A method for separating and purifying 1,2-cyclohexanediamine from a product synthesized from hexamethylenediamine by hydrogenation of adiponitrile

Abstract

The invention provides a method for separating and purifying 1,2-cyclohexanediamine from a product synthesized from hexamethylenediamine by hydrogenating adiponitrile. The method comprises the steps of firstly rectifying the product synthesized from hexamethylenediamine by hydrogenating adiponitrile in a lightness removal tower, collecting the obtained bottom liquid, sending it to a refining tower for further rectification, and extracting 1,2-cyclohexanediamine from the top of the refining tower. The method successfully separates and purifies 1,2-cyclohexanediamine from a product synthesized from adiponitrile with complex components and similar physical properties by limiting the theoretical plate number, tower top operating pressure, and tower bottom operating temperature of the lightness removal tower and the theoretical plate number, tower top operating pressure, and tower top operating temperature of the refining tower, thereby effectively improving the product quality and production efficiency of 1,2-cyclohexanediamine.

Description

Technical Field

[0001] The invention belongs to the field of separation and purification, and particularly relates to a method for separating and purifying 1,2-cyclohexanediamine from a product synthesized from hexamethylenediamine by hydrogenation of adiponitrile. Background Art

[0002] 1,2-Cyclohexanediamine is an important chemical raw material with a wide range of applications. For example, it is used as a chelating agent in the textile industry and water treatment, as a high-grade epoxy curing agent in the coatings industry, and as a key raw material for the third-generation platinum anticancer drug oxaliplatin in the pharmaceutical field. 1,2-Cyclohexanediamine can be obtained by synthesizing it using 2-aminocyclohexanol, 1,2-cyclohexanediol, or epoxycyclohexane. However, 1,2-Cyclohexanediamine is primarily derived from the hydrogenation of adiponitrile to produce hexanediamine.

[0003] Currently, the number of production facilities for hydrogenating adiponitrile to hexamethylenediamine is increasing, and their scale is also increasing. Consequently, the output of 1,2-cyclohexanediamine is also increasing. Although 1,2-cyclohexanediamine is a light component at the top of the first light removal column in the adiponitrile to hexamethylenediamine process, and its content is relatively high, the composition of the light components at the top of the first light removal column is still relatively complex, and the direct industrial utilization value of the mixture containing polyamines is relatively low. However, high-purity 1,2-cyclohexanediamine and hexamethylenediamine are both important chemical raw materials. Rational development of this product, in which the main components are recovered and purified to high-purity products, can greatly improve its economic and social benefits.

[0004] CN113248389A discloses a production system of 1,2-cyclohexanediamine, including a solid-liquid separation device, a dehydration tower, a decoking tower, and a refining tower. The material inlet of the solid-liquid separation device is used to be connected to a mixed material source discharged from a reactor after gas-liquid separation, catalyst filtration, and dealcoholization. The solid-liquid separation device supplies the dehydration tower through an overflow pipe. The bottom discharge port of the dehydration tower supplies the decoking tower through a first pipeline. The top discharge port of the decoking tower supplies the refining tower through a second pipeline. The top discharge port of the refining tower is connected to the condenser. The invention relates to a device which is connected to a reflux line, on which a reflux tank, a discharge pump and a first valve are sequentially arranged. The downstream end of the reflux line is connected to the reflux port of the refining tower. A discharge pipe is connected to the reflux line and is located between the discharge pump and the first valve. A second valve is arranged on the discharge pipe. The 1,2-cyclohexanediamine product is extracted from the top of the refining tower. However, the invention does not obtain high-purity 1,2-cyclohexanediamine, and there is currently little research on separating and purifying 1,2-cyclohexanediamine from the products produced in the production process of hexanediamine.

[0005] In the research literature on DCH separation technology, Shen Xiaojie only focused on the separation of the top material of the first light removal tower of the hexamethylenediamine production unit. The composition of the top material was 54% 1,2-cyclohexanediamine (DCH), 34% 1,6-hexamethylenediamine (HMD), 6% o-methylaminocyclopentylamine (AMCPA) and 6% H2O. The conclusion was that the mixture could be separated by column chromatography, but there were also some problems. Ordinary distillation methods could not effectively separate DCH.

[0006] Therefore, developing a method for separating and purifying 1,2-cyclohexanediamine from the product of hydrogenating adiponitrile to synthesize hexamethylenediamine is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0007] In view of the deficiencies in the prior art, the present invention aims to provide a method for separating and purifying 1,2-cyclohexanediamine from a product of hexamethylenediamine synthesized by hydrogenating adiponitrile. The method employs a lightness removal tower and a refining tower in combination, and limits the theoretical plate number, operating pressure, and operating temperature of the two towers. A distillation tower with a high theoretical plate number is operated under high vacuum conditions, thereby successfully achieving the separation and purification of 1,2-cyclohexanediamine, continuously and stably obtaining a 1,2-cyclohexanediamine product with high purity, and effectively improving the product quality and production efficiency of 1,2-cyclohexanediamine.

