WO2010016116A1 - Process for producing hydrogen gas from mixed gas containing hydrogen halide, hydrogen and silicon halide, process for producing silicon compound with use of the hydrogen gas, and plant for the processes - Google Patents

Abstract

A plant (100) for producing hydrogen gas through separation of hydrogen from a mixed gas containing hydrogen chloride, hydrogen and chlorosilane. The plant (100) comprises a washing column (102) adapted to bring the mixed gas into contact with a hydrochloric acid silica slurry and a hydrochloric acid scrubber (108) adapted to bring the purified gas obtained from the washing column (102) into contact with an aqueous solution of hydrochloric acid.

Description

Method for producing hydrogen gas from hydrogen halide, mixed gas containing hydrogen and silicon halide, method for producing silicon compound using the hydrogen gas, and plant for the method

The present invention relates to a method for producing hydrogen gas from a mixed gas containing hydrogen halide, hydrogen and silicon halide, a method for producing a silicon compound using the hydrogen gas, and a plant for the method.

Silicon is an element that is abundant in the crust after oxygen, and is estimated to account for about 28% of the elements that make up the crust. Metallic silicon has been used as a semiconductor material since the 1960s and has become the most important material in the electronics industry.

Monosilane (SiH ₄ ), monochlorosilane (SiH ₃ Cl), dichlorosilane (SiH ₂ Cl ₂ ), and trichlorosilane (SiHCl ₃ ) are special material gases used for manufacturing such semiconductors, liquid crystal panels, solar cells, and the like. It is. In recent years, demand has been steadily expanding, and growth is expected as a CVD material widely used in the electronics field.

Tetrachlorosilane (silicon tetrachloride: SiCl ₄ ) is a starting material for producing these monosilane, monochlorosilane, dichlorosilane, and trichlorosilane.

As a conventional method for producing tetrachlorosilane, for example, there is one described in Patent Document 1. In this document, chlorine that is diluted 3 to 10 times (volume ratio) with an inert gas and supplied from the bottom of the reactor is reacted with metal silicon in a semi-fluid state (slagging) at a reaction temperature of 450 ° C. to 800 ° C. A method for producing silicon tetrachloride is described.

As a conventional method for producing trichlorosilane, there is, for example, one described in Patent Document 2. In this document, a gas mixture having a molar ratio of SiCl ₄ and H ₂ of 1: 1 to 1: 2 is introduced into a reactor heated to 1200 ° C. over 1200 ° C. and reacted to obtain a thermal equilibrium state. The molar ratio of SiHCl ₃ and HCl, which is an equilibrium mixture, is 1: 1 to 1: 4, and the mixture containing SiCl ₂ and H ₂ is rapidly cooled to 600 ° C. or less within 1 second to carry out the reaction. A process for the production of SiHCl ₃ is described which improves the yield and yield of SiHCl ₃ by freezing.

Examples of conventional production methods for dichlorosilane, monochlorosilane, and monosilane are described in Patent Document 3, for example. In this document, at least one silane compound selected from monosilane, monochlorosilane, dichlorosilane or the like having a low boiling point due to a distillation effect while supplying raw material silicon hydride chloride to a reaction tower and causing a disproportionation reaction in the tower Is obtained from the top of the reaction tower, while the catalyst mixed liquid containing silicon tetrachloride and trichlorosilane is withdrawn from the bottom of the tower, and then the silane compound and the catalyst liquid are separated from the mixed solution, and the catalyst liquid is further reacted. A method for continuously producing a silane compound such as monosilane, monochlorosilane or dichlorosilane while circulating in a column is described.

Here, a silicon single crystal used for manufacturing a semiconductor device is produced from polycrystalline silicon by various growth methods. At this time, polycrystalline silicon used as a starting material is required to have extremely high purity. Therefore, although the same process is described in Patent Document 1, polycrystalline silicon is usually charged with hydrogen chloride (HCl) in a layer (fixed bed, fluidized bed) filled with metal silicon having a purity of 95% or more, Alternatively, silicon tetrachloride (SiCl ₄ ) and H ₂ are supplied to produce trichlorosilane (SiHCl ₃ ), which is purified by distillation, and the resulting high-purity trichlorosilane (SiHCl ₃ ) is added to the CVD furnace. And produced by a method of reducing with high purity hydrogen.

In the above-described process for producing high-purity trichlorosilane (SiHCl ₃ ), first, as shown in the following chemical formula (1) and chemical formula (2), depending on the difference in the gas acting on the metal silicon in the reaction furnace. Reaction occurs.

Si + 3HCl → SiHCl ₃ + H ₂ (1)
Si + 3SiCl ₄ + 2H ₂ → 4SiHCl ₃ (2)

In the above-mentioned gas after the reaction, in addition to the generated trichlorosilane, silicon tetrachloride as a by-product, hydrogen, unreacted gas, etc., metal silicon fine powder, metal silicon or substances other than silicon contained in metal silicon Solid and gaseous high-boiling substances (hereinafter also simply referred to as “high-boiling substances”) generated by chlorination of (Al, Fe, etc.) are included.

Therefore, when recovering chlorosilanes from the flocculated liquid of chlorosilanes containing fine powder and high-boiling substances (impurities), high-boiling substances that cause blockage of piping and the like are removed, and high-purity chlorosilane is obtained in a high yield. As a technique for recovering the kind, there is one described in Patent Document 4. In this document, a certain amount of fine powder and high-boiling substances concentrated as a bottom liquid at the bottom of the distillation column are extracted and heated in a separate container to gasify and separate the trichlorosilane and silicon tetrachloride, which are useful components. The method of extracting fine powder and high-boiling substances out of the system after returning to the distillation column and concentrating at the bottom of this separate container (reconcentration device) (that is, reconcentrating the bottom liquid concentrated at the bottom of the distillation column). Are listed. According to this document, fine powder and high-boiling substances can be efficiently obtained by setting the amount of the bottom liquid collected at the bottom of the distillation column and the amount of the liquid extracted from the reconcentrator to the outside of the system. It is described that high-purity chlorosilanes can be produced in a high yield without causing clogging of piping and the like.

In the semiconductor field, halogen-based gases such as halogen and hydrogen halide have been conventionally used as etching gas or cleaning gas. However, halogen-based gases are harmful to the human body and the environment, and it is indispensable to purify the exhaust gas containing these gases before discharging them outside the factory. As a method for purifying exhaust gas containing a halogen-based gas, a dry purification method in which the exhaust gas is introduced into a processing cylinder filled with a solid purification agent and brought into contact with the purification agent to remove the halogen-based gas from the exhaust gas. Many wet purification methods for removing halogen-based gas from exhaust gas by bringing it into contact with a halogen-based gas absorbing solution ejected from the upper part of the processing apparatus have been practiced.

For example, in the purification treatment of exhaust gas containing halogen-based gas discharged from the semiconductor manufacturing process, it is a case where dry exhaust gas containing highly reactive gas is treated without frequently replacing the purification agent with a new one. However, there is one disclosed in Patent Document 5 as a processing method and a processing apparatus that can reduce the halogen-based gas concentration in the gas after processing without risk of fire. In this document, an exhaust gas containing a halogen-based gas discharged from a semiconductor manufacturing process is brought into contact with an adsorbent to adsorb and remove the halogen-based gas from the exhaust gas, and a halogen-based gas absorption liquid is added to the adsorbent. An exhaust gas treatment apparatus is described in which a halogen-based gas adsorbed by an adsorbent is absorbed in a halogen-based gas absorption liquid and desorbed from the adsorbent. According to this document, by adopting such a configuration, it is not necessary to frequently replace the adsorbent (cleaning agent) with a new one, there is no risk of fire, and the halogen-based gas concentration in the treated gas It is described that can be easily lowered.

JP 2002-173313 A JP 60-81010 A Japanese Patent Publication No. 64-3804 JP 2004-256338 A JP 2006-130499 A

However, in the production of various chlorosilanes or monosilanes such as tetrachlorosilane, trichlorosilane, dichlorosilane, and monochlorosilane described in Patent Documents 1 to 3, HCl gas is used separately from the target gas containing various chlorosilanes or monosilanes. , H ₂ gas, chlorosilane gas, and the like are often discharged outside the reactor as unnecessary exhaust gas.

