Method for producing hydrogen fluoride removal agent

Abstract

Provided is a method for producing a hydrogen fluoride removal agent, in which degradation is unlikely to occur and the necessity of replacement is unlikely to occur. The method for producing a hydrogen fluoride removal agent is a method for producing a hydrogen fluoride removal agent that removes hydrogen fluoride from a crude fluorine gas that is fluorine gas containing hydrogen fluoride. The method includes: a molding step for obtaining a molded body by molding a powder raw material containing sodium fluoride and hydrogen fluoride; and a sintering step for sintering the molded body to obtain a hydrogen fluoride removal agent having a volume density of 1.8-2.4 g / mL. The ratio of sodium fluoride and hydrogen fluoride contained in the powder raw material is 0.2-0.7 moles of hydrogen fluoride relative to 1.0 moles of sodium fluoride.

Description

Manufacturing method of hydrogen fluoride remover

[0001] The present disclosure relates to a method for producing a hydrogen fluoride remover.

[0002] When a KF-2HF molten salt electrolyte is electrolyzed, fluorine gas (F2) is generated from the anode. Because the KF-2HF molten salt electrolyte has the vapor pressure of hydrogen fluoride (HF), the fluorine gas generated from the anode is contaminated with hydrogen fluoride at a concentration of 4 to 10% by volume. A known method for removing hydrogen fluoride from crude fluorine gas, which is fluorine gas containing hydrogen fluoride, is to adsorb hydrogen fluoride onto pellets of sodium fluoride (NaF), a hydrogen fluoride remover (see, for example, Patent Document 1).

[0003] In order to continuously perform a process of removing hydrogen fluoride from a crude fluorine gas by supplying the crude fluorine gas to a hydrogen fluoride removal tower filled with a hydrogen fluoride removing agent, it is necessary to use a plurality of hydrogen fluoride removal towers. For example, when two hydrogen fluoride removal towers are used, one hydrogen fluoride removal tower performs a hydrogen fluoride removal process of removing hydrogen fluoride from the crude fluorine gas, while the other hydrogen fluoride removal tower performs a hydrogen fluoride desorption process of desorbing hydrogen fluoride from the hydrogen fluoride removing agent that has adsorbed hydrogen fluoride, thereby regenerating the hydrogen fluoride removing agent. Then, by alternately switching between the hydrogen fluoride removal towers that perform the hydrogen fluoride removal process, the hydrogen fluoride removal process and the hydrogen fluoride desorption process can be performed in parallel in both hydrogen fluoride removal towers, thereby continuously performing a process of removing hydrogen fluoride from a crude fluorine gas.

[0004] Japanese Patent Publication No. 2009-215588

[0005] However, when the hydrogen fluoride removal treatment and the hydrogen fluoride desorption treatment (i.e., regeneration treatment) are alternately and repeatedly performed, there is a problem that the hydrogen fluoride removing agent in the hydrogen fluoride removal tower may crack, become powdery, or fuse together. If the hydrogen fluoride removing agent cracks, becomes powdery, or fuses together, the gas flow path in the hydrogen fluoride removal tower may be clogged or uneven flow may occur, so it has been necessary to replace the hydrogen fluoride removing agent with a new one after one or several regeneration treatments.

[0006] Since the replacement work of the hydrogen fluoride removing agent is complicated, if the replacement work of the hydrogen fluoride removing agent needs to be performed frequently, there is a risk that the process of removing hydrogen fluoride from crude fluorine gas cannot be carried out simply. Furthermore, since sodium fluoride pellets are not inexpensive, if the replacement work of the hydrogen fluoride removing agent needs to be performed frequently, there is a risk that the process of removing hydrogen fluoride from crude fluorine gas will become uneconomical. In this specification, cracking, powdering, or fusion of the hydrogen fluoride removing agent may also be referred to as "deterioration." An object of the present disclosure is to provide a method for producing a hydrogen fluoride removing agent that is less likely to deteriorate and less likely to need replacement.

[0007] In order to solve the above problems, one aspect of the present disclosure is as follows: [1] to [4] [1] A method for producing a hydrogen fluoride removing agent that removes hydrogen fluoride from a crude fluorine gas that is a fluorine gas containing hydrogen fluoride, the method comprising: a molding step of molding a powder raw material containing sodium fluoride and hydrogen fluoride to obtain a molded body; and a sintering step of sintering the molded body to obtain the hydrogen fluoride removing agent having a volume density of 1.8 g / mL or more and 2.4 g / mL or less, wherein the ratio of the sodium fluoride to the hydrogen fluoride contained in the powder raw material is 0.2 mol or more and 0.7 mol or less for every 1.0 mol of the sodium fluoride.

