System and method for preparing electronic-grade hydrogen fluoride by using industrial-grade sodium fluoride

Abstract

The invention belongs to the technical field of chemical engineering, and particularly relates to a system and a method for preparing electronic-grade hydrogen fluoride by utilizing industrial-grade sodium fluoride. The method comprises the following steps: taking industrial-grade sodium fluoride as a raw material, carrying out double decomposition reaction on the industrial-grade sodium fluoride and 98% industrial-grade concentrated sulfuric acid in a'reaction-filtration-drying 'three-in-one reactor, and generating anhydrous hydrogen fluoride gas and a sodium hydrogen sulfate byproduct under the conditions that the temperature is 200-290 DEG C and the sulfuric acid is excessive; byproducts are filtered by high-pressure nitrogen, and hydrogen fluoride residues are avoided after hot nitrogen is dried, so that the production safety is remarkably improved. The generated hydrogen fluoride gas sequentially passes through a '3A molecular sieve + modified acid-resistant molecular sieve 'synergistic adsorption column to deeply remove water, SO2, CO2 and other impurities (the water content is less than or equal to 5ppm, and the content of SO2 and CO2 is less than or equal to 0.5 ppm), and then passes through a light component removal tower and a heavy component removal tower for two-stage rectification purification to remove H2, N2, O2 / Ar and other light components and heavy component impurities, and finally an electronic-grade hydrogen fluoride product with the purity of 5N-8N (99.999%-99.999999%) is obtained. The method overcomes the defects of scarce raw materials and difficulty in impurity removal of a traditional fluorite method, is compact in equipment, low in leakage risk and controllable in energy consumption and cost, solves the industrial problem of efficient purification of electronic-grade hydrogen fluoride, and is suitable for a wafer processing technology in manufacturing of integrated circuits and super-large-scale integrated circuits.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of chemical industry, and particularly relates to a system and method for preparing electronic-grade hydrogen fluoride from industrial-grade sodium fluoride. BACKGROUND

[0002] The traditional production of electronic-grade hydrogen fluoride is based on the traditional fluorination reaction process, uses fluorite (fluorite) as raw material, generates anhydrous hydrogen fluoride by reacting with sulfuric acid, and then removes impurities through multi-stage rectification, purification and other processes to finally obtain high-purity electronic-grade hydrogen fluoride. This technical path is the basis for the early development of the industry, and is still one of the mainstream production methods. The impurity content in fluorite is relatively high, especially the high-grade fluorite (CaF2 content ≥ 97%) accounts for less than 10%, and some needs to rely on imports. Impurities such as metal ions and silicon may be introduced in the subsequent reaction, affecting the purity of hydrogen fluoride. If the purity of the auxiliary raw materials such as sulfuric acid used in the production process is insufficient, impurities will also be introduced, affecting the quality of the final product. For volatile impurities such as arsenic fluoride, special treatment methods such as oxidation are required to prevent them from being distilled out with hydrogen fluoride, and the process control requirements are strict and the purification difficulty is great.

[0003] The electrolytic method has gradually become an important development direction for the production of electronic-grade hydrogen fluoride. This technology generates high-purity fluorine gas by electrolyzing molten fluoride (such as potassium fluoride-lithium fluoride mixed system), and then reacts with hydrogen to synthesize hydrogen fluoride. The electrolytic method does not rely on fluorite raw materials, and the product purity can reach 6N level (99.9999%), and has the characteristics of green and high efficiency, but it is still in the pilot stage and has not been commercialized on a large scale. SUMMARY

[0004] In view of the problems and deficiencies in the prior art, the purpose of the present application is to provide a system and method for preparing electronic-grade hydrogen fluoride from industrial-grade sodium fluoride.

