Catalytic synthesis method of octafluorocyclopentene

Abstract

The invention belongs to the technical field of octafluorocyclopentene gas preparation, and particularly relates to a catalytic synthesis method of octafluorocyclopentene. The method specifically comprises the following step: under the action of a fluorine-chlorine catalyst, carrying out gas-phase catalytic fluorination reaction on 1-chloroheptafluorocyclopentene and anhydrous hydrogen fluoride at 80-120 DEG C to obtain octafluorocyclopentene. The preparation method of the fluorine-chlorine catalyst comprises the following steps: dissolving metal chloride in water, adding a precipitant, and fully stirring for reaction to obtain slurry; filtering the slurry to remove filtrate to obtain a solid, and washing the solid with deionized water until the solid is neutral; adding aluminum nitrate into the washed solid, fully stirring and drying to obtain a precursor of the catalyst; and performing compression molding on the precursor of the catalyst, roasting, and activating to obtain the fluorine-chlorine catalyst. The method is mild in reaction condition and high in catalytic efficiency.

Description

Technical Field

[0001] This application belongs to the technical field of octafluorocyclopentene gas preparation, and specifically relates to a catalytic synthesis method of octafluorocyclopentene. Background Art

[0002] Octafluorocyclopentene is an unsaturated perfluoroolefin with an ozone depletion potential (ODP) of 0, a global warming potential (GWP100) of 78.1, and an atmospheric lifetime of 1.1 years. As a new type of perfluorochemical, it is mainly used as an etching gas and cleaning agent for semiconductors, and is also regarded as a key fluorine-containing building block for preparing organic photochromic materials. Due to its excellent environmental and working properties, octafluorocyclopentene has received increasing attention in the fields of integrated circuits and the like, and thus has huge potential market demand and good development prospects.

[0003] Currently, the synthesis routes of octafluorocyclopentene can be roughly divided into two according to the phase state of the raw materials:

[0004] The first route is the liquid-phase fluorination method with a relatively high yield. However, the liquid-phase fluorination method requires the use of a large amount of solvents, and the excess fluorination reagents and reaction solvents are difficult to recycle, generating a large amount of waste liquid, which will cause serious pollution to the environment. For example, the patent with publication number WO2018235566A1 discloses a production method of octafluorocyclopentene, including a raw material heating step of heating 1-chloroheptafluorocyclopentene to above 40°C and below 55°C; and a fluorination step of maintaining a suspension containing an aprotic polar solvent and an alkaline earth metal fluoride at above 85°C while supplying the heated 1-chloroheptafluorocyclopentene to the suspension to obtain octafluorocyclopentene, and a relatively large amount of solvents are used in the whole reaction process.

[0005] The second route is to synthesize octafluorocyclopentene by gas-phase fluorination, but the yield and productivity are low, and the reaction conditions are relatively high, which is not suitable for industrialization, and there are deficiencies in the selection of catalysts. Subsequently, researchers improved the catalysts, and to a certain extent, the yield of the product and the conversion rate of the reactants were increased. For example, the Chinese patent with publication number CN107188778B discloses a preparation method of octafluorocyclopentene, in which 1-chloroheptafluorocyclopentene and anhydrous hydrogen fluoride are used as raw materials to carry out a gas-phase catalytic fluorine-chlorine exchange reaction at 280-400°C to obtain the product octafluorocyclopentene, and the selected catalyst is a composition of a compound containing one or more of the metal elements Zn, Co, Ni, Ge, In and chromium oxide. However, the reaction temperature is relatively high. Under relatively high temperature conditions, the substances in the reaction system are in a relatively high reaction activity, which is likely to cause some side reactions, resulting in a decrease in the yield of the target product.

