Methods for removing aluminum from high-boiling polycrystalline silicon, aluminochloroaluminate ionic liquids, applications, and catalytic cracking methods for high-boiling polycrystalline silicon.

Abstract

This invention discloses a method for removing aluminum from high-boiling-point polycrystalline silicon, an ionic liquid containing aluminochloroaluminate, its application, and a catalytic cracking method for high-boiling-point polycrystalline silicon. The method includes the following steps: introducing an ionic liquid, including pyrrolidine-based and / or piperidine-based ionic liquids, into the high-boiling-point polycrystalline silicon; heating the liquid to allow the cations in the ionic liquid to combine with aluminum trichloride in the polycrystalline silicon to form an ionic liquid containing aluminochloroaluminate. This method has excellent aluminum removal efficiency, effectively converting aluminum trichloride in the high-boiling-point polycrystalline silicon into an ionic liquid containing aluminochloroaluminate. The resulting ionic liquid is liquid, avoiding the problem of solid slag formation and equipment and pipeline blockage caused by traditional aluminum removal processes. The ionic liquid has a long service life and is easy to recycle and reuse, exhibiting good economic and environmental benefits.

Description

Technical Field

[0001] This invention belongs to the field of polycrystalline silicon production technology, specifically relating to a method for removing aluminum from high-boiling polycrystalline silicon, aluminochloride ionic liquid, its application, and a catalytic cracking method for high-boiling polycrystalline silicon. Background Technology

[0002] Polysilicon production is a crucial part of the photovoltaic industry, and its production capacity is rapidly expanding. Trichlorosilane (TCS) is an important raw material for polysilicon production, generally prepared through the reaction of silicon with hydrogen chloride (synthesis) or silicon powder, hydrogen, and silicon tetrachloride (cold hydrogenation). However, regardless of the synthesis or cold hydrogenation reaction, in addition to the target products such as trichlorosilane and silicon tetrachloride, a certain amount of silicon-based high-boiling compounds are also generated. These high-boiling compounds are mainly composed of chlorosilanes with Si-Si bonds, Si-C-Si bonds, and Si-O-Si bonds, exhibiting complex structures and strong irritant and corrosive properties, making them unsuitable for direct use. Silicon-containing high-boiling compounds have high boiling points and high viscosity, making them prone to accumulation in the system. Existing high-boiling-point catalytic cracking technologies require pretreatment of high-boiling-point substances to separate aluminum trichloride, which increases equipment investment and production costs. In addition, the aluminum complexes formed after adding aluminum removal agents or the crystals formed by cooling crystallization may cause a decrease in heating equipment efficiency and pipeline blockage during separation if the high-boiling-point substances are not removed in time, thereby increasing equipment maintenance costs, affecting production stability, and hindering the safe and stable operation of the equipment.

[0003] Currently, commonly used methods for treating high-boiling-point substances include incineration, hydrolysis, and catalytic cracking. Among these, catalytic cracking is a relatively environmentally friendly and economical method. Its basic principle is to use organic amines as catalysts and hydrogen chloride gas as cracking gas to decompose high-boiling-point substances into low-boiling-point chlorosilanes. During catalytic cracking, the organic amine catalyst undergoes a complexation reaction with aluminum trichloride impurities in the high-boiling-point substances, resulting in significant catalyst deactivation, short catalyst life, and low catalytic efficiency. To maintain catalytic effectiveness, the catalyst needs to be constantly replaced, increasing catalyst usage and production costs. Furthermore, aluminum trichloride in high-boiling-point substances causes equipment corrosion and pipeline blockage, severely affecting the stability of the production process. Aluminum trichloride has a boiling point of 182.7℃, but it sublimates at 177.8℃, a temperature very close to the boiling range of high-boiling-point substances (120–180℃), making it difficult to remove aluminum trichloride by distillation. Effective removal of aluminum trichloride at the forefront of high-boiling-point catalytic cracking is crucial for enhancing the stable operation of high-boiling-point cracking.

