A device and method for treating high boiling point by-products of polysilicon

Abstract

The present invention discloses a device and method for treating high-boiling substances produced as a by-product of polysilicon, and relates to the field of polysilicon by-product treatment. A device and method for treating high-boiling substances produced as a by-product of polysilicon, wherein anhydrous hydrogen chloride and high-boiling substances produced as a by-product of polysilicon production are reacted together in a fixed bed reactor, wherein the anhydrous hydrogen chloride and high-boiling substances produce low-boiling monochlorosilane, thereby converting the polysilicon by-product into a raw material for polysilicon production, and realizing the comprehensive utilization of the polysilicon by-product. The high-boiling substance treatment device and method of the present invention have the advantages of large loading amount of amino resin catalyst, convenient replacement of amino resin catalyst, effective prevention of catalyst carbonization due to heat, and reduction of the use amount of catalyst for high-boiling substances produced as a by-product of polysilicon.

Description

Technical Field

[0001] The invention relates to the technical field of polysilicon preparation, and in particular to polysilicon byproduct processing. Background Art

[0002] Polysilicon is the main raw material for manufacturing photovoltaic solar cells and other products. Among the methods for manufacturing high-purity polysilicon, the modified Siemens method is the current mainstream polysilicon production method. In the modified Siemens method, trichlorosilane and hydrogen react in a reduction furnace, and the silicon in trichlorosilane is reduced and deposited on the surface of the silicon core to form polysilicon rods with a diameter of 120-200mm. Then the raw material is stopped and the current is gradually reduced to stop. The polysilicon rods in the reduction furnace are gradually cooled. After cooling to a certain temperature, they are replaced with nitrogen and the polysilicon rods are taken out of the reduction furnace. The polysilicon rods taken out of the reduction furnace are broken into blocks, packaged, and transported to the downstream of the photovoltaic industry chain for use.

[0003] In the early days, polysilicon reduction furnaces produced 9, 12, and 24 pairs of polysilicon rods per batch. Currently, polysilicon reduction furnaces have become large-scale, generally with more than 36 pairs of rods, including large-scale reduction furnaces with 36, 40, 48, 60, 66, and 72 pairs of rods. In large-scale reduction furnaces, due to the dense arrangement of silicon rods and the high internal temperature, the solution produces silicon polymers, which have a high boiling point and are usually called high-boiling products after the polysilicon reduction tail gas is recovered and separated. The direct hydrolysis of these high-boiling products leads to the loss of silicon and chlorine. At present, some companies use cracking methods to recover trichlorosilane and silicon tetrachloride, or recover and separate them as high-value-added products or as raw materials to produce silicone oil.

[0004] In this regard, patent CN105271246B discloses a method for preparing chlorodisilane using polysilicon byproducts, firstly, a high-boiling substance containing aluminum chloride produced as a byproduct in the production process of polysilicon is kept warm to form a crystal and the crystal is separated; an auxiliary agent is added to the high-boiling substance from which the crystal is removed to form a mixed system; the temperature of the mixed system is raised to 30°C to 120°C and kept warm to form a mixed system containing a non-volatile aluminum compound; the mixed system containing the non-volatile aluminum compound is distilled at normal pressure or an absolute pressure of less than 0.2 MPa to obtain a mixed chlorodisilane not containing aluminum chloride; and the mixed chlorodisilane not containing aluminum chloride is distilled to obtain a single-component chlorodisilane.

[0005] Patent CN105778098A discloses a method for synthesizing silicone oil from high-boiling residues in polysilicon production. The raw materials for the method are high-boiling residues, methanol or ethanol, and the reaction process includes alcoholysis, analysis, polycondensation, neutralization and separation. The reaction conditions of the invention are easy to control, the reaction process is simple, the synthesized silicone oil product has stable performance, controllable molecular weight and high oil yield.

[0006] Patent CN103663460A uses high-boiling chlorosilane and hydrogen chloride to crack in a cracking reaction tower under the action of an organic amine catalyst, and performs a cracking reaction at 100-140°C under normal pressure. This method has a high recovery efficiency of more than 90%. Patent CN105314637A discloses a method and device for preparing halosilane by cracking a halosilicon polymer, including the steps of introducing a halosilicon polymer into a cracking reactor and cracking it to generate halosilane under the action of a catalyst and a cracking agent.

