A continuous distillation apparatus and method for crude m-phenylenediamine

Abstract

This invention relates to a continuous distillation apparatus and method for crude m-phenylenediamine. The apparatus includes a first light-removal column (1), a first reboiler (2), a first column bottom circulation pump (3), a first column bottom outlet pump (4), a first column top condenser (5), a first column top reflux tank (6), a first column top reflux outlet pump (7), a second light-removal column (8), a second reboiler (9), a second column bottom circulation pump (10), a second column bottom outlet pump (11), a second column top condenser (12), a second column top reflux tank (13), a second column top reflux outlet pump (14), a product column (15), a product column reboiler (16), a product column bottom circulation pump (17), a product column bottom outlet pump (18), a product column top condenser (19), a product column top reflux tank (20), and a product column top reflux outlet pump (21). The continuous distillation method for m-phenylenediamine of this invention can obtain m-phenylenediamine with a purity of 99.99%.

Description

Technical Field

[0001] This invention relates to the field of chemical technology, particularly to the field of IPC B01D9, and more specifically, to a continuous distillation apparatus and method for crude m-phenylenediamine. Background Technology

[0002] m-Phenylenediamine (MXDA) is a colorless liquid at room temperature. It is a high-performance epoxy resin curing agent and a widely used, high-value-added fine chemical. Industrially, m-Phenylenediamine is typically produced from isophthalonitrile using a batch autoclave or continuous fixed-bed hydrogenation process under the action of a catalyst. Currently, both processes produce byproducts in practical applications. Insufficient hydrogenation produces the byproduct 3-cyanobenzylamine, while excessive hydrogenation produces the byproduct 1,3-cyclohexanedimethylamine. During hydrogenation, imine condensation forms condensation polymers of secondary amines. Existing batch autoclave catalytic hydrogenation processes for producing m-Phenylenediamine generally use Raney nickel or modified Raney nickel as catalysts, with reaction pressures of 5-12 MPa and temperatures of 90-120℃, achieving an actual yield of 80-90%. This method suffers from problems such as high pressure, high temperature, and poor catalyst selectivity. In particular, after the catalyst is reused multiple times, the reaction will produce a large number of impurities, mainly including the hydrogenation intermediate 3-cyanobenzylamine, the condensation polymer secondary amine, the deamination product 3-methylbenzylamine, and the over-hydrogenation product 1,3-cyclohexanedimethylamine.

[0003] Current technologies primarily focus on the synthesis route and process optimization of m-phenylenediamine (m-phenylenediamine), as well as innovations in hydrogenation catalyst synthesis, while reports on product purification are relatively scarce. With the increasingly widespread application of m-phenylenediamine in polyurethane, nylon resins, and other fields, the demand for high-purity m-phenylenediamine will continue to increase. Therefore, impurities generated during the m-phenylenediamine synthesis process severely affect the product quality and application in chemical production, making purification a crucial step. Currently, m-phenylenediamine is mainly purified through evaporation / distillation. Industrially synthesized m-phenylenediamine before purification mainly consists of liquid ammonia, solvents, MXDA, low-boiling-point byproducts, and high-boiling-point byproducts. To obtain high-purity MXDA, product purification is essential. First, evaporation removes all used solvents, ammonia, and low-boiling-point byproducts, yielding crude m-phenylenediamine. This crude product is then distilled to remove higher-boiling-point impurities. Because the boiling points of m-phenylenediamine and its low-boiling-point byproducts 3-cyanobenzylamine, 3-methylbenzylamine, and 1,3-cyclohexanedimethylamine are close, the distillation method is ineffective in removing impurities and it is difficult to obtain high-purity m-phenylenediamine.

[0004] Chinese invention patent CN104148080A discloses a method for preparing m-phenylenediamine by continuous hydrogenation in a fixed bed. The process uses a modified nickel catalyst, with a pressure of 10-15 MPa and a temperature of 120-150℃. The m-phenylenediamine product obtained by this method contains some intermediate 3-cyanobenzylamine that has not reacted completely, affecting the purity. Summary of the Invention

[0005] The first aspect of the present invention provides a continuous distillation apparatus for crude m-phenylenediamine, comprising: a first light-removal column, a first reboiler, a first column bottom circulation pump, a first column bottom discharge pump, a first column top condenser, a first column top reflux tank, a first column top reflux discharge pump, a second light-removal column, a second reboiler, a second column bottom circulation pump, a second column bottom discharge pump, a second column top condenser, a second column top reflux tank, a second column top reflux discharge pump, a product column, a product column reboiler, a product column bottom circulation pump, a product column bottom discharge pump, a product column top condenser, a product column top reflux tank, and a product column top reflux discharge pump.

[0006] The top of the first light-light removal tower is connected to the first top condenser, the first top reflux pump, the second light-light removal tower, and the second bottom pump. The first top condenser is connected to the first top reflux pump via the first top reflux tank. The bottom of the first light-light removal tower is connected to the first bottom circulation pump and the first bottom pump. The first bottom circulation pump is connected to the first light-light removal tower via the first reboiler.

[0007] The first column bottom pump is connected to the product column. The top of the product column is connected to the product column top condenser and the product column top reflux pump. The product column top condenser is connected to the product column top reflux tank and the product column top reflux pump. The bottom of the product column is connected to the product column bottom circulation pump and the product column bottom pump. The product column bottom circulation pump is connected to the product column via the product column reboiler.

