Purification method of 1, 3, 6-hexane trinitrile

Abstract

The invention discloses a purification method of 1, 3, 6-hexanetricarbonitrile. The purification method comprises the following steps: S1, extracting a crude product 1, 3, 6-hexanetricarbonitrile by using an extracting agent; s2, carrying out vacuum film rectification on the 1, 3, 6-hexanetricarbonitrile extracted in the step S1; s3, diluting the 1, 3, 6-hexanetricarbonitrile rectified in the step S2 by using a diluent, and then decolorizing by using activated carbon; and S4, carrying out reduced pressure distillation on the decolored 1, 3, 6-hexanetricarbonitrile in the step S3, and when no diluent flows out, introducing nitrogen into the 1, 3, 6-hexanetricarbonitrile and continuously distilling to obtain a target product. According to the method, the purity and chromaticity meet the requirements of a battery grade after extraction with an extracting agent, decoloration with activated carbon and reduced pressure distillation, then nitrogen is introduced to take away residual moisture and diluent without introducing other substances, so that the content of metal ions meets the requirements of the battery grade, higher requirements are met through a simple method, and industrial production is facilitated.

Description

Technical Field

[0001] The present application relates to the field of chemical substance purification, and in particular to a method for purifying 1,3,6-hexanetrinitrile. Background Art

[0002] 1,3,6-hexanetrinitrile is an organic compound containing three cyano groups in its molecular structure. Since the carbon-nitrogen triple bond in the cyano group has a high bond energy and is not easily oxidized, nitriles have good stability and oxidation resistance on the positive electrode of the battery. The cyano group also has a strong coordination ability and can combine with the active sites on the surface of the positive electrode (such as high-valent metal ions such as nickel / cobalt / manganese, etc.), masking the active ions on the positive electrode surface, thereby reducing the decomposition of the electrode on the electrolyte. Therefore, 1,3,6-hexanetrinitrile can enhance the resistance of the electrolyte to positive electrode oxidation, thereby improving the cycle life of the electrolyte under high voltage.

[0003] However, there are relatively stringent requirements on the purity, color, moisture, metal ion content and other indicators of battery-grade 1,3,6-hexanetricarbonitrile. Generally, its purity is required to be above 99.0% and its color is below 50, that is, it is visually a colorless, clear and transparent liquid, with moisture below 100ppm and metal ion content below 3ppm.

[0004] Chinese patent CN104387291A discloses a method for purifying 1,3,6-hexane trinitrile, wherein the crude product is first distilled to an orange-yellow liquid, and then stirred, filtered, washed, concentrated, and other steps are performed for 16 hours with oxidants such as hydrogen peroxide, sodium hypochlorite, sodium periodate, potassium permanganate, potassium dichromate, hydrogen peroxide / ferric chloride, etc. to obtain a light yellow oily liquid as the finished product. The chromaticity of the product obtained by the above method is light yellow, which cannot meet the requirements of battery-grade 1,3,6-hexane trinitrile, and a large amount of potassium salt, sodium salt, manganese salt, and iron salt used in the purification process will cause the metal ion content of 1,3,6-hexane trinitrile to exceed the standard.

[0005] Therefore, it is necessary to provide a new method for purifying 1,3,6-hexane trinitrile so that its purity, chromaticity, moisture, metal ion content and other indicators can meet the requirements of battery-grade 1,3,6-hexane trinitrile. Summary of the invention

[0006] In order to solve the technical problems existing in the above-mentioned prior art, the present application provides a method for purifying 1,3,6-hexane trinitrile, comprising the following steps:

[0007] S1. extracting the crude 1,3,6-hexanetrinitrile using an extractant;

[0008] S2. subjecting the 1,3,6-hexane trinitrile extracted in step S1 to vacuum thin film distillation;

[0009] S3. diluting the 1,3,6-hexane trinitrile after distillation in step S2 with a diluent and then decolorizing with activated carbon;

[0010] S4. The 1,3,6-hexane tricarbonitrile decolorized in step S3 is subjected to reduced pressure distillation. When no diluent flows out, nitrogen is introduced into the 1,3,6-hexane tricarbonitrile and the distillation is continued to obtain the target product.

[0011] By adopting the above technical solution, most of the impurities are removed by using an extractant, and then vacuum film distillation is performed to further remove impurities, and then activated carbon is used for decolorization, most of the color can be removed. Further, during the vacuum distillation, the introduction of nitrogen can quickly take away the solvent and water in 1,3,6-hexane trinitrile, and prevent 1,3,6-hexane trinitrile from turning yellow due to long-term heating. Through the above steps, after the impurities are taken away, the purity and chromaticity can meet the battery grade requirements, and then the remaining water and diluent are quickly taken away by the introduction of nitrogen, and substances such as potassium permanganate are not introduced, and the metal ion content is controlled within the battery grade requirements. A relatively high requirement is achieved through a very simple method, and it is more conducive to industrial production.

