A system and method for recovering triethylamine in a vinylene carbonate production process

Abstract

The application discloses a system and method for recovering triethylamine in a vinylene carbonate production process, which comprises a dissolving kettle, a filtering device, a first resin tank, a second resin tank, a neutralization and separation device, a rectifying device, a triethylamine receiving tank, an anhydrous methanol high tank, an eluent receiving tank and a waste water receiving tank; the dissolving kettle is connected with the filtering device and the second resin tank in sequence; two pipelines are arranged at the bottom of the second resin tank and are connected with the neutralization and separation device and the eluent receiving tank respectively; two pipelines are arranged at the bottom of the neutralization and separation device and are connected with the waste water receiving tank and the rectifying device respectively; the rectifying device is connected with the triethylamine receiving tank; and the top of the first resin tank is connected with the anhydrous methanol high tank. After triethylamine hydrochloride is dissolved and filtered, macroporous resin is used to adsorb the impurities contained in the filtrate, and then triethylamine hydrochloride aqueous solution is obtained through the adsorption treatment; after the triethylamine hydrochloride aqueous solution is neutralized and separated by using sodium hydroxide, triethylamine crude product is obtained; and then, triethylamine is obtained through rectification; the recovery rate of the triethylamine is as high as 90%, and the purity is higher than 99.9%.

Description

Technical Field

[0001] This invention belongs to the field of triethylamine recovery technology, specifically relating to a system and method for recovering triethylamine in the production process of vinylene carbonate. Background Technology

[0002] Currently, the industrial production process for vinylene carbonate uses BHT as a polymerization inhibitor, dimethyl carbonate as a solvent, and triethylamine and chloroethylene carbonate as raw materials. The specific equation is as follows:

[0003]

[0004] Triethylamine hydrochloride is a byproduct of the above reaction. The recovery of triethylamine from triethylamine hydrochloride is achieved by neutralizing it with sodium hydroxide flakes in an aqueous solution of triethylamine hydrochloride, as shown in the following equation:

[0005]

[0006] Due to the low purity of chloroethylene carbonate used in the production of vinylene carbonate, the resulting triethylamine hydrochloride contains approximately 20% impurities, including various polymers produced during the polymerization of vinylene carbonate and acetylene carbonate, as well as ethylene carbonate, vinylene carbonate, chloroethylene carbonate, dichloroethylene carbonate, and pigments generated during the production process. Traditional processes for dissolving, neutralizing, separating, and distilling the triethylamine hydrochloride yields a high level of triethylamine impurities. The purity of triethylamine obtained after separation is only 70%–80%, and even after distillation, the highest purity is only 98%, with a yield of 70%–75%. This high impurity content makes triethylamine recovery and reuse very difficult. Currently, excessively high triethylamine recovery and reuse rates in the vinylene carbonate production process can lead to side reactions, generating a large amount of impurities and reducing the yield. Therefore, most production processes can only achieve partial or no recovery and reuse. Summary of the Invention

[0007] The purpose of this invention is to provide a system and method for recovering triethylamine in the production process of vinylene carbonate.

[0008] To achieve the above objectives, the following technical solution is adopted:

[0009] A system for recovering triethylamine in a vinylene carbonate production process includes a dissolving vessel, a filtration device, a first resin tank, a second resin tank, a neutralization and separation device, a distillation device, a triethylamine receiving tank, an anhydrous methanol high-level tank, an eluent receiving tank, and a wastewater receiving tank. The dissolving vessel is sequentially connected to the filtration device and the second resin tank. The bottom of the second resin tank has two pipelines that connect to the neutralization and separation device and the eluent receiving tank, respectively. The bottom of the neutralization and separation device also has two pipelines that connect to the wastewater receiving tank and the distillation device, respectively. The distillation device is connected to the triethylamine receiving tank. The top of the first resin tank is connected to the anhydrous methanol high-level tank.

[0010] A method for recovering triethylamine from the vinylene carbonate production process using the above-described system includes the following steps:

[0011] 1) The macroporous resin is pre-loaded into the first resin tank and the second resin tank. The triethylamine hydrochloride, a byproduct of the production of vinylene carbonate, is added to the dissolving vessel and dissolved in water. After the triethylamine hydrochloride is fully dissolved, it is filtered by the filtration equipment. The filtrate enters the first resin tank for primary adsorption and then continues to enter the second resin tank for secondary adsorption. After the secondary adsorption is completed, the triethylamine hydrochloride enters the neutralization and separation equipment, where caustic soda is added for neutralization. After neutralization, the upper liquid enters the distillation equipment, and the finished triethylamine is sent to the triethylamine receiving tank. The lower liquid enters the wastewater receiving tank.

[0012] 2) The anhydrous methanol in the high-level anhydrous methanol tank enters the first resin tank for primary elution, and then continues to enter the second resin tank for secondary elution. The secondary eluent enters the eluent receiving tank.

