Production method of hydrogen iodide gas

Abstract

To provide a method capable of industrially advantageously producing high-purity hydrogen iodide with a simple device and without fear of device damage etc.SOLUTION: A production method of hydrogen iodide comprises adding solid iodine to a liquid containing a hydrogenated product of naphthalene while circulating an inert gas through a discharge part, using a vibrating feeder having a hopper and the discharge part that discharges a predetermined amount of solid iodine, the discharge part having an inlet and an outlet for the inert gas.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a method for producing hydrogen iodide. Specifically, the present invention relates to an industrially advantageous method for producing high-purity hydrogen iodide.

Background Art

[0002] Hydrogen iodide is useful for various applications such as a synthetic raw material for various iodides, a pharmaceutical intermediate, and a reducing agent. Among them, high-purity hydrogen iodide gas is used as a high-performance etching agent in the semiconductor field, particularly for the dry etching of ITO. As a method for producing high-purity hydrogen iodide, for example, an industrially suitable apparatus (see Patent Document 1) for producing hydrogen iodide, or a method in which all of iodine is previously dissolved in a part of a hydrogen adduct of naphthalene, and this solution is reacted while continuously or intermittently adding it to the rest of the hydrogen adduct of naphthalene, and then contacting it with zeolite (see Patent Documents 2 to 3) and the like have been proposed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] From an industrial perspective, the method of Patent Document 1 is advantageous over the methods of Patent Document 2 or Patent Document 3 in which iodine is pre-dissolved in a part of the hydrogenated product of naphthalene and then added. Patent Document 1 specifically discloses a rotary valve as a device for quantitatively adding solid iodine from the viewpoint of safely adding a solid in a controlled amount in a good working environment to a reaction system in which a corrosive gas is generated. Here, in order to prevent corrosion of the base material such as SUS by iodine, it is necessary to use a material such as SUS lined with PVC resin for the rotary valve. However, since the rotary valve has a structure in which the rotor (valve body) rotates in the casing, it is excellent in terms of the continuous dischargeability of solid iodine. However, since solid iodine is likely to get caught in the clearance provided between the rotor and the casing, the lining at that location is likely to be damaged, and problems such as damage and wear of the rotary valve are likely to occur, and the device life is short. In addition, when the rotary valve is damaged, it is necessary to stop and repair the entire manufacturing facility, the production efficiency of hydrogen iodide is poor, and considering the repair cost of the facility, etc., there are still problems in the process and room for improvement. An object of the present invention is to provide an industrially advantageous method for producing hydrogen iodide with few troubles in devices and the like and that can be carried out by simple operation. As a result of intensive research, the present inventors have found that the above problems can be solved by adding solid iodine to a liquid containing a naphthalene hydride by a specific configuration using a vibrating feeder, and have completed the present invention.

Means for Solving the Problems

[0005] The present invention has the following aspects. [1] A method for producing hydrogen iodide, comprising a hopper and a discharge part that discharges a predetermined amount of solid iodine, and using a vibrating feeder in which the discharge part has an inlet for an inert gas, and adding solid iodine to a liquid containing a hydrogenated product of naphthalene while flowing an inert gas through the discharge part. [2] At least two valves, a first valve and a second valve, are provided in series, and there is a space for holding solid iodine between the two valves to quantitatively add solid iodine to the reactor, and an inert gas inlet and a degassing port for depressurizing the space between the first valve and the second valve are provided between the first valve and the second valve. A liquid containing a hydride of naphthalene is charged into the reactor having a solid material charging device, and solid iodine is added to the space of the solid material charging device while flowing an inert gas through the discharge portion using the vibration feeder. The method for producing hydrogen iodide according to [1]. [3] Controlling the first valve and the second valve of the solid material charging device to add solid iodine to the liquid containing a hydride of naphthalene within a certain period of time. The method for producing hydrogen iodide according to [2]. [4] A process for cooling hydrogen iodide gas generated by adding solid iodine to a liquid containing a hydride of naphthalene to 0°C to -30°C and separating the resulting condensate or solidified product from the hydrogen iodide gas. The method for producing hydrogen iodide according to any one of [1] to [3]. [5] A process for bringing the generated hydrogen iodide gas into contact with zeolite and activated carbon. The method for producing hydrogen iodide according to any one of [1] to [4]. [6] At least one of the zeolite and the activated carbon is pretreated by contacting with hydrogen iodide gas in advance. The method for producing hydrogen iodide according to [5]. [7] Maintaining the temperature of the liquid containing a hydride of naphthalene at 120 to 210°C to add the solid iodine, and after the addition is completed, raising the temperature of the mixture to the temperature at the time of addition +5 to +30°C to further perform aging. The method for producing hydrogen iodide according to any one of [1] to [6]. [8] Controlling the naphthalene content in the residue after the reaction to 30% by mass or less. The method for producing hydrogen iodide according to [7]. [Advantages of the Invention]

