A purification apparatus and method for nitrogen-containing compounds and their applications.

Abstract

This application discloses a purification apparatus, purification method, and application for nitrogen-containing compounds. The purification apparatus includes a light-light-removal tower, an ammonia recovery tower, a separation tower, a product tower, a wastewater tower, a wastewater cooler, and an absorption tank. The top of the light-light-removal tower is connected to the absorption tank; the bottom of the light-light-removal tower is connected to the ammonia recovery tower, which is connected to the separation tower; the top of the separation tower is connected to the product tower, and the bottom of the separation tower is connected to the wastewater tower; the top of the wastewater tower is connected to the wastewater cooler, which is connected to the absorption tank; the light-light-removal tower has an inlet; and the product tower and wastewater tower have outlets for the purified nitrogen-containing compound products. The nitrogen-containing compound purification apparatus disclosed in this application can be used for the purification of reaction products from the amination of methyl acetate to acetonitrile, is environmentally friendly, and suitable for large-scale continuous industrial operation.

Description

Technical Field

[0001] This application relates to a purification apparatus and method for nitrogen-containing compounds and their applications, belonging to the field of chemical technology. Background Technology

[0002] Acetonitrile is a colorless, transparent, sweet-tasting liquid compound and an important raw material for fine chemicals. It is widely used in the synthesis of pharmaceutical and pesticide intermediates and is also a high-performance organic solvent. Currently, there are only two mature acetonitrile synthesis routes: the acrylonitrile by-product method and the acetic acid ammoniation dehydration method. The former's acetonitrile production is severely limited by acrylonitrile production capacity, while the latter's raw materials are highly corrosive, and profit margins are drastically compressed due to raw material prices. New acetonitrile preparation routes are mostly in the laboratory research stage and have not yet been explored for industrial application; therefore, continued research is necessary.

[0003] The ammoniation and dehydration process of methyl acetate is a low-cost, high-purity method for producing acetonitrile. The industrialization challenge of this method lies in the separation of raw materials and non-condensable gaseous impurities and the purification process of the acetonitrile product. This invention provides a purification method for nitrogen-containing compounds obtained by this method, which is continuous, environmentally friendly, and suitable for large-scale continuous industrial operation. Summary of the Invention

[0004] According to one aspect of this application, a purification apparatus for nitrogen-containing compounds is provided, the purification apparatus comprising a light-light-removal tower, an ammonia recovery tower, a separation tower, a product tower, a wastewater tower, a wastewater cooler, and an absorption tank;

[0005] The top of the light-weight removal tower is connected to the absorption tank;

[0006] The bottom of the light component removal tower is connected to the ammonia recovery tower, and the ammonia recovery tower is connected to the separation tower;

[0007] The top of the separation tower is connected to the product tower, and the bottom of the separation tower is connected to the wastewater tower.

[0008] The top of the wastewater tower is connected to a wastewater cooler, and the wastewater cooler is connected to the absorption tank.

[0009] The light-weight removal tower is equipped with an inlet;

[0010] The product tower and wastewater tower are equipped with outlets for the refined products containing nitrogen compounds.

[0011] Optionally, the reflux ratio of the light-light-removal tower is 0.1 to 20.

[0012] Optionally, the theoretical number of plates in the light-light removal tower is 10 to 80.

[0013] Optionally, the top temperature of the light-weight removal tower is -20 to 60°C, and the operating pressure is 200 to 900 kPaA.

[0014] Optionally, the reflux ratio of the ammonia recovery tower is 0.1 to 10.

[0015] Optionally, the ammonia recovery tower has a theoretical number of trays of 10 to 80.

[0016] Optionally, the top temperature of the ammonia recovery tower is -20 to 60°C, and the operating pressure is 0.5 to 600 kPaA.

[0017] Optionally, the reflux ratio of the separation tower is 0.1 to 20.

[0018] Optionally, the separation tower has 10 to 80 theoretical plates.

[0019] Optionally, the top temperature of the separation tower is 20–120°C, and the operating pressure is 0.5–600 kPaA.

[0020] Optionally, the reflux ratio of the product tower is 1 to 50.

[0021] Optionally, the product tower has 20 to 100 theoretical plates.

[0022] Optionally, the top temperature of the product tower is 100-200°C, and the operating pressure is 800-2300 kPaA.

[0023] Optionally, the reflux ratio of the wastewater tower is 0.01 to 20.

[0024] Optionally, the theoretical number of trays in the wastewater tower is 10 to 80.

