Method and device for recovering anhydrous triethylamine

Abstract

The invention relates to a method and a device for recycling anhydrous triethylamine. The method comprises the following steps: S1, transferring wastewater containing triethylamine salt into a first reaction kettle; adjusting the pH value of the wastewater through hydrochloric acid; the mass concentration of the triethylamine salt in the wastewater is concentrated through steam heating; s2, after the wastewater is cooled, adjusting the pH value of the wastewater through caustic soda flakes; s3, standing the wastewater to layer the wastewater, and transferring water-containing triethylamine on the upper layer into a second reaction kettle; s4, adding caustic soda flakes into the water-containing triethylamine, stirring, standing, and distilling the water-containing triethylamine on the upper layer; s5, the second fraction at the temperature above the first temperature is the anhydrous triethylamine. According to the method and the device for recycling the triethylamine, the efficient recycling of the triethylamine can be realized, the recycling rate can reach 95 percent or above, and meanwhile, the water content in the recycled triethylamine is ensured to be lower than 0.05 percent.

Description

Technical Field

[0001] The invention relates to the field of chemistry, and in particular to a method and a device for recovering anhydrous triethylamine. Background Art

[0002] In the field of organic synthesis, the reaction of acyl chloride or acyl bromide with hydroxyl or amino group is a key step in the synthesis of esters and amides. This type of reaction usually requires the use of triethylamine as a catalyst to improve the reaction efficiency. However, after the reaction is completed, byproducts such as triethylamine hydrochloride, hydrobromide, and sulfonate will be produced. These byproducts need to be removed by washing in the post-treatment process, thereby producing a large amount of waste water containing triethylamine salts. This treatment method is not only costly, but also pollutes the environment. In order to achieve the goals of economy and environmental protection, the most ideal treatment method is to recycle and treat these byproducts so that they can be reused after reaching the qualified standards. Since acyl chloride or acyl bromide is sensitive to water and easily hydrolyzed, the moisture content must be strictly controlled in the process of recovering triethylamine to ensure the quality of the recyclate.

[0003] In view of this, a method and device for recovering anhydrous triethylamine are urgently needed. Summary of the invention

[0004] The object of the invention is to provide a method and device for recovering anhydrous triethylamine in view of the deficiencies in the prior art.

[0005] To achieve the above object, the technical solution adopted by the present invention is:

[0006] A first aspect of the present invention is to provide a method for reclaiming anhydrous triethylamine, the steps comprising:

[0007] S1, transferring the wastewater containing triethylamine salt to the first reaction kettle, wherein the mass concentration of the triethylamine salt in the wastewater is 15%-20%;

[0008] The pH value of the wastewater is adjusted to 4-6 by hydrochloric acid;

[0009] The mass concentration of the triethylamine salt in the wastewater is adjusted to 40%-50% by steam heating and concentration;

[0010] S2, after the wastewater is cooled to a temperature of 30°C-40°C, the pH value of the wastewater is adjusted to a pH value higher than 10 by using caustic soda flakes;

[0011] S3, allowing the wastewater to stand at a temperature of 55°C ± 5°C to separate into layers, removing the lower aqueous phase, and transferring the upper aqueous triethylamine to a second reaction kettle;

[0012] S4, after adding the flake caustic soda to the aqueous triethylamine, stirring for at least 1 hour, and standing for at least 24 hours, removing the liquid caustic soda on the lower layer, and distilling the aqueous triethylamine on the upper layer;

[0013] S5, transferring the first fraction below the first temperature to a receiving tank;

[0014] The second fraction above the first temperature is anhydrous triethylamine, and the water content of the anhydrous triethylamine is less than 0.05%.

[0015] Preferably, the triethylamine salt is triethylamine hydrochloride and / or triethylamine hydrobromide.

[0016] Preferably, in step S4, the water content of the liquid caustic soda in the lower layer is 55%-65%.

[0017] Preferably, the liquid caustic soda in the lower layer in step S4 is transferred to the first reaction kettle in step S2 to adjust the pH value of the wastewater together with the caustic soda flakes.

