Manganese-based catalyst and its application in the process of synthesizing adiponitrile from cyclohexene oxide

Abstract

The application belongs to the technical field of catalytic selective ammoxidation, and discloses a manganese-based catalyst for synthesizing adiponitrile from epoxycyclohexane as well as a preparation method and application of the manganese-based catalyst. The manganese-based catalyst comprises manganese oxide or supported manganese oxide. The pure manganese oxide is obtained by reducing high-valence manganese salt; the supported manganese oxide is obtained by impregnating or depositing and precipitating manganese salt on a carrier, and then calcining through a high-temperature reaction of a hydrothermal kettle. In the presence of the manganese-based catalyst, epoxycyclohexane is used as a substrate, an additive is added under an oxygen and ammonia atmosphere, and the yield of adiponitrile is up to 80.3%. Compared with the prior art, the application relates to a brand-new heterogeneous catalytic ammoxidation technical route, uses a heterogeneous inexpensive metal catalyst, does not use hydrocyanic acid, and has the advantages of simple operation, low cost, high product yield, green environmental protection and the like.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of catalytic selective ammoxidation, and relates to a manganese-based catalyst, in particular to a manganese-based catalyst for synthesizing adiponitrile and a preparation method and application thereof. BACKGROUND

[0002] Adiponitrile is a key intermediate for the production of PA66 (commonly known as nylon 66), and is mainly used for the production of nylon intermediate hexamethylene diamine. About 90% of adiponitrile is used for the production of nylon 66. Due to its high strength, temperature resistance, heat resistance, good electrical insulation and other characteristics, nylon 66 is widely used in various engineering plastics, automobiles, machinery, electrical parts, industrial yarns, civil yarns and other fields. The increasing downstream demand has driven up the price of hexamethylene diamine, and the demand for hexamethylene diamine is about to break through. It can be said that adiponitrile has become the throat of the entire industrial chain and the most vulnerable link. In addition, due to the high technical barriers and investment threshold, the industry concentration of adiponitrile is also very high. At present, the global adiponitrile capacity is 1.845 million tons, mainly concentrated in four enterprises of American Invista, American Oxsorb, German BASF (including Solvay) and Japanese Asahi Kasei. Among them, Invista accounts for more than 50%, and is also the only manufacturer that sells adiponitrile to the outside world. In China, the "adiponitrile-hexamethylene diamine-nylon 66" industry chain is facing a more embarrassing reality: oligarchic monopoly, serious technology blockade, complete reliance on imports, and pricing at the mercy of others. In fact, the effort of adiponitrile localization has never stopped. The catalytic ammoniation method of adipic acid of Liaoyang Branch of PetroChina stopped production in 2002 due to the high cost and no competitive advantage compared with the adiponitrile produced by the butadiene route abroad. In 2015, Shandong Runxing Chemical completed the first 100,000-ton-level adiponitrile production device in China, which adopted the propylene nitrile electrolytic dimerization process. However, the device exploded during the feeding test, and there was no further progress. China Tianchen Engineering Co., Ltd. and Shandong Haili Chemical completed a 50-ton butadiene direct hydrocyanation method adiponitrile pilot test in 2015. Tianchen Qixiang 1 million ton nylon new material industry base officially broke ground on the morning of August 19, 2019. The project is the first adiponitrile project in China. The industry base is located in Zibo Qilu Chemical Industry Zone. The industry base plans to produce 1 million tons of nylon new materials, 500,000 tons of hexamethylene diamine, 500,000 tons of adiponitrile and 500,000 tons of propylene nitrile in association. The project is expected to be completed in October 2021. Chongqing Ziguang Chemical 500-ton propylene nitrile electrolytic dimerization method adiponitrile pilot plant has been built, and there is no public information about the subsequent pilot test results. In February 2019, international adiponitrile giant Invista signed a cooperation agreement with Shanghai Chemical Industry Zone to start the design and planning of a 400,000-ton adiponitrile production base, which plans to start construction in 2020 and put into production in 2023.

