Method for preparing fluoroethylene carbonate

Abstract

This invention relates to the technical field of lithium-ion battery electrolyte additive synthesis and provides a method for preparing fluoroethylene carbonate. The invention involves mixing chloroethylene carbonate, a polymerization inhibitor, a catalyst, and liquid hydrogen fluoride to carry out a fluorination reaction to obtain fluoroethylene carbonate. By adding the polymerization inhibitor and catalyst simultaneously, the invention avoids the occurrence of side reactions such as polymerization of materials, while increasing the reaction rate, improving the conversion rate and product yield. The invention uses liquid hydrogen fluoride as the fluorination reagent, resulting in low cost, ease of use, and convenience for continuous production. The invention utilizes a benzotrifluoride compound as the solvent, effectively utilizing the remaining hydrogen fluoride, enabling efficient resource utilization and reducing production costs. The fluorination reaction of this invention can be carried out in a microchannel reactor, enabling continuous automated production. Therefore, the preparation method provided by this invention is efficient, economical, green, and environmentally friendly, offering broad prospects.

Description

Technical Field

[0001] This application claims the priority of a Chinese patent application filed with the China National Intellectual Property Administration on January 24, 2024, with the application number CN202410101101.1 and the invention title "Method for Preparing Fluoroethylene Carbonate", and all its contents are incorporated herein by reference.

[0002] The present invention relates to the technical field of synthesizing additives for lithium-ion battery electrolytes, and particularly to a method for preparing fluoroethylene carbonate.

Background Art

[0003] [[ID=十六]]A lithium-ion battery consists of a positive electrode, a negative electrode, a separator, and an electrolyte. The electrolyte is called the "blood" of the lithium-ion battery and plays a role in electron conduction between the positive and negative electrodes of the battery. The manufacturing cost of the electrolyte accounts for 14% of the total cost of the lithium battery. In addition to the positive electrode material, it can be said that the electrolyte is the most costly part. The electrolyte is prepared by mixing raw materials such as a solvent, a solute (i.e., a lithium salt), and additives at a certain ratio. Generally, the ratio of the solvent is 80-90%, the ratio of the lithium salt is about 8%, and the ratio of the additives is 5-10%. The manufacturing cost is such that the cost of the solute is the highest, accounting for nearly 50%, the cost of the solvent accounts for about 30%, and the cost of the additives accounts for about 10%. There are many types of additives, and their roles are also diverse. For example, they can improve conductivity, overcharge safety performance, storage performance, flame retardancy, stability, etc. Different lithium-ion battery manufacturers have different requirements for the use and performance of the battery, and accordingly, the focus of the selection of additives also changes. The importance of additives has become more prominent as the requirements for battery performance increase.

[0004] Fluoroethylene carbonate is an organic film-forming additive and an overcharge protection additive for lithium-ion battery electrolytes. It has good high-temperature and low-temperature performance and an anti-expansion function, and can improve the capacity and cycle life of lithium-ion batteries.

[0005] Currently, the main methods for producing fluoroethylene carbonate are as follows:

[0006] Patent US6010806 discloses a method for reacting dimethyl carbonate and 3,3,3-trifluoro-1,2-propylene oxide in the presence of sodium bicarbonate, but the raw materials used in such a method are expensive, the reaction time is long, and it is unfavorable for industrial production (Patent Document 1). Patent CN108250176A provides a high-speed continuous-flow synthesis process for fluoroethylene carbonate, in which F2 is highly toxic, highly reactive, easily uncontrollable, highly dangerous, produces many by-product impurities, is difficult to separate and purify, and has high production costs (Patent Document 2). Patent WO98115024 describes a method for reacting chloroethylene carbonate with potassium fluoride as raw materials. This method is a relatively mature synthesis method used in the Chinese domestic industry. However, this reaction is heterogeneous, time-consuming, has a low conversion rate, requires high particle size and activity for solid potassium fluoride, is expensive, and using large quantities of solid potassium fluoride increases labor intensity, making automation difficult. Furthermore, it generates large amounts of mixed solid waste of potassium chloride and potassium fluoride, resulting in high costs for waste liquid, waste gas, and solid waste (Patent Document 3). Patent CN101774923B discloses a method for preparing fluoroethylene carbonate. This method involves a substitution reaction between chloroethylene carbonate and a fluorinating agent in the presence of an organic solvent and an acid binder to produce fluoroethylene carbonate. Because this method uses solvents, it is expensive, the post-processing is complicated, and the yield is not high, at approximately 85% (Patent Document 4). Patents CN105968083A and CN114874179A disclose a method for preparing fluoroethylene carbonate. In this method, fluoroethylene carbonate is prepared using a microchannel with hydrogen fluoride as the fluorine source. Repeated experiments have shown that the actual conversion rate and product yield of this method are very limited and do not meet the requirements for industrial applications (Patent Documents 5 and 6).Patent CN116178333A discloses a method for preparing fluoroethylene carbonate using chloroethylene carbonate as a raw material, hydrogen fluoride as a fluorine source, and a mixture of SbCl5 and MoCl5 in a certain proportion as a catalyst. However, this method produces high levels of by-product impurities, which prevents the guarantee of product yield and quality. The yield is less than 85%, and the product purity is less than 99.5%, which completely fails to meet the requirement of 99.95% or higher purity required for electronic-grade lithium battery additives (Patent Document 7).

[0007] Based on the above, existing preparation methods generally suffer from problems such as low conversion rates and product yields, low product purity, and high costs, making them unsuitable for industrial production. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] U.S. Patent Application Publication No. 6010806 [Patent Document 2] Chinese Patent Application Publication No. 108250176 Specification [Patent Document 3] International Publication No. 98115024 [Patent Document 4] Specification of Chinese Patent Application Publication No. 101774923 [Patent Document 5] Chinese Patent Application Publication No. 105968083 Specification [Patent Document 6] Chinese Patent Application Publication No. 114874179 Specification [Patent Document 7] Chinese Patent Application Publication No. 116178333 Specification [Overview of the Initiative] [Problems that the invention aims to solve]

[0009] In view of this, the present invention provides a method for preparing fluoroethylene carbonate. The preparation method provided by the present invention has a high raw material conversion rate, high product yield and purity, and low preparation costs. [Means for solving the problem]

[0010] To achieve the objectives of the above invention, the present invention provides the following technical solutions.

[0011] A method for preparing fluoroethylene carbonate, The process includes the step of mixing chloroethylene carbonate, a polymerization inhibitor, a catalyst, and liquid hydrogen fluoride to carry out a fluorination reaction to obtain fluoroethylene carbonate, wherein the catalyst comprises one or more of metal fluorides, metal chlorides, and tetrabutylammonium fluoride, and the polymerization inhibitor comprises one or more of amine-based polymerization inhibitors, phenol-based polymerization inhibitors, and piperidinyl nitrooxide radical-based polymerization inhibitors.

