Method and device for preparing perfluorohexane

Abstract

The invention relates to a preparation process of a fluorination liquid, in particular to a preparation method and device of perfluorohexane, and the preparation method comprises the following steps: mixing hexafluoropropylene and fluorine-containing gas for reaction to obtain crude perfluorohexane; the method comprises the following steps of: performing primary alkali washing and secondary alkali washing on a crude product of perfluorohexane, removing moisture, and finally performing primary condensation and secondary condensation to obtain the product of perfluorohexane by primary condensation and recover hexafluoropropylene for circular reaction by secondary condensation. The preparation device comprises a reaction tower, a buffer tank, a primary alkaline washing tower, a secondary alkaline washing tower, a drying tower, a first cold trap and a second cold trap which are communicated in sequence. The method is simple in production process, high in hexafluoropropylene conversion rate, high in product purity and low in comprehensive cost, and has good economic benefits and application prospects.

Description

Technical Field

[0001] The present application relates to a process for preparing a fluorinated liquid, and more specifically, to a method and apparatus for preparing perfluorohexane. Background Art

[0002] The chemical formula of perfluorohexane is C6F 14 , is a colorless, odorless, non-flammable liquid with excellent chemical and thermal stability, which makes it widely used in many fields. The following are some of the main applications of perfluorohexane:

[0003] ①Industrial solvents and cleaning agents: As a high-performance industrial solvent, perfluorohexane is often used in the cleaning and degreasing processes of precision equipment. ②Coolant for electronic products: Due to its good thermal stability and chemical inertness, perfluorohexane can be used as a coolant for electronic products, especially under high temperature or high pressure environments. ③Substitute substances: Perfluorohexane can also be used as a safe substitute for certain hazardous substances, such as replacing traditional hydrocarbon solvents in certain industrial processes. ④Lubricant or plastic additive: In the automotive manufacturing and aerospace industries, perfluorohexane can be used as a lubricant and plastic additive to improve the performance and durability of products. ⑤Medical applications: The biological inertness and chemical stability of perfluorohexane make it a medical concern. It can dissolve gases (including oxygen in the air) to higher concentrations than ordinary organic solvents, making it a potential oxygen delivery medium.

[0004] Due to its wide application in many fields, the synthesis method of perfluorohexane has received increasing attention. At present, there are two main methods for preparing perfluorohexane. One is to prepare perfluorohexane by electrolysis. The Chinese patent with announcement number CN109652819B discloses a method for preparing branched perfluorohexane. The patent uses hexafluoropropylene dimer as raw material, catalytic hydrogenation to synthesize dodecafluorodihydrohexane; then dodecafluorodihydrohexane, anhydrous hydrogen fluoride and conductive additive dimethyl disulfide are electrochemically fluorinated in an electrolytic cell to obtain perfluorohexane. However, the electrolytic method for preparing perfluorohexane is complicated, and the raw material hexafluoropropylene dimer is expensive, has many side reactions, and has many impurities in the product, which is difficult to purify. The other is to use fluorine gas to directly fluorinate hexane at high temperature, but this reaction is carried out under high temperature conditions. Not only are the reaction conditions harsh, there are many side reactions, but the product is difficult to purify and the product yield is low.

[0005] In summary, the methods for preparing perfluorohexane in the prior art have problems such as harsh reaction conditions, difficult to control the reaction process, difficult product purification, and low product yield. Therefore, it is urgent to propose a method for preparing perfluorohexane with mild reaction conditions, fewer reaction by-products, and simple product purification to solve the current problems. Summary of the invention

[0006] In view of the problems in the prior art of preparing perfluorohexane, such as harsh reaction conditions, difficult reaction process control, difficulty in product purification, and low product yield, the present application proposes a method and device for preparing perfluorohexane.

[0007] The technical solution of this application:

[0008] On the one hand, the present application provides a method for preparing perfluorohexane, comprising the following steps:

[0009] Step S1. mixing hexafluoropropylene and fluorine-containing gas to react to obtain crude perfluorohexane;

[0010] Step S2. The crude perfluorohexane is subjected to primary and secondary alkali washing, followed by removal of moisture, and finally to primary and secondary condensation, wherein the primary condensation obtains the product perfluorohexane, and the secondary condensation recovers hexafluoropropylene for the circulation reaction.

