Preparation method of perfluoromethyl vinyl ether

Abstract

The invention relates to the technical field of fluorine-containing monomer synthesis, in particular to a preparation method of perfluoromethyl vinyl ether. The preparation method of the perfluoromethyl vinyl ether comprises the following steps: reacting fluorophosgene and hexafluoropropylene oxide under the catalysis of iodide to generate perfluoro-2-methoxypropionyl fluoride, and performing catalytic pyrolysis through zinc oxide-zirconium oxide to generate the perfluoromethyl vinyl ether. According to the method, when iodide is adopted as a catalyst in the reaction step of hexafluoropropylene oxide and fluorophosgene, self-polymerization of hexafluoropropylene oxide can be greatly reduced, most of hexafluoropropylene oxide participates in the reaction, and the yield of perfluoro-2-methoxypropionyl fluoride can be greatly increased to 85% or above. The solid solution formed by the zinc oxide-zirconium oxide catalyst can ensure the activity of efficiently catalyzing the pyrolytic reaction of perfluoro-2-methoxypropionyl fluoride, and meanwhile, the stability of the zinc oxide-zirconium oxide catalyst can be improved, and the service life of the zinc oxide-zirconium oxide catalyst is prolonged.

Description

Technical Field

[0001] The invention relates to the technical field of fluorine-containing monomer synthesis, and in particular to a method for preparing perfluoromethyl vinyl ether. Background Art

[0002] Perfluoromethyl vinyl ether (CF3OCF=CF2, PMVE for short) is an important fluorine-containing monomer that can be used to synthesize high-performance fluororubber and modify polytetrafluoroethylene. A small amount of perfluoromethyl vinyl ether is introduced into polytetrafluoroethylene to form a new polymer material, which improves its processing properties while retaining the excellent properties of polytetrafluoroethylene, making it easier to process. Depending on the raw materials, the synthesis methods of perfluoromethyl vinyl ether can be mainly divided into fluorooxytrifluoromethane method, perfluoro-2-methoxypropionyl fluoride method, and fluorophosgene method.

[0003] The fluorooxytrifluoromethane method uses fluorooxytrifluoromethane (CF3OF) and 1,2-difluoro-1,2-dichloroethylene (CFCl=CFCl) as raw materials to react to generate trifluoromethyl-1,2-dichloro-1,2,2-trifluorovinyl ether (CF3OCClFCClF2), and CF3OCClFCClF2 removes HCl under the action of zinc powder to obtain PMVE. Patent CN1775722A discloses a process for preparing perfluoromethyl vinyl ether by dechlorination reaction of trifluoromethyl-1,1,2-trifluoro-1,2-dichloro-ethyl ether, using dimethylformamide as solvent, or adding iodine as activator, and collecting the crude perfluoro(methyl vinyl) ether monomer in the gas phase out of the reflux condenser in a dry ice cold trap at -78°C. The raw material of this method, fluorooxytrifluoromethane, is flammable, explosive and highly toxic, and is a dangerous fluorination agent, which limits the industrial application of this raw material. In addition, the second step reaction uses zinc powder reduction, which consumes a large amount of zinc powder and solvent and is relatively costly.

[0004] The perfluoro-2-methoxypropionyl fluoride method uses perfluoro-2-methoxypropionyl fluoride as a raw material and synthesizes PMVE through two methods: catalyst and alkali metal salt. Patent US3321532 discloses a method of catalytically pyrolyzing perfluoro-2-methoxypropionyl fluoride using zinc oxide, calcium oxide, aluminum oxide, barium oxide, etc. as catalysts, wherein zinc oxide and calcium oxide have good catalytic activity, and the PMVE yield can reach 95%. Lebedev et al. reported a method for synthesizing PMVE, which is: at a reaction temperature of 120 ° C, using diethylene glycol dimethyl ether as a solvent, perfluoro-2-methoxypropionyl fluoride and sodium carbonate react to generate CF3OCF2CF2COONa, and then CF3OCF2CF2COONa is heated to remove the acyl fluoride group to form PMVE, with a yield of 95%. However, the perfluoro-2-methoxypropionyl fluoride method consumes a large amount of alkali metal carbonates, sulfates, hydroxides, etc., and the cycle for obtaining PMVE products is relatively long.