Then, if such unnecessary exhaust gas is discharged as it is to the outside of the various chlorosilane production plants, chlorosilane gases such as trichlorosilane, dichlorosilane, and monochlorosilane, or monosilane gas and H ₂ gas, and oxygen in the air. Risk of explosion by reaction and fire. In addition, HCl gas, chlorosilane gas, or monosilane gas is harmful to the human body and the environment, and it is indispensable to purify the exhaust gas containing these gases before discharging them outside the factory.

Furthermore, HCl gas and H ₂ gas contained in such unnecessary exhaust gas may be reused as raw materials when producing various chlorosilanes or monosilanes such as tetrachlorosilane, trichlorosilane, dichlorosilane, and monochlorosilane. There is. Therefore, discarding these HCl gas and H ₂ gas as unnecessary exhaust gas, or changing to another substance by chemical reaction for safe processing, HCl gas, which is a very useful raw material, H ₂ gas is wasted.

Here, the technique of Patent Document 4 removes high-boiling substances that cause clogging of pipes and the like when recovering chlorosilanes from an aggregate of chlorosilanes containing fine powder and high-boiling substances (impurities), The purpose is to recover high-purity chlorosilanes with high yield, so it is particularly useful for safely treating unnecessary exhaust gas containing HCl gas, H ₂ gas, chlorosilanes gas, etc. Can't stand.

In addition, the technique of Patent Document 5 uses sodium hydroxide (concentration 2 wt%), calcium hydroxide (concentration 2 wt%), sodium sulfite (concentration 5 wt%), sodium thiosulfate (concentration 20 wt%) as a halogen-based gas absorption solution. Since an aqueous solution containing sodium carbonate (concentration 5 wt%) and sodium hydrogen carbonate (concentration 5 wt%) is used, HCl gas is neutralized by the alkaline aqueous solution, and wasteful HCl gas, which is a useful raw material, is wasted. It will be thrown away. Further, even when water is used as the halogen-based gas absorbing solution, there is no mention of particularly recovering and reusing HCl gas.

Furthermore, if a mixed gas containing HCl gas, H ₂ gas, chlorosilane gas, etc. is treated by the technique of this Patent Document 5, chlorosilane gases such as trichlorosilane, dichlorosilane, and monochlorosilane, or monosilane gas, reacts with water or an aqueous alkaline solution will be generated by the SiO _2, and SiO ₂ is precipitated or deposited in the sump or drain pipe of halogen gas absorbing liquid, and extravasation of halogen gas absorbing liquid from the reservoir, It may cause clogging of drainage pipes.

The present invention has been made in view of the above circumstances, and it is possible to stably remove hydrogen halide and silicon halide from a mixed gas containing hydrogen halide, hydrogen and silicon halide by a wet processing method. An object of the present invention is to provide a technique for separating reusable hydrogen gas. Another object of the present invention is to provide a technique for separating industrially reusable hydrogen halide gas from hydrogen halide removed by the wet processing method.

According to the present invention, a method of producing hydrogen gas by separating hydrogen from a mixed gas containing hydrogen halide, hydrogen and silicon halide, and contacting the mixed gas and the first aqueous solvent, Reacting the silicon halide and the first aqueous solvent to obtain at least a part of the silicon halide from the mixed gas to obtain a first purified gas; and the first purified gas and the second aqueous solvent. Contacting the hydrogen halide into the second aqueous solvent to obtain a second purified gas obtained by removing at least a part of the hydrogen halide from the first purified gas. A method for producing hydrogen gas is provided.

According to this method, by contacting hydrogen halide, a mixed gas containing hydrogen and silicon halide, and the first aqueous solvent, first, the silicon halide and the first aqueous solvent are reacted, and the design, operation, At least a portion of the silicon halide can be stably removed from the mixed gas by a wet processing method that is easy to maintain. Then, by bringing the first purified gas from which at least a part of the silicon halide has been removed and the second aqueous solvent into contact with each other, the hydrogen halide contained in the first purified gas is converted into the second aqueous solvent. At least a part of the hydrogen halide can be stably removed from the first purified gas by a wet processing method that is absorbed in and easy to design, operate, and maintain.

Therefore, according to this method, at least a part of silicon halide and hydrogen halide is stably produced from a mixed gas containing hydrogen halide, hydrogen, and silicon halide by a wet processing method that is easy to design, operate, and maintain. By removing, high-purity hydrogen gas having a small content of silicon halide and hydrogen halide can be separated, and industrially reusable hydrogen gas can be separated.

Further, according to this method, the hydrogen halide removed by the above wet processing method is merely absorbed in the second aqueous solvent, and is separated by another chemical reaction with other chemical substances. Since it is not changed to a chemical substance, it is possible to recover the hydrogen halide absorbed in the second aqueous solvent. Therefore, according to this method, the industrially reusable hydrogen halide gas can be separated.

According to the present invention, there is also provided a method of reducing silicon halide to produce a silicon compound having a lower halogenation degree than silicon halide, wherein the silicon halide is reduced using hydrogen and silicon halide as raw materials. A step of recovering the mixed gas discharged when reducing the silicon halide, and a step of producing hydrogen gas by separating hydrogen from the mixed gas by the hydrogen gas production method. And a step of supplying the produced hydrogen gas as a raw material to the step of reducing the silicon halide again.

According to this method, using hydrogen and silicon halide as raw materials, after recovering the mixed gas containing hydrogen halide, hydrogen and silicon halide discharged when reducing the silicon halide, Since hydrogen is separated from the mixed gas by the production method to produce hydrogen gas, it is stable from the mixed gas containing hydrogen halide, hydrogen and silicon halide by the wet processing method that is easy to design, operate and maintain. In addition, at least a part of the silicon halide and hydrogen halide can be removed.

Therefore, according to this method, it is possible to separate high-purity hydrogen gas having a small content of silicon halide and hydrogen halide, and it is possible to separate hydrogen gas that can be industrially reused.

According to this method, the industrially reusable hydrogen gas thus separated is supplied again as a raw material to the step of reducing the silicon halide, thereby reducing the amount of dangerous exhaust gas emitted. At the same time, it enables efficient use of resources, improves the production efficiency of chemical processes that reduce silicon halide, and can also help solve environmental problems.

According to the present invention, there is also provided a plant for producing hydrogen gas by separating hydrogen from a mixed gas containing hydrogen halide, hydrogen and silicon halide, and contacting the mixed gas and the first aqueous solvent. To obtain a first purified gas obtained by reacting silicon halide and the first aqueous solvent to remove at least a part of the silicon halide from a mixed gas, and a first purified gas And a second purified gas obtained by allowing hydrogen halide to be absorbed into the second aqueous solvent by contacting the second aqueous solvent and removing at least a part of the hydrogen halide from the first purified gas. And a hydrogen gas production plant comprising:

According to this plant, hydrogen halide, a mixed gas containing hydrogen and silicon halide, and the first aqueous solvent are brought into contact with each other, so that the silicon halide and the first aqueous solvent are first reacted to design, operate, At least a portion of the silicon halide can be stably removed from the mixed gas by a wet processing method that is easy to maintain. Then, by bringing the first purified gas from which at least a part of the silicon halide has been removed and the second aqueous solvent into contact with each other, the hydrogen halide contained in the first purified gas is converted into the second aqueous solvent. At least a part of the hydrogen halide can be stably removed from the first purified gas by a wet processing method that is absorbed in and easy to design, operate, and maintain.

Therefore, according to this plant, at least a part of silicon halide and hydrogen halide is stably produced from a mixed gas containing hydrogen halide, hydrogen and silicon halide by a wet processing method which is easy to design, operate and maintain. By removing, high-purity hydrogen gas having a small content of silicon halide and hydrogen halide can be separated, and industrially reusable hydrogen gas can be separated.

In addition, according to this plant, the hydrogen halide removed by the above wet processing method is merely absorbed in the second aqueous solvent, and is separated by another chemical reaction with other chemical substances. Since it is not changed to a chemical substance, it is possible to recover the hydrogen halide absorbed in the second aqueous solvent. Therefore, according to this plant, separation of industrially reusable hydrogen halide gas can be performed.

The above-described hydrogen gas production method, silicon compound production method, and hydrogen gas production plant are one embodiment of the present invention, and the hydrogen gas production method, silicon compound production method, and hydrogen gas production plant of the present invention. May be any combination of the above components.

