Method for producing iodine heptafluoride

Abstract

Provided is a method for producing iodine heptafluoride with which it is possible to produce iodine heptafluoride having a low iodine gas content at a high yield. This method for producing iodine heptafluoride comprises: a preparation step for preparing a liquid mixture containing iodine pentafluoride and hydrogen fluoride, the hydrogen fluoride content being 0.1-20 mass% of the iodine pentafluoride content; a gasification step in which fluorine gas is mixed into the liquid mixture and the liquid mixture is gasified to obtain a raw material mixed gas containing iodine pentafluoride gas, hydrogen fluoride gas, and fluorine gas; and a reaction step in which the raw material mixed gas is reacted in the presence of a catalyst to produce iodine heptafluoride.

Description

Technical Field

[0001] The present invention relates to a method for preparing iodine heptafluoride. Background Art

[0002] In the semiconductor manufacturing process, a silicon nitride film is sometimes etched by dry etching using an etching gas. Iodine heptafluoride (IF7) is known as an etching gas having a relatively low global warming potential and high reactivity with silicon.

[0003] Iodine heptafluoride is generally produced by reacting iodine gas (I2) or iodine pentafluoride (IF5) with fluorine gas (F2). For example, Patent Document 1 discloses a method for obtaining iodine heptafluoride by reacting iodine gas with fluorine gas. In addition, Patent Document 2 discloses a method for obtaining iodine heptafluoride by reacting iodine pentafluoride gas with fluorine gas.

[0004] Prior art literature

[0005] Patent Document 1: Japanese Patent Gazette No. 6372340

[0006] Patent Document 2: Japanese Patent Gazette No. 6252214 Summary of the invention

[0007] However, in the method for producing iodine heptafluoride disclosed in Patent Document 1, iodine gas as a raw material may be mixed into iodine heptafluoride as an impurity. If iodine gas is mixed into the etching gas, the etching rate and etching selectivity of the silicon nitride film may be reduced, so it is not appropriate to use iodine gas as a raw material for producing iodine heptafluoride.

[0008] In addition, in the method for producing iodine heptafluoride disclosed in Patent Document 2, nickel (II) fluoride (NiF2), cobalt (II) fluoride (CoF2) or iron (III) fluoride (FeF3) is used as a catalyst, but if a catalyst other than these is used, the yield of iodine heptafluoride is sometimes low.

[0009] An object of the present invention is to provide a method for producing iodine heptafluoride, which can produce iodine heptafluoride with a low iodine gas content at a high yield.

[0010] In order to solve the above-mentioned problems, one aspect of the present invention is as described in the following [1] to [9].

[0011] [1] A method for producing iodine heptafluoride, comprising a preparation step, a gasification step and a reaction step.

[0012] In the preparation step, a liquid mixture is prepared, the liquid mixture contains iodine pentafluoride and hydrogen fluoride, and the content of the hydrogen fluoride is 0.1% by mass or more and 20% by mass or less of the content of the iodine pentafluoride,

[0013] In the gasification step, fluorine gas is mixed into the liquid mixture to gasify the liquid mixture, thereby obtaining a raw material mixed gas containing iodine pentafluoride gas, hydrogen fluoride gas and fluorine gas.

[0014] In the reaction step, the raw material mixed gas is reacted in the presence of a catalyst to generate iodine heptafluoride.

[0015] [2] The method for producing iodine heptafluoride according to [1], wherein the preparation step is a step of mixing hydrogen fluoride and liquid iodine pentafluoride to obtain the liquid mixture.

[0016] [3] The method for producing iodine heptafluoride according to [1] or [2], wherein the gasification step is a step of gasifying the liquid mixture by blowing fluorine gas into the liquid mixture to obtain the raw material mixed gas.

[0017] [4] According to the method for producing iodine heptafluoride described in [1] or [2], the gasification step is a step of gasifying the liquid mixture by blowing fluorine gas and a diluent gas into the liquid mixture to obtain a raw material mixed gas containing iodine pentafluoride gas, hydrogen fluoride gas, fluorine gas and the diluent gas, and the diluent gas is at least one of nitrogen, argon and helium.

[0018] [5] The method for producing iodine heptafluoride according to any one of [1] to [4], wherein the catalyst contains at least one metal belonging to the third period element or the fourth period element of the periodic table and belonging to any one of the group 3 elements to the group 13 elements.

[0019] [6] The method for producing iodine heptafluoride according to any one of [1] to [5], wherein the vaporization step is a step of vaporizing the liquid mixture by mixing fluorine gas with the liquid mixture at a temperature of 10° C. to 80° C.

[0020] [7] According to the method for producing iodine heptafluoride according to any one of [1] to [6], the ratio [F2] / [IF5] of the molar amount of the fluorine gas [F2] in the raw material mixed gas generated in the gasification step to the molar amount of the iodine pentafluoride [IF5] is greater than 1.0 and less than 30.

[0021] [8] The method for producing iodine heptafluoride according to any one of [1] to [7], wherein the reaction temperature in the reaction step is 150° C. or higher and 380° C. or lower.

[0022] [9] The method for producing iodine heptafluoride according to any one of [1] to [8], wherein the reaction time in the reaction step is 10 seconds to 100 seconds.

[0023] According to the present invention, iodine heptafluoride having a low iodine gas content can be produced with a high yield. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a schematic diagram of an iodine heptafluoride production apparatus for explaining a method for producing iodine heptafluoride according to one embodiment of the present invention. DETAILED DESCRIPTION

[0025] An embodiment of the present invention is described. Furthermore, this embodiment shows an example of the present invention, and the present invention is not limited to this embodiment. In addition, various changes or improvements can be applied to this embodiment, and such a changed or improved method is also included in the present invention. For example, the materials, dimensions, etc. illustrated in this embodiment are examples, and the present invention is not limited thereto, and can be implemented by appropriately changing within the scope of exerting the effect of the present invention.

[0026] The method for producing iodine heptafluoride of the present embodiment comprises a preparation step, a gasification step and a reaction step. The preparation step is a step of preparing a liquid mixture containing iodine pentafluoride and hydrogen fluoride. In the liquid mixture, the content of hydrogen fluoride is greater than 0.1% by mass and less than 20% by mass of the content of iodine pentafluoride.

[0027] The gasification step is a step of mixing fluorine gas with the liquid mixture to gasify the liquid mixture to obtain a raw material mixed gas containing iodine pentafluoride gas, hydrogen fluoride gas and fluorine gas.

[0028] The reaction step is a step of reacting the raw material mixed gas in the presence of a catalyst to generate iodine heptafluoride.

[0029] According to the method for producing iodine heptafluoride of this embodiment, since the raw material does not contain iodine gas, iodine heptafluoride with a low iodine gas content can be produced. Therefore, the iodine heptafluoride produced by the method for producing iodine heptafluoride of this embodiment is suitable as an etching gas for dry etching of a silicon nitride film, for example, and can be used in a semiconductor manufacturing process.

[0030] In addition, according to the method for producing iodine heptafluoride of this embodiment, iodine heptafluoride can be produced in high yield even when using nickel (II) fluoride, cobalt (II) fluoride or iron (III) fluoride as a catalyst, as well as when using catalysts other than these.

[0031] Hereinafter, the method for producing iodine heptafluoride according to the present embodiment will be described in more detail.

[0032] [1] Reaction to generate iodine heptafluoride

[0033] In the method for producing iodine heptafluoride of the present embodiment, iodine pentafluoride and fluorine gas as raw material compounds react as shown in the following chemical reaction formula (1) to produce iodine heptafluoride as a target product.

[0034] IF5 + F2 → IF7 (1)

[0035] [2] Preparation process

[0036] The preparation step in the method for producing iodine heptafluoride of the present embodiment is a step of preparing a liquid mixture, wherein the liquid mixture contains iodine pentafluoride and hydrogen fluoride, and the content of hydrogen fluoride is 0.1% by mass or more and 20% by mass or less of the content of iodine pentafluoride. The method for preparing the liquid mixture is not particularly limited, for example, hydrogen fluoride and liquid iodine pentafluoride may be mixed to obtain a liquid mixture, or liquid iodine pentafluoride containing hydrogen fluoride as an impurity may be used as a liquid mixture.

