Method and production system for hexafluorobutadiene

Abstract

The present invention discloses a method and system for producing hexafluorobutadiene, which includes the following steps: In step (1), an organic solution of bromotrifluoroethylene and zinc powder are respectively introduced into a first reactor containing an initiator, zinc powder, and an organic solvent, followed by a second reactor, and reacted to obtain a trifluorovinylzinc bromide solution. The reaction solution is then introduced into a precipitator to separate excess zinc powder, resulting in a zinc-free trifluorovinylzinc bromide solution. The excess zinc powder is then filtered and reused. In step (2), the trifluorovinylzinc bromide solution obtained above and a pre-prepared composite catalyst solution are introduced into a third reactor and subjected to a coupling reaction to obtain crude hexafluorobutadiene. In step (3), the crude hexafluorobutadiene obtained above is purified to obtain a product with a purity of ≥ 99.9%.

Description

[Technical Field]

[0001] Cross-reference of related applications This application claims priority to the Chinese patent application filed with the China National Patent Office on December 12, 2023, application number 202311705885.0, and incorporates the entire contents of said application by reference.

[0002] The present invention relates to the production of fluorine-containing electron gas, and more particularly to a method and production system for hexafluorobutadiene. [Background technology]

[0003] Hexafluorobutadiene (C4F6) is a colorless, liquefiable fluorine-containing gas with a boiling point of 5.5°C at atmospheric pressure and a liquid density of 1.44 g / mL at 15°C. Currently, hexafluorobutadiene is mainly used as a dry etching gas for critical-dimensional precision etching (accuracy reaching 100 nm) for the production of low-K dielectric constant rectifier circuit boards containing Cu, and it has better selectivity and depth-to-width ratio than other etching gases. For example, the width-to-depth etching ratio with C4F6 reaches 10 compared to octafluorocyclobutane (c-C4F8), while that of c-C4F8 is only 3, making C4F6 suitable for extremely narrow linewidth processes. C4F6 only etches silicon oxide films and does not affect photoresist, silicon films, or nitride films, thus exhibiting excellent etching selectivity. Furthermore, hexafluorobutadiene possesses excellent environmental properties, with an ODP of 0, a GWP (100) of 290, and a short atmospheric existence time of only 1.9 days. Therefore, it has an extremely low greenhouse effect, making it a green and environmentally friendly etching gas. Consequently, as the integrated circuit industry develops and attention to greenhouse gases increases, hexafluorobutadiene, with its superior etching effect and environmental friendliness, is sure to become a mainstream product and be widely used in the laser etching agent market.

[0004] The manufacturing process for hexafluorobutadiene has been a hot spot in research in recent years, but few methods have been able to achieve truly industrial production. Reports on the production of hexafluorobutadiene using conventional technology mainly include the following:

[0005] (1) Oxidative coupling process The homocoupling pathway centers on the preparation of trifluorovinyl zinc halide (CF2=CFZnX), an important intermediate, and furthermore, Fe 3+ or Cu 2+ The method involves obtaining hexafluorobutadiene by homocoupling in the presence of ions. For example, WO2006 / 026400 describes preparing bromotrifluoroethylene (CF2=CFBr) using chlorotrifluoroethylene (CF2=CFCl) as a starting material by hydrogenation, dechlorination, bromination, and removal of hydrogen bromide, then reacting it with zinc powder to prepare trifluorovinyl zinc bromide (CF2=CFZnBr), and finally, Fe 3+ or Cu 2+ It has been disclosed that hexafluorobutadiene can be obtained by homocoupling in the presence of ions. Although this method uses inexpensive materials, it involves many dangerous production processes, has many steps, and carries the risk of autopolymerization of the intermediate product trifluoroethylene, making it unsuitable for large-scale industrial production.

[0006] CN104829415 discloses a process route for producing hexafluorobutadiene using tetrafluoroethane (HFC-134a) as a raw material. First, tetrafluoroethane and bromine are reacted at high temperature to obtain 1,1-dibromotetrafluoroethane, then zinc powder is reacted in a polar aprotic solvent to prepare trifluorovinyl zinc bromide, and finally Fe 3+To obtain hexafluorobutadiene by homocoupling in the presence of an oxidizing agent, and the total reaction yield is 47%. This reaction uses inexpensive refrigerant HFC-134a as a raw material and has a relatively short process route. However, 1,1-dibromotetrafluoroethane has low activity, and the yield is low when preparing zinc powder and trifluorovinylzinc bromide. Therefore, this process route has a high actual unit consumption, generates a large amount of waste liquid, waste gas, and solid waste, and has little prospect for actual industrialization.

[0007] Journal of Fluorine Chemistry 129(2008)443-446 reports the following. Using tetrafluoroethane (HFC-134a) as a raw material and lithium diisopropylamide (LDA) as a hydrogen abstraction reagent, zinc chloride / tetrahydrofuran system was used to prepare trifluorovinylzinc chloride, and then, Cu 2+ or Fe 3+ under the action of, hexafluorobutadiene was obtained, and the reaction yield was 69 - 70%. This process uses inexpensive and easily available raw material R134a, has simple synthesis steps, and can be synthesized in "one pot". However, the strong base lithium diisopropylamide (LDA) used in the first reaction is expensive and the production process is highly dangerous, so the possibility of industrialization is low.

[0008] JP2001114710 reports a process route for synthesizing hexafluorobutadiene using tetrafluoroethylene as a raw material. First, 1,2-dibromotetrafluoroethane was obtained by the addition reaction of tetrafluoroethylene and bromine. Then, 1,2-dibromotetrafluoroethane was rearranged in the presence of a Lewis acid catalyst to obtain 1,1-dibromotetrafluoroethane. Further, 1,1-dibromotetrafluoroethane was reacted with zinc powder to obtain a trifluorovinylzinc bromide reagent. Finally, Cu 2+ or Fe 3+In the presence of a catalyst, trifluorovinyl zinc bromide reagent is homocoupled to obtain the target product, hexafluorobutadiene. This process has relatively mild reaction conditions and relatively low raw material costs, but its overall yield is low (less than 50%), and since tetrafluoroethylene is used as a raw material, its industrialization is limited.

[0009] (2) Dehalogenation process The dehalogenation process involves obtaining the intermediate tetrahalohexafluorobutane (XCF2-CFX-CFX-CF2X) by telomerization or intermolecular dehalogenation, and then reacting it with zinc powder in an alcohol solvent to produce hexafluorobutadiene. US304630 discloses a method for producing perfluorobutadiene from chlorotrifluoroethylene as a raw material. First, chlorotrifluoroethylene is reacted with iodine chloride (ICl) in a closed system at 35-40°C to obtain 1,2-dichloro-1,2,2-trifluoroiodoethane. Next, it is coupled with an equivalent amount of mercury under UV light irradiation to obtain 1,2,3,4-tetrachloro-1,1,2,3,4,4-hexafluorobutane. Finally, 1,2,3,4-tetrachloro-1,1,2,3,4,4-hexafluorobutane is dechlorinated in an alcohol solvent under the action of zinc powder to obtain hexafluorobutadiene. This method requires the use of stoichiometric amounts of iodine chloride and mercury in the reaction, and one of the products is mercury iodide, which is highly toxic and uses expensive reagents.

