A process for the preparation of N,N-diethylhexanediamine

Abstract

This invention relates to a method for preparing N,N-diethylhexanediamine, the method comprising the following steps performed sequentially: (1) filtering hexanediamine byproducts to obtain a first separated product, wherein the hexanediamine byproducts include N,N-diethylhexanediamine, dihexyltriamine, hexanediamine, sodium hydroxide crystals, aminohexanonitrile, water and 1,2-cyclohexanediamine; (2) adding the first separated product to water for mixing to obtain a layered sodium hydroxide / hexanediamine aqueous solution and a second separated product, and discharging the sodium hydroxide / hexanediamine aqueous solution to obtain the second separated product; (3) pre-distilling the second separated product to obtain a third separated product; (4) removing the third separated product from the heavy weight in a heavy weight removal tower, and collecting a fourth separated product from the top of the heavy weight removal tower; (5) removing the fourth separated product from the light weight in a light weight removal tower, and collecting N,N-diethylhexanediamine from the bottom of the light weight removal tower.

Description

Technical Field

[0001] This invention belongs to the field of separation and purification, and specifically relates to a method for preparing N,N-diethylhexanediamine. Background Technology

[0002] In the production of hexamethylenediamine, the presence of ethanol as a solvent inevitably produces N,N-diethylhexamethylenediamine. As a byproduct of hexamethylenediamine production, N,N-diethylhexamethylenediamine is currently treated as mixed hazardous waste. Incineration of this waste generates large amounts of ammonia nitrogen, resulting in significant pollution. However, purified N,N-diethylhexamethylenediamine has wide applications in fine chemical intermediates, auxiliaries and functional materials synthesis, and organic synthesis. Currently, the N,N-diethylhexamethylenediamine content in the byproducts of hexamethylenediamine production is low, and most of it is identified as hazardous waste or mixed with polyamines, requiring disposal costs or being sold at extremely low prices. This results in the underutilization of N,N-diethylhexamethylenediamine itself. Summary of the Invention

[0003] To address the above problems, the present invention provides a method for preparing N,N-diethylhexanediamine, the method comprising the following steps performed sequentially:

[0004] (1) The hexamethylenediamine byproducts are filtered to obtain the first separated product, wherein the hexamethylenediamine byproducts include N,N-diethylhexamethylenediamine, dihexylidenetriamine, hexamethylenediamine, sodium hydroxide crystals, aminohexanonitrile, water and 1,2-cyclohexamethylenediamine;

[0005] (2) The first separation product is added to water and mixed to obtain a layered sodium hydroxide / hexanediamine aqueous solution and a second separation product. The sodium hydroxide / hexanediamine aqueous solution is discharged to obtain the second separation product.

[0006] (3) The second separation product is pre-distilled to obtain the third separation product;

[0007] (4) The third separation product is deweighted in a deweighting tower, and the fourth separation product is collected from the top of the deweighting tower;

[0008] (5) The fourth separation product is subjected to light removal in a light removal tower, and N,N-diethylhexanediamine is collected from the bottom of the light removal tower.

[0009] Considering that the byproducts of hexamethylenediamine contain not only N,N-diethylhexamethylenediamine (boiling point 233.8℃, molecular weight 172.31), but also dihexylidenetriamine (boiling point 332.8℃, molecular weight 215.38), hexamethylenediamine (boiling point 204℃, molecular weight 116.2), sodium hydroxide crystals (melting point 318.4℃, molecular weight 40), aminohexanonitrile (boiling point 200.13℃, molecular weight 112.17), and 1,2-cyclohexamethylenediamine (boiling point 190℃, molecular weight 141.19), the separation and purification of N,N-diethylhexamethylenediamine presents a significant challenge. This invention creatively first filters out most of the sodium hydroxide crystals, then adds an appropriate amount of water to mix and obtain a layered sodium hydroxide / hexanediamine aqueous solution and a second separation product (water, hexanediamine, N,N-diethylhexanediamine, dihexyltriamine, aminohexanonitrile, 1,2-cyclohexanediamine). While discharging the sodium hydroxide / hexanediamine solution, the remaining sodium hydroxide and hexanediamine are removed. Then, the remaining water and hexanediamine are removed by pre-distillation to obtain a third separation product (N,N-diethylhexanediamine, dihexyltriamine, aminohexanonitrile, 1,2-cyclohexanediamine). Then, dihexyltriamine is removed by heavy removal, and finally aminohexanonitrile and 1,2-cyclohexanediamine are removed by light removal, finally obtaining high-purity and high-yield N,N-diethylhexanediamine.

[0010] Preferably, the content of N,N-diethylhexanediamine in the hexamethylenediamine byproduct is 20-40 wt%.

[0011] And / or, the content of dihexylidene triamine in the hexamethylenediamine byproduct is 20-50 wt%;

[0012] And / or, the content of hexamethylenediamine in the hexamethylenediamine byproduct is 20-40 wt%;

[0013] And / or, the content of sodium hydroxide crystals in the hexamethylenediamine byproduct is 5-10 wt%;

[0014] And / or, the content of aminohexanonitrile in the hexamethylenediamine byproduct is 1-5 wt%;

[0015] And / or, the 1,2-cyclohexanediamine content in the hexamethylenediamine byproduct is <1%.

