JP5511667B2 - 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 - Google Patents

Description

  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 lower part 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.

  As a conventional method for producing dichlorosilane, monochlorosilane, or monosilane, there is one 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). Have been described. 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, a halogen-based gas such as halogen or hydrogen halide has been conventionally used as an etching gas or a 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 Examined Patent Publication No. 64-3804 JP 2004-256338 A JP 2006-130499 A

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

And if such unnecessary exhaust gas is released as it is outside the production plant of various chlorosilanes, chlorosilane gases such as trichlorosilane, dichlorosilane and monochlorosilane, monosilane gas and H ₂ gas react with oxygen in the air. There is a risk of explosion and fire. In addition, HCl gas and chlorosilane gas are harmful to the human body and the environment, and it is essential 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, there is provided a method for removing silicon halide from a mixed gas containing hydrogen halide, hydrogen and silicon halide, wherein the silicon halide and the acidic aqueous solution are reacted by bringing the mixed gas and the acidic aqueous solution into contact with each other. And removing the at least part of the silicon halide from the mixed gas to obtain a purified gas.

  According to this method, by contacting a mixed gas containing hydrogen halide, hydrogen and silicon halide and an acidic aqueous solution, the silicon halide and the acidic aqueous solution are reacted to form silicon dioxide, so that the silicon halide is removed. can do. Further, according to this method, since silicon dioxide is easily suspended in an acidic aqueous solution, solidification of silicon dioxide can be suppressed.

  Therefore, according to this method, it is possible to prevent silicon dioxide from precipitating or adhering to the acid aqueous solution reservoir or drainage pipe, and overflowing of the acidic aqueous solution from the reservoir, blocking of the drainage pipe, or the like. Therefore, according to this method, at least a part of silicon halide can be stably removed from the mixed gas by a wet processing method that is easy to design, operate, and maintain.

  According to the present invention, there is also provided a plant for removing silicon halide from a mixed gas containing hydrogen halide, hydrogen and silicon halide, wherein the mixed gas and the acidic aqueous solution are brought into contact with each other, thereby bringing the silicon halide and the acidic aqueous solution into contact with each other. A silicon halide removal plant is provided that includes an acidic aqueous solution storage tank for reacting and removing at least a portion of the silicon halide from the mixed gas to obtain a purified gas.

  According to this plant, hydrogen halide, hydrogen and silicon halide mixed gas and acidic aqueous solution are contacted to react silicon halide and acidic aqueous solution to produce silicon dioxide, so silicon halide is removed can do. Moreover, according to this plant, since silicon dioxide is easy to suspend in acidic aqueous solution, solidification of silicon dioxide can be suppressed.

  Therefore, according to this plant, it is possible to prevent silicon dioxide from precipitating or adhering to the acidic aqueous solution reservoir or drainage pipe, and overflowing of the acidic aqueous solution from the reservoir, blocking of the drainage pipe, or the like. Therefore, according to this plant, at least a part of the silicon halide can be stably removed from the mixed gas by a wet processing method that is easy to design, operate, and maintain.

  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.

  Further, the exhaust gas treatment method of the present invention, the removal method of unreacted silicon halide, the treatment method of silicon halide in the mixed gas, the separation method of hydrogen gas, the purification method of hydrogen gas, the recovery method of hydrogen gas, the hydrogen gas Recycling method, hydrogen gas processing method, hydrogen halide gas production method, hydrogen halide gas separation method, halogenated gas purification method, halogenated gas recovery method, halogenated gas recycling method, halogen Hydrogen gas treatment method, silicon compound reduction method, hydrogen gas separation plant, hydrogen gas purification plant, hydrogen gas recovery plant, hydrogen gas reuse plant, hydrogen gas treatment plant, hydrogen halide gas production plant , Hydrogen halide gas separation plant, halogenated gas purification plant, halogenated gas recovery plant, halogenated gas recycling Use plants, processing plants halide gas, reducing plant silicon compounds, well as clogging prevention methods of these plants has the same configuration, the same effects.

  According to the present invention, at least a part of silicon halide can be stably removed from a mixed gas by a wet processing method that is easy to design, operate, and maintain.

It is a figure for demonstrating the installation of the chlorosilane removal plant which concerns on Embodiment 1. FIG. It is a figure for demonstrating the structure of the hydrochloric acid reaction tower with which the removal plant of chlorosilane which concerns on Embodiment 1 is equipped. It is a figure for demonstrating the structure of the gas-liquid contact pod with which the removal plant of chlorosilane which concerns on Embodiment 1 is equipped. It is a figure for demonstrating the equipment of the manufacturing process of dichlorosilane, monochlorosilane, and monosilane used in Embodiment 2. FIG. 10 is a diagram for explaining equipment for a production process of trichlorosilane used in a modification of the second embodiment.