[0006] According to the present invention, hydrogen iodide can be industrially advantageously produced with high purity. [Brief Description of the Drawings]

[0007]

Figure 1

Embodiments for Carrying Out the Invention

[0008] The present invention relates to a method for producing hydrogen iodide (hereinafter referred to as "this production method") in which a hopper and a discharge part for discharging a predetermined amount of solid iodine are provided, and while flowing an inert gas through the discharge part using a vibrating feeder having an inert gas inlet, solid iodine is added to a liquid containing a hydride of naphthalene. According to this production method, high-purity hydrogen iodide can be industrially advantageously produced with a simple apparatus and without the risk of apparatus damage or the like.

[0009] Examples of the hydride of naphthalene used in this production method include dihydronaphthalene (1,2-dihydronaphthalene, 1,4-dihydronaphthalene) or tetrahydronaphthalene (tetralin, or also referred to as 1,2,3,4-tetrahydronaphthalene) in which two or four hydrogen atoms are added to naphthalene. These may be used alone or in combination of two or more. Among them, tetrahydronaphthalene is preferable from the viewpoints of reactivity, ease of reaction control, and easy obtainment of high-purity hydrogen iodide in good yield. Since tetrahydronaphthalene is a liquid at 25°C and in the suitable temperature range (120 to 210°C) described later for carrying out this production method, it can be handled as a liquid containing a hydride of naphthalene by itself without adding a solvent or the like. The amount of the hydride of naphthalene used is preferably in the range of 0.1 to 2 molar times, more preferably in the range of 0.14 to 1.4 molar times, relative to the iodine to be reacted, from the viewpoints of productivity when carrying out this production method and ease of handling the residue after the reaction described later. When the amount of the hydride of naphthalene used is within the above range, it becomes easy to control the naphthalene content in the reaction solution after the reaction, that is, the residue, to 30% by mass or less, which is preferable.

[0010] There is no particular limitation on the shape of the solid iodine used in this manufacturing method, and powders, granules, flakes, etc. can be used. Among them, solid iodine in the form of flakes or granules with an average particle size of 1 to 5 mm, preferably 2 to 3 mm, is preferred from the viewpoint of excellent fluidity in the vibrating feeder and the solid material charging device, and being easily added quantitatively to the reactor.

[0011] This manufacturing method is preferably carried out in an inert gas atmosphere. Examples of the inert gas include nitrogen, helium, argon, etc. Among them, nitrogen or helium is preferred from the viewpoint of easily obtaining inexpensive and high-purity hydrogen iodide gas.

[0012] In this manufacturing method, a vibrating feeder is used as the device for the supply section that supplies solid iodine. By means of the vibrating feeder, solid iodine can be supplied to the solid material charging device described later while controlling the input amount and input speed. The vibrating feeder includes a hopper that supplies solid iodine and a discharge section that discharges a predetermined amount of solid iodine to the solid material charging device. It is extremely preferable that such a hopper has a cover for preventing solid iodine from coming into contact with air. There is no particular limitation on the vibration generating means in the vibrating feeder, and examples include electromagnetic means and means by the rotation of an unbalanced weight. Since there are no parts in the vibrating feeder where granular solid iodine gets caught and mechanically wears, there is no damage to the device due to the solid iodine getting caught when using a rotary valve, and frequent maintenance is not required. Also, the supply of solid iodine can be carried out gently and quantitatively.