[0003] The production technology of adiponitrile is difficult, and international multinational companies have strictly sealed the adiponitrile production technology to maintain the core technology advantage. The direct hydrocyanation of butadiene has a more competitive advantage in product cost compared with the propylene nitrile electrolytic dimerization method, and is the ideal butadiene production technology in the world. In the 1970s, DuPont developed the direct hydrocyanation of butadiene, and established the first production device in Texas and realized industrialization. The direct hydrocyanation of butadiene is to add two molecules of hydrocyanic acid (HCN) to butadiene in the presence of a catalyst composed of zero-valent nickel and phosphorus ligand, and the reaction process can be divided into three processes of primary hydrocyanation, isomerization and secondary hydrocyanation. The route needs to use the toxic reagent hydrocyanic acid, the multi-step reaction has huge energy consumption, and the catalyst is relatively "delicate", the catalyst selection and control are hard cores, the catalyst and butadiene consumption are large, and the investment is huge. The technical difficulty of the direct hydrocyanation of butadiene lies in the selection and preparation of a catalyst with ideal selectivity and yield, especially the selection of the catalyst ligand. Up to now, there is no adiponitrile production plant in China. Therefore, it is imminent to realize the localization of the adiponitrile production technology with independent intellectual property rights. This scientific and challenging work has important practical significance and scientific research value.

[0004] There is a literature 1 reporting the preparation of adiponitrile from cyclohexene oxide, which can obtain 70% of adiponitrile yield under the action of 3.5 times of iodine in the presence of ammonia and acetonitrile as a co-solvent. The above process has problems of a large amount of iodine pollution, high cost and the like, and it is difficult to meet the requirements of industrial production. Compared with the above, the present application prepares adiponitrile in one step under the action of a cheap manganese catalyst and in the presence of ammonia and oxygen. In the presence of the manganese-based catalyst, the yield of adiponitrile is as high as 80.3% under the action of oxygen and ammonia and by adding an additive. The adiponitrile synthesis technology proposed in the present application has the advantages of using a cheap multi-phase metal catalyst, recycling the catalyst, low energy consumption of one-step reaction, no use of highly toxic reagents such as hydrocyanic acid, simple operation, easy control and no pollution, and has great industrial application value.

[0005] Reference

[0006] 1. Ravindra R. Jadhav and Krishnacharya G. Akamanchi. *Chem. Lett. 2013, 42, 162164. The present application is mainly realized by the following technical solutions:

[0007] A manganese-based catalyst for synthesizing adiponitrile from cyclohexene oxide, characterized in that the manganese-based catalyst comprises simple manganese oxide or supported manganese oxide. The simple manganese oxide is obtained by reduction of high-valence manganese salt; the supported manganese oxide is obtained by impregnation or deposition of manganese salt on a carrier, and then by high-temperature hydrothermal method. The catalyst is used for synthesizing adiponitrile under the atmosphere of oxygen and ammonia with an additive.

[0008] The manganese-based catalyst for synthesizing adiponitrile, characterized in that it comprises the following preparation steps: preparation of simple manganese oxide: a certain amount of potassium permanganate is weighed and added to water, and stirred at room temperature until dissolved; a certain amount of manganese sulfate is weighed and added to water, and stirred at room temperature until dissolved; the obtained solution is slowly added dropwise to the above mixed solution, and the mixture is adjusted to a certain pH value with ammonia water; the mixture is stirred at room temperature for several hours, then transferred into a hydrothermal kettle, and kept in an oven at a certain temperature for several hours; after cooling, filtration and washing with deionized water until neutral, the target catalyst is obtained after vacuum drying. Preparation of supported manganese-based catalyst: a certain amount of carrier is dispersed in an aqueous solution of manganese sulfate, and stirred at room temperature; the mixture is adjusted to a certain pH value with ammonia water, and continues to be stirred at room temperature for 24 hours; the mixture is transferred into a hydrothermal kettle, and kept in an oven at a certain temperature for several hours; after cooling, filtration, washing and vacuum drying, the target catalyst is obtained.

