Method for preparing isopropanolamine from acrylonitrile

Abstract

The invention discloses a method for preparing isopropanolamine from acrylonitrile, which comprises the following steps: mixing acrylonitrile, a tetrahydrofuran aqueous solution and a catalyst, heating and refluxing, stirring and reacting for 12-24 hours under the protection of nitrogen, cooling, filtering, and removing the catalyst to obtain an isopropanolazonitrile-tetrahydrofuran-aqueous solution; the method comprises the following steps: adding Ni powder into an isopropanol nitrile-tetrahydrofuran-water solution, mixing, adding into a hydrogenation reaction kettle, carrying out hydrogenation reaction at the reaction temperature of 70-90 DEG C, and carrying out heat preservation reaction for 10-12 hours; and cooling, discharging, and carrying out reduced pressure distillation on the feed liquid to obtain isopropanolamine. According to the method, amine is obtained through nitrile hydrogenation in the reaction process, products are single and are monoisopropanolamine, products such as diisopropanolamine and triisopropanolamine do not exist, follow-up purification is facilitated, and high energy consumption of separation is greatly reduced.

Description

Technical Field

[0001] The present invention belongs to the field of isopropanolamine synthesis, and particularly relates to a method for preparing isopropanolamine from acrylonitrile. Background Art

[0002] Isopropanolamine is the common name of 1-amino-2-propanol (chemical formula: CH 3 CH(OH)CH 2 NH 2 ), also known as monoisopropanolamine. Isopropanolamine has a wide range of applications and is an important intermediate for many fine chemicals. It is widely used in the synthesis of various surfactants and intermediates of fine chemicals (such as pesticides, flavors, fragrances, pharmaceutical chemicals, etc.).

[0003] Currently, there are mainly two methods for synthesizing isopropanolamine:

[0004] Method 1: Using 1,2-propanediol as the starting material. For example, patent document CN112125814 A discloses: (a) reacting 1,2-propanediol under the action of a dehydrogenation catalyst to obtain 2-hydroxypropanal; (b) reacting the 2-hydroxypropanal obtained in step (1) with liquid ammonia and hydrogen under the action of a hydrogenation catalyst to prepare monoisopropanolamine. This method first requires specifically oxidizing the hydroxyl group at the 1st position of 1,2-propanediol to an aldehyde group, and then further obtaining isopropanolamine under the action of liquid ammonia and hydrogen. The reaction conditions are harsh and there are many side reactions, which is not suitable for industrial production.

[0005] Method 2: Using propylene oxide as the starting material. For example, patent documents CN110327967A, CN110981738A, CN101265196 B, WO 2021 / 099456 Al, etc. disclose using propylene oxide as the starting material, reacting with ammonia water or liquid ammonia, and using zeolite composed of trivalent or tetravalent metal oxides as the catalyst to synthesize a mixture of isopropanolamine series. By controlling the feeding ratio or subsequent step-by-step separation and other means, three products of monoisopropanolamine, diisopropanolamine, and triisopropanolamine are synthesized.

[0006] Currently, Method 2 has become the mainstream method for industrial production of isopropanolamine and has been industrialized.

[0007] However, the process of using propylene oxide as the starting material and reacting with ammonia water or liquid ammonia under high-pressure conditions to obtain isopropanolamine still has problems such as harsh reaction conditions, poor product selectivity, low yield, and high energy consumption for subsequent separation. In addition, the starting material propylene oxide is a hazardous chemical with low boiling point, flammable, explosive, and highly toxic properties, and it is dangerous to explode when it encounters the other raw material ammonia water in the reaction, which greatly reduces the safety and energy efficiency of the process.

[0008] Therefore, it can be seen that the current production of isopropanolamine has problems such as high production cost, high danger, and many by-products. Summary of the Invention

[0009] The purpose of this section is to outline some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of the present application, to avoid obscuring the purpose of this section, the abstract, and the title. However, such simplifications or omissions shall not be used to limit the scope of the present invention.

[0010] In view of the above and / or problems existing in the prior art, the present invention is proposed.

[0011] Therefore, the purpose of the present invention is to overcome the deficiencies in the prior art and provide a method for preparing isopropanolamine from acrylonitrile.

