HYDROGEN CHLORIDE MIXTURE, METHOD FOR PRODUCING THE SAME, AND FILLING CONTAINER

Abstract

A method for producing a hydrogen chloride mixture containing hydrogen chloride and water, the method including: a first dehydration step of cooling a hydrogen chloride mixture in which a concentration of water is 1 mol ppm or more, to condense and separate water in the hydrogen chloride mixture; a second dehydration step of bringing a hydrogen chloride mixture obtained in the first dehydration step into contact with a water adsorbent to allow a concentration of water to be less than 0.5 mol ppm; and a filling step of filling a filling container with a hydrogen chloride mixture obtained in the second dehydration step so that at least a part of the hydrogen chloride mixture is liquid, and a concentration of water in a liquid phase at a time of completion of the filling is 0.01 mol ppm or more and less than 1 mol ppm.

Claims

1. A method for producing a hydrogen chloride mixture comprising hydrogen chloride and water, the method including: a first dehydration step of cooling a hydrogen chloride mixture in which a concentration of water is 1 mol ppm or more, to condense and separate water in the hydrogen chloride mixture; a second dehydration step of bringing a hydrogen chloride mixture obtained in the first dehydration step into contact with a water adsorbent to allow a concentration of water to be less than 0.5 mol ppm; and a filling step of filling a filling container with a hydrogen chloride mixture obtained in the second dehydration step so that at least a part of the hydrogen chloride mixture is liquid, and a concentration of water in a liquid phase at a time of completion of the filling is 0.01 mol ppm or more and less than 1 mol ppm.

2. The method for producing a hydrogen chloride mixture according to claim 1, wherein at least a part of the filling container comprises stainless steel.

3. The method for producing a hydrogen chloride mixture according to claim 1, wherein a ratio V/G.sub.1 of an internal volume V (unit: L) of the filling container to an amount G.sub.1 (unit: kg) of the hydrogen chloride mixture filled into the filling container in the filling step is 1.67 or more and 11.8 or less.

4. The method for producing a hydrogen chloride mixture according to claim 2, wherein a ratio V/G.sub.1 of an internal volume V (unit: L) of the filling container to an amount G.sub.1 (unit: kg) of the hydrogen chloride mixture filled into the filling container in the filling step is 1.67 or more and 11.8 or less.

Description

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] In the present invention, the concentration of water in hydrogen chloride is defined to suppress the corrosion of a metal due to hydrogen chloride. It has been commonly known that the corrosion of a metal due to hydrogen chloride is strongly influenced by the concentration of water. However, the influence of the concentration of water at a ppm level has been unclear.

[0030] As a result of intensively examining the corrosion of a metal due to a slight amount of water in hydrogen chloride, the present inventors surprisingly found that the corrosion of a metal is considerably suppressed when the concentration of water is at a sufficiently low ppm level. The present invention was thus accomplished. One embodiment of the present invention will be described in detail below.

[0031] A hydrogen chloride mixture of the present embodiment contains hydrogen chloride and water. The hydrogen chloride mixture is filled into a filling container so that at least a part of the hydrogen chloride mixture is liquid. The concentration of water in a gas phase is 0.001 mol ppm or more and less than 4.5 mol ppm. The concentration of water in a liquid phase is 0.01 mol ppm or more and less than 1 mol ppm.

[0032] The filling container of the present embodiment is a filling container filled with a hydrogen chloride mixture containing hydrogen chloride and water. The filling container is filled with the hydrogen chloride mixture so that at least a part of the hydrogen chloride mixture is liquid. The concentration of water in a gas phase is 0.001 mol ppm or more and less than 4.5 mol ppm. In addition, the concentration of water in a liquid phase is 0.01 mol ppm or more and less than 1 mol ppm.

[0033] The concentrations of water in the gas phase and the liquid phase are the concentrations of water in the gas phase and the liquid phase between the time of the completion of filling the hydrogen chloride mixture into the filling container and the time of releasing almost all of the hydrogen chloride mixture in the filling container.

[0034] When the concentration of water in the gas phase of a hydrogen chloride mixture in which the gas phase and a liquid phase coexist is less than 0.01 mol ppm, it is difficult to directly measure the concentration of water, and therefore, 1/10 of the concentration of water in the liquid phase is regarded as the concentration of water in the gas phase. This is based on the fact that it is experientially known that the concentration of water in hydrogen chloride in which a liquid phase and a gas phase coexist satisfies concentration of water in gas phase: concentration of water in liquid phase=1:10.

