WO2017048094A1 - Trichlorosilane production method - Google Patents

Abstract

The present invention relates to a trichlorosilane production method using a gas-liquid-solid three-phase reaction, wherein trichlorosilane is produced by introducing a mixture, which has metal silicon particles dispersed in a liquid silane-based compound comprising tetrachlorosilane, together with hydrogen, or hydrogen and hydrogen chloride, into a tubular reactor, which alternately passes through a low-temperature region and a high-temperature region, and reacting same.

Description

Trichlorosilane Manufacturing Method

The present invention relates to a method for producing trichlorosilane, and more particularly, to a method for more efficiently preparing trichlorosilane from tetrachlorosilane using a gas-liquid-solid three-phase reaction.

This application was filed on September 15, 2015. Claiming the benefit of priority based on Korean Patent Application No. 10-2015-0130025 dated, all contents disclosed in the literature of that Korean patent application are incorporated as part of this specification.

Trichlorosilane (SiHCl ₃ : TCS) is a compound useful as a raw material for producing high purity polycrystalline silicon (aka polysilicon), and is used to precipitate high purity polysilicon by reacting with hydrogen at a high temperature of 1000 or more. This reaction is mainly represented by the following reaction formulas (1) and (2).

4SiHCl ₃ → Si + 3SiCl ₄ + 2H ₂ (1)

SiHCl ₃ + H ₂ Si + 3HCl (2)

Trichlorosilane used in the polysilicon precipitation reaction as described above is generally produced by the reaction of metal silicon and hydrogen chloride. For example, Patent Document 1 discloses a method for producing trichlorosilane by reaction of metal silicon and hydrogen chloride in the presence of iron and aluminum-containing catalyst using a fluidized bed reaction apparatus in accordance with the following reaction formula (3). .

Si + 3HCl SiHCl ₃ + H ₂ (3)

The gas produced by the reaction of metal silicon with hydrogen chloride is cooled to below -10 to condense and separate trichlorosilane, which contains other by-produced chlorosilanes in addition to trichlorosilane. Trichlorosilane is separated and recovered from the condensate containing these chlorosilanes by distillation and used as a raw material for polysilicon production. In addition, tetrachlorosilane (SiCl ₄ : STC) separated by distillation is mainly converted into trichlorosilane (TCS) by the reaction of the following formula (4) and reused in the production of polysilicon.

3SiCl ₄ + 2H ₂ + Si 4SiHCl ₃ (4)

On the other hand, Patent Literature 2 supplies metal silicon particles, hydrogen chloride, tetrachlorosilane, and hydrogen having a size of about 100 to 300 µm into a fluidized bed reactor filled with metal silicon particles, and trichloro by metal silicon and hydrogen chloride in the reaction vessel. Preparation of trichlorosilane which advances the production | generation reaction of silane (reaction of Formula (3)) and the production | generation reaction of trichlorosilane (reaction of Formula (4)) by reaction with metal silicon, tetrachlorosilane, and hydrogen simultaneously. A method has been proposed (see FIG. 1). In the above method, since the size of the metal silicon particles gradually decreases as the reaction proceeds, the metal silicon particles need to be replenished. However, since the replenishment time is determined by looking at the temperature change of the raw material, the reaction temperature is not constant and fluctuates, and there is a problem in that the quality of the product is uneven according to the reaction time.

In addition, the existing process using a fluidized bed reactor (FBR) is a simple solid-phase reaction process in which the solid metal silicon and the liquid tetrachlorosilane react, there is a limit in improving the conversion rate.

Therefore, there is a demand for a method for more efficiently converting chlorosilanes, particularly tetrachlorosilane, into trichlorosilane in the exhaust gas of the process for producing polysilicon from trichlorosilane and reused.

[Patent Documents]

(Patent Document 1) Japanese Unexamined Patent Publication No.3324922

(Patent Document 2) Japanese Unexamined Patent Publication No. 56-73617

The present invention seeks to provide a method for more efficiently converting chlorosilanes, particularly tetrachlorosilane, into trichlorosilane in the exhaust gas of the process for producing polysilicon from trichlorosilane.

In addition, to provide a trichlorosilane production apparatus that can implement the method.