[0008] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0009] In a first aspect, the present invention provides a method for separating and purifying 1,2-cyclohexanediamine from a product of hydrogenating adiponitrile to synthesize hexamethylenediamine, the method comprising the following steps:

[0010] (1) The product of hydrogenating adiponitrile to synthesize hexamethylenediamine is distilled in a lightness removal tower to collect the bottom liquid;

[0011] (2) distilling the bottom liquid obtained in step (1) in a refining tower, extracting 1,2-cyclohexanediamine from the top of the tower, and completing the separation and purification of the 1,2-cyclohexanediamine;

[0012] The number of theoretical plates of the light-removal tower is ≥30 (e.g., 35, 40, 45, or 50, etc.), the tower top operating pressure is -0.099 to -0.06 MPaG (e.g., -0.06 MPaG, -0.07 MPaG, -0.08 MPaG, or -0.09 MPaG, etc.), and the tower bottom operating temperature is 115 to 160° C. (e.g., 120° C., 125° C., 130° C., 135° C., 140° C., 150° C., or 155° C., etc.);

[0013] The theoretical plate number of the refining tower is ≥40 (for example, 45, 50, 55 or 60, etc.), the top operating pressure is -0.099 to -0.07MpaG (for example, -0.09MpaG, -0.08MpaG or -0.07MpaG, etc.), and the top operating temperature is 90 to 150°C (for example, 95°C, 105°C, 120°C, 130°C, 140°C, or 145°C, etc.).

[0014] Since the boiling points of the components in the product of hydrogenation of adiponitrile to synthesize hexamethylenediamine are very close (the molecular weight of 1,5-pentamethylenediamine is 102.2 and the boiling point is 180°C, the molecular weights of 1,2-cyclohexamethylenediamine and o-methylcyclopentylamine are both 114.2 and the boiling points are 190°C and 199°C respectively, and the molecular weight of 1,6-hexamethylenediamine is 116.2 and the boiling point is 205°C), it is difficult to obtain high-purity 1,2-cyclohexamethylenediamine by conventional separation and purification methods; the method provided by the present invention adopts a light removal tower and a refining tower By combining them and limiting the theoretical plate number, operating pressure and operating temperature of the two, the bottom liquid of the light-removal tower was distilled using a refining tower with a high theoretical plate number and under high vacuum conditions, and 1,2-cyclohexanediamine was successfully separated and purified. At the same time, since the bottom temperature of the light-removal tower was limited to 115-160°C, the bottom liquid containing heat-sensitive substances (1,2-cyclohexanediamine and 1,6-hexanediamine) was not easily carbonized and coked, thereby further ensuring that the purified 1,2-cyclohexanediamine was of high quality.

[0015] Preferably, the product of hydrogenating adiponitrile to synthesize hexamethylenediamine includes water, 1,5-pentamethylenediamine, 1,2-cyclohexamethylenediamine, o-methylaminocyclopentylamine and 1,6-hexamethylenediamine.

[0016] Preferably, the mass percentage of water in the product of hydrogenating adiponitrile to hexamethylenediamine is 1-5%, for example, 1.5%, 2%, 2.5%, 3%, 3.5%, 4% or 4.5%.

[0017] Preferably, the mass percentage of 1,5-pentanediamine in the product of hydrogenating adiponitrile to hexamethylenediamine is 0.1-5%, for example, 0.5%, 1%, 2%, 3% or 4%.

[0018] Preferably, the mass percentage of 1,2-cyclohexanediamine in the product of hydrogenating adiponitrile to hexamethylenediamine is 40-88%, for example, 45%, 50%, 55%, 60%, 65% or 70%.

[0019] Preferably, the mass percentage of o-methylaminocyclopentylamine (AMCPA) in the product of hydrogenating adiponitrile to synthesize hexamethylenediamine is 0.1-5.0%, for example, 0.5%, 1%, 2%, 3% or 4%.

[0020] Preferably, the mass percentage of 1,6-hexanediamine in the product of hydrogenating adiponitrile to hexamethylenediamine is 10-58%, for example, 15%, 25%, 35%, 45% or 55%.

[0021] Preferably, the product of hydrogenating adiponitrile to synthesize hexamethylenediamine further includes alcohol compounds and / or 1,4-butanediamine.

