A method for electrolytic preparation of octafluorocyclobutane from dichlorohexafluorocyclobutane

Abstract

The application belongs to the field of electronic special gas, and particularly relates to a method for electrolytically preparing octafluorocyclobutane from dichlorohexafluorocyclobutane. The method comprises the following steps: S1. electrolyte preparation: uniformly mixing potassium fluoride and anhydrous hydrogen fluoride according to a molar ratio of 1:1-1:15, and dehydrating to obtain a mixed solution, and adding the mixed solution into an electrolytic cell; S2. electrolytically preparing octafluorocyclobutane: adding dehydrated dichlorohexafluorocyclobutane into the mixed solution, uniformly mixing, heating, and electrifying to obtain crude octafluorocyclobutane, wherein the addition amount of the dichlorohexafluorocyclobutane is 5-15% of the mass of the mixed solution, the heating temperature is 5-25 DEG C, the voltage of electrification is 4-20 V, and the current is 12-45 A. The application uses dichlorohexafluorocyclobutane as an electrolytic raw material to electrolytically prepare octafluorocyclobutane, improves the conversion rate of the raw material, reduces the waste of unreacted raw material, and thus reduces the production cost.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of electronic special gases, and particularly relates to a method for electrolytically preparing octafluorocyclobutane from dichlorohexafluorocyclobutane. BACKGROUND

[0002] Dichlorohexafluorocyclobutane can be used for medical anesthesia and anesthesia-related research, and can also be used as an organic synthesis intermediate. However, dichlorohexafluorocyclobutane, which is a main by-product in the thermal cracking process of trifluorochloroethylene, has low utilization value and large output, thereby restricting the economy of the process. Octafluorocyclobutane (C4F8) RC-318, CAS 115-25-3, is a perfluoro derivative of cyclobutane with a boiling point of -6.04℃. The relative vapor density (g / ml, air = 1) is 7.0. At room temperature and atmospheric pressure, octafluorocyclobutane exists as a colorless and odorless gas at room temperature and atmospheric pressure, and is a non-flammable gas.

[0003] With the development of the semiconductor and microelectronic industries and the increasing environmental protection requirements, the demand for electronic special gases is also increasing. Many electronic gases with greenhouse effect and serious ozone destruction have gradually withdrawn from the market. As a green and environmentally friendly gas, octafluorocyclobutane has a low global warming potential (GWP) and zero ozone depletion potential (ODP). It can be used as a refrigeration machine, insulation gas, solvent, blowing agent, etchant, cleaning agent, etc., and is applied in the refrigeration, power, chemical, semiconductor and other industries. High-purity octafluorocyclobutane is an electronic gas that can be used in large-scale integrated circuit etching and cleaning in the semiconductor industry. With the continuous expansion of China's electronic information industry, the demand continues to grow, and the octafluorocyclobutane industry has broad development prospects.

[0004] There are currently several methods for preparing octafluorocyclobutane from dichlorohexafluorocyclobutane:

[0005] A method for catalytically synthesizing octafluorocyclobutane is disclosed in Chinese Patent No. CN118530087A. A self-made catalyst is used, the foam metal is immersed in the immersion liquid to obtain a solid mixture; the solid mixture is calcined to obtain a crude catalyst; however, the catalyst in this method is easy to follow the product into the channel as the reaction proceeds, not only causing waste of the catalyst, but also possibly causing the catalyst to block the pipeline of the preparation device, making subsequent cleaning difficult.

[0006] A method for synthesizing octafluorocyclobutane by fluorine-chlorine exchange reaction is disclosed in Chinese Patent No. CN114956950B. Hydrogen fluoride gas and 1,1,2,2,3,4-hexafluoro-3,4-dichlorocyclobutane gas are introduced into a reactor containing Cr2O3-NiO catalyst supported by activated carbon to react and obtain octafluorocyclobutane. However, the preparation process of the catalyst is complicated.

