Continuous synthesis method of carbonyl fluoride

Abstract

The invention belongs to the technical field of fluorine chemical industry, and particularly relates to a continuous synthesis method of carbonyl fluoride. The method is carried out in a reaction tube, the reaction tube is divided into a preheating section, a reaction initiation section, a continuous reaction section and a reaction quenching section, a catalyst is filled in the reaction initiation section and the continuous reaction section, and a fluorine-containing organic compound and oxygen are mixed and then are introduced from an inlet end of the reaction tube and sequentially flow through each section of the reaction tube, collecting a product gas at the outlet end of the reaction tube, refluxing a part of the collected product gas, enabling the product gas to enter the reaction tube again, and enabling the product gas which is not refluxed to enter a distillation tower to be separated, so as to obtain a carbonyl fluoride product; in the reaction process, redundant heat can be removed in time through the segmented independent temperature control device, and generation of by-products due to excessive oxidation is prevented. Meanwhile, the reflux of the product gas can dilute the reaction raw materials to avoid temperature runaway caused by overhigh local concentration, and can enable the reaction materials to quickly enter and exit from the reaction tube for multiple times, which is equivalent to the reaction of the raw materials for multiple times, so that the reaction is more sufficient and the conversion rate is higher.

Description

Technical Field

[0001] The invention belongs to the technical field of fluorine chemical industry, and particularly relates to a continuous synthesis method of carbonyl fluoride. Background Art

[0002] As an important fluorine-containing compound, carbonyl fluoride has broad application prospects in the fields of chemical industry, electronics, semiconductors, etc. For example, in the semiconductor manufacturing process, carbonyl fluoride can be used in the etching process, and its high selectivity and etching rate can meet the requirements of high-precision processing; in the chemical industry, carbonyl fluoride can be used as an intermediate in organic synthesis and participate in various chemical reactions. Therefore, the development of an efficient, economical and easy-to-industrial carbonyl fluoride synthesis method is of great practical significance. However, traditional carbonyl fluoride synthesis methods have many shortcomings. For example, the catalysts used in some methods have low activity and slow reaction rates, resulting in low production efficiency; some methods do not have precise control over the reaction conditions, making it difficult to ensure the stability of the reaction and the quality of the product; and some methods are not efficient in raw material utilization, resulting in problems such as raw material waste.

[0003] Chinese patent CN119569056A discloses a method for preparing carbonyl fluoride, using hexafluoropropylene and oxygen as raw materials. A catalyst is introduced into a reactor filled with a catalyst under high temperature conditions. The catalyst is one of palladium oxide, ruthenium oxide, platinum oxide, and molybdenum oxide. These catalysts are expensive, significantly increasing production costs. Chinese patent CN109607507A discloses a method for preparing carbonyl fluoride by cracking a perfluorinated compound. This method uses silver oxide as a catalyst and the reaction temperature reaches as high as 1200°C. This not only places high demands on the reaction equipment, increasing equipment investment and operating costs, but also poses significant safety risks. Furthermore, when testing for carbonyl fluoride, the application uses a method of converting the product into an ester by passing it through anhydrous methanol. This reaction is highly exothermic, and at high temperatures, hexafluoropropylene is prone to over-oxidation to form carbon dioxide. This method cannot promptly remove the reaction heat, making it difficult to stabilize the temperature during the reaction, which in turn affects the purity and yield of the product. In addition, 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 of the reaction process in a timely and accurate manner, which is not conducive to optimizing and adjusting the process parameters.

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

[0005] In view of the deficiencies in the prior art, the object of the present invention is to provide a continuous synthesis method of carbonyl fluoride, which adopts low-cost potassium fluoride or sodium fluoride as catalyst, can achieve efficient catalysis under relatively mild temperature conditions, safe and economic. During the reaction process, the excess heat can be removed in time by the segmented independent temperature control device to prevent the reactants from being over-oxidized to form by-products. At the same time, the product gas reflux can not only dilute the reaction raw materials to avoid the local concentration from being too high to cause temperature rise, but also allow the reaction materials to quickly enter and exit the reaction tube multiple times, which is equivalent to the raw materials being reacted multiple times, thereby making the reaction more sufficient and the conversion rate higher.

