Synthetic method and application of hexafluoropropylene oxide

Abstract

The invention provides a synthetic method of hexafluoropropylene oxide and application thereof, and relates to the technical field of fluorine chemical industry, and the synthetic method comprises the following steps: under supercritical conditions, hexafluoropropylene and oxygen are subjected to complete mixed flow induction to generate reaction free radicals, then the reaction free radicals are subjected to a reaction through a microchannel reactor, and the hexafluoropropylene oxide is continuously synthesized. The invention solves the technical problems of low conversion rate, low selectivity and rearrangement of hexafluoropropylene oxide into hexafluoroacetone during synthesis of hexafluoropropylene oxide in the prior art, and achieves the technical effects of high conversion rate, high selectivity and green continuous synthesis of hexafluoropropylene oxide.

Description

Technical Field

[0001] The invention relates to the technical field of fluorine chemical industry, and in particular to a synthesis method of hexafluoropropylene oxide and application thereof. Background Art

[0002] Hexafluoropropylene oxide (HFPO, Hexafluoropropylene oxide, CAS: 428-59-1) is an important fluorine-containing intermediate that can be used to synthesize high-end fluorine-containing functional materials such as fluororubber, fluoroplastics, perfluoroether oil, fluorine-containing surfactants and advanced cleaning agents. At present, the synthesis methods of HFPO include nucleophilic oxidation (hydrogen peroxide oxidation and hypochlorite oxidation), electrochemical oxidation (direct electrolysis and indirect electrolysis), carbonate oxidation and molecular oxygen oxidation (gas phase oxidation, liquid phase oxidation and photochemical reaction). Molecular oxygen liquid phase oxidation (US3536733, CN1634902) refers to a method in which hexafluoropropylene (HFP) reacts with oxygen in a specific solvent to produce HFPO at a certain temperature and pressure. The molecular oxygen liquid phase oxidation method has the advantages of high conversion rate, and the use of solvents can make the reaction stable and have a high safety factor, which is favored by major fluorine chemical companies at home and abroad.

[0003] Prior art CN101157669 discloses a process for continuously preparing hexafluoropropylene oxide. In a fully mixed flow reactor, hexafluoropropylene and oxygen are mixed and then introduced into the reactor. This method can realize continuous operation, but heat dissipation is difficult and there is a risk of oxygen explosion; the HFP conversion rate of the oxidation reaction is 85% to 95%, and the selectivity of HFPO is 65% to 68%. Prior art CN104672177 discloses a method for continuously oxidizing hexafluoropropylene oxide in a microchannel reactor. The reaction raw materials directly enter the microchannel reactor after passing through a mixer. Although the conversion rate and selectivity are greatly improved, the reaction is carried out under relatively high temperature conditions, which easily leads to the decomposition and rearrangement of HFPO. The synthesis of HFPO by HFP oxidation is a free radical induced reaction. The induction of free radicals affects the conversion rate of HFP and the selectivity of hexafluoropropylene oxide. If the induction time is too short, the conversion rate of HFP is low, and if the induction time is too long, more by-products are easily produced; in addition, HFPO is easily catalyzed to generate hexafluoroacetone (HFA), which affects the yield of HFPO. US321515 shows that in the presence of Lewis acid, HFPO is easily catalytically rearranged to form HFA; in the presence of Lewis base, HFPO is easily catalytically rearranged to form pentafluoropropionyl fluoride; since the reaction container is mostly made of carbon steel or stainless steel, it can act as a Lewis acid, and the reaction conditions are high temperature and high pressure, so HFPO is easily rearranged to form HFA during the oxidation process, which leads to a decrease in the yield of HFPO.

[0004] Prior art US3600409 and CN1995169 disclose methods of adding neutral aromatic compounds (such as diphenyl ether and benzene) to prevent HFPO rearrangement. However, aromatic compounds are often highly toxic, and intermittent reaction of aromatic compounds is prone to loss and difficult to recycle.

[0005] In view of this, the present invention is proposed. Summary of the invention

[0006] One of the purposes of the present invention is to provide a method for synthesizing hexafluoropropylene oxide, which can synthesize hexafluoropropylene oxide with high conversion rate and high selectivity.

[0007] The second object of the present invention is to provide an application of a method for synthesizing hexafluoropropylene oxide, which is beneficial to the green and continuous synthesis of hexafluoropropylene oxide.