[0007] Chinese patent publication number CN107721810B discloses a method for synthesizing octafluorocyclobutane by reacting 1,2-dichloro-3,3,4,4-tetrafluorocyclobutene with chlorine and hydrogen fluoride through addition and substitution reactions. This method uses relatively cheap raw materials and relatively mild reaction conditions. However, chlorine is highly corrosive to metals, easily causing equipment corrosion and leakage. It is also highly toxic and poses serious environmental hazards, limiting its industrial application. Summary of the Invention

[0008] In response to the problems of low yield, unsatisfactory catalytic effect, and complex reaction in the existing technology, the present application provides a method for preparing octafluorocyclobutane by electrolysis of dichlorohexafluorocyclobutane. This method is simple to operate, safe, environmentally friendly, and can run smoothly. It avoids the need to select a catalyst, ensures that the reaction maintains a high yield, and avoids the waste of raw materials while increasing the yield.

[0009] The technical solution of this application is as follows:

[0010] A method for preparing octafluorocyclobutane by electrolysis of dichlorohexafluorocyclobutane comprises the following steps:

[0011] Step S1. Electrolyte preparation

[0012] Mix potassium fluoride and anhydrous hydrogen fluoride in a molar ratio of 1:1 to 1:15, dehydrate the mixture to obtain a mixed solution, and add the mixed solution to the electrolytic cell;

[0013] Step S2. Preparation of octafluorocyclobutane by electrolysis

[0014] First, dichlorohexafluorocyclobutane is removed from water and then added to the mixed solution, mixed evenly, heated and energized to obtain crude octafluorocyclobutane, wherein the amount of dichlorohexafluorocyclobutane added is 5-15% of the mass of the mixed solution, the heating temperature is 5-25°C, the energizing voltage is 4-20V, and the current is 12-45A;

[0015] In which, the electrolytic cell in step S1 is provided with a plurality of alternating cathode electrode plates and anode electrode plates along a linear array, and the electrode plates are all arranged vertically; insulating material is padded between adjacent cathode electrode plates and anode electrode plates; circular holes for electrolyte circulation are evenly opened on the cathode electrode plates and anode electrode plates, and the diameter of the circular holes is 1 to 10 mm; the spacing between two adjacent circular holes on the same electrode plate is 5 to 20 mm; the spacing between adjacent cathode plates and anode plates is 1 to 8 mm.

[0016] Preferably, the diameter of the circular holes is 3-5 mm; the distance between two adjacent circular holes on the same electrode plate is 5-10 mm; and the distance between adjacent cathode plates and anode plates is 2-3 mm.

[0017] Preferably, the insulating material includes a plurality of polytetrafluoroethylene gaskets, which are evenly distributed on the side wall of the cathode electrode plate or the anode electrode plate to separate the cathode electrode plate and the anode electrode plate, and the distance between two adjacent polytetrafluoroethylene gaskets is 2 to 3 mm.

[0018] Preferably, the molar ratio of potassium fluoride to anhydrous hydrogen fluoride is 1:1 to 1:8.

[0019] Preferably, the dehydration treatment has a power-on voltage of 5 V, a power-on current of 3 to 5 A, and a power-on time of 0.5 to 2 h.

[0020] Preferably, the dichlorohexafluorocyclobutane dehydration process is: dichlorohexafluorocyclobutane is adsorbed and dehydrated by an adsorption material until the moisture content is reduced to below 10 ppm, and the adsorption material is any one of 3A molecular sieve, 4A molecular sieve or 5A molecular sieve.

[0021] Preferably, the amount of dichlorohexafluorocyclobutane added is 5-8% of the mass of the mixed solution, the heating temperature is 10-20° C., the voltage is 4-7V, and the current is 25-37A.

[0022] Preferably, the steps further include:

[0023] Step S3: condensing the crude octafluorocyclobutane at 0-5° C. and then passing it into a hydrogen fluoride removal tower to absorb hydrogen fluoride to obtain the product octafluorocyclobutane.

[0024] The beneficial effects of this application are as follows:

[0025] (1) This application uses dichlorohexafluorocyclobutane as the electrolysis raw material to prepare octafluorocyclobutane by electrolysis. Compared with traditional methods, this method improves the conversion rate of the raw material and reduces the waste of unreacted raw materials, thereby reducing production costs. At the same time, the electrolysis process directly promotes the breaking and recombination of chemical bonds without the need for additional catalysts, further simplifying the production process and reducing cost investment.