The present invention to achieve the above technical problem,

In a tubular reactor that alternately passes through the low temperature zone and the high temperature zone,

Provided is a trichlorosilane production method comprising producing trichlorosilane by injecting a mixture of metal silicon particles dispersed in a liquid silane compound including tetrachlorosilane together with hydrogen or hydrogen and hydrogen chloride. .

In the low temperature region, the tetrachlorosilane reacts in a liquid state, and in the high temperature region, the tetrachlorosilane reacts in a gaseous state.

The low temperature region reaction may be carried out under a pressure of 100 ° C or more and 320 ° C or less, 10 bar or more and 550 bar or less.

The high temperature region reaction may be carried out under a pressure of 300 ° C or more and 600 ° C or less, 10 bar or more and 550 bar or less.

The metal silicon particles preferably have a weight average particle diameter of about 35 microns or less.

The weight ratio of the metal silicon particles and the liquid silane compound may be about 1:20 to about 1: 200.

The liquid silane-based compound may be a byproduct of polysilicon precipitation process by trichlorosilane pyrolysis.

The reaction may be carried out under the condition that the weight ratio of hydrogen and tetrachlorosilane is 1:20 or more and 1: 200 or less.

The reaction may also be carried out under the condition that the weight ratio of hydrogen chloride and tetrachlorosilane is 1: 0 or more to 1:10 or less.

According to one embodiment, after the reaction may further comprise the step of separating the silicon particles remaining in the product.

According to another embodiment, the metal silicon particles may be exhausted in the reaction so that they do not remain in the product after the reaction.

The trichlorosilane prepared according to the above-described method may be used in a process of thermally decomposing polysilicon.

The present invention also to achieve another technical problem,

Silane-based compound supply means including liquid tetrachlorosilane;

Optionally, hydrogen chloride supply means;

An apparatus for mixing a silane compound and hydrogen chloride supplied from the respective supply means to form a liquid mixture;

Metal silicon particle supply means for supplying and dispersing metal silicon particles in the liquid mixture;

A tubular reactor supplied with a mixture in which metal silicon particles are dispersed and designed to alternately pass through a low temperature region and a high temperature region;

Hydrogen gas supply means for supplying hydrogen gas to the reactor; And

It provides a trichlorosilane manufacturing apparatus having a means for recovering trichlorosilane from the product discharged from the tubular reactor.

According to one embodiment, the metal silicon particles may be supplied in a form dispersed in a liquid silane compound.

In addition, the apparatus may be further provided with a raw material storage tank equipped with a stirrer for storing the mixed solution in which the metal silicon particles are dispersed.

In addition, according to one embodiment, the linear velocity of the mixed solution in which the metal silicon particles are dispersed is supplied to the tubular reactor may be adjusted to a range such that precipitation of the metal silicon particles does not occur.

According to the present invention, in a continuous process using a tubular reactor, the reaction temperature and pressure are controlled to change the tetrachlorosilane into a liquid phase or a gas phase, thereby allowing both metal silicon particles and liquid-solid or gas-solid domain reactions to achieve contact efficiency. As a result, the productivity of trichlorosilane can be increased. In addition, since the use of a microtubular reactor rather than a fluidized bed reactor facilitates thermal control, it is possible to minimize side reactions and improve product quality and productivity.

1 is a schematic diagram of a fluidized bed process according to the prior art.

2 is a graph showing the boiling point and vapor pressure relationships of tetrachlorosilane (STC) and trichlorosilane (TCS).

Figure 3 schematically illustrates the reaction principle of the metal silicon particles and tetrachlorosilane in the low temperature region and high temperature region.

4 is a schematic flowchart of a trichlorosilane production process according to the present invention.

FIG. 5 schematically illustrates the reaction in the low temperature region and the high temperature region of the tubular reactor shown in FIG. 4.

As the invention allows for various changes and numerous embodiments, particular embodiments will be illustrated in the drawings and described in detail in the written description. However, this is not intended to limit the present invention to specific embodiments, it should be understood to include all transformations, equivalents, and substitutes included in the spirit and scope of the present invention. In the following description of the present invention, if it is determined that the detailed description of the related known technology may obscure the gist of the present invention, the detailed description thereof will be omitted.

According to the present invention, a trichlorosilane is reacted by injecting a mixture of metal silicon particles dispersed in a liquid silane compound containing tetrachlorosilane into hydrogen or hydrogen and hydrogen chloride in a tubular reactor that alternately passes through a low temperature region and a high temperature region. It provides a method for producing trichlorosilane, characterized in that the production of rosilane.