[0005] The fluorophosgene method uses fluorophosgene (COF2) as a raw material, reacts with fluoride salt (MF) to form trifluoromethanolate (CF3OM), and trifluoromethanolate reacts with tetrafluoroethylene to obtain PMVE. The advantages of this method are mild reaction conditions, simple equipment, and low production cost, but the yield of trifluoromethoxy salt generated in the first step of the reaction is low, and the reaction time in the second step is too long. Fluorophosgene can also react with hexafluoropropylene oxide to obtain perfluoro-2-methoxypropionyl fluoride, and then perfluoro-2-methoxypropionyl fluoride reacts with alkali metal carbonate to form carboxylate, and perfluoromethyl vinyl ether can be obtained after thermal decomposition of the carboxylate. Patent US3114778 uses alkali metal fluoride and activated carbon as catalysts, diethylene glycol dimethyl ether as solvent to react with hexafluoropropylene oxide to obtain perfluoro-2-methoxy acyl fluoride, and the perfluoro-2-methoxypropionyl fluoride is removed by alkali metal carbonate or sulfate to form perfluoroalkane vinyl ether. When activated carbon is used as the catalyst in the first step, the yield of perfluoro-2-methoxypropionyl fluoride is 33% and the conversion rate of hexafluoropropylene oxide is 96.4%; when cesium fluoride is used as the catalyst, the yield is 68%. When K2SO4 is used as the catalyst in the second step, the yield of PMVE is 60%. In the second step, perfluoro-2-methoxypropionyl fluoride reacts with KOH to form potassium 2-methoxypropionate (CF3OCF2CF2COOK), which is then heated at 200°C for 24 hours to be completely converted into PMVE. The most promising industrial production method is to prepare perfluoro-2-methoxypropionyl fluoride with hexafluoropropylene oxide as raw materials and then obtain PMVE. However, the yield of perfluoro-2-methoxypropionyl fluoride in the first step in the currently published literature is not high, mainly because hexafluoropropylene oxide easily self-polymerizes to form self-polymers.

[0006] In view of this, the present invention is proposed. Summary of the invention

[0007] In order to solve the above problems, the present invention provides a method for preparing perfluoromethyl vinyl ether by reacting fluorophosgene with hexafluoropropylene oxide, which has lower cost and higher yield.

[0008] Specifically, the technical solution provided by the present invention is as follows: In a first aspect, the present invention provides a method for preparing perfluoromethyl vinyl ether, comprising the following steps: (1) catalyzing the reaction of fluorophosgene and hexafluoropropylene oxide with iodide to generate perfluoro-2-methoxypropionyl fluoride; wherein the amount of iodide used is 0.5% to 3% of the molar amount of fluorophosgene; and (2) catalytically pyrolyzing perfluoro-2-methoxypropionyl fluoride to generate perfluoromethyl vinyl ether.

[0009] Preferably, the iodide includes but is not limited to at least one of potassium iodide, sodium iodide, calcium iodide and magnesium iodide; more preferably, it is potassium iodide.

[0010] Preferably, the molar ratio of fluorophosgene to hexafluoropropylene oxide is 1:1.3-1.8.

[0011] Preferably, the reaction temperature of fluorophosgene and hexafluoropropylene oxide is 60-150°C.

[0012] Preferably, the catalyst used in catalytic pyrolysis is ZnO-ZrO2.

[0013] Preferably, ZnO-ZrO2 is prepared by using zinc nitrate and zirconium nitrate as raw materials through a precipitation method and then calcined.

[0014] More preferably, the molar ratio of zinc nitrate to zirconium nitrate is 1.1-1.3:1, and the calcination temperature is 400-600°C.

[0015] Preferably, the reaction temperature of the catalytic pyrolysis is 300-500°C.

[0016] Preferably, in the catalytic pyrolysis reaction, the contact time between perfluoro-2-methoxypropionyl fluoride and the catalyst is 3-10 min.