[0004] Current aluminum removal processes involve adding an aluminum-removing agent, such as EDTA or alkali metal chlorides, to the high-boiling-point material in an aluminum removal reactor. This forms a non-volatile aluminum compound mixture with the aluminum-containing impurities. The remaining components in the high-boiling-point material are then separated from this mixture by distillation, thus removing the aluminum chloride impurities. Alternatively, cooling and sedimentation crystallization can be used to preserve aluminum trichloride in a stable solid form, followed by filtration to achieve aluminum removal.

[0005] Patent CN105271246A discloses a method for preparing chlorosilane from polycrystalline silicon byproducts. First, high-boiling-point substances are kept at -5℃ to -50℃ for 10-80 hours to form crystals. The crystals are then separated by filtration. Next, an additive is added to the separated high-boiling-point substances, and the mixture is kept at 30-120℃ for 1-10 hours to form an aluminum complex. Finally, distillation yields chlorosilane free of aluminum trichloride. This method effectively removes aluminum trichloride from high-boiling-point substances, but the aluminum removal process is lengthy. The resulting crystals require a precision filter with a filtration accuracy of 0.1-10 micrometers for separation, increasing production costs. Furthermore, the filter is prone to clogging, and frequent cleaning leads to unstable production.

[0006] Patent CN 101925532A discloses a method for removing aluminum and other metal chlorides from chlorosilanes. This method involves introducing a seed crystal source into liquid chlorosilane, and then crystallizing aluminum trichloride onto the seed crystal in the liquid chlorosilane through stirring to form a solid slag, which is then separated by filtration. However, this method also suffers from the problem of easily causing equipment blockage.

[0007] Patent CN108658082A discloses a method for removing aluminum trichloride from high-boiling-point substances. This method involves cooling and crystallizing the high-boiling-point substances in a cooling and stirring tank, stirring at low temperature for 1-5 hours, then transferring them to a settling tank. The high-boiling-point substances are then allowed to settle in a nitrogen atmosphere for 1-20 hours, thereby separating a slurry containing solid impurities and metal halides. However, this method has a long processing time, and the effect of removing aluminum chloride is not ideal. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to address the above-mentioned deficiencies in the prior art by providing a method for removing aluminum from high-boiling polycrystalline silicon, a chloroaluminate ionic liquid, its application, and a catalytic cracking method for high-boiling polycrystalline silicon. The chloroaluminate ionic liquid, as a catalyst, has a highly efficient catalytic cracking effect and can decompose high-boiling polycrystalline silicon into low-boiling chlorosilanes. This method integrates aluminum removal and catalysis.

[0009] The technical solution adopted to solve the technical problem of this invention is to provide a method for removing aluminum from high-boiling polycrystalline silicon, comprising the following steps:

[0010] An ionic liquid, including pyrrolidine-based and / or piperidine-based ionic liquids, is introduced into a high-boiling polycrystalline silicon material. The mixture is then heated to allow the cations in the ionic liquid to combine with aluminum trichloride in the high-boiling polycrystalline silicon material to form an aluminochloride ionic liquid.

[0011] Preferably, the step of introducing an ionic liquid into the high-boiling polycrystalline silicon specifically involves:

[0012] Add ionic liquid with a mass fraction of 0.1-0.5% of high-boiling polycrystalline silicon.

[0013] Preferably, the pyrrolidine ionic liquid includes: N-propyl-N-methylpyrrolidine chloride ([Pr 13 ] + Cl - ) and / or N-butyl-N-methylpyrrolidine chloride ([Pr 14 ] + Cl - ).

[0014] Preferably, the piperidine-based ionic liquid includes: N-propyl-N-methylpiperidine chloride ([PP) 13 ] + Cl - ) and / or N-butyl-N-methylpiperidine chloride ([PP 14 ] + Cl - ).

[0015] Preferably, the heating temperature is 90–130°C.

[0016] The present invention also provides a chloroaluminate ionic liquid, which is prepared by the above method.

[0017] The aluminochloroaluminate ionic liquid described above in this invention is used as a catalyst for the catalytic cracking reaction of high-boiling polycrystalline silicon.

