-based materials. These materials can achieve catalytic oxidation of cyclic olefins under mild conditions and obtain high raw material conversion rate and product selectivity.

[0034] Other features and advantages of this disclosure will be described in detail in the following detailed description section. Detailed Implementation

[0035] The following provides a detailed description of specific embodiments of this disclosure. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit this disclosure.

[0036] This disclosure provides a method for the catalytic oxidation of cyclic olefins, the method comprising: contacting cyclic olefins and an oxidant in the presence of a catalyst containing modified nano-carbon-based materials to carry out an oxidation reaction;

[0037] The modified carbon nanomaterial is prepared by a method comprising the following steps:

[0038] (1) Place the graphite rod in a mixture containing starch and water, and electrolyze to obtain an electrolyzed starch mixture;

[0039] (2) Take out the solid material from the electrolyzed starch mixture, and then calcine it at 600-1500℃ for 1-12h in an oxygen-free atmosphere to obtain the calcined nano-carbon-based material.

[0040] (3) The calcined nano-carbon-based material is hydrothermally modified under alkaline conditions.

[0041] According to one embodiment of this disclosure, step (1) is carried out under normal temperature and pressure conditions with stirring, wherein the normal temperature is 25±5℃ and the normal pressure is 0.101±0.01MPa.

[0042] The modified nano-carbon-based material used in the method disclosed herein has superior catalytic performance, enabling the catalytic oxidation of cyclic olefins under relatively mild conditions, thereby achieving higher conversion rates and target product selectivity. The target product of this disclosure is epoxide cycloalkanes.

[0043] According to one embodiment of this disclosure, the catalyst is preferably 100% modified nano-carbon-based material.

[0044] In this disclosure, the specifications and types of starch are conventional and no specific requirements are made. That is, any existing common starch of any specification and type can achieve the technical solution of this disclosure.

[0045] According to one embodiment of this disclosure, the average particle size of the modified carbon nanomaterial is 20-500 nm, preferably 40-100 nm.

[0046] According to one embodiment of the present disclosure, in step (1), the weight ratio of starch to water in the mixture containing water and starch is 1:(1-10).

[0047] According to one embodiment of this disclosure, in step (1), the electrolysis conditions include: a voltage of 5-30V and a time of 2-10 days.

[0048] According to one embodiment of this disclosure, in step (1), the mixture containing starch and water contains an ammonia source; wherein, the ammonia source can be, for example, one or more of ammonia water, urea, and hydrazine hydrate; in the mixture, the weight ratio of starch to ammonia source can vary within a wide range, for example, the weight ratio of starch to ammonia source based on nitrogen-containing compounds can be 100:(0.1-500), preferably 100:(5-200), wherein, when the ammonia source is ammonia water, "ammonia source based on nitrogen-containing compounds" refers to the amount of ammonia source based on the weight of NH3; when the ammonia source is urea, "ammonia source based on nitrogen-containing compounds" refers to the amount of ammonia source based on the weight of urea; when the ammonia source is hydrazine hydrate, "ammonia source based on nitrogen-containing compounds" refers to the amount of ammonia source based on the weight of N2H4.

[0049] According to one embodiment of this disclosure, step (2) includes: removing the solid material from the electrolyzed starch mixture, and then calcining it in an oxygen-free atmosphere containing ammonia; wherein, ammonia can be directly introduced into the oxygen-free atmosphere to obtain an oxygen-free atmosphere containing ammonia, or ammonia water can be introduced into the oxygen-free atmosphere, and the ammonia water is heated to form a gaseous state to obtain an oxygen-free atmosphere containing ammonia. The molar fraction of ammonia in the oxygen-free atmosphere containing ammonia can vary in a wide range, for example, it can be 0.1-10 mol%, preferably 0.6-5 mol%; the introduction of ammonia can obtain modified carbon nanomaterials with better performance, and can further improve the conversion rate of raw materials and the selectivity of the target product.

[0050] According to a preferred embodiment of this disclosure, the modified carbon nanomaterial is prepared by a method comprising the following steps:

[0051] (1) Place the graphite rod in a mixture containing ammonia source, starch and water, and electrolyze it at 5-30V for 2-10 days to obtain the electrolyzed starch mixture.

