Preparation method of glutaric acid

Abstract

This invention belongs to the field of chemical technology, specifically relating to a method for preparing glutaric acid. The method includes: reacting cyclopentanone with an oxygen-containing gas in the presence of a solvent and a catalyst, and separating the glutaric acid; the contact is carried out in the presence of an auxiliary, wherein the auxiliary is a C5-C6 alcohol and / or a C6 ketone. This invention, by adding a suitable auxiliary to the cyclopentanone oxidation catalytic reaction, improves the conversion rate of cyclopentanone, enhances the selectivity of glutaric acid, reduces the occurrence of side reactions, and alleviates the burden of impurities in the synthesis liquid, achieving better technical results.

Description

Technical Field

[0001] This invention belongs to the field of chemical technology, specifically relating to a method for preparing glutaric acid. Background Technology

[0002] Glutaric acid is an important organic chemical raw material and intermediate, mainly used to produce glutaric anhydride, which is used as an initiator in the polymerization of synthetic resins and rubber. Peroxyglutaric acid, synthesized from glutaric acid, is one of the most commonly used peroxides among fatty dicarboxylic acids. Peroxyglutaric acid is not only a highly effective disinfectant but also used as a catalyst in the synthesis of polymers. In addition, glutaric acid has wide applications in the synthesis of liquid polyesters, the formulation of detergents, and sulfur-containing flue gas cleaning agents.

[0003] There are two main production methods for glutaric acid: the recovery method and the synthesis method. The recovery method recovers glutaric acid from the byproducts of adipic acid production and is currently the main method used in industry. This method depends on the production of adipic acid, resulting in inconsistent yields, complex processes, and poor product quality.

[0004] Synthetic methods are currently the most promising research direction in glutaric acid production. Traditional synthetic methods include multi-step synthesis using γ-butyrolactone as a raw material, oxidative hydrolysis using dihydropyran as a raw material, and acid hydrolysis using glutaronitrile as a raw material, but all of them have obvious drawbacks such as expensive raw materials and high reagent toxicity.

[0005] Glutamic acid can also be obtained by oxidizing cyclopentanone with oxygen or air, but glutaric acid has low selectivity and poor economic efficiency. Due to the large number of impurities and byproducts in the reaction solution, the separation of the main product, glutaric acid, is difficult. Summary of the Invention

[0006] To address the shortcomings of existing methods for preparing glutaric acid by oxidizing cyclopentanone, which suffer from low conversion rates of cyclopentanone and poor selectivity of glutaric acid, this invention provides a method for preparing glutaric acid by oxidizing cyclopentanone, which can improve both the conversion rate of the raw material and the selectivity of the product glutaric acid.

[0007] To achieve the above objectives, the present invention provides a method for preparing glutaric acid, the method comprising: reacting cyclopentanone with an oxygen-containing gas in the presence of a solvent and a catalyst, and separating to obtain glutaric acid; wherein the reaction is carried out in the presence of an auxiliary agent, wherein the auxiliary agent is a C5-C6 alcohol and / or a C6 ketone.

[0008] Due to the adoption of the above technical solution, the beneficial effects of the present invention compared with the prior art are as follows:

[0009] This invention improves the conversion rate of cyclopentanone, enhances the selectivity of glutaric acid, reduces the occurrence of side reactions, and alleviates the burden of impurities in the synthesis solution by adding appropriate auxiliaries to the cyclopentanone oxidation catalytic reaction, thus achieving better technical results. Detailed Implementation

[0010] 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.

[0011] This invention provides a method for preparing glutaric acid, the method comprising: reacting cyclopentanone with an oxygen-containing gas in the presence of a solvent and a catalyst, and separating to obtain glutaric acid; wherein the reaction is carried out in the presence of an auxiliary agent, wherein the auxiliary agent is a C5-C6 alcohol and / or a C6 ketone.

[0012] By adding appropriate auxiliaries to the cyclopentanone oxidation catalytic reaction, the conversion rate of cyclopentanone was improved, the selectivity of glutaric acid was enhanced, the occurrence of side reactions was reduced, and the burden of impurities in the synthesis solution was lessened.

[0013] In this invention, the molar ratio of the auxiliary agent to the solvent is not particularly required as long as the objective of the invention is achieved. According to a preferred embodiment of the invention, the molar ratio of the auxiliary agent to the solvent is 0.01-0.05:100, for example, 0.01:100, 0.02:100, 0.03:100, 0.04:100, or 0.05:100. By adopting the aforementioned preferred scheme, the conversion rate of cyclopentanone can be further improved, the selectivity of glutaric acid can be increased, the occurrence of side reactions can be reduced, and the burden of impurities in the synthesis solution can be lessened.