[0010] CN106336342 improves upon this process by using a zinc powder / acetic anhydride system for intermolecular coupling, thus avoiding the use of highly toxic mercury as a raw material. Furthermore, the process conditions are milder, and the reaction yields for all three steps are high (90%). However, it still uses expensive iodine as a raw material, making it unsuitable for mass production.

[0011] US2894043 discloses a method in which 1,2-dichlorodifluoroethylene (CFCl=CFCl) dimerizes in the presence of fluorine gas to synthesize the intermediate product 1,2,3,4-tetrachlorohexafluorobutane, which is then dechlorinated with zinc powder to obtain the target product, perfluorobutadiene. This method requires low temperature conditions (-70°C) for the fluorination dimerization step and also uses the very dangerous gas F2. US2676193 improves upon this method, but the reaction still requires high temperature (300°C) and high pressure (12 MPa), and the reaction yield is somewhat too low at 30-40%, with many by-products and difficulty in separating the product.

[0012] RU0118462 reports a route for synthesizing hexafluorobutadiene from chlorotrifluoroethylene, and this patent avoids the use of highly toxic mercury and expensive iodine reagents. First, chlorotrifluoroethylene is dimerized at high temperature to obtain 34% 1,2-dichlorohexafluorocyclobutane and 27% 3,4-dichlorohexafluoro-1-butene. Next, these two products are separated in a high-efficiency distillation column. 3,4-dichlorohexafluoro-1-butene is directly dechlorinated with zinc powder to obtain the target product, hexafluorobutadiene. The advantage of this method is that C4F6 is obtained in only two reaction steps, resulting in fewer steps. However, the separation of the dimerized products requires a demanding fractional distillation process, which increases production costs to some extent, and although the yield of the target intermediate is improved, it is still less than 30%.

[0013] (3) Catalytic coupling process WO2018235883 discloses a method for obtaining hexafluorobutadiene by catalyzing a homocoupling reaction using chlorotrifluoroethylene as a starting material in the presence of a palladium catalyst, a phosphorus ligand, and zinc powder, with a maximum yield of 86.1%. CN116693365 discloses a method for obtaining hexafluorobutadiene by cross-coupling reaction using chlorotrifluoroethylene and trifluoroethylene as starting materials in the presence of an activated palladium catalyst and a basic compound, with a maximum reaction yield of 83%. Although these methods are simple processes, they are not advantageous in terms of raw material costs because they use expensive palladium as a catalyst.

[0014] (4) Fluorine gas process WO2007125972 discloses a process for producing hexafluorobutadiene from butadiene as a raw material, and the main steps are as follows: First, 1,3-butadiene is reacted with chlorine gas to produce 1,2,3,4-tetrachlorobutane. Next, without a catalyst, 1,2,3,4-tetrachlorobutane is reacted with fluorine gas in the gas phase using an inert gas as a carrier gas to produce 1,2,3,4-tetrachlorohexafluorobutane. Finally, 1,2,3,4-tetrachlorohexafluorobutane is reacted with zinc powder in a solvent to obtain hexafluorobutadiene.

[0015] In order to address the shortcomings of conventional technologies, there is a need to provide a method for producing hexafluorobutadiene and a production system that are low-cost, have high product purity, and enable safe, continuous, and stable production. [Overview of the Initiative] [Problems that the invention aims to solve]

[0016] The object of the present invention is to provide a method and production system for hexafluorobutadiene, thereby realizing safe, stable, and reliable production of hexafluorobutadiene.

[0017] The technical route of the present invention is as follows.

[0018]

Chemical formula

Means for Solving the Problems

[0019] According to the first aspect of the present invention for achieving the object of the present invention, the present invention adopts the following technical solutions.

[0020] A method for producing hexafluorobutadiene, the production method comprising the following steps.

[0021] Step (1): Put the organic solution of bromotrifluoroethylene and zinc powder into a first reactor containing an initiator, zinc powder and an organic solvent, react to obtain a solution of trifluorovinyl zinc bromide, and put the solution of trifluorovinyl zinc bromide and zinc powder into a second reactor containing zinc powder, an initiator and a first organic solvent to completely convert the unreacted bromotrifluoroethylene, put the reaction solution into a precipitation device to separate the excess zinc powder, and obtain a solution of trifluorovinyl zinc bromide from which the zinc powder has been removed. The first organic solvent is selected from polar aprotic organic solvents. Step (2): Put the solution of trifluorovinyl zinc bromide from which the zinc powder has been removed obtained in step (1) and a prepared composite catalyst organic solution into a third reactor for a coupling reaction to obtain a synthetic liquid containing a crude product of hexafluorobutadiene. The composite catalyst organic solution consists of an oxidizing agent, a co-catalyst and a second organic solvent. The co-catalyst is selected from monovalent copper salts and ferrous salts. The second organic solvent is selected from polar aprotic organic solvents. Step (3): Put the synthetic liquid obtained in step (2) into a purification system to obtain a purified hexafluorobutadiene product.

[0022] The preparation steps of the bromotrifluoroethylene solution are as follows.

[0023] Step A, in which the same type of solvent as in the first reactor (with water content ≤ 500 ppm) is precisely added to the bromotrifluoroethylene solution preparation vessel, Step B is then performed by pouring in a certain amount of bromotrifluoroethylene, limiting the temperature inside the vessel to -10 to 10°C, and ensuring the mass concentration of the solution is 5 to 30%. Preferably, the temperature inside the vessel is limited to 0 to 5°C, and the mass concentration of the solution is 15 to 20%.

[0024] The specific steps for preparing the aforementioned trifluorovinyl zinc bromide solution are as follows:

[0025] Step A is performed by first adding an organic solvent, an initiator, and zinc powder to the first reactor and raising the temperature to a constant level while stirring, simultaneously adding a solvent, an initiator, and zinc powder to the second reactor and raising the temperature to a constant level while stirring, opening the overflow valve of the first reactor so that the material in the first reactor can overflow into the second reactor, Step B involves continuously adding an organic solution of bromotrifluoroethylene and zinc powder to a first reactor, continuously adding zinc powder to a second reactor, opening the overflow valve of the second reactor, thereby allowing the material in the second reactor to overflow or be pumped into a sedimentation apparatus, and obtaining a trifluorovinyl zinc bromide solution from which the zinc powder has been removed. The sedimentation apparatus includes a plurality of sedimentation tanks, preferably two sedimentation tanks, and the trifluorovinyl zinc bromide solution prepared in step (1) is added to the first sedimentation tank by overflow or pumping, opening the overflow valve or pump of the first sedimentation tank, thereby allowing the material in the first sedimentation tank to overflow or be pumped into the second sedimentation tank, and obtaining a trifluorovinyl zinc bromide solution from which no zinc powder remains. A pressure filtration sedimentation tank may be used as the sedimentation tank, allowing excess zinc powder to settle on the baffle plate of the sedimentation tank to obtain a trifluorovinyl zinc bromide solution free of residual zinc powder. The zinc powder in the sedimentation tank can then be used directly in the preparation reaction of the trifluorovinyl zinc bromide solution after pressure filtration.

