CN105906795A - Synthetic method for basic oil of perfluoropolyether lubricant oil - Google Patents

Abstract

The invention relates to a method for synthesizing perfluoropolyether lubricating oil base oil. Specifically, this paper discloses a method for synthesizing perfluoropolyether, comprising the steps of (1) synthesizing perfluoropolyether acyl fluoride and (2) synthesizing perfluoropolyether. The method has higher conversion rate of raw materials, higher average molecular weight of products, and the method is safer, simpler and lower in cost.

Description

A kind of synthetic method of perfluoropolyether lubricating oil base oil

technical field

The invention belongs to the field of polymer materials, and in particular relates to a method for synthesizing perfluoropolyether lubricating base oil.

Background technique

Perfluoropolyether is an important organic fluorine chemical product. Due to its excellent properties such as low surface energy, high thermodynamic stability, non-combustibility, high chemical inertness, and low friction coefficient, perfluoropolyether and its related products are widely used. Lubrication used in the fields of aerospace, electronics, machinery and nuclear industry has a great demand in the world.

At present, there are two main production methods of perfluoropolyether. One is the photo-oxidative polymerization technology of tetrafluoroethylene or hexafluoropropylene. This production technology has relatively low cost, but the yield is low, the process is complicated, and the degree of danger is high; The other is an anionic polymerization technology based on perfluoropropylene oxide or tetrafluorobutene oxide. This method has a relatively simple process flow and safe production, but it has more stringent reaction conditions, such as the purity of raw materials, reaction temperature, etc. The conditions will have a great impact on the conversion rate of raw materials in the reaction and the average degree of polymerization of the product. In addition, perfluoropolyether acid fluoride produced by anionic polymerization needs to undergo decarbonylation stabilization treatment before it can have better performance. At present, there are three main decarbonylation methods. Decarbonylation of polyether acyl fluoride, the catalyst used in this method has a high risk; one is to produce hydrogen-containing alkyl groups by decarbonylation of alkali hydrolysis, and then produce perfluoropolyether oil after fluorination of fluoride. Two-step reaction , This method is cumbersome; one is to decarbonize two molecules of perfluoropolyetheryl fluoride and photonyl fluoride by light radiation. This method produces a more dangerous product, photonyl fluoride, and is rarely used.

In the method disclosed in the prior art, it is also necessary to use metal hydride to remove impurities from hexafluoropropylene oxide, and add a diluent to reduce the viscosity of the material to prepare perfluoropolyether. This process has problems such as high cost of metal hydride, difficulty in recycling the diluent, low conversion rate of hexafluoropropylene oxide, and low average relative molecular weight of the product, which is difficult to meet industrial needs. At the same time, not only the process is cumbersome in the process of stabilizing the polymerization product, but also a lot of waste is generated.

Because the synthesis process of perfluoropolyether is complicated and the conditions are harsh, the production process urgently needs to be further improved to reduce production costs and increase the conversion rate of raw materials.

Contents of the invention

The purpose of the present invention is to provide a more effective and more economical synthesis method of perfluoropolyether.

In a first aspect of the present invention, a kind of synthetic method of perfluoropolyether is provided, comprising steps:

(1) Synthesis of perfluoropolyetheryl fluoride:

At -30 to -60°C, in a pressure vessel, the first solvent, the first catalyst, the initiator and hexafluoropropylene oxide are polymerized to form perfluoropolyetheryl fluoride;

(2) Synthesis of perfluoropolyether:

In a pressure vessel, the perfluoropolyether acid fluoride, the second solvent and the second catalyst in the step (1) are subjected to a decarbonylation reaction at 150-300° C. to form a perfluoropolyether.

In another preferred example, the polymerization reaction and/or the decarbonylation reaction are carried out under nitrogen protection or nitrogen atmosphere.

