A method for continuous separation of mixed diamines and heavy components

Abstract

The present invention relates to the technical field of mixture separation, and particularly to a continuous separation method for mixed diamines and heavy components, comprising: S1, dehydrating by distillation in a dehydration tower; S2, removing heavy components in a heavy component removal tower; S3, scraping film to remove coke; S4, separating m-phenylenediamine in a meta-position tower and separating o-phenylenediamine in an ortho-position tower. The system of the present invention adopts a continuous operation mode, and each tower works in coordination, improving the utilization rate of equipment, solving problems such as foam, blockage and high separation difficulty existing in the traditional separation process, improving the purity and yield of products, reducing production costs, and having certain economic benefits.

Description

Technical Field

[0001] The present invention relates to the technical field of mixture separation, and particularly to a continuous separation method for mixed diamine and heavy components. Background Art

[0002] Industrially, the preparation of phenylenediamine mainly relies on the hydrogenation reduction reaction of dinitrobenzene. This process is usually carried out under the action of a catalyst, using hydrogen as a reducing agent to effectively convert dinitrobenzene into phenylenediamine. This preparation process has the advantages of relatively low production cost, easy availability of raw materials, mild reaction conditions, and relatively simple operation process. However, while producing the target product phenylenediamine, a series of by-products will also be generated, including impurities such as water, nitrobenzene, methanol, and tar.

[0003] In the prior art, the heavy components in the mixed diamine are mainly tar, accounting for about 0.5 - 1% of the total material. In traditional separation processes such as distillation, extraction, and crystallization, the mixture of tar and phenylenediamine forms foam due to the interaction between components. The presence of foam affects the separation efficiency, leading to equipment blockage and unstable operation. In addition, the high viscosity and polarity of tar make it easy to adhere to the surface of the equipment or form a stable emulsion with other components during the separation process, thus increasing the difficulty of separation. Summary of the Invention

[0004] In order to solve the problems mentioned in the above background art, the present invention provides a continuous separation method for mixed diamine and heavy components.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A continuous separation method for mixed diamine and heavy components, comprising:

[0007] S1. Feed the mixed material into a dehydration tower, control the feed rate. The initial feed rate is 2 - 3 m 3 / h. After 1 - 2 h, adjust the feed rate to 5 - 5.5 m 3 / h. When the liquid level in the bottom of the dehydration tower reaches 20% and continues to rise, start the bottom reflux to control the bottom circulation rate. The bottom circulation rate is 70 - 80 m 3 / h. Feed 1.8 - 1.9 MPa hot steam into the bottom of the tower to heat up to the temperature in the bottom of the tower being 185 - 186 °C and the temperature at the top of the tower being 36 - 37 °C. Control the temperature rise rate in the bottom of the tower ≤ 50 °C / h. Extract the water vapor at the top of the tower, and after condensation, perform wastewater treatment. Obtain dehydrated mixed diamine in the bottom of the tower, with the water content ≤ 0.1%;

[0008] S2. The dehydrated mixed diamine is introduced into the heavy component removal tower. A separation aid is loaded into the heavy component removal tower, and the temperature of the heavy component removal tower is preheated to ≥80 °C 24 hours in advance. The vacuum degree of the heavy component removal tower is controlled at -0.098 to (-0.097) MPa, and the initial feed rate is 1 - 1.5 m 3 / h. After 1 - 2 hours, the feed rate is adjusted to 3 - 3.5 m 3 / h. When the liquid level in the bottom of the heavy component removal tower reaches 20% and continues to rise, the bottom reflux is started to control the bottom circulation volume, and the bottom circulation volume is 38 - 50 m 3 / h. 1.8 - 1.9 MPa hot steam is introduced into the bottom of the tower to heat up to the temperature in the bottom of the tower being 178 - 180 °C and the top temperature being 165 - 166 °C. The liquid level in the bottom of the heavy component removal tower is controlled at 50 - 60%. The mixed diamine vapor at the top of the tower is taken out, introduced into the heavy component removal tail cooler to be melted at 110 - 120 °C, and then naturally cooled to 60 - 65 °C to obtain the mixed diamine, and the high-boiling substances are obtained in the bottom of the tower;

