Continuous process for the production of heptafluoroisobutyryl fluoride

Abstract

The application 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, which is divided into a first preheating section, a second reaction section and a third reaction section. Fluorinated molecular sieve catalyst is loaded in the second reaction section and the third reaction section, each reaction section is heated to a corresponding preset temperature, mixed and preheated carbonyl fluoride and hexafluoropropene are introduced into the tubular reactor, and flow through each section of the tubular reactor in sequence, and react with the fluorinated molecular sieve catalyst in the second reaction section and the third reaction section. The gas discharged from the outlet end of the tubular reactor is condensed to obtain heptafluoroisobutyryl fluoride product. The process uses carbonyl fluoride and hexafluoropropene as the gas phase reaction raw material, and synthesizes heptafluoroisobutyryl fluoride by 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] The application belongs to the technical field of fluorinated chemicals, and particularly relates to a continuous production process of heptafluoroisobutyryl fluoride. BACKGROUND

[0002] Heptafluoroisobutyryl fluoride is an important fluorine-containing compound, which is toxic, has weak odor and is easy to liquefy. It is widely used in electronic industry cleaning agents, etchants, pesticide intermediates, fluorine-containing material monomers, etc. The preparation methods of heptafluoroisobutyryl fluoride mainly include electrochemical method (electrolytic fluorination method) and chemical synthesis method (acyl fluoride addition method, oxidative cleavage method). Among them, the electrochemical method has problems of many side reactions, low yield of main products and high energy consumption; the chemical synthesis method usually uses a batch reaction kettle for synthesis, which is simple to operate, but the one-pot method often has low yield and is accompanied by difficult-to-separate byproducts such as fluorine-containing ketones.

[0003] Chinese patent CN107935884A discloses a preparation method of acyl fluoride. In the presence of alkali metal fluoride and a cosolvent, the addition reaction of perfluoroalkene R1R2C=CR3R4 and carbonyl fluoride is carried out to obtain acyl fluoride R1R2(COF)C-CFR3R4. After the reaction is completed, the alkali metal fluoride and the cosolvent are not easy to recover and separate.

[0004] Chinese patent CN110734373A discloses a method for preparing heptafluoroisobutyryl fluoride by a reaction kettle liquid phase method. Hexafluoropropylene and carbonyl fluoride are used as raw materials, and 2-perfluoroalkyl benzothiazole compounds are used as catalysts. The catalyst is not easy to obtain, and the preparation cost is high.

[0005] Chinese patent CN109651131A discloses a method for preparing heptafluoroisobutyryl fluoride from hexafluoropropylene dimer. In the presence of a catalyst, heptafluoroisobutyryl fluoride is prepared from oxygen and hexafluoropropylene dimer. In the method, the oxidation process of oxygen needs to be carried out at high temperature, which has safety hazards.

[0006] Therefore, there is an urgent need for a method for continuously preparing heptafluoroisobutyryl fluoride, which is efficient in reaction, simple in process and suitable for industrial production. SUMMARY

[0007] In view of the deficiencies of the prior art, the purpose of the present application is to provide a continuous production process of heptafluoroisobutyryl fluoride. Carbonyl fluoride and hexafluoropropylene are used as gas phase reaction raw materials, and heptafluoroisobutyryl fluoride is synthesized by one-step continuous flow rapid reaction. The reaction route is short, the reaction conversion rate and selectivity are high, and the industrialized large-scale production is easy to realize.

[0008] The technical scheme adopted by the present application is as follows:

[0009] The continuous production process of heptafluoroisobutyryl fluoride is carried out in a tubular reactor, the tubular reactor 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.

[0010] The continuous production process comprises the following steps:

[0011] 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 hexafluoropropylene are introduced into the tubular reactor and flow through each section of the tubular reactor in sequence, react with the fluorinated molecular sieve catalyst in the second reaction section and the third reaction section, and the gas discharged from the outlet end of the tubular reactor is condensed to obtain heptafluoroisobutyryl fluoride product.