Also, the hydrogen gas separation method, hydrogen gas purification method, hydrogen gas recovery method, hydrogen gas recycling method, hydrogen gas treatment method, hydrogen halide gas production method, hydrogen halide gas separation method of the present invention Method, halogen gas purification method, halogen gas recovery method, halogen gas recycling method, halogen gas treatment method, silicon compound reduction method, hydrogen gas separation plant, hydrogen gas purification plant, hydrogen Gas recovery plant, hydrogen gas recycling plant, hydrogen gas processing plant, hydrogen halide gas production plant, hydrogen halide gas separation plant, halogenated gas purification plant, halogenated gas recovery plant, halogenated Gas recycling plants, halogenated gas processing plants, silicon compound reduction plants, etc. have the same configuration. And, the same effects.

According to the present invention, high-purity hydrogen gas having a small content of silicon halide and hydrogen halide can be separated, and industrially reusable hydrogen gas can be separated. Further, according to the present invention, industrially reusable hydrogen halide gas can be separated.

FIG. 5 is a diagram for explaining a flow of a hydrogen gas production process according to the first embodiment. FIG. 10 is a diagram for explaining equipment for a production process of trichlorosilane used in a modification of the second embodiment. It is a figure for demonstrating the equipment of the manufacturing process of dichlorosilane, monochlorosilane, and monosilane used in Embodiment 2.

Explanation of symbols

1: reaction tower 2: reboiler 3: condenser 4: raw material supply conduit 5: control valve 6: condenser 7: collection storage tank 8: control valve 9: evaporation tank 10: pump 11: condenser 12: storage tank 13: replenishment Tube 21: SiCl ₄ evaporator 22: heater 23: reactor 24: electric furnace 25: take-out tube 26: condenser 27: sample port 100: plant 102: washing tower 104: slurry storage tank 106: filter press 108: hydrochloric acid scrubber 110: diffusion tower 112: water washing tower 114; removal tower 116: moisture removal device

<Explanation of terms>
In the present specification and claims, the expression “minimum value to maximum value” means a numerical range not less than the minimum value and not more than the maximum value. Further, the expression “%” means volume% (v / v) unless otherwise specified.

(1) Silicon Halide In the present specification and claims, the term “halogenated silicon” means halogenated silicon and is a compound of chlorosilanes such as SiCl ₄ , SiHCl ₃ , SiH ₂ Cl ₂ , and SiH ₃ Cl. It is a concept that includes In addition to chlorosilane compounds, SiF ₄ , SiHF ₃ , SiH ₂ F ₂ , SiH ₃ F, SiBr ₄ , SiHBr ₃ , SiH ₂ Br ₂ , SiH ₃ Br, SiI ₄ , SiHI ₃ , SiH ₂ It is a concept including I ₂ and SiH ₃ I.

Note that chlorosilane, which is a kind of silicon halide, includes the following four types.
Material name Chemical formula Boiling point Tetrachlorosilane (silicon tetrachloride) SiCl ₄ 57 ° C
Trichlorosilane SiHCl ₃ 32 ° C
Dichlorosilane SiH ₂ Cl ₂ 8 ° C
Monochlorosilane SiH ₃ Cl 30 ° C
In addition, said trichlorosilane is classified into the dangerous goods (class 3) of the Fire Service Act.

(2) Monosilane Monosilane (SiH ₄ ) is a compound having a boiling point of −112 ° C., and is classified as a special high-pressure gas (pyrophoric). Monosilane is a special material gas used for manufacturing semiconductors, liquid crystal panels, solar cells, and the like. In recent years, demand has been steadily expanding, and growth is expected as a CVD material widely used in the electronics field.

(3) Silicon compound In the present specification and claims, the silicon compound means a compound containing silicon and other elements. Silicon compounds include silicon halides (tetrachlorosilane, trichlorosilane, dichlorosilane, monochlorosilane) and monosilane.

(4) Reduction of silicon halide In the present specification and claims, reduction of silicon halide means that a reduction substance such as hydrogen gas is reacted with silicon halide to increase the degree of reduction (halogenation). It means that it is converted to a low-grade substance. For example, in the case of reduction of a chlorosilane compound, it means that silicon halide is reduced in the following order.
SiCl ₄ → SiHCl ₃ → SiH ₂ Cl ₂ → SiH ₃ Cl → SiH ₄

(5) Hydrogen halide In the present specification and claims, hydrogen halide means a hydride of a Group 17 element. Only a compound that is bonded one-to-one with hydrogen is known, and HX may be written as an abbreviation for hydrogen halide in general. For example, hydrogen fluoride (HF, boiling point 19.5 ° C.), hydrogen chloride (HCl, boiling point−85.1 ° C.), hydrogen bromide (HBr, boiling point−67.1 ° C.), hydrogen iodide (HI, boiling point− 35.1 ° C.). Although hydrogen halides other than hydrofluoric acid are completely ionized in water, they themselves are not very strong polar substances. The aqueous solutions of hydrogen chloride, hydrogen bromide, and hydrogen iodide are completely ionized and show strong acidity, and the strength of the acid is in the order of HCl <HBr <HI. Of these, hydrochloric acid (hydrogen chloride, HCl) is most frequently used in the industry.

(6) Hydrogen In the present specification and claims, hydrogen means hydrogen molecule (hydrogen gas) H ₂ which is a simple substance of hydrogen. Hydrogen molecules are colorless and odorless gases at room temperature, have a boiling point of −252.6 ° C., are light and extremely flammable. In general, in addition to the production of ammonia (Harbour-Bosch process), the cheapest and cleanest reducing agents include trichlorosilane, dichlorosilane, monochlorosilane and monosilane production processes, as well as hydrochloric acid production, metal ore reduction, and oil and fat modification. It is used in many fields such as quality and desulfurization.

(7) Aqueous solvent In the present specification and claims, the aqueous solvent is a concept including water, an aqueous solution, and a polar solvent. In the present specification and claims, water is not limited to only 100% pure H ₂ O, and may be an aqueous solution or a water suspension containing some impurities, It shall be described as water. The polar solvent includes a protic polar solvent and an aprotic polar solvent. Examples of the protic solvent include water (H ₂ O), ethanol (CH ₃ CH ₂ OH), methanol (CH ₃ OH), acetic acid (CH ₃ C (═O) OH), and the like.

(8) Suspension In the present specification and claims, the term “suspension” means a mixture of particles and liquid that are at least 1 micrometer or larger and larger than a colloid. Unlike colloidal solutions, suspensions settle to a steady state over time. An example of a suspension is a slurry containing silica and water (or aqueous hydrochloric acid). Suspended particles can be seen with a microscope, and when placed in a quiet place, they settle down over time.

(9) Scrubber In the present specification and claims, a scrubber (cleaning dust collection device) is a kind of harmful substance removal device contained in exhaust gas, and a liquid such as water is used as a cleaning liquid to remove particles, etc. in the exhaust gas. A device that collects and separates impurities in a droplet or a liquid film of a cleaning solution, and means a cleaning dust collection device (wet scrubber or wet scrubber). In order to make the separation of dust by droplets effective in this type of apparatus, various devices have been devised for forming droplets, liquid films, and the like and cleaning methods. A method of collecting dust by passing exhaust gas into the stored water (reservoir type), a method of injecting pressurized water into the flow of exhaust gas (pressurized water type), and a cleaning film sprayed on a filling material such as plastic and porcelain. There are a method of collecting dust by contact (packed layer type), a method of dispersing cleaning liquid with a rotating body and contacting exhaust gas (rotary type).

(10) Filter press In the present specification and claims, the filter press is a typical method for pressure filtration, and is a filter plate with a hole in the center with metal or resin unevenness. This is a device in which a filter cloth is attached in series, and slurry (silica, sludge, excavated soil, cement, etc.) is pressed and pressed through a hole in the center of the filter plate with a pump. . With the pressure of the slurry that has been injected, only water is discharged from the filter cloth through the gap between the two filter plates, and a dehydrated cake is formed between the filter plates (actually between the filter cloth and the filter cloth). It is formed. After completion of dehydration, the filter plate is opened and the cake is discharged. Most recent products are products that automate the discharge of cake.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings, the same reference numerals are given to the same components, and the description will be omitted as appropriate.