[0009] S3. The high-boiling substances are introduced into the wiped film evaporator. The initial feed rate is 0.1 - 0.15 m 3 / h. After 30 - 60 minutes, the feed rate is adjusted to 0.2 - 0.25 m 3 / h. 1.8 - 1.9 MPa hot steam is introduced into the bottom of the tower to heat up to the temperature in the bottom of the tower being 166 - 170 °C. The vapor at the top of the tower is taken out, condensed to 60 - 65 °C and introduced into the meta-position kettle. After the materials in the bottom of the tower are filtered by suction, the solid phase is the separation aid, and the liquid phase is the tar. The separation aid can be re-loaded into the heavy component removal tower after being washed and dried. The tar is introduced into the tar tank, and 0.8 - 0.9 MPa steam is introduced into the tar tank for heating or heat preservation;

[0010] S4. The mixed diamine is introduced into the meta-position tower. The vacuum degree of the meta-position tower is controlled at -0.098 to (-0.095) MPa. When the liquid level in the bottom of the meta-position tower reaches 20% and continues to rise, the bottom reflux is started to control the bottom circulation volume, and the bottom circulation volume is 100 - 110 m 3 / h. 1.8 - 1.9 MPa hot steam is introduced into the bottom of the tower to heat up to the top temperature being 120 - 125 °C. The m-phenylenediamine vapor at the top of the tower is taken out, condensed to 60 - 65 °C and then collected into the m-phenylenediamine storage tank. The materials in the bottom of the tower are introduced into the ortho-position tower. The vacuum degree of the ortho-position tower is controlled at -0.097 to (-0.094) MPa. When the liquid level in the bottom of the meta-position tower reaches 20% and continues to rise, the bottom reflux is started to control the bottom circulation volume, and the bottom circulation volume is 10 - 15 m 3 / h, introduce 1.8 - 1.9 MPa of hot steam into the bottom of the tower to heat up to a top tower temperature of 140 - 145 °C, extract the o-phenylenediamine vapor at the top of the tower, continue to heat up to a bottom tower temperature of 180 - 182 °C, and a top tower temperature of 163 - 165 °C. After the o-phenylenediamine vapor is condensed to 60 - 65 °C, it is collected into the o-phenylenediamine storage tank. After the production is completed, the material in the bottom of the tower is p-phenylenediamine, which is sliced and stored.

[0011] Further, the separation aid in step S2 is prepared by the following steps:

[0012] Polyethylene glycol dimethacrylate, absolute ethanol, and vinyltrimethoxysilane are sequentially introduced into the reaction kettle, heated to 45 - 50 °C, stirred at a speed of 50 - 100 rpm for 30 - 60 min, add the catalyst p-toluenesulfonic acid, heat up to 65 - 75 °C, and stir and react at a speed of 100 - 200 rpm for 12 - 24 h. After the reaction is completed, cool to room temperature, add a 5 - 10% w / v sodium bicarbonate solution to neutralize the catalyst, continue to stir at a speed of 50 - 100 rpm for 30 - 60 min, transfer the product to a rotary evaporator, carry out vacuum distillation at 40 - 50 °C, and then place it in a vacuum oven to dry to constant weight to obtain the separation aid.

[0013] Further, the mass ratio of polyethylene glycol dimethacrylate, absolute ethanol, vinyltrimethoxysilane, and p-toluenesulfonic acid is (2 - 2.2):(5 - 6):(0.8 - 0.9):(0.02 - 0.04).