[0037] The method of mixing hydrogen fluoride and liquid iodine pentafluoride to obtain a liquid mixture is not particularly limited, and examples thereof include a method of blowing hydrogen fluoride gas into liquid iodine pentafluoride contained in a container (eg, a vaporizer).

[0038] Furthermore, as long as the ratio of the content of iodine pentafluoride and hydrogen fluoride satisfies the above conditions, the liquid mixture may be a mixture consisting of only two components of iodine pentafluoride and hydrogen fluoride, or may be a mixture consisting of three or more components containing other components besides iodine pentafluoride and hydrogen fluoride. As other components besides iodine pentafluoride and hydrogen fluoride, for example, diluent gas and fluorine gas described in detail later can be cited.

[0039] [3] Ratio of iodine pentafluoride to hydrogen fluoride

[0040] The liquid mixture contains iodine pentafluoride and hydrogen fluoride, and the content of hydrogen fluoride needs to be 0.1 mass % or more and 20 mass % or less of the content of iodine pentafluoride, preferably 0.5 mass % or more and 15 mass % or less, and more preferably 1 mass % or more and 10 mass % or less.

[0041] If the ratio of the content of iodine pentafluoride to hydrogen fluoride is within the above numerical range, the activity of the catalyst used in the reaction process becomes high, so the reaction of generating iodine heptafluoride is easy to proceed more effectively. In addition, if the ratio of the content of iodine pentafluoride to hydrogen fluoride is within the above numerical range, the degradation of the catalyst is not likely to occur, and the corrosion of the equipment (e.g., gasifier, piping, reactor) used in the manufacture of iodine heptafluoride is not likely to occur.

[0042] [4] Gasification process

[0043] The gasification process is a process of mixing fluorine gas in a liquid mixture, gasifying the liquid mixture, and obtaining a raw mixed gas containing iodine pentafluoride gas, hydrogen fluoride gas, and fluorine gas. The method of mixing fluorine gas in a liquid mixture is not particularly limited, and a method of mixing fluorine gas in a liquid mixture by blowing fluorine gas into the liquid mixture can be cited. By blowing fluorine gas into the liquid mixture, while mixing fluorine gas in the liquid mixture, the liquid mixture is gasified. As a result, a raw mixed gas containing iodine pentafluoride gas, hydrogen fluoride gas, and fluorine gas is obtained.

[0044] In addition, in the gasification process, fluorine gas and diluent gas can be blown into the liquid mixture to mix the fluorine gas and diluent gas into the liquid mixture. By blowing fluorine gas and diluent gas into the liquid mixture, the liquid mixture is gasified while the fluorine gas and diluent gas are mixed into the liquid mixture. As a result, a raw material mixed gas containing iodine pentafluoride gas, hydrogen fluoride gas, fluorine gas and diluent gas is obtained.

[0045] When the fluorine gas and the diluent gas are blown into the liquid mixture, the fluorine gas diluted with the diluent gas may be blown into the liquid mixture, or the fluorine gas and the diluent gas may be blown into the liquid mixture separately and simultaneously.

[0046] Furthermore, in the preparation step, hydrogen fluoride and liquid iodine pentafluoride are mixed to obtain a liquid mixture, and part or all of the hydrogen fluoride mixed with liquid iodine pentafluoride in the preparation step can also be mixed with fluorine gas (or fluorine gas and diluent gas) into the liquid mixture in the gasification step.

[0047] For example, in the case where all of the hydrogen fluoride mixed with liquid iodine pentafluoride in the preparation step is mixed with the liquid mixture in the gasification step, only liquid iodine pentafluoride is prepared in the preparation step without mixing hydrogen fluoride gas with liquid iodine pentafluoride, and hydrogen fluoride gas and fluorine gas (or hydrogen fluoride gas, fluorine gas and diluent gas) are mixed with liquid iodine pentafluoride in the gasification step to obtain a raw material mixed gas.

[0048] In addition, when a portion of the hydrogen fluoride mixed with the liquid iodine pentafluoride in the preparation step is mixed with the liquid mixture in the gasification step, the other portion of the hydrogen fluoride and the liquid iodine pentafluoride are mixed in the preparation step to form a liquid mixture, and a portion of the hydrogen fluoride gas and fluorine gas (or a portion of the hydrogen fluoride gas, fluorine gas and a diluent gas) are mixed with the liquid mixture in the gasification step to obtain a raw material mixed gas.

[0049] In the method for producing iodine heptafluoride of the present embodiment, the method for supplying fluorine gas or fluorine gas diluted with a diluent gas to the container containing the liquid mixture is not particularly limited, and examples thereof include the following methods.

[0050] That is, the following method can be cited: a gas supply mechanism is connected to a container filled with compressed fluorine gas or a container filled with compressed fluorine gas diluted with a diluent gas, and the fluorine gas or the fluorine gas diluted with the diluent gas is supplied to the container containing the liquid mixture while controlling the flow rate by the gas supply mechanism. The temperature of the fluorine gas or the fluorine gas diluted with the diluent gas when supplied to the container containing the liquid mixture is not particularly limited as long as it is a temperature at which the gas supply mechanism can operate.

[0051] Furthermore, the gas supply mechanism is not particularly limited as long as it has a mechanism capable of controlling the gas flow rate, but from the perspective of easy availability, it is preferred to use a mass flow controller, a flow meter, etc. Below, as an example of the gas supply mechanism, a mode in which a mass flow controller is used is shown.

[0052] In the method for producing iodine heptafluoride of the present embodiment, the method for supplying the raw material mixed gas to the reactor for carrying out the reaction for generating iodine heptafluoride is not particularly limited. For example, a method can be cited in which a liquid mixture (iodine pentafluoride) is heated in a vaporizer connected to a mass flow controller to vaporize it to generate a raw material mixed gas, and the raw material mixed gas is supplied to the reactor while controlling the flow rate with the mass flow controller.

[0053] Alternatively, a method of gasifying the liquid mixture using fluorine gas or fluorine gas diluted with a diluent gas may be used. That is, a mass flow controller is connected to a container filled with compressed fluorine gas or fluorine gas diluted with a diluent gas, and fluorine gas or fluorine gas diluted with a diluent gas is supplied to a vaporizer containing the liquid mixture while controlling the flow rate using the mass flow controller, the liquid mixture is gasified in the vaporizer, and the raw material mixed gas with the controlled flow rate is supplied to the reactor.

[0054] At this time, the fluorine gas or the fluorine gas diluted with the diluent gas can be blown into the liquid mixture (liquid phase) or supplied to the gas phase portion in the vaporizer. By blowing the fluorine gas or the fluorine gas diluted with the diluent gas into the liquid mixture, the liquid mixture can be efficiently vaporized even at a temperature below the boiling point of iodine pentafluoride.

[0055] In detail, in order to vaporize iodine pentafluoride, it is usually necessary to raise the temperature to a temperature close to the boiling point of iodine pentafluoride (97°C). However, if it is at a high temperature, iodine pentafluoride will be excessively vaporized and the purity of iodine heptafluoride may be reduced. Moreover, if low-purity iodine heptafluoride is used as an etching gas, there is a problem of reduced etching selectivity. In addition, if the container containing iodine pentafluoride is set to a high temperature, the corrosion inside the container is promoted, so it is not good to raise the temperature to a temperature near the boiling point of iodine pentafluoride. Moreover, the vapor pressure is low below 10°C, so the amount of iodine pentafluoride gas required for the reaction may not be obtained.

[0056] However, in the gasification process, if fluorine gas or fluorine gas diluted with a diluent gas is blown into the liquid mixture, the liquid mixture can be efficiently gasified even at a temperature below the boiling point of iodine pentafluoride. Therefore, by blowing fluorine gas or fluorine gas diluted with a diluent gas into the liquid mixture, the occurrence of various problems as described above can be suppressed.

