A method for preparing electronic-grade hydrofluoric acid

Abstract

This invention relates to a method for preparing electronic-grade hydrofluoric acid. The invention utilizes a microchannel reactor for the fluorine oxidation reaction, significantly reducing fluorine consumption and safety hazards during production. Furthermore, the microchannel reactor enhances the gas-liquid two-phase mass transfer during the oxidation reaction, further improving impurity removal and product quality. The addition of multi-effect distillation to the distillation process not only enables secondary heat utilization but also saves on the use of high-temperature heating media at the bottom of the column, effectively reducing energy consumption. In the modified liquid, DMF serves as the solvent, cobalt nitrate provides cobalt ions, and vinylguanidine provides guanidine functional groups and amino groups. Ammonia and propanethiol are used as plasma gases to introduce amino and thiol groups onto the membrane surface. These groups help improve membrane selectivity, effectively separating metal and non-metal ions, as well as acidic impurities in the raw materials.

Description

Technical Field

[0001] This invention belongs to the field of fluorochemical technology, specifically relating to a method for preparing electronic-grade hydrofluoric acid. Background Technology

[0002] In the manufacturing process of the electronics industry, hydrofluoric acid is used as an etching agent, cleaning agent, etc. It can be used in combination with electronic-grade reagents such as nitric acid, acetic acid, ammonium hydroxide and hydrogen peroxide. Its purity and cleanliness have a very important impact on the yield, electrical performance and reliability of integrated circuits.

[0003] The impurities in industrial anhydrous hydrogen fluoride vary depending on the preparation process. The most significant impurities affecting semiconductor chip processing are metal ions and some non-metal ions, such as arsenic, phosphorus, and silicon, with arsenic being the most critical. Currently, impurity ions are mainly removed through distillation, while non-metallic impurities require reaction-distillation. Research on the removal of arsenic, phosphorus, and silicon ions should adhere to principles such as minimizing secondary pollution, high removal efficiency, and low cost. Arsenic removal primarily involves oxidizing the difficult-to-remove arsenic trifluoride (boiling point 63℃) into the easily removable arsenic pentafluoride (boiling point -52.8℃), or oxidizing it to form high-boiling substances such as hexafluoroarsonic acid and hexafluoroarsates, which have significantly different boiling points from hydrogen fluoride. Fluorine-nitrogen mixed gas oxidants are effective; potassium permanganate solution, (NH4)2S2O8 solution, KHF2 solution, hydrogen peroxide solution, and solid platinum fluoride are also commonly used as oxidants. Chinese invention patent (patent number CN201110276860.4) discloses a method for preparing electronic-grade hydrofluoric acid. This method uses fluorine gas to oxidize trivalent arsenic ions in industrial anhydrous hydrofluoric acid raw materials, employing a bubble column reactor with an external fluorine gas circulation stream. Fluorine gas is highly toxic, chemically reactive, and a strong oxidizing agent. Existing conveying machinery, such as circulation pumps, struggles to solve the sealing problem, and leaks can easily lead to serious safety accidents. Using a circulating reaction further exacerbates the safety hazards of the reaction, and this method also has relatively high energy consumption. Summary of the Invention

[0004] Common oxidation reactions during hydrofluoric acid production include:

[0005] AsF3+2KMnO4+8HF→AsF5+2MnF2+2KF+4H2O

[0006] 4H2O2+2AsF3+4HF→2AsF5+O2↑+6H2O

[0007] AsF3+F2→AsF5

[0008] To address the shortcomings of existing technologies, this invention provides a method for preparing electronic-grade hydrofluoric acid. This method is simple, safe, produces high-quality products, consumes little energy, and is easy to apply industrially.

[0009] The specific steps of this invention are as follows:

[0010] (1) Pump the raw material industrial anhydrous hydrogen fluoride liquid from the raw material storage tank into the microchannel reactor, and at the same time, introduce high-purity oxidant into the inlet of the microchannel reactor to carry out the oxidation reaction.

