Method for recovering triethylamine from triethylamine hydrochloride waste residue generated in vinylene carbonate production process
The impurities in triethylamine hydrochloride waste residue were removed by heat treatment and organic polar solvent dissolution, and ammonia gas was used for reaction, which solved the problems of difficult recycling, high cost and organic wastewater in the prior art, and achieved efficient and low-cost triethylamine recovery.
Patent Information
- Application Number
- CN202411751297.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-02
- Publication Date
- 2025-03-07
AI Technical Summary
In the prior art, when triethylamine is recovered from triethylamine hydrochloride waste slag produced by the vinyl carbonate production process, impurities have problems that are difficult to recover, have low recovery rate, are high cost, and produce difficult-to-treat organic wastewater.
The impurities in the triethylamine hydrochloride waste residue were removed by heat treatment and organic polar solvent dissolution, and then the reaction was carried out by ammonia gas to produce triethylamine and ammonium chloride, and high-purity triethylamine was separated by filtration and distillation.
The recovery rate and purity of triethylamine are improved, the recovery cost is reduced, and the production of organic wastewater is avoided, and the organic polar solvents that are used for anhydrous recycling are realized.
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Abstract
Description
Technical Field
[0001] The invention relates to the technical field of triethylamine recovery, in particular to a method for recovering triethylamine from triethylamine hydrochloride waste residue generated in a vinylene carbonate production process. Background Art
[0002] Vinyl carbonate is an important lithium battery electrolyte additive. With the rapid development of new energy vehicles and power battery industries in recent years, the demand for vinyl carbonate has continued to grow.
[0003] The main process of vinylene carbonate in the current industry is to use chloroethylene carbonate as raw material, triethylamine as dechlorination reagent, and dimethyl carbonate as reaction solvent for production. The specific reaction equation is as follows:
[0004]
[0005] A large amount of dark brown triethylamine hydrochloride is produced in the production process of vinylene carbonate, which contains 20-30wt% of organic matter. If these triethylamine hydrochloride waste residues are directly treated as "production waste solids", it will bring great pressure to environmental protection and also lead to higher costs for the production of vinylene carbonate.
[0006] Currently, the main method for recovering triethylamine from triethylamine hydrochloride is to convert triethylamine hydrochloride into triethylamine by reacting triethylamine hydrochloride with liquid alkali, obtain crude triethylamine by liquid separation, and then purify the crude triethylamine to obtain triethylamine.
[0007] Since the raw material of vinylene carbonate for industrial production of vinylene carbonate has low purity, impurities such as oligomers or polymers of vinylene carbonate, vinyl carbonate, dichloroethylene carbonate and pigments generated during the production process appear during the reaction. These impurities, as well as the reaction solvent and dimethyl carbonate added in the subsequent washing of triethylamine hydrochloride, will adhere to the surface of triethylamine hydrochloride. At the same time, these impurities will also react with alkali solution, making it more difficult to recover and separate triethylamine, reducing the recovery rate of triethylamine, and the consumption of liquid alkali is large, resulting in high cost of recovering triethylamine.
[0008] In view of this situation, some processes have been partially improved. For example, Chinese invention patent CN114478263A discloses a method for recovering triethylamine in the production of vinylene carbonate. Before using liquid caustic soda to react with triethylamine hydrochloride, triethylamine hydrochloride is washed twice with an organic polar solvent to wash away some organic impurities adhering to the surface. Although this patent reduces the impact of organic impurities adhering to the surface of triethylamine hydrochloride on recovery to a certain extent, it adds consumption of organic polar solvents, and the washing solvent also enters the system as a new organic impurity. In addition, this patent uses sodium hydroxide solution and triethylamine hydrochloride waste residue to react, which will produce a large amount of brown-black sodium chloride wastewater containing organic matter. At present, there is still no effective treatment measure for this type of wastewater in the world.
[0009] Ren Fujian, Liu Yingli and others mentioned a method of recovering triethylamine with ammonia water in "Recovery of Triethylamine with Ammonia Method" (Pesticide Journal, Vol. 45, No. 4, April 2006, pp. 251-252). However, this method is used to treat triethylamine hydrochloride waste residues produced in the production process of vinylene carbonate, which will produce a large amount of brown-black ammonium chloride waste brine containing organic matter, which is difficult to treat and cannot be used as a fertilizer.
