A process for the production of adipic acid

Abstract

The application discloses a production method of adipic acid, which comprises the following steps: reacting cyclohexane with an oxygen-containing gas in the presence of a catalyst, a solvent and a reaction aid to generate adipic acid, wherein the catalyst comprises inorganic or organic salts of at least two of group VIII transition metals or the catalyst comprises a mixture of inorganic or organic salts of at least one of group VIII transition metals and inorganic or organic salts of at least one of group VIIB metals, the solvent is selected from at least one of polar protic solvents, and the aid is selected from at least one of organic acid anhydrides. The method can reduce the generation of high-boiling polymers in the production process of adipic acid, make the mother liquor easy to reuse, reduce the production of three wastes, and realize the continuous production of adipic acid.

Description

Technical Field

[0001] This invention belongs to the field of adipic acid production technology, and specifically relates to a method for producing adipic acid. Background Technology

[0002] Adipic acid (AA), also known as fatty acid, has the chemical formula C6H. 10 O4 is an important organic dicarboxylic acid, ranking second in production among all dicarboxylic acids after terephthalic acid. It has a wide range of applications, serving not only as a crucial monomer for nylon and polyurethane but also as a key raw material for the biodegradable plastic PBAT.

[0003] Currently, the main production processes for adipic acid worldwide are the cyclohexane two-step process and the cyclohexene two-step process. The cyclohexane process uses cyclohexane as a raw material, first oxidizing it in air to produce a mixture of cyclohexanol and cyclohexanone (KA oil), then oxidizing the KA oil with nitric acid to obtain adipic acid. This process is relatively complex, with a low single-pass conversion rate of only 3%-6%, producing numerous byproducts and generating significant amounts of industrial waste. While this method requires high investment, it offers the lowest production cost for adipic acid.

[0004] The cyclohexene process, developed by Asahi Kasei Corporation of Japan, uses benzene as a raw material. It involves partial hydrogenation to produce cyclohexene, followed by hydration to produce cyclohexanol, and finally oxidation with nitric acid to produce adipic acid. Compared to the cyclohexane process, this technology has advantages in product yield, energy consumption, and waste treatment. However, it requires significant investment, has high adipic acid production costs, and inevitably generates a large amount of cyclohexane as a byproduct, failing to fundamentally solve the problem of cyclohexane disposal.

[0005] Both of these processes use benzene, hydrogen, and nitric acid as raw materials, and both require nitric acid oxidation in the final step, which corrodes equipment and generates large amounts of nitrogen oxides that pollute the air.

[0006] To address these issues, scientists have explored a greener, more environmentally friendly, and simpler process for synthesizing adipic acid using cyclohexane as a raw material and air or oxygen as an oxidant.

[0007] For example, in the literature Organic Process Research & Development 1998, 2, 255-260, the authors used N-hydroxyphthalimide (NHPI) as a free radical catalyst to directly oxidize cyclohexane with oxygen to obtain adipic acid under the promotion of a small amount of transition metal. The cyclohexane conversion rate was 73% and the adipic acid yield was 53%.

[0008] For example, Chinese patent CN 1231449C (Invention title: Method for preparing adipic acid by biomimetic catalytic oxidation of cyclohexane with oxygen) uses metal porphyrin as a catalyst, which effectively realizes the direct air oxidation of cyclohexane to prepare adipic acid.

[0009] The above cases all achieved efficient conversion of cyclohexane to adipic acid. However, due to the numerous side reactions during the oxidation process, many high-boiling-point impurities were formed, making it impossible to reuse the mother liquor. This not only prevented the continuous production of adipic acid but also caused a large amount of waste problems. Summary of the Invention

[0010] To address the problems in existing technologies where the direct oxidation of cyclohexane to adipic acid generates large amounts of high-boiling-point polymers that are difficult to separate and remove, making it impossible to reuse the mother liquor, resulting in significant waste and hindering continuous adipic acid production, this invention aims to provide a method for producing adipic acid. This method reduces the generation of high-boiling-point polymers during adipic acid production, facilitates mother liquor reuse, reduces waste, and enables continuous adipic acid production.