[0011] (2) An anhydrous hydrogen fluoride mixture containing a small amount of oxidant impurities is obtained at the outlet of the microchannel reactor and sent to a primary distillation column to remove light component impurities. A condenser is installed at the top of the primary distillation column.

[0012] (3) Anhydrous hydrofluoric acid liquid is collected from the bottom of the first-stage distillation column and transported to the second-stage distillation column to remove heavy component impurities. No condenser is installed at the top of the second-stage distillation column, but a double-effect reboiler is installed at the bottom. The steam at the top of the second-stage distillation column is used as the heat source for the reboiler at the bottom of the first-stage distillation column. After heat exchange, the steam is used to obtain anhydrous hydrofluoric acid liquid. Part of it is returned to the second-stage distillation column, and the rest is collected as anhydrous hydrofluoric acid product. After filtration, it can be blended with high-purity water to obtain the final electronic-grade hydrogen fluoride product.

[0013] Preferably, in the raw material industrial anhydrous hydrogen fluoride liquid in step (1), the hydrogen fluoride content is ≥99.99%, the fluorosilicic acid content is ≤0.0008%, the sulfur dioxide content is ≤0.0001%, the non-volatile acid (calculated as H2SO4) is ≤0.001%, the water content is ≤0.0005%, and the sulfur component content is ≤0.0063%.

[0014] Preferably, the high-purity oxidant in step (1) is selected from one or more of fluorine, potassium permanganate, hydrogen peroxide, ammonium persulfate, and oxygen, with fluorine being the most preferred.

[0015] Preferably, the microchannel reactor in step (1) is selected from one or more of the following: rectangular microchannel reactor, silicon microchannel reactor, PTFE type microchannel reactor, PMMA type microchannel reactor, PE microchannel reactor, PDMS microchannel reactor, glass microchannel reactor, ceramic microchannel reactor, aluminum microchannel reactor, stainless steel microchannel reactor, and copper microchannel reactor, with PTFE type microchannel reactor being the most preferred.

[0016] Preferably, a T-tube is installed before the inlet of the microchannel reactor in step (1).

[0017] Preferably, the mass flow ratio of high-purity fluorine gas to anhydrous hydrogen fluoride raw material in step (1) is 0.005-0.1:1.

[0018] Preferably, the primary distillation column in step (2) is made of stainless steel lined with polytetrafluoroethylene.

[0019] Preferably, the top temperature of the first-stage distillation column in step (2) is 19-25°C and the pressure is atmospheric pressure.

[0020] Preferably, the primary distillation column condenser in step (2) uses cooling water as the coolant, and the outlet temperature is controlled at around 19.5°C.

[0021] Preferably, the secondary distillation column in step (3) is made of stainless steel lined with polytetrafluoroethylene.

[0022] Preferably, the top temperature of the secondary distillation column in step (3) is 42-58℃.

[0023] Preferably, the reflux ratio of the secondary distillation column in step (3) is 2.0-2.5.

[0024] Preferably, the pressure of the secondary distillation column in step (3) is 2.5-5.0 times the atmospheric pressure.

[0025] Preferably, the filtration in step (3) is filtration using a modified polytetrafluoroethylene nanofiltration membrane, wherein the modified polytetrafluoroethylene nanofiltration membrane has a precision of 0.1-1.0 μm.

[0026] Preferably, the modification method of the modified polytetrafluoroethylene nanofiltration membrane includes the following steps:

[0027] Immerse 50-60 parts of polytetrafluoroethylene nanofiltration membrane in the modification solution for 10-20 hours, then remove and dry. Place the membrane in a plasma surface treatment instrument. Plasma parameters: power 100-200W, treatment time 40-120s; gas flow rate: ammonia 10-20sccm, propanethiol 10-20sccm. The modification solution consists of 500-600 parts of DMF, 4-10 parts of cobalt nitrate, and 0.04-0.7 parts of vinylguanidine. Post-treatment method: ultrasonically clean the modified polytetrafluoroethylene membrane in acetone for 10-30 minutes, then clean it in deionized water for 10-30 minutes, and finally dry it in a vacuum drying oven at 60-80℃ for 10-24 hours.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] Using a microchannel reactor for the fluorine oxidation reaction significantly reduces fluorine consumption, lowers safety hazards during production, and enhances gas-liquid mass transfer during the oxidation reaction, further improving impurity removal and product quality. Incorporating multi-effect distillation into the distillation process not only enables the secondary utilization of heat but also saves on the use of high-temperature heating media at the bottom of the column, effectively reducing energy consumption.