[0013] Furthermore, the macroporous resin is XDA-1, XDA-2, XDA-6 or XDA-8, and the filling volume accounts for 65%-85% of the tank volume. The ratio of macroporous resin dosage to the mass of the processed material is 1:2.5-3.0. The triethylamine hydrochloride aqueous solution after filtration contains 2%-3% impurities.

[0014] Furthermore, the ratio of water used to dissolve triethylamine hydrochloride to the mass of triethylamine hydrochloride is 0.8-1.1, and the dissolution temperature is 25-35℃.

[0015] Furthermore, the neutralization temperature is 30-45℃, and the pH after neutralization is 12-14.

[0016] Furthermore, the flow rate of anhydrous methanol during elution is 50-150 kg / h.

[0017] Furthermore, the temperature at the bottom of the distillation column is 91-92℃, the temperature at the top of the column is 89-90℃, and the pressure is atmospheric pressure.

[0018] The beneficial effects of this invention are as follows:

[0019] Compared to traditional processes, this invention adds filtration, macroporous resin adsorption for impurity removal, and atmospheric distillation processes, increasing the yield of recovered triethylamine to 90% and the purity to 99.9%. The complete reuse of triethylamine will not cause side reactions during the production of vinylene carbonate that lead to a decrease in yield. Attached Figure Description

[0020] Figure 1 This is a process flow diagram of the present invention;

[0021] In the diagram: 1. Dissolving vessel; 2. Filtration equipment; 3. First resin tank; 4. Second resin tank; 5. Neutralization and separation equipment; 6. Distillation equipment; 7. Triethylamine receiving tank; 8. Anhydrous methanol high-level tank; 9. Eluent receiving tank; 10. Wastewater receiving tank. Detailed implementation method.

[0022] The present invention will be further described below with reference to the accompanying drawings and embodiments, but the scope of protection of the present invention is not limited thereto.

[0023] Reference Figure 1 A system for recovering triethylamine from a vinylene carbonate production process includes a dissolving vessel 1, a filtration device 2, a first resin tank 3, a second resin tank 4, a neutralization and separation device 5, a distillation device 6, a triethylamine receiving tank 7, an anhydrous methanol high-level tank 8, an eluent receiving tank 9, and a wastewater receiving tank 10. The dissolving vessel 1 is connected in sequence to the filtration device 2 and the second resin tank 4. The bottom of the second resin tank 4 is provided with two pipes, which are respectively connected to the neutralization and separation device 5 and the eluent receiving tank 9. The bottom of the neutralization and separation device 5 is provided with two pipes, which are respectively connected to the wastewater receiving tank 10 and the distillation device 6. The distillation device 6 is connected to the triethylamine receiving tank 7. The top of the first resin tank 3 is connected to the anhydrous methanol high-level tank 8.

[0024] Example 1

[0025] Macroporous resin, XDA-1, was pre-loaded into the first resin tank 3 and the second resin tank 4, with a loading volume of 2.0 m³ in each tank. 2000 kg of water was added to the dissolving vessel 1, and the temperature was controlled at 25°C. 2000 kg of crude triethylamine hydrochloride (approximately 80% purity) obtained from vinylene carbonate production was added to the dissolving vessel 1 and dissolved for 4 hours. After the triethylamine hydrochloride was fully dissolved, it was filtered through the filtration device 2, yielding 3700 kg of filtrate. The filtrate was then fed into the first resin tank 3 for primary adsorption, and then continued into the second resin tank 4 for secondary adsorption. The flow rate was controlled at 150 kg / h. The batch processing capacity was... The volume of the filtrate for dissolving triethylamine hydrochloride is calculated. When adsorbed organic impurities other than triethylamine hydrochloride are detected in the effluent from the discharge pipe of the second resin tank 4, it is considered that the adsorption is saturated. The secondary adsorbent is then passed into the neutralization and separation equipment 5, with the temperature controlled at 45℃. 467 kg of caustic soda flakes are slowly added to the neutralization and separation equipment 5. When neutralization is complete, the pH value is 13. The upper liquid is triethylamine, and the lower liquid is sodium chloride aqueous solution. This liquid enters the wastewater collection tank 10, yielding 1070 kg of triethylamine. This triethylamine is then fed into the distillation equipment 6 for atmospheric distillation. The bottom temperature of the distillation column is 91.5℃, and the top temperature is 89.5℃. The distillation yields 1058.6 kg of the finished product, triethylamine.

[0026] Anhydrous methanol is introduced from the high-level anhydrous methanol tank 8 into the first resin tank 3 for primary elution. The primary eluent continues to enter the second resin tank 4 for secondary elution. The eluent flow rate is 70 kg / h. The secondary eluent enters the eluent receiving tank 9. When no adsorbed organic impurities other than methanol can be detected in the secondary eluent, the elution and regeneration are completed. The regenerated macroporous adsorption resin is recycled.