[0012] Preferably, in step S1, the volume ratio of the extractant to the crude 1,3,6-hexanetrinitrile is 1:(1-3), and the extractant is anhydrous ethanol, isopropanol or anhydrous methanol;

[0013] More preferably, the extractant is anhydrous ethanol.

[0014] By adopting the above technical scheme, since the crude 1,3,6-hexanetrinitrile contains more amine impurities, which is one of the reasons for its darker chromaticity, and most of these amine impurities are alcohol-soluble substances, while 1,3,6-hexanetrinitrile is a weakly polar organic substance, using anhydrous ethanol, isopropanol or anhydrous methanol as an extractant can remove most of the amine impurities, reduce the chromaticity of 1,3,6-hexanetrinitrile, and thus improve its purity.

[0015] Preferably, in step S2, a wiped film molecular distiller is used to perform vacuum thin film distillation to remove light components and heavy components.

[0016] Preferably, the method for removing the light components is to set the main heating temperature of the scraped film molecular distiller to 170-200°C, the distillation column temperature to 185-210°C, the vacuum degree to 20-30Pa, and the scraped film rotation speed to 250-300r / min.

[0017] Preferably, the method for removing the heavy components is to set the main heating temperature of the scraped film molecular distiller to 230-300°C, the distillation column temperature to 210-250°C, the vacuum degree to 20-30Pa, and the scraped film speed to 250-300r / min.

[0018] By adopting the above technical solution, the remaining impurities are removed in batches under different distillation methods, so that different impurities can be removed more conveniently and quickly, avoiding 1,3,6-hexanetrinitrile from turning yellow again under long-term high temperature conditions, and further reducing the chromaticity.

[0019] Preferably, in step S3, the diluent is ethyl acetate, dichloromethane or chloroform;

[0020] Preferably, the diluent is ethyl acetate.

[0021] Preferably, in step S3, the volume ratio of the 1,3,6-hexane trinitrile to the diluent is 1:(5-10), and the added amount of the activated carbon is 0.5-1% of the 1,3,6-hexane trinitrile.

[0022] By adopting the above technical scheme, 1,3,6-hexane trinitrile, as a high-viscosity organic substance, has a slow filtration speed if activated carbon is directly added for decolorization, and industrialization is not feasible. Although increasing the temperature can increase the filtration speed, the increase in temperature will cause the chromaticity of 1,3,6-hexane trinitrile to increase. Therefore, the filtration speed can be increased by simple solvent dilution, which is simple and convenient and suitable for industrial production. Experiments have found that the filtration time of diluted 1,3,6-hexane trinitrile is 6 to 10 times longer than that of undiluted 1,3,6-hexane trinitrile.

[0023] Preferably, in step S4, the temperature of the reduced pressure distillation is 50-80°C. When no diluent flows out, the temperature is adjusted to 40-60°C, nitrogen is introduced into 1,3,6-hexanetrinitrile and distillation is continued to obtain the target product.

[0024] Preferably, the nitrogen is introduced upward from the bottom of 1,3,6-hexanetrinitrile, and a vacuum is drawn above the 1,3,6-hexanetrinitrile.

[0025] Preferably, the pressure of the nitrogen when introduced is set to 0.01-0.5 MPa.

[0026] By adopting the above technical solution, the temperature is reduced to a low temperature state of 40 to 60°C, and the chromaticity of 1,3,6-hexane trinitrile is not easy to darken, and at the same time, nitrogen is introduced upward from the bottom of 1,3,6-hexane trinitrile under this low temperature state, and the nitrogen can travel inside 1,3,6-hexane trinitrile to take away the residual water and diluent that are difficult to remove, and the nitrogen carrying water and diluent is quickly pumped away by vacuuming above, so as to ensure that 1,3,6-hexane trinitrile does not turn yellow, and quickly remove the water and diluent therein, so that the chromaticity and water content of 1,3,6-hexane trinitrile are reduced to an extremely low state, reaching the standard of battery-grade 1,3,6-hexane trinitrile. The present application uses a simple method to solve the problem that is difficult to solve in the prior art, and the purification method of the present application is more suitable for industrial production.

[0027] In summary, this application has the following beneficial effects:

[0028] 1. The purification method of 1,3,6-hexane trinitrile provided in the present application adopts four steps to gradually remove the impurities that cause yellowing, and adopts a simple method to remove the remaining small part of the impurities in batches, and then the remaining water and diluent are taken away by nitrogen, so that the chromaticity, purity, water content and metal ion content of 1,3,6-hexane trinitrile meet the standards of battery-grade 1,3,6-hexane trinitrile.

