Continuous Synthesis Method of Carbonyl Fluoride

Abstract

This invention belongs to the field of fluorochemical technology, specifically relating to a continuous synthesis method for carbonyl fluoride. The method is carried out in a reaction tube, which is divided into a preheating section, a reaction initiation section, a continuous reaction section, and a reaction quenching section. A catalyst is loaded into the reaction initiation and continuous reaction sections. A mixture of fluorinated organic compounds and oxygen is introduced from the inlet end of the reaction tube, flowing sequentially through each section. Product gas is collected at the outlet end of the reaction tube. A portion of the collected product gas is refluxed and reintroduced into the reaction tube. The remaining product gas is sent to a distillation column for separation to obtain the carbonyl fluoride product. During the reaction, a segmented independent temperature control device can promptly remove excess heat, preventing excessive oxidation and the formation of byproducts. Simultaneously, the product gas reflux dilutes the reactants to avoid excessively high local concentrations and overheating, and allows the reactants to enter and exit the reaction tube multiple times and rapidly, effectively resulting in multiple reactions and a higher conversion rate.

Description

Technical Field

[0001] This invention belongs to the field of fluorochemical technology, specifically relating to a continuous synthesis method for carbonyl fluoride. Background Technology

[0002] Carbonyl fluoride, as an important fluorine-containing compound, has broad application prospects in chemical, electronic, and semiconductor fields. For example, in semiconductor manufacturing, carbonyl fluoride can be used in etching processes, and its high selectivity and etching rate can meet the requirements of high-precision processing. In the chemical industry, carbonyl fluoride can serve as an intermediate in organic synthesis, participating in various chemical reactions. Therefore, developing an efficient, economical, and easily industrialized method for synthesizing carbonyl fluoride is of significant practical importance. However, traditional methods for synthesizing carbonyl fluoride have many shortcomings. For example, some methods use catalysts with low activity, resulting in slow reaction rates and low production efficiency; some methods lack precise control over reaction conditions, making it difficult to guarantee reaction stability and product quality; and some methods are not efficient in utilizing raw materials, leading to waste.

[0003] Chinese patent CN119569056A discloses a method for preparing carbonyl fluoride, using hexafluoropropylene and oxygen as raw materials, and reacting them in a reactor filled with a catalyst under high temperature conditions. The catalyst is one of palladium oxide, ruthenium oxide, platinum oxide, and molybdenum oxide. Such catalysts are expensive, greatly increasing production costs. Chinese patent CN109607507A discloses a method for preparing carbonyl fluoride by cracking perfluorinated compounds. This method uses silver oxide as a catalyst, and the reaction temperature reaches as high as 1200℃, which not only places high demands on the reaction equipment, increasing equipment investment and operating costs, but also poses significant safety hazards. Furthermore, in detecting carbonyl fluoride, this application uses the method of passing the product through anhydrous methanol to convert it into an ester to determine the carbonyl fluoride content in the product. This reaction is a highly exothermic reaction; at high temperatures, hexafluoropropylene is easily over-oxidized to form carbon dioxide, and this method cannot remove the heat of reaction in time, thus making it difficult to stably control the temperature during the reaction process, thereby affecting the purity and yield of the product. Furthermore, determining the content of carbonyl fluoride in the product through esterification reaction has problems such as complex reaction and low accuracy. It cannot reflect the actual situation in the reaction process in a timely and accurate manner, which is not conducive to optimizing and adjusting process parameters.

[0004] Therefore, there is an urgent need to develop a continuous synthesis process for carbonyl fluoride that is economical, safe, and highly selective in order to meet market demand. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a continuous synthesis method for carbonyl fluoride, employing inexpensive potassium fluoride or sodium fluoride as a catalyst. This method achieves efficient catalysis under relatively mild temperature conditions, ensuring safety and economy. During the reaction, a segmented independent temperature control device can promptly remove excess heat, preventing excessive oxidation of reactants and the formation of byproducts. Simultaneously, the product gas reflux dilutes the reactants to avoid localized overheating and temperature runaway, and allows the reactants to enter and exit the reaction tube multiple times rapidly, effectively resulting in multiple reactions and thus a more complete reaction and higher conversion rate.