[0035] In such a hydrogen chloride mixture, the concentration of water in a liquid phase is very low at the time of the completion of filling the hydrogen chloride mixture into a filling container. Therefore, even if water is concentrated into a liquid phase side with releasing a hydrogen chloride mixture gas from the filling container, the concentration of water in the liquid phase is kept in the state of being sufficiently low until all of a liquefied hydrogen chloride mixture in the filling container is gasified. Thus, the concentration of water in the hydrogen chloride mixture gas released from the filling container is sufficiently low from the early stage of the releasing to the end stage of the releasing (the stage of gasifying all of the liquefied hydrogen chloride mixture in the filling container). Therefore, the corrosion of a metal due to the hydrogen chloride mixture gas released from the filling container can be considerably suppressed until the end stage of the releasing.

[0036] The concentration of water in the liquid phase is 0.01 mol ppm or more and less than 1 mol ppm, preferably 0.01 mol ppm or more and 0.95 mol ppm or less, more preferably 0.01 mol ppm or more and 0.45 mol ppm or less, and still more preferably 0.01 mol ppm or more and 0.05 mol ppm or less.

[0037] When the concentration of water in the liquid phase is less than 1 mol ppm, the concentration of water in a hydrogen chloride mixture gas released from the filling container is kept at a level at which the corrosion of a metal is suppressed (for example, less than 4.5 mol ppm), until the end stage of the releasing, even if water is concentrated in a liquid phase side with releasing the hydrogen chloride mixture gas from the filling container. It is difficult to confirm the concentration of water lower than 0.01 mol ppm.

[0038] The concentrations of water in the hydrogen chloride mixture in the filling container and the hydrogen chloride mixture gas released from the filling container are low as described above, and the hydrogen chloride mixture and the hydrogen chloride mixture gas hardly corrode a metal. Thus, a metal such as stainless steel can be used in a portion with which the hydrogen chloride mixture in the filling container and the hydrogen chloride mixture gas released from the filling container come in contact. For example, a portion with which a hydrogen chloride mixture in a filling container, a pipe, a production apparatus, a supply apparatus, a conveying apparatus, a reaction apparatus, or the like for a hydrogen chloride mixture comes in contact may include a metal such as stainless steel. The kind of usable stainless steel is not particularly limited. Examples of the kind include SUS316, SUS316L, SUS304, and SUS304L.

[0039] The initial filling amount G.sub.0 (unit: kg) of the hydrogen chloride mixture into the filling container is not particularly limited, and may be set at 70% or more and 100% or less of the upper limit value of a mass calculated according to the internal volume V of the filling container, stipulated in Article 48-4 of the High Pressure Gas Safety Act. In other words, a ratio of V/G.sub.0 of the internal volume V (unit: L) of the filling container to the initial filling amount G.sub.0 (unit: kg) of the hydrogen chloride mixture into the filling container is not particularly limited, but may be set at 1.67 or more and 2.40 or less.

[0040] A case in which the ratio V/G.sub.0 is 1.67 or more (i.e., a case in which the initial filling amount G.sub.0 of the hydrogen chloride mixture into the filling container is 100% or less of the upper limit value of a mass calculated according to the internal volume V of the filling container) is safe because the hydrogen chloride mixture is not excessively filled into the filling container. In contrast, when the ratio V/G.sub.0 is 2.40 or less (i.e., when the initial filling amount G.sub.0 of the hydrogen chloride mixture into the filling container is 70% or more of the upper limit value of a mass calculated according to the internal volume V of the filling container), the efficiency of transporting the hydrogen chloride mixture by the filling container is high because the initial filling amount G.sub.0 of the hydrogen chloride mixture with respect to the internal volume V of the filling container is sufficient.

[0041] A ratio V/G.sub.0 of the internal volume V (unit: L) of the filling container to the initial filling amount G.sub.0 (unit: kg) of the hydrogen chloride mixture into the filling container is more preferably 1.70 or more and 2.13 or less, and still more preferably 1.74 or more and 1.88 or less.