[0025] Optionally, the temperature at the top of the wastewater tower is 10–60°C, and the operating pressure is 0.5–600 kPaA.

[0026] Optionally, the cooling temperature of the wastewater cooler is 15–30°C.

[0027] Optionally, the operating temperature of the absorption tank is 10–40°C, and the operating pressure is 0.5–400 kPaA.

[0028] Optionally, the absorption tank is an insulated container with a gas inlet inserted below the liquid surface, a two-phase mixing pipe with a built-in nozzle, or other types of gas-liquid mixers.

[0029] According to another aspect of this application, a method for purifying a nitrogen-containing compound is provided, the method comprising:

[0030] A nitrogen-containing compound is passed into a reaction apparatus and fractionated to obtain a purified product.

[0031] The reaction apparatus is selected from the purification apparatus for nitrogen-containing compounds described above.

[0032] Optionally, the nitrogen-containing compound comprises the following components on a molar basis:

[0033]

[0034]

[0035] Optionally, the method includes the following steps:

[0036] (1) Nitrogen-containing compounds are passed into the light-light removal tower. After fractionation, the dimethyl ether at the top of the light-light removal tower enters the absorption tank.

[0037] (2) The ammonia at the bottom of the light tower enters the ammonia recovery tower, and the unreacted ammonia gas is separated at the top of the tower. The heavy material at the bottom of the tower enters the separation tower for separation. The light component containing acetonitrile, methanol and methyl acetate is obtained at the top of the separation tower and enters the product tower for separation. Crude methanol is obtained at the top of the product tower and acetonitrile is obtained at the bottom of the product tower.

[0038] (3) The water and acetamide heavy components at the bottom of the separation tower enter the wastewater tower. The wastewater at the bottom of the separation tower is cooled by the wastewater cooler and then enters the absorption tank. Acetamide is obtained at the bottom of the separation tower.

[0039] Optionally, the method of using the above-described apparatus includes the following steps:

[0040] 1) The raw material is first fed into the light residue removal tower, where dimethyl ether impurities are separated at the top of the tower, along with a small amount of ammonia, and then sent to the absorption tank.

[0041] 2) Ammonia-containing impurities are absorbed by mixing with wastewater in the absorption tank before being discharged;

[0042] 3) The material obtained from the bottom of the light-weight material removal tower is sent to the ammonia recovery tower, where unreacted ammonia is separated at the top and the heavy material obtained from the bottom is sent to the separation tower.

[0043] 4) The separation tower separates the material in the middle. The light component containing acetonitrile, methanol and methyl acetate is obtained at the top of the tower, and the heavy component containing water and acetyl is obtained at the bottom of the tower.

[0044] 5) The bottom material of the separation tower is separated in the wastewater tower to obtain wastewater and intermediate product acetamide. The wastewater is cooled by the wastewater cooler and then sent to the absorption tank.

[0045] 6) The light material at the top of the separation tower is sent to the product tower, where the acetonitrile-methanol azeotropic condition is disrupted under high pressure, resulting in crude methanol at the top of the tower and acetonitrile at the bottom.

[0046] According to another aspect of this application, the application of the above-described purification apparatus in the reaction product of the amination of methyl acetate to acetonitrile is provided.

[0047] In this application, a method for purifying nitrogen-containing compounds is disclosed, using a liquid product obtained after flash evaporation separation of an amination product as raw material (the raw material molar composition is methyl acetate 0.005–0.2%, ammonia 30.0–80.0%, acetonitrile 5.0–25.0%, acetamide 0.1–1.0%, methanol 3.0–30.0%, water 5.0–25.0%, and dimethyl ether 0.001–1.5%). The apparatus comprises the following parts:

[0048] The system consists of a light component removal tower, an ammonia recovery tower, a separation tower, a product tower, a wastewater tower, a wastewater cooler, and an absorption tank. The refined raw material is first fed into the light component removal tower, where dimethyl ether impurities and a small amount of entrained ammonia are separated at the top. This residue is then sent to the absorption tank, where it is mixed with wastewater and absorbed before being discharged. The bottom material from the light component removal tower is sent to the ammonia recovery tower, where unreacted ammonia is separated at the top, and the heavy material at the bottom is sent to the separation tower. The separation tower divides the material in half, yielding a light component containing acetonitrile, methanol, and methyl acetate at the top, and a heavy component containing water and acetamide at the bottom. The bottom material is further separated in the wastewater tower to obtain wastewater and the intermediate product acetamide. The wastewater is cooled by the wastewater cooler and then sent to the absorption tank. The light material from the top is sent to the product tower, where the acetonitrile-methanol azeotropic condition is disrupted under high pressure, yielding crude methanol at the top and acetonitrile at the bottom.