[0006] The technical solution adopted in this invention is as follows:

[0007] The continuous synthesis method of carbonyl fluoride is carried out in a reaction tube, which is divided into a preheating section, a reaction initiation section, a continuous reaction section and a reaction quenching section from the inlet end to the outlet end, and each section is independently temperature controlled.

[0008] The continuous synthesis method includes the following steps:

[0009] The catalyst was loaded into the reaction initiation section and the continuous reaction section. The reaction initiation section and the continuous reaction section were heated to 350°C, and then nitrogen was introduced for purging at a flow rate of 5 L / min for 8 hours to remove moisture from the reaction tube and the catalyst. After purging, the moisture content in the reaction tube was measured using a dew point meter to ensure that the moisture content was <10 ppm. After the moisture content is tested and found to be within acceptable limits, nitrogen gas is introduced into the reaction tube, and the pressure inside the reaction tube is adjusted to 0.15~0.2MPa. Then, fluorinated organic compounds and oxygen are introduced into the mixer for mixing. The resulting mixed gas is introduced from the inlet end of the reaction tube and flows through each section of the reaction tube in sequence. In the reaction initiation section and the continuous reaction section, the gas comes into contact with the catalyst and undergoes an oxidation reaction. The product gas is collected at the outlet end of the reaction tube, and the collected product gas is circulated back through a membrane press. 85~95wt.% of the collected product gas is returned to the inlet end of the mixer, mixed with the newly introduced fluorinated organic compounds and oxygen, and then enters the reaction tube again. The product gas that is not returned enters the distillation column for separation to obtain carbonyl fluoride products. The separated oxygen is recovered and reused.

[0010] The catalyst support is one of activated carbon, metal oxide or metal fluoride, and the active component is an alkali metal fluoride;

[0011] The fluorinated organic compound is hexafluoropropylene or trifluoroacetyl fluoride.

[0012] The molar ratio of the fluorinated organic compound to oxygen is 1:(1.5~5).

[0013] The temperatures and total residence times of each section of the reaction tube are as follows: the temperature of the preheating section is 100~150℃, and the total residence time is 2~4s; the temperature of the reaction initiation section is 250~300℃, and the total residence time is 1~3s; the temperature of the continuous reaction section is 330~380℃, and the total residence time is 1~3s; the temperature of the reaction quenching section is 70~90℃, and the total residence time is 5~8s.

[0014] The pressure in each section of the reaction tube is 0.05~0.3MPa.

[0015] Preferably, the catalyst support is activated carbon; the alkali metal fluoride is at least one of potassium fluoride or sodium fluoride.

[0016] The method for preparing the catalyst includes the following steps:

[0017] (1) Pre-treat activated carbon by immersing it in nitric acid solution, then wash the pre-treated activated carbon until it is neutral and dry it.

[0018] (2) The activated carbon obtained in step (1) after nitric acid pretreatment is stirred and mixed with an alkali metal fluoride solution, and then dried, ground and calcined in sequence to obtain an alkali metal fluoride supported catalyst.

[0019] (3) The alkali metal fluoride supported catalyst, binder and water are mixed and kneaded, extruded and calcined in sequence to finally obtain the catalyst.

[0020] In step (1), the concentration of the nitric acid solution is 30~50 wt.%; the pretreatment temperature is 30~60℃ and the time is 2~6h.

[0021] In step (2), the concentration of the alkali metal fluoride solution is 10~50 wt.%; the impregnation temperature is room temperature and the impregnation time is 12~48 h; the calcination temperature is 300~400℃ and the calcination time is 2~5 h; and the loading of the alkali metal fluoride is 20~60%.

[0022] In step (3), the binder is starch; the mass ratio of alkali metal fluoride supported catalyst, binder and water is (70~90):(1~5):(10~20).

[0023] In step (3), the roasting temperature is 300~400℃ and the roasting time is 1~4h.

[0024] The catalyst is spherical in shape with a particle size of 3-6 mm.