[0014] Compared with the prior art, the beneficial effects of the present invention are:

[0015] 1. During the preparation process, polyethylene glycol dimethacrylate and vinyltrimethoxysilane undergo a condensation reaction to form relatively long molecular chains containing ether bonds, ester bonds, siloxane bonds, etc., which further constitute a three-dimensional crosslinked network, endowing it with certain flexibility and rigidity, increasing the molecular weight of the separation aid, and significantly enhancing its mechanical strength and chemical stability. At the same time, the presence of hydrophilic and hydrophobic groups in the separation aid enables it to form a stable dispersion system in the liquid and effectively reduce the surface tension of the liquid. The separation aid can act as a hydrogen bond acceptor and donor, interacting with the hydrogen bonds in the mixed diamine or heavy components, which helps the separation aid adsorb and coat the heavy components more efficiently in the deweighting tower. In addition, the long molecular chain and crosslinked network structure of the separation aid endow it with a large surface area and volume, thereby enhancing the van der Waals force interaction with the mixed diamine and heavy components, further stabilizing the adsorption and coating process. The crosslinked network structure of the separation aid may also produce a steric hindrance effect, hindering the diffusion of heavy components in the deweighting tower, thus prolonging their residence time in the tower, improving the separation efficiency and selectivity, enabling the separation aid to significantly improve the separation efficiency between the mixed diamine and heavy components, enhancing the stability of the system at the same time, and optimizing the mass transfer and heat transfer processes in the deweighting tower.

[0016] 2. This system adopts a continuous operation mode, and each tower works in coordination, improving the utilization rate of equipment, effectively solving problems such as foam, blockage, and high separation difficulty existing in traditional separation processes, improving the purity and yield of products, reducing production costs, and having certain economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or in the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the 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 drawings can also be obtained based on these drawings.

[0018] Figure 1 It is a flow block diagram of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0019] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0020] Unless otherwise specified, the raw materials used in the present invention are all conventional products purchased from the market.

[0021] Preparation Example 1

[0022] The separation aid is prepared by the following steps:

[0023] 2 kg of polyethylene glycol dimethacrylate, 5 kg of absolute ethanol, and 0.8 kg of vinyltrimethoxysilane were successively introduced into a reaction kettle, heated to 45 °C, stirred at a speed of 50 rpm for 30 min, 0.02 kg of p-toluenesulfonic acid was added, the temperature was raised to 65 °C, and the mixture was stirred and reacted at a speed of 100 rpm for 12 h. After the reaction was completed, it was cooled to room temperature, 5% w / v sodium bicarbonate solution was added, and stirring was continued at a speed of 50 rpm for 30 min. The product was transferred to a rotary evaporator, and distilled under reduced pressure at 40 °C, and then dried to a constant weight in a vacuum oven to obtain the separation aid.

[0024] Preparation Example 2

[0025] The separation aid is prepared by the following steps:

[0026] 2.16 kg of polyethylene glycol dimethacrylate, 5.6 kg of absolute ethanol, and 0.83 kg of vinyltrimethoxysilane were successively introduced into a reaction kettle, heated to 48 °C, stirred at a speed of 60 rpm for 40 min, 0.03 kg of p-toluenesulfonic acid was added, the temperature was raised to 70 °C, and the mixture was stirred and reacted at a speed of 150 rpm for 18 h. After the reaction was completed, it was cooled to room temperature, 8% w / v sodium bicarbonate solution was added, and stirring was continued at a speed of 60 rpm for 40 min. The product was transferred to a rotary evaporator, and distilled under reduced pressure at 45 °C, and then dried to a constant weight in a vacuum oven to obtain the separation aid.

[0027] Preparation Example 3

[0028] The separation aid is prepared by the following steps:

[0029] 2.2 kg of polyethylene glycol dimethacrylate, 6 kg of absolute ethanol, and 0.9 kg of vinyltrimethoxysilane were successively introduced into a reaction kettle, heated to 50 °C, stirred at a speed of 100 rpm for 60 min, 0.04 kg of p-toluenesulfonic acid was added, the temperature was raised to 75 °C, and the mixture was stirred and reacted at a speed of 200 rpm for 24 h. After the reaction was completed, it was cooled to room temperature, 10% w / v sodium bicarbonate solution was added, and stirring was continued at a speed of 100 rpm for 60 min. The product was transferred to a rotary evaporator, and distilled under reduced pressure at 50 °C, and then dried to a constant weight in a vacuum oven to obtain the separation aid.