[0009] In the above preparation method, the carrier is one of alumina, silica, hydroxyapatite, hydrotalcite and magnesium oxide, preferably alumina.

[0010] In the above preparation method, the alumina can be in three crystal forms, i.e. α-Al2O3, β-Al2O3 and γ-Al2O3.

[0011] In the above preparation method, the pH value is adjusted to 7-10; the stirring time at room temperature is 0.5-12 hours.

[0012] In the above preparation method, the hydrothermal kettle is placed in an oven at a temperature of 100-180℃; the vacuum drying treatment is vacuumizing the solid at 60-100℃ for 12-24 hours.

[0013] In the above preparation method, the obtained manganese-based catalyst has a manganese content of 20%-60%.

[0014] The method for synthesizing adiponitrile is as follows: under the manganese-based catalyst, oxygen is used as the oxidant, ammonia is used as the ammonia source, cyclohexene oxide is used as the raw material, the reaction solvent is an organic solvent, the system pressure is 0.5-2.0 MPa, the reaction temperature is 70-120℃, the reaction time is 4-24 hours, and the obtained product after reaction is adiponitrile; the yield and selectivity of the product are determined by chromatography internal standard method.

[0015] The reaction solvent in the above synthesis method is any one of acetonitrile, n-heptane, toluene, 1,2-dichloroethane, dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF), tetrahydrofuran, and water, and acetonitrile is the most preferred.

[0016] The reaction temperature in the above synthesis method is preferably 100°C, and the reaction time is preferably 12 hours.

[0017] The molar ratio of the epoxycyclohexane to the manganese-based catalyst in the above synthesis method is 1:0.01-0.05.

[0018] The present application has the following advantages and effects compared with the prior art:

[0019] (1) The raw material required for preparing the inexpensive manganese-based catalyst used in the present application is simple and easy to obtain, and the preparation conditions are simple, so it is very easy to synthesize in large quantities. The catalyst has good recycling effect. After reaction, it can be reused after simple filtration, washing and drying, and the catalytic activity and selectivity are not changed.

[0020] (2) The present application is completely different from the existing butadiene technology abroad, and is a completely new process route: starting from epoxycyclohexane, the adiponitrile is directly prepared by one-pot aminooxidation. Compared with the butadiene method, this route has one-step reaction, uses recyclable inexpensive metal catalyst, and does not use hydrocyanic acid. The yield of adiponitrile can reach 80.3%, and the route is simple, green and pollution-free, and has more prospects for industrial production.

[0021] Compared with the existing technology, the technology involved in the present application is a completely new multi-phase catalytic aminooxidation technology route, which uses inexpensive metal catalyst and does not use hydrocyanic acid, and has the advantages of simple operation, low cost, high product yield, green environmental protection, etc. DETAILED DESCRIPTION

[0022] The present application will be further described below in conjunction with specific examples, but the protection scope of the present application is not limited to this:

[0023] Example 1

[0024] 6g of potassium permanganate was added to 20ml of deionized water, and stirred at room temperature until completely dissolved. 9g of manganese sulfate aqueous solution was added to 40ml of water, and the latter was added dropwise to the former. Under the condition of stirring at room temperature, ammonia water (25wt%-28wt% ammonia aqueous solution) was used to adjust the pH of the system to 7. After 12h of continuous stirring, it was transferred into a 100ml autoclave, placed in a 180-degree oven for 5h, then cooled to room temperature, filtered, washed with deionized water until neutral, and vacuum dried in an 80-degree oven for 18h.

