Synthesis method of trichlorosilane and production method and production device of polycrystalline silicon

Abstract

The invention provides a trichlorosilane synthesis method, a polycrystalline silicon production method and a polycrystalline silicon production device, and the trichlorosilane synthesis method comprises the following steps: 1) mixing silicon tetrachloride and dichlorosilane to obtain a mixture; wherein the temperature of the silicon tetrachloride is higher than that of the dichlorosilane, and the temperature of the silicon tetrachloride is 50-60 DEG C; and 2) carrying out an anti-disproportionation reaction on the mixture to obtain the trichlorosilane. According to the trichlorosilane synthesis method provided by the invention, the temperature of silicon tetrachloride is higher than that of dichlorosilane, and the temperature of silicon tetrachloride is 50-60 DEG C. When silicon tetrachloride and dichlorosilane are mixed, silicon tetrachloride with higher temperature can exchange heat with dichlorosilane with lower temperature, so that the temperature of dichlorosilane is increased, and the temperature of trichlorosilane is reduced. And the temperature of the mixed silicon tetrachloride and dichlorosilane can meet the temperature of the anti-disproportionation reaction, so that the need of providing extra heat is avoided, and the energy consumption is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of polysilicon, and in particular relates to a synthesis method of trichlorosilane, a production method of polysilicon and a production device. Background Art

[0002] In the production of polysilicon, the modified Siemens process is widely used due to its mature technology. This method uses trichlorosilane and hydrogen as raw materials and obtains polysilicon products through high-temperature reduction; however, in this process, a large amount of silicon tetrachloride, dichlorosilane and other by-products will be produced, which will affect the product yield and increase production costs.

[0003] Most existing technologies convert dichlorosilane into trichlorosilane through a reverse disproportionation reaction between dichlorosilane and silicon tetrachloride, which not only utilizes dichlorosilane but also consumes a portion of silicon tetrachloride in the production system, thereby reducing production costs and improving the elemental utilization of silicon.

[0004] However, in the prior art, the raw material dichlorosilane for the anti-disproportionation reaction needs to be heated to meet the temperature of the anti-disproportionation reaction, which increases energy consumption. Summary of the invention

[0005] The main purpose of the present invention is to provide a synthesis method of trichlorosilane, which can avoid providing additional heat and reduce energy consumption.

[0006] The present invention also provides a method for producing polysilicon, which can obtain silicon tetrachloride and silicon dichloride for anti-disproportionation reaction, realize the recycling of resources, and reduce the consumption and waste of raw materials.

[0007] The present invention also provides a polysilicon production device. The polysilicon can be produced by using the device to obtain silicon tetrachloride and silicon dichloride for anti-disproportionation reaction, thereby realizing the recycling of resources and reducing the consumption and waste of raw materials.

[0008] In a first aspect, the present invention provides a method for synthesizing trichlorosilane, comprising the following steps:

[0009] 1) mixing silicon tetrachloride and silicon dichloride to obtain a mixture; wherein the temperature of the silicon tetrachloride is greater than the temperature of the silicon dichloride, and the temperature of the silicon tetrachloride is 50° C.-60° C.;

[0010] 2) subjecting the mixture to a deproportionation reaction to obtain the trichlorosilane.

[0011] In the above-mentioned synthesis method of trichlorosilane, the difference between the temperature of the silicon tetrachloride and the temperature of the dichlorosilane is 20°C-34°C.

[0012] In the above-mentioned method for synthesizing trichlorosilane, the temperature of dichlorosilane is 26°C-30°C.

[0013] In the synthesis method of trichlorosilane as described above, the silicon tetrachloride is obtained by separating and treating the reducing tail gas in the production of polysilicon.

[0014] The synthesis method of trichlorosilane as described above, wherein the temperature of the anti-disproportionation reaction is 55°C-75°C;

[0015] And / or, the time of the anti-disproportionation reaction is 4h-8h;

[0016] And / or, the pressure of the anti-disproportionation reaction is 0.65MPa-0.75MPa;

[0017] And / or, the molar ratio of the silicon tetrachloride to the silicon dihydrogen dichloride is (3.5-5):1.