[0008] [2] The method for producing a hydrogen fluoride removing agent according to [1], wherein the ratio of the sodium fluoride to the hydrogen fluoride contained in the powdered raw material is 0.3 mol to 0.5 mol of the hydrogen fluoride per 1.0 mol of the sodium fluoride. [3] The method for producing a hydrogen fluoride removing agent according to [1] or [2], wherein the powdered raw material is a mixture of sodium hydrogen fluoride and sodium fluoride. [4] The method for producing a hydrogen fluoride removing agent according to any one of [1] to [3], wherein the sintering step is a step of sintering the compact at a temperature of 300°C to 800°C.

[0009] According to the present disclosure, it is possible to provide a hydrogen fluoride remover that is less likely to deteriorate and requires less replacement.

[0010] An embodiment of the present disclosure will be described below. Note that this embodiment shows an example of the present disclosure, and the present disclosure is not limited to this embodiment. Furthermore, various modifications or improvements can be made to this embodiment, and such modifications or improvements may also be included in the present disclosure.

[0011] Conventionally, when hydrogen fluoride is removed from crude fluorine gas, which is fluorine gas containing hydrogen fluoride, using a hydrogen fluoride removing agent made of sodium fluoride, if hydrogen fluoride removal treatment and hydrogen fluoride desorption treatment are repeatedly performed alternately, there has been a problem that the hydrogen fluoride removing agent may crack or become powdery, or the hydrogen fluoride removing agents may fuse together, as described above. After extensive investigation, the present inventors have attributed the cause of this deterioration of the hydrogen fluoride removing agent to the following.

[0012] The adsorption of hydrogen fluoride to sodium fluoride is not adsorption onto the surface of a solid, but can be said to be the formation of a composition between sodium fluoride and hydrogen fluoride. For example, after hydrogen fluoride is adsorbed (condensed) onto the surface of a hydrogen fluoride remover, the adsorbed hydrogen fluoride is absorbed and diffused into the interior of the sodium fluoride crystals, resulting in a phenomenon that can be said to be the formation of a composition. Hereinafter, this phenomenon of adsorption and absorption will be referred to as "sorption."

[0013] When the amount of hydrogen fluoride sorbed increases, the rate at which hydrogen fluoride diffuses into the sodium fluoride crystals slows, and the amount of hydrogen fluoride condensing on the surface of the hydrogen fluoride removing agent increases, so the hydrogen fluoride concentration of the sodium fluoride-hydrogen fluoride composition formed on the surface of the hydrogen fluoride removing agent increases and the melting point decreases.This is thought to be why the phenomenon of contacting hydrogen fluoride removing agents fusing together occurs.

[0014] Furthermore, sodium fluoride swells when it sorbs hydrogen fluoride and shrinks when it desorbs hydrogen fluoride. Therefore, it is thought that repeated swelling and shrinkage causes cracking and further progresses to pulverization. Furthermore, the greater the amount of sorbed hydrogen fluoride, the greater the degree of swelling and shrinkage, and therefore the greater the amount of sorbed hydrogen fluoride, the worse the degree of cracking and pulverization.

[0015] As a result of extensive research, the present inventors have discovered a method for producing a hydrogen fluoride remover with a small sorption capacity for hydrogen fluoride (i.e., the maximum amount of hydrogen fluoride that can be sorbed). A small sorption capacity for hydrogen fluoride makes it difficult for contacting hydrogen fluoride removers to fuse together. Furthermore, a small sorption capacity for hydrogen fluoride makes it difficult for the hydrogen fluoride remover, which is made of sodium fluoride, to undergo swelling and shrinkage only slightly, even when hydrogen fluoride removal treatment and hydrogen fluoride desorption treatment are alternately and repeatedly performed. Therefore, even when hydrogen fluoride removal treatment and hydrogen fluoride desorption treatment are alternately and repeatedly performed, deterioration (cracks, powdering) of the hydrogen fluoride remover is unlikely to occur. Because deterioration of the hydrogen fluoride remover is unlikely to occur, the hydrogen fluoride removal treatment and hydrogen fluoride desorption treatment can be alternately and repeatedly performed on the hydrogen fluoride remover multiple times (e.g., 40 times or more, 200 times or more).

[0016] In this specification, the sorbable amount of hydrogen fluoride is sometimes referred to as the "maximum hydrogen fluoride sorption amount." This maximum hydrogen fluoride sorption amount can be calculated by the following formula using the mass of the hydrogen fluoride removing agent that has sorbed hydrogen fluoride up to the maximum sorbable amount and the mass of hydrogen fluoride sorbed by the hydrogen fluoride removing agent at that time: Maximum hydrogen fluoride sorption amount (mass %) = (mass of hydrogen fluoride) / (mass of hydrogen fluoride removing agent that has sorbed hydrogen fluoride) × 100

[0017] Conventionally, the maximum hydrogen fluoride sorption capacity of a typical hydrogen fluoride remover made of sodium fluoride is 32% by mass. Therefore, although a large amount of hydrogen fluoride can be sorbed, when hydrogen fluoride removal treatment and hydrogen fluoride desorption treatment are repeatedly performed alternately, the degree of swelling and shrinkage that occurs in the hydrogen fluoride remover is large. Therefore, it is difficult to repeatedly perform the hydrogen fluoride removal treatment and hydrogen fluoride desorption treatment alternately multiple times on the hydrogen fluoride remover, and deterioration may occur even after performing only one hydrogen fluoride removal treatment and one hydrogen fluoride desorption treatment. Therefore, frequent replacement of the hydrogen fluoride remover is required.