[0011] Therefore, the first aspect of the present invention provides a method for producing adipic acid, comprising reacting cyclohexane with an oxygen-containing gas in the presence of a catalyst, a solvent, and a reaction promoter to produce adipic acid, wherein the catalyst comprises an inorganic or organic salt of at least two Group VIII transition metals, or the catalyst comprises an inorganic or organic salt of at least one Group VIII transition metal and an inorganic or organic salt of at least one Group VIIB metal, the solvent is selected from at least one polar protic solvent, and the promoter is selected from at least one organic acid anhydride.

[0012] According to some embodiments of the present invention, the inorganic or organic salt is selected from at least one of free carboxylates, organic complexes, and halides.

[0013] According to some embodiments of the present invention, the inorganic or organic salt is an acetate and / or chloride.

[0014] According to some embodiments of the present invention, the Group VIII transition metal is selected from iron, cobalt, nickel, ruthenium, palladium and platinum.

[0015] According to some embodiments of the present invention, the Group VIII transition metal includes cobalt.

[0016] According to some embodiments of the present invention, the Group VIII transition metals include iron and cobalt.

[0017] According to some embodiments of the present invention, the Group VIIB metals include manganese.

[0018] According to some embodiments of the present invention, the catalyst contains at least a cobalt salt. According to the present invention, when the catalyst is a combination of cobalt salt and nickel salt, cobalt salt and manganese salt, or cobalt salt and iron salt, the content of high-boiling-point impurities in the reaction is low. The catalyst exhibits better performance when it is a combination of cobalt salt and nickel salt or cobalt salt and iron salt. Most preferably, the catalyst contains a combination of cobalt salt and iron salt, resulting in an even lower content of high-boiling-point impurities in the reaction and optimal performance.

[0019] According to some preferred embodiments of the present invention, the catalyst is a mixture of cobalt acetate and ferric chloride.

[0020] According to some embodiments of the present invention, the polar protic solvent is selected from at least one of organic polar protic solvents with less than 6 carbon atoms in the molecule.

[0021] According to some preferred embodiments of the present invention, the polar protic solvent includes neutral polar protic solvents and / or acidic polar protic solvents.

[0022] According to some embodiments of the present invention, the neutral polar protic solvent is selected from alcohols, such as fatty alcohols, including but not limited to tert-butanol.

[0023] According to some embodiments of the present invention, the acidic polar protic solvent satisfies 3 ≤ pKa < 7, for example, acetic acid.

[0024] According to some embodiments of the present invention, the reaction aid is selected from C2-C10 organic acid anhydrides.

[0025] According to some embodiments of the present invention, the organic acid anhydride is selected from at least one of the compounds represented by the formula R1-CO-O-CO-R2, wherein R1 and R2 are the same or different, each independently selected from C1-C8 alkyl groups, and R1 and R2 may optionally be connected to -CO-O-CO- groups to form cyclic acid anhydrides.

[0026] According to some embodiments of the present invention, the organic anhydride is selected from acetic anhydride and / or adipic anhydride.

[0027] According to the present invention, when the catalyst includes cobalt and iron and organic acid anhydrides are further added as reaction promoters, the high-boiling-point content in the reaction products is lower, which is beneficial to the continuous synthesis of the reaction and reduces the three wastes of the reaction.

[0028] According to some embodiments of the present invention, the oxygen-containing gas is selected from gases with an oxygen volume content of 5-100%, preferably air.

[0029] According to some embodiments of the present invention, the feed rate of the oxygen-containing gas is 10-100 L / min per 10 moles of cyclohexane.

[0030] According to some embodiments of the present invention, the mass ratio of the catalyst to cyclohexane is 0.001 to 0.1. In some embodiments, the mass ratio of the catalyst to cyclohexane is 0.003 to 0.07.