[0006] In summary, in the existing reactions for preparing octafluorocyclopentene, the liquid-phase fluorination method requires a large amount of solvents. The excess fluorination reagents and reaction solvents are difficult to recycle, generating a large amount of waste liquid, which will cause serious pollution to the environment. The gas-phase fluorination method has low yields and reaction rates, and requires relatively high reaction conditions. Therefore, there is an urgent need to propose a catalytic synthesis method for octafluorocyclopentene to solve the current problems. Summary of the Invention

[0007] In the existing reactions for preparing octafluorocyclopentene, the liquid-phase fluorination method requires a large amount of solvents. The excess fluorination reagents and reaction solvents are difficult to recycle, generating a large amount of waste liquid, which will cause serious pollution to the environment. The gas-phase fluorination method has low yields and reaction rates, and requires relatively high reaction conditions. This application proposes a catalytic synthesis method for octafluorocyclopentene to solve the current problems.

[0008] The specific solution of this application is as follows:

[0009] A catalytic synthesis method for octafluorocyclopentene, in which, under the action of a fluorine-chlorine catalyst, 1-chloroheptafluorocyclopentene and anhydrous hydrogen fluoride undergo a gas-phase catalytic fluorination reaction at 80°C to 120°C to obtain octafluorocyclopentene.

[0010] Preferably, the preparation method of the fluorine-chlorine catalyst is as follows:

[0011] Step S1. Dissolve a metal chloride in water, add a precipitant, and fully stir and react to obtain a slurry;

[0012] Step S2. Filter the slurry to remove the filtrate to obtain a solid, and wash the solid with deionized water until it is neutral;

[0013] Step S3. Add an aluminum nitrate solution to the washed solid, fully stir and dry to obtain a catalyst precursor;

[0014] Step S4. Press the catalyst precursor into a mold, and perform activation after calcination to obtain the fluorine-chlorine catalyst.

[0015] Preferably, in Step S1, the metal chloride is an alkaline earth metal chloride or a transition metal chloride, and 20 ml of water is added per 1 g of the metal chloride.

[0016] Preferably, in Step S1, the alkaline earth metal chloride is barium chloride, and the transition metal chloride is zinc chloride.

[0017] Preferably, the precipitant in Step S1 is ammonia water, and ammonia water is added until the pH value of the solution is 7.5 to 8, and the reaction temperature is 60°C.

[0018] Preferably, the concentration of the aluminum nitrate solution in Step S3 is 3 to 4 M, and 50 mL of the aluminum nitrate solution is added per 1 g of the washed solid.

[0019] Preferably, the stirring time in step S3 is 2 h, and the drying condition is drying at 150 °C for 12 h.

[0020] Preferably, the calcination condition in step S4 is calcination at 450 °C for 10 h under a nitrogen atmosphere; the activation condition is activation with a mixed gas composed of hydrogen fluoride and hydrogen with a molar ratio of 10:1 at 300 °C for 10 h.

[0021] Preferably, the carrier of the catalyst is γ-aluminum oxide, and the loading condition is calcination at 400-500 °C for 0.5-1.5 h.

[0022] Preferably, the reaction pressure of the gas-phase catalytic fluorination reaction is 0.1-0.5 MPa, the molar ratio of 1-chloroheptafluorocyclopentene to anhydrous hydrogen fluoride is 1:(5-15), the contact time is 30 s, the flow rate after mixing the two gases of 1-chloroheptafluorocyclopentene and anhydrous hydrogen fluoride is 0.5-15 m / s, and the addition amount of the fluorine-chlorine catalyst is 1-2 g.