[0008] The top of the second light-light removal tower is connected to the second top condenser and the second top reflux pump, respectively. The second top condenser is connected to the second top reflux tank and the second top reflux pump. The bottom of the second light-light removal tower is connected to the second bottom circulation pump and the second bottom pump, respectively. The second bottom circulation pump is connected to the second light-light removal tower via the second reboiler.

[0009] This application research found that setting up a combination of a first light component removal tower and a second light component removal tower effectively separates the light components in crude m-phenylenediamine, improving the overall distillation yield of the system. The first light component removal tower, by sacrificing some of the m-phenylenediamine product yield from the bottom of the tower, collects a portion of the m-phenylenediamine and all the light components together from the top of the first light component removal tower, achieving a better separation effect. All the light components and a portion of the m-phenylenediamine collected from the top of the first light component removal tower are then re-distilled through the second light component removal tower. A large amount of light components is collected from the top of the second light component removal tower, while crude m-phenylenediamine containing a small amount of light components is collected from the bottom of the second light component removal tower. This crude m-phenylenediamine collected from the bottom of the second light component removal tower is then returned to the first light component removal tower for distillation. The second light component removal tower can recover m-phenylenediamine from the light components, further improving the overall distillation yield of the system. The m-phenylenediamine after the light components have been removed is then passed through a product tower to remove the heavy secondary amine component, and high-purity m-phenylenediamine is collected from the top of the product tower.

[0010] A second aspect of the present invention provides a method for continuous distillation of crude m-phenylenediamine, comprising the following steps:

[0011] S1, crude m-phenylenediamine is fed into the first light component removal tower. The mixture of light component and m-phenylenediamine is collected at the top of the first light component removal tower, and m-phenylenediamine containing heavy component is collected at the bottom of the first light component removal tower.

[0012] S2, the mixture collected from the top of the first light component removal tower is fed into the second light component removal tower. The light component is collected from the top of the second light component removal tower. The crude m-phenylenediamine containing the light component is collected from the bottom of the second light component removal tower, and the crude m-phenylenediamine collected from the bottom of the second light component removal tower is returned to the first light component removal tower for feeding.

[0013] S3, the m-phenylenediamine containing heavy components collected from the bottom of the first light component removal tower is fed into the product tower. The m-phenylenediamine is collected at the top of the product tower, and the heavy components are collected from the bottom of the product tower.

[0014] The crude m-phenylenediamine product is prepared by hydrogenating isophthalonitrile and then removing the solvent.

[0015] The raw materials for preparing the crude m-phenylenediamine product include: isophthalonitrile, solvent, catalyst and hydrogen.

[0016] Preferably, the solvent comprises methanol and toluene, wherein the weight ratio of methanol to toluene is 1:(0.5-3).

[0017] More preferably, the weight ratio of methanol to toluene is 1:(1-2).

[0018] The crude m-phenylenediamine product comprises, by weight percentage: 75-99% m-phenylenediamine, 0.5-15% light component and 0.5-15% heavy component; the light component includes at least one of 3-cyanobenzylamine, 3-methylbenzylamine and 1,3-cyclohexanedimethylamine.

[0019] Preferably, the crude m-phenylenediamine product comprises, by weight percentage: 85-96% m-phenylenediamine, 0.5-2% light components, and 3-12% heavy components; the light components include 3-cyanobenzylamine, 3-methylbenzylamine, and 1,3-cyclohexanedimethylamine.

[0020] Both the first and second light-light removal towers contain an alkali in their reboilers. The alkali is selected from at least one of NaOH (sodium hydroxide), KOH (potassium hydroxide), Na3PO4 (sodium phosphate), Na2HPO4 (sodium hydrogen phosphate), K3PO4 (potassium phosphate), K2HPO4 (potassium hydrogen phosphate), PhCOONa (sodium benzoate), PhCOOK (potassium benzoate), CH3COONa (sodium acetate), and CH3COOK (potassium acetate).

[0021] Preferably, the alkali is selected from at least one of PhCOONa, PhCOOK, CH3COONa, and CH3COOK.

[0022] The amount of alkali added to the bottom of the first light-removal tower is 0.01 to 1 wt‰ of the m-phenylenediamine feed; the amount of alkali added to the bottom of the second light-removal tower is 0.01 to 0.5 wt‰ of the m-phenylenediamine feed.

[0023] Preferably, the alkali added to the bottom of the first light-removal tower accounts for 0.05 to 0.5 wt‰ of the m-phenylenediamine feed; and the alkali added to the bottom of the second light-removal tower accounts for 0.02 to 0.2 wt‰ of the m-phenylenediamine feed.

[0024] The first light-light removal tower, the second light-light removal tower, and the product tower all include packing materials, which include at least one of the following: self-corrugated packing, grid packing, wire mesh packing, Pall rings, conjugate rings, cross rings, and θ mesh rings.

[0025] Preferably, the packing includes at least one of corrugated packing, grid packing, wire mesh packing, Pall rings, and conjugate rings.

[0026] The content of intermediate phenylenediamine in the top product of the tower is greater than 99.99 wt%.

[0027] The parameters of the first light-light removal tower include: 25 to 150 trays, reflux ratio of 1:(0.1-10), top temperature of 90 to 180°C, bottom temperature of 120 to 250°C, and top pressure of 0.1 to 12 kPa.

