A method for preparing fluoroethylene carbonate

Abstract

This invention relates to the field of lithium-ion battery electrolyte additive synthesis technology, and provides a method for preparing fluoroethylene carbonate. The invention involves mixing chloroethylene carbonate, a polymerization inhibitor, a catalyst, and liquid hydrogen fluoride for a fluorination reaction to obtain fluoroethylene carbonate. The simultaneous addition of a polymerization inhibitor and a catalyst avoids side reactions such as material polymerization while increasing the reaction rate, thereby improving conversion rate and product yield. The use of liquid hydrogen fluoride as the fluorinating agent is low-cost, convenient, and suitable for continuous production. The use of trifluorotoluene-based compounds as a solvent and the effective utilization of residual hydrogen fluoride through trichlorotoluene-based compounds facilitate resource utilization and reduce production costs. The fluorination reaction can be carried out in a microchannel reactor, enabling continuous and automated production. In summary, the preparation method provided by this invention is efficient, economical, and environmentally friendly, with broad prospects.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery electrolyte additive synthesis technology, and in particular to a method for preparing fluoroethylene carbonate. Background Technology

[0002] Lithium-ion batteries consist of a positive electrode, a negative electrode, a separator, and an electrolyte. The electrolyte, often referred to as the "blood" of a lithium-ion battery, plays a crucial role in conducting electrons between the positive and negative electrodes. The manufacturing cost of the electrolyte accounts for 14% of the total cost of a lithium battery, making it the most expensive component after the positive electrode material. The electrolyte is formulated from solvents, solutes (i.e., lithium salts), and additives in specific proportions. Typically, the solvent accounts for 80-90%, the lithium salt for about 8%, and the additives for 5-0%. In terms of manufacturing costs, the solute is the most expensive, accounting for nearly 50%, the solvent for about 30%, and the additives for about 10%. There are many types of additives, each with different functions, such as improving conductivity, overcharge safety, storage performance, flame retardancy, and stability. Different lithium-ion battery manufacturers have different requirements for battery applications and performance, leading to varying focuses in their additive selection. As battery performance requirements increase, the importance of additives becomes even more pronounced.

[0003] Fluorinated ethylene carbonate is an organic film-forming additive and overcharge protection additive for lithium-ion battery electrolytes. It has good high and low temperature performance and anti-gas expansion function, which can improve the capacity and cycle life of lithium-ion batteries.

[0004] The main methods for producing fluoroethylene carbonate are as follows:

[0005] US Patent 6010806 discloses a method for reacting dimethyl carbonate and 3,3,3-trifluoro-1,2-propylene oxide in the presence of sodium bicarbonate. This method uses expensive raw materials and has a long reaction time, making it unsuitable for industrial production. Patent CN108250176A provides a rapid continuous flow synthesis process for fluoroethylene carbonate, which uses a mixture of F2 / N2 gas to react with ethylene carbonate. F2 is highly toxic and reactive, prone to runaway, posing a high risk, and produces many byproduct impurities that are difficult to separate and purify, resulting in high production costs. Patent WO98115024 uses chloroethylene carbonate and potassium fluoride as raw materials. This method is relatively mature in the domestic industry, but it is a heterogeneous reaction, time-consuming, with low conversion rates. It requires high particle size and activity of solid potassium fluoride, which is expensive. The large-scale use of solid potassium fluoride leads to high labor intensity, is difficult to automate, and generates a large amount of mixed potassium chloride and potassium fluoride solid waste, resulting in high waste costs. Patent CN101774923B discloses a method for preparing fluoroethylene carbonate, which involves a substitution reaction between chloroethylene carbonate and a fluorinating agent in the presence of an organic solvent and an acid-binding agent to produce fluoroethylene carbonate. This method increases costs due to the use of a solvent, has a cumbersome post-processing procedure, and a low yield of only about 85%. Patents CN105968083A and CN114874179A disclose a method for preparing fluoroethylene carbonate, which uses hydrogen fluoride as a fluorine source and a microchannel to prepare the fluoroethylene carbonate. Repeated experiments have verified that this method has very limited actual conversion and product yield, failing to meet the conditions for industrial application. Patent CN116178333A discloses a method for preparing fluoroethylene carbonate using chloroethylene carbonate as raw material, hydrogen fluoride as fluorine source, and a mixture of SbCl5 and MoCl5 in a certain proportion as catalyst. However, due to the high level of by-product impurities in this method, the product yield and quality are not guaranteed. The yield is less than 85%, and the product purity is less than 99.5%, which is far below the 99.95% requirement for electronic-grade lithium battery additives.

[0006] In summary, existing preparation methods generally suffer from low conversion rates and product yields, low product purity, and high costs, making them unsuitable for industrial production. Summary of the Invention

[0007] In view of this, the present invention provides a method for preparing fluoroethylene carbonate. The preparation method provided by the present invention has high raw material conversion rate, high product yield and purity, and low preparation cost.

[0008] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0009] A method for preparing fluoroethylene carbonate includes the following steps:

[0010] A fluorination reaction is carried out by mixing chloroethylene carbonate, a polymerization inhibitor, a catalyst, and liquid hydrogen fluoride to obtain fluoroethylene carbonate; the catalyst includes one or more of metal fluorides, metal chlorides, and tetrabutylammonium fluoride; the polymerization inhibitor includes one or more of amine polymerization inhibitors, phenolic polymerization inhibitors, and piperidine nitroxide radical polymerization inhibitors.

[0011] Preferably, a solvent is also added during the mixing process, and the solvent is a trifluorotoluene compound; the structural formula of the trifluorotoluene compound is shown in Formula I:

[0012]

[0013] In Formula I: n is an integer from 0 to 5, and R is one or more of alkyl, phenyl, and halogen;

[0014] The molar ratio of the chloroethylene carbonate to the solvent is 1:(0.2-2).