[0026] The initiator is one or more selected from bromomethane, 1,2-dibromoethane, elemental iodine, chlorotrimethylsilane, and trifluorovinyl zinc bromide solution, and the molar ratio of the supply rate of bromotrifluoroethylene (mol / h) to the amount of base initiator used (mol) is 1:(1~100).

[0027] Preferably, the initiator is one selected from 1,2-dibromoethane, elemental iodine, and trifluorovinyl zinc bromide reagent solution, and the molar ratio of the supply rate of bromotrifluoroethylene (mol / h) to the amount of base initiator used (mol) is 1:(1~50). More preferably, the initiator is trifluorovinyl zinc bromide reagent solution.

[0028] In the process of preparing the trifluorovinyl zinc bromide solution, the ratio of the supply rate of the bromotrifluoroethylene organic solution in kg / h to the mass of the base raw material in the first reactor in kg is 1:(10~100), and the ratio of the supply rate of the bromotrifluoroethylene organic solution in kg / h to the mass of the base raw material in the second reactor in kg is 1:(5~100).

[0029] Preferably, the ratio of the supply rate of the bromotrifluoroethylene organic solution in kg / h to the mass of the base raw material in the first reactor in kg is 1:(10~50), and the ratio of the supply rate of the bromotrifluoroethylene organic solution in kg / h to the mass of the base raw material in the second reactor in kg is 1:(10~50).

[0030] In the process of preparing the trifluorovinyl zinc bromide solution, the molar ratio of bromotrifluoroethylene to the supply rate of zinc powder in the first reactor is 1:(1.0~5.0), and the molar ratio of bromotrifluoroethylene to the supply rate of zinc powder in the second reactor is 1:(0.1~2.0).

[0031] Preferably, in the reaction process, the molar ratio of the supply rate of bromotrifluoroethylene to zinc powder in the first reactor is 1:(1.0~3.0), and the molar ratio of the supply rate of bromotrifluoroethylene to zinc powder in the second reactor is 1:(0.1~1.0).

[0032] In the process of preparing the trifluorovinyl zinc bromide solution in step (1), the mesh size of the zinc powder is 100 to 500 mesh.

[0033] Preferably, the mesh size of the zinc powder is 200 to 400 mesh.

[0034] In the process of preparing the trifluorovinyl zinc bromide solution in step (1), the organic solvent is selected from polar aprotic organic solvents, and the polar aprotic organic solvent is one, two or more selected from tetrahydrofuran, N,N-dimethylformamide, N,N-dimethylacetamide, hexamethylphosphate triamide, dimethyl sulfoxide, and N-methylpyrrolidone, and the water content of the polar aprotic organic solvent is ≤500 ppm.

[0035] Preferably, the polar aprotic organic solvent in step (1) is one, two, or a combination of three or more selected from N,N-dimethylformamide, N,N-dimethylacetamide, and dimethyl sulfoxide, and the water content of the polar aprotic organic solvent is ≤200 ppm.

[0036] In step (1), during the preparation of the trifluorovinyl zinc bromide solution, the temperature range of the first reactor is 60 to 120°C, and the temperature range of the second reactor is 60 to 90°C.

[0037] Preferably, the temperature range of the first reactor is 60 to 90°C, and the temperature range of the second reactor is 60 to 70°C.

[0038] In the process of preparing hexafluorobutadiene in step (2), the oxidizing agent is one or more selected from sodium peroxide, potassium peroxide, sodium perborate, sodium persulfate, potassium persulfate, ammonium persulfate, and di-tert-butyl peroxide; the co-catalyst is one or more selected from cuprous chloride, cuprous bromide, cuprous iodide, ferrous chloride, and ferrous bromide; and the polar aprotic organic solvent is one or more selected from tetrahydrofuran, N,N-dimethylformamide, N,N-dimethylacetamide, hexamethylphosphate triamide, dimethyl sulfoxide, and N-methylpyrrolidone.

[0039] Preferably, in the process of preparing hexafluorobutadiene in step (2), the oxidizing agent is selected from ammonium perborate, sodium persulfate, and potassium persulfate, and the auxiliary agent is one or more selected from cuprous iodide and ferrous chloride. The polar aprotic organic solvent is one or more selected from N,N-dimethylformamide, N,N-dimethylacetamide, and dimethyl sulfoxide.

[0040] In the process of preparing hexafluorobutadiene in step (2), the molar ratio of trifluorovinyl zinc bromide to oxidizing agent is 1:(1.0~3.0). In the trifluorovinyl zinc bromide solution, the molar ratio of trifluorovinyl zinc bromide to co-catalyst is 1:(0.01~0.2).

[0041] Preferably, the molar ratio of trifluorovinyl zinc bromide to oxidizing agent is 1:(1.0~1.5). In the trifluorovinyl zinc bromide solution, the molar ratio of trifluorovinyl zinc bromide to co-catalyst is 1:(0.01~0.05).

[0042] In the process of preparing hexafluorobutadiene in step (2), the coupling reaction temperature is -10 to 50°C, the reaction pressure is 0 to 0.5 MPa, and the residence time in the reactor is 10 to 600 seconds.

[0043] Preferably, the coupling reaction temperature is 0 to 10°C, the reaction pressure is 0 to 0.2 MPa, and the residence time in the reactor is 50 to 300 seconds.

[0044] In step (3), the purification system is preferably a combination of a distillation apparatus and a rectification apparatus. After the reaction is complete, the reaction mixture is placed in the distillation apparatus, the product is immediately distilled off, and further rectification is performed to obtain a high-purity hexafluorobutadiene product.

[0045] The bromotrifluoroethylene content in the crude hexafluorobutadiene obtained by distillation is ≤0.1%, and the heptafluorobutene content is ≤0.01%. After rectification, the purity of the product is ≥99.9%.

[0046] According to a second aspect of the present invention, the present invention employs the following technical solution.

[0047] A production system for the manufacture of hexafluorobutadiene, the production system used in the above manufacturing method, comprising a trifluorovinyl zinc bromide solution preparation unit, a hexafluorobutadiene preparation unit, a zinc powder filtration unit, a distillation unit, and a rectification unit. The trifluorovinyl zinc bromide solution preparation unit includes a bromotrifluoroethylene organic solution supply device, a zinc powder input device, a solvent and initiator input device, a first reactor, and a second reactor, wherein the bromotrifluoroethylene organic solution supply device, the zinc powder input device, and the solvent and initiator input device are connected to and supply the first reactor, the zinc powder input device, the solvent and initiator input device are connected to and supply the second reactor, the first reactor is connected to the second reactor and used to send the trifluorovinyl zinc bromide solution obtained by reaction in the first reactor to the second reactor, the upper parts of the first and second reactors are connected to a vacuum device and a high-purity nitrogen device, respectively, via condensers, and the outlet of the second reactor is connected to a zinc powder precipitation device. The hexafluorobutadiene preparation unit includes a trifluorovinyl zinc bromide solution supply device, a composite catalyst solution supply device, and a third reactor, the trifluorovinyl zinc bromide solution supply device and the composite catalyst solution supply device being connected to the inlet end of the third reactor. The distillation unit includes a hexafluorobutadiene synthesis solution supply device, a distillation apparatus, and a product collection device. The rectification unit includes a hexafluorobutadiene crude feeder, a rectification column, a pre-distillation storage tank, a product collection tank, and a rectification residue storage tank.