[0011] Preferably, the molar ratio of hexafluoropropylene to fluorine in the fluorine-containing gas in step S1 is (2-6):1, the fluorine-containing gas is a mixture of fluorine and an inert gas, and the inert gas accounts for 40-70 vol% of the total amount of hexafluoropropylene and the fluorine-containing gas.

[0012] Preferably, the temperature of the mixing reaction in step S1 is 10 to 200° C., and the pressure is -0.05 to 0.3 MPa.

[0013] Preferably, the alkali solution for the primary alkali washing and the secondary alkali washing in step S2 is any one of sodium hydroxide and potassium hydroxide.

[0014] Preferably, the adsorbent for removing moisture in step S2 is any one of 3A, 4A, 5A and Na-X zeolite.

[0015] On the other hand, the present application provides a preparation device of perfluorohexane, comprising a reaction tower, a buffer tank, a primary alkali washing tower, a secondary alkali washing tower, a drying tower, a first cold trap and a second cold trap, wherein the reaction tower, the buffer tank, the primary alkali washing tower, the secondary alkali washing tower, the drying tower, the first cold trap and the second cold trap are connected in sequence through pipelines.

[0016] Preferably, the reaction tower is filled with a filler, the filler is a metal ring, and the material of the metal ring is any one of nickel and monel; the side of the reaction tower is provided with a hexafluoropropylene gas inlet and a fluorine-containing gas inlet.

[0017] Preferably, the first cold trap is provided with a first cold trap column at the upper part and a first tower kettle at the lower part (the first cold trap column is connected to the first tower kettle; the second cold trap is provided with a second cold trap column at the upper part and a second tower kettle at the lower part, the second cold trap column is connected to the second tower kettle, and the upper end of the second cold trap is also provided with a gas outlet.

[0018] Preferably, the temperature of the first cold trap column is -25 to 20°C, and the temperature of the first tower bottom is 0 to 40°C; the temperature of the second cold trap column is -90 to -40°C, and the temperature of the second tower bottom is -50 to -30°C.

[0019] Beneficial effects of this application:

[0020] The preparation method of perfluorohexane provided in the present application has high conversion efficiency and low loss. By accurately controlling the molar ratio of hexafluoropropylene to fluorine gas (2 to 6): 1 and optimizing the reaction temperature and pressure conditions, the efficient conversion of hexafluoropropylene to perfluorohexane is achieved, which not only improves the conversion rate, but also significantly reduces the generation of by-products, greatly improves the economy of the overall process, and reduces resource waste. The raw materials for the preparation method of perfluorohexane provided in the present application, hexafluoropropylene, are widely available, low-priced, easy to purchase, and reduce production costs. The two-stage alkali washing process (alkali solution is sodium hydroxide or potassium hydroxide) used in the purification process of the present application effectively removes acidic gases and other impurities in the crude product. Subsequently, the water is further removed by drying to ensure the purity of the product and reduce the water content of the product. After separation by primary and secondary condensation, perfluorohexane with a purity of up to 99.95% is obtained, which meets the strict requirements of the high-end electronics industry for high-quality raw materials. In the entire preparation process of the present application, the unreacted hexafluoropropylene is recovered and recycled, which reduces the production cost and reduces the emission of harmful substances. The raw materials used in the present application are relatively environmentally friendly and have little impact on the environment. The device of the present application constructs a closed-loop production system, achieving the unity of economic and environmental benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Attached Figure 1 This is a schematic diagram of the preparation device of perfluorohexane in this application.

[0022] Figure numerals: 1, hexafluoropropylene gas inlet; 2, fluorine-containing gas inlet; 3, reaction tower; 4, buffer tank; 5, primary alkali washing tower; 6, secondary alkali washing tower; 7, drying tower; 8, adsorbent plate; 9, first cold trap; 10, first cold trap column; 11, first tower bottom; 12, second cold trap; 13, second cold trap column; 14, second tower bottom; 15, gas outlet. DETAILED DESCRIPTION

[0023] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the specific implementation mode, structure, characteristics and effects of the present invention are described in detail below in combination with the accompanying drawings and preferred embodiments.