[0028] Preferably, the parameters of the first light-light removal tower include: the number of trays, including but not limited to 25, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, and 150; the reflux ratio, including but not limited to 1:10, 1:5, 1:2, 1:1, 2:1, 5:1, and 10:1; the tower top temperature, including but not limited to 90℃, 100℃, 110℃, 120℃, 130℃, 140℃, 150℃, 160℃, 170℃, and 180℃; the tower bottom temperature, including but not limited to 120℃, 140℃, 160℃, 180℃, 200℃, 220℃, 240℃, and 250℃; and the tower top pressure, including but not limited to 0.1KPa, 0.5KPa, 1KPa, 2KPa, 4KPa, 6KPa, 8KPa, 10KPa, and 12KPa.

[0029] More preferably, the parameters of the first light-light removal tower include: 40 to 100 trays, reflux ratio of 1:(0.2-5), top temperature of 100 to 140°C, bottom temperature of 140 to 200°C, and top pressure of 1 to 10 kPa.

[0030] More preferably, the parameters of the first light-light removal tower include: 40 to 100 trays, reflux ratio of 1:(0.2-5), top temperature of 130 to 140°C, bottom temperature of 170 to 190°C, and top pressure of 4 to 6 kPa.

[0031] The parameters of the second light-light removal tower include: 15 to 120 trays, reflux ratio of 1:(0.125-8), top temperature of 80 to 180°C, bottom temperature of 100 to 220°C, and top pressure of 0.1 to 12 kPa.

[0032] Preferably, the parameters of the second light-light removal tower include: the number of trays, including but not limited to 15, 25, 35, 45, 60, 80, 100, and 120; the reflux ratio, including but not limited to 1:8, 1:4, 1:2, 1:1, 2:1, 4:1, and 8:1; the tower top temperature, including but not limited to 80℃, 90℃, 100℃, 120℃, 140℃, 160℃, and 180℃; the tower bottom temperature, including but not limited to 100℃, 120℃, 140℃, 160℃, 180℃, 200℃, 210℃, and 220℃; and the tower top pressure, including but not limited to 0.1KPa, 0.5KPa, 1KPa, 2KPa, 4KPa, 6KPa, 8KPa, 10KPa, and 12KPa.

[0033] More preferably, the parameters of the second light-light removal tower include: 20 to 80 trays, reflux ratio of 1:(0.25-4), top temperature of 90 to 140°C, bottom temperature of 120 to 180°C, and top pressure of 1 to 8 kPa.

[0034] More preferably, the parameters of the second light-light removal tower include: 20 to 80 trays, reflux ratio of 1:(0.25-4), top temperature of 120 to 140°C, bottom temperature of 130 to 150°C, and top pressure of 2 to 4 kPa.

[0035] The parameters of the product column include: 40 to 180 trays, reflux ratio of 1:(0.2-10), top temperature of 90 to 200°C, bottom temperature of 120 to 260°C, and top pressure of 0.1 to 10 kPa.

[0036] Preferably, the parameters of the product column include: the number of trays, including but not limited to 40, 50, 60, 70, 80, 100, 120, 140, 160, and 180; the reflux ratio, including but not limited to 1:10, 1:8, 1:6, 1:4, 1:2, 1:1, 2:1, 3:1, 4:1, and 5:1; the top temperature, including but not limited to 90℃, 100℃, 120℃, 140℃, 160℃, 180℃, and 200℃; the bottom temperature, including but not limited to 120℃, 140℃, 160℃, 180℃, 200℃, 220℃, 240℃, and 260℃; and the top pressure, including but not limited to 0.1KPa, 0.5KPa, 1KPa, 2KPa, 4KPa, 6KPa, and 8KPa.

[0037] More preferably, the parameters of the product column include: 55 to 150 trays, reflux ratio of 1:(0.3-5), top temperature of 100 to 145°C, bottom temperature of 140 to 220°C, and top pressure of 1 to 8 kPa.

[0038] More preferably, the parameters of the product column include: 55 to 150 trays, reflux ratio of 1:(0.3-5), top temperature of 130 to 145°C, bottom temperature of 190 to 220°C, and top pressure of 1 to 3 kPa.

[0039] During the distillation of m-phenylenediamine (PPD), due to the high temperature at the bottom of the distillation column, PPD undergoes intermolecular deamination and polymerization, producing polycyclic heavy impurities, namely secondary amines. This invention adds a small amount of alkali to the bottoms of both the first and second light-light ...

[0040] Beneficial effects

[0041] 1. This invention achieves effective separation of light components in crude m-phenylenediamine by combining a first light component removal tower and a second light component removal tower, thereby improving the overall distillation yield of the system.

[0042] 2. In this invention, a small amount of alkali is added to the bottom of both the first and second light-light removal towers, which can significantly inhibit the intermolecular deamination and polycondensation of m-phenylenediamine and reduce the loss during the distillation process of m-phenylenediamine, thereby improving the yield and purity of m-phenylenediamine.

[0043] 3. By adjusting the parameters of the first light-light removal tower, the second light-light removal tower, and the product tower, this invention can obtain a purity greater than [a certain value].

[0044] The 99.99 wt% m-phenylenediamine content meets the requirements of downstream applications in polyurethane, nylon resin, epoxy resin curing agents, and other fields.