[0015] Preferably, the fluorination reaction is carried out in an autoclave.

[0016] Preferably, the fluorination reaction includes: adding chloroethylene carbonate, solvent, catalyst, polymerization inhibitor and liquid hydrogen fluoride into a high-pressure reactor, and then heating to carry out the fluorination reaction under certain temperature and pressure conditions;

[0017] During the fluorination reaction, hydrogen chloride gas generated is discharged while the reaction is underway. The discharged hydrogen chloride gas is absorbed by water to produce hydrochloric acid as a byproduct. The pressure of the fluorination reaction is controlled by the amount of hydrogen chloride gas discharged. During the fluorination reaction, the gaseous hydrogen fluoride and gaseous solvent generated are condensed, collected, and returned to the autoclave.

[0018] Preferably, after the fluorination reaction is completed, the process further includes mixing the obtained reaction solution with a trichlorotoluene-based compound, wherein the trichlorotoluene-based compound reacts with the remaining hydrogen fluoride in the reaction solution to obtain a mixed reaction solution of fluoroethylene carbonate and trichlorotoluene-based compound; the mixed reaction solution is distilled to remove solvent and obtain a concentrated solution and a trichlorotoluene-based compound; the trichlorotoluene-based compound is recycled; the concentrated solution is then subjected to fractional distillation and melt crystallization to obtain the fluoroethylene carbonate product;

[0019] The structure of the trichlorotoluene-like compounds is shown in Formula II:

[0020]

[0021] In Formula II: n is an integer from 0 to 5, and R is one or more of alkyl, phenyl, and halogen.

[0022] Preferably, the fluorination reaction is carried out in a microchannel reactor.

[0023] Preferably, the fluorination reaction includes:

[0024] A mixture is obtained by mixing chloroethylene carbonate, a catalyst, and a polymerization inhibitor; or a mixture is obtained by mixing chloroethylene carbonate, a catalyst, a polymerization inhibitor, and a solvent.

[0025] The mixture and liquid hydrogen fluoride are introduced into a microchannel reactor to carry out the fluorination reaction.

[0026] Preferably, the fluorination reaction further includes: performing gas-liquid separation on the generated gas-liquid mixture to obtain a reaction liquid and a mixed gas; the mixed gas includes hydrogen fluoride and hydrogen chloride; the mixed gas is condensed to recover hydrogen fluoride, and the remaining hydrogen chloride is absorbed with water to prepare hydrochloric acid.

[0027] 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 liquid receiving tank 6, and a liquid hydrogen fluoride recovery tank 7.

[0028] 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.

[0029] The inlet of the gas-liquid separator 4 is connected to the outlet of the microchannel reactor 3;

[0030] The inlet of the condenser 5 is connected to the gas outlet of the gas-liquid separator 4;

[0031] The inlet of the reaction liquid receiving tank 6 is connected to the liquid outlet of the gas-liquid separator 4;

[0032] The inlet of the liquid hydrogen fluoride recovery tank 7 is connected to the liquid outlet of the condenser 5.

[0033] Preferably, the fluorination reaction is carried out at a temperature of 30°C to 80°C and a pressure of 0.1 to 1.5 MPa.

[0034] Preferably, the polymerization inhibitor includes one or more of phenothiazine, polymerization inhibitor 701, p-tert-butylcatechol, hydroquinone, diphenylamine, and polymerization inhibitor 705;

[0035] The molar ratio of the chloroethylene carbonate to the polymerization inhibitor is 1:(0.0001~0.001);

[0036] The molar ratio of the chloroethylene carbonate to liquid hydrogen fluoride is 1:(1-5).

[0037] 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; the molar ratio of ethylene chlorocarbonate to the catalyst is 1:(0.001-0.01).

[0038] Preferably, the distillation vessel temperature is 90℃~110℃, the top temperature is 60℃~80℃, and the pressure is below 15mmHg; the melting crystallization includes: cooling the product collected after distillation to 18℃~20℃, crystallizing for 10~16h, then releasing the uncrystallized material, and heating the remaining crystalline material to 35℃~40℃ for melting to obtain high-quality fluoroethylene carbonate.

[0039] This invention provides a method for preparing fluoroethylene carbonate, comprising the following steps: mixing chloroethylene carbonate (CEC), a polymerization inhibitor, a catalyst, and liquid hydrogen fluoride to carry out a fluorination reaction to obtain fluoroethylene carbonate (FEC); the catalyst comprises one or more of metal fluorides, metal chlorides, and tetrabutylammonium fluoride; the polymerization inhibitor comprises one or more of amine polymerization inhibitors, phenolic polymerization inhibitors, and piperidine nitroxide radical polymerization inhibitors. This invention simultaneously incorporates a polymerization inhibitor and a catalyst in the fluorination reaction, thereby increasing the reaction rate and thus improving the conversion rate and product yield while avoiding side reactions such as material polymerization. Example results show that the molar yield of fluoroethylene carbonate produced by this invention can reach over 90%, and the product purity can reach over 99.95%. Furthermore, this invention uses liquid hydrogen fluoride as the fluorinating agent. Compared with fluorinating agents such as potassium fluoride and fluorine gas, liquid hydrogen fluoride is cheaper, safer, easier to use, and easier to automate, reducing the labor intensity of workshop workers and lowering production costs. At the same time, liquid hydrogen fluoride has higher mass transfer efficiency than gaseous hydrogen fluoride, which is beneficial for improving the conversion rate and product yield.

[0040] Furthermore, this invention uses trifluorotoluene compounds as solvents for the fluorination reaction. Trifluorotoluene compounds are highly stable, do not easily decompose, and will not interfere with the fluorination reaction. At the same time, they have excellent solubility, which can dissolve the small amount of polymer generated in the reaction, preventing the polymer from sticking to the walls or clogging the pipes, thereby improving the yield and purity of the product. In addition, trifluorotoluene compounds are easy to separate and recover, and can be recycled, which is conducive to further reducing production costs.