[0012] Preferably, a solvent is added during the mixing process, the solvent being a benzotrifluoride compound, and the structural formula of the benzotrifluoride compound is as shown in formula I. JPEG2026514265000002.jpg3828 Formula I In formula I, n is an integer from 0 to 5, and R is one or more of alkyl groups, phenyl groups, and halogens. The molar ratio of chloroethylene carbonate to solvent is 1:(0.2~2).

[0013] Preferably, the fluorination reaction is carried out in an autoclave.

[0014] Preferably, the fluorination reaction includes adding chloroethylene carbonate, a solvent, a catalyst, a polymerization inhibitor, and liquid hydrogen fluoride to an autoclave, then heating, and carrying out the fluorination reaction under constant temperature and pressure conditions. In the fluorination reaction process, hydrogen chloride gas generated during the reaction is discharged, the discharged hydrogen chloride gas is absorbed by water to prepare by-product hydrochloric acid, and the pressure of the fluorination reaction is controlled by the discharge amount of hydrogen chloride gas. In the fluorination reaction process, the generated gaseous hydrogen fluoride and gaseous solvent are condensed and then collected, and then returned to the autoclave.

[0015] Preferably, after the fluorination reaction is completed, the obtained reaction solution is mixed with a benzotrichloride-based compound, and the benzotrichloride-based compound is reacted with the remaining hydrogen fluoride in the reaction solution to obtain a mixed reaction solution of fluoroethylene carbonate and a benzotrifluoride-based compound. The mixed reaction solution is distilled and desolvated to obtain a concentrated solution and a benzotrifluoride-based compound respectively. The benzotrifluoride-based compound obtained by the distillation and desolvation is recycled. The concentrated solution is subjected to fractional distillation and melt crystallization sequentially to obtain a fluoroethylene carbonate product. The structure of the benzotrichloride-based compound is as shown in Formula II. JPEG2026514265000003.jpg3227Formula II In Formula II, n is an integer from 0 to 5, and R is one or more of an alkyl group, a phenyl group, and a halogen.

[0016] Preferably, the fluorination reaction is carried out in a microchannel reactor.

[0017] Preferably, the fluorination reaction comprises mixing chloroethylene carbonate, a catalyst, and a polymerization inhibitor to obtain a mixed solution, or mixing chloroethylene carbonate, a catalyst, a polymerization inhibitor, and a solvent to obtain a mixed solution. introducing the mixed solution and liquid hydrogen fluoride into a microchannel reactor to carry out a fluorination reaction.

[0018] Preferably, after the fluorination reaction, the generated gas-liquid mixture is subjected to gas-liquid separation to obtain a reaction solution and a mixed gas containing hydrogen fluoride and hydrogen chloride, and the mixed gas is condensed to recover hydrogen fluoride, and the remaining hydrogen chloride is absorbed with water to prepare hydrochloric acid.

[0019] Preferably, the apparatus used for the fluorination reaction further includes a liquid hydrogen fluoride storage tank 1, a mixed liquid storage tank 2, a gas-liquid separator 4, a condenser 5, a reaction solution receiving tank 6, and a liquid hydrogen fluoride recovery tank 7. The outlet of the liquid hydrogen fluoride storage tank 1 and the outlet of the mixed liquid storage tank 2 communicate with the inlet of the microchannel reactor 3. The inlet of the gas-liquid separator 4 communicates with the outlet of the microchannel reactor 3. The inlet of the condenser 5 communicates with the gas outlet of the gas-liquid separator 4. The inlet of the reaction solution receiving tank 6 communicates with the liquid outlet of the gas-liquid separator 4. The inlet of the liquid hydrogen fluoride recovery tank 7 communicates with the liquid outlet of the condenser 5.

[0020] Preferably, the temperature of the fluorination reaction is 30°C to 80°C, and the pressure is 0.1 to 1.5 MPa.

[0021] Preferably, the polymerization inhibitor includes one or more of phenothiazine, polymerization inhibitor 701, p-tert-butylcatechol, hydroquinone, diphenylamine, and polymerization inhibitor 705. The molar ratio of the chloroethylene carbonate to the polymerization inhibitor is 1:(0.0001 to 0.001). The molar ratio of the chloroethylene carbonate to the liquid hydrogen fluoride is 1:(1 to 5).

[0022] Preferably, the catalyst comprises one or more of potassium fluoride, ferric chloride, antimony trichloride, tungsten hexachloride, antimony pentachloride, tin tetrachloride, titanium tetrachloride, and tetrabutylammonium fluoride, and the molar ratio of the chloroethylene carbonate to the catalyst is 1:(0.001~0.01).

[0023] Preferably, the rectification vessel temperature is 90°C to 110°C, the top temperature is 60°C to 80°C, and the pressure is 15 mmHg or less. The melt crystallization process involves lowering the temperature of the product collected after rectification to 18°C ​​to 20°C, allowing it to crystallize for 10 to 16 hours, then releasing the uncrystallized material, and raising the temperature of the remaining crystallized material to 35°C to 40°C to melt it and obtain a fluoroethylene carbonate refined product.

[0024] The present invention provides a method for preparing fluoroethylene carbonate, comprising the steps of mixing chloroethylene carbonate (CEC), a polymerization inhibitor, a catalyst, and liquid hydrogen fluoride to carry out a fluorination reaction to obtain fluoroethylene carbonate (FEC), wherein the catalyst comprises one or more of metal fluorides, metal chlorides, and tetrabutylammonium fluoride, and the polymerization inhibitor comprises one or more of amine-based polymerization inhibitors, phenol-based polymerization inhibitors, and piperidinyl nitrooxide radical-based polymerization inhibitors. The present invention avoids the occurrence of side reactions such as polymerization of materials by adding the polymerization inhibitor and catalyst simultaneously during the fluorination reaction, while increasing the reaction rate and further improving the conversion rate and product yield. Results from the examples show that the molar yield of the fluoroethylene carbonate of the present invention can reach 90% or more, and the purity of the product can reach 99.95% or more. Furthermore, the present invention uses liquid hydrogen fluoride as a fluorinating reagent, and compared to fluorinating reagents such as potassium fluoride and fluorine gas, liquid hydrogen fluoride is cheaper, safer, easier to use, easier to implement automated control, reduces the workload of workers in the workplace, and lowers production costs. At the same time, liquid hydrogen fluoride has higher mass transfer efficiency than gaseous hydrogen fluoride, which is advantageous for improving conversion rates and product yields.

[0025] Furthermore, the present invention uses a benzotrifluoride compound as the solvent for the fluorination reaction. The benzotrifluoride compound is highly stable, resistant to decomposition, does not interfere with the fluorination reaction, and has excellent solubility, dissolving the small amount of polymer produced by the reaction, preventing adhesion to polymer walls and clogging of pipes, improving the yield and purity of the product. The benzotrifluoride compound is also easy to separate, recover, and reuse, which is advantageous for further reducing production costs.

[0026] Furthermore, the present invention not only allows for the preparation of benzotrifluoride compounds by effectively utilizing excess hydrogen fluoride by adding a benzotrichloride compound to the reaction solution after the fluorination reaction is complete and reacting it with the remaining hydrogen fluoride in the system, but also avoids the need for alkali neutralization and hydrogen fluoride removal operations in post-treatment, thereby significantly reducing production costs.