[0045] 4. The continuous distillation method for crude m-phenylenediamine of the present invention is simple to operate and suitable for continuous industrial production.

[0046] 5. The crude m-phenylenediamine used in this invention is prepared by hydrogenating isophthalonitrile and removing the solvent. The raw materials are simple to prepare and widely available, which can effectively reduce production costs. Attached Figure Description

[0047] Figure 1 This is a schematic diagram of the continuous distillation apparatus for crude m-phenylenediamine in Example 1.

[0048] The components are as follows: 1. First light component removal tower; 2. First reboiler; 3. First tower bottom circulation pump; 4. First tower bottom product pump; 5. First tower top condenser; 6. First tower top reflux tank; 7. First tower top reflux product pump; 8. Second light component removal tower; 9. Second reboiler; 10. Second tower bottom circulation pump; 11. Second tower bottom product pump; 12. Second tower top condenser; 13. Second tower top reflux tank; 14. Second tower top reflux product pump; 15. Product tower; 16. Product tower reboiler; 17. Product tower bottom circulation pump; 18. Product tower bottom product pump; 19. Product tower top condenser; 20. Product tower top reflux tank; 21. Product tower top reflux product pump. Detailed Implementation

[0049] Example 1

[0050] A continuous distillation apparatus for crude m-phenylenediamine, such as... Figure 1 As shown, it includes: a first light-light removal tower 1, a first reboiler 2, a first tower bottom circulation pump 3, a first tower bottom outlet pump 4, a first tower top condenser 5, a first tower top reflux tank 6, a first tower top reflux outlet pump 7, a second light-light removal tower 8, a second reboiler 9, a second tower bottom circulation pump 10, a second tower bottom outlet pump 11, a second tower top condenser 12, a second tower top reflux tank 13, a second tower top reflux outlet pump 14, a product tower 15, a product tower reboiler 16, a product tower bottom circulation pump 17, a product tower bottom outlet pump 18, a product tower top condenser 19, a product tower top reflux tank 20, and a product tower top reflux outlet pump 21.

[0051] The top of the first light-light removal tower 1 is connected to the first top condenser 5, the first top reflux pump 7, the second light-light removal tower 8, and the second bottom pump 11, respectively. The first top condenser 5 is connected to the first top reflux pump 7 via the first top reflux tank 6. The bottom of the first light-light removal tower 1 is connected to the first bottom circulation pump 3 and the first bottom pump 4, respectively. The first bottom circulation pump 3 is connected to the first light-light removal tower 1 via the first reboiler 2.

[0052] The first column bottom pump 4 is connected to the product column 15. The top of the product column 15 is connected to the product column top condenser 19 and the product column top reflux pump 21. The product column top condenser 19 is connected to the product column top reflux tank 20 and the product column top reflux pump 21. The bottom of the product column 15 is connected to the product column bottom circulation pump 17 and the product column bottom pump 18. The product column bottom circulation pump 17 is connected to the product column 15 via the product column reboiler 16.

[0053] The top of the second light-light removal tower 8 is connected to the second top condenser 12 and the second top reflux pump 14, respectively. The second top condenser 12 is connected to the second top reflux tank 13 and the second top reflux pump 14. The bottom of the second light-light removal tower 8 is connected to the second bottom circulation pump 10 and the second bottom pump 11, respectively. The second bottom circulation pump 10 is connected to the second light-light removal tower 8 via the second reboiler 9.

[0054] A method for continuous distillation of crude m-phenylenediamine comprises the following steps:

[0055] S1, 1200g of crude m-phenylenediamine is continuously fed into the first light component removal tower 1 at a rate of 600g / h using a metering pump (the first light component removal tower is filled with Suzhou Saipu BRH type Pall ring packing, with a theoretical number of 40 plates). At the same time, PhCOONa is continuously fed into the bottom of the first light component removal tower 1 at a rate of 60mg / h. The pressure at the top of the first light component removal tower 1 is controlled at 5KPa, the temperature at the top of the tower is 140℃, the temperature at the bottom of the tower is 180℃, and the reflux ratio is 1:1. The light component containing m-phenylenediamine is collected from the top of the first light component removal tower 1 at a rate of 30g / h, and the heavy component containing m-phenylenediamine is collected from the bottom of the first light component removal tower 1 at a rate of about 570g / h.

[0056] S2, the light component containing m-phenylenediamine collected from the top of the first light component removal tower 1 is directly fed into the second light component removal tower 8 (the second light component removal tower is filled with Suzhou Saipu BRH type Pall ring packing, with a theoretical plate number of 25) at a rate of about 30 g / h. At the same time, PhCOONa is continuously fed into the bottom of the first light component removal tower 1 at a rate of 6 mg / h. The pressure at the top of the second light component removal tower 8 is controlled at 3 kPa, the top temperature is 120°C, the bottom temperature is 140°C, and the reflux ratio is 1:2. The light component containing m-phenylenediamine is collected from the top of the second light component removal tower 8 at a rate of about 8 g / h, and the crude m-phenylenediamine containing the light component is collected from the bottom of the second light component removal tower 8 at a rate of about 22 g / h and returned to the first light component removal tower 1 for re-distillation.