[0029] 2. The purification method of 1,3,6-hexane trinitrile provided in the present application, especially at low temperature, uses nitrogen to pass from bottom to top and evacuates the top. This method can ensure that 1,3,6-hexane trinitrile does not turn yellow, and quickly removes the remaining water and diluent that are difficult to remove. The method is simple and greatly improves the convenience of industrial production. DETAILED DESCRIPTION

[0030] Example

[0031] The following example is a method for purifying 1,3,6-hexanetrinitrile.

[0032] The vacuum thin film distillation device used in the following embodiments can be any commercially available wiped film molecular distillation device.

[0033] Example 1

[0034] A method for purifying 1,3,6-hexane trinitrile, the first step is to pour 30 kg of crude 1,3,6-hexane trinitrile into an extraction kettle, slowly add 15 kg of anhydrous ethanol, stir while flowing, continue stirring for 30 to 60 minutes after the anhydrous ethanol is added, and extract the ethanol layer after standing for 30 to 60 minutes. Repeat the above steps three times, and collect the 1,3,6-hexane trinitrile in the lower layer. The ethanol in the ethanol layer can be recycled and reused.

[0035] In the second step, the extracted 1,3,6-hexane trinitrile is slowly flowed into the thin film distillation tower of the wiped film molecular distiller, the main heating temperature is set to 190°C, the distillation column temperature is set to 200°C, the speed of the scraped film is set to 280r / min, the vacuum degree is set to 20Pa, the light components are discarded, and the remaining 1,3,6-hexane trinitrile is collected;

[0036] The remaining 1,3,6-hexane trinitrile was slowly flowed into the thin film distillation tower, the main heating temperature was set to 280°C, the distillation column temperature was set to 210°C, the vacuum degree was set to 20Pa, the film scraping speed was 280r / min, the heavy components were discarded and the remaining 1,3,6-hexane trinitrile was collected.

[0037] The third step is to add 5 times the volume of ethyl acetate to the distilled 1,3,6-hexanetrinitrile, stir evenly, add 1% activated carbon, stir for 30 to 60 minutes, and then filter through plate and frame filtration and a 0.22μm precision filtration system.

[0038] In the fourth step, the filtered 1,3,6-hexane trinitrile is pressed into the distillation tower, the tower temperature is set to 70°C, and the vacuum is controlled between 0.08 and 0.1 MPa. When no ethyl acetate liquid flows out, the temperature is adjusted to 50°C, the nitrogen valve at the bottom of the kettle is opened, the nitrogen pressure is set to 0.2 MPa, and the vacuum valve above the top of the kettle is opened. The target product is obtained by continuing distillation for 2 hours by the method of downward delivery and upward extraction. Then the 1,3,6-hexane trinitrile obtained is tested for color, purity, moisture and metal ion content, and the test results are shown in Table 1.

[0039] Example 2

[0040] A method for purifying 1,3,6-hexane trinitrile, the first step is to pour 30 kg of crude 1,3,6-hexane trinitrile into an extraction kettle, slowly add 10 kg of isopropanol, stir while flowing, continue stirring for 30 to 60 minutes after the isopropanol is added, and extract the isopropanol layer after standing for 30 to 60 minutes. Repeat the above steps three times, and collect the 1,3,6-hexane trinitrile in the lower layer. The isopropanol in the isopropanol layer can be recycled and reused.

[0041] In the second step, the extracted 1,3,6-hexane trinitrile is slowly flowed into the thin film distillation tower of the wiped film molecular distiller, the main heating temperature is set to 170°C, the distillation column temperature is set to 210°C, the scraping speed is set to 250r / min, the vacuum degree is set to 30Pa, the light components are discarded, and the remaining 1,3,6-hexane trinitrile is collected;

[0042] The remaining 1,3,6-hexane trinitrile was slowly flowed into the thin film distillation tower, the main heating temperature was set to 230°C, the distillation column temperature was set to 250°C, the vacuum degree was set to 25Pa, the film scraping speed was 300r / min, the heavy components were discarded and the remaining 1,3,6-hexane trinitrile was collected.

[0043] The third step is to add 5 times the volume of ethyl acetate to the distilled 1,3,6-hexanetrinitrile, stir evenly, add 1% activated carbon, stir for 30 to 60 minutes, and then filter through plate and frame filtration and a 0.22μm precision filtration system.

[0044] In the fourth step, the filtered 1,3,6-hexane trinitrile is pressed into the distillation tower, the tower temperature is set to 70°C, and the vacuum is controlled between 0.08 and 0.1 MPa. When no ethyl acetate liquid flows out, the temperature is adjusted to 50°C, the nitrogen valve at the bottom of the kettle is opened, the nitrogen pressure is set to 0.2 MPa, and the vacuum valve above the top of the kettle is opened. The target product is obtained by continuing distillation for 2 hours by the method of downward delivery and upward extraction. Then the obtained 1,3,6-hexane trinitrile is tested for color, purity, moisture and metal ion content, and the test results are shown in Table 1.

