Continuous production process of heptafluoroisobutyryl fluoride

Abstract

The invention belongs to the technical field of fluorine chemical industry, and particularly relates to a continuous production process of heptafluoroisobutyryl fluoride. The process is carried out in a tubular reactor, the tubular reactor is divided into a first preheating section, a second reaction section and a third reaction section, a fluorinated molecular sieve catalyst is filled in the second reaction section and the third reaction section, each reaction section is respectively heated to a corresponding preset temperature, carbonyl fluoride and hexafluoropropylene which are mixed and preheated are introduced into the tubular reactor, and a fluorinated molecular sieve catalyst is introduced into the tubular reactor. Enabling the gas to sequentially flow through each section of the tubular reactor, contacting and reacting with the fluorinated molecular sieve catalyst in the second reaction section and the third reaction section, and condensing the gas discharged from the outlet end of the tubular reactor to obtain a heptafluoroisobutyryl fluoride product. According to the process, carbonyl fluoride and hexafluoropropylene are used as gas-phase reaction raw materials, and heptafluoroisobutyryl fluoride is synthesized through a one-step continuous flow rapid reaction. The reaction route is short, the reaction conversion rate and selectivity are high, and industrial large-scale production is easy to realize.

Description

Technical Field

[0001] This invention belongs to the field of fluorochemical technology, specifically relating to a continuous production process for heptafluoroisobutyryl fluoride. Background Technology

[0002] Heptafluoroisobutyryl fluoride is an important fluorine-containing compound with toxicity, a faint odor, and is easily liquefied. It has a wide range of applications, including cleaning agents in the electronics industry, etching agents, pesticide intermediates, and monomers for fluorine-containing materials. The main methods for preparing heptafluoroisobutyryl fluoride are electrochemical methods (electrolytic fluorination) and chemical synthesis methods (acyl fluoride addition method and oxidative cracking method). Among these, the electrochemical method suffers from numerous side reactions, low yield of the main product, and high energy consumption. The chemical synthesis method typically uses a batch reactor, which is simple to operate, but one-pot feeding often results in low yields and the presence of difficult-to-separate byproducts such as fluorinated ketones.

[0003] Chinese patent CN107935884A discloses a method for preparing acyl fluorides. In the presence of an alkali metal fluoride and a co-solvent, a perfluoroolefin R1R2C=CR3R4 undergoes an addition reaction with a carbonyl fluoride to obtain acyl fluoride R1R2(COF)C-CFR3R4. After the reaction is completed, the alkali metal fluoride and the co-solvent are difficult to recover and separate.

[0004] Chinese patent CN110734373A discloses a method for preparing heptafluoroisobutyryl fluoride using a liquid-phase reaction vessel, employing hexafluoropropylene and carbonyl fluoride as raw materials and 2-perfluoroalkylbenzothiazole compounds as catalysts. However, this method suffers from the difficulty in obtaining the catalyst and its high preparation cost.

[0005] Chinese patent CN109651131A discloses a method for preparing heptafluoroisobutyryl fluoride from hexafluoropropylene dimer. The method involves using oxygen and hexafluoropropylene dimer as raw materials in the presence of a catalyst to produce heptafluoroisobutyryl fluoride. However, the oxidation process of oxygen in this method requires high-temperature conditions, posing a safety hazard.

[0006] Therefore, there is an urgent need for a continuous method for the preparation of heptafluoroisobutyryl fluoride that is highly efficient, simple in process, and suitable for industrial production. Summary of the Invention

[0007] To address the shortcomings of existing technologies, the present invention aims to provide a continuous production process for heptafluoroisobutyryl fluoride, which uses carbonyl fluoride and hexafluoropropylene as gas-phase reaction raw materials and employs a one-step continuous flow rapid reaction to synthesize heptafluoroisobutyryl fluoride; the reaction route is short, the reaction conversion rate and selectivity are high, and it is easy to realize large-scale industrial production. The technical solution adopted in this invention is as follows: The continuous production process of heptafluoroisobutyryl fluoride is carried out in a tubular reactor, which is divided into a first preheating section, a second reaction section and a third reaction section from the inlet end to the outlet end, and each section is independently temperature controlled. The continuous production process includes the following steps: Fluorinated molecular sieve catalyst is loaded into the second and third reaction sections. The first, second, and third reaction sections are heated to their respective preset temperatures. The mixed and preheated carbonyl fluoride and hexafluoropropylene are introduced into the tubular reactor, allowing them to flow sequentially through each section of the reactor. In the second and third reaction sections, they come into contact with the fluorinated molecular sieve catalyst and react. The gas discharged from the outlet of the tubular reactor is condensed to obtain heptafluoroisobutyryl fluoride product.

