Perfluoro-3-methyl-2-pentene as well as preparation method and application thereof

Abstract

The invention discloses perfluoro-3-methyl-2-pentene and a preparation method and application thereof.The preparation method comprises the steps that under the action of a catalyst, tetrafluoroethylene is heated for a tetrafluoroethylene trimerization reaction, after the reaction is finished, an obtained gas product is condensed and rectified, and perfluoro-3-methyl-2-pentene is obtained; wherein the catalyst is a fluoride salt catalyst. The fluoride salt catalyst is preferably a fluorinated quaternary ammonium salt catalyst or a fluorinated chlorate salt catalyst. According to the invention, the fluorinated salt catalyst with high catalytic activity, especially the fluorinated quaternary ammonium salt catalyst, is adopted to catalyze tetrafluoroethylene to carry out tetrafluoroethylene trimerization reaction, and the conversion rate of tetrafluoroethylene and the selectivity of perfluoro-3-methyl-2-pentene are both high by controlling the reaction conditions. Compared with a general tetrafluoroethylene oligomerization method, the method provided by the invention has the advantages of high yield of perfluoro-3-methyl-2-pentene, long service life of the catalyst, no solvent, small amount of three wastes, simple operation and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of fluorine chemical industry, and in particular to perfluoro-3-methyl-2-pentene and a preparation method and application thereof. Background Art

[0002] Internet Data Center (IDC) is a hardware facility center used to store Internet data. Data centers consume a lot of energy. In data centers, heat dissipation accounts for a huge proportion of power consumption. In order to save heat dissipation costs, many international Internet giants will build data centers in relatively cold places. As data centers develop towards large-scale and high-density, high energy consumption and strong heat dissipation problems have become unprecedented challenges facing data centers, and traditional air cooling technology can no longer meet the requirements.

[0003] Liquid cooling technology has become a revolutionary technology to solve the heat dissipation problem of data centers. Liquid-cooled data centers have a large demand for coolant, and it is expected that the demand for 10,000 tons of coolant will be met in the next 3-5 years. As the market's requirements for fluorinated liquids in terms of price and environmental protection become more and more stringent, fluorinated liquids are developing towards low GWP and low prices.

[0004] At present, the immersion coolants on the market mainly include hydrocarbons (mineral oil, etc., the advantages are non-volatile, low price, and environmentally friendly; the disadvantages are flash point, flammability, low chemical stability, decomposition products will corrode equipment, and high viscosity), silicones (cetyl polydimethylsiloxane, the advantages are good temperature resistance, stability and contact safety; the disadvantages are high viscosity, poor fluidity, flash point, and residue after volatilization) and fluorocarbons (hydrofluoroethers, perfluoropolyethers, fluorinated olefins and perfluoroamines, the advantages are no flash point, non-toxicity, low viscosity, and no residue after volatilization; the disadvantages are high cost and high GWP values ​​of some types). Fluorocarbon compounds are currently the mainstream immersion coolants.

[0005] Among these fluorocarbon products, hydrofluoric saturated compounds (such as hydrofluorocarbons and hydrofluoroethers) have high dielectric constants and high GWP values; hydrofluoric unsaturated compounds (hydrofluoroolefins and unsaturated hydrofluoroethers) have high dielectric constants and low insulation properties; perfluoro saturated compounds (such as perfluoroalkanes, perfluoroamines, and perfluoropolyethers) have high GWP values. Only perfluoro unsaturated compounds can take into account low dielectric constants, good insulation properties, and low GWP values. Currently, perfluoro alkenyl amines and perfluoro alkenyl ethers among perfluoro unsaturated compounds are difficult to synthesize and have high cost prices. Perfluoro olefins have the advantages of easy synthesis and low cost. Therefore, perfluoro olefins will become a new generation of immersion liquid coolants.