In another preferred example, step (1) is: under the protection of nitrogen, add the first solvent, the first catalyst and the initiator into the pressure vessel; Introducing hexafluoropropylene oxide into the pressure vessel for polymerization to form perfluoropolyetheryl fluoride; and/or

Step (2) is: add the perfluoropolyetheryl fluoride of step (1) into the pressure vessel, add the second solvent and the second catalyst under nitrogen atmosphere, and carry out the decarbonylation reaction at 150°C to 300°C, Thus forming a perfluoropolyether.

In another preferred example, the pressure vessel is a stainless steel pressure vessel.

In another preferred example, the pressure vessel is provided with a stirrer.

In another preferred example, the polymerization reaction is carried out at -40 to -50°C.

In another preferred example, the decarbonylation reaction is carried out at 200-250°C.

In another preferred embodiment, the first solvent or the second solvent is dried; and/or

The first solvent or the second solvent is an aprotic polar solvent.

In another preferred example, the first solvent or the second solvent is sequentially dewatered with 3A molecular sieves and refluxed with calcium oxide for 3-6 hours.

In another preferred example, the first solvent or the second solvent is a ketone solvent, an ether solvent, or a combination thereof.

In another preferred example, the ketone solvent is diisopropyl ketone and diisobutyl ketone.

In another preferred example, the ether solvent is ethylene glycol diethyl ether, diethylene glycol diethyl ether, triethylene glycol diethyl ether.

In another preferred example, before the hexafluoropropylene oxide is passed into the pressure vessel, the impurity is removed through a neutral water absorbing agent-basic compound-adsorbent.

In another preferred example, the neutral water-absorbing agent is anhydrous calcium chloride, silica gel, 3A molecular sieve, or a combination thereof.

In another preferred embodiment, the basic compound is calcium oxide, potassium hydroxide, sodium hydroxide, or a combination thereof.

In another preferred example, the adsorbent is activated alumina pellets.

In another preferred example, in step (1), the stirring is stopped after the reaction is completed and the lower liquid phase is separated to obtain the perfluoropolyetheryl fluoride.

In another preferred example, in step (2), liquid separation is performed after the reaction is complete, so as to obtain the perfluoropolyether.

In another preferred example, the first catalyst is a composition of alkali metal fluoride and alkali metal halide (non-fluorine); wherein, the alkali metal fluoride is cesium fluoride, rubidium fluoride, potassium fluoride , or a combination thereof; the alkali metal halide (non-fluorine) is sodium chloride, sodium bromide, potassium chloride, potassium bromide, potassium iodide, or a combination thereof.

In another preferred example, the first catalyst is dried; preferably, it is vacuum-dried at 140° C. for 4 hours.

In another preferred example, the mass ratio of the first catalyst to hexafluoropropylene oxide is 1:10-100.

In another preferred example, the mass ratio of the first catalyst to hexafluoropropylene oxide is 1:20-50.

In another preferred example, in the first catalyst, the mass ratio of alkali metal fluoride to alkali metal halide (non-fluorine) is 1:0.005-0.2.

In another preferred example, in the first catalyst, the mass ratio of alkali metal fluoride to alkali metal halide (non-fluorine) is 1:0.02-0.2.

In another preferred embodiment, the initiator is an acyl fluoride initiator selected from the group consisting of perfluorovaleryl fluoride, heptafluorobutyryl fluoride, or a combination thereof.

In another preferred example, the mass ratio of the initiator to hexafluoropropylene oxide is 1:50-200.

In another preferred example, the mass ratio of the initiator to hexafluoropropylene oxide is 1:100-200.

In another preferred embodiment, the second catalyst is aluminum chloride, aluminum bromide, cobalt fluoride, nickel chloride, or a combination thereof.

It should be understood that within the scope of the present invention, the above-mentioned technical features of the present invention and the technical features specifically described in the following (such as embodiments) can be combined with each other to form new or preferred technical solutions. Due to space limitations, we will not repeat them here.

detailed description

After extensive and in-depth research, the present inventor has developed a new synthesis method of perfluoropolyether. The method uses hexafluoropropylene oxide gas as a raw material, and then undergoes polymerization reaction and decarbonylation reaction to obtain the product perfluoropolyether. ether. The polymerization reaction adopts specific reaction conditions (such as selecting a specific catalyst and initiator, etc.), and the decarbonylation reaction also adopts specific reaction conditions (such as selecting a specific catalyst, etc.). The method has a high perfluoropolyether yield and the product has a higher average relative molecular weight, and the decarbonylation method is more convenient, safer and lower in cost. On this basis, the inventors have completed the present invention.

