A refining device for nitrogen-containing solvent precursor and a refining method and application thereof

Abstract

The application discloses a refining device and method and application of a nitrogen-containing solvent precursor. The refining method takes liquid-phase material obtained through cryogenic separation of a gas-phase mixture obtained through an ammoniation reaction as raw material, and obtains acetonitrile main product, acetamide by-product and recycled unreacted raw material through the steps of side-line rectification, component rough separation, three-waste separation and differential pressure separation, and avoids the discharge of polluting gas by dissolving trace impurities and non-condensable gas at low temperature through self-produced wastewater. The application can be used for the separation and refining of liquid-phase reaction product of methyl acetate ammoniation acetonitrile, and is simple in process, friendly to environment, easy to operate and suitable for industrialized large-scale continuous production.

Description

TECHNICAL FIELD

[0001] The application relates to a refining device and method and application of a nitrogen-containing solvent precursor, and belongs to the technical field of chemical industry. BACKGROUND

[0002] Acetonitrile is a colorless transparent liquid compound with a sweet taste, is an important fine chemical raw material, is widely used in the synthesis of pharmaceutical, pesticide and chemical intermediates, and is also a good organic solvent. At present, the mature acetonitrile synthesis route only has two kinds of acetonitrile by-product method and acetic acid ammoniation dehydration method. The acetonitrile yield of the former is seriously restricted by the acrylonitrile production capacity, the raw material of the latter has strong corrosion, and at the same time, the raw material price affects the profit space to be sharply compressed. New acetonitrile preparation routes are basically in the laboratory research stage and have not been industrialized, so it is necessary to continuously research.

[0003] The acetic acid methyl ester ammoniation dehydration process is a low-cost and high-product-purity acetonitrile preparation method, and the industrialization difficulty of the method lies in the separation of raw materials and non-condensable gas phase impurities and the refining process of acetonitrile products. SUMMARY

[0004] In order to overcome the problem of difficult separation of raw materials and non-condensable gas phase impurities in the reaction process of acetic acid methyl ester ammoniation for preparing acetonitrile, the application provides a refining method for the liquid phase crude product of the method, which is simple in process, friendly to the environment, easy to operate and suitable for industrialized large-scale continuous production.

[0005] According to one aspect of the application, a refining method of a nitrogen-containing solvent precursor is provided, comprising the following steps:

[0006] A. The ammoniation product is introduced into a deamination tower, and is separated and condensed, ammonia gas is obtained from the top of the tower, and an intermediate product I is obtained from the bottom of the tower;

[0007] B. The intermediate product I is introduced into a light-removing tower, and is operated at a pressure, a material II containing methyl acetate, methanol and acetonitrile is obtained from the top of the tower, a light-removing product is obtained from the bottom of the tower, the dehydrogenation product is introduced into a wastewater tower, and is subjected to vacuum rectification, an acetamide product is obtained from the bottom of the tower;

[0008] C. The material II is introduced into a de-esterification tower, and is subjected to total condensation rectification, a material III containing methyl acetate and methanol is obtained from the top of the tower, and an intermediate product II containing acetonitrile and methanol is obtained from the bottom of the tower;

[0009] D. The intermediate product II is introduced into a high-pressure tower, and is subjected to pressurization, a material IV containing methanol and acetonitrile is obtained from the top of the tower, and an acetonitrile product is obtained from the bottom of the tower;

[0010] E. The material IV is introduced into a low-pressure tower, and is subjected to pressure release, a material V containing methanol and acetonitrile is obtained from the top of the tower, and is introduced into the high-pressure tower, and a methanol product is obtained from the bottom of the tower;

[0011] The molar composition of the aminated product is:

[0012] Methyl acetate 0.005-0.2%;

[0013] Ammonia 30-80%;

[0014] Acetonitrile 5-25%;

[0015] Acetamide 0.1-1.0%;

[0016] Methanol 3-30%;

[0017] Dimethyl ether 0.001-1.5%;

[0018] Water 5-25%.

[0019] Optionally, in step A, the material I is introduced into an absorption tank and mixed with water.

[0020] Optionally, in step B, water vapor obtained from the top of the wastewater column is condensed by a wastewater cooler and introduced into the absorption tank.

