Device and method for removing water from anhydrous hydrogen fluoride

Abstract

The present invention discloses a device for removing water from anhydrous hydrogen fluoride, comprising an electrolytic cell body, an electrolytic cell upper cover, an anode plate, a cathode plate and a partition. An electrolytic chamber is arranged in the electrolytic cell body, and the anode plate, the cathode plate and the partition are all located in the electrolytic chamber. The anode plate is fixed in the electrolytic cell body and separates the lower space of the electrolytic chamber. The cathode plate is fixed to the electrolytic cell upper cover and extends to the bottom of the electrolytic chamber. The partition is fixed to the electrolytic cell upper cover and is located between the anode plate and the cathode plate. The partition separates the upper space of the electrolytic chamber into an anode gas chamber and a cathode gas chamber. Through the innovative design of the electrode sheet and the electrolytic cell, continuous water removal treatment of anhydrous hydrogen fluoride is achieved, and the removal efficiency is improved. The present invention also discloses a method for removing water from anhydrous hydrogen fluoride based on the above-mentioned device for removing water from anhydrous hydrogen fluoride. The electrolytic method is used to remove trace water in anhydrous hydrogen fluoride, and continuous treatment can be achieved. No oxidizing agent or adsorbent such as fluorine gas is required, and the treatment process is simple and efficient.

Description

Technical Field

[0001] The invention relates to the field of inorganic fine chemicals, and in particular to a device and method for removing water from anhydrous hydrogen fluoride. Background Art

[0002] Anhydrous hydrogen fluoride is a chemical product with a wide range of uses. The content of hydrogen fluoride is above 99.8%. It is a colorless fuming liquid and is easily gasified under reduced pressure or high temperature. Anhydrous hydrogen fluoride has been widely used in atomic energy, chemical industry, petroleum and other industries. It is a strong oxidant and a basic raw material for the preparation of elemental fluorine, various fluorine refrigerants, inorganic fluorides, and various organic fluorides. It can be prepared into aqueous hydrofluoric acid for various purposes, used in the manufacture of graphite and catalysts for the manufacture of organic compounds. It is a raw material for the production of refrigerant "Freon", fluorine-containing resins, organic fluorides and fluorine. In chemical production, it can be used as a catalyst for organic synthesis such as alkylation, polymerization, condensation, and isomerization. It is also used to corrode strata when mining certain mineral deposits, as well as to extract rare earth elements and radioactive elements. In the atomic energy industry and nuclear weapons production, it is a raw material for the manufacture of uranium hexafluoride, and is also a raw material for the production of rocket fuel and additives. In addition, anhydrous hydrogen fluoride is also used as a solvent for the synthesis of lithium hexafluorophosphate, an electrolyte for lithium batteries.

[0003] When anhydrous hydrogen fluoride is used for organic synthesis, fluorine production, and lithium hexafluorophosphate production, trace amounts of water in it can easily cause product quality to deteriorate and pose serious safety hazards. Therefore, it is often necessary to remove water from the anhydrous hydrogen fluoride raw material before the reaction. Anhydrous hydrogen fluoride is usually produced by hydrofluoric acid distillation. According to the requirements of GB7746-2011 "Industrial Anhydrous Hydrogen Fluoride", the moisture content of Class II qualified industrial anhydrous hydrogen fluoride products is ≤600ppm, and the moisture content of Class I is ≤50ppm. On the one hand, the distillation cost required to meet the moisture requirements of Class I is relatively high. At the same time, anhydrous hydrogen fluoride will also absorb moisture from the environment during filling, storage and transportation, causing the moisture content to increase. When conducting a synthetic reaction, it is often necessary to reduce the moisture content in anhydrous hydrogen fluoride to below 20ppm, so the anhydrous hydrogen fluoride needs to be treated to reduce the moisture content before the reaction.

[0004] At present, the main methods for removing water from hydrogen fluoride are adsorption, fluorine gas oxidation and electrochemical oxidation.

