JP2013112589A - Method and apparatus for producing trichlorosilane - Google Patents

Abstract

A trichlorosilane production method and production apparatus capable of smoothly removing a copper-based catalyst and producing high-purity trichlorosilane.
A method for producing trichlorosilane by reacting a mixed gas containing metal silicon, tetrachlorosilane, and hydrogen in the presence of a copper-based catalyst, the heating step for heating the mixed gas to a temperature at which the mixed gas can be reacted. A conversion reaction step of generating a reaction gas containing trichlorosilane by reacting the mixed gas heated by the heating step with the metal silicon; and a dust removal step of removing solids contained in the reaction gas. A heat exchanging step of exchanging heat between the reaction gas and the mixed gas and sending the mixed gas to the heating step; and a catalyst for removing a copper-based catalyst deposited in the reaction gas cooled by the heat exchanging step A removal step.
[Selection] Figure 1

Description

  The present invention relates to a method and an apparatus for producing trichlorosilane, which converts tetrachlorosilane to trichlorosilane.

High-purity polycrystalline silicon used as a semiconductor material is mixed with trichlorosilane (silicon trichloride: SiHCl ₃ : TCS) and hydrogen as a raw material, and this mixed gas is introduced into a reaction furnace and brought into contact with a red hot silicon rod. And produced by the method (Siemens method) of depositing polycrystalline silicon on the surface of the silicon rod by hydrogen reduction or thermal decomposition of trichlorosilane at high temperature.
In the production of polycrystalline silicon, the reactor exhaust gas contains unreacted trichlorosilane and hydrogen, by-product tetrachlorosilane (silicon tetrachloride: SiCl ₄ : STC), hydrogen chloride, and the like. For this reason, trichlorosilane and tetrachlorosilane are recovered from the exhaust gas after the reaction, and the tetrachlorosilane is converted to trichlorosilane and reused as a raw material for silicon deposition.

  In Patent Document 1, silicon particles (metal silicon), tetrachlorosilane, and hydrogen are converted to trichlorosilane by reacting at 400 to 700 ° C. in a fluidized bed of a conversion furnace in the presence of a catalyst containing copper silicide. Technology is disclosed. In the middle of the reaction gas discharge pipe provided in the conversion furnace, a fine particle recovery cyclone (cyclone) is installed, and the fine particles in the fluidized bed are separated and discharged through the reaction gas discharge pipe.

Japanese Patent Laid-Open No. 10-29813

An example of a catalyst used for converting tetrachlorosilane to trichlorosilane is copper-based catalyst copper chloride (CuCl). The gas generated by this conversion reaction contains, in addition to the generated trichlorosilane, metal chlorides and polymers generated by the reaction of impurities in unreacted fine powder and metal silicon, and copper chloride as a metal catalyst. Of these, the solids are recovered with a cyclone. However, even the solid content is smaller than the cyclone classification ability or the gas content passes through the cyclone and flows downstream.
A purification distillation system for increasing the purity of trichlorosilane is provided downstream of the conversion furnace. However, when copper chloride is introduced into the purification distillation system, there is a risk of causing circulation pump wear, clogging troubles, and the like. In addition, the purification distillation system contains a polymer, and there is a problem that the scale of the treatment equipment increases when it is necessary to treat the copper chloride contained in the polymer treatment liquid. .

  This invention is made | formed in view of such a situation, The copper-based catalyst can be removed smoothly and the manufacturing method and manufacturing apparatus of trichlorosilane which can manufacture a highly purified trichlorosilane are provided. For the purpose.

  The method for producing trichlorosilane of the present invention is a method for producing trichlorosilane by reacting a mixed gas containing metal silicon, tetrachlorosilane and hydrogen in the presence of a copper-based catalyst, wherein the mixed gas is brought to a temperature at which the mixed gas can be reacted. A heating step for heating, a conversion reaction step for generating a reaction gas containing trichlorosilane by reacting the mixed gas heated by the heating step with the metal silicon, and removing solids contained in the reaction gas A dust removal step, a heat exchange step of exchanging heat between the reaction gas and the mixed gas and sending the mixed gas to the heating step, and a copper system precipitated in the reaction gas cooled by the heat exchange step And a catalyst removal step for removing the catalyst.