[0025] Preferably, the synthesis apparatus used in the continuous synthesis method of carbonyl fluoride includes a mixer, a reaction tube, a buffer tank, and a membrane press connected in sequence. The outlet of the membrane press is connected to the inlet of the mixer and a distillation column via pipelines. The inlet of the mixer is connected to a hexafluoropropylene feed line, an oxygen feed line, and a nitrogen line. An online gas chromatograph is installed on the outlet pipeline of the membrane press. The reaction tube is divided into a preheating section, a reaction initiation section, a continuous reaction section, and a reaction quenching section from the inlet end to the outlet end, and each section is independently temperature-controlled. The reaction tube can be a straight pipe, or the shape of the pipeline can be changed according to the site.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0027] (1) The continuous synthesis method of carbonyl fluoride described in this invention uses hexafluoropropylene or trifluoroacetyl fluoride as raw materials, avoiding the use of highly corrosive and toxic gases such as fluorine, phosgene, and tetrafluoroethylene, thus reducing the safety risks of raw materials. At the same time, it uses inexpensive potassium fluoride or sodium fluoride as catalysts, and the reaction can be achieved under relatively mild temperature conditions, which is safe, efficient and cost-controllable;

[0028] (2) By dividing the reaction tube into a preheating section, a reaction initiation section, a continuous reaction section and a reaction quenching section, and implementing independent temperature control for each section, the present invention can remove excess heat in time, maintain a reasonable reaction temperature, accurately control the reaction process, effectively prevent hexafluoropropylene from being over-oxidized to form the by-product carbon dioxide, thereby improving the selectivity of the target product carbonyl fluoride and reducing raw material loss.

[0029] (3) In this invention, the collected product gas is partially refluxed and mixed with newly introduced fluorinated organic compounds and oxygen before being reintroduced into the reaction tube. On the one hand, the refluxed gas can serve as a dilution gas to dilute the newly introduced oxygen and fluorinated organic compounds, preventing runaway temperatures caused by violent reactions due to excessively high local concentrations, and ensuring the stability of the reaction system temperature. On the other hand, it allows the reactants to enter and exit the reaction tube quickly and repeatedly, reducing the residence time in the high-temperature reaction zone. This is equivalent to the raw materials reacting multiple times, which can make the reaction more complete and improve the conversion rate. It can also effectively inhibit the excessive oxidation of fluorinated organic compounds and alleviate the intensity of exothermic reactions, which is beneficial for controlling the reaction temperature.

[0030] (4) The reaction process of this invention does not produce corrosive gases such as hydrogen fluoride, thus reducing equipment corrosion problems; high-purity carbonyl fluoride can be obtained by separating the unrecirculated product gas through a distillation column. In addition, the composition of the product can be determined in a timely manner through online gas phase detection, thereby adjusting the process parameters in a timely manner, improving the conversion rate of fluorine-containing organic compounds and the selectivity of carbonyl fluoride, and reducing raw material loss. Attached Figure Description

[0031] Figure 1This is a schematic diagram of the synthesis apparatus used in the embodiment. In the figure:

[0032] 1. Mixer; 2. Reaction tube; 3. Buffer tank; 4. Membrane press; 5. Distillation column; 6. Hexafluoropropylene feed line; 7. Oxygen feed line; 8. Nitrogen line; 9. Online gas chromatograph; 10. Preheating section; 11. Reaction initiation section; 12. Continuous reaction section; 13. Reaction quenching section.

[0033] Figure 2 The image shows a gas chromatogram of the carbonyl fluoride prepared in Example 1. Detailed Implementation

[0034] The present invention will be further described below with reference to the embodiments, but these embodiments do not limit the implementation of the present invention.

[0035] Unless otherwise specified, the raw materials used in the examples and comparative examples are all commercially available materials, and the process methods used in the examples and comparative examples are all conventional methods in the art.

[0036] The catalyst used in the examples was prepared as follows:

[0037] (1) The activated carbon was vacuum dried at 110°C for 1 hour, then the activated carbon was immersed in a 35 wt.% nitric acid solution and pretreated at 60°C for 3 hours. The pretreated activated carbon was washed with deionized water until neutral and then dried in a spray dryer for 12 hours.