[0014] In this invention, the auxiliary agent can be a conventional choice in the art. According to a preferred embodiment of the invention, the auxiliary agent is selected from any one, two, or three of cyclohexanone, cyclohexanol, and cyclopentanol, preferably cyclohexanone and / or cyclohexanol, and more preferably cyclohexanone. By adopting the aforementioned preferred scheme, the conversion rate of cyclopentanone can be further improved, the selectivity of glutaric acid can be improved, the occurrence of side reactions can be reduced, and the burden of impurities in the synthesis liquid separation can be reduced.

[0015] In this invention, the catalyst is a conventional choice in the art. According to a preferred embodiment of the invention, the catalyst is one or more of zirconium salt, copper salt, manganese salt, and cobalt salt; preferably, the catalyst is a zirconium salt, or a combination of zirconium salt and one or more of copper salt, manganese salt, and cobalt salt. By adopting the aforementioned preferred embodiment, the conversion rate of cyclopentanone can be further improved, the selectivity of glutaric acid can be increased, the occurrence of side reactions can be reduced, and the burden of impurities in the synthesis liquid separation can be lessened.

[0016] In this invention, zirconium salts, copper salts, manganese salts, and cobalt salts are all conventional choices in the art. According to a preferred embodiment of the invention, the zirconium salt is zirconium chloride, the copper salt is copper acetate, the manganese salt is manganese acetate, and the cobalt salt is cobalt acetate. By adopting the aforementioned preferred scheme, the conversion rate of cyclopentanone can be further improved, the selectivity of glutaric acid can be increased, the occurrence of side reactions can be reduced, and the burden of impurities in the synthesis liquid separation can be lessened.

[0017] To further improve the conversion rate of cyclopentanone, enhance the selectivity of glutaric acid, reduce the occurrence of side reactions, and alleviate the burden of impurities in the synthesis liquid, according to a preferred embodiment of the present invention, the catalyst is a mixture of zirconium chloride and cobalt acetate, wherein the molar ratio of cobalt acetate to zirconium chloride is 0.1-5:1, preferably 0.1-1:1, for example 0.1:1, 0.2:1, 0.3:1, 0.1-0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1; more preferably 0.1-0.5:1, for example 0.1:1, 0.2:1, 0.3:1, 0.1-0.4:1, 0.5:1.

[0018] In this invention, as long as the objective of the invention can be achieved, the molar ratio of the total catalyst to the solvent is not particularly required. According to a preferred embodiment of the invention, the molar ratio of the total catalyst to the solvent is 0.01-0.2:100, preferably 0.1-0.2:100. By adopting the aforementioned preferred embodiment, the conversion rate of cyclopentanone can be further improved, the selectivity of glutaric acid can be improved, the occurrence of side reactions can be reduced, and the burden of impurities in the synthesis liquid separation can be reduced.

[0019] In this invention, the solvent can be any conventional choice in the art as long as it achieves the purpose of this invention. According to a preferred embodiment of this invention, the solvent is one or more of acetic acid, acetone and acetonitrile.

[0020] According to a preferred embodiment of the present invention, the oxygen content in the oxygen-containing gas is 5-18% by volume, preferably 6-12% by volume. By adopting the aforementioned preferred embodiment, the conversion rate of cyclopentanone can be further improved, the selectivity of glutaric acid can be increased, the occurrence of side reactions can be reduced, and the burden of impurities in the synthesis liquid separation can be reduced.

[0021] According to a preferred embodiment of the present invention, the method includes:

[0022] I) The catalyst, auxiliaries, cyclopentanone, and solvent are added to the oxidation reactor to form a reaction mixture;

[0023] II) Introduce oxygen-containing gas into the reactor and heat the reactor to the reaction temperature and pressure;

[0024] III) Oxygen-containing gas under working pressure is continuously fed into the reactor for contact;

[0025] IV) Stop feeding to end the reaction.

[0026] By adopting the aforementioned preferred scheme, the conversion rate of cyclopentanone can be further improved, the selectivity of glutaric acid can be increased, the occurrence of side reactions can be reduced, and the burden of impurities in the synthesis liquid separation can be reduced.