[0013] The connection part between the discharge section of the vibrating feeder and the solid material charging device that supplies solid iodine to the reactor is preferably composed of a flexible material for vibration. Such a connection part is a part that constitutes a part of the discharge section of the vibrating feeder and is provided with an inert gas introduction section, and an inert gas is circulated and sealed during the supply of solid iodine. In this specification, the "discharge section" of the vibrating feeder is used in the meaning including the discharge section of the vibrating feeder and the connection part between the discharge section and the solid material charging device. Examples of the inert gas include nitrogen, helium, argon, etc. mentioned above. There is no particular limitation on the flow rate of the inert gas in the discharge part of the vibrating feeder (the connection part between the discharge part of the vibrating feeder and the solid material charging device) when supplying solid iodine, but usually, a range of 0.1 to 4 L / min is preferable. When supplying solid iodine, by sealing the discharge part of the vibrating feeder with an inert gas, preferably with the inside of the discharge part being slightly positively pressurized, the entire solid iodine supply part can be made into an inert gas atmosphere, and leakage of hydrogen iodide gas from the reactor can be prevented.

[0014] The solid material charging device for supplying solid iodine to the reactor, which is connected to the discharge part of the vibrating feeder, is equipped with at least two valves, a first valve and a second valve, in series, has a space part for holding solid iodine between both valves and quantitatively adding solid iodine to the reactor, and is provided with an inert gas inlet and a degassing port for depressurizing the space between the first valve and the second valve between the first valve and the second valve. In this production method, a reactor having such a solid material charging device is loaded with a liquid containing a hydride of naphthalene, and while flowing an inert gas through the discharge part (the connection part between the discharge part of the vibrating feeder and the solid material charging device) using a vibrating feeder, solid iodine is added to the space part of the solid material charging device.

[0015] An example of the reaction device for carrying out this production method is shown in FIG. 1. The vibrating feeder 2 equipped with the hopper 1 sends solid iodine quantitatively to the connection part 3 by vibration. The connection part 3 corresponds to the discharge part of the vibrating feeder, is equipped with an inert gas introduction part 3a, and seals by flowing an inert gas when supplying solid iodine. The inert gas flowing through the connection part 3 is discharged through the exhaust line 1a connected to the upper part of the hopper 1 in FIG. 1, so that the entire solid iodine supply part is made into an inert gas atmosphere. Note that the inert gas flowing through the connection part 3 may be discharged by separately providing a discharge part (not shown) in the connection part 3.

[0016] The valve 4 (first valve) of the solid substance charging device opens for a certain period of time, sends solid iodine to the space part 7, and then closes. At this time, since hydrogen iodide gas is generated in the reactor and it is in a positive pressure state, before opening the valve 8 (second valve) of the solid substance charging device, the valve 12 (inert gas inlet) is opened, and inert gas is introduced into the inside of the space part 7 until the pressure inside the space part 7 becomes higher than the internal pressure of the reaction system, and then the valve 12 is closed. From the viewpoint of preventing the intrusion of hydrogen iodide gas into the space part 7 and further into the connection part 3, and not affecting the pressure fluctuation inside the reaction system, it is preferable that the internal pressure of the space part 7 is 0.001 to 10 MPa higher than the internal pressure of the reaction system, and it is preferably adjusted to be 0.01 to 0.1 MPa higher. Next, the valve 8 is opened, solid iodine is added to the reactor, and then it is closed. At this time, as described above, since the internal pressure of the space part 7 is higher than the internal pressure of the reaction system, the hydrogen iodide gas generated in the reaction system does not penetrate into the inside of the space part 7. At this time, since the pressure corresponding to the internal pressure of the reaction system remains in the internal pressure of the space part 7, the valve 13 (degassing port) is opened and then closed to release this pressure. The valve 4 opens and closes again, and the above-mentioned operation is repeated. The valves 4, 8, 12, and 13 are solenoid valves, and a series of operations can be automatically performed by the valve opening and closing operations by the solenoid valve timer.

[0017] Here, at least two of the first valve and the second valve in the solid substance charging device are provided for controlling the addition amount of solid iodine. That is, by controlling the addition amount by the vibrating feeder and controlling at least the first valve and the second valve in the solid substance charging device, solid iodine can be quantitatively added to the liquid containing naphthalene hydride, and the generation reaction of hydrogen iodide gas can proceed smoothly without causing a runaway reaction.

[0018] In this manufacturing method, since the inside of the reactor becomes a positive pressure during the reaction, in order to prevent the leakage of hydrogen iodide gas from the solid iodine inlet, the solid iodine inlet 10 is also sealed with an inert gas. The valves that are in direct contact with the reactor and the reaction system are preferably made of corrosion-resistant materials such as resin lining, glass lining, and ceramics that can withstand contact with iodine and hydrogen iodide gas.