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 Pipe 21: SiCl ₄ evaporator 22: heater 23: reactor 24: electric furnace 25: take-out pipe 26: condenser 27: sample port 100: plant 102: hydrochloric acid reaction tower 104: slurry reservoir 106: filter press 108: hydrochloric acid Scrubber 110: diffusion tower 112: water washing tower 114; removal tower 202: inner wall 204: bottom 206: rubber lining coating 208: vinyl chloride coating 210: silica particles 212: introduction pipe 214: spray 300: pod inner pipe 302: pod inner pipe Lower inside 304: Upper side of pod inner pipe 306: Bubbler pipe 308: Gas inlet 310: Gas outlet 312: Hydrochloric acid aqueous solution inlet 31 4: Discharge outlet

<Explanation of terms>
In the present specification and claims, the notation “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 six 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
Hexachlorodisilane Si ₂ Cl ₆ 144 ° C.
Disiloxane H ₃ SiOSiH ₃ -14.4 ° C
Methyldichlorosilane CH ₄ Cl ₂ Si 41 ° C.
Dimethylsilane (CH ₃ ) ₂ SiH ₂ -20 ° C
Trimethylchlorosilane C ₃ H ₉ ClSi 57.3 ° 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 are very 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 waste water film sprayed on plastic, porcelain and other fillings. There are a method of collecting dust by contact (packed bed 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.

(11) Turbulent flow In this specification and the claims, turbulent flow means a non-stationary fluid flow field. In general, in the case of a fluid flowing in a circular pipe, the Reynolds number is about 2,000 or less, laminar flow, about 2,000 to 4,000 transition region (region where laminar flow and turbulent flow change), 4, Since about 000 or more are regarded as turbulent flow, the definition is also applied in the present specification and claims.

(12) Acidic aqueous solution In the present specification and claims, an aqueous solution having a pH of 0 to 7 is defined as an acidic aqueous solution. Naturally, the concept includes aqueous solutions of strong acids such as hydrochloric acid aqueous solution (hydrogen chloride aqueous solution), sulfuric acid aqueous solution (dilute sulfuric acid aqueous solution), nitric acid aqueous solution, carbonated aqueous solution (carbon dioxide aqueous solution), acetic acid aqueous solution, citric acid aqueous solution and the like. is there.

  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 equipment of a silicon halide removal plant according to the present embodiment. In the silicon halide removal plant shown in FIG. 1, silicon halide is removed from a mixed gas containing hydrogen chloride, hydrogen and chlorosilane.

  The plant 100 shown in FIG. 1 is a plant 100 that removes silicon halide 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.

  In addition, it is preferable that the density | concentration of the silicon halide in this mixed gas is 1% or less. Generally, the concentration of silicon halide contained in the exhaust gas in the reduction reaction of chlorosilane is 1% or less, and if the concentration of silicon halide in the exhaust gas is 1% or less, the plant 100 described later This is because silicon halide can be removed stably without difficulty.

  In this plant 100, first, in a hydrochloric acid reaction tower 102, a mixed gas containing hydrogen chloride, hydrogen and chlorosilane and an acidic aqueous solution (hydrochloric acid aqueous solution) are brought into contact with each other, whereby chlorosilane and acidic aqueous solution (hydrochloric acid aqueous solution) contained in the mixed gas are contacted. The water contained in is reacted. As a result, in the hydrochloric acid reaction tower 102, 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.

At this time, the hydrochloric acid reaction tower 102 serves as a kind of reaction apparatus (acidic aqueous solution storage tank) for reacting chlorosilane gas with water to produce silicon dioxide (SiO ₂ ). As a result, the chlorosilane gas contained in the mixed gas is reslurried (suspended) as silica particles (SiO ₂ particles) in the hydrochloric acid aqueous solution circulating through the hydrochloric acid reaction tower 102 and the slurry storage tank 104. Here, since the silicon dioxide component (SiO ₂ component) has a characteristic of being easily suspended in an acidic aqueous solution (hydrochloric acid aqueous solution), solidification of silicon dioxide can be suppressed. That is, an acidic aqueous solution such as a hydrochloric acid aqueous solution has excellent characteristics that silica (silicon dioxide) is easy to reslurry and hardly changes in quality as compared with water or a basic aqueous solution, and thus suppresses solidification of silicon dioxide. Can do.

Therefore, in this plant 100, even in the hydrochloric acid reaction tower 102 where the silicon dioxide component (SiO ₂ component) is generated, silicon dioxide precipitates or adheres to the hydrochloric acid aqueous solution reservoir or drainage pipe, and the hydrochloric acid aqueous solution overflows from the reservoir. In addition, it is possible to suppress the occurrence of blockage of the drain pipe. A part of the silica particles (SiO ₂ particles) suspended without being dissolved in the hydrochloric acid aqueous solution stays as a suspension at the bottom of the slurry reservoir 104, but the retained silica particles (SiO ₂ particles). A part of the liquid is removed from the slurry storage tank 104 because the liquid is sent to the filter press 106. Therefore, according to the plant 100, at least a part of the silicon halide can be stably removed from the mixed gas by a wet processing method that is easy to design, operate, and maintain.