That is, the present invention is a method of generating a phase change (liquid-gas) of the liquid raw material by dividing the temperature zone into a low temperature zone and a high temperature zone in the tubular reactor in a continuous process.

2 representatively shows the relationship between the boiling point and the vapor pressure of tetrachlorosilane (STC) and trichlorosilane (TCS). As can be seen in Figure 2 it can be seen that the phase inversion of the liquid reaction raw material containing tetrachlorosilane by appropriately adjusting the reaction temperature and pressure. For example, assuming that the internal pressure of the reactor is 200 bar, if the temperature is lower than 400 ° C., the tetrachlorosilane (STC) becomes a liquid to transfer the silicon powder. On the contrary, when the temperature is higher than 400 ° C., the tetrachlorosilane becomes a gas, so that the tetrachlorosilane wetted on the surface of the silicon powder is vaporized, so that the silicon powder can be in surface contact with hydrogen chloride gas or hydrogen gas, thereby increasing the reactivity of the silicon powder.

The reaction raw material is a state in which solid (metal silicon particles, etc.), liquid (tetrachlorosilane-containing silane compound), and gas (hydrogen or hydrogen chloride) are all mixed. The liquid reaction raw material becomes a gaseous reactant or a liquid phase depending on the reaction temperature. It serves as a fluid conveyance.

The conversion reaction according to the present invention may be subjected to the following reaction process.

3SiCl ₄ (l) + 2H ₂ (g) + Si (s)-> 4SiHCl ₃ (l) + H ₂ (g) + HCl (g)

3 schematically shows the principle of reaction in the low temperature region and the high temperature region.

First, in the low temperature region, the liquid raw material is transferred to a wet state on the surface of the solid raw material, and trichlorosilane, which is a product, may also be present as a liquid and transported together.

According to the present invention, since the whole system is a continuous tubular reactor, the reaction must proceed while the reactants are continuously transferred. If all of the reactants are gas and solid (silicon powder), the gas and solid are not transported, so to transfer silicon powder by liquefying tetrachlorosilane with relatively low vapor pressure in the gas to transport solid silicon powder. . That is, the liquid tetrachlorosilane in the low temperature region and the tetrachlorosilane in the gas phase in the high temperature region have a completely different role in the tubular reactor.

After being transferred to the high temperature region, tetrachlorosilane (STC) moistened in the metal silicon particles is vaporized to react with other reaction gases (hydrogen or hydrogen chloride) on the metal silicon particles.

The low temperature region should be at least 100 ° C. and the high temperature region should be less than 600 ° C. at maximum. If the temperature difference between the high temperature region and the low temperature region is too large, a phenomenon occurs in which the temperature boundary between the two regions is widened, which may reduce the effect of each region. The low temperature region and the high temperature region may vary depending on the reaction pressure inside the reaction tube. For example, if the pressure inside the reaction tube is 50 bar, the low temperature range is at least 100 ° C and less than 220 ° C, and the high temperature range is at least 260 ° C and less than 600 ° C. If the pressure inside the reaction tube is 100 bar, the low temperature range is 100 ° C or more and less than 270 ° C, and the high temperature range is 320 ° C or more and less than 600 ° C. If the pressure inside the reaction tube is 150 bar, the low temperature range is 100 ° C or more and less than 320 ° C, and the high temperature range is 370 ° C or more and less than 600 ° C.

The region of the reaction temperature according to the more detailed pressure is in accordance with the vapor pressure curve of tetrachlorosilane and trichlorosilane of FIG. 2. The low temperature region follows the vapor pressure curve of trichlorosilane where both the reactant tetrachlorosilane and the product trichlorosilane can be liquid, and the high temperature region follows the vapor pressure curve of tetrachlorosilane having a relatively low vapor pressure.

The gas-liquid-solid three-phase reaction is difficult because the contact site on the solid surface is blocked by the liquid, which induces a solid-gas reaction by adjusting the reaction conditions to increase the reaction efficiency. Can be.

Hereinafter, each reactant will be described in more detail.

Tetrachlorosilane

The tetrachlorosilane used in the reaction according to the present invention is not particularly limited, but tetrachloroproduced from trichlorosilane in the process of producing polysilicon from trichlorosilane in order to facilitate the effective use of the tetrachlorosilane produced by the production process of polysilicon and the like. Silanes may be used.