[0006] The technical solutions adopted by the present invention are as follows: The continuous synthesis method of carbonyl fluoride is carried out in a reaction tube, wherein 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 continuous synthesis method comprises the following steps: The catalyst was loaded into the reaction initiation section and the continuous reaction section, and the temperature of the reaction initiation section and the continuous reaction section was raised to 350°C. Then, nitrogen was introduced for purging at a nitrogen flow rate of 5 L / min for 8 hours to remove moisture from the reaction tube and the catalyst. After the purging was completed, the moisture content in the reaction tube was tested using a dew point meter to ensure that the moisture content was <10 ppm. After the moisture test is qualified, nitrogen is introduced into the reaction tube, and the pressure in the reaction tube is adjusted to 0.15~0.2MPa. The fluorinated organic compound and oxygen are then introduced into the mixer for mixing. The formed mixed gas is introduced from the inlet end of the reaction tube, flows through each section of the reaction tube in sequence, contacts the catalyst in the reaction initiation section and the continuous reaction section, and an oxidation reaction occurs. The product gas is collected at the outlet end of the reaction tube, and the collected product gas is circulated and refluxed through a membrane press. 85~95wt.% of the collected product gas is refluxed to the inlet end of the mixer, mixed with the newly introduced fluorinated organic compound and oxygen, and then enters the reaction tube again. The product gas that is not refluxed enters the distillation tower for separation to obtain a carbonyl fluoride product, and the separated oxygen is recovered for further use. The catalyst carrier is one of activated carbon, metal oxide or metal fluoride, and the active component is alkali metal fluoride; The fluorine-containing organic compound is hexafluoropropylene or trifluoroacetyl fluoride.

[0007] The molar ratio of the fluorine-containing organic compound to oxygen is 1:(1.5-5).

[0008] The temperature and total residence time of each section of the reaction tube are as follows: the temperature of the preheating section is 100-150°C, and the total residence time is 2-4 seconds; the temperature of the reaction initiation section is 250-300°C, and the total residence time is 1-3 seconds; the temperature of the continuous reaction section is 330-380°C, and the total residence time is 1-3 seconds; the temperature of the reaction quenching section is 70-90°C, and the total residence time is 5-8 seconds.

[0009] The pressure of each section of the reaction tube is 0.05~0.3MPa.

[0010] Preferably, the carrier of the catalyst is activated carbon; and the alkali metal fluoride is at least one of potassium fluoride or sodium fluoride.

[0011] The preparation method of the catalyst comprises the following steps: (1) Immersing the activated carbon in a nitric acid solution for pretreatment, washing the pretreated activated carbon to neutrality, and drying; (2) The activated carbon obtained in step (1) and pretreated with nitric acid is stirred and mixed with an alkali metal fluoride solution, and after impregnation, the mixture is dried, ground, and calcined in sequence to obtain an alkali metal fluoride-supported catalyst; (3) The alkali metal fluoride-supported catalyst, a binder and water are mixed, and the mixture is kneaded, extruded and calcined in sequence to finally obtain the catalyst.

[0012] In the step (1), the concentration of the nitric acid solution is 30-50 wt.%, the pretreatment temperature is 30-60° C., and the pretreatment time is 2-6 hours.

[0013] In the 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 roasting temperature is 300-400° C., and the roasting time is 2-5 h; and the loading amount of the alkali metal fluoride is 20-60%.

[0014] In the step (3), the binder is starch; the mass ratio of the alkali metal fluoride-supported catalyst, the binder and water is (70-90): (1-5): (10-20).

[0015] In the step (3), the calcination temperature is 300-400°C and the calcination time is 1-4 hours.

[0016] The catalyst is spherical in shape and has a particle size of 3 to 6 mm.

[0017] Preferably, the synthesis apparatus used in the continuous synthesis method of carbonyl fluoride comprises 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 the distillation column via pipelines. The inlet of the mixer is connected to a hexafluoropropylene feed line, an oxygen feed line, and a nitrogen feed line, respectively. The outlet pipeline of the membrane press is provided with an online gas chromatograph. The reaction tube is sequentially divided from the inlet to the outlet into a preheating section, a reaction initiation section, a continuous reaction section, and a reaction quenching section, each section being independently temperature-controlled. The reaction tube can be a straight tube, or the shape of the tube can be modified to suit the site.