[0045] Example 3

[0046] A method for purifying 1,3,6-hexane trinitrile, the first step is to pour 30 kg of crude 1,3,6-hexane trinitrile into an extraction kettle, slowly add 30 kg of anhydrous methanol, stir while flowing, continue stirring for 30 to 60 minutes after the anhydrous methanol is added, and extract the methanol layer after standing for 30 to 60 minutes. Repeat the above steps three times, and collect the 1,3,6-hexane trinitrile in the lower layer. The methanol in the methanol layer can be recycled and reused.

[0047] In the second step, the extracted 1,3,6-hexane trinitrile is slowly flowed into the thin film distillation tower of the wiped film molecular distiller, the main heating temperature is set to 200°C, the distillation column temperature is set to 185°C, the speed of the scraped film is set to 300r / min, the vacuum degree is set to 25Pa, the light components are discarded, and the remaining 1,3,6-hexane trinitrile is collected;

[0048] The remaining 1,3,6-hexane trinitrile was slowly flowed into the thin film distillation tower, the main heating temperature was set to 300°C, the distillation column temperature was set to 230°C, the vacuum degree was set to 25Pa, the film scraping speed was 250r / min, the heavy components were discarded and the remaining 1,3,6-hexane trinitrile was collected.

[0049] The third step is to add 5 times the volume of ethyl acetate to the distilled 1,3,6-hexanetrinitrile, stir evenly, add 1% activated carbon, stir for 30 to 60 minutes, and then filter through plate and frame filtration and a 0.22μm precision filtration system.

[0050] In the fourth step, the filtered 1,3,6-hexane trinitrile is pressed into the distillation tower, the tower temperature is set to 70°C, and the vacuum is controlled between 0.08 and 0.1 MPa. When no ethyl acetate liquid flows out, the temperature is adjusted to 50°C, the nitrogen valve at the bottom of the kettle is opened, the nitrogen pressure is set to 0.2 MPa, and the vacuum valve above the top of the kettle is opened. The target product is obtained by continuing distillation for 2 hours by the method of downward delivery and upward extraction. Then the obtained 1,3,6-hexane trinitrile is tested for color, purity, moisture and metal ion content, and the test results are shown in Table 1.

[0051] Example 4

[0052] A method for purifying 1,3,6-hexane trinitrile, the first step is to pour 30 kg of crude 1,3,6-hexane trinitrile into an extraction kettle, slowly add 15 kg of anhydrous ethanol, stir while flowing, continue stirring for 30 to 60 minutes after the anhydrous ethanol is added, and extract the ethanol layer after standing for 30 to 60 minutes. Repeat the above steps three times, and collect the 1,3,6-hexane trinitrile in the lower layer. The ethanol in the ethanol layer can be recycled and reused.

[0053] In the second step, the extracted 1,3,6-hexane trinitrile is slowly flowed into the thin film distillation tower of the wiped film molecular distiller, the main heating temperature is set to 190°C, the distillation column temperature is set to 200°C, the speed of the scraped film is set to 280r / min, the vacuum degree is set to 20Pa, the light components are discarded, and the remaining 1,3,6-hexane trinitrile is collected;

[0054] The remaining 1,3,6-hexane trinitrile was slowly flowed into the thin film distillation tower, the main heating temperature was set to 280°C, the distillation column temperature was set to 210°C, the vacuum degree was set to 20Pa, the film scraping speed was 280r / min, the heavy components were discarded and the remaining 1,3,6-hexane trinitrile was collected.

[0055] The third step is to add 10 times the volume of dichloromethane to the 1,3,6-hexanetrinitrile after distillation, stir evenly, add 0.5% activated carbon, stir for 30 to 60 minutes, and then filter through plate and frame filtration and 0.22μm precision filtration system.

[0056] In the fourth step, the filtered 1,3,6-hexane trinitrile is pressed into the distillation tower, the tower temperature is set to 70°C, and the vacuum is controlled between 0.08 and 0.1 MPa. When no ethyl acetate liquid flows out, the temperature is adjusted to 50°C, the nitrogen valve at the bottom of the kettle is opened, the nitrogen pressure is set to 0.2 MPa, and the vacuum valve above the top of the kettle is opened. The target product is obtained by continuing distillation for 2 hours by the method of downward delivery and upward extraction. Then the obtained 1,3,6-hexane trinitrile is tested for color, purity, moisture and metal ion content, and the test results are shown in Table 1.