[0018] In the method for synthesizing trichlorosilane as described above, a catalyst is used to catalyze the anti-disproportionation reaction, and the catalyst includes an ion exchange resin.

[0019] The method for synthesizing trichlorosilane as described above further comprises: subjecting the trichlorosilane to a distillation treatment to obtain distilled trichlorosilane.

[0020] In a second aspect, the present invention provides a method for producing polycrystalline silicon, comprising the following steps:

[0021] 1) subjecting trichlorosilane and hydrogen to a reduction reaction to obtain the polysilicon and reduction tail gas;

[0022] 2) separating and treating the reduction tail gas to obtain silicon tetrachloride and dichlorosilane;

[0023] 3) Using the silicon tetrachloride and dichlorosilane, the trichlorosilane is synthesized according to the synthesis method of trichlorosilane as described above.

[0024] In the method for producing polycrystalline silicon as described above, the trichlorosilane is returned and reacted with the hydrogen to undergo the reduction reaction to obtain the polycrystalline silicon.

[0025] In a third aspect, the present invention provides a production device for executing the above-mentioned method for producing polysilicon, comprising a reduction unit for performing a reduction reaction between trichlorosilane and hydrogen;

[0026] A separation unit, used for separating and treating the reduction tail gas;

[0027] A mixing unit, used for mixing silicon tetrachloride and dichlorosilane;

[0028] The reaction unit is used for carrying out a deproportionation reaction on a mixture including silicon tetrachloride and dichlorosilane.

[0029] In the synthesis method of trichlorosilane provided by the present invention, the temperature of silicon tetrachloride is higher than that of silicon dichlorodihydrogen, and the temperature of silicon tetrachloride is 50°C-60°C. When silicon tetrachloride and silicon dichlorodihydrogen are mixed, silicon tetrachloride with a higher temperature can exchange heat with silicon dichlorodihydrogen with a lower temperature, so that the temperature of silicon dichlorodihydrogen is increased. The temperature of silicon tetrachloride and silicon dichlorodihydrogen after mixing can meet the temperature of the anti-disproportionation reaction, thereby avoiding the provision of additional heat and reducing energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or related technologies, the following briefly introduces the drawings required for use in the embodiments of the present invention or related technologies. Obviously, the drawings described below are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0031] Figure 1 A schematic diagram of a polysilicon production device provided by the present invention.

[0032] Description of reference numerals:

[0033] 1-reduction unit; 2-separation unit; 3-mixing unit; 4-reaction unit; 5-distillation unit. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] In the production process of polysilicon, the modified Siemens process is widely used because of its mature process and high product purity. This method mainly produces polysilicon through the chemical reaction of trichlorosilane and hydrogen at high temperature. However, a significant challenge of this process is the generation of by-products, especially silicon tetrachloride (SiCl4) and dichlorodihydrogen silicon (SiH2Cl2). These by-products not only reduce the yield of silicon, but also increase the production cost and the burden of environmental treatment.

[0036] In order to improve the element utilization rate of silicon and reduce production costs, the existing technology usually adopts the anti-disproportionation reaction to convert dichlorosilane into trichlorosilane while consuming part of silicon tetrachloride. This process effectively recovers the silicon element in the by-product and reduces the generation of waste. However, the traditional anti-disproportionation reaction requires heating dichlorosilane to reach the temperature required for the reaction, which leads to additional energy consumption and increases the complexity and cost of production.

[0037] Therefore, how to improve the efficiency of the anti-disproportionation reaction without significantly increasing energy consumption has become an important research direction for optimizing the polysilicon production process. According to the research of the inventors of this application, by rationally designing the reaction conditions and utilizing the temperature advantage of silicon tetrachloride, the anti-disproportionation reaction can be promoted without significantly increasing energy consumption. This method can not only increase the output of trichlorosilane, but also effectively reduce production costs and environmental impacts, providing a more economical and environmentally friendly solution for polysilicon production.

