A process for the preparation of fluoroethylene carbonate
By diluting chloroethylene carbonate with fluoroethylene carbonate and introducing ammonia and hydrogen fluoride, combined with nitrogen purging and 'sweat' crystallization, the problems of high equipment requirements, safety hazards, and low yield in the preparation process of fluoroethylene carbonate were solved, achieving high-purity and high-yield preparation.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- HENAN FLUORINE BASED NEW MATERIAL TECH CO LTD
- Filing Date
- 2026-02-27
- Publication Date
- 2026-06-09
AI Technical Summary
Existing methods for preparing fluoroethylene carbonate suffer from problems such as high requirements for reaction equipment, significant safety hazards, high costs, low yields, and complex purification processes.
A solvent-free reaction was adopted, in which fluoroethylene carbonate was added to chloroethylene carbonate for dilution and ammonia and hydrogen fluoride were introduced. The reaction temperature was controlled at 25-80℃. After the reaction was completed, the mixture was filtered and purged with nitrogen. Purification was carried out by combining 'sweating' crystallization and molecular sieve adsorption.
It achieves low-temperature reaction and low-energy purification, improves yield and reduces material loss, and the product purity reaches over 99.95%, which meets the requirements for use of electrolyte salts in lithium-ion batteries.
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Figure CN122167383A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of lithium battery additive technology, and particularly relates to a method for preparing fluoroethylene carbonate. Background Technology
[0002] Fluorinated ethylene carbonate (FEC) is an important electrolyte additive that can form an effective solid electrolyte interphase (SEI) film on the battery electrode surface, thereby effectively preventing side reactions between oxidants in the electrolyte and the negative electrode. It can also significantly improve battery cycle stability, rate capability, and safety performance, making it a high-performance lithium-ion battery electrolyte additive.
[0003] Application CN 119707909A discloses a method for preparing fluoroethylene carbonate: using vinylene carbonate and anhydrous hydrogen fluoride as raw materials, the reaction is carried out under the catalysis of an organic base pyridine hydrofluoric acid salt. The reaction pressure is 0.3-3 MPa. After the reaction, excess hydrogen fluoride is removed from the reaction solution under negative pressure, and then the product is obtained by distillation. The disadvantages of this method are: firstly, it requires sophisticated reaction equipment, as the reaction uses hydrogen fluoride and is carried out at high pressure, requiring specialized equipment with significant safety hazards and high cost; secondly, the initial negative pressure distillation of the reaction solution to obtain 99.5% pure FEC requires further purification, such as rectification or "sweating" crystallization, which reduces the yield due to the additional step.
[0004] Application CN 120518577A discloses a method for preparing fluoroethylene carbonate. Ethylene carbonate undergoes a fluorination reaction in the presence of a fluorinating reagent, a co-catalyst, and a phase transfer catalyst to obtain fluoroethylene carbonate. The co-catalyst is concentrated sulfuric acid, and the fluorinating reagent is a fluorinated basic salt. The post-processing method involves solid-liquid analysis, solvent distillation, and purification by distillation to obtain fluoroethylene carbonate. The disadvantages of this method are that the addition of concentrated sulfuric acid to the reaction solution results in high residual acidity, and the cost of secondary processing is also high. Especially during the distillation purification process, a certain temperature is required, and under acidic conditions, FEC is more prone to deterioration. Summary of the Invention
[0005] The purpose of this invention is to provide a method for preparing fluoroethylene carbonate with high yield, short reaction time and very low reaction temperature.
[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for preparing fluoroethylene carbonate includes the following steps: ammonia and hydrogen fluoride are introduced into a container containing chloroethylene carbonate and reacted, followed by filtration to obtain filtrate and filter cake. The reaction ends when the remaining amount of chloroethylene carbonate is less than 0.01-0.15% of the added amount, as detected by gas phase detection. The filtrate is purified by nitrogen purging to obtain fluoroethylene carbonate.
[0007] Furthermore, to accelerate the reaction, the chloroethylene carbonate is first diluted with fluoroethylene carbonate before use, and the mass of the fluoroethylene carbonate is 10 to 200% of the mass of the chloroethylene carbonate.
[0008] Furthermore, the container is equipped with a stirring and heating device, and the container is purged with nitrogen before use.
[0009] Furthermore, the reaction temperature is 25–80°C, the molar ratio of ammonia to hydrogen fluoride is 1.01–1.5:1, and the injection rate is 0.01–0.1 m³ / h.