[0019] In this manufacturing method, solid iodine is added to the heated hydride of naphthalene to produce hydrogen iodide. In this manufacturing method, a liquid containing a hydride of naphthalene (for example, tetralin) is first charged into a reactor, and then, by controlling the vibration of a vibrating feeder and the first valve and the second valve of a solid material charging device connected to the vibrating feeder, solid iodine can be added to the liquid containing the hydride of naphthalene within a certain period of time. Therefore, the charging amount of the hydride of naphthalene can be changed according to the capacity of the reactor, the volumetric efficiency of the reactor can be increased, and the productivity is excellent.

[0020] This manufacturing method can be carried out either under atmospheric pressure or under pressure, and it is preferably carried out near atmospheric pressure from the viewpoint of easy operation. When the reaction is carried out under atmospheric pressure, the reaction temperature is preferably in the range of 120°C or higher and within the boiling point of the hydride of naphthalene (around 210°C under atmospheric pressure) from the viewpoints of allowing the hydrogen iodide gas generation reaction to proceed industrially advantageously and suppressing the evaporation of organic substances such as the hydride of naphthalene when hydrogen iodide gas is generated. That is, the reaction temperature is preferably in the range of 120°C to 210°C, and more preferably in the range of 150°C to 180°C.

[0021] In this manufacturing method, the addition rate of solid iodine to the hydride of naphthalene may vary depending on the amount of the hydride of naphthalene relative to solid iodine, the reaction temperature, the production amount, the shape of the reaction vessel, etc., and the heating capacity of the reactor and the cooling capacity of a hydrogen iodide gas holder described later are also matters to be considered. Usually, from the viewpoint of easily controlling the hydrogen iodide gas generation reaction, the addition rate of solid iodine is preferably in the range of 0.005 to 1.0 mol per hour as the molar amount of solid iodine relative to the hydride of naphthalene in the reactor, and more preferably in the range of 0.01 to 0.1 mol.

[0022] In this manufacturing method, the temperature of the liquid containing the hydride of naphthalene is preferably maintained at 120°C to 210°C described above, and solid iodine is added. After the addition is completed, it is preferable to raise the temperature of the mixture to the temperature during addition +5°C to +30°C and further perform aging. Such aging is not merely to simply complete the hydrogen iodide gas generation reaction in this manufacturing method, but to control the progress of the reaction so that naphthalene contained as a by-product does not precipitate and solidify when the reaction solution after the reaction, that is, the residue, is cooled, and to increase the production amount of hydrogen iodide gas. The aging time is usually preferably in the range of 10 minutes to 120 minutes, and more preferably in the range of 15 minutes to 90 minutes.

[0023] Also, from such a perspective, in this manufacturing method, it is preferable to control the naphthalene content in the reaction solution after the reaction, that is, the residue, to 30% by mass or less, and more preferably to 26% by mass or less. If the naphthalene content is within the above range, the entire residue will not solidify even when cooled, making it easy to handle and facilitating subsequent processes such as post-treatment. If the hydride of naphthalene is used in a sufficient excess relative to solid iodine to carry out the hydrogen iodide gas generation reaction, a state where naphthalene does not precipitate can be formed even in the residue after the reaction. However, in that case, it will lead to a decrease in the production efficiency of hydrogen iodide gas with respect to the reactor volume and an increase in the manufacturing cost of hydrogen iodide gas due to an increase in the usage amount of the hydride of naphthalene. Therefore, this manufacturing method is industrially advantageous.

[0024] In this manufacturing method, it is preferably further included a step of cooling the hydrogen iodide gas generated by adding solid iodine to the liquid containing the hydride of naphthalene to 0°C to -30°C and separating the resulting condensate or solidified product from the hydrogen iodide gas. The cooling temperature is more preferably in the range of -20°C to -30°C. With a cooling temperature within such a range, moisture that may be contained in the generated hydrogen iodide gas and organic substances such as the hydride of naphthalene that may evaporate from the reaction solution can be separated and removed.

[0025] This manufacturing method preferably includes a step of bringing the generated hydrogen iodide gas into contact with zeolite and activated carbon from the viewpoint of easily obtaining higher-purity hydrogen iodide. The step of bringing it into contact with zeolite and activated carbon is more preferably carried out after the step of cooling the hydrogen iodide gas generated by the reaction to 0°C to -30°C and separating the resulting condensate or solidified product from the hydrogen iodide gas as described above.