Metal silicon particles

By adjusting the size of the metal silicon particles to a size of 35 microns or less, the contact area of the tetrachlorosilane and the silicon particles increases to increase the reaction site, thereby increasing the reaction rate to increase the productivity of the trichlorosilane. Since the size of the metal silicon particles gradually decreases, the silicon particles may be completely exhausted after a certain reaction time.

In the present invention, the metal silicon particle particles are used to uniformly disperse the silicon metal particles in the liquid tetrachlorosilane to prevent aggregation and precipitation and to increase the contact area between the silicon metal particles and the tetrachlorosilane.

The metal silicon used for the reaction is a solid particle material containing a silicon element in a metal state such as metallurgical metal silicon, silicon iron, or polysilicon. Moreover, also about an impurity, such as an iron compound contained in metal silicon, there is no restriction | limiting in particular in the component and content. However, in the present invention, the metal silicon particles or powders refer to particles having a weight average particle diameter of about 35 microns or less. The average particle diameter of the metal silicon may be about 30 microns or less, or about 25 microns or less, or about 10 microns or less, or about 5 microns or less, and about 0.1 microns or more, or about 0.5 microns or more.

The mixing ratio of the metal silicon particles and the tetrachlorosilane may be about 200 parts by weight or less, or about 150 parts by weight or less, about 20 parts by weight or more, or about 50 parts by weight or more based on 1 part by weight of the metal silicon particles.

The amount of the metal silicon particles to be added may be appropriately selected in a range such that the distance between the metal silicon particles dispersed in the tetrachlorosilane is about 1000 nm or less, or about 500 nm or less, or about 10 nm or more or about 50 nm or more.

Preferably, the step of separating the metal silicon of the fine powder remaining in the reaction from the reaction product by eliminating all of the metal silicon particles in the reaction and remaining.

Hydrogen

In the reaction according to the invention hydrogen reacts with tetrachlorosilane to help form trichlorosilane. As the hydrogen source, various industrially available hydrogens can be used, and hydrogen discharged in the process of producing polysilicon can be appropriately purified and used.

The weight ratio of hydrogen and tetrachlorosilane may be 1:20 to 200, preferably 1:50 to 100.

Or, it may be in the range of 5 mol or less, 4 mol or less, or 3 mol or less, and 1 mol or more, with respect to 1 mol of tetrachlorosilane, but the present invention is not limited thereto. It may be set in an appropriate range depending on the type or size of the reaction device.

Hydrogen chloride

Hydrogen chloride used for the reaction with the metal silicon can be selectively added, and even if hydrogen or the like is mixed, it is used without any limitation. However, chlorosilanes, such as trichlorosilane, tetrachlorosilane, and dichlorosilane, generally react with water because of their high hydrolyzability. For this reason, when water contains hydrogen chloride, there exists a possibility that the yield of the produced trichlorosilane may be reduced. Therefore, it is preferable that this hydrogen chloride is in a dry state. Since the hydrogen chloride is dispersed in a molecular unit, it can be sufficiently distributed around the silicon nanoparticles dispersed in the liquid reactant, thereby increasing the reaction efficiency.

The weight ratio of hydrogen chloride and tetrachlorosilane may be 1: 0 to 10 or less, preferably 1: 0 to 5 or less.

Or about 1 mole or less, or about 0.8 mole or less, or about 0.5 mole or less per mole of tetrachlorosilane, and may also be about 0.1 mole or more, or about 0.2 mole or more, but is not limited thereto. Along with the speed, it can be set in an appropriate range depending on the type and size of the reaction apparatus.

Reactor

Since the reaction according to the invention proceeds in the liquid phase, it is preferable that the reaction apparatus uses a tubular reactor, in particular a microtubular reactor. Microtubular reactors have a tube inner diameter in the range of about 10 mm or less or about 1 mm or more and a length in the range of about 10 cm or more or about 500 cm or less is preferred to ensure uniform dispersion of reactants and sufficient residence time. . The ratio of diameter to length of the fine tubular reactor may be 1: 10 to 5000, more preferably 1: 20 to 500.