[0012] 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.

[0013] The pressure of each section of the tubular reactor is 0.05-0.1MPa.

[0014] The molar ratio of carbonyl fluoride to hexafluoropropylene is (1-3):1.

[0015] The preheating temperature is 100-300℃.

[0016] The bulk density of the fluorinated molecular sieve catalyst in the second reaction section and the third reaction section is 1.4-2.5g / cm 3 .

[0017] The preparation method of the fluorinated molecular sieve catalyst comprises the following steps:

[0018] (1) The molecular sieve is immersed in an acid solution for dealumination treatment to selectively remove part of the aluminum elements in the molecular sieve framework to form vacancies;

[0019] (2) The molecular sieve treated in step (1) is placed in a reducing gas atmosphere for reduction treatment to reduce part of the Al 3+ in the molecular sieve framework to Al 2+ to enhance the affinity of the molecular sieve for fluorine;

[0020] (3) mixing the molecular sieve treated in step (2) with a fluorine source, under an inert atmosphere, heating to a reaction temperature, constant temperature reaction 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, cooling the product after reaction to room temperature, washing the product after reaction with an alkaline solution to remove residual fluoride, and then drying at a drying temperature to obtain a fluorinated molecular sieve catalyst, wherein the fluorine loading is 8-12 wt.%.

[0021] In step (1), the acid solution is oxalic acid solution, the concentration is 0.05-0.2 mol / L; the temperature of dealumination treatment is 60-100℃, and the time of dealumination treatment is 1-3h.

[0022] In step (2), the reducing gas is a mixture of H2 and N2, wherein the volume fraction of H2 is 3-8%; the temperature of reduction treatment is 350-450℃, and the time of reduction treatment is 0.5-2h.

[0023] In step (3), the fluorine source is NH4F, NH4F is decomposed 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.

[0024] In step (3), the alkaline solution is an ammonia solution, the mass fraction is 3-8%; the drying temperature is 100-120℃.

[0025] Compared with the prior art, the beneficial effects of the present application are as follows:

[0026] (1) The present application selects carbonyl fluoride and hexafluoropropylene as the gas phase reaction raw materials, which are easy to obtain and low in cost; at the same time, a self-designed tubular reactor is used to realize continuous flow reaction, breaking the limitation of traditional process. Seven fluorinated isobutyryl fluoride can be quickly synthesized by one-step continuous flow, which saves the tedious operation of intermediate product separation and purification, not only shortens the reaction route and production cycle, but also improves the production efficiency and product stability, reduces the equipment investment and operation cost, and is more suitable for industrial large-scale production demand;

[0027] (2) The present application optimizes the reaction parameters and matches the self-prepared fluorinated molecular sieve catalyst to make the reaction more mild and efficient; while improving the reaction conversion rate and selectivity, the energy consumption is reduced, and finally the selectivity of seven fluorinated isobutyryl fluoride can reach 99.9%, and the conversion rate of hexafluoropropylene can reach 99.9%;

[0028] (3) The heptafluoroisobutyryl fluoride product prepared by the method can be quickly and accurately separated from the reaction mixture, and the separation process is simple in operation, low in cost and in line with environmental protection requirements, thereby providing strong technical support for the industrial production of heptafluoroisobutyryl fluoride. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 Gas chromatogram of heptafluoroisobutyryl fluoride prepared in Example 1. DETAILED DESCRIPTION

[0030] The application will be further described in conjunction with the following examples, but the examples do not limit the implementation of the application.

[0031] The raw materials used in the examples and comparative examples are conventional commercially available raw materials unless otherwise specified, and the process methods used in the examples and comparative examples are conventional methods in the art unless otherwise specified.