<Embodiment 1>
FIG. 1 is a diagram for explaining the equipment of the hydrogen gas production process according to the present embodiment. In the hydrogen gas production process shown in FIG. 1, hydrogen gas is separated from a mixed gas containing hydrogen chloride, hydrogen and chlorosilane to produce hydrogen gas.

A plant 100 shown in FIG. 1 is a plant 100 that produces hydrogen gas by separating hydrogen from a mixed gas containing hydrogen chloride, hydrogen, and chlorosilane. The mixed gas is supplied by recovering a gas discharged when reducing chlorosilane using hydrogen and chlorosilane as raw materials. That is, the plant 100 stably treats exhaust gas in the reduction reaction of chlorosilane so as not to adversely affect the environmental load and the human body, and separates hydrogen and hydrogen chloride for reuse as valuable raw materials. It is a plant for the purpose.

Note that the hydrogen chloride concentration in the mixed gas is preferably 10 mol% or less, and for example, a gas within the range of 7 to 8 mol% can be suitably used. Generally, in addition to the fact that the hydrogen chloride concentration contained in the exhaust gas in the reduction reaction of chlorosilane is 10 mol% or less, if the hydrogen chloride concentration in this exhaust gas is 10 mol% or less, the plant 100 described below can reasonably chlorinate. This is because hydrogen can be treated stably.

In this plant 100, first, in a washing tower 102, a mixed gas containing hydrogen chloride, hydrogen and chlorosilane and an aqueous solvent (silica hydrochloric acid circulating slurry) are brought into contact with each other, whereby chlorosilane and an aqueous solvent (silica hydrochloric acid silica) contained in the mixed gas are contacted. The water contained in the circulating slurry is reacted. As a result, a first purified gas (mixed gas containing hydrogen chloride, hydrogen and a small amount of residual chlorosilane) obtained by removing at least a part of chlorosilane from the mixed gas is obtained in the cleaning tower 102.

At this time, the washing tower 102 plays a role as a kind of reaction apparatus for reacting chlorosilane gas with water to produce silicon dioxide (SiO ₂ ). As a result, the chlorosilane gas contained in the mixed gas is absorbed (precisely suspended) as silica particles (SiO ₂ particles) in the hydrochloric acid silica slurry circulating in the washing tower 102 and the slurry storage tank 104. It will be. A part of the silica particles (SiO ₂ particles) stays as a suspension at the bottom of the slurry storage tank 104, and therefore a part of the retained silica particles (SiO ₂ particles) is removed from the slurry storage tank 104. It is extracted and fed to the filter press 106.

Here, since the reaction rate of chlorosilane and water is high, most of the chlorosilane is converted into silica particles (SiO ₂ particles) in the washing tower 102 and therefore does not migrate to the hydrochloric acid scrubber 108. However, in this cleaning tower 102, part of the hydrogen chloride contained in the mixed gas is absorbed by the water contained in the hydrochloric acid silica slurry. However, since the absorption rate of hydrogen chloride by water is not so high, the washing tower 102 does not absorb much, and most of the hydrogen chloride moves to the next hydrochloric acid scrubber 108 and is absorbed by the hydrochloric acid aqueous solution in the hydrochloric acid scrubber 108. Will be.

Next, the first purified gas (mixed gas containing hydrogen chloride, hydrogen and a slight amount of residual chlorosilane) is sent from the top exit of the cleaning tower 102 to the hydrochloric acid scrubber 108. This hydrochloric acid scrubber 108 is contained in the first purified gas by contacting the first purified gas (mixed gas containing hydrogen chloride, hydrogen and a slight amount of residual chlorosilane) and an aqueous solvent (hydrochloric acid aqueous solution). Hydrogen chloride is absorbed into an aqueous solvent (aqueous hydrochloric acid). As a result, a second purified gas (a slight residual hydrogen chloride, hydrogen obtained by removing at least a part of hydrogen chloride from the first purified gas (a mixed gas containing hydrogen chloride, hydrogen and a small amount of residual chlorosilane)). And a mixed gas containing a small amount of residual chlorosilane).

At this time, the hydrochloric acid scrubber 108 absorbs hydrogen chloride and chlorosilane contained in the first purified gas, which is the top outlet gas of the cleaning tower 102, with water contained in the aqueous hydrochloric acid solution (exactly, hydrogen chloride is absorbed with water). Chlorosilane reacts with water to produce silicon dioxide (SiO ₂ ).

In this hydrochloric acid scrubber 108, a small amount of silica particles (SiO ₂ particles) are generated by the reaction of chlorosilane and water, as in the case of the washing tower 102. However, as shown in FIG. Is circulated between the cleaning tower 102 and a small amount of silica particles (SiO ₂ particles) generated in the hydrochloric acid scrubber 108 are sent into the cleaning tower 102 together with the hydrochloric acid aqueous solution, and then further slurried. Since it stays as a suspension at the bottom of the storage tank 104, some of the retained silica particles (SiO ₂ particles) are extracted from the slurry storage tank 104 and fed to the filter press 106.

Further, the plant 100 is a removal device (not shown) for removing silica particles (SiO ₂ particles) generated by the reaction of chlorosilane and water in the washing tower 102 from the bottom suspension of the slurry storage tank 104. Is further provided. This removal device (not shown) only needs to be able to discharge silica particles (SiO ₂ particles) well from the bottom suspension of the slurry reservoir 104. For example, the removal device (not shown) may be scraped by a screw or may be sucked by a pump. .

In addition, as already explained in part, the plant 100 performs solid-liquid separation on the suspension containing the silica particles (SiO ₂ particles) thus removed, so that a liquid containing hydrogen chloride ( A filter press 106 for collecting (hydrochloric acid) is further provided. That is, the filter press 106 separates the silica particles suspension comprising (SiO ₂ particles), and a solid component comprising silica particles (SiO ₂ particles) predominantly, a liquid component comprising an aqueous solution of hydrochloric acid mainly in It will serve as a kind of solid-liquid separator. In this plant 100, the silica content is filtered by the filter press 106 in this way, and then the filtered liquid is sent to the stripping tower 110.

The plant 100 further includes a diffusion tower 110 for diffusing the liquid (hydrochloric acid aqueous solution) containing hydrogen halide recovered by the filter press 106 in this way. As described above, in this plant 100, the hydrochloric acid aqueous solution is diffused in the stripping tower 110, whereby gas-liquid separation is performed into hydrogen chloride gas having a hydrogen chloride concentration of 99% or more and a liquid (hydrochloric acid aqueous solution) containing hydrogen chloride. Can do. That is, the diffusion tower 110 plays a role as a kind of gas-liquid separator. In the stripping tower 110, the liquid (hydrochloric acid aqueous solution) containing hydrogen halide recovered by the filter press 106 is released into the stripping tower 110, so that the pressure of the hydrogen chloride in the liquid (hydrochloric acid aqueous solution) is reduced. Since the saturation concentration is lowered and the contact area with the gas is increased, hydrogen chloride in the liquid (hydrochloric acid aqueous solution) is gasified to obtain high-purity hydrogen chloride gas having a hydrogen chloride concentration of 99% or more.

That is, in the stripping tower 110, the liquid after filtration by the filter press 106 is stripped, hydrogen chloride gas is obtained from the top of the stripping tower, and an aqueous hydrochloric acid solution having a concentration of about 20% is obtained from the bottom of the tower. The bottom liquid of the stripping tower 110 (hydrochloric acid solution having a concentration of about 20%) is sent to the cleaning tower 102 and the hydrochloric acid scrubber 108. In this way, in the plant 100, hydrogen chloride is circulated in the plant 100 without being wasted and discarded, so that resource efficiency is improved and adverse effects on the environment are reduced.

On the other hand, the second purified gas (mixed gas containing a slight residual hydrogen chloride, hydrogen and a slight residual chlorosilane) obtained by the hydrochloric acid scrubber 108 is further sent to the washing tower 112. In the washing tower 112, the second purified gas (mixed gas containing a slight residual hydrogen chloride, hydrogen and a slight residual chlorosilane) and an aqueous solvent (aqueous hydrochloric acid solution) are brought into contact.