[0038] Based on this, in a first aspect, the present invention provides a method for synthesizing trichlorosilane, comprising the following steps:

[0039] 1) Silicon tetrachloride and dichlorosilane are mixed to obtain a mixture; wherein the temperature of the silicon tetrachloride is greater than that of the dichlorosilane, and the temperature of the silicon tetrachloride is 50°C-60°C; for example, the temperature may be 50°C, 51°C, 52°C, 53°C, 54°C, 55°C, 56°C, 57°C, 58°C, 59°C, 60°C or a range consisting of any two thereof.

[0040] 2) The mixture is subjected to an anti-disproportionation reaction to obtain trichlorosilane.

[0041] Specifically, in step 1), since the temperature of silicon tetrachloride is 50°C-60°C, which is higher than the temperature of silicon dichloride, silicon tetrachloride and silicon dichloride are mixed, and the temperature of silicon dichloride can be used to increase the temperature of silicon dichloride. In the obtained mixture, the temperatures of silicon tetrachloride and silicon dichloride can meet the temperature for the anti-disproportionation reaction, and there is no need to heat silicon dichloride additionally, which reduces energy consumption, reduces dependence on external energy, and achieves efficient energy utilization and lower production costs.

[0042] The present invention does not limit the sources of silicon tetrachloride and dichlorosilane. For example, they can be obtained by separating the tail gas generated by the reduction furnace after trichlorosilane and hydrogen undergo reduction reaction in polysilicon production.

[0043] In step 2), the mixture is subjected to a deproportionation reaction, that is, the valence state of silicon in silicon tetrachloride is reduced, while the valence state of silicon in dichlorodihydrogen silicon is increased, thereby obtaining trichlorosilane.

[0044] In the synthesis method of trichlorosilane provided by the present invention, the temperature of silicon tetrachloride is higher than that of silicon dichlorodihydrogen, and the temperature of silicon tetrachloride is 50°C-60°C. When silicon tetrachloride and silicon dichlorodihydrogen are mixed, silicon tetrachloride with a higher temperature can exchange heat with silicon dichlorodihydrogen with a lower temperature, so that the temperature of silicon dichlorodihydrogen is increased. The temperature of silicon tetrachloride and silicon dichlorodihydrogen after mixing can meet the temperature of the anti-disproportionation reaction, thereby avoiding the provision of additional heat and reducing energy consumption.

[0045] In some embodiments of the present invention, the temperature difference between silicon tetrachloride and dichlorosilane is 20°C-34°C, for example, it can be 20°C, 22°C, 25°C, 28°C, 30°C, 34°C or any two thereof.

[0046] In the present invention, the difference between the temperature of silicon tetrachloride and the temperature of silicon dichloride is limited to the above range. By utilizing the higher temperature of silicon tetrachloride, heat can be effectively transferred to silicon dichloride, so that the temperature of the mixture obtained by mixing the two meets the temperature of the anti-disproportionation reaction, reducing the demand for external heat sources, thereby reducing energy consumption and reducing production costs.

[0047] In some embodiments of the present invention, the temperature of dichlorosilane is 26°C-30°C, for example, 26°C, 27°C, 28°C, 29°C, 30°C or any two thereof.

[0048] In the present invention, the temperature of dichlorosilane is within the above range, which can further make full use of the higher temperature of silicon tetrachloride to transfer heat to dichlorosilane, so that the temperature of the mixture obtained by mixing the two can more easily meet the temperature of the anti-disproportionation reaction, further reducing the demand for external heat sources, thereby reducing energy consumption and reducing production costs.

[0049] In some embodiments of the present invention, silicon tetrachloride is obtained by separating and treating reducing tail gas in the production of polysilicon.