The perfluoropolyether can be used as lubricating oil base oil, and the invention provides a synthesis method of the perfluoropolyether.

The operations involved in the method of the present invention (such as anhydrous and oxygen-free operation, water removal operation of solvent, etc.) can be known in the art, and can also be performed according to the operation method provided by the present invention.

The method of the present invention is carried out in a pressure vessel, preferably in a stainless steel pressure vessel with a stirrer. Before carrying out the reaction, the container needs to pass a nitrogen leak test to ensure the airtightness of the container.

Preferably, the method of the present invention may comprise the following steps:

(1) Under the protection of nitrogen, add the first solvent, the first catalyst and the initiator in the pressure vessel; after vacuuming, stir at -30～-60°C (preferably -40～-50°C) Passing hexafluoropropylene oxide into the pressure vessel to carry out polymerization reaction for a period of time (such as 1-24 hours, preferably, 2-14 hours), thereby forming perfluoropolyetheryl fluoride;

(2) Add the perfluoropolyetheryl fluoride of step (1) into the pressure vessel, add the second solvent and the second catalyst under nitrogen atmosphere, and make , performing a decarbonylation reaction for a period of time (such as 1-24 hours, preferably, 2-8 hours), thereby forming a perfluoropolyether.

In another preferred example, said may include the following steps:

(i) Under the protection of nitrogen, add the first solvent, the first catalyst and the initiator to the pressure vessel, pump high-purity nitrogen several times (such as three times) through the double-row pipe to obtain an anhydrous and oxygen-free environment, and finally pump into In a vacuum state, put the pressure vessel into a low-temperature constant temperature tank, adjust the temperature to -30~-60°C (preferably -40~-50°C), feed hexafluoropropylene oxide gas, and decompress the gas, At a speed of 50-100mL/s, it passes through three impurity removal towers in series of neutral water absorbent-alkaline compound-adsorbent, and finally passes into the pressure vessel. After starting to feed gas, start stirring, carry out polymerization reaction for a period of time (as 1-24 hours, preferably, 2-14 hours), after the reaction is complete, the mixture of phases can be separated, and the lower liquid phase can be separated and collected to obtain the whole Fluoropolyether fluoride;

(ii) Add the obtained perfluoropolyetheryl fluoride into the pressure vessel that has replaced the air with high-purity nitrogen, add the second solvent and the second catalyst, and at the same time, ensure that the high-purity nitrogen carrier gas is heated at 150 to 300°C ( Preferably, the decarbonylation reaction is carried out at 200-250° C. for a period of time (such as 1-24 hours, preferably 2-8 hours). After the reaction is completed, the lower liquid phase is separated to obtain perfluoropolyether.

Preferably, the first solvent or the second solvent is dried, such as using 3A molecular sieves and calcium oxide to remove water; preferably, passing through 3A molecular sieves for a period of time (such as 12h) and calcium oxide distillation for a period of time ( Such as 3-6h); more preferably, the first solvent or the second solvent is a solvent with a water content≤10ppm.

Preferably, the first solvent or the second solvent is a ketone solvent (such as diisopropyl ketone, diisobutyl ketone), an ether solvent (such as ethylene glycol diethyl ether, diethylene glycol diethyl ether, tris glycol ether), or a combination thereof.