[0018] This invention also provides a method for the catalytic cracking of high-boiling polycrystalline silicon, comprising the following steps:

[0019] 1) Remove aluminum from high-boiling polycrystalline silicon using the above method;

[0020] 2) Hydrogen chloride is introduced into the high-boiling polycrystalline silicon and heated. The high-boiling polycrystalline silicon undergoes a catalytic cracking reaction to produce chlorosilane.

[0021] Step 1) Specifically, high-boiling polycrystalline silicon is added to a sealed reactor to a liquid level of 50-70%. An ionic liquid with a mass fraction of 0.1-0.5% of the high-boiling silicon is added and stirred until homogeneous. The temperature is then raised to 90-130°C, allowing the cations in the ionic liquid to combine with the aluminum trichloride in the high-boiling silicon to form aluminochloride ionic liquid. At the same time, the impurity aluminum trichloride is converted into aluminochloride ionic liquid. The resulting aluminochloride ionic liquid does not require separation.

[0022] Step 2) involves continuously introducing dry HCl into the reactor, maintaining the reactor temperature between 90 and 130°C. This catalytic cracking of high-boiling-point substances produces chlorosilanes. During this process, the chloroaluminate ionic liquid acts as a catalyst, effectively increasing the amount of chlorosilane produced. Simultaneously, the generated chlorosilanes are separated by simple distillation, yielding high-purity chlorosilanes.

[0023] In the method for removing aluminum from high-boiling polycrystalline silicon and catalytic cracking proposed in this invention, the chloroaluminate ion liquid anion comes from aluminum chloride (AlCl4). - Al2Cl7 - and Al3Cl 10 - The cation is N-propyl-N-methylpyrrolidine cation ([Pr 13 ] + ), N-butyl-N-methylpyrrolidine cation ([Pr 14 ] + ), N-propyl-N-methylpiperidine cation ([PP) 13 ] + ), N-butyl-N-methylpiperidine cation ([PP) 14 ] + One or more of them.

[0024] The structural formula of the pyrrolidine ionic liquid of the present invention is as follows, where n1 = 2, 3.

[0025]

[0026] The structural formula of the piperidine-based ionic liquid of the present invention is as follows, where n2 = 2, 3.

[0027]

[0028] Preferably, the heating temperature in step 2) is 90–130°C.

[0029] In the method for removing aluminum from high-boiling-point polycrystalline silicon and catalytic cracking proposed in this invention, the main components of the high-boiling-point polycrystalline silicon are hexachlorosilane and pentachlorosilane, and the catalytic cracking products are trichlorosilane and silicon tetrachloride. During the polycrystalline silicon production process, silicon tetrachloride needs to be converted into trichlorosilane. Most of the high-boiling-point substances are formed during this conversion process. Due to the high density and viscosity of the high-boiling-point substances, a large amount of silicon tetrachloride and trichlorosilane are emitted during their emission.

[0030] Compared with existing technologies, the method for removing aluminum from high-boiling polycrystalline silicon, the aluminochloroaluminate ionic liquid, the application, and the catalytic cracking method for high-boiling polycrystalline silicon in this invention have the following beneficial effects:

[0031] (1) It has a good aluminum removal effect and can effectively convert aluminum trichloride in polycrystalline silicon high boiling point into chloroaluminate ion liquid. The obtained chloroaluminate ion liquid is in liquid state, which avoids the problem of equipment and pipeline blockage caused by solid slag formation in traditional aluminum removal process.

[0032] (2) Chloroaluminate ionic liquid has a highly efficient catalytic cracking effect as a catalyst, which can decompose high-boiling polycrystalline silicon into low-boiling chlorosilanes. This method integrates aluminum removal and catalysis, reduces equipment investment, and lowers the production cost of enterprises.

[0033] (3) Ionic liquids have a long service life and are easy to recycle and reuse, and have good economic and environmental benefits. Detailed Implementation

[0034] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to specific embodiments.

[0035] The embodiments of this patent are described in detail below, examples of which are shown in [reference needed], wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by reference are exemplary and are only used to explain this patent, and should not be construed as limiting this patent.