[0041] Furthermore, after the fluorination reaction is completed, the present invention adds a trichlorotoluene-like compound to the reaction solution to react with the remaining hydrogen fluoride in the system. This not only effectively utilizes the excess hydrogen fluoride to prepare trichlorotoluene-like compounds, but also avoids the need for alkali neutralization to remove hydrogen fluoride in the post-processing, greatly reducing production costs.

[0042] Furthermore, the hydrogen chloride gas generated during the reaction process can be absorbed by water to prepare hydrochloric acid as a byproduct, thus realizing the utilization of waste gas and achieving significant economic benefits.

[0043] Furthermore, the amount of catalyst used in this invention is very small, only 0.1% to 1% of the molar amount of ethylene chloride carbonate. The main reasons are as follows: by using the polymerization inhibitor and the catalyst together, the polymerization inhibitor can greatly reduce the formation of polymers. The catalyst cannot dissolve in the reaction system, and if a large amount of polymer is generated, it will encapsulate the catalyst and affect the catalytic effect. This invention can improve the catalytic activity by using the polymerization inhibitor and the catalyst together. The above reasons enable the catalyst to be used in this invention to be greatly reduced. Since catalysts are generally relatively expensive, this invention reduces the amount of catalyst used, thereby greatly reducing the production cost.

[0044] Furthermore, the present invention uses a microchannel reactor for fluorination reaction, which can realize continuous and automated production, greatly reducing operational risks and improving safety.

[0045] Furthermore, the present invention reduces the generation of side-reaction polymers due to the use of polymerization inhibitors during the reaction process, thus generating less hazardous waste. Attached Figure Description

[0046] Figure 1 This is a schematic diagram of the device structure for using a microchannel reactor in this invention. Figure 1 In the middle: 1-Liquid hydrogen fluoride storage tank, 2-Mixed liquid storage tank, 3-Microchannel reactor, 4-Gas-liquid separator, 5-Condenser 5, 6-Reaction liquid receiving tank, 7-Liquid hydrogen fluoride recovery tank, 8-Liquid hydrogen fluoride feed pump, 9-Mixed liquid feed pump 9;

[0047] Figure 2 The HPLC chromatogram of the fluoroethylene carbonate prepared in Example 1;

[0048] Figure 3 The 1H NMR spectrum of the fluoroethylene carbonate prepared in Example 1;

[0049] Figure 4 The carbon NMR spectrum of the fluoroethylene carbonate prepared in Example 1. Detailed Implementation

[0050] This invention provides a method for preparing fluoroethylene carbonate, comprising the following steps:

[0051] A fluorination reaction is carried out by mixing chloroethylene carbonate, a polymerization inhibitor, a catalyst, and liquid hydrogen fluoride to obtain fluoroethylene carbonate; the catalyst includes one or more of metal fluorides, metal chlorides, and tetrabutylammonium fluoride; the polymerization inhibitor includes one or more of amine polymerization inhibitors, phenolic polymerization inhibitors, and piperidine nitroxide radical polymerization inhibitors.

[0052] In this invention, a solvent is preferably added during the mixing process, and the solvent is preferably a trifluorotoluene compound; the structural formula of the trifluorotoluene compound is preferably shown in Formula I:

[0053]

[0054] 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 on the benzene ring. When n is greater than 1, the R groups can be the same or different. R is one or more of alkyl, phenyl and halogen, and the number of carbon atoms of the alkyl group is preferably 1 to 10, more preferably 1 to 5. Specifically, R is more preferably one or more of methyl, phenyl, F, Cl, Br and I. In a specific embodiment of the present invention, the trifluorotoluene compound is preferably trifluorotoluene (i.e., n is 0), or preferably a compound with the structure shown in Formula I-1.

[0055]

[0056] In Formula I-1: R is preferably one of methyl and Cl.

[0057] In a specific embodiment of the present invention, the solvent is most preferably trifluorotoluene or p-chlorotrifluorotoluene.

[0058] In this invention, the molar ratio of the chloroethylene carbonate to the solvent is preferably 1:(0.2-2), more preferably 1:(0.2-1.5), and even more preferably 1:0.22; the purity of the chloroethylene carbonate is preferably 90wt%-95wt%.

[0059] In this invention, the polymerization inhibitor preferably includes one or more of phenothiazine, polymerization inhibitor 701, p-tert-butylcatechol, hydroquinone, diphenylamine, and polymerization inhibitor 705; the molar ratio of ethylene chloride carbonate to the 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 includes one or more of metal fluorides, metal chlorides, and tetrabutylammonium fluoride, preferably at least two; specifically, the catalyst preferably includes potassium fluoride, ferric chloride, antimony trichloride, tungsten hexachloride, antimony pentachloride, tin tetrachloride, and tetrabutylammonium chloride. The catalyst comprises one or more of titanium chloride and tetrabutylammonium fluoride, more preferably at least two; 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 this invention, when the catalyst is of two types, it is preferably titanium tetrachloride and tungsten hexachloride, and the molar ratio of titanium tetrachloride and tungsten hexachloride is preferably (1-5):1, more preferably 2:1; or preferably tungsten hexachloride and tin tetrachloride, and the molar ratio of tungsten hexachloride and tin tetrachloride is preferably 1:(1-5), more preferably 1:(2.2-2.3). This invention preferably uses at least two catalysts in combination, which can further enhance catalytic activity and thus improve product yield.

[0060] In this invention, the molar ratio of the chloroethylene carbonate and liquid hydrogen fluoride is preferably 1:(1-5), more preferably 1:(1-3), and even more preferably 1:1.5; the liquid hydrogen fluoride is preferably obtained by liquefying anhydrous hydrogen fluoride gas.