[0017] As one of the more preferred specific embodiments, the present invention provides a method for preparing perfluoromethyl vinyl ether, comprising the following steps: S1. Using iodide as a catalyst, catalyzing the reaction of fluorophosgene and hexafluoropropylene oxide to generate perfluoro-2-methoxypropionyl fluoride, wherein the amount of the catalyst added is 0.5% to 3% of the molar amount of the added fluorophosgene, the molar ratio of fluorophosgene to hexafluoropropylene oxide is 1:1.3 to 1.8, and the reaction temperature is 60 to 150°C; S2, dissolving zinc nitrate and zirconium nitrate in deionized water to prepare a mixed metal salt aqueous solution; dissolving ammonium carbonate in deionized water to prepare an ammonium carbonate aqueous solution; slowly adding the ammonium carbonate aqueous solution dropwise to the mixed metal salt aqueous solution to form a precipitate, filtering, drying, and calcining after the precipitation to obtain a ZnO-ZrO2 catalyst; S3, passing perfluoro-2-methoxypropionyl fluoride into a fixed bed reactor filled with ZnO-ZrO2 catalyst to catalyze and thermally decompose to generate perfluoromethyl vinyl ether.

[0018] Beneficial effects: The present invention provides a method for preparing perfluoromethyl vinyl ether, wherein iodide is used to catalyze the reaction of fluorophosgene and hexafluoropropylene oxide to generate perfluoro-2-methoxypropionyl fluoride, and then zinc oxide-zirconium oxide is used to catalyze thermal decomposition to generate perfluoromethyl vinyl ether. When iodide is used as a catalyst in the step of reacting hexafluoropropylene oxide with fluorophosgene, the self-polymerization of hexafluoropropylene oxide can be greatly reduced, and most of the hexafluoropropylene oxide participates in the reaction, which can greatly increase the yield of perfluoro-2-methoxypropionyl fluoride to more than 85%. The solid solution formed by the zinc oxide-zirconium oxide catalyst can ensure the high-efficiency catalytic activity of the thermal decomposition reaction of perfluoro-2-methoxypropionyl fluoride, and at the same time can improve the stability of the zinc oxide-zirconium oxide catalyst and extend the service life. DETAILED DESCRIPTION

[0019] The present invention provides a method for preparing perfluoromethyl vinyl ether, wherein fluorophosgene and hexafluoropropylene oxide are used as raw materials, perfluoro-2-methoxypropionyl fluoride is generated under the action of a catalyst, and the perfluoro-2-methoxypropionyl fluoride is catalytically cracked to generate perfluoromethyl vinyl ether. The preparation method provided by the present invention can greatly improve the yield of perfluoro-2-methoxypropionyl fluoride, and the yield of perfluoromethyl vinyl ether is high, and has good industrialization prospects.

[0020] Specifically, the preparation method provided by the present invention comprises the following steps: (1) Using iodide as a catalyst, fluorophosgene and hexafluoropropylene oxide are catalyzed to react to generate perfluoro-2-methoxypropionyl fluoride, wherein the amount of the catalyst added is 0.5% to 3% of the molar amount of fluorophosgene added, the molar ratio of fluorophosgene to hexafluoropropylene oxide is 1:1.3 to 1.8, and the reaction temperature is 60 to 150°C.

[0021] (2) Dissolve zinc nitrate and zirconium nitrate in deionized water to prepare a mixed metal salt aqueous solution; dissolve ammonium carbonate in deionized water to prepare an ammonium carbonate aqueous solution; slowly add the ammonium carbonate aqueous solution to the mixed metal salt aqueous solution to form a precipitate, and after the precipitation is complete, filter, dry, and calcine to obtain a ZnO-ZrO2 catalyst.

[0022] (3) Perfluoro-2-methoxypropionyl fluoride is introduced into a fixed bed reactor filled with ZnO-ZrO2 catalyst to catalytically pyrolyze and generate PMVE.

[0023] In the present invention, the iodide in step (1) is preferably selected from potassium iodide, sodium iodide, calcium iodide and magnesium iodide.

[0024] In the present invention, the molar ratio of zinc nitrate to zirconium nitrate in step (2) is preferably 1.1-1.3:1, and the calcination temperature is preferably 400-600°C.