[0057] S3, the bottom of the first light component removal tower 1, containing m-phenylenediamine, is directly fed into product tower 15 at a rate of approximately 570 g / h. (The product tower is filled with Suzhou Saipu BRH type Pall ring packing, with a theoretical number of 60 plates.) The pressure at the top of product tower 15 is controlled at 2 kPa, the temperature at the top of the tower is 140°C, the temperature at the bottom of the tower is 200°C, and the reflux ratio is 1:3. The bottom of product tower 15 is collected from the heavy component at a rate of approximately 60 g / h, and the top of product tower 15 is collected from the heavy component at a rate of approximately 532 g / h.

[0058] The preparation method of the crude m-phenylenediamine product is as follows: In a 20L high-pressure reactor, add 1200g of isophthalonitrile, 10300g of a mixed solvent of methanol and toluene (mass ratio, methanol:toluene = 1:2), and 500g of ammonia; add a commercial Raney nickel catalyst (Maclean's). Add 100g of Nickel, cover the autoclave, and test the pressure with high-pressure nitrogen (7.5MPaG). Then, replace the air in the autoclave with low-pressure nitrogen (0.6MPaG) and hydrogen (1.0MPaG) three times each. Carry out the hydrogenation reaction at a temperature of 80℃ and a pressure of 6.5MPa with a stirring speed of 600rpm. The reaction time was 240 min. When the instantaneous hydrogen absorption rate dropped to below 30 sccm, stirring was stopped, the hydrogen inlet valve was closed, and circulating water was used to cool the mixture. Then, the residual gas in the reactor was discharged, and the reaction mother liquor was filtered out using a built-in filter. Methanol, toluene, and ammonia were removed by distillation to obtain 1200 g of crude m-phenylenediamine after hydrogenation and solvent removal of isophthalonitrile. The crude m-phenylenediamine was analyzed by gas chromatography, and its composition was: m-phenylenediamine 90.5 wt%, 3-cyanobenzylamine 0.05 wt%, 3-methylbenzylamine 0.55 wt%, 1,3-cyclohexanedimethylamine 0.40 wt%, and the balance being heavy components (secondary amines).

[0059] Example 2

[0060] A continuous distillation apparatus for crude m-phenylenediamine, as described in Example 1.

[0061] A method for continuous distillation of crude m-phenylenediamine comprises the following steps:

[0062] S1, 1200g of crude m-phenylenediamine is continuously fed into the first light component removal tower 1 at a rate of 600g / h using a metering pump (the first light component removal tower is filled with Suzhou Saipu BRH type Pall ring packing, with a theoretical number of 40 plates). At the same time, PhCOONa is continuously fed into the bottom of the first light component removal tower 1 at a rate of 60mg / h. The pressure at the top of the first light component removal tower 1 is controlled at 5KPa, the temperature at the top of the tower is 142℃, the temperature at the bottom of the tower is 182℃, and the reflux ratio is 1:1. The light component containing m-phenylenediamine is collected from the top of the first light component removal tower 1 at a rate of 30g / h, and the heavy component containing m-phenylenediamine is collected from the bottom of the first light component removal tower 1 at a rate of approximately 570g / h.

[0063] S2, the light component containing m-phenylenediamine collected from the top of the first light component removal tower 1 is directly fed into the second light component removal tower 8 (the second light component removal tower is filled with Suzhou Saipu GEH type conjugate ring packing, with 30 theoretical plates) at a rate of about 30 g / h. At the same time, PhCOONa is continuously fed into the bottom of the first light component removal tower 1 at a rate of 6 mg / h. The pressure at the top of the second light component removal tower 8 is controlled at 3 kPa, the top temperature at 125°C, the bottom temperature at 145°C, and the reflux ratio at 1:3. The light component containing m-phenylenediamine is collected from the top of the second light component removal tower 8 at a rate of about 10 g / h, and the crude m-phenylenediamine containing the light component is collected from the bottom of the second light component removal tower 8 at a rate of about 20 g / h and returned to the first light component removal tower 1 for re-distillation.

[0064] S3, the bottom of the first light component removal tower 1, containing m-phenylenediamine, is directly fed into product tower 15 at a rate of approximately 570 g / h. (The product tower is filled with Suzhou Saipu GEH type conjugate ring packing, with a theoretical number of 50 plates.) The pressure at the top of product tower 15 is controlled at 2 kPa, the temperature at the top of the tower is 138°C, the temperature at the bottom of the tower is 198°C, and the reflux ratio is 1:2. The bottom of product tower 15 is collected from the heavy component at a rate of approximately 60 g / h, and the top of product tower 15 is collected from the heavy component at a rate of approximately 530 g / h.

[0065] The preparation method of the crude m-phenylenediamine product is as follows: In a 20L high-pressure reactor, add 1200g of isophthalonitrile, 10300g of a mixed solvent of methanol and toluene (mass ratio, methanol:toluene = 1:2), and 500g of ammonia; add a commercial Raney nickel catalyst (Maclean's). Add 100g of Nickel, cover the autoclave, and test the pressure with high-pressure nitrogen (7.5MPaG). Then, replace the air in the autoclave with low-pressure nitrogen (0.6MPaG) and hydrogen (1.0MPaG) three times each. Carry out the hydrogenation reaction at a temperature of 80℃ and a pressure of 6.5MPa with a stirring speed of 600rpm. The reaction time was 240 min. When the instantaneous hydrogen absorption rate dropped to below 30 sccm, stirring was stopped, the hydrogen inlet valve was closed, and circulating water was used to cool the mixture. Then, the residual gas in the reactor was discharged, and the reaction mother liquor was filtered out using a built-in filter. Methanol, toluene, and ammonia were removed by distillation to obtain 1200 g of crude m-phenylenediamine after hydrogenation and solvent removal of isophthalonitrile. The crude m-phenylenediamine was analyzed by gas chromatography, and its composition was: m-phenylenediamine 90.5 wt%, 3-cyanobenzylamine 0.05 wt%, 3-methylbenzylamine 0.55 wt%, 1,3-cyclohexanedimethylamine 0.40 wt%, and the balance being heavy components (secondary amines).