[0022] Preferably, the total mass percentage of alcohol compounds in the product of hydrogenating adiponitrile to hexamethylenediamine is 0 to 5000 ppm and is not equal to 0, such as 500 ppm, 1000 ppm, 2000 ppm, 3000 ppm or 4000 ppm.

[0023] Preferably, the alcohol compound includes ethanol and cyclopentanol.

[0024] Preferably, the mass percentage of 1,4-butanediamine in the product of hydrogenating adiponitrile to hexamethylenediamine is 0 to 5000 ppm and is not equal to 0, such as 500 ppm, 1000 ppm, 2000 ppm, 3000 ppm or 4000 ppm.

[0025] Preferably, in step (1), the feed inlet for the product of hydrogenation of adiponitrile to hexamethylenediamine is located at the 5th to 25th (e.g., 10th, 15th, or 20th, etc.) plates from bottom to top of the lightness removal tower, which needs to be determined in combination with the theoretical number of plates of the lightness removal tower.

[0026] Preferably, the reflux ratio of the lightness removal tower is 10 to 30, such as 15, 20 or 25.

[0027] Preferably, in step (2), the feed port of the bottom liquid is located at the 10th to 35th (e.g., 15th, 20th, 25th, or 30th, etc.) plate from bottom to top of the refining tower, which needs to be determined in combination with the theoretical number of plates of the refining tower.

[0028] Preferably, the reflux ratio of the refining tower is 10 to 20, such as 12, 15 or 17.

[0029] Preferably, after the distillation in step (1), water, 1,5-pentanediamine, optionally 1,4-butanediamine, optionally cyclopentanol and optionally ethanol are produced at the top of the lightness removal tower.

[0030] Preferably, the refining tower in step (2) is provided with a refining section, an impurity removal section and a stripping section in order from top to bottom, and the 1,2-cyclohexanediamine is extracted from the top of the refining section.

[0031] Preferably, the impurity removal section is located on the 2nd to 7th (eg, 2nd, 5th, or 7th, etc.) theoretical plates from bottom to top of the refining tower.

[0032] Preferably, the impurity removal section is provided with a side line, and the o-methylaminocyclopentylamine is produced from the side line.

[0033] The refining tower used in the method provided by the present invention is provided with a side line extraction. This is mainly because after the bottom liquid of the refining tower returns to the hexamethylenediamine distillation device, AMCPA will cause accumulation in the entire hexamethylenediamine refining system, making the separation of 1,2-cyclohexanediamine and 1,6-hexamethylenediamine more difficult. By providing a side line extraction of AMCPA, the separation effect of 1,2-cyclohexanediamine and 1,6-hexamethylenediamine is helped to be improved.

[0034] Preferably, the 1,6-hexanediamine is withdrawn from the bottom of the stripping section.

[0035] As a preferred technical solution of the present invention, the method comprises the following steps:

[0036] (1) feeding a product of hydrogenating adiponitrile to synthesize hexamethylenediamine, including water, 1,5-pentanediamine, 1,2-cyclohexanediamine, o-methylaminocyclopentylamine, 1,6-hexanediamine, optionally an alcohol compound, and 1,4-butanediamine, from the 5th to 25th plates of a light-removal tower from bottom to top for rectification, wherein the theoretical number of plates of the light-removal tower is ≥30, the operating pressure at the top of the tower is -0.099 to -0.06 MPaG, the operating temperature of the bottom of the tower is 115 to 160° C., and the reflux ratio is 10 to 30; collecting the bottom liquid at the bottom of the tower, and producing water, 1,5-pentanediamine, 1,4-butanediamine, and optionally an alcohol compound at the top of the tower;

[0037] (2) The bottom liquid obtained in step (1) is distilled in a refining tower which is provided with a refining section, an impurity removal section and a stripping section in order from top to bottom, wherein the theoretical plate number of the refining tower is ≥40, the tower top operating pressure is -0.099 to -0.07 MPaG, the tower top operating temperature is 90 to 150° C., and the reflux ratio is 10 to 20. The feeding position of the bottom liquid is the 10th to 35th plate from the bottom to the top of the theoretical plate number, the impurity removal section is located at the 2nd to 7th plate from the bottom to the top of the refining tower, and the impurity removal section is provided with a side line. O-methylaminocyclopentylamine is withdrawn from the side line of the impurity removal section, 1,2-cyclohexanediamine is withdrawn from the top of the refining section, and 1,6-hexanediamine is withdrawn from the bottom of the stripping section, thereby completing the separation and purification of the 1,2-cyclohexanediamine.