[0052] (2) Take out the solid material from the electrolyzed starch mixture, and then calcine it at 600-1500℃ for 1-12h in an oxygen-free atmosphere containing ammonia to obtain the calcined nano-carbon-based material.

[0053] (3) The calcined nano-carbon-based material is hydrothermally modified under alkaline conditions.

[0054] According to one embodiment of this disclosure, in step (1), the size of the graphite rod is not specifically limited. In one specific embodiment, the diameter of the graphite rod is 2-20 mm and the length is 2-100 cm. During electrolysis, the graphite rod is perpendicular to the electrolyte surface, and a certain distance needs to be maintained between the graphite rods. The distance can vary within a wide range, for example, 1-20 cm.

[0055] In this disclosure, there are no special restrictions on the amount of the mixture used, which can be adjusted according to the material and size of the conductive material and the electrolysis conditions.

[0056] In this disclosure, the method for removing solid material from the electrolyzed starch mixture in step (2) is a conventional solid-liquid separation method in the art, such as filtration, centrifugation, etc.; step (2) also includes: drying the removed solid material and then calcining it in an oxygen-free atmosphere; wherein, the drying method can be any conventional method of drying materials, such as placing the material in a drying oven for drying, with conditions including: time of 1-48h and temperature of 60-200℃.

[0057] In this disclosure, the oxygen-free atmosphere can be an inert gas atmosphere or an atmosphere with an oxygen content of less than 2% by volume. The inert gas contained in the inert gas atmosphere can be one or more of nitrogen, argon and helium.

[0058] According to one embodiment of this disclosure, calcination is an operation well known to those skilled in the art, for example, it can be carried out in a muffle furnace or a tube furnace. The calcination temperature in an oxygen-free atmosphere can be 800-1200°C, the calcination time is 2-8 hours, and the calcination pressure can be 0.1-0.5 MPa.

[0059] According to one embodiment of this disclosure, step (3) includes: mixing the calcined nano-carbon-based material with an alkaline aqueous solution, and then performing the hydrothermal modification; the weight ratio of the calcined nano-carbon-based material to the alkaline aqueous solution is 1:(1-10); the conditions for hydrothermal modification include: time of 2-24h, temperature of 100-200℃, and the hydrothermal modification can be carried out under autogenous pressure.

[0060] According to one embodiment of this disclosure, the alkaline aqueous solution is an aqueous solution containing an inorganic base; the aqueous solution containing an inorganic base includes one or more of sodium hydroxide aqueous solution, potassium hydroxide aqueous solution, calcium hydroxide aqueous solution and ammonia water; preferably, sodium hydroxide aqueous solution and / or potassium hydroxide aqueous solution; in the aqueous solution containing an inorganic base, the concentration of the inorganic base is 0.1-20% by weight, preferably 0.5-10% by weight.

[0061] In this disclosure, the oxidation reaction can be carried out in any conventional catalytic reactor, such as a batch reactor, a fixed-bed reactor, a moving-bed reactor, a suspended-bed reactor, or a slurry-bed reactor.

[0062] According to one embodiment of this disclosure, the catalytic oxidation reaction is carried out in a slurry bed reactor, such as a high-pressure reactor. Based on 100 mL of the cycloolefin, the amount of the catalyst is 20-2000 mg, preferably 50-200 mg, calculated based on the modified nano-carbon-based material contained in the catalyst.

[0063] According to one embodiment of this disclosure, the catalytic oxidation reaction is carried out in a fixed-bed reactor, and the weight hourly space velocity (WHSV) of the cycloolefins can be 0.1-100 h⁻¹. -1 Preferably 0.5-50h -1 More preferably 1-20h -1 .

[0064] According to one embodiment of this disclosure, the conditions for the oxidation reaction include: a temperature of 30-150°C, a time of 0.1-12 h, and a pressure of 0.1-5.0 MPa; preferably, the temperature is 50-90°C, the time is 2-8 h, and the pressure is 0.1-2.5 MPa; the oxidation reaction can be carried out under stirring conditions to make the reaction more complete.

