Purification method of electronic-grade fluorinated liquid

Abstract

The invention relates to the technical field of impurity removal of high-purity chemicals, in particular to a purification method of electronic-grade fluorinated liquid. The purification method comprises the following steps: taking a fluorination liquid raw material, and sequentially carrying out neutralization reaction, impurity removal treatment and rectification treatment to obtain the electronic-grade fluorination liquid. The neutralization reaction comprises the following steps: adding a neutralizer into the fluorination liquid raw material, uniformly mixing, then adding a dispersing aid to obtain a mixed solution, adjusting the pH value of the mixed solution to 7, standing for layering, and taking a subnatant to obtain the fluorination liquid after the neutralization reaction; the impurity removal treatment comprises adsorption impurity removal treatment and gas stripping impurity removal treatment; the rectification treatment is as follows: the fluorinated liquid subjected to impurity removal treatment by the gas stripping tower flows into an intermediate product tank to be stored, and then flows into a rectifying tower to be rectified, so that the electronic-grade fluorinated liquid is obtained. When the purification method is used for purification, a product conforming to electronic-grade fluorination liquid parameters of the 3M company can be obtained.

Description

Technical Field

[0001] This invention relates to the field of high-purity chemical purification technology, specifically to a purification method for electronic-grade fluorinated liquids. Background Technology

[0002] Electronic-grade fluorinated fluids are widely used as stable coolants and electronic testing fluids due to their excellent thermal conductivity, insulation, non-flammability, good chemical inertness, environmental friendliness, extremely low surface tension, ability to penetrate extremely fine pores, and material compatibility. They are currently the most widely used submersible coolants and can be applied to data centers and power supply cooling systems. In summary, electronic-grade fluorinated fluids are widely used in various fields such as electronics, semiconductor manufacturing, defense, aerospace, automotive, machinery, chemical, textile, construction, and pharmaceuticals due to their beneficial properties. Furthermore, electronic-grade fluorinated fluids offer high profit margins.

[0003] China's domestic electronic-grade fluorinated fluids are mainly imported from 3M. While 3M's supply to China is gradually decreasing, electronic-grade fluorinated fluids have wide applications, with huge usage in full-size wafer testing and as coolants. With technological advancements, the market gap is expected to widen annually. Domestically produced electronic-grade fluorinated fluids suffer from problems such as excessive gold impurities, high hydrofluoric acid content, and excessively long boiling ranges. Currently, the purification method for electronic-grade fluorinated fluids mainly involves neutralizing the acid value of the raw material perfluorotributylamine with alkaline substances, followed by distillation purification. However, the parameters of the electronic-grade fluorinated fluid obtained through this purification method differ significantly from those of 3M's product. Therefore, developing an electronic-grade fluorinated fluid whose parameters meet 3M's standards is extremely urgent.

[0004] For example, CN114560758A discloses a purification method for electronic-grade nonafluorobutyl methyl ether. The method is as follows: reagent-grade nonafluorobutyl methyl ether is washed with an alkaline aqueous solution and then adsorbed by an adsorbent molecular sieve to obtain an adsorbed fluorinated liquid; the adsorbed fluorinated liquid is continuously distilled, first in a light component removal column at a temperature of 60℃-70℃, a pressure of 0.1MPa-1MPa, and a reflux ratio of (300-500):1, and then in a heavy component removal column at a temperature of 60℃-100℃, a pressure of 0.1MPa-1MPa, and a reflux ratio of (500-1000):1, to obtain a primary product of nonafluorobutyl methyl ether; after heating to nonafluorobutyl methyl ether vapor, it is filtered through a filter and then introduced into a metal ion-free container through a metal ion-free PFA pipeline to obtain electronic-grade nonafluorobutyl methyl ether. This invention purifies reagent-grade nonafluorobutyl methyl ether to electronic-grade nonafluorobutyl methyl ether. Although this patent incorporates an adsorption purification step during purification, significantly improving the reagent purity of nonafluorobutyl methyl ether, common fluorinated liquid raw materials include perfluorotributylamine, perfluoropolyether, perfluorononenyltrifluoroethyl ether, hydrofluoroether, and light fluorinated oil, etc. This patent only studies the purification method specifically for nonafluorobutyl methyl ether.