[0007] However, for the homogeneous catalyst used in the existing high-boiling-point cracking to prepare trichlorosilane and silicon tetrachloride, it is impossible to replace the catalyst in a timely and convenient manner under the catalytic effect of the homogeneous catalyst, and when the failed catalyst is treated together with the high-boiling point, the loss of silicon and chlorine elements is caused. The prior art shows that it is necessary to adopt a solid-supported catalyst and form a device and method for treating high-boiling points, so as to conveniently replace the catalyst and reduce the loss of silicon and chlorine elements. The high-boiling point treatment device and method of the present invention have the advantages of large catalyst loading capacity, convenient catalyst replacement, effective prevention of catalyst carbonization by heat, and reduction of the amount of catalyst used for high-boiling point by-product of polysilicon. Summary of the invention

[0008] The technical problem to be solved by the present invention is to provide a novel high-boiling material treatment device and method to solve the loss of silicon and chlorine elements caused by the deactivation of existing homogeneous catalysts.

[0009] Based on the present invention, a novel high boiling point material treatment device and method are provided, wherein the high boiling point material treatment device comprises: a gas-liquid-solid fluidized bed reactor for treating high boiling points produced as by-products of polysilicon, comprising a cylinder (1), an upper baffle (2), a lower baffle (3), a catalyst discharge port (4), a gas distributor (5), a high boiling point material feed port (6), a reaction product outlet (11), and a catalyst filling port (12).

[0010] The device and method for treating high-boiling-point byproducts of polysilicon can use steam or electric heating to maintain the reactor temperature. Preferably, the cylinder is provided with a steam jacket for insulation or a steam pipe for heating, and the insulation temperature is 30-160°C, preferably 50-140°C.

[0011] The device and method for treating high-boiling-point byproducts of polysilicon can use a solid-supported catalyst. Preferably, the catalyst used is an amino resin catalyst in which an amino group is fixed on a resin.

[0012] The device and method for treating high-boiling substances produced as byproducts of polysilicon can use baffles and filters to prevent the catalyst from being lost along with the material. Preferably, there is a catalyst baffle at the upper and lower parts of the reactor.

[0013] The catalyst adding port of the device and method for treating high-boiling-point by-products of polysilicon can be horizontal or inclined. Preferably, the catalyst adding port is inclined downward.

[0014] The catalyst baffle of the device and method for treating high-boiling-point byproducts of polysilicon is porous, allowing materials to flow through while trapping catalysts. The pore size of the catalyst baffle is smaller than the diameter of catalyst particles. Preferably, the pore size of the catalyst baffle is 1 / 3-4 / 5 of the diameter of the catalyst particles.

[0015] The upper catalyst baffle of the device and method for treating high-boiling substances produced as byproducts of polysilicon is located 3-30 mm above the upper portion of the catalyst loading port, preferably 5-10 mm above the upper portion of the catalyst loading port.

[0016] The lower catalyst baffle of the device and method for treating polysilicon by-product high boiling points is located 0-10 mm below the lower portion of the catalyst discharge outlet, preferably 3-5 mm below the lower portion of the catalyst discharge outlet.

[0017] The device and method for treating polysilicon by-product high boiling point products are characterized in that the height H1 of the upper catalyst baffle is 60%-98% of the height H of the reactor. Preferably, the height H1 of the upper catalyst baffle is 85%-95% of the height H of the reactor.

[0018] The device and method for treating high-boiling-point byproducts of polysilicon are characterized in that the height H2 of the lower catalyst baffle is 2%-15% of the height H of the reactor. Preferably, the height H2 of the lower catalyst baffle is 3%-10% of the height H of the reactor.

[0019] The device and method for treating high-boiling substances produced as by-products of polysilicon are characterized in that the high-boiling cracking reaction temperature is 30-160°C, preferably, the high-boiling reaction temperature is 50-140°C.

[0020] The device and method for treating high-boiling substances produced as by-products of polysilicon are characterized in that the high-boiling cracking reaction pressure is 0.05-1.6 MPa, and preferably, the high-boiling reaction pressure is 0.1-0.8 MPa.

[0021] The device and method for treating high-boiling substances produced as byproducts of polysilicon are characterized in that anhydrous hydrogen chloride introduced into the reaction device is distributed through a gas distributor so as to evenly pass through the fixed bed layer.