[0038] The method for separating and purifying 1,2-cyclohexanediamine of the present invention is a continuous separation process.

[0039] In a second aspect, the present invention provides an application of the method described in the first aspect in separating and purifying 1,2-cyclohexanediamine.

[0040] In a third aspect, the present invention provides a separation and purification device for separating and purifying 1,2-cyclohexanediamine from a product of hydrogenating adiponitrile to synthesize hexamethylenediamine, characterized in that the separation and purification device comprises a lightness removal tower and a refining tower.

[0041] The present invention provides a separation and purification device for separating and purifying 1,2-cyclohexanediamine from a product synthesized from hexamethylenediamine by hydrogenating adiponitrile, comprising a lightness removal tower and a refining tower. The device can be used to separate and purify 1,2-cyclohexanediamine from a product synthesized from hexamethylenediamine by hydrogenating adiponitrile, wherein the product synthesized from hexamethylenediamine is directly fed into the lightness removal tower for distillation, and the bottom liquid is collected and fed into the refining tower for distillation. Pure 1,2-cyclohexanediamine is extracted from the top of the refining tower, and 1,6-hexamethylenediamine can be directly extracted from the bottom of the refining tower. Furthermore, the device can be directly connected to a 1,6-hexamethylenediamine refining device.

[0042] The number of theoretical plates of the light-removal tower is ≥30 (e.g., 35, 40, 45, or 50, etc.), the tower top operating pressure is -0.099 to -0.06 MPaG (e.g., -0.06 MPaG, -0.07 MPaG, -0.08 MPaG, or -0.09 MPaG, etc.), and the tower bottom operating temperature is 115 to 160° C. (e.g., 125° C., 130° C., 135° C., 140° C., 145° C., 150° C., or 160° C., etc.);

[0043] The theoretical plate number of the refining tower is ≥40 (for example, 45, 50, 55 or 60, etc.), the top operating pressure is -0.099 to -0.07MpaG (for example, -0.09MpaG, -0.08MpaG or -0.07MpaG, etc.), and the top operating temperature is 90 to 150°C (for example, 95°C, 105°C, 120°C, 130°C, 140°C, or 145°C, etc.).

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] The method for separating and purifying 1,2-cyclohexanediamine from the product of hexamethylenediamine synthesized by hydrogenation of adiponitrile provided by the present invention is a continuous separation process, comprising the steps of first continuously feeding the product of hexamethylenediamine synthesized by hydrogenation of adiponitrile into a lightness removal tower, performing distillation in the lightness removal tower, collecting the tower bottom liquid, and then performing distillation on the obtained tower bottom liquid in a refining tower, and extracting 1,2-cyclohexanediamine from the tower top; the method is achieved by limiting the theoretical plate number of the lightness removal tower to ≥30 and the tower top operating pressure to -0.099~ The process was carried out under the following conditions: -0.06MPaG, bottom operating temperature of 115-160℃, theoretical plate number of the refining tower limited to ≥40, top operating pressure of -0.099-0.07MPaG, top operating temperature of 90-150℃, 1,2-cyclohexanediamine was successfully separated and purified from the hexamethylenediamine product of adiponitrile with complex components and similar physical properties, with high yield and purity, effectively improving the product quality and production efficiency of 1,2-cyclohexanediamine. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 A process flow chart of the method for separating and purifying 1,2-cyclohexanediamine from the product of hydrogenating adiponitrile to synthesize hexamethylenediamine provided in Example 1;

[0047] Among them, 1-lightness removal tower, 2-refining tower. DETAILED DESCRIPTION

[0048] The technical solution of the present invention is further described below by way of specific embodiments. It should be understood by those skilled in the art that the embodiments are merely to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0049] The source of the product of hydrogenating adiponitrile to synthesize hexamethylenediamine used in the present invention can be specifically referred to CN113248389A.

[0050] Example 1

[0051] A method for separating and purifying 1,2-cyclohexanediamine from the product of hexamethylenediamine synthesized by hydrogenation of adiponitrile, the process flow diagram is as follows: Figure 1 As shown, the method specifically includes the following steps:

[0052] (1) The product of hydrogenating adiponitrile to synthesize hexamethylenediamine (mass composition: 3.5% water, 0.05% ethanol, 0.1% cyclopentanol, 0.05% 1,4-butanediamine, 2% 1,5-pentanediamine, 41% 1,2-cyclohexanediamine, 2.6% o-methylaminocyclopentylamine and 50.7% 1,6-hexanediamine) is continuously fed into a light-removal column 1 having 50 theoretical plates for rectification. The feed position is located at the fifth plate from bottom to top. The top operating pressure of the light-removal column 1 is -0.09 MPa(G), the bottom operating temperature is 128°C, the top operating temperature is 50°C, the reflux ratio is 20, and light components (including water, ethanol, cyclopentanol, 1,4-butanediamine and 1,5-pentanediamine) are extracted from the top of the column, and the bottom liquid is obtained in the bottom of the column;