[0048] The material of each piece of equipment in the trifluorovinyl zinc bromide solution preparation unit is selected from enamel glass, carbon steel, 316L, and fluororesin-lined carbon steel; the material of the zinc powder filtration unit is selected from carbon steel, 304, and 316L; and the material of the distillation unit is selected from enamel glass, 304, and 316L.

[0049] Furthermore, stirring devices are provided in the first and second reactors, with the type of stirring blades selected from propeller-type stirring blades; and stirring devices are provided in the distillation apparatus, with the type of stirring blades selected from anchor-type stirring blades. [Effects of the Invention]

[0050] The beneficial effects of this invention are as follows:

[0051] (1) In the step of preparing trifluorovinyl zinc bromide, a two-stage series reactor is used, which not only achieves almost complete conversion of the raw material bromotrifluoroethylene and improves the utilization rate of the raw material, but also reduces the workload of subsequent product rectification and purification, thus helping to improve the purity of the product.

[0052] (2) In the step of preparing hexafluorobutadiene by oxidation coupling, an inexpensive peroxide is used as the oxidizing agent and a catalytic amount of copper or iron salt is used as an auxiliary agent. Compared to conventional processes that use an equivalent amount of copper or iron salt, this not only reduces raw material costs and the discharge of heavy metal solid waste, but also reduces the environmental burden. Furthermore, using an inorganic peroxide as the oxidizing agent reduces the generation of fluorine-containing olefins, which are impurities that are difficult to separate, compared to metal chloride oxidizing agents, and helps to improve the purity of the product. [Brief explanation of the drawing]

[0053] [Figure 1] Figure 1 is a schematic diagram of a trifluorovinyl zinc bromide solution preparation unit and a zinc powder filtration unit in an embodiment of the present invention. [Figure 2] Figure 2 is a schematic diagram of the hexafluorobutadiene preparation unit and distillation unit in an embodiment of the present invention. [Figure 3] Figure 3 is a chromatogram of the hexafluorobutadiene product produced in Example 15 of the present invention. [Explanation of symbols]

[0054] The following symbols are included in each of the above figures. 1. Bromotrifluoroethylene solution storage tank 2. Initiator or solvent storage tank 3. First reactor 4. Second reactor 5. First zinc powder storage tank 6. Second zinc powder storage tank 7. First condenser 8. Second condenser 9. First sedimentation tank 10. Second sedimentation tank 11. First Trifluorovinyl Zinc Bromide Solution Storage Tank 12. Second Trifluorovinyl Zinc Bromide Solution Storage Tank 13. Composite catalyst solution storage tank 14. Reactor No. 3 15. Hexafluorobutadiene synthesis solution buffer tank 16. First distillation apparatus 17. Second distillation apparatus 18. Third condenser 19. Fourth condenser 20. First hexafluorobutadiene buffer tank 21. First hexafluorobutadiene crude product tank 22. Fifth condenser 23. Sixth condenser 24. Second hexafluorobutadiene buffer tank 25. Second hexafluorobutadiene crude product tank 26. Storage tank for distillation residue [Modes for carrying out the invention]

[0055] The present invention will be further described below in conjunction with specific embodiments, however, the present invention is not limited to these specific embodiments. It should be understood by those skilled in the art that the present invention covers all candidate forms, improved forms and equivalent forms that may be included in the claims.

[0056] First, we will explain the production system for manufacturing hexafluorobutadiene according to the present invention, in conjunction with the drawings.

[0057] The production system for hexafluorobutadiene includes a trifluorovinyl zinc bromide solution preparation unit, a hexafluorobutadiene preparation unit, a zinc powder filtration unit, a distillation unit, and a rectification unit. The trifluorovinyl zinc bromide solution preparation unit includes a bromotrifluoroethylene organic solution supply device, a zinc powder input device, a solvent and initiator input device, a first reactor 3, and a second reactor 4.

[0058] The bromotrifluoroethylene organic solution supply device includes a bromotrifluoroethylene solution storage tank 1, and the solvent and initiator feeding device includes an initiator or solvent storage tank 2, each supplying material to the corresponding feeding section at the top of the first reactor 3 by pumping or gravity. The zinc powder feeding device includes a first zinc powder storage tank 5 that is fed by gravity. The first reactor 3 is connected to the second reactor 4 to send the trifluorovinyl zinc bromide solution obtained by reaction in the first reactor 3 to the second reactor 4. The second reactor 4 is further connected to a zinc powder feeding device, which may be a second zinc powder storage tank 6 that is fed by gravity. The upper parts of the first reactor 3 and the second reactor 4 are connected to a vacuum device via a first condenser 7 and a second condenser 8, respectively. The outlet of the second reactor 4 is connected to the zinc powder filtration unit, which may employ a two-stage sedimentation tank consisting of a first sedimentation tank 9 and a second sedimentation tank 10. The outlet of the second sedimentation tank 10 is connected to a first trifluorovinyl zinc bromide solution storage tank 11, which may also serve as a material buffer for production.

[0059] The hexafluorobutadiene preparation unit includes a trifluorovinyl zinc bromide solution supply device, a composite catalyst solution supply device, and a third reactor 14. The third reactor 14 is a tubular reactor, and the trifluorovinyl zinc bromide solution supply device and the composite catalyst solution supply device are connected to the inlet end of the third reactor. The trifluorovinyl zinc bromide solution supply device includes a second trifluorovinyl zinc bromide solution storage tank 12, and the second trifluorovinyl zinc bromide solution storage tank 12 and the first trifluorovinyl zinc bromide solution storage tank 11 may be the same. The trifluorovinyl zinc bromide solution supply device pumps to supply material to the third reactor 14. The composite catalyst solution supply device includes a composite catalyst solution storage tank 13 and pumps to supply material to the third reactor 14.

[0060] The distillation unit includes a hexafluorobutadiene synthesis solution supply device, a distillation apparatus, and a product collection device. A hexafluorobutadiene synthesis solution buffer tank 15 may be connected to the outlet end of the third reactor 14.

[0061] The distillation unit includes a hexafluorobutadiene synthesis solution supply device, a distillation apparatus, and a product collection device.

[0062] The hexafluorobutadiene synthesis solution supply device includes a hexafluorobutadiene synthesis solution buffer tank 15, which pumps to supply material to two parallel purification systems. The first purification system includes a first distillation apparatus 16, which is connected to a first hexafluorobutadiene buffer tank 20 via a third condenser 18, and the first hexafluorobutadiene buffer tank 20 is connected to a first hexafluorobutadiene crude tank 21 via a fourth condenser 19. The second purification system includes a second distillation apparatus 17, which is connected to a second hexafluorobutadiene buffer tank 24 via a fifth condenser 22, and the second hexafluorobutadiene buffer tank 24 is connected to a second hexafluorobutadiene crude tank 25 via a sixth condenser 23. The second hexafluorobutadiene crude tank 25 is further connected to a rectification apparatus. In the figure, reference numeral 26 denotes a distillation residue storage tank.

