Method for preparing and purifying perfluorohexane

Abstract

The invention provides a novel process route for preparing perfluorohexane (C6F14), and the preparation method comprises the following steps: diluting fluorine gas with inert gas to obtain first mixed gas, and mixing hexafluoropropylene dimer (C6F12) with perfluorinated liquid to obtain first mixed liquid; the first mixed gas and the first mixed solution are treated through a microchannel reactor and then transferred into a reaction kettle, a product in the reaction kettle is collected, the product is separated, and the crude perfluorohexane product is obtained. The problems that in the prior art, the C6F14 preparation process is complex, and the conversion rate is low are solved. On the other hand, the invention discloses a purification method for obtaining a high-purity C6F14 finished product. The conversion rate and the purity of the perfluorohexane obtained by the scheme of the invention are obviously improved.

Description

Technical Field

[0001] This invention relates to the field of fluorinated liquid preparation and purification, and particularly to a method for preparing and purifying perfluorohexane. Background Technology

[0002] Perfluorohexane is an important perfluorocarbon compound with chemical inertness, high thermal stability, excellent electrical insulation, low surface tension, and outstanding ability to dissolve and carry oxygen. Based on these unique properties, perfluorohexane has broad application prospects in many high-tech and specialty industrial fields, such as: as a cleaning agent for precision components in the electronics industry; an intermediate in the production of high-end fluorinated oils and fluororubbers; a core component in ultrasound contrast agents or artificial blood substitutes in the medical field; and a cooling medium or heat-conducting fluid in special environments.

[0003] Patent No. CN 119552048 A discloses a method and apparatus for preparing perfluorohexane. In the disclosed technical solution, hexafluoropropylene and a fluorine-containing gas are mixed and reacted to obtain crude perfluorohexane. The crude perfluorohexane is then subjected to a primary alkaline wash and a secondary alkaline wash, followed by water removal. Finally, it undergoes a primary condensation and a secondary condensation. The primary condensation yields the product perfluorohexane, while the secondary condensation recovers hexafluoropropylene for recycling. The preparation apparatus of this application includes a reaction tower, a buffer tank, a primary alkaline wash tower, a secondary alkaline wash tower, a drying tower, a first cold trap, and a second cold trap, connected in sequence. During purification, the crude perfluorohexane product is separated by condensation, and then undergoes defluorination (removing substances with strong oxidizing or corrosive properties remaining from the fluorination reaction, such as excess fluorine, oxygen difluoride, and hydrogen fluoride), deep dehydration, and distillation to separate the small amount of cracked and polymerized CF4, C2F6, and C4F from the fluorination reaction. 10 C8F 18 And to separate the remaining small amount of C3F8 to obtain high-purity C6F. 14 .

[0004] In existing methods for preparing perfluorohexane from hexafluoropropylene, the selectivity of perfluorohexane is not high, with experiments showing that the yield is usually between 20% and 25%. This is because the method produces a lot of byproducts, has a complex process, and results in a low yield. Summary of the Invention

[0005] The main objective of this invention is, on the one hand, to propose a novel method for preparing perfluorohexane, thereby overcoming the challenges posed by the complex processes and C6F content limitations in existing technologies for preparing perfluorohexane. 14 To address the issue of low yield, a purification method is disclosed to obtain high-purity C6F. 14 Finished product.

[0006] Methods for preparing perfluorohexane include: S1. Dilute fluorine gas with an inert gas to obtain a first mixed gas, C6F.12 The mixture is mixed with a perfluorofluorinated liquid to obtain a first mixture. S2. The first mixed gas and the first mixed liquid are first processed through a microchannel reactor, then transferred to a reaction vessel, and the products in the reaction vessel are collected. The products are then separated to obtain crude perfluorohexane.

[0007] This process is simple, produces low levels of byproducts, and facilitates subsequent separation.

[0008] Preferably, the inert gas is one of nitrogen, argon, helium or neon with a purity ≥99.99%, the fluorine gas has a purity ≥99.95%, the first mixed gas has a purity of 15~25% based on the volume percentage of the fluorine gas, and the perfluorinated liquid is at least one of FC-40, perfluoropolyether or Y-type PFPE oil.