What is necessary is just to determine reaction temperature suitably in consideration of the material, capability, etc. of a manufacturing apparatus, but when reaction temperature is higher than necessary, the selectivity of trichlorosilane will fall, and chloro other than trichlorosilane, such as tetrachlorosilane and dichlorosilane, The amount of silane by-products increases. In addition, direct chlorination (Si + 3HCl → SiHCl ₃ + H ₂ ) is an exothermic reaction. In the same reactor, the reaction of tetrachlorosilane with hydrogen to generate trichlorosilane is an endothermic reaction. Therefore, the reaction temperature can be set in various ways in consideration of the conditions of these two reactions.

In particular, in the present invention, it is important to induce a phase inversion of the liquid reaction raw material, so that the tubular reactor alternately passes through the high temperature region and the low temperature region.

The low temperature region is generally set in the range of 320 ° C or lower. Preferably, the temperature may be set to 300 ° C. or less, and may be set to 100 ° C. or more, or 150 ° C. or more, but is not limited thereto. As the pressure in the reactor increases, the selectivity of the trichlorosilane increases and the reactivity of the tetrachlorosilane also increases, so proper control of the pressure is required. It must be set at a pressure above about 10 bar, or below about 550 bar, as it must maintain a liquid phase.

The high temperature zone should be a condition under which each reactant, silicon powder, hydrogen, hydrogen chloride, and tetrachlorosilane (STC) react to form trichlorosilane (TCS) .In this case, the STC should be in the gas phase, so the reaction conditions are below STC vapor pressure. Should be. If the STC is in a liquid state, the surface of the silicon powder is wet, so hydrogen chloride cannot react with the surface of the silicon. Therefore, all liquid STC must be vaporized.

Since the apparatus according to the present invention is a continuous tubular reactor, the pressures in both the high and low temperature regions are the same unless a separate device such as a special pressure controller (for example, a back pressure regulator) is installed separately. Therefore, the only variable that can convert the phase of STC into liquid-phase phase is the temperature, so it can be divided into low-temperature (liquid) -high temperature (gas) according to the steam pressure conditions of the STC. In the case of the high temperature region, for example, when the internal pressure of the tubular reactor is 200 bar, the temperature at which STC exhibits gas phase-liquid phase transition is about 400 ° C., so the temperature in the high temperature region will be 400 ° C. or higher, and the low temperature region will be 400 ° C. or lower. Will be. For accurate phase separation, it is preferable to control the high temperature region to 450 ° C. or higher temperature and the low temperature region to 350 ° C. or lower so that the reaction temperature of the high temperature region and the low temperature region differs by a predetermined temperature or more. However, if the temperature difference between the two areas is too large, not only temperature control will be difficult, but also the durability of the equipment will be affected. Therefore, it is necessary to set the temperature considering all the conditions as well as the reactivity. For example, the reaction temperature in the high temperature range is suitably about 300 ° C to about 600 ° C, more preferably about 350 ° C to 500 ° C.

Reaction catalyst

Catalysts may be used in the process according to the invention to improve the reaction efficiency, but are not required to be used. The present invention enables efficient reaction without a catalyst.

As the catalyst, those known as catalyst components in the reaction of metal silicon with hydrogen chloride can be used without limitation. As such a catalyst component, metals, such as aluminum, copper, titanium, and chlorides, such as metal of group VIII elements, such as iron, cobalt, nickel, palladium, and platinum, and its chloride, are mentioned specifically ,. These catalysts can be used alone or in combination of a plurality of catalysts. The amount of the catalyst component used is not particularly limited as long as the amount of trichlorosilane is improved in production efficiency, and may be appropriately determined in consideration of the capability of the production apparatus and the like.

In addition, although the said catalyst component can be made exist by adding in a reaction system, when the metal silicon used contains catalyst components, such as an iron compound, as an impurity, this impurity can be used effectively as a catalyst component. Of course, even in the case of using metal silicon containing the catalyst component as an impurity, there is no problem even if the catalyst component is further added into the reaction system in order to increase the reactivity between the metal silicon and hydrogen chloride.

Polysilicon  Produce

Trichlorosilane prepared from tetrachlorosilane according to the present invention can be used as a raw material for producing high purity polycrystalline silicon (aka polysilicon). Trichlorosilane may be pyrolyzed at high temperature of 1000 ° C. or higher to precipitate polysilicon, as shown in the following scheme. In some cases it may be desirable to pyrolyze in the presence of hydrogen.