[0065] In this disclosure, the molar ratio of cyclic olefin to oxidant can vary within a wide range. According to one embodiment of this disclosure, the molar ratio of cyclic olefin to oxidant is 1:(0.1-10), preferably 1:(0.5-6).

[0066] In this disclosure, the oxidant may be, for example, hydrogen peroxide and / or organic peroxides, preferably hydrogen peroxide.

[0067] In this disclosure, the cyclic olefin is one or more of substituted or unsubstituted monocyclic olefins of C6-C12 and substituted or unsubstituted bicyclic olefins of C8-C16; the substituents in the substituted monocyclic olefins may be the same as or different from the substituents in the substituted bicyclic olefins, and each is independently selected from one or more of halogens and alkyl groups having 1-5 carbon atoms, such as methyl, ethyl, n-propyl, fluorine, chlorine, bromine, etc.; the cyclic olefin may be, for example, cyclohexene.

[0068] To improve the mixing degree between reactants, according to one embodiment of this disclosure, the oxidation reaction is carried out in the presence of a solvent, which can be any liquid substance capable of promoting the dissolution of reactants. Specifically, the solvent is one of C1-C6 saturated monohydric alcohols, C3-C6 ketones, and C2-C6 nitriles, or a combination of two or three of them. Examples of solvents include methanol, ethanol, isopropanol, acetone, butanone, or acetonitrile, or a combination of two or three of them. The amount of solvent used can be selected according to actual needs, and will not be elaborated further here.

[0069] The present invention will be further illustrated by the following examples, but the present invention is not limited thereto.

[0070] All reagents used in this invention are commercially available analytical grade reagents. Unless otherwise specified, they are all purchased commercially, with starch purchased from Anaiji Chemical.

[0071] In the preparation examples, the average particle size of the modified carbon nanomaterials was determined using FEI's TECNAIG standard. 2 The measurements were performed using an F20 (200kV) transmission electron microscope. The test conditions were as follows: accelerating voltage 20kV, sample preparation using the suspension method, placing the sample in a 2mL glass bottle, dispersing it with anhydrous ethanol, shaking it evenly, taking one drop with a dropper and dropping it onto a 3mm diameter sample grid, letting it dry, placing it in the sample injector, and then inserting it into the electron microscope for observation. 100 particles were randomly selected for particle size statistics.

[0072] Preparation Example 1

[0073] Modified carbon nanomaterial A1 was prepared using the following steps:

[0074] (1) Under normal temperature and pressure and with stirring, add 500 mL of ammonia solution with a mass concentration of 5% to a beaker, and then add an appropriate amount of starch to obtain a mixture containing starch, ammonia source and water.

[0075] In the mixture, the weight ratio of starch to water is 1:9.5, and the weight ratio of starch to ammonia source is 100:50. Two identical graphite rods (12 mm in diameter and 35 cm in length) are placed in the mixture, with a distance of 10 cm between them. The graphite rods are connected to the positive and negative terminals of a DC power supply, respectively, and an electrolysis of 25 V is applied for 4 days to obtain the electrolyzed starch mixture.

[0076] (2) The electrolyzed starch mixture was filtered, and the resulting solid was dried at 120°C for 12 hours. Then, ammonia was introduced into the nitrogen atmosphere, where the molar ratio of nitrogen to ammonia was 95:5. The solid was calcined in the nitrogen-ammonia atmosphere for 3 hours at a pressure of 0.12 MPa and a temperature of 1100°C to obtain the calcined nano-carbon-based material.

[0077] (3) After calcining the nano-carbon-based material, it was mixed with 2 times the mass of ammonia solution with a concentration of 5% by weight, and then hydrothermally treated at 180°C under self-generated pressure for 12 hours to obtain modified nano-carbon-based material A1 with an average particle size of 50 nm.

[0078] Preparation Example 2

[0079] Modified nano-carbon-based material A2 was prepared using the method of Example 1, except that in step (2), the calcination temperature was 700℃ and the time was 12h, and the average particle size of modified nano-carbon-based material A2 was 25nm.

[0080] Preparation Example 3

[0081] Modified nano-carbon-based material A3 was prepared using the method of Example 1. The difference is that in step (2), the calcination temperature was 1250℃ and the time was 1h, and the average particle size of nano-carbon-based material A3 was 130nm.