[0008] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted:

[0009] In a first aspect, a method for synthesizing hexafluoropropylene oxide comprises the following steps:

[0010] Under supercritical conditions, hexafluoropropylene and oxygen are firstly induced to generate reaction free radicals through full mixed flow, and then reacted through a microchannel reactor to obtain hexafluoropropylene oxide.

[0011] Furthermore, the synthesis method comprises the following steps:

[0012] A raw material solution containing hexafluoropropylene and oxygen is first induced to generate reaction free radicals under full mixed flow supercritical conditions in a tank reactor, and then introduced into a microchannel reactor for reaction under supercritical conditions to obtain hexafluoropropylene oxide;

[0013] Preferably, the reaction pressure under the supercritical condition is 5 MPa to 8 MPa, and the reaction temperature is 100° C. to 150° C.

[0014] Further, the solvent of the raw material solution includes a fluorocarbon solvent;

[0015] The raw material solution also contains an inhibitor.

[0016] Furthermore, the fluorocarbon solvent includes environmentally friendly hydrofluorocarbon C n H a F 2n+2-a and perfluoroether C n F b O c At least one of;

[0017] wherein n≥3, and n, a, b and c are all independently integers.

[0018] Furthermore, the mass ratio of the fluorocarbon solvent to hexafluoropropylene is ≥5;

[0019] The molar ratio of hexafluoropropylene to oxygen is ≥2.

[0020] Further, the inhibitor includes cyclohexyl ether;

[0021] The cyclohexyl ether includes at least one of cyclohexyl methyl ether and cyclohexyl ethyl ether;

[0022] The inhibitor is added in an amount of 50 ppm to 500 ppm relative to the fluorocarbon solvent.

[0023] Furthermore, the residence time of the raw material solution in the autoclave reactor is 20s to 1min, and the residence time in the microchannel reactor is 1min to 30min.

[0024] Furthermore, the pressure of the autoclave reactor is at least 0.2 MPa higher than that of the microchannel reactor.

[0025] Furthermore, the fluorocarbon solvent and inhibitor after the reaction in the microchannel reactor are cooled and filtered and then recovered for oxidation synthesis of hexafluoropropylene oxide.

[0026] In a second aspect, a method for continuously synthesizing hexafluoropropylene oxide is provided.

[0027] Compared with the prior art, the present invention has at least the following beneficial effects:

[0028] The method for synthesizing hexafluoropropylene oxide provided by the present invention has the advantages that before the raw materials react through a microchannel reactor, full mixing is firstly performed to induce the generation of reaction free radicals, the reaction conditions are controllable, not only the conversion rate of the raw materials can be improved and the reaction time can be shortened, but also the risks of runaway temperature and oxygen explosion in the oxidation reaction can be avoided, the method is safe and reliable, and easy to be industrially scaled up; in short, under supercritical conditions, full mixing is firstly performed to induce the generation of reaction free radicals, and then the reaction is carried out through a microchannel reactor, hexafluoropropylene (HFP) is oxidized and synthesized to obtain hexafluoropropylene oxide (HFPO), and with the coordinated cooperation of various steps and process parameters thereof, the technical effect of synthesizing hexafluoropropylene oxide with high conversion rate and high selectivity is achieved.

[0029] The application of the synthesis method of hexafluoropropylene oxide provided by the invention is conducive to the green and continuous synthesis of hexafluoropropylene oxide. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0031] Figure 1 A schematic diagram of a synthesis reaction of hexafluoropropylene oxide provided in one embodiment of the present invention;

[0032] Figure 2 A process flow chart of the synthesis of hexafluoropropylene oxide provided in one embodiment of the present invention.

[0033] Icons: 1-fluorocarbon solvent storage tank; 2-hexafluoropropylene storage tank; 3-oxygen storage tank; 4-fluorocarbon solvent delivery pump; 5-hexafluoropropylene delivery pump; 6-oxygen delivery pump; 7-kettle reactor; 8-microchannel reactor; 9-first heat exchanger; 10-second heat exchanger; 11-filter; 12-distillation tower. DETAILED DESCRIPTION

[0034] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than 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.

[0035] According to a first aspect of the present invention, there is provided a method for synthesizing hexafluoropropylene oxide, comprising the following steps:

[0036] Under supercritical conditions, hexafluoropropylene and oxygen are firstly induced to generate reaction free radicals through full mixed flow, and then reacted through a microchannel reactor to obtain hexafluoropropylene oxide.