[0012] To solve the above technical problems, the present invention provides the following technical solution: A method for preparing isopropanolamine from acrylonitrile, comprising:

[0013] Mix acrylonitrile, an aqueous solution of tetrahydrofuran, and a catalyst, heat under reflux, stir and react for 12 - 24 h under nitrogen protection, cool and filter to remove the catalyst, and obtain isopropionitrile - tetrahydrofuran - aqueous solution;

[0014] Add Ni powder to the isopropionitrile - tetrahydrofuran - aqueous solution, mix, add it to a hydrogenation reaction kettle, carry out hydrogenation reaction, the reaction temperature is 70 - 90 °C, and keep the temperature for reaction for 10 - 12 h;

[0015] Cool down, discharge the material, and subject the material liquid to vacuum distillation to obtain isopropanolamine.

[0016] As a preferred embodiment of the method of the present invention, wherein: the preparation method of the catalyst comprises:

[0017] Cut industrial wool felt into pieces of 1 mm - 2 mm in size, wash it with double - distilled water and absolute ethanol 3 - 4 times successively, filter and add it to absolute ethanol, and set aside;

[0018] Add palladium chloride dihydrate PdCl 2 ·2H 2 O and ferric chloride hexahydrate FeCl 3 ·6H 2 O to the wool felt ethanol solution, heat to reflux, and stir overnight under nitrogen protection;

[0019] After the reaction is completed, cool to room temperature, then filter the product, wash it with absolute ethanol, and dry it to obtain brown fragments, which are the catalyst.

[0020] As a preferred embodiment of the method of the present invention, wherein: the industrial wool felt, palladium chloride dihydrate PdCl 2 ·2H 2 O and ferric chloride hexahydrate FeCl 3 ·6H 2 O have a mass ratio of 80 to 100: 0.5 to 0.7: 2 to 2.7.

[0021] As a preferred embodiment of the method of the present invention, wherein: the concentration of the tetrahydrofuran aqueous solution is 60% V / V.

[0022] As a preferred embodiment of the method of the present invention, wherein: the ratio of acrylonitrile, the tetrahydrofuran aqueous solution and the catalyst is 100 mL: 1000 mL: 5 to 10 g.

[0023] As a preferred embodiment of the method of the present invention, wherein: Ni powder is added to the isopropanol nitrile-tetrahydrofuran-aqueous solution, and the ratio of the isopropanol nitrile-tetrahydrofuran-aqueous solution to Ni powder is 1000 to 1100 mL: 1 to 9 g.

[0024] As a preferred embodiment of the method of the present invention, wherein: the temperature reduction includes reducing the temperature to room temperature.

[0025] As a preferred embodiment of the method of the present invention, wherein: the feed liquid is subjected to vacuum distillation, wherein the vacuum distillation temperature is 80 to 90 °C and the vacuum degree is -0.08 to -0.09 MPa.

[0026] Advantages of the present invention:

[0027] (1) The present invention provides a method for preparing isopropanolamine from acrylonitrile. The starting raw material acrylonitrile is widely used in synthetic fibers, synthetic rubbers and synthetic resins, such as polyacrylonitrile, nylon 66, nitrile rubber, ABS resin, polyacrylamide, acrylate esters, etc. At the same time, it is also used in organic synthesis intermediates, pesticides, grain fumigants, etc. It is the second largest acrylonitrile derivative after polypropylene, and is cheap and easily available.

[0028] (2) The reaction process of the present invention is to obtain an amine by nitrile hydrogenation. The product is single, all being mono-isopropanolamine, and there are no products such as di-isopropanolamine and tri-isopropanolamine, which is beneficial to subsequent purification and greatly reduces the high energy consumption of separation.

[0029] (3) The process of the present invention is relatively simple, the product quality is high, the purification cost is low, the equipment investment is small, and the production operation is safe, meeting the needs of large-scale industrial production. Brief Description of the Drawings

[0030] To more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the accompanying drawings required for the description of the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can be obtained based on these drawings. Among them:

[0031] Figure 1 This is the GC detection chart of the isopropanolamine prepared in Example 1 of the present invention.

[0032] Figure 2 The isopropanolamine prepared in Example 1 of the present invention 1 1H NMR chart.

[0033] Figure 3 This is the GC detection chart of the isopropanolamine prepared in Example 2 of the present invention.

[0034] Figure 4 This is the GC detection chart of the isopropanolamine prepared in Example 3 of the present invention. Detailed implementation manners

[0035] To make the above objects, features, and advantages of the present invention more obvious and understandable, the following will provide a detailed description of the specific implementation manners of the present invention in combination with the embodiments of the specification.

[0036] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can also be implemented in other ways different from those described herein. Those skilled in the art can make similar extensions without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0037] Secondly, the so-called "one embodiment" or "embodiment" herein refers to a specific feature, structure, or characteristic that can be included in at least one implementation manner of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment that mutually excludes other embodiments.