In this case, in the production of trichlorosilane, in the heating of the mixed gas containing tetrachlorosilane and hydrogen, efficient heating is performed by performing heat exchange using the temperature of the reaction gas discharged from the conversion furnace in a high temperature state. It can be performed. On the other hand, by performing heat exchange, the temperature of the reaction gas containing trichlorosilane generated by the reaction can be lowered, and the copper-based catalyst contained in the reaction gas can be precipitated. Since it can be removed in a solid state, the processing equipment can be made small.
As described above, since the copper catalyst can be removed before the reaction gas after heat exchange is introduced into the purification distillation system, it is possible to prevent the circulation pump from being worn or clogged in the purification distillation system. .

In the method for producing trichlorosilane of the present invention, in the catalyst removal step, the copper-based catalyst can be captured by a filter such as a sintered filter or a metal filter.
Since the copper catalyst contained in the reaction gas is solidified by the heat exchange step, it can be easily removed by a filter.

  The trichlorosilane production apparatus of the present invention is an apparatus for producing trichlorosilane by reacting a mixed gas containing metal silicon, tetrachlorosilane and hydrogen in the presence of a copper-based catalyst, wherein the mixed gas is brought to a temperature at which the mixed gas can be reacted. Included in a heater for heating, a conversion furnace for generating a reaction gas containing trichlorosilane by reacting the mixed gas heated by the heater and the metal silicon, and a reaction gas derived from the conversion furnace A dust remover that removes the solid content, a heat exchanger that exchanges heat with the mixed gas before the reaction gas that has passed through the dust remover is supplied to the heater, and a reaction that exchanges heat with the mixed gas And a filter that removes the copper-based catalyst contained in the gas.

  According to the present invention, by performing heat exchange between the reaction gas and the mixed gas, the mixed gas can be efficiently heated, and the copper-based catalyst can be removed smoothly with a small-scale processing facility. Of trichlorosilane can be produced.

It is the schematic which shows the apparatus for enforcing the manufacturing method of the trichlorosilane of embodiment of this invention.

Hereinafter, embodiments of the method and apparatus for producing trichlorosilane of the present invention will be described.
FIG. 1 shows an overall schematic configuration of a trichlorosilane production apparatus. In the figure, trichlorosilane is TCS, tetrachlorosilane is STC, metal silicon is Si, hydrogen is H ₂ , and copper-based catalyst copper chloride is CuCl. It is written.

  The trichlorosilane production apparatus 1 reacts tetrachlorosilane with metal silicon and hydrogen to produce chlorosilanes containing trichlorosilane, and heats and supplies a mixed gas of tetrachlorosilane and hydrogen to the conversion furnace 2. A heater 3, a dust remover 4 that removes solids contained in the reaction gas derived from the conversion furnace 2, and a mixed gas before the reaction gas that has passed through the dust remover 4 is supplied to the heater 3 A heat exchanger 5 that exchanges heat with the mixed gas, a filter 8 that removes solids such as a copper catalyst contained in the reaction gas exchanged with the mixed gas, and a purified distillation system 9 that purifies trichlorosilane by distillation. It has.

  The metal silicon supplied to the conversion furnace 2 is in the form of particles, and the conversion furnace 2 is configured to react this metal silicon with hydrogen and tetrachlorosilane by a fluidized bed. The reaction in the conversion furnace 2 is an endothermic reaction, and hydrogen and tetrachlorosilane are supplied in a state heated in advance by the heater 3.