[0023] The beneficial effects of this application are as follows:

[0024] (1) The catalyst prepared by this application has high activity: This application introduces transition metal zinc or alkaline earth metal barium. The introduction of transition zinc ions forms structural defect sites on the surface of γ-Al2O3 through lattice doping, increasing the specific surface area of the carrier and the average pore diameter at the same time. The densified pore structure promotes the formation of highly dispersed nanoscale active centers of the active components on the surface of the carrier, effectively inhibiting the sintering and agglomeration of metal particles and enhancing the redox cycle efficiency of the catalytic fluorine-chlorine exchange reaction. As an alkaline earth metal, barium has the advantages of high Lewis acidity and open metal sites, making its catalyst have a high specific surface area. In the gas-phase catalytic fluorination reaction, it can effectively promote the reaction of 1-chloroheptafluorocyclopentene with anhydrous hydrogen fluoride, increase the reaction rate, and enable the reaction to proceed at a relatively low temperature (80 °C - 120 °C), thereby reducing energy consumption.

[0025] (2) The catalyst of this application has strong stability: After high-temperature calcination and activation treatment, the catalyst has good thermal stability and chemical stability. During the reaction process, the catalyst can maintain the stability of its activity and structure for a long time, and is not prone to phenomena such as sintering, poisoning, or deactivation, thereby extending the service life of the catalyst and reducing production costs.

[0026] (3) The reaction conditions of this application are mild: This catalyst can catalyze the reaction of 1-chloroheptafluorocyclopentene with anhydrous hydrogen fluoride at a relatively low temperature of 80 °C - 120 °C. Compared with some reactions that require higher temperatures or more stringent conditions, this helps to reduce energy consumption and improve the economy of the reaction. Specific embodiments

[0027] To further elaborate on the technical means and effects adopted by this application to achieve the intended invention purpose, the following, in conjunction with preferred embodiments, details the specific implementation manners, structures, features, and their effects according to this application as follows.

[0028] To achieve the purpose of this application, 1-chloroheptafluorocyclopentene (F7-1) is used as a raw material, and with a catalyst, octafluorocyclopentene (F8E) is prepared through a gas-phase fluorination reaction. The main reactions that occur are as follows:

[0029]

[0030] Catalyst Preparation Examples

[0031] Preparation Example 1

[0032] Step S1. Take 5 g of zinc chloride and dissolve it in 150 mL of water with stirring. Then add ammonia water and continuously add ammonia water until the pH value of the solution reaches 7.5. At the same time, control the reaction temperature at 60 °C and fully stir the reaction under this condition to obtain a slurry.

[0033] Step S2. Perform a filtration operation on the obtained slurry to remove the filtrate, thereby obtaining a solid substance. Wash the solid with deionized water until it is neutral.

[0034] Step S3. Add aluminum nitrate to the washed solid, where the concentration of aluminum nitrate is 4 M. Add 1 g of the washed solid for every 50 mL of aluminum nitrate, stir for 2 h, and dry the mixture at 150 °C for 12 h to obtain a catalyst precursor.

[0035] Step S4. Press the catalyst precursor into a mold, and then perform a calcination treatment. Calcinate it at 450 °C for 10 h in a nitrogen atmosphere. After the calcination is completed, perform an activation operation. At 300 °C, activate it for 10 h using a mixed gas composed of hydrogen fluoride and hydrogen with a molar ratio of 10:1. Finally, obtain a fluorochloride catalyst. At 450 °C, the calcination time is 1 h, and load the fluorochloride catalyst onto γ-aluminum oxide.

[0036] Preparation Example 2

[0037] The distinguishing feature of this preparation example from Preparation Example 1 is that barium chloride is selected, and the pH value of the solution is 8; the concentration of aluminum nitrate is 3 M; at 400 °C, the calcination time is 1.5 h, and load the fluorochloride catalyst onto γ-aluminum oxide.

[0038] Preparation Example 3

[0039] The distinguishing feature of this preparation example from Preparation Example 1 is that the concentration of aluminum nitrate is 3.5 M; at 500 °C, the calcination time is 0.5 h, and load the fluorochloride catalyst onto γ-aluminum oxide.