[0026] Examples of zeolite include type A and mordenite type. The shape of the zeolite is not limited, and any of pellets, powders, spheres, etc. can be used. Commercially available products may be used as the zeolite, for example, molecular sieves (trade name) 3A, 4A, 5A, AW-300, etc. Examples of activated carbon include various activated carbons obtained from plant-based materials such as coconut shells and wood; mineral-based materials such as peat, lignite, coke, and coal pitch; synthetic resin-based materials such as phenolic resins and acrylic resins; natural fiber materials such as cellulose; etc. Commercially available products may be used as the activated carbon, for example, "4GS-S", "4G-2S", "2GS" (all trade names), etc. In this manufacturing method, zeolite and activated carbon are preferably heat-treated in an inert gas atmosphere such as nitrogen or helium in the range of 200 to 400°C, preferably under reduced pressure conditions, to be pre-activated in advance, and then handled in an inert gas atmosphere to avoid contact with the atmosphere. The heat treatment is preferably carried out at a temperature of 200 to 400°C for 30 minutes to 10 hours while filling zeolite and activated carbon in a tower or column and flowing an inert gas. Note that zeolite and activated carbon may be filled in independent towers or columns and connected for use, or both may be mixed and filled in a single tower or column for use.

[0027] Also, in this manufacturing method, it is preferable that at least one of zeolite and activated carbon is pretreated by being brought into contact with hydrogen iodide gas in advance. The pretreatment of contacting with hydrogen iodide in advance is preferably carried out on at least one of the above-mentioned heat-treated zeolite and activated carbon, and more preferably carried out on both of them. By performing such pretreatment, impurities such as sulfur content contained in the zeolite and activated carbon can be removed. Therefore, when hydrogen iodide generated by the reaction of iodine and naphthalene hydride is passed through, impurities such as water and organic substances can be removed more effectively, and high-purity hydrogen iodide can be easily obtained. The pretreatment of zeolite and activated carbon is carried out under the pressure of atmospheric pressure to 20 MPa and the temperature condition of 50 to 500 °C (preferably 80 to 200 °C), and the space velocity (SV) of the mixed gas of inert gas and hydrogen iodide is 300 to 1500 h -1 in the range, and it is preferable to contact hydrogen iodide in an amount of 10 to 60% by mass with respect to the zeolite and activated carbon to be pretreated. Further, it is preferable to fill the above-mentioned zeolite and activated carbon in a tower or column, and after performing the above-mentioned heat treatment, subsequently perform a pretreatment of contacting with hydrogen iodide gas.

[0028] The hydrogen iodide gas generated by the reaction is cooled to 0 °C to -30 °C, and the hydrogen iodide gas from which the generated condensate or solidified product is separated is preferably contacted with zeolite and activated carbon which have both been subjected to heat treatment and pretreatment with hydrogen iodide gas, so that impurities such as moisture and organic substances can be further removed. The means of contacting the hydrogen iodide gas generated by the reaction with zeolite and activated carbon is, for example, in a tower or column filled with zeolite and activated carbon, under the pressure of atmospheric pressure to 20 MPa and the temperature condition of -30 to 100 °C (preferably -30 to 50 °C), and the space velocity (SV) of hydrogen iodide gas is 300 to 1500 h -1 in the range is preferably carried out.

[0029] In addition, the used zeolite and activated carbon can be regenerated by known means such as a heating method, a pressure regeneration method, a purge gas stripping method, and a displacement (substitution) method.

[0030] The hydrogen iodide gas after being brought into contact with zeolite and activated carbon can be led to and collected in a hydrogen iodide gas holder pre-cooled to a temperature below the boiling point of the hydrogen iodide gas. The cooling temperature of the hydrogen iodide holder is preferably in the range of -40 to -60°C. The collected hydrogen iodide gas already has the purity required as a high-performance etching agent in the semiconductor field. That is, in this production method, high-purity hydrogen iodide gas, for example, with a water content of 1 ppm or less and an organic content of 0.5 ppm or less, can be obtained.