[0057] Example 5

[0058] A method for purifying 1,3,6-hexane trinitrile, the first step is to pour 30 kg of crude 1,3,6-hexane trinitrile into an extraction kettle, slowly add 15 kg of anhydrous ethanol, stir while flowing, continue stirring for 30 to 60 minutes after the anhydrous ethanol is added, and extract the ethanol layer after standing for 30 to 60 minutes. Repeat the above steps three times, and collect the 1,3,6-hexane trinitrile in the lower layer. The ethanol in the ethanol layer can be recycled and reused.

[0059] In the second step, the extracted 1,3,6-hexane trinitrile is slowly flowed into the thin film distillation tower of the wiped film molecular distiller, the main heating temperature is set to 190°C, the distillation column temperature is set to 200°C, the speed of the scraped film is set to 280r / min, the vacuum degree is set to 20Pa, the light components are discarded, and the remaining 1,3,6-hexane trinitrile is collected;

[0060] The remaining 1,3,6-hexane trinitrile was slowly flowed into the thin film distillation tower, the main heating temperature was set to 280°C, the distillation column temperature was set to 210°C, the vacuum degree was set to 20Pa, the film scraping speed was 280r / min, the heavy components were discarded and the remaining 1,3,6-hexane trinitrile was collected.

[0061] The third step is to add 8 times the volume of chloroform to the distilled 1,3,6-hexanetrinitrile, stir evenly, add 0.8% activated carbon, stir for 30 to 60 minutes, and then filter through plate and frame filtration and a 0.22μm precision filtration system.

[0062] In the fourth step, the filtered 1,3,6-hexane trinitrile is pressed into the distillation tower, the tower temperature is set to 70°C, and the vacuum is controlled between 0.08 and 0.1 MPa. When no ethyl acetate liquid flows out, the temperature is adjusted to 50°C, the nitrogen valve at the bottom of the kettle is opened, the nitrogen pressure is set to 0.2 MPa, and the vacuum valve above the top of the kettle is opened. The target product is obtained by continuing distillation for 2 hours by the method of downward delivery and upward extraction. Then the obtained 1,3,6-hexane trinitrile is tested for color, purity, moisture and metal ion content, and the test results are shown in Table 1.

[0063] Example 6

[0064] A method for purifying 1,3,6-hexane trinitrile, the first step is to pour 30 kg of crude 1,3,6-hexane trinitrile into an extraction kettle, slowly add 15 kg of anhydrous ethanol, stir while flowing, continue stirring for 30 to 60 minutes after the anhydrous ethanol is added, and extract the ethanol layer after standing for 30 to 60 minutes. Repeat the above steps three times, and collect the 1,3,6-hexane trinitrile in the lower layer. The ethanol in the ethanol layer can be recycled and reused.

[0065] In the second step, the extracted 1,3,6-hexane trinitrile is slowly flowed into the thin film distillation tower of the wiped film molecular distiller, the main heating temperature is set to 190°C, the distillation column temperature is set to 200°C, the speed of the scraped film is set to 280r / min, the vacuum degree is set to 20Pa, the light components are discarded, and the remaining 1,3,6-hexane trinitrile is collected;

[0066] The remaining 1,3,6-hexane trinitrile was slowly flowed into the thin film distillation tower, the main heating temperature was set to 280°C, the distillation column temperature was set to 210°C, the vacuum degree was set to 20Pa, the film scraping speed was 280r / min, the heavy components were discarded and the remaining 1,3,6-hexane trinitrile was collected.

[0067] The third step is to add 5 times the volume of ethyl acetate to the distilled 1,3,6-hexanetrinitrile, stir evenly, add 1% activated carbon, stir for 30 to 60 minutes, and then filter through plate and frame filtration and a 0.22μm precision filtration system.

[0068] In the fourth step, the filtered 1,3,6-hexane trinitrile is pressed into the distillation tower, the tower temperature is set to 50°C, and the vacuum is controlled between 0.08 and 0.1 MPa. When no ethyl acetate liquid flows out, the temperature is adjusted to 40°C, the nitrogen valve at the bottom of the kettle is opened, the nitrogen pressure is set to 0.5 MPa, and the vacuum valve above the top of the kettle is opened. The target product is obtained by continuing distillation for 2 hours by the method of downward delivery and upward extraction. Then the obtained 1,3,6-hexane trinitrile is tested for color, purity, moisture and metal ion content, and the test results are shown in Table 1.

[0069] Example 7

[0070] A method for purifying 1,3,6-hexane trinitrile, the first step is to pour 30 kg of crude 1,3,6-hexane trinitrile into an extraction kettle, slowly add 15 kg of anhydrous ethanol, stir while flowing, continue stirring for 30 to 60 minutes after the anhydrous ethanol is added, and extract the ethanol layer after standing for 30 to 60 minutes. Repeat the above steps three times, and collect the 1,3,6-hexane trinitrile in the lower layer. The ethanol in the ethanol layer can be recycled and reused.