[0006] Compared with other types of dielectric insulating liquids, including mineral oil, fluorinated fluids have many significant advantages: fluorinated fluids are less toxic, non-flammable, and have the boiling point and thermal stability required for two-phase immersion cooling operations, making them more operator-friendly; in addition, electronic equipment removed from fluorinated fluids is clean and dry, making care and maintenance simple.

[0007] Immersion liquid cooling uses coolant as the heat transfer medium, completely immerses the heat generating device in the coolant, and performs heat exchange through direct contact. Depending on whether the coolant undergoes phase change, immersion liquid cooling is divided into single-phase immersion liquid cooling and two-phase immersion liquid cooling. Two-phase immersion liquid cooling exponentially improves the heat transfer efficiency of the coolant through the boiling and condensation process. It relies on the latent heat of evaporation of the coolant and is a cooling method with higher efficiency than single-phase cooling.

[0008] At present, there are few patents and documents for the preparation of perfluoro-3-methyl-2-pentene. U.S. Patent No. 4377717 discloses a method for preparing perfluoro-2-methyl-2-pentene by gas-phase catalytic polymerization of hexafluoropropylene, using activated carbon as a catalyst, a reaction temperature of 410-420°C, a residence time of 13 seconds, a yield of 29.6%, and a selectivity of 64.5%. This method has a high reaction temperature, and a low reaction conversion rate and selectivity.

[0009] CN107473929B discloses a method for preparing perfluoro-2-methyl-2-pentene and perfluoro-4-methyl-2-pentene by oligomerization of hexafluoropropylene. The method uses one, two or more combinations of CsF, NaF, LiF, KF and RbF as catalysts, and one, two or more combinations of N,N-dimethylformamide, N,N-dimethylacetamide, cyclopentane, acetonitrile, tetrahydrofuran, dimethyl sulfoxide, diethylene glycol diethyl ether, diethylene glycol dimethyl ether, ethylene glycol diethyl ether and propylene glycol dimethyl ether as solvents to achieve the co-production of perfluoro-2-methyl-2-pentene and perfluoro-4-methyl-2-pentene. However, the method is an intermittent reaction operation, and the production efficiency is low.

[0010] CN1044786538B discloses a method for preparing perfluoro-2-methyl-2-pentene. The method uses a metal fluoride salt as a main catalyst, a guanidine compound as a co-catalyst, a polar aprotic solvent as a medium, and hexafluoropropylene as a raw material to prepare perfluoro-2-methyl-2-pentene. The yield of perfluoro-2-methyl-2-pentene in the method is about 95-98%, but the reaction time of the method is long and the co-catalyst is difficult to recycle.

[0011] US5387728 discloses a method for preparing perfluoro-4-methyl-2-pentene by liquid phase catalytic polymerization of hexafluoropropylene, wherein perfluoro-4-methyl-2-pentene is prepared by intense stirring reaction at 30-40°C in the presence of non-polar solvents such as diethylene glycol diethyl ether, tetrahydrofuran and acetonitrile, using amine compounds such as N,N,N',N'-tetramethylethylenediamine and fluorides such as potassium fluoride and cesium fluoride as catalysts. The catalyst solvent system of this method is complex, the product separation is difficult, and the stirring dynamic seal is prone to leakage under high pressure.

[0012] CN1876611A discloses a method for preparing hexafluoropropylene dimer by using non-polar solvent acetonitrile as solvent and potassium thiocyanate as catalyst at 10-50°C. This patent also discloses a reaction device for preparing hexafluoropropylene dimer, in which a crank connecting rod drives the reciprocating motion, so that the material is well stirred and dynamic sealing is avoided. Although this device can stir the material well, it is not conducive to industrial scale-up.

[0013] US4377717A discloses a method for producing perfluoro-2-methylpentene-2, which uses activated carbon as a catalyst and continuously passes perfluoropropylene vapor through the activated carbon at high temperature. The reaction temperature is 250-500°C and the product yield is 65-75%. The reaction temperature involved in this method is relatively high and the yield is relatively low.