[0050] It is understandable that the tail gas generated during the production of polysilicon contains silicon tetrachloride. Through separation and treatment, this by-product can be effectively recovered, reducing resource waste and realizing resource recycling. At the same time, recycling silicon tetrachloride in tail gas can reduce dependence on purchased raw materials, thereby reducing production costs and improving economic benefits. In addition, processing and recycling silicon tetrachloride in tail gas can reduce the emission of harmful substances and reduce pollution to the environment, which complies with environmental protection laws and regulations and the requirements of sustainable development.

[0051] In some embodiments of the present invention, the temperature of the anti-disproportionation reaction is 55°C-75°C, for example, it can be 55°C, 56°C, 57°C, 58°C, 59°C, 60°C, 62°C, 65°C, 67°C, 70°C, 75°C or a range consisting of any two of them.

[0052] In some embodiments, the time of the anti-disproportionation reaction is 4 h-8 h, for example, it can be 4 h, 5 h, 6 h, 7 h, 8 h or a range consisting of any two thereof.

[0053] In some embodiments, the pressure of the anti-disproportionation reaction is 0.65 MPa-0.75 MPa, for example, it can be 0.65 MPa, 0.66 MPa, 0.67 MPa, 0.68 MPa, 0.69 MPa, 0.70 MPa, 0.71 MPa, 0.72 MPa, 0.73 MPa, 0.74 MPa, 0.75 MPa or a range consisting of any two of them.

[0054] In some embodiments, the molar ratio of silicon tetrachloride to silicon dihydrogen dichloride is (3.5-5):1, for example, 3.5:1, 3.7:1, 4:1, 4.2:1, 4.5:1, 4.7:1, 5:1 or a range consisting of any two thereof.

[0055] The temperature of the anti-disproportionation reaction in the present invention is within the above range, which can improve production efficiency, reduce unnecessary side reactions, and improve the purity and yield of the trichlorosilane product.

[0056] The time of the anti-disproportionation reaction is within the above range, which can ensure that the reaction is completely carried out, while avoiding the waste of resources caused by too long reaction time, and can also improve equipment utilization and increase production.

[0057] The pressure of the anti-disproportionation reaction is within the above range, which makes the reaction closer to the equilibrium state and is beneficial to increasing the yield of the target product.

[0058] The molar ratio of silicon tetrachloride to silicon dichloride in the anti-disproportionation reaction is within the above range, which can improve the selectivity of the anti-disproportionation reaction, reduce the generation of by-products, effectively utilize raw materials, and reduce the waste of raw materials.

[0059] In some embodiments of the invention, the deproportionation reaction is catalyzed using a catalyst, the catalyst comprising an ion exchange resin.

[0060] It can be understood that the ion exchange resin includes anion and cation exchange resins, wherein the anions may include at least one of chloride ions, hydroxide ions, sulfate ions, bicarbonate ions, nitrate ions, phosphate ions, and acetate ions; and the cations may include at least one of sodium ions, hydrogen ions, potassium ions, calcium ions, magnesium ions, and ammonium ions. During the anti-disproportionation reaction, silicon tetrachloride and dichlorodihydrogen silicon are complexed with the active amino groups in the ion exchange resin (weakly alkaline) to form a secondary complex, and then the secondary complex is decomposed into trichlorosilane and active amino groups.

[0061] Ion exchange resins can provide active sites and accelerate the efficiency of the anti-disproportionation reaction, thereby shortening the reaction time, improving production efficiency, selectively promoting the formation of target products, reducing the occurrence of side reactions, and improving the purity and yield of target products. Ion exchange resins can also play their catalytic role under mild conditions, reducing energy consumption and equipment requirements. Since ion exchange resins are solid catalysts, they can be easily separated and recovered by simple filtration or sedimentation after the reaction, reducing catalyst loss and production costs. Ion exchange resins have a long service life and good chemical stability, and can maintain activity in multiple reaction cycles, reducing the frequency of catalyst replacement.