[0018] The hydrogen fluoride remover produced by the method for producing a hydrogen fluoride remover according to this embodiment (hereinafter, sometimes referred to as the "hydrogen fluoride remover according to this embodiment") is a sintered body containing sodium fluoride, and its volume density is 1.8 g / mL or more and 2.4 g / mL or less.

[0019] By using the hydrogen fluoride removing agent according to this embodiment, it is possible to remove hydrogen fluoride from crude fluorine gas, which is fluorine gas containing hydrogen fluoride, to purify the crude fluorine gas and produce purified fluorine gas with a reduced hydrogen fluoride concentration. The hydrogen fluoride removing agent according to this embodiment has a lower maximum hydrogen fluoride sorption amount, for example, 16 mass %, than conventional hydrogen fluoride removing agents made of sodium fluoride. Because the amount of hydrogen fluoride that can be sorbed is small, the phenomenon of fusion between hydrogen fluoride removing agents that come into contact with each other is unlikely to occur.

[0020] Furthermore, although it is difficult to sorb large amounts of hydrogen fluoride compared to conventional hydrogen fluoride removers made of sodium fluoride, the degree of swelling and shrinkage that occurs in the hydrogen fluoride remover is small when hydrogen fluoride removal treatment and hydrogen fluoride desorption treatment are alternately repeated. Therefore, as described above, the hydrogen fluoride remover is less likely to deteriorate, and the hydrogen fluoride removal treatment and hydrogen fluoride desorption treatment can be alternately repeated multiple times (e.g., 40 times or more, 200 times or more). Therefore, the need to replace the hydrogen fluoride remover is less likely to occur. The maximum hydrogen fluoride sorption amount of the hydrogen fluoride remover according to this embodiment is preferably 10% by mass or more and 26% by mass or less. The shape of the hydrogen fluoride remover according to this embodiment is not particularly limited, and can be, for example, cylindrical, spherical, oval-spherical, or plate-shaped.

[0021] The hydrogen fluoride remover according to the present embodiment can be used to remove hydrogen fluoride from a crude fluorine gas, which is a fluorine gas containing hydrogen fluoride, but can also be used to remove hydrogen fluoride from a crude gas, which is another type of gas containing hydrogen fluoride. Examples of other gases include fluorine-containing compound gases, and specific examples include chlorine monofluoride (ClF), chlorine trifluoride (ClF), chlorine pentafluoride (ClF), bromine trifluoride (BrF), bromine pentafluoride (BrF), bromine heptafluoride (BrF), iodine trifluoride (IF), iodine pentafluoride (IF), iodine heptafluoride (IF), uranium hexafluoride (UF), tungsten hexafluoride (WF), molybdenum hexafluoride (MoF), xenon hexafluoride (XeF), silicon tetrafluoride (SiF), nitrogen trifluoride (NF), and sulfur tetrafluoride (SF).

[0022] The hydrogen fluoride removing agent according to this embodiment can be produced as follows: That is, the production method for the hydrogen fluoride removing agent according to this embodiment is a method for producing a hydrogen fluoride removing agent that removes hydrogen fluoride from a crude fluorine gas that is a fluorine gas containing hydrogen fluoride, and includes a molding step of molding a powder raw material containing sodium fluoride and hydrogen fluoride to obtain a molded body, and a sintering step of sintering the molded body to obtain a hydrogen fluoride removing agent having a volume density of 1.8 g / mL or more and 2.4 g / mL or less, wherein the ratio of sodium fluoride to hydrogen fluoride contained in the powder raw material is 0.2 mol or more and 0.7 mol or less for every 1.0 mol of sodium fluoride.

[0023] In the method for producing a hydrogen fluoride remover according to this embodiment, a molded body is sintered in a sintering step to obtain a sintered body containing sodium fluoride (i.e., a hydrogen fluoride remover). However, since a powdered raw material containing sodium fluoride and hydrogen fluoride is used, hydrogen fluoride volatilizes from the molded body in the sintering step, forming voids in the sintered body (hydrogen fluoride remover).