[0082] Preparation Example 4

[0083] Modified nano-carbon-based material A4 was prepared using the method of Example 1. The difference is that in step (2), the material was calcined only in a nitrogen atmosphere, that is, ammonia was not introduced during the calcination process. The average particle size of nano-carbon-based material A4 was 70 nm.

[0084] Preparation Example 5

[0085] Modified nano-carbon-based material A5 was prepared using the method of Example 1, except that in step (1), the same mass of water was used instead of the ammonia solution; the average particle size of nano-carbon-based material A5 was 100 nm.

[0086] Preparation Example 6

[0087] Modified nano-carbon-based material A6 was prepared using the method of Example 1, except that in step (1), the same mass of water was used instead of the ammonia solution; in step (2), the material was calcined only in a nitrogen atmosphere, i.e., no ammonia was introduced during the calcination process, and the average particle size of nano-carbon-based material A6 was 30 nm.

[0088] Preparation Example 7

[0089] The modified nano-carbon-based material A7 was prepared using the method of Example 1, except that in step (3), a sodium hydroxide aqueous solution with a concentration of 5% by weight was used instead of ammonia aqueous solution at a mass ratio of 4 times; the average particle size of nano-carbon-based material A7 was 90 nm.

[0090] Preparation Example 8

[0091] Modified carbon nanomaterial A8 was prepared using the method described in Example 1, with the difference being:

[0092] In step (1), ammonia water is replaced with hydrazine hydrate. In the mixture, the weight ratio of starch to water is 1:5, and the weight ratio of starch to ammonia source is 100:400. The electrolysis voltage is 5V and the time is 10 days.

[0093] In step (2), the molar ratio of nitrogen to ammonia is 100:8;

[0094] In step (3), the hydrothermal treatment temperature is 110℃ and the time is 4h;

[0095] The modified carbon nanomaterial has an average particle size of 120 nm.

[0096] Preparation of Comparative Example 1

[0097] The modified nano-carbon-based material DA1 was prepared using the method of Example 1. The difference is that steps (1) and (3) were not performed, and the starch was directly subjected to the calcination treatment in step (2). The average particle size of the nano-carbon-based material DA1 was 270 nm.

[0098] Preparation of Comparative Example 2

[0099] The modified nano-carbon-based material DA2 was prepared using the method of Example 1. The difference was that the calcination in step (2) was not performed. That is, the starch mixture after electrolysis in step (1) was filtered, the obtained solid was dried at 120°C for 12 hours, and then the modification treatment in step (3) was performed. The average particle size of the nano-carbon-based material DA2 was 15 nm.

[0100] Preparation of Comparative Example 3

[0101] The modified carbon nanomaterial DA3 was prepared using the method of Example 1, except that step (3) was not performed. The average particle size of the carbon nanomaterial DA3 was 180 nm.

[0102] Preparation of Comparative Example 4

[0103] The modified carbon nanomaterial DA4 was prepared using the method of Example 1, except that the same mass of water was used instead of the ammonia solution in step (3), and the average particle size of the carbon nanomaterial DA4 was 110 nm.

[0104] Preparation of Comparative Example 5

[0105] The modified nano-carbon-based material DA5 was prepared using the method of Example 1. The difference is that steps (1) and (2) were not performed, and starch was directly modified in step (3). The average particle size of the nano-carbon-based material DA5 was 18 nm.

[0106] Preparation of Comparative Example 6

[0107] The modified nano-carbon-based material DA6 was prepared using the method of Example 1. The difference is that step (1) was omitted, and the starch was directly subjected to the calcination treatment in step (2) and the modification in step (3). The average particle size of the nano-carbon-based material DA6 was 190 nm.

[0108] The examples illustrate the method for catalytic oxidation of cyclic olefins using the modified nano-carbon-based materials of the present invention. Comparative examples illustrate the method for catalytic oxidation of cyclic olefins using catalytic materials different from those of the present invention; the results are listed in Table 1.

[0109] In the following examples and comparative examples, gas chromatography (GC: Agilent, 7890A) and gas chromatography-mass spectrometry (GC-MS: Thermo Fisher Trace ISQ) were used to analyze the oxidation products.