[0057] [5] Vaporization temperature

[0058] In the gasification process, the temperature at which fluorine gas or fluorine gas diluted with a diluent gas is mixed with the liquid mixture to vaporize the liquid mixture (hereinafter sometimes referred to as "gasification temperature") is preferably above 10°C and below 80°C, more preferably above 20°C and below 70°C, and more preferably above 30°C and below 60°C.

[0059] For example, the temperature inside the vaporizer when the liquid mixture is vaporized and supplied to the reactor can be appropriately changed according to the supply rate of the raw mixed gas to the reactor. Therefore, it is preferred to control the supply rate of the raw mixed gas to the reactor so that the temperature inside the vaporizer is within the above-mentioned numerical range.

[0060] If the temperature in the vaporizer is within the above-mentioned temperature range, the vapor pressure of iodine pentafluoride is sufficiently high even at a temperature below the boiling point of iodine pentafluoride. Therefore, in addition to excellent productivity of iodine heptafluoride, the equipment (e.g., vaporizer, piping, reactor) used in the production of iodine heptafluoride is not easily corroded by iodine pentafluoride.

[0061] [6] Molar ratio of fluorine gas to iodine pentafluoride

[0062] In order to efficiently produce high-purity iodine heptafluoride by the method for producing iodine heptafluoride of the present embodiment, the ratio [F2] / [IF5] of the molar amount of fluorine gas [F2] to the molar amount of iodine pentafluoride [IF5] in the raw material mixed gas generated in the gasification step is preferably 1.0 or more and 30 or less, more preferably 5 or more and 25 or less, and further preferably 10 or more and 15 or less. If the ratio [F2] / [IF5] is within the above numerical range, it is possible to suppress the unreacted iodine pentafluoride and fluorine gas from remaining.

[0063] [7] Dilution gas

[0064] In the gasification process of the method for producing iodine heptafluoride of the present embodiment, as described above, the diluent gas and the fluorine gas may be mixed into the liquid mixture to gasify the liquid mixture. Therefore, in the reaction process of the method for producing iodine heptafluoride of the present embodiment, the reaction of iodine pentafluoride and fluorine gas may be carried out in a state diluted by the diluent gas.

[0065] In the reaction step of the method for producing iodine heptafluoride of this embodiment, by mixing the diluent gas with the fluorine gas and performing the reaction in a diluted state, it becomes easy to control the reaction by suppressing the generation of local excess heat, thereby suppressing runaway of the reaction and corrosion of the reactor.

[0066] The type of diluent gas is not particularly limited as long as it is an inert gas, and for example, at least one of nitrogen (N2), argon (Ar) and helium (He) can be used. Among these inert gases, nitrogen is preferred from the viewpoint of easy availability and low cost.

[0067] The amount of the diluent gas used is not particularly limited, and is preferably 30% by volume or more of the total gas volume of the fluorine gas and the diluent gas in the reactor, more preferably 50% by volume or more, and further preferably 70% by volume or more. If the amount of the diluent gas used is within the above numerical range, the risk of local reaction and runaway reaction can be fully reduced, so iodine heptafluoride can be manufactured more safely.

[0068] [8] Reaction temperature

[0069] In the reaction step of the method for producing iodine heptafluoride of the present embodiment, the temperature for the reaction of iodine pentafluoride and fluorine gas (hereinafter sometimes referred to as "reaction temperature") is preferably 150°C to 380°C, more preferably 180°C to 350°C, and further preferably 210°C to 320°C.

[0070] If the reaction temperature is within the above temperature range, the reaction of iodine pentafluoride and fluorine gas is easy to proceed smoothly. In addition, if the reaction temperature is within the above temperature range, corrosion of the reactor caused by the compounds (fluorine gas, iodine pentafluoride, hydrogen fluoride) in the raw material mixed gas and iodine heptafluoride is not easy to occur, so it is not necessary to use expensive materials such as platinum as the material of the reactor. Furthermore, if the reaction temperature is within the above temperature range, the reverse reaction of the chemical reaction formula (1) is not easy to proceed, so the decomposition of iodine heptafluoride as the target product is not easy to occur during the reaction.

[0071] The method for reacting iodine pentafluoride and fluorine gas at a temperature within the above temperature range is not particularly limited, and examples thereof include a method of supplying a raw material mixed gas into a reactor while adjusting the temperature in the reactor to a temperature within the above temperature range.

[0072] The method for adjusting the temperature in the reactor to a temperature within the above temperature range is not particularly limited, and examples thereof include heating the reactor with a heating means such as an electric heater or steam, or cooling the reactor with a jacket through which a cold medium flows, depending on the situation.

[0073] Furthermore, when the reaction of iodine pentafluoride and fluorine gas is carried out with the catalyst disposed in the reactor, the reactor can be heated with the catalyst disposed in the reactor, and after the reactor and the catalyst are adjusted to the desired temperature, the raw material mixed gas is supplied to the reactor. When the temperature of the catalyst is within the above temperature range and is high, the yield of iodine heptafluoride is improved.

[0074] [9] Response time

[0075] In the reaction step of the method for producing iodine heptafluoride of the present embodiment, the time for the reaction of iodine pentafluoride and fluorine gas (hereinafter, sometimes referred to as "reaction time") is not particularly limited, and can be appropriately set in consideration of the yield and productivity of iodine heptafluoride, and is preferably from 10 seconds to 100 seconds, more preferably from 20 seconds to 90 seconds, and further preferably from 30 seconds to 80 seconds.

[0076] In the case where the reaction process is performed by circulating the raw material mixed gas in a reactor filled with a catalyst, the time from the raw material mixed gas supplied to the reactor flowing into the reactor to the time of being discharged, that is, the time the raw material mixed gas stays in the reactor can be regarded as the reaction time. Therefore, the reaction time is sometimes recorded as "retention time" below. Furthermore, the residence time is defined as the reciprocal of the space velocity (SV) (=supply rate of the raw material mixed gas to the reactor / capacity of the reactor).

[0077] As long as the reaction temperature at which the reverse reaction of iodine heptafluoride decomposes into iodine pentafluoride and fluorine gas is not significant, the yield of iodine heptafluoride increases with the increase of residence time. However, with the increase of residence time, the necessity of increasing the volume of the reactor is generated. In addition, considering the productivity of iodine heptafluoride, the residence time is preferably short. Considering these factors, the residence time is preferably within the above-mentioned numerical range.

[0078]

[10] Catalyst

[0079] In the reaction step of the method for producing iodine heptafluoride of the present embodiment, a catalyst is used to smoothly carry out the reaction of generating iodine heptafluoride from iodine pentafluoride and fluorine gas. In order to control the reaction of generating iodine heptafluoride, the reaction of iodine pentafluoride and fluorine gas may be carried out in a reactor having a catalyst disposed therein.

[0080] The catalyst preferably has low reactivity with iodine pentafluoride, hydrogen fluoride, fluorine gas, and iodine heptafluoride. As a substance used as a catalyst, it is preferred to contain at least one of a metal belonging to the third period element or the fourth period element of the periodic table and belonging to any group of elements from the third group to the thirteenth group (i.e., aluminum (Al), scandium (Sc), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), and gallium (Ga).

[0081] These metals may be simple metals, alloys, or metal compounds. Examples of metal compounds include oxides and fluorides. The catalyst may be used alone or in combination of two or more.

[0082] Specific examples of the catalyst are shown below. As a single substance of the metal, aluminum, scandium, iron, cobalt, nickel, etc. can be listed. As an oxide of the metal, aluminum oxide (Al2O3 such as α-Al2O3), scandium (III) oxide (Sc2O3), vanadium oxide (VO, V2O3, V2O5), chromium oxide (CrO, Cr2O3, CrO2, CrO3), iron oxide (FeO, Fe2O3, Fe3O4), cobalt (II) oxide (CoO), nickel (II) oxide (NiO), etc. can be listed.