[0030] In the modification solution, DMF serves as the solvent, cobalt nitrate provides cobalt ions, and vinylguanidine provides guanidine functional groups and amino groups. Ammonia and propanethiol, as plasma gases, may introduce amino and thiol groups onto the membrane surface, which contribute to improving the membrane's selectivity and other properties. The surface properties of the polytetrafluoroethylene nanofiltration membrane are significantly improved, enabling the effective separation of metal and non-metal ions, as well as acidic impurities in the feed. These modifications not only enhance the membrane's antifouling properties but also expand its application prospects in fields such as electronic products. Attached Figure Description

[0031] Figure 1 This is a process flow diagram of the present invention. Detailed Implementation

[0032] The present invention will now be described in detail with reference to embodiments to provide a basic understanding of these aspects. It should be correctly understood that the embodiments and accompanying drawings are merely a brief description of the invention and not a limitation thereof. This overview does not attempt to define the scope of any or all aspects. Therefore, simple modifications made based on the present invention fall within the scope of protection claimed by the present invention.

[0033] Example 1

[0034] Anhydrous hydrogen fluoride liquid, the raw material, is pumped from the raw material storage tank into the inlet of a parallel microchannel reactor at a flow rate controlled at 100 kg / h. Simultaneously, high-purity fluorine gas is introduced into the microchannel reactor inlet at a flow rate set at 0.5 kg / h. A T-tube is installed at the microchannel reactor inlet, with the anhydrous hydrogen fluoride raw material and fluorine gas entering from opposite sides of the T-tube, mixing, and then entering the microchannel reactor together. The microchannel reactor jacket is equipped with a temperature control system, maintaining the reaction temperature at 15°C for the oxidation reaction. The gas-liquid mixture collected at the microchannel reactor outlet is directly fed into the middle of a primary distillation column, where excess fluorine and light component impurities are removed from the anhydrous hydrogen fluoride. The primary distillation column operates at atmospheric pressure, and a condenser is used to cool the overhead vapor. Cooling water is used as the coolant in the tube side of the condenser, while steam, as the hot stream, partially condenses into liquid in the shell side. The outlet temperature of the hot stream is controlled at approximately 19.5°C. Non-condensable gases, as light impurities, enter the tail gas treatment system, and the condensed liquid is returned to the first-stage distillation column from the top of the column as reflux. Anhydrous hydrofluoric acid liquid is collected from the bottom of the first-stage distillation column and pumped to the middle of the second-stage distillation column using a pressure pump to remove the remaining heavy impurities. The secondary distillation column operates at 3.0 times atmospheric pressure, without a condenser at the top. The temperature at the top of the secondary distillation column is controlled at approximately 45°C. The vapor at the top of the column serves as the heat source for the double-effect reboiler in the first-stage distillation column, heating the liquid in the first-stage column. Simultaneously, the vapor at the top of the secondary distillation column is condensed after heat exchange to obtain anhydrous hydrofluoric acid liquid, which is refluxed back to the upper part of the secondary distillation column at a reflux ratio of 2.0. The remainder is collected as anhydrous hydrofluoric acid product. After filtration through a modified polytetrafluoroethylene nanofiltration membrane, the arsenic content in the anhydrous hydrogen fluoride is reduced from 2.3 ppm to 0.1 ppb. Further blending with high-purity water yields the final electronic-grade hydrogen fluoride product.