[0110] The following formulas are used to calculate the raw material conversion rate and the target product selectivity, respectively:

[0111] Cyclic olefin conversion % = (molar amount of cyclic olefin added before reaction - molar amount of cyclic olefin remaining after reaction) / molar amount of cyclic olefin added before reaction × 100%;

[0112] Target product selectivity % = (molar amount of target product generated after reaction) / molar amount of cyclic olefin added before reaction × 100%.

[0113] Example 1

[0114] 50 mg of modified carbon nanomaterial A1 was added as a catalyst, along with 20 mL of cyclohexene and 100 mL of acetone, to a 250 mL high-pressure reactor. Then, 1.5 times the molar amount of cyclohexene in a 30% aqueous solution of hydrogen peroxide was added dropwise with stirring. After the addition was complete, the mixture was stirred at 60 °C and 0.1 MPa for 5 h for oxidation reaction. After cooling and depressurization, the modified carbon nanomaterial was separated by centrifugation and filtration, and the oxidation products were analyzed. The results are listed in Table 1.

[0115] Examples 2-8

[0116] Examples 2-8 were carried out using the same method as in Example 1 for the catalytic oxidation of cyclohexene, the only difference being that modified nano-carbon-based materials A2-A8 were used as catalysts in Examples 2-8. The results are listed in Table 1.

[0117] Example 9

[0118] The catalytic oxidation of cyclohexene was carried out using the method of Example 1, except that acetone was not added. The results are listed in Table 1.

[0119] Example 10

[0120] The catalytic oxidation of cyclohexene was carried out using the method of Example 1, except that the reaction temperature was 80°C, the pressure was 0.5 MPa, the time was 3 h, and the amount of catalyst used was 100 mg. The results are listed in Table 1.

[0121] Example 11

[0122] The catalyst of Example 1 was used in a fixed-bed reactor for the catalytic oxidation of cyclohexene. The specific steps were as follows: The reaction was carried out in a small fixed-bed microreactor. 2g of catalyst was placed in the isothermal zone of the fixed-bed reactor, with quartz sand packed both above and below. The reactor was heated to a reaction temperature of 60°C and held at that temperature for 1 hour. The cyclohexene was fed at a molar ratio of 1:1.5 to hydrogen peroxide under a pressure of 0.2 MPa, with a weight hourly space velocity (WHSV) of 5 h⁻¹ for cyclohexene. -1 The results of the reaction after 2 hours are listed in Table 1.

[0123] Comparative Examples 1-6

[0124] The catalytic oxidation of cyclohexene was carried out using the same method as in Example 1, except that the nano-carbon-based materials prepared in Comparative Examples 1-6 were used as catalysts.

[0125] Table 1

[0126]

[0127]

[0128] As shown in Table 1, the method disclosed herein can carry out the catalytic oxidation of cycloolefins such as cyclohexene under mild conditions, and can significantly improve the conversion rate of cyclohexene and the selectivity of the target product cyclohexane oxide.

[0129] The preferred embodiments of this disclosure have been described in detail above. However, this disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this disclosure, various simple modifications can be made to the technical solutions of this disclosure, and these simple modifications all fall within the protection scope of this disclosure.

[0130] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.

[0131] Furthermore, various different embodiments of this disclosure can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content disclosed in this disclosure.

Claims

1. A method for the catalytic oxidation of cyclic olefins, characterized in that, The method includes: contacting a cycloolefin and an oxidant in the presence of a catalyst containing modified nano-carbon-based materials to carry out an oxidation reaction; The modified carbon nanomaterial is prepared by a method comprising the following steps: (1) Place the graphite rod in a mixture containing starch and water, and electrolyze to obtain an electrolyzed starch mixture; (2) Take out the solid material from the electrolyzed starch mixture, and then calcine it at 600-1500℃ for 1-12h in an oxygen-free atmosphere to obtain the calcined nano-carbon-based material; (3) The calcined nano-carbon-based material is hydrothermally modified under alkaline conditions.