[0018] Compared with the prior art, the present invention has the following beneficial effects: (1) The continuous synthesis method of carbonyl fluoride described in the present invention uses hexafluoropropylene or trifluoroacetyl fluoride as raw materials, avoiding the use of highly corrosive and toxic gases such as fluorine, phosgene, and tetrafluoroethylene, thereby reducing the safety risks of the raw materials. At the same time, using inexpensive potassium fluoride or sodium fluoride as a catalyst, the reaction can be achieved under relatively mild temperature conditions, making it safe, efficient, and cost-effective. (2) The present invention divides the reaction tube into a preheating section, a reaction initiation section, a continuous reaction section, and a reaction quenching section, and implements independent temperature control for each section. This allows for timely removal of excess heat, maintains a reasonable reaction temperature, accurately controls the reaction process, and effectively prevents excessive oxidation of hexafluoropropylene to form a byproduct of carbon dioxide, thereby improving the selectivity of the target product, carbonyl fluoride, and reducing raw material loss. (3) The present invention partially refluxes the collected product gas, mixes it with the newly introduced fluorinated organic compound and oxygen, and then re-enters the reaction tube. On the one hand, the reflux gas can be used as a diluent gas to dilute the newly introduced oxygen and fluorinated organic compound, preventing the temperature runaway phenomenon caused by the violent reaction due to excessive local concentration, and ensuring the temperature stability of the reaction system; on the other hand, it can make the reaction materials quickly enter and exit the reaction tube multiple times, reducing the residence time in the high-temperature reaction zone, which is equivalent to the raw materials reacting multiple times, making the reaction more complete to improve the conversion rate, and effectively inhibiting the excessive oxidation of the fluorinated organic compound, while alleviating the intensity of heat release, which is conducive to controlling the reaction temperature; (4) The reaction process of the present invention does not produce corrosive gases such as hydrogen fluoride, thereby reducing equipment corrosion problems. High-purity carbonyl fluoride can be obtained by separating the non-refluxed product gas through a distillation tower. In addition, through online gas phase detection, the composition of the product can be determined in a timely manner, thereby adjusting the process parameters in a timely manner, improving the conversion rate of fluorinated organic compounds and carbonyl fluoride selectivity, and reducing raw material loss. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Schematic diagram of the structure of the synthesis device used in the embodiment, in the figure: 1. Mixer; 2. Reaction tube; 3. Buffer tank; 4. Membrane press; 5. Distillation tower; 6. Hexafluoropropylene feed line; 7. Oxygen feed line; 8. Nitrogen pipeline; 9. Online gas chromatograph; 10. Preheating section; 11. Reaction initiation section; 12. Continuous reaction section; 13. Reaction quenching section.

[0020] Figure 2 This is the gas chromatogram of carbonyl fluoride obtained in Example 1. DETAILED DESCRIPTION

[0021] The present invention will be further described below with reference to the following examples, but they do not limit the implementation of the present invention.

[0022] Unless otherwise specified, the raw materials used in the examples and comparative examples are conventional commercially available raw materials, and the process methods used in the examples and comparative examples are conventional methods in the art unless otherwise specified.

[0023] The catalyst used in the examples was prepared as follows: (1) The activated carbon was vacuum dried at 110 °C for 1 h, then immersed in a 35 wt.% nitric acid solution and pretreated at 60 °C for 3 h. The pretreated activated carbon was washed with deionized water until neutral, and then dried in a spray dryer for 12 h. (2) The activated carbon obtained in step (1) and pretreated with nitric acid was mixed with a potassium fluoride solution (concentration of 20 wt.%, solvent is deionized water), and stirred for 60 min, wherein the mass ratio of the activated carbon and potassium fluoride was 4:1, and then immersed at room temperature for 48 h and dried in a spray dryer for 12 h. The dried catalyst was ground into powder, and the powder was placed in a calcination furnace and calcined at 300 ° C for 3 h under a nitrogen atmosphere to obtain an activated carbon-supported catalyst, wherein the potassium fluoride loading amount was 20%; (3) The activated carbon-loaded catalyst, starch and water were mixed in a mass ratio of 80:5:15, placed in a kneader and kneaded for 30 minutes, and then the kneaded mud was loaded into a hydraulic extruder and extruded to obtain a catalyst embryo. The embryo was placed in a roasting furnace and roasted at 350°C for 1 hour to finally obtain the catalyst. The catalyst was spherical in shape and had a particle size of 4±1 mm.