[0014] CN113999362B discloses a polyurethane rigid foam and a preparation method thereof, wherein perfluoro-3-methyl-2-pentene is used as a low-conductivity additive and polyisocyanate is stirred and emulsified at high speed to form a stable fluorine liquid two-phase. This patent does not involve a preparation method of perfluoro-3-methyl-2-pentene.

[0015] CN111647191B discloses a low-conductivity foaming agent composition and a polyurethane rigid foam prepared therefrom, wherein the foaming agent composition is composed of cyclopentane, 1,1,1,2,2,3-hexafluoropropane and perfluoro-3-methyl-2-pentene. Similarly, the patent does not involve a method for preparing perfluoro-3-methyl-2-pentene.

[0016] CN116004331A discloses a combined solvent and its application, wherein one or more of perfluoro-3-methyl-2-pentene, perfluoro-2-methyl-2-pentene and (Z)-perfluoro-3-methyl-2-pentene are compounded with ethylene dichloride, which not only has good dissolution and removal capabilities for organic pollutants such as mineral oil, synthetic oil, rosin soldering flux and silicone oil, but also has good compatibility with rubber and plastic materials, and will not produce swelling effect on the material matrix, affecting the normal use of electronic devices. Similarly, this patent does not involve the preparation method of perfluoro-3-methyl-2-pentene. Summary of the invention

[0017] The purpose of the present invention is to provide a method for preparing perfluoro-3-methyl-2-pentene, which has the advantages of low synthesis cost, green environmental protection, non-toxicity, etc., and can be produced in batches. The produced perfluoro-3-methyl-2-pentene can be used as a coolant for liquid-cooled data centers.

[0018] The first aspect of the present invention provides a method for preparing perfluoro-3-methyl-2-pentene, comprising the following steps:

[0019] Under the action of a catalyst, tetrafluoroethylene is heated to carry out a tetrafluoroethylene trimerization reaction. After the reaction is completed, the obtained gas product is condensed and distilled to obtain perfluoro-3-methyl-2-pentene; wherein the catalyst is a fluoride salt catalyst.

[0020] Tetrafluoroethylene undergoes anionic polymerization under the action of fluoride salt catalyst, and tetrafluoroethylene trimerization occurs to generate perfluoro-3-methyl-2-pentene. The specific reaction formula is as follows:

[0021]

[0022] Preferably, the fluoride salt catalyst is a quaternary ammonium fluoride catalyst or a fluoride chloride catalyst, and preferably a quaternary ammonium fluoride catalyst. The fluoride ion of the quaternary ammonium fluoride catalyst is more active than other catalysts, so that the conversion rate of the raw material and the selectivity of the target product are higher.

[0023] Preferably, the quaternary ammonium fluoride catalyst is prepared by the following method:

[0024] The carrier is impregnated with a quaternary ammonium salt solution, filtered, and a quaternary ammonium salt catalyst precursor is obtained. The quaternary ammonium salt catalyst precursor is then fluorinated to obtain the fluorinated quaternary ammonium salt catalyst.

[0025] Preferably, the quaternary ammonium salt is a quaternary ammonium chloride, including at least one of tetrabutylammonium chloride, tetrabutylammonium bromide, tetramethylammonium chloride, tetramethylammonium bromide, tetraethylammonium chloride, tetraethylammonium bromide, tetrapropylammonium chloride, tetrapropylammonium bromide, trimethylhexadecylammonium chloride, trimethylhexadecylammonium bromide, trioctylmethylammonium chloride, trioctylmethylammonium fluoride, tetramethylammonium fluoride, tetrabutylammonium fluoride or tetraethylammonium fluoride. The use of quaternary ammonium chloride as an active component to prepare a catalyst can make the tetrafluoroethylene trimerization reaction have a higher reaction rate.

[0026] Preferably, the solvent of the quaternary ammonium salt solution is at least one of methanol, ethanol, acetonitrile or methyl tert-butyl ether.