[0024] For example, when a powder raw material containing a mixture of sodium fluoride and sodium hydrogen fluoride (NaF.HF) is used, hydrogen fluoride volatilizes from the sodium hydrogen fluoride during the sintering process, forming voids in the hydrogen fluoride remover. Because voids are formed in the hydrogen fluoride remover, hydrogen fluoride is easily sorbed, and the hydrogen fluoride remover according to this embodiment has a sufficiently large maximum hydrogen fluoride sorption amount.

[0025] On the other hand, since the ratio of sodium fluoride to hydrogen fluoride contained in the powder raw material is controlled to 0.2 moles or more and 0.7 moles or less of hydrogen fluoride per 1.0 mole of sodium fluoride, fewer voids are formed in the hydrogen fluoride remover and the porosity is suppressed compared to when the ratio is 1.0 mole of hydrogen fluoride per 1.0 mole of sodium fluoride (for example, when only sodium hydrogen fluoride is used as the powder raw material).

[0026] As a result, the maximum hydrogen fluoride sorption amount of the hydrogen fluoride remover is suppressed to, for example, 16 mass %, and therefore, as described above, the hydrogen fluoride remover produced by the method for producing a hydrogen fluoride remover according to this embodiment is less likely to deteriorate. Therefore, it is possible to alternately repeat the hydrogen fluoride removal treatment and the hydrogen fluoride desorption treatment, for example, 200 times or more.

[0027] The porosity of the hydrogen fluoride remover may be 14% or more and 36% or less. Furthermore, the ratio of sodium fluoride to hydrogen fluoride contained in the powder raw material is preferably 1.0 mole of sodium fluoride to 0.3 moles or more and 0.5 moles or less of hydrogen fluoride. This allows the production of a hydrogen fluoride remover that is less susceptible to deterioration.

[0028] Furthermore, the powder raw material can be a mixture of sodium hydrogen fluoride and sodium fluoride. The ratio of sodium fluoride to hydrogen fluoride contained in the powder raw material can be controlled by adjusting the mixing ratio of sodium hydrogen fluoride and sodium fluoride. Furthermore, the molding step is a step of molding the powder raw material to obtain a molded body, and in order to optimize the maximum hydrogen fluoride sorption amount of the hydrogen fluoride removal agent, it is preferable to mold the molded body so that the volume density is 2.3 g / mL or more and 2.6 g / mL or less.

[0029] The volume density of the hydrogen fluoride removal agent and the molded body is the value obtained by dividing the mass by the geometric volume. The method for measuring the geometric volume of the hydrogen fluoride removal agent and the molded body is not particularly limited. Taking the example of a cylindrical hydrogen fluoride removal agent and the molded body, the diameter and length can be measured using a caliper or the like, and the geometric volume can be calculated from the measurements. The diameter of the cylindrical hydrogen fluoride removal agent and the molded body may be, for example, the average value of the diameters measured at three positions: the upper, middle, and lower sections.

[0030] Furthermore, the sintering step may be a step of sintering the molded body at a temperature of 300° C. or higher and 800° C. or lower. That is, the sintering temperature at which the molded body is sintered is not particularly limited, but in order to obtain a favorable strength and maximum hydrogen fluoride sorption amount of the hydrogen fluoride removal agent, the sintering temperature is preferably 300° C. or higher and 800° C. or lower, more preferably the lower limit of the sintering temperature is 400° C. or higher, and more preferably the upper limit of the sintering temperature is 600° C. or lower.

[0031] The atmosphere during sintering is not particularly limited, and may be, for example, at least one gas selected from air, nitrogen gas (N), helium (He), and argon (Ar). The volume density of the hydrogen fluoride remover obtained through the sintering step is 1.8 g / mL or more and 2.4 g / mL or less, but in order to obtain a more suitable maximum hydrogen fluoride sorption amount, the lower limit is preferably 1.9 g / mL or more and the upper limit is preferably 2.2 g / mL or less.

[0032] The length of time (sintering time) for sintering the compact in the sintering step is not particularly limited, but is preferably 2 hours or more, more preferably 4 hours or more. The degree of progress of sintering varies depending on the sintering temperature and sintering time, and the volume density that is achieved is determined by the sintering temperature. Therefore, the sintering temperature and sintering time may be adjusted so as to obtain a sintered body that exhibits the desired volume density.

[0033] Next, a method for removing hydrogen fluoride from crude fluorine gas using the hydrogen fluoride removing agent according to this embodiment will be described. When hydrogen fluoride is removed from crude fluorine gas by sorbing it onto the hydrogen fluoride removing agent according to this embodiment, there are no particular restrictions on the concentration of hydrogen fluoride in the crude fluorine gas. The concentration of hydrogen fluoride in the crude fluorine gas may be, for example, several thousand ppm by volume or several % by volume. Specific examples include 2% by volume or more and 10% by volume or less, and 20% by volume or more and 30% by volume or less. When the concentration of hydrogen fluoride in the crude fluorine gas is 20% by volume or more, the concentration of hydrogen fluoride in the crude fluorine gas may be reduced by a condensation operation or the like, and then hydrogen fluoride may be sorbed using the hydrogen fluoride removing agent according to this embodiment.