[0042] One embodiment of a method for producing such a hydrogen chloride mixture as described above will now be described. First, water is removed, by two dehydration steps, from a hydrogen chloride mixture gas in which the concentration of water is 1 mol ppm or more, to obtain a hydrogen chloride mixture gas in which the concentration of water is less than 0.5 mol ppm. In the first dehydration step, the hydrogen chloride mixture gas in which the concentration of water is 1 mol ppm or more is cooled to condense and separate water in the hydrogen chloride mixture gas. A hydrogen chloride mixture gas in which the concentration of water is 0.5 mol ppm or more and less than 1 mol ppm is obtained by cooling the hydrogen chloride mixture gas in which the concentration of water is 1 mol ppm or more to, for example, 69 C.

[0043] Subsequently, in the second dehydration step, the hydrogen chloride mixture gas dehydrated in the first dehydration step is brought into contact with a water adsorbent, and further dehydrated to allow the concentration of water to be less than 0.5 mol ppm. When the concentration of water in the hydrogen chloride mixture gas can be set at less than 0.5 mol ppm, the kind of the water adsorbent is not particularly limited, and examples of the kind include zeolite, activated carbon, silica gel, and diphosphorus pentaoxide. The kind of the zeolite is not particularly limited. The ratio between silica and alumina contained in the zeolite, and the diameters of pores in the zeolite are not particularly limited. The zeolite preferably has resistance to hydrogen chloride. Examples of the zeolite include molecular sieve 3A and high-silica zeolite.

[0044] The hydrogen chloride mixture gas in which the concentration of water is set at less than 0.5 mol ppm in the first dehydration step and the second dehydration step is compressed in a filling step, and filled into, for example, a filling container having a capacity of 1 L or more and 2000 L or less. In this case, the hydrogen chloride mixture gas is compressed and filled so that at least a part of the hydrogen chloride mixture gas is liquid, and the concentration of water in a liquid phase at the time of the completion of the filling is 0.01 mol ppm or more and less than 1 mol ppm.

[0045] A method for compressing the hydrogen chloride mixture gas and filling the hydrogen chloride mixture gas into the filling container is not particularly limited. Examples of the method include a method in which the pressure of a hydrogen chloride mixture gas is increased by a compressor to liquefy the hydrogen chloride mixture gas, and a low-boiling point component and a high-boiling point component are removed using a distillation column, followed by storing the resultant in a product tank and by transferring and filling the resultant from the product tank into a filling container.

[0046] The capacity of the filling container can be set at 1 L or more and 2000 L or less, and is preferably 2 L or more and 1800 L or less, and more preferably 3 L or more and 1500 L or less. A case in which the capacity of the filling container is 1 L or more results in excellent efficiency because the amount of usable hydrogen chloride mixture is large. In contrast, when the capacity of the filling container is 2000 L or less, it is easy to produce and transport the filling container.

[0047] When the hydrogen chloride mixture is filled into the filling container, the temperature of the filling container is not particularly limited, and the filling container may be cooled to 90 C. or more and 0 C. or less in advance. When water remains in the filling container, the concentration of water in the filled hydrogen chloride mixture is increased. Therefore, heating treatment under reduced pressure may be performed in advance so that the amount of water remaining in the filling container is 0.1 mol ppm or less.

[0048] Further, a ratio V/G.sub.1 of the internal volume V (unit: L) of the filling container to the amount G.sub.1 (unit: kg) of the hydrogen chloride mixture filled into the filling container in the filling step is not particularly limited, and may be set at 1.67 or more and 11.8 or less. A case in which the ratio V/G.sub.1 is 1.67 or more is safe because the hydrogen chloride mixture is not excessively filled into the filling container. In contrast, when the ratio V/G.sub.1 is 11.8 or less, the hydrogen chloride mixture is liquefied.

[0049] A ratio V/G.sub.1 of the internal volume V (unit: L) of the filling container to the amount G.sub.1 (unit: kg) of the hydrogen chloride mixture filled into the filling container in the filling step is more preferably 1.67 or more and 3.13 or less, and still more preferably 1.67 or more and 2.40 or less.

[0050] A method for measuring the concentration of water in a hydrogen chloride mixture in each step (first dehydration step, second dehydration step, and filling step) of the method for producing a hydrogen chloride mixture of the present embodiment is not particularly limited as long as being able to be a method by which the concentration at a level of around 0.01 mol ppm can be correctly measured. Examples of the method include a method using a mirror cooling dew-point meter, a Fourier transform infrared spectrometer (FT-IR), a phosphorus pentoxide-type moisture meter, or the like, and cavity ring-down spectroscopy (CRDS).

