KR101754457B1 - Dispersion of silicon metal powder and process for producing chlorosilane using same - Google Patents

Abstract

The present invention provides a dispersion comprising a liquid silane compound and a metal silicon powder dispersed in a liquid silane compound. The dispersion of the metal silicon powder may be used for the production of chlorosilane, and specifically 1) mixing the dispersion with hydrogen chloride; And 2) reacting the mixture of step 1) in the presence of hydrogen.

Description

DISPERSION OF SILICON METAL POWDER AND PROCESS FOR PRODUCING CHLOROSILANE USING SAME [0002]

The present invention relates to a metal silicon particle dispersion and a method for producing chlorosilane using the same, and more particularly, to a metal silicon particle dispersion which can be used for a process capable of more efficiently producing trichlorosilane and a method for producing trichlorosilane using the same will be.

Trichlorosilane (SiHCl ₃ : TCS), which is a hydrogensilane useful as a raw material for producing a high-purity polycrystalline silicon (also referred to as polysilicon), is used for precipitating high-purity polysilicon by reacting with hydrogen at a high temperature of 1000 ° C. or higher. This reaction is mainly represented by the following reaction formulas (1) and (2).

₄ SiHCl ₃ ? Si + ₃ SiCl ₄ + 2H ₂ (1)

SiHCl ₃ + H ₂ ? Si + 3HCl (2)

The trichlorosilane used in the polysilicon precipitation reaction is generally prepared by the reaction of metal silicon with hydrogen chloride. For example, Patent Document 1 discloses a method for producing trichlorosilane by the reaction of the following reaction formula (3) by reacting metal silicon and gaseous hydrogen chloride in a fluidized bed reaction in the presence of an iron and aluminum containing catalyst using a fluidized bed reactor .

Si + 3HCl -> SiHCl ₃ + H ₂ (3)

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

3 SiCl ₄ + 2H ₂ + Si? 4 SiHCl ₃ (4)

On the other hand, Patent Document 2 discloses a method of supplying gaseous hydrogen chloride, tetrachlorosilane, and hydrogen into a fluidized bed reactor filled with metal silicon particles having a size of about 100 to 300 탆, and introducing gaseous trichloro The reaction of the formation reaction of the silane (the reaction of the formula (3)) with the reaction of the formation of the trichlorosilane in the gas phase by the reaction of the metal silicon, tetrachlorosilane and hydrogen (reaction of the formula (4) (See Fig. 1). In the above method, since the size of the metal silicon particles gradually decreases as the reaction progresses, it is necessary to replenish the metal silicon particles. However, since the replenishment timing is determined based on the temperature change of the raw material, the reaction temperature is not constant and fluctuates, resulting in a problem that the quality of the product is uneven depending on the reaction time.

Japanese Patent No. 3324922 Japanese Patent Laid-Open No. 56-73617

The present invention seeks to provide a dispersion in which metal silicon powder is stably dispersed.

The present invention also provides a method for efficiently producing chlorosilane, particularly trichlorosilane, using the above dispersion.

In order to achieve the above-described object,

The liquid silane-based compound and /

And a metal silicon powder dispersed in the silane-based compound.

A dispersion of metal silicon powder is provided.

According to another aspect of the present invention,

1) mixing the dispersion of the metal silicon powder with hydrogen chloride; And

2) reacting the mixture of step 1) in the presence of hydrogen to produce chlorosilane.

According to the present invention, there is provided a dispersion in which metal silicon fine particles are stably dispersed in a liquid silane compound, and the dispersion can be liquid-phase reacted with hydrogen chloride and hydrogen, so that the reaction mixture can be uniformly mixed. Therefore, productivity is improved when chlorosilane is produced because contact efficiency is improved.

1 is a schematic view of a fluidized bed process according to the prior art.
2 is a schematic flow diagram of a process for producing chlorosilanes according to one embodiment of the present invention.

Hereinafter, the present invention will be described in detail.

According to the present invention, there is provided a dispersion of a metal silicon powder, which comprises a liquid silane compound and a metal silicon powder dispersed in the silane compound.

According to one embodiment, the dispersion may be 0.8% / min or less when the settling velocity of the silicon powder is expressed as a change in transmittance or inverse scattering degree.

According to one embodiment, the metal silicon powder may have an average particle size of 35 mu m or less.