[0035] The modification method for the modified polytetrafluoroethylene nanofiltration membrane includes the following steps:

[0036] 50 kg of polytetrafluoroethylene nanofiltration membrane was immersed in the modification solution for 10 h, then removed and dried. It was then placed in a plasma surface treatment instrument (PlasmaSurface G5K model); plasma parameters: power 100 W, treatment time 40 s; gas flow rate: ammonia 10 sccm, propanethiol 10 sccm; the modification solution consisted of 500 kg DMF, 4 kg cobalt nitrate, and 0.04 kg vinylguanidine; post-treatment method: the modified polytetrafluoroethylene membrane was ultrasonically cleaned in acetone for 10 min, then cleaned in deionized water for 10 min, and finally dried in a vacuum drying oven at 60 °C for 10 h.

[0037] Example 2

[0038] Anhydrous hydrogen fluoride liquid, the raw material, is pumped from the raw material storage tank into the inlet of a parallel microchannel reactor at a flow rate controlled at 100 kg / h. Simultaneously, high-purity fluorine gas is introduced into the microchannel reactor inlet at a flow rate set at 0.8 kg / h. A T-tube is installed at the microchannel reactor inlet, with the anhydrous hydrogen fluoride raw material and fluorine gas entering from opposite sides of the T-tube, mixing, and then entering the microchannel reactor together. The microchannel reactor jacket is equipped with a temperature control system, maintaining the reaction temperature at 15°C for the oxidation reaction. The gas-liquid mixture collected at the microchannel reactor outlet is directly fed into the middle of a primary distillation column, where excess fluorine and light component impurities are removed from the anhydrous hydrogen fluoride. The primary distillation column operates at atmospheric pressure, and a condenser is used to cool the overhead vapor. Cooling water is used as the coolant in the tube side of the condenser, while steam, as the hot stream, partially condenses into liquid in the shell side. The outlet temperature of the hot stream is controlled at approximately 19.5°C. Non-condensable gases, as light impurities, enter the tail gas treatment system, and the condensed liquid is returned to the first-stage distillation column from the top of the column as reflux. Anhydrous hydrofluoric acid liquid is collected from the bottom of the first-stage distillation column and pumped to the middle of the second-stage distillation column using a pressure pump to remove the remaining heavy impurities. The secondary distillation column operates at 3.5 times atmospheric pressure, without a condenser at the top. The top temperature of the secondary distillation column is controlled at approximately 49°C. The vapor from the top of the column serves as the heat source for the double-effect reboiler in the first-stage distillation column, heating the liquid in the first-stage column. Simultaneously, the vapor from the top of the secondary distillation column is condensed after heat exchange to obtain anhydrous hydrofluoric acid liquid, which is refluxed back to the upper part of the secondary distillation column at a reflux ratio of 2.4. The remainder is collected as anhydrous hydrofluoric acid product. After filtration through a modified polytetrafluoroethylene nanofiltration membrane, the arsenic content in the anhydrous hydrogen fluoride is reduced from 2.3 ppm to 0.092 ppb. The final electronic-grade hydrogen fluoride product can be obtained by blending with high-purity water.

[0039] The modification method for the modified polytetrafluoroethylene nanofiltration membrane includes the following steps:

[0040] 55 kg of polytetrafluoroethylene nanofiltration membrane was immersed in the modification solution for 15 hours, then removed and dried. It was then placed in a plasma surface treatment instrument (PlasmaSurface G5K model); plasma parameters: power 150 W, treatment time 80 s; gas flow rate: ammonia 15 sccm, propanethiol 15 sccm; the modification solution consisted of 50 kg DMF, 7 kg cobalt nitrate, and 0.4 kg vinylguanidine; post-treatment method: the modified polytetrafluoroethylene membrane was ultrasonically cleaned in acetone for 20 minutes, then cleaned in deionized water for 20 minutes, and finally dried in a vacuum drying oven at 70°C for 16 hours.