[0005] For example, patent CN117085367A discloses a method and apparatus for ion-based impurity removal from high-purity fluorinated liquid. The method includes the following steps: adding an exchange-adsorbent material to a container holding the fluorinated liquid, then adding ultrapure water, adsorbing and removing impurities, and separating the impurities. This invention adds ultrapure water to cover the fluorinated liquid with an aqueous phase. The exchange-adsorbent material is located between the aqueous phase and the organic phase of the fluorinated liquid. Impurity ions in the fluorinated liquid migrate to the more easily ionized aqueous phase after contacting the phase interface, and are then adsorbed by the exchange-adsorbent material, achieving the effect of ion-based impurity removal. This invention solves the problem of incompatibility between fluorinated liquid and exchange-adsorbent materials such as resins, achieving effective impurity removal from high-purity fluorinated liquid. However, this patent only targets the removal of metal ions, while the main impurities in the fluorinated liquid raw material also include hydrofluoric acid, low-boiling-point impurities such as non-condensable gas CO2, and high-boiling-point impurities such as incompletely fluorinated organic amines. Furthermore, this patent does not specifically address how to solve the problems of excessively high hydrofluoric acid content and excessively large boiling range.

[0006] Therefore, there is an urgent need to develop a purification method that is suitable for fluorinated liquids with different raw materials, low hydrofluoric acid content, short boiling range, and parameters that meet 3M's standards. Summary of the Invention

[0007] In view of the existing deficiencies, the present invention aims to provide a purification method for fluorinated liquids suitable for different raw materials, with low hydrofluoric acid content, small boiling range, and parameters that conform to 3M's standards.

[0008] To achieve the above objectives, the present invention employs the following technical solution:

[0009] On one hand, the present invention provides a method for purifying electronic-grade fluorinated liquid, the purification method comprising the following steps: taking fluorinated liquid raw material and subjecting it to neutralization reaction, impurity removal treatment and distillation treatment in sequence to obtain electronic-grade fluorinated liquid; the impurity removal treatment includes adsorption impurity removal treatment and gas stripping impurity removal treatment;

[0010] The specific steps of the adsorption and impurity removal treatment are as follows: the fluorinated liquid after the neutralization reaction is adsorbed and impurities are removed by an adsorption and impurity removal column to obtain fluorinated liquid A;

[0011] The specific steps of the stripping and impurity removal process are as follows: Fluorinated liquid A is stripped and impurity removed through a stripping tower to obtain fluorinated liquid B;

[0012] Specifically, the neutralization reaction is as follows: a neutralizing agent is added to the fluorinated liquid raw material and mixed evenly, then a dispersant is added to obtain a mixed liquid; the pH of the mixed liquid is adjusted to 7, and the lower layer is taken after standing to obtain the fluorinated liquid after the neutralization reaction.

[0013] Specifically, the above-mentioned distillation process involves: first, storing the fluorinated liquid B in an intermediate product tank, and then distilling it in a distillation column to obtain electronic-grade fluorinated liquid.

[0014] Preferably, the fluorinated liquid raw material can be one or a mixture of perfluorotributylamine, perfluoropolyether, perfluorononenyltrifluoroethyl ether, hydrofluoroether, light fluorinated oil, and heavy fluorinated oil.

[0015] Preferably, the above-mentioned dispersant is selected from one of glycerol, polyvinyl alcohol, propylene glycol, and polyethylene glycol.

[0016] Preferably, the neutralizing agent is selected from alkali metal oxides and alkali metal hydroxides; more preferably, the neutralizing agent is sodium hydroxide and sodium oxide.

[0017] The basis for choosing alkali metal oxides and alkali metal hydroxides as neutralizing agents is that the presence of a large number of hydroxide ions causes organic impurities containing carboxylic acid groups to react with metal ions to generate large molecular organic compounds containing metal ions, which facilitates the removal of large molecular organic compounds in the later stage.