Preferably, the hexafluoropropylene oxide gas needs to undergo impurity removal. As mentioned above, the hexafluoropropylene oxide gas can be removed after decompression through three series of neutral water absorbing agent-alkaline compound-adsorbent tower. Wherein, the neutral water-absorbing agent may preferably be one or more of 3A molecular sieves, silica gel, and anhydrous calcium chloride; the alkaline compound may preferably be one of sodium hydroxide, sodium hydroxide, and calcium oxide. One or more; the adsorbent can preferably be activated alumina pellets. Preferably, the hydrogen fluoride content in the hexafluoropropylene oxide gas after impurity removal can be reduced from 0.15% to less than 0.06%, the water content can be reduced from about 600ppm to 3-5ppm, and the hexafluoroacetone content can be reduced to less than 0.1%. Industrial production standards. Compared with the use of hydride to remove impurities in the traditional process, the cost of the impurity removal method of the present invention is relatively low, and the production is safe, and the impurity removal materials used for the impurity removal can be recycled and reused, which is beneficial to industrial production.

Preferably, the first catalyst is a combination of alkali metal fluoride and alkali metal halide (non-fluorine). Preferably, the first catalyst is dried before use; more preferably, it is vacuum-dried at 140° C. for 4 hours.

Preferably, the initiator is one or more of perfluorovaleryl fluoride and heptafluorobutyryl fluoride.

Preferably, the second base catalyst is at least one or more of aluminum fluoride, aluminum chloride, aluminum bromide, cobalt fluoride and nickel chloride.

The polymerization reaction of the present invention does not use a diluent, which reduces the waste of raw materials, directly reacts and polymerizes in an aprotic solvent, reduces the process of diluent separation and recovery, simplifies the production process, and after the complete reaction, the solvent and the product are separated. The upper layer is the solvent, and the lower layer is the product. The two can be separated by liquid separation without complicated separation process. It has the characteristics of simple process, easy production, and low cost, which is conducive to industrial production.

Polymerization reaction of the present invention uses acyl fluoride compound as initiator, and the reaction mechanism of traditional production technology is, with the F in the solvent -act on the middle carbon atom of hexafluoropropylene oxide, form carbanion, then continue ^to act on hexafluoropropylene oxide Propane, finally de-F ^- to form perfluoropolyether acid fluoride; in the present invention, the acid fluoride compound is used as the initiation of the reaction, compared with the F in the solvent ^- acting on the acid fluoride group to form a carbanion and then continuously acting on the hexafluoro ring Propylene oxide speeds up the reaction process.

The decarbonylation reaction of the present invention uses aluminum fluoride and the like as catalysts for the decarbonylation reaction, and does not use the more dangerous antimony pentafluoride or expensive transition metal complexes in the traditional process. The process is simple, the production is safe, and it is beneficial to the industry. Production.

Preferably, the yield of the product obtained by the method of the present invention is ≥90%; more preferably, ≥92%; more preferably, ≥95%. The average molecular weight of the product is ≥1000; preferably ≥4000; more preferably ≥5000 or 1000-20000 or 4000-15000 or 5000-11000.

Compared with the prior art, the advantages of the present invention mainly include:

1. The present invention provides a new method for synthesizing perfluoropolyether. The method reacts purified hexafluoropropylene oxide with solvent, catalyst and initiator in an aprotic solvent at -30～-60°C The initial polymer of perfluoropolyether is obtained, and then a metal halide such as aluminum halide is used as a catalyst to decarbonylate the initial polymer to synthesize the final stable perfluoropolyether oil. The invention can make the yield of the perfluoropolyether reach more than 95%, has a relatively high average relative molecular weight, and can obtain the perfluoropolyether oil with high performances such as stability and oxidation resistance after being capped.

2. In the method of the present invention, do not add diluent, make technology relatively simple, cost is lower; And in the decarbonylation reaction, do not use precious transition metal halide salt as catalyzer, but use the halide salt of aluminum instead, cost is lower Low, easy to recycle, suitable for industrial production.

Below in conjunction with specific embodiment, further illustrate the present invention. It should be understood that these examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention. For the experimental methods without specific conditions indicated in the following examples, the conventional conditions or the conditions suggested by the manufacturer are usually followed. Percentages and parts are by weight unless otherwise indicated.