[0083] As metal fluorides, aluminum fluoride (AlF3), scandium (III) fluoride (ScF3), vanadium (III) fluoride (VF3), chromium (III) fluoride (CrF3), iron fluoride (FeF2, FeF3), cobalt fluoride (CoF2, CoF3), nickel (II) fluoride (NiF2), etc. In view of the low reactivity with iodine pentafluoride, hydrogen fluoride, fluorine gas, and iodine heptafluoride and the difficulty in obtaining, Al2O3, AlF3, FeF3, CoF2, and NiF2 are more preferred.

[0084] The shape of the catalyst is not particularly limited as long as the fluorine gas and iodine pentafluoride gas flowing in the reactor can be efficiently contacted and these gases do not clog the reactor.

[0085] If specific examples are given, fluorine gas, hydrogen fluoride gas, iodine pentafluoride gas or iodine heptafluoride gas can be brought into contact with a metal porous body or a metal mesh at high temperature to fluorinate the metal surface to generate a material of metal fluoride as a catalyst. Alternatively, a material obtained by molding a commercially available metal fluoride or metal oxide powder into pellets, or a commercially available metal fluoride or metal oxide molded product can be directly used.

[0086] However, from the viewpoint that the contact area per unit volume between the gas and the metal surface is large and the reaction to generate iodine heptafluoride is carried out efficiently, the shape of the catalyst is preferably porous, mesh-like, etc. In particular, from the viewpoint of easy availability, a pore diameter of 0.3 mm or more and 3.2 mm or less and a specific surface area of ​​500 m 2 / m 3 Above and 10000m 2 / m 3 A porous body having a wire diameter of 0.04 mm to 0.8 mm and a mesh size of 0.04 mm to 0.98 mm.

[0087] The amount of the catalyst used varies depending on the shape of the catalyst, but is preferably an amount that makes the space filling rate in the reactor 30% to 80%, more preferably 40% to 70%, and even more preferably 50% to 60%.

[0088] Furthermore, the amount of the catalyst used can also be expressed by the mass of the catalyst used per unit mass of iodine heptafluoride generated per unit time. The amount of the catalyst used in the case of such expression is preferably 0.14 or more and 1.40 or less, more preferably 0.16 or more and 0.71 or less, and further preferably 0.18 or more and 0.47 or less.

[0089]

[11] Reactor structure

[0090] The reactor that can be used in the manufacture method of iodine heptafluoride of the present embodiment is not particularly limited as long as it has a structure that iodine pentafluoride gas and fluorine gas can contact with the catalyst, but a flow-through reactor is preferred. In addition, the shape of the reactor can be a tubular or a groove type, and as a tubular type, it can be a single tubular or a multi-tubular type, and the catalyst filling method can be a fluidized bed or a fixed bed. As the shape of the reactor, preferably a single tubular or a multi-tubular type, as a catalyst filling method, preferably a fixed bed.

[0091] When a flow reactor is used, it is necessary to simultaneously supply iodine pentafluoride gas and fluorine gas into the flow reactor.

[0092] However, in the method for producing iodine heptafluoride of the present embodiment, if iodine heptafluoride is to be obtained continuously, a flow-through tubular reactor is preferably used as the reactor. The shape of the flow-through tubular reactor is not particularly limited as long as it can allow iodine pentafluoride gas, fluorine gas, etc. to circulate. When a catalyst is arranged in the reactor, it is preferably capable of accommodating the catalyst and having a cavity so that the gas can circulate in a state where the catalyst is accommodated.

[0093]

[12] Reactor material

[0094] The reactor that can be used in the manufacturing method of iodine heptafluoride of the present embodiment needs to be formed of a material that is resistant to corrosion by fluorine gas, hydrogen fluoride, and iodine pentafluoride. Specifically, metals such as nickel, nickel-based alloys, aluminum, stainless steel, platinum, and ceramics such as aluminum oxide can be exemplified. As specific examples of nickel-based alloys, INCONEL alloy (registered trademark), HASTELLOY alloy (registered trademark), MONEL alloy (registered trademark), etc. can be cited.

[0095] When the temperature in the reactor is set to 150°C or higher, nickel, nickel-based alloys, platinum, and aluminum oxide, which are particularly excellent in corrosion resistance, are preferably selected from the above materials, and nickel and nickel-based alloys, which are easily available and relatively inexpensive, are particularly preferred. Furthermore, metal oxides and metal fluorides used as catalysts may also be used as the material of the reactor.

[0096] As a reactor that can be used in the method for producing iodine heptafluoride of the present embodiment, a bright annealing tube made of nickel is preferably used. Nickel has excellent corrosion resistance to high-temperature fluorine gas, hydrogen fluoride, iodine pentafluoride, and iodine heptafluoride used in the method for producing iodine heptafluoride of the present embodiment, and the bright annealing tube has a smooth surface, so the risk of abnormal reaction between the above-mentioned gas and metal residue and damage to the reactor can be minimized.

[0097] If a nickel-made reactor is used to implement the manufacturing method of iodine heptafluoride of the present embodiment, the inner surface of the reactor may be fluorinated by fluorine gas, hydrogen fluoride, iodine pentafluoride, or iodine heptafluoride to become NiF2. However, NiF2 can be used as a catalyst in the manufacturing method of iodine heptafluoride of the present embodiment, and it can be seen that it does not matter even if the inner surface of the reactor becomes NiF2. Similarly, even if the material of the reactor is the metal exemplified above, it does not matter if the inner surface of the reactor is fluorinated by the reaction of the metal with fluorine gas, hydrogen fluoride, iodine pentafluoride, or iodine heptafluoride.

[0098] As raw materials for bright annealed tubes, in addition to nickel, nickel-based alloys containing iron, copper, chromium, molybdenum, etc. (such as INCONEL alloy (registered trademark), HASTELLOY alloy (registered trademark), MONEL alloy (registered trademark)) and NiF2 having a nickel content of 50 mass% or more can be used.

[0099]

[13] Cooling capture container

[0100] In the method for producing iodine heptafluoride of the present embodiment, since a gas containing iodine heptafluoride (hereinafter sometimes referred to as "reaction mixture gas") is obtained through the reaction process, iodine heptafluoride can be captured by cooling the reaction mixture gas. For example, a cooling and capturing container can be used for cooling the reaction mixture gas.

[0101] If the reaction mixture gas obtained in the reaction step is supplied to a cooling and collecting container and cooled to a temperature at which iodine pentafluoride is liquefied and iodine heptafluoride is neither solidified nor liquefied, iodine pentafluoride and iodine heptafluoride can be separated. For example, if cooled to 10° C., most of iodine pentafluoride becomes liquid and is collected in a cooling and collecting container (hereinafter, sometimes referred to as a “cooling and collecting container for collecting iodine pentafluoride”), but most of iodine heptafluoride remains in a gaseous state and passes through the cooling and collecting container.

[0102] Furthermore, although a part of iodine heptafluoride may solidify or dissolve in iodine pentafluoride and be captured in a cooling and capturing container for capturing iodine pentafluoride, most of iodine heptafluoride easily passes through the cooling and capturing container for capturing iodine pentafluoride in the form of gas.

[0103] The cooling temperature of the reaction mixture gas in the collection container is preferably in the range of -80°C to 0°C, more preferably in the range of -70°C to -10°C, and further preferably in the range of -60°C to -20°C. Within this temperature range, iodine pentafluoride can be captured with high efficiency, and the amount of captured iodine heptafluoride is small, so the separation efficiency of iodine heptafluoride and iodine pentafluoride is high.

[0104] If the capture is performed at a temperature below 9.4°C, the melting point of iodine pentafluoride, there is a concern that iodine pentafluoride may solidify in the piping connected to the cooling and capturing container, causing clogging of the piping. If a diluent gas is used in the reaction step and the reaction mixture gas is accompanied by a diluent gas, clogging of the piping caused by the solidification of iodine pentafluoride can be suppressed.

[0105] The internal pressure of the cooling and collecting container for collecting iodine pentafluoride is preferably 0.05 MPa to 0.5 MPa, more preferably 0.1 MPa to 0.3 MPa. The pressure in the present invention refers to absolute pressure unless otherwise specified.