[0016] Preferably, in step (1), the mesh size of the filter used for filtration is 40 to 80 mesh.

[0017] Preferably, in step (2), the mass ratio of the first separated product to water is (10~15):1.

[0018] Preferably, in step (3), the pre-distillation is carried out under the following conditions: temperature of 100~130℃ and time of 0.5~2 hours.

[0019] Preferably, in step (4), the theoretical number of plates in the deweighting tower is ≥40, the tower top operating pressure is 1~5 KPa, the tower top operating temperature is 130~170℃, preferably 140~160℃.

[0020] Preferably, in step (5), the theoretical number of plates in the light-light removal tower is ≥45, the operating pressure at the top of the tower is 1~5 KPa, and the operating temperature at the bottom of the tower is 130~170℃, preferably 140~170℃, and more preferably 150~160℃.

[0021] Preferably, in step (4), the feed inlet of the third separated product is located at the 25th to 35th plate from bottom to top of the heavy removal tower, and the feed inlet of the third separated product is located at 550 to 600 mm, preferably 550 mm, of the height of the light removal tower; preferably, the reflux ratio of the heavy removal tower is 10 to 20.

[0022] Preferably, in step (5), the feed inlet of the fourth separated product is located at the 20th to 30th plate from bottom to top of the light-light removal tower, and the feed inlet of the fourth separated product is located at 450 to 550 mm, preferably 500 mm, of the height of the light-light removal tower; preferably, the reflux ratio of the light-light removal tower is 10 to 30.

[0023] Preferably, in step (4), after the deweighting process, dihexyltriamine is collected at the bottom of the deweighting tower and preferably incinerated.

[0024] Preferably, in step (5), after the removal of light components, aminohexanonitrile and 1,2-cyclohexanediamine are collected from the top of the light component removal tower and preferably incinerated.

[0025] Preferably, in step (5), the purity of the obtained N,N-diethylhexanediamine is ≥99.90%, and the recovery rate is ≥90.0%, preferably ≥95.0%.

[0026] The beneficial effects of this invention are:

[0027] This invention employs a process of filtration, pre-distillation, heavy removal, and light removal to achieve the separation and purification of high-purity and high-yield N,N-diethylhexanediamine, thus solving the technical problem of producing high-purity N,N-diethylhexanediamine using hexanediamine byproducts. Attached Figure Description

[0028] Figure 1 This is a partial process flow diagram of a method for preparing N,N-diethylhexanediamine according to an embodiment of the present invention. Detailed Implementation

[0029] The present invention will be further illustrated by the following embodiments, but this is not intended to limit the present invention. Those skilled in the art can make modifications or improvements based on the basic idea of ​​the invention, but as long as they do not depart from the basic idea of ​​the present invention, they are all within the scope of the present invention.

[0030] Examples 1-13

[0031] (1) The hexamethylenediamine byproduct (N,N-diethylhexamethylenediamine content is 39.4 wt%, dihexylidenetriamine content is 21.2 wt%, hexamethylenediamine content is 23.9 wt%, sodium hydroxide crystal content is 9.8 wt%, aminohexanonitrile content is 4.9 wt%, 1,2-cyclohexamethylenediamine content is 0.8%) was first filtered (filter screen is 40 mesh) to obtain the first separated product;

[0032] (2) The first separation product and water (the mass ratio of the first separation product and water is 10:1) are mixed to obtain a layered sodium hydroxide / hexanediamine aqueous solution and a second separation product. The sodium hydroxide / hexanediamine aqueous solution is discharged to obtain the second separation product.

[0033] (3) The second separation product is pre-distilled (110℃ / 1 hour) to obtain the third separation product;

[0034] (4) The third separation product is deweighted in a deweighting tower (see Table 1), and the fourth separation product is collected from the top of the deweighting tower;

[0035] (5) The fourth separation product was subjected to light removal in a light removal tower (see Table 1), and N,N-diethylhexanediamine was collected from the bottom of the light removal tower.

[0036] Table 1 shows the process parameters for the preparation of N,N-diethylhexanediamine in Examples 1-13:

[0037]

[0038] Performance testing:

[0039] The purity of the obtained N,N-diethylhexanediamine was determined by gas chromatography.

[0040] The yield of N,N-diethylhexanediamine was taken as the ratio of the actual mass of N,N-diethylhexanediamine obtained to the theoretical mass of hexanediamine byproducts.

[0041] Table 2 shows the purity and yield of N,N-diethylhexanediamine obtained in Examples 1-13:

[0042]

[0043] Combining Table 1 and Table 2, we can see that:

[0044] Comparing Examples 10, 1, 2, 3, and 11, it can be seen that the purity and yield of N,N-diethylhexanediamine were significantly improved when the top operating temperature of the deweighting column in Examples 1-3 was between 140 and 160°C. However, in Examples 10 (where the deweighting column temperature was lower) and 11 (where the temperature was higher), at least one of the purity and yield of N,N-diethylhexanediamine decreased.