[0062] In some embodiments of the present invention, the process further comprises: subjecting trichlorosilane to distillation treatment to obtain distilled trichlorosilane.

[0063] It can be understood that distillation is an effective separation and purification technology that can remove impurities and by-products in trichlorosilane, thereby improving the purity of trichlorosilane.

[0064] In a second aspect, the present invention provides a method for producing polycrystalline silicon, comprising the following steps:

[0065] 1) Reducing trichlorosilane with hydrogen to obtain polysilicon and reduced tail gas;

[0066] 2) Separating and treating the reduction tail gas to obtain silicon tetrachloride and dichlorosilane;

[0067] 3) Using silicon tetrachloride and dichlorosilane, trichlorosilane is synthesized according to the synthesis method of trichlorosilane as described above.

[0068] Specifically, in step 1), trichlorosilane and hydrogen undergo a reduction reaction to obtain polycrystalline silicon and reduction tail gas, wherein the reduction tail gas includes trichlorosilane, silicon tetrachloride, dichlorosilane, hydrogen, hydrogen chloride, etc.

[0069] In step 2), the reduction tail gas is condensed and then separated to obtain silicon tetrachloride and dichlorosilane.

[0070] In step 3), the separated silicon tetrachloride and silicon dichloride are mixed, and then trichlorosilane is synthesized according to the synthesis method of trichlorosilane provided in the first aspect of the present invention.

[0071] The polysilicon production method provided by the present invention can realize the recycling of resources, reduce the consumption and waste of raw materials, reduce production costs, and improve economic benefits by separating and treating the reduction tail gas, recovering silicon tetrachloride and dichlorosilane, and using them to synthesize silicon trichloride.

[0072] In some embodiments of the present invention, trichlorosilane is returned to react with hydrogen to undergo a reduction reaction to obtain polycrystalline silicon.

[0073] In the present invention, trichlorosilane is recycled into the reduction reaction to form a closed-loop production process, thereby reducing the waste of raw materials and improving resource utilization.

[0074] In a third aspect, the present invention provides a production device for executing the above-mentioned polysilicon production method, such as Figure 1 As shown, it includes a reduction unit 1 for performing a reduction reaction on trichlorosilane and hydrogen;

[0075] Separation unit 2, used for separating and treating the reduction tail gas;

[0076] A mixing unit 3, for mixing silicon tetrachloride and dichlorosilane;

[0077] The reaction unit 4 is used for carrying out a deproportionation reaction on a mixture including silicon tetrachloride and silicon dichloride.

[0078] In the present invention, the tail gas outlet of the reduction unit 1 is connected to the tail gas inlet of the separation unit 2, the first liquid phase outlet of the separation unit 2 is connected to the first liquid phase inlet of the mixing unit 3, the second liquid phase outlet of the separation unit 2 is connected to the second liquid phase inlet of the mixing unit 3, the material outlet of the mixing unit 3 is connected to the material inlet of the reaction unit 4, and the product outlet of the reaction unit 4 is connected to the material inlet of the distillation unit 5.

[0079] Specifically, in the present invention, trichlorosilane and hydrogen undergo a reduction reaction in the reduction unit 1 to obtain polysilicon and reduction tail gas, the reduction tail gas is output through the tail gas outlet of the reduction unit 1, and enters the separation unit 2 through the tail gas inlet of the separation unit 2 for separation treatment to obtain silicon tetrachloride and dichlorosilane, wherein dichlorosilane is output from the first liquid phase outlet at the top of the separation unit 2 and enters the mixing unit 3 from the first liquid phase inlet of the mixing unit 3, silicon tetrachloride is output from the second liquid phase outlet at the side of the separation unit 2 and enters the mixing unit 3 from the second liquid phase inlet of the mixing unit 3, in the mixing unit 3, the temperature of the obtained mixture can meet the temperature of the anti-disproportionation reaction after the silicon tetrachloride and dichlorosilane with higher temperature are mixed. The mixture is output from the material outlet of the mixing unit 3, enters the reaction unit 4 through the material inlet of the reaction unit 4 for anti-disproportionation reaction, and trichlorosilane is obtained.