[0036] Trichlorosilane (TCS) is an important raw material for the preparation of polycrystalline silicon, generally obtained through the reaction of silicon with hydrogen chloride (synthesis) or silicon powder, hydrogen, and silicon tetrachloride (cold hydrogenation). However, regardless of whether it is synthesis or cold hydrogenation, in addition to the target products such as trichlorosilane and silicon tetrachloride, a certain amount of silicon-based high-boiling compounds are also generated. These polycrystalline silicon high-boiling compounds are mainly composed of chlorosilanes with Si-Si bonds, Si-C-Si bonds, and Si-O-Si bonds.

[0037] Example 1

[0038] This embodiment provides a method for removing aluminum from high-boiling polycrystalline silicon, including the following steps:

[0039] An ionic liquid, including pyrrolidine-based and / or piperidine-based ionic liquids, is introduced into a high-boiling polycrystalline silicon substrate. Heating causes the cations in the ionic liquid to combine with aluminum trichloride in the polycrystalline silicon substrate to form an aluminochloride ionic liquid. The high-boiling polycrystalline silicon substrate and the ionic liquid then separate into strata.

[0040] This embodiment also provides a chloroaluminate ionic liquid, which is prepared by the method described above.

[0041] The aluminochloroaluminate ionic liquid described above in this invention is used as a catalyst for the catalytic cracking reaction of high-boiling polycrystalline silicon.

[0042] This embodiment also provides a catalytic cracking method for high-boiling polycrystalline silicon, including the following steps:

[0043] 1) Remove aluminum from high-boiling polycrystalline silicon using the above method;

[0044] 2) Hydrogen chloride is introduced into the high-boiling polycrystalline silicon and heated. The high-boiling polycrystalline silicon undergoes a catalytic cracking reaction to produce chlorosilane.

[0045] Compared with existing technologies, the method for removing aluminum from high-boiling polycrystalline silicon, the aluminochloroaluminate ionic liquid, the application, and the catalytic cracking method for high-boiling polycrystalline silicon in this embodiment have the following beneficial effects:

[0046] (1) It has a good aluminum removal effect and can effectively convert aluminum trichloride in polycrystalline silicon high boiling point into chloroaluminate ion liquid. The obtained chloroaluminate ion liquid is in liquid state, which avoids the problem of equipment and pipeline blockage caused by solid slag formation in traditional aluminum removal process.

[0047] (2) Chloroaluminate ionic liquid has a highly efficient catalytic cracking effect as a catalyst, which can decompose high-boiling polycrystalline silicon into low-boiling chlorosilanes. This method integrates aluminum removal and catalysis, reduces equipment investment, and lowers the production cost of enterprises.

[0048] (3) Ionic liquids have a long service life and are easy to recycle and reuse, and have good economic and environmental benefits.

[0049] Example 2

[0050] This embodiment provides a method for removing aluminum from high-boiling polycrystalline silicon, including the following steps:

[0051] Remove aluminum. Add the high-boiling polycrystalline silicon to a sealed reactor until the reactor level reaches 60%, then add 0.5% (by mass) of N-propyl-N-methylpyrrolidone chloride ([Pr... 13 ] + Cl -Stir until homogeneous, then heat to 130°C while stirring. Maintain this temperature for 2 hours. N-propyl-N-methylpyrrolidine chloride ([Pr 13 ] + Cl - The cations in ) ([Pr 13 ] + ) combines with aluminum trichloride (AlCl3) in high-boiling polycrystalline silicon to form aluminochloride ionic liquid ([Pr 13 ] + AlCl4 - ), generated [Pr 13 ] + AlCl4 - It will continue to react with aluminum trichloride, an impurity in high-boiling polycrystalline silicon, to form [Pr 13 ] + Al2Cl7 - and [Pr 13 ] + Al3Cl 10 - The obtained [Pr 13 ] + AlCl4 - 、[Pr 13 ] + Al2Cl7 - and [Pr 13 ] + Al3Cl 10 - It possesses strong Lewis acidity and can be used as a catalytically active material for the catalytic cracking of high-boiling polycrystalline silicon. High-boiling polycrystalline silicon separates from ionic liquids.