[0106] If iodine heptafluoride that has passed through a cooling and capturing container for capturing iodine pentafluoride is supplied to another cooling and capturing container (hereinafter, sometimes referred to as a "cooling and capturing container for capturing iodine heptafluoride") and cooled to a temperature at which iodine heptafluoride solidifies or liquefies, iodine heptafluoride can be captured in the other cooling and capturing container. The cooling temperature in the cooling and capturing container for capturing iodine heptafluoride is not particularly limited as long as it is a temperature lower than the boiling point of iodine heptafluoride. However, in order to improve the capture efficiency of iodine heptafluoride, it is preferably cooled to a temperature at which the vapor pressure of iodine heptafluoride is sufficiently low. Specifically, the cooling temperature in the cooling and capturing container for capturing iodine heptafluoride is preferably in the range of above -100°C and below 0°C, and more preferably in the range of above -80°C and below -20°C.

[0107] Furthermore, if the capture is performed at a temperature below the melting point of iodine heptafluoride, there is a concern that iodine heptafluoride solidifies in the piping connected to the cooling and capturing container for capturing iodine heptafluoride, resulting in clogging of the piping. If a diluent gas is used in the reaction process and the reaction mixture gas is accompanied by the diluent gas, clogging of the piping caused by the solidification of iodine heptafluoride can be suppressed. Furthermore, the internal pressure of the cooling and capturing container for capturing iodine heptafluoride is preferably 0.05 MPa or more and 0.5 MPa or less, and more preferably 0.1 MPa or more and 0.3 MPa or less.

[0108] The cooling and collecting container for collecting iodine pentafluoride and the cooling and collecting container for collecting iodine heptafluoride need to be formed of a corrosion-resistant material that is difficult to react with fluorine gas, hydrogen fluoride, iodine pentafluoride, and iodine heptafluoride. Specifically, metals such as nickel, nickel-based alloys, aluminum, stainless steel, platinum, and ceramics such as alumina can be exemplified.

[0109] Specific examples of nickel-based alloys include INCONEL alloy (registered trademark), HASTELLOY alloy (registered trademark), MONEL alloy (registered trademark), etc. In addition, the inner surface of the cooling and collecting container formed of the above metals that contacts fluorine gas, etc. may be fluorinated. Among them, aluminum, alumina, and stainless steel, which are easily available and relatively inexpensive, are particularly preferred.

[0110] In addition, the capacity and number of the cooling and collecting container for capturing iodine pentafluoride and the cooling and collecting container for capturing iodine heptafluoride are not particularly limited and can be set arbitrarily according to the amount of the substance captured. When a plurality of cooling and collecting containers are provided, the cooling and collecting containers can also be connected in series or in parallel. Hereinafter, an example in which one cooling and collecting container is provided is used for explanation.

[0111]

[14] Example of an iodine heptafluoride production device

[0112] The method for producing iodine heptafluoride of this embodiment can be Figure 1 The process is implemented in the iodine heptafluoride production apparatus shown. Figure 1 The iodine heptafluoride manufacturing apparatus shown comprises: a vaporizer 11 for storing liquid iodine pentafluoride or a liquid mixture and vaporizing the liquid mixture to manufacture a raw material mixed gas; a reactor 20 for reacting iodine pentafluoride and fluorine gas in the raw material mixed gas sent from the vaporizer 11; a fluorine gas supply device 1 for supplying fluorine gas to the vaporizer 11; a mass flow controller 4 for controlling the flow rate of fluorine gas supplied from the fluorine gas supply device 1 to the vaporizer 11; a hydrogen fluoride supply device 2 for supplying hydrogen fluoride gas to the vaporizer 11; a mass flow controller 5 for controlling the flow rate of hydrogen fluoride gas supplied from the hydrogen fluoride supply device 2 to the vaporizer 11; a dilution gas supply device 3 for supplying an inert gas to the vaporizer 11; a mass flow controller 6 for controlling the flow rate of the inert gas supplied from the dilution gas supply device 3 to the vaporizer 11; and a heating device 12 for heating the stored material in the vaporizer 11.

[0113] A metal (not shown) as a catalyst is disposed in the reactor 20. The reactor 20 is provided with a heating device (not shown) such as an electric furnace, and the temperature in the reactor 20 can be controlled to an arbitrary temperature. The reactor 20 is provided with a pressure gauge 21 for measuring the pressure in the reactor 20.

[0114] in addition, Figure 1The iodine heptafluoride production apparatus shown in the figure is further provided with a cooling and capturing container 31 (equivalent to the above-mentioned "cooling and capturing container for capturing iodine pentafluoride"). The cooling and capturing container 31 cools the reaction mixture gas containing iodine pentafluoride and iodine heptafluoride, captures iodine pentafluoride, and allows iodine heptafluoride to pass through to separate iodine heptafluoride and iodine pentafluoride. The cooling and capturing container 31 is provided with a cooling device 32, and the temperature in the cooling and capturing container 31 can be controlled by the cooling device 32. In addition, the cooling and capturing container 31 is provided with a thermometer 33 for measuring the temperature in the cooling and capturing container 31.

[0115] The cooling and collecting container 31 is connected to the reactor 20 via a pipe. The pipe connecting the reactor 20 and the cooling and collecting container 31 is provided with a pressure regulating valve 22 and a Fourier transform infrared spectrophotometer 30, and the pressure regulating valve 22 and the Fourier transform infrared spectrophotometer 30 are arranged in series in the order described starting from the reactor 20 side.

[0116] Next, use Figure 1 An example of a method for producing iodine heptafluoride using the iodine heptafluoride production apparatus shown in FIG.

[0117] Liquid iodine pentafluoride 10 is stored in a vaporizer 11, and hydrogen fluoride gas is blown into it from a hydrogen fluoride supply device 2. The concentration of hydrogen fluoride in the iodine pentafluoride 10 is controlled by supplying hydrogen fluoride gas while controlling the flow rate with a mass flow controller 5.

[0118] At this time, the liquid iodine pentafluoride 10 in the vaporizer 11 is heated by the heating device 12 to increase the vaporized amount of the iodine pentafluoride 10. Thus, the liquid iodine pentafluoride 10 and the iodine pentafluoride gas exist in the vaporizer 11.

[0119] Fluorine gas can be supplied from the fluorine gas supply device 1 to the liquid iodine pentafluoride 10 in the vaporizer 11 while the flow rate is controlled by the mass flow controller 4, and inert gas can be supplied from the dilution gas supply device 3 while the flow rate is controlled by the mass flow controller 6. At this time, the concentration of fluorine gas in the gas supplied to the liquid iodine pentafluoride 10 in the vaporizer 11 can be controlled by the mass flow controllers 4 and 6.

[0120] That is, if only fluorine gas is supplied without supplying inert gas, fluorine gas with a concentration of 100% can be supplied to the liquid iodine pentafluoride 10 in the vaporizer 11. Alternatively, if both fluorine gas and inert gas are supplied, fluorine gas diluted with inert gas to an arbitrary concentration can be supplied to the liquid iodine pentafluoride 10 in the vaporizer 11.

[0121] In addition, fluorine gas diluted with an inert gas to x volume % is hereinafter referred to as "x volume % fluorine gas". For example, fluorine gas diluted with an inert gas to 20 volume % is referred to as "20 volume % fluorine gas", fluorine gas diluted with an inert gas to 50 volume % is referred to as "50 volume % fluorine gas", and fluorine gas not diluted with an inert gas is referred to as "100 volume % fluorine gas".

[0122] Fluorine gas is supplied to the liquid iodine pentafluoride 10 in the vaporizer 11, and the liquid iodine pentafluoride 10 is vaporized to become iodine pentafluoride gas, thereby generating a raw material mixed gas containing iodine pentafluoride gas, hydrogen fluoride gas, and fluorine gas. When an inert gas is supplied to the liquid iodine pentafluoride 10 in the vaporizer 11 together with the fluorine gas, a raw material mixed gas containing iodine pentafluoride gas, hydrogen fluoride gas, fluorine gas, and inert gas is generated. Then, the generated raw material mixed gas is sent from the vaporizer 11 to the reactor 20 via a pipe.