According to one embodiment, the metal silicon may be 0.005 to 0.05 part by weight relative to 100 parts by weight of the liquid silane compound.

According to one embodiment, the metal silicon powder may be pre-treated by a non-oxidative contact method to substantially remove the surface oxide layer.

According to one embodiment, the inter-particle distance of the metal silicon powder contained in the dispersion may be 10 to 1000 nm.

According to one embodiment, the silane-based compound may comprise tetrachlorosilane.

According to one embodiment, the tetrachlorosilane may be a by-product in the step of depositing polysilicon by the reaction of trichlorosilane and hydrogen.

The present invention also relates to

1) mixing hydrogen chloride with a dispersion of the metal silicon powder described above; And

2) reacting the mixture of step 1) in the presence of hydrogen to produce chlorosilane.

According to one embodiment, the dispersion of step 1) comprises tetrachlorosilane, and the chlorosilane produced in step 2) may comprise trichlorosilane.

According to one embodiment, the reaction of steps 1) and 2) may be a reaction proceeding in liquid phase.

According to one embodiment, the reaction of step 2) may be carried out at a pressure of 30 to 500 bar and a temperature of 200 to 1000 ° C.

According to one embodiment, it may further comprise separating the chlorosilane produced after the reaction and the silicon particles remaining after the reaction.

According to another embodiment, the metal silicon particles may be exhausted to the reaction so that the silicon particles remaining after the reaction are not subjected to the separation step.

Hereinafter, embodiments of the present invention will be described in more detail.

The dispersion of metal silicon powder according to the present invention comprises a liquid silane compound and a particulate metal silicon powder.

The dispersion according to the present invention can maintain a very stable state when the settling velocity of the silicon powder is 0.8% / min or less when expressed by a change in transmittance or back scattering degree. That is, the dispersion can be used for various purposes because the metal silicon powder is suppressed from agglomeration or precipitation and is excellent in storage stability. The settling velocity is measured by measuring transmittance and back scattering using a dispersion stability measuring device, for example, a near infrared light source of 880 nm, based on a silicon powder concentration of about 16 wt% of the dispersion, Can be measured using Turbiscan equipment.

According to one embodiment, the metal silicon powder may be pre-treated by a non-oxidative contact method such as a ball mill, a jet mill, a roller mill or the like, but is not limited thereto. The non-oxidative contact method means a method of substantially removing the surface oxide layer through physical or chemical processing under the condition that the silicon surface is not oxidized. The pretreated metal silicon powder can be removed so that the surface oxide layer is substantially removed, for example, the oxide content is 50 wt% or less. If a surface oxide layer is present, it may be undesirable for the dispersion characteristics to be removed.

The silane-based compound used in the dispersion is not particularly limited, but may be chlorosilanes such as monochlorosilane, dichlorosilane, trichlorosilane, tetrachlorosilane, etc. According to one embodiment, tetrachloro Silane. ≪ / RTI >

The silane compound may be a by-product in the step of precipitating polysilicon by the reaction of trichlorosilane and hydrogen. The silane compound may be cooled and liquefied to be used in the metal silicon dispersion have.

The metal silicon used in the dispersion is a solid particle material containing a metallic element silicon such as metallic silicon, iron silicon, or polysilicon of metallurgy. There are no particular restrictions on the content or content of impurities such as iron compounds contained in the metal silicon. However, the average particle diameter of the metal silicon particles may be 35 μm or less, or 20 μm or less, or 10 μm or less, or 8 μm or less, or 0.5 to 5 μm or so. In this specification, the terms "particle" or "powder" may be used interchangeably.

The mixing ratio of the metal silicon particles and the silane-based compound may be 1:20 to 200, or 1:50 to 150 in terms of weight ratio. In other words, the metal silicon particles may be 0.005 to 0.05 parts by weight, or 0.006 to 0.02 parts by weight, based on 100 parts by weight of the silane compound. The amount of the metal silicon particles to be charged can be appropriately selected within a range such that the distance between the metal silicon particles dispersed in the liquid silane compound is 10 to 1000 nm, or 20 to 800 nm, or 50 to 500 nm.

The dispersion according to the present invention can be used for the production of chlorosilanes.

The method for preparing chlorosilane includes: 1) mixing hydrogen chloride with the above-described dispersion of metal silicon powder; And 2) reacting the mixture of step 1) in the presence of hydrogen.