[0027] Furthermore, the present invention allows for the preparation of by-product hydrochloric acid after absorbing the hydrogen chloride gas generated during the reaction process with water, thereby enabling the utilization of waste gas and demonstrating clear economic benefits.

[0028] Furthermore, the amount of catalyst used in the present invention is very small, only 0.1% to 1% of the molar amount of chloroethylene carbonate, mainly for the following reasons: By using a polymerization inhibitor and a catalyst in combination, the polymerization inhibitor can significantly reduce polymer formation, and the catalyst cannot dissolve in the reaction system. If a large amount of polymer is produced, it coats the catalyst and affects the catalytic effect. The present invention can improve catalytic activity by using a polymerization inhibitor and a catalyst in combination. Due to the above reasons, the amount of catalyst used in the present invention is significantly reduced, and catalysts are generally relatively expensive. The present invention reduces the amount of catalyst used and further significantly reduces production costs.

[0029] Furthermore, this invention enables continuous automated production by using a microchannel reactor to carry out the fluorination reaction, significantly reducing operational risks and providing greater safety.

[0030] Furthermore, because the present invention uses a polymerization inhibitor in the reaction process, the formation of by-reaction polymers is reduced, and therefore, less hazardous waste is generated. [Brief explanation of the drawing]

[0031] [Figure 1] This is a schematic diagram of the apparatus structure when a reaction is carried out using a microchannel reactor in the present invention. [Figure 2] This is the HPLC spectrum of the fluoroethylene carbonate prepared in Example 1. [Figure 3] This is the hydrogen nuclear magnetic resonance spectrum of the fluoroethylene carbonate prepared in Example 1. [Figure 4] This is the carbon nuclear magnetic resonance spectrum of the fluoroethylene carbonate prepared in Example 1. [Modes for carrying out the invention]

[0032] The present invention provides a method for preparing fluoroethylene carbonate. The process includes the step of mixing chloroethylene carbonate, a polymerization inhibitor, a catalyst, and liquid hydrogen fluoride to carry out a fluorination reaction to obtain fluoroethylene carbonate, wherein the catalyst comprises one or more of metal fluorides, metal chlorides, and tetrabutylammonium fluoride, and the polymerization inhibitor comprises one or more of amine-based polymerization inhibitors, phenol-based polymerization inhibitors, and piperidinyl nitrooxide radical-based polymerization inhibitors.

[0033] In the present invention, it is preferable to add a solvent at the time of mixing, and the solvent is preferably a benzotrifluoride compound, and the structural formula of the benzotrifluoride compound is preferably as shown in formula I. JPEG2026514265000004.jpg3728 Formula I In formula I, n is an integer from 0 to 5, more preferably 0, 1, 2, 3, 4, or 5, and even more preferably 0 or 1, specifically, n represents the total number of all R groups in the benzene ring, and when n is greater than 1, each R group may be the same or different, R is one or more of alkyl groups, phenyl groups, and halogens, the number of carbon atoms in the alkyl group is preferably 1 to 10, more preferably 1 to 5, specifically, R is more preferably one or more of methyl groups, phenyl groups, F, Cl, Br, and I, and in specific examples of the present invention, the benzotrifluoride compound is preferably benzotrifluoride (i.e., n is 0), or preferably a compound having the structure shown in formula I-1. JPEG2026514265000005.jpg2246 Formula I-1 In formula I-1, R is preferably one of a methyl group and Cl.

[0034] In specific embodiments of the present invention, the solvent is most preferably benzotrifluoride or p-chlorobenzotrifluoride.

[0035] In the present invention, the molar ratio of chloroethylene carbonate to solvent is preferably 1:(0.2~2), more preferably 1:(0.2~1.5), and even more preferably 1:0.22, and the purity of the chloroethylene carbonate is preferably 90 wt%~95 wt%.

[0036] In the present invention, the polymerization inhibitor preferably comprises one or more of phenothiazine, polymerization inhibitor 701, p-tert-butylcatechol, hydroquinone, diphenylamine, and polymerization inhibitor 705, the molar ratio of chloroethylene carbonate to polymerization inhibitor is preferably 1:(0.0001~0.001), more preferably 1:(0.0002~0.0005), and even more preferably 1:0.0004, the catalyst comprises one or more of metal fluorides, metal chlorides, and tetrabutylammonium fluoride, preferably at least two, specifically the catalyst comprises potassium fluoride, ferric chloride, antimony trichloride, tungsten hexachloride, antimony pentachloride, tin tetrachloride, titanium tetrachloride, and The catalyst comprises one or more, more preferably at least two, tetrabutylammonium fluoride, and the molar ratio of the chloroethylene carbonate to the catalyst is preferably 1:(0.001~0.01), more preferably 1:(0.002~0.005), and even more preferably 1:0.003. In the present invention, if there are two catalysts, they are preferably titanium tetrachloride and tungsten hexachloride, and the molar ratio of titanium tetrachloride to tungsten hexachloride is preferably (1~5):1, more preferably 2:1. Alternatively, they are preferably tungsten hexachloride and tin tetrachloride, and the molar ratio of tungsten hexachloride to tin tetrachloride is preferably 1:(1~5), more preferably 1:(2.2~2.3). In the present invention, it is preferable to use at least two catalysts in the composite, which can further improve catalytic activity and further improve the yield of the product.

[0037] In the present invention, the molar ratio of chloroethylene carbonate to liquid hydrogen fluoride is preferably 1:(1-5), more preferably 1:(1-3), and even more preferably 1:1.5, and the liquid hydrogen fluoride is preferably obtained by liquefying anhydrous hydrogen fluoride gas.

[0038] In the present invention, the fluorination reaction is preferably carried out in an autoclave. When the fluorination reaction is carried out in an autoclave, the fluorination reaction is preferably carried out by adding chloroethylene carbonate, a solvent, a catalyst, a polymerization inhibitor, and liquid hydrogen fluoride to the autoclave, then heating, and carrying out the fluorination reaction at a constant temperature and pressure. In specific examples of the present invention, it is preferable to first add chloroethylene carbonate, a solvent, a catalyst, and a polymerization inhibitor to the autoclave, and then add liquid hydrogen fluoride under stirring conditions.