[0027] In this invention, as long as the objective of the invention can be achieved, the molar flow ratio of the oxygen-containing gas to the solvent is not particularly required. According to a preferred embodiment of the invention, the molar flow ratio of the oxygen-containing gas to the solvent is 10-30:1. By adopting the aforementioned preferred scheme, the conversion rate of cyclopentanone can be further improved, the selectivity of glutaric acid can be improved, the occurrence of side reactions can be reduced, and the burden of impurities in the synthesis liquid separation can be reduced.

[0028] In this invention, the feed molar ratio of oxygen-containing gas to solvent refers to the ratio of the flow rate of oxygen-containing gas (mol / h) to the feed flow rate of the solvent solution (mol / h) (based on the amount of acetic acid in the feed solution).

[0029] In this invention, the molar ratio of cyclopentanone to solvent is not particularly required as long as the objective of the invention is achieved. According to a preferred embodiment of the invention, the molar ratio of cyclopentanone to solvent is 0.5-2:1, for example, 0.5:1, 1:1, 1.5:1, or 2:1. By adopting the aforementioned preferred scheme, the conversion rate of cyclopentanone can be further improved, the selectivity of glutaric acid can be increased, the occurrence of side reactions can be reduced, and the burden of impurities in the synthesis solution can be reduced.

[0030] In this invention, the contact conditions are conventionally chosen in the art. According to a preferred embodiment of the invention, the contact temperature is 80-110°C, for example, 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, or 110°C.

[0031] According to a preferred embodiment of the present invention, the contact pressure is 3-8 MPa, for example, 3 MPa, 4 MPa, 5 MPa, 6 MPa, 7 MPa, or 8 MPa.

[0032] According to a preferred embodiment of the present invention, the contact time is 2-6 hours, such as 2 hours, 3 hours, 4 hours, 5 hours, or 6 hours.

[0033] By adopting the aforementioned preferred scheme, the conversion rate of cyclopentanone can be further improved, the selectivity of glutaric acid can be increased, the occurrence of side reactions can be reduced, and the burden of impurities in the synthesis liquid separation can be reduced.

[0034] The present invention will be further described below through specific embodiments, but the scope of the present invention is not limited to the scope covered by the embodiments. In the following embodiments, the raw materials are all commercially available products. The specific calculation methods for cyclopentanone conversion rate and glutaric acid selectivity are as follows:

[0035] Cyclopentanone conversion rate = (molar amount of cyclopentanone before reaction - molar amount of cyclopentanone after reaction) / molar amount of cyclopentanone before reaction

[0036] Glutaric acid selectivity = Molar amount of glutaric acid produced in the reaction / (Molar amount of cyclopentanone before the reaction - Molar amount of cyclopentanone after the reaction)

[0037] Example 1

[0038] 1) Dissolve 0.12 mol of zirconium chloride in 100 mol of acetic acid, add 0.03 mol of cyclohexanone as an auxiliary agent, and add 100 mol of cyclopentanone as a reaction raw material. Mix the above materials to prepare an acetic acid solution and add it to the oxidation reaction vessel.

[0039] 2) Oxygen-deficient air (oxygen volume content 12%, the remainder mainly nitrogen) is continuously introduced into the oxidation reactor at a gas flow rate of 18 mol / h. The reactor is heated to the reaction temperature of 85℃ and the reaction pressure is 5.0 MPa.

[0040] 3) Acetic acid solution and oxygen-deficient air are continuously fed into the reactor. The acetic acid solution feed flow rate is 1 mol / h (calculated based on the amount of acetic acid in the solution), and the oxygen-deficient air flow rate is 18 mol / h.

[0041] 4) After 4 hours of reaction, stop feeding to end the reaction. Take a sample of the glutaric acid oxidation reaction solution from the synthesis liquid collection tank for analysis of its composition. The cyclopentanone conversion rate was calculated to be 87.0%, and the glutaric acid selectivity was 90.7%.

[0042] Example 2

[0043] 1) Dissolve 0.12 mol of zirconium chloride in 100 mol of acetic acid, add 0.03 mol of cyclohexanol as an auxiliary agent, and add 100 mol of cyclopentanone as a reaction raw material. Mix the above materials to prepare an acetic acid solution and add it to the oxidation reaction vessel.

[0044] 2) Oxygen-deficient air (oxygen volume content 12%, the remainder mainly nitrogen) is continuously introduced into the oxidation reactor at a gas flow rate of 18 mol / h. The reactor is heated to the reaction temperature of 85℃ and the reaction pressure is 5.0 MPa.

[0045] 3) Acetic acid solution and oxygen-deficient air are continuously fed into the reactor. The acetic acid solution feed flow rate is 1 mol / h (calculated based on the amount of acetic acid in the solution), and the oxygen-deficient air flow rate is 18 mol / h.