[0026] (2) The electrolysis method of this application significantly reduces waste emissions during the production process, particularly the generation of hazardous gases. By precisely controlling the electrolysis conditions and subsequent processing steps, such as condensation cooling and removal of hydrogen fluoride, a clean and safe production environment is ensured, in line with the development concept of modern green chemistry.

[0027] (3) The present application rationally designs the electrolytic plates (anode electrode plates and cathode electrode plates), including the diameter and spacing of the circular holes, as well as the spacing between the cathode plate and the anode plate, which not only improves the electrolysis efficiency, but also enhances the fluidity and mixing effect of the electrolyte, which is conducive to the uniform progress of the reaction, thereby improving the product yield.

[0028] In summary, the present invention avoids the use of complex reaction conditions and catalysts, making the operation process simpler and safer, achieving high-yield preparation of octafluorocyclobutane, while avoiding the waste of raw materials and improving the utilization rate of raw materials. DETAILED DESCRIPTION

[0029] In order to further explain the technical means and effects adopted by the present application to achieve the predetermined purpose of the invention, the specific implementation methods, structures, features and effects of the present application are described in detail below in combination with the preferred embodiments. It should be noted that the applicant has found through a large number of experiments in the early stage that the aperture of the circular holes on the cathode electrode plate and the anode electrode plate, the distance between two adjacent circular holes of the cathode electrode plate or the anode electrode plate, and the adjacent anode electrode plates and cathode electrode plates have good electrolysis effects within the parameter range set in the present application.

[0030] Example 1

[0031] Electrolytic plate preparation:

[0032] Material preparation: Select nickel metal plates as cathode electrode plates and anode electrode plates, clean and dry the metal plates to ensure that the surface of the electrode plates is flat, free of rust and pollution.

[0033] Punching: Use a punching tool to evenly punch circular holes on the cathode electrode plate and the anode electrode plate. The diameter of the circular holes is 4 mm, and the spacing between the circular holes is kept at 5 to 7 mm to ensure uniform distribution of the electrolyte and uniform transmission of the current.

[0034] Cross arrangement: The cathode electrode plates and anode electrode plates with holes are arranged crosswise, and the spacing between the crosswise arranged cathode electrode plates and anode electrode plates is controlled at 2 to 3 mm to ensure a good spacing between the cathode and anode to facilitate the flow and reaction of the electrolyte.

[0035] Insulation treatment: Insert a PTFE gasket made of insulating material between the cathode electrode plate and the anode electrode plate with a spacing of 2 to 3 mm to prevent short circuit during the electrolysis process.

[0036] Electrolyte preparation:

[0037] Mixed solution: Accurately weigh potassium fluoride and anhydrous hydrogen fluoride according to the molar ratio of potassium fluoride to anhydrous hydrogen fluoride of 1:1, pour into the electrolytic cell, and stir for 20 minutes.

[0038] Dehydration treatment: Place the mixed solution in an electrolytic cell, connect the power supply, adjust the voltage to 5V and the current to 3A, and continue to power on for 1 hour to ensure that the water in the mixed solution is removed.

[0039] Preparation of octafluorocyclobutane by electrolysis:

[0040] Dehydration of dichlorohexafluorocyclobutane: Pour dichlorohexafluorocyclobutane into a molecular sieve dehydration device and use 3A, 4A or 5A molecular sieve for adsorption dehydration treatment. Use a detection instrument to detect the water content of dichlorohexafluorocyclobutane to be 5.8ppm, and proceed to the next step.

[0041] Adding dichlorohexafluorocyclobutane: add the dehydrated dichlorohexafluorocyclobutane to the dehydrated electrolyte at a ratio of 8% by mass of the mixed solution, and stir thoroughly for 20 minutes.