[0053] (2) The bottom liquid obtained in step (1) is distilled again in a refining tower 2, the number of theoretical plates of the refining tower 2 is 50, the feed position of the bottom liquid is the 24th block from the bottom of the refining tower, the top operating pressure is -0.096 MPa (G), the top operating temperature is 100°C, the bottom operating temperature is 115.8°C, the reflux ratio is 12, and a refining section, an impurity removal section and a stripping section are sequentially arranged from top to bottom. The impurity removal section is provided with a side line, and the side line is provided at the 5th theoretical plate from the bottom to the top of the refining tower 2. 1,2-cyclohexanediamine (purity of 99.5%) is withdrawn from the top of the refining section, o-methylaminocyclopentylamine is withdrawn from the side line, and 1,6-hexanediamine is withdrawn from the bottom liquid of the refining tower 2 and pumped to the hexanediamine distillation system to complete the separation and purification of the 1,2-cyclohexanediamine.

[0054] Example 2

[0055] A method for separating and purifying 1,2-cyclohexanediamine from a product of hexamethylenediamine synthesized by hydrogenating adiponitrile, the method comprising the following steps:

[0056] (1) The product of hydrogenating adiponitrile to synthesize hexamethylenediamine (mass composition: 1% water, 0.05% ethanol, 0.1% cyclopentanol, 0.05% 1,4-butanediamine, 0.1% 1,5-pentanediamine, 88% 1,2-cyclohexanediamine, 0.7% o-methylaminocyclopentylamine, and 10% 1,6-hexanediamine) is continuously fed into a light-removal column having 30 theoretical plates for rectification. The feed position is located at the fifth plate from bottom to top. The top operating pressure of the light-removal column is -0.08 MPa(G), the bottom operating temperature is 140°C, the top operating temperature is 46°C, the reflux ratio is 30, water, ethanol, cyclopentanol, 1,4-butanediamine, and 1,5-pentanediamine are produced from the top of the column, and the bottom liquid is obtained from the bottom of the column.

[0057] (2) The bottom liquid obtained in step (1) is distilled in a refining tower, the number of theoretical plates of the refining tower is 55, the feeding position of the bottom liquid is the 35th plate from the bottom of the refining tower, the top operating pressure is -0.07 MPa (G), the top operating temperature is 145 ° C, the bottom operating temperature is 157.5 ° C, the reflux ratio is 10, and a refining section, an impurity removal section and a stripping section are sequentially arranged from top to bottom. The impurity removal section is provided with a side line, and the side line is provided at the 5th theoretical plate from the bottom to the top of the refining tower. 1,2-cyclohexanediamine (purity is 99.2%) is extracted from the top of the refining section, o-methylaminocyclopentylamine is extracted from the side line, and 1,6-hexanediamine is extracted from the bottom of the tower and pumped to the hexanediamine distillation system to complete the separation and purification of the 1,2-cyclohexanediamine.

[0058] Example 3

[0059] A method for separating and purifying 1,2-cyclohexanediamine from a product of hexamethylenediamine synthesized by hydrogenating adiponitrile, the method comprising the following steps:

[0060] (1) The product of hydrogenating adiponitrile to synthesize hexamethylenediamine (mass composition: 1% water, 0.07% ethanol, 0.08% 1,4-butanediamine, 0.55% 1,5-pentanediamine, 40% 1,2-cyclohexanediamine, 0.3% o-methylaminocyclopentylamine, and 58% 1,6-hexanediamine) is continuously fed into a lightness removal column with 50 theoretical plates for rectification. The feed position is the 25th plate from bottom to top. The operating pressure at the top of the column is -0.09 MPa(G), the operating temperature at the bottom of the column is 130.8°C, the operating temperature at the top of the column is 50°C, the reflux ratio is 30, water, ethanol, cyclopentanol, and 1,5-pentanediamine are produced at the top of the column, and the bottom liquid is obtained in the bottom of the column.