[0005] U.S. Patent No. 5,597,545 discloses a method for adsorbing water in hydrogen fluoride by carbon molecular sieve, which comprises: contacting hydrogen fluoride with carbon molecular sieve, adsorbing water in hydrogen fluoride, and also adsorbing a part of hydrogen fluoride; then heating the molecular sieve to decompose the adsorbed water and hydrogen fluoride; then continuing to heat, completely decomposing hydrogen fluoride, and recovering the carbon molecular sieve. This method has low water removal efficiency and high processing cost.

[0006] Fluorine gas can oxidize the water in hydrogen fluoride to generate hydrogen fluoride and oxygen difluoride. The boiling point of oxygen difluoride is -154°C, while the boiling point of hydrogen fluoride is 19.5°C. Therefore, oxygen difluoride is easy to separate from liquid anhydrous hydrogen fluoride:

[0007] 2F2+H2O→2HF+OF2

[0008] However, the cost of preparing fluorine gas by electrolysis is high, and fluorine gas is highly oxidizing, with violent water removal reactions, high requirements on equipment materials, and high risks. Summary of the invention

[0009] According to one aspect of the present invention, a device for removing water from anhydrous hydrogen fluoride is provided, comprising an electrolytic cell body, an electrolytic cell upper cover, an anode plate, a cathode plate and a partition, wherein an electrolytic chamber is arranged in the electrolytic cell body, a liquid inlet is arranged at one end of the electrolytic cell body, a liquid outlet is arranged at the other end of the electrolytic cell body, the upper end of the electrolytic cell body is open, the electrolytic cell upper cover is fixed to the electrolytic cell body and seals the upper end of the electrolytic cell body, the anode plate, the cathode plate and the partition are all located in the electrolytic chamber, the anode plate is fixed to the electrolytic cell body and separates the lower space of the electrolytic chamber, the cathode plate is fixed to the electrolytic cell upper cover and extends to the bottom of the electrolytic chamber, the partition is fixed to the electrolytic cell upper cover and is located between the anode plate and the cathode plate, and the partition separates the upper space of the electrolytic chamber into an anode gas chamber and a cathode gas chamber.

[0010] In some embodiments, the electrolytic cell upper cover is provided with an anode gas chamber outlet and a cathode gas chamber outlet, the anode gas chamber outlet is connected to the anode gas chamber, and the cathode gas chamber outlet is connected to the cathode gas chamber.

[0011] In some embodiments, the anode plate, cathode plate and separator are all provided in multiple pieces, and the anode plates and cathode plates are alternately arranged in sequence to form an S-shaped liquid flow channel between the liquid inlet and the liquid outlet of the electrolytic cell body.

[0012] In some embodiments, the anode plate, cathode plate and separator are vertically spaced and evenly arranged parallel to each other, the anode plate and cathode plate are made of stainless steel or nickel, and the separator is made of polytetrafluoroethylene.

[0013] In some embodiments, a liquid level line is provided in the electrolytic cell body, the upper end of the anode plate is lower than the liquid level line, and the lower end of the partition is lower than the liquid level line.

[0014] In some embodiments, the distance between the lower end of the cathode plate and the bottom surface of the electrolysis chamber is 10 mm to 150 mm, and the distance between the cathode and the anode is 15 mm to 300 mm.

[0015] In some embodiments, the device for removing water from anhydrous hydrogen fluoride further includes a DC power supply, the anode plate is connected to the positive electrode of the DC power supply, the cathode plate is connected to the negative electrode of the DC power supply, and the voltage of the DC power supply is 3V to 7V.

[0016] In some embodiments, the device for removing water from anhydrous hydrogen fluoride further includes a liquid inlet valve and a liquid outlet valve, wherein the liquid inlet valve is connected to the liquid inlet, and the liquid outlet valve is connected to the liquid outlet.