[0010] Patent CN118851914A mentions that triethylamine aqueous solution is added to triethylamine hydrochloride, and then liquid ammonia is added, and the pressure is 5-10bar under airtight pressurization. This method generates triethylamine and ammonium chloride in reaction, but it adopts liquid ammonia process complexity, and needs high pressure, has relatively high requirements on equipment, slow reaction, and incomplete reaction. And this method has very high purity requirements for raw material triethylamine hydrochloride, needs to reach 98-99wt%, and the by-product triamine hydrochloride of general production of vinylene carbonate cannot reach such high purity, particularly containing a large amount of organic by-product triethylamine hydrochloride waste residue (triethylamine hydrochloride content: 70-80wt%) of production of vinylene carbonate, so this method is not suitable for recovering triethylamine from the triethylamine hydrochloride waste residue produced by vinylene carbonate production technology, and using this method simultaneously can produce black mixture of ammonium chloride and organic matter, is difficult to handle, and can't obtain relatively pure ammonium chloride. Summary of the invention
[0011] The purpose of the present invention is to provide a method for recovering triethylamine from triethylamine hydrochloride waste residue produced in a vinylene carbonate production process, and to solve the problem of generating a large amount of organic waste brine in the existing process.
[0012] The present invention discloses a method for recovering triethylamine from triethylamine hydrochloride waste residue produced in a vinylene carbonate production process, comprising the following steps:
[0013] S1: thermally treating triethylamine hydrochloride waste residue generated in the vinylene carbonate production process;
[0014] S2: mixing the heat-treated triethylamine hydrochloride waste residue with an organic polar solvent, so that the triethylamine hydrochloride in the waste residue is dissolved in the organic polar solvent;
[0015] S3: filtering to remove impurities insoluble in the organic polar solvent in the mixed solution;
[0016] S4: passing ammonia gas into the liquid from which impurities have been removed for reaction; after the reaction is completed, filtering to remove the solid ammonium chloride;
[0017] S5: separating the triethylamine and the organic polar solvent in the obtained filtrate.
[0018] The invention discloses a method for recovering triethylamine from triethylamine hydrochloride waste residue produced in a vinylene carbonate production process. The triethylamine hydrochloride waste residue is heated and dried to remove residual dimethyl carbonate solvent, and then triethylamine hydrochloride is dissolved in an organic polar solvent, and insoluble organic impurities therein are filtered to obtain a clarified triethylamine hydrochloride solution; ammonia gas is introduced into the triethylamine hydrochloride solution for reaction to generate ammonium chloride and triethylamine, triethylamine is dissolved in the organic polar solvent, and ammonium chloride solid is precipitated, and ammonium chloride solid is obtained by filtration. The filtrate is distilled to recover triethylamine and organic polar solvent. The recovery process disclosed by the invention does not use water, does not generate wastewater, and the organic polar solvent can be recycled, and the by-product ammonium chloride solid obtained can be used as a fertilizer.
[0019] In the production process of vinylene carbonate, dimethyl carbonate is usually used as a solvent. The triethylamine hydrochloride waste residue produced in the production process is washed with dimethyl carbonate, and the impurities that can be dissolved in organic polar solvents are much less.
[0020] Furthermore, in step S1, the temperature of the heat treatment is 90-110°C.
[0021] The triethylamine hydrochloride waste residue is subjected to heat treatment, water and other low-boiling-point volatile components in the waste residue are removed by heat treatment, and the impurity content in subsequent triethylamine is reduced.
[0022] Furthermore, in the step S1, dimethyl carbonate is recovered during the heat treatment.
[0023] When vinylene carbonate is produced, dimethyl carbonate is used as a raw material. A small amount of dimethyl carbonate will remain in the waste residue. The dimethyl carbonate is evaporated by heat treatment and then recycled. At the same time, dimethyl carbonate is miscible with various polar solvents such as water, alcohol (such as methanol, ethanol), ether, etc. The dimethyl carbonate in the waste residue is removed to avoid mixing into the solution as an impurity during dissolution, thereby affecting the purity of the recovered product.