[0009] Based on the volume percentage of fluorine gas, when the purity reaches 15-30%, the conversion rate of perfluorohexane is high. This is because the inert gas absorbs the heat of reaction, reduces the reactivity, makes the reaction temperature more moderate, and reduces the formation of by-products.

[0010] Preferably, during the mixing process of the inert gas and the fluorine gas, the mass flow rate of the inert gas is 0.16~2.64 kg / h, and the mass flow rate of the fluorine gas is 0.223~0.894 kg / h. The C6F 12 During the mixing process with the perfluorofluorinated liquid, the C6F is introduced. 12 The mass flow rate is 1.6~6.41 kg / h, and its purity is ≥99.9%, while the mass flow rate of the perfluorinated liquid is 0.7 kg / h; During the process of introducing the first mixed gas and the first mixed liquid into the microchannel reactor, the mass flow rate of the first mixed gas is 0.383~3.534 kg / h, and the mass flow rate of the first mixed liquid is 2.3~7.11 kg / h; During the process of feeding the reactants from the microchannel reactor into the reaction vessel, the mass flow rate of the reactants is 2.25~5.55 kg / h.

[0011] Preferably, the reaction temperature in the reactor is -15 to 30°C and the pressure is 0.01 to 1 MPa.

[0012] Preferably, after the reaction in the reactor is completed, the product is sent to a separator, and the temperature in the separator is controlled at 0 to -10 °C to separate inert gas and fluorine gas.

[0013] Use C6F 12 Synthesis of C6F by fluorination with F214 During the synthesis process, the content of the byproduct C3F8 decreased, thereby increasing the content of the target product C6F. 14 The conversion rate was improved, increasing the selectivity to over 90%, which simplified the entire preparation process, eliminating the need for excessive separation steps. Diluting F2 with an inert gas reduced the reactivity and, through the C6F... 12 The mixed fluorinated liquid can quickly remove the heat of reaction during the reaction, reducing the generation of cracking byproducts.

[0014] Before feeding the reactants into the reactor, they are first fed into a microchannel reactor for pre-reaction to improve the mixing effect and further enhance heat dissipation. Furthermore, the reaction conditions in this technical solution are optimized to ensure the reaction proceeds under mild temperature and pressure, reducing energy consumption and improving operational safety.

[0015] On the other hand, a method for purifying perfluorohexane was disclosed: crude C6F... 14 The solution is fed into a water washing tower at a mass flow rate of 10 kg / h for washing, followed by dehydration in a dehydration adsorber at a mass flow rate of 10 kg / h, and finally distilled in a distillation column at a mass flow rate of 10 kg / h to remove the perfluorinated liquid, yielding the final product C6F. 14 The perfluorofluorinated liquid can be re-reacted with the C6F 12 Mix and reuse.

[0016] Preferably, the pH of the water washing tower is controlled between 11 and 14 to wash away residual F2 and HF from the reaction.

[0017] Preferably, the pressure inside the dehydration adsorber is 0~0.1 MPa, the temperature is maintained at 60~90℃, and the adsorbent used in the dehydration adsorber is sodium lime, 3A, 5A, or XH-11.

[0018] Preferably, the top condensation temperature of the distillation column is 0~30 ℃, the bottom vaporization temperature is 60~180 ℃, and the pressure inside the column is 0.01~1 MPa.

[0019] The crude perfluorohexane product generated in the preparation process enters the distillation system. First, it passes through a water washing tower to remove F2 and HF, then enters a dehydration adsorber for dehydration, and finally enters a distillation column for further distillation to obtain C6F with a purity of 99.99%. 14 This process is suitable for continuous industrial production. The distillation process is simple, and the obtained C6F... 14 It has high purity, meeting the demand for high-purity C6F14 fluorinated liquid in the high-end electronics and precision instrument fields. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0021] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

[0022] Figure 1 This is a reaction flow diagram of the present invention; Figure 2 This is a distillation process flow diagram of the present invention. Detailed Implementation

[0023] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of this application can be combined with each other. At the same time, the raw materials mentioned below that are not described in detail are all commercially available products; the method steps or synthesis methods not mentioned in detail are all method steps or synthesis methods known to those skilled in the art.