[0018] Preferably, the concentration of the neutralizing agent is 10%-50%.

[0019] Preferably, the volume ratio of the dispersant to the fluorinated liquid added in the neutralization reaction is 1:1000-1:100.

[0020] Preferably, the adsorption column is a molecular sieve adsorption column; the molecular sieve in the molecular sieve adsorption column is selected from one or more of 3A molecular sieve, 4A molecular sieve, 5A molecular sieve, ZSM-5 molecular sieve, 13X molecular sieve, 10X molecular sieve, high-silica Y-type molecular sieve and activated alumina.

[0021] More preferably, the molecular sieve is a 4A molecular sieve, a ZSM-5 molecular sieve, or a 5A molecular sieve.

[0022] Preferably, the particle size of the 4A molecular sieve is 2.5-3 mm, the particle size of the ZSM-5 molecular sieve is 2.5-3 mm, and the particle size of the 5A molecular sieve is 2.5-3 mm.

[0023] The basis for selecting molecular sieves is: ZSM-5 molecular sieves are used to remove non-polar and weakly polar organic impurities, while 4A and 5A molecular sieves are used to remove water and some acidic impurities.

[0024] Preferably, the fluorinated liquid after the neutralization reaction flows sequentially through 4A molecular sieve, ZSM-5 molecular sieve and 5A molecular sieve.

[0025] Preferably, the stacking height of the molecular sieve is 9-12 times the diameter of the molecular sieve adsorption column, and the diameter of the molecular sieve is 4-20 mesh.

[0026] More preferably, the stacking height of the molecular sieve is 10 times the diameter of the molecular sieve adsorption column, and the diameter of the molecular sieve is 12 mesh.

[0027] Preferably, the diameter of the molecular sieve adsorption tower is 10-50 cm. More preferably, the diameter of the adsorption column is 12 cm.

[0028] Preferably, a sieve plate is fixedly provided in the inner cavity of the molecular sieve adsorption column, the molecular sieve is located on the sieve plate, and a guide plate is fixedly provided on the inner top wall of the molecular sieve adsorption column, with the guide plates spaced 300-800mm apart.

[0029] More preferably, the spacing between the aforementioned guide vanes is 450 mm.

[0030] Preferably, the flow rate of the fluorinated liquid after the neutralization reaction through the adsorption and impurity removal column is 0.2-2 L / min.

[0031] Preferably, the diameter of the stripping tower is 10-50 cm. More preferably, the diameter of the stripping tower is 20 cm.

[0032] Preferably, the flow rate of the fluorinated liquid A through the stripping tower is 0.5-6 L / min.

[0033] Preferably, the gas used in the gas stripping and impurity removal process is an inert gas such as oxygen, nitrogen, helium, or hydrogen.

[0034] More preferably, the gas used in the gas stripping impurity removal treatment is nitrogen, and the nitrogen flow rate is 0.1-2 m³ / h. 3 / h.

[0035] Preferably, the distillation column includes a stripping section, a rectification section, a fractionation section, and a reboiler; the stripping section has 15-40 theoretical plates, the rectification section has 10-30 theoretical plates, and the diameter of the distillation column is 10-50 cm.

[0036] More preferably, the distillation column includes a stripping section, a rectification section, a fractionation section, and a reboiler; the stripping section has 32 theoretical plates, the rectification section has 24 theoretical plates, and the diameter of the distillation column is 12 cm.

[0037] Preferably, the packing material of the distillation column is selected from one or more of Raschig rings, Pall rings, θ rings, arc saddle rings, stainless steel or rectangular saddle rings.

[0038] Preferably, the reflux ratio in the distillation column is 1:1 to 1:8, and more preferably 1:4.