[0037] The method for synthesizing hexafluoropropylene oxide provided by the present invention has the advantages that before the raw materials react through a microchannel reactor, full mixing is firstly performed to induce the generation of reaction free radicals, the reaction conditions are controllable, not only the conversion rate of the raw materials can be improved and the reaction time can be shortened, but also the risks of runaway temperature and oxygen explosion in the oxidation reaction can be avoided, the method is safe and reliable, and easy to be industrially scaled up; in short, under supercritical conditions, full mixing is firstly performed to induce the generation of reaction free radicals, and then the reaction is carried out through a microchannel reactor, hexafluoropropylene (HFP) is oxidized and synthesized to obtain hexafluoropropylene oxide (HFPO), and with the coordinated cooperation of various steps and process parameters thereof, the technical effect of synthesizing hexafluoropropylene oxide with high conversion rate and high selectivity is achieved.

[0038] In a preferred embodiment, the synthesis method of the present invention comprises the following steps:

[0039] The raw material solution contains hexafluoropropylene and oxygen, which are first induced to generate reaction free radicals under full mixed flow supercritical conditions in a kettle reactor, and then introduced into a microchannel reactor for reaction under supercritical conditions to obtain hexafluoropropylene oxide. The reaction diagram is shown in Figure 1 .

[0040] It should be noted that the microchannel reactor has a large fluid specific surface area, continuous and controllable operation, can achieve rapid heat exchange, avoid temperature runaway, has a stable reaction, is easy to industrialize, and can effectively inhibit the side reaction of oxidation, which is beneficial to improving the selectivity of hexafluoropropylene oxide; in addition, in order to prevent hexafluoropropylene oxide from rearranging in the microchannel reactor, the material of the microchannel reactor can be an inert material, such as silicon carbide, copper, silver, gold or barite, but not limited to this.

[0041] In the present invention, the raw material solution reacts in a supercritical state in the reactor. The reaction pressure in the supercritical state can be, for example, 5MPa, 6MPa, 7MPa, 8MPa, but is not limited thereto; the reaction temperature in the supercritical state can be, for example, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, but is not limited thereto.

[0042] In a preferred embodiment, the solvent of the raw material solution includes but is not limited to a fluorocarbon solvent;

[0043] At the same time, the raw material solution may also contain an inhibitor.

[0044] It should be noted that the critical pressures of hexafluoropropylene and oxygen in the raw material solution are 2.9MPa and 5MPa, respectively, and the critical temperatures are 95°C and -119°C, respectively; at the same time, the fluorocarbon solvent in the raw material solution also needs to reach a supercritical state. Hexafluoropropylene, oxygen and fluorocarbon solvents have excellent solubility and mass transfer coefficients in the supercritical state, which is conducive to achieving an ultra-high conversion rate of hexafluoropropylene.

[0045] In the present invention, fluorocarbon solvent and hexafluoropropylene can be preheated by heat exchange of oxidation products and then fed from the top of the autoclave reactor, and oxygen can be preheated by heat exchange of fluorocarbon solvent and then fed from the bottom of the autoclave reactor. This cleverly utilizes the heat of heat exchange in the process flow, making full use of the heat and greatly reducing energy consumption.

[0046] In a preferred embodiment, the fluorocarbon solvent is not limited to environmentally friendly hydrofluorocarbon C n H a F 2n+2-a and perfluoroether C n F b O cAt least one of the following (wherein n≥3, n, a, b and c are all independently integers) has good solubility in hexafluoropropylene.

[0047] In a preferred embodiment, the mass ratio of the fluorocarbon solvent to hexafluoropropylene (HFP) may be ≥5, for example, 5, 6, 7, 8, 9, 10, but not limited thereto; at the same time, the mass ratio of hexafluoropropylene (HFP) to oxygen (O 2 ) can have a molar ratio of ≥2, for example, 2, 3, 4, 5, but is not limited thereto.

[0048] In the present invention, in order to prevent hexafluoropropylene oxide from rearranging and deteriorating during the reaction, a neutral reactor combined with a neutral inhibitor can be used, and after the reaction is completed, the inhibitor and the fluorocarbon solvent can be recovered and reused at the same time, which can effectively and safely inhibit the hexafluoropropylene oxide from rearranging and deteriorating into hexafluoroacetone (HFA), which is beneficial to further improve the yield of hexafluoropropylene oxide.