[0032] Example 1

[0033] The preparation method of the fluorinated molecular sieve catalyst comprises the following steps:

[0034] (1) The molecular sieve is immersed in an oxalic acid solution with a concentration of 0.1 mol / L, and is subjected to dealumination treatment at 80℃ for 2h to selectively remove aluminum and form vacancies;

[0035] (2) The molecular sieve treated in step (1) is placed in a mixed gas of H2 and N2 (the volume fraction of H2 is 5%) and is subjected to reduction treatment at 400℃ for 1h to reduce part of Al 3+ in the molecular sieve framework to Al 2+ ;

[0036] (3) The molecular sieve treated in step (2) is mixed with NH4F at a mass ratio of 1:0.25, and is heated to 500℃ at a rate of 5℃ / min under N2 atmosphere, and is reacted for 4h to make HF produced by the decomposition of NH4F react with the molecular sieve framework, and then the product after reaction is cooled to room temperature, washed with an ammonia water solution with a mass fraction of 5% to remove residual fluorine, and then dried at 110℃ to obtain a fluorinated molecular sieve catalyst with a fluorine loading of 10wt.%.

[0037] The continuous production process of heptafluoroisobutyryl fluoride is carried out in a tubular reactor, and the tubular reactor is sequentially 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.

[0038] The continuous production process comprises the following steps:

[0039] 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. 3 The 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.

[0040] 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.

[0041] 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%.

[0042] 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%.

[0043] Table 1 Figure 1 Gas chromatography data

[0044]

[0045] Example 2

[0046] 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.

[0047] The product of heptafluoroisobutyryl fluoride is analyzed by using a gas chromatograph, and the conversion rate of hexafluoropropylene is calculated to be 99.5%, and the selectivity of heptafluoroisobutyryl fluoride is calculated to be 99.2%.

[0048] Example 3

[0049] 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 a back pressure valve; 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℃, and the total residence time is 0.05s; the temperature of the second reaction section is 300℃, and the total residence time is 0.04s; the temperature of the third reaction section is 250℃, and the total residence time is 0.01s.

[0050] The product of heptafluoroisobutyryl fluoride is analyzed by using a gas chromatograph, and the conversion rate of hexafluoropropylene is calculated to be 99.9%, and the selectivity of heptafluoroisobutyryl fluoride is calculated to be 99.6%.

[0051] Example 4

[0052] The preparation method of the fluorinated molecular sieve catalyst comprises the following steps:

[0053] (1) The molecular sieve is immersed in an oxalic acid solution with a concentration of 0.1 mol / L, and is subjected to dealumination treatment at 80℃ for 2h to selectively remove aluminum and form vacancies;

[0054] (2) The molecular sieve treated in step (1) is placed in a mixed gas of H2 and N2 (the volume fraction of H2 is 5%) and is subjected to reduction treatment at 400℃ for 1h to reduce part of Al 3+ in the framework of the molecular sieve to Al 2+ ;

[0055] (3) The molecular sieve treated in step (2) is mixed with NH4F at a mass ratio of 1:0.3, and is heated to 500℃ at a rate of 5℃ / min under N2 atmosphere, and is reacted for 4h at constant temperature to make HF produced by the decomposition of NH4F react with the framework of the molecular sieve; the product after reaction is cooled to room temperature, and is washed with an ammonia water solution with a mass fraction of 5% to remove residual fluorine, and then is dried at 110℃ to obtain a fluorinated molecular sieve catalyst with a fluorine loading of 12wt.%.

[0056] The continuous production process of heptafluoroisobutyryl fluoride is different from that of Example 1 in that the fluorinated molecular sieve catalyst with a fluorine loading of 12wt.% is used; the molar ratio of carbonyl fluoride to hexafluoropropene 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℃, and the total residence time is 0.04s; the temperature of the second reaction section is 250℃, and the total residence time is 0.07s; and the temperature of the third reaction section is 300℃, and the total residence time is 0.1s.

[0057] The product of heptafluoroisobutyryl fluoride is analyzed by using a gas chromatograph, and it is calculated that the conversion rate of hexafluoropropene is 99.9%, and the selectivity of heptafluoroisobutyryl fluoride is 99.9%.