[0021] Optionally, in step A, the reflux ratio of the deamination column is 200-1000, the theoretical plate number is 10-80, the top temperature is -20-60°C, and the operating pressure is 200-900 kPaA.

[0022] Optionally, in step B, the reflux ratio of the light-removing column is 0.1-10, the theoretical plate number is 10-80, the top temperature is -40-80°C, and the operating pressure is 0.01-10 kPaA.

[0023] Optionally, the reflux ratio of the wastewater column is 0.1-10, the theoretical plate number is 10-80, the top temperature is 10-60°C, and the operating pressure is 0.01-200 kPaA.

[0024] Optionally, in step C, the reflux ratio of the deesterification column is 100-900, the theoretical plate number is 10-80, the top temperature is 20-80°C, and the operating pressure is 0-200 kPaA.

[0025] Optionally, in step D, the reflux ratio of the high-pressure column is 0.1-30, the theoretical plate number is 10-80, the top temperature is 50-150°C, and the operating pressure is 150-600 kPaA.

[0026] Optionally, in step E, the reflux ratio of the low-pressure column is 0.1-30, the theoretical plate number is 10-80, the top temperature is 30-150°C, and the operating pressure is 20-300 kPaA.

[0027] Optionally, the operating pressure of the absorption tank is 1-300 kPaA and the operating temperature is 1-40℃.

[0028] Optionally, the operating temperature of the wastewater cooler is 1-40℃.

[0029] According to still another aspect of the present application, there is provided a refining device for nitrogen-containing solvent precursor, comprising a deaminating column, a light-removing column, a wastewater column, a de-esterifying column, a high-pressure column and a low-pressure column,

[0030] The overhead outlet of the deaminating column is connected with the absorption tank, the ammonia gas outlet of the deaminating column is connected with the reaction unit, and the bottom outlet of the deaminating column is connected with the material inlet of the light-removing column;

[0031] The overhead outlet of the light-removing column is connected with the material inlet of the de-esterifying column, and the bottom outlet of the light-removing column is connected with the wastewater column;

[0032] The bottom outlet of the wastewater column is connected with the acetamide recovery unit;

[0033] The overhead outlet of the de-esterifying column is connected with the methyl acetate recovery unit, and the bottom outlet of the de-esterifying column is connected with the material inlet of the high-pressure column;

[0034] The overhead outlet of the high-pressure column is connected with the material inlet of the low-pressure column, and the bottom outlet of the high-pressure column is connected with the acetonitrile recovery unit;

[0035] The overhead outlet of the low-pressure column is connected with the material inlet of the high-pressure column, and the bottom outlet of the low-pressure column is connected with the methanol recovery unit.

[0036] Optionally, the overhead outlet of the wastewater column is connected with the absorption tank, and a wastewater cooler is arranged between the overhead outlet of the wastewater column and the absorption tank.

[0037] Optionally, the absorption tank is a gas-liquid mixer.

[0038] Optionally, the gas-liquid mixer comprises a two-phase mixing pipeline of an adiabatic container or an internal injection nozzle inserted below the liquid surface.

[0039] According to still another aspect of the present application, there is provided a separation and refining method for the liquid-phase reaction product of methyl acetate ammoniation to acetonitrile, which is selected from the above-mentioned refining method.

[0040] The beneficial effects that can be produced by the present application include:

[0041] The refining method for nitrogen-containing solvent precursor provided by the present application is continuous in process, can be used for separation and refining of the liquid-phase reaction product of methyl acetate ammoniation to acetonitrile, has simple flow, is environmentally friendly, easy to operate, and suitable for industrialized large-scale continuous production. Attached Figure Description

[0042] Figure 1 This is a schematic diagram of a purification method for a nitrogen-containing solvent precursor according to this application.