Here, since the reaction rate of chlorosilane and water is large, most of the chlorosilane is mainly composed of silicon dioxide component (SiO ₂ component) suspended in hydrochloric acid aqueous solution or silica particles (SiO ₂ ) suspended in hydrochloric acid aqueous solution. ₂ particles), it does not move to the hydrochloric acid scrubber 108. However, in this hydrochloric acid reaction tower 102, a part of hydrogen chloride contained in the mixed gas is absorbed by water contained in the aqueous hydrochloric acid solution. However, since the absorption rate of hydrogen chloride by water is not so high, the hydrochloric acid reaction tower 102 does not absorb much, and most of the hydrogen chloride moves to the next hydrochloric acid scrubber 108 and becomes hydrochloric acid aqueous solution in the hydrochloric acid scrubber 108. Will be absorbed.

Next, the first purified gas (mixed gas containing hydrogen chloride, hydrogen and a small amount of residual chlorosilane) is entrained with silica particles (SiO ₂ particles) from the top outlet of the hydrochloric acid reaction tower 102 to the hydrochloric acid scrubber 108. It is sent as unreacted chlorosilane gas. 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 contained in the first purified gas, which is the top outlet gas of the hydrochloric acid reaction tower 102, and the remaining unreacted chlorosilane gas with water contained in the aqueous hydrochloric acid solution. It serves as an absorption device for absorbing hydrogen with water and reacting unreacted chlorosilane gas with water to produce silicon dioxide (SiO ₂ ).

In this hydrochloric acid scrubber 108, a small amount of silica particles (SiO ₂ particles) are produced by the reaction of unreacted chlorosilane gas and water, as in the case of the hydrochloric acid reaction tower 102. As shown in FIG. Since the 108 aqueous hydrochloric acid solution is an acidic aqueous solution having a pH of 7.0 or less, a very small amount of silica particles (SiO ₂ particles) is easily suspended. Further, entrainment containing silica particles (SiO ₂ particles) also come contaminated hydrochloric acid the reaction tower 102, but silica particles contained in the entrainment (SiO ₂ particles) also suspended in aqueous hydrochloric acid hydrochloride scrubber 108 End up.

Of course, some silica particles (SiO ₂ particles) may be suspended, but also in that case, the hydrochloric acid aqueous solution of the hydrochloric acid scrubber 108 circulates between the hydrochloric acid reaction tower 102 and hydrochloric acid. A small amount of silica particles (SiO ₂ particles) generated in the scrubber 108 and suspended silicon dioxide components (SiO ₂ components) are sent into the hydrochloric acid reaction tower 102 together with the hydrochloric acid aqueous solution, and then further added to the slurry storage tank. Since it stays as a suspension at the bottom of 104 or is suspended in an aqueous hydrochloric acid solution, a part of the retained silica particles (SiO ₂ particles) or suspended silicon dioxide components (SiO ₂ components) is stored in the slurry. It is extracted from the tank 104 and fed to the filter press 106.

The plant 100 also has a removal device (not shown) for removing silica particles (SiO ₂ particles) generated by the reaction of chlorosilane and water in the hydrochloric acid reaction tower 102 from the bottom suspension of the slurry reservoir 104. ). 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 stripping tower 110 for stripping the liquid (hydrochloric acid aqueous solution) containing hydrogen halide collected 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 (an aqueous hydrochloric acid solution having a concentration of about 20%) is sent to the hydrochloric acid reaction tower 102, the hydrochloric acid scrubber 108, and the water washing tower 112. 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.

  FIG. 2 is a diagram for explaining the configuration of the hydrochloric acid reaction tower 102 provided in the chlorosilane removal plant 100 according to the first embodiment. The hydrochloric acid reaction tower 102 is provided with one or a plurality of introduction pipes 212 for directly supplying chlorosilane in a gaseous state into a hydrochloric acid aqueous solution and bringing it into contact. In this way, through the introduction pipe 212 of the hydrochloric acid reaction tower 102, chlorosilane is directly supplied and brought into contact with the hydrochloric acid aqueous solution in a gas state, thereby generating silicon dioxide by the reaction of the chlorosilane and the hydrochloric acid aqueous solution. By performing directly, the production reaction from chlorosilane to silica can be efficiently performed.

  The number of the introduction pipes 212 is not particularly limited, and may be one, two, three, four, five, six, seven, as long as chlorosilane can be directly supplied into the hydrochloric acid aqueous solution in a gas state. Any number of 8, 9, and 10 may be used. However, it is preferable that the leading end opening of the introduction pipe 212 has a sufficient length because it needs to be immersed in an aqueous hydrochloric acid solution.