[0027] Preferably, the carrier is alumina or activated carbon. Alumina carrier is preferred.

[0028] Preferably, the diameter of the alumina particles is 0.04-5 mm and the specific surface area is 10-200 m 2 More preferably, the diameter of the alumina particles is 0.5-1 mm.

[0029] Preferably, the molar ratio of the quaternary ammonium salt to the carrier is 0.05-0.5:1. If the molar ratio of the quaternary ammonium salt to the carrier is too low, the content of the active component is low and the reaction efficiency is low; if the molar ratio of the two is too high, the surface of the carrier is easily occupied, the carrier does not play a synergistic role, and the product yield is reduced. The present invention controls the molar ratio of the quaternary ammonium salt to the carrier within the above range, so that the tetrafluoroethylene trimerization reaction has a higher reaction efficiency and a higher yield of the target product.

[0030] Preferably, the immersion temperature is 20-50°C, and the immersion time is 1-5 hours. More preferably, the immersion temperature is 40-50°C, and the immersion time is 2-3 hours.

[0031] Preferably, the quaternary ammonium salt catalyst precursor is completely fluorinated with hydrogen fluoride gas. To ensure that the catalyst precursor is completely fluorinated, an excess of hydrogen fluoride gas can be used during the reaction. The completely fluorinated quaternary ammonium salt catalyst has better reaction activity, so that the conversion rate of the raw material and the selectivity of the target product are both higher.

[0032] Preferably, the fluorination is carried out in a fixed bed reactor, and the specific fluorination process is as follows: first, the quaternary ammonium salt catalyst precursor is filled into the fixed bed reactor, and then the temperature is raised to 120-150° C., and then hydrogen fluoride gas is introduced to fluorinate the quaternary ammonium salt catalyst precursor, the fluorination temperature is 150-180° C., the residence time of hydrogen fluoride gas in the catalyst bed is 2-5 min, and the introduction time of hydrogen fluoride gas is 2-3 h. Under this condition, the quaternary ammonium salt catalyst precursor (including the carrier) can be completely fluorinated, and in the catalyst fluorination process, no water condenses in the tail gas, which can be considered as complete fluorination.

[0033] More preferably, the fluorination temperature is 160-170°C.

[0034] Preferably, before fluorinating the quaternary ammonium salt catalyst precursor, the temperature of the fixed bed reactor is first raised to 80-100° C. and purged with nitrogen for 20-30 minutes to remove impurities and moisture on the catalyst surface and a small amount of residual methanol.

[0035] Preferably, after the fluorination is completed, the introduction of hydrogen fluoride gas is stopped, the residual hydrogen fluoride gas is replaced with nitrogen, and the temperature is lowered for standby use. After the fluorination is completed, the residual HF is replaced with nitrogen to avoid interference of HF with subsequent reactions.

[0036] Preferably, when tetrafluoroethylene trimerization is carried out using the quaternary ammonium fluoride catalyst prepared by the present invention, the quaternary ammonium fluoride catalyst is first filled into a reactor, and then the reactor is heated, and a small flow of nitrogen is introduced during the heating process to remove hydrogen fluoride remaining on the catalyst surface. After reaching the reaction temperature, the nitrogen is turned off, tetrafluoroethylene is introduced, and tetrafluoroethylene trimerization is carried out.

[0037] Preferably, the mass ratio of the fluoride salt catalyst to tetrafluoroethylene is 0.05-0.5:1.

[0038] Preferably, the tetrafluoroethylene trimerization reaction is carried out in a fixed bed reactor.

[0039] Preferably, the temperature of the tetrafluoroethylene trimerization reaction is 60-120°C, the pressure is 0.2-1.5MPa, and the tetrafluoroethylene residence time is 10-60min. The present invention controls the conditions of the tetrafluoroethylene trimerization reaction within the above range, and the yield of the target product is high. More preferably, the temperature of the tetrafluoroethylene trimerization reaction is 70-90°C, the pressure is 0.2-0.4MPa, and the tetrafluoroethylene residence time is 10-20min.