[0025] Example 2

[0026] Add 9g of manganese sulfate to 40ml of water and stir at room temperature for a few minutes. Then add 4g of γ-Al2O3 and adjust the pH of the system to 7 with ammonia water (25wt% to 28wt% ammonia aqueous solution) while stirring at room temperature. Continue stirring for 12 hours and then transfer the mixture to a 100ml hydrothermal reactor. Place the reactor in an oven at 180 degrees Celsius for 5 hours and then cool to room temperature. Filter the mixture, wash it with deionized water until neutral, and then vacuum dry it in an oven at 80 degrees Celsius for 18 hours.

[0027] Example 3

[0028] Add 9g of manganese sulfate to 40ml of water and stir at room temperature for a few minutes. Then add 4g of silicon dioxide and adjust the pH of the system to 7 with ammonia water (an aqueous solution containing 25wt% to 28wt% ammonia) while stirring at room temperature. Continue stirring for 12 hours and then transfer the solution to a 100ml hydrothermal reactor. Place the reactor in an oven at 180 degrees Celsius for 5 hours and then cool to room temperature. Filter the solution, wash with deionized water until neutral, and then vacuum dry in an oven at 80 degrees Celsius for 18 hours.

[0029] Example 4

[0030] Add 9g of manganese sulfate to 40ml of water and stir at room temperature for a few minutes. Then add 4g of hydroxyapatite and adjust the pH of the system to 7 with ammonia water (an aqueous solution containing 25wt% to 28wt% ammonia) while stirring at room temperature. Continue stirring for 12 hours and then transfer the solution to a 100ml hydrothermal reactor. Place the reactor in an oven at 180 degrees Celsius for 5 hours and then cool to room temperature. Filter the solution, wash with deionized water until neutral, and then vacuum dry in an oven at 80 degrees Celsius for 18 hours.

[0031] Example 5

[0032] Add 9g of manganese sulfate to 40ml of water and stir at room temperature for a few minutes. Then add 4g of hydrotalcite and adjust the pH of the system to 7 with ammonia water (an aqueous solution containing 25wt% to 28wt% ammonia) while stirring at room temperature. Continue stirring for 12 hours and then transfer the solution to a 100ml hydrothermal reactor. Place the reactor in an oven at 180 degrees Celsius for 5 hours and then cool to room temperature. Filter the solution, wash with deionized water until neutral, and then vacuum dry in an oven at 80 degrees Celsius for 18 hours.

[0033] Example 6

[0034] Add 9g of manganese sulfate to 40ml of water and stir at room temperature for a few minutes. Then add 4g of magnesium oxide and adjust the pH of the system to 7 with ammonia water (an aqueous solution containing 25wt% to 28wt% ammonia) while stirring at room temperature. Continue stirring for 12 hours and then transfer the solution to a 100ml hydrothermal reactor. Place the reactor in an oven at 180 degrees Celsius for 5 hours and then cool to room temperature. Filter the solution, wash with deionized water until neutral, and then vacuum dry in an oven at 80 degrees Celsius for 18 hours.

[0035] The catalytic application of the manganese-based catalyst for synthesizing adiponitrile according to the present application can be achieved by the scheme in Example 7: the product obtained after the reaction is adiponitrile, and the product yield and selectivity are determined by chromatography internal standard method.

[0036] Comparison of the catalyst prepared above for synthesizing adiponitrile from cyclohexene oxide

[0037]

[0038] Example 7

[0039] The manganese-based catalyst prepared in Examples 1-6 (100 mol% of the amount of manganese based on the amount of cyclohexene oxide used), 196 mg of cyclohexene oxide, 10 mol% of tetrabutylammonium bromide, and 10 mol% of ammonium iodide were sequentially added to a 25 mL pressure vessel lined with polytetrafluoroethylene, the reaction vessel was closed, 0.7 MPa of ammonia was first filled into the vessel, then oxygen was used to increase the pressure of the vessel to 1.5 MPa, and the reaction was carried out at 100°C for 12 h. After the reaction was completed, the reaction vessel was cooled to room temperature, and the pressure was slowly released by slow release of gas. Then, 30 mg of 4-ethylbiphenyl was added to the reaction solution, and gas chromatography analysis was performed.