[0052] This embodiment also provides a chloroaluminate ionic liquid, which is prepared by the method described above.

[0053] The chloroaluminate ionic liquid described above in this embodiment is used as a catalyst for the catalytic cracking reaction of high-boiling polycrystalline silicon.

[0054] This embodiment also provides a catalytic cracking method for high-boiling polycrystalline silicon, including the following steps:

[0055] 1) First step, aluminum removal. Add the high-boiling polycrystalline silicon to a sealed reactor until it reaches 60% of the reactor level. Then add 0.5% (by mass) of N-propyl-N-methylpyrrolidone chloride ([Pr... 13 ] + Cl - Stir until homogeneous, then heat to 130°C while stirring. Maintain this temperature for 2 hours. N-propyl-N-methylpyrrolidine chloride ([Pr 13 ]+ Cl - The cations in ) ([Pr 13 ] + ) combines with aluminum trichloride (AlCl3) in high-boiling polycrystalline silicon to form aluminochloride ionic liquid ([Pr 13 ] + AlCl4 - ), generated [Pr 13 ] + AlCl4 - It will continue to react with aluminum trichloride, an impurity in high-boiling polycrystalline silicon, to form [Pr 13 ] + Al2Cl7 - and [Pr 13 ] + Al3Cl 10 - The obtained [Pr 13 ] + AlCl4 - 、[Pr 13 ] + Al2Cl7 - and [Pr 13 ] + Al3Cl 10 - It has strong Lewis acidity and can be used as a catalytically active material for the catalytic cracking of high-boiling polycrystalline silicon.

[0056] 2) The second step is catalytic cracking. Dry HCl is continuously introduced into the reactor, and the reactor temperature is maintained at 130℃. The high-boiling-point substances in the reactor undergo catalytic cracking to produce chlorosilanes. In this process, the chloroaluminate ionic liquid acts as a catalyst, effectively increasing the amount of chlorosilanes produced. Simultaneously, the generated chlorosilanes can be separated by simple distillation to obtain high-purity chlorosilanes.

[0057] The aluminum content of high-boiling polysilicon materials and high-boiling materials after aluminum removal reaction was tested. The test method referred to Section 5.5, "Determination of Iron, Aluminum, Chromium, Titanium, Copper, Manganese, Nickel, Boron and Phosphorus Content," of the Chinese Chemical Industry Standard HG / T 5745-2020. The aluminum removal rate was calculated as 1 - (Aluminum content of material after aluminum removal / Aluminum content of material before aluminum removal) × 100%. Gas chromatography was used to analyze the content of hexachlorosilane and pentachlorosilane components before and after the cracking of the high-boiling material. The tested and calculated aluminum removal rate was approximately 99.56%, and the primary conversion rate of the high-boiling material was approximately 93.23%. Samples of the high-boiling material were taken before entering the reactor to detect the aluminum content. After the reaction, the reactor was stopped and allowed to stand for 15-30 minutes. The supernatant of the high-boiling material was taken to detect the aluminum ion content. The results were then calculated using the formula.

[0058] Preferably, the heating temperature in step 2) is 90–130°C.

[0059] After implementation, this embodiment will solve the following technical problems: First, it converts aluminum trichloride in high-boiling polysilicon into liquid aluminochloride ionic liquid, thereby removing aluminum trichloride impurities from the high-boiling polysilicon and improving the problem of equipment and pipeline blockage; Second, it utilizes the aluminochloride ionic liquid generated in the aluminum removal step to promote the catalytic cracking reaction and improve the conversion efficiency of high-boiling polysilicon; Third, the aluminochloride ionic liquid catalyst has a higher content of active components, which can effectively solve the problem of reduced catalytic performance caused by aluminum trichloride complexation; Fourth, it uses high-boiling polysilicon generated during polysilicon production as raw material to produce silicon tetrachloride (or trichlorosilane), reducing silicon consumption; Fifth, it turns waste into treasure, realizing the green recycling of high-boiling polysilicon and impurity aluminum trichloride in the polysilicon production process, reducing waste emissions, reducing environmental pollution, and reducing chlorine and alkali consumption; Sixth, it integrates aluminum removal and catalytic cracking, reducing equipment and cost investment, and simplifying the process.