[0031] According to some embodiments of the present invention, the mass ratio of the reaction aid to the cyclohexane is 0.05 to 1.0.

[0032] According to some embodiments of the present invention, the mass ratio of the solvent to cyclohexane is 1.0 to 10.0.

[0033] According to some embodiments of the present invention, the reaction temperature is 80°C to 120°C.

[0034] According to some embodiments of the present invention, the pressure of the reaction is 1.0 to 3.0 MPa.

[0035] According to some embodiments of the present invention, the reaction time is 1 to 8 hours.

[0036] The method of the present invention can reduce the generation of high-boiling-point polymers during the production of adipic acid, make the mother liquor easy to reuse, reduce the output of waste, and realize the continuous production of adipic acid. Attached Figure Description

[0037] Figure 1 This is a high-performance liquid chromatogram of the synthetic solution obtained in the embodiment of the present invention. Detailed Implementation

[0038] To make the present invention easier to understand, the present invention will be described in detail below with reference to embodiments. These embodiments are only for illustrating the present invention and should not be regarded as limiting the scope of the present invention. Unless otherwise specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Unless otherwise specified, the materials used in the embodiments are commercially available or conventional products prepared by known methods.

[0039] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0040] The data in the embodiments of this invention were obtained using the following testing methods:

[0041] Detection of high-boiling-point impurities in the synthesis solution:

[0042] 1. Take 20.000g of the reaction synthesis solution, put it into a freeze dryer, and freeze dry it for 8 hours under a vacuum of 5Pa and a temperature of -80℃ to remove low-boiling organic matter, and obtain a white solid with a weight of m2 g.

[0043] 2. The white solid was dissolved in water and methanol at a ratio of 90:10 (V / V) using electromagnetic stirring, and detected by high-performance liquid chromatography (HPLC). Chromatographic conditions: ZORBAX SAX 4.6mm × 250mm 5μm column; mobile phase: methanol: 50mmol / L KH₂PO₄: aqueous solution = 5:95 (V / V); column temperature: 25℃; flow rate: 1.0mL / min; injection volume: 20μL; detection wavelength: 210nm. The contents of adipic acid, glutaric acid, and succinic acid in the white solid were determined to be m₃, m₄, and m₅, respectively.

[0044] 3. Calculate the weight of high-boiling-point impurities in the white solid: = m2 - (m3 + m4 + m5), and the content of high-boiling-point impurities in the reaction synthesis solution: = [m2 - (m3 + m4 + m5)] / 20

[0045] Example 1

[0046] Appropriate amounts of cyclohexane, acetic acid, and acetic anhydride (mass ratio of acetic acid to acetic anhydride = 10:1), as well as an acetic acid solution containing ferric chloride and cobalt acetate (mass ratio of ferric chloride to cobalt acetate = 1:1, and the total mass concentration of ferric chloride and cobalt acetate in the acetic acid solution is 5%), were added to the raw material tanks containing cyclohexane, acetic acid, and catalyst. The reaction was carried out using a continuous reactor consisting of two reactors connected in series, each with a volume of 2L. The reaction pressure was set at 1.2MPa, the reaction temperature at 100℃, the stirring speed at 500r / min, the air flow rate at 3L / min, the cyclohexane feed rate at 150g / h, the acetic acid feed rate at 340g / h, and the catalyst solution feed rate at 10g / h. The total residence time of each component in the reactor was 4h. A real-time sampling port and a collection tank were provided at the tail end of the reactor. 20.000 g of the reaction solution from a specific time period was freeze-dried to obtain 0.436 g of a white solid. Liquid phase analysis revealed that this solid contained 0.365 g of adipic acid, 0.021 g of glutaric acid, and 0.010 g of succinic acid. Based on the formula, the weight of the high-boiling-point impurity was 0.04 g, representing 0.20% of the total content in the reaction solution. For ease of comparison, the main experimental conditions and results are listed in Table 1.