[0024] Example 1

[0025] This embodiment provides a device for preparing perfluorohexane, such as Figure 1As shown, it includes a reaction tower 3, a buffer tank 4, a primary alkali washing tower 5, a secondary alkali washing tower 6, a drying tower 7, a first cold trap and a first cold trap 12, and the reaction tower 3, the buffer tank 4, the primary alkali washing tower 5, the secondary alkali washing tower 6, the drying tower 7, the first cold trap 9 and the first cold trap 12 are connected in sequence through pipelines.

[0026] The reaction tower 3 is filled with a filler, wherein the filler is a metal ring, and the material of the metal ring is any one of nickel and monel. The side of the reaction tower 3 is provided with a hexafluoropropylene gas inlet 1 and a fluorine-containing gas inlet 2.

[0027] A first cold trap column 10 is provided at the upper part of the first cold trap 9, and a first tower kettle 11 is provided at the lower part, and the first cold trap column 10 and the first tower kettle 11 are connected; a second cold trap column 13 is provided at the upper part of the second cold trap 12, and a second tower kettle 14 is provided at the lower part, and the second cold trap column 13 and the second tower kettle 14 are connected, and a gas outlet 15 is also provided at the upper end of the second cold trap 12.

[0028] Example 2

[0029] Based on the perfluorohexane preparation device provided in Example 1, this example provides a method for preparing perfluorohexane.

[0030] Hexafluoropropylene is introduced into the reaction tower 3 through the hexafluoropropylene gas inlet 1, and the fluorine-containing gas is introduced into the reaction tower 3 through the fluorine-containing gas inlet. A fluorination reaction is carried out in the reaction tower 3. The reaction temperature is controlled to be 10°C, the reaction pressure is -0.05MPa, the molar ratio of hexafluoropropylene to fluorine gas is 2, helium accounts for 40vol% of the total amount of hexafluoropropylene and fluorine-containing gas, and the filler material in the reaction tower 3 is nickel. The reacted gas enters the buffer tank 4, and then enters the primary alkali washing tower 5. After alkali washing, it enters the secondary alkali washing tower 6 to remove acidic gas and other impurities in the reacted gas. The primary alkali washing tower 5 and the secondary alkali washing tower 6 are used to remove the acidic gas and other impurities in the reacted gas. The solution in the washing tower 6 is a NaOH solution, and then enters the drying tower 7 to remove moisture from the gas. The adsorbent on the adsorbent plate 8 in the drying tower 7 is a 3A molecular sieve. Finally, the gas flows into the first cold trap 9, and the temperature of the first cold trap column 10 is controlled to be -25°C, and the temperature of the first tower bottom 11 is 0°C. Perfluorohexane is collected in the first tower bottom 11, and the remaining gas flows into the first cold trap 12. The temperature of the second cold trap column 13 is controlled to be -90°C, and the temperature of the second tower bottom 14 is -50°C. Hexafluoropropylene is collected in the second tower bottom 14 and can be circulated to participate in the reaction by heating again; inert helium is discharged from the gas outlet 15.

[0031] Example 3

[0032] Based on the perfluorohexane preparation device provided in Example 1, this example provides a method for preparing perfluorohexane.

[0033] Hexafluoropropylene is introduced into the reaction tower 3 through the hexafluoropropylene gas inlet 1, and the fluorine-containing gas is introduced into the reaction tower 3 through the fluorine-containing gas inlet. A fluorination reaction is carried out in the reaction tower 3. The reaction temperature is controlled to be 70°C, the reaction pressure is -0.05MPa, the molar ratio of hexafluoropropylene to fluorine gas is 3, helium accounts for 50vol% of the total amount of hexafluoropropylene and fluorine-containing gas, and the filler material in the reaction tower 3 is monel. The reacted gas enters the buffer tank 4, and then enters the primary alkali washing tower 5. After alkali washing, it enters the secondary alkali washing tower 6 to remove acidic gas and other impurities in the reacted gas. The primary alkali washing tower 5 and the secondary alkali washing tower 6 are used to remove acidic gas and other impurities in the reacted gas. The solution in the alkali washing tower 6 is a KOH solution, and then enters the drying tower 7 to remove moisture in the gas. The adsorbent on the adsorbent plate 8 in the drying tower 7 is a 4A molecular sieve. Finally, the gas flows into the first cold trap 9, and the temperature of the first cold trap column 10 is controlled to be -10°C, and the temperature of the first tower bottom 11 is 15°C. Perfluorohexane is collected in the first tower bottom 11, and the remaining gas flows into the first cold trap 12. The temperature of the second cold trap column 13 is controlled to be -74°C, and the temperature of the second tower bottom 14 is -43°C. Hexafluoropropylene is collected in the second tower bottom 14 and can be circulated to participate in the reaction by heating again; helium is discharged from the gas outlet 15.