[0018] Preferably, the first fraction in the receiving tank in step S5 and the aqueous triethylamine in the upper layer in step S3 are transferred to the second reaction kettle in step S4, and then the caustic soda flakes are added and stirred for at least 1 hour, and then allowed to stand for at least 24 hours.

[0019] Preferably, the first temperature is higher than 80°C.

[0020] Preferably, the method further comprises: further drying the second fraction by a drying tower.

[0021] A second aspect of the present invention is to provide a device for reclaiming anhydrous triethylamine, which is applicable to the aforementioned method, comprising:

[0022] The first reactor;

[0023] A first receiving tank, wherein the feed port of the first receiving tank is connected to the first discharge port pipeline of the first reactor, and the first receiving tank is used to receive the liquid evaporated when the waste water steam in the first reactor is heated and concentrated;

[0024] A second reactor, wherein the feed port of the second reactor is connected to the second discharge port of the first reactor through a pipeline;

[0025] a second receiving tank, the second receiving tank being connected to the first discharge port pipeline of the second reactor, and the second receiving tank being used to receive the first fraction; and

[0026] A third receiving tank is connected to the second discharge port pipeline of the second reactor, and is used to receive the second fraction.

[0027] Preferably, it further comprises: a drying tower, which is arranged on the connecting pipeline between the second reaction kettle and the third receiving tank.

[0028] Preferably, it also includes:

[0029] A first condenser, which is disposed on a connecting pipeline between the first reaction kettle and the first receiving tank; and

[0030] The second condenser is arranged on the connecting pipeline between the second reactor and the second receiving tank or the third receiving tank.

[0031] The present invention adopts the above technical solution, and has the following technical effects compared with the prior art:

[0032] The method and device for recovering triethylamine of the present invention can realize the efficient recovery of triethylamine, and the recovery rate can reach more than 95%, and at the same time ensure that the water content in the recovered triethylamine is less than 0.05%; through the method of the present invention, the recovered triethylamine has extremely high purity and can be directly used for esterification or amidation synthesis reaction, thereby significantly reducing the production cost. In addition, the wastewater generated in the recovery process mainly contains inorganic salts, which greatly reduces the difficulty of treating the wastewater, making the entire process more environmentally friendly and green. The present invention not only improves the recycling rate of resources, but also effectively reduces the discharge of chemical wastes, which is of great significance to environmental protection and sustainable development. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a schematic structural diagram of the device of triethylamine in the present invention;

[0034] The reference numerals include:

[0035] The first reactor 1; the first receiving tank 2; the second reactor 3; the second receiving tank 4; the third receiving tank 5; the drying tower 6; the first condenser 7; and the second condenser 8. DETAILED DESCRIPTION

[0036] The specific embodiments of the present invention will be described in detail below.

[0037] Unless otherwise defined, technical or scientific terms used in the claims and the specification shall have the common meanings understood by persons having ordinary skills in the technical field to which the present invention belongs.

[0038] The words "include" or similar words used in the patent application specification and claims of the present invention mean that the items appearing before "include" include the items listed after "include" or their equivalents, and do not exclude other items.

[0039] The numerical values ​​mentioned in the present invention include all numerical values ​​that increase from low to high by one unit, assuming that there are at least two units between any lower value and the higher value. For example, if a component or a physical quantity is said to be from 1 to 100, 10 to 90 is more preferred, and 20 to 80 is the most preferred, it is intended to express that values ​​such as 5 to 95, 14 to 76, 23 to 67, 32 to 58, 41 to 49 are clearly listed in this specification; for values ​​less than 1, 0.0001, 0.001, 0.01 or 0.1 are considered to be more suitable as a unit. The above examples are for illustrative purposes only. In fact, all numerical combinations between the lowest value and the highest value listed are deemed to be clearly listed in this specification in a similar manner.

[0040] The "water content" mentioned in the present invention refers to the mass percentage of water in the substance unless otherwise specified.