Therefore, in the water washing tower 112, chlorosilane remaining in the second purified gas and water in the hydrochloric acid aqueous solution are reacted to generate silicon dioxide (SiO ₂ ), so that it slightly remains in the second purified gas. At least a portion of the chlorosilane to be removed is removed. Further, in the water washing tower 112, hydrogen chloride remaining in the second purified gas is absorbed by the aqueous hydrochloric acid solution, so that at least a part of the hydrogen chloride remaining slightly in the second purified gas is removed. As a result, a third purified gas obtained by further removing at least part of the slightly remaining chlorosilane and slightly remaining hydrogen chloride from the second purified gas is obtained from the top of the water washing tower 112. become. This third purified gas is a mixed gas containing very little residual hydrogen chloride, hydrogen and very little residual chlorosilane.

That is, the water washing tower 112 absorbs hydrogen chloride contained in the second purified gas sent from the tower top outlet of the hydrochloric acid scrubber 108 with water contained in the aqueous hydrochloric acid solution. Further, this water washing tower 112 absorbs chlorosilane contained in the second purified gas into water contained in the aqueous hydrochloric acid solution (more precisely, it reacts with water to produce silicon dioxide (SiO ₂ )). Become. In other words, the water washing tower 112 is a kind of reaction absorber that reacts chlorosilane with water contained in an aqueous hydrochloric acid solution to produce silicon dioxide (SiO ₂ ), and further absorbs hydrogen chloride with water contained in the aqueous hydrochloric acid solution. Will play a role.

Then, the third purified gas (including very little residual hydrogen chloride, hydrogen, and very little residual chlorosilane) obtained in the water washing tower 112 is sent to the removal tower 114 from the top outlet of the water washing tower 112. In this removal tower 114, a third purified gas (containing very little residual hydrogen chloride, hydrogen and very little residual chlorosilane) and an alkaline aqueous solvent (NaOH aqueous solution) are brought into contact with each other, thereby bringing the third purified gas into contact with the third purified gas. Is reacted with a slight remaining amount of hydrogen chloride and an alkaline aqueous solvent (aqueous NaOH solution). As a result, a fourth purified gas (high-purity hydrogen gas having a purity of 99% or more) obtained by removing at least a part of hydrogen chloride from the third purified gas is obtained from the top of the removal tower 114. That is, the removal tower 114 serves as an acid-alkali reactor for washing and neutralizing a small amount of hydrogen chloride contained in the third purified gas obtained from the top outlet of the water washing tower 112 with an aqueous NaOH solution.

The fourth purified gas (high-purity hydrogen gas) obtained from the top of the removal tower 114 removes moisture from the fourth purified gas (high-purity hydrogen gas) and has a moisture content of 0. It is sent to a water removal device (not shown) for obtaining a fifth purified gas that is 5% or less. The moisture removing device (not shown) is not particularly limited as long as moisture can be removed from the fourth purified gas (high purity hydrogen gas). For example, the moisture removing device is filled with a moisture adsorbing material. An adsorption tower, a vacuum moisture removing device, a dry scrubber filled with a moisture absorbent capable of removing moisture can be preferably used. Note that hydrogen gas (for example, newly purchased virgin H ₂ gas) may be supplied from another flow before the dehydration. That is, the moisture removing device (not shown) serves as a kind of hydrogen purifier (not shown) that dehydrates the hydrogen separated in the hydrochloric acid recovery step and the supplemental hydrogen.

Hereinafter, the operation and effect of the plant 100 according to the present embodiment will be described.
A hydrogen gas production plant 100 according to this embodiment is a plant 100 that produces hydrogen gas by separating hydrogen from a mixed gas containing hydrogen chloride, hydrogen, and chlorosilane. And this production plant 100 makes the water contained in a chlorosilane and a hydrochloric acid silica slurry react by making a mixed gas and a hydrochloric acid silica slurry contact, The 1st refinement | purification formed by removing at least one part of a chlorosilane from a mixed gas A cleaning tower 102 for obtaining gas is provided. In addition, the production plant 100 is configured to absorb hydrogen chloride in the aqueous hydrochloric acid solution by contacting the first purified gas and the aqueous hydrochloric acid solution, and remove at least a part of the hydrogen chloride from the first purified gas. A hydrochloric acid scrubber 108 is provided to obtain a second purified gas.

For this reason, according to this production plant 100, by contacting the mixed gas containing hydrogen chloride, hydrogen and chlorosilane and the silica hydrochloride slurry, first, the water contained in the chlorosilane and silica hydrochloride slurry is reacted to design, operate and maintain. Thus, at least a part of chlorosilane can be stably removed from the mixed gas by the wet processing method. Then, by bringing the first purified gas from which at least a part of chlorosilane has been removed and the aqueous hydrochloric acid solution into contact with each other, hydrogen chloride contained in the first purified gas is absorbed in the second aqueous solvent and designed. -At least a part of hydrogen chloride can be stably removed from the first purified gas by a wet processing method that is easy to operate and maintain.

Therefore, according to this method, at least a part of chlorosilane and hydrogen chloride is stably removed from a mixed gas containing hydrogen chloride, hydrogen and chlorosilane by a wet processing method that is easy to design, operate and maintain. High-purity hydrogen gas having a small content of chlorosilane and hydrogen chloride can be separated, and industrially reusable hydrogen gas can be separated. Further, according to this method, the hydrogen chloride removed by the above wet processing method is merely absorbed in the hydrochloric acid aqueous solution, and is changed into another chemical substance by a chemical reaction with other chemical substances. Therefore, it is possible to recover the hydrogen chloride absorbed in the aqueous hydrochloric acid solution. Therefore, according to this method, separation of industrially reusable hydrogen chloride gas can be performed.

Moreover, the hydrogen gas production plant 100 according to the present embodiment further includes a removal device for removing silicon dioxide generated by the reaction of water contained in the chlorosilane and silica hydrochloride slurry from the silica hydrochloride slurry. For this reason, it is possible to prevent silicon dioxide from staying and precipitating in the washing tower 102 and the slurry storage tank 104 and blocking the operation of the production plant 100, thereby improving the safety of the production plant 100 and further maintenance costs. Can be reduced.

Further, the hydrogen gas production plant 100 according to the present embodiment further includes a filter press 106 for solid-liquid separation of the removed suspension containing silicon dioxide and recovering an aqueous hydrochloric acid solution from the suspension. Therefore, the hydrochloric acid aqueous solution can be recovered from the hydrochloric acid silica slurry removed from the cleaning tower 102 and the slurry storage tank 104, and can be reused as a valuable raw material. Therefore, in this production plant 100, the utilization efficiency of resources can be increased and adverse effects on the environment can be reduced.

In addition, the hydrogen gas production plant 100 according to the present embodiment dissipates the recovered hydrochloric acid aqueous solution, thereby separating the gas into a hydrogen chloride gas having a hydrogen chloride concentration of 99% or more and a hydrochloric acid aqueous solution. Is further provided. Therefore, industrially reusable hydrogen chloride gas having a hydrogen chloride concentration of 99% or more can be recovered from the hydrochloric acid aqueous solution, and can be reused as a valuable raw material. Further, this aqueous hydrochloric acid solution can also be recycled to the washing tower 102, the hydrochloric acid scrubber 108, and the water washing tower 112 separately. Therefore, in this production plant 100, the utilization efficiency of resources can be increased and adverse effects on the environment can be reduced.

Further, the hydrogen gas production plant 100 according to the present embodiment causes the chlorsilane remaining in the second purified gas and the water contained in the aqueous hydrochloric acid solution to react with each other by bringing the second purified gas and the hydrochloric acid aqueous solution into contact with each other. A water washing tower for obtaining a third purified gas, wherein hydrogen chloride remaining in the second purified gas is absorbed in an aqueous hydrochloric acid solution and at least a part of chlorosilane and hydrogen chloride is removed from the second purified gas. 112 is further provided. For this reason, in this production plant 100, since the chlorsilane and hydrogen chloride remaining in the second purified gas can be removed because they have been separately removed in the cleaning tower 102 and the hydrochloric acid scrubber 108, the third The purity of the hydrogen gas contained in the purified gas can be further increased.

Further, the hydrogen gas production plant 100 according to the present embodiment causes the hydrogen chloride and the NaOH aqueous solution remaining in the third purified gas to react with each other by bringing the third purified gas and the NaOH aqueous solution into contact with each other. A removal tower 114 for obtaining a fourth purified gas obtained by removing at least a part of hydrogen chloride from the purified gas is further provided. For this reason, in this production plant 100, it is possible to remove at least part of the hydrogen chloride remaining in the third purified gas because it has been separately removed in the washing tower 112, so that hydrogen contained in the fourth purified gas The purity of the gas can be further increased.