[0025] In the present invention, the catalytic pyrolysis temperature in step (3) is preferably 300-500°C.

[0026] In the present invention, the contact time between the perfluoro-2-methoxypropionyl fluoride and the catalyst in step (3) is preferably 3-10 min.

[0027] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] The endpoints and any values ​​of the ranges disclosed in this specification are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0029] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "specific implementations", or "some specific implementations" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the embodiment of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0030] In the examples provided in this specification, if no specific techniques or conditions are specified, the techniques or conditions described in the literature in this field or the product instructions are used. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased through regular channels.

[0031] Example 1 This embodiment provides a method for preparing perfluoromethyl vinyl ether, and the specific steps are as follows.

[0032] In a 20L autoclave, 100g potassium iodide and 2L tetraethylene glycol dimethyl ether were added, and 4Kg fluorophosgene was added after evacuating the air and replacing the nitrogen. The temperature was raised, and hexafluoropropylene oxide was slowly introduced after the temperature reached 60°C. The total weight of hexafluoropropylene oxide added was 15Kg. After the reaction was completed, the yield of perfluoro-2-methoxypropionyl fluoride was calculated to be 92%. 210g zinc nitrate and 340g zirconium nitrate were dissolved in deionized water to prepare a mixed metal salt aqueous solution; ammonium carbonate was dissolved in deionized water to prepare an ammonium carbonate aqueous solution; the ammonium carbonate aqueous solution was slowly added dropwise to the mixed metal salt aqueous solution to form a precipitate. After the precipitation was complete, the catalyst was filtered, dried, and calcined at 400°C to obtain the ZnO-ZrO2-400 catalyst. Perfluoro-2-methoxypropionyl fluoride was introduced into a fixed bed reactor filled with ZnO-ZrO2-400 catalyst for catalytic pyrolysis reaction. The reaction temperature was 400 °C, and the contact time between perfluoro-2-methoxypropionyl fluoride and the catalyst was 5 min. After the reaction, it was measured that perfluoro-2-methoxypropionyl fluoride was completely cracked to form perfluoromethyl vinyl ether.

[0033] Example 2 This embodiment provides a method for preparing perfluoromethyl vinyl ether, and the specific steps are as follows.

[0034] In a 20L autoclave, 45g of sodium iodide and 2L of tetraethylene glycol dimethyl ether were added, and 4Kg of fluorophosgene was added after evacuating the air and replacing the nitrogen. The temperature was raised, and hexafluoropropylene oxide was slowly introduced after the temperature reached 80°C. The total weight of hexafluoropropylene oxide added was 13Kg. After the reaction was completed, the yield of perfluoro-2-methoxypropionyl fluoride was calculated to be 88%. 230g of zinc nitrate and 340g of zirconium nitrate were dissolved in deionized water to prepare a mixed metal salt aqueous solution; ammonium carbonate was dissolved in deionized water to prepare an ammonium carbonate aqueous solution; the ammonium carbonate aqueous solution was slowly added dropwise to the mixed metal salt aqueous solution to form a precipitate. After the precipitation was complete, it was filtered, dried, and calcined at 500°C to obtain the ZnO-ZrO2-500 catalyst. Perfluoro-2-methoxypropionyl fluoride was introduced into a fixed bed reactor filled with ZnO-ZrO2-500 catalyst for catalytic pyrolysis reaction. The reaction temperature was 300 °C, and the contact time between perfluoro-2-methoxypropionyl fluoride and the catalyst was 8 min. After the reaction, it was measured that perfluoro-2-methoxypropionyl fluoride was completely cracked to form perfluoromethyl vinyl ether.

[0035] Example 3 This embodiment provides a method for preparing perfluoromethyl vinyl ether, and the specific steps are as follows.