[0041] Example 1

[0042] like Figure 1 As shown, this embodiment provides a device for recovering anhydrous triethylamine, comprising:

[0043] The first reactor 1;

[0044] A first receiving tank 2, wherein the feed port of the first receiving tank 2 is connected to the first discharge port pipeline of the first reactor 1, and the first receiving tank 2 is used to receive the liquid evaporated when the waste water vapor in the first reactor 1 is heated and concentrated;

[0045] A second reactor 3, wherein the feed port of the second reactor 3 is connected to the second discharge port pipeline of the first reactor 1;

[0046] A second receiving tank 4, the second receiving tank 4 is connected to the first discharge port pipeline of the second reactor 3, and the second receiving tank 4 is used to receive the first fraction;

[0047] A third receiving tank 5, wherein the third receiving tank 5 is connected to the second discharge port pipeline of the second reactor 3, and the third receiving tank 5 is used to receive the second fraction; and

[0048] A drying tower 6 is provided on a connecting pipeline between the second reaction kettle 3 and the third receiving tank 5 .

[0049] In a preferred embodiment, it also includes:

[0050] A first condenser 7, which is disposed on a connecting pipeline between the first reaction kettle 1 and the first receiving tank 2; and

[0051] The second condenser 8 is arranged on the connecting pipeline between the second reactor 3 and the second receiving tank 4 or the third receiving tank 5 .

[0052] Example 2

[0053] This embodiment provides a method for recovering anhydrous triethylamine, using the device shown in Example 1, the steps comprising:

[0054] S1, transferring 2t of wastewater containing triethylamine hydrochloride to the first reaction kettle 1, wherein the mass concentration of triethylamine hydrochloride in the wastewater is 20%;

[0055] The pH value of the wastewater is adjusted to 4-6 by hydrochloric acid;

[0056] The mass concentration of triethylamine hydrochloride in the wastewater is adjusted to 40%-50% by steam heating and concentration. The evaporated material in the process is condensed by the first condenser 7 and then enters the first receiving tank 2;

[0057] S2, after the wastewater is cooled to a temperature of 30°C-40°C, the pH value of the wastewater is adjusted to a pH value higher than 10 by using caustic soda flakes;

[0058] Among them, caustic soda flakes can reduce the amount of water brought in and reduce the amount of wastewater generated. The pH value of the wastewater is adjusted to a value higher than 10 in order to fully free triethylamine from its salt form.

[0059] S3, allowing the wastewater to stand at a temperature of 55°C ± 5°C to separate into layers, removing the lower aqueous phase (sodium chloride aqueous solution), and transferring the upper layer of triethylamine containing 4% to 5% of water to the second reaction kettle 3;

[0060] S4, after adding 25kg of the flake caustic soda into the second reactor 3, stirring for at least 1 hour, and standing for at least 24 hours, the liquid caustic soda with a moisture content of 55%-65% in the lower layer is removed, and the aqueous triethylamine with a moisture content of 0.3%-0.5% in the upper layer is distilled;

[0061] Among them, compared with sodium sulfate (sodium sulphate), caustic soda flakes show significant advantages in the drying process. Specifically, caustic soda flakes can dry the water content of triethylamine to less than 0.5%, while sodium sulfate can only dry the water content of triethylamine to 2%-4%. The stirring time and the standing time can ensure that the triethylamine is fully dried.

[0062] S5, the first fraction below 85°C has a content of about 10% and a moisture content of 2%-3%, and enters the second receiving tank 4 after being condensed by the second condenser 8;

[0063] The second fraction above 85° C. is anhydrous triethylamine with a water content of less than 0.05%, which is condensed in the second condenser 8 and further dried in the drying tower 6 before entering the third receiving tank 5 .

[0064] In a preferred embodiment, the liquid caustic soda with a water content of 55%-65% in the lower layer in step S4 is transferred to the first reaction kettle 1 in step S2 to adjust the pH of the wastewater together with the caustic soda flakes;

[0065] Among them, although the liquid caustic soda with a water content of XX will bring in water, it can avoid the generation of solid waste, realize the recycling of resources, and reduce the environmental burden. In a preferred embodiment, the first fraction in the second receiving tank 4 in the step S5 and the aqueous triethylamine with a water content of 4%-5% in the upper layer in the step S3 are transferred to the second reactor 3 in the step S4, and then the caustic soda flakes are added and stirred for at least 1 hour, and then left to stand for at least 24 hours.