[0066] Example 3

[0067] A continuous distillation apparatus for crude m-phenylenediamine, as described in Example 1.

[0068] A method for continuous distillation of crude m-phenylenediamine comprises the following steps:

[0069] S1, 1200g of crude m-phenylenediamine is continuously fed into the first light component removal tower 1 at a rate of 600g / h using a metering pump (the first light component removal tower is filled with Suzhou Saipu BRH type Pall ring packing, with a theoretical number of 40 plates). At the same time, PhCOONa is continuously fed into the bottom of the first light component removal tower 1 at a rate of 60mg / h. The pressure at the top of the first light component removal tower 1 is controlled at 5KPa, the temperature at the top of the tower is 140℃, the temperature at the bottom of the tower is 180℃, and the reflux ratio is 1:1. The light component containing m-phenylenediamine is collected from the top of the first light component removal tower 1 at a rate of 30g / h, and the heavy component containing m-phenylenediamine is collected from the bottom of the first light component removal tower 1 at a rate of about 570g / h.

[0070] S2, the light component containing m-phenylenediamine collected from the top of the first light component removal tower 1 is directly fed into the second light component removal tower 8 (the second light component removal tower is filled with Suzhou Saipu BRH type Pall ring packing, with a theoretical plate number of 25) at a rate of about 30 g / h. At the same time, PhCOONa is continuously fed into the bottom of the first light component removal tower 1 at a rate of 6 mg / h. The pressure at the top of the second light component removal tower 8 is controlled at 3 kPa, the top temperature is 120°C, the bottom temperature is 140°C, and the reflux ratio is 1:2. The light component containing m-phenylenediamine is collected from the top of the second light component removal tower 8 at a rate of about 8 g / h, and the crude m-phenylenediamine containing the light component is collected from the bottom of the second light component removal tower 8 at a rate of about 22 g / h and returned to the first light component removal tower 1 for re-distillation.

[0071] S3, the bottom of the first light component removal tower 1, containing m-phenylenediamine, is directly fed into product tower 15 at a rate of approximately 570 g / h. (The product tower is filled with Suzhou Saipu BRH type Pall ring packing, with a theoretical number of 60 plates.) The pressure at the top of product tower 15 is controlled at 2 kPa, the temperature at the top of the tower is 142°C, the temperature at the bottom of the tower is 202°C, and the reflux ratio is 1:3. The bottom of product tower 15 is discharged from the heavy component at a rate of approximately 24 g / h, and the top of product tower 15 is discharged from the heavy component at a rate of approximately 568 g / h.

[0072] The preparation method of the crude m-phenylenediamine product is as follows: In a 20L high-pressure reactor, add 1200g of isophthalonitrile, 10300g of a mixed solvent of methanol and toluene (mass ratio, methanol:toluene = 1:1), and 500g of ammonia; add a commercial Raney nickel catalyst (Maclean's). 100g of -Nickel) was added, the autoclave lid was closed, and the autoclave was pressure tested with high-pressure nitrogen (7.5MPaG). Then, the air inside the autoclave was replaced three times each with low-pressure nitrogen (0.6MPaG) and hydrogen (1.0MPaG). At a temperature of 80℃ and a pressure of 6.5MPa, isophthalonitrile solution was continuously fed into the fixed bed at a feed rate of 1800g / h. The hydrogen flow rate into the fixed bed was 138NL / h to carry out the hydrogenation reaction. During the hydrogenation process, the back pressure valve was used to control the reaction pressure of the fixed bed to be stabilized at 6.5MPa. The feeding time for the hydrogenation reaction is approximately 6.7 hours. After the feeding is completed, the hydrogen inlet valve is closed, and then the residual gas in the fixed bed is discharged. The mother liquor is obtained from the receiving tank and then subjected to distillation to remove methanol, toluene, and ammonia, yielding approximately 1200 g of crude m-phenylenediamine after hydrogenation and solvent removal of isophthalonitrile. The crude product was analyzed by gas chromatography, and its composition was: 95 wt% m-phenylenediamine, 0.05 wt% 3-cyanobenzylamine, 0.55 wt% 3-methylbenzylamine, 0.40 wt% 1,3-cyclohexanedimethylamine, with the balance being heavy components (secondary amines).

[0073] Example 4

[0074] A continuous distillation apparatus for crude m-phenylenediamine, as described in Example 1.

[0075] A method for continuous distillation of crude m-phenylenediamine comprises the following steps:

[0076] S1, 1200g of crude m-phenylenediamine is continuously fed into the first light component removal tower 1 at a rate of 600g / h using a metering pump (the first light component removal tower is filled with Sulzer MellapakPlus 252Y perforated plate corrugated packing, with a theoretical plate number of 30). At the same time, PhCOONa is continuously fed into the bottom of the first light component removal tower 1 at a rate of 60mg / h. The pressure at the top of the first light component removal tower 1 is controlled at 5KPa, the temperature at the top of the tower is 135℃, the temperature at the bottom of the tower is 178℃, and the reflux ratio is 1:3. The light component containing m-phenylenediamine is collected from the top of the first light component removal tower 1 at a rate of 30g / h, and the heavy component containing m-phenylenediamine is collected from the bottom of the first light component removal tower 1 at a rate of approximately 570g / h.