[0049] In a preferred embodiment, the inhibitor can be selected as a neutral, low-toxic cyclohexyl ether that does not participate in the oxidation reaction, for example, at least one of cyclohexyl methyl ether and cyclohexyl ethyl ether. The inhibitor can occupy the empty orbital of the Lewis acid, thereby effectively preventing hexafluoropropylene oxide from rearranging and deteriorating into hexafluoroacetone.

[0050] In a preferred embodiment, the amount of the inhibitor added to the fluorocarbon solvent can be 50ppm to 500ppm, for example, 50ppm, 100ppm, 150ppm, 200ppm, 250ppm, 300ppm, 350ppm, 400ppm, 450ppm, 500ppm, but not limited to this; the inhibitor can be added to the fluorocarbon solvent in advance, and the amount added should not be too much, otherwise it will affect the rate of the oxidation reaction.

[0051] In a preferred embodiment, the residence time of the raw material solution in the autoclave reactor can be 20s to 1min, and its typical but non-limiting residence time is, for example, 20s, 30s, 40s, 50s, and 1min. The residence time should not be too long, otherwise it may cause the formation of by-products; the residence time of the raw material solution in the microchannel reactor can be 1min to 30min, and its typical but non-limiting residence time is, for example, 1min, 5min, 10min, 15min, 20min, 25min, and 30min. The residence time should not be too short, otherwise it will lead to insufficient conversion of hexafluoropropylene, and the residence time should not be too long, otherwise it may cause the formation of by-products such as carbonyl fluoride, trifluoroacetyl fluoride and high-boiling polymers thereof.

[0052] In the present invention, the pressure of the autoclave reactor may be higher than that of the microchannel reactor. The pressure of the autoclave reactor is at least 0.2 MPa higher than that of the microchannel reactor, which is more conducive to ensuring continuous feeding of the autoclave reactor to the microchannel reactor.

[0053] In a preferred embodiment, the fluorocarbon solvent and inhibitor after the reaction in the microchannel reactor can be recovered for oxidation synthesis of hexafluoropropylene oxide after cooling and filtering.

[0054] A typical synthesis method of hexafluoropropylene oxide comprises the following steps:

[0055] (1) using oxygen, hexafluoropropylene and a fluorocarbon solvent containing an inhibitor as raw materials to react in a tank reactor, with a stirring speed of 50 r / min to 200 r / min, a residence time of 20 s to 1 min, a reaction system in a supercritical state, a reaction pressure of 5 MPa to 8 MPa, and a reaction temperature of 100° C. to 150° C., thereby generating reaction free radicals under fully mixed flow supercritical conditions in a neutral tank reactor;

[0056] The fluorocarbon solvent, hexafluoropropylene and oxygen are respectively fed into the autoclave reactor by means of a delivery pump to increase pressure; the feeding sequence is to first feed the fluorocarbon solvent, and then feed the hexafluoropropylene into the autoclave reactor;

[0057] Specifically, the fluorocarbon solvent and hexafluoropropylene are firstly heat exchanged through the tube layer of the first heat exchanger and then fed from the top of the tank reactor, and the oxygen is then heat exchanged through the tube layer of the second heat exchanger and then fed from the bottom of the tank reactor, forming a countercurrent reaction;

[0058] It should be noted that if hexafluoropropylene and oxygen are added as the first materials, it is very likely to cause oxygen explosion;

[0059] The mass ratio of fluorocarbon solvent to hexafluoropropylene is ≥5;

[0060] The feed molar ratio of hexafluoropropylene to oxygen is ≥2, which is more conducive to improving the conversion rate of hexafluoropropylene;

[0061] The inhibitor may be a cyclohexyl ether, including at least one of cyclohexyl methyl ether and cyclohexyl ethyl ether;

[0062] The amount of inhibitor added relative to the fluorocarbon solvent is 50ppm to 500ppm;

[0063] (2) The reaction free radicals generated by the full mixed flow in step (1) are connected in series to the microchannel reactor to continue the oxidation reaction, with a residence time of 1 min to 30 min, the reaction system is in a supercritical state, the reaction pressure is 5 MPa to 8 MPa, and the reaction temperature is 100° C. to 150° C. to obtain hexafluoropropylene oxide;

[0064] The crude product after the oxidation reaction enters the distillation tower for separation after heat exchange in the shell layer of the first heat exchanger. The heat after the heat exchange can be used to preheat the fluorocarbon solvent and hexafluoropropylene, so the heat can be fully utilized;

[0065] (3) The fluorocarbon solvent and inhibitor after the oxidation reaction in the microchannel reactor in step (2) are cooled and filtered and then recovered for oxidation synthesis of hexafluoropropylene oxide;

[0066] Since fluorocarbon solvents and inhibitors do not participate in the oxidation reaction, they can be separated by a distillation tower after the reaction, and then returned to the oxidation reaction after passing through a second heat exchanger and a filter, so that the fluorocarbon solvents and inhibitors can be recycled in a green way.