[0038] The technical problem to be solved by the present invention is to establish a new method for synthesizing isopropanolamine with high purity and suitable for industrialization using simple, easily available, and inexpensive raw materials. The main steps are as follows:

[0039]

[0040] Starting from acrylonitrile, first undergo hydration under the catalysis of chromium acetylacetonate, and then undergo a hydrogenation reaction with hydrogen under the action of a nickel-based catalyst to obtain a crude product of isopropanolamine, and then directly obtain high-purity mono-isopropanolamine through rectification.

[0041] The raw materials in the embodiments of the present invention are all ordinary commercially available products.

[0042] Example 1

[0043] This example provides a method for preparing isopropanolamine from acrylonitrile. The main steps are as follows:

[0044] 1. Hydration

[0045] (1) Preparation of catalyst

[0046] Cut 100 g of industrial wool felt into pieces of 1 mm - 2 mm in size, wash it 3 times successively with 500 mL of double-distilled water and anhydrous ethanol, filter it and add it to 100 mL of anhydrous ethanol for standby;

[0047] Add 0.7 g of palladium chloride dihydrate PdCl 2 ·2H 2 O and 2.7 g of ferric chloride hexahydrate FeCl 3 ·6H 2 O to the above-mentioned wool felt ethanol solution, heat it to reflux, and stir overnight under nitrogen protection;

[0048] After the reaction is completed, cool it to room temperature, filter the product, wash it with anhydrous ethanol, and then dry it to obtain 80 g of brown fragments, which are the catalysts (wool-Pd-Fe) required for the first-step reaction.

[0049] (2) Hydration reaction

[0050] Add the above 10 g of catalyst and 100 mL of acrylonitrile to 1000 mL of 60% (V / V) tetrahydrofuran aqueous solution, heat it to reflux, stir overnight (12 h) under nitrogen protection, cool and filter after the reaction is completed to remove the catalyst, and obtain isopropanol nitrile-tetrahydrofuran-aqueous solution.

[0051] 2. Hydrogenation

[0052] Mix the isopropanol nitrile-tetrahydrofuran-aqueous solution (1100 mL) with 5 g of Ni powder, add it to a 2 L hydrogenation reactor, add 22 g of hydrogen from the hydrogenation port under stirring, raise the temperature to control the reaction temperature at 90 °C, keep the temperature for 12 h, and stop heating when the pressure no longer changes;

[0053] Cool down, discharge the material, transfer the material liquid to a 2 L round-bottom flask, and perform vacuum distillation to obtain 42 g of pure isopropanolamine. The 1 1H NMR spectrum of isopropanolamine is shown in Figure 2 ;

[0054] The total conversion rate of monoethanolamine is 56.3%. After GC detection (see Figure 1 ), the purity of monoisopropanolamine is greater than 98%;

[0055] Among them, total conversion rate (%) = (number of moles of actual product / number of moles of theoretically obtainable product) × 100%.

[0056] Example 2

[0057] 1. Hydration

[0058] (1) Preparation of catalyst

[0059] Same as Example 1.

[0060] (2) Hydration reaction

[0061] Add the above 5 g of catalyst and 100 mL of acrylonitrile to 1000 mL of a 60% (V / V) aqueous solution of tetrahydrofuran, heat to reflux, stir under nitrogen protection for 24 h, cool and filter after the reaction is completed to remove the catalyst, and obtain isopropyl cyanohydrin - tetrahydrofuran - aqueous solution.

[0062] 2. Hydrogenation

[0063] Mix the mixture (1100 mL) obtained from the first - step reaction with 1 g of Ni powder, add it to a 2 - L hydrogenation reactor, add 44 g of hydrogen from the hydrogenation inlet under stirring, raise the temperature to control the reaction temperature at 90 °C, keep the temperature for 6 h, and stop heating when the pressure no longer changes;

[0064] Lower the temperature, discharge the material, transfer the liquid to a 2 - L round - bottom flask, and perform vacuum distillation to obtain 38.7 g of pure isopropanolamine. The conversion rate of monoethanolamine is 51.8%. After GC detection (see Figure 3 ) the purity of isopropanolamine is greater than 98%.

[0065] Example 3

[0066] 1. Hydration

[0067] (1) Preparation of catalyst

[0068] Same as Example 1.

[0069] (2) Hydration reaction

[0070] Add the above 1 g of catalyst and 100 mL of acrylonitrile to 1000 mL of a 60% (V / V) aqueous solution of tetrahydrofuran, heat to reflux, stir under nitrogen protection for 24 h, cool and filter after the reaction is completed to remove the catalyst, and obtain isopropyl cyanohydrin - tetrahydrofuran - aqueous solution.