[0030] Example 1

[0031] A continuous separation method for mixed diamine and heavy components, comprising:

[0032] S1. The mixed material is introduced into a dehydration tower, the feeding amount is controlled, and the initial feeding amount is 2 m3 / h. After 1 h, adjust the feed rate to 5 m 3 / h. When the liquid level in the bottom of the dehydration tower reaches 20% and continues to rise, start the bottom reflux to control the bottom circulation rate, and the bottom circulation rate is 70 m 3 / h. Introduce 1.8 MPa hot steam into the bottom of the tower to heat up to the temperature in the bottom of the tower being 185 °C and the top temperature being 36 °C. Control the temperature rise rate in the bottom of the tower to be 50 °C / h. Extract the water vapor at the top of the tower, and after condensation, treat it as wastewater. Obtain dehydrated mixed diamine in the bottom of the tower;

[0033] S2. Feed the dehydrated mixed diamine into the heavy component removal tower. Load 1 wt% of the separation aid prepared in Preparation Example 1 into the heavy component removal tower, and preheat the temperature of the heavy component removal tower to 80 °C 24 h in advance. Control the vacuum degree of the heavy component removal tower to be -0.098 MPa, and the initial feed rate is 1 m 3 / h. After 1 h, adjust the feed rate to 3 m 3 / h. When the liquid level in the bottom of the heavy component removal tower reaches 20% and continues to rise, start the bottom reflux to control the bottom circulation rate, and the bottom circulation rate is 38 m 3 / h. Introduce 1.8 MPa hot steam into the bottom of the tower to heat up to the temperature in the bottom of the tower being 178 °C and the top temperature being 165 °C. Control the liquid level in the bottom of the heavy component removal tower to be 50%. Extract the mixed diamine vapor at the top of the tower, introduce it into the heavy component removal tail cooler to melt the material at 110 °C, and then naturally cool it to 60 °C to obtain mixed diamine, and obtain high-boiling substances in the bottom of the tower;

[0034] S3. Feed the high-boiling substances into the wiped film evaporator, and the initial feed rate is 0.1 m 3 / h. After 30 min, adjust the feed rate to 0.2 m 3 / h. Introduce 1.8 MPa hot steam into the bottom of the tower to heat up to the temperature in the bottom of the tower being 166 °C. Extract the vapor at the top of the tower, condense it to 60 °C and introduce it into the meta-position kettle. The material in the bottom of the tower is introduced into the coke tar tank, and 0.8 MPa steam is introduced into the coke tar tank for heat preservation;

[0035] S4. Feed the mixed diamine into the meta-position tower. Control the vacuum degree of the meta-position tower to be -0.098 MPa. When the liquid level in the bottom of the meta-position tower reaches 20% and continues to rise, start the bottom reflux to control the bottom circulation rate, and the bottom circulation rate is 100 m 3 / h. Introduce 1.8 MPa hot steam into the bottom of the tower to heat up to the top temperature being 120 °C. Extract the m-phenylenediamine vapor at the top of the tower, condense it to 60 °C and collect it into the m-phenylenediamine storage tank. The material in the bottom of the tower is introduced into the ortho-position tower. Control the vacuum degree of the ortho-position tower to be -0.097 MPa. When the liquid level in the bottom of the meta-position tower reaches 20% and continues to rise, start the bottom reflux to control the bottom circulation rate, and the bottom circulation rate is 10 m 3At a rate of 1.8 MPa of hot steam is introduced into the bottom of the column to raise the temperature to 140 °C at the top of the column, and the vapor of o-phenylenediamine at the top of the column is withdrawn. Then, the temperature is further raised to 180 °C at the bottom of the column and 163 °C at the top of the column. After the vapor of o-phenylenediamine is condensed to 60 °C, it is collected in the o-phenylenediamine storage tank. After the production is completed, the material in the bottom of the column is p-phenylenediamine, which is sliced and stored.