[0047] Example 2

[0048] Appropriate amounts of cyclohexane, acetic acid, and adipic anhydride (mass ratio of acetic acid to adipic anhydride = 10:1), as well as an acetic acid solution containing ferric chloride and cobalt acetate (mass ratio of ferric chloride to cobalt acetate = 1:1, total mass concentration of ferric chloride and cobalt acetate in the acetic acid solution is 5%), were added to the raw material tanks containing cyclohexane, acetic acid, and catalyst. The reaction was carried out using a continuous reaction apparatus consisting of two reactors connected in series, each with a volume of 2L. The reaction pressure was set at 1.2MPa, the reaction temperature at 100℃, the stirring speed at 500r / min, the air flow rate at 3L / min, the cyclohexane feed rate at 150g / h, the acetic acid feed rate at 340g / h, and the catalyst solution feed rate at 10g / h. The total residence time of each component in the reactor was 4h. A real-time sampling port and a collection tank were provided at the tail end of the reactor. 20.000 g of the reaction solution from a specific time period was freeze-dried to obtain 0.447 g of a white solid. Liquid phase analysis revealed that this solid contained 0.343 g of adipic acid, 0.031 g of glutaric acid, and 0.012 g of succinic acid. Based on the formula, the weight of the high-boiling-point impurity was 0.061 g, representing 0.31% of the total content in the reaction solution. For ease of comparison, the main experimental conditions and results are listed in Table 1.

[0049] Example 3

[0050] Appropriate amounts of cyclohexane, acetic acid, and acetic anhydride (mass ratio of acetic acid to acetic anhydride = 10:1), as well as an acetic acid solution containing nickel acetate and cobalt acetate (mass ratio of nickel acetate to cobalt acetate = 1:1, and the total mass concentration of nickel acetate and cobalt acetate in the acetic acid solution is 5%), were added to the raw material tanks containing cyclohexane, acetic acid, and catalyst. The reaction was carried out using a continuous reactor consisting of two reactors connected in series, each with a volume of 2L. The reaction pressure was set at 1.2MPa, the reaction temperature at 100℃, the stirring speed at 500r / min, the air flow rate at 3L / min, the cyclohexane feed rate at 150g / h, the acetic acid feed rate at 340g / h, and the catalyst feed rate at 10g / h. The total residence time of each component in the reactor was 4h. A real-time sampling port and a collection tank were provided at the tail end of the reactor. 20.000 g of the reaction solution from a specific time period was freeze-dried to obtain 0.586 g of a white solid. Liquid phase analysis revealed that it contained 0.261 g of adipic acid, 0.037 g of glutaric acid, and 0.019 g of succinic acid. Based on the formula, the weight of the high-boiling-point impurity was 0.269 g, representing 1.35% of the total content in the reaction solution. For ease of comparison, the main experimental conditions and results are listed in Table 1.

[0051] Example 4

[0052] Appropriate amounts of cyclohexane, acetic acid, and acetic anhydride (mass ratio of acetic acid to acetic anhydride = 10:1), and an acetic acid solution containing ferric chloride and cobalt acetate (mass ratio of ferric chloride to cobalt acetate = 1:1, total mass concentration of ferric chloride and cobalt acetate in the acetic acid solution is 5%) were added to the raw material tanks containing cyclohexane, acetic acid, and catalyst, respectively. The reaction was carried out using a continuous reactor consisting of two reactors connected in series, each with a volume of 2L. The reaction pressure was set at 1.2MPa, the reaction temperature at 100℃, the stirring speed at 500r / min, the air flow rate at 3L / min, the cyclohexane feed flow rate at 150g / h, the total feed flow rate of the acetic acid and acetic anhydride solution at 150g / h (of which the acetic anhydride flow rate is approximately 31g / h), and the catalyst acetic acid solution feed flow rate at 200g / h. The total residence time of each component in the reactor was 4h. A real-time sampling port and a collection tank were provided at the tail end of the reactor. 20.000 g of the reaction solution from a specific time period was freeze-dried to obtain 0.656 g of a white solid. Liquid phase analysis revealed that it contained 0.461 g of adipic acid, 0.054 g of glutaric acid, and 0.031 g of succinic acid. Based on the formula, the weight of the high-boiling-point impurity was 0.110 g, and its content in the reaction solution was 0.55%. For ease of comparison, the main experimental conditions and results are listed in Table 1.