[0071] 2. Hydrogenation

[0072] Mix the mixture (1100 mL) obtained from the first-step reaction with 1 g of nickel powder, add it to a 2 L hydrogenation reactor, and while stirring, add 22 g of hydrogen from the hydrogenation inlet. Raise the temperature to control the reaction temperature at 100 °C, keep the temperature constant for 12 h, and stop heating when the pressure no longer changes.

[0073] Cool down the temperature, discharge the material, transfer the liquid material to a 1 L round-bottom flask, and perform vacuum distillation to obtain 18.7 g of pure isopropanolamine. The conversion rate of monoethanolamine is 25%, and by GC detection (see Figure 4 ) the content of isopropanolamine is greater than 50%.

[0074] Comparative Example 1

[0075] (1) Preparation of catalyst (wool-Pd-Fe)

[0076] Cut 100 g of industrial wool felt into small pieces of 1 - 2 mm in size, wash it three times successively with 500 mL of double-distilled water and anhydrous ethanol. After each washing, remove the impurities by filtration, and add the washed wool felt to 100 mL of anhydrous ethanol.

[0077] Add 0.7 g of palladium dichloride dihydrate (PdCl 2 ·2H 2 O) and 2.7 g of iron(III) chloride hexahydrate (FeCl 3 ·6H 2 O) to the wool felt ethanol solution, heat it to reflux under nitrogen protection, and stir the reaction overnight.

[0078] After the reaction is completed, wait for the solution to cool to room temperature, filter the product and wash it with anhydrous ethanol. Finally, dry the catalyst to obtain 80 g of brown granular solid, which is the required catalyst (wool-Pd-Fe).

[0079] (2) Preparation of isopropionitrile-tetrahydrofuran-aqueous solution

[0080] Mix 10 g of the catalyst (wool-Pd-Fe) prepared above with 100 mL of acrylonitrile, and add it to 1000 mL of 60% (V / V) tetrahydrofuran aqueous solution. Heat the mixture to the reflux temperature and stir the reaction for 12 h under nitrogen protection.

[0081] After the reaction is completed, cool it to room temperature, filter to remove the catalyst, and obtain a tetrahydrofuran-aqueous solution containing isopropionitrile.

[0082] (3) Preparation of isopropanolamine by hydrogenation reaction

[0083] Mix the 1100 mL of isopropyl cyanide - tetrahydrofuran - aqueous solution obtained in (2) with 5 g of Co - Mo catalyst powder (Mo powder, 325 mesh, purity 99%, Co powder, 500 mesh, purity 99%, prepared by mixing in a mass ratio of 1:1), and add it to a 2 - liter hydrogenation reactor;

[0084] Start stirring, and introduce 22 g of hydrogen from the hydrogenation inlet. Heat up to 90 °C and maintain this temperature for reaction for 12 hours;

[0085] After the reaction is completed, cool down to room temperature and stop the hydrogenation reaction. When the reaction pressure no longer changes, stop heating. Subsequently, take out the reactants, transfer them to a 2 - liter round - bottom flask, and remove the solvent by vacuum distillation, but pure isopropanolamine cannot be separated.

[0086] Comparative Example 2

[0087] (1) Prepare the catalyst (wool - Pd - Fe)

[0088] Cut 100 g of industrial wool felt into small pieces of 1 - 2 mm in size, wash it three times successively with 500 mL of double - distilled water and anhydrous ethanol, remove impurities by filtration after each washing, and add the washed wool felt to 100 mL of anhydrous ethanol for standby;

[0089] Add 0.7 g of palladium dichloride dihydrate (PdCl 2 ·2H 2 O) to the wool felt ethanol solution, heat it to reflux under nitrogen protection, and stir the reaction overnight;

[0090] After the reaction is completed, wait for the solution to cool to room temperature, filter the product and wash it with anhydrous ethanol, and finally dry the catalyst. Finally, 60 g of brown fragments, namely the required catalyst (wool - Pd - Fe), are obtained.

[0091] (2) Prepare isopropyl cyanide - tetrahydrofuran - aqueous solution

[0092] Mix 10 g of the catalyst (wool - Pd - Fe) prepared above with 100 mL of acrylonitrile, and add it to 1000 mL of 60% (V / V) tetrahydrofuran aqueous solution;

[0093] Heat the mixture to reflux and stir the reaction for 12 h under nitrogen protection; after the reaction is completed, cool it to room temperature, filter to remove the catalyst, and obtain isopropyl cyanide - tetrahydrofuran - aqueous solution.