4SiHCl ₃ → Si + 3 SiCl ₄ + 2H ₂ (1)

SiHCl ₃ + H ₂ Si + 3 HCl (2)

Polysilicon precipitation reaction using trichlorosilane is well known in the art, and thus description of specific process conditions is omitted.

Trichlorosilane production apparatus according to the present invention

Silane-based compound supply means including liquid tetrachlorosilane;

Optionally, hydrogen chloride supply means;

An apparatus for mixing a silane compound and hydrogen chloride supplied from the respective supply means to form a liquid mixture;

Metal silicon particle supply means for supplying and dispersing metal silicon particles in the liquid mixture;

A tubular reactor supplied with a mixture in which metal silicon particles are dispersed, and designed to alternately pass through a high temperature region and a low temperature region;

Hydrogen gas supply means for supplying hydrogen gas to the reactor; And

A means for recovering trichlorosilane from the product exiting the tubular reactor may be provided.

More specifically, in the hydrogen gas supply means, the hydrogen gas flow rate may be adjusted by a mass flow controller (MFC). Hydrogen gas discharged by the pressure of the hydrogen feed bomb is supplied to the reactor by controlling the flow rate through the MFC.

In the hydrogen chloride supply means, the hydrogen chloride gas may be regulated by MFC. The hydrogen chloride gas discharged by the pressure of the hydrogen chloride bombe is dissolved in the tetrachlorosilane solution and fed to the reactor together with the tetrachlorosilane solution.

According to one embodiment, the tetrachlorosilane solution in which hydrogen chloride is dissolved may be stored in the raw material storage tank.

The raw material storage tank has a double jacket to maintain a temperature of 10 ° C. or less in consideration of the boiling point of the raw material, so that the low temperature is preferably maintained by the cooler.

The tank is equipped with a device capable of adding silicon powder so that the silicon powder can be injected and dispersed in a tetrachlorosilane solution.

The tank may be provided with a space of the partition wall to prevent outside air from flowing into the container, the space of the partition is connected to the vacuum pump, and prevents the introduction of external oxygen and moisture when the silicon powder is injected.

In order to maintain a uniform dispersion state of the silicon particles, the raw material storage tank is preferably equipped with a stirrer. The stirrer rotates from about 50 rpm to about 500 rpm to inhibit the precipitation of silicon particles.

There may be two or more of these raw material storage tanks, and the pipes are connected so that when the raw material stored in the first tank is exhausted, the second tank can be continuously injected.

The mixture in which the silicon particles are dispersed is continuously injected from the raw material storage tank into the tubular reactor by a pump for liquid transfer. The pump for liquid transfer may have a discharge pressure of about 100 bar or more, more preferably about 200 bar or more. Solid silicon powder must also be transported with the solution, and a particular type of pump (high pressure pump) is suitable, considering the reactivity of the tetrachlorosilane solution with water and oxygen.

The raw material injected into the tubular reactor using a high pressure pump passes through the tubular reactor which alternately passes through the low temperature region and the high temperature region. At this time, the reaction temperature in the low temperature region is appropriately selected from the range of about 100 ℃ to about 320 ℃, more preferably from about 150 ℃ to 300 ℃. The reaction temperature in the high temperature range is suitably selected in the range of about 300 ° C to about 600 ° C, more preferably about 350 ° C to 500 ° C.

After the reaction is completed, all of the products pass through the rear end of the tubular reactor cooled to 10 ° C. or lower, and are recovered in the collecting device. At this time, unreacted hydrogen, hydrogen chloride gas, and chlorine gas are separated from the liquid by a collecting device, and the liquid is transferred to another storage container through another conveying device.

Hereinafter, an embodiment according to the method of the present invention will be described in detail with reference to the drawings.

4 and 5 schematically show an apparatus according to an embodiment of the invention.

As shown in FIG. 4, the gaseous tetrachlorosilane (1) passes through the cooler (10) and is converted into liquid tetrachlorosilane (2). Liquid tetrachlorosilane (2) is combined with hydrogen chloride (4), and hydrogen chloride is dissolved in tetrachlorosilane to form a liquid phase. Metal silicon particle 6 is thrown in and mix | blended here. It may be pressurized by the pump 20 as needed before blending with the metallic silicon particles, but is not limited thereto.