[0017] According to another aspect of the present invention, there is provided a method for removing water from anhydrous hydrogen fluoride, comprising the following steps:

[0018] 1) Open the liquid inlet valve and deliver anhydrous hydrogen fluoride into the electrolysis chamber through the liquid inlet;

[0019] 2) electrifying the anode plate and the cathode plate to cause an ionization reaction on the anode plate and the cathode plate and decompose the water in the hydrogen fluoride to generate oxygen difluoride gas on the anode plate and hydrogen gas on the cathode plate;

[0020] 3) When the hydrogen fluoride liquid level reaches the liquid level line, open the liquid outlet valve to allow the dehydrated anhydrous hydrogen fluoride to enter the reaction device or be collected in the product storage tank. Hydrogen fluoride continuously passes through the electrolytic cell body to continuously treat the water in the hydrogen fluoride.

[0021] In some embodiments, the following steps are also included:

[0022] 4) collecting the gas generated on the anode plate with the anode gas chamber, and collecting the gas generated on the cathode plate with the cathode gas chamber;

[0023] 5) The gases collected in the anode gas chamber and the cathode gas chamber are condensed and refluxed into hydrogen fluoride, and the non-condensable gases are purified and discharged after reaching the standards. The non-condensable gas in the anode gas chamber is OF2, which is absorbed by alkaline solution and reacts to generate sodium fluoride and oxygen. Some uncondensed hydrogen fluoride also reacts with the alkali to generate sodium fluoride:

[0024] OF2+2NaOH→2NaF+H2O+O2↑

[0025] HF+NaOH→NaF+H2O

[0026] The non-condensable gas in the cathode gas chamber is H2, which is also purified by washing with alkaline solution. Some of the uncondensed hydrogen fluoride reacts with the alkali to form sodium fluoride.

[0027] The beneficial effects of the present invention are as follows: the present invention utilizes the principle of electrolysis to rationally design a device and method for removing water from anhydrous hydrogen fluoride, and realizes continuous water removal of anhydrous hydrogen fluoride through innovative design of electrode sheets and electrolytic cells, thereby improving removal efficiency. The device of the present invention is made of corrosion-resistant materials and can effectively avoid hydrofluoric acid corrosion. The electrolysis method is used to remove trace amounts of water in anhydrous hydrogen fluoride, which can achieve continuous treatment, and does not require the use of oxidizing agents or adsorbents such as fluorine gas, and the treatment process is simple and efficient. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a schematic structural diagram of a device for removing water from anhydrous hydrogen fluoride according to one embodiment of the present invention;

[0029] Figure 2 for Figure 1 AA top view of the device for removing water from anhydrous hydrogen fluoride;

[0030] Figure 3 for Figure 1 A schematic structural diagram of a cathode plate of a device for removing water from anhydrous hydrogen fluoride;

[0031] Figure 4 for Figure 1 The diagram shows the usage status of the device for removing water from anhydrous hydrogen fluoride. DETAILED DESCRIPTION

[0032] Example 1

[0033] Figure 1 to Figure 4 A device for removing water from anhydrous hydrogen fluoride according to an embodiment of the present invention is schematically shown.

[0034] Reference Figure 1 to Figure 4 A device for removing water from anhydrous hydrogen fluoride includes an electrolytic cell body 1, an electrolytic cell upper cover 2, an anode plate 3, a cathode plate 4, a partition 5, a liquid inlet valve 6, a liquid outlet valve 7 and a DC power supply 8.

[0035] The electrolytic cell body 1 is square, and an electrolytic chamber 13 is arranged in the electrolytic cell body 1. A liquid inlet 11 is arranged at one end of the electrolytic cell body 1, and a liquid outlet 12 is arranged at the other end of the electrolytic cell body 1. The upper end of the electrolytic cell body 1 is open, and the edge of the electrolytic cell upper cover 2 is bolted to the edge of the electrolytic cell body 1 and seals the upper end of the electrolytic cell body 1, so that the electrolytic chamber 13 becomes a closed space. The anode plate 3, the cathode plate 4 and the partition 5 are all located in the electrolytic chamber, the anode plate 3 is fixed in the electrolytic cell body 1 and separates the lower space of the electrolytic chamber 13, and the cathode plate 4 is fixed to the electrolytic cell upper cover 2 and extends to the bottom of the electrolytic chamber 13. The partition 5 is fixed to the electrolytic cell upper cover 2 and is located between the anode plate 3 and the cathode plate 4, and the partition 5 separates the upper space of the electrolytic chamber 13 into an anode gas chamber 14 and a cathode gas chamber 15.

