Method for preparing perfluoroalkane through fluorination of fluorine-containing olefin compound
Through the new gas-solid-phase reaction process, fluoro-containing olefin compounds and fluoro nitrogen are reacted at high temperature under the action of a catalyst, solving the problem of low perfluoronane yield and achieving efficient, safe and easy industrialization of perfluoroalkanes.
Patent Information
- Application Number
- CN202411576173.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-06
- Publication Date
- 2025-02-07
AI Technical Summary
Currently, the yield of perfluorononane is relatively low and it is difficult to meet the growth of market demand.
A new gas-solid-phase reaction process is adopted to react fluorine-containing olefin compounds with fluorine nitrogen at high temperature under the action of a catalyst to form perfluoroalkanes. The method includes steps such as drying treatment, gas replacement, catalyst fixation, gasification and reaction.
It achieves short reaction time, high reaction efficiency, safe and simple operation, and easy industrialization. The reaction can be completed under low concentration of fluorine nitrogen, with low catalyst usage, saving costs.
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Abstract
Description
Technical Field
[0001] The present application relates to the field of preparation of fluorine-containing fine chemicals, and in particular to a method for preparing perfluoroalkanes by fluorination of fluorine-containing olefin compounds. Background Art
[0002] Perfluoroalkanes, as organic fluorine compounds, are a class of elemental organic compounds in which the hydrogen attached to the carbon atom in the organic compound molecule is replaced by fluorine. Compounds in which all carbon-hydrogen bonds in the molecule are converted into carbon-fluorine bonds are called perfluoro organic compounds, and those that are partially replaced are called monofluoro or polyfluoro organic compounds. Since fluorine is the element with the highest electronegativity, polyfluoro organic compounds have the characteristics of chemical stability, surface activity and excellent temperature resistance. Because fluorine is the element with the highest electronegativity, the introduction of fluorine atoms gives perfluoro organic compounds unique physical properties, chemical properties and physiological activity, and makes perfluoro organic compounds have the characteristics of chemical stability, surface activity and excellent temperature resistance. Therefore, perfluoro compounds have been widely and deeply studied and applied in many cutting-edge technologies, major industrial projects, medicine, pesticides and other industries.
[0003] At present, the market demand for fluorine-containing high-efficiency coolants with boiling points between 120-140℃ is increasing sharply. Perfluorononane, as a fluorine-containing high-efficiency coolant with excellent performance, has a boiling point of about 125℃, which just meets this demand range, so it is regarded as a potential ideal substitute. However, despite the high market demand, the current yield of perfluorononane is relatively low, which is difficult to meet the growing market demand. Summary of the invention
[0004] In order to provide a novel method for preparing perfluoroalkane compounds and improve the yield of perfluorononane, the present application provides a method for preparing perfluoroalkane by fluorination of fluorine-containing olefin compounds.
[0005] The present application provides a method for preparing perfluoroalkanes by fluorination of fluorinated olefin compounds using the following technical scheme: A method for preparing perfluoroalkanes by fluorination of fluorine-containing olefin compounds comprises the following steps: The raw material fluorine-containing olefin compound and catalyst are dried separately and then set aside; the reaction device and pipeline are replaced with gas with nitrogen, the catalyst is added to the fixed bed after nitrogen treatment, the catalyst is placed in the fixed bed, and the fixed bed pipeline temperature is heated to the target temperature; the fluorine-containing olefin compound is added to the gasification chamber, the gasification device is heated to the target temperature, and after all gasification, it is passed into the mixing tank at a certain rate, and the fluorine and nitrogen are passed into the mixing tank at the same time. After mixing, the gas is slowly passed into the fixed bed, and the gas flow is slowly and fully contacted with the catalyst in the fixed bed to react, and stay for a period of time; the mixed gas after the reaction is cooled into liquid through a condenser and flows to an absorption tank for absorption, the remaining fluorine and nitrogen are absorbed by the absorption device, and the nitrogen is emptied. The liquid in the absorption tank is purified by post-treatment to obtain perfluoroalkane, and the remaining unreacted fluorine-containing olefin compound can be recovered and used as a raw material for further reaction; The reaction formula is as follows:
[0006] By adopting the above technical scheme and a new gas-solid phase reaction process, under the action of a catalyst, gaseous fluorine-containing olefin compounds and a certain concentration of fluorine-nitrogen gas pass through a fixed bed device under specific conditions, and the fluorine-containing olefin compounds can be fluorinated in a short time to generate perfluoroalkane compounds. The reaction time is short, the reaction efficiency is high, the experimental operation is safe and simple, and it is easy to industrialize.