Hydrogen gas may be added to any of the steps described above. For example, the liquid tetrachlorosilane (2) may be added before or after blending with the hydrogen chloride (4) or before or after dispersing the metal silicon particles.

The liquid tetrachlorosilane / hydrogen chloride mixture 7 in which the metal silicon particles are dispersed is injected into the tubular reactor 30 to proceed with the reaction. Although not shown in the drawings, the mixed solution may be stored in a raw material storage tank equipped with a stirrer as described above. The reactor 30 is provided with heating means (not shown) for providing an optimum reaction temperature, and can be designed to provide sufficient residence time and contact area.

As shown in FIG. 5, the tubular reactor is designed to alternately pass through the low temperature region and the high temperature region.

The metal silicon particles (solid), tetrachlorosilane (liquid or gas), hydrogen (gas) and hydrogen chloride (gas) which are injected as reaction raw materials are solid-liquid-gas mixtures, and the liquid reaction raw materials are solid metals in the low temperature region. The silicon particles are impregnated and transferred to the high temperature region. In the high temperature region, the solid phase-phase reaction may proceed while the liquid reaction raw material wetted on the surface of the metal silicon particles is vaporized. Thereafter, the liquid reaction raw material is wet again with the solid reaction raw material while being moved to the low temperature region again, and is transferred to the high temperature region to proceed with the reaction. By repeating this process, the conversion efficiency can be increased.

In addition, silicon particles dispersed in tetrachlorosilane are precipitated because of their high density. Therefore, the linear velocity when the silicon-dispersed silane solution passes through the tubular reactor should be higher than the precipitation rate of silicon. For example, in the case of 10 μm silicon particles, for example, the precipitation rate in a tetrachlorosilane solution is about 10 mm per second, and if the solution passes through a 10 mm inner tubular reactor without precipitation, the linear velocity of the solution is at least 10 mm per second. Should be at least Therefore, the length and inner diameter of the tubular reactor may be determined according to the size and precipitation rate of the silicon powder.

According to a preferred embodiment, the metal silicon particle particles can be exhausted to the reaction, in this case, a process for separating the metal silicon particles remaining after the reaction (for example, filtering process) can be omitted.

The discharge 8 from the reactor 3 is in the liquid phase at the pressure inside the reactor, although it is also possible to use a pressurized or reduced pressure distillation apparatus to separate trichlorosilane and hydrogen chloride / hydrogen in the liquid reactant, but at room temperature By using silane as a liquid and hydrogen chloride and hydrogen as a gas, trichlorosilane, hydrogen chloride and hydrogen, which exist in a liquid state immediately after the reaction, can be easily obtained by storing the trichlorosilane in a pressure-released state.

The method according to the present invention proceeds using a tubular reactor in a liquid phase reaction using liquid tetrachlorosilane, and also reacts the metal silicon particles so that the reactants can be uniformly mixed, the reaction surface area is increased, and the reaction temperature is easily controlled. The production efficiency can be maximized.

Hereinafter, specific embodiments of the present invention will be described. However, the following examples are merely one embodiment of the present invention and the scope of the present invention is not limited thereto.

Example  One

Metallic silicon (purity 98%, average particle diameter) while maintaining the internal pressure at 160 bar at a reaction temperature of 350 ° C. The reaction was carried out by introducing a dispersion obtained by dispersing 3 µm) in tetrachlorosilane at 1% by weight, hydrogen chloride and hydrogen at the flow rates as shown in Table 1, respectively. The temperature of the low temperature zone and the high temperature zone and the pressure conditions inside the reaction tube were as follows.

Low temperature range: 260 ℃, 100bar

High temperature range: 360 ℃, 100bar

Example	Raw material amount (g / min)				Product composition (mol%)			Residual Metal Silicon (g)
	STC	HCl	H 2	Si	TCS	STC	HCl
1-1	14.9	0.15	0.1	0.15	16	47	37	0.045
1-2	11.2	0.15	0.1	0.15	6	78	16	0.121
1-3	14.9	0.15	0.1	0.3	21	41	38	0.276
1-4	14.9	0	0.1	0.15	5	81	14	0.086

Example  2

Low temperature zone reaction temperature is 210 ℃. The reaction temperature in the high temperature zone was 300 ° C., and the reaction was carried out in the same manner as in Example 1-1 except that the STC was in the liquid phase even in the high temperature zone. Mol%.