[0039] In the present invention, during the fluorination reaction process, hydrogen chloride gas generated during the reaction is discharged, the discharged hydrogen chloride gas is absorbed with water to prepare by-product hydrochloric acid, and the pressure of the fluorination reaction is controlled by the amount of hydrogen chloride gas discharged. Specifically, it is preferable to control the amount of hydrogen chloride gas discharged by controlling the exhaust gas control valve. During the fluorination reaction process, the generated gaseous hydrogen fluoride and gaseous solvent are condensed and collected, and then returned to the autoclave. The condensation is preferably carried out in a condenser, and the condensed product is preferably collected in a hydrogen fluoride intermediate tank. In the present invention, it is preferable to prepare hydrochloric acid from the discharged hydrogen chloride gas using a method of absorption of a thin film as it flows down, and the condensation is preferably carried out using a condenser. The temperature of the fluorination reaction is preferably 30°C to 80°C, more preferably 60°C to 70°C, the pressure of the fluorination reaction is preferably 0.1 to 1.5 MPa, more preferably 0.3 to 1.5 MPa, and even more preferably 0.6 to 0.8 MPa, and the duration of the fluorination reaction is preferably 3 to 6 hours. In the present invention, by controlling the temperature of the fluorination reaction to 30°C to 80°C, the reaction can proceed efficiently and the occurrence of side reactions can be reduced. If the reaction temperature exceeds 80°C, the amount of by-products increases and the purity of the product decreases. After the fluorination reaction is completed, it is preferable to lower the temperature of the reaction solution to room temperature and return the pressure to atmospheric pressure.

[0040] In the present invention, the reaction equation for the fluorination reaction is as shown in formula A, JPEG2026514265000006.jpg31101 Formula A In the present invention, after the fluorination reaction is completed, it is preferable to mix the obtained reaction solution with a benzotrichloride compound, react the benzotrichloride compound with the remaining hydrogen fluoride in the reaction solution to obtain a mixed reaction solution of fluoroethylene carbonate and a benzotrifluoride compound, distill and desolvate the mixed reaction solution to obtain a concentrated solution and a benzotrifluoride compound, respectively, recycle the benzotrifluoride compound, and sequentially perform rectification and melt crystallization on the concentrated solution to obtain fluoroethylene carbonate.

[0041] In the present invention, the structure of the benzotrichloride compound is preferably as shown in Formula II, JPEG2026514265000007.jpg3328 Formula II, In formula II, n is an integer from 0 to 5, more preferably 0, 1, 2, 3, 4, or 5, and even more preferably 0 or 1, with the same meaning as in formula I, which will not be elaborated here. R is one or more of alkyl groups, phenyl groups, and halogens, more preferably one or more of methyl groups, phenyl groups, F, Cl, Br, and I, and even more preferably one of methyl groups and Cl. In specific examples of the present invention, the benzotrichloride compound is most preferably benzotrichloride, the molar ratio of the benzotrichloride compound to chloroethylene carbonate is preferably (0.1 to 4):1, more preferably (0.5 to 3):1, and even more preferably 1:1, and the reaction equation between the benzotrichloride compound and the remaining hydrogen fluoride in the reaction solution is as shown in formula B. JPEG2026514265000008.jpg32128 Formula B In the present invention, the reaction temperature between the benzotrichloride compound and the remaining hydrogen fluoride in the reaction solution is preferably 20°C to 70°C, more preferably 50°C to 60°C, the pressure is preferably 1 to 2 MPa, more preferably 1.5 to 1.8 MPa, the reaction time is preferably 2 to 3 hours, during the reaction process it is preferable to discharge the hydrogen chloride gas produced during the reaction, and it is preferable to prepare by-product hydrochloric acid from the hydrogen chloride gas by absorption of a thin film as it flows down, the hydrogen fluoride gas produced during the reaction process is condensed by a condenser and collected in an intermediate hydrogen fluoride tank, then returned to the autoclave, and after the hydrogen fluoride in the system is completely consumed and the pressure in the autoclave stops rising, the reaction is considered complete. After the reaction is complete, the present invention prefers to exhaust and reduce the pressure to obtain a mixed reaction solution of fluoroethylene carbonate and the benzotrichloride compound. The present invention does not require any special conditions for the method of distillation and desolvation of the mixed reaction solution, and any method well known to those skilled in the art may be used. In the present invention, the temperature of the rectification vessel for the concentrated liquid is preferably 90°C to 110°C, the top temperature is preferably 60°C to 80°C, the pressure is preferably 15 mmHg or less, more preferably 10 mmHg or less, and the melt crystallization is preferably carried out by lowering the temperature of the product collected after rectification to 18°C ​​to 20°C and crystallizing it for 10 to 16 hours, then releasing the material that has not crystallized, and raising the temperature of the remaining crystallized material to 35°C to 40°C to melt it and obtain a purified fluoroethylene carbonate product, the purity of the purified fluoroethylene carbonate product is 99.95% or higher.

[0042] In the present invention, the fluorination reaction is preferably carried out in a microchannel reactor. When the fluorination reaction is carried out in a microchannel reactor, the fluorination reaction is preferably carried out by mixing chloroethylene carbonate, a catalyst, and a polymerization inhibitor to obtain a mixture, or by mixing chloroethylene carbonate, a catalyst, a polymerization inhibitor, and a solvent to obtain a mixture, and then introducing the mixture and liquid hydrogen fluoride into the microchannel reactor to carry out the fluorination reaction. In the present invention, the ratio of amounts of chloroethylene carbonate, catalyst, polymerization inhibitor, and solvent used is the same as in the above solution and will not be elaborated here. The flow rate of the mixture in the microchannel reactor is preferably 60 to 80 g / min, and the residence time is preferably 20 to 30 min. The flow rate of the liquid hydrogen fluoride in the microchannel reactor is preferably 35 to 45 g / min, and the residence time is preferably 20 to 30 min. The flow rate ratio of chloroethylene carbonate to liquid hydrogen fluoride in the mixture is preferably 6:(1 to 5), more preferably 6:3.5. The temperature of the fluorination reaction is preferably 30°C to 80°C, more preferably 60°C to 70°C. The pressure of the fluorination reaction is preferably 0.1 to 1.5 MPa, more preferably 0.1 to 1.0 MPa, and even more preferably 0.2 to 0.4 MPa. In specific embodiments of the present invention, it is preferable to introduce the liquid hydrogen fluoride and the mixture into the microchannel reactor by a pressurizing pump.

[0043] In the present invention, when the fluorination reaction is carried out in a microchannel reactor, it is preferable to separate the gas-liquid mixture produced by the fluorination reaction to obtain a reaction solution and a mixed gas, the mixed gas containing hydrogen fluoride and hydrogen chloride, the mixed gas being condensed to recover hydrogen fluoride, and the remaining hydrogen chloride being absorbed with water to prepare by-product hydrochloric acid. The absorption method is preferably a flowing thin-film absorption. In the present invention, if the mixed solution does not contain a solvent, it is preferable to directly rectify the reaction solution obtained by the gas-liquid separation and then perform melt crystallization to obtain fluoroethylene carbonate, and if the mixed solution contains a solvent, it is preferable to first distill and desolvent the reaction solution obtained by the gas-liquid separation to obtain a concentrated solution, then rectify the concentrated solution and then perform melt crystallization to obtain fluoroethylene carbonate, the methods of rectification and melt crystallization are consistent with the above solution and will not be elaborated here.