[0060] Specifically, in this embodiment, high-boiling polycrystalline silicon is added to a sealed reactor until the reactor level reaches 60%. A sample of the high-boiling polycrystalline silicon is taken and tested to determine its aluminum impurity content. Then, 0.5% (by mass) of N-propyl-N-methylpyrrolidine chloride ([Pr...) is added. 13 ] + Cl - Stir the mixture thoroughly with a stirrer, then heat it to 130°C while stirring. Maintain this temperature for 2 hours. N-propyl-N-methylpyrrolidine chloride ([Pr 13 ] + Cl - The cations in ) ([Pr 13 ] + ) combines with aluminum trichloride (AlCl3) in high-boiling polycrystalline silicon to form aluminochloride ionic liquid ([Pr 13 ] + AlCl4 - ), generated [Pr 13 ] + AlCl4 - It will continue to react with aluminum trichloride, an impurity in high-boiling polycrystalline silicon, to form [Pr 13 ] + Al2Cl7 - and [Pr 13 ] + Al3Cl 10 - The obtained [Pr 13 ] + AlCl4 - 、[Pr13 ] + Al2Cl7 - and [Pr 13 ] + Al3Cl 10 - It possesses strong Lewis acidity and can be used as a catalytically active material for the catalytic cracking of high-boiling-point polycrystalline silicon. After the reaction, the aluminum content of the high-boiling-point product was sampled and tested: After the reaction was completed, stirring was stopped and the mixture was allowed to stand for 30 minutes. The supernatant was then collected, and the aluminum impurity content in the high-boiling-point product was measured.

[0061] This embodiment provides a method for removing aluminum from high-boiling polysilicon, an aluminochloride ionic liquid, its application, and a catalytic cracking method for high-boiling polysilicon. The ionic liquid is used as both an aluminum remover and a catalyst. First, aluminum trichloride in the high-boiling polysilicon is converted into a liquid aluminochloride ionic liquid. The generated aluminochloride ionic liquid then acts as a catalyst to catalyze the cracking of the high-boiling polysilicon. Using this method, high-boiling polysilicon can be effectively recycled in a green manner, reducing silicon, chlorine, and alkali consumption in polysilicon production, as well as production costs. It also improves issues such as equipment blockage, poor aluminum removal efficiency, and low catalytic performance.

[0062] Compared with existing technologies, the method for removing aluminum from high-boiling polycrystalline silicon, the aluminochloroaluminate ionic liquid, the application, and the catalytic cracking method for high-boiling polycrystalline silicon in this embodiment have the following beneficial effects:

[0063] (1) It has a good aluminum removal effect and can effectively convert aluminum trichloride in polycrystalline silicon high boiling point into chloroaluminate ion liquid. The obtained chloroaluminate ion liquid is in liquid state, which avoids the problem of equipment and pipeline blockage caused by solid slag formation in traditional aluminum removal process.

[0064] (2) Chloroaluminate ionic liquid has a highly efficient catalytic cracking effect as a catalyst, which can decompose high-boiling polycrystalline silicon into low-boiling chlorosilanes. This method integrates aluminum removal and catalysis, reduces equipment investment, and lowers the production cost of enterprises.

[0065] (3) Ionic liquids have a long service life and are easy to recycle and reuse, and have good economic and environmental benefits.