Example 1

Diisopropyl ketone and ethylene glycol diethyl ether were successively dewatered with 3A molecular sieves and calcium oxide was refluxed for 3 hours to remove water. Under nitrogen protection, 40 g of the first solvent (diisopropyl ketone), 5 g of the first catalyst (a composition of cesium fluoride and sodium chloride in a mass ratio of 1:0.1) and an initiator (perfluorinated valeryl fluoride) 2g, pump high-purity nitrogen through double-row pipes three times to obtain an anhydrous and oxygen-free environment, and finally evacuate into a vacuum state, put the pressure vessel into a low-temperature thermostat, and adjust the temperature to -60°C. 200g of hexafluoropropylene oxide gas, after decompression, passes through three series of neutral water-absorbing agent (anhydrous calcium chloride)-basic compound (calcium oxide)-adsorbent (alumina ball) at a speed of 100mL/s After the impurity removal tower, it is finally passed into the pressure vessel. Stir while feeding gas to carry out polymerization reaction. After 5 hours of reaction, the mixture can be separated into phases, and the lower liquid phase can be separated and collected to obtain perfluoropolyetheryl fluoride.

The perfluoropolyether acid fluoride obtained is added in the pressure vessel that has replaced air with high-purity nitrogen, and the second solvent (ethylene glycol diethyl ether) 30g and the second catalyst (aluminum chloride) 5g are added, while ensuring high Carrier gas of pure nitrogen was used for decarbonylation reaction at 150°C. After 3 hours of reaction, the lower liquid phase was separated to obtain perfluoropolyether. The yield was 95.2%, and the average molecular weight was 5753.

Example 2

Diisobutyl ketone and diethylene glycol diethyl ether were successively dewatered with 3A molecular sieve and refluxed with calcium oxide for 3 hours to dewater. The first catalyst (composition of rubidium fluoride and sodium bromide in a mass ratio of 1:0.05) was vacuum-dried at 140° C. for 4 hours. Under the protection of nitrogen, 40 g of the first solvent (diisobutyl ketone), 8 g of the first catalyst (the composition of rubidium fluoride and sodium bromide in a mass ratio of 1:0.05) and initiator (perfluorinated valeryl fluoride) 1.5g, pump high-purity nitrogen through double-row pipes three times to obtain an anhydrous and oxygen-free environment, and finally evacuate into a vacuum state, put the pressure vessel into a low-temperature thermostat, and adjust the temperature to -50°C. 200g of hexafluoropropylene oxide gas, after decompression, passes through three impurity removal towers in series of neutral water absorbent (silica gel)-alkaline compound (potassium hydroxide)-adsorbent (alumina pellets) at a speed of 80mL/s After that, it is finally passed into the pressure vessel. Stir while feeding gas to carry out polymerization reaction. After 6 hours of reaction, the mixture can be separated into phases, and the lower liquid phase can be separated and collected to obtain perfluoropolyether acid fluoride.

The perfluoropolyetheryl fluoride obtained is added into the pressure vessel that has been replaced with high-purity nitrogen, and the second solvent (diethylene glycol diethyl ether) 30g and the second catalyst (aluminum bromide) 5g are added, and at the same time, ensure Carrier gas of high-purity nitrogen is used for decarbonylation reaction at 200°C. After 4 hours of reaction, the lower liquid phase is separated to obtain perfluoropolyether. The yield was 96.4%, and the average molecular weight was 8726.

Example 3

Diisobutyl ketone and triethylene glycol ethyl ether were successively dewatered with 3A molecular sieves and calcium oxide was refluxed for 6 hours to remove water. The first catalyst (composition of potassium fluoride and potassium bromide in a mass ratio of 1:0.02) was vacuum-dried at 140° C. for 4 hours. Under nitrogen protection, add the first solvent (diisobutyl ketone) 40g, the first catalyst (the composition of potassium fluoride and potassium bromide in mass ratio 1:0.02) 10g and initiator (heptafluoro Butyryl fluoride) 2g, pump high-purity nitrogen three times through double-row pipes to obtain an anhydrous and oxygen-free environment, and finally evacuate into a vacuum state, put the pressure vessel into a low-temperature thermostat, and adjust the temperature to -40 °C. 200g of hexafluoropropylene oxide gas, after decompression, passes through three impurity removal towers in series of neutral water absorbent (silica gel)-alkaline compound (potassium hydroxide)-adsorbent (alumina ball) at a speed of 50mL/s After that, it is finally passed into the pressure vessel. Stir while feeding gas to carry out polymerization reaction. After 12 hours of reaction, the mixture can be separated into phases, and the lower liquid phase can be separated and collected to obtain perfluoropolyether acid fluoride.