  In FIG. 2, the inside of the hydrochloric acid reaction tower 102 is depicted, and the bottom portion 204 can be seen at the back. Here, a rubber lining film 206 is provided on the inner wall 202 of the hydrochloric acid reaction tower 102 on the left side. On the other hand, a vinyl chloride coating 208 is provided on the inner wall 202 of the hydrochloric acid reaction tower 102 on the right side. The hydrochloric acid reaction column 102 used in this embodiment may have either the right or left configuration, but it is preferable that the left side rubber lining film 206 is provided.

  Further, as shown in the figure, the hydrochloric acid reaction tower 102 is provided with a spray 214 as a spray mechanism for maintaining the inner wall 202 of the hydrochloric acid reaction tower 102 in a wet state with an aqueous hydrochloric acid solution or water. In this way, by providing the spray 214 in the hydrochloric acid reaction tower 102 and maintaining the inner wall 202 of the hydrochloric acid reaction tower 102 in a wet state with an aqueous hydrochloric acid solution or water, silica particles are less likely to adhere to the inner wall 202, and the silica particles Even if adhering to the inner wall 202, the silica particles are easily suspended by the hydrochloric acid aqueous solution or water sprayed from the spray 214, so that the silica particles adhering to the inner wall 202 are easily removed.

  A large number of silica particles 210 adhering to the vinyl chloride coating 208 on the inner wall 202 of the hydrochloric acid reaction tower 102 on the right side, which is generally used, are observed, and the silica particles 210 precipitate or adhere to the reservoir or drainage pipe of the hydrochloric acid reaction tower 102. As a result, there is still a slight possibility that an aqueous hydrochloric acid solution overflows from the reservoir, or the drain pipe is blocked.

  On the other hand, since the rubber lining coating 206 is provided on the inner wall 202 of the hydrochloric acid reaction tower 102 on the left side, the adhering silica particles 210 are hardly observed, and the silica particles 210 are not present in the reservoir or drainage pipe of the hydrochloric acid reaction tower 102. The possibility of occurrence of precipitation or adhesion, overflowing of an aqueous hydrochloric acid solution from the reservoir, blockage of the drain pipe, etc. is almost completely eliminated. At this time, it is preferable that the hydrochloric acid reaction tower 102 is provided with a spray 214 as a spraying mechanism for maintaining the inner wall 202 in a wet state with a hydrochloric acid aqueous solution or water, and further a rubber lining film 206 is applied to the inner wall 202. In this way, due to the synergistic effect of each other, silica particles hardly adhere to the inner wall 202 even when operated for a long time, so that an aqueous hydrochloric acid solution overflows from the reservoir, or the drainage pipe is blocked. Sex can be almost completely eliminated.

  The hydrochloric acid aqueous solution circulating in the hydrochloric acid reaction tower 102 and the attached slurry storage tank 104 preferably has a hydrochloric acid concentration of 10% to 40%. This is because, if the concentration of the hydrochloric acid aqueous solution is within this range, the absorption of chlorosilane can be made efficient and the properties of the produced silica can be stabilized.

  FIG. 3 is a view for explaining the configuration of the hydrochloric acid scrubber 108 having the gas-liquid contact pod provided in the chlorosilane removal plant 100 according to the first embodiment. As shown in the figure, the pod inner tube 300 exists in the gas-liquid contact pod of the hydrochloric acid scrubber 108, and the lower inner portion 302 of the pod inner tube and the upper inner portion 304 of the pod inner tube 300 communicate with each other. The aqueous hydrochloric acid solution and the purified gas pass through the inner pipe 300 in the counterflow direction. A so-called turbulent flow is generated around the bubbler tube 306, the hydrochloric acid aqueous solution and the purified gas collide with each other violently, and mixing and gas-liquid contact with high efficiency are performed.

  The pod inner pipe 300 is provided with a bubbler pipe 306 which is a bubbling mechanism, so-called turbulent flow and a large amount of bubbles are generated around the bubbler pipe 306, and the hydrochloric acid aqueous solution and the purified gas collide with each other violently. When the bubbles burst, gas-liquid contact with good mixing efficiency is performed. This figure also shows a gas inlet 308 and a gas outlet 310 to the pod inner pipe 300 having a bubbler pipe 306, and also describes a hydrochloric acid aqueous solution inlet 312 and a discharge liquid outlet 314. From these arrangements, it is well understood that the aqueous hydrochloric acid solution and the purified gas pass through the pod inner tube 300 in the counterflow direction.

  As described above, the chlorosilane removal plant 100 according to Embodiment 1 is so-called around the bubbler pipe 306 by bringing the purified gas into contact with another hydrochloric acid aqueous solution in the gas-liquid contact pod inner pipe 300 of the hydrochloric acid scrubber 108. Since turbulent flow occurs and the hydrochloric acid aqueous solution and the purified gas collide with each other violently and mix and make efficient gas-liquid contact, the chlorosilane remaining in the purified gas and this hydrochloric acid aqueous solution react violently to purify Since most of the unreacted chlorosilane gas remaining from the gas is removed, a second purified gas containing almost no chlorosilane gas can be obtained.