[0066] Example 3

[0067] This embodiment provides a method for removing aluminum from high-boiling polycrystalline silicon, including the following steps:

[0068] To remove aluminum, add high-boiling polycrystalline silicon to a sealed reactor until the liquid level reaches 60%. Then add 0.5% (by mass) of N-butyl-N-methylpyrrolidone chloride ([Pr... 14 ] + Cl -Stir until homogeneous, then heat to 130°C while stirring, and maintain this temperature for 2 hours. N-Butyl-N-methylpyrrolidine chloride ([Pr...) 14 ] + Cl - The cations in ) ([Pr 14 ] + ) combines with aluminum trichloride (AlCl3) in high-boiling polycrystalline silicon to form aluminochloride ionic liquid ([Pr 14 ] + AlCl4 - ), generated [Pr 14 ] + AlCl4 - It will continue to react with aluminum trichloride, an impurity in high-boiling polycrystalline silicon, to form [Pr 14 ] + Al2Cl7 - and [Pr 14 ] + Al3Cl 10 - The obtained [Pr 14 ] + AlCl4 - 、[Pr 14 ] + Al2Cl7 - and [Pr 14 ] + Al3Cl 10 - It possesses strong Lewis acidity and can be used as a catalytically active material for the catalytic cracking of high-boiling polycrystalline silicon. High-boiling polycrystalline silicon separates from ionic liquids.

[0069] This embodiment also provides a chloroaluminate ionic liquid, which is prepared by the method described above.

[0070] The chloroaluminate ionic liquid described above in this embodiment is used as a catalyst for the catalytic cracking reaction of high-boiling polycrystalline silicon.

[0071] This embodiment also provides a catalytic cracking method for high-boiling polycrystalline silicon, including the following steps:

[0072] 1) First step, aluminum removal. Add the high-boiling polycrystalline silicon to a sealed reactor until it reaches 60% of the reactor level. Then add 0.5% (by mass) of N-butyl-N-methylpyrrolidone chloride ([Pr... 14 ] + Cl - Stir until homogeneous, then heat to 130°C while stirring, and maintain this temperature for 2 hours. N-Butyl-N-methylpyrrolidine chloride ([Pr...) 14 ]+ Cl - The cations in ) ([Pr 14 ] + ) combines with aluminum trichloride (AlCl3) in high-boiling polycrystalline silicon to form aluminochloride ionic liquid ([Pr 14 ] + AlCl4 - ), generated [Pr 14 ] + AlCl4 - It will continue to react with aluminum trichloride, an impurity in high-boiling polycrystalline silicon, to form [Pr 14 ] + Al2Cl7 - and [Pr 14 ] + Al3Cl 10 - The obtained [Pr 14 ] + AlCl4 - 、[Pr 14 ] + Al2Cl7 - and [Pr 14 ] + Al3Cl 10 - It has strong Lewis acidity and can be used as a catalytically active material for the catalytic cracking of high-boiling polycrystalline silicon.

[0073] 2) The second step is catalytic cracking. Dry HCl is continuously introduced into the reactor, and the reactor temperature is maintained at 130℃. The high-boiling-point substances in the reactor undergo catalytic cracking to produce chlorosilanes. In this process, the chloroaluminate ionic liquid acts as a catalyst, effectively increasing the amount of chlorosilanes produced. Simultaneously, the generated chlorosilanes can be separated by simple distillation to obtain high-purity chlorosilanes.

[0074] The aluminum content of high-boiling polysilicon and the high-boiling polysilicon after the aluminum removal reaction was tested. The test method referred to Section 5.5, "Determination of the Content of Iron, Aluminum, Chromium, Titanium, Copper, Manganese, Nickel, Boron and Phosphorus," in the Chinese Chemical Industry Standard HG / T 5745-2020. The aluminum removal rate was calculated as 1 - (Aluminum content of the material after aluminum removal / Aluminum content of the material before aluminum removal) × 100%. Gas chromatography was used to analyze the content of hexachlorosilane and pentachlorosilane in the high-boiling polysilicon before and after pyrolysis. The tests showed that the aluminum removal rate was approximately 99.90%, and the primary conversion rate of the high-boiling polysilicon was approximately 95.67%.