[0049] The beneficial effects that this application can produce include:

[0050] This application uses a liquid product obtained after crude separation of an amination product as raw material. Through steps such as light impurity separation, light raw material recovery, high-pressure azeotropic decomposition, and wastewater separation, acetonitrile product and recycled gaseous and liquid raw materials and intermediate products are obtained. Trace amounts of non-condensable impurities are dissolved in self-produced wastewater at low temperatures, avoiding the emission of polluting gases. The process is continuous, and the refining unit can be used for refining the reaction product of methyl acetate amination to acetonitrile. It is environmentally friendly and suitable for large-scale continuous industrial operation. Attached Figure Description

[0051] Figure 1 This is a schematic diagram of the purification apparatus for liquid-phase nitrogen-containing compounds in Example 1 of this application.

[0052] in:

[0053] 1. Light weight removal tower; 2. Ammonia recovery tower; 3. Separation tower; 4. Product tower; 5. Wastewater tower; 6. Wastewater cooler; 7. Absorption tank. Detailed Implementation

[0054] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0055] Unless otherwise specified, all raw materials used in the embodiments of this application were purchased through commercial channels.

[0056] Example 1

[0057] like Figure 1 The diagram shows a purification apparatus for nitrogen-containing compounds. The purification apparatus includes a light-weight removal tower 1, an ammonia recovery tower 2, a separation tower 3, a product tower 4, a wastewater tower 5, a wastewater cooler 6, and an absorption tank 7. The top of the light-weight removal tower 1 is connected to the absorption tank 7; the bottom of the light-weight removal tower 1 is connected to the ammonia recovery tower 2, and the ammonia recovery tower 2 is connected to the separation tower 3; the top of the separation tower 3 is connected to the product tower 4, and the bottom of the separation tower 3 is connected to the wastewater tower 5; the top of the wastewater tower 5 is connected to the wastewater cooler 6, and the wastewater cooler 6 is connected to the absorption tank 7. The absorption tank 7 is an insulated container with a gas inlet inserted below the liquid surface, a two-phase mixing pipe with a built-in nozzle, or another type of gas-liquid mixer. The light-weight removal tower 1 is equipped with an inlet; the product tower 4 and the wastewater tower 5 are equipped with outlets for the purified nitrogen-containing compound products.

[0058] Example 2

[0059] The raw materials (molar composition: methyl acetate 0.05%, ammonia 54.09%, acetonitrile 14.61%, acetamide 0.91%, methanol 15.34%, water 14.82%, dimethyl ether 0.06%) are first fed into the light component removal tower 1. The top pressure of tower 1 is 700 kPaA, the top temperature is 7°C, and it has 30 theoretical plates with a reflux ratio of 1.5. At the top of tower 1, waste gas with a dimethyl ether molar content of 28.19% is separated and sent to absorption tank 7. In the absorption tank, it is adiabatically mixed with wastewater and then discharged. The material obtained from the bottom of tower 1 is sent to ammonia recovery tower 2. The top pressure of recovery tower 2 is 300 kPaA, the top temperature is -9°C, and it has 30 theoretical plates with a reflux ratio of 0.15. At the top of recovery tower 2, unreacted ammonia gas with a molar purity of 99.99% is separated, and the heavy material obtained from the bottom is sent to tower 3. Separation tower 3 has a top pressure of 105 kPaA and a top temperature of 71°C. It has 40 theoretical plates and a reflux ratio of 1. Separation tower 3 separates the material in the middle. The top of separation tower 3 yields a light component containing acetonitrile, methanol, and methyl acetate, while the bottom of separation tower 3 yields a heavy component containing water and acetamide. The bottom material of separation tower 3 is sent to wastewater tower 5. Wastewater tower 5 has a top pressure of 9 kPaA and a top temperature of 44°C. It has 30 theoretical plates and a reflux ratio of 0.08. The material is separated in wastewater tower 5 to obtain wastewater and the intermediate product acetamide. The wastewater is cooled to 25°C by wastewater cooler 6 and then sent to absorption tank 7. The light material at the top of separation tower 3 is sent to product tower 4. The pressure at the top of product tower 4 is 1900 kPaA, the temperature at the top of the tower is 164℃, and it is equipped with 80 theoretical plates and a reflux ratio of 9. Under high pressure, the acetonitrile-methanol azeotropic condition is destroyed, and crude methanol is obtained at the top of product tower 4, while acetonitrile is obtained at the bottom of product tower 4.