[0036] Example 2

[0037] A continuous separation method for mixed diamines and heavy components, comprising:

[0038] S1. The mixed material is introduced into a dehydration column, and the feed rate is controlled. The initial feed rate is 2.6 m 3 / h. After 1.5 h, the feed rate is adjusted to 5.1 m 3 / h. When the liquid level in the bottom of the dehydration column reaches 20% and continues to rise, the bottom reflux is started to control the bottom circulation rate, and the bottom circulation rate is 73 m 3 / h. 1.86 MPa of hot steam is introduced into the bottom of the column to raise the temperature in the bottom of the column to 185.5 °C and the temperature at the top of the column to 36.5 °C. The temperature rise rate in the bottom of the column is controlled at 40 °C / h, and the water vapor at the top of the column is withdrawn and treated as wastewater after condensation. The dehydrated mixed diamines are obtained in the bottom of the column;

[0039] S2. The dehydrated mixed diamines are introduced into a heavy component removal column. 1 wt% of the separation aid prepared in Preparation Example 2 is loaded into the heavy component removal column, and the temperature of the heavy component removal column is preheated to 85 °C 24 h in advance. The vacuum degree of the heavy component removal column is controlled at 0.0975 MPa, and the initial feed rate is 1.3 m 3 / h. After 1.5 h, the feed rate is adjusted to 3.3 m 3 / h. When the liquid level in the bottom of the heavy component removal column reaches 20% and continues to rise, the bottom reflux is started to control the bottom circulation rate, and the bottom circulation rate is 41 m 3 / h. 1.85 MPa of hot steam is introduced into the bottom of the column to raise the temperature in the bottom of the column to 179 °C and the temperature at the top of the column to 165.5 °C. The liquid level in the bottom of the heavy component removal column is controlled at 55%, and the vapor of the mixed diamines at the top of the column is withdrawn and introduced into the heavy component removal tail cooler to be melted at 115 °C and then naturally cooled to 63 °C to obtain the mixed diamines, and the heavy-boiling components are obtained in the bottom of the column;

[0040] S3. The heavy-boiling components are introduced into a wiped film evaporator. The initial feed rate is 0.12 m 3 / h. After 45 min, the feed rate is adjusted to 0.23 m 3 / h. 1.89 MPa of hot steam is introduced into the bottom of the column to raise the temperature in the bottom of the column to 168 °C, and the vapor at the top of the column is withdrawn and condensed to 64 °C and then introduced into the meta-position kettle. The material in the bottom of the column is introduced into the coke oil tank, and 0.86 MPa of steam is introduced into the coke oil tank for heat preservation;

[0041] S4. The mixed diamine is introduced into the meta-tower, and the vacuum degree of the meta-tower is controlled at -0.096 MPa. When the liquid level in the bottom of the meta-tower reaches 20% and continues to rise, the bottom reflux is started to control the bottom circulation rate, and the bottom circulation rate is 105 m 3 / h. 1.85 MPa hot steam is introduced into the bottom to heat up to the top temperature of 123 °C. The meta-phenylenediamine vapor at the top is withdrawn, condensed to 63 °C and then collected in the meta-phenylenediamine storage tank. The material in the bottom of the tower is introduced into the ortho-tower, and the vacuum degree of the ortho-tower is controlled at -0.095 MPa. When the liquid level in the bottom of the meta-tower reaches 20% and continues to rise, the bottom reflux is started to control the bottom circulation rate, and the bottom circulation rate is 13 m 3 / h. 1.85 MPa hot steam is introduced into the bottom to heat up to the top temperature of 142 °C. The ortho-phenylenediamine vapor at the top is withdrawn, and the temperature is further raised to the bottom temperature of 181 °C and the top temperature of 164 °C. The ortho-phenylenediamine vapor is condensed to 63 °C and then collected in the ortho-phenylenediamine storage tank. After the production is completed, the material in the bottom of the tower is p-phenylenediamine, which is sliced and stored.