[0040] The second aspect of the present invention provides perfluoro-3-methyl-2-pentene prepared by the above preparation method.

[0041] The third aspect of the present invention provides the use of the perfluoro-3-methyl-2-pentene as a coolant for a liquid-cooled data center. The perfluoro-3-methyl-2-pentene of the present invention has similar coolant properties to perfluoro-2-methyl-2-pentene and perfluoro-4-methyl-2-pentene, and has the advantages of low synthesis cost, green environmental protection, and non-toxicity, and is suitable for use as a fluorinated liquid in a phase change immersion liquid cooling system of a data center.

[0042] Compared with the prior art, the present invention has at least the following beneficial effects:

[0043] (1) The present invention uses a fluoride salt catalyst with high catalytic activity, especially a quaternary ammonium fluoride catalyst, to catalyze tetrafluoroethylene for tetrafluoroethylene trimerization to prepare perfluoro-3-methyl-2-pentene, and controls the reaction conditions to achieve high conversion rates of tetrafluoroethylene and high selectivity of target products. The method of the present invention can achieve a conversion rate of tetrafluoroethylene of more than 98% and a selectivity of perfluoro-3-methyl-2-pentene of more than 86%.

[0044] (2) The present invention prepares perfluoro-3-methyl-2-pentene through tetrafluoroethylene trimerization. Compared with the general tetrafluoroethylene polymerization method, the present invention has the advantages of high perfluoro-3-methyl-2-pentene yield, long catalyst service life, no solvent, small amount of three wastes, simple operation, etc. DETAILED DESCRIPTION

[0045] Example 1

[0046] Dissolve 115g of tetramethylammonium chloride in 200g of anhydrous methanol, add 142g of 1-3mm alumina balls, keep the impregnation temperature at 45°C, and the impregnation time is 2.5h. After the impregnation is completed, filter out the excess methanol with a funnel and pour the alumina balls into the tubular reactor. Turn on the heating, control the bed temperature to 90°C, and pass nitrogen at the same time. The nitrogen flow rate is 100mL / min, and it is kept at 90°C for 30min. The bed temperature is raised to 130°C, the nitrogen is stopped, and the anhydrous HF gas is switched for fluorination. Control the HF residence time for 5min, the bed temperature is 162°C, and the fluorination time is 2.5h. After the tail gas is condensed without water, the fluorination is considered complete. After the fluorination is completed, switch to nitrogen for purging, keep the nitrogen flow rate at 100mL / min, and reduce the reactor bed temperature to 80°C. When the temperature is 80°C, turn off the nitrogen, switch to tetrafluoroethylene feed, and control the tetrafluoroethylene residence time to 12min. The back pressure valve at the reactor outlet was opened to maintain the pressure in the reactor at 0.25 MPa. The tail gas was condensed by a -15°C ice machine, and then the condensate was distilled to obtain the target product perfluoro-3-methyl-2-pentene. The condensate was collected and analyzed by gas chromatography, and the data are shown in Table 1.

[0047] Example 2

[0048] Dissolve 291g of tetrabutylammonium chloride in 208g of anhydrous methanol, add 146g of 1-3mm alumina balls, keep the impregnation temperature at 45°C, and the impregnation time is 3h. After the impregnation is completed, filter out the excess methanol with a funnel and pour the alumina balls into the tubular reactor. Turn on the heating, control the bed temperature to 90°C, and pass nitrogen at the same time. The nitrogen flow rate is 100mL / min, and it is kept at 90°C for 30min. The bed temperature is raised to 100°C, the nitrogen is stopped, and the anhydrous HF gas is switched for fluorination. Control the HF residence time for 5min, the bed temperature at 140°C, and the fluorination time for 2.5h. After the tail gas is condensed without water, the fluorination is considered complete. After the fluorination is completed, switch to nitrogen for purging, keep the nitrogen flow rate at 100mL / min, and reduce the reactor bed temperature to 85°C. When the temperature is 85°C, turn off the nitrogen, switch to tetrafluoroethylene feed, and control the tetrafluoroethylene residence time to 15min. The back pressure valve at the reactor outlet was opened to maintain the pressure in the reactor at 0.25 MPa. The tail gas was condensed by a -15°C ice machine, and then the condensate was distilled to obtain the target product perfluoro-3-methyl-2-pentene. The condensate was collected and analyzed by gas chromatography, and the data are shown in Table 1.