[0034] Example 4

[0035] Based on the perfluorohexane preparation device provided in Example 1, this example provides a method for preparing perfluorohexane.

[0036] Hexafluoropropylene is introduced into the reaction tower 3 through the hexafluoropropylene gas inlet 1, and the fluorine-containing gas is introduced into the reaction tower 3 through the fluorine-containing gas inlet. A fluorination reaction is carried out in the reaction tower 3. The reaction temperature is controlled to be 130° C., the reaction pressure is 0.15 MPa, the molar ratio of hexafluoropropylene to fluorine gas is 4, argon accounts for 60 vol% of the total amount of hexafluoropropylene and fluorine-containing gas, and the filler material in the reaction tower 3 is nickel. The reacted gas enters the buffer tank 4, and then enters the primary alkali washing tower 5. After alkali washing, it enters the secondary alkali washing tower 6 to remove acidic gas and other impurities in the reacted gas. The primary alkali washing tower 5 and the secondary alkali washing tower 6 are used to remove acidic gas and other impurities in the reacted gas. The solution in the alkali washing tower 6 is a NaOH solution, and then enters the drying tower 7 to remove moisture in the gas. The adsorbent on the adsorbent plate 8 in the drying tower 7 is a 5A molecular sieve. Finally, the gas flows into the first cold trap 9, and the temperature of the first cold trap column 10 is controlled to be 5°C, and the temperature of the first tower bottom 11 is 30°C. Perfluorohexane is collected in the first tower bottom 11, and the remaining gas flows into the first cold trap 12. The temperature of the second cold trap column 13 is controlled to be -57°C, and the temperature of the second tower bottom 14 is -36°C. Hexafluoropropylene is collected in the second tower bottom 14 and can be circulated to participate in the reaction by heating again; argon is discharged from the gas outlet 15.

[0037] Example 5

[0038] Based on the perfluorohexane preparation device provided in Example 1, this example provides a method for preparing perfluorohexane.

[0039] Hexafluoropropylene is introduced into the reaction tower 3 through the hexafluoropropylene gas inlet 1, and the fluorine-containing gas is introduced into the reaction tower 3 through the fluorine-containing gas inlet. A fluorination reaction is carried out in the reaction tower 3. The reaction temperature is controlled to be 200°C, the reaction pressure is 0.30MPa, the molar ratio of hexafluoropropylene to fluorine gas is 6, argon accounts for 70vol% of the total amount of hexafluoropropylene and fluorine-containing gas, and the filler material in the reaction tower 3 is nickel. The reacted gas enters the buffer tank 4 and then enters the primary alkali washing tower 5. After alkali washing, it enters the secondary alkali washing tower 6 to remove acidic gas and other impurities in the reacted gas. The primary alkali washing tower 5 and the secondary alkali washing tower 6 are used to remove the acidic gas and other impurities in the reacted gas. The solution in the washing tower 6 is a NaOH solution, and then enters the drying tower 7 to remove moisture from the gas. The adsorbent on the adsorbent plate 8 in the drying tower 7 is a Na-X molecular sieve. Finally, the gas flows into the first cold trap 9, and the temperature of the first cold trap column 10 is controlled to be 20°C, and the temperature of the first tower bottom 11 is 40°C. Perfluorohexane is collected in the first tower bottom 11, and the remaining gas flows into the first cold trap 12. The temperature of the second cold trap column 13 is controlled to be -40°C, and the temperature of the second tower bottom 14 is -30°C. Hexafluoropropylene is collected in the second tower bottom 14 and can be circulated to participate in the reaction by heating again; argon gas is discharged from the gas outlet 15.