[0038] (2) The activated carbon pretreated with nitric acid obtained in step (1) was mixed with potassium fluoride solution (concentration of 20 wt.%, solvent of deionized water) and stirred for 60 min. The mass ratio of activated carbon pretreated with nitric acid to potassium fluoride was 4:1. After soaking at room temperature for 48 h, it was placed in a spray dryer and dried for 12 h. The dried catalyst was ground into powder and placed in a calcination furnace and calcined at 300 °C for 3 h under a nitrogen atmosphere to obtain activated carbon supported catalyst with a potassium fluoride loading of 20%.

[0039] (3) The activated carbon-supported catalyst, starch and water are mixed in a mass ratio of 80:5:15 and kneaded in a kneader for 30 minutes. Then the kneaded mud is loaded into a hydraulic extruder and extruded to form a catalyst preform. The preform is placed in a calcination furnace and calcined at 350°C for 1 hour to finally obtain the catalyst. The catalyst is spherical in shape and has a particle size of 4±1 mm.

[0040] The synthesis apparatus used in the embodiments, such as Figure 1As shown, the system includes a mixer 1, a reaction tube 2, a buffer tank 3, and a membrane press 4 connected in sequence. The outlet of the membrane press 4 is connected to the inlet of the mixer 1 and the distillation column 5 via pipelines. The inlet of the mixer 1 is connected to a hexafluoropropylene feed line 6, an oxygen feed line 7, and a nitrogen line 8. An online gas chromatograph 9 is installed on the outlet pipeline of the membrane press 4. The reaction tube 1 uses N0600 nickel tubing with a nominal diameter of 80 mm. The reaction tube 1 is divided into a preheating section 10, a reaction initiation section 11, a continuous reaction section 12, and a reaction quenching section 13 from the inlet end to the outlet end. Each section is independently temperature controlled.

[0041] Example 1

[0042] The continuous synthesis method of the aforementioned carbonyl fluoride includes the following steps:

[0043] The catalyst was continuously and seamlessly loaded into the reaction initiation and sustaining reaction sections. The reaction initiation and sustaining reaction sections were heated to 350±15℃, and then purged with nitrogen at a flow rate of 5L / min for 8 hours to remove moisture from the reaction tubes and catalyst. After purging, the moisture content in the reaction tubes was measured using a dew point meter to ensure that the moisture content was <10ppm. After the moisture content is tested and found to be within acceptable limits, nitrogen gas is introduced into the reaction tube, and the pressure inside the reaction tube is adjusted to 0.175±0.025MPa. Then, hexafluoropropylene and oxygen with a molar ratio of 1:2 are introduced into the mixer for mixing. The resulting mixed gas is introduced from the inlet end of the reaction tube and flows through each section of the reaction tube in sequence. In the reaction initiation section and the continuous reaction section, the gas comes into contact with the catalyst and undergoes an oxidation reaction. The product gas is collected at the outlet end of the reaction tube, and the collected product gas is circulated back through a membrane press. 90±5wt.% of the collected product gas is returned to the inlet end of the mixer, mixed with the newly introduced hexafluoropropylene and oxygen, and then enters the reaction tube again. The product gas that is not returned enters the distillation column for separation to obtain carbonyl fluoride product. The separated oxygen is recovered and reused.

[0044] The temperatures and total residence times of each section of the reaction tube are as follows: the preheating section has a temperature of 115±15℃ and a total residence time of 3s; the reaction initiation section has a temperature of 275±15℃ and a total residence time of 1.5s; the continuous reaction section has a temperature of 350±15℃ and a total residence time of 1s; and the reaction quenching section has a temperature of 80±10℃ and a total residence time of 5s. The pressure of each section of the reaction tube is 0.18±0.1MPa.

[0045] The content of carbonyl fluoride in the product was determined to be 95% by gas chromatography, and the carbon dioxide content was 0.6%. The HFP conversion rate was calculated to be 100%, and the carbonyl fluoride selectivity was 98.4%.

[0046] Figure 2Table 1 shows the gas chromatogram of the carbonyl fluoride prepared in Example 1. Figure 2 The corresponding gas chromatography data, combined with Figure 2 Analysis of Table 1 shows that, in gas chromatography, the component with a retention time of 20.098 min is carbonyl fluoride, with a peak area percentage as high as 94.992%.