[0042] Electrolysis condition setting: The reaction temperature is controlled at 10°C by adjusting the refrigerant circulation volume of the electrolytic cell jacket. At the same time, the voltage of the electrolytic cell is adjusted to the range of 4 to 5V, and the current is controlled between 25A and 27A to ensure that the electrolysis reaction is carried out under stable conditions.

[0043] Electrolysis reaction: Turn on the power and start the electrolysis reaction. During the electrolysis process, the changes in reaction temperature and current are monitored in real time to ensure that the reaction proceeds smoothly under the set conditions.

[0044] Collect crude product: After the electrolysis reaction is completed, collect the gas produced by the reaction, which is the crude octafluorocyclobutane.

[0045] Post-processing:

[0046] Condensation and cooling: The collected crude octafluorocyclobutane gas is passed through a condenser at 0-5°C for condensation and cooling.

[0047] Removal of hydrogen fluoride: The condensed gas is further processed through a hydrogen fluoride removal tower filled with sodium fluoride particles to remove hydrogen fluoride and other components.

[0048] Collect the product: collect the gas after removing hydrogen fluoride into a cold trap to obtain the product octafluorocyclobutane.

[0049] Example 2

[0050] Electrolytic plate preparation:

[0051] Material preparation: Select nickel metal plates as cathode electrode plates and anode electrode plates, clean and dry the metal plates to ensure that the surface of the electrode plates is flat, free of rust and pollution.

[0052] Punching: Use a punching tool to evenly punch circular holes on the cathode electrode plate and the anode electrode plate. The diameter of the circular holes is 3 mm, and the spacing between the circular holes is maintained at 9 to 10 mm to ensure uniform distribution of the electrolyte and uniform transmission of the current.

[0053] Cross arrangement: The cathode electrode plates and anode electrode plates with holes are arranged crosswise, and the spacing between the crosswise arranged cathode electrode plates and anode electrode plates is controlled at 1 to 3 mm to ensure a good spacing between the cathode and anode to facilitate the flow and reaction of the electrolyte.

[0054] Insulation treatment: Insert a PTFE gasket made of insulating material between the cathode electrode plate and the anode electrode plate with a spacing of 2 to 3 mm to prevent short circuit during the electrolysis process.

[0055] Electrolyte preparation:

[0056] Mixed solution: Accurately weigh potassium fluoride and anhydrous hydrogen fluoride according to the molar ratio of potassium fluoride to anhydrous hydrogen fluoride of 1:3, pour them into the electrolytic cell, and stir for 20 minutes.

[0057] Dehydration treatment: Place the mixed solution in an electrolytic cell, connect the power supply, adjust the voltage to 5V and the current to 3A, and continue to power on for 2 hours to ensure that the water in the mixed solution is removed.

[0058] Preparation of octafluorocyclobutane by electrolysis:

[0059] Dehydration of dichlorohexafluorocyclobutane: Pour dichlorohexafluorocyclobutane into a molecular sieve dehydration device and use 3A, 4A or 5A molecular sieve for adsorption dehydration treatment. Use a detection instrument to detect that the moisture content of dichlorohexafluorocyclobutane is 10ppm, and then proceed to the next operation.

[0060] Adding dichlorohexafluorocyclobutane: add the dehydrated dichlorohexafluorocyclobutane to the dehydrated electrolyte at a ratio of 5% by mass of the mixed solution, and stir thoroughly for 20 minutes.

[0061] Electrolysis condition setting: The reaction temperature is controlled at 10°C by adjusting the refrigerant circulation volume of the electrolytic cell jacket. At the same time, the voltage of the electrolytic cell is adjusted to the range of 5 to 7V, and the current is controlled between 27A and 35A to ensure that the electrolysis reaction is carried out under stable conditions.

[0062] Electrolysis reaction: Turn on the power and start the electrolysis reaction. During the electrolysis process, the changes in reaction temperature and current are monitored in real time to ensure that the reaction proceeds smoothly under the set conditions.

[0063] Collect crude product: After the electrolysis reaction is completed, collect the gas produced by the reaction, which is the crude octafluorocyclobutane.