[0061] In this invention, the fluorination reaction is preferably carried out in an autoclave; when the fluorination reaction is carried out in an autoclave, the fluorination reaction preferably includes: adding ethylene chlorocarbonate, solvent, catalyst, polymerization inhibitor and liquid hydrogen fluoride to the autoclave, and then heating to carry out the fluorination reaction at a certain temperature and pressure; in a specific embodiment of this invention, it is preferable to first add ethylene chlorocarbonate, solvent, catalyst and polymerization inhibitor to the autoclave, and then add liquid hydrogen fluoride under stirring conditions.

[0062] In this invention, during the fluorination reaction, the generated hydrogen chloride gas is discharged simultaneously with the reaction. The discharged hydrogen chloride gas is absorbed by water to prepare hydrochloric acid as a byproduct. The pressure of the fluorination reaction is preferably controlled by the discharge rate of hydrogen chloride gas, specifically by controlling the discharge rate of hydrogen chloride gas through a tail gas regulating valve. During the fluorination reaction, the generated gaseous hydrogen fluoride and gaseous solvent are condensed, collected, and 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 this invention, the discharged hydrogen chloride gas is preferably used to prepare hydrochloric acid by falling film absorption. The condensation is preferably carried out using a condenser. The temperature of the fluorination reaction is preferably 30℃~80℃, more preferably 60℃~70℃. The pressure of the fluorination reaction is preferably 0.1~1.5MPa, more preferably 0.3~1.5MPa, and even more preferably 0.6~0.8MPa. The time of the fluorination reaction is preferably 3~6 hours. This invention controls the fluorination reaction temperature to 30℃~80℃, which enables the reaction to proceed efficiently and reduces the occurrence of side reactions. If the reaction temperature exceeds 80℃, the amount of by-products will increase and the purity of the product will decrease. After the fluorination reaction is completed, it is preferable to cool the reaction solution to room temperature and restore the pressure to atmospheric pressure.

[0063] In this invention, the reaction formula for the fluorination reaction is shown in Formula A:

[0064]

[0065] In this invention, after the fluorination reaction is completed, the resulting reaction solution is preferably mixed with a trichlorotoluene-based compound. The trichlorotoluene-based compound reacts with the remaining hydrogen fluoride in the reaction solution to obtain a mixed reaction solution of fluoroethylene carbonate and trichlorotoluene-based compound. The mixed reaction solution is then distilled to remove solvent, yielding a concentrated solution and a trichlorotoluene-based compound. The trichlorotoluene-based compound is recycled. The concentrated solution is then subjected to distillation and melt crystallization to obtain fluoroethylene carbonate.

[0066] In this invention, the structure of the trichlorotoluene compound is preferably as shown in Formula II:

[0067]

[0068] 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. The meaning of n is the same as in Formula I, and will not be repeated here. R is one or more of alkyl, phenyl and halogen, more preferably one or more of methyl, phenyl, F, Cl, Br and I, and even more preferably one of methyl and Cl. In a specific embodiment of the present invention, the trichlorotoluene compound is most preferably trichlorotoluene; the molar ratio of the trichlorotoluene compound and chloroethylene carbonate is preferably (0.1-4):1, more preferably (0.5-3):1, and even more preferably 1:1; the reaction formula of the trichlorotoluene compound and the remaining hydrogen fluoride in the reaction solution is shown in Formula B:

[0069]

[0070] In this invention, the preferred temperature for the reaction of the trichlorotoluene compound with the remaining hydrogen fluoride in the reaction solution is 20°C to 70°C, more preferably 50°C to 60°C; the preferred pressure is 1 to 2 MPa, more preferably 1.5 to 1.8 MPa; and the preferred reaction time is 2 to 3 hours. During the reaction, the generated hydrogen chloride gas is preferably discharged while the reaction is proceeding, and the hydrogen chloride gas is preferably absorbed through a falling film to prepare hydrochloric acid as a byproduct. The generated hydrogen fluoride gas is condensed by a condenser and collected in a hydrogen fluoride intermediate tank, and then returned to the autoclave. When the hydrogen fluoride in the system is completely consumed and the pressure inside the autoclave no longer rises, the reaction is considered complete. After the reaction is complete, this invention preferably depressurizes the gas to obtain a mixed reaction solution of fluoroethylene carbonate and trichlorotoluene compound. The present invention does not have special requirements for the distillation and desolvation method of the mixed reaction solution; any method well known to those skilled in the art can be used. In the present invention, the preferred kettle temperature for the distillation of the concentrated solution is 90℃~110℃, the preferred top temperature is 60℃~80℃, and the preferred pressure is below 15mmHg, more preferably below 10mmHg. The melting and crystallization preferably includes: cooling the product collected after distillation to 18℃~20℃, crystallizing for 10~16h, then releasing the uncrystallized material, and heating the remaining crystalline material to 35℃~40℃ for melting to obtain the refined fluoroethylene carbonate; the purity of the refined fluoroethylene carbonate is above 99.95%.

[0071] In this 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 preferably includes: mixing ethylene chlorocarbonate, a catalyst and a polymerization inhibitor to obtain a mixture; or mixing ethylene chlorocarbonate, a catalyst and a polymerization inhibitor and a solvent to obtain a mixture; and passing the mixture and liquid hydrogen fluoride into the microchannel reactor to carry out the fluorination reaction. In this invention, the ratio of ethylene chlorocarbonate, catalyst, polymerization inhibitor, and solvent is the same as in the above-described scheme and will not be repeated here. The flow rate of the mixture in the microchannel reactor is preferably 60-80 g / min, and the residence time is preferably 20-30 min. The flow rate of the liquid hydrogen fluoride in the microchannel reactor is preferably 35-45 g / min, and the residence time is preferably 20-30 min. The flow ratio of ethylene chlorocarbonate to liquid hydrogen fluoride in the mixture is preferably 6:(1-5), more preferably 6:3.5. The temperature of the fluorination reaction is preferably 30℃-80℃, more preferably 60℃-70℃. The pressure of the fluorination reaction is preferably 0.1-1.5 MPa, more preferably 0.1-1.0 MPa, and even more preferably 0.2-0.4 MPa. In a specific embodiment of this invention, it is preferable to introduce the liquid hydrogen fluoride and the mixture into the microchannel reactor using a pressure pump.