In addition, the hydrogen gas production plant 100 according to the present embodiment removes moisture from the fourth purified gas to obtain a fifth purified gas having a moisture content of 0.5% or less. Is further provided. For this reason, in this production plant 100, since it has failed to be removed separately in the washing tower 102, the hydrochloric acid scrubber 108, and the water washing tower 112, at least part of the water remaining in the fourth purified gas can be removed. The purity of the hydrogen gas contained in the purified gas can be further increased.

<Embodiment 2>
The hydrogen gas production plant 100 according to Embodiment 1 can be suitably used by being incorporated in a manufacturing process of dichlorosilane, monochlorosilane, and monosilane. The contents already described in the first embodiment are not repeated in this embodiment.

FIG. 2 is a diagram for explaining equipment for manufacturing processes of dichlorosilane, monochlorosilane, and monosilane used in the second embodiment. Silicon hydride chloride such as trichlorosilane or dichlorosilane is supplied to the middle upper stage of the reaction tower 1 through the raw material supply conduit 4. The reaction tower 1 is a stainless steel distillation tower having a tower diameter of 83 mm, a height of 200 mm and 18 stages. A stainless steel condenser 3 is provided at the top of the reaction tower 1 so that methanol dry ice can be passed through the jacket for cooling. A reboiler 2 having a heater with a maximum output of 1 KW is provided at the lower part of the reaction tower 1.

In the reaction tower 1, the disproportionation reaction and separation by distillation occur at the same time, and the gas rich in the low-boiling components generated by the disproportionation reaction moves upward and is cooled in the condenser 3 to condense the accompanying high-boiling components. It is condensed in a stainless steel condenser 6 cooled with liquid nitrogen and collected in a collection storage tank 7 with liquid.

On the other hand, high-boiling components such as trichlorosilane and tetrachlorosilane generated by the disproportionation reaction move to the bottom of the column and are extracted together with the catalyst from the reboiler 2 to the evaporation tank 9 while adjusting the liquid level. The evaporating tank 9 is made of a stainless steel container with a stirrer having an internal volume of 3 L, and is provided with a jacket. Heated heating medium oil is circulated through the heating tank to heat the evaporation tank. This evaporation tank 9 was operated at a temperature higher than the boiling point of tetrachlorosilane generated by the disproportionation reaction and lower than the catalyst, and trichlorosilane and tetrachlorosilane extracted from the reboiler 2 were evaporated and cooled with methanol dry ice. It is collected by the condenser 11 and collected in the storage tank 12. The catalyst remaining in the evaporation tank 9 is extracted by the pump 10 and is circulated again to the top of the reaction tower 1. In this case, when the concentration of the hydrochloride of the tertiary aliphatic hydrocarbon-substituted amine in the catalyst is not a predetermined concentration, hydrogen chloride is supplied from the supply pipe 13 as necessary.

Also in this case, not all of the trichlorosilane and tetrachlorosilane as raw materials are consumed in the reaction tower 1, but some of these raw materials are transferred to the bottom of the tower and the liquid from the reboiler 2 together with the catalyst. The surface is adjusted and extracted to the evaporation tank 9. This evaporation tank 9 was operated at a temperature higher than the boiling point of tetrachlorosilane generated by the disproportionation reaction and lower than the catalyst, and trichlorosilane and tetrachlorosilane extracted from the reboiler 2 were evaporated and cooled with methanol dry ice. It is collected by the condenser 11 and collected in the storage tank 12. However, not all of the trichlorosilane and tetrachlorosilane can be condensed in the condenser 11 and recovered in the storage tank 12, and some of the trichlorosilane and tetrachlorosilane are directly discharged to the outside as exhaust gas.

In addition, the exhaust gas contains a small amount of hydrogen gas and hydrogen chloride gas. This is because hydrogen chloride is replenished from the replenishment pipe 13 as necessary, and part of the replenished hydrogen chloride gas may be contained in the exhaust gas. In addition, although originally intended to cause the following reactions,
2SiHCl ₃ ⇔SiCl ₄ + SiH ₂ Cl ₂
2SiH ₂ Cl ₂ ⇔SiHCl ₃ + SiH ₃ Cl
2SiH ₃ Cl⇔SiH ₂ Cl ₂ + SiH ₄
This is because hydrogen gas may be generated due to the following hydrochloric acid elimination reaction.
SiH ₄ + HCl → SiH ₃ Cl + H ₂
SiH ₃ Cl + HCl → SiH ₂ Cl ₂ + H ₂
SiH ₂ Cl ₂ + HCl → SiHCl ₃ + H ₂
SiHCl ₃ + HCl → SiCl ₄ + H ₂

Therefore, also in the manufacturing process of dichlorosilane, monochlorosilane, and monosilane, hydrogen chloride, hydrogen, tetrachlorosilane, and trichlorosilane are contained by recovering exhaust gas discharged when reducing trichlorosilane from the top of the storage tank 12. The mixed gas is supplied to the cleaning tower 102 of the hydrogen gas production plant 100 in FIG. The hydrogen chloride concentration in the mixed gas is preferably 5% or less. In general, the hydrogen chloride concentration contained in the exhaust gas in the production process of dichlorosilane, monochlorosilane, and monosilane is 5% or less, and if the hydrogen chloride concentration in the exhaust gas is 5% or less, the plant described later This is because 100 can reasonably treat hydrogen chloride.

As described in Embodiment 1 above, the mixed gas supplied to the cleaning tower 102 of the plant 100 is recovered as high-purity hydrogen gas from the top of the removal tower 114 as a result of being processed in the plant 100. Through the moisture removing device, the moisture content is reduced to 0.5% or less. The hydrogen gas production plant 100 can produce hydrogen gas by separating hydrogen from the mixed gas. Although it is difficult to reuse the hydrogen gas thus produced in the apparatus for producing dichlorosilane, monochlorosilane, and monosilane shown in FIG. 2, this high-purity hydrogen gas is used as a raw material for some other useful chemical process. Needless to say, it can be used.

On the other hand, hydrogen chloride gas with a purity of 99.9% or more recovered from the top of the stripping tower 110 of the plant 100 is supplied again to the evaporation tank 9 of the apparatus for producing dichlorosilane, monochlorosilane, and monosilane shown in FIG. can do. By reusing hydrogen chloride gas in this way, dichlorosilane, monochlorosilane, and monosilane can be produced by reducing trichlorosilane using the high-purity hydrogen chloride gas again.

That is, according to this plant 100, after recovering the mixed gas containing hydrogen chloride, hydrogen and chlorosilane discharged from the top of the storage tank 12 in the apparatus of FIG. The gas production plant 100 can produce hydrogen gas by separating hydrogen from the mixed gas. Therefore, according to this plant 100, at least a part of chlorosilane and hydrogen chloride can be stably removed from a mixed gas containing hydrogen chloride, hydrogen, and chlorosilane by a wet processing method that is easy to design, operate, and maintain. it can.

Therefore, according to this method, high-purity hydrogen gas having a small content of chlorosilane and hydrogen chloride can be separated, and hydrogen gas and hydrogen chloride gas which can be industrially reused can be separated. According to this method, the industrially reusable hydrogen chloride gas separated in this way is supplied again to the evaporation tank 9 in the apparatus of FIG. At the same time, it enables efficient use of resources, improves the production efficiency of chemical processes that reduce trichlorosilane, and can also help solve environmental problems.

<Modification of Embodiment 2>
The hydrogen gas production plant 100 according to Embodiment 1 can be suitably used by being incorporated into a trichlorosilane production process. The contents already described in the first and second embodiments are not repeated in this modification.

FIG. 3 is a diagram for explaining the equipment for the production process of trichlorosilane used in the modification of the second embodiment. The reactor 23 of the apparatus of FIG. 3 has an inner diameter of 5 cm and a length of 80 cm. A take-out pipe 25 having an inner diameter of 2 mm is provided from the latter half of the heating section of the reactor 23 to the rear outlet, and the reaction gas passes through the take-out pipe 25. Then, it is taken out from the reactor 23 and rapidly cooled. Using such an apparatus, the reaction is carried out at a hydrogen flow rate of 400 cc / min, silicon tetrachloride: hydrogen = 1: 1.33, 1250 ° C. The temperature at the outlet of the reactor is 400 ° C. (quenching time 0.03 seconds). However, the trichlorosilane manufacturing process equipment described in FIG. 3 is a laboratory-sized equipment. When actually operating as a commercial process, this laboratory-sized equipment is installed in the plant according to the production scale. Of course, you need to scale up to a size facility.