[0063] In the following embodiment, the above production system is used.

[0064] (Example 1) (1) In a 500L first reactor made of 316L material, 300 kg of N,N-dimethylformamide solution of trifluorovinyl zinc bromide with a mass fraction of 25% was added and stirring was started, then 65 kg of zinc powder was added and the reactor was heated to 80°C.

[0065] (2) In a 500L second reactor made of 316L material, 300 kg of N,N-dimethylformamide solution of trifluorovinyl zinc bromide with a mass fraction of 25% was added, stirring was started, 32.5 kg of zinc powder was added, and the reactor was heated to 60°C.

[0066] (3) A solution of bromotrifluoroethylene in N,N-dimethylformamide (20% by mass) was added to the first reactor, and the flow rate was limited to 15 kg / h. Simultaneously, zinc powder (325 mesh, 1.3 kg / h) was added to the first reactor using a solid supply system.

[0067] (4) The valve of the overflow port connected to the second reactor of the first reactor was opened, and the material in the first reactor entered the second reactor when the liquid level exceeded the height of the overflow port. At the same time, zinc powder (325 mesh, 0.35 kg / h) was added to the second reactor by the solid supply equipment.

[0068] (5) The valve of the overflow port of the second reactor to the first sedimentation tank was opened, and the material in the second reactor entered the first sedimentation tank when the liquid level exceeded the height of the overflow port, and the excess zinc powder from the reaction was precipitated on the baffle plate.

[0069] (6) The connecting valve of the first sedimentation tank to the second sedimentation tank was opened, and when the liquid level of the material in the first sedimentation tank exceeded the height of the valve outlet, the material transport pump was opened to transport the material to the second sedimentation tank and allow the remaining zinc powder to settle on the baffle plate.

[0070] (7) The valve connecting the second sedimentation tank to the trifluorovinyl zinc bromide solution storage tank was opened, and when the liquid level of the material in the second sedimentation tank exceeded the height of the valve outlet, the material transport pump was opened to transport the material to the storage tank. After 72 hours of operation, samples were taken from the trifluorovinyl zinc bromide solution storage tank and analyzed, yielding the following results: The normalized content of bromotrifluoroethylene by area percentage method was 0.005%, the mass fraction of trifluorovinyl zinc bromide was 25.1% (internal standard method by fluorine nuclear magnetic resonance), the theoretical mass fraction was 26%, and the average yield was 96.5%.

[0071] (Example 2) The procedure in this example was the same as in Example 1, with the only difference being the following: The flow rate of 15 kg / h for the N,N-dimethylformamide solution of bromotrifluoroethylene (20% mass fraction) was replaced with a flow rate of 20 kg / h for the N,N-dimethylformamide solution (20% mass fraction); the addition of zinc powder (325 mesh, 1.3 kg / h) to the first reactor was replaced with the addition of zinc powder (325 mesh, 1.8 kg / h); and the addition of zinc powder (325 mesh, 0.35 kg / h) to the second reactor was replaced with the addition of zinc powder (325 mesh, 0.48 kg / h). All other conditions remained unchanged. After 72 hours of operation, samples were taken from the trifluorovinyl zinc bromide solution storage tank and analyzed, yielding the following results. The area percentage content of bromotrifluoroethylene was 0.008%, the mass fraction of trifluorovinyl zinc bromide was 24.4% (internal standard method by fluorine nuclear magnetic resonance), the theoretical mass fraction was 26%, and the average yield was 93.8%.

[0072] (Example 3) The procedure in this embodiment was the same as in Embodiment 1, with the only difference being that the addition of zinc powder (325 mesh, 0.35 kg / h) to the second reactor was replaced with the addition of zinc powder (325 mesh, 0.20 kg / h) to the second reactor.

[0073] Other conditions were kept unchanged. After 72 hours of operation, samples were taken from the trifluorovinyl zinc bromide solution storage tank and analyzed, yielding the following results: The area percentage content of bromotrifluoroethylene was 0.006%, the mass fraction of trifluorovinyl zinc bromide was 24.7% (internal standard method by fluorine nuclear magnetic resonance), the theoretical mass fraction was 26%, and the average yield was 95.0%.

[0074] (Example 4) The procedure in this embodiment was the same as in Example 1, with the only difference being that the zinc powder mesh size was changed from 325 mesh to 500 mesh, while other conditions remained unchanged. After 72 hours of operation, samples were taken from the trifluorovinyl zinc bromide solution storage tank and analyzed, yielding the following results: The bromotrifluoroethylene content by area percentage was 0.01%, the mass fraction of trifluorovinyl zinc bromide was 22.2% (internal standard method by fluorine nuclear magnetic resonance), the theoretical mass fraction was 26%, and the average yield was 85.3%.

[0075] (Example 5) The procedure in this embodiment was the same as in Example 1, with the only difference being that the temperature of the first reactor was changed from 80°C to 60°C, while other conditions remained unchanged. After 72 hours of operation, samples were taken from the trifluorovinyl zinc bromide solution storage tank and analyzed, yielding the following results: The area percentage content of bromotrifluoroethylene was 0.012%, the mass fraction of trifluorovinyl zinc bromide was 21.7% (internal standard method by fluorine nuclear magnetic resonance), the theoretical mass fraction was 26%, and the average yield was 83.3%.

[0076] (Example 6) The procedure in this embodiment was the same as in Embodiment 1, with the only difference being that the temperature of the second reactor was changed from 60°C to 70°C, while other conditions remained unchanged. After 72 hours of operation, samples were taken from the trifluorovinyl zinc bromide solution storage tank and analyzed, yielding the following results: The area percentage content of bromotrifluoroethylene was 0.005%, the mass fraction of trifluorovinyl zinc bromide was 24.9% (internal standard method by fluorine nuclear magnetic resonance), the theoretical mass fraction was 26%, and the average yield was 95.8%.

[0077] (Example 7) The procedure in this example was the same as in Example 1, with the only difference being the following: Instead of adding a 25% mass fraction N,N-dimethylformamide solution of trifluorovinyl zinc bromide to the first and second reactors, the addition of a 25% mass fraction N,N-dimethylacetamide solution of trifluorovinyl zinc bromide to the first and second reactors was replaced. Instead of adding a 20% mass fraction N,N-dimethylformamide solution of bromotrifluoroethylene to the first reactor, the addition of a 20% mass fraction N,N-dimethylacetamide solution of bromotrifluoroethylene to the first reactor was replaced, with all other conditions remaining unchanged. After 72 hours of operation, samples were taken from the trifluorovinyl zinc bromide solution storage tank and analyzed, yielding the following results. The area percentage content of bromotrifluoroethylene was 0.007%, the mass fraction of trifluorovinyl zinc bromide was 23.9% (internal standard method by fluorine nuclear magnetic resonance), the theoretical mass fraction was 26%, and the average yield was 91.9%.