[0049] Example 3

[0050] Dissolve 54g of tetramethylammonium bromide in 251g of anhydrous methanol, add 189g of 1-3mm alumina balls, keep the impregnation temperature at 50°C, and the impregnation time is 3h. After the impregnation is completed, filter out the excess methanol with a funnel and pour the alumina balls into the tubular reactor. Turn on the heating, control the bed temperature to 95°C, and introduce nitrogen at the same time. The nitrogen flow rate is 100mL / min, and it is maintained at 90°C for 30min. The bed temperature is raised to 140°C, the nitrogen is stopped, and the anhydrous HF gas is switched for fluorination. Control the HF residence time for 7min, the bed temperature at 180°C, and the fluorination time for 2.5h. After the tail gas is condensed without water, the fluorination is considered complete. After the fluorination is completed, switch to nitrogen for purging, and the nitrogen flow rate is maintained at 100mL / min, while the reactor bed temperature is reduced to 90°C. When the temperature is 90°C, turn off the nitrogen, switch to tetrafluoroethylene feed, and control the tetrafluoroethylene residence time to 12min. The back pressure valve at the reactor outlet was opened to maintain the pressure in the reactor at 0.4 MPa. The tail gas was condensed by a -15°C ice machine, and then the condensate was distilled to obtain the target product perfluoro-3-methyl-2-pentene. The condensate was collected and analyzed by gas chromatography, and the data are shown in Table 1.

[0051] Comparative Example 1

[0052] Add 142g of 1-3mm alumina balls to 200g of anhydrous methanol, keep the impregnation temperature at 45°C, and the impregnation time is 2.5h. After the impregnation is completed, filter out the excess methanol with a funnel and pour the alumina balls into a tubular reactor. Turn on the heating, control the bed temperature to 90°C, and introduce nitrogen at the same time. The nitrogen flow rate is 100mL / min, and it is maintained at 90°C for 30min. The bed temperature is raised to 130°C, the nitrogen is stopped, and the anhydrous HF gas is switched for fluorination. Control the HF residence time for 5min, the bed temperature at 162°C, and the fluorination time for 2.5h. After the tail gas is condensed without water, the fluorination is considered complete. After the fluorination is completed, switch to nitrogen for purging, keep the nitrogen flow rate at 100mL / min, and reduce the reactor bed temperature to 80°C. When the temperature is 80°C, turn off the nitrogen, switch to tetrafluoroethylene feed, and control the tetrafluoroethylene residence time to 12min. The back pressure valve at the reactor outlet was opened to maintain the pressure in the reactor at 0.25 MPa. The tail gas was condensed by a -15°C ice machine, and then the condensate was distilled to obtain the target product perfluoro-3-methyl-2-pentene. The condensate was collected and analyzed by gas chromatography, and the data are shown in Table 1.