[0036] The electrolytic cell upper cover 2 is provided with an anode gas chamber outlet 21 and a cathode gas chamber outlet 22, the anode gas chamber outlet 21 is connected to the anode gas chamber 14, and the cathode gas chamber outlet 22 is connected to the cathode gas chamber 15. The anode gas chamber outlet 21 and the cathode gas chamber outlet 22 are connected to the reflux device 91 and the purification device 92 respectively.

[0037] The anode plate 3, cathode plate 4 and partition plate 5 are vertically spaced and evenly arranged parallel to each other. The anode plate 3, cathode plate 4 and partition plate 5 are arranged in multiple pieces. The anode plate 3 and cathode plate 4 are alternately arranged in sequence to form an S-shaped liquid flow channel between the liquid inlet 11 and the liquid outlet 12 of the electrolytic cell body 1.

[0038] A liquid level line 16 is provided in the electrolytic cell body 1, the upper end of the anode plate 3 is lower than the liquid level line 16, and the lower end of the partition 5 is lower than the liquid level line 16. When the liquid in the electrolytic cell body 1 reaches the liquid level line 16, it can be ensured that the liquid in the electrolytic cell body 1 can flow smoothly in an S-shaped line.

[0039] The anode plate 3 and the cathode plate 4 can be made of stainless steel or nickel, and the separator 5 can be made of polytetrafluoroethylene. The distance between the lower end of the cathode plate 4 and the bottom surface of the electrolytic chamber 13 is 10mm-150mm, and the distance between the cathode and the anode is 15mm-300mm.

[0040] The anode plate 3 is connected to the positive electrode of the DC power supply 8, and the cathode plate 4 is connected to the negative electrode of the DC power supply 8. The voltage of the DC power supply 8 is 3V to 7V.

[0041] The inlet valve 6 is connected to the liquid inlet 11, and the outlet valve 7 is connected to the liquid outlet 12. The liquid level in the electrolytic cell body 1 and the liquid circulation speed can be controlled by the inlet valve 6 and the outlet valve 7.

[0042] The upper portion of the cathode plate 4 is provided with a notch 41 penetrating the cathode plate 4 , so that two sides of the cathode plate 4 form a communicating space, so that the two sides of the cathode plate 4 only need to share one air outlet.

[0043] The outer side of the electrolytic cell body 1 is also provided with an insulation layer 17, which can ensure the temperature of the electrolytic cell body 1 is stable, ensure that the anhydrous hydrogen fluoride is always in a liquid state in the electrolytic cell, and the electrolysis process proceeds smoothly. The electrolytic cell body 1 and the electrolytic cell upper cover 2 are provided with a sealing ring to ensure the sealing between the electrolytic cell body 1 and the electrolytic cell upper cover 2.

[0044] Through the structural design of the electrolytic cell body, the partition 5 and the anhydrous HF liquid level divide the gas phase space in the upper part of the cell into an anode gas chamber 14 and a cathode gas chamber 15. Since the gas density generated on the surface of the anode plate 3 and the cathode plate 4 is relatively small, they enter the anode gas chamber 14 and the cathode gas chamber 15 respectively after floating, and then enter the condensation reflux device through the anode gas chamber outlet 21 and the cathode gas chamber outlet 22 respectively. By setting up the anode gas chamber 14 and the cathode gas chamber 15 separately, the hydrogen generated by the cathode plate 4 is prevented from contacting with the oxidizing gas generated by the anode plate 3 to generate safety hazards. There is a certain gap between the lower end of the cathode and the bottom surface of the electrolytic cell, and the anode is directly fixed to the bottom surface of the electrolytic cell. Through the setting of the anode and the cathode, the anhydrous HF is folded in an up and down S shape in the electrolytic cell, so that the anhydrous HF is fully in contact with the electrode surface for electrolytic dehydration, thereby improving the water removal efficiency.