[0024] Furthermore, in step S2, the organic polar solvent is selected from one or more of methanol, ethanol, chloroform, dichloromethane, acetone, N,N-dimethylformamide (DMF), and dimethyl sulfoxide (DMSO).
[0025] The waste residue from which low-molecular volatile substances are removed is dissolved in an organic polar solvent. Triethylamine hydrochloride in the waste residue is dissolved in the organic polar solvent, while organic high molecular polymer impurities are insoluble in the organic polar solvent. The organic high molecular polymer impurities in the waste residue are removed by filtering.
[0026] Furthermore, in step S2, the organic polar solvent is selected from one or more of methanol, ethanol and chloroform.
[0027] Furthermore, in step S4, the reaction is carried out under normal pressure.
[0028] Normal pressure reactions are easier to operate and have low requirements for operating equipment.
[0029] The reaction process of triethylamine hydrochloride and ammonia is as follows:
[0030]
[0031] The reaction of triethylamine hydrochloride and ammonia is an exothermic acid-base neutralization reaction, and the reaction temperature must be controlled below the boiling point of the organic polar solvent.
[0032] Furthermore, in step S4, the reaction temperature is controlled at 15-60°C.
[0033] Furthermore, in step S4, the reaction temperature is controlled at 20-50°C.
[0034] Properly increasing the temperature can speed up the reaction rate.
[0035] Furthermore, the filtrate obtained in the step S4 is used to replace the organic polar solvent and is mixed with the heat-treated triethylamine hydrochloride waste residue in the step S2.
[0036] The filtrate containing triethylamine solution is used to dissolve triethylamine hydrochloride in waste residue instead of organic polar solvent, which can improve the utilization rate of organic polar solvent. Triethylamine and organic polar solvent can be mutually soluble in any proportion, and the organic polar solvent mixed with triethylamine will not affect the dissolution of triethylamine hydrochloride in waste residue.
[0037] Furthermore, in the step S5, when the volume of the filtrate increases by 40-70%, the triethylamine and the organic polar solvent in the filtrate are separated by distillation.
[0038] The triethylamine and the organic polar solvent are separated by distillation, and the separated product has high purity. Meanwhile, the triethylamine and the organic polar solvent have low boiling points, and the distillation energy consumption is relatively low.
[0039] Compared with the prior art, the present invention has the following advantages:
[0040] 1. The present invention uses ammonia gas to replace the sodium hydroxide solution used in the traditional process to treat triethylamine hydrochloride, efficiently recovers triethylamine, and avoids the generation of sodium chloride wastewater containing organic matter in the recovery process.
[0041] 2. The present invention reduces the problem of organic impurities adhering to triethylamine hydrochloride affecting the subsequent separation of triethylamine by first performing the processes of heating, dissolving, filtering and the like on triethylamine hydrochloride, thereby increasing the recovery rate of triethylamine.
[0042] 3. The present invention adopts an organic polar solvent that is easily separated and recycled instead of water to dissolve the triethylamine hydrochloride waste residue, thereby solving the problem of generating a large amount of brown-black organic ammonium chloride wastewater during the recovery process.
[0043] 4. The triethylamine recovered by the present invention has high purity and can be used for the production of vinylene carbonate, converting the by-products in the production into raw materials required for the production, reducing the consumption of triethylamine in the production process, and realizing the green production of vinylene carbonate. BRIEF DESCRIPTION OF THE DRAWINGS
[0044] Figure 1 The invention discloses a process flow chart of a method for recovering triethylamine from triethylamine hydrochloride waste residue produced in a vinylene carbonate production process. DETAILED DESCRIPTION
[0045] In order to make the technical solution of the present invention clearer, the present invention is further described in detail below in conjunction with the accompanying drawings and specific examples. It should be understood that these examples are used to illustrate the basic principles, main features and advantages of the present invention, and the present invention is not limited to the scope of the following examples; the implementation conditions used in the examples can be further adjusted according to specific requirements, and the unspecified example conditions are usually the conditions in conventional experiments. In the following examples, unless otherwise specified, all raw materials are commercially available or prepared by conventional methods.