[0046] 4) After 4 hours of reaction, stop feeding to end the reaction. Take a sample of the glutaric acid oxidation reaction solution from the synthesis liquid collection tank for analysis of its composition. The cyclopentanone conversion rate was calculated to be 86.8%, and the glutaric acid selectivity was 89.9%.

[0047] Example 3

[0048] 1) Dissolve 0.12 mol of zirconium chloride in 100 mol of acetic acid, add 0.03 mol of cyclopentanol as an auxiliary agent, add 100 mol of cyclopentanone as a reaction raw material, mix the above materials to prepare an acetic acid solution and add it to the oxidation reaction vessel.

[0049] 2) Oxygen-deficient air (oxygen volume content 12%, the remainder being mainly nitrogen) is continuously introduced into the oxidation reactor at a flow rate of 18 mol / h. The reactor is heated to a reaction temperature of 85℃ and a reaction pressure of 5.0 MPa.

[0050] 3) Acetic acid solution and oxygen-deficient air are continuously fed into the reactor. The acetic acid solution feed flow rate is 1 mol / h (calculated based on the amount of acetic acid in the solution), and the oxygen-deficient air flow rate is 18 mol / h.

[0051] 4) After 4 hours of reaction, stop feeding to end the reaction. Take a sample of the glutaric acid oxidation reaction solution from the synthesis liquid collection tank for analysis of its composition. The cyclopentanone conversion rate was calculated to be 86.9%, and the glutaric acid selectivity was 90.1%.

[0052] Example 4

[0053] 1) Dissolve 0.04 mol of cobalt acetate and 0.08 mol of zirconium chloride in 100 mol of acetic acid, add 0.03 mol of cyclohexanone as an auxiliary agent, and add 100 mol of cyclopentanone as a reaction raw material. Mix the above materials to prepare an acetic acid solution and add it to the oxidation reaction vessel.

[0054] 2) Oxygen-deficient air (9% oxygen by volume, with the remainder mainly nitrogen) is continuously introduced into the oxidation reactor at a flow rate of 20 mol / h. The reactor is heated to a reaction temperature of 85°C and a reaction pressure of 5.0 MPa.

[0055] 3) Acetic acid solution and oxygen-deficient air are continuously fed into the reactor. The acetic acid solution feed flow rate is 1 mol / h (calculated based on the amount of acetic acid in the solution), and the oxygen-deficient air flow rate is 20 mol / h.

[0056] 4) After 4 hours of reaction, stop feeding to end the reaction. Take a sample of the glutaric acid oxidation reaction solution from the synthesis liquid collection tank for analysis of its composition. The cyclopentanone conversion rate was calculated to be 97.7%, and the glutaric acid selectivity was 94.0%.

[0057] Example 5

[0058] 1) Dissolve 0.06 mol of cobalt acetate and 0.12 mol of zirconium chloride in 100 mol of acetic acid, add 0.03 mol of cyclohexanone as an auxiliary agent, and add 100 mol of cyclopentanone as a reaction raw material. Mix the above materials to prepare an acetic acid solution and add it to the oxidation reaction vessel.

[0059] 2) Oxygen-deficient air (oxygen volume content 12%, the remainder mainly nitrogen) is continuously introduced into the oxidation reactor at a gas flow rate of 18 mol / h. The reactor is heated to the reaction temperature of 85℃ and the reaction pressure is 5.0 MPa.

[0060] 3) Acetic acid solution and oxygen-deficient air are continuously fed into the reactor. The acetic acid solution feed flow rate is 1 mol / h (calculated based on the amount of acetic acid in the solution), and the oxygen-deficient air flow rate is 18 mol / h.

[0061] 4) After 4 hours of reaction, stop feeding to end the reaction. Take a sample of the glutaric acid oxidation reaction solution from the synthesis liquid collection tank for analysis of its composition. The cyclopentanone conversion rate was calculated to be 97.6%, and the glutaric acid selectivity was 93.2%.

[0062] Example 6

[0063] 1) Dissolve 0.01 mol of cobalt acetate and 0.1 mol of zirconium chloride in 100 mol of acetic acid, add 0.03 mol of cyclohexanone as an auxiliary agent, and add 50 mol of cyclopentanone as a reaction raw material. Mix the above materials to prepare an acetic acid solution and add it to the oxidation reaction vessel.