[0072] In this invention, when the fluorination reaction is carried out in a microchannel reactor, the gas-liquid mixture produced by the fluorination reaction is preferably subjected to gas-liquid separation to obtain a reaction liquid and a mixed gas; the mixed gas includes hydrogen fluoride and hydrogen chloride; the mixed gas is condensed to recover hydrogen fluoride, and the remaining hydrogen chloride is absorbed with water to prepare hydrochloric acid as a byproduct; the absorption method is preferably falling film absorption; in this invention, when the mixture does not contain a solvent, the reaction liquid obtained from the gas-liquid separation is preferably directly distilled and then melt-crystallized to obtain fluoroethylene carbonate; when the mixture includes a solvent, the reaction liquid obtained from the gas-liquid separation is preferably first distilled to remove the solvent, to obtain a concentrated liquid, and then the concentrated liquid is distilled and then melt-crystallized to obtain fluoroethylene carbonate; the distillation and melt-crystallization methods are the same as those described above and will not be repeated here.

[0073] In this invention, when the fluorination reaction is carried out in a microchannel reactor, the apparatus 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; 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 connected to 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 inlet of the liquid hydrogen fluoride recovery tank 7 is connected to the liquid outlet of the condenser 5; preferably, a liquid hydrogen fluoride feed pump 8 is installed on the pipeline connecting the liquid hydrogen fluoride storage tank 1 and the microchannel reactor 3, and preferably, a mixed liquid feed pump 9 is installed on the pipeline connecting the mixed liquid storage tank 2 and the microchannel reactor 3; both the liquid hydrogen fluoride feed pump 8 and the mixed liquid feed pump 9 are pressure pumps.

[0074] Figure 1 This is a schematic diagram of the device structure for using a microchannel reactor in this invention. The following is a description of the device structure. Figure 1 The specific reaction process is as follows: Liquid hydrogen fluoride flows out from liquid hydrogen fluoride storage tank 1 and is fed into microchannel reactor 3 by liquid hydrogen fluoride feed pump 8. The mixture (prepared from ethylene chlorocarbonate, catalyst, and polymerization inhibitor, or prepared from ethylene chlorocarbonate, catalyst, polymerization inhibitor, and solvent) flows out from mixture storage tank 2 and is fed into microchannel reactor 3 by mixture feed pump 9. The gas-liquid mixture produced by the reaction flows out from the outlet of microchannel reactor 3 and enters gas-liquid separator 4 for gas-liquid separation. The liquid produced by separation is the reaction liquid, which flows out from the liquid outlet of gas-liquid separator 4 and enters reaction liquid receiving tank 6 for subsequent distillation and purification. The gas produced by separation is a mixture of hydrogen fluoride and hydrogen chloride, which flows out from the gas outlet of gas-liquid separator 4 and enters condenser 5 for condensation. The liquid hydrogen fluoride produced by condensation enters liquid hydrogen fluoride recovery tank 7 for subsequent recycling. The remaining hydrogen chloride gas is discharged from the gas outlet of condenser 5 and subsequently absorbed by tail gas absorption tower to prepare hydrochloric acid.

[0075] This invention addresses the problems of high hazardous waste emissions, low product yields, and high raw material costs in existing synthesis processes. It provides a method for preparing fluoroethylene carbonate with low hazardous waste generation, high yield, and low raw material costs. Furthermore, when a microchannel reactor is used for the fluorination reaction, continuous and automated production can be achieved, significantly improving production efficiency.

[0076] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0077] Example 1

[0078] To a 2000 mL autoclave, 600 g of 95% ethylene chloride carbonate (MW122.5, 4.65 mol), 150 g of trifluorotoluene (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 added sequentially. Stirring was initiated, and 280 g of liquid hydrogen fluoride (MW20, 14 mol) was added. After the liquid hydrogen fluoride was completely added, the mixture was slowly heated to 60℃–70℃, and the reaction was maintained at 0.6–0.8 MPa for 5 hours. Hydrogen chloride gas was released during the reaction. Samples were taken for analysis, and the FEC purity was 90.2%, the CEC purity was 3.8%, and the conversion rate was 95.9%.

[0079] After the reaction was complete, the temperature was lowered to 15℃~25℃, and the atmosphere was vented to atmospheric pressure. 450g of trichlorotoluene (MW 195.47, 2.30mol) was added, and the pressure was controlled at 1.5~1.8MPa. The temperature was maintained at 50℃~60℃, and the reaction was kept at this temperature for 4 hours. Hydrogen chloride gas generated during the reaction was discharged. After the reaction was complete, a mixture of FEC and trifluorotoluene was discharged. Then, 470g of byproduct trifluorotoluene with a purity of 99.7% and a molar yield of 95.09% was obtained by distillation. The concentrate was then distilled at a reboiler temperature of 90℃, a top temperature of 60℃, and a pressure below 15mmHg. The product collected after distillation was cooled to 18℃ and crystallized for 10 hours. The uncrystallized material was then discharged, and the remaining crystalline material was heated to 35℃ to melt, yielding approximately 468g of purified fluoroethylene carbonate with a purity of 99.98% and a molar yield of 95.0%.