[0042] Example 3

[0043] A continuous separation method for mixed diamine and heavy components, comprising:

[0044] S1. The mixed material is introduced into the dehydration tower, and the feed rate is controlled. The initial feed rate is 3 m 3 / h. After 1.5 h, the feed rate is adjusted to 5.5 m 3 / h. When the liquid level in the bottom of the dehydration tower reaches 20% and continues to rise, the bottom reflux is started to control the bottom circulation rate, and the bottom circulation rate is 80 m 3 / h. 1.9 MPa hot steam is introduced into the bottom to heat up to the bottom temperature of 186 °C and the top temperature of 37 °C. The temperature rise rate of the bottom is controlled at 40 °C / h. The water vapor at the top is withdrawn, condensed and treated as waste water. The dehydrated mixed diamine is obtained in the bottom of the tower;

[0045] S2. The dehydrated mixed diamine is introduced into the heavy component removal tower. 1 wt% of the separation aid prepared in Preparation Example 3 is loaded into the heavy component removal tower, and the temperature of the heavy component removal tower is preheated to 90 °C 24 h in advance. The vacuum degree of the heavy component removal tower is controlled at -0.097 MPa, and the initial feed rate is 1.5 m 3 / h. After 2 h, the feed rate is adjusted to 3.5 m 3 / h. When the liquid level in the bottom of the heavy component removal tower reaches 20% and continues to rise, the bottom reflux is started to control the bottom circulation rate, and the bottom circulation rate is 50 m 3 / h. 1.9 MPa hot steam is introduced into the bottom to heat up to the bottom temperature of 180 °C and the top temperature of 166 °C. The liquid level in the bottom of the heavy component removal tower is controlled at 60%. The mixed diamine vapor at the top is withdrawn, introduced into the heavy component removal tail cooler to melt at 120 °C, and then naturally cooled to 65 °C to obtain the mixed diamine. The heavy-boiling substances are obtained in the bottom of the tower;

[0046] S3. The high-boiling substances are fed into a wiped-film evaporator. The initial feeding rate is 0.15 m 3 / h. After 60 minutes, the feeding rate is adjusted to 0.25 m 3 / h. 1.9 MPa hot steam is fed into the bottom of the column to raise the temperature in the bottom of the column to 170 °C. The top vapor is withdrawn, condensed to 65 °C and then fed into the meta-position kettle. The material in the bottom of the column is fed into the tar kettle, and 0.9 MPa steam is fed into the tar kettle for heating or heat preservation;

[0047] S4. The mixed diamines are fed into the meta-position column. The vacuum degree of the meta-position column is controlled at -0.095 MPa. When the liquid level in the bottom of the meta-position column reaches 20% and continues to rise, the bottom reflux is started to control the bottom circulation rate. The bottom circulation rate is 110 m 3 / h. 1.9 MPa hot steam is fed into the bottom of the column to raise the temperature at the top of the column to 125 °C. The meta-phenylenediamine vapor at the top of the column is withdrawn, condensed to 65 °C and then collected into the meta-phenylenediamine storage tank. The material in the bottom of the column is fed into the ortho-position column. The vacuum degree of the ortho-position column is controlled at -0.094 MPa. When the liquid level in the bottom of the meta-position column reaches 20% and continues to rise, the bottom reflux is started to control the bottom circulation rate. The bottom circulation rate is 15 m 3 / h. 1.9 MPa hot steam is fed into the bottom of the column to raise the temperature at the top of the column to 145 °C. The ortho-phenylenediamine vapor at the top of the column is withdrawn, and the temperature is further raised to 182 °C at the bottom of the column and 165 °C at the top of the column. The ortho-phenylenediamine vapor is condensed to 65 °C and then collected into the ortho-phenylenediamine storage tank. After the production is completed, the material in the bottom of the column is p-phenylenediamine, which is sliced and then stored.

[0048] Comparative Example 1

[0049] The difference between this comparative example and Example 1 is that polyethylene glycol dimethacrylate is used as the separation aid, and the other steps are the same as those in Example 1.