[0007] Preferably, the catalyst is one or a mixture of potassium fluoride, cesium fluoride, sodium fluoride, aluminum fluoride, etc.
[0008] Preferably, the catalyst is a mixture of cesium fluoride and aluminum fluoride; the mass ratio of cesium fluoride to aluminum fluoride is 1:1-10.
[0009] Preferably, the mass ratio of cesium fluoride to aluminum fluoride is 1:2.5.
[0010] Preferably, the fluorine-containing olefin compound is one of hexafluoropropylene dimer and hexafluoropropylene trimer.
[0011] Preferably, the volume concentration of fluorine gas in the fluorine-nitrogen mixed gas is 1-25%.
[0012] Preferably, the volume concentration of fluorine gas in the fluorine-nitrogen mixed gas is 5-10%.
[0013] Preferably, the molar ratio of the fluorine-containing olefin compound to the fluorine gas is 1:1-10.
[0014] Preferably, the molar ratio of the fluorine-containing olefin compound to the fluorine gas is 1:2.
[0015] Preferably, the temperature of the fluorine-containing olefin compound gasification chamber is 200-300°C; and the fixed bed reaction temperature is 200-400°C.
[0016] Preferably, the temperature of the fluorine-containing olefin compound gasification chamber is 250°C; and the fixed bed reaction temperature is 250°C.
[0017] Preferably, the residence time of the mixed gas in the fluorination reaction section is 1-10 min.
[0018] Preferably, the residence time of the mixed gas in the fluorination reaction section is 5 minutes.
[0019] Preferably, the absorption device uses porous block fluoride absorption.
[0020] In summary, the present application includes at least one of the following beneficial technical effects: 1. A new gas-solid phase reaction process is used to gasify hexafluoropropylene dimer, hexafluoropropylene trimer and other fluorinated olefin compounds, and then directly fluorinate them with fluorine nitrogen gas under the action of a catalyst at high temperature to prepare perfluoroalkane compounds. The reaction time is short, the reaction efficiency is high, the experimental operation is safe and simple, and it is easy to industrialize; 2. The reaction can be completed at low concentrations of raw fluorine and nitrogen gases, requiring less catalyst, greatly saving costs. DETAILED DESCRIPTION
[0021] The present application is further described in detail below with reference to the embodiments. Example
[0022] Example 1 The raw material fluorine-containing olefin compound and catalyst are dried separately and then used for later use; a mixed catalyst of 20g of cesium fluoride and 50g of aluminum fluoride is added to the fixed bed after nitrogen treatment, and the mixture is evenly mixed and placed in the fixed bed, and the temperature of the fixed bed is raised to 250°C; 2kg of hexafluoropropylene trimer is added to the vaporization chamber, and the temperature is set to 250°C. After all the gasification is completed, it is introduced into the mixing tank at a certain rate, and at the same time, fluorine nitrogen gas with a volume concentration of 5% of fluorine gas is introduced into the mixing tank, and the molar ratio of hexafluoropropylene trimer to fluorine gas is maintained at 1:2. After mixing, the gas is slowly introduced into the fixed bed, and the gas flow is allowed to slowly and fully contact the catalyst in the fixed bed for reaction, and the residence time is 5 minutes. The mixed gas after the reaction is cooled by a -10°C condenser into liquid and flows to an absorption tank for absorption. The remaining fluorine nitrogen gas is absorbed by a special absorption device containing sodium fluoride, and the nitrogen is emptied. The liquid in the absorption tank is purified by post-treatment to obtain perfluoroalkane, and the remaining unreacted hexafluoropropylene trimer can be recovered and used as a raw material for further reaction.