[0034] When crude fluorine gas is brought into contact with the hydrogen fluoride removing agent according to the present embodiment to sorb hydrogen fluoride, the linear velocity of the flowing crude fluorine gas is not particularly limited, but in order to prevent a large pressure loss and an increase in the amount of unsorbed hydrogen fluoride, a linear velocity of 0.1 m / sec or less is preferred.

[0035] The temperature at which crude fluorine gas is brought into contact with the hydrogen fluoride removing agent according to this embodiment to sorb hydrogen fluoride is not particularly limited, but is preferably 50° C. or higher and 150° C. or lower, and more preferably 60° C. or higher and 100° C. or lower. If the temperature is 50° C. or higher, fusion of the hydrogen fluoride removing agent is unlikely to occur. Furthermore, if the temperature is 150° C. or lower, desorption of hydrogen fluoride from the hydrogen fluoride removing agent is unlikely to occur.

[0036] The method for desorbing sorbed hydrogen fluoride from the hydrogen fluoride remover is not particularly limited, but a method in which the hydrogen fluoride remover is heated while passing an inert gas through it is preferred. In order to economically perform sufficient desorption, the heating temperature is preferably 150°C or higher and 300°C or lower, more preferably 190°C or higher and 250°C or lower, and even more preferably 200°C or higher and 230°C or lower. The type of inert gas is not particularly limited as long as it does not react with sodium fluoride, but air, nitrogen gas, helium, argon, etc. can be used.

[0037] The present disclosure will be described in more detail below with reference to examples and comparative examples. (Example 1) 200 g of sodium hydrogen fluoride manufactured by Morita Chemical Industry Co., Ltd. and 200 g of sodium fluoride with a purity of 99.0% manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. were mixed together to produce a mixed powder, which was then pulverized using a powder mill (dry pulverizer) to obtain a powder raw material. The ratio of sodium fluoride to hydrogen fluoride contained in this powder raw material was 1.0 mol of sodium fluoride to 0.40 mol of hydrogen fluoride.

[0038] This powder raw material was filled into a cylindrical mold with an inner diameter of 3 mm, and pressed at 150 N / mm using a tablet press. 2 The powder raw material was compressed at a pressure of 1000 kJ / cm2 to obtain a compact of the powder raw material. The obtained compact was cylindrical in shape and 3 mm in length. The volume density of this compact was measured and found to be 2.47 g / mL. A large number of compacts were produced by this tableting method, and a total of 200 g of compacts of the powder raw material was obtained.

[0039] 35 mL of the powder raw material compact obtained as described above was packed into a nickel tube with an inner diameter of 1 inch, and while nitrogen gas was circulated through the nickel tube at a gas flow rate of 200 mL / min based on standard conditions, the outside of the nickel tube was heated to 500°C with an electric heater. The powder raw material compact was sintered by heating at 500°C for 2 hours, and then cooled to room temperature to obtain a sintered body of sodium fluoride (i.e., a hydrogen fluoride remover).

[0040] The cooled hydrogen fluoride removing agent was removed from the nickel tube, and it was confirmed that the hydrogen fluoride removing agent was not cracked or pulverized. The volume density of the hydrogen fluoride removing agent was measured and found to be 2.11 g / mL. The hydrogen fluoride removing agent obtained as described above was cylindrical, with a diameter of 3 mm and a length of 3 mm.

[0041] Next, the maximum hydrogen fluoride sorption capacity of the hydrogen fluoride remover was determined. The maximum hydrogen fluoride sorption capacity is the maximum amount of hydrogen fluoride that can be sorbed. The hydrogen fluoride remover that had been removed to confirm the absence of cracking or powdering was refilled into the nickel tube, and the total mass of the nickel tube filled with the hydrogen fluoride remover was measured. The nickel tube was then heated to 80°C, and nitrogen gas and hydrogen fluoride gas were passed through it to perform a sorption treatment in which hydrogen fluoride was sorbed into the hydrogen fluoride remover. The flow rate of nitrogen gas was 180 mL / min under standard conditions, and the flow rate of hydrogen fluoride gas was 20 mL / min under standard conditions. The outlet gas emerging from the outlet of the nickel tube was then analyzed using a Fourier transform infrared spectrophotometer (FT-IR), and the hydrogen fluoride concentration in the outlet gas was measured.