[0008] The temperatures and total residence times of each section of the tubular reactor are as follows: the temperature of the first preheating section is 100~300℃, and the total residence time is 0.01~0.1s; the temperature of the second reaction section is 150~350℃, and the total residence time is 0.01~0.1s; the temperature of the third reaction section is 200~300℃, and the total residence time is 0.01~0.1s.

[0009] The pressure in each section of the tubular reactor is 0.05~0.1MPa.

[0010] The molar ratio of the carbonyl fluoride to hexafluoropropylene is (1~3):1.

[0011] The preheating temperature is 100~300℃.

[0012] The bulk density of the fluorinated molecular sieve catalyst in the second and third reaction sections is 1.4~2.5 g / cm³. 3 .

[0013] The preparation method of the fluorinated molecular sieve catalyst includes the following steps: (1) Immerse the molecular sieve in an acidic solution for dealumination treatment to selectively remove some aluminum elements from the molecular sieve framework and form vacancies; (2) The molecular sieve treated in step (1) is placed in a reducing gas atmosphere for reduction treatment to remove some of the Al in the molecular sieve framework. 3+ Restore to Al 2+ To enhance the affinity of molecular sieves for fluorine; (3) The molecular sieve treated in step (2) is mixed with a fluorine source and heated to the reaction temperature under an inert atmosphere. The reaction is kept at a constant temperature for a period of time so that the fluorine-containing gas generated by the decomposition of the fluorine source reacts with the molecular sieve framework. The product after the reaction is cooled to room temperature and washed with an alkaline solution to remove residual fluorides. Then it is dried at a drying temperature to obtain the fluorinated molecular sieve catalyst, wherein the fluorine loading is 8~12 wt.%.

[0014] In step (1), the acidic solution is an oxalic acid solution with a concentration of 0.05~0.2mol / L; the temperature for the dealuminization treatment is 60~100℃ and the time for the dealuminization treatment is 1~3h.

[0015] In step (2), the reducing gas is a mixture of H2 and N2, wherein the volume fraction of H2 is 3-8%; the reduction treatment temperature is 350-450℃, and the reduction treatment time is 0.5-2h.

[0016] In step (3), the fluorine source is NH4F, which decomposes into NH3 and HF, and the molecular sieve framework reacts with HF; the mass ratio of molecular sieve to NH4F is 1:(0.1~0.3); the reaction temperature is 400~500℃, and the reaction time is 2~6h.

[0017] In step (3), the alkaline solution is an ammonia solution with a mass fraction of 3-8%; the drying temperature is 100-120℃.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) This invention uses carbonyl fluoride and hexafluoropropylene as gas-phase reaction raw materials, which are readily available and inexpensive. At the same time, it adopts a self-designed tubular reactor to achieve continuous flow reaction, breaking the limitations of traditional processes. Heptafluoroisobutyryl fluoride can be rapidly synthesized through a one-step continuous flow method, eliminating the cumbersome operations such as intermediate product separation and purification. This not only shortens the reaction route and production cycle, but also improves production efficiency and product stability, while reducing equipment investment and operating costs, making it more suitable for the needs of large-scale industrial production. (2) By optimizing reaction parameters and using self-prepared fluorinated molecular sieve catalysts, this invention makes the reaction milder and more efficient; while improving the reaction conversion rate and selectivity, it reduces energy consumption, and ultimately achieves a selectivity of 99.9% for heptafluoroisobutyryl fluoride and a conversion rate of 99.9% for hexafluoropropylene. (3) The heptafluoroisobutyryl fluoride product obtained by the present invention can be quickly and accurately separated from the reaction mixture. The separation process is simple to operate, low in cost and meets environmental protection requirements, providing strong technical support for the industrial production of heptafluoroisobutyryl fluoride. Attached Figure Description

[0019] Figure 1 The image shows a gas chromatogram of heptafluoroisobutyryl fluoride prepared in Example 1. Detailed Implementation

[0020] 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.

[0021] 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.