[0051] In the case of a gas phase, the concentration of water in the present invention is measured by cavity ring-down spectroscopy with a sample extracted from a gas phase portion in the filling container. In the case of a liquid phase, the concentration is measured by cavity ring-down spectroscopy, similarly with the case of the gas phase, with a sample extracted from a liquid phase portion in the filling container and then gasified.

[0052] According to the method for producing a hydrogen chloride mixture of the present embodiment, a hydrogen chloride mixture in which the concentration of water is very low, and the corrosion of a metal such as stainless steel hardly occurs can be produced by a simple facility. The hydrogen chloride mixture produced by the method for producing a hydrogen chloride mixture of the present embodiment can be used as an etching gas or a cleaning gas when a semiconductor or a thin-film transistor is produced.

[0053] Particularly in an epitaxial growth process for SiGe (semiconductor), GaN (light-emitting diode or the like), or SiC (power semiconductor), the hydrogen chloride mixture is used not only as a cleaning gas and also as a film formation gas. When an impurity exists in the film formation gas, the impurity remains in a film. Therefore, the hydrogen chloride mixture obtained by the method for producing a hydrogen chloride mixture of the present embodiment is very useful. Further, the hydrogen chloride mixture obtained by the method for producing a hydrogen chloride mixture of the present embodiment can also be used for producing various chemicals such as pharmaceutical products and dye intermediates.

[0054] The present embodiment shows an example of the present invention, and the present invention is not limited to the present embodiment. Various modifications or improvements may be made to the present embodiment, and an embodiment to which such modifications or improvements are made can also be encompassed in the present invention.

EXAMPLES

[0055] Examples and Comparative Examples will be described below to explain the present invention in more detail.

Example 1

[0056] Into a filling container having a capacity of 47 L, 25 kg of a hydrogen chloride mixture containing hydrogen chloride and water was filled so that apart of the hydrogen chloride mixture was liquid. The hydrogen chloride mixture in the filling container was separated into a gas phase and a liquid phase, and the concentration of water in the liquid phase at the time of the completion of the filling was 0.80 mol ppm.

[0057] The gas phase was extracted from the filling container at a release rate of 2 L/min until the amount of the hydrogen chloride mixture remaining in the filling container became 3 kg. In this state, the liquid phase in the filling container disappeared, all of the hydrogen chloride mixture was gasified, and the concentration of water in the hydrogen chloride mixture was 4.0 mol ppm.

[0058] A test piece made of SUS316L, with a rectangular shape (having a width of 10 mm, a length of 50 mm, and a thickness of 1 mm), was prepared, the mass of the test piece was measured, and the test piece was hung with a string made of Teflon (registered trademark) in a pressure-resistant container. The hydrogen chloride mixture gas in which the concentration of water was 4.0 mol ppm was introduced into the pressure-resistant container to achieve an internal pressure of 0.5 MPaG.

[0059] The pressure-resistant container was left standing for five days in the state of being heated to 100 C., and then sufficiently purged with N.sub.2. After confirmation that the concentration of hydrogen chloride was less than 0.1 mol ppm, the pressure-resistant container was opened, and the test piece was taken out. The taken test piece was ultrasonically cleaned with each of ultrapure water and 10% by mass of aqueous nitric acid solution for 10 minutes, the mass of the test piece was then measured, and a corrosion rate was calculated from the change of the mass. As a result, the corrosion rate was 1.0 m/.

Example 2

[0060] The same operation as in Example 1 except that the concentration of water in a liquid phase at the time of the completion of filling into a filling container was 0.40 mol ppm was performed to obtain a hydrogen chloride mixture gas in which the concentration of water was 2.0 mol ppm. The same operation as in Example 1 except that the hydrogen chloride mixture gas was used was performed to measure the corrosion rate of a test piece. The corrosion rate was 0.81 m/.

Example 3

[0061] The same operation as in Example 1 except that the concentration of water in a liquid phase at the time of the completion of filling into a filling container was 0.050 mol ppm was performed to obtain a hydrogen chloride mixture gas in which the concentration of water was 0.25 mol ppm. The same operation as in Example 1 except that the hydrogen chloride mixture gas was used was performed to measure the corrosion rate of a test piece. The corrosion rate was 0.52 m/.