[0078] (Example 8) The procedure in this embodiment was the same as in Example 1, with the only difference being that zinc powder was replaced with zinc powder recovered from the first sedimentation tank, while other conditions remained unchanged. After 72 hours of operation, samples were taken from the trifluorovinyl zinc bromide solution storage tank and analyzed, yielding the following results: The area percentage content of bromotrifluoroethylene was 0.006%, the mass fraction of trifluorovinyl zinc bromide was 24.3% (internal standard method by fluorine nuclear magnetic resonance), the theoretical mass fraction was 26%, and the average yield was 93.5%.

[0079] (Comparative Example 1) A trifluorovinyl zinc bromide solution was prepared by reacting the materials in a single reactor, and the operating steps were as follows:

[0080] (1) In a 500L first reactor made of 316L material, 300 kg of N,N-dimethylformamide solution of trifluorovinyl zinc bromide with a mass fraction of 25% was added and stirring was started, then 65 kg of zinc powder was added and the reactor was heated to 80°C.

[0081] (2) A solution of bromotrifluoroethylene in N,N-dimethylformamide (20% by mass) was added to the first reactor, and the flow rate was limited to 15 kg / h. Simultaneously, zinc powder (325 mesh, 1.3 kg / h) was added to the first reactor using a solid supply system.

[0082] (3) The valve of the overflow port to the first sedimentation tank of the first reactor was opened, and the material in the second reactor entered the first sedimentation tank when the liquid level exceeded the height of the overflow port, and the excess zinc powder from the reaction was precipitated on the baffle plate.

[0083] (4) The connecting valve of the first sedimentation tank to the second sedimentation tank was opened, and when the liquid level of the material in the first sedimentation tank exceeded the height of the valve outlet, the material transport pump was opened to transport the material to the second sedimentation tank and allow the remaining zinc powder to settle on the baffle plate.

[0084] (5) The valve connecting the second sedimentation tank to the trifluorovinyl zinc bromide solution storage tank was opened, and when the liquid level of the material in the second sedimentation tank exceeded the height of the valve outlet, the material transport pump was opened to transport the material to the storage tank. After 72 hours of operation, samples were taken from the trifluorovinyl zinc bromide solution storage tank and analyzed, yielding the following results: The area percentage content of bromotrifluoroethylene was 1.56%, the mass fraction of trifluorovinyl zinc bromide was 20.2% (internal standard method by fluorine nuclear magnetic resonance), the theoretical mass fraction was 26%, and the average yield was 77.8%.

[0085] (Example 9) (1) Add 300 kg of N,N-dimethylformamide to a 500 L enamel glass reaction vessel, and while stirring, add ammonium persulfate (40 kg, 175 mol) and cuprous iodide (0.67 kg, 3.5 mol). Maintain the internal temperature at 0-5°C to complete the preparation of the oxidizing agent solution. The oxidizing agent concentration was 0.51 mol / kg, and the auxiliary agent concentration was 0.01 mol / kg.

[0086] (2) The oxidizing agent solution prepared above (flow rate of 40 kg / h, corresponding to a flow rate of 20.4 mol / h for ammonium persulfate and a flow rate of 0.4 mol / h for cuprous iodide) and the trifluorovinyl zinc bromide solution (mass fraction of 25%, flow rate of 16.8 kg / h, corresponding to a trifluorovinyl zinc bromide flow rate of 18.6 mol / h) were added to a spiral tube reactor (total length 10 m, inner diameter 8 mm) made of 316 L material. The internal temperature was limited to 0-5°C, and the pressure inside the reaction tube was 0.05 MPa.

[0087] (3) The synthesized solution was introduced into distillation apparatus A or B from the outlet of the reaction tube, the temperature inside the vessel was 60°C, the vacuum inside the vessel was 0.1 MPa, and condensation was performed after the vacuum pump to collect crude hexafluorobutadiene, with the temperature of the condenser being -15°C. The process was run for 72 hours, and the results were as follows: 107.6 kg of crude hexafluorobutadiene was collected from the crude product tank after the pump, and the content of the main component was 95.33% (the content of other impurities is shown in Table 1 below). Converted to a percentage by weight, this was 102.6 kg, the theoretical yield was 108.5 kg, and the average yield was 94.6%.

[0088] (Example 10) The procedure in this example was the same as in Example 9, with the only difference being the following: The oxidizing agent solution prepared above (flow rate of 60 kg / h, corresponding to a flow rate of ammonium persulfate of 30.6 mol / h and a flow rate of cuprous iodide of 0.6 mol / h) and the trifluorovinyl zinc bromide solution (mass fraction of 25%, flow rate of 25.2 kg / h, corresponding to a trifluorovinyl zinc bromide content of 27.9 mol / h) were added, with all other conditions unchanged. The system was run for 72 hours, and the results were as follows: 156.1 kg of hexafluorobutadiene crude was collected from the crude tank after pumping, and the content of the main component was 95.81% (the content of each other impurity was as shown in Table 1 below). Converted to weight percentage, this was 149.5 kg, the theoretical yield was 162.8 kg, and the average yield was 91.8%.

[0089] (Example 11) The procedure in this example was the same as in Example 9, with the only difference being that in step (1), ammonium persulfate (40 kg, 0.175 kmol) was replaced with potassium persulfate (40 kg, 0.148 kmol), resulting in an oxidizing agent concentration of 0.43 mol / kg and an auxiliary agent concentration of 0.01 mol / kg.

[0090] In step (2), the oxidizing agent solution (with a flow rate of 40 kg / h, corresponding to a flow rate of 20.4 mol / h for ammonium persulfate and 0.4 mol / h for cuprous iodide) was replaced with the oxidizing agent solution (with a flow rate of 47.4 kg / h, corresponding to a flow rate of 20.4 mol / h for potassium persulfate and 0.4 mol / h for cuprous iodide), while keeping other conditions unchanged. The system was run for 72 hours, and the results were as follows: 104.3 kg of hexafluorobutadiene crude was collected from the crude tank after pumping, and the content of the main component was 93.80% (the content of each other impurity is shown in Table 1 below). Converted to a weight percentage, this was 97.8 kg, the theoretical yield was 108.5 kg, and the average yield was 90.1%.

[0091] (Example 12) The procedure in this example was the same as in Example 9, with the only difference being that in step (1), cuprous iodide (0.67 kg, 3.5 mol) was replaced with ferrous chloride (0.70 kg, 3.5 mol). All other conditions remained unchanged. The process was run for 72 hours, and the results were as follows: 109.4 kg of hexafluorobutadiene crude was collected from the crude tank after pumping, with a main component content of 94.68% (the content of each other impurity was as shown in Table 1 below). Converted to a percentage by weight, this was 103.6 kg, the theoretical yield was 108.5 kg, and the average yield was 95.5%.

[0092] (Example 13) The procedure in this example was the same as in Example 9, with the only difference being: In step (1), cuprous iodide (0.67 kg, 3.5 mol) was replaced with cuprous iodide (1.33 kg, 7.0 mol) to complete the preparation of the oxidizing agent solution, and the additive concentration was changed from 0.01 mol / kg to 0.02 mol / kg. In step (2), the flow rate of cuprous iodide was changed from 0.4 mol / h to 0.8 mol / h. Other conditions were kept unchanged. The system was run for 72 hours, and the results were as follows: 107.4 kg of hexafluorobutadiene crude was collected from the crude tank after pumping, and the content of the main component was 95.02% (the content of each other impurity was as shown in Table 1 below). Converted to weight percent, this was 102.0 kg, the theoretical yield was 108.5 kg, and the average yield was 94.0%.