The method for producing the chlorosilane is to carry out a liquid phase reaction such that the reaction between metal silicon and hydrogen chloride, and the reaction between metal silicon and silane compound and hydrogen proceed simultaneously to produce chlorosilane. The reaction for producing the chlorosilane is such that the reaction area between the reactants is widened by reacting the silane compound with hydrogen chloride and hydrogen by using a dispersion in which the metal silicon powder is stably dispersed and uniform contact is induced to maximize the reaction efficiency .

According to a preferred embodiment of the present invention, in order to effectively utilize chlorosilane produced as a by-product in the process of producing polysilicon and the like, tetrachlorosilane as a by-product in the production process of polysilicon and the like from trichlorosilane is used May be useful in the process for producing trichlorosilane. The reaction formula of trichlorosilane according to the present invention can be expressed as follows.

_{3SiCl 4 (ℓ) + HCl (} ℓ) + 3H 2 (g) + Si (s) -> 4SiHCl 3 (ℓ) + HCI (ℓ) + H 2 (ℓ) (5)

In the above reaction formula, the reaction products may exist in a liquid state due to the internal pressure of the reactor immediately after the reaction. Specifically, the reaction may be carried out at a pressure of 30 to 500 bar and a temperature of 200 to 1,000 ° C.

It is possible to omit the step of separating the remaining metal silicon of the reaction product from the reaction product by making the metal silicon not used and remaining in the reaction.

Hereinafter, each reactant will be described in more detail with reference to a production method of trichlorosilane.

Hydrogen chloride

The hydrogen chloride used in the reaction with the metal silicon is used without limitation even if hydrogen or the like is incorporated. However, in general, chlorosilanes such as trichlorosilane, tetrachlorosilane, and dichlorosilane react with moisture because of high hydrolysis ability. Therefore, if water is contained in hydrogen chloride, the yield of the produced chlorosilane may be lowered. Therefore, it is preferable that the hydrogen chloride is in a dry state. Since hydrogen chloride is dispersed in a molecular unit, it can be sufficiently distributed around the silicon metal particles dispersed in the liquid reaction product, thereby increasing the reaction efficiency.

Hydrogen chloride is easily dissolved in the liquid dispersion according to the present invention even in the case of being supplied in the gaseous phase, and can participate in the liquid phase reaction.

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, relative to 1 mole of tetrachlorosilane, and more preferably about 0.1 mole or more, or about 0.2 mole or more, Speed, and can be set in an appropriate range depending on the type and size of the reaction apparatus.

Reactor

Since the reaction according to the present invention proceeds in a liquid phase, it is preferable to use a tubular reactor, particularly a microtubular reactor, as the reactor. The microtubular reactors are preferred for ensuring a uniform dispersion of the reactants and a sufficient residence time that the tubular inner diameter is in the range of about 10 mm or less or about 1 mm or more and the length is about 10 cm or more or about 500 cm or less . The ratio of diameter to length of the microtubular reactor may be from 1:10 to 5000, more preferably from 1:20 to 500.

The reaction temperature may be suitably determined in consideration of the material and the capability of the production apparatus. However, if the reaction temperature is higher than necessary, the selectivity of trichlorosilane is lowered and chlorosilane other than trichlorosilane such as tetrachlorosilane or dichlorosilane The amount of silane byproduct is increased. Direct chlorination (Si + 3HCl → SiHCl ₃ + H ₂ ) is an exothermic reaction. The reaction in which tetrachlorosilane reacts with hydrogen in the same reactor to form trichlorosilane is an endothermic reaction. Therefore, in consideration of the conditions of these two reactions, the reaction temperature can be variously set, and is generally set to a range of 1000 ° C or less. Preferably 800 DEG C or less, or 600 DEG C or less, or 400 DEG C or less, and may be set to a temperature of 200 DEG C or more, or 300 DEG C or more, but is not limited thereto.

As the pressure of the reactor increases, the selectivity of the chlorosilane formed increases and the reactivity of the silane compound increases, so proper control of the pressure is necessary. And is generally set in the range of 10 bar to 300 bar.

Hydrogen

In the reaction according to the invention, hydrogen helps to form chlorosilanes by reaction with silane-based compounds. As the source of hydrogen, various industrially available hydrogen may be used, and hydrogen or the like discharged during the production of polysilicon may be appropriately purified and used.