Also in this trichlorosilane production process, hydrogen chloride, hydrogen, and tetrachlorosilane are recovered by recovering exhaust gas discharged from the top of the condenser 26 using hydrogen and tetrachlorosilane as raw materials. 1 is supplied to the cleaning tower 102 of the hydrogen gas production plant 100 in FIG. In general, when chlorosilane is reduced to produce a silicon compound having a halogenation degree lower than that of chlorosilane, a mixed gas containing hydrogen chloride, hydrogen and tetrachlorosilane is obtained as exhaust gas. The hydrogen chloride concentration in the mixed gas is preferably 5% or less. In general, in addition to the concentration of hydrogen chloride contained in the exhaust gas in the production process of trichlorosilane being 5% or less, if the hydrogen chloride concentration in the exhaust gas is 5% or less, the plant 100 to be described later does not have any difficulty. This is because hydrogen chloride can be treated stably.

As described in Embodiment 1 above, the mixed gas supplied to the cleaning tower 102 of the plant 100 is recovered as high-purity hydrogen gas from the top of the removal tower 114 as a result of being processed in the plant 100. Through the moisture removing device, the moisture content is reduced to 0.5% or less. Then, the hydrogen gas production plant 100 separates hydrogen from the mixed gas to produce hydrogen gas, and the produced hydrogen gas is again supplied to the reactor 23 of the apparatus for reducing chlorosilane shown in FIG. It can be supplied as a raw material. By reusing hydrogen gas in this manner, tetrachlorosilane can be reduced again to produce trichlorosilane using the high purity hydrogen gas as a raw material.

That is, according to this plant 100, after collecting the mixed gas containing hydrogen chloride, hydrogen and chlorosilane discharged from the top of the condenser 26 in the apparatus of FIG. 3 when reducing chlorosilane using hydrogen and chlorosilane as raw materials. Thus, the hydrogen gas production plant 100 can separate hydrogen from the mixed gas to produce hydrogen gas. Therefore, according to this plant 100, at least a part of chlorosilane and hydrogen chloride can be stably removed from a mixed gas containing hydrogen chloride, hydrogen, and chlorosilane by a wet processing method that is easy to design, operate, and maintain. it can.

Therefore, according to this method, it is possible to separate high-purity hydrogen gas having a low content of chlorosilane and hydrogen chloride, and it is possible to separate hydrogen gas that can be industrially reused. According to this method, the industrially reusable hydrogen gas separated in this way is supplied again to the reactor 23 in the apparatus of FIG. 3 as a raw material for the step of reducing chlorosilane. In addition to reducing the amount of exhaust gas emitted, it enables efficient use of resources, improves the production efficiency of chemical processes that reduce chlorosilane, and helps to solve environmental problems.

In this case, the hydrogen chloride gas with a purity of 99.9% or more recovered from the top of the stripping tower 110 of the plant 100 is difficult to reuse in the apparatus for reducing chlorosilane shown in FIG. It goes without saying that hydrogen chloride gas having a purity of 99.9% or more can be used as a raw material for any useful chemical process.

As described above, the embodiments of the present invention have been described with reference to the drawings. However, these are exemplifications of the present invention, and various configurations other than the above can be adopted.

For example, in the above embodiment, the hydrogen halide is hydrogen chloride and the silicon halide is chlorosilane. However, the present invention is not particularly limited. For example, the hydrogen halide is HBr, and the silicon halide is SiBr ₄ , SiHBr ₃ , SiH ₂ Br ₂ , and SiH ₃ Br may be used. Alternatively, for example, the hydrogen halide may be HI and the silicon halide may be SiI ₄ , SiHI ₃ , SiH ₂ I ₂ , SiH ₃ I. Even if it does in this way, since all are the compounds regarding the same halogen element, the effect similar to said embodiment is show | played.

Further, in the above embodiment, silica hydrochloride slurry is used as the first aqueous solvent, but there is no particular limitation. For example, water, an aqueous solution, a polar solvent, or a slurry thereof may be used as the aqueous solvent. Good. Also in this case, the same action and effect can be achieved with an aqueous solvent.

In the above embodiment, an aqueous hydrochloric acid solution is used as the second aqueous solvent. However, there is no particular limitation, and for example, water, an aqueous solution, a polar solvent, or a slurry thereof may be used as the aqueous solvent. . Also in this case, the same action and effect can be achieved with an aqueous solvent.

Further, in the above embodiment, the scrubber hydrochloric acid is used as the absorber, but there is no particular limitation, and liquid such as water is used as the cleaning liquid, and impurities such as particles in the exhaust gas are contained in the cleaning liquid droplets or the liquid film. If it is a device that collects and separates it in an arbitrary absorption device (a method of collecting dust by passing exhaust gas in the stored water (reservoir type), a method of injecting pressurized water into the flow of exhaust gas (pressurized water type), A method of collecting exhaust gas in contact with the water film of the cleaning liquid sprayed on packing materials such as plastic and porcelain (packing layer type), a method of dispersing the cleaning liquid with a rotating body and contacting the exhaust gas (rotary type)) Even if it uses, the same effect is produced.

In the above embodiment, a filter press is used as the solid-liquid separation device. However, the present invention is not particularly limited, and any device can be used as long as it can generally separate solids and liquids suitably. For example, even when a centrifugal separator, a sedimentation separator, a filtration separator, or the like is used, the same effect can be obtained.

In the above embodiment, the washing tower 112 and the removal tower 114 are separate facilities. However, the washing tower 112 and the removal tower 114 may be integrated into a single equipment. In such a case, there is an advantage that the configuration of the plant 100 can be simplified, and the cost for construction, operation, and maintenance can be reduced.

Hereinafter, the present invention will be further described with reference to examples, but the present invention is not limited thereto.

<Example 1>
As shown in FIG. 1, a cleaning tower 102 (also including a slurry storage tank 104), a hydrochloric acid scrubber 108, a filter removing device (not shown, also including a filter press 106), a stripping tower 110, a water washing tower 112, a removal tower 114 (moisture content) The plant 100 of the hydrogen gas production process using the removal device 116 is also constructed. In this embodiment, the inlet composition of the cleaning tower 102 and the outlet composition of the hydrochloric acid scrubber 108 under the normal operating conditions of the plant 100 were examined.

Using the plant 100 shown in FIG. 1 described in the first embodiment, a mixed gas (the composition of the inlet of the cleaning tower 102 is hydrogen 84.7% (v / v), hydrogen chloride 15% (v / v), chlorosilane 0 .3% (v / v)) and 0% moisture were supplied to the washing tower 102. The cleaning tower 102 was operated for 200 hours under the conditions of a flow rate of 10 Nm ³ / h and a pressure of 100 kPa, and then the gas collected from the top outlet of the hydrochloric acid scrubber 108 was analyzed by gas chromatography. The outlet composition was 98.5% (v / v) or more of hydrogen, 20 ppm (v / v) of hydrogen chloride, less than 10 ppm (v / v) of chlorosilane, and 1.5% of water.

<Example 2>
In this example, the outlet composition of the stripping tower 110 under normal operating conditions of the plant 100 of Example 1 was studied.

The plant 100 shown in FIG. 1 described in the first embodiment is operated under the same conditions as in Example 1, and the gas collected from the top outlet of the stripping tower 110 is analyzed by gas chromatography. The outlet composition of 110 was less than 10 pp of hydrogen, 99.99% (v / v) or more of hydrogen chloride, less than 10 ppm (v / v) of chlorosilane, and less than 10 ppm (v / v) of water.

<Example 3>
In this example, the outlet composition of the water washing tower 112 under the normal operating conditions of the plant 100 of Example 1 was studied.

The plant 100 shown in FIG. 1 described in the first embodiment is operated under the same conditions as in the first embodiment, and the gas collected from the top outlet of the rinsing tower 112 is analyzed by gas chromatography. The outlet composition of 112 was 99.7% (v / v) or more of hydrogen, 10 ppm (v / v) of hydrogen chloride, less than 10 ppm (v / v) of chlorosilane, and 0.3% (v / v) of water.