[0023] Example 2 The raw material fluorine-containing olefin compound and catalyst are dried separately and then used for standby; a mixed catalyst of 10g cesium fluoride and 60g aluminum fluoride is added to the fixed bed after nitrogen treatment, and the mixture is evenly mixed and placed in the fixed bed, and the temperature of the fixed bed is raised to 250°C; 2kg hexafluoropropylene trimer is added to the vaporization chamber, and the temperature is set to 250°C. After all the gasification is completed, it is introduced into the mixing tank at a certain rate, and at the same time, fluorine nitrogen gas with a volume concentration of 5% of fluorine gas is introduced into the mixing tank, and the molar ratio of hexafluoropropylene trimer to fluorine gas is maintained at 1:2. After mixing, the gas is slowly introduced into the fixed bed, and the gas flow is slowly and fully contacted with the catalyst in the fixed bed for reaction, and the residence time is 5min. The mixed gas after the reaction is cooled by a -10°C condenser into liquid and flows to the absorption tank for absorption. The remaining fluorine nitrogen gas is absorbed by a special absorption device containing sodium fluoride, and the nitrogen is emptied. The liquid in the absorption tank is purified by post-treatment to obtain perfluoroalkane, and the remaining unreacted hexafluoropropylene trimer can be recovered and used as a raw material for further reaction.
[0024] Example 3 The raw material fluorine-containing olefin compound and catalyst are dried separately and then set aside; a mixed catalyst of 35g of cesium fluoride and 35g of aluminum fluoride is added to the fixed bed after nitrogen treatment, and the mixture is evenly mixed and placed in the fixed bed, and the temperature of the fixed bed is raised to 250°C; 2kg of hexafluoropropylene trimer is added to the vaporization chamber, and the temperature is set to 250°C. After all the gasification, it is passed into the mixing tank at a certain rate, and at the same time, fluorine nitrogen gas with a volume concentration of 5% of fluorine gas is passed into the mixing tank, and the molar ratio of hexafluoropropylene trimer to fluorine gas is maintained at 1:2. After mixing, the gas is slowly passed into the fixed bed, and the gas flow is allowed to slowly and fully contact the catalyst in the fixed bed for reaction, and the residence time is 5min. The mixed gas after the reaction is cooled by a -10°C condenser into liquid and flows to the absorption tank for absorption. The remaining fluorine nitrogen gas is absorbed by a special absorption device containing sodium fluoride, and the nitrogen is emptied. The liquid in the absorption tank is purified by post-treatment to obtain perfluoroalkane, and the remaining unreacted hexafluoropropylene trimer can be recovered and continued to be used as a raw material for reaction.
[0025] Example 4 The raw material fluorine-containing olefin compound and catalyst are dried separately and then used; a mixed catalyst of 7g cesium fluoride and 63g aluminum fluoride is added to the fixed bed after nitrogen treatment, and the mixture is evenly mixed and placed in the fixed bed, and the temperature of the fixed bed is raised to 250°C; 2kg hexafluoropropylene trimer is added to the vaporization chamber, and the temperature is set to 250°C. After all the gasification, it is passed into the mixing tank at a certain rate, and at the same time, fluorine nitrogen gas with a volume concentration of 5% of fluorine gas is passed into the mixing tank, and the molar ratio of hexafluoropropylene trimer to fluorine gas is maintained at 1:2. After mixing, the gas is slowly passed into the fixed bed, and the gas flow is allowed to slowly and fully contact the catalyst in the fixed bed for reaction, and the residence time is 5 minutes. The mixed gas after the reaction is cooled by a -10°C condenser into liquid and flows to the absorption tank for absorption. The remaining fluorine nitrogen gas is absorbed by a special absorption device containing sodium fluoride, and the nitrogen is emptied. The liquid in the absorption tank is purified by post-treatment to obtain perfluoroalkane, and the remaining unreacted hexafluoropropylene trimer can be recovered and used as a raw material for further reaction.
[0026] Example 5 The raw material fluorine-containing olefin compound and catalyst are dried separately and then used for standby; a mixed catalyst of 20g of cesium fluoride and 50g of aluminum fluoride is added to the fixed bed after nitrogen treatment, and the mixture is evenly mixed and placed in the fixed bed, and the temperature of the fixed bed is raised to 250°C; 2kg of hexafluoropropylene trimer is added to the vaporization chamber, and the temperature is set to 250°C. After all the gasification, it is passed into the mixing tank at a certain rate, and at the same time, fluorine nitrogen gas with a volume concentration of 3% of fluorine gas is passed into the mixing tank, and the molar ratio of hexafluoropropylene trimer to fluorine gas is maintained at 1:2. After mixing, the gas is slowly passed into the fixed bed, and the gas flow is allowed to slowly and fully contact the catalyst in the fixed bed for reaction, and the residence time is 5 minutes. The mixed gas after the reaction is cooled by a -10°C condenser into liquid and flows to the absorption tank for absorption, and the remaining fluorine nitrogen gas is absorbed by a special absorption device containing sodium fluoride, and the nitrogen is emptied. The liquid in the absorption tank is purified by post-treatment to obtain perfluoroalkane, and the remaining unreacted hexafluoropropylene trimer can be recovered and continued to be used as a raw material for reaction.