[0036] 350 g of calcium iodide and 2 L of tetraethylene glycol dimethyl ether were added to a 20 L autoclave. After evacuating the air and replacing it with nitrogen, 4 kg of fluorophosgene was added. The temperature was raised. After the temperature reached 120 °C, hexafluoropropylene oxide was slowly introduced. The total weight of hexafluoropropylene oxide added was 14 kg. After the reaction was completed, the yield of perfluoro-2-methoxypropionyl fluoride was calculated to be 86%. 210 g of zinc nitrate and 340 g of zirconium nitrate were dissolved in deionized water to prepare a mixed metal salt aqueous solution; ammonium carbonate was dissolved in deionized water to prepare an ammonium carbonate aqueous solution; the ammonium carbonate aqueous solution was slowly added dropwise to the mixed metal salt aqueous solution to form a precipitate. After the precipitation was complete, it was filtered, dried, and calcined at 600 °C to obtain the ZnO-ZrO2-600 catalyst. Perfluoro-2-methoxypropionyl fluoride was introduced into a fixed bed reactor filled with ZnO-ZrO2-600 catalyst for catalytic pyrolysis reaction. The reaction temperature was 400 °C, and the contact time between perfluoro-2-methoxypropionyl fluoride and the catalyst was 6 min. After the reaction, it was measured that perfluoro-2-methoxypropionyl fluoride was completely cracked to form perfluoromethyl vinyl ether.

[0037] Example 4 This embodiment provides a method for preparing perfluoromethyl vinyl ether, and the specific steps are as follows.

[0038] 170 g of magnesium iodide and 2 L of tetraethylene glycol dimethyl ether were added to a 20 L autoclave. After evacuating the air and replacing it with nitrogen, 4 kg of fluorophosgene was added. The temperature was raised. After the temperature reached 100 ° C, hexafluoropropylene oxide was slowly introduced. The total weight of hexafluoropropylene oxide added was 18 kg. After the reaction was completed, the yield of perfluoro-2-methoxypropionyl fluoride was calculated to be 85%. 210 g of zinc nitrate and 340 g of zirconium nitrate were dissolved in deionized water to prepare a mixed metal salt aqueous solution; ammonium carbonate was dissolved in deionized water to prepare an ammonium carbonate aqueous solution; the ammonium carbonate aqueous solution was slowly added dropwise to the mixed metal salt aqueous solution to form a precipitate. After the precipitation was complete, it was filtered, dried, and calcined at 450 ° C to obtain the ZnO-ZrO2-450 catalyst. Perfluoro-2-methoxypropionyl fluoride was introduced into a fixed bed reactor filled with ZnO-ZrO2-450 catalyst for catalytic pyrolysis reaction. The reaction temperature was 300 °C, and the contact time between perfluoro-2-methoxypropionyl fluoride and the catalyst was 10 min. After the reaction, it was measured that perfluoro-2-methoxypropionyl fluoride was completely cracked to form perfluoromethyl vinyl ether.

[0039] Example 5 This embodiment provides a method for preparing perfluoromethyl vinyl ether, and the specific steps are as follows.

[0040] 300 g potassium iodide and 2 L tetraethylene glycol dimethyl ether were added to a 20 L autoclave. After evacuating the air and replacing it with nitrogen, 4 kg of fluorophosgene was added. The temperature was raised. After the temperature reached 150 ° C, hexafluoropropylene oxide was slowly introduced. The total weight of hexafluoropropylene oxide added was 16 kg. After the reaction was completed, the yield of perfluoro-2-methoxypropionyl fluoride was calculated to be 92%. 210 g zinc nitrate and 340 g zirconium nitrate were dissolved in deionized water to prepare a mixed metal salt aqueous solution; ammonium carbonate was dissolved in deionized water to prepare an ammonium carbonate aqueous solution; the ammonium carbonate aqueous solution was slowly added dropwise to the mixed metal salt aqueous solution to form a precipitate. After the precipitation was complete, it was filtered, dried, and calcined at 550 ° C to obtain the ZnO-ZrO2-550 catalyst. Perfluoro-2-methoxypropionyl fluoride was introduced into a fixed bed reactor filled with ZnO-ZrO2-550 catalyst for catalytic pyrolysis reaction. The reaction temperature was 500 °C, and the contact time between perfluoro-2-methoxypropionyl fluoride and the catalyst was 3 min. After the reaction, it was measured that perfluoro-2-methoxypropionyl fluoride was completely cracked to form perfluoromethyl vinyl ether.

[0041] Example 6 This embodiment provides a method for preparing perfluoromethyl vinyl ether, and the specific steps are as follows.