[0064] Post-processing:

[0065] Condensation and cooling: The collected crude octafluorocyclobutane gas is passed through a condenser at 0-5°C for condensation and cooling.

[0066] Removal of hydrogen fluoride: The condensed gas is further processed through a hydrogen fluoride removal tower filled with sodium fluoride particles to remove hydrogen fluoride and other components.

[0067] Collect the product: collect the gas after removing hydrogen fluoride into a cold trap to obtain the product octafluorocyclobutane.

[0068] Example 3

[0069] Electrolytic plate preparation:

[0070] Material preparation: Select nickel metal plates as cathode electrode plates and anode electrode plates, clean and dry the metal plates to ensure that the surface of the electrode plates is flat, free of rust and pollution.

[0071] Punching: Use a punching tool to evenly punch circular holes on the cathode electrode plate and the anode electrode plate. The diameter of the circular holes is 5 mm, and the spacing between the circular holes is kept at 7 to 9 mm to ensure uniform distribution of the electrolyte and uniform transmission of the current.

[0072] Cross arrangement: The cathode electrode plates and anode electrode plates with holes are arranged crosswise, and the spacing between the cross-arranged cathode electrode plates and anode electrode plates is controlled at 3 to 6 mm to ensure a good spacing between the cathode and anode to facilitate the flow and reaction of the electrolyte.

[0073] Insulation treatment: Insert a PTFE gasket made of insulating material between the cathode electrode plate and the anode electrode plate with a spacing of 2 to 3 mm to prevent short circuit during the electrolysis process.

[0074] Preparation of electrolyte: Mixed solution: According to the molar ratio of potassium fluoride to anhydrous hydrogen fluoride of 1:8, accurately weigh potassium fluoride and anhydrous hydrogen fluoride, pour them into the electrolytic cell, and stir for 20 minutes.

[0075] Dehydration treatment: Place the mixed solution in an electrolytic cell, connect the power supply, adjust the voltage to 5V, the current to 3A, and continue to power on for 0.5 hours to ensure that the water in the mixed solution is removed.

[0076] Preparation of octafluorocyclobutane by electrolysis:

[0077] Dehydration of dichlorohexafluorocyclobutane: Pour dichlorohexafluorocyclobutane into the molecular sieve dehydration device and use 3A, 4A or 5A molecular sieve for adsorption dehydration treatment. Use the detection instrument to detect the water content of dichlorohexafluorocyclobutane to be 8ppm, and then proceed to the next step.

[0078] Adding dichlorohexafluorocyclobutane: add the dehydrated dichlorohexafluorocyclobutane to the dehydrated electrolyte at a ratio of 7% by mass of the mixed solution, and stir thoroughly for 20 minutes.

[0079] Electrolysis condition setting: The reaction temperature is controlled at 10°C by adjusting the refrigerant circulation volume of the electrolytic cell jacket. At the same time, the voltage of the electrolytic cell is adjusted to the range of 5-6V and the current is controlled between 35A and 37A to ensure that the electrolysis reaction is carried out under stable conditions.

[0080] Electrolysis reaction: Turn on the power and start the electrolysis reaction. During the electrolysis process, the changes in reaction temperature and current are monitored in real time to ensure that the reaction proceeds smoothly under the set conditions.

[0081] Collect crude product: After the electrolysis reaction is completed, collect the gas produced by the reaction, which is the crude octafluorocyclobutane.

[0082] Post-processing:

[0083] Condensation and cooling: The collected crude octafluorocyclobutane gas is passed through a condenser at 0-5°C for condensation and cooling.

[0084] Removal of hydrogen fluoride: The condensed gas is further processed through a hydrogen fluoride removal tower filled with sodium fluoride particles to remove hydrogen fluoride and other components.

[0085] Collect the product: collect the gas after removing hydrogen fluoride into a cold trap to obtain the product octafluorocyclobutane.

[0086] Example 4

[0087] Electrolytic plate preparation:

[0088] Material preparation: Select nickel metal plates as cathode electrode plates and anode electrode plates, clean and dry the metal plates to ensure that the surface of the electrode plates is flat, free of rust and pollution.