[0027] Example 6 The raw material fluorine-containing olefin compound and catalyst are dried separately and then used; a mixed catalyst of 20g of cesium fluoride and 50g of aluminum fluoride is added to the fixed bed after nitrogen treatment, and the mixture is evenly mixed and placed in the fixed bed, and the temperature of the fixed bed is raised to 250°C; 2kg of hexafluoropropylene trimer is added to the vaporization chamber, and the temperature is set to 250°C. After all the gasification is completed, it is introduced into the mixing tank at a certain rate, and at the same time, fluorine nitrogen gas with a volume concentration of 1% of fluorine gas is introduced into the mixing tank, and the molar ratio of hexafluoropropylene trimer to fluorine gas is maintained at 1:2. After mixing, the gas is slowly introduced into the fixed bed, and the gas flow is slowly and fully contacted with the catalyst in the fixed bed for reaction, and the residence time is 5 minutes. The mixed gas after the reaction is cooled by a -10°C condenser into liquid and flows to the absorption tank for absorption, and the remaining fluorine nitrogen gas is absorbed by a special absorption device containing sodium fluoride, and the nitrogen is emptied. The liquid in the absorption tank is purified by post-treatment to obtain perfluoroalkane, and the remaining unreacted hexafluoropropylene trimer can be recovered and used as a raw material for further reaction.
[0028] Example 7 The raw material fluorine-containing olefin compound and catalyst are dried separately and then used for later use; a mixed catalyst of 20g of cesium fluoride and 50g of aluminum fluoride is added to the fixed bed after nitrogen treatment, the mixture is evenly mixed and placed in the fixed bed, and the temperature of the fixed bed is raised to 250°C; 2kg of hexafluoropropylene trimer is added to the vaporization chamber, the temperature is set to 250°C, and after all the gasification is completed, it is introduced into the mixing tank at a certain rate, and at the same time, fluorine nitrogen gas with a volume concentration of 10% of fluorine gas is introduced into the mixing tank, and the molar ratio of hexafluoropropylene trimer to fluorine gas is maintained at 1:2. After mixing, the gas is slowly introduced into the fixed bed, and the gas flow is slowly and fully contacted with the catalyst in the fixed bed for reaction, and the residence time is 5 minutes. The mixed gas after the reaction is cooled by a -10°C condenser into liquid and flows to the absorption tank for absorption, and the remaining fluorine nitrogen gas is absorbed by a special absorption device containing sodium fluoride, and the nitrogen is emptied. The liquid in the absorption tank is purified by post-treatment to obtain perfluoroalkane, and the remaining unreacted hexafluoropropylene trimer can be recovered and continued to be used as a raw material for reaction.
[0029] Example 8 The raw material fluorine-containing olefin compound and catalyst are dried separately and then used for later use; a mixed catalyst of 20g of cesium fluoride and 50g of aluminum fluoride is added to the fixed bed after nitrogen treatment, and the mixture is evenly mixed and placed in the fixed bed, and the temperature of the fixed bed is raised to 250°C; 2kg of hexafluoropropylene trimer is added to the vaporization chamber, and the temperature is set to 250°C. After all the gasification, it is passed into the mixing tank at a certain rate, and at the same time, fluorine nitrogen gas with a volume concentration of 25% of fluorine gas is passed into the mixing tank, and the molar ratio of hexafluoropropylene trimer to fluorine gas is maintained at 1:2. After the mixing is completed, the gas is slowly passed into the fixed bed, and the gas flow is allowed to slowly and fully contact the catalyst in the fixed bed for reaction, and the residence time is 5 minutes. The mixed gas after the reaction is cooled by a -10°C condenser into liquid and flows to the absorption tank for absorption, and the remaining fluorine nitrogen gas is absorbed by a special absorption device containing sodium fluoride, and the nitrogen is emptied. The liquid in the absorption tank is purified by post-treatment to obtain perfluoroalkane, and the remaining unreacted hexafluoropropylene trimer can be recovered and continued to be used as a raw material for reaction.