[0053] Example 5

[0054] Appropriate amounts of cyclohexane, acetic acid, and acetic anhydride (acetic acid to acetic anhydride mass ratio = 10:1), and an acetic acid solution of manganese acetate and cobalt acetate (manganese acetate to cobalt acetate mass ratio = 1:1, the total mass concentration of manganese acetate and cobalt acetate in the acetic acid solution of manganese acetate and cobalt acetate is 5%) were added to the raw material tanks. The reaction was carried out using a continuous reaction apparatus consisting of two reactors connected in series, each with a volume of 2L. The reaction pressure was set at 1.2MPa, the reaction temperature at 100℃, the stirring speed at 500r / min, the air flow rate at 3L / min, the cyclohexane feed rate at 150g / h, the acetic acid feed rate at 340g / h, and the catalyst solution feed rate at 10g / h. The total residence time of each component in the reactor was 4h. A real-time sampling port and a collection tank were provided at the tail end of the reactor. 20.000 g of the reaction solution from a specific time period was freeze-dried to obtain 0.535 g of a white solid. Liquid phase analysis revealed that it contained 0.313 g of adipic acid, 0.032 g of glutaric acid, and 0.012 g of succinic acid. Based on the formula, the weight of the high-boiling-point impurity was 0.178 g, and its content in the reaction solution was 0.89%. For ease of comparison, the main experimental conditions and results are listed in Table 1.

[0055] Example 6

[0056] Appropriate amounts of cyclohexane, tert-butanol, and acetic anhydride (mass ratio of tert-butanol to acetic anhydride = 10:1) and a tert-butanol solution containing ferric chloride and cobalt acetate (mass ratio of ferric chloride to cobalt acetate = 1:1, total mass concentration of ferric chloride and cobalt acetate in the tert-butanol solution is 5%) were added to the feed tanks. The heating temperature of each feed tank was 50℃. The reaction was carried out using a continuous reaction apparatus consisting of two reactors connected in series, each with a volume of 2L. The reaction pressure was set at 1.2MPa, the reaction temperature at 100℃, the stirring speed at 500r / min, the air flow rate at 3L / min, the cyclohexane feed rate at 150g / h, the tert-butanol feed rate at 340g / h, and the catalyst solution feed rate at 10g / h. The total residence time of each component in the reactor was 4h. The reactor was equipped with a real-time sampling port and a collection tank at the tail end. 20.000 g of the reaction solution from a specific time period was freeze-dried to obtain 0.454 g of a white solid. Liquid phase analysis revealed that this solid contained 0.273 g of adipic acid, 0.026 g of glutaric acid, and 0.013 g of succinic acid. Based on the formula, the weight of the high-boiling-point impurity was 0.142 g, representing 0.71% of the total content in the reaction solution. For ease of comparison, the main experimental conditions and results are listed in Table 1.

[0057] Comparative Example 1

[0058] Appropriate amounts of cyclohexane, acetic acid, and an acetic acid solution containing ferric chloride and cobalt acetate (mass ratio of ferric chloride to cobalt acetate = 1:1, total mass concentration of ferric chloride and cobalt acetate in the acetic acid solution is 5%) were added to the raw material tanks containing cyclohexane, acetic acid, and catalyst, respectively. The reaction was carried out using a continuous reaction apparatus consisting of two reactors connected in series, each with a volume of 2L. The reaction pressure was set at 1.2MPa, the reaction temperature at 100℃, the stirring speed at 500r / min, the air flow rate at 3L / min, the cyclohexane feed rate at 150g / h, the acetic acid feed rate at 340g / h, and the catalyst feed rate at 10g / h. The total residence time of each component in the reactor was 4h. A real-time sampling port and a collection tank were installed at the tail end of the reactor. 20.000 g of the reaction solution from a specific time period was freeze-dried to obtain 0.658 g of a white solid. Liquid phase analysis revealed that it contained 0.235 g of adipic acid, 0.056 g of glutaric acid, and 0.022 g of succinic acid. Based on the formula, the weight of the high-boiling-point impurity was 0.345 g, representing 1.73% of the total content in the reaction solution. For ease of comparison, the main experimental conditions and results are listed in Table 1.