[0080] The HPLC spectrum of the fluoroethylene carbonate prepared in this embodiment is shown below. Figure 2 As shown, the spectral data are presented in Table 1:

[0081] Table 1. Spectral data of HPLC chromatograms

[0082] Retention time / min Peak width / min Peak area Peak Peak area % 5.856 0.4 37731.99 4911.38 99.98246 7.087 0.15 2.82 1.07 0.00747 7.531 0.14 3.8 1.36 0.01007 sum / 37738.61 / /

[0083] The 1H NMR spectrum of the fluoroethylene carbonate prepared in this embodiment is shown below. Figure 3 As shown, the NMR data are as follows: 1¹H NMR (400MHz, DMSO) δ 6.67–6.50 (d, 1H, CH), 4.79–4.59 (m, 2H, CH₂); The carbon NMR spectrum of the fluoroethylene carbonate prepared in this example is as follows. Figure 4 As shown.

[0084] Example 2

[0085] To a 2000 mL autoclave, 600 g of 90% ethylene chloride carbonate (MW122.5, 4.41 mol), 150 g of trifluorotoluene (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. Stirring was initiated, and 280 g of liquid hydrogen fluoride (MW20, 14 mol) was added. After the liquid hydrogen fluoride was completely added, the mixture was slowly heated to 60℃–70℃, and the pressure was maintained at 0.6–0.8 MPa for 5 hours. Hydrogen chloride gas was released during the reaction. Samples were taken and analyzed; the FEC purity was 91.2%, the CEC purity was 3.0%, and the conversion rate was 96.8%.

[0086] After the reaction was complete, the temperature was lowered to 15℃~25℃, and the atmosphere was vented to atmospheric pressure. 450g of trichlorotoluene (MW 195.47, 2.30mol) was added, and the pressure was controlled at 1.5~1.8MPa. The temperature was maintained at 50℃~60℃, and the reaction was kept at this temperature for 3 hours. The generated hydrogen chloride gas was discharged during the reaction. After the reaction was complete, a mixture of FEC and trifluorotoluene was obtained. This mixture was then distilled to remove solvent, yielding 475g of byproduct trifluorotoluene with a purity of 99.5% and a molar yield of 96.5%. The concentrated solution was further purified by distillation and melt crystallization (under the same conditions as in Example 1) to obtain approximately 445g of purified fluoroethylene carbonate with a purity of 99.97% and a molar yield of 95.1%.

[0087] Example 3

[0088] To a 2000 mL autoclave, 600 g of 95% chloroethylene carbonate (MW122.5, 4.65 mol), 180 g of p-chlorotrifluorotoluene (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 added sequentially. Stirring was initiated, and 280 g of liquid hydrogen fluoride (MW20, 14 mol) was added. After the liquid hydrogen fluoride was completely added, the mixture was slowly heated to 60℃–70℃, and the pressure was controlled at 0.6–0.8 MPa. The reaction was maintained at this temperature for 5 hours, with hydrogen chloride gas being released during the reaction. Samples were taken for analysis, and the FEC purity was 91.2%, the CEC purity was 3.5%, and the conversion rate was 96.3%.

[0089] After the reaction was complete, the temperature was lowered to 15℃~25℃, and the atmosphere was vented to atmospheric pressure. 530g of p-chlorotrichlorotoluene (MW 229.9, 2.31mol) was added, and the pressure was controlled at 1.5~1.8MPa. The temperature was maintained at 50℃~60℃, and the reaction was carried out for 3 hours. Hydrogen chloride gas generated during the reaction was discharged. After the reaction was complete, a mixture of FEC and p-chlorotrifluorotoluene was obtained. This mixture was then distilled to obtain 570g of byproduct p-chlorotrifluorotoluene with a purity of 99.5% and a molar yield of 95.6%. The concentrated solution was further purified by distillation and melt crystallization (under the same conditions as in Example 1) to obtain approximately 465g of purified fluoroethylene carbonate with a purity of 99.97% and a molar yield of 94.3%.

[0090] Example 4

[0091] Dissolve 6g of p-tert-butylcatechol (MW166.2, 0.03mol), 50g of titanium tetrachloride (MW189.6, 0.26mol), and 50g of tungsten hexachloride in 6000g of 95% chloroethylene carbonate (MW122.5, 46.5mol), and place the mixture in a mixing tank 2. The jacketed heating system of the microchannel reactor 3 is turned on, and the temperature is controlled at 60℃~70℃. At the same time, the mixed liquid feed pump 9 and the liquid hydrogen fluoride feed pump 8 are started, and the flow ratio of CEC and liquid hydrogen fluoride is controlled at 6:3.5. The material is slowly introduced into the microchannel to carry out the reaction. The pressure of the microchannel reactor 3 is controlled at 0.2~0.4MPa by controlling the opening of the outlet valve. The gas-liquid mixture obtained from the reaction is separated by the gas-liquid separator 4. The resulting mixed gas is condensed by the condenser 5. The excess hydrogen fluoride enters the liquid hydrogen fluoride recovery tank 7 for reuse. The hydrogen chloride is absorbed to prepare hydrochloric acid as a by-product. The reaction liquid obtained from the gas-liquid separation enters the reaction liquid receiving tank 6. After distillation and melt crystallization (the conditions for distillation and melt crystallization are the same as in Example 1), the high-quality fluoroethylene carbonate is obtained with a purity of 99.97% and a molar yield of 95.7%.

[0092] Example 5

[0093] To a 2000 mL autoclave, 600 g of 90% chloroethylene carbonate (MW122.5, 4.41 mol), 150 g of trifluorotoluene (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 added sequentially. Stirring was initiated, and then 280 g of liquid hydrogen fluoride (MW20, 14 mol) was added. After the liquid hydrogen fluoride was completely added, the mixture was slowly heated to 60℃–70℃, and the pressure was controlled at 0.6–0.8 MPa. The reaction was maintained at this temperature for 5 hours, with hydrogen chloride gas being released during the reaction. Samples were taken for analysis, and the FEC purity was 84.6%, the CEC purity was 8.9%, and the conversion rate was 90.4% (the conversion rate was relatively low).