[0066] In a preferred embodiment, the filler in the drying tower 6 is a molecular sieve, which can be reused after drying.

[0067] Example 3

[0068] This embodiment provides a method for recovering anhydrous triethylamine, using the device shown in Example 1, the steps comprising:

[0069] S1, transferring 2t of wastewater containing triethylamine hydrobromide to the first reaction kettle 1, wherein the mass concentration of triethylamine hydrobromide in the wastewater is 15%;

[0070] The pH value of the wastewater is adjusted to 4-6 by hydrochloric acid;

[0071] The mass concentration of triethylamine hydrobromide in the wastewater is adjusted to 40%-50% by steam heating and concentration. The evaporated material in the process is condensed by the first condenser 7 and then enters the first receiving tank 2;

[0072] S2, after the wastewater is cooled to a temperature of 30°C-40°C, the pH value of the wastewater is adjusted to a pH value higher than 10 by using caustic soda flakes;

[0073] Among them, caustic soda flakes can reduce the amount of water brought in and reduce the amount of wastewater generated. The pH value of the wastewater is adjusted to a value higher than 10 in order to fully free triethylamine from its salt form.

[0074] S3, allowing the wastewater to stand at a temperature of 55°C ± 5°C to separate into layers, removing the lower aqueous phase (sodium bromide aqueous solution), and transferring the upper layer of triethylamine containing 4% to 5% of water to the second reaction kettle 3;

[0075] S4, after adding 25kg of the flake caustic soda into the second reactor 3, stirring for at least 1 hour, and standing for at least 24 hours, the liquid caustic soda with a moisture content of 55%-65% in the lower layer is removed, and the aqueous triethylamine with a moisture content of 0.3%-0.5% in the upper layer is distilled;

[0076] Among them, compared with sodium sulfate (sodium sulphate), caustic soda flakes show significant advantages in the drying process. Specifically, caustic soda flakes can dry the water content of triethylamine to less than 0.5%, while sodium sulfate can only dry the water content of triethylamine to 2%-4%. The stirring time and the standing time can ensure that the triethylamine is fully dried.

[0077] S5, the content of the first fraction below 87°C is about 10%, the water content is 2%-3%, and it enters the second receiving tank 4 after being condensed by the second condenser 8;

[0078] The second fraction above 87° C. is anhydrous triethylamine with a water content of less than 0.05%, which is condensed in the second condenser 8 and further dried in the drying tower 6 before entering the third receiving tank 5 .

[0079] In a preferred embodiment, the liquid caustic soda with a water content of 55%-65% in the lower layer in step S4 is transferred to the first reaction kettle 1 in step S2 to adjust the pH of the wastewater together with the caustic soda flakes;

[0080] Among them, although the liquid caustic soda with a water content of XX will bring in water, it can avoid the generation of solid waste, realize the recycling of resources, and reduce the environmental burden. In a preferred embodiment, the first fraction in the second receiving tank 4 in the step S5 and the aqueous triethylamine with a water content of 4%-5% in the upper layer in the step S3 are transferred to the second reactor 3 in the step S4, and then the caustic soda flakes are added and stirred for at least 1 hour, and then left to stand for at least 24 hours.

[0081] In a preferred embodiment, the filler in the drying tower 6 is a molecular sieve, which can be reused after drying.

[0082] In summary, the method and device for recovering triethylamine of the present invention can realize the efficient recovery of triethylamine, and the recovery rate can reach more than 95%, while ensuring that the water content in the recovered triethylamine is less than 0.05%; through the method of the present invention, the triethylamine recovered has extremely high purity and can be directly used for esterification or amidation synthesis reaction, thereby significantly reducing the production cost. In addition, the wastewater generated in the recovery process mainly contains inorganic salts, which greatly reduces the difficulty of wastewater treatment and makes the entire process more environmentally friendly and green. The present invention not only improves the recycling rate of resources, but also effectively reduces the discharge of chemical wastes, which is of great significance to environmental protection and sustainable development.