The perfluoropolyetheracyl fluoride obtained is added in the pressure vessel that has replaced the air with high-purity nitrogen, and the second solvent (triethylene glycol ether) 30g and the second catalyst (nickel chloride) 5g are added, while ensuring high Carrier gas of pure nitrogen is used for decarbonylation reaction at 300°C. After 6 hours of reaction, the lower liquid phase is separated to obtain perfluoropolyether. The yield was 97.4%, and the average molecular weight was 9245.

Example 4

Diisobutyl ketone and ethylene glycol diethyl ether were successively dewatered with 3A molecular sieves and calcium oxide was refluxed for 6 hours to remove water. Under the protection of nitrogen, 40 g of the first solvent (diisobutyl ketone, ethylene glycol diethyl ether with a mass ratio of 1:1), 40 g of the first catalyst (rubidium fluoride, potassium fluoride, potassium iodide) were added to the pressure vessel. According to the mass ratio of 0.5:0.5:0.1 composition) 10g and the initiator (perfluorovaleryl fluoride, heptafluorobutyryl fluoride mass ratio of 2:1 composition) 2.0g, pump high-purity nitrogen through double-row pipes Three times to obtain an anhydrous and oxygen-free environment, and finally evacuate into a vacuum state, put the pressure vessel into a low-temperature thermostat, and adjust the temperature to -60°C. 200g of hexafluoropropylene oxide gas, after decompression, passes through a neutral water-absorbing agent (a composition of anhydrous calcium chloride and 3A molecular sieve with a mass ratio of 1:1)-basic compound (calcium oxide, hydrogen Potassium oxide mass ratio of 1:1 composition) - adsorbent (alumina pellets) connected in series with three impurity removal towers, and finally pass into the pressure vessel. Stir while feeding gas to carry out polymerization reaction. After 12 hours of reaction, the mixture can be separated into phases, and the lower liquid phase can be separated and collected to obtain perfluoropolyether acid fluoride.

Add the obtained perfluoropolyetheryl fluoride into a pressure vessel that has replaced the air with high-purity nitrogen, and add 30 g of the second solvent (diisobutyl ketone, ethylene glycol diethyl ether with a mass ratio of 1:1) With 5g of the second catalyst (a composition of aluminum chloride and nickel chloride with a mass ratio of 1:1), at the same time, high-purity nitrogen carrier gas was ensured, and the decarbonylation reaction was carried out at 200°C. After 4 hours of reaction, the lower layer was separated liquid phase to obtain perfluoropolyether. The yield was 94.8%, and the average molecular weight was 10102.

Example 5

Diisobutyl ketone and triethylene glycol ethyl ether were successively dewatered with 3A molecular sieves and calcium oxide was refluxed for 6 hours to remove water. Under nitrogen protection, add 40 g of the first solvent (diisobutyl ketone, triethylene glycol ethyl ether mass ratio of 1:1 composition), the first catalyst (rubidium fluoride, potassium fluoride, bromine Sodium chloride, potassium chloride according to mass ratio 0.5:0.5:0.05:0.05 composition) 10g and initiator (perfluorovaleryl fluoride, heptafluorobutyryl fluoride mass ratio is the composition of 1:1 composition) 1.5g, through The high-purity nitrogen gas was pumped through the double-row pipe for three times to obtain an anhydrous and oxygen-free environment. Finally, it was pumped into a vacuum state, and the pressure vessel was placed in a low-temperature constant temperature tank, and the temperature was adjusted to -60°C. 200g of hexafluoropropylene oxide gas, after decompression, passes through a neutral water-absorbing agent (a composition of anhydrous calcium chloride and silica gel with a mass ratio of 1:1)-basic compound (calcium oxide, hydroxide The composition with a mass ratio of sodium of 1:1)-adsorbent (alumina pellets) connects three impurity removal towers in series, and finally passes into the pressure vessel. Stir while feeding gas to carry out polymerization reaction. After 12 hours of reaction, the mixture can be separated into phases, and the lower liquid phase can be separated and collected to obtain perfluoropolyether acid fluoride.