[0046] Example 1
[0047] Reference Figure 1 As shown, 1501.8 g of triethylamine hydrochloride waste residue produced in the production of vinylene carbonate was taken, heated at 90° C. to recover dimethyl carbonate therein, and 1417.8 g of dry triethylamine hydrochloride was obtained.
[0048] 1417.8 g of dried triethylamine hydrochloride waste residue was divided into 5 portions of similar mass.
[0049] First, take a portion of dried triethylamine hydrochloride waste residue and add 1200 ml of methanol, stir evenly, make the triethylamine hydrochloride in the waste residue fully dissolved in methanol, filter to remove black organic polymer impurities insoluble in methanol, and obtain triethylamine hydrochloride methanol solution. Ammonia is introduced into the triethylamine hydrochloride methanol solution for reaction, and the reaction temperature is maintained at 20-50°C. The generated ammonium chloride is insoluble in methanol and precipitates in the form of solid, which promotes the reaction to proceed in the forward direction. After the reaction is completed, filter to obtain by-product ammonium chloride solid and triethylamine-methanol primary filtrate.
[0050] The first filtrate was used to dissolve the second waste residue, and the previous filtration, ammonia reaction, and refiltration operations were repeated. The secondary filtrate was used to continue dissolving the third waste residue. The above operations were repeated until 5 parts of triethylamine hydrochloride waste residues were processed, and a total of 398.4 g of ammonium chloride solid and triethylamine-methanol filtrate were obtained.
[0051] The triethylamine-methanol filtrate was subjected to rectification and separation to obtain 738.9 g of triethylamine and recovered methanol.
[0052] The obtained triethylamine was measured by gas chromatography: the content of triethylamine was 99.71wt%, and the water content was 57ppm. The triethylamine can be directly recycled to the production of vinylene carbonate.
[0053] Example 2
[0054] 1500.6 g of triethylamine hydrochloride waste residue produced in the production of vinylene carbonate was taken and heated to 110° C. to recover dimethyl carbonate therein, thereby obtaining 1410.9 g of dry triethylamine hydrochloride.
[0055] 1410.9 g of dried triethylamine hydrochloride waste residue was divided into 5 portions of similar mass.
[0056] First, take a portion of dried triethylamine hydrochloride waste residue and add 1200 ml of ethanol, stir evenly, make the triethylamine hydrochloride in the waste residue fully dissolved in ethanol, filter to remove black organic polymer impurities insoluble in ethanol, and obtain triethylamine hydrochloride ethanol solution. Add ammonia gas to the triethylamine hydrochloride ethanol solution for reaction, keep the reaction temperature at 20-50°C, the generated ammonium chloride is insoluble in ethanol and precipitates in the form of solid, which promotes the reaction to proceed in the forward direction, and filter after the reaction to obtain by-product ammonium chloride solid and triethylamine-ethanol primary filtrate.
[0057] The first filtrate of triethylamine-ethanol was used to dissolve the second waste residue, and the previous filtration, ammonia reaction, and refiltration operations were repeated. The obtained secondary filtrate was used to continue to dissolve the third waste residue. The above operations were repeated until 5 parts of triethylamine hydrochloride waste residues were treated, and a total of 391.8 g of ammonium chloride solid and triethylamine-ethanol filtrate were obtained.
[0058] The triethylamine-ethanol filtrate was subjected to rectification and separation to obtain 714.6 g of triethylamine and recovered ethanol.
[0059] The obtained triethylamine was measured by gas chromatography: the content of triethylamine was 99.58wt%, and the water content was 62ppm. The triethylamine can be directly recycled to the production of vinylene carbonate.
[0060] Example 3
[0061] 1499.4 g of triethylamine hydrochloride waste residue produced in the production of vinylene carbonate was taken and heated to 100° C. to recover dimethyl carbonate therein, thereby obtaining 1424.4 g of dry triethylamine hydrochloride.