[0005] To achieve the above purpose, the present application adopts the following technical solutions: The first aspect of the present application provides a system for preparing electronic-grade hydrogen fluoride from industrial-grade sodium fluoride, which comprises a three-in-one reactor, a fluorine gas outlet of the three-in-one reactor is communicated with an inlet of a membrane press, an outlet of the membrane press is communicated with an inlet at the bottom of a molecular sieve adsorption column, an outlet at the top of the molecular sieve adsorption column is sequentially connected with a pressure reducing valve and a heat exchanger, and then communicated with a middle section feed inlet of a light-removing tower, an outlet at the bottom of the light-removing tower is communicated with a middle section feed inlet of a heavy-removing tower, and an outlet at the top of the heavy-removing tower is connected with an electronic-grade hydrogen fluoride pipeline; The three-in-one reactor comprises a kettle body, a liftable stirrer axially arranged in the kettle body, the liftable stirrer comprising a stirring shaft and stirring blades, a filter plate arranged at the bottom of the kettle body below the liftable stirrer, a sodium fluoride inlet, a concentrated sulfuric acid inlet, a hydrogen fluoride gas outlet and a high-pressure nitrogen gas inlet arranged at the top of the kettle body, a hot nitrogen gas inlet and a filtrate outlet arranged at the bottom of the kettle body, the high-pressure nitrogen gas inlet also being a hot nitrogen gas outlet, a solid salt outlet arranged at the lower part of the kettle body above the filter plate, and a heat-conducting oil jacket arranged outside the kettle body, the lower part of the heat-conducting oil jacket being provided with a heat-conducting oil inlet and the upper part being provided with a heat-conducting oil outlet.

[0006] Further, the lower part of the molecular sieve adsorption column is filled with acid-resistant molecular sieves and the upper part is filled with modified acid-resistant molecular sieves; the two molecular sieve adsorption columns are connected in parallel, one of which is in operation and the other is standby.

[0007] Further, the kettle body is made of lead or lined with fluorine stainless steel; the materials of the light-removing column and the heavy-removing column are 316L carbon steel lined with fluorine or 316L stainless steel, respectively, and the top of each column is provided with a condenser and a reflux pipeline, and the bottom of each column is provided with a jacketed reboiler.

[0008] The second aspect of the present application provides a method for preparing electronic-grade hydrogen fluoride by using industrial-grade sodium fluoride by using the system of the first aspect, comprising the following steps: (1) passing the concentrated sulfuric acid and the dried and treated sodium fluoride into the three-in-one reactor, respectively, and stirring to react at 200-290 DEG C, and obtaining hydrogen fluoride gas and a solid-liquid mixture after the reaction is completed; (2) passing the hydrogen fluoride gas discharged from the top of the three-in-one reactor into a membrane press for compression, and then sending the compressed hydrogen fluoride gas into the bottom of a molecular sieve adsorption column, the lower part of which is filled with acid-resistant molecular sieves and the upper part is filled with modified acid-resistant molecular sieves, and the hydrogen fluoride gas is sequentially adsorbed by the acid-resistant molecular sieves and the modified acid-resistant molecular sieves, and then discharged from the top of the molecular sieve adsorption column; (3) passing the hydrogen fluoride gas discharged from the molecular sieve adsorption column into a pressure-reducing valve for pressure reduction and a heat exchanger for temperature reduction in sequence, and then into a light-removing column for rectification, and after the rectification is completed, the light components are collected from the top of the column, and the hydrogen fluoride components after the light components are removed are collected from the column bottom; (4) passing the hydrogen fluoride components collected from the column bottom of the light-removing column into a heavy-removing column for rectification, and after the rectification is completed, the heavy components are collected from the column bottom, and the electronic-grade hydrogen fluoride is collected from the top of the column.

[0009] Preferably, in step (1), the molar ratio of the sodium fluoride to the concentrated sulfuric acid is 1: (1.15-1.2).

[0010] Preferably, in step (2), the modified acid-resistant molecular sieve is composed of rare earth metal and molecular sieve matrix, wherein the rare earth metal is lanthanum or cerium, the molecular sieve matrix is at least one of MCM-22, MCM-41, MCM-56 and ZSM-5, and the content of the rare earth metal is 0.01%-0.1% based on the mass of the molecular sieve matrix; and the acid-resistant molecular sieve is 3A molecular sieve.

[0011] Preferably, in step (2), the hydrogen fluoride gas passes through the molecular sieve adsorption column from bottom to top at a flow rate of 200-400 kg / h, a temperature of 30-50 ℃ and a pressure of 7-10 bar.

[0012] Preferably, in step (3), the pressure of the reduced pressure valve after pressure reduction is 2-6 bar, and the temperature of the heat exchanger after temperature reduction is 35-45 ℃.