[0027] Conclusion: 1058.6 kg of triethylamine was obtained with a purity of 99.9% and a yield of 90%.

[0028] Example 2

[0029] Macroporous resin, XDA-2, was pre-loaded into the first resin tank 3 and the second resin tank 4, with a loading volume of 2 m³ in each tank. 1800 kg of water was added to the dissolving vessel 1, and the temperature was controlled at 35°C. 2000 kg of crude triethylamine hydrochloride (approximately 80% purity) obtained from vinylene carbonate production was added to the dissolving vessel 1 and dissolved for 4 hours. After the triethylamine hydrochloride was fully dissolved, it was filtered through the filter device 2, yielding 3500 kg of filtrate. The filtrate then entered the first resin tank 3 for primary adsorption, and then continued into the second resin tank 4 for secondary adsorption, with the flow rate controlled at 100 kg / h. The processing volume is the amount of triethylamine hydrochloride dissolution filtrate. When impurities other than triethylamine hydrochloride are detected in the effluent from the discharge pipe of the second resin tank 4, it is considered that the adsorption is saturated. The secondary adsorbent is passed into the neutralization and separation equipment 5, and the temperature is controlled at 30℃. 466 kg of caustic soda flakes are slowly added to the neutralization and separation equipment 5. When the neutralization is completed, the pH value is 13. The upper liquid is triethylamine, and the lower liquid is sodium chloride aqueous solution, which enters the wastewater collection tank 10, yielding 1085 kg of triethylamine. This triethylamine is then fed into the distillation equipment 6 for atmospheric distillation. The bottom temperature of the column is 91℃, and the top temperature of the column is 89℃. The product obtained from the distillation is 1060.5 kg of triethylamine.

[0030] Anhydrous methanol is introduced from the high-level anhydrous methanol tank 8 into the first resin tank 3 for primary elution. The primary eluent continues to enter the second resin tank 4 for secondary elution. The eluent flow rate is 80 kg / h. The secondary eluent enters the eluent receiving tank 9. When no adsorbed organic impurities other than methanol can be detected in the secondary eluent, the elution and regeneration are completed, and the regenerated macroporous adsorption resin is recycled.

[0031] Conclusion: 1060.5 kg of triethylamine was obtained with a purity of 99.9% and a yield of 90.1%.

[0032] Example 3

[0033] Macroporous resin, XDA-6, was pre-loaded into the first resin tank 3 and the second resin tank 4, with a loading volume of 2 m³ in each tank. 1900 kg of water was added to the dissolving vessel 1, and the temperature was controlled at 35°C. 2000 kg of crude triethylamine hydrochloride (approximately 80% purity) obtained from vinylene carbonate production was added to the dissolving vessel 1 and dissolved for 4 hours. After the triethylamine hydrochloride was fully dissolved, it was filtered through the filtration device 2, yielding 3580 kg of filtrate. The filtrate then entered the first resin tank 3 for primary adsorption, and then continued into the second resin tank 4 for secondary adsorption. The flow rate was controlled at 200 kg / h. The batch processing capacity was... The volume of the filtrate for dissolving triethylamine hydrochloride is calculated. When impurities other than triethylamine hydrochloride are detected in the effluent from the discharge pipe of the second resin tank 4, it is considered that the adsorption is saturated. The secondary adsorbent is then introduced into the neutralization and separation equipment 5, with the temperature controlled at 30℃. 468 kg of caustic soda flakes are slowly added to the neutralization and separation equipment 5. When neutralization is complete, the pH value is 12. The upper liquid is triethylamine, and the lower liquid is sodium chloride aqueous solution, which enters the wastewater collection tank 10, yielding 1075.2 kg of triethylamine. This triethylamine is then introduced into the distillation equipment 6 through pipe 17. Atmospheric pressure distillation is performed with the bottom temperature at 92℃ and the top temperature at 90℃. The distillation yields 1064.5 kg of the finished product, triethylamine.

[0034] Anhydrous methanol is introduced from the high-level anhydrous methanol tank 8 into the first resin tank 3 for primary elution. The primary eluent continues to enter the second resin tank 4 for secondary elution. The eluent flow rate is 90 kg / h. The secondary eluent enters the eluent receiving tank 9. When no adsorbed organic impurities other than methanol can be detected in the secondary eluent, the elution and regeneration are completed, and the regenerated macroporous adsorption resin is recycled.

[0035] Conclusion: 1064.5 kg of triethylamine was obtained with a purity of 99.9% and a yield of 90.5%.