[0044] In the present invention, when the fluorination reaction is carried out in a microchannel reactor, the apparatus used for the fluorination reaction further includes a liquid hydrogen fluoride storage tank 1, a mixed liquid storage tank 2, a gas-liquid separator 4, a condenser 5, a reaction liquid receiving tank 6, and a liquid hydrogen fluoride recovery tank 7, wherein the outlet of the liquid hydrogen fluoride storage tank 1 and the outlet of the mixed liquid storage tank 2 communicate with the inlet of the microchannel reactor 3, the inlet of the gas-liquid separator 4 communicates with the outlet of the microchannel reactor 3, and the inlet of the condenser 5 communicates with the gas outlet of the gas-liquid separator 4. The inlet of the reaction liquid receiving tank 6 is preferably connected to the liquid outlet of the gas-liquid separator 4, the inlet of the liquid hydrogen fluoride recovery tank 7 is preferably connected to the liquid outlet of the condenser 5, a liquid hydrogen fluoride supply pump 8 is preferably installed in the piping connecting the liquid hydrogen fluoride storage tank 1 and the microchannel reactor 3, and a mixed liquid supply pump 9 is preferably installed in the piping connecting the mixed liquid storage tank 2 and the microchannel reactor 3, and both the liquid hydrogen fluoride supply pump 8 and the mixed liquid supply pump 9 are pressurized pumps.

[0045] Figure 1 is a schematic diagram of the apparatus structure when a reaction is carried out using a microchannel reactor in the present invention. The specific reaction process will be described below with reference to Figure 1. Liquid hydrogen fluoride flows out from liquid hydrogen fluoride storage tank 1 and is introduced into microchannel reactor 3 under the action of liquid hydrogen fluoride supply pump 8. The mixed liquid (prepared with chloroethylene carbonate, catalyst and polymerization inhibitor, or prepared with chloroethylene carbonate, catalyst, polymerization inhibitor and solvent) flows out from mixed liquid storage tank 2 and is introduced into microchannel reactor 3 under the action of mixed liquid supply pump 9. The gas-liquid mixture produced by the reaction flows out from the outlet of microchannel reactor 3 and into gas-liquid separator 4. The gas enters the tank and undergoes gas-liquid separation. The liquid produced by the separation is the reaction solution, which flows out from the liquid outlet of the gas-liquid separator 4 and enters the reaction solution receiving tank 6. Subsequently, rectification is performed, and the gas produced by the separation is a mixed gas of hydrogen fluoride and hydrogen chloride. This gas flows out from the gas outlet of the gas-liquid separator 4 and enters the condenser 5 for condensation. The liquid hydrogen fluoride produced by condensation enters the liquid hydrogen fluoride recovery tank 7 and is subsequently recycled. The remaining hydrogen chloride gas is discharged from the gas outlet of the condenser 5 and subsequently absorbed in an exhaust gas absorption tower to prepare hydrochloric acid.

[0046] This invention addresses the problems commonly associated with existing synthesis process routes, such as the large amount of hazardous waste generated, low product yield, and high raw material costs. It provides a method for preparing fluoroethylene carbonate that generates less hazardous waste, has a high yield, and low raw material costs. At the same time, when the fluorination reaction is carried out using a microchannel reactor, continuous automated production can be achieved, significantly improving production efficiency.

[0047] The technical solutions of the present invention will be clearly and completely described below with reference to embodiments of the present invention, and it is clear that the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by those skilled in the art without creative work based on embodiments of the present invention fall within the technical scope of the present invention.

[0048] Example 1 600 g of 95% chloroethylene carbonate (MW122.5, 4.65 mol), 150 g of benzotrifluoride (MW146.1, 1.03 mol), 0.6 g of p-tert-butylcatechol (MW166.2, 0.003 mol), 5 g of titanium tetrachloride (MW189.6, 0.026 mol), and 5 g of tungsten hexachloride (MW396.5, 0.013 mol) were sequentially added to a 2000 mL autoclave, and stirring was started. Then, 280 g of liquid hydrogen fluoride (MW20, 14 mol) was added. After the addition of liquid hydrogen fluoride was completed, the mixture was gradually heated to 60°C to 70°C, and the pressure was controlled to 0.6 to 0.8 MPa for 5 hours to allow the reaction to proceed. Hydrogen chloride gas was discharged while the reaction was in progress, and samples were taken to detect an FEC purity of 90.2%, a CEC purity of 3.8%, and a conversion rate of 95.9%.

[0049] After the reaction was complete, the temperature was lowered to 15°C to 25°C, the system was evacuated to atmospheric pressure, 450 g of benzotrichloride (MW 195.47, 2.30 mol) was added, the pressure was controlled to 1.5 to 1.8 MPa, and the temperature was controlled to 50°C to 60°C. The reaction was maintained at this temperature for 4 hours, and the hydrogen chloride gas produced during the reaction was discharged. After the reaction was complete, the materials were discharged to obtain a mixture of FEC and benzotrifluoride. Next, distillation and desolvation were performed to obtain 470 g of by-product benzotrifluoride with a purity of 99.7% and a molar yield of 95.09%. The concentrate was then rectified at a rectification vessel temperature of 90°C, a top temperature of 60°C, and a pressure of 15 mmHg or less. The product collected after rectification was cooled to 18°C ​​and allowed to crystallize for 10 hours. The uncrystallized material was then released, and the remaining crystallized material was heated to 35°C and melted to obtain approximately 468 g of purified fluoroethylene carbonate with a purity of 99.98% and a molar yield of 95.0%.

[0050] The HPLC spectrum of the fluoroethylene carbonate prepared in this embodiment is shown in Figure 2, and the spectral data is shown in Table 1. (Table 1: Spectral data of HPLC spectra) JPEG2026514265000009.jpg19119 The hydrogen nuclear magnetic resonance spectrum of the fluoroethylene carbonate prepared in this embodiment is shown in Figure 3, and the nuclear magnetic resonance data is: 1The 1H NMR (400 MHz, DMSO) showed δ6.67-6.50 (d, 1H, CH) and 4.79-4.59 (m, 2H, CH2), and Figure 4 shows the carbon nuclear magnetic resonance spectra of the fluoroethylene carbonate prepared in this example.

[0051] Example 2 600 g of 90% chloroethylene carbonate (MW122.5, 4.41 mol), 150 g of benzotrifluoride (MW146.1, 1.03 mol), 0.6 g of p-tert-butylcatechol (MW166.2, 0.003 mol), 5 g of tungsten hexachloride (MW396.5, 0.013 mol), and 6 g of tin tetrachloride (MW206.5, 0.029 mol) were added sequentially to a 2000 mL autoclave, and stirring was started. Then, 280 g of liquid hydrogen fluoride (MW20, 14 mol) was added. After the addition of liquid hydrogen fluoride was completed, the mixture was gradually heated to 60°C to 70°C, and the pressure was controlled to 0.6 to 0.8 MPa for 5 hours to allow the reaction to proceed. Hydrogen chloride gas was discharged while the reaction was in progress, and samples were taken to detect an FEC purity of 91.2%, a CEC purity of 3.0%, and a conversion rate of 96.8%.