[0022] Example 1 The preparation method of the fluorinated molecular sieve catalyst includes the following steps: (1) The molecular sieve was immersed in a 0.1 mol / L oxalic acid solution and subjected to a dealumination treatment at 80°C for 2 h to selectively dealude aluminum and form vacancies; (2) The molecular sieve treated in step (1) is placed in a mixed gas atmosphere of H2 and N2 (H2 volume fraction is 5%) and reduced at 400℃ for 1 h to remove part of the Al in the molecular sieve framework. 3+ Restore to Al 2+ ; (3) The molecular sieve treated in step (2) is mixed with NH4F at a mass ratio of 1:0.25. Under N2 atmosphere, the temperature is increased to 500℃ at a rate of 5℃ / min and the reaction is kept at a constant temperature for 4h to allow the HF produced by the decomposition of NH4F to react with the molecular sieve framework. The product after the reaction is cooled to room temperature and washed with a 5% ammonia solution to remove residual fluorides. Then it is dried at 110℃ to obtain a fluorinated molecular sieve catalyst with a fluorine loading of 10wt.%.

[0023] The continuous production process of heptafluoroisobutyryl fluoride is carried out in a tubular reactor, which is divided into a first preheating section, a second reaction section and a third reaction section from the inlet end to the outlet end, and each section is independently temperature controlled. The continuous production process includes the following steps: A fluorinated molecular sieve catalyst with a fluorine loading of 10 wt.% (1.5 kg in total) was loaded into the second and third reaction sections, and the bulk density of the fluorinated molecular sieve catalyst in the second and third reaction sections was controlled to be 1.5 g / cm³. 3The first preheating section, second reaction section, and third reaction section were each heated to 300℃ and purged with nitrogen gas at a pressure of 0.05 MPa for 3 hours. Then, purging was continued for 2 hours with carbonyl fluoride at a pressure of 0.05 MPa. After purging, the first preheating section, second reaction section, and third reaction section were heated to their respective preset temperatures. A mixture of carbonyl fluoride and hexafluoropropylene at a molar ratio of 3:1 was preheated to 150℃ and then introduced into a tubular reactor, flowing sequentially through each section. In the second and third reaction sections, the mixture contacted and reacted with the fluorinated molecular sieve catalyst. The pressure in each section of the tubular reactor was adjusted to 0.1 MPa using a back pressure valve. The gas discharged from the outlet of the tubular reactor was condensed, and the condensate at -10℃ was collected to obtain the heptafluoroisobutyryl fluoride product.

[0024] The temperatures and total residence times of each section of the tubular reactor are as follows: the temperature of the first preheating section is 300℃ and the total residence time is 0.05s; the temperature of the second reaction section is 300℃ and the total residence time is 0.01s; and the temperature of the third reaction section is 300℃ and the total residence time is 0.06s.

[0025] Gas chromatography was used to analyze the heptafluoroisobutyryl fluoride product. The conversion rate of hexafluoropropylene was calculated to be 99.9%, and the selectivity of heptafluoroisobutyryl fluoride was 99.95%.

[0026] Figure 1 Table 1 shows the gas chromatogram of heptafluoroisobutyryl fluoride prepared in Example 1. Figure 1 The corresponding gas chromatography data, combined with Figure 1 Analysis of Table 1 shows that the component with a retention time of 7.087 min in gas chromatography is heptafluoroisobutyryl fluoride, with a peak area percentage as high as 99.9771%.

[0027] Table 1 Figure 1 Gas chromatography data

[0028] Example 2 The difference from Example 1 is that the molar ratio of carbonyl fluoride to hexafluoropropylene is 1:1; the temperature and total residence time of each section of the tubular reactor are as follows: the temperature of the first preheating section is 150°C and the total residence time is 0.01s; the temperature of the second reaction section is 250°C and the total residence time is 0.1s; the temperature of the third reaction section is 300°C and the total residence time is 0.04s.

[0029] The heptafluoroisobutyryl fluoride product was analyzed by gas chromatography. The conversion rate of hexafluoropropylene was calculated to be 99.5%, and the selectivity of heptafluoroisobutyryl fluoride was 99.2%.

[0030] Example 3 The difference from Example 1 is that the molar ratio of carbonyl fluoride to hexafluoropropylene is 1.5:1; the pressure of each section of the tubular reactor is adjusted to 0.05 MPa by the back pressure valve; and the temperature and total residence time of each section of the tubular reactor are as follows: the temperature of the first preheating section is 200°C and the total residence time is 0.05 s; the temperature of the second reaction section is 300°C and the total residence time is 0.04 s; and the temperature of the third reaction section is 250°C and the total residence time is 0.01 s.