[0042] When the hydrogen fluoride concentration in the outlet gas reached 10% by volume (i.e., when the hydrogen fluoride removal agent no longer sorbed hydrogen fluoride), the flow of nitrogen gas and hydrogen fluoride gas was stopped, the nickel tube was cooled, and the total mass of the nickel tube filled with the hydrogen fluoride removal agent was measured. By comparing the total mass before and after the flow of hydrogen fluoride gas, the mass of hydrogen fluoride sorbed by the hydrogen fluoride removal agent was determined, and from this value, the maximum hydrogen fluoride sorption capacity of the hydrogen fluoride removal agent was calculated. As a result, the maximum hydrogen fluoride sorption capacity of the hydrogen fluoride removal agent was 16.1% by mass.

[0043] Next, this nickel tube was heated to 200°C, and nitrogen gas was passed through to perform a hydrogen fluoride desorption treatment (i.e., regeneration treatment). The flow rate of nitrogen gas was 360 mL / min under standard conditions. The outlet gas coming out of the outlet of the nickel tube was analyzed using a Fourier transform infrared spectrophotometer to measure the hydrogen fluoride concentration in the outlet gas. The hydrogen fluoride desorption treatment was continued until the hydrogen fluoride concentration in the outlet gas reached 50 ppm by volume. When the hydrogen fluoride concentration in the outlet gas reached 50 ppm by volume, the flow of nitrogen gas was stopped. The nickel tube was then heated to 80°C, and the same sorption treatment as above was performed, followed by the same desorption treatment as above.

[0044] This cycle of sorption and desorption was repeated a total of 40 times. The hydrogen fluoride remover was removed from the nickel tube and checked for cracking and pulverization. 2.5% of the hydrogen fluoride remover was found to be cracked and pulverized. 4% of the hydrogen fluoride remover was fused together, forming multiple clumps. The remaining 93.5% of the hydrogen fluoride remover showed no cracks, deformation, or other abnormalities. The results of Example 1 are summarized in Table 1.

[0045]

[0046] Example 2 200 g of a molded body of the powder raw material was obtained in the same manner as in Example 1, except that a mixed powder of 280 g of sodium hydrogen fluoride and 120 g of sodium fluoride was used. In the case of Example 2, the ratio of sodium fluoride to hydrogen fluoride contained in the powder raw material was 1.0 mol of sodium fluoride to 0.61 mol of hydrogen fluoride. The volume density of this molded body was measured and found to be 2.37 g / mL. Then, the molded body of the powder raw material was sintered in the same manner as in Example 1 to obtain a hydrogen fluoride remover consisting of a sintered body of sodium fluoride.

[0047] The cooled hydrogen fluoride removing agent was removed from the nickel tube, and it was confirmed that the hydrogen fluoride removing agent was not cracked or pulverized. The volume density of the hydrogen fluoride removing agent was measured and found to be 1.88 g / mL. The hydrogen fluoride removing agent obtained as described above was cylindrical, with a diameter of 3 mm and a length of 3 mm.

[0048] Next, a sorption treatment was carried out in which hydrogen fluoride was sorbed into the hydrogen fluoride removing agent in the same manner as in Example 1. As a result, the maximum hydrogen fluoride sorption amount of the hydrogen fluoride removing agent was 22.6 mass%. Next, a hydrogen fluoride desorption treatment was carried out in the same manner as in Example 1, except that the temperature was 210°C. Then, as in Example 1, a cycle of the sorption treatment and the desorption treatment was repeated a total of 40 times.

[0049] The hydrogen fluoride removers were removed from the nickel tube and checked for cracking and powdering. 6% of the hydrogen fluoride removers were found to be cracked and powdered. 12% of the hydrogen fluoride removers were fused together, forming clumps of multiple pieces. The remaining 82% of the hydrogen fluoride removers showed no cracks, deformation, or other abnormalities. The results of Example 2 are summarized in Table 1.

[0050] Example 3 200 g of a molded body of the powder raw material was obtained in the same manner as in Example 1, except that a mixed powder of 120 g of sodium hydrogen fluoride and 280 g of sodium fluoride was used. In the case of Example 3, the ratio of sodium fluoride to hydrogen fluoride contained in the powder raw material was 1.0 mol of sodium fluoride to 0.23 mol of hydrogen fluoride. The volume density of this molded body was measured and found to be 2.59 g / mL. Then, the molded body of the powder raw material was sintered in the same manner as in Example 1 to obtain a hydrogen fluoride remover consisting of a sintered body of sodium fluoride.

[0051] The cooled hydrogen fluoride removing agent was removed from the nickel tube, and it was confirmed that the hydrogen fluoride removing agent was not cracked or pulverized. The volume density of the hydrogen fluoride removing agent was measured and found to be 2.37 g / mL. The hydrogen fluoride removing agent obtained as described above was cylindrical in shape, with a diameter of 3 mm and a length of 3 mm.

[0052] Next, a sorption treatment was carried out in which hydrogen fluoride was sorbed into the hydrogen fluoride removing agent in the same manner as in Example 1. As a result, the maximum hydrogen fluoride sorption amount of the hydrogen fluoride removing agent was 9.7 mass%. Next, a hydrogen fluoride desorption treatment was carried out in the same manner as in Example 1, except that the temperature was 210°C. Then, as in Example 1, a cycle of the sorption treatment and the desorption treatment was repeated a total of 40 times.