[0045] Example 2

[0046] A method for applying the device for removing water from anhydrous hydrogen fluoride in Example 1 comprises the following steps:

[0047] 1) Open the liquid inlet valve 6 and deliver the anhydrous hydrogen fluoride in the storage container into the electrolysis chamber 13 through the liquid inlet 11;

[0048] 2) Turning on the DC power supply 8, and energizing the anode plate 3 and the cathode plate 4, so that an ionization reaction occurs on the anode plate 3 and the cathode plate 4 to decompose the water in the hydrogen fluoride, generating oxygen difluoride gas on the anode plate 3 and generating hydrogen gas on the cathode plate 4;

[0049] Electrolysis of anhydrous hydrogen fluoride can also remove trace amounts of water. The principle is that due to the presence of water, part of the hydrogen fluoride is ionized into hydrogen ions and fluoride ions. After power is applied, the hydrogen ions gain electrons and release hydrogen gas at the cathode, and the water molecules are oxidized to generate oxygen difluoride at the anode:

[0050]

[0051] Cathode: 4H + +4e→2H2↑

[0052] Anode: H2O+4F - -4e - →OF2↑+2HF

[0053] 3) After the hydrogen fluoride liquid level reaches the liquid level line 16, the liquid outlet valve 7 is opened to allow the dehydrated anhydrous hydrogen fluoride to pass into the reaction device or be collected in the product storage tank, and the hydrogen fluoride can continuously pass through the electrolytic cell body 1. The water in hydrogen fluoride can be continuously processed, providing technical and equipment support for continuous industrial production.

[0054] 4) The oxygen difluoride gas generated on the anode plate 3 is collected by the anode gas chamber 14 disposed on the upper part of the anode plate 3, and the hydrogen gas generated on the cathode plate 4 is collected by the cathode gas chamber 15 disposed on the upper part of the cathode plate 4; the gases generated on the anode plate 3 and the cathode plate 4 are collected separately to avoid safety hazards caused by the contact between the hydrogen generated at the cathode and the oxidizing gas generated at the anode.

[0055] 5) The gases collected in the anode gas chamber 14 and the cathode gas chamber 15 are separated and recovered from hydrogen fluoride by the reflux device 91, and the non-condensable gases are purified by the purification device 92 to meet the standards before being discharged. The gases collected in the anode gas chamber 14 include hydrogen and gaseous HF, and the gases collected in the cathode gas chamber 15 include OF2 and gaseous HF. They are purified by sodium hydroxide solution or sodium carbonate solution respectively, and can be directly discharged after absorbing OF2 and HF.

[0056] After being treated by the above equipment and method, the water content of anhydrous HF with a water content of about 150ppm can be reduced to 10ppm after electrolytic dehydration.

[0057] The above are only some embodiments of the present invention. For those skilled in the art, several modifications and improvements can be made without departing from the inventive concept of the present invention, which all belong to the protection scope of the invention.