[0047] Table 1: Figure 2 The corresponding gas chromatography data

[0048]

[0049] Example 2

[0050] The continuous synthesis method of the aforementioned carbonyl fluoride includes the following steps:

[0051] The catalyst was continuously and seamlessly loaded into the reaction initiation and sustaining reaction sections. The reaction initiation and sustaining reaction sections were heated to 350±15℃, and then purged with nitrogen at a flow rate of 5L / min for 8 hours to remove moisture from the reaction tubes and catalyst. After purging, the moisture content in the reaction tubes was measured using a dew point meter to ensure that the moisture content was <10ppm. After the moisture content is tested and found to be within acceptable limits, nitrogen gas is introduced into the reaction tube, and the pressure inside the reaction tube is adjusted to 0.175±0.025MPa. Then, hexafluoropropylene and oxygen with a molar ratio of 1:3 are introduced into the mixer for mixing. The resulting mixed gas is introduced from the inlet end of the reaction tube and flows through each section of the reaction tube in sequence. In the reaction initiation section and the continuous reaction section, the gas comes into contact with the catalyst and undergoes an oxidation reaction. The product gas is collected at the outlet end of the reaction tube, and the collected product gas is circulated back through a membrane press. 90±5wt.% of the collected product gas is returned to the inlet end of the mixer, mixed with the newly introduced hexafluoropropylene and oxygen, and then enters the reaction tube again. The product gas that is not returned enters the distillation column for separation to obtain carbonyl fluoride product. The separated oxygen is recovered and reused.

[0052] The temperatures and total residence times of each section of the reaction tube are as follows: the preheating section has a temperature of 115±15℃ and a total residence time of 3s; the reaction initiation section has a temperature of 275±15℃ and a total residence time of 1.5s; the continuous reaction section has a temperature of 350±15℃ and a total residence time of 1s; and the reaction quenching section has a temperature of 80±10℃ and a total residence time of 5s. The pressure of each section of the reaction tube is 0.18±0.1MPa.

[0053] The content of carbonyl fluoride in the product was determined to be 87% by gas chromatography, and the carbon dioxide content was 1.1%. The conversion rate of HFP was calculated to be 99.5%, and the selectivity was 91.5%.

[0054] Example 3

[0055] The continuous synthesis method of the aforementioned carbonyl fluoride includes the following steps:

[0056] The catalyst was continuously and seamlessly loaded into the reaction initiation and sustaining reaction sections. The reaction initiation and sustaining reaction sections were heated to 350±15℃, and then purged with nitrogen at a flow rate of 5L / min for 8 hours to remove moisture from the reaction tubes and catalyst. After purging, the moisture content in the reaction tubes was measured using a dew point meter to ensure that the moisture content was <10ppm. After the moisture content is tested and found to be within acceptable limits, nitrogen gas is introduced into the reaction tube, and the pressure inside the reaction tube is adjusted to 0.175±0.025MPa. Then, hexafluoropropylene and oxygen with a molar ratio of 1:5 are introduced into the mixer for mixing. The resulting mixed gas is introduced from the inlet end of the reaction tube and flows through each section of the reaction tube in sequence. In the reaction initiation section and the continuous reaction section, the gas comes into contact with the catalyst and undergoes an oxidation reaction. The product gas is collected at the outlet end of the reaction tube, and the collected product gas is circulated back through a membrane press. 90±5wt.% of the collected product gas is returned to the inlet end of the mixer, mixed with the newly introduced hexafluoropropylene and oxygen, and then enters the reaction tube again. The product gas that is not returned enters the distillation column for separation to obtain carbonyl fluoride product. The separated oxygen is recovered and reused.

[0057] The temperatures and total residence times of each section of the reaction tube are as follows: the preheating section has a temperature of 115±15℃ and a total residence time of 3s; the reaction initiation section has a temperature of 275±15℃ and a total residence time of 1.5s; the continuous reaction section has a temperature of 350±15℃ and a total residence time of 1s; and the reaction quenching section has a temperature of 80±10℃ and a total residence time of 5s. The pressure of each section of the reaction tube is 0.18±0.1MPa.