[0067] In summary, the present invention first induces the generation of reaction free radicals under fully mixed flow supercritical conditions (neutral conditions) in a kettle reactor, and then connects the reactor in series to a microchannel reactor for reaction, thereby forming a "kettle-microchannel" continuous supercritical synthesis process of hexafluoropropylene oxide. With the coordinated cooperation of each step and its process parameters, the process has the advantages of short reaction induction period, mild conditions, high conversion rate, high selectivity, safety and reliability, and easy industrial scale-up.

[0068] According to a second aspect of the present invention, there is provided an application of any one of the above-mentioned synthesis methods in the continuous synthesis of hexafluoropropylene oxide.

[0069] The application of the synthesis method of hexafluoropropylene oxide provided by the invention is conducive to the green and continuous synthesis of hexafluoropropylene oxide.

[0070] The present invention is further described below by way of examples. Unless otherwise specified, the materials in the examples are prepared according to existing methods or directly purchased from the market.

[0071] Examples 1-9

[0072] Example 1-9 provides a method for synthesizing hexafluoropropylene oxide, which adopts a "kettle-microchannel" series process. The process flow chart is shown in Figure 2 , including the following steps:

[0073] The fluorocarbon solvent storage tank 1 first adds the inhibitor into the fluorocarbon solvent, and the fluorocarbon solvent storage tank 1 and the hexafluoropropylene storage tank 2 respectively feed the fluorocarbon solvent and hexafluoropropylene (HFP) from the top of the kettle to the kettle reactor 7 through the tube layer of the first heat exchanger 9 through the fluorocarbon solvent delivery pump 4 and the hexafluoropropylene delivery pump 5; wherein the inhibitor is cyclohexyl ether, and the fluorocarbon solvent is an environmentally friendly hydrofluorocarbon;

[0074] The oxygen storage tank 3 delivers oxygen (O 2 ) is fed from the bottom of the kettle into the kettle reactor 7 through the tube layer of the second heat exchanger 10;

[0075] Under supercritical conditions, the raw material solution of hexafluoropropylene and oxygen is first induced to generate reaction free radicals by full mixing flow in the autoclave reactor 7, and then enters the silicon carbide microchannel reactor 8 to continue the reaction to obtain hexafluoropropylene oxide (HFPO); wherein the temperature and pressure of the reactor are controlled by the heat exchange medium to ensure that the reaction fluid is in a supercritical state;

[0076] The oxidation product after the reaction in the microchannel reactor 8 is cooled by the shell layer of the first heat exchanger 9 and then enters the distillation tower 12 for separation. The main component of the distillation tower 12 discharged at the top of the tower is O 2 、COF 2 and CF 3 COF, reflux HFPO and a small amount of unreacted HFP, the main components of the bottom are fluorocarbon solvents and inhibitors;

[0077] The fluorocarbon solvent and inhibitor in the bottom of the distillation tower 12 are cooled by the shell of the second heat exchanger 10 and filtered by the filter 11 before being recycled to the fluorocarbon solvent storage tank 1 .

[0078] The amount of inhibitor added relative to the fluorocarbon solvent, the mass ratio of the fluorocarbon solvent to HFP, and the mass ratio of HFP to O in Examples 1-9 2 The molar ratio of , the reaction temperature and pressure of the reactor, the residence time of the autoclave reactor (R1), the residence time of the microchannel reactor (R2), the HFP conversion rate, the hexafluoroacetone (HFA) content and the HFPO selectivity are shown in Table 1 respectively.

[0079] Table 1 HFP conversion, HFA content and HFPO selectivity under different reaction conditions in Examples 1-9

[0080]

[0081] Comparative Example 1

[0082] This comparative example provides a method for synthesizing hexafluoropropylene oxide, which differs from Example 8 only in that the raw material solution of hexafluoropropylene and oxygen is not subjected to full mixing induction in the autoclave reactor 7 to generate reactive free radicals, but directly enters the microchannel reactor 8 for oxidation reaction;

[0083] The remaining steps and process parameters are the same as those in Example 8.