[0094] (3) Prepare isopropanolamine by hydrogenation reaction

[0095] Mix the 1100 mL of isopropyl cyanide - tetrahydrofuran - aqueous solution obtained in step (2) with 5 g of nickel (Ni) catalyst powder, and add it to a 2 - L hydrogenation reactor;

[0096] Under stirring, 22 g of hydrogen gas was added from the hydrogenation port, the temperature was raised to 90 °C and the reaction was maintained at this temperature for 12 h. After the reaction was completed, the temperature was lowered to room temperature and heating was stopped;

[0097] When the reaction pressure no longer changed, hydrogenation was stopped;

[0098] Subsequently, the reaction product was taken out and transferred to a 2 L round-bottom flask. The solvent was removed by vacuum distillation, and finally 3 g of crude isopropanolamine was obtained, with a yield of less than 5%.

[0099] The present invention provides a method for preparing isopropanolamine from acrylonitrile. The starting raw material acrylonitrile is widely used in synthetic fibers, synthetic rubbers and synthetic resins, such as polyacrylonitrile, nylon 66, nitrile rubber, ABS resin, polyacrylamide, acrylate esters, etc. At the same time, it is also used in organic synthesis intermediates, pesticides, grain fumigants, etc. It is the second largest acrylonitrile derivative after polypropylene, and is cheap and easily available; the reaction process of the present invention is to obtain amine by nitrile hydrogenation, and the product is single, all being mono-isopropanolamine, without products such as di-isopropanolamine and tri-isopropanolamine, which is beneficial to subsequent purification and greatly reduces the high energy consumption of separation; the process of the present invention is relatively simple, the product quality is high, the purification cost is low, the equipment investment is small, and the production operation is safe, meeting the needs of large-scale industrial production.

[0100] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not restrictive. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered within the scope of the present invention.

Claims

1. A method for preparing isopropanolamine from acrylonitrile, characterized in that: include, acrylonitrile, tetrahydrofuran aqueous solution and Pd-Fe catalyst are mixed, heated to reflux, stirred for reaction for 12 to 24 hours under nitrogen protection, cooled, filtered, and the catalyst is removed to obtain isopropanol nitrile-tetrahydrofuran-water solution; Add Ni powder to isopropanol nitrile-tetrahydrofuran-water solution, add the mixture to a hydrogenation reactor, perform hydrogenation reaction at a temperature of 70-90°C, and keep the reaction temperature for 10-12h; The temperature is lowered, the material is discharged, and the liquid is distilled under reduced pressure to obtain isopropanolamine.

2. The method according to claim 1, characterized in that: The catalyst, and its preparation method comprises: Cut the industrial wool felt into pieces of 1mm to 2mm in size, wash it with double distilled water and anhydrous ethanol for 3 to 4 times, filter it and add it to anhydrous ethanol for later use; Add palladium chloride dihydrate PdCl2·2H2O and ferric chloride hexahydrate FeCl3·6H2O to the wool felt ethanol solution, heat to reflux temperature (about 80°C), and stir for 18-24 hours under nitrogen protection; After the reaction is completed, the mixture is cooled to room temperature, and the product is filtered, washed with anhydrous ethanol, and dried to obtain brown fragments, namely the catalyst.

3. The method according to claim 2, characterized in that: The mass ratio of the industrial wool felt, palladium chloride dihydrate PdCl2·2H2O and ferric chloride hexahydrate FeCl3·6H2O is 80-100: 0.5-0.7: 2-2.

7.

4. The method according to any one of claims 1 to 3, characterized in that: The concentration of the tetrahydrofuran aqueous solution is 60% V / V.

5. The method according to claim 4, characterized in that: The ratio of the acrylonitrile, the tetrahydrofuran aqueous solution and the catalyst is 100 mL: 1000 mL: 5-10 g.

6. The method according to claim 1, characterized in that: The Ni powder is added to the isopropanol nitrile-tetrahydrofuran-water solution and mixed, wherein the ratio of the isopropanol nitrile-tetrahydrofuran-water solution to the Ni powder is 1000-1100 mL: 1-9 g.

7. The method according to claim 1, characterized in that: The cooling includes cooling to room temperature.

8. The method according to claim 1, characterized in that: The feed liquid is subjected to reduced pressure distillation, wherein the reduced pressure distillation temperature is 80 to 90° C. and the vacuum degree is -0.08 to -0.09 MPa.

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