[0060] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A purification apparatus for nitrogen-containing compounds, characterized in that, The refining device includes a light-light removal tower (1), an ammonia recovery tower (2), a separation tower (3), a product tower (4), a wastewater tower (5), a wastewater cooler (6), and an absorption tank (7). The top of the light removal tower (1) is connected to the absorption tank (7); The bottom of the light-light removal tower (1) is connected to the ammonia recovery tower (2), and the bottom of the ammonia recovery tower (2) is connected to the separation tower (3). The top of the separation tower (3) is connected to the product tower (4), and the bottom of the separation tower (3) is connected to the wastewater tower (5). The top of the wastewater tower (5) is connected to the wastewater cooler (6), and the wastewater cooler (6) is connected to the absorption tank (7). The light-removal tower (1) is equipped with an inlet; The product tower (4) and wastewater tower (5) are equipped with outlets for the refined products containing nitrogen compounds.

2. The refining apparatus according to claim 1, characterized in that, The reflux ratio of the light-light removal tower (1) is 0.1~20; The theoretical number of plates in the light removal tower (1) is 10 to 80. The temperature at the top of the light-removal tower (1) is -20~60℃, and the operating pressure is 200~900kPaA.

3. The refining apparatus according to claim 1, characterized in that, The reflux ratio of the ammonia recovery tower (2) is 0.1~10; The theoretical number of trays in the ammonia recovery tower (2) is 10 to 80. The temperature at the top of the ammonia recovery tower (2) is -20~60 ℃, and the operating pressure is 0.5~600kPaA.

4. The refining apparatus according to claim 1, characterized in that, The reflux ratio of the separation tower (3) is 0.1~20; The theoretical number of plates in the separation tower (3) is 10 to 80. The top temperature of the separation tower (3) is 20~120 ℃ and the operating pressure is 0.5~600kPaA.

5. The refining apparatus according to claim 1, characterized in that, The reflux ratio of the product tower (4) is 1~50; The theoretical number of plates in the product tower (4) is 20 to 100. The top temperature of the product tower (4) is 100~200 ℃ and the operating pressure is 800~2300 kPaA.

6. The refining apparatus according to claim 1, characterized in that, The reflux ratio of the wastewater tower (5) is 0.01~20; The theoretical number of trays in the wastewater tower (5) is 10 to 80. The temperature at the top of the wastewater tower (5) is 10~60 ℃, and the operating pressure is 0.5~600kPaA; The cooling temperature of the wastewater cooler (6) is 15~30℃; The operating temperature of the absorption tank (7) is 10~40℃ and the operating pressure is 0.5~400kPaA.

7. A method for purifying nitrogen-containing compounds, characterized in that, The method includes: A nitrogen-containing compound is passed into a reaction apparatus and fractionated to obtain a purified product. The reaction apparatus is selected from the purification apparatus for nitrogen-containing compounds according to any one of claims 1 to 6.

8. The refining method according to claim 7, characterized in that, Based on molar composition, the nitrogen-containing compound comprises the following components: Methyl acetate 0.005~0.2%; Ammonia 30.0%~80.0%; Acetonitrile 5.0~25.0%; Acetamide 0.1~1.0%; Methanol 3.0~30.0%; Water content: 5.0% to 25.0%; Dimethyl ether 0.001~1.5%.

9. The refining method according to claim 7, characterized in that, The method includes the following steps: (1) Nitrogen-containing compounds are introduced into the light-light removal tower. After fractionation, the dimethyl ether at the top of the light-light removal tower enters the absorption tank. (2) The ammonia at the bottom of the light tower enters the ammonia recovery tower, and the unreacted ammonia gas is separated at the top of the tower. The heavy material at the bottom of the tower enters the separation tower for separation. The light component containing acetonitrile, methanol and methyl acetate is obtained at the top of the separation tower and enters the product tower for separation. Crude methanol is obtained at the top of the product tower and acetonitrile is obtained at the bottom of the product tower. (3) The water and acetamide heavy components at the bottom of the separation tower enter the wastewater tower. The wastewater at the bottom of the separation tower is cooled by the wastewater cooler and then enters the absorption tank. Acetamide is obtained at the bottom of the separation tower.

10. The use of the purification apparatus according to any one of claims 1 to 6 in the reaction product of the amination of methyl acetate to acetonitrile.

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