[0052] After the reaction was complete, the temperature was lowered to 15°C to 25°C, the system was evacuated to atmospheric pressure, 450 g of benzotrichloride (MW 195.47, 2.30 mol) was added, the pressure was controlled to 1.5 to 1.8 MPa, the temperature was controlled to 50°C to 60°C, and the reaction was maintained at a constant temperature for 3 hours. Hydrogen chloride gas produced during the reaction was discharged, and after the reaction was complete, the materials were discharged to obtain a mixture of FEC and benzotrifluoride. Next, distillation and desolvation were performed to obtain 475 g of by-product benzotrifluoride with a purity of 99.5% and a molar yield of 96.5%. The concentrated solution was further rectified and melt crystallized (the rectification and melt crystallization conditions were the same as those of Example 1) to obtain approximately 445 g of purified fluoroethylene carbonate with a purity of 99.97% and a molar yield of 95.1%.

[0053] Example 3 600 g of 95% chloroethylene carbonate (MW122.5, 4.65 mol), 180 g of p-chlorobenzotrifluoride (MW180.5, 1.0 mol), 0.6 g of p-tert-butylcatechol (MW166.2, 0.003 mol), 5 g of titanium tetrachloride (MW189.6, 0.026 mol), and 5 g of tungsten hexachloride (MW396.5, 0.013 mol) were sequentially added to a 2000 mL autoclave, and stirring was started. Then, 280 g of liquid hydrogen fluoride (MW20, 14 mol) was added. After the addition of liquid hydrogen fluoride was completed, the mixture was gradually heated to 60°C to 70°C, and the pressure was controlled to 0.6 to 0.8 MPa for 5 hours to allow the reaction to proceed. Hydrogen chloride gas was discharged while the reaction was in progress, and samples were taken to detect an FEC purity of 91.2%, a CEC purity of 3.5%, and a conversion rate of 96.3%.

[0054] After the reaction was complete, the temperature was lowered to 15°C to 25°C, the system was evacuated to atmospheric pressure, 530 g of p-chlorobenzotrichloride (MW 229.9, 2.31 mol) was added, the pressure was controlled to 1.5 to 1.8 MPa, and the temperature was controlled to 50°C to 60°C. The reaction was maintained at a constant temperature for 3 hours, and the hydrogen chloride gas produced during the reaction was discharged. After the reaction was complete, the materials were discharged to obtain a mixture of FEC and p-chlorobenzotrifluoride. Next, distillation and desolvation were performed to obtain 570 g of by-product p-chlorobenzotrifluoride with a purity of 99.5% and a molar yield of 95.6%. The concentrated solution was further rectified and melt crystallized (the rectification and melt crystallization conditions were the same as those of Example 1) to obtain approximately 465 g of purified fluoroethylene carbonate with a purity of 99.97% and a molar yield of 94.3%.

[0055] Example 4 6 g of p-tert-butylcatechol (MW 166.2, 0.03 mol), 50 g of titanium tetrachloride (MW 189.6, 0.26 mol), and 50 g of tungsten hexachloride were dissolved in 6000 g of 95% chloroethylene carbonate (MW 122.5, 46.5 mol), and the mixture was placed in a storage tank 2. The jacket heating system of the microchannel reactor 3 was turned on and the temperature was controlled to 60°C to 70°C. At the same time, the mixed liquid supply pump 9 and the liquid hydrogen fluoride supply pump 8 were started, and the flow rate ratio of CEC to liquid hydrogen fluoride was controlled to 6:3.5. Materials were gradually introduced into the microchannel to allow the reaction to proceed, and the pressure of the microchannel reactor 3 was controlled to 0.2 to 0.4 MPa by controlling the opening of the outlet valve. The gas-liquid mixture obtained from the reaction was separated in the gas-liquid separator 4, the resulting mixed gas was condensed in the condenser 5, the excess hydrogen fluoride was put into the liquid hydrogen fluoride recovery tank 7 for reuse, hydrogen chloride was absorbed to prepare by-product hydrochloric acid, the reaction liquid obtained from the gas-liquid separation was put into the reaction liquid receiving tank 6, and after further rectification and melt crystallization (the conditions for rectification and melt crystallization were the same as in Example 1), a purified fluoroethylene carbonate product with a purity of 99.97% and a molar yield of 95.7% was obtained.

[0056] Example 5 In a 2000 mL autoclave, 600 g of 90% chloroethylene carbonate (MW122.5, 4.41 mol), 150 g of benzotrifluoride (MW146.1, 1.03 mol), 0.6 g of p-tert-butylcatechol (MW166.2, 0.003 mol), and 5 g of tungsten hexachloride (MW396.5, 0.013 mol) were sequentially added, and stirring was started. Then, 280 g of liquid hydrogen fluoride (MW20, 14 mol) was added. After the addition of liquid hydrogen fluoride was complete, the mixture was gradually heated to 60°C to 70°C, and the pressure was controlled to 0.6 to 0.8 MPa for 5 hours to allow the reaction to proceed. Hydrogen chloride gas was discharged while the reaction was in progress, and samples were taken. The FEC purity was detected as 84.6%, the CEC purity as 8.9%, and the conversion rate as 90.4% (low conversion rate).

[0057] After the reaction was complete, the temperature was lowered to 15°C to 25°C, the system was evacuated to atmospheric pressure, 450 g of benzotrichloride (MW 195.47, 2.30 mol) was added, the pressure was controlled to 1.5 to 1.8 MPa, and the temperature was controlled to 50°C to 60°C. The reaction was maintained at a constant temperature for 3 to 4 hours, during which the hydrogen chloride gas produced during the reaction was discharged. After the reaction was complete, the materials were discharged to obtain a mixture of FEC and benzotrifluoride. Next, distillation and desolvation were performed to obtain 473 g of by-product benzotrifluoride with a purity of 99.5% and a molar yield of 97.2%. The concentrated solution was rectified and melt crystallized (the rectification and melt crystallization conditions were the same as those of Example 1) to obtain approximately 408 g of purified fluoroethylene carbonate with a purity of 99.95% and a molar yield of 87.3%.

[0058] Comparative Example 1: Using diethyl carbonate as the solvent 600 g of 90% chloroethylene carbonate (MW122.5, 4.41 mol), 120 g of diethyl carbonate (MW118.1, 1.03 mol), 0.6 g of p-tert-butylcatechol (MW166.2, 0.003 mol), 5 g of tungsten hexachloride (MW396.5, 0.013 mol), and 6 g of tin tetrachloride (MW206.5, 0.029 mol) were added sequentially to a 2000 mL autoclave, and stirring was started. Then, 280 g of liquid hydrogen fluoride (MW20, 14 mol) was added. After the addition of liquid hydrogen fluoride was completed, the mixture was gradually heated to 60°C to 70°C, and the pressure was controlled to 0.6 to 0.8 MPa for 5 hours to allow the reaction to proceed. Hydrogen chloride gas was discharged while the reaction was in progress, and samples were taken to detect an FEC purity of 80.1%, a CEC purity of 8.9%, and a conversion rate of 90% (low conversion rate).