[0064] 2) Oxygen-deficient air (oxygen volume content 6%, the remainder is nitrogen) is continuously introduced into the oxidation reactor at a gas flow rate of 18 mol / h. The reactor is heated to the reaction temperature of 80℃ and the reaction pressure is 8.0 MPa.

[0065] 3) Acetic acid solution and oxygen-deficient air are continuously fed into the reactor. The feed flow rate of acetic acid solution is 1 mol / h (calculated based on the amount of acetic acid in the solution), and the flow rate of oxygen-deficient air is 30 mol / h.

[0066] 4) After 2 hours of reaction, stop feeding to end the reaction. Take a sample of the glutaric acid oxidation reaction solution from the synthesis liquid collection tank for analysis of its composition. The cyclopentanone conversion rate was calculated to be 93.4%, and the glutaric acid selectivity was 92.7%.

[0067] Example 7

[0068] 1) Dissolve 0.005 mol of cobalt acetate and 0.005 mol of zirconium chloride in 100 mol of acetic acid, add 0.1 mol of cyclohexanone as an auxiliary agent, and add 200 mol of cyclopentanone as a reaction raw material. Mix the above materials to prepare an acetic acid solution and add it to the oxidation reaction vessel.

[0069] 2) Oxygen-deficient air (oxygen volume content 18%, the remainder mainly nitrogen) is continuously introduced into the oxidation reactor at a gas flow rate of 10 mol / h. The reactor is heated to a reaction temperature of 110℃ and a reaction pressure of 3.0 MPa.

[0070] 3) Acetic acid solution and oxygen-deficient air are continuously fed into the reactor. The feed flow rate of acetic acid solution is 1 mol / h (calculated based on the amount of acetic acid in the solution), and the flow rate of oxygen-deficient air is 10 mol / h.

[0071] 4) After 3 hours of reaction, stop feeding to end the reaction. Take a sample of the glutaric acid oxidation reaction solution from the synthesis liquid collection tank for analysis of its composition. The cyclopentanone conversion rate was calculated to be 92.5%, and the glutaric acid selectivity was 89.5%.

[0072] Example 8

[0073] 1) Dissolve 0.09 mol of cobalt acetate and 0.03 mol of zirconium chloride in 100 mol of acetic acid, add 0.01 mol of cyclohexanone as an auxiliary agent, and add 100 mol of cyclopentanone as a reaction raw material. Mix the above materials to prepare an acetic acid solution and add it to the oxidation reaction vessel.

[0074] 2) Oxygen-deficient air (oxygen volume content 12%, the remainder mainly nitrogen) is continuously introduced into the oxidation reactor at a gas flow rate of 18 mol / h. The reactor is heated to the reaction temperature of 95℃ and the reaction pressure is 6.0 MPa.

[0075] 3) Acetic acid solution and oxygen-deficient air are continuously fed into the reactor. The acetic acid solution feed flow rate is 1 mol / h (calculated based on the amount of acetic acid in the solution), and the oxygen-deficient air flow rate is 18 mol / h.

[0076] 4) After 6 hours of reaction, the feed was stopped and the reaction was terminated. A sample of the glutaric acid oxidation reaction solution was taken from the synthesis liquid collection tank for analysis of its composition. The cyclopentanone conversion rate was calculated to be 91.7% and the glutaric acid selectivity was 92.2%.

[0077] Example 9

[0078] 1) Dissolve 0.05 mol of cobalt acetate and 0.15 mol of zirconium chloride in 100 mol of acetic acid, add 0.05 mol of cyclohexanone as an auxiliary agent, and add 100 mol of cyclopentanone as a reaction raw material. Mix the above materials to prepare an acetic acid solution and add it to the oxidation reaction vessel.

[0079] 2) Air (oxygen content 21% by volume, the remainder mainly nitrogen) is continuously introduced into the oxidation reactor at a flow rate of 10 mol / h. The reactor is heated to a reaction temperature of 85℃ and a reaction pressure of 5.0 MPa.

[0080] 3) Acetic acid solution and oxygen-deficient air are continuously fed into the reactor. The acetic acid solution feed flow rate is 1 mol / h (calculated based on the amount of acetic acid in the solution), and the air flow rate is 10 mol / h.

[0081] 4) After 4 hours of reaction, stop feeding to end the reaction. Take a sample of the glutaric acid oxidation reaction solution from the synthesis liquid collection tank for analysis of its composition. The cyclopentanone conversion rate was calculated to be 92.9%, and the glutaric acid selectivity was 92.4%.