[0024] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

[0025] This invention discloses a method for preparing perfluorohexane, comprising the following steps: Solving C6F in existing technologies 14 To address the issue of low conversion rates, a purification method is disclosed to obtain high-purity (perfluorohexane) C6F. 14 Finished product.

[0026] like Figure 1 As shown, the preparation method of perfluorohexane is as follows: S1. First, nitrogen gas with a mass flow rate of 0.16~2.64 kg / h and a purity of ≥99.99% is mixed with F2 gas with a mass flow rate of 0.223~0.894 kg / h and a purity of ≥99.95% to obtain a first mixed gas volume. This mixture is then diluted to 15%~50% to reduce the activity of F2 and the intensity of the reaction, thereby reducing the formation of by-products.

[0027] S2, simultaneously using C6F with a mass flow rate of 1.6~6.41 kg / h and a purity ≥99.9%. 12 The mixture is mixed with a perfluorofluorinated liquid with a mass flow rate of 0.7 kg / h to obtain a first mixed liquid. The perfluorofluorinated liquid is FC-40, perfluoropolyether, or Y-type PFPE oil. The high-boiling-point perfluorofluorinated liquid can quickly remove the heat of reaction during the reaction, which greatly reduces the generation of cracking products, reduces the by-products generated by the reaction, and improves the conversion rate of the products.

[0028] S3. Using a mass flow control valve, the first mixed gas is first introduced into a microchannel reactor at a mass flow rate of 0.383~3.534 kg / h and the first mixed liquid at a mass flow rate of 2.3~7.11 kg / h for pre-reaction. Then, they are introduced into the reaction vessel at a mass flow rate of 2.25~5.55 kg / h for further reaction. This step can improve the mixing degree of the raw materials and the heat dissipation effect. During the reaction, the reaction temperature in the reaction vessel is controlled at -15~30 ℃, and the reaction pressure is controlled at 0.01~1 MPa.

[0029] S4. After the product sample from step S3 passes the test, it is sent to a shell-and-tube heat exchanger (separator) to control the condensation temperature at 0 to -10℃ and the pressure at 0 to 0.5MPa. After separating nitrogen and fluorine, crude perfluorohexane is obtained.

[0030] The final crude perfluorohexane product has a purity of up to 75%, with byproducts including CF4, C2F6, and C3F8, and the reaction selectivity can reach over 95%.

[0031] like Figure 2 As shown, the purification process for perfluorohexane is as follows: S1. The crude perfluorohexane product obtained from the above reaction is first fed into a water washing tower at a mass flow rate of 10 kg / h. The pH of the water washing tower is controlled between 14 and 11 to wash away the residual F2 and HF from the reaction.

[0032] S2. After being washed with water, the crude perfluorohexane product is fed into a dehydration adsorber at a mass flow rate of 10 kg / h. The adsorbents used in the dehydration adsorber are soda lime, 3A, 5A, and XH-11. The internal pressure is 0.1~0 MPa, and the temperature is maintained at 60~90℃.

[0033] S3. Subsequently, the material obtained from dehydration in step S2 is introduced into the upper part of the distillation column at a mass flow rate of 10 kg / h. The condensation temperature at the top of the column is controlled at 0~30 ℃, the pressure inside the column is 0.01~1MPa, and the vaporization temperature at the bottom of the column is 60~180 ℃. Nitrogen, oxygen, and perfluorofluorinated liquid are removed, and perfluorohexane with a purity of 99.99% is collected.

[0034] In this article, the purity of a gas refers to its volume fraction. The reaction equipment and models include: Microchannel reactor: Interdigitated microchannel premixed structure + tube wall microreactor Separator: Shell and tube heat exchanger (total heat exchange area 5.3m²) 2 ) Water washing tower: Packed scrubbing tower (packing layer thickness 1000mm * 15 sections) Dehydration Adsorption Tower: 5A Molecular Sieve Adsorber Distillation column: 18000 mm high, 325 mm diameter, 110 trays Detection instrument: GC-2014, equipped with a 30m alumina + 30m GasPro column Comparative Example 1 C6F with a flow rate of 1.6 kg / h and a purity of 99.9% was used. 12 After premixing with FC-40 fluorinated liquid at a flow rate of 0.7 kg / h to obtain a first mixture, it is introduced into a microchannel reactor at a flow rate of 2.3 kg / h along with undiluted F2 with a purity of 99.95% at a flow rate of 0.223 kg / h for pre-reaction. Subsequently, the material in the microchannel reactor is introduced into a reaction vessel at a flow rate of 2.25 kg / h, wherein the pressure of the reaction vessel is 0.05 MPa and the temperature is 15 ℃.