[0089] Punching: Use a punching tool to evenly punch circular holes on the cathode electrode plate and the anode electrode plate. The diameter of the circular holes is controlled within the range of 1 to 3 mm, and the spacing between the circular holes is maintained at 10 to 15 mm to ensure uniform distribution of the electrolyte and uniform transmission of the current.

[0090] Cross arrangement: The cathode electrode plates and anode electrode plates with holes are arranged crosswise, and the spacing between the cross-arranged cathode electrode plates and anode electrode plates is controlled at 6 to 8 mm to ensure a good spacing between the cathode and anode to facilitate the flow and reaction of the electrolyte.

[0091] Insulation treatment: Insert a PTFE gasket made of insulating material between the cathode electrode plate and the anode electrode plate with a spacing of 2 to 3 mm to prevent short circuit during the electrolysis process.

[0092] Electrolyte preparation:

[0093] Mixing solution: According to the molar ratio of potassium fluoride to anhydrous hydrogen fluoride of 1:15, accurately weigh potassium fluoride and anhydrous hydrogen fluoride, and pour into the electrolytic cell, stir for 20 min.

[0094] Dehydration treatment: Place the mixed solution in the electrolytic cell, turn on the power, adjust the voltage to 5V, and the current to 3A, and continue to power on for 1 hour to ensure that the water in the mixed solution is removed.

[0095] Electrolytic preparation of octafluorocyclobutane:

[0096] Dehydration of dichlorohexafluorocyclobutane: Pour the dichlorohexafluorocyclobutane into the molecular sieve dehydration device, use 3A, 4A or 5A molecular sieve for adsorption dehydration treatment, and use the detection instrument to detect the moisture content of the dichlorohexafluorocyclobutane to be 10ppm, and proceed to the next step.

[0097] Add dichlorohexafluorocyclobutane: Add the dehydrated dichlorohexafluorocyclobutane to the electrolyte that has been dehydrated according to the proportion of 15% of the mixed solution quality, and stir thoroughly for 20 min.

[0098] Electrolysis condition setting: Adjust the reaction temperature to 10℃ by adjusting the circulation amount of electrolytic cell jacket coolant, at the same time, adjust the voltage of electrolytic cell to 8-10V, and control the current between 12A-17A, to ensure that the electrolysis reaction is carried out in stable conditions.

[0099] Electrolysis reaction: Turn on the power and start the electrolysis reaction. During the electrolysis process, monitor the changes of reaction temperature and current in real time to ensure that the reaction proceeds smoothly under the set conditions.

[0100] Collecting crude product: After the electrolysis reaction is completed, collect the gas produced by the reaction, which is the crude octafluorocyclobutane.

[0101] Post-treatment:

[0102] Condensation cooling: The collected crude octafluorocyclobutane gas is cooled by a condenser at 0-5℃.

[0103] Remove hydrogen fluoride: The condensed gas is further treated by a hydrogen fluoride removal tower filled with sodium fluoride particles to remove hydrogen fluoride and other components.

[0104] Collect the product: Collect the gas after removing hydrogen fluoride into a cold trap to obtain the product octafluorocyclobutane.

[0105] Example 5

[0106] Preparation of electrolytic plate:

[0107] Material preparation: Select a nickel metal plate as the cathode and anode electrode plates, clean and dry the metal plates to ensure that the surface of the electrode plates is flat, free of rust and contamination.

[0108] Punching: Use a punching tool to evenly punch circular holes on the cathode electrode plate and the anode electrode plate. The diameter of the circular holes is controlled within the range of 8 to 10 mm, and the spacing between the circular holes is maintained at 15 to 20 mm to ensure uniform distribution of the electrolyte and uniform transmission of the current.

[0109] Cross arrangement: The cathode electrode plates and anode electrode plates with holes are arranged crosswise, and the spacing between the cross-arranged cathode electrode plates and anode electrode plates is controlled at 6 to 8 mm to ensure a good spacing between the cathode and anode to facilitate the flow and reaction of the electrolyte.