[0093] (Example 14) The procedure in this embodiment was the same as in Example 9, with the only difference being: maintaining the internal temperature at 0-5°C was replaced with maintaining the internal temperature at 5-10°C, and limiting the internal temperature to 0-5°C in step (2) was replaced with 5-10°C, while other conditions remained unchanged. The system was operated for 72 hours, and the results were as follows: 107.1 kg of hexafluorobutadiene crude was collected from the crude tank after pumping, and the content of the main component was 94.25% (the content of each other impurity was as shown in Table 1 below). Converted to a percentage by weight, this was 100.9 kg, the theoretical yield was 108.5 kg, and the average yield was 93.0%.

[0094] (Comparative Example 2) The procedure in this example was the same as in Example 9, with the only difference being that cuprous iodide was not added as an auxiliary agent during the preparation of the oxidizing agent solution in step (1), and all other conditions remained unchanged. The process was run for 72 hours, and the results were as follows: 10.7 kg of hexafluorobutadiene crude was collected from the crude tank after pumping, and the content of the main component was 66.51% (the content of each other impurity is shown in Table 1 below). Converted to a percentage by weight, this was 7.1 kg, the theoretical yield was 108.5 kg, and the average yield was 6.5%.

[0095] (Comparative Example 3) The procedure in this example was the same as in Example 9, with the only difference being the following: In step (3), the hexafluorobutadiene synthesis solution was distilled in an intermittent distillation vessel, and the synthesis solution after 72 hours of operation was placed in the distillation apparatus only once, without changing any other conditions. The results were as follows: 98.3 kg of hexafluorobutadiene crude was collected from the crude tank after pumping, and the content of the main component was 93.85% (the content of each other impurity was as shown in Table 1 below). Converted to a percentage by weight, it was 92.3 kg, the theoretical yield was 108.5 kg, and the average yield was 85.1%.

[0096] (Comparative Example 4) The procedure in this embodiment was the same as in Example 9, with the only difference being the following: In the process of preparing the oxidizing agent solution in step (1), the persulfate oxidizing agent was replaced with an equimolar amount of iron salt oxidizing agent, specifically as follows:

[0097] (1) 300 kg of N,N-dimethylformamide was added to a 500 L enamel glass reaction vessel, and ferric chloride (28.4 kg, 0.175 kmol) was added while stirring. The internal temperature was maintained at 0-5°C to complete the preparation of the oxidizing agent solution, and the oxidizing agent concentration was 0.53 mol / kg.

[0098] (2) In a spiral tube reactor (total length 10 m, inner diameter 8 mm) made of 316 L material, the oxidizing agent solution prepared above (flow rate 38.5 kg / h, corresponding to a flow rate of 20.4 mol / h for ferric chloride) and a trifluorovinyl zinc bromide solution (mass fraction 25%, flow rate 16.8 kg / h, corresponding to a trifluorovinyl zinc bromide flow rate of 18.6 mol / h) were added, the internal temperature was limited to 0-5°C, and the pressure inside the reaction tube was 0.05 MPa.

[0099] Step (3) was the same as in Example 9, and the process was run for 72 hours, with the following results: 102.7 kg of hexafluorobutadiene crude was collected from the crude tank after pumping, and the content of the main component was 88.52% (the content of each other impurity is shown in Table 1 below). Converted to a percentage by weight, this was 90.9 kg, the theoretical yield was 108.5 kg, and the average yield was 83.8%.

[0100] [Table 1]

[0101] (Example 15) Using the crude hexafluorobutadiene prepared in Example 9 as the raw material, a rectification experiment was conducted, and the rectification column parameters and rectification parameters were as shown in Tables 2 and 3 below.

[0102] [Table 2]

[0103] [Table 3] In the rectification process, 100 kg was supplied, yielding 22.6 kg of pre-distillate, resulting in a final product weight of 65.7 kg and a residue of 10.5 kg. The product purity was 99.9908%, the rectification yield per batch was 65.7%, and the material balance ratio was 98.8%. The chromatogram of the rectified product is shown in Figure 3. The results are as follows.

[0104] Table 4

Claims

1. The process involves (1) placing an organic solution of bromotrifluoroethylene and zinc powder into a first reactor containing an initiator, zinc powder, and an organic solvent, reacting them to obtain a trifluorovinyl zinc bromide solution, placing the trifluorovinyl zinc bromide solution and zinc powder into a second reactor containing zinc powder, an initiator, and a first organic solvent to completely convert the unreacted bromotrifluoroethylene, and placing the reaction solution into a precipitation apparatus to separate the excess zinc powder to obtain a trifluorovinyl zinc bromide solution from which the zinc powder has been removed, wherein the first organic solvent is selected from polar aprotic organic solvents. Step (2) is a step in which the trifluorovinyl zinc bromide solution from which the zinc powder obtained in step (1) has been removed and a pre-prepared composite catalyst organic solution are placed in a third reactor and subjected to a coupling reaction to obtain a synthetic solution containing crude hexafluorobutadiene, wherein the composite catalyst organic solution consists of an oxidizing agent, a co-catalyst, and a second organic solvent, the co-catalyst is selected from monovalent copper salts and ferrous salts, and the second organic solvent is selected from polar aprotic organic solvents. The step (3) includes placing the synthetic solution obtained in step (2) into a purification system and performing continuous distillation to obtain purified hexafluorobutadiene, A method for producing hexafluorobutadiene, characterized in that the initiator is one or more selected from bromomethane, 1,2-dibromoethane, elemental iodine, chlorotrimethylsilane, and trifluorovinyl zinc bromide reagent solution.

2. The method for producing hexafluorobutadiene according to Claim 1, characterized in that the molar ratio of the supply rate of bromotrifluoroethylene (mol / h) to the amount of base initiator used (mol) is 1:(1 to 50).

3. The method for producing hexafluorobutadiene according to claim 2, characterized in that the initiator is one or more selected from the 1,2-dibromoethane, the chlorotrimethylsilane, and the trifluorovinyl zinc bromide reagent solution, and the ratio of the supply rate of the bromotrifluoroethylene in mol / h to the number of moles of the base initiator used is 1:(1 to 100).

4. 1) The condition that the mass concentration of the organic solution of bromotrifluoroethylene is 5% to 30%, 2) In the reaction process, the ratio of the supply rate of bromotrifluoroethylene organic solution in kg / h to the mass of the base raw material in the first reactor in kg is 1:(10 to 100), 3) In the reaction process, the ratio of the supply rate of bromotrifluoroethylene organic solution in kg / h to the mass of the base raw material in the first reactor in kg is 1:(10-50), 4) The ratio of the supply rate of bromotrifluoroethylene organic solution in kg / h to the mass of the base raw material in the second reactor in kg is 1:(5-100), 5) The ratio of the supply rate of bromotrifluoroethylene organic solution in kg / h to the mass of the base raw material in the second reactor in kg is 1:(10-50), 6) The molar ratio of the supply rate of bromotrifluoroethylene to zinc powder in the first reactor is 1:(1.0 to 5.0), 7) The molar ratio of the supply rate of bromotrifluoroethylene to zinc powder in the first reactor is 1:(1.0 to 3.0), 8) The molar ratio of the supply rate of bromotrifluoroethylene to zinc powder in the second reactor is 1:(0.1 to 2.0), 9) The method for producing hexafluorobutadiene according to any one of claims 1 to 3, characterized in that at least one of the following conditions is met: the molar ratio of the supply rate of bromotrifluoroethylene to the supply rate of zinc powder in the second reactor is 1:(0.1 to 1.0).