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

Alternatively, it may be in the range of 5 moles or less of hydrogen, 4 moles or less, or 3 moles or less based on 1 mole of tetrachlorosilane, and may be 1 mole or more, but the present invention is not limited thereto. It can be set in an appropriate range depending on the type and size of the reaction apparatus.

Reaction catalyst

In the process according to the present invention, a catalyst may be used to enhance the reaction efficiency but it is not necessarily used.

As the catalyst, any known catalyst component in the reaction of metallic silicon and hydrogen chloride can be used without limitation. Specific examples of such a catalyst component include a metal or a chloride of a Group VIII element such as iron, cobalt, nickel, palladium, and platinum, and a metal or a chloride such as aluminum, copper, or titanium. These catalysts may be used alone or in combination of a plurality of catalysts. The amount of the catalyst component to be used is not particularly limited as far as it improves the production efficiency of the chlorosilane, and may be suitably determined in consideration of the capability of the production apparatus and the like.

The catalyst component may be present by adding it to the reaction system, but when the metal silicon to be used contains a catalyst component such as an iron compound as an impurity, this impurity can be effectively used as a catalyst component. Needless to say, even when metal silicon containing a catalyst component as an impurity is used, there is no problem even if a catalyst component is further added into the reaction system in order to enhance reactivity between metal silicon and hydrogen chloride.

Polysilicon manufacturing

The trichlorosilane prepared from tetrachlorosilane according to the present invention can be used as a raw material for producing a high-purity polycrystalline silicon (aka polysilicon). As shown in the following reaction formula, trichlorosilane can be pyrolyzed at a high temperature of 1000 占 폚 or higher and precipitated as polysilicon. In some cases, it may be desirable to pyrolyze in the presence of hydrogen.

₄ SiHCl ₃ ? Si + ₃ SiCl ₄ + 2H ₂ (1)

SiHCl ₃ + H ₂ ? Si + 3HCl (2)

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

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

As shown in Fig. 2, 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. And the metal silicon particles 6 are added to the mixture. But may be pressurized by pump 20 as needed before it is combined with the metal silicon particles.

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

The liquid tetrachlorosilane / hydrogen chloride mixed solution 7 in which the metal silicon particles are dispersed is injected into the tubular reactor 30 and the reaction proceeds. Although not shown in the figure, the mixed liquid 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.

Further, the silicon particles dispersed in tetrachlorosilane precipitate because of high density. Therefore, the linear velocity at which the silicon-dispersed silane solution passes through the tubular reactor should be higher than the deposition rate of silicon. For example, in the case of 10 μm silicon particles, the settling rate in a tetrachlorosilane solution is about 10 mm per second. To pass the solution through a tubular reactor with an inner diameter of 10 mm without precipitation, the linear velocity of the solution is at least 10 mm Or more. Therefore, the length and the inner diameter of the tubular reactor can be determined according to the size of the silicon powder and the settling velocity.

It is preferable that the metal silicon particles are exhausted to the reaction. In this case, a process (for example, a filtering process) for separating the metal silicon particles remaining after the reaction may be omitted.

The effluent 8 from the reactor 3 is present in a liquid state by the pressure in the reactor and a pressurized or reduced pressure distillation apparatus can be used to separate the trichlorosilane and hydrogen chloride / hydrogen in the liquid reaction product. However, Liquid trichlorosilane can be easily obtained by using trichlorosilane, hydrogen chloride, and hydrogen, which are present in a liquid state immediately after the reaction, in a state in which the silane is a liquid and hydrogen chloride and hydrogen are gases.

The process according to the present invention is useful for the production of trichlorosilane using a tubular reactor in the liquid phase reaction using liquid tetrachlorosilane and also for the production of a dispersion containing metal silicon in liquid tetrachlorosilane, Can be uniformly mixed, the reaction surface area is increased, and the reaction temperature can be easily controlled, thereby maximizing the production efficiency.

Hereinafter, the present invention will be described in more detail with reference to specific examples. The following examples are intended to further illustrate the present invention, and the present invention is not limited by the following examples.

Example 1

The metal silicon powder having an average particle diameter of 5 탆 was subjected to a ball milling process for 24 hours and then subjected to an etching process using hydrogen fluoride to be pretreated to remove the oxide layer on the surface of the metal silicon. 3 g of the pretreated metal silicon powder was added to 45 g of liquid tetrachlorosilane and stirred at room temperature under atmospheric pressure for 2 minutes to prepare a dispersion.