[0050] Comparative Example 2

[0051] The difference between this comparative example and Example 2 is that vinyltrimethoxysilane is used as the separation aid, and the other steps are the same as those in Example 2.

[0052] Comparative Example 3

[0053] The difference between this comparative example and Example 3 is that activated carbon is used as the separation aid, and the other steps are the same as those in Example 3.

[0054] The feeding and discharging conditions of each bottom of the columns in Examples 1-3 and Comparative Examples 1-3 are shown in Table 1:

[0055] Table 1. Feeding and discharging conditions of Examples 1-3 and Comparative Examples 1-3 (unit: kg / h)

[0056]

[0057] As can be seen from Table 1, the feeding amounts of the mixed diamines in Examples 1-3 are relatively close, and the feeding amounts of the separation aids are also kept consistent (1 wt% based on the mixed diamines). The discharge amounts of water, nitrobenzene, m-phenylenediamine, o-phenylenediamine, and p-phenylenediamine have small differences among the examples, and the discharge amounts of impurities also have small differences among the examples and are low, indicating that the separation aids prepared in the preparation examples can effectively separate heavy components such as tar and phenylenediamine.

[0058] In Comparative Example 1, polyethylene glycol dimethacrylate was used as the separation aid, while in Comparative Example 2, vinyltrimethoxysilane was used, and in Comparative Example 3, activated carbon was used. In Comparative Examples 1-3, the discharge amounts of m-xylene, o-xylene, and p-xylene are significantly lower than those in the examples, while the discharge amounts of impurities are significantly higher than those in the examples. The impurities contain a mixed component of tar and phenylenediamine, indicating that using different separation aids has a significant impact on the separation effect. Especially in Comparative Example 3, the discharge amount of its impurities is the highest, indicating that activated carbon may not have a good effect in this separation system.

[0059] The chemical structure and properties of the separation aid may affect its interaction with the mixed diamine and the heavy components, thereby affecting the separation effect. The separation aids prepared in the preparation examples may be able to interact more effectively with the mixed diamine and the heavy components, thereby achieving better separation.

[0060] In summary, the separation aids prepared in Preparation Examples 1-3 show a significant separation effect in the separation of the mixed diamine and the heavy components, improving the separation efficiency and product quality of Examples 1-3.

[0061] In the description of the specification, the descriptions referring to terms such as "preparation example", "example", "each example", etc. mean that the specific features, structures, materials, or characteristics described in connection with that example or preparation example are included in at least one example or preparation example of the present invention. In this specification, the schematic descriptions of the above terms do not necessarily refer to the same example or preparation example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more examples or preparation examples.

[0062] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution of the present invention and its inventive concept, makes equivalent substitutions or changes, and all should be covered by the protection scope of the present invention.

Claims

1. A method for continuous separation of mixed diamines and heavy components, characterized in that: include: S1, passing the mixed material into a dehydration tower, controlling the feed amount and the tower bottom circulation amount, passing hot steam to increase the temperature, extracting and treating the water vapor at the top of the tower, and obtaining a dehydrated mixed diamine with a water content of ≤0.1% in the tower bottom; S2, the dehydrated mixed diamine is passed into a deweighting tower which is pre-loaded with a separation aid and preheated, the vacuum degree, feed amount and tower bottom circulation amount are controlled, hot steam is passed in to increase the temperature, the mixed diamine vapor at the top of the tower is extracted and processed, and high boiling products are obtained in the tower bottom; S3, high boiling materials are passed into the scraped film evaporator, the feed amount is controlled, hot steam is passed into the evaporator to increase the temperature, the vapor from the top of the tower is extracted and processed, and the materials in the bottom of the tower are passed into the tar tank; S4, the mixed diamine is passed into the meta-tower, the vacuum degree and the tower bottom circulation volume are controlled, hot steam is passed in to increase the temperature, the meta-phenylenediamine vapor at the top of the tower is extracted and processed, the material in the tower bottom is passed into the ortho-tower, the vacuum degree and the tower bottom circulation volume of the ortho-tower are controlled, hot steam is passed in to increase the temperature, the ortho-phenylenediamine vapor at the top of the tower is extracted and processed, and the temperature is continued to be increased. After the production is completed, the material in the tower bottom is p-phenylenediamine, which is sliced ​​and stored; The separation aid in step S2 comprises the following steps: Polyethylene glycol dimethacrylate, anhydrous ethanol and vinyl trimethoxysilane are sequentially introduced into a reaction kettle, heated to 45-50°C, stirred for the first time, and then p-toluenesulfonic acid is added, and the temperature is raised to 65-75°C, stirred for the second time. After the reaction is completed, the reaction is cooled to room temperature, and a 5-10% w / v sodium bicarbonate solution is added. The reaction is stirred for the third time, and the product is transferred to a rotary evaporator, distilled under reduced pressure at 40-50°C, and then dried in a vacuum oven to constant weight to obtain a separation aid; The mass ratio of polyethylene glycol dimethacrylate, anhydrous ethanol, vinyltrimethoxysilane and p-toluenesulfonic acid is (2-2.2):(5-6):(0.8-0.9):(0.02-0.04).