[0030] Example 9 The raw material fluorine-containing olefin compound and catalyst are dried separately and then set aside; a mixed catalyst of 20g of cesium fluoride and 50g of aluminum fluoride is added to the fixed bed after nitrogen treatment, and the mixture is evenly mixed and placed in the fixed bed, and the temperature of the fixed bed is raised to 200°C; 2kg of hexafluoropropylene trimer is added to the vaporization chamber, and the temperature is set to 200°C. After all the gasification is completed, it is introduced into the mixing tank at a certain rate, and at the same time, fluorine nitrogen gas with a volume concentration of 5% of fluorine gas is introduced into the mixing tank, and the molar ratio of hexafluoropropylene trimer to fluorine gas is maintained at 1:2. After mixing, the gas is slowly introduced into the fixed bed, and the gas flow is slowly and fully contacted with the catalyst in the fixed bed for reaction, and the residence time is 5 minutes. The mixed gas after the reaction is cooled by a -10°C condenser into liquid and flows to an absorption tank for absorption. The remaining fluorine nitrogen gas is absorbed by a special absorption device containing sodium fluoride, and the nitrogen is emptied. The liquid in the absorption tank is purified by post-treatment to obtain perfluoroalkane, and the remaining unreacted hexafluoropropylene trimer can be recovered and used as a raw material for further reaction.
[0031] Example 10 The raw material fluorine-containing olefin compound and catalyst are dried separately and then set aside; a mixed catalyst of 20g of cesium fluoride and 50g of aluminum fluoride is added to the fixed bed after nitrogen treatment, and the mixture is evenly mixed and placed in the fixed bed, and the temperature of the fixed bed is raised to 400°C; 2kg of hexafluoropropylene trimer is added to the vaporization chamber, and the temperature is set to 300°C. After all the gasification is completed, it is introduced into the mixing tank at a certain rate, and at the same time, fluorine nitrogen gas with a volume concentration of 5% of fluorine gas is introduced into the mixing tank, and the molar ratio of hexafluoropropylene trimer to fluorine gas is maintained at 1:2. After mixing, the gas is slowly introduced into the fixed bed, and the gas flow is allowed to slowly and fully contact the catalyst in the fixed bed for reaction, and the residence time is 5 minutes. The mixed gas after the reaction is cooled by a -10°C condenser into liquid and flows to an absorption tank for absorption. The remaining fluorine nitrogen gas is absorbed by a special absorption device containing sodium fluoride, and the nitrogen is emptied. The liquid in the absorption tank is purified by post-treatment to obtain perfluoroalkane, and the remaining unreacted hexafluoropropylene trimer can be recovered and continued to be used as a raw material for reaction.
[0032] Embodiment 11 The raw material fluorine-containing olefin compound and catalyst are dried separately and then used for later use; a mixed catalyst of 20g of cesium fluoride and 50g of aluminum fluoride is added to the fixed bed after nitrogen treatment, the mixture is evenly mixed and placed in the fixed bed, and the temperature of the fixed bed is raised to 250°C; 2kg of hexafluoropropylene trimer is added to the vaporization chamber, the temperature is set to 250°C, and after all the gasification is completed, it is introduced into the mixing tank at a certain rate, and at the same time, fluorine nitrogen gas with a volume concentration of 5% of fluorine gas is introduced into the mixing tank, and the molar ratio of hexafluoropropylene trimer to fluorine gas is maintained at 1:2. After mixing, the gas is slowly introduced into the fixed bed, and the gas flow is allowed to slowly and fully contact the catalyst in the fixed bed for reaction, and the residence time is 1min. The mixed gas after the reaction is cooled by a -10°C condenser into liquid and flows to an absorption tank for absorption, and the remaining fluorine nitrogen gas is absorbed by a special absorption device containing sodium fluoride, and the nitrogen is emptied. The liquid in the absorption tank is purified by post-treatment to obtain perfluoroalkane, and the remaining unreacted hexafluoropropylene trimer can be recovered and continued to be used as a raw material for reaction.