2. The method according to claim 1, wherein, The modified carbon nanomaterial has an average particle size of 20-500 nm.

3. The method according to claim 1, wherein, In step (1), in the mixture containing starch and water, the weight ratio of starch to water is 1:(1-10). The electrolysis conditions include: a voltage of 5-30V and a time of 2-10 days.

4. The method according to claim 1, wherein, In step (1), the mixture containing starch and water contains an ammonia source.

5. The method according to claim 4, wherein, The ammonia source is selected from one or more of ammonia water, urea and hydrazine hydrate.

6. The method according to claim 4, wherein, In the mixture, the weight ratio of the starch to the ammonia source (calculated as a nitrogen-containing compound) is 100:(0.1-500).

7. The method according to claim 4, wherein, In the mixture, the weight ratio of the starch to the ammonia source (calculated as a nitrogen-containing compound) is 100:(5-200).

8. The method according to claim 1, wherein, Step (2) includes: taking out the solid material from the electrolyzed starch mixture and then calcining it in an oxygen-free atmosphere containing ammonia. The calcination conditions include: a temperature of 800-1200℃, a time of 2-8 hours, and a pressure of 0.1-0.5 MPa.

9. The method according to claim 8, wherein, In the oxygen-free atmosphere containing ammonia, the mole fraction of ammonia is 0.1-10 mol.

10. The method according to claim 8, wherein, In the oxygen-free atmosphere containing ammonia, the molar fraction of ammonia is 0.6-5 mol.

11. The method according to claim 1, wherein, Step (3) includes: mixing the calcined nano-carbon-based material with an alkaline aqueous solution, and then performing the hydrothermal modification; The weight ratio of the calcined nano-carbon-based material to water is 1:(1-10). The conditions for hydrothermal modification include: a time of 2-24 hours and a temperature of 100-200℃.

12. The method according to claim 11, wherein, The alkaline aqueous solution is an aqueous solution containing an inorganic base; The aqueous solution containing inorganic bases includes one or more of the following: sodium hydroxide aqueous solution, potassium hydroxide aqueous solution, calcium hydroxide aqueous solution, and ammonia solution.

13. The method according to claim 12, wherein, In the aqueous solution containing the inorganic base, the concentration of the inorganic base is 0.1-20% by weight.

14. The method according to claim 12, wherein, In the aqueous solution containing the inorganic base, the concentration of the inorganic base is 0.5-10% by weight.

15. The method according to claim 1, wherein, The conditions for the oxidation reaction include: a temperature of 30-150℃, a time of 0.1-12h, and a pressure of 0.1-5.0MPa; The molar ratio of the cyclic olefin to the oxidant is 1:(0.1-10).

16. The method according to claim 1, wherein, The oxidant is hydrogen peroxide and / or organic peroxide; The cyclic olefin is one or more of substituted or unsubstituted monocyclic olefins of C6-C12 and substituted or unsubstituted bicyclic olefins of C8-C16. The substituents in the substituted monocyclic olefin may be the same as or different from the substituents in the substituted bicyclic olefin, and each is independently selected from one or more halogens and alkyl groups having 1-5 carbon atoms.

17. The method according to claim 1, wherein, The oxidant is hydrogen peroxide.

18. The method according to claim 1, wherein, The oxidation reaction is carried out in the presence of a solvent, which is one of a C1-C6 saturated monohydric alcohol, a C3-C6 ketone, and a C2-C6 nitrile, or a combination of two or three of them.

19. The method according to claim 18, wherein, The solvent is methanol, ethanol, isopropanol, acetone, butanone, or acetonitrile, or a combination of two or three of them.

20. The method according to claim 1, wherein, Based on 100 mL of the cyclic olefin, and considering the modified nano-carbon-based material contained in the catalyst, the amount of the catalyst is 20-2000 mg.

21. The method according to claim 1, wherein, Based on 100 mL of the cyclic olefin, and considering the modified nano-carbon-based material contained in the catalyst, the amount of the catalyst is 50-200 mg.

22. The method according to claim 1, wherein, The weight hourly space velocity of the cycloolefin is 0.1-100 h⁻¹. -1 .

23. The method according to claim 1, wherein, The weight hourly space velocity of the cycloolefin is 0.5-50 h⁻¹. -1 .

Images