[0058] Example 5

[0059] The preparation method of the fluorinated molecular sieve catalyst comprises the following steps:

[0060] (1) The molecular sieve is immersed in an oxalic acid solution with a concentration of 0.1mol / L, and is subjected to dealumination treatment at 80℃ for 2h to selectively remove aluminum and form vacancies;

[0061] (2) The molecular sieve treated in step (1) is placed in a mixed gas of H2 and N2 (the volume fraction of H2 is 5%) and is subjected to reduction treatment at 400℃ for 1h to reduce part of Al 3+ in the framework of the molecular sieve to Al 2+ ;

[0062] (3) The molecular sieve treated in step (2) is mixed with NH4F at a mass ratio of 1:0.19, and is heated to 500℃ at a rate of 5℃ / min under N2 atmosphere, and is reacted for 4h at constant temperature to make HF produced by the decomposition of NH4F react with the framework of the molecular sieve. The product after reaction is cooled to room temperature, washed with an ammonia water solution with a mass fraction of 5% to remove residual fluoride, and then dried at 110℃ to obtain a fluorinated molecular sieve catalyst with a fluorine loading of 8wt.%.

[0063] The continuous production process of heptafluoroisobutyryl fluoride is different from that of Example 1 in that the fluorinated molecular sieve catalyst with a fluorine loading of 8wt.% is used; the molar ratio of carbonyl fluoride to hexafluoropropene 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℃, and the total residence time is 0.05s; the temperature of the second reaction section is 270℃, and the total residence time is 0.04s; and the temperature of the third reaction section is 300℃, and the total residence time is 0.1s.

[0064] The product of heptafluoroisobutyryl fluoride is analyzed by using a gas chromatograph, and through calculation, the conversion rate of hexafluoropropylene is 99.7%, and the selectivity of heptafluoroisobutyryl fluoride is 99.4%.

[0065] Comparative Example 1

[0066] 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 / cm 3 ; the temperature is 300℃, and the total residence time is 0.07s.

[0067] The product of heptafluoroisobutyryl fluoride is analyzed by using a gas chromatograph, and through calculation, the conversion rate of hexafluoropropylene is 70.7%, and the selectivity of heptafluoroisobutyryl fluoride is 88.4%. This shows that compared with the common single-stage tubular reactor, the three-stage tubular reactor of the present application can make the catalyst and the reaction gas more fully contact, effectively improving the yield of heptafluoroisobutyryl fluoride.

[0068] Comparative Example 2

[0069] The difference from Example 1 is that the continuous production process of heptafluoroisobutyryl fluoride uses KF / Al2O3 catalyst.

[0070] The preparation method of the KF / Al2O3 catalyst comprises the following steps:

[0071] γ-Al2O3 particles with a particle size of 4±1mm are calcined in a muffle furnace at 500℃ for 3h to remove surface adsorbed water and impurities. KF solid is dissolved in deionized water to prepare a KF saturated solution. 3kg of pretreated γ-Al2O3 particles are placed in a container with a lid, and 3300mL of KF saturated solution is slowly added dropwise to ensure that the liquid penetrates uniformly into the particle pores, avoiding the accumulation of liquid between particles. After the dropwise addition is completed, the container is sealed and aged at room temperature for 12h. The impregnated particles are dried at 60℃ for 3h to prevent the rapid evaporation of water on the surface of the particles, which can cause KF to agglomerate on the surface. Then the temperature is increased to 100℃ for further drying for 5h to completely remove the internal moisture. Finally, the particles are calcined at 450℃ for 3h to form a stable active species of KF on the surface of the particles.

[0072] The product of heptafluoroisobutyryl fluoride is analyzed by using a gas chromatograph, and through calculation, the conversion rate of hexafluoropropylene is 81.6%, and the selectivity of heptafluoroisobutyryl fluoride is 92.4%. This shows that compared with the fluorinated metal catalyst prepared by the traditional impregnation method, the fluorinated molecular sieve catalyst of the present application can more efficiently catalyze the reaction of hexafluoropropylene and carbonyl fluoride to generate heptafluoroisobutyryl fluoride.