[0071] In the second step, the extracted 1,3,6-hexane trinitrile is slowly flowed into the thin film distillation tower of the wiped film molecular distiller, the main heating temperature is set to 190°C, the distillation column temperature is set to 200°C, the speed of the scraped film is set to 280r / min, the vacuum degree is set to 20Pa, the light components are discarded, and the remaining 1,3,6-hexane trinitrile is collected;

[0072] The remaining 1,3,6-hexane trinitrile was slowly flowed into the thin film distillation tower, the main heating temperature was set to 280°C, the distillation column temperature was set to 210°C, the vacuum degree was set to 20Pa, the film scraping speed was 280r / min, the heavy components were discarded and the remaining 1,3,6-hexane trinitrile was collected.

[0073] The third step is to add 5 times the volume of ethyl acetate to the distilled 1,3,6-hexanetrinitrile, stir evenly, add 1% activated carbon, stir for 30 to 60 minutes, and then filter through plate and frame filtration and a 0.22μm precision filtration system.

[0074] In the fourth step, the filtered 1,3,6-hexane trinitrile is pressed into the distillation tower, the tower temperature is set to 80°C, and the vacuum is controlled between 0.08 and 0.1 MPa. When no ethyl acetate liquid flows out, the temperature is adjusted to 60°C, the nitrogen valve at the bottom of the kettle is opened, the nitrogen pressure is set to 0.01 MPa, and the vacuum valve above the top of the kettle is opened. The target product is obtained by continuing distillation for 2 hours by the method of downward delivery and upward extraction. Then the obtained 1,3,6-hexane trinitrile is tested for color, purity, moisture and metal ion content, and the test results are shown in Table 1.

[0075] Example 8

[0076] A method for purifying 1,3,6-hexane trinitrile, the first step is to pour 30 kg of crude 1,3,6-hexane trinitrile into an extraction kettle, slowly add 15 kg of anhydrous ethanol, stir while flowing, continue stirring for 30 to 60 minutes after the anhydrous ethanol is added, and extract the ethanol layer after standing for 30 to 60 minutes. Repeat the above steps three times, and collect the 1,3,6-hexane trinitrile in the lower layer. The ethanol in the ethanol layer can be recycled and reused.

[0077] In the second step, the extracted 1,3,6-hexane trinitrile is slowly flowed into the thin film distillation tower of the wiped film molecular distiller, the main heating temperature is set to 190°C, the distillation column temperature is set to 200°C, the speed of the scraped film is set to 280r / min, the vacuum degree is set to 20Pa, the light components are discarded, and the remaining 1,3,6-hexane trinitrile is collected;

[0078] The remaining 1,3,6-hexane trinitrile was slowly flowed into the thin film distillation tower, the main heating temperature was set to 280°C, the distillation column temperature was set to 210°C, the vacuum degree was set to 20Pa, the film scraping speed was 280r / min, the heavy components were discarded and the remaining 1,3,6-hexane trinitrile was collected.

[0079] The third step is to add 5 times the volume of ethyl acetate to the distilled 1,3,6-hexanetrinitrile, stir evenly, add 1% activated carbon, stir for 30 to 60 minutes, and then filter through plate and frame filtration and a 0.22μm precision filtration system.

[0080] In the fourth step, the filtered 1,3,6-hexane trinitrile is pressed into a distillation tower, the tower bottom temperature is set to 70°C, and the vacuum degree is controlled between 0.08 and 0.1 MPa. When no ethyl acetate liquid flows out, the temperature is adjusted to 50°C, nitrogen is introduced from the top, and the nitrogen pressure is set to 0.2 MPa. The distillation is continued for 2 hours to obtain the target product. The obtained 1,3,6-hexane trinitrile is then tested for color, purity, moisture and metal ion content. The test results are shown in Table 1.

[0081] Example 9

[0082] A method for purifying 1,3,6-hexane trinitrile, the first step is to pour 30 kg of crude 1,3,6-hexane trinitrile into an extraction kettle, slowly add 15 kg of anhydrous ethanol, stir while flowing, continue stirring for 30 to 60 minutes after the anhydrous ethanol is added, and extract the ethanol layer after standing for 30 to 60 minutes. Repeat the above steps three times, and collect the 1,3,6-hexane trinitrile in the lower layer. The ethanol in the ethanol layer can be recycled and reused.

[0083] In the second step, the extracted 1,3,6-hexane trinitrile is slowly flowed into the thin film distillation tower of the wiped film molecular distiller, the main heating temperature is set to 190°C, the distillation column temperature is set to 200°C, the speed of the scraped film is set to 280r / min, the vacuum degree is set to 20Pa, the light components are discarded, and the remaining 1,3,6-hexane trinitrile is collected;

[0084] The remaining 1,3,6-hexane trinitrile was slowly flowed into the thin film distillation tower, the main heating temperature was set to 280°C, the distillation column temperature was set to 210°C, the vacuum degree was set to 20Pa, the film scraping speed was 280r / min, the heavy components were discarded and the remaining 1,3,6-hexane trinitrile was collected.