[0094] After the reaction was complete, the temperature was lowered to 15℃~25℃, and the atmosphere was vented to atmospheric pressure. 450g of trichlorotoluene (MW 195.47, 2.30mol) was added, and the pressure was controlled at 1.5~1.8MPa. The temperature was controlled at 50℃~60℃, and the reaction was maintained at this temperature for 3~4 hours. Hydrogen chloride gas generated during the reaction was discharged. After the reaction was complete, a mixture of FEC and trifluorotoluene was obtained. This mixture was then distilled to remove solvent, yielding 473g of byproduct trifluorotoluene with a purity of 99.5% and a molar yield of 97.2%. The concentrate was then fractionally distilled and melt-crystallized (under the same conditions as in Example 1) to obtain approximately 408g of purified fluoroethylene carbonate with a purity of 99.95% and a molar yield of 87.3%.

[0095] Comparative Example 1 used diethyl carbonate as a solvent.

[0096] To a 2000 mL autoclave, add 600 g of 90% ethylene chloride 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). Start stirring, then add 280 g of liquid hydrogen fluoride (MW20, 14 mol). After the liquid hydrogen fluoride is added, slowly heat to 60℃–70℃, maintain the pressure at 0.6–0.8 MPa, and continue the reaction for 5 hours. While reacting, release hydrogen chloride gas. Samples were taken for analysis; the FEC purity was 80.1%, the CEC purity was 8.9%, and the conversion rate was 90% (low conversion rate).

[0097] After the reaction was complete, the temperature was lowered to 15℃~25℃, and the atmosphere was vented to atmospheric pressure. 450g of trichlorotoluene (MW 195.47, 2.32mol) was added, and the pressure was controlled at 1.5~1.8MPa. The temperature was controlled at 50℃~60℃, and the reaction was maintained for 3~4 hours. Hydrogen chloride gas generated during the reaction was discharged. After the reaction was complete, a mixture of FEC, trifluorotoluene, and diethyl carbonate was obtained. This mixture was then distilled to obtain 445g of a mixed solvent of byproduct trifluorotoluene and diethyl carbonate. The concentrated solution was then subjected to further distillation and melt crystallization (under the same conditions as in Example 1) to obtain approximately 402g of purified fluoroethylene carbonate with a purity of 99.4% (the purity is too low to reach electronic grade purity) and a molar yield of 85.9% (the yield is relatively low).

[0098] Comparative Example 2: Fluorination reaction temperature increased

[0099] To a 2000 mL autoclave, add 600 g of 90% ethylene chloride carbonate (MW122.5, 4.41 mol), 150 g of trifluorotoluene (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). Stir and add 280 g of liquid hydrogen fluoride (MW20, 14 mol). After the liquid hydrogen fluoride is added, slowly heat to 85℃–95℃, maintain the pressure at 0.6–0.8 MPa, and continue the reaction for 5 hours. While reacting, release hydrogen chloride gas. Samples were taken for testing; the FEC purity was 78.5%, the CEC purity was 1.8%, and the conversion rate was 98.1% (although the conversion rate was high, the product purity was low, and byproduct impurities increased).

[0100] After the reaction was complete, the temperature was lowered to 15℃~25℃, and the atmosphere was vented to atmospheric pressure. 450g of trichlorotoluene (MW 195.47, 2.30mol) was added, and the pressure was controlled at 1.5~1.8MPa. The temperature was maintained at 50℃~60℃, and the reaction was kept at this temperature for 4 hours. Hydrogen chloride gas generated during the reaction was discharged. After the reaction was complete, a mixture of FEC and trifluorotoluene was obtained. This mixture was then distilled to obtain 470g of byproduct trifluorotoluene with a purity of 99.5% and a molar yield of 96.6%. The concentrated solution was further purified by distillation and melt crystallization (under the same conditions as in Example 1) to obtain approximately 330g of refined fluoroethylene carbonate with a purity of 99.3% (low product purity) and a molar yield of 70.5% (due to the high reaction temperature, there was a high polymer residue in the distillation vessel, resulting in a lower product yield).

[0101] Comparative Example 3 (inhibitor omitted)

[0102] To a 2000 mL autoclave, 600 g of 90% ethylene chloride carbonate (MW122.5, 4.41 mol), 150 g of trifluorotoluene (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 added sequentially. Stirring was initiated, and then 280 g of liquid hydrogen fluoride (MW20, 14 mol) was added. After the liquid hydrogen fluoride was completely added, the mixture was slowly heated to 60℃–70℃, and the pressure was maintained at 0.6–0.8 MPa for 5 hours. Hydrogen chloride gas was released during the reaction. Samples were taken and analyzed; the FEC purity was 91.2%, the CEC purity was 3.0%, and the conversion rate was 96.8%.

[0103] After the reaction was complete, the temperature was lowered to 15℃~25℃, and the atmosphere was vented to atmospheric pressure. 450g of trichlorotoluene (MW 195.47, 2.30mol) was added, and the pressure was controlled at 1.5~1.8MPa. The temperature was maintained at 50℃~60℃, and the reaction was kept at this temperature for 3 hours. Hydrogen chloride gas generated during the reaction was discharged. After the reaction was complete, a mixture of FEC and trifluorotoluene was obtained. This mixture was then distilled to remove solvent, yielding 464g of byproduct trifluorotoluene with a purity of 99.5% and a molar yield of 95.4%. The concentrated solution was further purified by distillation and melt crystallization (under the same conditions as in Example 1) to obtain approximately 363g of purified fluoroethylene carbonate with a purity of 99.97% and a molar yield of 77.5%. (The low yield was due to partial polymerization caused by the absence of a polymerization inhibitor.)