[0080] In addition, the polysilicon production device of the present invention further comprises a distillation unit 5, trichlorosilane is output from the product outlet of the reaction unit 4, after being cooled by the cooling adsorption column, enters the distillation unit 5 from the material inlet of the distillation unit 5 for distillation treatment, and obtains distilled trichlorosilane. The distilled trichlorosilane can be returned to perform a reduction reaction with hydrogen to produce polysilicon.

[0081] It should be noted that, in the present invention, the reduction unit 1 may be a reduction furnace, the separation unit 2 may be a recovery separation tower, the mixing unit 3 may be a static mixer, the reaction unit 4 may be an anti-disproportionation column, and the distillation unit 5 may be a distillation tower.

[0082] The polysilicon production device provided by the present invention can obtain silicon tetrachloride and silicon dichloride for anti-disproportionation reaction, thereby realizing the recycling of resources and reducing the consumption and waste of raw materials.

[0083] The technical solution of the present invention is further described below in conjunction with specific embodiments.

[0084] Example 1

[0085] The device of this embodiment is a polysilicon production device, such as Figure 1 As shown, it includes a reduction unit 1 (reduction furnace); a separation unit 2 (recovery separation tower); a mixing unit 3 (static mixer); a reaction unit 4 (anti-disproportionation column); and a distillation unit 5 (distillation tower).

[0086] Among them, the tail gas outlet of the reduction unit 1 is connected to the tail gas inlet of the separation unit 2, the first liquid phase outlet of the separation unit 2 is connected to the first liquid phase inlet of the mixing unit 3, the second liquid phase outlet of the separation unit 2 is connected to the second liquid phase inlet of the mixing unit 3, the material outlet of the mixing unit 3 is connected to the material inlet of the reaction unit 4, and the product outlet of the reaction unit 4 is connected to the material inlet of the distillation unit 5.

[0087] Specifically, trichlorosilane and hydrogen undergo a reduction reaction in the reduction unit 1 to obtain polysilicon and reduction tail gas, which is output through the tail gas outlet of the reduction unit 1 and enters the separation unit 2 through the tail gas inlet of the separation unit 2 for separation treatment to obtain silicon tetrachloride and dichlorosilane, wherein dichlorosilane is output from the first liquid phase outlet at the top of the separation unit 2 and enters the mixing unit 3 from the first liquid phase inlet of the mixing unit 3, and silicon tetrachloride is output from the second liquid phase outlet at the side of the separation unit 2 and enters the mixing unit 3 from the second liquid phase inlet of the mixing unit 3. In the mixing unit 3, silicon tetrachloride (temperature of 55°C) and dichlorosilane (temperature of 26.5°C) are mixed, and the temperature of the obtained mixture can meet the temperature of the anti-disproportionation reaction. The mixture is output from the material outlet of the mixing unit 3 and enters the reaction unit 4 through the material inlet of the reaction unit 4 for anti-disproportionation reaction to obtain trichlorosilane. The temperature of the anti-disproportionation reaction is 65°C, the time is 8h, the pressure is 0.7MPa, the molar ratio of silicon tetrachloride to dichlorodihydrogen silicon is 4:1, and the catalyst is an ion exchange resin (manufacturer: Shaanxi Lanshen Technology Co., Ltd.). Trichlorosilane is output from the product outlet of the reaction unit 4, and after cooling by the cooling adsorption column, it enters the distillation unit 5 from the material inlet of the distillation unit 5 for distillation treatment to obtain distilled trichlorosilane. The distilled trichlorosilane can be returned to react with hydrogen for reduction to produce polysilicon.

[0088] Example 2-13

[0089] The polysilicon production device and production method of Example 2-13 are basically the same as those of Example 1, except that one or more items in the production method are changed. Specific parameters are shown in Table 1.