[0041] Example 3

[0042] Anhydrous hydrogen fluoride liquid, the raw material, is pumped from the raw material storage tank into the inlet of a parallel microchannel reactor at a flow rate controlled at 100 kg / h. Simultaneously, high-purity fluorine gas is introduced into the microchannel reactor inlet at a flow rate set at 1.0 kg / h. A T-tube is installed at the microchannel reactor inlet, with the anhydrous hydrogen fluoride raw material and fluorine gas entering from opposite sides of the T-tube, mixing, and then entering the microchannel reactor together. The microchannel reactor jacket is equipped with a temperature control system, maintaining the reaction temperature at 15°C for the oxidation reaction. The gas-liquid mixture collected at the microchannel reactor outlet is directly fed into the middle of a primary distillation column, where excess fluorine and light component impurities are removed from the anhydrous hydrogen fluoride. The primary distillation column operates at atmospheric pressure, and a condenser is used to cool the overhead vapor. Cooling water is used as the coolant in the tube side of the condenser, while steam, as the hot stream, partially condenses into liquid in the shell side. The outlet temperature of the hot stream is controlled at approximately 19.5°C. Non-condensable gases, as light impurities, enter the tail gas treatment system, and the condensed liquid is returned to the first-stage distillation column from the top of the column as reflux. Anhydrous hydrofluoric acid liquid is collected from the bottom of the first-stage distillation column and pumped to the middle of the second-stage distillation column using a pressure pump to remove the remaining heavy impurities. The secondary distillation column operates at 4.0 times atmospheric pressure, without a condenser at the top. The temperature at the top of the secondary distillation column is controlled at approximately 52°C. The vapor at the top of the column serves as the heat source for the double-effect reboiler in the first-stage distillation column, heating the liquid in the first-stage column. Simultaneously, the vapor at the top of the secondary distillation column is condensed after heat exchange to obtain anhydrous hydrofluoric acid liquid, which is refluxed back to the upper part of the secondary distillation column at a reflux ratio of 2.2. The remainder is collected as anhydrous hydrofluoric acid product. After filtration through a modified polytetrafluoroethylene nanofiltration membrane, the arsenic content in the anhydrous hydrogen fluoride is reduced from 2.3 ppm to 0.088 ppb. The final electronic-grade hydrogen fluoride product can be obtained by blending with high-purity water.

[0043] The modification method for the modified polytetrafluoroethylene nanofiltration membrane includes the following steps:

[0044] 60 kg of polytetrafluoroethylene nanofiltration membrane was immersed in the modification solution for 20 h, then removed and dried. It was then placed in a plasma surface treatment instrument (PlasmaSurface G5K model); plasma parameters: power 200 W, treatment time 120 s; gas flow rate: ammonia 20 sccm, propanethiol 20 sccm; the modification solution consisted of 600 kg DMF, 10 kg cobalt nitrate, and 0.7 kg vinylguanidine; post-treatment method: the modified polytetrafluoroethylene membrane was ultrasonically cleaned in acetone for 30 min, then cleaned in deionized water for 30 min, and finally dried in a vacuum drying oven at 80 °C for 24 h.

[0045] Example 4

[0046] Anhydrous hydrogen fluoride liquid, the raw material, is pumped from the raw material storage tank into the inlet of a parallel microchannel reactor at a flow rate controlled at 100 kg / h. Simultaneously, high-purity fluorine gas is introduced into the microchannel reactor inlet at a flow rate set at 0.5 kg / h. A T-tube is installed at the microchannel reactor inlet, with the anhydrous hydrogen fluoride raw material and fluorine gas entering from opposite sides of the T-tube, mixing, and then entering the microchannel reactor together. The microchannel reactor jacket is equipped with a temperature control system, maintaining the reaction temperature at 15°C for the oxidation reaction. The gas-liquid mixture collected at the microchannel reactor outlet is directly fed into the middle of a primary distillation column, where excess fluorine and light component impurities are removed from the anhydrous hydrogen fluoride. The primary distillation column operates at atmospheric pressure, and a condenser is used to cool the overhead vapor. Cooling water is used as the coolant in the tube side of the condenser, while steam, as the hot stream, partially condenses into liquid in the shell side. The outlet temperature of the hot stream is controlled at approximately 19.5°C. Non-condensable gases, as light impurities, enter the tail gas treatment system, and the condensed liquid is returned to the first-stage distillation column from the top of the column as reflux. Anhydrous hydrofluoric acid liquid is collected from the bottom of the first-stage distillation column and pumped to the middle of the second-stage distillation column using a pressure pump to remove the remaining heavy impurities. The secondary distillation column operates at 3.0 times atmospheric pressure, without a condenser at the top. The temperature at the top of the secondary distillation column is controlled at approximately 45°C. The vapor at the top of the column serves as the heat source for the double-effect reboiler in the first-stage distillation column, heating the liquid in the first-stage column. Simultaneously, the vapor at the top of the secondary distillation column is condensed after heat exchange to obtain anhydrous hydrofluoric acid liquid, which is refluxed back to the upper part of the secondary distillation column at a reflux ratio of 2.0. The remainder is collected as anhydrous hydrofluoric acid product. After filtration through a polytetrafluoroethylene nanofiltration membrane, the arsenic content in the anhydrous hydrogen fluoride is reduced from 2.3 ppm to 0.44 ppb. Further blending with high-purity water yields the final electronic-grade hydrogen fluoride product.