[0123] The iodine pentafluoride gas and the fluorine gas react in the reactor 20, and the iodine pentafluoride gas and the fluorine gas are supplied to react in such a manner that the ratio [F2] / [IF5] of the molar amount of fluorine gas [F2] to the molar amount of iodine pentafluoride [IF5] in the raw material mixed gas is greater than 1.0 and less than 30.

[0124] During the reaction, the pressure in the reactor 20 is measured by the pressure gauge 21. When fluorine gas is supplied to the liquid iodine pentafluoride 10 in the vaporizer 11, a reaction mixture gas containing iodine heptafluoride and iodine pentafluoride is obtained as a result of the reaction. When an inert gas is supplied to the liquid iodine pentafluoride 10 in the vaporizer 11 together with the fluorine gas, a reaction mixture gas containing iodine heptafluoride, iodine pentafluoride and the inert gas is obtained. However, the reaction mixture gas may contain nitrogen, oxygen and hydrogen fluoride in addition to the unreacted fluorine gas.

[0125] The pressure of the obtained reaction mixture gas is adjusted to about 0.1 MPa by the pressure regulating valve 22, and the reaction mixture gas is sent to the Fourier transform infrared spectrophotometer 30. After the components of the reaction mixture gas are quantitatively analyzed by Fourier transform infrared spectroscopic analysis, the reaction mixture gas is sent to the cooling and collecting container 31. The temperature in the cooling and collecting container 31 is controlled to a predetermined temperature by the cooling device 32, so that the reaction mixture gas is separated into a gas component containing iodine heptafluoride and a liquid component containing iodine pentafluoride.

[0126] Specifically, most of the iodine pentafluoride in the reaction mixture gas is liquefied in the cooling and capturing container 31 and captured by the cooling and capturing container 31. On the other hand, although a part of the iodine heptafluoride in the reaction mixture gas is solidified or liquefied and captured, most of it is in gaseous form, and therefore, a gas containing gaseous iodine heptafluoride and at least one selected from unreacted fluorine gas and inert gas is discharged from the cooling and capturing container 31 as exhaust gas.

[0127] The exhaust gas containing iodine heptafluoride having passed through the cooling and collecting container 31 contains iodine heptafluoride gas, unreacted fluorine gas, and inert gas as main components. By further purifying the exhaust gas by distillation, adsorption, or the like, high-purity iodine heptafluoride can be produced.

[0128] Example

[0129] The present invention will be described in more detail below with reference to Examples and Comparative Examples.

[0130] [Catalyst Preparation Example 1]

[0131] A porous aluminum body (manufactured by Taisei Industry Co., Ltd., pore diameter 0.5 mm) was placed in a nickel bright annealing tube (inner diameter 25.4 mm, length 900 mm) equipped with an electric heater and a pressure gauge. The bright annealing tube was heated by the electric heater to a temperature of 300°C.

[0132] The nickel bright annealed tube is a bright annealed tube made of Ni201 (nickel purity 99.7 mass % or more) standardized in "nickel and nickel alloy seamless tubes" of JIS H4552:2000.

[0133] Next, 50% by volume fluorine gas is introduced from one end (hereinafter referred to as the "inlet") of the bright annealing tube at a flow rate of 200 sccm, and exhausted from the other end (hereinafter referred to as the "outlet"). As a result, the aluminum and fluorine gas that constitute the aluminum porous body react to form an AlF3 porous body. At this time, the pressure in the bright annealing tube is 0.1 MPa. Here, "sccm" is the volume flow rate (cm2) per minute standardized under the conditions of 0°C and 1 atmosphere. 3 ).

[0134] The completion of the reaction of generating AlF3 on the aluminum surface by the reaction between aluminum and fluorine gas was confirmed by the following method. The exhaust gas discharged from the outlet of the bright annealing tube was circulated in a 10 mass % potassium iodide (KI) aqueous solution for 5 minutes, and the potassium iodide aqueous solution after the exhaust gas was circulated was redox titrated using a 0.1N sodium thiosulfate aqueous solution. The concentration of fluorine gas discharged from the outlet of the bright annealing tube was quantified by this redox titration.

[0135] When the concentration of the fluorine gas discharged from the outlet of the bright annealing tube is equal to the concentration of the fluorine gas supplied from the inlet of the bright annealing tube, it is determined that the reaction between aluminum and fluorine gas is completed. In addition, redox titration is performed at the time point when 50 volume % fluorine gas is circulated in the bright annealing tube for 3 hours, thereby confirming the completion of the reaction.

[0136] The AlF 3 porous body obtained as described above was used as a catalyst, and a bright annealing tube in which the AlF 3 porous body was arranged was used as a reactor for producing iodine heptafluoride.

[0137] [Catalyst Preparation Example 2]

[0138] The preparation and analysis of the NiF2 catalyst were carried out in the same manner as in Catalyst Preparation Example 1, except that the aluminum porous body was changed to small pieces (1.6 mm thick, 5 mm wide, 5 mm long) cut from a 99% pure nickel plate (manufactured by Niraco Co., Ltd., 1.6 mm thick, 100 mm wide, 110 mm long).

[0139] [Catalyst Preparation Example 3]

[0140] The preparation and analysis of the CoF2 catalyst were carried out in the same manner as in Catalyst Preparation Example 1, except that the aluminum porous body was changed to small pieces (0.1 mm thick, 5 mm wide, 5 mm long) cut from a cobalt plate with a purity of 99.9% (produced by Niraco Co., Ltd., 0.1 mm thick, 50 mm wide, 50 mm long).

[0141] [Catalyst Preparation Example 4]

[0142] The preparation and analysis of the FeF3 catalyst were carried out in the same manner as in Catalyst Preparation Example 1, except that the aluminum porous body was changed to small pieces (0.10 mm thick, 5 mm wide, 5 mm long) cut from an iron plate with a purity of 99.998% (produced by Niraco Co., Ltd., 0.10 mm thick, 50 mm wide, 50 mm long).

[0143] [Catalyst Preparation Example 5]

[0144] The preparation and analysis of the CrF3 catalyst were carried out in the same manner as in Catalyst Preparation Example 1, except that the aluminum porous body was changed to small pieces (2.0 mm thick, 5 mm wide, 5 mm long) cut from a chromium plate with a purity of 99.9% (produced by Niraco Co., Ltd., 2.0 mm thick, 50 mm wide, 50 mm long).

[0145] [Catalyst Preparation Example 6]

[0146] The preparation and analysis of the VF3 catalyst were carried out in the same manner as in Catalyst Preparation Example 1, except that the aluminum porous body was changed to small pieces (0.1 mm thick, 5 mm wide, 5 mm long) cut from a vanadium plate having a purity of 99.7% (produced by Niraco Co., Ltd., 0.1 mm thick, 50 mm wide, 50 mm long).

[0147] [Catalyst Preparation Example 7]

[0148] The preparation and analysis of the ScF3 catalyst were carried out in the same manner as in Catalyst Preparation Example 1, except that the aluminum porous body was changed to small pieces (0.25 mm thick, 5 mm wide, 5 mm long) cut from a scandium plate with a purity of 99.9% (produced by NIRACO Co., Ltd., 0.25 mm thick, 25 mm wide, 25 mm long).

[0149] [Example 1]

[0150] Use with Figure 1 The iodine heptafluoride production apparatus shown in FIG. 1 was used to produce iodine heptafluoride. A bright annealing tube (reactor) containing 84 g of the catalyst (porous body made of AlF3) prepared in Preparation Example 1 was heated in an electric furnace to a temperature (i.e., reaction temperature) in the bright annealing tube of 280° C. Therefore, the temperature of the catalyst also became 280° C.