[0033] Example 12 The raw material fluorine-containing olefin compound and catalyst are dried separately and then used for later use; a mixed catalyst of 20g of cesium fluoride and 50g of aluminum fluoride is added to the fixed bed after nitrogen treatment, and the mixture is evenly mixed and placed in the fixed bed, and the temperature of the fixed bed is raised to 250°C; 2kg of hexafluoropropylene trimer is added to the vaporization chamber, and the temperature is set to 250°C. After all the gasification, it is passed into the mixing tank at a certain rate, and at the same time, fluorine nitrogen gas with a volume concentration of 5% of fluorine gas is passed into the mixing tank, and the molar ratio of hexafluoropropylene trimer to fluorine gas is maintained at 1:2. After mixing, the gas is slowly passed into the fixed bed, and the gas flow is allowed to slowly and fully contact the catalyst in the fixed bed for reaction, and the residence time is 10 minutes. The mixed gas after the reaction is cooled by a -10°C condenser into liquid and flows to the absorption tank for absorption, and the remaining fluorine nitrogen gas is absorbed by a special absorption device containing sodium fluoride, and the nitrogen is emptied. The liquid in the absorption tank is purified by post-treatment to obtain perfluoroalkane, and the remaining unreacted hexafluoropropylene trimer can be recovered and continued to be used as a raw material for reaction.
[0034] Embodiment 13 The raw material fluorine-containing olefin compound and catalyst are dried separately and then used; a mixed catalyst of 20g of cesium fluoride and 50g of aluminum fluoride is added to the fixed bed after nitrogen treatment, and the mixture is evenly mixed and placed in the fixed bed, and the temperature of the fixed bed is raised to 250°C; 2kg of hexafluoropropylene trimer is added to the vaporization chamber, and the temperature is set to 250°C. After all the gasification, it is passed into the mixing tank at a certain rate, and at the same time, fluorine nitrogen gas with a volume concentration of 5% of fluorine gas is passed into the mixing tank, and the molar ratio of hexafluoropropylene trimer to fluorine gas is maintained at 1:1. After mixing, the gas is slowly passed into the fixed bed, and the gas flow is allowed to slowly and fully contact the catalyst in the fixed bed for reaction, and the residence time is 5 minutes. The mixed gas after the reaction is cooled by a -10°C condenser into liquid and flows to an absorption tank for absorption. The remaining fluorine nitrogen gas is absorbed by a special absorption device containing sodium fluoride, and the nitrogen is emptied. The liquid in the absorption tank is purified by post-treatment to obtain perfluoroalkane, and the remaining unreacted hexafluoropropylene trimer can be recovered and continued to be used as a raw material for reaction.
[0035] Embodiment 14 The raw material fluorine-containing olefin compound and catalyst are dried separately and then used; a mixed catalyst of 20g of cesium fluoride and 50g of aluminum fluoride is added to the fixed bed after nitrogen treatment, and the mixture is evenly mixed and placed in the fixed bed, and the temperature of the fixed bed is raised to 250°C; 2kg of hexafluoropropylene trimer is added to the vaporization chamber, and the temperature is set to 250°C. After all the gasification is completed, it is introduced into the mixing tank at a certain rate, and at the same time, fluorine nitrogen gas with a volume concentration of 5% of fluorine gas is introduced into the mixing tank, and the molar ratio of hexafluoropropylene trimer to fluorine gas is maintained at 1:10. After mixing, the gas is slowly introduced into the fixed bed, and the gas flow is allowed to slowly and fully contact the catalyst in the fixed bed for reaction, and the residence time is 5min. The mixed gas after the reaction is cooled by a -10°C condenser into liquid and flows to an absorption tank for absorption, and the remaining fluorine nitrogen gas is absorbed by a special absorption device containing sodium fluoride, and the nitrogen is emptied. The liquid in the absorption tank is purified by post-treatment to obtain perfluoroalkane, and the remaining unreacted hexafluoropropylene trimer can be recovered and used as a raw material for further reaction.