[0073] Comparative Example 3

[0074] The continuous production process of heptafluoroisobutyryl fluoride is different from that of example 1 in that a NaF / C catalyst is used.

[0075] The preparation method of the NaF / C catalyst comprises the following steps:

[0076] The activated carbon particles are repeatedly washed with clean water until the effluent is clear, so as to remove impurities and dust on the surface. NaF solid is dissolved in deionized water to prepare a NaF saturated solution. The pretreated activated carbon particles are put into the NaF saturated solution, and the particles are completely immersed. The NaF is fully adsorbed on the surface and pores of the activated carbon particles by stirring at room temperature for 6 hours. The impregnated activated carbon particles are taken out and dried in an oven at 100 DEG C for 8 hours, and then calcined at 400 DEG C for 4 hours to obtain the NaF / C catalyst.

[0077] The heptafluoroisobutyryl fluoride product is analyzed by using a gas chromatograph, and the conversion rate of hexafluoropropylene is 75.1% and the selectivity of heptafluoroisobutyryl fluoride is 80.4% by calculation. This shows that, compared with the fluorinated metal catalyst prepared by using the traditional impregnation method, the fluorinated molecular sieve catalyst of the present application exhibits better catalytic performance in the reaction of hexafluoropropylene and carbonyl fluoride to generate heptafluoroisobutyryl fluoride.

[0078] Comparative example 4

[0079] The continuous production process of heptafluoroisobutyryl fluoride is different from that of example 1 in that a CsF / C catalyst is used.

[0080] The preparation method of the CsF / C catalyst is different from that of comparative example 3 in that a CsF solid is used to prepare a saturated solution as an impregnation liquid.

[0081] The heptafluoroisobutyryl fluoride product is analyzed by using a gas chromatograph, and the conversion rate of hexafluoropropylene is 75.1% and the selectivity of heptafluoroisobutyryl fluoride is 80.4% by calculation. This shows that, compared with the fluorinated metal catalyst prepared by using the traditional impregnation method, the fluorinated molecular sieve catalyst of the present application exhibits better catalytic performance in the reaction of hexafluoropropylene and carbonyl fluoride to generate heptafluoroisobutyryl fluoride.

[0082] Comparative example 5

[0083] Into a 15L reaction kettle, 1.5kg of fluorinated molecular sieve catalyst with a fluorine loading of 10wt.% is added, and carbonyl fluoride and hexafluoropropylene with a molar ratio of 1.5:1 are introduced into the reaction kettle for reaction, the reaction temperature is controlled at 85 DEG C, and the pressure of the reaction kettle is maintained at 0.1MPa by a back pressure valve. The total amount of carbonyl fluoride is 15mol, and the total amount of hexafluoropropylene is 10mol. After 10h of reaction, the reaction kettle is cooled to-10 DEG C, and the supernatant is taken out for detection.

[0084] The product heptafluoroisobutyryl fluoride is analyzed by using a gas chromatograph, and conversion of hexafluoropropylene is 86.5% and selectivity of heptafluoroisobutyryl fluoride is 91.6% by calculation. This shows that compared with a kettle type reactor, the tube type reactor of the application has better effect in the reaction of catalyzing hexafluoropropylene and carbonyl fluoride to generate 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 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. 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. 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 NH4F, and the reaction is carried out under an inert atmosphere, and the product after the reaction is washed and dried to obtain the fluorinated molecular sieve catalyst.

2. 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.

3. 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.

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

5. 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 .

6. The continuous production process of heptafluoroacetyl fluoride according to claim 1, 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.

7. The continuous production process of heptafluoroacetyl fluoride according to claim 1, 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.

8. The continuous production process of heptafluoroacetyl fluoride according to claim 1, characterized in that, In step (3), 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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