[0042] In a 20L autoclave, 100g potassium iodide and 2L tetraethylene glycol dimethyl ether were added, and 4Kg fluorophosgene was added after evacuating the air and replacing the nitrogen. The temperature was raised, and hexafluoropropylene oxide was slowly introduced after the temperature reached 60°C. The total weight of hexafluoropropylene oxide added was 15Kg. After the reaction was completed, the yield of perfluoro-2-methoxypropionyl fluoride was calculated to be 92%. 210g zinc nitrate and 340g zirconium nitrate were dissolved in deionized water to prepare a mixed metal salt aqueous solution; ammonium carbonate was dissolved in deionized water to prepare an ammonium carbonate aqueous solution; the ammonium carbonate aqueous solution was slowly added dropwise to the mixed metal salt aqueous solution to form a precipitate. After the precipitation was complete, the catalyst was filtered, dried, and calcined at 400°C to obtain the ZnO-ZrO2-400 catalyst. Perfluoro-2-methoxypropionyl fluoride was introduced into a fixed bed reactor filled with ZnO-ZrO2-400 catalyst for catalytic pyrolysis reaction. The reaction temperature was 400 ℃, and the contact time between perfluoro-2-methoxypropionyl fluoride and the catalyst was 5 minutes. After the reaction, it was measured that the perfluoro-2-methoxypropionyl fluoride was completely cracked to form perfluoromethyl vinyl ether. After the ZnO- ZrO2-400 catalyst was continuously operated in the fixed bed reactor for 72 hours, the conversion rate of perfluoro-2-methoxypropionyl fluoride decreased from 100% to 92%. After the catalyst was calcined at 400 ℃ for 2 hours after running for 72 hours, the cracking reaction of perfluoro-2-methoxypropionyl fluoride was catalyzed under the same conditions, and the conversion rate of perfluoro-2-methoxypropionyl fluoride was 98%.

[0043] Comparative Example 1 100 g of cesium fluoride and 2 L of tetraethylene glycol dimethyl ether were added to a 20 L autoclave. After evacuating the air and replacing it with nitrogen, 4 kg of fluorophosgene was added. The temperature was raised. After the temperature reached 60 °C, hexafluoropropylene oxide was slowly introduced. The total weight of hexafluoropropylene oxide added was 15 kg. After the reaction was completed, the yield of perfluoro-2-methoxypropionyl fluoride was calculated to be 58%. 210 g of zinc nitrate and 340 g of zirconium nitrate were dissolved in deionized water to prepare a mixed metal salt aqueous solution; ammonium carbonate was dissolved in deionized water to prepare an ammonium carbonate aqueous solution; the ammonium carbonate aqueous solution was slowly added dropwise to the mixed metal salt aqueous solution to form a precipitate. After the precipitation was complete, the catalyst was filtered, dried, and calcined at 400 °C to obtain the ZnO-ZrO2-400 catalyst. Perfluoro-2-methoxypropionyl fluoride was introduced into a fixed bed reactor filled with ZnO-ZrO2-400 catalyst for catalytic pyrolysis reaction. The reaction temperature was 400 °C, and the contact time between perfluoro-2-methoxypropionyl fluoride and the catalyst was 5 min. After the reaction, it was measured that perfluoro-2-methoxypropionyl fluoride was completely cracked to form perfluoromethyl vinyl ether.

[0044] Comparative Example 2 This embodiment provides a method for preparing perfluoromethyl vinyl ether, and the specific steps are as follows.