[0010] Furthermore, the nitrogen purging time is 2 to 16 hours, and the filtrate is purged with nitrogen to remove excess ammonia.
[0011] Furthermore, the purification process involves "sweating" crystallization and molecular sieve adsorption. After "sweating," the unqualified material is used as a diluent for the next batch of synthesis. The material loss during the entire process is almost zero.
[0012] Furthermore, the filter cake is produced as a by-product after being washed with a carbonate solvent. The filter cake is washed with a carbonate solvent, and the filtrate from the washing is first collected and stored. After several batches, it is concentrated for distillation and crystallization to obtain the product again. The carbonate solvent is preferably dimethyl carbonate and diethyl carbonate. The washing number is preferably 2-4 times, and the amount of each washing is preferably 0.2-4 times the mass of fluoroethylene carbonate produced.
[0013] Mechanism: This invention involves adding a small amount of fluoroethylene carbonate as a diluent to chloroethylene carbonate, while simultaneously introducing ammonia and hydrogen fluoride. The resulting anhydrous ammonium fluoride serves as the fluorine source for the chloroethylene carbonate, initiating a substitution reaction. After the reaction, the mixture is filtered, and the filtrate is subjected to negative pressure to remove excess ammonia or hydrogen fluoride, yielding crude fluoroethylene carbonate. This crude product is then subjected to "sweating" crystallization and molecular sieve adsorption to obtain fluoroethylene carbonate with a purity greater than 99.95%. The foredistillate from the "sweating" crystallization is used as a diluent for the next batch of reactions, thus solving the problems of difficult purification, high levels of waste, and low yield.
[0014] The advantages of this invention are: 1. This invention uses a solvent-free reaction with a low reaction temperature, resulting in virtually no polymerization reaction. 2. In this invention, ammonia is used in slight excess, and the reaction is still slightly alkaline after completion, which reduces the occurrence of polymerization reaction; 3. In this invention, the washing liquid and the reaction liquid are processed separately, which is beneficial to improving the yield; 4. This invention uses "sweating" crystallization to purify the product, which has low energy consumption, no material loss, and is green and environmentally friendly; 5. This invention removes ammonia entrained in the filtrate by nitrogen stripping, and the operation is simple; 6. The ammonium halide obtained from the filter residue of this invention can be dried and sold directly as a by-product ammonium halide. The operation is simple and environmentally friendly. Attached Figure Description
[0015] Figure 1 The NMR fluorine spectrum of the fluoroethylene carbonate prepared in Example 1 is shown below. Figure 2 This is the 1H NMR spectrum of the fluoroethylene carbonate prepared in Example 1. Detailed Implementation
[0016] Example 1 A method for preparing fluoroethylene carbonate involves installing a stirrer and other equipment on a 1-liter four-necked tetrafluoroethylene flask, purging with nitrogen, adding 122.6 g of chloroethylene carbonate (purity greater than 99.9%) and 12.3 g of fluoroethylene carbonate, and simultaneously introducing ammonia and hydrogen fluoride at a molar ratio of 1.01. The reaction is carried out at 25°C, with gas-phase monitoring of the reaction progress. After the reaction is complete, the filtrate is obtained by filtration. The filtrate is then stripped with nitrogen to remove excess ammonia. The filter residue is washed twice with dimethyl carbonate, 21.2 g each time, and the washing liquid is collected for centralized treatment. The nitrogen-stripped liquid undergoes "sweating" crystallization and molecular sieve adsorption, followed by filtration to obtain 98.62 g of fluoroethylene carbonate with a purity of 99.98%, yielding a recovery rate of 81.36%. Example 2 A method for preparing fluoroethylene carbonate involves installing a stirrer and other equipment on a 1-liter four-necked tetrafluoroethylene flask, purging with nitrogen, adding 122.6 g of chloroethylene carbonate (purity greater than 99.9%) and 245.2 g of fluoroethylene carbonate, and simultaneously introducing ammonia and hydrogen fluoride at a molar ratio of 1.5. The reaction is carried out at 80°C, with gas-phase monitoring of the reaction progress. After the reaction is complete, the mixture is filtered to obtain a filtrate. The filtrate is then stripped with nitrogen to remove excess ammonia. The filter residue is washed twice with dimethyl carbonate, 424 g each time, and the washing liquid is collected for further processing. The nitrogen-stripped liquid undergoes "sweating" crystallization and molecular sieve adsorption, followed by filtration to obtain 325.99 g of fluoroethylene carbonate with a purity of 99.97%, yielding a recovery rate of 76.15%.