[0062] 1424.4 g of dried triethylamine hydrochloride waste residue was divided into 5 portions of similar mass.
[0063] First, take a portion of the dried triethylamine hydrochloride waste residue and add 1200ml of chloroform, stir evenly, so that the triethylamine hydrochloride in the waste residue is fully dissolved in chloroform, filter to remove the black organic polymer impurities that are insoluble in chloroform, and obtain a triethylamine hydrochloride chloroform solution. Ammonia is introduced into the triethylamine hydrochloride chloroform solution for reaction, and the reaction temperature is maintained at 20-50°C. The generated ammonium chloride is insoluble in chloroform and precipitates in the form of solid, which promotes the reaction to proceed in the forward direction. After the reaction is completed, filter to obtain the by-product ammonium chloride solid and the triethylamine-chloroform primary filtrate;
[0064] The first filtrate of triethylamine-chloroform was used to dissolve the second waste residue, and the previous filtration, ammonia reaction, and refiltration operations were repeated. The obtained secondary filtrate was used to continue to dissolve the third waste residue. The above operations were repeated until 5 parts of triethylamine hydrochloride waste residues were treated, and a total of 412.8 g of ammonium chloride solid and triethylamine-chloroform filtrate were obtained.
[0065] The triethylamine-chloroform filtrate was subjected to rectification and separation to obtain 722.7 g of triethylamine and recovered chloroform.
[0066] The obtained triethylamine was measured by gas chromatography: the content of triethylamine was 99.75wt%, and the content of water was 54ppm. The triethylamine can be directly recycled to the production of vinylene carbonate.
[0067] Comparative Example 1
[0068] 1500.6 g of triethylamine hydrochloride waste residue produced in the production of vinylene carbonate was taken and heated at 90° C. to recover dimethyl carbonate therein, thereby obtaining 1412.7 g of dry triethylamine hydrochloride.
[0069] 1412.7g of dried triethylamine hydrochloride waste residue was added to 1200ml of water, stirred evenly, the triethylamine hydrochloride in the waste residue was fully dissolved in water, filtered to remove water-insoluble organic polymer impurities, and a brown-black triethylamine hydrochloride aqueous solution was obtained (some black organic impurities in the waste residue were soluble in water). Sodium hydroxide was added to the brown-black triethylamine hydrochloride aqueous solution to react, the reaction temperature was maintained at 20-50°C, and after the reaction was completed, the reaction was allowed to stand for stratification, and the crude triethylamine product 753.9g and a large amount of brown-black organic waste brine were obtained by separation.
[0070] 753.9 g of crude triethylamine was dried over anhydrous Na2SO4 and filtered to obtain 740.7 g of triethylamine. The obtained triethylamine was measured by gas chromatography to have a triethylamine content of 99.68 wt % and a water content of 331 ppm.
[0071] Comparative Example 2
[0072] 1499.4 g of triethylamine hydrochloride waste residue produced in the production of vinylene carbonate was taken and heated to 110° C. to recover dimethyl carbonate therein, thereby obtaining 1408.5 g of dry triethylamine hydrochloride.
[0073] Dissolve 1408.5g of dried triethylamine hydrochloride waste residue in 1200ml of water, stir evenly to make the triethylamine hydrochloride in the waste residue fully dissolved in water, filter to remove water-insoluble organic polymer impurities, and obtain a brown-black triethylamine hydrochloride aqueous solution. Pass ammonia gas into the triethylamine hydrochloride aqueous solution to react, keep the reaction temperature at 20-50°C, stand and separate after the reaction, and separate to obtain 739.8g of triethylamine crude product and a large amount of brown-black ammonium chloride organic waste brine.
[0074] 739.8 g of crude triethylamine was dried over anhydrous Na2SO4 and filtered to obtain 725.4 g of triethylamine. The obtained triethylamine was measured by gas chromatography to have a triethylamine content of 99.71 wt % and a water content of 315 ppm.
[0075] Comparative Example 3
[0076] To a 5L stainless steel reactor with a pressure gauge, add 1502.3g of triethylamine hydrochloride waste residue dried at 100°C, add 1.5L triethylamine and 78.2g water, then pressurize into liquid ammonia and gradually raise the temperature to 40°C. By controlling the amount of ammonia, the pressure in the reactor is controlled to 6.8-7.3bar, and the reaction is stirred for 12h.