[0039] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0040] (1) In this application, when the fluorinated liquid feedstock is neutralized by an alkaline substance, the acidic substances in the fluorinated liquid feedstock are neutralized; when the fluorinated liquid feedstock passes through a molecular sieve adsorption tower, low-boiling-point impurities such as water in the fluorinated liquid feedstock are effectively removed; dissolved non-condensable gases and pseudo-acidity problems in the fluorinated liquid feedstock are solved by gas stripping; high-boiling-point impurities such as higher alkanes, incompletely fluorinated organic amines, and various metal ion impurities are effectively removed during distillation. Through the purification method of this application, a product conforming to the parameters of 3M's electronic-grade fluorinated liquid can be obtained.

[0041] (2) By selecting sodium hydroxide, in an alkaline environment, acidic substances lose hydrogen ions and react with sodium ions, thereby increasing their molecular weight, which makes it easier to remove them later.

[0042] (3) The volatility of the fluorinated liquid can be made to meet the corresponding technical parameters by controlling the proportion of distillation reflux. Attached Figure Description

[0043] Figure 1 This is a process flow diagram for electronic-grade fluorinated liquid.

[0044] Wherein, W0 is the reaction vessel; V0 is the raw material vessel; V1, V2, V3, V4, V5 are intermediate product vessels; V6 is the finished product vessel; V7 is the tail gas absorption vessel; T0, T1, T2 are adsorption towers; T3 is the stripping tower; T4 is the distillation tower; C1, C2 are condensers; F1, F2 are filters. Detailed Implementation

[0045] The present invention will be further described in detail below with reference to specific embodiments. These embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to the following embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the following embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

[0046] In the examples of the electronic-grade fluorinated liquid purification process, the fluorinated liquid raw material was industrial-grade fluorinated liquid produced by Shandong Zhongshan Optoelectronic Materials Co., Ltd., and other reagents were commercially available.

[0047] Example 1

[0048] A method for purifying electronic-grade fluorinated liquid includes the following steps:

[0049] Neutralization reaction:

[0050] The neutralizing agent is added to the fluorinated liquid raw material and mixed evenly. Then, glycerol is added to the reaction vessel, heated and stirred evenly. Sodium hydroxide solution and glycerol are added to perfluorotributylamine and mixed evenly to obtain a mixed solution. The pH value of the mixed solution is 7 to obtain the pretreated fluorinated liquid raw material. The fluorinated liquid raw material is perfluorotributylamine, the volume of the fluorinated liquid raw material is 5L, the concentration of the neutralizing agent is 10%, and the volume of the dispersant is 5ml.

[0051] Adsorption tower impurity removal treatment:

[0052] The fluorinated liquid after neutralization reaction is sequentially fed into adsorption tower T0 containing 4A molecular sieve, adsorption tower T1 containing ZSM-5 molecular sieve, and adsorption tower T2 containing 5A molecular sieve at a flow rate of 0.2 L / min.

[0053] The particle size of 4A molecular sieve, ZSM-5 molecular sieve, and 5A molecular sieve is 3mm. When the diameter of the adsorption column is 12cm, the height of the adsorption column is 120cm, the height of the packing is 110cm, and the nominal diameter of the packing is 1cm. The stacking height of the molecular sieves is 10 times the diameter of the molecular sieve adsorption column, the mesh size of the molecular sieves is 12 mesh, and the spacing of the guide plates fixed on the top wall of the adsorption column is 450mm.

[0054] Air stripping for impurity removal:

[0055] The fluorinated liquid intermediate, after impurity removal treatment in the adsorption tower, is introduced into the stripping tower T3 at a flow rate of 3 L / min, while the nitrogen flow rate is controlled at 1 m³ / min. 3 / h, the intermediate fluorinated liquid is subjected to carrier gas for 1 hour.

[0056] Distillation process:

[0057] The fluorinated liquid solution, after being purified by the adsorption tower, is distilled at a flow rate of 1 L / min through distillation column T4, with a reflux ratio of 1:4, to obtain electronic-grade fluorinated liquid. The packing material of the distillation column is stainless steel.

[0058] The distillation column includes a stripping section, a rectification section, a fractionation section, and a reboiler; the stripping section has 32 theoretical plates, and the rectification section has 24 theoretical plates; the diameter of the distillation column is 12 cm.