[0059] After the reaction was complete, the temperature was lowered to 15°C to 25°C, the system was evacuated to atmospheric pressure, 450 g of benzotrichloride (MW 195.47, 2.32 mol) was added, the pressure was controlled to 1.5 to 1.8 MPa, and the temperature was controlled to 50°C to 60°C. The reaction was maintained at a constant temperature for 3 to 4 hours, during which the hydrogen chloride gas produced during the reaction was discharged. After the reaction was complete, the materials were discharged to obtain a mixture of FEC, benzotrifluoride, and diethyl carbonate. Next, the mixture was distilled and desolvated to obtain 445 g of a mixed solvent of by-product benzotrifluoride and diethyl carbonate. The concentrated solution was further rectified and melt crystallized (the rectification and melt crystallization conditions were the same as those of Example 1) to obtain approximately 402 g of purified fluoroethylene carbonate with a purity of 99.4% (low purity, making it difficult to reach electronic grade purity) and a molar yield of 85.9% (low yield).

[0060] Comparative Example 2: Increase in fluorination reaction temperature 600 g of 90% chloroethylene carbonate (MW122.5, 4.41 mol), 150 g of benzotrifluoride (MW146.1, 1.03 mol), 0.6 g of p-tert-butylcatechol (MW166.2, 0.003 mol), 5 g of tungsten hexachloride (MW396.5, 0.013 mol), and 6 g of tin tetrachloride (MW206.5, 0.029 mol) were added sequentially to a 2000 mL autoclave, and stirring was started. Then, 280 g of liquid hydrogen fluoride (MW20, 14 mol) was added. After the addition of liquid hydrogen fluoride was completed, the mixture was gradually heated to 85°C to 95°C, and the pressure was controlled to 0.6 to 0.8 MPa for 5 hours to allow the reaction to proceed. Hydrogen chloride gas was discharged during the reaction, and samples were taken. The FEC purity was detected as 78.5%, the CEC purity as 1.8%, and the conversion rate as 98.1% (although the conversion rate was high, the purity of the product was low and the amount of by-product impurities increased).

[0061] After the reaction was complete, the temperature was lowered to 15°C to 25°C, the system was evacuated to atmospheric pressure, 450 g of benzotrichloride (MW 195.47, 2.30 mol) was added, the pressure was controlled to 1.5 to 1.8 MPa, and the temperature was controlled to 50°C to 60°C. The reaction was maintained at a constant temperature for 4 hours, and the hydrogen chloride gas produced during the reaction was discharged. After the reaction was complete, the materials were discharged to obtain a mixture of FEC and benzotrifluoride. Next, distillation and desolvation were performed to obtain 470 g of by-product benzotrifluoride with a purity of 99.5% and a molar yield of 96.6%. The concentrated solution was further rectified and melt crystallized (the rectification and melt crystallization conditions were the same as those of Example 1) to obtain approximately 330 g of purified fluoroethylene carbonate with a purity of 99.3% (low product purity) and a molar yield of 70.5% (low product yield due to a large amount of polymer remaining in the distillation vessel because of the high reaction temperature).

[0062] Comparative Example 3: Omission of polymerization inhibitor 600 g of 90% chloroethylene carbonate (MW122.5, 4.41 mol), 150 g of benzotrifluoride (MW146.1, 1.03 mol), 5 g of tungsten hexachloride (MW396.5, 0.013 mol), and 6 g of tin tetrachloride (MW206.5, 0.029 mol) were sequentially added to a 2000 mL autoclave, and stirring was started. Then, 280 g of liquid hydrogen fluoride (MW20, 14 mol) was added. After the addition of liquid hydrogen fluoride was complete, the mixture was gradually heated to 60°C to 70°C, and the pressure was controlled to 0.6 to 0.0 MPa for 5 hours to allow the reaction to proceed. Hydrogen chloride gas was discharged while the reaction was in progress, and samples were taken to detect a FEC purity of 91.2%, a CEC purity of 3.0%, and a conversion rate of 96.8%.

[0063] After the reaction was complete, the temperature was lowered to 15°C-25°C, the system was evacuated to atmospheric pressure, 450 g of benzotrichloride (MW 195.47, 2.30 mol) was added, the pressure was controlled to 1.5-1.8 MPa, and the temperature was controlled to 50°C-60°C. The reaction was maintained at this temperature for 3 hours, and the hydrogen chloride gas produced during the reaction was discharged. After the reaction was complete, the materials were discharged to obtain a mixture of FEC and benzotrifluoride. Next, distillation and desolvation were performed to obtain 464 g of by-product benzotrifluoride with a purity of 99.5% and a molar yield of 95.4%. The concentrated solution was further rectified and melt crystallized (the rectification and melt crystallization conditions were the same as in Example 1) to obtain approximately 363 g of purified fluoroethylene carbonate with a purity of 99.97% and a molar yield of 77.5%. (Partial polymerization occurred because no polymerization inhibitor was added, resulting in a low yield).

[0064] Comparative Example 4: Omission of Catalyst 600 g of 90% chloroethylene carbonate (MW122.5, 4.41 mol), 150 g of benzotrifluoride (MW146.1, 1.03 mol), and 0.6 g of p-tert-butylcatechol (MW166.2, 0.003 mol) were sequentially added to a 2000 mL autoclave, and stirring was started. Then, 280 g of liquid hydrogen fluoride (MW20, 14 mol) was added. After the addition of liquid hydrogen fluoride was complete, the mixture was gradually heated to 60°C to 70°C, and the pressure was controlled to 0.6 to 0.8 MPa for 5 hours to allow the reaction to proceed. Hydrogen chloride gas was discharged while the reaction was in progress, and samples were taken to detect a FEC purity of 56.6%, a CEC purity of 35.3%, and a conversion rate of 61.6%.

[0065] After the reaction was complete, the temperature was lowered to 15°C-25°C, the system was evacuated to atmospheric pressure, 450g of benzotrichloride (MW 195.47, 2.30 mol) was added, the pressure was controlled to 1.5-1.8 MPa, and the temperature was controlled to 50°C-60°C. The reaction was maintained at this temperature for 3 hours, and the hydrogen chloride gas produced during the reaction was discharged. After the reaction was complete, the materials were discharged to obtain a mixture of FEC and benzotrifluoride. Next, distillation and desolvation were performed to obtain 473g of by-product benzotrifluoride with a purity of 99.5% and a molar yield of 97.2%. The concentrated solution was rectified and melt crystallized (the rectification and melt crystallization conditions were the same as in Example 1), yielding approximately 235g of fluoroethylene carbonate product with a purity of 99.2% and a molar yield of 50.2%. (Because no catalyst was used, the conversion rate was low, there was a large amount of raw material residue, and the purity of the product was unacceptable).

[0066] Based on the above, the method for preparing fluoroethylene carbonate provided by the present invention has a high conversion rate, high yield and purity of the product, low raw material costs, low generation of hazardous waste, ease of realizing continuous automated production, and offers broad prospects.