[0058] The content of carbonyl fluoride in the product was determined to be 89.2% by gas chromatography, and the carbon dioxide content was 4.3%. The HFP conversion rate was calculated to be 100%, and the carbonyl fluoride selectivity was 92%.

[0059] Example 4

[0060] The continuous synthesis method of the aforementioned carbonyl fluoride includes the following steps:

[0061] The catalyst was continuously and seamlessly loaded into the reaction initiation and sustaining reaction sections. The reaction initiation and sustaining reaction sections were heated to 350±15℃, and then purged with nitrogen at a flow rate of 5L / min for 8 hours to remove moisture from the reaction tubes and catalyst. After purging, the moisture content in the reaction tubes was measured using a dew point meter to ensure that the moisture content was <10ppm. After the moisture content is tested and found to be within acceptable limits, nitrogen gas is introduced into the reaction tube, and the pressure inside the reaction tube is adjusted to 0.175±0.025MPa. Then, trifluoroacetyl fluoride and oxygen with a molar ratio of 1:1.5 are introduced into the mixer for mixing. The resulting mixed gas is introduced from the inlet end of the reaction tube and flows through each section of the reaction tube in sequence. In the reaction initiation section and the continuous reaction section, the gas comes into contact with the catalyst and undergoes an oxidation reaction. The product gas is collected at the outlet end of the reaction tube, and the collected product gas is circulated back through a membrane press. 90±5wt.% of the collected product gas is returned to the inlet end of the mixer, mixed with the newly introduced trifluoroacetyl fluoride and oxygen, and then enters the reaction tube again. The product gas that is not returned enters the distillation column for separation to obtain carbonyl fluoride product. The separated oxygen is recovered and reused.

[0062] The temperatures and total residence times for each section of the reaction tube are as follows: Preheating section: 130±15℃, total residence time: 3.5s; Reaction initiation section: 275±15℃, total residence time: 2s; Continuous reaction section: 350±15℃, total residence time: 2s; Reaction quenching section: 80±10℃, total residence time: 7.5s. The pressure in each section of the reaction tube is 0.18±0.1MPa.

[0063] The content of carboxylic acid fluoride in the product was determined to be 92.6% by gas chromatography, and the carbon dioxide content was 1.15%. The conversion rate of trifluoroacetyl fluoride was calculated to be 98.7%, and the selectivity of carboxylic acid fluoride was 98.77%.

[0064] Comparative Example 1

[0065] The difference from Example 1 is that no catalyst was added to the reaction tube; otherwise, it was the same as Example 1. Gas chromatography analysis showed that the content of carbonyl fluoride in the product was 37.6%, and the content of trifluoroacetyl fluoride was 35.6%. The calculated HFP conversion rate was 90%, and the selectivity of carbonyl fluoride was 35.2%. This indicates that without a catalyst, the reaction system cannot effectively promote the further oxidation of the intermediate trifluoroacetyl fluoride to the target product carbonyl fluoride, resulting in a significant decrease in the selectivity of carbonyl fluoride.

[0066] Comparative Example 2

[0067] The difference from Example 1 is that the product gas collected at the outlet of the reaction tube is not refluxed for further reaction, but directly fed into a distillation column for separation. The reaction gas is analyzed by online monitoring. The system pressure is maintained at 0.18 ± 0.1 MPa, and other parameters are the same as in Example 1. The content of carbonyl fluoride in the product was determined to be 47.9% by online gas chromatography. The conversion rate of HFP was calculated to be 91.8%, and the selectivity of carbonyl fluoride was 45.4%. This indicates that the lack of product gas reflux leads to the reactants passing through the reactor only once, resulting in insufficient residence time and a significant reduction in reaction conversion and selectivity.