[0031] When filling the hydrogen iodide holder into a small pressure vessel such as a cylinder, a step of connecting the hydrogen iodide holder and a reflux device as necessary, adjusting the temperature of the hydrogen iodide holder to cause reflux, and then transferring it to the small pressure vessel may be performed. The temperature of the hydrogen iodide holder during reflux is preferably maintained near the boiling point of hydrogen iodide (-35.4°C), for example, in the vicinity of -37°C to -34°C. There is no particular limitation on the reflux time of the hydrogen iodide gas, but from the viewpoint of easily obtaining higher-purity hydrogen iodide, usually, the range of 10 minutes to 10 hours is preferable. After performing reflux, when subsequently filling the hydrogen iodide gas into a small pressure vessel, the temperature of the hydrogen iodide holder may be further increased within a range where the transfer operation of the hydrogen iodide gas can be smoothly performed. By such a reflux operation, the purity of hydrogen iodide can be further increased. The production method of the present invention includes a step of cooling the hydrogen iodide gas generated by the reaction to 0°C to -30°C and separating the resulting condensate or solidified product from the hydrogen iodide gas, a step of bringing it into contact with the above-described zeolite and activated carbon, and in addition to these steps, a step of leading and collecting it in a hydrogen iodide gas holder pre-cooled to a temperature below the boiling point of the hydrogen iodide gas, and a step of refluxing the collected hydrogen iodide gas may be further included, and it is more preferable to include such a reflux step.

[0032] As described above, the production method of hydrogen iodide of the present invention has been described, but the present invention is not limited to the configuration of the above-described embodiments. For example, the production method of hydrogen iodide of the present invention may have any other arbitrary configuration added in the configuration of the above-described embodiments, or may be replaced with any configuration that produces the same effect.

Example

[0033] The present invention will be specifically described below with reference to examples. However, the present invention is not limited only to the following examples.

[0034] Example 1 (1) Hydrogen iodide was produced using the reactor shown in Fig. 1. Tetralin (92 kg, 0.696 kmol) was charged into a 100 L glass-lined reactor with its interior replaced by nitrogen. After flowing helium into the reactor to replace the interior with helium, the internal temperature was raised to 175 °C. (2) 25 kg of solid iodine was placed in hopper 1, and the vibrating feeder 2 was started to add the solid iodine to the solid material charging device via the connection part 3 which is the discharge part. At this time, nitrogen was supplied from the inert gas introduction part 3a to the connection part 3, and nitrogen was circulated by discharging it from the exhaust line 1a connected to the upper part of hopper 1 to seal the connection part 3. Thereafter, the opening and closing of the valve of the solid material charging device were performed electromagnetically. That is, the solenoid valve of valve 4 opened for 5 seconds, sent the solid iodine to the space part 7 and then closed. Since hydrogen iodide gas was generated in the reactor, it was in a positive pressure state of 0.002 - 0.006 MPa. Next, valve 12 opened for 10 seconds to introduce helium into the space part 7. After closing valve 12, the ceramic valve 8 opened for 2 seconds to add the solid iodine into the tetralin in the reactor. After valve 8 closed, valve 13 opened for 5 seconds and then closed to release the remaining pressure inside the space part 7. A series of valve opening and closing operations, that is, valve 4 opens for 5 seconds → valve 4 closes → wait for 10 seconds → valve 12 opens for 10 seconds → valve 12 closes → wait for 5 seconds → valve 8 opens for 2 seconds → valve 8 closes → wait for 8 seconds → valve 13 opens for 5 seconds → valve 13 closes → wait for 15 seconds (→ valve 4 opens again) were automatically repeated electromagnetically with a timer, and the solid iodine in hopper 1 was added via the vibrating feeder through the solid material charging device over a total of 3.3 hours. Note that valve 4, space part 7, valve 12, and valve 13 were all made of PVC (polyvinyl chloride).

[0035] (3) After the addition of solid iodine was completed, the reaction mixture was stirred at an internal temperature of 175°C for 15 minutes, and then the temperature was raised to 200°C and aged for 1 hour. The generated hydrogen iodide gas was cooled to -25°C to remove moisture (impurities), and then further purified by contacting with zeolite and activated carbon packed in a tower, and then collected by guiding it to a holder maintained at -36°C or lower. Note that prior to contacting with the hydrogen iodide gas generated in the reaction, both the zeolite and the activated carbon were first heat-treated at 230°C for 6 hours under a nitrogen stream after being packed in the tower, and then pretreated at 140°C for 5 hours under a hydrogen iodide gas stream before being used. After the completion of the series of reactions, the concentration of hydrogen iodide gas in the gas discharged from valve 13 was measured, and as a result, it was not detected. That is, the hydrogen iodide gas generated in the reaction did not leak at all into the space portion 7 of the solid material charging device, the connection portion 3, or the hopper 1 provided in the vibratory feeder, and the device could be stably operated without any device troubles. (4) After the completion of the reaction in (3) above, the internal temperature of the mixture was set to 175°C again, 25 kg of solid iodine was put into hopper 1, the vibratory feeder was started, and the operations in (2) and (3) above were repeated 2 more times. As a result, hydrogen iodide gas was obtained with an isolation yield of 90%. Regarding the obtained hydrogen iodide, when gas chromatography analysis was performed, the nitrogen content was 2 ppm or less, and the oxygen content was 1 ppm or less. Also, the water content based on the water content analysis using a dew point meter was 1 ppm or less, the metal impurities based on ICP analysis were below the detection limit, and the purity of the hydrogen iodide gas was 99.999% or more. (6) When the procedures in (1) to (4) above were repeated, no troubles such as device failures or damages occurred over 10 years or more, and hydrogen iodide could be produced with high production efficiency by performing normal device maintenance.