[0013] Preferably, in step (3), the operating pressure of the light-removing column is 2.5-3 bar, the column bottom temperature is 45.8-53.4 ℃, and the reflux ratio is 10-15.

[0014] Preferably, in step (4), the operating pressure of the heavy-removing column is 2.0-2.5 bar, the column top temperature is 40.2-47.2 ℃, the column bottom temperature is 42.3-47.3 ℃, and the reflux ratio is 5-10.

[0015] Preferably, in step (1), after the reaction in the three-in-one reactor is completed, the feeding is stopped, the hydrogen fluoride gas outlet is closed, high-pressure nitrogen gas is introduced into the kettle body from the high-pressure nitrogen gas inlet, the solid-liquid mixture on the filter plate is separated under the action of the nitrogen gas pressure, the liquid phase residual liquid passes through the filter plate and is discharged from the filtrate outlet at the bottom of the kettle body, and the solid mixture is intercepted above the filter plate; then hot nitrogen gas is introduced from the hot nitrogen gas inlet at the bottom of the kettle body to blow dry the solid mixture, and the dried solid salt is discharged from the solid salt outlet through the liftable stirrer.

[0016] Preferably, in step (1), the sodium fluoride is industrial-grade sodium fluoride with a purity of ≥98%, and the concentrated sulfuric acid is industrial-grade concentrated sulfuric acid with a purity of 98%.

[0017] Preferably, in step (1), the drying treatment of the sodium fluoride is as follows: the sodium fluoride is dried by hot air at 120-180 ℃ until the water content is ≤0.5%, so as to avoid dilution of the sulfuric acid by the water generated in the reaction and reduction of the reaction efficiency.

[0018] Compared with the prior art, the present application has the following beneficial effects: The method of the application generates anhydrous hydrogen fluoride gas and sodium bisulfate by-product under the conditions of 200-290 DEG C and excess sulfuric acid through a three-in-one reactor of "reaction-filter-drying" for double decomposition reaction with industrial-grade sodium fluoride as raw material and 98% industrial-grade concentrated sulfuric acid; the by-product has no hydrogen fluoride residue after filtering by high-pressure nitrogen and drying by hot nitrogen, which significantly improves the production safety. The generated hydrogen fluoride gas passes through a "3A molecular sieve+modified acid-resistant molecular sieve" collaborative adsorption column in sequence to deeply remove water, SO2, CO2 and other impurities (water content ≤5ppm, SO2 and CO2 content ≤0.5ppm), and then is purified by two-stage rectification of a light-removing column and a heavy-removing column to remove H2, N2, O2 / Ar and other light components and heavy component impurities, and finally electronic-grade hydrogen fluoride products with purity of 5N-8N (99.999%-99.999999%) are obtained. The application solves the defects of traditional fluorite method such as raw material scarcity and difficult impurity removal, and has compact equipment, low risk of leakage, controllable energy consumption and cost, solves the industry pain point of efficient purification of electronic-grade hydrogen fluoride, and is suitable for wafer processing technology in integrated circuit and very large scale integrated circuit manufacturing: (1) The three-in-one reactor is used to produce hydrogen fluoride gas in the application, which is simple and compact, reduces the risk of leakage, and solves the problems of long operation period, high safety risk and low production efficiency of the kettle reactor.

[0019] (2) The dried anhydrous hydrogen fluoride is pressurized by a film press, and then passes through two acid-resistant molecular sieves in sequence for adsorption and impurity removal; one is a commercial 3A molecular sieve, and the other is a molecular sieve modified by rare earth elements. The water content in the hydrogen fluoride gas after adsorption and impurity removal can be reduced to <5ppm, and the CO2 and SO2 contents can be reduced to <0.5ppm. After adsorption treatment, there is no water and acidic gas in the hydrogen fluoride gas, which greatly reduces the corrosiveness of acidic gas to stainless steel equipment and reduces equipment investment. In addition, adsorption can remove part of the impurities, which can reduce the separation requirements of rectification separation, especially the difficult-to-separate CO2 and SO2.