  The hydrochloric acid aqueous solution circulating in the hydrochloric acid scrubber 108 preferably has a hydrochloric acid concentration of 10% to 40%. This is because, if the concentration of the hydrochloric acid aqueous solution is within this range, the absorption of chlorosilane can be made efficient and the properties of the produced silica can be stabilized.

Hereinafter, the operation and effect of the plant 100 according to the present embodiment will be described.
The chlorosilane removal plant 100 according to this embodiment is a plant 100 that separates hydrogen from a mixed gas containing hydrogen chloride, hydrogen, and chlorosilane to remove chlorosilane. And this plant 100 is made to contact the mixed gas and hydrochloric acid aqueous solution, the water contained in chlorosilane and hydrochloric acid aqueous solution is made to react, and the 1st refined gas formed by removing at least one part of chlorosilane from mixed gas is obtained. A hydrochloric acid reaction tower 102 is provided.

Therefore, according to this plant 100, by contacting a mixed gas containing hydrogen chloride, hydrogen and chlorosilane, and an aqueous hydrochloric acid solution which is an acidic aqueous solution, first, water contained in the chlorosilane and the aqueous hydrochloric acid solution is reacted, and the design, operation, By a wet processing method that is easy to maintain, at least a portion of chlorosilane can be stably removed from the mixed gas. Furthermore, since silicon dioxide (SiO ₂ ) generated by the reaction of chlorosilane and hydrochloric acid aqueous solution is easily suspended in an acidic solution, it is possible to suppress the occurrence of a problem that the hydrochloric acid reaction tower 102 is blocked due to fixation of silica particles.

  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. A high-purity purified gas having a low chlorosilane content can be separated, and industrially recyclable hydrogen gas and hydrogen chloride gas can be separated from the purified gas.

  Further, in the chlorosilane removal plant 100 according to the present embodiment, the hydrochloric acid reaction tower 102 which is an acidic aqueous solution storage tank is supplied with a mixed gas containing chlorosilane directly in a gaseous state and brought into contact with the hydrochloric acid aqueous solution. Alternatively, a plurality of introduction pipes 212 are provided. Therefore, the reaction efficiency of chlorosilane and hydrochloric acid aqueous solution contained in the mixed gas is improved, so that most chlorosilane can be removed at the stage of the hydrochloric acid reaction tower 102.

  In the chlorosilane removal plant 100 according to the present embodiment, the hydrochloric acid reaction tower 102 which is an acidic aqueous solution storage tank has a spray 214 which is a spray mechanism for maintaining the inner wall of the hydrochloric acid reaction tower 102 in a wet state with an aqueous hydrochloric acid solution or water. Is provided. In this way, by providing the spray 214 in the hydrochloric acid reaction tower 102 and maintaining the inner wall 202 of the hydrochloric acid reaction tower 102 in a wet state with an aqueous hydrochloric acid solution or water, silica particles are less likely to adhere to the inner wall 202, and the silica particles Even if adhering to the inner wall 202, the silica particles are easily suspended by the hydrochloric acid aqueous solution or water sprayed from the spray 214, so that the silica particles adhering to the inner wall 202 are easily removed.

  Furthermore, in the chlorosilane removal plant 100 according to this embodiment, a rubber lining film 206 is provided in the hydrochloric acid reaction tower 102 which is an acidic aqueous solution storage tank. As described above, since the rubber lining film 206 is provided on the inner wall 202 of the hydrochloric acid reaction tower 102, the adhered silica particles 210 are hardly observed, and the silica particles 210 are not collected in the reservoir portion or drainage pipe of the hydrochloric acid reaction tower 102. The possibility of occurrence of precipitation or adhesion, overflowing of an aqueous hydrochloric acid solution from the reservoir, blockage of the drain pipe, etc. is almost completely eliminated.

  Further, in the silicon halide removal plant 100 of the present embodiment, the purified gas obtained as described above is brought into gas-liquid contact with another hydrochloric acid aqueous solution in a turbulent state, whereby chlorosilane contained in the purified gas is contained. And a hydrochloric acid scrubber 108 which is a gas-liquid contact device for obtaining a second purified gas obtained by reacting the aqueous hydrochloric acid solution and removing at least a part of chlorosilane from the purified gas.