[0077] The mixture after the reaction was filtered to obtain dark black solid particles and a filtrate. The dark black solid particles were tested to be mainly composed of a mixture of triethylamine hydrochloride, ammonium chloride and organic impurities, wherein the content of ammonium chloride was only 5.72%. The obtained filtrate was mainly triethylamine.
[0078] The results show that this method has high reaction pressure, requires pressure vessels, and has high equipment requirements; it also requires additional triethylamine, which is slow to react, incomplete, and has a low conversion rate. Only a small amount of triethylamine can be recovered from triethylamine hydrochloride waste residue; organic impurities cannot be separated and removed, and pure ammonium chloride solid cannot be obtained. Only a mixture of triethylamine hydrochloride, ammonium chloride and organic impurities can be obtained. It is not suitable for recovering triethylamine from triethylamine hydrochloride waste residue produced in the vinylene carbonate production process.
[0079] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.
Claims
1. A method for recovering triethylamine from triethylamine hydrochloride waste residue produced in a vinylene carbonate production process, characterized in that: The following steps are involved: S1: thermally treating triethylamine hydrochloride waste residue generated in the vinylene carbonate production process; S2: mixing the heat-treated triethylamine hydrochloride waste residue with an organic polar solvent, so that the triethylamine hydrochloride in the waste residue is dissolved in the organic polar solvent; S3: filtering to remove impurities insoluble in the organic polar solvent in the mixed solution; S4: passing ammonia gas into the liquid from which impurities have been removed for reaction; after the reaction is completed, filtering to remove the solid ammonium chloride; S5: separating the triethylamine and the organic polar solvent in the obtained filtrate.
2. A method for recovering triethylamine from triethylamine hydrochloride waste residue produced in a vinylene carbonate production process according to claim 1, characterized in that: In the step S1, the temperature of the heat treatment is 90-110°C.
3. A method for recovering triethylamine from triethylamine hydrochloride waste residue produced in a vinylene carbonate production process according to claim 2, characterized in that: In the step S1, dimethyl carbonate is recovered during the heat treatment.
4. A method for recovering triethylamine from triethylamine hydrochloride waste residue produced in a vinylene carbonate production process according to claim 1, characterized in that: In step S2, the organic polar solvent is selected from one or more of methanol, ethanol, chloroform, dichloromethane, acetone, N,N-dimethylformamide, and dimethyl sulfoxide.
5. A method for recovering triethylamine from triethylamine hydrochloride waste residue produced in a vinylene carbonate production process according to claim 4, characterized in that: In step S2, the organic polar solvent is selected from one or more of methanol, ethanol and chloroform.
6. A method for recovering triethylamine from triethylamine hydrochloride waste residue produced in a vinylene carbonate production process according to claim 1, characterized in that: In the step S4, the reaction is carried out under normal pressure.
7. A method for recovering triethylamine from triethylamine hydrochloride waste residue produced in a vinylene carbonate production process according to claim 6, characterized in that: In step S4, the reaction temperature is controlled at 15-60°C.
8. A method for recovering triethylamine from triethylamine hydrochloride waste residue produced in a vinylene carbonate production process according to claim 7, characterized in that: In step S4, the reaction temperature is controlled at 20-50°C.
9. A method for recovering triethylamine from triethylamine hydrochloride waste residue produced in a vinylene carbonate production process according to claim 1, characterized in that: The filtrate obtained in the step S4 is used to replace the organic polar solvent and mixed with the heat-treated triethylamine hydrochloride waste residue in the step S2.
10. A method for recovering triethylamine from triethylamine hydrochloride waste residue produced in a vinylene carbonate production process according to claim 9, characterized in that: In the step S5, when the volume of the filtrate increases by 40-70%, the triethylamine and the organic polar solvent in the filtrate are separated by distillation.
Citation Information
Patent Citations
Method for recovering triethylamine in vinylene carbonate production
CN114478263A