[0022] By using the above-mentioned device and method for producing high-boiling substances as by-products of polysilicon, the high-boiling substances can be effectively cracked in the reactor to produce silicon tetrachloride, dichlorosilane, trichlorosilane, etc. Compared with the prior art, the present invention has the advantages of large catalyst loading capacity, convenient catalyst replacement, effective prevention of catalyst carbonization due to heat, and reduced use of catalyst for high-boiling substances produced as by-products of polysilicon. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The invention relates to a device for treating high-boiling substances produced as by-products of polysilicon. DETAILED DESCRIPTION

[0024] The following is a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments by ordinary technicians in this field without making creative changes are within the protection scope of the present invention.

[0025] Figure 1 This is a specific embodiment of the present invention. In this embodiment, the catalyst is loaded with an amino resin catalyst in the cylinder 1 through the upper baffle 2 and the lower baffle 3. The amino resin catalyst can be loaded through the catalyst loading port 12 and discharged from the catalyst discharge port 4. The temperature of the jacket insulation is controlled to be 90°C, the high boiling enters the reactor from the bottom inlet 6 through the pipeline 8 and the valve 7, the HCl gas enters the reactor through the pipeline 10 and the valve 9, and the gas distributor 5 disperses the HCl entering the reactor. The reaction temperature is controlled to be 120°C and the pressure is 0.3MPa for reaction. The reaction product is discharged from the reactor through the top outlet 11, collected and separated through the valve 14 and the pipeline 13, and the separated trichlorosilane is provided to the polysilicon reduction device as a raw material after rectification, and the silicon tetrachloride is provided to the silicon tetrachloride hydrogenation device.

[0026] Although the above text has given a detailed description and explanation of the specific embodiments of the present invention with reference to the accompanying drawings, it should be pointed out that those skilled in the art can make various equivalent changes and modifications to the above embodiments based on the concept of the present invention, and the functional effects produced therefrom still do not exceed the spirit covered by the specification, and should all be within the protection scope of the present invention.

Claims

1. A method for treating high boiling point by-products of polysilicon, characterized in that The invention comprises the following steps: raw material anhydrous hydrogen chloride enters from the bottom of a gas-liquid-solid fluidized bed reactor through a gas distributor, and by-product high-boiling substances of polysilicon enter from the bottom of the gas-liquid-solid fluidized bed reactor; the gas-liquid-solid fluidized bed reactor is provided with a catalyst baffle at the upper and lower parts respectively; the catalyst is arranged at the bottom and upper baffles of the gas-liquid-solid fluidized bed reactor and is restricted in the gas-liquid-solid fluidized bed reactor; the catalyst is an amino resin catalyst; monosilane generated by the reaction, incompletely reacted anhydrous hydrogen chloride and by-product high-boiling substances of polysilicon flow out from the top of the gas-liquid-solid fluidized bed reactor together for further separation; the catalyst baffle is porous, and the pore size of the catalyst baffle is 1 / 3-4 / 5 of the diameter of the catalyst particles.

2. The method for treating high boiling points produced as by-products of polysilicon according to claim 1, characterized in that: The cylinder of the gas-liquid-solid fluidized bed reactor is provided with a steam jacket for heat insulation or a steam pipe for heat insulation.

3. The method for treating high boiling points produced as by-products of polysilicon according to claim 2, characterized in that: The insulation temperature is 30-160℃.

4. The method for treating high boiling points produced as by-products of polysilicon according to claim 1, characterized in that: The amino resin catalyst addition port is tilted downward.

5. The method for treating high boiling points produced as by-products of polysilicon according to claim 1, characterized in that: The upper catalyst baffle is located 3-30 mm higher than the upper portion of the catalyst loading port.

6. The method for treating high boiling points produced as by-products of polysilicon according to claim 1, characterized in that: The position of the lower catalyst baffle is 0-10 mm lower than the lower part of the catalyst discharge outlet.

7. The method for treating polysilicon by-product high boiling points according to claim 1, characterized in that The height of the upper catalyst baffle is 60%-98% of the height of the gas-liquid-solid fluidized bed reactor, and the height of the lower catalyst baffle is 2%-15% of the height of the gas-liquid-solid fluidized bed reactor.

8. The method for treating high boiling points produced as by-products of polysilicon according to claim 1, characterized in that The cracking reaction temperature of high-boiling products produced as by-products of polysilicon is between 30-160°C.

9. The method for treating high boiling points produced as by-products of polysilicon according to claim 1, characterized in that The cracking reaction pressure of high-boiling products produced as by-products of polysilicon is between 0.05 and 1.6 MPa.

10. The method for treating high boiling point by-products of polysilicon according to claim 1, characterized in that The introduced anhydrous hydrogen chloride enters the reaction device and is distributed through a gas distributor.

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