[0040] Results

[0041] The purity of perfluorohexane in Examples 2 to 5 and the loss of hexafluoropropylene in the second cold trap were detected. The results are shown in Table 1.

[0042] Table 1

[0043] sample Purity of Perfluorohexane Loss of hexafluoropropylene Example 2 99.91％ 0.1％ Example 3 99.94％ 0.2％ Example 4 99.95％ 0.2％ Example 5 99.92％ 0.9％

[0044] Results Analysis

[0045] It can be seen from Comparative Examples 2 to 5 in combination with Table 1 that the method for preparing perfluorohexane provided in the present application has high conversion efficiency and low loss. By precisely controlling the molar ratio of hexafluoropropylene to fluorine gas (2 to 6): 1 and optimizing the reaction temperature and pressure conditions, efficient conversion of hexafluoropropylene to perfluorohexane is achieved, and perfluorohexane with a purity of up to 99.95% is obtained, which meets the strict requirements of the high-end electronics industry for high-quality raw materials, and the loss of hexafluoropropylene in the second cold trap is as low as 0.1%.

[0046] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technical personnel in this field can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A method for preparing perfluorohexane, characterized in that: The steps include: Step S1. mixing hexafluoropropylene and a fluorine-containing gas to react to obtain crude perfluorohexane; Step S2. The crude perfluorohexane is subjected to primary and secondary alkali washing, followed by removal of moisture, and finally to primary and secondary condensation, wherein the primary condensation obtains the product perfluorohexane, and the secondary condensation recovers hexafluoropropylene for the circulation reaction.

2. The method for preparing perfluorohexane according to claim 1, characterized in that: The molar ratio of hexafluoropropylene to fluorine gas in the fluorine-containing gas in step S1 is (2-6):1, and the fluorine-containing gas is a mixture of fluorine gas and an inert gas, and the inert gas accounts for 40-70 vol% of the total amount of hexafluoropropylene and the fluorine-containing gas.

3. The method for preparing perfluorohexane according to claim 1, characterized in that: The temperature of the mixing reaction in step S1 is 10 to 200° C., and the pressure is -0.05 to 0.3 MPa.

4. The method for preparing perfluorohexane according to claim 1, characterized in that: The alkali solution for the primary alkali washing and the secondary alkali washing in step S2 is any one of sodium hydroxide and potassium hydroxide.

5. The method for preparing perfluorohexane according to claim 1, characterized in that: The adsorbent for removing moisture in step S2 is any one of 3A, 4A, 5A and Na-X zeolite.

6. A perfluorohexane preparation device, based on the perfluorohexane preparation method according to any one of claims 1 to 5, characterized in that: The invention comprises a reaction tower (3), a buffer tank (4), a primary alkali washing tower (5), a secondary alkali washing tower (6), a drying tower (7), a first cold trap (9) and a first cold trap (12); the reaction tower (3), the buffer tank (4), the primary alkali washing tower (5), the secondary alkali washing tower (6), the drying tower (7), the first cold trap (9) and the first cold trap (12) are connected in sequence through a pipeline.

7. The method for preparing perfluorohexane according to claim 6, characterized in that: The reaction tower (3) is filled with a filler, the filler is a metal ring, and the material of the metal ring is any one of nickel and monel; the side of the reaction tower (3) is provided with a hexafluoropropylene gas inlet (1) and a fluorine-containing gas inlet (2).

8. The method for preparing perfluorohexane according to claim 6, characterized in that: The first cold trap (9) has a first cold trap column (10) at the upper part and a first tower kettle (11) at the lower part, and the first cold trap column (10) and the first tower kettle (11) are connected; the second cold trap (12) has a second cold trap column (13) at the upper part and a second tower kettle (14) at the lower part, and the second cold trap column (13) and the second tower kettle (14) are connected, and the upper end of the second cold trap (12) is also provided with a gas outlet (15).

9. The method for preparing perfluorohexane according to claim 8, characterized in that: The temperature of the first cold trap column (10) is -25 to 20°C, and the temperature of the first tower bottom (11) is 0 to 40°C; the temperature of the second cold trap column (13) is -90 to -40°C, and the temperature of the second tower bottom (14) is -50 to -30°C.

Images