[0043] 1. Ammonia removal tower, 2. Light weight removal tower, 3. Wastewater tower, 4. Deesterification tower, 5. High-pressure tower, 6. Low-pressure tower, 7. Wastewater cooler, 8. Absorption tank. Detailed Implementation

[0044] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0045] Example 1

[0046] The separated raw material (mole composition: methyl acetate 0.05%, ammonia 54.09%, acetonitrile 14.61%, acetamide 0.91%, methanol 15.34%, water 14.82%, dimethyl ether 0.06%) is first fed into the deamination column 1, the overhead pressure of the deamination column 1 is 700 kPaA, the overhead temperature is 9°C, 30 theoretical plates are provided, and the reflux ratio is 700. Dimethyl ether with a mole content of 19.90% is separated at the overhead of the deamination column 1 and is fed into the absorption tank 8, where it is mixed with waste water for absorption and is discharged after being cooled by the waste water cooler 7 to 10°C. Ammonia with a mole concentration of 99.97% is taken from the 8th theoretical plate of the deamination column 1 and can be used as a circulating raw material in the reaction unit. The material obtained at the bottom of the deamination column 1 is fed into the light-removing column 2, the overhead pressure of the light-removing column 2 is 1.5 kPaA, the overhead temperature is -18°C, 30 theoretical plates are provided, and the reflux ratio is 3. A mixture containing methyl acetate, methanol and acetonitrile is separated at the overhead of the light-removing column 2 and is fed into the deesterification column 4. The light-removed material obtained at the bottom of the light-removing column 2 is fed into the waste water column 3. The overhead pressure of the deesterification column 4 is 109 kPaA, the overhead temperature is 56°C, 60 theoretical plates are provided, and the reflux ratio is 600. Impurity oil containing methyl acetate and methanol is separated at the overhead of the deesterification column 4 and is fed into the methyl acetate recovery unit. The mixture of methanol and acetonitrile obtained at the bottom of the deesterification column 4 is fed into the high-pressure column 5. The overhead pressure of the high-pressure column 5 is 300 kPaA, the overhead temperature is 95°C, 50 theoretical plates are provided, and the reflux ratio is 10. Through rectification separation, the high-pressure column 5 obtains methyl acetate / acetonitrile azeotrope at the overhead, which is fed into the low-pressure column 6. The high-pressure column 5 obtains acetonitrile with a mole purity of 99.98% at the bottom, which is fed into the acetonitrile recovery unit. The overhead pressure of the low-pressure column 6 is 110 kPaA, the overhead temperature is 66°C, 50 theoretical plates are provided, and the reflux ratio is 15. The low-pressure column 6 obtains methyl acetate / acetonitrile azeotrope at the overhead, which is fed back into the high-pressure column 5 for separation. The low-pressure column 6 obtains methanol with a mole purity of 99.96% at the bottom, which is fed into the methanol recovery unit. The waste water column 3 receives the light-removed material from the bottom of the light-removing column 2, the overhead pressure is 1.5 kPaA, the overhead temperature is 16°C, 40 theoretical plates are provided, and the reflux ratio is 0.6. Waste water is obtained at the overhead of the waste water column 3, which is cooled by the waste water cooler 7 to 10°C and is then fed into the absorption tank 8. The absorption tank 8 obtains acetamide with a mole purity of 99.92% at the bottom.

[0047] The above is only a few embodiments of the present application, and does not limit the present application in any form. Although the preferred embodiments are disclosed above, the present application is not limited thereto. Any person skilled in the art can make some changes or modifications to the disclosed technical content without departing from the scope of the technical solution of the present application, which are equivalent to equivalent embodiments and belong to the scope of the technical solution.

Claims

1. A method for purifying a nitrogen-containing solvent precursor, characterized in that, Includes the following steps: A. The ammoniation product is fed into the deammoniation tower, where it is condensed. The top of the tower yields material I containing dimethyl ether, the side stream yields ammonia, and the bottom of the tower yields intermediate product I. B. The intermediate product I is fed into a light-light product removal tower. Under operating pressure, material II containing methyl acetate, methanol and acetonitrile is obtained at the top of the tower, and the light-light product is obtained at the bottom of the tower. The light-light product is fed into a wastewater tower and subjected to vacuum distillation to obtain acetamide product at the bottom of the tower. C. Pass the material II into a deesterification tower and perform total condensation distillation. The top of the tower yields material III containing methyl acetate and methanol, and the bottom of the tower yields intermediate product II containing acetonitrile and methanol. D. The intermediate product II is fed into a high-pressure tower and pressurized. The top of the tower yields material IV containing methanol and acetonitrile, and the bottom of the tower yields acetonitrile product. E. The material IV is fed into a low-pressure tower to release the pressure. The material V containing methanol and acetonitrile is obtained at the top of the tower and fed into the high-pressure tower. The methanol product is obtained at the bottom of the tower. The molar composition of the amination product is as follows: Methyl acetate 0.005~0.2%; Ammonia 30-80%; Acetonitrile 5~25%; Acetamide 0.1~1.0%; Methanol 3~30%; Dimethyl ether 0.001~1.5%; Water content: 5-25%.