[0061] (2) The bottom liquid obtained in step (1) is distilled in a refining tower, the number of theoretical plates of the refining tower is 40, the feed position is the 10th plate from bottom to top, the tower top operating pressure is -0.098 MPa (G), the tower top operating temperature is 90°C, the tower bottom operating temperature is 108°C, the reflux ratio is 20, and a refining section, an impurity removal section and a stripping section are sequentially arranged from top to bottom. The impurity removal section is provided with a side line, and the side line is provided at the 5th theoretical plate from bottom to top of the refining tower. 1,2-cyclohexanediamine (purity is 99.5%) is extracted from the top of the refining section, o-methylaminocyclopentylamine is extracted from the side line, and 1,6-hexanediamine is extracted from the bottom liquid of the tower and pumped to the hexanediamine distillation system to complete the separation and purification of the 1,2-cyclohexanediamine.

[0062] Example 4

[0063] A method for separating and purifying 1,2-cyclohexanediamine from a product of hexamethylenediamine synthesized by hydrogenating adiponitrile, the method comprising the following steps:

[0064] (1) The product of hydrogenating adiponitrile to synthesize hexamethylenediamine (mass composition: 5% water, 0.3% ethanol, 0.2% cyclopentanol, 0.5% 1,4-butanediamine, 5% 1,5-pentanediamine, 50% 1,2-cyclohexanediamine, 5% o-methylaminocyclopentylamine and 34% 1,6-hexanediamine) is continuously fed into a lightness removal column with 55 theoretical plates for rectification. The feed position is the 25th plate from bottom to top. The operating pressure at the top of the column is -0.06 MPa(G), the operating temperature at the bottom of the column is 157.5°C, the operating temperature at the top of the column is 58°C, the reflux ratio is 10, water, ethanol, cyclopentanol, 1,4-butanediamine and 1,5-pentanediamine are produced at the top of the column, and the bottom liquid is obtained in the bottom of the column;

[0065] (2) The bottom liquid obtained in step (1) is distilled in a refining tower, the number of theoretical plates of the refining tower is 40, the feed position is the 22nd plate from bottom to top, the tower top operating pressure is -0.088 MPa (G), the tower top operating temperature is 124 ° C, the tower bottom operating temperature is 137 ° C, the reflux ratio is 15, and a refining section, an impurity removal section and a stripping section are sequentially arranged from top to bottom. A side line is set at the bottom of the impurity removal section, and the side line is set at the 7th theoretical plate from bottom to top of the refining tower. 1,2-cyclohexanediamine (purity is 99.2%) is extracted from the top of the refining section, and o-methylaminocyclopentylamine is extracted from the side line. 1,6-hexanediamine is extracted from the bottom liquid of the tower bottom and pumped to the hexanediamine distillation system to complete the separation and purification of the 1,2-cyclohexanediamine.

[0066] Example 5

[0067] A method for separating and purifying 1,2-cyclohexanediamine from a product of hydrogenating adiponitrile to hexanediamine, the method differing from Example 1 only in that the top operating pressure of the lightness removal tower is -0.099 MPaG, the bottom operating temperature is 115°C, the top operating pressure of the refining tower is -0.099 MPaG, and the top operating temperature is 90°C. Other parameters and steps are the same as those in Example 1.

[0068] Example 6

[0069] A method for separating and purifying 1,2-cyclohexanediamine from a product of hexamethylenediamine synthesized by hydrogenating adiponitrile, the method comprising the following steps:

[0070] (1) The product of hydrogenating adiponitrile to synthesize hexamethylenediamine (mass composition: 3.0% water, 0.06% ethanol, 0.1% cyclopentanol, 2% 1,5-pentanediamine, 52% 1,2-cyclohexanediamine, 2.1% o-methylaminocyclopentylamine, and 40.74% 1,6-hexanediamine) is continuously fed into a lightness removal column with 40 theoretical plates for rectification. The feed position is the sixth plate from bottom to top. The operating pressure at the top of the column is -0.087 MPa(G), the operating temperature at the bottom of the column is 134°C, the operating temperature at the top of the column is 50°C, the reflux ratio is 15, water, ethanol, 1,5-cyclopentanol, and pentamethylenediamine are produced from the top of the column, and the bottom liquid is fed into a refining column.

[0071] (2) The bottom liquid obtained in step (1) is distilled in a refining tower, the number of theoretical plates of the refining tower is 50, the feed position is the 26th plate from bottom to top, the tower top operating pressure is -0.095 MPa (G), the tower top operating temperature is 104.3 ° C, the tower bottom operating temperature is 118.6 ° C, the reflux ratio is 15, and a refining section, an impurity removal section and a stripping section are sequentially arranged from top to bottom. A side line is set at the bottom of the impurity removal section, and the side line is set at the second theoretical plate from bottom to top of the refining tower. 1,2-cyclohexanediamine (purity of 99.6%) is extracted from the top of the refining section, and o-methylaminocyclopentylamine is extracted from the side line. The bottom liquid 1,6-hexanediamine is obtained in the tower bottom and pumped to the hexanediamine distillation system to complete the separation and purification of the 1,2-cyclohexanediamine.