[0024] The synthesis device used in the embodiment is as follows Figure 1As shown, it 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 tower 5 through pipelines. The inlet of the mixer 1 is connected to a hexafluoropropylene feed pipeline 6, an oxygen feed pipeline 7 and a nitrogen pipeline 8, respectively. The outlet pipeline of the membrane press 4 is provided with an online gas chromatograph 9. The pipeline used in the reaction tube 1 is an N0600 nickel tube 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, and each section is independently temperature-controlled.

[0025] Example 1 The continuous synthesis method of carbonyl fluoride comprises the following steps: The catalyst was loaded continuously and without gaps into the reaction initiation section and the sustained reaction section. The reaction initiation section and the sustained reaction section were heated to 350±15°C and then purged with nitrogen at a flow rate of 5L / min for 8 hours to remove moisture from the reaction tube and catalyst. After the purge was complete, the moisture content in the reaction tube was tested using a dew point meter to ensure that the moisture content was <10ppm. After the moisture test is qualified, nitrogen is introduced into the reaction tube, and the pressure in 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 formed mixed gas is introduced from the inlet end of the reaction tube, flows through each section of the reaction tube in sequence, contacts the catalyst in the reaction initiation section and the continuous reaction section, and an oxidation reaction occurs. The product gas is collected at the outlet end of the reaction tube and circulated back through the membrane press. 90±5wt.% of the collected product gas is refluxed 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 refluxed enters the distillation tower for separation to obtain a carbonyl fluoride product, and the separated oxygen is recovered for further use. The temperature and total residence time of each section of the reaction tube are as follows: the preheating section is 115±15°C with a total residence time of 3 seconds; the reaction initiation section is 275±15°C with a total residence time of 1.5 seconds; the continuous reaction section is 350±15°C with a total residence time of 1 second; the reaction quenching section is 80±10°C with a total residence time of 5 seconds. The pressure of each section of the reaction tube is 0.18±0.1 MPa.

[0026] The content of carbonyl fluoride in the product was determined by gas chromatography to be 95%, and the content of carbon dioxide was 0.6%. The HFP conversion was calculated to be 100%, and the carbonyl fluoride selectivity was 98.4%.

[0027] Figure 2 The gas chromatogram of carbonyl fluoride obtained in Example 1 is shown in Table 1. Figure 2 The corresponding gas chromatography data, combined with Figure 2 According to the analysis in Table 1, in the gas chromatography detection, the component corresponding to the retention time of 20.098 min is carbonyl fluoride, and its peak area percentage is as high as 94.992%.

[0028] Table 1: Figure 2 Corresponding gas chromatography data

[0029] Example 2 The continuous synthesis method of carbonyl fluoride comprises the following steps: The catalyst was loaded continuously and without gaps into the reaction initiation section and the sustained reaction section. The reaction initiation section and the sustained reaction section were heated to 350±15°C and then purged with nitrogen at a flow rate of 5L / min for 8 hours to remove moisture from the reaction tube and catalyst. After the purge was complete, the moisture content in the reaction tube was tested using a dew point meter to ensure that the moisture content was <10ppm. After the moisture test is qualified, nitrogen is introduced into the reaction tube, and the pressure in 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 formed mixed gas is introduced from the inlet end of the reaction tube, flows through each section of the reaction tube in sequence, contacts the catalyst in the reaction initiation section and the continuous reaction section, and an oxidation reaction occurs. The product gas is collected at the outlet end of the reaction tube and circulated back through the membrane press. 90±5wt.% of the collected product gas is refluxed 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 refluxed enters the distillation tower for separation to obtain a carbonyl fluoride product, and the separated oxygen is recovered for further use. The temperature and total residence time of each section of the reaction tube are as follows: the preheating section is 115±15°C with a total residence time of 3 seconds; the reaction initiation section is 275±15°C with a total residence time of 1.5 seconds; the continuous reaction section is 350±15°C with a total residence time of 1 second; the reaction quenching section is 80±10°C with a total residence time of 5 seconds. The pressure of each section of the reaction tube is 0.18±0.1 MPa.

[0030] The carbonyl fluoride content of the product was determined by gas chromatography to be 87%, and the carbon dioxide content was 1.1%. The HFP conversion was calculated to be 99.5%, and the selectivity was 91.5%.