[0084] Compared with Example 8, the disadvantage of this comparative example is that there are fewer reaction free radicals and the conversion rate of HFP is lower.

[0085] In this comparative example, the HFP conversion rate was 54% and the HFPO selectivity was 48%.

[0086] Comparative Example 2

[0087] This comparative example provides a method for synthesizing hexafluoropropylene oxide, which differs from Example 8 only in that the reaction temperature is 90°C;

[0088] The remaining steps and process parameters are the same as those in Example 8.

[0089] Compared with Example 8, the defects of this comparative example are that the reaction temperature is low, the reaction raw materials have not reached a critical state, and the solubility performance is slightly low.

[0090] In this comparative example, the HFP conversion rate was 85% and the HFPO selectivity was 84%.

[0091] Comparative Example 3

[0092] This comparative example provides a method for synthesizing hexafluoropropylene oxide, which differs from Example 8 only in that the reaction temperature is 160°C;

[0093] The remaining steps and process parameters are the same as those in Example 8.

[0094] Compared with Example 8, the drawback of this comparative example is that the reaction temperature is relatively high, which may cause HFPO to decompose into trifluoroacetyl fluoride and difluorocarbene, or carbonyl fluoride and fluoro(trifluoromethyl)carbene.

[0095] In this comparative example, the HFP conversion rate was 98% and the HFPO selectivity was 67%.

[0096] It can be seen that the synthesis method of the present invention adopts the "agitator-microchannel" series process, and the raw materials are first fully mixed in advance to induce the generation of reaction free radicals, and then reacted through the microchannel reactor. Not only the reaction conditions are controllable, but also the conversion rate of hexafluoropropylene is improved, the reaction time is shortened, and the risk of high temperature and oxygen explosion in the oxidation reaction is avoided. It is safe, reliable, and easy to scale up industrial production.

[0097] 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 replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for synthesizing hexafluoropropylene oxide, characterized in that: The following steps are involved: Under supercritical conditions, hexafluoropropylene and oxygen are firstly induced to generate reaction free radicals through full mixed flow, and then reacted through a microchannel reactor to obtain hexafluoropropylene oxide.

2. The synthesis method according to claim 1, characterized in that The synthesis method comprises the following steps: A raw material solution containing hexafluoropropylene and oxygen is first induced to generate reaction free radicals under full mixed flow supercritical conditions in a tank reactor, and then introduced into a microchannel reactor for reaction under supercritical conditions to obtain hexafluoropropylene oxide; Preferably, the reaction pressure under the supercritical condition is 5 MPa to 8 MPa, and the reaction temperature is 100° C. to 150° C.

3. The synthesis method according to claim 2, characterized in that The solvent of the raw material solution includes a fluorocarbon solvent; The raw material solution also contains an inhibitor.

4. The synthesis method according to claim 3, characterized in that The fluorocarbon solvent includes environmentally friendly hydrofluorocarbon C n H a F 2n+2-a and perfluoroether C n F b O c At least one of; wherein n≥3, and n, a, b and c are all independently integers.

5. The synthesis method according to claim 3, characterized in that The mass ratio of the fluorocarbon solvent to hexafluoropropylene is ≥5; The molar ratio of hexafluoropropylene to oxygen is ≥2.

6. The synthesis method according to claim 3, characterized in that The inhibitor includes cyclohexyl ether; The cyclohexyl ether includes at least one of cyclohexyl methyl ether and cyclohexyl ethyl ether; The inhibitor is added in an amount of 50 ppm to 500 ppm relative to the fluorocarbon solvent.

7. The synthesis method according to claim 2, characterized in that The residence time of the raw material solution in the autoclave reactor is 20s to 1min, and the residence time in the microchannel reactor is 1min to 30min.

8. The synthesis method according to claim 7, characterized in that The pressure of the autoclave reactor is at least 0.2 MPa higher than that of the microchannel reactor.

9. The synthesis method according to claim 3, characterized in that: The fluorocarbon solvent and inhibitor after the reaction in the microchannel reactor are cooled and filtered and then recycled for oxidation synthesis of hexafluoropropylene oxide.

10. Use of the synthesis method according to any one of claims 1 to 9 in the continuous synthesis of hexafluoropropylene oxide.

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