[0040] Example 1

[0041] The catalyst prepared in Preparation Example 1 was selected, and the conditions for the gas-phase catalytic fluorine-chlorine exchange reaction were as follows: the reaction pressure was 0.1 MPa, the reaction temperature was 80 °C, the molar ratio of 1-chloroheptafluorocyclopentene to anhydrous hydrogen fluoride was 1:5, the contact time was 30 s, the flow rate after mixing the two gases of 1-chloroheptafluorocyclopentene and anhydrous hydrogen fluoride was 10 m / s, and the addition amount of the fluorine-chlorine catalyst was 1.5 g.

[0042] Example 2

[0043] The catalyst prepared in Preparation Example 1 was selected, and the conditions for the gas-phase catalytic fluorine-chlorine exchange reaction were as follows: the reaction pressure was 0.2 MPa, the reaction temperature was 90 °C, the molar ratio of 1-chloroheptafluorocyclopentene to anhydrous hydrogen fluoride was 1:5.5, the contact time was 30 s, the flow rate after mixing the two gases of 1-chloroheptafluorocyclopentene and anhydrous hydrogen fluoride was 0.5 m / s, and the addition amount of the fluorine-chlorine catalyst was 1 g.

[0044] Example 3

[0045] The catalyst prepared in Preparation Example 1 was selected, and the conditions for the gas-phase catalytic fluorine-chlorine exchange reaction were as follows: the reaction pressure was 0.3 MPa, the reaction temperature was 100 °C, the molar ratio of 1-chloroheptafluorocyclopentene to anhydrous hydrogen fluoride was 1:6, the contact time was 30 s, the flow rate after mixing the two gases of 1-chloroheptafluorocyclopentene and anhydrous hydrogen fluoride was 3 m / s, and the addition amount of the fluorine-chlorine catalyst was 1.8 g.

[0046] Example 4

[0047] The catalyst prepared in Preparation Example 1 was selected, and the conditions for the gas-phase catalytic fluorine-chlorine exchange reaction were as follows: the reaction pressure was 0.4 MPa, the reaction temperature was 110 °C, the molar ratio of 1-chloroheptafluorocyclopentene to anhydrous hydrogen fluoride was 1:7, the contact time was 30 s, the flow rate after mixing the two gases of 1-chloroheptafluorocyclopentene and anhydrous hydrogen fluoride was 5 m / s, and the addition amount of the fluorine-chlorine catalyst was 2 g.

[0048] Example 5

[0049] The catalyst prepared in Preparation Example 1 was selected, and the conditions for the gas-phase catalytic fluorine-chlorine exchange reaction were as follows: the reaction pressure was 0.5 MPa, the reaction temperature was 120 °C, the molar ratio of 1-chloroheptafluorocyclopentene to anhydrous hydrogen fluoride was 1:8, the contact time was 30 s, the flow rate after mixing the two gases of 1-chloroheptafluorocyclopentene and anhydrous hydrogen fluoride was 8 m / s, and the addition amount of the fluorine-chlorine catalyst was 1.7 g.

[0050] Example 6

[0051] The catalyst prepared in Preparation Example 2 was selected, and the conditions for the gas-phase catalytic fluorine-chlorine exchange reaction were as follows: the reaction pressure was 0.1 MPa, the reaction temperature was 80 °C, the molar ratio of 1-chloroheptafluorocyclopentene to anhydrous hydrogen fluoride was 1:10, the contact time was 30 s, the flow rate after mixing the two gases of 1-chloroheptafluorocyclopentene and anhydrous hydrogen fluoride was 9 m / s, and the addition amount of the fluorine-chlorine catalyst was 1.5 g.

[0052] Example 7

[0053] The catalyst prepared in Preparation Example 3 was selected, and the conditions for the gas-phase catalytic fluorine-chlorine exchange reaction were as follows: the reaction pressure was 0.2 MPa, the reaction temperature was 90 °C, the molar ratio of 1-chloroheptafluorocyclopentene to anhydrous hydrogen fluoride was 1:11, the contact time was 30 s, the flow rate after mixing the two gases of 1-chloroheptafluorocyclopentene and anhydrous hydrogen fluoride was 12 m / s, and the addition amount of the fluorine-chlorine catalyst was 1.6 g.