The heater 3 further heats the mixed gas heated via the heat exchanger 5 to a temperature at which the mixed gas can react. In the illustrated example, the heater 3 includes a heating unit 31 and a pre-conversion reaction unit 32, and the heating unit 31 converts the mixed gas heated through the heat exchanger 5 into the mixed gas. The pre-conversion reaction unit 32 is configured to further heat the mixed gas heated by the heating unit 31 to a temperature at which the mixed gas can react.
The heating unit 31 is configured to heat the mixed gas to about 400 ° C. with a metal electric heater (referred to as a metal heater), and the pre-conversion reaction unit 32 includes a carbon heater inside. By bringing the mixed gas into contact with a carbon heater that has generated heat at a high temperature of 600 ° C. to 850 ° C., the mixed gas is rapidly heated to a temperature of 580 ° C. or higher at which the mixed gas can react.

The dust remover 4 is composed of a cyclone or the like, and separates the solid content such as metal silicon powder contained in the high-temperature reaction gas led out from the conversion furnace 2 from the gas content, and the heat exchanger 5 The solid content in the reaction gas is removed before the introduction.
The heat exchanger 5 is configured to heat the mixed gas before being supplied to the heater 3 by using the temperature of the reaction gas. The heat exchanger 5 has a high temperature (about 550 ° C.) and a low temperature (about 150 ° C.). By performing heat exchange with the mixed gas, the mixed gas is heated and the reaction gas is cooled.
The filter 8 is configured by a filter such as a sintered filter or a metal filter, and is configured to remove impurities including copper chloride of the copper-based catalyst deposited in the reaction gas through the heat exchanger 5.
The purification distillation system 9 is configured to purify tetrachlorosilane and trichlorosilane by cooling and condensing the reaction gas containing trichlorosilane after the conversion reaction, and then distilling the condensed liquid.
Reference numeral 6 shown in FIG. 1 is a metallic silicon drier, and reference numeral 7 is a hopper that mixes metallic silicon and copper chloride, which will be described later.

Next, a method for producing trichlorosilane using the trichlorosilane production apparatus 1 will be described.
As a raw material, metallic silicon, tetrachlorosilane, or hydrogen is used. Metallic silicon is granular silicon made by refining silica (SiO ₂ ) to a purity of about 98%.
Of these, a mixed gas of tetrachlorosilane and hydrogen is heated before being supplied to the conversion furnace 2. First, the mixed gas of these tetrachlorosilane and hydrogen is heat-exchanged with the high temperature (about 550 degreeC) reaction gas produced | generated by the converter 2 with the heat exchanger 5, and is heated to about 400 degreeC. On the other hand, the reaction gas is cooled to about 300 ° C. by this heat exchange (heat exchange step).
Thereafter, the mixed gas is heated to about 400 ° C. by the heating unit 31 of the heater 3 and quickly heated to 580 ° C. or more by the carbon heater of the next pre-conversion reaction unit 32 (heating step). At this time, a part of the mixed gas reacts according to the following reaction formula (1).
SiCl ₄ + H ₂ → SiHCl ₃ + HCl (1)

On the other hand, metallic silicon and a reaction catalyst are supplied into the conversion furnace 2 to form a fluidized bed, and when the heated mixed gas is supplied to the conversion furnace 2, they react to contain trichlorosilane. Gas is generated (conversion reaction step). In this case, a copper-based catalyst such as copper chloride (CuCl) is used as the reaction catalyst. At this time, trichlorosilane is produced by the following reaction formula (2).
Si + 3HCl → SiHCl ₃ + H ₂ (2)

Note that hydrogen chloride (HCl) generated in the heating process also reacts with metal silicon (Si) to generate trichlorosilane (reaction formula (3)).
Si + 3SiCl ₄ + 2H ₂ → 4SiHCl ₃ (3)

  As described above, the reaction gas generated in the conversion reaction step contains, in addition to trichlorosilane, unreacted tetrachlorosilane and hydrogen, as well as fine metal silicon powder and impurities (Fe, Al, Ti, Ni, etc.) are reacted to form a metal chloride and a polymer composed of a higher-order silicon chloride compound, and copper-based catalyst copper chloride. In the reaction gas derived from the conversion furnace 2, copper chloride is contained as a solid component combined with metallic silicon and a gaseous component. Of these, most of the solids such as metal silicon powder and copper chloride contained in the reaction gas are removed by the dust remover 4 (dust removal step).