[0020] (3) The adsorbed and purified anhydrous hydrogen fluoride is cooled and depressurized, and then enters the light-removing column to remove hydrogen, nitrogen, oxygen / argon, sulfur dioxide and other light component impurities. The light-removing column adopts a kettle, and the heavy component is discharged from the bottom. The high-purity liquefied hydrogen fluoride is collected from the top of the column, and finally electronic-grade hydrogen fluoride products with purity of 5N-8N (99.999%-99.999999%) are obtained. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 It is a system schematic diagram of Example 1 of the application. Figure 2 The figure is a schematic diagram of the three-in-one reactor of the embodiment 1 of the present application.

[0022] In the figure, three-in-one reactor 1, membrane press 2, molecular sieve adsorption column 3, light-removing column 4, heavy-removing column 5, buffer tank 6, filling system 7, sodium fluoride inlet N1, concentrated sulfuric acid inlet N2, hydrogen fluoride gas outlet N3, high-pressure nitrogen gas inlet N4, solid salt outlet N5, filtrate outlet N6, hot nitrogen gas inlet N7, heat-conducting oil inlet N8, heat-conducting oil outlet N9, liftable stirrer I, heat-conducting oil jacket II, stirring paddle III, filter plate IV, speed reducer M. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical scheme and advantages of the present application more clear and obvious, the present application is further described in detail below by combining with the embodiments and the drawings. It should be understood that the specific embodiments described here are only used to explain the present application, and are not used to limit the present application.

[0024] The system for preparing electronic-grade hydrogen fluoride by using industrial-grade sodium fluoride in the following embodiments is shown in Figure 1 , which comprises a three-in-one reactor 1. The hydrogen fluoride gas outlet N3 of the three-in-one reactor 1 is in communication with the inlet of a membrane press 2. The outlet of the membrane press 2 is in communication with the bottom inlet of a molecular sieve adsorption column 3. The top outlet of the molecular sieve adsorption column 3 is connected with a pressure-reducing valve and a heat exchanger in sequence, and then is in communication with the middle feeding inlet of a light-removing column 4. The outlet of the column bottom of the light-removing column 4 is in communication with the middle feeding inlet of a heavy-removing column 5. The top outlet of the heavy-removing column 5 is connected with an electronic-grade hydrogen fluoride pipeline. The electronic-grade hydrogen fluoride pipeline is connected with a buffer tank 6 and a filling system 7 in sequence. The lower part of the molecular sieve adsorption column 3 is filled with acid-resistant molecular sieve, and the upper part is filled with modified acid-resistant molecular sieve. Two molecular sieve adsorption columns 3 are connected in parallel, one of which is in operation and the other is standby. The kettle body of the three-in-one reactor 1 is made of lead or lined with fluorine stainless steel. The materials of the light-removing column 4 and the heavy-removing column 5 are 316L carbon steel lined with fluorine and 316L stainless steel, respectively. Condensers and reflux pipelines are provided at the top of the columns, and jacketed reboilers are provided at the bottom of the columns.

[0025] The specific structure of the three-in-one reactor 1 is shown in Figure 2 , which comprises a kettle body, a liftable stirrer I arranged axially in the kettle body, and a stirring paddle III. The liftable stirrer I comprises a stirring shaft and the stirring paddle III. The end of the stirring shaft extending out of the kettle body is coaxially connected with a speed reducer M. A filter plate IV is arranged at the bottom of the kettle body below the liftable stirrer. The top of the kettle body is provided with a sodium fluoride inlet N1, a concentrated sulfuric acid inlet N2, a hydrogen fluoride gas outlet N3 and a high-pressure nitrogen gas inlet N4. The bottom of the kettle body is provided with a hot nitrogen gas inlet N7 and a filtrate outlet N6. The high-pressure nitrogen gas inlet N4 is also a hot nitrogen gas outlet. The lower part of the kettle body above the filter plate is provided with a solid salt outlet N5. The kettle body is provided with a heat-conducting oil jacket II outside. The lower part of the heat-conducting oil jacket II is provided with a heat-conducting oil inlet N8, and the upper part is provided with a heat-conducting oil outlet N9.