[0085] The third step is to add 5 times the volume of ethyl acetate to the distilled 1,3,6-hexanetrinitrile, stir evenly, add 1% activated carbon, stir for 30 to 60 minutes, and then filter through plate and frame filtration and a 0.22μm precision filtration system.

[0086] In the fourth step, the filtered 1,3,6-hexane trinitrile is pressed into the distillation tower, the tower temperature is set to 70°C, and the vacuum is controlled between 0.08 and 0.1 MPa. When no ethyl acetate liquid flows out, the nitrogen valve at the bottom of the kettle is opened, the nitrogen pressure is set to 0.2 MPa, and the vacuum valve above the top of the kettle is opened. The target product is obtained by continuing distillation for 2 hours by the method of downward delivery and upward extraction. Then the obtained 1,3,6-hexane trinitrile is tested for color, purity, moisture and metal ion content, and the test results are shown in Table 1.

[0087] Example 10

[0088] A method for purifying 1,3,6-hexane trinitrile, the first step is to pour 30 kg of crude 1,3,6-hexane trinitrile into an extraction kettle, slowly add 15 kg of anhydrous ethanol, stir while flowing, continue stirring for 30 to 60 minutes after the anhydrous ethanol is added, and extract the ethanol layer after standing for 30 to 60 minutes. Repeat the above steps three times, and collect the 1,3,6-hexane trinitrile in the lower layer. The ethanol in the ethanol layer can be recycled and reused.

[0089] In the second step, the extracted 1,3,6-hexane trinitrile is slowly flowed into the thin film distillation tower of the wiped film molecular distiller, the main heating temperature is set to 190°C, the distillation column temperature is set to 200°C, the speed of the scraped film is set to 280r / min, the vacuum degree is set to 20Pa, the light components are discarded, and the remaining 1,3,6-hexane trinitrile is collected;

[0090] The remaining 1,3,6-hexane trinitrile was slowly flowed into the thin film distillation tower, the main heating temperature was set to 280°C, the distillation column temperature was set to 210°C, the vacuum degree was set to 20Pa, the film scraping speed was 280r / min, the heavy components were discarded and the remaining 1,3,6-hexane trinitrile was collected.

[0091] The third step is to add 5 times the volume of ethyl acetate to the distilled 1,3,6-hexanetrinitrile, stir evenly, add 1% activated carbon, stir for 30 to 60 minutes, and then filter through plate and frame filtration and a 0.22μm precision filtration system.

[0092] In the fourth step, the filtered 1,3,6-hexane trinitrile is pressed into the distillation tower, the tower temperature is set to 100°C, and the vacuum degree is controlled between 0.08 and 0.1 MPa. When no ethyl acetate liquid flows out, the nitrogen valve at the bottom of the kettle is opened, the nitrogen pressure is set to 0.2 MPa, and the vacuum valve above the top of the kettle is opened. The target product is obtained by continuing distillation for 2 hours by the method of downward delivery and upward extraction. Then the obtained 1,3,6-hexane trinitrile is tested for color, purity, moisture and metal ion content, and the test results are shown in Table 1.

[0093] Comparative Example 1

[0094] A method for purifying 1,3,6-hexane trinitrile, the first step is to pour 30 kg of crude 1,3,6-hexane trinitrile into an extraction kettle, slowly add 15 kg of anhydrous ethanol, stir while flowing, continue stirring for 30 to 60 minutes after the anhydrous ethanol is added, and extract the ethanol layer after standing for 30 to 60 minutes. Repeat the above steps three times, and collect the 1,3,6-hexane trinitrile in the lower layer. The ethanol in the ethanol layer can be recycled and reused.

[0095] In the second step, the extracted 1,3,6-hexane trinitrile is slowly flowed into the thin film distillation tower of the wiped film molecular distiller, the main heating temperature is set to 190°C, the distillation column temperature is set to 200°C, the speed of the scraped film is set to 280r / min, the vacuum degree is set to 20Pa, the light components are discarded, and the remaining 1,3,6-hexane trinitrile is collected;

[0096] The remaining 1,3,6-hexane trinitrile was slowly flowed into the thin film distillation tower, the main heating temperature was set to 280°C, the distillation column temperature was set to 210°C, the vacuum degree was set to 20Pa, the film scraping speed was 280r / min, the heavy components were discarded and the remaining 1,3,6-hexane trinitrile was collected.

[0097] The third step is to add 5 times the volume of ethyl acetate to the distilled 1,3,6-hexanetrinitrile, stir evenly, add 1% activated carbon, stir for 30 to 60 minutes, and then filter through plate and frame filtration and a 0.22μm precision filtration system.