[0040] Example 8

[0041] 6 g of potassium permanganate was added to 20 ml of deionized water, and stirred at room temperature until completely dissolved. 9 g of manganese sulfate aqueous solution was added to 40 ml of water, and the latter was added dropwise to the former. Under the condition of stirring at room temperature, ammonia (25 wt% to 28 wt% ammonia aqueous solution) was used to adjust the pH of the system to 9. After continuous stirring for 12 h, it was transferred into a 100 ml hydrothermal kettle, and placed in a 180 degree oven for 5 h. After cooling to room temperature, it was filtered, washed with deionized water until neutral, and vacuum dried in an 80 degree oven for 18 hours.

[0042] The manganese-based catalyst (200 mol% of the amount of manganese based on the amount of cyclohexene oxide used) described above, 196 mg of cyclohexene oxide, 20 mol% of ammonium iodide, and 4 mL of acetonitrile were sequentially added to a 25 mL pressure vessel lined with polytetrafluoroethylene, the reaction vessel was closed, 0.7 MPa of ammonia was first filled into the vessel, then oxygen was used to increase the pressure of the vessel to 1.5 MPa, and the reaction was carried out at 100°C for 12 h. After the reaction was completed, the reaction vessel was cooled to room temperature, and the pressure was slowly released by slow release of gas. Then, 30 mg of 4-ethylbiphenyl was added to the reaction solution, and gas chromatography analysis was performed, and the conversion rate of cyclohexene oxide was 100%, and the yield of adiponitrile was 82%.

[0043] Example 9

[0044] Into 20 ml of deionized water, 6 g of potassium permanganate was added and stirred at room temperature until completely dissolved. Into 40 ml of water, 9 g of manganese sulfate aqueous solution was added, and the latter was added dropwise into the former. The system was adjusted to pH 10 with ammonia (25 wt% to 28 wt% ammonia aqueous solution) under stirring at room temperature. After 12 h of continuous stirring, it was transferred into a 100 ml autoclave, and placed in a 120 degree oven for 5 h. After cooling to room temperature, it was filtered, washed with deionized water until neutral, and vacuum dried in an 80 degree oven for 18 h.

[0045] Into a 25 ml polytetrafluoroethylene-lined pressure vessel, the above manganese-based catalyst (200 mol% of the amount of epoxycyclohexane based on manganese), 196 mg of epoxycyclohexane, 20 mol% of ammonium iodide, and 4 mL of acetonitrile were sequentially added. The reaction vessel was closed, and then 0.7 MPa of ammonia was filled into the vessel, and then the pressure in the vessel was increased to 1.5 MPa with oxygen. The reaction was carried out at 100°C for 12 h. After the reaction was completed, the reaction vessel was cooled to room temperature, and then the pressure was slowly released by slow gas release. To the reaction solution, 4-ethylbiphenyl was added, and the conversion rate of epoxycyclohexane was 100% and the yield of adiponitrile was 75% by gas chromatography analysis.

[0046] Example 10

[0047] Into 20 ml of deionized water, 6 g of potassium permanganate was added and stirred at room temperature until completely dissolved. Into 40 ml of water, 9 g of manganese sulfate aqueous solution was added, and the latter was added dropwise into the former. The system was adjusted to pH 10 with ammonia (25 wt% to 28 wt% ammonia aqueous solution) under stirring at room temperature. After 12 h of continuous stirring, it was transferred into a 100 ml autoclave, and placed in a 180 degree oven for 5 h. After cooling to room temperature, it was filtered, washed with deionized water until neutral, and vacuum dried in an 80 degree oven for 18 h.