5. 1) The condition that the mesh size of the zinc powder is 100 mesh to 500 mesh, 2) The condition is that the mesh size of the zinc powder is 200 mesh to 400 mesh, 3) The polar aprotic organic solvent in step (1) is one or more selected from tetrahydrofuran, N,N-dimethylformamide, N,N-dimethylacetamide, hexamethylphosphate triamide, dimethyl sulfoxide, and N-methylpyrrolidone, and the water content of the polar aprotic organic solvent is ≤500 ppm. 4) The method for producing hexafluorobutadiene according to any one of claims 1 to 3, characterized in that at least one of the following conditions is met: the water content of the polar aprotic organic solvent in step (1) is ≤ 200 ppm.

6. 1) The temperature range of the first reactor is 60°C to 120°C, 2) The temperature range of the first reactor is set to 60°C to 90°C, 3) The temperature range of the second reactor is 60°C to 90°C, 4) The method for producing hexafluorobutadiene according to any one of claims 1 to 3, characterized in that the temperature range of the second reactor is 60°C to 70°C, and at least one of the above conditions is met.

7. The method for producing hexafluorobutadiene according to any one of claims 1 to 3, characterized in that the sedimentation apparatus includes a plurality of sedimentation tanks.

8. The method for producing hexafluorobutadiene according to any one of claims 1 to 3, characterized in that the sedimentation apparatus includes two stages, a first sedimentation tank and a second sedimentation tank, and the trifluorovinyl zinc bromide solution prepared in step (1) is added to the first sedimentation tank and the second sedimentation tank in that order by overflow or pumping, thereby precipitating excess zinc powder and obtaining a trifluorovinyl zinc bromide solution free of residual zinc powder.

9. The method for producing hexafluorobutadiene according to claim 7, characterized in that the zinc powder in the sedimentation tank in step (1) can be used directly in the preparation reaction of the trifluorovinyl zinc bromide solution after being subjected to pressure filtration.

10. A method for producing hexafluorobutadiene according to any one of claims 1 to 3, characterized in that, in step (2), the oxidizing agent in the composite catalyst organic solution is one or more selected from sodium peroxide, potassium peroxide, sodium perborate, sodium persulfate, potassium persulfate, ammonium persulfate, and di-tert-butyl peroxide; the co-catalyst is one or more selected from cuprous chloride, cuprous bromide, cuprous iodide, ferrous chloride, and ferrous bromide; and the polar aprotic organic solvent in step (2) is one or more selected from tetrahydrofuran, N,N-dimethylformamide, N,N-dimethylacetamide, hexamethylphosphate triamide, dimethyl sulfoxide, and N-methylpyrrolidone.

11. 1) In step (2), the molar ratio of trifluorovinyl zinc bromide to oxidizing agent is 1:(1.0 to 3.0), 2) In step (2) above, the molar ratio of trifluorovinyl zinc bromide to oxidizing agent is 1:(1.0 to 1.5), 3) The condition in the trifluorovinyl zinc bromide solution is that the molar ratio of trifluorovinyl zinc bromide to co-catalyst is 1:(0.01 to 0.2), 4) The method for producing hexafluorobutadiene according to any one of claims 1 to 3, characterized in that at least one of the following conditions is met: the molar ratio of trifluorovinyl zinc bromide to co-catalyst in the trifluorovinyl zinc bromide solution is 1:(0.01 to 0.05).

12. 1) In step (2), the temperature of the coupling reaction is -10°C to 50°C, the reaction pressure is 0 MPa to 0.5 MPa, and the residence time in the reactor is 10 seconds to 600 seconds, 2) A method for producing hexafluorobutadiene according to any one of claims 1 to 3, characterized in that at least one of the following conditions is met: in step (2), the temperature of the coupling reaction is 0°C to 10°C, the reaction pressure is 0 MPa to 0.2 MPa, and the residence time in the reactor is 50 seconds to 300 seconds.

13. A method for producing hexafluorobutadiene according to any one of claims 1 to 3, characterized in that in step (3), the synthetic solution obtained in step (2) is distilled to obtain crude hexafluorobutadiene, and further rectified to obtain pure hexafluorobutadiene.

14. The method for producing hexafluorobutadiene according to claim 13, characterized in that the bromotrifluoroethylene content in the crude hexafluorobutadiene obtained by distillation is ≤0.1%, the heptafluorobutene content is ≤0.01%, and the purity of the product after rectification is ≥99.9%.

15. A production system for the manufacture of hexafluorobutadiene, used in the manufacturing method described in any one of claims 1 to 3, comprising a trifluorovinyl zinc bromide solution preparation unit, a hexafluorobutadiene preparation unit, a zinc powder filtration unit, a distillation unit, and a rectification unit, The trifluorovinyl zinc bromide solution preparation unit includes a bromotrifluoroethylene organic solution supply device, a zinc powder feeder, a solvent and initiator feeder, a first reactor, and a second reactor, wherein the bromotrifluoroethylene organic solution supply device, the zinc powder feeder, and the solvent and initiator feeder are connected to the first reactor and supply materials to it, the zinc powder feeder and the solvent and initiator feeder are connected to the second reactor and supply materials to it, the first reactor is connected to the second reactor and used to send the trifluorovinyl zinc bromide solution obtained by reaction in the first reactor to the second reactor, the upper parts of the first and second reactors are connected to a vacuum and high-purity nitrogen device via a condenser, and the outlet of the second reactor is connected to a zinc powder precipitation device. The hexafluorobutadiene preparation unit includes a trifluorovinyl zinc bromide solution supply device, a composite catalyst solution supply device, and a third reactor, the trifluorovinyl zinc bromide solution supply device and the composite catalyst solution supply device being connected to the inlet end of the third reactor. The distillation unit includes a hexafluorobutadiene synthesis solution supply device, a distillation apparatus, and a product collection device. The production system for hexafluorobutadiene is characterized in that the rectification unit includes a hexafluorobutadiene crude feeder, a rectification column, a pre-distillation storage tank, a product collection tank, and a rectification residue storage tank.

16. The production system for hexafluorobutadiene according to claim 15, characterized in that the material of each piece of equipment in the trifluorovinyl zinc bromide solution preparation unit and the hexafluorobutadiene preparation unit is selected from enamel glass, carbon steel, 316L, and fluororesin-lined carbon steel, the material of the equipment in the zinc powder filtration unit is selected from carbon steel, 304, and 316L, and the material of the equipment in the distillation unit is selected from enamel glass, 304, and 316L.

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