[0031] The heptafluoroisobutyryl fluoride product was analyzed by gas chromatography. The conversion rate of hexafluoropropylene was calculated to be 99.9%, and the selectivity of heptafluoroisobutyryl fluoride was 99.6%.

[0032] Example 4 The preparation method of the fluorinated molecular sieve catalyst includes the following steps: (1) The molecular sieve was immersed in a 0.1 mol / L oxalic acid solution and subjected to a dealumination treatment at 80°C for 2 h to selectively dealude aluminum and form vacancies; (2) The molecular sieve treated in step (1) is placed in a mixed gas atmosphere of H2 and N2 (H2 volume fraction is 5%) and reduced at 400℃ for 1 h to remove part of the Al in the molecular sieve framework. 3+ Restore to Al 2+ ; (3) The molecular sieve treated in step (2) is mixed with NH4F at a mass ratio of 1:0.3. Under N2 atmosphere, the temperature is increased to 500℃ at a rate of 5℃ / min and the reaction is kept at a constant temperature for 4h to allow the HF produced by the decomposition of NH4F to react with the molecular sieve framework. The product after the reaction is cooled to room temperature and washed with a 5% ammonia solution to remove residual fluorides. Then it is dried at 110℃ to obtain a fluorinated molecular sieve catalyst with a fluorine loading of 12wt.%.

[0033] The continuous production process of heptafluoroisobutyryl fluoride differs from that in Example 1 in that a fluorinated molecular sieve catalyst with a fluorine loading of 12 wt.% is used; the molar ratio of carbonyl fluoride to hexafluoropropylene is 1.5:1; and the temperature and total residence time of each section of the tubular reactor are as follows: the temperature of the first preheating section is 200°C, and the total residence time is 0.04 s; the temperature of the second reaction section is 250°C, and the total residence time is 0.07 s; and the temperature of the third reaction section is 300°C, and the total residence time is 0.1 s.

[0034] Gas chromatography was used to analyze the heptafluoroisobutyryl fluoride product. The conversion rate of hexafluoropropylene was calculated to be 99.9%, and the selectivity of heptafluoroisobutyryl fluoride was 99.9%.

[0035] Example 5 The preparation method of the fluorinated molecular sieve catalyst includes the following steps: (1) The molecular sieve was immersed in a 0.1 mol / L oxalic acid solution and subjected to a dealumination treatment at 80°C for 2 h to selectively dealude aluminum and form vacancies; (2) The molecular sieve treated in step (1) is placed in a mixed gas atmosphere of H2 and N2 (H2 volume fraction is 5%) and reduced at 400℃ for 1 h to remove part of the Al in the molecular sieve framework. 3+ Restore to Al 2+ ; (3) The molecular sieve treated in step (2) is mixed with NH4F at a mass ratio of 1:0.19. Under N2 atmosphere, the temperature is increased to 500℃ at a rate of 5℃ / min and the reaction is kept at a constant temperature for 4h to allow the HF produced by the decomposition of NH4F to react with the molecular sieve framework. The product after the reaction is cooled to room temperature and washed with a 5% ammonia solution to remove residual fluorides. Then it is dried at 110℃ to obtain a fluorinated molecular sieve catalyst with a fluorine loading of 8wt.%.

[0036] The continuous production process of heptafluoroisobutyryl fluoride differs from that in Example 1 in that a fluorinated molecular sieve catalyst with a fluorine loading of 8 wt.% is used; the molar ratio of carbonyl fluoride to hexafluoropropylene is 2:1; and the temperature and total residence time of each section of the tubular reactor are as follows: the temperature of the first preheating section is 250°C, and the total residence time is 0.05 s; the temperature of the second reaction section is 270°C, and the total residence time is 0.04 s; and the temperature of the third reaction section is 300°C, and the total residence time is 0.1 s.

[0037] Gas chromatography was used to analyze the heptafluoroisobutyryl fluoride product. The conversion rate of hexafluoropropylene was calculated to be 99.7%, and the selectivity of heptafluoroisobutyryl fluoride was 99.4%.

[0038] Comparative Example 1 The difference from Example 1 is that the continuous production process of heptafluoroisobutyryl fluoride is carried out in a single-stage tubular reactor, and the bulk density of the fluorinated molecular sieve catalyst in the single-stage tubular reactor is 1.5 g / cm³. 3 The temperature was 300℃ and the total residence time was 0.07s.