[0035] The reaction product in the reactor is passed into a separator for separation. The temperature inside the separator is controlled at -10℃ to separate the crude perfluorohexane product, as well as nitrogen and fluorine. The crude perfluorohexane product then enters the purification process.

[0036] The crude perfluorohexane product was fed into a water washing tower at a flow rate of 10 kg / h, with controlled circulating spraying to remove F2 and HF components. Subsequently, it was fed into a dehydration adsorber at a flow rate of 10 kg / h, with the internal pressure controlled at 0.05 MPa and temperature at 90 °C. After being washed away by a 5A molecular sieve to remove moisture, it was fed into a distillation column at a flow rate of 10 kg / h. The column's top condensation temperature was 30 °C, the bottom vaporization temperature was 100 °C, and the internal pressure was 0.1 MPa. The final product, C6F, was collected. 14 .

[0037] Example 1 C6F with a flow rate of 1.6 kg / h and a purity of 99.9% was used. 12 A first mixture was obtained by premixing F2 with FC-40 at a flow rate of 0.7 kg / h. F2 with a purity of 99.95% was diluted with nitrogen at a flow rate of 0.16 kg / h to a purity of 50%, resulting in a first mixed gas. The first mixture and the first mixed gas were then introduced into a microchannel reactor at a flow rate of 2.3 kg / h and 0.383 kg / h respectively for pre-reaction. Subsequently, the material from the microchannel reactor was introduced into a reaction vessel at a flow rate of 2.25 kg / h, wherein the pressure of the reaction vessel was 0.05 MPa and the temperature was 15 °C.

[0038] The reaction product in the reactor is passed into a separator for separation. The temperature inside the separator is controlled at -10℃ to separate the crude perfluorohexane product, as well as nitrogen and fluorine. The crude perfluorohexane product then enters the purification process.

[0039] The crude perfluorohexane product was fed into a water washing tower at a flow rate of 10 kg / h, with controlled circulating spraying to remove F2 and HF components. Subsequently, it was fed into a dehydration adsorber at a flow rate of 10 kg / h, with the internal pressure controlled at 0.05 MPa and temperature at 90 °C. After being washed away by a 5A molecular sieve to remove moisture, it was fed into a distillation column at a flow rate of 10 kg / h. The column's top condensation temperature was 30 °C, the bottom vaporization temperature was 100 °C, and the internal pressure was 0.1 MPa. The final product, C6F, was collected. 14 .

[0040] Example 2 C6F with a flow rate of 1.6 kg / h and a purity of 99.9% was used. 12 A first mixed liquid was obtained by premixing F2 with FC-40 at a flow rate of 0.7 kg / h. F2 with a purity of 99.95% was diluted with nitrogen at a flow rate of 0.38 kg / h to a purity of 30%, resulting in a first mixed gas. The first mixed liquid and the first mixed gas were then introduced into a microchannel reactor at a flow rate of 2.3 kg / h and 0.883 kg / h respectively for pre-reaction. Subsequently, the material from the microchannel reactor was introduced into a reaction vessel at a flow rate of 2.25 kg / h, wherein the pressure of the reaction vessel was 0.05 MPa and the temperature was 15 °C.

[0041] The reaction product in the reactor is passed into a separator for separation. The temperature inside the separator is controlled at -10℃ to separate the crude perfluorohexane product, as well as nitrogen and fluorine. The crude perfluorohexane product then enters the purification process.