2. The refining method according to claim 1, characterized in that, In step A, material I is introduced into the absorption tank and mixed with water.

3. The refining method according to claim 2, characterized in that, In step B, the water vapor obtained at the top of the wastewater tower is condensed by the wastewater cooler and then introduced into the absorption tank.

4. The refining method according to claim 1, characterized in that, In step A, the reflux ratio of the deammoniation tower is 200~1000, the theoretical number of plates is 10~80, the tower top temperature is -20~60℃, and the operating pressure is 200~900kPaA.

5. The refining method according to claim 1, characterized in that, In step B, the reflux ratio of the light-light-removal tower is 0.1~10, the theoretical number of plates is 10~80, the tower top temperature is -40~80℃, and the operating pressure is 0.01~10kPaA.

6. The refining method according to claim 1, characterized in that, The wastewater tower has a reflux ratio of 0.1 to 10, a theoretical number of plates of 10 to 80, a top temperature of 10 to 60°C, and an operating pressure of 0.01 to 200 kPaA.

7. The refining method according to claim 1, characterized in that, In step C, the reflux ratio of the deesterification tower is 100~900, the number of theoretical plates is 10~80, the top temperature of the tower is 20~80℃, and the operating pressure is 0~200kPaA.

8. The refining method according to claim 1, characterized in that, In step D, the reflux ratio of the high-pressure tower is 0.1~30, the theoretical number of plates is 10~80, the tower top temperature is 50~150℃, and the operating pressure is 150~600kPaA.

9. The refining method according to claim 1, characterized in that, In step E, the reflux ratio of the low-pressure tower is 0.1~30, the theoretical number of plates is 10~80, the tower top temperature is 30~150℃, and the operating pressure is 20~300kPaA.

10. The refining method according to claim 2, characterized in that, The operating pressure of the absorption tank is 1~300 kPaA, and the operating temperature is 1~40℃.

11. The refining method according to claim 3, characterized in that, The operating temperature of the wastewater cooler is 1~40℃.

12. The application of a purification apparatus for a nitrogen-containing solvent precursor in the purification method according to any one of claims 1 to 11, characterized in that, The refining unit includes an ammonia removal tower, a light volatile organic compound (SVC) removal tower, a wastewater treatment tower, a deesterification tower, a high-pressure tower, and a low-pressure tower. The top outlet of the ammonia removal tower is connected to the absorption tank, the ammonia outlet of the ammonia removal tower is connected to the reaction unit, and the bottom outlet of the ammonia removal tower is connected to the material inlet of the light nitrate removal tower. The top outlet of the light component removal tower is connected to the material inlet of the deesterification tower, and the bottom outlet of the light component removal tower is connected to the wastewater tower. The bottom outlet of the wastewater tower is connected to the acetamide recovery unit; The top outlet of the deesterification tower is connected to the methyl acetate recovery unit, and the bottom outlet of the deesterification tower is connected to the material inlet of the high-pressure tower. The top outlet of the high-pressure tower is connected to the material inlet of the low-pressure tower, and the bottom outlet of the high-pressure tower is connected to the acetonitrile recovery unit. The top outlet of the low-pressure tower is connected to the feed inlet of the high-pressure tower, and the bottom outlet of the low-pressure tower is connected to the methanol recovery unit.

13. The application according to claim 12, characterized in that, The top outlet of the wastewater tower is connected to the absorption tank, and a wastewater cooler is provided between the top outlet of the wastewater tower and the absorption tank.

14. The application according to claim 12, characterized in that, The absorption tank is a gas-liquid mixer.

15. The application according to claim 14, characterized in that, The gas-liquid mixer includes a two-phase mixing pipe with a gas inlet inserted into an insulated container or an internal nozzle below the liquid surface.

16. A method for separating and purifying the liquid-phase reaction products of the amination of methyl acetate to acetonitrile, characterized in that, The separation and purification method is selected from the purification method according to any one of claims 1 to 11.

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