[0059] Comparative Example 2

[0060] Appropriate amounts of cyclohexane, acetic acid, and an acetic acid solution containing manganese acetate and cobalt acetate (mass ratio of manganese acetate to cobalt acetate = 1:1, and the total mass concentration of manganese acetate and cobalt acetate in the acetic acid solution is 5%) were added to the raw material tanks containing cyclohexane, acetic acid, and catalyst, respectively. The reaction was carried out using a continuous reactor consisting of two reactors connected in series, each with a volume of 2L. The reaction pressure was set at 1.2MPa, the reaction temperature at 100℃, the stirring speed at 500r / min, the air flow rate at 3L / min, the cyclohexane feed rate at 150g / h, the acetic acid feed rate at 340g / h, and the catalyst feed rate at 10g / h. The total residence time of each component in the reactor was 4h. A real-time sampling port and a collection tank were installed at the tail end of the reactor. 20.000 g of the reaction solution from a specific time period was freeze-dried to obtain 0.473 g of a white solid. Liquid phase analysis revealed that this solid contained 0.208 g of adipic acid, 0.023 g of glutaric acid, and 0.015 g of succinic acid. Based on the formula, the weight of the high-boiling-point impurity was 0.227 g, representing 1.14% of the total content in the reaction solution. For ease of comparison, the main experimental conditions and results are listed in Table 1.

[0061] Comparative Example 3

[0062] Appropriate amounts of cyclohexane, acetic acid, and acetic anhydride (mass ratio of acetic acid to acetic anhydride = 10:1), along with an acetic acid solution containing cobalt acetate (mass concentration of cobalt acetate = 5%), were added to the raw material tanks containing cyclohexane, acetic acid, and catalyst. The reaction was carried out using a continuous reaction apparatus consisting of two reactors connected in series, each with a volume of 2L. The reaction pressure was set at 1.2MPa, the reaction temperature at 100℃, the stirring speed at 500r / min, the air flow rate at 3L / min, the cyclohexane feed rate at 150g / h, the acetic acid feed rate at 340g / h, and the catalyst solution feed rate at 10g / h. The total residence time of each component in the reactor was 4h. A real-time sampling port and a collection tank were installed at the tail end of the reactor. 20.000 g of the reaction solution from a specific time period was freeze-dried to obtain 0.443 g of a white solid. Liquid phase analysis revealed that it contained 0.185 g of adipic acid, 0.030 g of glutaric acid, and 0.005 g of succinic acid. Based on the formula, the weight of the high-boiling-point impurity was 0.223 g, and its content in the reaction solution was 1.12%. For ease of comparison, the main experimental conditions and results are listed in Table 1.

[0063] Comparative Example 4

[0064] Appropriate amounts of cyclohexane, acetic acid, and a cobalt acetate solution (cobalt acetate concentration of 5%) were added to the raw material tanks containing cyclohexane, acetic acid, and catalyst, respectively. A continuous reaction apparatus was used, consisting of two reactors connected in series, each with a volume of 2L. The reaction pressure was set at 1.2MPa, the reaction temperature at 100℃, the stirring speed at 500r / min, the air flow rate at 3L / min, the cyclohexane feed rate at 150g / h, the acetic acid feed rate at 340g / h, and the catalyst solution feed rate at 10g / h. The total residence time of each component in the reactor was 4h. A real-time sampling port and a collection tank were installed at the tail end of the reactor. 20.000g of the reaction solution from one time period was freeze-dried, yielding 0.498g of a white solid. Liquid phase analysis revealed that this solid contained 0.113g of adipic acid, 0.015g of glutaric acid, and 0.002g of succinic acid. The formula yielded a high-boiling-point impurity weight of 0.368 g, with a content of 1.84% in the reaction synthesis solution. For ease of comparison, the main experimental conditions and results are listed in Table 1.