[0110] Insulation treatment: Insert a PTFE gasket made of insulating material between the cathode electrode plate and the anode electrode plate with a spacing of 2 to 3 mm to prevent short circuit during the electrolysis process.

[0111] Electrolyte preparation:

[0112] Mixed solution: Accurately weigh potassium fluoride and anhydrous hydrogen fluoride according to the molar ratio of potassium fluoride to anhydrous hydrogen fluoride of 1:10, pour into the electrolytic cell, and stir for 20 minutes.

[0113] Dehydration treatment: Place the mixed solution in an electrolytic cell, connect the power supply, adjust the voltage to 5V and the current to 3A, and continue to power on for 1 hour to ensure that the water in the mixed solution is removed.

[0114] Preparation of octafluorocyclobutane by electrolysis:

[0115] Dehydration of dichlorohexafluorocyclobutane: Pour dichlorohexafluorocyclobutane into a molecular sieve dehydration device and use 3A, 4A or 5A molecular sieve for adsorption dehydration treatment. Use a detection instrument to detect the water content of dichlorohexafluorocyclobutane to be 7ppm, and then proceed to the next step.

[0116] Adding dichlorohexafluorocyclobutane: add the dehydrated dichlorohexafluorocyclobutane to the dehydrated electrolyte at a ratio of 10% of the mass of the mixed solution, and stir thoroughly for 20 minutes.

[0117] Electrolysis condition setting: The reaction temperature is controlled at 10°C by adjusting the refrigerant circulation volume of the electrolytic cell jacket. At the same time, the voltage of the electrolytic cell is adjusted to the range of 17 to 20 V, and the current is controlled between 40 A and 45 A to ensure that the electrolysis reaction is carried out under stable conditions.

[0118] Electrolysis reaction: Turn on the power and start the electrolysis reaction. During the electrolysis process, the changes in reaction temperature and current are monitored in real time to ensure that the reaction proceeds smoothly under the set conditions.

[0119] Collect crude product: After the electrolysis reaction is completed, collect the gas produced by the reaction, which is the crude octafluorocyclobutane.

[0120] Post-processing:

[0121] Condensation and cooling: The collected crude octafluorocyclobutane gas is passed through a condenser at 0-5°C for condensation and cooling.

[0122] Removal of hydrogen fluoride: The condensed gas is further processed through a hydrogen fluoride removal tower filled with sodium fluoride particles to remove hydrogen fluoride and other components.

[0123] Collect the product: collect the gas after removing hydrogen fluoride into a cold trap to obtain the product octafluorocyclobutane.

[0124] Comparative Example 1

[0125] The technical feature that distinguishes this comparative example from Example 1 is that the molar ratio of potassium fluoride to anhydrous hydrogen fluoride in this comparative example is 1:20.

[0126] Comparative Example 2

[0127] The technical feature that distinguishes this comparative example from Example 1 is that the amount of dichlorohexafluorocyclobutane added in this comparative example is 25% of the mass of the mixed solution.

[0128] Comparative Example 3

[0129] The technical feature that distinguishes this comparative example from Example 1 is that the heating temperature of this comparative example is 3°C.

[0130] Comparative Example 4

[0131] The technical feature that distinguishes this comparative example from Example 1 is that the electrolysis voltage of this comparative example is 5V.

[0132] Performance Testing

[0133] The purity and yield of the octafluorocyclobutane obtained in Examples 1 to 4 and Comparative Examples 1 to 4 were tested, and the results are shown in Table 1.

[0134] Table 1

[0135] sample Product purity (%) Conversion rate (%) Example 1 86 54 Example 2 80 58 Example 3 83 68 Example 4 80 39 Comparative Example 1 56 37 Comparative Example 2 66 29 Comparative Example 3 63 35 Comparative Example 4 52 24

[0136] From the purity and yield of octafluorocyclobutane obtained in Examples 1 to 4 and Comparative Examples 1 to 4, it can be seen that within the parameter range set in the present application, the purity and yield of octafluorocyclobutane are high, wherein the purity of the product can reach up to 86% and the yield can reach up to 68%.