2. The method for continuous separation of mixed diamines and heavy components according to claim 1, characterized in that: The initial feed amount in step S1 is 2-3m 3 / h, after 1-2h, adjust the feed rate to 5-5.5m 3 / h, the tower bottom circulation volume is 70-80m 3 / h.

3. The method for continuous separation of mixed diamines and heavy components according to claim 1, characterized in that: In step S1, 1.8-1.9 MPa hot steam is introduced to raise the temperature in the tower kettle to 185-186°C, the tower top temperature to 36-37°C, and the tower kettle temperature rise range is ≤50°C / h.

4. The method for continuous separation of mixed diamines and heavy components according to claim 1, characterized in that: The first stirring is carried out at a speed of 50-100 rpm for 30-60 min; The second stirring is carried out at a speed of 100-200 rpm for 12-24 hours; The third stirring is carried out at a speed of 50-100 rpm for 30-60 min.

5. The method for continuous separation of mixed diamines and heavy components according to claim 1, characterized in that: In step S2, the preheating temperature of the deweighting tower is ≥80°C, the vacuum degree is -0.098~(-0.097)MPa, and the initial feed amount is 1-1.5m 3 / h, after 1-2h, adjust the feed rate to 3-3.5m 3 / h, the tower bottom circulation volume is 38-50m 3 / h.

6. The method for continuous separation of mixed diamines and heavy components according to claim 1, characterized in that: In step S2, 1.8-1.9 MPa hot steam is introduced into the kettle to raise the temperature of the kettle to 178-180° C., the temperature of the tower top is 165-166° C., and the liquid level in the kettle of the degravity tower is controlled to be 50-60%.

7. The method for continuous separation of mixed diamines and heavy components according to claim 1, characterized in that: The initial feed amount in step S3 is 0.1-0.15m 3 / h, after 30-60min, adjust the feed rate to 0.2-0.25m 3 / h, and introduce 1.8-1.9MPa hot steam to raise the temperature in the tower kettle to 166-170℃.

8. The method for continuous separation of mixed diamines and heavy components according to claim 1, characterized in that: The vacuum degree of the intermediate tower in step S4 is -0.098~(-0.095)MPa, and the circulation volume of the tower bottom is 100-110m 3 / h, and introduce 1.8-1.9MPa hot steam to raise the tower top temperature to 120-125℃.

9. The method for continuous separation of mixed diamines and heavy components according to claim 1, characterized in that: In step S4, the vacuum degree of the ortho tower is -0.097~(-0.094)MPa, and the circulation volume of the tower bottom is 10-15m 3 / h, introduce 1.8-1.9MPa hot steam to raise the temperature to 140-145℃ at the top of the tower, and continue to raise the temperature to 180-182℃ at the bottom of the tower. The temperature at the top of the tower is 163-165℃.

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