[0151] Next, a liquid mixture consisting of hydrogen fluoride and iodine pentafluoride is placed in a vaporizer, and the liquid mixture is heated to 40°C. The content of hydrogen fluoride in the liquid mixture (represented as "HF concentration" in Table 1) is 10% by mass of the content of iodine pentafluoride. Next, iodine pentafluoride is vaporized by blowing nitrogen into the liquid phase of the liquid mixture heated to 40°C, and a gas containing iodine pentafluoride gas is obtained, which is supplied to the bright annealing tube. The flow rate of nitrogen gas blown into the liquid mixture is 800 sccm at 0°C and 101 kPa. The concentration of iodine pentafluoride in the gas containing iodine pentafluoride gas is measured by Fourier transform infrared spectroscopy, and the flow rate of iodine pentafluoride gas at this time is calculated, and the result is 40 sccm.

[0152] Next, 100% by volume fluorine gas is blown into the liquid phase of the liquid mixture in the vaporizer at a flow rate of 160 sccm to vaporize iodine pentafluoride (i.e., the vaporization temperature is 40°C). Thus, a raw material mixed gas containing iodine pentafluoride gas, hydrogen fluoride gas, fluorine gas and nitrogen gas is generated, and is therefore supplied to the bright annealing tube. In other words, a raw material mixed gas having a composition ratio (volume ratio) of iodine pentafluoride:fluorine gas = 1:4 when the total of iodine pentafluoride gas and fluorine gas is 100 is supplied to the bright annealing tube. Therefore, the ratio [F2] / [IF5] of the molar amount of fluorine gas [F2] in the raw material mixed gas to the molar amount of iodine pentafluoride [IF5] is 4.0. At this time, the time (reaction time) that the raw material mixed gas stays in the bright annealing tube is 22 seconds.

[0153] Under such conditions, the raw material mixed gas was circulated for 1 hour, and the reaction of obtaining iodine heptafluoride from fluorine gas and iodine pentafluoride was continuously carried out. That is, the reaction mixture gas discharged from the bright annealing tube was returned to the bright annealing tube for reaction again. This operation was continuously carried out for 1 hour. Then, the reaction mixture gas after the reaction for 1 hour was subjected to Fourier transform infrared spectroscopic analysis to measure the concentrations of iodine pentafluoride, iodine heptafluoride and hydrogen fluoride in the reaction mixture gas. At this time, the amount of nitrogen was set to be constant, and the composition of the reaction mixture gas and the conversion rate of iodine pentafluoride, that is, the yield of iodine heptafluoride based on iodine pentafluoride, were calculated. The results are shown in Table 1.

[0154] The concentration of iodine pentafluoride in the raw material mixed gas before the reaction is calculated as follows. That is, assuming that the concentration of iodine pentafluoride in the raw material mixed gas before the reaction is equal to the sum of the concentration of iodine pentafluoride in the reaction mixture gas after the reaction and the concentration of iodine heptafluoride in the reaction mixture gas after the reaction, the concentration of iodine pentafluoride in the reaction mixture gas after the reaction, the concentration of iodine heptafluoride, the concentration of the diluent gas added as needed, and the flow rate of the reaction mixture gas after the reaction are calculated.

[0155] Fourier transform infrared spectrophotometry was performed using a Fourier transform infrared spectrophotometer Nicolet iS5 manufactured by Thermo Fisher Scientific, and the concentrations of iodine pentafluoride, iodine heptafluoride, and hydrogen fluoride were measured by this analysis. The measurement wavelength (wave number) used in the analysis using the infrared spectrophotometer was 710 cm for iodine pentafluoride. -1 , iodine heptafluoride is 749cm -1 , hydrogen fluoride is 4039cm -1 .

[0156] The yield of iodine heptafluoride based on iodine pentafluoride can be calculated by the following formula.

[0157] Yield of iodine heptafluoride (%) = concentration of iodine heptafluoride (volume %) / [concentration of iodine heptafluoride (volume %) + concentration of iodine pentafluoride (volume %)]

[0158] Table 1

[0159]

[0160] [Example 2]

[0161] The reaction and analysis were carried out in the same manner as in Example 1 except that the catalyst was changed to the NiF2 catalyst prepared in Catalyst Preparation Example 2. The results are shown in Table 1.

[0162] [Example 3]

[0163] The reaction and analysis were carried out in the same manner as in Example 1 except that the catalyst was changed to the CoF2 catalyst prepared in Catalyst Preparation Example 3. The results are shown in Table 1.

[0164] [Example 4]

[0165] The reaction and analysis were carried out in the same manner as in Example 1 except that the catalyst was changed to the FeF3 catalyst prepared in Catalyst Preparation Example 4. The results are shown in Table 1.

[0166] [Example 5]

[0167] The reaction and analysis were carried out in the same manner as in Example 1 except that the catalyst was changed to the CrF3 catalyst prepared in Catalyst Preparation Example 5. The results are shown in Table 1.

[0168] [Example 6]

[0169] The reaction and analysis were carried out in the same manner as in Example 1 except that the catalyst was changed to the VF3 catalyst prepared in Catalyst Preparation Example 6. The results are shown in Table 1.

[0170] [Example 7]

[0171] The reaction and analysis were carried out in the same manner as in Example 1 except that the catalyst was changed to the ScF3 catalyst prepared in Catalyst Preparation Example 7. The results are shown in Table 1.

[0172] [Example 8]

[0173] The reaction and analysis were carried out in the same manner as in Example 1 except that the catalyst was changed to α-Al 2 O 3 (manufactured by NIKETO CORPORATION, purity 99.5%). The results are shown in Table 1.

[0174] [Comparative Example 1]

[0175] The reaction and analysis were carried out in the same manner as in Example 1 except that no catalyst was used (the reactor was not filled with a catalyst).

[0176] [Example 9]

[0177] The reaction and analysis were carried out in the same manner as in Example 1 except that the vaporization temperature was set to 10° C. and the flow rate of the iodine pentafluoride gas was set to 35 sccm.

[0178] [Example 10]

[0179] The reaction and analysis were carried out in the same manner as in Example 1 except that the vaporization temperature was 80° C. and the flow rate of the iodine pentafluoride gas was 58 sccm.

[0180] [Example 11]

[0181] The reaction and analysis were carried out in the same manner as in Example 1 except that the reaction temperature was 200°C. The results are shown in Table 1.

[0182] [Example 12]

[0183] The reaction and analysis were carried out in the same manner as in Example 1 except that the reaction temperature was 380°C. The results are shown in Table 1.

[0184] [Example 13]

[0185] The reaction and analysis were performed in the same manner as in Example 1 except that the length of the bright annealing tube was 410 mm and the residence time was 10 seconds (s).

[0186] [Example 14]

[0187] The reaction and analysis were carried out in the same manner as in Example 1 except that the length of the bright annealing tube was 3600 mm and the residence time was 88 seconds. The results are shown in Table 1.

[0188] [Example 15]

[0189] The reaction and analysis were performed in the same manner as in Example 1 except that the length of the bright annealing tube was 4100 mm and the residence time was 100 seconds. The results are shown in Table 1.

[0190] [Example 16]

[0191] The reaction and analysis were performed in the same manner as in Example 1 except that the length of the bright annealing tube was 8200 mm and the residence time was 200 seconds. The results are shown in Table 1.

[0192] [Example 17]

[0193] The reaction and analysis were carried out in the same manner as in Example 1, except that the flow rate of the fluorine gas blown into the liquid mixture in the vaporizer was 50 sccm and the flow rate of the nitrogen gas was 950 sccm.

[0194] [Example 18]

[0195] The reaction and analysis were performed in the same manner as in Example 1 except that the flow rate of the fluorine gas blown into the liquid mixture in the vaporizer was 500 sccm and the flow rate of the nitrogen gas was 500 sccm.

[0196] [Example 19]

[0197] The reaction and analysis were carried out in the same manner as in Example 1, except that the flow rate of the fluorine gas blown into the liquid mixture in the vaporizer was 990 sccm and the flow rate of the nitrogen gas was 10 sccm. The results are shown in Table 1.