[0017] Example 3 A method for preparing fluoroethylene carbonate involves installing a stirrer and other equipment on a 1-liter four-necked tetrafluoroethylene flask, purging with nitrogen, and adding 122.6 g of chloroethylene carbonate (purity greater than 99.9%) and 122.6 g of fluoroethylene carbonate. Ammonia and hydrogen fluoride are simultaneously introduced, with a molar ratio of ammonia to hydrogen fluoride of 1.3. The reaction is carried out at 50°C, and the reaction progress is monitored using the gas phase. After the reaction is complete, the mixture is filtered to obtain a filtrate. The filtrate is then stripped with nitrogen to remove excess ammonia. The filter residue is washed twice with dimethyl carbonate, 300 g each time, and the washing liquid is collected for further processing. The nitrogen-stripped liquid undergoes "sweating" crystallization and molecular sieve adsorption, followed by filtration to obtain 208.13 g of fluoroethylene carbonate with a purity of 99.97%, yielding a recovery rate of 80.62%.
[0018] Example 4 A method for preparing fluoroethylene carbonate involves installing a stirrer and other equipment on a 1-liter four-necked tetrafluoroethylene flask, purging with nitrogen, adding 122.6 g of chloroethylene carbonate (purity greater than 99.9%) and 122.6 g of fluoroethylene carbonate, and adding 48.1 g of solid ammonium fluoride in batches. The reaction is carried out at 50°C, and the reaction progress is monitored by gas phase. After the reaction is complete, the filtrate is obtained by filtration. The filtrate is then stripped with nitrogen, and the filter residue is washed twice with dimethyl carbonate, 300 g each time. The washing liquid is then centrally processed. The nitrogen-stripped liquid undergoes "sweating" crystallization and molecular sieve adsorption, followed by filtration to obtain 191.96 g of fluoroethylene carbonate with a purity of 99.95%, yielding a yield of 65.43%.
[0019] Performance testing The fluoroethylene carbonates prepared in Examples 1-4 were subjected to relevant performance tests according to the requirements of HGT4790-2014. The test results are shown in Table 1.
[0020] Table 1. Tests for fluoroethylene carbonate As shown in Table 1, the fluoroethylene carbonates obtained in Examples 1-3 have a purity of not less than 99.96%, a water content of not more than 11 ppm, a free acid content of not more than 2 ppm, an organochlorine content of not more than 2 ppm, a color content of not more than 4 ppm, and extremely low levels of other impurity ions. All indicators of the fluoroethylene carbonate synthesized in this invention are superior to those obtained through solid ammonium fluoride synthesis. The test results indicate that the fluoroethylene carbonate prepared by the method of this invention yields a product with high purity, meeting the requirements for use as an electrolyte salt in lithium-ion batteries, and is suitable for widespread application.
Claims
1. A method for preparing fluoroethylene carbonate, characterized in that, Includes the following steps: Ammonia and hydrogen fluoride were introduced into a container containing chloroethylene carbonate, and the mixture was filtered to obtain filtrate and filter cake. The filtrate was purified by purging with nitrogen to obtain fluoroethylene carbonate.
2. The method for preparing fluoroethylene carbonate as described in claim 1, characterized in that: The chloroethylene carbonate is first diluted with fluoroethylene carbonate before use, and the mass of the fluoroethylene carbonate is 10 to 200% of the mass of the chloroethylene carbonate.
3. The method for preparing fluoroethylene carbonate as described in claim 1, characterized in that: The container is equipped with a stirring and heating device, and the container is purged with nitrogen before use.
4. The method for preparing fluoroethylene carbonate according to claim 1, characterized in that: The reaction temperature is 25–80°C, the molar ratio of ammonia to hydrogen fluoride is 1.01–1.5:1, and the injection rate is 0.01–0.1 m³ / h.
5. The method for preparing fluoroethylene carbonate as described in claim 1, characterized in that: The nitrogen purging time is 2 to 16 hours.
6. The method for preparing fluoroethylene carbonate according to claim 1, characterized in that: The purification process involves sweat crystallization and molecular sieve adsorption.
7. The method for preparing fluoroethylene carbonate according to claim 1, characterized in that: The filter cake is produced as a by-product after being washed with carbonate solvent.
8. The method for preparing fluoroethylene carbonate as described in claim 1, characterized in that: The reaction endpoint is when the remaining amount of chloroethylene carbonate is less than 0.01 to 0.15% of the added amount.