[0036] Example 4

[0037] Macroporous resin, XDA-8, was pre-loaded into the first resin tank 3 and the second resin tank 4, with a loading volume of 2.0 m³ in each tank. 2000 kg of water was added to the dissolving vessel 1, and the temperature was controlled at 25°C. 2000 kg of crude triethylamine hydrochloride (approximately 80% purity) obtained from the production of vinylene carbonate was added to the dissolving vessel 1 and dissolved for 4 hours. After the triethylamine hydrochloride was fully dissolved, it was filtered through the filter device 2, yielding 3700 kg of filtrate. The filtrate was then fed into the first resin tank 3 for primary adsorption, and then continued into the second resin tank 4 for secondary adsorption, with the flow rate controlled at 200 kg / h. The processing volume is the amount of triethylamine hydrochloride dissolution filtrate. When impurities other than triethylamine hydrochloride are detected in the effluent from the discharge pipe of the second resin tank 4, it is considered that the adsorption is saturated. The secondary adsorbent is then passed into the neutralization and separation equipment 5, with the temperature controlled at 30℃. 467 kg of caustic soda flakes are slowly added to the neutralization and separation equipment 5. When neutralization is complete, the pH value is 12. The upper liquid is triethylamine, and the lower liquid is sodium chloride aqueous solution, which enters the wastewater collection tank 10, yielding 1085.2 kg of triethylamine. This triethylamine is then fed into the distillation equipment 6 for atmospheric distillation. The bottom temperature of the column is 92℃, and the top temperature is 90℃. The distillation yields 1068.7 kg of the finished product, triethylamine.

[0038] Anhydrous methanol is introduced from the anhydrous methanol high-level tank 8 into the first resin tank 3 for primary elution. The primary eluent continues to enter the second resin tank 4 for secondary elution. The eluent flow rate is 100 kg / h. The secondary eluent enters the eluent receiving tank 9. When no adsorbed organic impurities other than methanol can be detected in the secondary eluent, the elution and regeneration are completed, and the regenerated macroporous adsorption resin is recycled.

[0039] Conclusion: 1068.7 kg of triethylamine was obtained with a purity of 99.9% and a yield of 90.9%.

Claims

1. A system for recovering triethylamine in a vinylene carbonate production process, characterized in that, The system includes a dissolving vessel (1), a filtration device (2), a first resin tank (3), a second resin tank (4), a neutralization and separation device (5), a distillation device (6), a triethylamine receiving tank (7), an anhydrous methanol high-level tank (8), an eluent receiving tank (9), and a wastewater receiving tank (10). The dissolving vessel (1) is connected in sequence to the filtration device (2) and the second resin tank (4). The bottom of the second resin tank (4) is equipped with two pipes, which are respectively connected to the neutralization and separation device (5) and the eluent receiving tank (9). 5) has two pipelines at the bottom, which are connected to the wastewater receiving tank (10) and the distillation equipment (6) respectively. The distillation equipment (6) is connected to the triethylamine receiving tank (7). The top of the first resin tank (3) is connected to the anhydrous methanol high-level tank (8). The first resin tank (3) and the second resin tank (4) are filled with macroporous resin, which is XDA-1, XDA-2, XDA-6 or XDA-8. The filling volume accounts for 65%-85% of the tank volume. The ratio of resin dosage to the mass of the treated material is 1:2.5-3.

0.

2. A method for recovering triethylamine using the system as described in claim 1, characterized in that, Includes the following steps: 1) The macroporous resin is preloaded into the first resin tank (3) and the second resin tank (4). The by-product of the production of vinylene carbonate, triethylamine hydrochloride, is added to the dissolving vessel (1) and dissolved in water. After the triethylamine hydrochloride is fully dissolved, it is filtered in the filtration device (2). The filtrate enters the first resin tank (3) for primary adsorption and then continues to enter the second resin tank (4) for secondary adsorption. After the secondary adsorption is completed, the triethylamine hydrochloride enters the neutralization and separation device (5). Sodium hydroxide is added for neutralization. After neutralization is completed, the upper liquid enters the distillation device (6). The finished triethylamine is distilled and sent to the triethylamine receiving tank (7). The lower liquid enters the wastewater receiving tank (10). 2) The anhydrous methanol in the high-level anhydrous methanol tank (8) enters the first resin tank (3) for primary elution, and then continues to enter the second resin tank (4) for secondary elution. The secondary eluent enters the eluent receiving tank (9).

3. The method as described in claim 2, characterized in that, The ratio of water used to triethylamine hydrochloride by mass is 0.8-1.1, and the dissolution temperature is 25-35℃.

4. The method as described in claim 2, characterized in that, The neutralization temperature is 30-45℃, and the pH after neutralization is 12-14.

5. The method as described in claim 2, characterized in that, The temperature at the bottom of the distillation column is 91-92℃, the temperature at the top of the column is 89-90℃, and the pressure is atmospheric pressure.

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