[0082] Comparative Example 1

[0083] 1) Dissolve 0.12 mol of cobalt acetate in 100 mol of acetic acid, add 100 mol of cyclopentanone as a reaction raw material, mix the above materials to prepare an acetic acid solution and add it to the oxidation reaction vessel;

[0084] 2) Oxygen-deficient air (oxygen volume content 12%, the remainder mainly nitrogen) is continuously introduced into the oxidation reactor at a gas flow rate of 18 mol / h. The reactor is heated to the reaction temperature of 85℃ and the reaction pressure is 5.0 MPa.

[0085] 3) Acetic acid solution and oxygen-deficient air are continuously fed into the reactor. The acetic acid solution feed flow rate is 1 mol / h (calculated based on the amount of acetic acid in the solution), and the oxygen-deficient air flow rate is 18 mol / h.

[0086] 4) After 4 hours of reaction, stop feeding to end the reaction. Take a sample of the glutaric acid oxidation reaction solution from the synthesis liquid collection tank for analysis of its composition. The cyclopentanone conversion rate was calculated to be 66.3%, and the glutaric acid selectivity was 58.1%.

[0087] Comparative Example 2

[0088] 1) Dissolve 0.06 mol of cobalt acetate and 0.06 mol of zirconium chloride in 100 mol of acetic acid, add 0.03 mol of n-butanone as an auxiliary agent, and add 100 mol of cyclopentanone as a reaction raw material. Mix the above materials to prepare an acetic acid solution and add it to the oxidation reaction vessel.

[0089] 2) Oxygen-deficient air (oxygen volume content 12%, the remainder mainly nitrogen) is continuously introduced into the oxidation reactor at a gas flow rate of 18 mol / h. The reactor is heated to the reaction temperature of 85℃ and the reaction pressure is 5.0 MPa.

[0090] 3) Acetic acid solution and oxygen-deficient air are continuously fed into the reactor. The acetic acid solution feed flow rate is 1 mol / h (calculated based on the amount of acetic acid in the solution), and the oxygen-deficient air flow rate is 18 mol / h.

[0091] 4) After 4 hours of reaction, stop feeding to end the reaction. Take a sample of the glutaric acid oxidation reaction solution from the synthesis liquid collection tank for analysis of its composition. The cyclopentanone conversion rate was calculated to be 78.3%, and the glutaric acid selectivity was 67.3%.

[0092] If the data in the table differs from the examples, the examples shall prevail.

[0093] Table 1

[0094]

[0095] As can be seen from the results in Table 1, the method for preparing glutaric acid according to the present invention has the advantages of high cyclopentanone conversion rate and glutaric acid selectivity.

[0096] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for preparing glutaric acid, characterized in that, The method includes: reacting cyclopentanone with an oxygen-containing gas in the presence of a solvent and a catalyst to separate glutaric acid; the contact is carried out in the presence of an auxiliary agent, wherein the auxiliary agent is cyclohexanone; The molar ratio of the additive to the solvent is 0.01-0.05:100; The oxygen content in oxygen-containing gas is 5-18% by volume; The catalyst is a mixture of zirconium chloride and cobalt acetate, wherein the molar ratio of cobalt acetate to zirconium chloride is 0.1-5:1; The molar ratio of total catalyst to solvent is 0.01-0.2:100; The solvent is acetic acid; The molar ratio of cyclopentanone to solvent is 0.5-2:

1.

2. The method according to claim 1, wherein, The molar ratio of cobalt acetate to zirconium chloride is 0.1-1:

1.

3. The method according to claim 2, wherein, The molar ratio of cobalt acetate to zirconium chloride is 0.1-0.5:

1.

4. The method according to claim 1, wherein, The molar ratio of total catalyst to solvent is 0.1-0.2:

100.

5. The method according to claim 1, wherein, The oxygen content in oxygen-containing gas is 6-12% by volume.

6. The method according to claim 1, wherein, The method includes: I) The catalyst, auxiliaries, cyclopentanone, and solvent are added to the oxidation reactor to form a reaction mixture; II) Introduce oxygen-containing gas into the reactor and heat the reactor to the reaction temperature and pressure; III) Oxygen-containing gas under working pressure is continuously fed into the reactor for contact; IV) Stop feeding to end the reaction.

7. The method according to claim 6, wherein, The feed molar flow ratio of oxygen-containing gas to solvent is 10-30:

1.

8. The method according to claim 6, wherein, The contact temperature is 80-110℃; and / or The contact pressure is 3-8 MPa; and / or Contact time: 2-6 hours.

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