[0042] The crude perfluorohexane product was fed into a water washing tower at a flow rate of 10 kg / h, with controlled circulating spraying to remove F2 and HF components. Subsequently, it was fed into a dehydration adsorber at a flow rate of 10 kg / h, with the internal pressure controlled at 0.05 MPa and temperature at 90 °C. After being washed away by a 5A molecular sieve to remove moisture, it was fed into a distillation column at a flow rate of 10 kg / h. The column's top condensation temperature was 30 °C, the bottom vaporization temperature was 100 °C, and the internal pressure was 0.1 MPa. The final product, C6F, was collected. 14 .

[0043] Example 3 C6F with a flow rate of 1.6 kg / h and a purity of 99.9% was used. 12 A first mixed liquid was obtained by premixing with FC-40 at a flow rate of 0.7 kg / h. F2 with a purity of 99.95% was diluted with nitrogen at a flow rate of 1.1 kg / h at a flow rate of 0.223 kg / h to achieve a purity of 15%, thus obtaining a first mixed gas. Subsequently, the first mixed liquid and the first mixed gas were introduced into a microchannel reactor at a flow rate of 2.3 kg / h and 1.323 kg / h respectively for pre-reaction. The material from the microchannel reactor was then introduced into a reaction vessel at a flow rate of 3.7 kg / h, wherein the pressure in the reaction vessel was 0.05 MPa and the temperature was 15 °C.

[0044] The reaction product in the reactor is passed into a separator for separation. The temperature inside the separator is controlled at -10℃ to separate the crude perfluorohexane product, as well as nitrogen and fluorine. The crude perfluorohexane product then enters the purification process.

[0045] The crude perfluorohexane product was fed into a water washing tower at a flow rate of 10 kg / h, with controlled circulating spraying to remove F2 and HF components. Subsequently, it was fed into a dehydration adsorber at a flow rate of 10 kg / h, with the internal pressure controlled at 0.05 MPa and temperature at 90 °C. After being washed away by a 5A molecular sieve to remove moisture, it was fed into a distillation column at a flow rate of 10 kg / h. The column's top condensation temperature was 30 °C, the bottom vaporization temperature was 100 °C, and the internal pressure was 0.1 MPa. The final product, C6F, was collected. 14 .

[0046] Example 4 C6F with a flow rate of 6.41 kg / h and a purity of 99.9% was used. 12A first mixed liquid was obtained by premixing with FC-40 at a flow rate of 0.7 kg / h. F2 with a purity of 99.95% was diluted with nitrogen at a flow rate of 0.894 kg / h until the F2 purity reached 20%, thus obtaining a first mixed gas. The first mixed liquid and the first mixed gas were then introduced into a microchannel reactor at a flow rate of 7.11 kg / h and 3.534 kg / h respectively for pre-reaction. Subsequently, the material from the microchannel reactor was introduced into a reaction vessel at a flow rate of 5.55 kg / h, wherein the pressure in the reaction vessel was 0.05 MPa and the temperature was 15 °C.

[0047] The reaction product in the reactor is passed into a separator for separation. The temperature inside the separator is controlled at -10℃ to separate the crude perfluorohexane product, as well as nitrogen and fluorine. The crude perfluorohexane product then enters the purification process.

[0048] The crude perfluorohexane product was fed into a water washing tower at a flow rate of 10 kg / h, with controlled circulating spraying to remove F2 and HF components. Subsequently, it was fed into a dehydration adsorber at a flow rate of 10 kg / h, with the internal pressure controlled at 0.05 MPa and temperature at 90 °C. After being washed away by a 5A molecular sieve to remove moisture, it was fed into a distillation column at a flow rate of 10 kg / h. The column's top condensation temperature was 30 °C, the bottom vaporization temperature was 100 °C, and the internal pressure was 0.1 MPa. The final product, C6F, was collected. 14 .

[0049] Comparative Example 4 The raw material ratios and reaction conditions were the same for Comparative Example 4 and Example 4, but the continuous reaction time was extended to examine the long-term stability and scale-up effect of the process.

[0050] The reaction results generated in Examples 1 to 4 are shown in Table 1. Table 1 In comparison to Comparative Example 1 and Example 1, undiluted F2 and C6F were used in Comparative Example 1. 12 The reaction was carried out to obtain C6F. 14 The yield was 15% because the purity of F2 was too high and its activity too strong, leading to a violent reaction, increased byproducts, and thus significantly reduced the yield of C6F. 14 The yield.