[0077] S2, the light component containing m-phenylenediamine collected from the top of the first light component removal tower 1 is directly fed into the second light component removal tower 8 (the second light component removal tower is filled with Sulzer MellapakPlus 352Y perforated plate corrugated packing, with a theoretical plate number of 28) at a rate of about 30 g / h. At the same time, PhCOONa is continuously fed into the bottom of the first light component removal tower 1 at a rate of 6 mg / h. The pressure at the top of the second light component removal tower 8 is controlled at 3 kPa, the top temperature at 120°C, the bottom temperature at 140°C, and the reflux ratio at 1:2. The light component containing m-phenylenediamine is collected from the top of the second light component removal tower 8 at a rate of about 10 g / h, and the crude m-phenylenediamine containing the light component is collected from the bottom of the second light component removal tower 8 at a rate of about 20 g / h and returned to the first light component removal tower 1 for re-distillation.

[0078] S3, the bottom of the first light component removal tower 1, containing m-phenylenediamine, is directly fed into product tower 15 at a rate of approximately 570 g / h. (The product tower is filled with Sulzer Mellapak Plus 252Y perforated plate corrugated packing, with a theoretical plate number of 55). The pressure at the top of product tower 15 is controlled at 2 kPa, the temperature at the top of the tower is 142°C, the temperature at the bottom of the tower is 202°C, and the reflux ratio is 1:2. The bottom of product tower 15 is collected from the heavy component at a rate of approximately 24 g / h, and the top of product tower 15 is collected from the heavy component at a rate of approximately 566 g / h.

[0079] The preparation method of the crude m-phenylenediamine product is as follows: In a 20L high-pressure reactor, add 1200g of isophthalonitrile, 10300g of a mixed solvent of methanol and toluene (mass ratio, methanol:toluene = 1:1), and 500g of ammonia; add a commercial Raney nickel catalyst (Maclean's). 100g of -Nickel) was added, the autoclave lid was closed, and the autoclave was pressure tested with high-pressure nitrogen (7.5MPaG). Then, the air inside the autoclave was replaced three times each with low-pressure nitrogen (0.6MPaG) and hydrogen (1.0MPaG). At a temperature of 80℃ and a pressure of 6.5MPa, isophthalonitrile solution was continuously fed into the fixed bed at a feed rate of 1800g / h. The hydrogen flow rate into the fixed bed was 138NL / h to carry out the hydrogenation reaction. During the hydrogenation process, the back pressure valve was used to control the reaction pressure of the fixed bed to be stabilized at 6.5MPa. The feeding time for the hydrogenation reaction is approximately 6.7 hours. After the feeding is completed, the hydrogen inlet valve is closed, and then the residual gas in the fixed bed is discharged. The mother liquor is obtained from the receiving tank and then subjected to distillation to remove methanol, toluene, and ammonia, yielding approximately 1200 g of crude m-phenylenediamine after hydrogenation and solvent removal of isophthalonitrile. The crude product was analyzed by gas chromatography, and its composition was: 95 wt% m-phenylenediamine, 0.05 wt% 3-cyanobenzylamine, 0.55 wt% 3-methylbenzylamine, 0.40 wt% 1,3-cyclohexanedimethylamine, with the balance being heavy components (secondary amines).

[0080] Comparative Example 1

[0081] The specific implementation method is the same as in Example 1, except that PhCOONa is not added in steps S1 and S2.

[0082] Comparative Example 2

[0083] The specific implementation method is the same as in Example 1, except that the pressure at the top of the first light-removal tower 1 is 0.05 kPa, the temperature at the top of the tower is 108°C, the temperature at the bottom of the tower is 135°C, and the reflux ratio is 1:2.

[0084] Comparative Example 3

[0085] The specific implementation method is the same as in Example 1, except that the pressure at the top of product tower 15 is 0.08 kPa, the temperature at the top of the tower is 112°C, the temperature at the bottom of the tower is 158°C, and the reflux ratio is 1:1.

[0086] Performance testing and data

[0087] The distilled m-phenylenediamine obtained in the examples and comparative examples was subjected to performance tests, and the test data are listed in Table 1. The m-phenylenediamine was analyzed by gas chromatography using an Agilent GC8890 gas chromatograph with an HP-5 column. The injection port temperature was 250°C, the FID detector temperature was 250°C, the column flow rate was 1.0 mL / min, the hydrogen flow rate was 35 mL / min, and the air flow rate was 350 mL / min. A programmed temperature ramp was used: 80°C for 3 min, ramped to 240°C at 10°C / min, and held at 240°C for 2 min. The content of each substance was determined using the peak area normalization method.