[0067] The foregoing are merely preferred embodiments of the present invention, and those skilled in the art can make some improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should be considered within the scope of protection. [Explanation of symbols]

[0068] In Figure 1: 1. Liquid hydrogen fluoride storage tank 2. Mixed liquid storage tank 3 Microchannel Reactor 4 Gas-liquid separator 5. Condenser 6. Reaction solution receiving tank 7. Liquid hydrogen fluoride recovery tank 8. Liquid Hydrogen Fluoride Supply Pump 9. Mixture supply pump

Claims

1. A method for preparing fluoroethylene carbonate, A method for preparing fluoroethylene carbonate, comprising the step of mixing chloroethylene carbonate, a polymerization inhibitor, a catalyst, and liquid hydrogen fluoride to carry out a fluorination reaction to obtain fluoroethylene carbonate, wherein the catalyst comprises one or more of metal fluorides, metal chlorides, and tetrabutylammonium fluoride, and the polymerization inhibitor comprises one or more of amine-based polymerization inhibitors, phenol-based polymerization inhibitors, and piperidinyl nitrooxide radical-based polymerization inhibitors.

2. A solvent is also added during the mixing process, and the solvent is a benzotrifluoride compound, the structural formula of which is shown in formula I. 【Chemistry 1】 Equation I, In formula I, n is an integer from 0 to 5, and R is one or more of alkyl groups, phenyl groups, and halogens. The preparation method according to claim 1, characterized in that the molar ratio of chloroethylene carbonate to solvent is 1:(0.2 to 2).

3. The preparation method according to claim 2, characterized in that the benzotrifluoride compound is benzotrifluoride or p-chlorobenzotrifluoride.

4. The preparation method according to claim 2, characterized in that the fluorination reaction is carried out in an autoclave.

5. The fluorination reaction involves adding chloroethylene carbonate, a solvent, a catalyst, a polymerization inhibitor, and liquid hydrogen fluoride to an autoclave, and then heating the mixture to carry out the fluorination reaction under constant temperature and pressure conditions. The preparation method according to claim 4, characterized in that, in the fluorination reaction process, hydrogen chloride gas generated during the reaction is discharged, the discharged hydrogen chloride gas is absorbed with water to prepare by-product hydrochloric acid, the pressure of the fluorination reaction is controlled by controlling the discharge of hydrogen chloride gas, and in the fluorination reaction process, the generated gaseous hydrogen fluoride and gaseous solvent are collected after condensation and then returned to the autoclave.

6. The process includes: mixing the resulting reaction solution with a benzotrichloride compound after the fluorination reaction is completed; reacting the benzotrichloride compound with the remaining hydrogen fluoride in the reaction solution to obtain a mixed reaction solution of fluoroethylene carbonate and a benzotrifluoride compound; distilling and desolvating the mixed reaction solution to obtain a concentrated solution and a benzotrifluoride compound, respectively; recycling the benzotrifluoride compound obtained by distillation and desolvation; and sequentially performing rectification and melt crystallization on the concentrated solution to obtain a fluoroethylene carbonate product. The structure of the aforementioned benzotrichloride compound is shown in formula II. 【Chemistry 2】 Formula II, The preparation method according to claim 5, characterized in that, in formula II, n is an integer from 0 to 5, and R is one or more of an alkyl group, a phenyl group, and a halogen.

7. The preparation method according to claim 1 or 2, characterized in that the fluorination reaction is carried out in a microchannel reactor.

8. The fluorination reaction described above is The process involves mixing chloroethylene carbonate, a catalyst, and a polymerization inhibitor to obtain a mixture, or mixing chloroethylene carbonate, a catalyst, a polymerization inhibitor, and a solvent to obtain a mixture. The preparation method according to claim 7, characterized in that it includes introducing the aforementioned mixture and liquid hydrogen fluoride into a microchannel reactor to carry out a fluorination reaction.

9. The preparation method according to claim 8, characterized in that the flow rate ratio of chloroethylene carbonate to liquid hydrogen fluoride in the mixture is 6:(1-5).

10. The preparation method according to claim 8, further comprising: separating the gas-liquid mixture generated after the fluorination reaction to obtain a reaction solution and a mixed gas containing hydrogen fluoride and hydrogen chloride; condensing the mixed gas to recover hydrogen fluoride and absorbing the remaining hydrogen chloride with water to prepare hydrochloric acid.

11. The apparatus used in the fluorination reaction further includes a liquid hydrogen fluoride storage tank (1), a mixed liquid storage tank (2), a gas-liquid separator (4), a condenser (5), a reaction liquid receiving tank (6), and a liquid hydrogen fluoride recovery tank (7). The outlet of the liquid hydrogen fluoride storage tank (1) and the outlet of the mixed liquid storage tank (2) are connected to the inlet of the microchannel reactor (3). The inlet of the gas-liquid separator (4) is in communication with the outlet of the microchannel reactor (3), The inlet of the condenser (5) is connected to the gas outlet of the gas-liquid separator (4), The inlet of the reaction liquid receiving tank (6) is connected to the liquid outlet of the gas-liquid separator (4), The preparation method according to claim 7, characterized in that the inlet of the liquid hydrogen fluoride recovery tank (7) is connected to the liquid outlet of the condenser (5).

12. The preparation method according to claim 1, characterized in that the temperature of the fluorination reaction is 30°C to 80°C and the pressure is 0.1 to 1.5 MPa.

13. The polymerization inhibitor comprises one or more of phenothiazine, polymerization inhibitor 701, p-tert-butylcatechol, hydroquinone, diphenylamine, and polymerization inhibitor 705. The molar ratio of the chloroethylene carbonate to the polymerization inhibitor is 1:(0.0001 to 0.001). The preparation method according to claim 1, characterized in that the molar ratio of chloroethylene carbonate to liquid hydrogen fluoride is 1:(1 to 5).

14. The preparation method according to claim 13, characterized in that the catalyst comprises one or more of potassium fluoride, ferric chloride, antimony trichloride, tungsten hexachloride, antimony pentachloride, tin tetrachloride, titanium tetrachloride, and tetrabutylammonium fluoride, and the molar ratio of the chloroethylene carbonate to the catalyst is 1:(0.001 to 0.01).

15. The preparation method according to claim 14, characterized in that the catalyst is titanium tetrachloride and tungsten hexachloride, and the molar ratio of titanium tetrachloride to tungsten hexachloride is (1 to 5):1, or the catalyst is tungsten hexachloride and tin tetrachloride, and the molar ratio of tungsten hexachloride to tin tetrachloride is 1:(1 to 5).

16. The preparation method according to claim 6, characterized in that the temperature of the rectification vessel is 90°C to 110°C, the top temperature is 60°C to 80°C, the pressure is 15 mmHg or less, and the melt crystallization includes lowering the temperature of the product collected after rectification to 18°C ​​to 20°C, allowing it to crystallize for 10 to 16 hours, then releasing the material that has not crystallized, and raising the temperature of the remaining crystallized material to 35°C to 40°C to melt it, thereby obtaining a purified fluoroethylene carbonate product.

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