  In this way, in the gas-liquid contact pod inner pipe 300 of the hydrochloric acid scrubber 108, by bringing the purified gas into contact with another aqueous hydrochloric acid solution, so-called turbulent flow is generated around the bubbler tube 306, and the aqueous hydrochloric acid solution and the purified gas are produced. Are violently collided with each other and mixed and gas-liquid contact is performed with good efficiency.Therefore, the chlorosilane remaining in the purified gas and the hydrochloric acid aqueous solution react vigorously, and most of the unreacted chlorosilane gas remaining from the purified gas is removed. Since it will be removed, a second purified gas containing almost no chlorosilane gas can be obtained.

  The gas-liquid contact pod inner pipe 300 of the hydrochloric acid scrubber 108 as a gas-liquid contact device is entrained with the unreacted silicon halide gas remaining in the purified gas obtained as described above or the purified gas. A bubbler tube 306 is provided as a bubbling mechanism for bubbling silicon dioxide particles formed in the aqueous hydrochloric acid solution. A so-called turbulent flow and a large amount of bubbles are generated around the bubbler tube 306, the aqueous hydrochloric acid solution and the purified gas collide with each other violently, and the bubbles burst, so that gas-liquid contact with high mixing efficiency is performed. . As a result, the chlorosilane remaining in the purified gas and this hydrochloric acid aqueous solution react violently to remove most of the unreacted chlorosilane gas remaining from the purified gas, so the second purified gas containing almost no chlorosilane gas. Can be obtained.

<Embodiment 2>
The chlorosilane removal plant 100 according to Embodiment 1 can suitably use exhaust gas discharged from a manufacturing process of dichlorosilane, monochlorosilane, and monosilane as a mixed gas at the starting point of the process. The contents already described in the first embodiment are not repeated in this embodiment.

  FIG. 4 is a diagram for explaining equipment of a manufacturing process 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 hydrochloric acid reaction tower 102 of the chlorosilane removal plant 100 in FIG. The concentration of chlorosilane in the mixed gas is preferably 1% or less. Generally, if the concentration of chlorosilane contained in the exhaust gas in the production process of dichlorosilane, monochlorosilane, and monosilane is 1% or less and the concentration of chlorosilane in the exhaust gas is 1% or less, the plant described later This is because chlorosilane can be treated stably by 100.

  As described in the first embodiment, the mixed gas supplied to the hydrochloric acid reaction 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. Furthermore, the moisture content is reduced to 0.5% or less through the moisture removing device. Then, the chlorosilane removal plant 100 described above 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. 4, 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, 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 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 removal 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, high-purity hydrogen gas having a small content of chlorosilane and hydrogen chloride can be separated, and industrially reusable hydrogen gas and hydrogen chloride gas can be separated. According to this method, the industrially reusable hydrogen chloride gas thus separated is again supplied to the evaporation tank 9 in the apparatus of FIG. 4, thereby reducing the amount of dangerous exhaust gas released. 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 chlorosilane removal plant 100 according to Embodiment 1 can suitably use the exhaust gas discharged from the production process of trichlorosilane as a mixed gas serving as a starting point of the process. The contents already described in the first and second embodiments are not repeated in this modification.

  FIG. 5 is a diagram for explaining the equipment for the production process of trichlorosilane used in the modification of the second embodiment. The reactor 23 in the apparatus of FIG. 5 has an inner diameter of 5 cm and a length of 80 cm, and 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. 5 is a laboratory-sized equipment. When actually operating as a commercial process, this laboratory-sized equipment is converted into a 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. Is supplied to the hydrochloric acid reaction tower 102 of the chlorosilane removal 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 chlorosilane concentration in the mixed gas is preferably 1% or less. Generally, in addition to the fact that the concentration of chlorosilane contained in the exhaust gas in the production process of trichlorosilane is 1% or less, if the concentration of chlorosilane in the exhaust gas is 1% or less, chlorosilane is reasonably used by the plant 100 described later. It is because it can process stably.

  As described in the first embodiment, the mixed gas supplied to the hydrochloric acid reaction 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. Furthermore, the moisture content is reduced to 0.5% or less through the moisture removing device. Then, the chlorosilane removal plant 100 separates hydrogen from the mixed gas to produce hydrogen gas, and the produced hydrogen gas is supplied again to the reactor 23 of the apparatus for reducing chlorosilane shown in FIG. Can be supplied as 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. 5 when reducing chlorosilane using hydrogen and chlorosilane as raw materials. Thus, the chlorosilane removal plant 100 described above 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 that can be industrially reused can be separated. 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. 5 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 mentioned above, although embodiment of this invention was described with reference to drawings, these are the illustrations of this invention, Various structures other than the above are also employable.

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.

  In the above embodiment, an aqueous hydrochloric acid solution 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. . 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 cleaning liquid sprayed on fillings such as plastic and porcelain (packed bed type), a method of dispersing cleaning liquid with a rotating body and contacting 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, a hydrochloric acid scrubber equipped with a bubbler is used as a gas-liquid contact device that generates turbulent flow. However, the invention is not particularly limited, and generally gas and liquid are preferably generated by generating turbulent flow. Any device may be used as long as it is a device that makes vigorous contact with, for example, a general cyclone, a stirrer, a cylindrical bubble column, a packed column, a porous tube bent in a spiral shape, a zigzag shape, etc. The same effects can be obtained even if a reaction apparatus, an ultrasonic atomization apparatus, or the like is used.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further, this invention is not limited to these.