[0053] Comparative Example 2

[0054] Dissolve 58g of potassium fluoride in 500g of anhydrous methanol, add 300g of 1-3mm alumina balls, keep the impregnation temperature at 45°C, and the impregnation time is 2.5h. After the impregnation is completed, filter out the excess methanol with a funnel and pour the alumina balls into a tubular reactor. Turn on the heating, control the bed temperature to 90°C, and pass nitrogen at the same time. The nitrogen flow rate is 100mL / min, and it is kept at 90°C for 30min. The bed temperature is raised to 130°C, the nitrogen is stopped, and the anhydrous HF gas is switched for fluorination. Control the HF residence time for 5min, the bed temperature is 162°C, and the fluorination time is 2.5h. After the tail gas is condensed without water, the fluorination is considered complete. After the fluorination is completed, switch to nitrogen for purging, keep the nitrogen flow rate at 100mL / min, and reduce the reactor bed temperature to 80°C. When the temperature is 80°C, turn off the nitrogen, switch to tetrafluoroethylene feed, and control the tetrafluoroethylene residence time to 12min. The back pressure valve at the reactor outlet was opened to maintain the pressure in the reactor at 0.25 MPa. The tail gas was condensed by a -15°C ice machine, and then the condensate was distilled to obtain the target product perfluoro-3-methyl-2-pentene. The condensate was collected and analyzed by gas chromatography, and the data are shown in Table 1.

[0055] Table 1

[0056]

Claims

1. A method for preparing perfluoro-3-methyl-2-pentene, characterized in that: The following steps are involved: Under the action of a catalyst, tetrafluoroethylene is heated to carry out a tetrafluoroethylene trimerization reaction. After the reaction is completed, the obtained gas product is condensed and distilled to obtain perfluoro-3-methyl-2-pentene; wherein the catalyst is a fluoride salt catalyst.

2. The method according to claim 1, characterized in that: The fluoride salt catalyst is a quaternary ammonium fluoride salt catalyst or a fluoride chloride salt catalyst.

3. The method according to claim 2, characterized in that The quaternary ammonium fluoride catalyst is prepared by the following method: The carrier is impregnated with a quaternary ammonium salt solution, filtered, and a quaternary ammonium salt catalyst precursor is obtained. The quaternary ammonium salt catalyst precursor is then fluorinated to obtain the fluorinated quaternary ammonium salt catalyst.

4. The method according to claim 3, characterized in that The quaternary ammonium salt is a quaternary ammonium chloride, including at least one of tetrabutylammonium chloride, tetrabutylammonium bromide, tetramethylammonium chloride, tetramethylammonium bromide, tetraethylammonium chloride, tetraethylammonium bromide, tetrapropylammonium chloride, tetrapropylammonium bromide, trimethylhexadecylammonium chloride, trimethylhexadecylammonium bromide, trioctylmethylammonium chloride, trioctylmethylammonium fluoride, tetramethylammonium fluoride, tetrabutylammonium fluoride or tetraethylammonium fluoride; the carrier is alumina or activated carbon; the molar ratio of the quaternary ammonium salt to the carrier is 0.05-0.5:

1.

5. The method according to claim 3, characterized in that: The quaternary ammonium salt catalyst precursor is completely fluorinated by hydrogen fluoride gas.

6. The method according to claim 3, characterized in that The fluorination is carried out in a fixed bed reactor, and the fluorination process is as follows: first, a quaternary ammonium salt catalyst precursor is filled into the fixed bed reactor, and then the temperature is raised to 120-150° C., and then hydrogen fluoride gas is introduced to fluorinate the quaternary ammonium salt catalyst precursor. The fluorination temperature is 150-180° C., the residence time of the hydrogen fluoride gas in the catalyst bed is 2-5 minutes, and the introduction time of the hydrogen fluoride gas is 2-3 hours.

7. The method according to claim 1, characterized in that The mass ratio of the fluoride salt catalyst to tetrafluoroethylene is 0.05-0.5:

1.

8. The method according to claim 1, characterized in that The temperature of the tetrafluoroethylene trimerization reaction is 60-120° C., the pressure is 0.2-1.5 MPa, and the tetrafluoroethylene residence time is 10-60 min.

9. Perfluoro-3-methyl-2-pentene prepared according to the method of any one of claims 1 to 8.

10. Use of the perfluoro-3-methyl-2-pentene according to claim 9 as a coolant for a liquid-cooled data center.

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