[0072] Example 7

[0073] A method for separating and purifying 1,2-cyclohexanediamine from the product of hydrogenating adiponitrile to synthesize hexamethylenediamine, which differs from Example 1 only in that the feed position of the tower bottom liquid in step (2) is located at the 8th plate from the bottom to the top of the refining tower, and the other parameters and steps are the same as those in Example 1.

[0074] Example 8

[0075] A method for separating and purifying 1,2-cyclohexanediamine from a product of hydrogenating adiponitrile to synthesize hexanediamine, the method differing from Example 1 only in that the reflux ratio of the refining tower is 6, and the other parameters and steps are the same as those in Example 1.

[0076] Comparative Example 1

[0077] A method for separating and purifying 1,2-cyclohexanediamine from a product of hydrogenating adiponitrile to synthesize hexamethylenediamine, which differs from Example 1 only in that the number of theoretical plates of the refining tower is 25, and other parameters and steps are the same as those in Example 1.

[0078] Comparative Example 2

[0079] A method for separating and purifying 1,2-cyclohexanediamine from a product of hydrogenating adiponitrile to hexanediamine, the method differing from Example 1 only in that the top operating pressure of the refining tower is -0.06 MPaG, the top operating temperature is 159° C., and the bottom operating temperature is 168° C.; other parameters and steps are the same as those in Example 1.

[0080] Performance testing:

[0081] (1) Yield of 1,2-cyclohexanediamine: Yield of 1,2-cyclohexanediamine = the amount of 1,2-cyclohexanediamine produced to meet the requirements / the amount of 1,2-cyclohexanediamine in the raw materials × 100%;

[0082] (2) Purity of 1,2-cyclohexanediamine: Detected by gas chromatography.

[0083] The samples provided in Examples 1 to 8 and Comparative Examples 1 to 2 were tested according to the above test method. The test results are shown in Table 1:

[0084] Table 1

[0085]

[0086]

[0087] According to the data in Table 1, we can see that:

[0088] The purity of 1,2-cyclohexanediamine in the products obtained in Examples 1 to 6 is 99.2 to 99.6%, and the yield of 1,2-cyclohexanediamine is 90.9 to 95.5%;

[0089] Comparing the data of Example 1 and Comparative Example 1, it can be found that the theoretical plate number of the refining tower is too low, which will lead to a decrease in the purity and yield of 1,2-cyclohexanediamine in the final product;

[0090] By comparing the data of Example 1 and Comparative Example 2, it can be found that the top operating pressure and operating temperature of the refining tower are not within the specified range of the present invention, which will also lead to a decrease in the purity and yield of 1,2-cyclohexanediamine in the final product.

[0091] Comparing the data of Example 1 with those of Examples 7 and 8, it can be found that the feed position of the bottom liquid and the reflux ratio of the refining tower also affect the purity and yield of the final 1,2-cyclohexanediamine.

[0092] The applicant states that while the present invention, through the aforementioned embodiment, illustrates a method for separating and purifying 1,2-cyclohexanediamine from the product of hydrogenating adiponitrile to hexanediamine, the present invention is not limited to the aforementioned process steps, nor does it necessarily rely on the aforementioned process steps for implementation. Persons skilled in the art will appreciate that any improvements to the present invention, equivalent substitutions for the raw materials used, addition of auxiliary components, and selection of specific methods, etc., fall within the scope of protection and disclosure of the present invention.

Claims

1. A method for separating and purifying 1,2-cyclohexanediamine from a product of hexamethylenediamine synthesized by hydrogenation of adiponitrile, characterized in that: The method comprises the following steps: (1) The product of hydrogenating adiponitrile to synthesize hexamethylenediamine is distilled in a lightness removal tower to collect the bottom liquid; (2) distilling the bottom liquid obtained in step (1) in a refining tower, extracting 1,2-cyclohexanediamine from the top of the tower, and completing the separation and purification of the 1,2-cyclohexanediamine; The products of the hydrogenation of adiponitrile to synthesize hexamethylenediamine include water, 1,5-pentamethylenediamine, 1,2-cyclohexamethylenediamine, o-methylaminocyclopentylamine and 1,6-hexamethylenediamine; The theoretical plate number of the lightness removal tower is ≥30, the top operating pressure is -0.099 to -0.06 MPaG, and the bottom operating temperature is 115 to 160°C; The refining tower has a theoretical plate number of ≥40, a reflux ratio of 10 to 20, a top operating pressure of -0.099 to -0.07 MPaG, and a top operating temperature of 90 to 150° C. The refining tower is provided with a refining section, an impurity removal section and a stripping section in sequence from top to bottom, and the 1,2-cyclohexanediamine is extracted from the top of the refining section; The impurity removal section is located at the 2nd to 7th plates from the bottom to the top of the refining tower; The impurity removal section is provided with a side line, and the o-methylaminocyclopentylamine is produced from the side line.