[0036] Comparative Example 1 Hydrogen iodide was produced in the same manner as in Example 1, except that a reaction device equipped with a quantitative addition device for solid iodine equipped with a rotary valve, which is disclosed in Patent Document 1, was used instead of the reaction device shown in Fig. 1. The isolated yield and purity of the obtained hydrogen iodide gas were the same as those in Example 1. However, damage such as lining material peeling and corrosion of the base material was likely to occur due to solid iodine getting caught in the clearance part of the rotary valve. Therefore, production stoppage troubles frequently occurred, and the production efficiency of hydrogen iodide gas was poor. In addition, the rotary valve needed to be replaced at least once a year or more, and in addition to normal equipment maintenance, equipment repair costs and the like were required. Therefore, it can be seen that Example 1, which is the production method of the present invention, is industrially advantageous over the production method of Comparative Example 1 and is excellent in economic efficiency.

Industrial Applicability

[0037] The hydrogen iodide gas obtained by the production method of the present invention has high purity and is useful, for example, for the dry etching of ITO.

Explanation of Symbols

[0038] 1 Hopper 1a Exhaust line 2 Vibrating feeder 3 Connection part (discharge part) 3a Inert gas introduction part 4, 8, 12, 13, 14 Solenoid valve (valve) 5, 7, 9 Space part 6 Observation window 10 Solid iodine inlet 11 Pipe stand 20 Vibration generating means 30 Stirrer 40 Reactor

Claims

1. A method for producing hydrogen iodide, comprising a hopper and a discharge section for discharging a predetermined amount of solid iodine, and using a vibrating feeder having an inert gas inlet in the discharge section to add solid iodine to a liquid containing a hydride of naphthalene while flowing inert gas through the discharge section.

2. At least two valves, a first valve and a second valve, are provided in series, and there is a space for holding solid iodine between the two valves to quantitatively add solid iodine to the reactor, and an inert gas inlet and a degassing port for depressurizing the space between the first valve and the second valve are provided between the first valve and the second valve. A reactor having a solid material charging device is charged with a liquid containing a hydride of naphthalene, and solid iodine is added to the space of the solid material charging device using the vibrating feeder while flowing inert gas through the discharge section. The method for producing hydrogen iodide according to Claim 1.

3. The method for producing hydrogen iodide according to Claim 2, wherein the first valve and the second valve of the solid material charging device are controlled to add solid iodine to a liquid containing a hydride of naphthalene within a certain period of time.

4. The method for producing hydrogen iodide according to Claim 1, comprising a step of cooling hydrogen iodide gas generated by adding solid iodine to a liquid containing a hydride of naphthalene to 0°C to -30°C and separating the resulting condensate or solidified product from the hydrogen iodide gas.

5. The method for producing hydrogen iodide according to Claim 1, comprising a step of bringing the generated hydrogen iodide gas into contact with zeolite and activated carbon.

6. The method for producing hydrogen iodide according to Claim 5, wherein at least one of the zeolite and the activated carbon has been pretreated by contacting with hydrogen iodide gas in advance.

7. The method for producing hydrogen iodide according to Claim 1, wherein the temperature of the liquid containing the hydride of naphthalene is maintained at 120 to 210°C to add the solid iodine, and after the addition is completed, the temperature of the mixture is raised to the temperature at the time of addition +5 to +30°C for further aging.

8. The method for producing hydrogen iodide according to Claim 7, wherein the naphthalene content in the residue after the reaction is controlled to 30% by mass or less.

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