[0090] Comparative Example 1

[0091] The production apparatus and production method of polysilicon in Comparative Example 1 are substantially the same as those in Example 1, except that the temperature of silicon tetrachloride is 40° C., and additional heat is required to heat the mixture of silicon tetrachloride and silicon dihydrogen dichloride.

[0092] Table 1

[0093]

[0094] As can be seen from Table 1, in the synthesis method of trichlorosilane provided by the present invention, the temperature of silicon tetrachloride is greater than that of silicon dichlorodihydrogen, and the temperature of silicon tetrachloride is 50°C-60°C. When silicon tetrachloride and silicon dichlorodihydrogen are mixed, silicon tetrachloride with a higher temperature can be heat exchanged with silicon dichlorodihydrogen with a lower temperature, so that the temperature of silicon dichlorodihydrogen is increased, and the temperature of silicon tetrachloride and silicon dichlorodihydrogen after mixing can meet the temperature of the anti-disproportionation reaction, thereby avoiding the provision of additional heat and reducing energy consumption.

[0095] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for synthesizing trichlorosilane, characterized in that: The following steps are involved: 1) mixing silicon tetrachloride and silicon dichloride to obtain a mixture; wherein the temperature of the silicon tetrachloride is greater than the temperature of the silicon dichloride, and the temperature of the silicon tetrachloride is 50° C.-60° C.; 2) subjecting the mixture to a deproportionation reaction to obtain the trichlorosilane.

2. The method for synthesizing trichlorosilane according to claim 1, characterized in that: The difference between the temperature of the silicon tetrachloride and the temperature of the dichlorosilane is 20°C to 34°C.

3. The method for synthesizing trichlorosilane according to claim 1 or 2, characterized in that: The temperature of the dichlorosilane is 26°C-30°C.

4. The method for synthesizing trichlorosilane according to any one of claims 1 to 3, characterized in that: The silicon tetrachloride is obtained by separating and treating the reducing tail gas in the production of polysilicon.

5. The method for synthesizing trichlorosilane according to any one of claims 1 to 4, characterized in that: The temperature of the anti-disproportionation reaction is 55°C-75°C; And / or, the time of the anti-disproportionation reaction is 4h-8h; And / or, the pressure of the anti-disproportionation reaction is 0.65MPa-0.75MPa; And / or, the molar ratio of the silicon tetrachloride to the silicon dihydrogen dichloride is (3.5-5):

1.

6. The method for synthesizing trichlorosilane according to any one of claims 1 to 5, characterized in that: The anti-disproportionation reaction is catalyzed using a catalyst, which includes an ion exchange resin.

7. The method for synthesizing trichlorosilane according to any one of claims 1 to 6, characterized in that: Also includes: The trichlorosilane is subjected to rectification treatment to obtain rectified trichlorosilane.

8. A method for producing polycrystalline silicon, characterized in that: The following steps are involved: 1) subjecting trichlorosilane and hydrogen to a reduction reaction to obtain the polysilicon and reduction tail gas; 2) separating and treating the reduction tail gas to obtain silicon tetrachloride and dichlorosilane; 3) Using the silicon tetrachloride and dichlorosilane, the trichlorosilane is synthesized according to the method for synthesizing trichlorosilane according to any one of claims 1 to 7.

9. The method for producing polycrystalline silicon according to claim 8, characterized in that: The trichlorosilane is returned to undergo the reduction reaction with the hydrogen to obtain the polycrystalline silicon.

10. A production device for executing the method for producing polycrystalline silicon according to claim 8 or 9, characterized in that: It includes a reduction unit for performing a reduction reaction on trichlorosilane and hydrogen; A separation unit, used for separating and treating the reduction tail gas; A mixing unit, used for mixing silicon tetrachloride and dichlorosilane; The reaction unit is used for carrying out a deproportionation reaction on a mixture including silicon tetrachloride and dichlorosilane.

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