Add the obtained perfluoropolyetheryl fluoride into a pressure vessel that has replaced the air with high-purity nitrogen, and add 30 g of the second solvent (diisobutyl ketone, triethylene glycol ether with a mass ratio of 2:1) and the second catalyst (cobalt fluoride, nickel chloride mass ratio of 2:1 composition) 5g, at the same time, ensure high-purity nitrogen carrier gas, decarbonylation reaction at 250 ° C, after 4 hours of reaction, separate the lower layer liquid phase to obtain perfluoropolyether. The yield was 97.2%, and the average molecular weight was 12324.

All documents mentioned in this application are incorporated by reference in this application as if each were individually incorporated by reference. In addition, it should be understood that after reading the above teaching content of the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of the present application.

Claims (10)

1. a synthetic method of perfluoropolyether, is characterized in that, comprises steps: (1) Synthesis of perfluoropolyetheryl fluoride: At -30 to -60°C, in a pressure vessel, the first solvent, the first catalyst, the initiator and hexafluoropropylene oxide are polymerized to form perfluoropolyetheryl fluoride; (2) Synthesis of perfluoropolyether: In a pressure vessel, the perfluoropolyether acid fluoride, the second solvent and the second catalyst in the step (1) are subjected to a decarbonylation reaction at 150-300° C. to form a perfluoropolyether. 2. synthetic method as claimed in claim 1, is characterized in that, Step (1) is: under the protection of nitrogen, add the first solvent, the first catalyst and the initiator into the pressure vessel; Polyfluoropropylene oxide is polymerized to form perfluoropolyetheryl fluoride; and/or Step (2) is: add the perfluoropolyetheryl fluoride of step (1) into the pressure vessel, add the second solvent and the second catalyst under nitrogen atmosphere, and carry out the decarbonylation reaction at 150°C to 300°C, Thus forming a perfluoropolyether. 3. the synthetic method as claimed in claim 1 or 2, is characterized in that, The first solvent or the second solvent is dried; and/or The first solvent or the second solvent is an aprotic polar solvent. 4. The synthesis method according to claim 1 or 2, characterized in that, before the hexafluoropropylene oxide is passed into the pressure vessel, it is removed by neutral water absorbing agent-basic compound-adsorbent. 5. synthetic method as claimed in claim 1 or 2, is characterized in that, described first catalyst is the composition of alkali metal fluoride and alkali metal halide (non-fluorine); Wherein, described alkali metal fluoride is Cesium fluoride, rubidium fluoride, potassium fluoride, or a combination thereof; the alkali metal halide (non-fluorine) is sodium chloride, sodium bromide, potassium chloride, potassium bromide, potassium iodide, or a combination thereof. 6. The synthesis method according to claim 1, characterized in that the mass ratio of the first catalyst to hexafluoropropylene oxide is 1:10-100. 7. The synthesis method according to claim 5, characterized in that, in the first catalyst, the mass ratio of the alkali metal fluoride to the alkali metal halide (non-fluorine) is 1:0.005-0.2. 8. The synthesis method according to claim 1, wherein the initiator is an acyl fluoride initiator selected from the group consisting of perfluorovaleryl fluoride, heptafluorobutyryl fluoride, or a combination thereof. 9. The synthesis method according to claim 1, characterized in that the mass ratio of the initiator to hexafluoropropylene oxide is 1:50-200. 10. The synthesis method according to claim 1, wherein the second catalyst is aluminum chloride, aluminum bromide, cobalt fluoride, nickel chloride, or a combination thereof.