Then, the reaction gas that has passed through the dust remover 4 is sent to the heat exchanger 5 to exchange heat with the mixed gas, and is cooled to about 300 ° C. Thereby, the impurity containing the copper catalyst of the copper catalyst contained in the reaction gas is deposited. The impurities containing the precipitated solid copper chloride are removed by the filter 8 (catalyst removal step).
Thereafter, the reaction gas passing through the filter 8 is sent to the purification distillation system 9. The reaction gas is cooled in the purification distillation system 9 to be a condensed liquid, and the condensed liquid is distilled to purify tetrachlorosilane and trichlorosilane, thereby increasing the purity of trichlorosilane.

As described above, in the trichlorosilane production apparatus 1 of the present embodiment, heat exchange with a mixed gas containing tetrachlorosilane and hydrogen is performed using the temperature of the high-temperature reaction gas derived from the conversion furnace 2. The mixed gas can be heated efficiently.
In addition, the reaction gas derived from the conversion furnace 2 is previously removed from the solid gas in the reaction gas in the dust remover 4 before being introduced into the heat exchanger 5. Fine solids that could not be trapped by gas, gaseous copper chloride, etc. flow downstream. The reaction gas that has passed through the dust remover 4 undergoes heat exchange with a mixed gas containing tetrachlorosilane and hydrogen in the next heat exchanger 5, so that the temperature decreases, and gaseous copper chloride contained in the reaction gas. Can be deposited into a solid state. Then, impurities including copper chloride in a solid state can be removed by the filter 8 together with the fine solid content that has passed through the dust remover 4. Since copper chloride is in a solid state, the subsequent treatment can be made small.
The reaction gas that has passed through the filter 8 has increased purity of trichlorosilane, and high purity trichlorosilane can be purified by the following purification distillation system 9.
As described above, according to the present invention, the copper-based catalyst can be removed before flowing into the purification distillation system 9, so that it is possible to prevent the circulation pump from being worn, clogged, and the like, and high purity trichlorosilane. Can be manufactured.

In addition, this invention is not limited to the said embodiment, A various change can be added in the range which does not deviate from the meaning of this invention.
For example, in the trichlorosilane production apparatus of the above embodiment, the metal silicon is dried through a drier before being introduced into the conversion furnace. However, a step of further heating after the drying may be provided.

DESCRIPTION OF SYMBOLS 1 Trichlorosilane manufacturing apparatus 2 Conversion furnace 3 Heater 4 Dust removal device 5 Heat exchanger 6 Dryer 7 Hopper 8 Filter 9 Purification distillation system 31 Heating part 32 Pre-conversion reaction part

Claims (3)

  A method for producing trichlorosilane by reacting a mixed gas containing metal silicon, tetrachlorosilane, and hydrogen in the presence of a copper-based catalyst, the heating step heating the mixed gas to a reactable temperature, and the heating step A conversion reaction step of generating a reaction gas containing trichlorosilane by reacting the mixed gas heated with the metal silicon, a dust removal step of removing solids contained in the reaction gas, and the reaction gas A heat exchange step of exchanging heat with the mixed gas and sending the mixed gas to the heating step; and a catalyst removal step of removing the copper-based catalyst deposited in the reaction gas cooled by the heat exchange step. A method for producing trichlorosilane, comprising:   The method for producing trichlorosilane according to claim 1, wherein the catalyst removing step is performed by capturing the copper catalyst with a filter such as a sintered filter or a metal filter.   An apparatus for producing trichlorosilane by reacting a mixed gas containing metal silicon, tetrachlorosilane and hydrogen in the presence of a copper-based catalyst, the heater for heating the mixed gas to a temperature capable of reacting, and the heater A conversion furnace for generating a reaction gas containing trichlorosilane by reacting the mixed gas heated with metal with the metal silicon, and a dust remover for removing solids contained in the reaction gas derived from the conversion furnace A heat exchanger for exchanging heat with the mixed gas before being supplied to the heater, and a copper catalyst contained in the reaction gas heat-exchanged with the mixed gas. An apparatus for producing trichlorosilane, comprising a filter to be removed.

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