Claims

1. A device for removing water from anhydrous hydrogen fluoride, characterized in that: The electrolytic cell comprises an electrolytic cell body (1), an electrolytic cell upper cover (2), an anode plate (3), a cathode plate (4), a partition (5), a liquid inlet valve (6) and a liquid outlet valve (7); the electrolytic cell body (1) is provided with an electrolytic chamber (13); one end of the electrolytic cell body (1) is provided with a liquid inlet (11); the other end of the electrolytic cell body (1) is provided with a liquid outlet (12); the upper end of the electrolytic cell body (1) is open; the electrolytic cell upper cover (2) is fixed to the electrolytic cell body (1) and seals the upper end of the electrolytic cell body (1); the anode plate (3), the cathode plate (4) and the partition (5) are all located in the electrolytic chamber; the anode plate (3) is fixed to the electrolytic cell body (1) and separates the lower space of the electrolytic chamber (13); the cathode plate (4) is fixed to the electrolytic cell upper cover (2) and extends toward the bottom of the electrolytic chamber (13); the partition (5) is fixed to the electrolytic cell upper cover (2) and extends toward the bottom of the electrolytic chamber (13); The electrolytic cell is fixed on the upper cover (2) and is located between the anode plate (3) and the cathode plate (4); the partition (5) divides the upper space of the electrolytic chamber (13) into an anode gas chamber (14) and a cathode gas chamber (15); the anode plate (3), the cathode plate (4) and the partition (5) are all arranged in multiple pieces; the anode plate (3) and the cathode plate (4) are arranged alternately in sequence so that an S-shaped liquid flow channel is formed between the liquid inlet (11) and the liquid outlet (12) of the electrolytic cell body (1); the upper cover (2) of the electrolytic cell is provided with an anode gas chamber outlet (21) and a cathode gas chamber outlet (22); the anode gas chamber outlet (21) is connected to the anode gas chamber (14), and the cathode gas chamber outlet (22) is connected to the cathode gas chamber (15); the liquid inlet valve (6) is connected to the liquid inlet (11), and the liquid outlet valve (7) is connected to the liquid outlet (12).

2. The device for removing water from anhydrous hydrogen fluoride according to claim 1, characterized in that: The anode plate (3), cathode plate (4) and separator (5) are all vertically spaced and evenly arranged parallel to each other; the anode plate (3) and cathode plate (4) are made of stainless steel or nickel, and the separator (5) is made of polytetrafluoroethylene.

3. The device for removing water from anhydrous hydrogen fluoride according to claim 1 or 2, characterized in that A liquid level line (16) is provided in the electrolytic cell body (1), the upper end of the anode plate (3) is lower than the liquid level line (16), and the lower end of the partition (5) is lower than the liquid level line (16).

4. The device for removing water from anhydrous hydrogen fluoride according to claim 3, characterized in that: The distance between the lower end of the cathode plate (4) and the bottom surface of the electrolytic chamber (13) is 10 mm to 150 mm, and the distance between the cathode and the anode is 15 mm to 300 mm.

5. The device for removing water from anhydrous hydrogen fluoride according to claim 1, characterized in that: It also comprises a DC power supply (8), the anode plate (3) is connected to the positive electrode of the DC power supply (8), the cathode plate (4) is connected to the negative electrode of the DC power supply, and the voltage of the DC power supply is 3V to 7V.

6. The method for removing water from anhydrous hydrogen fluoride according to the device for removing water from anhydrous hydrogen fluoride according to claim 3, characterized in that: The steps include: 1) Opening the liquid inlet valve (6) and delivering anhydrous hydrogen fluoride into the electrolysis chamber (13) through the liquid inlet (11); 2) electrifying the anode plate (3) and the cathode plate (4) so ​​that an ionization reaction occurs on the anode plate (3) and the cathode plate (4) and water in the hydrogen fluoride is decomposed to generate oxygen difluoride gas on the anode plate (3) and hydrogen gas on the cathode plate (4); 3) After the hydrogen fluoride liquid level reaches the liquid level line (16), the liquid outlet valve (7) is opened to allow the dehydrated anhydrous hydrogen fluoride to pass into the reaction device or be collected in the product storage tank. The hydrogen fluoride continuously passes through the electrolytic cell body (1) to continuously treat the water in the hydrogen fluoride; 4) using an anode gas chamber (14) to collect gas generated on the anode plate (3), and using a cathode gas chamber (15) to collect gas generated on the cathode plate (4); 5) The gases collected in the anode gas chamber (14) and the cathode gas chamber (15) are condensed and refluxed into hydrogen fluoride, and the non-condensable gases are purified and discharged after meeting the standards.

Images