[0031] Example 3 The continuous synthesis method of carbonyl fluoride comprises the following steps: The catalyst was loaded continuously and without gaps into the reaction initiation section and the sustained reaction section. The reaction initiation section and the sustained reaction section were heated to 350±15°C and then purged with nitrogen at a flow rate of 5L / min for 8 hours to remove moisture from the reaction tube and catalyst. After the purge was complete, the moisture content in the reaction tube was tested using a dew point meter to ensure that the moisture content was <10ppm. After the moisture test is qualified, nitrogen is introduced into the reaction tube, and the pressure in 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 formed mixed gas is introduced from the inlet end of the reaction tube, flows through each section of the reaction tube in sequence, contacts with the catalyst in the reaction initiation section and the continuous reaction section, and an oxidation reaction occurs. The product gas is collected at the outlet end of the reaction tube and circulated back through the membrane press. 90±5wt.% of the collected product gas is refluxed 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 refluxed enters the distillation tower for separation to obtain a carbonyl fluoride product, and the separated oxygen is recovered for further use. The temperature and total residence time of each section of the reaction tube are as follows: the preheating section is 115±15°C with a total residence time of 3 seconds; the reaction initiation section is 275±15°C with a total residence time of 1.5 seconds; the continuous reaction section is 350±15°C with a total residence time of 1 second; the reaction quenching section is 80±10°C with a total residence time of 5 seconds. The pressure of each section of the reaction tube is 0.18±0.1 MPa.

[0032] Gas chromatography determined the carbonyl fluoride content of the product to be 89.2% and the carbon dioxide content to be 4.3%. Calculations showed an HFP conversion of 100% and a carbonyl fluoride selectivity of 92%.

[0033] Example 4 The continuous synthesis method of carbonyl fluoride comprises the following steps: The catalyst was loaded continuously and without gaps into the reaction initiation section and the sustained reaction section. The reaction initiation section and the sustained reaction section were heated to 350±15°C and then purged with nitrogen at a flow rate of 5L / min for 8 hours to remove moisture from the reaction tube and catalyst. After the purge was complete, the moisture content in the reaction tube was tested using a dew point meter to ensure that the moisture content was <10ppm. After the moisture test is qualified, nitrogen is introduced into the reaction tubes, and the pressure in the reaction tubes is adjusted to 0.175±0.025MPa. Then, trifluoroacetyl fluoride and oxygen in a molar ratio of 1:1.5 are introduced into a mixer for mixing. The formed mixed gas is introduced from the inlet end of the reaction tubes, flows through each section of the reaction tubes in sequence, contacts with the catalyst in the reaction initiation section and the continuous reaction section, and an oxidation reaction occurs. The product gas is collected at the outlet end of the reaction tubes, and the collected product gas is circulated back by a membrane press. 90±5wt.% of the collected product gas is refluxed to the inlet end of the mixer, mixed with newly introduced trifluoroacetyl fluoride and oxygen, and then re-enters the reaction tubes. The product gas that is not refluxed enters a distillation tower for separation to obtain a carbonyl fluoride product, and the isolated oxygen is recovered for continued use. The temperature and total residence time of each section of the reaction tube are as follows: the preheating section is 130±15°C with a total residence time of 3.5 seconds; the reaction initiation section is 275±15°C with a total residence time of 2 seconds; the continuous reaction section is 350±15°C with a total residence time of 2 seconds; and the reaction quenching section is 80±10°C with a total residence time of 7.5 seconds. The pressure of each section of the reaction tube is 0.18±0.1 MPa.

[0034] The content of carbonyl fluoride in the product was determined by gas chromatography to be 92.6%, and the content of carbon dioxide was 1.15%. The conversion rate of trifluoroacetyl fluoride was calculated to be 98.7%, and the selectivity of carbonyl fluoride was 98.77%.

[0035] Comparative Example 1 The difference from Example 1 is that no catalyst was added to the reaction tube, and all other reactions were the same as in Example 1. The carbonyl fluoride content in the product was 37.6% and the trifluoroacetyl fluoride content was 35.6% by gas chromatography. The HFP conversion was calculated to be 90%, and the selectivity of carbonyl fluoride was 35.2%. This indicates that in the absence of a catalyst, the reaction system is unable to effectively promote the further oxidation of the intermediate trifluoroacetyl fluoride into the target product, carbonyl fluoride, resulting in a significant decrease in the carbonyl fluoride selectivity.