[0059] Example 2

[0060] The difference from Example 1 is that the fluorinated liquid raw material in the neutralization reaction is perfluoromethylpentyl ether, the neutralizing agent is selected from alkali metal oxides and sodium oxide, the concentration of the neutralizing agent is 50%, the molecular sieves T0, T1 and T2 are 3A molecular sieve, 4A molecular sieve and 5A molecular sieve respectively, and the stacking height of the molecular sieves is 9 times the diameter of the molecular sieve adsorption column, the diameter of the adsorption column is 10 cm, and the rest is the same as in Example 1.

[0061] Example 3

[0062] The difference from Example 1 is that the fluorinated liquid raw material in the neutralization reaction is perfluorononenyl trifluoroethyl ether, and the molecular sieves T0, T1 and T2 are 13X molecular sieve, 10X molecular sieve and high-silica Y-type molecular sieve respectively. The stacking height of the molecular sieves is 12 times the diameter of the molecular sieve adsorption column, and the diameter of the gas stripping tower is 50 cm. Everything else is the same as in Example 1.

[0063] Example 4

[0064] The difference from Example 1 is that the neutralizing agent in the neutralization reaction is potassium hydroxide, and the molecular sieves T0, T1 and T2 are 5A molecular sieve, ZSM-5 molecular sieve and 13X molecular sieve respectively. The diameter of the molecular sieve is 4 mesh. The spacing of the guide plates fixed on the top wall of the adsorption column is 300 mm. The packing of the gas stripping tower and the distillation tower are rectangular saddle rings. Everything else is the same as in Example 1.

[0065] Example 5

[0066] The difference from Example 1 is that the concentration of sodium hydroxide solution in the neutralization reaction is 40%, and the molecular sieves T0, T1 and T2 are 10X molecular sieve, high-silica Y-type molecular sieve and activated alumina respectively. The diameter of the molecular sieve is 20 mesh, the diameter of the adsorption column is 50 cm, the spacing of the guide plates fixed on the top wall of the adsorption column is 800 mm, and the packing of the gas stripping tower and the distillation tower are both arc saddle rings. Everything else is the same as in Example 1.

[0067] Example 6

[0068] The difference from Example 1 is that the dispersant in the neutralization reaction is polyvinyl alcohol with a volume of 5L, the stacking height of the molecular sieve is 9 times the diameter of the molecular sieve adsorption column, the flow rate of the fluorinated liquid in the adsorption tower impurity removal treatment is 0.2L / min, the diameter of the stripping tower is 10cm, and the packing of the stripping tower and the distillation tower are both θ rings. Everything else is the same as in Example 1.

[0069] Example 7

[0070] The difference from Example 1 is that the flow rate of the fluorinated liquid in the adsorption tower impurity removal treatment is 2 L / min, and the flow rate of fluorinated liquid A flowing through the stripping tower in the stripping treatment is 6 L / min. The rest is the same as Example 1.

[0071] Example 8

[0072] The difference from Example 1 is that the dispersant in the neutralization reaction is polyethylene glycol, and the flow rate of fluorinated liquid A through the stripping tower in the stripping treatment is 0.5 L / min. The rest is the same as in Example 1.

[0073] Example 9

[0074] The difference from Example 1 is that the nitrogen flow rate in the air stripping impurity removal process is 0.1 m³ / s. 3 / h, the stripping section of the distillation column has 15 theoretical plates, the rectification section has 10 theoretical plates, the column diameter is 10cm, and other aspects are the same as in Example 1.

[0075] Example 10

[0076] The difference from Example 1 is that the nitrogen flow rate in the air stripping impurity removal process is 2m³ / h. 3 / h, the stripping section of the distillation column has 40 theoretical plates, and the rectification section has 30 theoretical plates; the diameter of the distillation column is 50cm, and the packing of both the stripping column and the rectification column is Pall rings, and the rest is the same as in Example 1.