[0048] Into a 25 ml polytetrafluoroethylene-lined pressure vessel, the above manganese-based catalyst (200 mol% of the amount of epoxycyclohexane based on manganese), 196 mg of epoxycyclohexane, 20 mol% of ammonium iodide, and 4 mL of acetonitrile were sequentially added. The reaction vessel was closed, and then 0.7 MPa of ammonia was filled into the vessel, and then the pressure in the vessel was increased to 1.5 MPa with oxygen. The reaction was carried out at 100°C for 12 h. After the reaction was completed, the reaction vessel was cooled to room temperature, and then the pressure was slowly released by slow gas release. To the reaction solution, 4-ethylbiphenyl was added, and the conversion rate of epoxycyclohexane was 100% and the yield of adiponitrile was 75% by gas chromatography analysis.

Claims

1. Use of a manganese-based catalyst in the synthesis of adiponitrile from cyclohexene oxide, characterized in that: the manganese-based catalyst comprises one or more than two of manganese oxide or supported manganese oxide; the manganese oxide is obtained by reduction of a high-valence manganese salt; the preparation process of the manganese oxide is as follows: potassium permanganate is weighed and added to water, and stirred at room temperature until dissolved; manganese sulfate is weighed and added to water, and stirred at room temperature until dissolved; the manganese sulfate solution is added dropwise into the potassium permanganate solution to obtain a mixed solution, and then the mixed solution is adjusted to a pH value of 7-10 with ammonia water, and stirred at room temperature for 0.5-12 hours, and then transferred into an autoclave, and kept at 100-180℃ for 3-12 hours, and then cooled, filtered, washed with deionized water until neutral, and vacuum dried to obtain the target catalyst; the preparation process of the supported manganese oxide is as follows: the carrier is dispersed in the manganese sulfate aqueous solution, and stirred at room temperature, and the pH value of the mixed solution is adjusted to 7-10 with ammonia water, and the stirring is continued at room temperature for 12-24 hours, and then transferred into an autoclave, and kept at 100-180℃ for 3-12 hours, and then cooled, filtered, washed with deionized water until neutral, and vacuum dried to obtain the target catalyst. The carrier is one or more than two of silicon dioxide, aluminum oxide, magnesium oxide, hydroxyapatite, and hydrotalcite. The aluminum oxide is one or more than two of α-Al2O3, β-Al2O3, and γ-Al2O3.

4. The use according to claim 1, characterized in that:

2. Use according to claim 1, characterized in that: the preparation process of the manganese oxide or the supported manganese oxide is as follows: transferred into an autoclave, and kept at 100-180℃ for 3-12 hours in an oven, and then cooled, filtered, washed with deionized water until neutral, and vacuum dried to obtain the target catalyst.

3. Use according to claim 2, characterized in that: The vacuum drying treatment is that the solid is vacuumed at 60-100℃ for 12-24 hours. The mass percentage of manganese in the supported manganese oxide is 20%-60%. In the presence of the manganese-based catalyst, oxygen is used as the oxidant, ammonia is used as the ammonia source, cyclohexene oxide is used as the raw material, an additive is added, and the reaction is carried out in an organic solvent under the conditions of an ammonia gas pressure of 0.1-0.7 MPa, an oxygen gas pressure of 0.5-2.0 MPa, a reaction temperature of 70-120℃, and a reaction time of 4-24 hours, and then the product adiponitrile is obtained, and the additive is any one or more than two of ammonium fluoride, ammonium bromide, ammonium iodide, and tetrabutylammonium bromide. The organic solvent is any one or more than two of toluene, acetonitrile, 1,4-dioxane, 1,2-dichloroethane, dimethyl sulfoxide, N,N-dimethylformamide, n-heptane, and tetrahydrofuran; and the reaction temperature is 100℃, and the reaction time is 12 hours.

5. Use according to claim 1 or 4, characterized in that: ​ 6. Use according to claim 1 or 2, characterized in that: ​ 7. Use according to claim 1, characterized in that: ​ 8. Use according to claim 7, characterized in that, ​

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