[0036] Comparative Example 2 The difference from Example 1 is that the product gas was collected at the outlet of the reaction tube and not refluxed for further reaction, but was directly fed into a distillation column for separation. The reaction gas was then tested and analyzed using online monitoring. The system pressure was maintained at 0.18±0.1 MPa, with all other conditions being the same as in Example 1. The carbonyl fluoride content in the product was determined by online gas chromatography to be 47.9%, and the calculated HFP conversion was 91.8%, with a carbonyl fluoride selectivity of 45.4%. This indicates that the lack of product gas reflux results in a single pass of the reaction mass through the reactor, resulting in insufficient residence time and a significant reduction in reaction conversion and selectivity.

[0037] Comparative Example 3 The difference from Example 1 is that the alumina-supported AgO catalyst was prepared with reference to Example 6 in patent CN109607507A, and the carrier used was spherical alumina with a particle size of 4±1 mm. All other aspects were the same as in Example 1. The carbonyl fluoride content of the product was determined by online gas chromatography to be 44.3%, 39.6% for trifluoroacetyl fluoride, 5% for pentafluoropropionyl fluoride, and 1.2% for HFA. The calculated HFP conversion was 97.5%, and the carbonyl fluoride selectivity was 47.94%.

Claims

1. A continuous synthesis method of 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 comprises the following steps: The catalyst is loaded into a reaction initiation section and a continuous reaction section, the reaction initiation section and the continuous reaction section are heated, and then nitrogen is introduced for purging. After the purging is completed, a fluorinated organic compound and oxygen are introduced into a mixer for mixing. The resulting mixed gas is introduced from the inlet end of a reaction tube, flows through each section of the reaction tube in sequence, contacts the catalyst in the reaction initiation section and the continuous reaction section, and undergoes an oxidation reaction. Product gas is collected at the outlet end of the reaction tube, and 85-95 wt.% of the collected product gas is refluxed to the inlet end of the mixer, mixed with the newly introduced fluorinated organic compound and oxygen, and then re-enters the reaction tube. The product gas that has not refluxed enters a distillation column for separation to obtain a carbonyl fluoride product. The catalyst carrier is one of activated carbon, metal oxide or metal fluoride, and the active component is alkali metal fluoride; The fluorine-containing organic compound is hexafluoropropylene or trifluoroacetyl fluoride.

2. The continuous synthesis method of carbonyl fluoride according to claim 1, wherein The molar ratio of the fluorine-containing 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 temperature and total residence time of each section of the reaction tube are as follows: the temperature of the preheating section is 100-150°C, and the total residence time is 2-4 seconds; the temperature of the reaction initiation section is 250-300°C, and the total residence time is 1-3 seconds; the temperature of the continuous reaction section is 330-380°C, and the total residence time is 1-3 seconds; the temperature of the reaction quenching section is 70-90°C, and the total residence time is 5-8 seconds.

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

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

6. The continuous synthesis method of carbonyl fluoride according to claim 5, characterized in that The preparation method of the catalyst comprises the following steps: (1) Immersing the activated carbon in a nitric acid solution for pretreatment, washing the pretreated activated carbon to neutrality, and drying; (2) The activated carbon obtained in step (1) and pretreated with nitric acid is stirred and mixed with an alkali metal fluoride solution, and after impregnation, the mixture is dried, ground, and calcined in sequence to obtain an alkali metal fluoride-supported catalyst; (3) The alkali metal fluoride-supported catalyst, a binder and water are mixed, and the mixture is kneaded, extruded and calcined in sequence to finally obtain the catalyst.

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

8. The continuous synthesis method of carbonyl fluoride according to claim 6, characterized in that In the 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 roasting temperature is 300-400° C., and the roasting time is 2-5 h; and the loading amount of the alkali metal fluoride is 20-60%.

9. The continuous synthesis method of carbonyl fluoride according to claim 6, characterized in that In the step (3), the binder is starch; the mass ratio of the alkali metal fluoride-supported catalyst, the binder, and water is (70-90): (1-5): (10-20); the roasting temperature is 300-400° C., and the roasting time is 1-4 hours.

10. The continuous synthesis method of carbonyl fluoride according to claim 6, characterized in that: The catalyst is spherical in shape and has a particle size of 3 to 6 mm.

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