[0077] Example 11

[0078] The difference from Example 1 is that the dispersant in the neutralization reaction is propylene glycol, and the packing for both the stripping tower and the distillation tower is Raschig ring.

[0079] Comparative Example 1

[0080] The difference from Example 1 is that the volume of the dispersant in the neutralization reaction is 1 ml.

[0081] Comparative Example 2

[0082] The difference from Example 1 is that the volume of the dispersant in the neutralization reaction is 60 ml.

[0083] Comparative Example 3

[0084] The difference from Example 1 is that the fluorinated liquid raw material in step A is nonafluorobutyl methyl ether.

[0085] Comparative Example 4

[0086] The difference from Example 1 is that the distillation reflux ratio is 1:9.

[0087] Comparative Example 5

[0088] The difference from Example 1 is that no air stripping impurity removal process is performed.

[0089] Performance testing

[0090] The technical indicators in Example 1 were tested, and the test results are shown in Table 1. The volatilization rates at room temperature in Examples 1-13, Comparative Examples 1-5, and 3M's electronic-grade fluorinated liquid were also tested, and the test results are shown in Table 1.

[0091] Table 1. Volatility test results of electronic-grade fluorinated liquid

[0092]

[0093] As shown in Table 1 above, compared with the electronic-grade fluorinated liquid from 3M Company, the electronic-grade fluorinated liquid in Examples 1-11 has a similar or even lower evaporation rate at room temperature. Therefore, the electronic-grade fluorinated liquid obtained by the purification method of this application can meet the standard.

[0094] Table 2 shows the test results of the examples, comparative examples, and 3M electronic-grade fluorinated liquid.

[0095]

[0096]

[0097] The acidity and fluoride ion content of the electronic-grade fluorinated liquids in Examples 1-3 are similar to or even lower than those of the electronic-grade fluorinated liquids of 3M. Therefore, the electronic-grade fluorinated liquids obtained by the purification method of this application can meet the standards.

[0098] A comparison of Examples 1 and 4-6 revealed that increasing the concentration of the neutralizing agent sodium hydroxide had some effect on reducing acidity, but the effect was not significant. Compared to Example 1, when propylene glycol was used as the dispersant in Example 11, the effect on reducing the acidity of the fluorinated liquid was poor.

[0099] A comparison of Example 1 and Example 7 revealed that an excessively fast feed rate can cause the molecular sieve to penetrate, resulting in an adsorption effect that does not reach the level of Example 1.

[0100] A comparison of Examples 1 and 8-10 revealed that a flow rate of 3 L / min is more suitable for reducing the acidity of the fluorinated liquid. This was further compared with nitrogen flow rates of 1 m... 3 At a rate of / h, it is more effective in reducing acidity.

[0101] Comparative Examples 1 and 2 show that excessively low or high volumes of dispersant have a significant impact on reducing the alkaline washing reaction time. A volume ratio of dispersant to fluorinated liquid raw material of 1:1000-1:100 yields better acid removal results. Furthermore, the applicant found that adding dispersant can significantly reduce the alkaline washing reaction time, and the neutralization reaction time can be shortened from 40 hours to 10 hours.

[0102] As can be seen from Comparative Example 3, the purification method is not effective when the fluorinated liquid raw material is nonafluorobutyl methyl ether, indicating that purification is more effective when the fluorinated liquid raw material is the fluorinated liquid raw material limited to that specified in this application.

[0103] As can be seen from Example 1 and Comparative Example 4, the control of the reflux ratio in distillation affects the removal ratio of light components and thus the volatility of the final fluorinated liquid. An excessively high reflux ratio will lead to an increase in the volatility of the fluorinated liquid. Therefore, a reflux ratio of 1:4 is more effective in controlling volatility.

[0104] As shown in Comparative Example 5, the gas stripping method can blow out the dissolved gas in the fluorinated liquid, thereby solving the problem of false acid value of the fluorinated liquid raw material; gas stripping can also carry out easily vaporized components through the airflow, thereby achieving the effect of controlling volatility, and the loss of the main component is relatively small.