[0065] Table 1

[0066]

[0067] (a: The solvent is tert-butanol, and the solvent for all other reactions is acetic acid)

[0068] It should be noted that the embodiments described above are only for explaining the present invention and do not constitute any limitation on the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory terms, not limiting terms. Modifications can be made to the present invention within the scope of the claims, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed herein; on the contrary, the present invention can be extended to all other methods and applications with the same function.

Claims

1. A method for producing adipic acid, comprising reacting cyclohexane with an oxygen-containing gas in the presence of a catalyst, a solvent, and a reaction auxiliaries to produce adipic acid, wherein, The catalyst comprises an inorganic or organic salt of two group VIII transition metals or the catalyst comprises an inorganic or organic salt of at least one group VIII transition metal and an inorganic or organic salt of at least one group VIIB metal; the solvent is selected from at least one polar protic solvent; and the reaction promoter is selected from at least one C2-C10 organic acid anhydride. The Group VIII transition metal is selected from iron and cobalt, the Group VIIB metal is manganese, and the catalyst includes at least a cobalt salt.

2. The production method according to claim 1, characterized in that, The inorganic or organic salt is selected from at least one of carboxylates, organic complexes, and halides.

3. The production method according to claim 2, characterized in that, The inorganic or organic salt is selected from acetates and / or chlorides.

4. The production method according to any one of claims 1-3, characterized in that, The catalyst is selected from a mixture of cobalt and iron salts or a mixture of cobalt and manganese salts.

5. The production method according to any one of claims 1-3, characterized in that, The polar protic solvent is selected from at least one of the organic polar protic solvents with less than 6 carbon atoms in the molecule.

6. The production method according to claim 5, characterized in that, The polar protic solvents include neutral polar protic solvents and / or acidic polar protic solvents.

7. The production method according to claim 6, characterized in that, The neutral polar protic solvent is selected from alcohols, and / or the acidic polar protic solvent satisfies 3 ≤ pKa < 7.

8. The production method according to claim 7, characterized in that, The neutral polar protic solvent is selected from fatty alcohols, and / or the acidic polar protic solvent is acetic acid.

9. The production method according to any one of claims 1-3, characterized in that, The organic acid anhydride is selected from at least one of the compounds represented by the formula R1-CO-O-CO-R2, wherein R1 and R2 are the same or different, each independently selected from C1-C8 alkyl groups, and R1 and R2 are optionally connected to -CO-O-CO- groups to form cyclic acid anhydrides.

10. The production method according to claim 9, characterized in that, The organic anhydride is selected from acetic anhydride and / or adipic anhydride.

11. The production method according to any one of claims 1-3, characterized in that, The oxygen-containing gas is selected from gases with an oxygen volume content of 5-100%.

12. The production method according to claim 11, characterized in that, The oxygen-containing gas is air.

13. The production method according to any one of claims 1-3, characterized in that, The feed rate of the oxygen-containing gas is 10-100 L / min, based on 10 moles of cyclohexane.

14. The production method according to any one of claims 1-3, characterized in that, The mass ratio of the catalyst to cyclohexane is (0.001~0.1):1, and / or the mass ratio of the reaction aid to cyclohexane is (0.05~1.0):1; and / or the mass ratio of the solvent to cyclohexane is (1.0~10.0):

1.

15. The production method according to any one of claims 1-3, characterized in that, The reaction temperature is 80℃-120℃, and / or the reaction pressure is 1.0-3.0 MPa, and / or the reaction time is 1-8 hours.

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