[0026] Example 1 A method for preparing electronic grade hydrogen fluoride from industrial grade sodium fluoride using the above system, the specific steps are as follows: (1) The industrial grade sodium fluoride with purity ≥98% is sent into the hot air dryer, and dried at 120-150°C to the water content ≤0.5%, the dried industrial grade sodium fluoride is continuously sent into the three-in-one reactor 1 through the screw conveyor; at the same time, the acid-resistant pump is used to continuously pump the 98% industrial grade concentrated sulfuric acid into the three-in-one reactor 1 according to the dosage of the molar ratio of sodium fluoride to concentrated sulfuric acid being 1:1.2; the heat conducting oil is introduced into the heat conducting oil jacket II of the three-in-one reactor 1, and the reaction material temperature is controlled at 270°C, under the stirring condition, the sodium fluoride reacts with the concentrated sulfuric acid to generate hydrogen fluoride gas and sodium bisulfate, and the reaction generated hydrogen fluoride gas is continuously led out from the top of the three-in-one reactor 1.

[0027] (2) The hydrogen fluoride gas discharged from the top of the three-in-one reactor 1 is introduced into the membrane compressor 2 to be compressed to 8bar, and then the compressed hydrogen fluoride gas is introduced into the molecular sieve adsorption column 3; the lower part of the molecular sieve adsorption column 3 is filled with 12kg of commercial acid-resistant 3A molecular sieve for deep dehydration, the upper part is filled with 12kg of MCM-22 modified acid-resistant molecular sieve containing 0.05% of rare earth metal lanthanum (La) for removing SO2 and CO2, and the bottom of the molecular sieve is filled with a layer of 1 / 4 inch porcelain balls and a layer of 1 / 8 inch porcelain balls, and the two kinds of molecular sieves are filled with 1 / 8 inch porcelain balls; the hydrogen fluoride gas passes through the molecular sieve adsorption column 3 from bottom to top at a flow rate of 250kg / h under the conditions of 40°C and 8bar pressure, and after adsorption purification, the water content in the hydrogen fluoride gas is reduced to below 5ppm, and the contents of SO2 and CO2 are reduced to below 0.5ppm.

[0028] (3) The molar composition of the hydrogen fluoride gas discharged from the molecular sieve adsorption column 3 is: HF 0.999594, hydrogen 0.00008, nitrogen 0.00008, water 0.000005, oxygen / argon 0.00016, SO2 0.0000005, CO2 0.0000005, CO 0.00008. The gas is depressurized to a pressure of 3 bar through a pressure reducing valve. At this pressure, there is no azeotrope among the internal components of the hydrogen fluoride gas. The gas is then cooled to 20-25°C through a heat exchanger, and then enters the light component removal column 4 at a flow rate of 250 kg / h. The temperature at the bottom of the light component removal column 4 is 53.4°C, and the pressure in the column is 3 bar. The overhead condenser is started, and liquid phase reflux is generated. The reboiler at the bottom of the column is started, and rising vapor is generated. The rising vapor is condensed into liquid phase by the coolant, and most of it returns to the column. A small part is discharged as non-condensable gas, and the reflux ratio is 15. The hydrogen fluoride component after removal of light components is discharged from the bottom of the light component removal column 4, and automatically enters the heavy component removal column 5 through pressure difference. The light components are hydrogen (H2), nitrogen (N2), oxygen / argon (O2 / Ar), sulfur dioxide (SO2), etc.

[0029] (4) The hydrogen fluoride component taken from the bottom of the light component removal column 4 enters the middle section of the heavy component removal column 5 at a flow rate of 127.8 kg / h. The pressure at the top of the heavy component removal column 5 is 2.5 bar, the temperature at the top is 47.2°C, and the temperature at the bottom is 47.3°C. The reflux ratio is 10. The heavy components are discharged from the bottom of the heavy component removal column 5 at a flow rate of 27.8 kg / h. The electronic grade hydrogen fluoride is taken from the top of the heavy component removal column 5 at a flow rate of 100 kg / h, with a purity of >99.99999% (>6N grade) and a water content of less than 10 ppb. After passing through the buffer tank 6, it goes to the filling system 7.