[0053] The hydrogen fluoride removers were removed from the nickel tube and checked for cracking and powdering. 0.5% of the hydrogen fluoride removers were found to be cracked and powdered. 1.5% of the hydrogen fluoride removers were fused together, forming clumps of multiple pieces. The remaining 98% of the hydrogen fluoride removers showed no cracks, deformation, or other abnormalities. The results of Example 3 are summarized in Table 1.

[0054] Example 4 200 g of a molded body of the powder raw material was obtained in the same manner as in Example 1, except that a mixed powder of 160 g of sodium hydrogen fluoride and 240 g of sodium fluoride was used. In the case of Example 4, the ratio of sodium fluoride to hydrogen fluoride contained in the powder raw material was 1.0 mol of sodium fluoride to 0.31 mol of hydrogen fluoride. The volume density of this molded body was measured and found to be 2.53 g / mL. Then, the molded body of the powder raw material was sintered in the same manner as in Example 1 to obtain a hydrogen fluoride remover consisting of a sintered body of sodium fluoride.

[0055] The cooled hydrogen fluoride removing agent was removed from the nickel tube, and it was confirmed that the hydrogen fluoride removing agent was not cracked or pulverized. The volume density of the hydrogen fluoride removing agent was measured and found to be 2.24 g / mL. The hydrogen fluoride removing agent obtained as described above was cylindrical in shape, with a diameter of 3 mm and a length of 3 mm.

[0056] Next, a sorption treatment was carried out in which hydrogen fluoride was sorbed into the hydrogen fluoride removing agent in the same manner as in Example 1. As a result, the maximum hydrogen fluoride sorption amount of the hydrogen fluoride removing agent was 12.9 mass%. Next, a hydrogen fluoride desorption treatment was carried out in the same manner as in Example 1, except that the temperature was 210°C. Then, as in Example 1, a cycle of the sorption treatment and the desorption treatment was repeated a total of 40 times.

[0057] The hydrogen fluoride removers were removed from the nickel tube and checked for cracks and powdering. 2% of the hydrogen fluoride removers were found to be cracked and powdered. Also, 2% of the hydrogen fluoride removers were fused together, forming clumps of multiple pieces. The remaining 96% of the hydrogen fluoride removers showed no cracks, deformation, or other abnormalities. The results of Example 4 are summarized in Table 1.

[0058] Comparative Example 1: 200 g of a molded body of the powder raw material was obtained in the same manner as in Example 1, except that 400 g of sodium hydrogen fluoride was used instead of the mixed powder. In the case of Comparative Example 1, the ratio of sodium fluoride to hydrogen fluoride contained in the powder raw material was 1.0 mol of sodium fluoride to 1.0 mol of hydrogen fluoride. The volume density of this molded body was measured and found to be 2.23 g / mL. Then, the molded body of the powder raw material was sintered in the same manner as in Example 1 to obtain a hydrogen fluoride remover consisting of a sintered body of sodium fluoride.

[0059] The cooled hydrogen fluoride removing agent was removed from the nickel tube, and it was confirmed that the hydrogen fluoride removing agent was not cracked or pulverized. The volume density of the hydrogen fluoride removing agent was measured and found to be 1.55 g / mL. The hydrogen fluoride removing agent obtained as described above was cylindrical, with a diameter of 3 mm and a length of 3 mm.

[0060] Next, a sorption treatment was carried out in which hydrogen fluoride was sorbed into the hydrogen fluoride removing agent in the same manner as in Example 1. As a result, the maximum hydrogen fluoride sorption amount of the hydrogen fluoride removing agent was 32.3 mass%. Next, a hydrogen fluoride desorption treatment was carried out in the same manner as in Example 1, except that the temperature was 210°C. Then, as in Example 1, a cycle of the sorption treatment and the desorption treatment was repeated a total of seven times.

[0061] The hydrogen fluoride removers were removed from the nickel tube and checked for cracks and powdering. 25% of the hydrogen fluoride removers were found to be cracked and powdered. 27% of the hydrogen fluoride removers were fused together, forming clumps of multiple pieces. The remaining 48% of the hydrogen fluoride removers were not cracked but were deformed. The results of Comparative Example 1 are summarized in Table 1.

[0062] (Comparative Example 2) 200 g of a molded body of the powder raw material was obtained in the same manner as in Example 1, except that a mixed powder of 80 g of sodium hydrogen fluoride and 320 g of sodium fluoride was used. In the case of Comparative Example 2, the ratio of sodium fluoride to hydrogen fluoride contained in the powder raw material was 1.0 mol of sodium fluoride to 0.14 mol of hydrogen fluoride. The volume density of this molded body was measured and found to be 2.66 g / mL. Then, the molded body of the powder raw material was sintered in the same manner as in Example 1 to obtain a hydrogen fluoride remover consisting of a sintered body of sodium fluoride.