<Example 1>
In this example, the case where an acidic aqueous solution was used in the hydrochloric acid reaction tower 102 (including the slurry storage tank 104) and the hydrochloric acid scrubber 108 was examined.

Using the plant 100 shown in FIG. 1 described in Embodiment 1, a mixed gas (hydrogen 84.7% (v / v), hydrogen chloride 15% (v / v), chlorosilane 0.3% (v / v), Water (0% (v / v)) was supplied to the hydrochloric acid reaction tower 102. At this time, an aqueous hydrochloric acid solution having a concentration of 20 to 35% (wt / wt) was circulated in the hydrochloric acid reaction tower 102 and the hydrochloric acid scrubber 108. Further, the hydrochloric acid reaction tower 102 was provided with a rubber lining coating 206, and an aqueous hydrochloric acid solution was sprayed from the spray 214, so that the inner wall 202 of the hydrochloric acid reaction tower 102 was always kept wet. After the operation was continued for 200 hours under the conditions of a flow rate of 10 Nm ³ / h and a pressure of 100 kPa, the gas collected from the top outlet of the hydrochloric acid reaction tower 102 was analyzed by gas chromatography. Hydrogen was found to be 91.0% (v / v) Hydrogen chloride 6.0% (v / v), chlorosilane 100 ppm (v / v), moisture 3% (v / v). In addition, the situation in the hydrochloric acid reaction tower 102 and the hydrochloric acid scrubber 108 after the operation was finished was a state in which almost no silica was adhered to the inner wall 202 except that silica was slightly adhered to the bottom. .

<Example 2>
As in Example 1, the case where an acidic aqueous solution was used in the hydrochloric acid reaction tower 102 (including the slurry storage tank 104) and the hydrochloric acid scrubber 108 was examined in this example.

  The plant 100 shown in FIG. 1 described in Embodiment 1 was operated under the same conditions as in Example 1, and the gas collected from the top outlet of the hydrochloric acid scrubber 108 was analyzed by gas chromatography. 0.5% (v / v), hydrogen chloride 20 ppm (v / v), chlorosilane less than 10 ppm (v / v), and water content 1.5% (v / v). In addition, the situation in the hydrochloric acid reaction tower 102 and the hydrochloric acid scrubber 108 after the end of the operation was such that there was almost no silica adhesion on the inner wall 202 except for the slight silica adhesion around the terrarette. It was.

<Example 3>
The case where the rubber lining coating 206 was removed from the hydrochloric acid reaction tower 102 of Example 1 was examined in this example.

  1 except that the rubber lining coating 206 is removed from the hydrochloric acid reaction tower 102 of the plant 100 shown in FIG. 1 described in the first embodiment, and the operation is performed under the same conditions as in the first embodiment. The gas collected from the top outlet of the gas was analyzed by gas chromatography. Hydrogen 91.0% (v / v), hydrogen chloride 6.0% (v / v), chlorosilane 100 ppm (v / v), moisture 3 % (V / v), and the absorption efficiency of chlorosilane was not particularly deteriorated. However, when the operation was continued for a long time, the hydrochloric acid reaction tower 102 was blocked after 150 hours from the start of operation, and the operation became impossible. When the situation inside the hydrochloric acid reaction column 102 and the hydrochloric acid scrubber 108 is investigated after the operation becomes impossible, silica having a thickness of 5 to 15 cm is deposited on the inner wall 202, and the gas and liquid flow path diameters are about 1/3. It was reduced to the following.

<Comparative Example 1>
The case where water was used instead of the hydrochloric acid aqueous solution in Example 1 was examined in this comparative example.

  The plant 100 shown in FIG. 1 described in Embodiment 1 is operated under the same conditions as in Example 1 except that water is used instead of the hydrochloric acid aqueous solution. When the gas collected from the outlet was analyzed by gas chromatography, hydrogen 93.0% (v / v), hydrogen chloride 4.0% (v / v), chlorosilane 100 ppm (v / v), water 3% ( v / v). However, when the operation was continued for a long time, the hydrochloric acid reaction tower 102 was blocked after 50 hours from the start of operation, and the operation became impossible. When the situation inside the hydrochloric acid reaction column 102 and the hydrochloric acid scrubber 108 is investigated after the operation becomes impossible, silica having a thickness of 5 to 15 cm is deposited on the inner wall 202, and the gas and liquid flow path diameters are about 1/3. It was reduced to the following. Further, the silica adhering to the inner wall 202 was in the form of water glass and could not be easily removed and peeled off.