[0068] Comparative Example 3

[0069] The difference from Example 1 is that the alumina-supported AgO catalyst was prepared according to Example 6 of patent CN109607507A, using spherical alumina support with a particle size of 4±1 mm. Other aspects are the same as in Example 1. Online gas chromatography analysis revealed that the product contained 44.3% carbofluoride, 39.6% trifluoroacetyl fluoride, 5% pentafluoropropionyl fluoride, and 1.2% HFA. The calculated HFP conversion rate was 97.5%, and the carbofluoride selectivity was 47.94%.

Claims

1. A continuous synthesis method for carbonyl fluoride, characterized in that, The continuous synthesis method is carried out in a reaction tube, which is divided into a preheating section, a reaction initiation section, a continuous reaction section and a reaction quenching section from the inlet end to the outlet end, and each section is independently temperature controlled. The continuous synthesis method includes the following steps: The catalyst is loaded into the reaction initiation section and the continuous reaction section. The reaction initiation section and the continuous reaction section are heated and then purged with nitrogen. After purging, fluorinated organic compounds and oxygen are introduced into a mixer for mixing. The resulting mixed gas is introduced from the inlet end of the reaction tube and flows through each section of the reaction tube in sequence. In the reaction initiation section and the continuous reaction section, the gas comes into contact with the catalyst and undergoes an oxidation reaction. The product gas is collected at the outlet end of the reaction tube. 85-95 wt.% of the collected product gas is returned to the inlet end of the mixer and mixed with the newly introduced fluorinated organic compounds and oxygen before entering the reaction tube again. The product gas that is not returned enters a distillation column for separation to obtain the carbonyl fluoride product. The catalyst support is one of activated carbon, metal oxide or metal fluoride, and the active component is an alkali metal fluoride; The fluorinated organic compound is hexafluoropropylene or trifluoroacetyl fluoride; The temperatures and total residence times of each section of the reaction tube are as follows: the temperature of the preheating section is 100~150℃, and the total residence time is 2~4s; the temperature of the reaction initiation section is 250~300℃, and the total residence time is 1~3s; the temperature of the continuous reaction section is 330~380℃, and the total residence time is 1~3s; the temperature of the reaction quenching section is 70~90℃, and the total residence time is 5~8s.

2. The continuous synthesis method of carbonyl fluoride according to claim 1, characterized in that, The molar ratio of the fluorinated organic compound to oxygen is 1:(1.5~5).

3. The continuous synthesis method of carbonyl fluoride according to claim 1, characterized in that, The pressure in each section of the reaction tube is 0.05~0.3MPa.

4. The continuous synthesis method of carbonyl fluoride according to claim 1, characterized in that, The catalyst is supported by activated carbon; the alkali metal fluoride is at least one of potassium fluoride or sodium fluoride.

5. The continuous synthesis method of carbonyl fluoride according to claim 4, characterized in that, The method for preparing the catalyst includes the following steps: (1) Pre-treat activated carbon by immersing it in nitric acid solution, then wash the pre-treated activated carbon until it is neutral and dry it. (2) The activated carbon obtained in step (1) after nitric acid pretreatment is stirred and mixed with an alkali metal fluoride solution, and then dried, ground and calcined in sequence to obtain an alkali metal fluoride supported catalyst. (3) The alkali metal fluoride supported catalyst, binder and water are mixed and kneaded, extruded and calcined in sequence to finally obtain the catalyst.

6. The continuous synthesis method of carbonyl fluoride according to claim 5, characterized in that, In step (1), the concentration of the nitric acid solution is 30~50 wt.%.

7. The continuous synthesis method of carbonyl fluoride according to claim 5, characterized in that, In step (2), the concentration of the alkali metal fluoride solution is 10~50 wt.%; the impregnation temperature is room temperature and the impregnation time is 12~48 h; the calcination temperature is 300~400℃ and the calcination time is 2~5 h; and the loading of the alkali metal fluoride is 20~60%.

8. The continuous synthesis method of carbonyl fluoride according to claim 5, characterized in that, In step (3), the binder is starch; the mass ratio of alkali metal fluoride supported catalyst, binder and water is (70~90):(1~5):(10~20); the calcination temperature is 300~400℃ and the calcination time is 1~4h.

9. The continuous synthesis method of carbonyl fluoride according to claim 5, characterized in that, The catalyst is spherical in shape with a particle size of 3-6 mm.

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