[0054] Example 8

[0055] The catalyst prepared in Preparation Example 2 was selected, and the conditions for the gas-phase catalytic fluorine-chlorine exchange reaction were as follows: the reaction pressure was 0.3 MPa, the reaction temperature was 100 °C, the molar ratio of 1-chloroheptafluorocyclopentene to anhydrous hydrogen fluoride was 1:13, the contact time was 30 s, the flow rate after mixing the two gases of 1-chloroheptafluorocyclopentene and anhydrous hydrogen fluoride was 13 m / s, and the addition amount of the fluorine-chlorine catalyst was 1.8 g.

[0056] Example 9

[0057] The catalyst prepared in Preparation Example 2 was selected, and the conditions for the gas-phase catalytic fluorine-chlorine exchange reaction were as follows: the reaction pressure was 0.4 MPa, the reaction temperature was 110 °C, the molar ratio of 1-chloroheptafluorocyclopentene to anhydrous hydrogen fluoride was 1:14, the contact time was 30 s, the flow rate after mixing the two gases of 1-chloroheptafluorocyclopentene and anhydrous hydrogen fluoride was 14 m / s, and the addition amount of the fluorine-chlorine catalyst was 1.2 g.

[0058] Example 10

[0059] The catalyst prepared in Preparation Example 3 was selected, and the conditions for the gas-phase catalytic fluorine-chlorine exchange reaction were as follows: the reaction pressure was 0.5 MPa, the reaction temperature was 120 °C, the molar ratio of 1-chloroheptafluorocyclopentene to anhydrous hydrogen fluoride was 1:15, the contact time was 30 s, the flow rate after mixing the two gases of 1-chloroheptafluorocyclopentene and anhydrous hydrogen fluoride was 15 m / s, and the addition amount of the fluorine-chlorine catalyst was 1.1 g.

[0060] It should be noted that the addition amount of the fluorine-chlorine catalyst mentioned in Examples 1 to 10 and Comparative Example 1 of this application refers to the mass without loading it onto γ-aluminum oxide.

[0061] Comparative Example 1

[0062] The catalyst is chromium oxide. The conditions for the gas-phase catalytic fluorine-chlorine exchange reaction are as follows: the reaction pressure is 0.2 MPa, the reaction temperature is 100 °C, the molar ratio of 1-chloroheptafluorocyclopentene to anhydrous hydrogen fluoride is 1:10, and the contact time is 30 s.

[0063] Result detection

[0064] The yields of the products obtained in Examples 1 to 10 and the product obtained in Comparative Example 1 were statistically analyzed, and the results are shown in Table 1.

[0065] Sample Conversion rate of F7-1 (%) Yield of F8E (%) Example 1 76％ 80 Example 2 88 83 Example 3 93 88 Example 4 86 81 Example 5 84 80 Example 6 78 82 Example 7 90 90 Example 8 96 96 Example 9 88 90 Example 10 82 84 Comparative Example 1 15 46

[0066] In the table, F7-1 is 1-chloroheptafluorocyclopentene, and F8E is octafluorocyclopentene.

[0067] From the data in Table 1 above, it can be seen that the conversion rate of the currently known catalyst, i.e., the catalyst used in Comparative Example 1, is relatively low, the yield of octafluorocyclopentene is relatively low, and there are more impurities. However, the catalyst prepared by this application can greatly improve the conversion rate of 1-chloroheptafluorocyclopentene and the yield of octafluorocyclopentene. From Comparative Example 1 and Examples 1 to 8, it can be seen that when transition metal zinc ions or alkaline earth metal barium ions are introduced, the specific surface area of γ-aluminum oxide increases, the pore volume and average pore diameter decrease, the active components are more evenly dispersed on the catalyst surface, and the catalytic activity is improved. The introduction of Zn generates defect sites on the catalyst surface, enabling it to adsorb more oxygen and generate more active oxygen, thereby improving the catalytic activity; barium, as an alkaline earth metal, has the advantages of high Lewis acidity and open metal sites, making its catalyst have a high specific surface area.