<Comparative example 2>
The case where the spray 214 was removed from the hydrochloric acid reaction tower 102 of Example 2 was examined in this example.

  The plant 100 shown in FIG. 1 described in the first embodiment is used under the same conditions as in Example 3 except that the spray 214 is removed from the hydrochloric acid reaction tower 102. When gas collected from the top outlet was analyzed by gas chromatography, hydrogen 91.0% (v / v), hydrogen chloride 5.0% (v / v), chlorosilane 1.0% (v / v), The water content was 3% (v / v). However, when the operation was continued for a long time, the hydrochloric acid scrubber 108 was blocked after 35 hours from the start of operation, and the operation became impossible. When the situation in the hydrochloric acid reaction column 102 and the hydrochloric acid scrubber 108 is investigated after the operation becomes impossible, silica having a thickness of 5 to 15 cm is deposited on the inner wall 202, and the gas and liquid flow path diameters are about 1/3. It was reduced to the following.

<Discussion>
From the experimental results of the above Examples and Comparative Examples, in Examples 1 to 3, the chlorosilane was absorbed with an acidic solution, and the inner wall 202 of the hydrochloric acid reaction tower 102 was wetted, whereby the hydrochloric acid reaction tower 102 and It can be said that chlorosilane was efficiently absorbed while preventing the hydrochloric acid scrubber 108 from being blocked.

  That is, from the above results, by using a plant 100 as shown in FIG. 1, an aqueous hydrochloric acid solution is circulated in the hydrochloric acid reaction column 102 and the hydrochloric acid scrubber 108, so that a mixed gas containing hydrogen chloride, hydrogen and chlorosilane can be obtained. It can be seen that chlorosilane can be efficiently and stably removed. Moreover, it turns out that the blockage of the plant by the adhering of a silica particle does not occur easily.

  In Example 3, there was a problem that the hydrochloric acid reaction tower 102 was clogged after 150 hours from the start of operation, but it became clear that the absorption efficiency of chlorosilane was not particularly deteriorated, and silica adhered to the inner wall 202. And chlorosilane absorption efficiency deterioration are assumed to have no relationship. In Comparative Example 1, the silica adhering to the inner wall 202 was in the form of water glass, but the reason is assumed to be that the silica produced by the dissolution of chlorosilane in water was cured. Furthermore, in Comparative Example 2, the hydrochloric acid scrubber 108 was blocked after 35 hours from the start of operation, and the operation became impossible. This was because the absence of the spray 214 caused the absorption of chlorosilane in the hydrochloric acid reaction tower 102. Is assumed to be incomplete.

  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 (6)

In a method for removing silicon halide from a mixed gas containing hydrogen halide, hydrogen and silicon halide, an aqueous hydrochloric acid solution is flowed into a hydrochloric acid reaction tower having a rubber lining on the inner wall surface, and the inner wall surface is subjected to an aqueous hydrochloric acid solution. introducing the mixed gas while in a wet state is brought into contact with mixed gas and aqueous hydrochloric acid reacted comprises obtaining a purified gas from the gas mixture by removing at least a portion of the halogenation silicon, silicon halide Removal method. By contacting the second aqueous solution of hydrochloric acid by introducing the purified gas in hydrochloric acid scrubber, further comprising the step of obtaining a second purified gas to remove silicon halide remaining in the refining gas, according to claim 1 Of removing silicon halide. Halogenation hydrogen is hydrogen chloride, halogenation silicon, tetrachlorosilane, trichlorosilane, dichlorosilane, monochlorosilane silane, hexachlorodisilane, disiloxane, methyldichlorosilane, dimethylsilane, from the group consisting of trimethylchlorosilane The method for removing a silicon halide according to claim 1 , wherein the silicon halide is a compound of one or more selected chlorosilanes. In a plant for removing silicon halide from a mixed gas containing hydrogen halide, hydrogen and silicon halide, a hydrochloric acid reaction tower whose inner wall surface is rubber-lined , and means for introducing the mixed gas into the hydrochloric acid reaction tower ; A silicon halide removal plant , which is attached to the hydrochloric acid reaction tower and includes a spray mechanism for introducing an aqueous hydrochloric acid solution into the hydrochloric acid reaction tower and maintaining the inner wall surface of the hydrochloric acid reaction tower in a wet state by the introduced aqueous hydrochloric acid solution . The halogen according to claim 4, further comprising a hydrochloric acid scrubber connected to the hydrochloric acid reaction tower and contacting the second purified hydrochloric acid solution with the purified gas introduced to remove silicon halide remaining in the purified gas. Silicon fluoride removal plant. Hydrochloric scrubber has a bubbling mechanism for bubbling the unreacted silicon halide gas or entrained silicon dioxide particles formed by the purification gas, in said second aqueous solution of hydrochloric acid remaining in the refined gas, according to claim 5 The silicon halide removal plant described in 1 .

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