[0047] Example 5

[0048] Anhydrous hydrogen fluoride liquid, the raw material, is pumped from the raw material storage tank into the inlet of a parallel microchannel reactor at a flow rate controlled at 100 kg / h. Simultaneously, high-purity fluorine gas is introduced into the microchannel reactor inlet at a flow rate set at 0.8 kg / h. A T-tube is installed at the microchannel reactor inlet, with the anhydrous hydrogen fluoride raw material and fluorine gas entering from opposite sides of the T-tube, mixing, and then entering the microchannel reactor together. The microchannel reactor jacket is equipped with a temperature control system, maintaining the reaction temperature at 15°C for the oxidation reaction. The gas-liquid mixture collected at the microchannel reactor outlet is directly fed into the middle of a primary distillation column, where excess fluorine and light component impurities are removed from the anhydrous hydrogen fluoride. The primary distillation column operates at atmospheric pressure, and a condenser is used to cool the overhead vapor. Cooling water is used as the coolant in the tube side of the condenser, while steam, as the hot stream, partially condenses into liquid in the shell side. The outlet temperature of the hot stream is controlled at approximately 19.5°C. Non-condensable gases, as light impurities, enter the tail gas treatment system, and the condensed liquid is returned to the first-stage distillation column from the top of the column as reflux. Anhydrous hydrofluoric acid liquid is collected from the bottom of the first-stage distillation column and pumped to the middle of the second-stage distillation column using a pressure pump to remove the remaining heavy impurities. The secondary distillation column operates at 3.5 times atmospheric pressure, without a condenser at the top. The temperature at the top of the secondary distillation column is controlled at approximately 49°C. The vapor at the top of the column serves as the heat source for the double-effect reboiler in the first-stage distillation column, heating the liquid in the first-stage column. Simultaneously, the vapor at the top of the secondary distillation column is condensed after heat exchange to obtain anhydrous hydrofluoric acid liquid, which is refluxed back to the upper part of the secondary distillation column at a reflux ratio of 2.4. The remainder is collected as anhydrous hydrofluoric acid product. After filtration through a polytetrafluoroethylene nanofiltration membrane, the arsenic content in the anhydrous hydrogen fluoride is reduced from 2.3 ppm to 0.37 ppb. The final electronic-grade hydrogen fluoride product can be obtained by blending with high-purity water.