[0088] Table 1

[0089]

Claims

1. A continuous distillation apparatus for crude m-phenylenediamine, characterized in that, include: First light-light removal tower (1), first reboiler (2), first tower bottom circulation pump (3), first tower bottom outlet pump (4), first tower top condenser (5), first tower top reflux tank (6), first tower top reflux outlet pump (7), second light-light removal tower (8), second reboiler (9), second tower bottom circulation pump (10), second tower bottom outlet pump (11), second tower top condenser (12), second tower top reflux tank (13), second tower top reflux outlet pump (14), product tower (15), product tower reboiler (16), product tower bottom circulation pump (17), product tower bottom The product tower has a top condenser (18), a product tower top reflux tank (20), and a product tower top reflux pump (21). The top of the first light-removal tower (1) is connected to the first top condenser (5), the first top reflux pump (7), the second light-removal tower (8), and the second bottom pump (11). The first top condenser (5) is connected to the first top reflux pump (7) via the first top reflux tank (6). The bottom of the first light-removal tower (1) is connected to the first bottom circulation pump (3) and the first bottom pump (4). The first reboiler circulation pump (3) is connected to the first light-removal tower (1) via the first reboiler (2); the first reboiler outlet pump (4) is connected to the product tower (15), and the top of the product tower (15) is connected to the product tower top condenser (19) and the product tower top reflux outlet pump (21), respectively. The product tower top condenser (19) is connected to the product tower top reflux tank (20) and the product tower top reflux outlet pump (21), respectively. The reboiler of the product tower (15) is connected to the product tower reboiler circulation pump (17) and the product tower reboiler outlet pump (18), respectively. The product tower bottom circulation pump (17) is connected to the product tower (15) via the product tower reboiler (16); the top of the second light removal tower (8) is connected to the second tower top condenser (12) and the second tower top reflux pump (14), respectively. The second tower top condenser (12) is connected to the second tower top reflux tank (13) and the second tower top reflux pump (14); the bottom of the second light removal tower (8) is connected to the second tower bottom circulation pump (10) and the second tower bottom pump (11), respectively. The second tower bottom circulation pump (10) is connected to the second light removal tower (8) via the second reboiler (9).

2. A method for continuous distillation of crude m-phenylenediamine using the apparatus according to claim 1, characterized in that, Includes the following steps: S1, feed crude m-phenylenediamine into the first light component removal tower (1), collect the mixture of light component and m-phenylenediamine at the top of the first light component removal tower (1), and collect m-phenylenediamine containing heavy component at the bottom of the first light component removal tower (1). S2, the mixture collected from the top of the first light removal tower (1) is fed into the second light removal tower (8), the light component is collected from the top of the second light removal tower (8), the crude m-phenylenediamine containing the light component is collected from the bottom of the second light removal tower (8), and the crude m-phenylenediamine collected from the bottom of the second light removal tower (8) is returned to the first light removal tower (1) for feeding; S3, the m-phenylenediamine containing heavy components collected from the bottom of the first light removal tower (1) is fed into the product tower (15), the m-phenylenediamine is collected at the top of the product tower (15), and the heavy components are collected at the bottom of the product tower (15).

3. The method for continuous distillation of crude m-phenylenediamine according to claim 2, characterized in that, The first light removal tower (1) and the second light removal tower (8) both contain an alkali, which is selected from at least one of NaOH, KOH, Na3PO4, Na2HPO4, K3PO4, K2HPO4, PhCOONa, PhCOOK, CH3COONa, and CH3COOK.

4. The method for continuous distillation of crude m-phenylenediamine according to claim 3, characterized in that, The amount of alkali added to the bottom of the first light removal tower (1) is 0.01 to 1 wt‰ of the feed amount of m-phenylenediamine.

5. The method for continuous distillation of crude m-phenylenediamine according to claim 2 or 4, characterized in that, The amount of alkali added to the bottom of the second light removal tower (8) is 0.01 to 0.5 wt‰ of the feed amount of m-phenylenediamine.

6. The method for continuous distillation of crude m-phenylenediamine according to claim 5, characterized in that, The crude m-phenylenediamine product comprises, by weight percentage: 75-99% m-phenylenediamine, 0.5-15% light component and 0.5-15% heavy component; the light component includes at least one of 3-cyanobenzylamine, 3-methylbenzylamine and 1,3-cyclohexanedimethylamine.

7. The method for continuous distillation of crude m-phenylenediamine according to claim 2 or 6, characterized in that, The first light removal tower (1), the second light removal tower (8), and the product tower (15) all include packing materials, which include at least one of the following: self-corrugated packing, grid packing, wire mesh packing, Pall rings, conjugate rings, cross rings, and θ mesh rings.

8. The method for continuous distillation of crude m-phenylenediamine according to claim 7, characterized in that, The parameters of the first light removal tower (1) include: 25 to 150 trays, reflux ratio of 1:(0.1-10), top temperature of 90 to 180°C, bottom temperature of 120 to 250°C, and top pressure of 0.1 to 12 kPa.

9. The method for continuous distillation of crude m-phenylenediamine according to claim 8, characterized in that, The parameters of the second light removal tower (8) include: 15 to 120 trays, reflux ratio of 1:(0.125-8), top temperature of 80 to 180°C, bottom temperature of 100 to 220°C, and top pressure of 0.1 to 12 kPa.

10. The method for continuous distillation of crude m-phenylenediamine according to claim 9, characterized in that, The parameters of the product tower (15) include: 40 to 180 trays, reflux ratio of 1:(0.2-10), top temperature of 90 to 200°C, bottom temperature of 120 to 260°C, and top pressure of 0.1 to 10 kPa.

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