[0098] In the fourth step, the filtered 1,3,6-hexane trinitrile is pressed into a distillation tower, the tower bottom temperature is set to 70°C, and the vacuum degree is controlled between 0.08 and 0.1 MPa. When no ethyl acetate liquid flows out, the target product is obtained. Then the obtained 1,3,6-hexane trinitrile is tested for color, purity, moisture and metal ion content. The test results are shown in Table 1.

[0099] Table 1 Performance test table of 1,3,6-hexane trinitrile of Examples 1-10 and Comparative Example 1

[0100] Example Chroma(<50) Purity (≥99.0%) Moisture (<100ppm) Metals (<3ppm) Example 1 5 99.81 15 <3ppm Example 2 10 99.72 22 <3ppm Example 3 10 99.75 20 <3ppm Example 4 5 99.79 28 <3ppm Example 5 5 99.71 26 <3ppm Example 6 10 99.59 35 <3ppm Example 7 10 99.41 48 <3ppm Example 8 15 99.34 80 <3ppm Example 9 25 99.25 46 <3ppm Example 10 40 99.12 26 <3ppm Comparative Example 1 35 99.18 140 <3ppm

[0101] It can be seen from the experimental results of Examples 1-10, Comparative Example 1 and Table 1 that the purification method of 1,3,6-hexane trinitrile provided by the present application can make the chromaticity of the obtained 1,3,6-hexane trinitrile lower, the purity higher, and the metal ion content is lower than 3ppm, especially the moisture can be much lower than 100ppm. It can be seen that at low temperatures, the present method uses nitrogen to pass from bottom to top, and the method of vacuuming above can ensure that the 1,3,6-hexane trinitrile does not turn yellow, and quickly takes away the remaining difficult to remove moisture and diluent, while ensuring that the chromaticity of 1,3,6-hexane trinitrile no longer darkens, relative to the prior art, a relatively excellent effect is obtained, which fully meets the standard of battery-grade 1,3,6-hexane trinitrile.

[0102] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A method for purifying 1,3,6-hexanetrinitrile, characterized in that: The following steps are involved: S1. extracting the crude 1,3,6-hexanetrinitrile using an extractant; S2. subjecting the 1,3,6-hexane trinitrile extracted in step S1 to vacuum thin film distillation; S3. diluting the 1,3,6-hexane trinitrile after distillation in step S2 with a diluent and then decolorizing with activated carbon; S4. The 1,3,6-hexane tricarbonitrile decolorized in step S3 is subjected to reduced pressure distillation. When no diluent flows out, nitrogen is introduced into the 1,3,6-hexane tricarbonitrile and the distillation is continued to obtain the target product.

2. The purification method according to claim 1, characterized in that In step S1, the volume ratio of the extractant to the crude 1,3,6-hexanetrinitrile is 1:(1-3), and the extractant is anhydrous ethanol, isopropanol or anhydrous methanol; Preferably, the extractant is anhydrous ethanol.

3. The purification method according to claim 1, characterized in that In step S2, a wiped film molecular distiller is used to perform vacuum thin film distillation to remove light components and heavy components.

4. The purification method according to claim 3, characterized in that The method for removing the light components is to set the main heating temperature of the scraped film molecular distiller to 170-200°C, the distillation column temperature to 185-210°C, the vacuum degree to 20-30Pa, and the scraped film rotation speed to 250-300r / min.

5. The purification method according to claim 3, characterized in that The method for removing the heavy components is to set the main heating temperature of the scraped film molecular distiller to 230-300°C, the distillation column temperature to 210-250°C, the vacuum degree to 20-30Pa, and the scraped film speed to 250-300r / min.

6. The purification method according to claim 1, characterized in that In step S3, the diluent is ethyl acetate, dichloromethane or chloroform; Preferably, the diluent is ethyl acetate.

7. The purification method according to claim 1, characterized in that In step S3, the volume ratio of the 1,3,6-hexane trinitrile to the diluent is 1:(5-10), and the added amount of the activated carbon is 0.5-1% of the 1,3,6-hexane trinitrile.

8. The purification method according to claim 1, characterized in that In step S4, the temperature of the reduced pressure distillation is 50-80°C. When no diluent flows out, the temperature is adjusted to 40-60°C, nitrogen is introduced into 1,3,6-hexanetrinitrile and distillation is continued to obtain the target product.

9. The purification method according to claim 8, characterized in that The nitrogen gas is introduced upward from the bottom of 1,3,6-hexanetricarbonitrile, and a vacuum is drawn above 1,3,6-hexanetricarbonitrile.

10. The purification method according to claim 8, characterized in that The pressure of the nitrogen gas during introduction is set to 0.01-0.5 MPa.