[0030] (5) After the reaction in the three-in-one reactor 1 in step (1) is completed, the feeding is stopped, and the hydrogen fluoride gas outlet is closed. High pressure nitrogen gas is introduced into the kettle body from the high pressure nitrogen gas inlet N4. The solid-liquid mixture on the filter plate IV is separated under the action of nitrogen pressure. The liquid residue passes through the filter plate IV and is discharged from the filtrate outlet N6 at the bottom of the kettle body. The solid mixture of sodium bisulfate and a small amount of unreacted sodium fluoride is trapped above the filter plate IV. Then hot nitrogen gas is introduced from the hot nitrogen gas inlet N7 at the bottom of the kettle body to blow dry the solid mixture of sodium bisulfate and a small amount of unreacted sodium fluoride, obtaining a solid salt free of sulfuric acid and hydrogen fluoride gas. The dried solid salt is discharged from the solid salt outlet N5 through the liftable stirrer I. The three-in-one reactor 1 is ready for the next batch production.

[0031] Example 2: A method for preparing electronic grade hydrogen fluoride from industrial grade sodium fluoride using the above system, the specific steps are as follows: (1) The industrial grade sodium fluoride with purity ≥98% is sent into a hot air dryer, and dried at 140-180°C until the water content is ≤0.1%. The dried industrial grade sodium fluoride is continuously sent into a three-in-one reactor 1 by a screw conveyor. At the same time, 98% industrial grade concentrated sulfuric acid is continuously pumped into the three-in-one reactor 1 by an acid-resistant pump according to the dosage of 1:1.15 of the molar ratio of sodium fluoride to concentrated sulfuric acid. The heat conducting oil is introduced into the heat conducting oil jacket II of the three-in-one reactor 1, and the temperature of the reaction material is controlled at 275°C. Under the condition of stirring, the sodium fluoride reacts with the concentrated sulfuric acid to generate hydrogen fluoride gas and sodium bisulfate, and the generated hydrogen fluoride gas is continuously led out from the top of the three-in-one reactor 1.

[0032] (2) The hydrogen fluoride gas discharged from the top of the three-in-one reactor 1 is compressed to 0.8Mpa by a membrane compressor 2, and then the compressed hydrogen fluoride gas is introduced into a molecular sieve adsorption column 3. The lower part of the molecular sieve adsorption column 3 is filled with 20kg of commercial acid-resistant 3A molecular sieve for deep dehydration, and the upper part is filled with 30kg of ZSM-5 modified acid-resistant molecular sieve containing 0.03% of rare earth metal cerium (Ce) for removing SO2 and CO2. A layer of 1 / 4 inch porcelain balls and a layer of 1 / 8 inch porcelain balls are filled at the bottom of the molecular sieve, and 1 / 8 inch porcelain balls are filled between the two kinds of molecular sieves. The hydrogen fluoride gas passes through the molecular sieve adsorption column 3 from bottom to top at a flow rate of 400kg / h under the conditions of 30°C and 8bar pressure. After adsorption purification, the water content in the hydrogen fluoride gas is reduced to below 3ppm, and the contents of SO2 and CO2 are reduced to below 0.55ppm.

[0033] (3) The molar composition of the hydrogen fluoride gas discharged from the molecular sieve adsorption column 3 is: HF is 0.999, hydrogen is 0.00006, nitrogen is 0.00005, water is 0.000001, oxygen / argon is 0.0002, SO2 is 0.1ppm, and CO2 is 0.1ppm, and CO is 0.0001. The gas is depressurized to a pressure of 2.5bar by a pressure reducing valve. Under this pressure, there is no azeotrope among the internal components of the hydrogen fluoride gas. The gas is then cooled to 20-25°C by a heat exchanger, and then enters a light component removal column 4 at a flow rate of 400kg / h. The temperature at the bottom of the light component removal column 4 is 45.8°C, and the pressure in the column is 2.5bar. The overhead condenser is started, and liquid phase reflux is generated. The reboiler at the bottom of the column is started, and the rising steam is generated. The rising steam is condensed into liquid phase by a refrigerant, most of which returns to the column, and a small part is discharged as non-condensable gas. The reflux ratio is 10. The hydrogen fluoride gas after removal of light components is discharged from the bottom of the light component removal column 4, and automatically enters a heavy component removal column 5 by pressure difference. The light components include hydrogen (H2), nitrogen (N2), oxygen / argon (O2 / Ar), sulfur dioxide (SO2), etc.