Claims

1. A method for producing electronic grade hydrofluoric acid, characterized by, The specific steps include the following: (1) Pump the raw material industrial anhydrous hydrogen fluoride liquid from the raw material storage tank into the microchannel reactor, and at the same time, high-purity fluorine gas is introduced into the inlet of the microchannel reactor for oxidation reaction. (2) An anhydrous hydrogen fluoride mixture containing a small amount of oxidant impurities is obtained at the outlet of the microchannel reactor and sent to a primary distillation column to remove light component impurities. A condenser is installed at the top of the primary distillation column. (3) Anhydrous hydrofluoric acid liquid is collected from the bottom of the first-stage distillation column and sent to the second-stage distillation column to remove heavy component impurities. No condenser is installed at the top of the second-stage distillation column, but a double-effect reboiler is installed at the bottom. The steam at the top of the second-stage distillation column is used as the heat source for the reboiler at the bottom of the first-stage distillation column. After heat exchange, the steam is used to obtain anhydrous hydrofluoric acid liquid. Part of it is returned to the second-stage distillation column, and the rest is collected as anhydrous hydrofluoric acid product. After filtration, it can be adjusted with high-purity water to obtain the final electronic-grade hydrogen fluoride product. In step (3), the filtration is performed using a modified polytetrafluoroethylene nanofiltration membrane, and the precision of the modified polytetrafluoroethylene nanofiltration membrane is 0.1-1.0 μm. The modification method for the modified polytetrafluoroethylene nanofiltration membrane includes the following steps: Immerse 50-60 parts of polytetrafluoroethylene nanofiltration membrane in the modification solution for 10-20 hours, then remove and dry. Place the membrane in a plasma surface treatment instrument. Plasma parameters: power 100-200W, treatment time 40-120s; gas flow rate: ammonia 10-20sccm, propanethiol 10-20sccm. The modification solution consists of 500-600 parts of DMF, 4-10 parts of cobalt nitrate, and 0.04-0.7 parts of vinylguanidine. Post-treatment method: ultrasonically clean the modified polytetrafluoroethylene membrane in acetone for 10-30 minutes, then clean it in deionized water for 10-30 minutes, and finally dry it in a vacuum drying oven at 60-80℃ for 10-24 hours.

2. The method of claim 1, wherein the electronic grade hydrofluoric acid is prepared by the steps of: In step (1), the raw material industrial anhydrous hydrogen fluoride liquid has the following characteristics: hydrogen fluoride content ≥99.99%, fluorosilicic acid content ≤0.0008%, sulfur dioxide content ≤0.0001%, non-volatile acid as H2SO4 ≤0.001%, water content ≤0.0005%, and sulfur component content ≤0.0063%.

3. The method of claim 1, wherein the electronic grade hydrofluoric acid is prepared by the steps of: The microchannel reactor in step (1) is selected from one or more of the following: rectangular microchannel reactor, silicon microchannel reactor, PTFE type microchannel reactor, PMMA type microchannel reactor, PE microchannel reactor, PDMS microchannel reactor, glass microchannel reactor, ceramic microchannel reactor, aluminum microchannel reactor, stainless steel microchannel reactor, and copper microchannel reactor.

4. The method for preparing electronic-grade hydrofluoric acid according to claim 1, characterized in that, A T-tube is installed before the inlet of the microchannel reactor in step (1).

5. The method of claim 1, wherein the electronic grade hydrofluoric acid is prepared by the steps of: The mass flow ratio of high-purity fluorine gas to anhydrous hydrogen fluoride raw material in step (1) is 0.005-0.1:

1.

6. The method of claim 1, wherein the electronic grade hydrofluoric acid is prepared by the steps of: The primary distillation column in step (2) is made of stainless steel lined with polytetrafluoroethylene.

7. The method for preparing electronic-grade hydrofluoric acid according to claim 1, characterized in that, The temperature at the top of the primary distillation column in step (2) is 19-25℃, and the pressure is atmospheric pressure.

8. The method for preparing electronic-grade hydrofluoric acid according to claim 1, characterized in that, In step (2), the primary distillation column condenser uses cooling water as the coolant, and the outlet temperature is controlled at 19.5℃.

9. The method for preparing electronic-grade hydrofluoric acid according to claim 1, characterized in that, The secondary distillation column in step (3) is made of stainless steel lined with polytetrafluoroethylene.

10. The method for preparing electronic-grade hydrofluoric acid according to claim 1, characterized in that, The top temperature of the secondary distillation column in step (3) is 45-58℃.

11. The method for preparing electronic-grade hydrofluoric acid according to claim 1, characterized in that, The reflux ratio of the secondary distillation column in step (3) is 2.0-5.

0.

12. The method for preparing electronic-grade hydrofluoric acid according to claim 1, characterized in that, The pressure of the secondary distillation column in step (3) is 2.0-5.0 times the atmospheric pressure.

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