Example 2

A dispersion was prepared in the same manner as in Example 1, except that the metal silicon powder was not pretreated.

Example 3

A dispersion was prepared in the same manner as in Example 1, except that the amount of the metal silicon powder was changed to 6 g.

Example 4

A dispersion was prepared in the same manner as in Example 2 except that a metal silicon powder having an average particle diameter of 10 탆 was used.

Comparative Example 1

A dispersion was prepared in the same manner as in Example 2, except that a metal silicon powder having an average particle size of 63 탆 was used.

Comparative Example 2

A dispersion was prepared in the same manner as in Example 2 except that a metal silicon powder having an average particle size of 150 mu m was used.

Evaluation of dispersion stability

The dispersions of Examples 1 to 4 and Comparative Examples 1 and 2 were evaluated for dispersion stability. Specifically, there are various methods for evaluating dispersion stability, but Turbiscan equipment was used. Turbiscan measured the transmittance (T%) value and the back scattering (BS%) value with the initial light source at 100% using 880nm near infrared light as a light source, It measures the change in the transmittance or inverse scattering of the whole area of the solution according to the height of the sample.

The results are shown in Table 1.

division Transmittance / back scattering change (% / min) Example 1 0.08 Example 2 0.07 Example 3 0.06 Example 4 0.21 Comparative Example 1 100 Comparative Example 2 100

According to the above results, it can be confirmed that the dispersion according to the present invention has a high degree of dispersion stability due to a small degree of change in the degree of inverse scattering and high transmittance in spite of the lapse of time.

Preparation of trichlorosilane

Trichlorosilanes were prepared using the dispersions of Examples 1 to 4 and Comparative Examples 1 and 2. The reaction conditions are as follows.

Tubular reactor (reactor specification): Sus316 Reaction tube having an inner diameter of 4 mm and a length of 300 mm

Reaction temperature: 350 degrees

Reaction pressure: 160 bar

Reaction time: 30 minutes

Dispersion supply flow rate: 20 cc / min

Hydrogen chloride feed flow rate: 10 cc / min

Hydrogen supply flow rate: 100 cc / min

The yield of trichlorosilane produced as a result of the reaction is as follows.

division yield(%) Example 1 21.3 Example 2 21.8 Example 3 24.5 Example 4 5.1 Comparative Example 1 2.2 Comparative Example 2 1.4

According to the experimental results, it was confirmed that the yield and purity of trichlorosilane were greatly improved when trichlorosilane was prepared using the dispersion according to the present invention.

10. Cooler
20. Pump
30. Tubular Reactor

Claims (14)

Liquid tetrachlorosilane and
Wherein the metal silicon powder is dispersed in the tetrachlorosilane, and the metal silicon powder has an average particle size of 8 占 퐉 or less. The dispersion of the metal silicon powder has a variation of transmittance or inverse scattering of 0.08% / min or less. Dispersion of metal silicon powder. delete delete The method according to claim 1,
Wherein the metal silicon powder is 0.005 to 0.05 parts by weight based on 100 parts by weight of the liquid tetrachlorosilane. The method according to claim 1,
Wherein the metal silicon powder has a surface oxide layer of 50 wt% or less. The method according to claim 1,
Wherein a dispersion of metal silicon powder dispersed in the dispersion has an inter-particle distance of 10 to 1000 nm. delete The method according to claim 1,
Wherein said tetrachlorosilane is by-produced in the step of precipitating polysilicon by the reaction of trichlorosilane and hydrogen. 1) mixing hydrogen chloride with the dispersion of metal silicon powder according to claim 1; And
2) reacting the mixture of step 1) in the presence of hydrogen to produce trichlorosilane. delete 10. The method of claim 9,
Wherein the reaction of steps 1) and 2) is a liquid phase reaction. 10. The method of claim 9,
Wherein the reaction of step 2) is carried out at a pressure of 30 to 500 bar and a temperature of 200 to 1000 ° C. 10. The method of claim 9,
And separating the trichlorosilane produced after the reaction and the metal silicon powder remaining after the reaction. 10. The method of claim 9,
Wherein the metal silicon powder is consumed in the reaction so that the step of separating the remaining metal silicon powder after the reaction is not performed.

Images