[0083] The above description is only a preferred embodiment of the present invention, and does not limit the implementation mode and protection scope of the present invention. For those skilled in the art, it should be aware that all solutions obtained by equivalent substitutions and obvious changes made using the description and illustrations of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for recovering anhydrous triethylamine, characterized in that the steps include: S1, transferring the wastewater containing triethylamine salt to the first reaction kettle, wherein the mass concentration of the triethylamine salt in the wastewater is 15%-20%; The pH value of the wastewater is adjusted to 4-6 by hydrochloric acid; The mass concentration of the triethylamine salt in the wastewater is adjusted to 40%-50% by steam heating and concentration; S2, after the wastewater is cooled to a temperature of 30°C-40°C, the pH value of the wastewater is adjusted to a pH value higher than 10 by using caustic soda flakes; S3, allowing the wastewater to stand at a temperature of 55°C ± 5°C to separate into layers, removing the lower aqueous phase, and transferring the upper aqueous triethylamine to a second reaction kettle; S4, after adding the flake caustic soda to the aqueous triethylamine, stirring for at least 1 hour, and standing for at least 24 hours, removing the liquid caustic soda on the lower layer, and distilling the aqueous triethylamine on the upper layer; S5, transferring the first fraction below the first temperature to a receiving tank; The second fraction above the first temperature is anhydrous triethylamine, and the water content of the anhydrous triethylamine is less than 0.05%.

2. The method according to claim 1, characterized in that The triethylamine salt is triethylamine hydrochloride and / or triethylamine hydrobromide.

3. The method according to claim 1, characterized in that In step S4, the water content of the liquid caustic soda in the lower layer is 55%-65%.

4. The method according to claim 1 or 3, characterized in that: The liquid caustic soda in the lower layer in step S4 is transferred to the first reaction kettle in step S2 to adjust the pH value of the wastewater together with the caustic soda flakes.

5. The method according to claim 1, characterized in that The first fraction in the receiving tank in step S5 and the aqueous triethylamine in the upper layer in step S3 are transferred to the second reaction kettle in step S4, and then the caustic soda flakes are added, stirred for at least 1 hour, and allowed to stand for at least 24 hours.

6. The method according to claim 1, characterized in that The first temperature is higher than 80°C.

7. The method according to claim 1, characterized in that Also includes: The second fraction is further dried by a drying tower.

8. A device for recovering anhydrous triethylamine, suitable for the method according to any one of claims 1 to 7, characterized in that: include: A first reaction kettle (1); A first receiving tank (2), wherein the feed port of the first receiving tank (2) is connected to the first discharge port pipeline of the first reactor (1), and the first receiving tank (2) is used to receive the liquid evaporated when the waste water vapor in the first reactor (1) is heated and concentrated; A second reaction kettle (3), wherein the feed port of the second reaction kettle (3) is connected to the second discharge port pipeline of the first reaction kettle (1); a second receiving tank (4), the second receiving tank (4) being connected to the first discharge port pipeline of the second reaction kettle (3), and the second receiving tank (4) being used to receive the first fraction; and A third receiving tank (5), the third receiving tank (5) is connected to the second discharge port pipeline of the second reaction kettle (3), and the third receiving tank (5) is used to receive the second fraction.

9. The device according to claim 8, characterized in that Also includes: A drying tower (6), wherein the drying tower (6) is arranged on a connecting pipeline between the second reaction kettle (3) and the third receiving tank (5).

10. The device according to claim 8, characterized in that Also includes: A first condenser (7), the first condenser (7) being arranged on a connecting pipeline between the first reaction kettle (1) and the first receiving tank (2); as well as A second condenser (8), the second condenser (8) is arranged on the connecting pipeline between the second reaction kettle (3) and the second receiving tank (4) or the third receiving tank (5).

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