<Comparative Example 1>
The case where the scrubber 108 was removed from Example 1 was examined in this example.

The plant 100 shown in FIG. 1 described in the first embodiment is operated under the same conditions as in the first embodiment except that the hydrochloric acid scrubber 108 is removed, and the gas collected from the top outlet of the cleaning tower 102 is gas. When analyzed by chromatography, the outlet composition of the washing tower 102 is as follows: hydrogen 91.0% (v / v), hydrogen chloride 6.0% (v / v), chlorosilane 100 ppm (v / v), water 3% (V / v).

<Discussion>
From the experimental results of the above-described Examples and Comparative Examples, it can be seen that the cleaning tower 102 and the hydrochloric acid scrubber 108 are devices that can take up absorption of hydrogen chloride and trace amounts of chlorosilane. Moreover, it turns out that hydrogen chloride and a trace amount chlorosilane can be absorbed more efficiently by adding the stripping tower 110. Then, it can be seen that if the water washing tower 112 is added, hydrogen chloride and a small amount of chlorosilane can be absorbed even more efficiently.

That is, according to the above results, by using a plant 100 as shown in FIG. 1, high-purity hydrogen gas having a small content of chlorosilane and hydrogen chloride is separated from a mixed gas containing hydrogen chloride, hydrogen and chlorosilane. You can see that you can. It can also be seen that high purity hydrogen chloride gas can also be separated.

In the above, this invention was demonstrated based on the Example. It is to be understood by those skilled in the art that this embodiment is merely an example, and that various modifications are possible and that such modifications are within the scope of the present invention.

Claims (20)

1. A method for producing hydrogen gas by separating hydrogen from a mixed gas containing hydrogen halide, hydrogen and silicon halide,
   A first gas obtained by bringing the mixed gas and the first aqueous solvent into contact with each other to react the silicon halide and the first aqueous solvent to remove at least a part of the silicon halide from the mixed gas. Obtaining a purified gas;
   By contacting the first purified gas and a second aqueous solvent, the hydrogen halide is absorbed into the second aqueous solvent, and at least a part of the hydrogen halide is absorbed from the first purified gas. Obtaining a second purified gas by removal;
   A method for producing hydrogen gas, including:
2. The method for producing hydrogen gas according to claim 1,
   Recovering the gas discharged when reducing the silicon halide by the disproportionation reaction of silicon halide as the mixed gas,
   A method for producing hydrogen gas, further comprising:
3. The method for producing hydrogen gas according to claim 1,
   Using hydrogen and silicon halide as raw materials, a step of recovering the gas discharged when reducing the silicon halide as the mixed gas,
   A method for producing hydrogen gas, further comprising:
4. The method for producing hydrogen gas according to claim 1,
   Removing silicon dioxide produced by the reaction of the silicon halide and the first aqueous solvent from the first aqueous solvent;
   A method for producing hydrogen gas, further comprising:
5. The method for producing hydrogen gas according to claim 4,
   Separating the suspension containing the removed silicon dioxide by solid-liquid separation, and recovering the liquid containing the hydrogen halide from the suspension;
   A method for producing hydrogen gas, further comprising:
6. The method for producing hydrogen gas according to claim 5,
   By dissipating the recovered liquid containing hydrogen halide,
   A hydrogen halide gas having a hydrogen halide concentration of 99% or more;
   A liquid containing hydrogen halide;
   The process of gas-liquid separation
   A method for producing hydrogen gas, further comprising:
7. The method for producing hydrogen gas according to claim 1,
   By bringing the second purified gas and the third aqueous solvent into contact with each other, the silicon halide remaining in the second purified gas and the third aqueous solvent are reacted with each other in the second purified gas. The remaining hydrogen halide is absorbed in the third aqueous solvent, and a third purified gas is obtained by removing at least a part of the silicon halide and the hydrogen halide from the second purified gas. Process
   A method for producing hydrogen gas, further comprising:
8. The method for producing hydrogen gas according to claim 7,
   By contacting the third purified gas with an alkaline aqueous solvent, the hydrogen halide remaining in the third purified gas and the alkaline aqueous solvent are reacted, and the halogenated from the third purified gas. Obtaining a fourth purified gas obtained by removing at least a part of hydrogen;
   A method for producing hydrogen gas, further comprising:
9. The method for producing hydrogen gas according to claim 8,
   Removing water from the fourth purified gas to obtain a fifth purified gas having a moisture content of 0.5% or less,
   A method for producing hydrogen gas, further comprising:
10. The method for producing hydrogen gas according to claim 1,
    The hydrogen halide is hydrogen chloride;
    The silicon halide is chlorosilane,
    Production method of hydrogen gas.
11. The method for producing hydrogen gas according to claim 10,
    The first aqueous solvent is a hydrochloric acid silica slurry,
    The second aqueous solvent is an aqueous hydrochloric acid solution.
    Production method of hydrogen gas.
12. A method of reducing a silicon halide to produce a silicon compound having a lower halogenation degree than the silicon halide,
    Reducing the silicon halide by a disproportionation reaction of the silicon halide using a hydrogen halide gas;
    Recovering the mixed gas discharged when reducing the silicon halide;
    Separating hydrogen halide gas from the mixed gas by the hydrogen gas production method according to claim 6;
    Supplying the separated hydrogen halide gas to the step of reducing the silicon halide again;
    A method for producing a silicon compound, comprising:
13. A method of reducing a silicon halide to produce a silicon compound having a lower halogenation degree than the silicon halide,
    A step of reducing the silicon halide using hydrogen and silicon halide as raw materials;
    Recovering the mixed gas discharged when reducing the silicon halide;
    A step of producing hydrogen gas by separating hydrogen from the mixed gas by the method for producing hydrogen gas according to claim 1;
    Supplying the produced hydrogen gas as a raw material to the step of reducing the silicon halide again;
    A method for producing a silicon compound, comprising:
14. A plant for producing hydrogen gas by separating hydrogen from a mixed gas containing hydrogen halide, hydrogen and silicon halide,
    A first gas obtained by bringing the mixed gas and the first aqueous solvent into contact with each other to react the silicon halide and the first aqueous solvent to remove at least a part of the silicon halide from the mixed gas. A reactor for obtaining purified gas;
    By contacting the first purified gas and a second aqueous solvent, the hydrogen halide is absorbed into the second aqueous solvent, and at least a part of the hydrogen halide is absorbed from the first purified gas. An absorption device for obtaining a second purified gas to be removed;
    A hydrogen gas production plant.
15. The hydrogen gas production plant according to claim 14,
    A removal device for removing silicon dioxide produced by the reaction of the silicon halide and the first aqueous solvent from the first aqueous solvent;
    A hydrogen gas production plant.
16. The hydrogen gas production plant according to claim 15,
    A solid-liquid separation device for solid-liquid separation of the suspension containing the removed silicon dioxide and recovering the liquid containing the hydrogen halide from the suspension;
    A hydrogen gas production plant.
17. The hydrogen gas production plant according to claim 16,
    By dissipating the recovered liquid containing hydrogen halide,
    A hydrogen halide gas having a hydrogen halide concentration of 99% or more;
    A liquid containing hydrogen halide;
    A gas-liquid separator that separates gas and liquid
    A hydrogen gas production plant.
18. The hydrogen gas production plant according to claim 14,
    By bringing the second purified gas and the third aqueous solvent into contact with each other, the silicon halide remaining in the second purified gas and the third aqueous solvent are reacted with each other in the second purified gas. The remaining hydrogen halide is absorbed in the third aqueous solvent, and a third purified gas is obtained by removing at least a part of the silicon halide and the hydrogen halide from the second purified gas. Reaction absorber for
    A hydrogen gas production plant.
19. The hydrogen gas production plant according to claim 18,
    By contacting the third purified gas with an alkaline aqueous solvent, the hydrogen halide remaining in the third purified gas and the alkaline aqueous solvent are reacted, and the halogenated from the third purified gas. An acid-alkali reactor for obtaining a fourth purified gas obtained by removing at least a part of hydrogen,
    A hydrogen gas production plant.
20. The hydrogen gas production plant according to claim 19,
    A moisture removing device for removing water from the fourth purified gas to obtain a fifth purified gas having a moisture content of 0.5% or less,
    A hydrogen gas production plant.

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