[0198] [Example 20]

[0199] The reaction and analysis were carried out in the same manner as in Example 1 except that the vaporization temperature was set to 9° C., the flow rate of fluorine gas blown into the liquid mixture in the vaporizer was set to 1000 sccm, the flow rate of nitrogen gas was set to 0 sccm, and the flow rate of iodine pentafluoride gas was set to 32 sccm. The results are shown in Table 1.

[0200] [Example 21]

[0201] The reaction and analysis were carried out in the same manner as in Example 1 except that the vaporization temperature was set to 40° C., the flow rate of fluorine gas blown into the liquid mixture in the vaporizer was set to 160 sccm, the flow rate of nitrogen gas was set to 0 sccm, and the flow rate of iodine pentafluoride gas was set to 6 sccm. The results are shown in Table 1.

[0202] [Comparative Example 2]

[0203] The reaction and analysis were carried out in the same manner as in Example 1, except that the content of hydrogen fluoride in the liquid mixture was 0.01 mass % of the content of iodine pentafluoride.

[0204] [Example 22]

[0205] The reaction and analysis were carried out in the same manner as in Example 1, except that the content of hydrogen fluoride in the liquid mixture was 0.1 mass % of the content of iodine pentafluoride.

[0206] [Example 23]

[0207] The reaction and analysis were carried out in the same manner as in Example 1, except that the content of hydrogen fluoride in the liquid mixture was 1 mass % of the content of iodine pentafluoride.

[0208] [Example 24]

[0209] The reaction and analysis were carried out in the same manner as in Example 1, except that the content of hydrogen fluoride in the liquid mixture was 15% by mass of the content of iodine pentafluoride.

[0210] [Example 25]

[0211] The reaction and analysis were carried out in the same manner as in Example 1, except that the content of hydrogen fluoride in the liquid mixture was 20 mass % of the content of iodine pentafluoride.

[0212] [Comparative Example 3]

[0213] The reaction and analysis were carried out in the same manner as in Example 1, except that the content of hydrogen fluoride in the liquid mixture was 25% by mass of the content of iodine pentafluoride.

[0214] From the results of Examples 1 to 8, it can be seen that even when AlF3, NiF2, CoF2, FeF3, CrF3, VF3, ScF3, and α-Al2O3 are used as catalysts, the reaction proceeds smoothly and the yield of iodine heptafluoride is good. In addition, from the results of Comparative Example 1, it can be seen that if no catalyst is used, the yield of iodine heptafluoride decreases.

[0215] From the results of Example 9, it can be seen that when the vaporization temperature is 10°C, the flow rate of iodine pentafluoride decreases, so the yield of iodine heptafluoride is lower than that of Example 1. In addition, from the results of Example 10, it can be seen that when the vaporization temperature is 80°C or more, the flow rate of iodine pentafluoride increases, so the yield of iodine heptafluoride is slightly lower than that of Example 1.

[0216] From the results of Examples 1 and 11, it can be seen that if the reaction temperature is below 200°C, the yield of iodine heptafluoride is slightly reduced. In addition, from the results of Examples 1 and 12, it can be seen that if the reaction temperature is above 380°C, the yield of iodine heptafluoride is slightly reduced. It is believed that the reason is that the reverse reaction of the chemical reaction formula (1) occurs due to the high reaction temperature.

[0217] From the results of Examples 13 to 16, it is believed that the yield of iodine heptafluoride increases when the reaction time is increased. However, when the reaction time is 100 seconds or longer, the degree of improvement in the yield decreases, and thus the productivity decreases.

[0218] From the results of Example 1, Example 17, and Example 18, it can be seen that if the ratio [F2] / [IF5] of the molar amount of fluorine gas [F2] in the raw material mixed gas to the molar amount of iodine pentafluoride [IF5] is 1 or less, the yield of iodine heptafluoride decreases. In addition, from the results of Example 19 and Example 20, it can be seen that if the ratio [F2] / [IF5] of the molar amount of fluorine gas [F2] in the raw material mixed gas to the molar amount of iodine pentafluoride [IF5] is 30 or more, the amount of fluorine gas becomes excessive, so the yield of iodine heptafluoride decreases. Furthermore, in Example 21, although there is no diluent gas, it is confirmed that the yield of iodine heptafluoride is good by gasifying iodine pentafluoride by heating the vaporizer and blowing fluorine gas.

[0219] From the results of Examples 22 and 23 and Comparative Example 2, it can be seen that when the content of hydrogen fluoride in the liquid mixture is reduced to less than 0.1% by mass of the content of iodine pentafluoride, the yield of iodine heptafluoride decreases. The reason for this is believed to be that the catalyst activation by hydrogen fluoride does not occur sufficiently because the concentration of hydrogen fluoride in the liquid mixture is low.

[0220] The results of Examples 24 and 25 and Comparative Example 3 show that the yield of iodine heptafluoride decreases when the content of hydrogen fluoride in the liquid mixture is increased to more than 20% by mass of the content of iodine pentafluoride. The reason for this is believed to be that the catalyst corrodes due to the high concentration of hydrogen fluoride in the liquid mixture.

[0221] Description of Reference Numerals

[0222] 1…Fluorine gas supply device

[0223] 2…Hydrogen fluoride supply device

[0224] 3…Dilution gas supply device

[0225] 4, 5, 6…Mass flow controller

[0226] 10…Iodine pentafluoride

[0227] 11…Carburettor

[0228] 12…Heating device

[0229] 20…reactor

[0230] 21… Pressure gauge

[0231] 22…Pressure regulating valve

[0232] 30…Fourier transform infrared spectrophotometer

[0233] 31…Cooling capture container

[0234] 32…Cooling device

[0235] 33…Thermometer

Claims

1. A method for producing iodine heptafluoride, comprising a preparation step, a gasification step and a reaction step. In the preparation step, a liquid mixture is prepared, the liquid mixture contains iodine pentafluoride and hydrogen fluoride, and the content of the hydrogen fluoride is 0.1% by mass or more and 20% by mass or less of the content of the iodine pentafluoride, In the gasification step, fluorine gas is mixed into the liquid mixture to gasify the liquid mixture, thereby obtaining a raw material mixed gas containing iodine pentafluoride gas, hydrogen fluoride gas and fluorine gas. In the reaction step, the raw material mixed gas is reacted in the presence of a catalyst to generate iodine heptafluoride.

2. The method for producing iodine heptafluoride according to claim 1, wherein the preparation step is a step of mixing hydrogen fluoride and liquid iodine pentafluoride to obtain the liquid mixture.

3. The method for producing iodine heptafluoride according to claim 1 or 2, wherein the gasification step is a step of gasifying the liquid mixture by blowing fluorine gas into the liquid mixture to obtain the raw material mixed gas.

4. The method for producing iodine heptafluoride according to claim 1 or 2, wherein the gasification step is a step of gasifying the liquid mixture by blowing fluorine gas and a diluent gas into the liquid mixture to obtain a raw material mixed gas containing iodine pentafluoride gas, hydrogen fluoride gas, fluorine gas and the diluent gas, and the diluent gas is at least one of nitrogen, argon and helium.

5. The method for producing iodine heptafluoride according to claim 1 or 2, wherein the catalyst contains at least one metal belonging to the third period element or the fourth period element of the periodic table and belonging to any one of the third group elements to the thirteenth group elements. 6 . The method for producing iodine heptafluoride according to claim 1 , wherein the vaporization step is a step of vaporizing the liquid mixture by mixing fluorine gas with the liquid mixture at a temperature of 10° C. to 80° C.

7. The method for producing iodine heptafluoride according to claim 1 or 2, wherein a ratio [F2] / [IF5] of a molar amount of the fluorine gas [F2] to a molar amount of iodine pentafluoride [IF5] in the raw material mixed gas generated in the gasification step is greater than or equal to 1.0 and less than or equal to 30. 8 . The method for producing iodine heptafluoride according to claim 1 , wherein the reaction temperature in the reaction step is 150° C. or higher and 380° C. or lower. 9 . The method for producing iodine heptafluoride according to claim 1 , wherein the reaction time in the reaction step is 10 seconds to 100 seconds.

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