2. The method according to claim 1, characterized in that The mass percentage of water in the product of synthesizing hexamethylenediamine by hydrogenating adiponitrile is 1-5%.

3. The method according to claim 1, characterized in that The mass percentage of 1,5-pentanediamine in the product of hydrogenating adiponitrile to synthesize hexamethylenediamine is 0.1-5%.

4. The method according to claim 1, wherein The mass percentage of 1,2-cyclohexanediamine in the product of synthesizing hexamethylenediamine by hydrogenating adiponitrile is 40-88%.

5. The method according to claim 1, characterized in that The mass percentage of o-methylaminocyclopentylamine in the product of synthesizing hexamethylenediamine by hydrogenating adiponitrile is 0.1-5%.

6. The method according to claim 1, characterized in that The mass percentage of 1,6-hexanediamine in the product of hydrogenating adiponitrile to synthesize hexamethylenediamine is 10-58%.

7. The method according to claim 1, characterized in that The product of synthesizing hexamethylenediamine by hydrogenating adiponitrile also includes alcohol compounds and / or 1,4-butanediamine.

8. The method according to claim 7, characterized in that The total mass percentage of alcohol compounds in the product of hydrogenating adiponitrile to synthesize hexamethylenediamine is 0 to 5000 ppm and is not equal to 0.

9. The method according to claim 7, characterized in that The alcohol compound includes ethanol and / or cyclopentanol.

10. The method according to claim 7, characterized in that The mass percentage of 1,4-butanediamine in the product of hydrogenating adiponitrile to synthesize hexamethylenediamine is 0 to 5000 ppm and is not equal to 0.

11. The method according to claim 1, wherein In step (1), the feed inlet for the product of hydrogenating adiponitrile to synthesize hexamethylenediamine is located at the 5th to 25th plates from the bottom to the top of the light removal tower.

12. The method according to claim 1, characterized in that The reflux ratio of the lightness removal tower is 10-30.

13. The method according to claim 1, wherein In step (2), the feed port of the bottom liquid is located at the 10th to 35th plates from bottom to top of the refining tower.

14. The method according to claim 1, wherein After the distillation in step (1), water, 1,5-pentanediamine, 1,4-butanediamine, optionally cyclopentanol and optionally ethanol are produced at the top of the lightness removal tower.

15. The method according to claim 1, wherein The 1,6-hexanediamine is extracted from the bottom of the stripping section.

16. The method according to any one of claims 1 to 15, characterized in that The method comprises the following steps: (1) feeding a product of hydrogenating adiponitrile to synthesize hexamethylenediamine, including water, 1,5-pentanediamine, 1,2-cyclohexanediamine, o-methylaminocyclopentylamine, 1,6-hexanediamine, optionally an alcohol compound, and 1,4-butanediamine, from the 5th to 25th plates from the bottom to the top of a lightness removal tower for rectification, wherein the theoretical plate number of the lightness removal tower is ≥30, the tower top operating pressure is -0.099 to -0.06 MPaG, the tower bottom operating temperature is 115 to 160° C., and the reflux ratio is 10 to 30, collecting the tower bottom liquid at the bottom of the lightness removal tower, and producing water, 1,5-pentanediamine, 1,4-butanediamine, and optionally an alcohol compound at the top of the tower; (2) The bottom liquid obtained in step (1) is distilled in a refining tower which is provided with a refining section, an impurity removal section and a stripping section in order from top to bottom, wherein the theoretical plate number of the refining tower is ≥40, the tower top operating pressure is -0.099 to -0.07 MPaG, the tower top operating temperature is 90 to 150° C., and the reflux ratio is 10 to 20. The feed position of the bottom liquid is located at the 10th to 35th plates from the bottom of the refining tower, the impurity removal section is located at the 2nd to 7th plates from the bottom of the refining tower, and the impurity removal section is provided with a side line. O-methylaminocyclopentylamine is extracted from the side line of the impurity removal section, 1,2-cyclohexanediamine is extracted from the top of the refining section, and 1,6-hexanediamine is extracted from the bottom of the stripping section, thereby completing the separation and purification of 1,2-cyclohexanediamine.

17. Use of the method according to any one of claims 1 to 16 in separating and purifying 1,2-cyclohexanediamine.

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