[0137] The above description is merely a preferred embodiment of the present application and does not constitute any form of limitation to the present application. Although the present application has been disclosed as above with preferred embodiments, it is not intended to limit the present application. Any person skilled in the art can make some changes or modifications to equivalent embodiments using the technical contents disclosed above without departing from the scope of the technical solution of the present application. However, any modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present application without departing from the content of the technical solution of the present application are still within the scope of the technical solution of the present application.

Claims

1. A method for preparing octafluorocyclobutane by electrolysis of dichlorohexafluorocyclobutane, characterized in that: The steps include: Step S1. Electrolyte preparation Mix potassium fluoride and anhydrous hydrogen fluoride in a molar ratio of 1:1 to 1:15, dehydrate the mixture to obtain a mixed solution, and add the mixed solution to the electrolytic cell; Step S2. Preparation of octafluorocyclobutane by electrolysis First, dichlorohexafluorocyclobutane is removed from water and then added to the mixed solution, mixed evenly, heated and energized to obtain crude octafluorocyclobutane, wherein the amount of dichlorohexafluorocyclobutane added is 5-15% of the mass of the mixed solution, the heating temperature is 5-25°C, the energizing voltage is 4-20V, and the current is 12-45A; In which, the electrolytic cell in step S1 is provided with a plurality of alternating cathode electrode plates and anode electrode plates along a linear array, and the electrode plates are all arranged vertically; insulating material is padded between adjacent cathode electrode plates and anode electrode plates; circular holes for electrolyte circulation are evenly opened on the cathode electrode plates and anode electrode plates, and the diameter of the circular holes is 1 to 10 mm; the spacing between two adjacent circular holes on the same electrode plate is 5 to 20 mm; the spacing between adjacent cathode plates and anode plates is 1 to 8 mm.

2. The method for preparing octafluorocyclobutane by electrolysis of dichlorohexafluorocyclobutane according to claim 1, characterized in that: The diameter of the circular holes is 3-5 mm; the distance between two adjacent circular holes on the same electrode plate is 5-10 mm; and the distance between adjacent cathode plates and anode plates is 2-3 mm.

3. The method for preparing octafluorocyclobutane by electrolysis of dichlorohexafluorocyclobutane according to claim 1, characterized in that: The insulating material includes multiple polytetrafluoroethylene gaskets, which are evenly distributed on the side walls of the cathode electrode plate or the anode electrode plate and are used to separate the cathode electrode plate and the anode electrode plate. The distance between two adjacent polytetrafluoroethylene gaskets is 2 to 3 mm.

4. The method for preparing octafluorocyclobutane by electrolysis of dichlorohexafluorocyclobutane according to claim 1, characterized in that: The molar ratio of potassium fluoride to anhydrous hydrogen fluoride is 1:1 to 1:

8.

5. The method for preparing octafluorocyclobutane by electrolysis of dichlorohexafluorocyclobutane according to claim 1, characterized in that: The dehydration process: the power-on voltage is 5V, the power-on current is 3-5A, and the power-on time is 0.5-2h.

6. The method for preparing octafluorocyclobutane by electrolysis of dichlorohexafluorocyclobutane according to claim 1, characterized in that: The dichlorohexafluorocyclobutane dehydration process comprises: removing water from the dichlorohexafluorocyclobutane by adsorption with an adsorption material until the water content is reduced to below 10 ppm, and the adsorption material is any one of 3A molecular sieve, 4A molecular sieve or 5A molecular sieve.

7. The method for preparing octafluorocyclobutane by electrolysis of dichlorohexafluorocyclobutane according to claim 1, characterized in that: The added amount of dichlorohexafluorocyclobutane is 5-8% of the mass of the mixed solution, the heating temperature is 10-20° C., the voltage is 4-7V, and the current is 25-37A.

8. The method for preparing octafluorocyclobutane by electrolysis of dichlorohexafluorocyclobutane according to claim 1, characterized in that: The steps also include: Step S3: condensing the crude octafluorocyclobutane at 0-5° C. and then passing it into a hydrogen fluoride removal tower to absorb hydrogen fluoride to obtain the product octafluorocyclobutane.