[0034] (4) The hydrogen fluoride gas taken from the bottom of the light component removal column 3 is introduced into the middle section of the heavy component removal column 5 at a flow rate of 180.5 kg / h. The pressure at the top of the heavy component removal column 5 is 2.0 bar, the temperature at the top is 40.2°C, the temperature at the bottom is 42.3°C, and the reflux ratio is 5. The heavy components are removed from the bottom of the heavy component removal column 5 at a flow rate of 35.5 kg / h, and the electronic grade hydrogen fluoride is taken from the top of the heavy component removal column 5 at a flow rate of 180 kg / h. The purity of the electronic grade hydrogen fluoride is >99.99995% (>6N grade), and the water content is less than 30 ppb. The electronic grade hydrogen fluoride is sent to the filling system 7 after passing through the buffer tank 6.

[0035] (5) After the reaction in the three-in-one reactor 1 in step (1) is completed, the feeding is stopped, the hydrogen fluoride gas outlet is closed, and high-pressure nitrogen gas is introduced into the reactor body from the high-pressure nitrogen gas inlet N4. The solid-liquid mixture on the filter plate IV is separated under the action of the nitrogen gas pressure, and the liquid phase residual liquid is discharged from the filter liquid outlet N6 at the bottom of the reactor body. The solid mixture of sodium bisulfate and a small amount of unreacted sodium fluoride is intercepted above the filter plate IV. Then, hot nitrogen gas is introduced from the hot nitrogen gas inlet N7 at the bottom of the reactor body to blow dry the solid mixture of sodium bisulfate and a small amount of unreacted sodium fluoride, thereby obtaining a solid salt containing no sulfuric acid and hydrogen fluoride gas. The dried solid salt is discharged from the solid salt outlet N5 through the liftable stirrer I. The three-in-one reactor 1 is ready for the next batch production.

[0036] The above examples are only used to illustrate the technical solutions of the present application, and are not intended to limit the protection scope of the present application. Based on the idea of the present application, those skilled in the art can modify or equivalently replace the technical solutions of the present application without departing from the essence and scope of the present application.

Claims

1. A system for preparing electronic-grade hydrogen fluoride using industrial-grade sodium fluoride, characterized in that, It includes a three-in-one reactor. The hydrogen fluoride gas outlet of the three-in-one reactor is connected to the inlet of the membrane press. The outlet of the membrane press is connected to the bottom inlet of the molecular sieve adsorption column. The top outlet of the molecular sieve adsorption column is connected to a pressure reducing valve and a heat exchanger in sequence, and then connected to the feed inlet of the middle section of the light-light removal tower. The bottom outlet of the light-light removal tower is connected to the feed inlet of the middle section of the heavy-light removal tower. The top outlet of the heavy-light removal tower is connected to an electronic-grade hydrogen fluoride pipeline. The three-in-one reactor includes a vessel body and a liftable agitator axially arranged within the vessel body. The liftable agitator includes a stirring shaft and stirring blades. A filter plate is located at the bottom of the vessel body below the liftable agitator. The top of the vessel body has a sodium fluoride inlet, a concentrated sulfuric acid inlet, a hydrogen fluoride gas outlet, and a high-pressure nitrogen inlet. The bottom of the vessel body has a hot nitrogen inlet and a filtrate outlet. The high-pressure nitrogen inlet is also the hot nitrogen outlet. A solid salt outlet is located above the filter plate at the lower part of the vessel body. A heat transfer oil jacket is located outside the vessel body. The lower part of the heat transfer oil jacket has a heat transfer oil inlet, and the upper part has a heat transfer oil outlet.

2. The system for preparing electronic-grade hydrogen fluoride using industrial-grade sodium fluoride according to claim 1, characterized in that, The lower part of the molecular sieve adsorption column is filled with acid-resistant molecular sieve, and the upper part is filled with modified acid-resistant molecular sieve; two molecular sieve adsorption columns are connected in parallel, with one in operation and the other on standby.

3. The system for preparing electronic-grade hydrogen fluoride using industrial-grade sodium fluoride according to claim 1, characterized in that, The vessel body is made of lead or fluorine-lined stainless steel; the light-weight removal tower and the heavy-weight removal tower are made of 316L carbon steel lined with fluorine or 316L stainless steel, respectively. The top of each tower is equipped with a condenser and a reflux pipe, and the bottom of each tower is equipped with a jacketed reboiler.