Comparative example  One

The reaction temperature in the low temperature region was 320 ° C., the reaction temperature in the high temperature region was 400 ° C. The reaction was carried out in the same manner as in Example 1-1 except that the STC was brought into the gas phase even at a low temperature region with an internal pressure of 60 bar. The TCS content in the resulting product was 7 mol%, but the reactant silicon was deposited in the tubular reactor, making continuous processing impossible.

According to the present invention, in a continuous process using a tubular reactor, the reaction temperature and pressure are controlled to change the tetrachlorosilane into a liquid phase or a gas phase, thereby allowing both metal silicon particles and liquid-solid or gas-solid domain reactions to achieve contact efficiency. As a result, the productivity of trichlorosilane can be increased. In addition, since the use of a microtubular reactor rather than a fluidized bed reactor facilitates thermal control, it is possible to minimize side reactions and improve product quality and productivity.

Claims (16)

1. In a tubular reactor that alternately passes through the low temperature zone and the high temperature zone,

   A trichlorosilane production method comprising producing trichlorosilane by injecting a mixture of metal silicon particles dispersed in a liquid silane compound including tetrachlorosilane together with hydrogen or hydrogen and hydrogen chloride.
2. The method of claim 1,

   The tetrachlorosilane reacts in a liquid state in the low temperature region, and the tetrachlorosilane reacts in a gaseous state in the high temperature region.
3. The method of claim 1,

   The low temperature region reaction is carried out under a pressure of 100 ° C or more and 320 ° C or less, 10 bar or more and 550 bar or less, trichlorosilane production method.
4. The method of claim 1,

   The high temperature zone reaction is carried out under a pressure of 300 ° C or more and 600 ° C or less, 10 bar or more and 550 bar or less, trichlorosilane production method.
5. The method of claim 1,

   The metal silicon particles have a weight average particle diameter of less than 35 microns, trichlorosilane manufacturing method.
6. The method of claim 1,

   The weight ratio of the metal silicon particles and the liquid silane compound is 1: 20 to 1: 200, trichlorosilane production method.
7. The method of claim 1,

   The liquid silane-based compound is a trichlorosilane production method that is a by-product of the polysilicon precipitation process by trichlorosilane pyrolysis.
8. The method of claim 1,

   The weight ratio of hydrogen and tetrachlorosilane is 1:20 to 200, trichlorosilane manufacturing method.
9. The method of claim 1,

   The weight ratio of hydrogen chloride and tetrachlorosilane is 1: 0 to 10, trichlorosilane production method.
10. The method of claim 1,

    Separating the silicon particles remaining in the product after the reaction, trichlorosilane production method.
11. The method of claim 1,

    The metal silicon particles are exhausted in the reaction, characterized in that do not remain in the product after the reaction, trichlorosilane production method.
12. A method for producing polysilicon comprising the step of pyrolyzing trichlorosilane prepared by any one of claims 1 to 11 to precipitate polysilicon.
13. Silane-based compound supply means including liquid tetrachlorosilane;

    Optionally, hydrogen chloride supply means;

    An apparatus for mixing a silane compound and hydrogen chloride supplied from the respective supply means to form a liquid mixture;

    Metal silicon particle supply means for supplying and dispersing metal silicon particles in the liquid mixture;

    A tubular reactor supplied with a mixture in which the metal silicon particles are dispersed and designed to pass alternately through the low temperature region and the high temperature region;

    Hydrogen gas supply means for supplying hydrogen gas to the reactor; And

    Trichlorosilane production apparatus having a means for recovering trichlorosilane from the product discharged from the tubular reactor.
14. The method of claim 13,

    The metal silicon particles are supplied in the form of dispersed in a liquid silane compound, trichlorosilane manufacturing apparatus.
15. The method of claim 13,

    It further comprises a raw material storage tank equipped with a stirrer for storing the mixed solution in which the metal silicon particles are dispersed, trichlorosilane manufacturing apparatus.
16. The method of claim 13,

    The linear velocity at which the mixed solution in which the metal silicon particles are dispersed is supplied to the tubular reactor is adjusted to a range such that precipitation of the metal silicon particles does not occur, the trichlorosilane manufacturing apparatus.

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