[0051] From Examples 1 to 4, we can see that when the purity of F2 decreases, C6F... 14 The yield and purity of C6F are both increasing. When the purity of F2 is in the range of 15-30%, the yield reaches 92-95%. 14The purity reached 99.99% because the activity of F2 decreased after dilution, the temperature change during the reaction was mild, and the yields of byproducts such as CF4, C2F6, and C3F8 were low, thereby increasing the yield of C6F4. 14 This improves the reaction yield and simultaneously reduces the difficulty of distillation.

[0052] Compared to Example 4, Comparative Example 4 had a longer reaction feed time, but the product yield and purity remained the same. This is because the continuous reaction conditions were mild, making the whole system relatively stable and demonstrating the advantage of easy scale-up of the reaction.

[0053] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A method for preparing perfluorohexane, characterized in that, include: S1. Dilute fluorine gas with an inert gas to obtain a first mixed gas, C6F. 12 The mixture is mixed with a perfluorofluorinated liquid to obtain a first mixture. S2. The first mixed gas and the first mixed liquid are first processed through a microchannel reactor, then transferred to a reaction vessel, and the products in the reaction vessel are collected. The products are then separated to obtain crude perfluorohexane.

2. The method for preparing perfluorohexane according to claim 1, characterized in that, The inert gas is one of nitrogen, argon, helium or neon with a purity ≥99.99%, the fluorine gas has a purity ≥99.95%, the first mixed gas has a purity of 15~30% based on the volume percentage of the fluorine gas, and the perfluorinated liquid is at least one of FC-40, perfluoropolyether or Y-type PFPE oil.

3. The method for preparing perfluorohexane as described in claim 2, characterized in that, During the mixing process of the inert gas and the fluorine gas, the mass flow rate of the inert gas is 0.16~2.64 kg / h, and the mass flow rate of the fluorine gas is 0.223~0.894 kg / h. The C6F 12 During the mixing process with the perfluorofluorinated liquid, the C6F is introduced. 12 The mass flow rate is 1.6~6.41 kg / h, and its purity is ≥99.9%, while the mass flow rate of the perfluorinated liquid is 0.7 kg / h; During the process of introducing the first mixed gas and the first mixed liquid into the microchannel reactor, the mass flow rate of the first mixed gas is 0.383~3.534 kg / h, and the mass flow rate of the first mixed liquid is 2.3~7.11 kg / h; During the process of feeding the reactants from the microchannel reactor into the reaction vessel, the mass flow rate of the reactants is 2.25~5.55 kg / h.

4. The method for preparing perfluorohexane according to any one of claims 1 to 3, characterized in that, The reaction temperature inside the reactor is -15~30℃, and the pressure is 0.01~1 MPa.

5. The method for preparing perfluorohexane as described in claim 4, characterized in that, After the reaction in the reactor is completed, the product is sent to a separator, and the temperature inside the separator is controlled at 0 to -10 °C to separate the inert gas and the fluorine gas to obtain C6F. 14 Crude product.

6. A method for purifying perfluorohexane, characterized in that, Purify the crude perfluorohexane product prepared by any one of the methods described in claims 1 to 5; Includes: the C6F 14 The crude product is fed into a water washing tower for washing, then into a dehydration adsorber for dehydration, and finally into a distillation column for rectification to remove the perfluorinated liquid, yielding the finished product C6F. 14 .

7. The purification method for perfluorohexane as described in claim 6, characterized in that, The pH of the water washing tower is controlled between 11 and 14 to wash away residual F2 and HF from the reaction.

8. The purification method for perfluorohexane as described in claim 7, characterized in that, The pressure inside the dehydration adsorber is 0~0.1 MPa, and the temperature is maintained at 60~90℃. The adsorbent used in the dehydration adsorber is at least one of sodium lime, 3A, 5A or XH-11.

9. The purification method for perfluorohexane as described in claim 8, characterized in that, The top condensation temperature of the distillation column is 0~30 ℃, the bottom vaporization temperature is 60~180 ℃, and the pressure inside the column is 0.01~1 MPa.

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