[0104] Comparative Example 4 (catalyst omitted)

[0105] 600 g of 90% ethylene chloride carbonate (MW122.5, 4.41 mol), 150 g of trifluorotoluene (MW146.1, 1.03 mol), and 0.6 g of p-tert-butylcatechol (MW166.2, 0.003 mol) were added sequentially to a 2000 mL autoclave. Stirring was started, and 280 g of liquid hydrogen fluoride (MW20, 14 mol) was added. After the liquid hydrogen fluoride was completely added, the mixture was slowly heated to 60℃–70℃, and the reaction was maintained at 0.6–0.8 MPa for 5 hours. Hydrogen chloride gas was released during the reaction. Samples were taken and analyzed; the FEC purity was 56.6%, the CEC purity was 35.3%, and the conversion rate was 61.6%.

[0106] After the reaction was complete, the temperature was lowered to 15℃~25℃, and the atmosphere was vented to atmospheric pressure. 450g of trichlorotoluene (MW 195.47, 2.30mol) was added, and the pressure was controlled at 1.5~1.8MPa. The temperature was maintained at 50℃~60℃, and the reaction was kept at this temperature for 3 hours. Hydrogen chloride gas generated during the reaction was discharged. After the reaction was complete, a mixture of FEC and trifluorotoluene was obtained. This mixture was then distilled to remove solvent, yielding 473g of byproduct trifluorotoluene with a purity of 99.5% and a molar yield of 97.2%. The concentrated solution was further purified by distillation and melt crystallization (under the same conditions as in Example 1) to obtain approximately 235g of fluoroethylene carbonate product with a purity of 99.2% and a molar yield of 50.2%. (Due to the lack of a catalyst, the conversion rate was low, the raw material residue was large, and the product purity was substandard.)

[0107] In summary, the method for preparing fluoroethylene carbonate provided by this invention has a high conversion rate, high product yield and purity, low raw material cost, and low hazardous waste production. It is also easy to achieve continuous and automated production and has broad prospects.

[0108] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing fluoroethylene carbonate, characterized in that, Includes the following steps: Vinyl chlorinated carbonate, a polymerization inhibitor, a catalyst, and liquid hydrogen fluoride are mixed and subjected to a fluorination reaction to obtain fluorovinyl carbonate; the catalyst is titanium tetrachloride and tungsten hexachloride, and the molar ratio of titanium tetrachloride and tungsten hexachloride is (1~5):1; or the catalyst is tungsten hexachloride and tin tetrachloride, and the molar ratio of tungsten hexachloride and tin tetrachloride is 1:(1~5); the polymerization inhibitor is p-tert-butylcatechol; the molar ratio of vinyl chlorinated carbonate to catalyst is 1:(0.001~0.01), and the molar ratio of vinyl chlorinated carbonate to polymerization inhibitor is 1:(0.0001~0.001); A solvent, specifically a trifluorotoluene compound or p-chlorotrifluorotoluene, is added during the mixing process. After the fluorination reaction is completed, the resulting reaction solution is mixed with the trichlorotoluene compound, which then reacts with the remaining hydrogen fluoride in the reaction solution to obtain a mixed reaction solution of fluoroethylene carbonate and the trifluorotoluene compound. The mixed reaction solution is then distilled to remove solvent, yielding a concentrated solution and the trifluorotoluene compound. The trifluorotoluene compound is recycled. The molar ratio of the chloroethylene carbonate to the solvent is 1:(0.2~2); The trichlorotoluene compounds are trichlorotoluene or p-chlorotrichlorotoluene.

2. The preparation method according to claim 1, characterized in that, The fluorination reaction is carried out in an autoclave.

3. The preparation method according to claim 2, characterized in that, The fluorination reaction includes: adding chloroethylene carbonate, solvent, catalyst, polymerization inhibitor and liquid hydrogen fluoride into a high-pressure reactor, then heating, and carrying out the fluorination reaction under certain temperature and pressure conditions; During the fluorination reaction, hydrogen chloride gas generated is discharged while the reaction is underway. The discharged hydrogen chloride gas is absorbed by water to produce hydrochloric acid as a byproduct. The pressure of the fluorination reaction is controlled by controlling the amount of hydrogen chloride gas discharged. During the fluorination reaction, the gaseous hydrogen fluoride and gaseous solvent generated are condensed, collected, and returned to the autoclave.

4. The preparation method according to claim 3, characterized in that, The concentrate is subjected to distillation and melt crystallization in sequence to obtain fluoroethylene carbonate product.

5. The preparation method according to claim 4, characterized in that, The distillation vessel temperature is 90℃~110℃, the top temperature is 60℃~80℃, and the pressure is below 15mmHg; the melting crystallization includes: cooling the product collected after distillation to 18℃~20℃, crystallizing for 10~16 hours, then releasing the uncrystallized material, and heating the remaining crystalline material to 35℃~40℃ for melting to obtain high-quality fluoroethylene carbonate.

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

7. The preparation method according to claim 6, characterized in that, The fluorination reaction includes: Vinyl chloride carbonate, catalyst, polymerization inhibitor and solvent are mixed to obtain a mixture; The mixture and liquid hydrogen fluoride are introduced into a microchannel reactor to carry out the fluorination reaction.

8. The preparation method according to claim 7, characterized in that, The fluorination reaction further includes: gas-liquid separation of the generated gas-liquid mixture to obtain a reaction liquid and a mixed gas; the mixed gas includes hydrogen fluoride and hydrogen chloride; the mixed gas is condensed to recover hydrogen fluoride, and the remaining hydrogen chloride is absorbed with water to prepare hydrochloric acid.

9. The preparation method according to claim 6, characterized in that, The apparatus used for the fluorination reaction also 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 connected to 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 inlet of the liquid hydrogen fluoride recovery tank (7) is connected to the liquid outlet of the condenser (5).

10. The preparation method according to any one of claims 1-3 and 7-9, characterized in that, The fluorination reaction is carried out at a temperature of 30℃ to 80℃ and a pressure of 0.1 to 1.5 MPa.

11. The preparation method according to any one of claims 1-3 and 7-9, characterized in that, The molar ratio of the chloroethylene carbonate to the liquid hydrogen fluoride is 1:(1~5).

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