[0063] The cooled hydrogen fluoride removing agent was removed from the nickel tube, and it was confirmed that the hydrogen fluoride removing agent was not cracked or pulverized. The volume density of the hydrogen fluoride removing agent was measured and found to be 2.51 g / mL. The hydrogen fluoride removing agent obtained as described above was cylindrical in shape, with a diameter of 3 mm and a length of 3 mm.

[0064] Next, a sorption treatment was carried out in which hydrogen fluoride was sorbed into the hydrogen fluoride removal agent in the same manner as in Example 1. As a result, the maximum hydrogen fluoride sorption amount of the hydrogen fluoride removal agent was 6.5 mass%. Next, a hydrogen fluoride desorption treatment was carried out in the same manner as in Example 1, except that the temperature was 210°C. Then, as in Example 1, a cycle of the sorption treatment and the desorption treatment was repeated a total of 40 times.

[0065] The hydrogen fluoride remover was removed from the nickel tube and checked for cracks or powdering. No cracks or powdering were found. However, 0.2% of the hydrogen fluoride remover was fused together, forming clumps of multiple pieces. The remaining 98.8% of the hydrogen fluoride remover showed no cracks, deformation, or other defects. However, the maximum hydrogen fluoride sorption capacity was low, and the hydrogen fluoride adsorption performance was insufficient. The results of Comparative Example 2 are summarized in Table 1.

[0066] (Comparative Example 3) 200 g of a molded body of the powder raw material was obtained in the same manner as in Example 1, except that a mixed powder of 320 g of sodium hydrogen fluoride and 80 g of sodium fluoride was used. In the case of Comparative Example 3, the ratio of sodium fluoride to hydrogen fluoride contained in the powder raw material was 1.0 mol of sodium fluoride to 0.73 mol of hydrogen fluoride. The volume density of this molded body was measured and found to be 2.32 g / mL. Then, the molded body of the powder raw material was sintered in the same manner as in Example 1 to obtain a hydrogen fluoride remover consisting of a sintered body of sodium fluoride.

[0067] The cooled hydrogen fluoride removing agent was removed from the nickel tube, and it was confirmed that the hydrogen fluoride removing agent was not cracked or pulverized. The volume density of the hydrogen fluoride removing agent was measured and found to be 1.76 g / mL. The hydrogen fluoride removing agent obtained as described above was cylindrical, with a diameter of 3 mm and a length of 3 mm.

[0068] Next, a sorption treatment was carried out in which hydrogen fluoride was sorbed into the hydrogen fluoride removing agent in the same manner as in Example 1. As a result, the maximum hydrogen fluoride sorption amount of the hydrogen fluoride removing agent was 25.8 mass%. Next, a hydrogen fluoride desorption treatment was carried out in the same manner as in Example 1, except that the temperature was 210°C. Then, as in Example 1, a cycle of the sorption treatment and the desorption treatment was repeated a total of seven times.

[0069] The hydrogen fluoride removers were removed from the nickel tube and checked for cracks and powdering. 12% of the hydrogen fluoride removers were found to be cracked and powdered. 15% of the hydrogen fluoride removers were fused together, forming clumps of multiple pieces. The remaining 67% of the hydrogen fluoride removers were not cracked but were deformed. The results of Comparative Example 3 are summarized in Table 1.

Claims

1. A method for producing a hydrogen fluoride remover that removes hydrogen fluoride from crude fluorine gas, which is fluorine gas containing hydrogen fluoride, comprising: a molding step of molding a powder raw material containing sodium fluoride and hydrogen fluoride to obtain a molded body; and a sintering step of sintering the molded body to obtain the hydrogen fluoride remover having a volume density of 1.8 g / mL or more and 2.4 g / mL or less, wherein the ratio of the sodium fluoride to the hydrogen fluoride contained in the powder raw material is 0.2 moles or more and 0.7 moles or less of the hydrogen fluoride to 1.0 mole of the sodium fluoride.

2. A method for producing a hydrogen fluoride remover according to claim 1, wherein the ratio of the sodium fluoride to the hydrogen fluoride contained in the powder raw material is 0.3 moles or more and 0.5 moles or less of the hydrogen fluoride to 1.0 mole of the sodium fluoride.

3. A method for producing a hydrogen fluoride remover according to claim 1 or 2, wherein the powder raw material is a mixture of sodium hydrogen fluoride and sodium fluoride.

4. A method for producing a hydrogen fluoride remover according to claim 1 or claim 2, wherein the sintering step is a step of sintering the molded body at a temperature of 300°C or higher and 800°C or lower.

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