[0036] Embodiment 15 The raw material fluorine-containing olefin compound and catalyst are dried separately and then used; 70g of potassium fluoride mixed catalyst is added to the fixed bed treated with nitrogen, mixed evenly and placed in the fixed bed, and the temperature of the fixed bed is raised to 250°C; 2kg of hexafluoropropylene dimer is added to the vaporization chamber, the temperature is set to 250°C, and after all are vaporized, it is passed into the mixing tank at a certain rate, and at the same time, fluorine nitrogen gas with a volume concentration of 5% of fluorine gas is passed into the mixing tank, and the molar ratio of hexafluoropropylene trimer to fluorine gas is maintained at 1:2. After mixing, the gas is slowly passed into the fixed bed, and the gas flow is allowed to slowly and fully contact the catalyst in the fixed bed for reaction, and the residence time is 5 minutes. The mixed gas after the reaction is cooled by a -10°C condenser into liquid and flows to an absorption tank for absorption. The remaining fluorine nitrogen gas is absorbed by a special absorption device containing sodium fluoride, and the nitrogen is emptied. The liquid in the absorption tank is purified by post-treatment to obtain perfluoroalkane, and the remaining unreacted hexafluoropropylene trimer can be recovered and continued to be used as a raw material for reaction.
[0037] Performance testing 1. The product perfluoroalkane obtained in Examples 1-15 was subjected to liquid phase analysis to obtain the purity and yield of the product. The results are shown in Table 1.
[0038] The specific test results are as follows: Table 1 Performance test results It can be seen from the test results in Table 1 that the method for preparing perfluoroalkane by fluorination of fluorine-containing olefin compounds provided in the present application can obtain a product with high yield and purity.
[0039] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.
Claims
1. A method for preparing perfluoroalkanes by fluorination of fluorinated olefin compounds, characterized in that: The following steps are involved: The raw material fluorine-containing olefin compound and catalyst are dried separately and then set aside; the reaction device and pipeline are replaced with gas with nitrogen, the catalyst is added to the fixed bed after nitrogen treatment, the catalyst is placed in the fixed bed, and the fixed bed pipeline temperature is heated to the target temperature; the fluorine-containing olefin compound is added to the gasification chamber, the gasification device is heated to the target temperature, and after all gasification, it is passed into the mixing tank at a certain rate, and the fluorine and nitrogen are passed into the mixing tank at the same time. After mixing, the gas is slowly passed into the fixed bed, and the gas flow is slowly and fully contacted with the catalyst in the fixed bed to react, and stay for a period of time; the mixed gas after the reaction is cooled into liquid through a condenser and flows to an absorption tank for absorption, the remaining fluorine and nitrogen are absorbed by the absorption device, and the nitrogen is emptied. The liquid in the absorption tank is purified by post-treatment to obtain perfluoroalkane, and the remaining unreacted fluorine-containing olefin compound can be recovered and used as a raw material for further reaction; The reaction formula is as follows:
2. The method for preparing perfluoroalkanes by fluorination of fluorinated olefin compounds according to claim 1, characterized in that: The catalyst is one or a mixture of potassium fluoride, cesium fluoride, sodium fluoride, aluminum fluoride, etc.
3. The method for preparing perfluoroalkanes by fluorination of fluorinated olefin compounds according to claim 2, characterized in that: The catalyst is a mixture of cesium fluoride and aluminum fluoride; the mass ratio of the cesium fluoride to the aluminum fluoride is 1:1-10.
4. The method for preparing perfluoroalkanes by fluorination of fluorinated olefin compounds according to claim 3, characterized in that: The mass ratio of cesium fluoride to aluminum fluoride is 1:2.
5.
5. The method for preparing perfluoroalkanes by fluorination of fluorinated olefin compounds according to claim 1, characterized in that: The fluorine-containing olefin compound is one of a hexafluoropropylene dimer and a hexafluoropropylene trimer.
6. The method for preparing perfluoroalkanes by fluorination of fluorinated olefin compounds according to claim 1, characterized in that: The volume concentration of fluorine gas in the fluorine-nitrogen mixed gas is 1-25%.
7. The method for preparing perfluoroalkanes by fluorination of fluorinated olefin compounds according to claim 1, characterized in that: The molar ratio of the fluorine-containing olefin compound to the fluorine gas is 1:1-10.
8. The method for preparing perfluoroalkanes by fluorination of fluorinated olefin compounds according to claim 1, characterized in that: The temperature of the fluorine-containing olefin compound gasification chamber is 200-300°C; the fixed bed reaction temperature is 200-400°C.
9. The method for preparing perfluoroalkanes by fluorination of fluorinated olefin compounds according to claim 1, characterized in that: The residence time of the mixed gas in the fluorination reaction section is 1-10 minutes.
10. The method for preparing perfluoroalkanes by fluorination of fluorinated olefin compounds according to claim 1, characterized in that: The absorption device adopts porous block fluoride absorption.