Example 4

[0062] The same operation as in Example 1 except that the concentration of water in a liquid phase at the time of the completion of filling into a filling container was 0.010 mol ppm was performed to obtain a hydrogen chloride mixture gas in which the concentration of water was 0.050 mol ppm. The same operation as in Example 1 except that the hydrogen chloride mixture gas was used was performed to measure the corrosion rate of a test piece. The corrosion rate was 0.44 m/.

Comparative Example 1

[0063] The same operation as in Example 1 except that the concentration of water in a liquid phase at the time of the completion of filling into a filling container was 1.0 mol ppm was performed to obtain a hydrogen chloride mixture gas in which the concentration of water was 5.0 mol ppm. The same operation as in Example 1 except that the hydrogen chloride mixture gas was used was performed to measure the corrosion rate of a test piece. The corrosion rate was 7.4 m/.

Comparative Example 2

[0064] The same operation as in Example 1 except that the concentration of water in a liquid phase at the time of the completion of filling into a filling container was 2.0 mol ppm was performed to obtain a hydrogen chloride mixture gas in which the concentration of water was 10 mol ppm. The same operation as in Example 1 except that the hydrogen chloride mixture gas was used was performed to measure the corrosion rate of a test piece. The corrosion rate was 54 m/.

[0065] The results (see Table 1) reveals that when the concentration of water in a liquid phase at the time of the completion of filling into a filling container is less than 1 mol ppm, the concentration of water in a hydrogen chloride mixture gas released from the filling container is sufficiently low until the end stage of the release (the stage of gasifying all of a liquefied hydrogen chloride mixture in the filling container), and therefore, the corrosion of a metal is considerably suppressed.

TABLE-US-00001 TABLE 1 Example Example Example Example Comparative Comparative 1 2 3 4 Example 1 Example 2 Concentration of water in liquid phase at 0.80 0.40 0.05 0.01 1.0 2.0 time of completion of filling (mol ppm) Concentration (mol ppm) of water in gas 4.0 2.0 0.25 0.05 5.0 10 phase after extraction of gas phase until residual amount becomes 3 kg Corrosion rate (m/y) 1.0 0.81 0.52 0.44 7.4 54

Example 5

[0066] An example of a method for producing a hydrogen chloride mixture in which the concentration of water is less than 1 mol ppm will now be described. A raw hydrogen chloride mixture gas in which the concentration of water was 1000 mol ppm was fed at a flow rate of 320 m.sup.3/h to a cooler condenser, and cooled to 10 C. to condense the water in the raw hydrogen chloride mixture gas and to remove a part of the water in the raw hydrogen chloride mixture gas.

[0067] Further, the raw hydrogen chloride mixture gas from which the part of the water had been removed was fed to a water adsorption tower, brought into contact with a water adsorbent (Molecular Sieve 3A manufactured by UNION SHOWA K.K.) filled in the water adsorption tower, and dehydrated. With regard to the velocities of circulation of the raw hydrogen chloride mixture gas, the linear velocity LV was 10 m/min, and the space velocity SV was 1000/h. The concentration of water in the hydrogen chloride mixture gas at the outlet of the water adsorption tower was 0.34 mol ppm.

[0068] Into a filling container having a capacity of 47 L, 25 kg of the hydrogen chloride mixture gas in which the concentration of water was 0.34 mol ppm was filled, while increasing the pressure of the hydrogen chloride mixture gas by a pump. The concentration of water in a liquefied hydrogen chloride mixture (liquid phase) in the filling container was 0.41 mol ppm.

Comparative Example 3

[0069] A raw hydrogen chloride mixture gas in which the concentration of water was 1000 mol ppm was fed at a flow rate of 320 m.sup.3/h to a cooler condenser, and cooled to 69 C. to condense the water in the raw hydrogen chloride mixture gas and to remove a part of the water in the raw hydrogen chloride mixture gas. The concentration of water in the obtained hydrogen chloride mixture gas was 0.51 mol ppm.

[0070] Into a filling container having a capacity of 47 L, 25 kg of the hydrogen chloride mixture gas in which the concentration of water was 0.51 mol ppm was filled, while increasing the pressure of the hydrogen chloride mixture gas by a pump. The concentration of water in a liquefied hydrogen chloride mixture (liquid phase) in the filling container was 1.0 mol ppm.

[0071] The results reveal that a hydrogen chloride mixture in which the concentration of water is less than 1 mol ppm can be obtained by establishing two-stage dehydration steps of a step of performing cooling to condense water and a step of performing contact with a water adsorbent.