[0039] The heptafluoroisobutyryl fluoride product was analyzed by gas chromatography. Calculations showed that the conversion rate of hexafluoropropylene was 70.7%, and the selectivity of heptafluoroisobutyryl fluoride was 88.4%. This indicates that compared to common single-stage tubular reactors, the three-stage tubular reactor of this invention allows for more complete contact between the catalyst and the reactant gas, effectively improving the yield of heptafluoroisobutyryl fluoride.

[0040] Comparative Example 2 The continuous production process of heptafluoroisobutyryl fluoride differs from that in Example 1 in that it uses a KF / Al2O3 catalyst.

[0041] The preparation method of the KF / Al2O3 catalyst includes the following steps: γ-Al₂O₃ particles with a diameter of 4±1 mm were calcined in a muffle furnace at 500℃ for 3 hours to remove surface adsorbed water and impurities. KF solid was dissolved in deionized water to prepare a saturated KF solution. 3 kg of pretreated γ-Al₂O₃ particles were placed in a covered container, and 3300 mL of the saturated KF solution was slowly added dropwise, ensuring uniform penetration of the liquid into the particle pores and avoiding liquid accumulation between particles. After the addition was complete, the container was sealed and allowed to age at room temperature for 12 hours. The impregnated particles were then dried at 60℃ for 3 hours to prevent rapid evaporation of surface moisture, which could lead to KF agglomeration on the surface. The temperature was then raised to 100℃ and dried for another 5 hours to completely remove internal moisture. Finally, the particles were calcined at 450℃ for 3 hours to allow KF to form stable active species on the particle surface.

[0042] The heptafluoroisobutyryl fluoride product was analyzed by gas chromatography. Calculations showed that the conversion rate of hexafluoropropylene was 81.6%, and the selectivity of heptafluoroisobutyryl fluoride was 92.4%. This indicates that, compared with fluorinated metal catalysts prepared by the conventional impregnation method, the fluorinated molecular sieve catalyst of this invention can more efficiently catalyze the reaction of hexafluoropropylene with carbonyl fluoride to produce heptafluoroisobutyryl fluoride.

[0043] Comparative Example 3 The continuous production process of heptafluoroisobutyryl fluoride differs from that in Example 1 in that it uses a NaF / C catalyst.

[0044] The preparation method of the NaF / C catalyst includes the following steps: The activated carbon particles were repeatedly rinsed with clean water until the effluent was clear to remove surface impurities and dust. NaF solid was dissolved in deionized water to prepare a saturated NaF solution. The pretreated activated carbon particles were then immersed in the NaF saturated solution, ensuring complete immersion. The solution was stirred at room temperature for 6 hours to allow NaF to be fully adsorbed onto the surface and within the pores of the activated carbon particles. The impregnated activated carbon particles were then removed and placed in an oven to dry at 100°C for 8 hours, followed by calcination at 400°C for 4 hours to obtain the NaF / C catalyst.

[0045] The heptafluoroisobutyryl fluoride product was analyzed by gas chromatography. Calculations showed that the conversion rate of hexafluoropropylene was 75.1%, and the selectivity for heptafluoroisobutyryl fluoride was 80.4%. This indicates that, compared to fluorinated metal catalysts prepared by the traditional impregnation method, the fluorinated molecular sieve catalyst of this invention exhibits superior catalytic performance in the reaction of hexafluoropropylene and carbonyl fluoride to produce heptafluoroisobutyryl fluoride.

[0046] Comparative Example 4 The continuous production process of heptafluoroisobutyryl fluoride differs from that in Example 1 in that it uses a CsF / C catalyst.

[0047] The preparation method of the CsF / C catalyst differs from that of Comparative Example 3 in that a saturated solution of solid CsF is used as the impregnation liquid.

[0048] The heptafluoroisobutyryl fluoride product was analyzed by gas chromatography. Calculations showed that the conversion rate of hexafluoropropylene was 75.1%, and the selectivity of heptafluoroisobutyryl fluoride was 80.4%. This indicates that, compared with existing CsF / C catalysts with good catalytic performance, the fluorinated molecular sieve catalyst of this invention can more efficiently catalyze the reaction of hexafluoropropylene with carbonyl fluoride to produce heptafluoroisobutyryl fluoride.