[0068] The above is only a preferred embodiment of this application and does not impose any form of limitation on this application. Although this application has been disclosed above with a preferred embodiment, it is not intended to limit this application. Any person skilled in the art can make some modifications or equivalents by using the disclosed technical content within the scope of the technical solution of this application. However, any modification, equivalent change, and modification made to the above embodiments based on the technical essence of this application without departing from the content of the technical solution of this application still fall within the scope of the technical solution of this application.

Claims

1. A catalytic synthesis method of octafluorocyclopentene, characterized in that, Under the action of a fluorochlorine catalyst, 1-chloroheptafluorocyclopentene and anhydrous hydrogen fluoride undergo a gas-phase catalytic fluorination reaction at 80°C to 120°C to obtain octafluorocyclopentene.

2. The catalytic synthesis method of octafluorocyclopentene according to claim 1, characterized in that, The preparation method of the fluorochlorine catalyst is as follows: Step S1. Dissolve the metal chloride in water, add a precipitant, and fully stir and react to obtain a slurry; Step S2. Filter the slurry to remove the filtrate to obtain a solid, and wash the solid with deionized water until it is neutral; Step S3. Add an aluminum nitrate solution to the washed solid, fully stir and dry to obtain a catalyst precursor; Step S4. Press the catalyst precursor into a mold, calcine it, and then activate it to obtain a fluorochlorine catalyst.

3. The catalytic synthesis method of octafluorocyclopentene according to claim 2, wherein In step S1, the metal chloride is an alkaline earth metal chloride or a transition metal chloride, and 20 ml of water is added per 1 g of the metal chloride.

4. The catalytic synthesis method of octafluorocyclopentene according to claim 2, wherein, In step S1, the alkaline earth metal chloride is barium chloride, and the transition metal chloride is zinc chloride.

5. The catalytic synthesis method of octafluorocyclopentene according to claim 2, characterized in that, In step S1, the precipitant is ammonia water, and ammonia water is added until the pH value of the solution is 7.5 to 8, and the reaction temperature is 60°C.

6. A catalytic synthesis method of octafluorocyclopentene according to claim 2, characterized in that, In step S3, the concentration of the aluminum nitrate solution is 3 to 4 M, and 50 mL of the aluminum nitrate solution is added per 1 g of the washed solid.

7. A catalytic synthesis method of octafluorocyclopentene according to claim 2, characterized in that, In step S3, the stirring time is 2 h, and the drying condition is drying at 150°C for 12 h.

8. A catalytic synthesis method of octafluorocyclopentene according to claim 2, characterized in that, In step S4, the calcination condition is calcination at 450°C for 10 h in a nitrogen atmosphere; the activation condition is activation with a mixed gas composed of hydrogen fluoride and hydrogen with a molar ratio of 10:1 at 300°C for 10 h.

9. A catalytic synthesis method of octafluorocyclopentene according to claim 1, characterized in that, The carrier of the catalyst is γ-aluminum oxide, and the loading condition is calcination at 400 to 500°C for 0.5 to 1.5 h.

10. A catalytic synthesis method of octafluorocyclopentene according to claim 1, characterized in that, The reaction pressure of the gas-phase catalytic fluorination reaction is 0.1 to 0.5 MPa, the molar ratio of 1-chloroheptafluorocyclopentene to anhydrous hydrogen fluoride is 1:(5 to 15), the contact time is 30 s, the flow rate after mixing the two gases of 1-chloroheptafluorocyclopentene and anhydrous hydrogen fluoride is 0.5 to 15 m / s, and the addition amount of the fluorochlorine catalyst is 1 to 2 g.

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