4. A method for preparing electronic-grade hydrogen fluoride from industrial-grade sodium fluoride using the system described in any one of claims 1-3, characterized in that, Includes the following steps: (1) Concentrated sulfuric acid and dried sodium fluoride were introduced into a three-in-one reactor and stirred at 200-290°C to react. After the reaction was completed, hydrogen fluoride gas and a solid-liquid mixture were obtained. (2) The hydrogen fluoride gas discharged from the top of the three-in-one reactor is compressed by a membrane press. Then the compressed hydrogen fluoride gas is sent from the bottom of the molecular sieve adsorption column. The lower part of the molecular sieve adsorption column is filled with acid-resistant molecular sieve and the upper part is filled with modified acid-resistant molecular sieve. After being adsorbed by the acid-resistant molecular sieve and the modified acid-resistant molecular sieve in sequence, the hydrogen fluoride gas is discharged from the top of the molecular sieve adsorption column. (3) The hydrogen fluoride gas discharged from the molecular sieve adsorption column is first passed through a pressure reducing valve to reduce pressure and a heat exchanger to cool down, and then passed through a light component removal column for distillation. After distillation, the light component is taken out from the top of the column, and the hydrogen fluoride component after the light component is removed is taken out from the bottom of the column. (4) The hydrogen fluoride component collected from the bottom of the light removal tower is fed into the heavy removal tower for distillation. After distillation, the heavy component is collected from the bottom of the tower and the electronic grade hydrogen fluoride is collected from the top of the tower.

5. The method for preparing electronic-grade hydrogen fluoride using industrial-grade sodium fluoride according to claim 4, characterized in that, In step (1), the molar ratio of sodium fluoride to concentrated sulfuric acid is 1:(1.15~1.2).

6. The method for preparing electronic-grade hydrogen fluoride using industrial-grade sodium fluoride according to claim 4, characterized in that, In step (2), the modified acid-resistant molecular sieve is composed of rare earth metals and a molecular sieve matrix, wherein the rare earth metals are lanthanum or cerium, and the molecular sieve matrix is ​​at least one of MCM-22, MCM-41, MCM-56 and ZSM-5, and the content of rare earth metals is 0.01% to 0.1% based on the mass of the molecular sieve matrix; the acid-resistant molecular sieve is 3A molecular sieve.

7. The method for preparing electronic-grade hydrogen fluoride using industrial-grade sodium fluoride according to claim 4, characterized in that, In step (2), hydrogen fluoride gas passes through the molecular sieve adsorption column from bottom to top at a flow rate of 200-400 kg / h, a temperature of 30-50°C, and a pressure of 7-10 bar.

8. The method for preparing electronic-grade hydrogen fluoride using industrial-grade sodium fluoride according to claim 4, characterized in that, In step (3), the pressure after the pressure reducing valve is reduced is 2 to 6 bar, and the temperature after the heat exchanger is cooled is 35 to 45°C.

9. The method for preparing electronic-grade hydrogen fluoride using industrial-grade sodium fluoride according to claim 4, characterized in that, In step (3), the operating pressure of the light-weight removal tower is 2.5-3 bar, the bottom temperature is 45.8-53.4℃, and the reflux ratio is 10-15; in step (4), the operating pressure of the heavy-weight removal tower is 2.0-2.5 bar, the top temperature is 40.2-47.2℃, the bottom temperature is 42.3-47.3℃, and the reflux ratio is 5-10.

10. The method for preparing electronic-grade hydrogen fluoride using industrial-grade sodium fluoride according to any one of claims 4-9, characterized in that, After the reaction is complete, stop feeding, close the hydrogen fluoride gas outlet, and introduce high-pressure nitrogen into the reactor through the high-pressure nitrogen inlet. The solid-liquid mixture on the filter plate is separated under the pressure of nitrogen. The liquid residue passes through the filter plate and is discharged from the filtrate outlet at the bottom of the reactor, while the solid mixture is trapped above the filter plate. Then, hot nitrogen is introduced through the hot nitrogen inlet at the bottom of the reactor to dry the solid mixture. The dried solid salt is discharged from the solid salt outlet through a liftable stirrer.

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