[0105] In summary, the purification method described in this invention can be used to obtain electronic fluorinated liquids that meet 3M's standards.

Claims

1. A method for purifying electronic-grade fluorinated liquid, characterized in that: The purification method includes the following steps: taking the fluorinated liquid raw material and subjecting it to neutralization reaction, impurity removal treatment and distillation treatment in sequence to obtain electronic grade fluorinated liquid; the impurity removal treatment includes adsorption impurity removal treatment and gas stripping impurity removal treatment. The specific steps of the adsorption and impurity removal treatment are as follows: the fluorinated liquid after the neutralization reaction is adsorbed and impurities are removed by an adsorption and impurity removal column to obtain fluorinated liquid A; The specific steps of the stripping and impurity removal process are as follows: Fluorinated liquid A is stripped and impurity removed through a stripping tower to obtain fluorinated liquid B.

2. The purification method according to claim 1, characterized in that: The neutralization reaction is as follows: The neutralizing agent is added to the fluorinated liquid raw material and mixed evenly. Then, a dispersant is added to obtain a mixed liquid. The pH value of the mixed liquid is adjusted to 7, and the lower layer is taken out after standing to obtain the fluorinated liquid after neutralization reaction.

3. The purification method according to claim 1, characterized in that: The distillation process is as follows: First, the fluorinated liquid B is stored in an intermediate product tank, and then it is distilled in a distillation column to obtain electronic-grade fluorinated liquid.

4. The purification method according to claim 1, characterized in that: The adsorption and impurity removal column is a molecular sieve adsorption column; the molecular sieve in the molecular sieve adsorption column is selected from one or more of 3A molecular sieve, 4A molecular sieve, 5A molecular sieve, ZSM-5 molecular sieve, 13X molecular sieve, 10X molecular sieve, high-silica Y-type molecular sieve and activated alumina.

5. The purification method according to claim 4, characterized in that: The stacking height of the molecular sieves is 9-12 times the diameter of the molecular sieve adsorption column, and the diameter of the molecular sieves is 4-20 mesh.

6. The purification method according to claim 4, characterized in that: The diameter of the molecular sieve adsorption column is 10-50 cm.

7. The purification method according to claim 4, characterized in that: The molecular sieve adsorption column has a fixed sieve plate in its inner cavity, the molecular sieve is located on the sieve plate, and a guide plate is fixed on the inner top wall of the molecular sieve adsorption column, with the guide plate spacing being 300-800mm.

8. The purification method according to claim 1, characterized in that: The flow rate of the fluorinated liquid after the neutralization reaction as it flows through the adsorption and impurity removal column is 0.2-2 L / min.

9. The purification method according to claim 1, characterized in that: The diameter of the gas stripping tower is 10-50cm.

10. The purification method according to claim 1, characterized in that: The flow rate of the fluorinated liquid A as it flows through the stripping tower is 0.5-6 L / min.

11. The purification method according to claim 1, characterized in that: The stripping carrier in the stripping tower is an inert gas, specifically nitrogen, with a flow rate of 0.1-2 m³ / h. 3 / h.

12. The purification method according to claim 2, characterized in that: The neutralizing agent is selected from alkali metal oxides or alkali metal hydroxides, and the concentration of the neutralizing agent is 10%-50%.

13. The purification method according to claim 2, characterized in that: The dispersant is selected from one or more of glycerol, polyvinyl alcohol, propylene glycol and polyethylene glycol, and the volume ratio of the dispersant to the fluorinated liquid raw material is 1:1000-1:

100.

14. The purification method according to claim 3, characterized in that: The distillation column includes a stripping section, a rectification section, a fractionation section, and a reboiler; the stripping section has 15-40 theoretical plates, the rectification section has 10-30 theoretical plates, and the diameter of the distillation column is 10-50 cm.

15. The purification method according to claim 1 or 3, characterized in that: The packing materials for the stripping tower and distillation tower are one or more of Raschig rings, Pall rings, θ rings, arc saddle rings, stainless steel or rectangular saddle rings.

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