[0045] Comparing Examples 4, 2, and 5, it can be seen that the purity and yield of N,N-diethylhexanediamine obtained by operating at the top of the deweighting tower in Examples 4, 2, and 5 at a pressure of 1~5 kPa are significantly improved.

[0046] Comparing Examples 12, 8, 2, 9, and 13, it can be seen that in Examples 8, 2, and 9, the reboiler operating temperature in the light-light removal column was between 140 and 160°C, resulting in significantly improved purity and yield of N,N-diethylhexanediamine. However, in Example 12, with a lower reboiler operating temperature, and in Example 13, with a higher reboiler operating temperature, at least one of the resulting N,N-diethylhexanediamine purity and yield decreased.

[0047] Comparing Examples 6, 2, and 7, it can be seen that when the operating pressure at the top of the light-light removal column in Examples 6, 2, and 7 is between 1 and 5 kPa, the purity and yield of the obtained N,N-diethylhexanediamine are significantly improved.

Claims

1. A method for preparing N,N-diethylhexanediamine, characterized in that, The method includes the following steps performed sequentially: (1) The hexamethylenediamine byproducts are filtered to obtain the first separated product, wherein the hexamethylenediamine byproducts include N,N-diethylhexamethylenediamine, dihexylidenetriamine, hexamethylenediamine, sodium hydroxide crystals, aminohexanonitrile, water and 1,2-cyclohexamethylenediamine; (2) The first separation product is added to water and mixed to obtain a layered sodium hydroxide / hexanediamine aqueous solution and a second separation product. The sodium hydroxide / hexanediamine aqueous solution is discharged to obtain the second separation product. (3) The second separation product is pre-distilled to obtain the third separation product; (4) The third separation product is deweighted in a deweighting tower, and the fourth separation product is collected from the top of the deweighting tower; (5) The fourth separation product is subjected to light removal in a light removal tower, and N,N-diethylhexanediamine is collected from the bottom of the light removal tower.

2. The method according to claim 1, characterized in that, The content of N,N-diethylhexanediamine in the hexamethylenediamine byproduct is 20-40 wt%. And / or, the content of dihexylidene triamine in the hexamethylenediamine byproduct is 20-50 wt%; And / or, the content of hexamethylenediamine in the hexamethylenediamine byproduct is 20-40 wt%; And / or, the content of sodium hydroxide crystals in the hexamethylenediamine byproduct is 5-10 wt%; And / or, the content of aminohexanonitrile in the hexamethylenediamine byproduct is 1-5 wt%; And / or, the 1,2-cyclohexanediamine content in the hexamethylenediamine byproduct is <1%.

3. The method according to claim 1 or 2, characterized in that, In step (1), the mesh size of the filter used for filtration is 40 to 80 mesh; In step (2), the mass ratio of the first separated product to water is (10~15):

1.

4. The method according to claim 1 or 2, characterized in that, In step (3), the pre-distillation is carried out under the following conditions: temperature of 100~130℃ and time of 0.5~2 hours.

5. The method according to claim 1 or 2, characterized in that, In step (4), the theoretical number of plates in the deweight removal tower is ≥40, the tower top operating pressure is 1~5 KPa, the tower top operating temperature is 130~170℃, preferably 140~160℃.

6. The method according to claim 1 or 2, characterized in that, In step (5), the theoretical number of plates in the light-light removal tower is ≥45, the operating pressure at the top of the tower is 1~5 KPa, and the operating temperature at the bottom of the tower is 130~170℃, preferably 150~160℃.

7. The method according to claim 1 or 2, characterized in that, In step (4), the feed inlet of the third separated product is located at the 25th to 35th plate from bottom to top of the heavy removal tower, and the feed inlet of the third separated product is located at 550 to 600 mm, preferably 550 mm, of the height of the light removal tower; preferably, the reflux ratio of the heavy removal tower is 10 to 20.

8. The method according to claim 1 or 2, characterized in that, In step (5), the feed inlet of the fourth separated product is located at the 20th to 30th plate from bottom to top of the light-light removal tower, and the feed inlet of the fourth separated product is located at 450 to 550 mm, preferably 500 mm, of the height of the light-light removal tower; preferably, the reflux ratio of the light-light removal tower is 10 to 30.

9. The method according to claim 1 or 2, characterized in that, In step (4), after the deweighting process, dihexyltriamine is collected at the bottom of the deweighting tower and preferably incinerated.

10. The method according to claim 1 or 2, characterized in that, In step (5), after the removal of light components, aminohexanonitrile and 1,2-cyclohexanediamine are collected from the top of the light component removal tower and preferably incinerated. And / or, in step (5), the purity of the obtained N,N-diethylhexanediamine is ≥99.90%, and the recovery rate is ≥90.0%, preferably ≥95.0%.

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