[0045] In a 20L autoclave, 100g potassium iodide and 2L tetraethylene glycol dimethyl ether were added, and 4Kg fluorophosgene was added after evacuating the nitrogen gas. The temperature was raised, and hexafluoropropylene oxide was slowly introduced after the temperature reached 60°C. The total weight of hexafluoropropylene oxide added was 15Kg. After the reaction was completed, the yield of perfluoro-2-methoxypropionyl fluoride was calculated to be 92%. 210g zinc nitrate was dissolved in deionized water to prepare a mixed metal salt aqueous solution; ammonium carbonate was dissolved in deionized water to prepare an ammonium carbonate aqueous solution; the ammonium carbonate aqueous solution was slowly added dropwise to the zinc nitrate aqueous solution to form a precipitate. After the precipitation was complete, it was filtered, dried, and calcined at 400°C to obtain the ZnO-400 catalyst. Perfluoro-2-methoxypropionyl fluoride was introduced into a fixed bed reactor filled with ZnO-400 catalyst for catalytic pyrolysis reaction. The reaction temperature was 400 ℃, and the contact time between perfluoro-2-methoxypropionyl fluoride and catalyst was 5 minutes. After the reaction, it was measured that perfluoro-2-methoxypropionyl fluoride was completely cracked to form perfluoromethyl vinyl ether. After the ZnO-400 catalyst was continuously operated in the fixed bed reactor for 72 hours, the conversion rate of perfluoro-2-methoxypropionyl fluoride decreased from 100% to 71%. After the catalyst was calcined at 400 ℃ for 2 hours after running for 72 hours, the cracking reaction of perfluoro-2-methoxypropionyl fluoride was catalyzed under the same conditions, and the conversion rate of perfluoro-2-methoxypropionyl fluoride was 88%.

[0046] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing perfluoromethyl vinyl ether, characterized in that: The method comprises the following steps: (1) using iodide to catalyze the reaction of fluorophosgene and hexafluoropropylene oxide to generate perfluoro-2-methoxypropionyl fluoride; wherein the amount of iodide used is 0.5% to 3% of the molar amount of fluorophosgene; and (2) catalytically pyrolyzing perfluoro-2-methoxypropionyl fluoride to generate perfluoromethyl vinyl ether.

2. The preparation method according to claim 1, characterized in that: The iodide includes but is not limited to at least one of potassium iodide, sodium iodide, calcium iodide, and magnesium iodide; preferably potassium iodide.

3. The preparation method according to claim 1 or 2, characterized in that: The molar ratio of fluorophosgene to hexafluoropropylene oxide is 1:1.3~1.

8.

4. The preparation method according to any one of claims 1 to 3, characterized in that: The reaction temperature of fluorophosgene and hexafluoropropylene oxide is 60~150℃.

5. The preparation method according to any one of claims 1 to 4, characterized in that: The catalyst used in catalytic pyrolysis is ZnO-ZrO2.

6. The preparation method according to claim 5, characterized in that: ZnO-ZrO2 is prepared by precipitation method and then calcined using zinc nitrate and zirconium nitrate as raw materials.

7. The preparation method according to claim 6, characterized in that: The molar ratio of zinc nitrate to zirconium nitrate is 1.1-1.3:1, and the calcination temperature is 400-600°C.

8. The preparation method according to any one of claims 1 to 7, characterized in that: The reaction temperature of catalytic pyrolysis is 300~500℃.

9. The preparation method according to any one of claims 1 to 7, characterized in that: In the catalytic pyrolysis reaction, the contact time between perfluoro-2-methoxypropionyl fluoride and the catalyst is 3-10 minutes.

10. The preparation method according to any one of claims 1 to 8, characterized in that: The steps include: S1. Using iodide as a catalyst, catalyzing the reaction of fluorophosgene and hexafluoropropylene oxide to generate perfluoro-2-methoxypropionyl fluoride, wherein the amount of the catalyst added is 0.5% to 3% of the molar amount of the added fluorophosgene, the molar ratio of fluorophosgene to hexafluoropropylene oxide is 1:1.3 to 1.8, and the reaction temperature is 60 to 150°C; S2, dissolving zinc nitrate and zirconium nitrate in deionized water to prepare a mixed metal salt aqueous solution; dissolving ammonium carbonate in deionized water to prepare an ammonium carbonate aqueous solution; slowly adding the ammonium carbonate aqueous solution dropwise to the mixed metal salt aqueous solution to form a precipitate, filtering, drying, and calcining after the precipitation to obtain a ZnO-ZrO2 catalyst; S3, passing perfluoro-2-methoxypropionyl fluoride into a fixed bed reactor filled with ZnO-ZrO2 catalyst to catalyze and thermally decompose to generate perfluoromethyl vinyl ether.