[0049] Comparative Example 5 1.5 kg of fluorinated molecular sieve catalyst with a fluorine loading of 10 wt.% was added to a 15 L reactor. Carbonyl fluoride and hexafluoropropylene with a molar ratio of 1.5:1 were introduced into the reactor for reaction. The reaction temperature was controlled at 85 °C, and the reactor pressure was maintained at 0.1 MPa through a back pressure valve. The reaction was carried out for 10 h. The total feed amount of carbonyl fluoride was 15 mol, and the total feed amount of hexafluoropropylene was 10 mol. After the reaction was completed, the reactor was cooled to -10 °C, and the clear liquid phase was taken for analysis.

[0050] The heptafluoroisobutyryl fluoride product was analyzed by gas chromatography. Calculations showed that the conversion rate of hexafluoropropylene was 86.5%, and the selectivity of heptafluoroisobutyryl fluoride was 91.6%. This indicates that, compared to a batch reactor, the tubular reactor of this invention is more effective in catalyzing the reaction of hexafluoropropylene and carbonyl fluoride to produce heptafluoroisobutyryl fluoride.

Claims

1. A continuous production process of heptafluoroisobutyryl fluoride, characterized by, The continuous production process is carried out in a tubular reactor, which is sequentially divided into a first preheating section, a second reaction section and a third reaction section from an inlet end to an outlet end, and each section is independently temperature-controlled; The continuous production process comprises the following steps: The fluorinated molecular sieve catalyst is loaded in the second reaction section and the third reaction section, the first preheating section, the second reaction section and the third reaction section are heated to corresponding preset temperatures respectively, the mixed and preheated carbonyl fluoride and hexafluoropropene are introduced into the tubular reactor, and the gas discharged from the outlet end of the tubular reactor is condensed to obtain the heptafluoroisobutyryl fluoride product.

2. The continuous production process of heptafluoroacetyl fluoride according to claim 1, characterized in that, The temperature and total residence time of each section of the tubular reactor are as follows: the temperature of the first preheating section is 100-300℃, and the total residence time is 0.01-0.1s; the temperature of the second reaction section is 150-350℃, and the total residence time is 0.01-0.1s; The temperature of the third reaction section is 200-300℃, and the total residence time is 0.01-0.1s.

3. The continuous production process of heptafluoroacetyl fluoride according to claim 1, characterized in that, The pressure of each section of the tubular reactor is 0.05-0.1MPa.

4. The continuous production process of heptafluoroacetyl fluoride according to claim 1, characterized in that, The molar ratio of carbonyl fluoride to hexafluoropropene is (1-3):

1.

5. The continuous production process of heptafluoroacetyl fluoride according to claim 1, characterized in that, The preheating temperature is 100-300℃.

6. The continuous production process of heptafluoroacetyl fluoride according to claim 1, characterized in that, The bulk density of the fluorinated molecular sieve catalyst in the second reaction section and the third reaction section is 1.4-2.5 g / cm 3 .

7. The continuous production process of heptafluoroacetyl fluoride according to claim 1, characterized in that, The preparation method of the fluorinated molecular sieve catalyst comprises the following steps: (1) The molecular sieve is immersed in an acid solution for dealumination treatment; (2) The molecular sieve treated in step (1) is placed in a reducing gas atmosphere for reduction treatment; (3) The molecular sieve treated in step (2) is mixed with a fluorine source and reacted in an inert atmosphere, and the product after reaction is washed and dried to obtain the fluorinated molecular sieve catalyst.

8. The continuous production process of heptafluoroacetyl fluoride according to claim 7, characterized in that, In step (1), the acid solution is oxalic acid solution, and the concentration is 0.05-0.2mol / L; the dealumination treatment temperature is 60-100℃, and the dealumination treatment time is 1-3h.

9. The continuous production process of heptafluoroacetyl fluoride according to claim 7, characterized in that, In step (2), the reducing gas is a mixed gas of H2 and N2, wherein the volume fraction of H2 is 3-8%; the reduction treatment temperature is 350-450℃, and the reduction treatment time is 0.5-2h.

10. The continuous production process of heptafluoroacetyl fluoride according to claim 7, characterized in that, In step (3), the fluorine source is NH4F, and the mass ratio of the molecular sieve to NH4F is 1:(0.1-0.3); the reaction temperature is 400-500℃, and the reaction time is 2-6h.

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