[0075] Compared with existing technologies, the method for removing aluminum from high-boiling polycrystalline silicon, the aluminochloroaluminate ionic liquid, the application, and the catalytic cracking method for high-boiling polycrystalline silicon in this embodiment have the following beneficial effects:

[0076] (1) It has a good aluminum removal effect and can effectively convert aluminum trichloride in polycrystalline silicon high boiling point into chloroaluminate ion liquid. The obtained chloroaluminate ion liquid is in liquid state, which avoids the problem of equipment and pipeline blockage caused by solid slag formation in traditional aluminum removal process.

[0077] (2) Chloroaluminate ionic liquid has a highly efficient catalytic cracking effect as a catalyst, which can decompose high-boiling polycrystalline silicon into low-boiling chlorosilanes. This method integrates aluminum removal and catalysis, reduces equipment investment, and lowers the production cost of enterprises.

[0078] (3) Ionic liquids have a long service life and are easy to recycle and reuse, and have good economic and environmental benefits.

[0079] Example 4

[0080] This embodiment provides a method for removing aluminum from high-boiling polycrystalline silicon, including the following steps:

[0081] To remove aluminum, add high-boiling polycrystalline silicon to a sealed reactor until the liquid level reaches 60%. Then add 0.5% (by mass) of N-propyl-N-methylpiperidine chloride ([PP)). 13 ] + Cl - Stir until homogeneous, then heat to 130°C while stirring. Maintain this temperature for 2 hours. N-propyl-N-methylpiperidine chloride ([PP) 13 ] + Cl - The cations in ) ([PP) 13 ] + ) combines with aluminum trichloride (AlCl3) in high-boiling polycrystalline silicon to form aluminochloride ionic liquid ([PP) 13 ] + AlCl4 - ), generated [PP 13 ] + AlCl4 - It will continue to react with aluminum trichloride, an impurity in high-boiling polycrystalline silicon, to form [PP]. 13 ] + Al2Cl7 - and [PP] 13 ] + Al3Cl 10 - The obtained [PP] 13 ] + AlCl4 - , [PP 13 ] + Al2Cl7 - and [PP]13 ] + Al3Cl 10 - It possesses strong Lewis acidity and can be used as a catalytically active material for the catalytic cracking of high-boiling polycrystalline silicon. High-boiling polycrystalline silicon separates from ionic liquids.

[0082] This embodiment also provides a chloroaluminate ionic liquid, which is prepared by the method described above.

[0083] The chloroaluminate ionic liquid described above in this embodiment is used as a catalyst for the catalytic cracking reaction of high-boiling polycrystalline silicon.

[0084] This embodiment also provides a catalytic cracking method for high-boiling polycrystalline silicon, including the following steps:

[0085] 1) First step, aluminum removal. Add the high-boiling polycrystalline silicon to a sealed reactor until it reaches 60% of the reactor level. Then add 0.5% (by mass) of N-propyl-N-methylpiperidine chloride ([PP... 13 ] + Cl - Stir until homogeneous, then heat to 130°C while stirring. Maintain this temperature for 2 hours. N-propyl-N-methylpiperidine chloride ([PP) 13 ] + Cl - The cations in ) ([PP) 13 ] + ) combines with aluminum trichloride (AlCl3) in high-boiling polycrystalline silicon to form aluminochloride ionic liquid ([PP) 13 ] + AlCl4 - ), generated [PP 13 ] + AlCl4 - It will continue to react with aluminum trichloride, an impurity in high-boiling polycrystalline silicon, to form [PP]. 13 ] + Al2Cl7 - and [PP] 13 ] + Al3Cl 10 - The obtained [PP] 13 ] + AlCl4 - , [PP 13 ] + Al2Cl7 - and [PP] 13 ] + Al3Cl 10 -It has strong Lewis acidity and can be used as a catalytically active material for the catalytic cracking of high-boiling polycrystalline silicon.

[0086] 2) The second step is catalytic cracking. Dry HCl is continuously introduced into the reactor, and the reactor temperature is maintained at 130℃. The high-boiling polycrystalline silicon in the reactor undergoes catalytic cracking to produce chlorosilanes. In this process, the chloroaluminate ionic liquid acts as a catalyst, effectively increasing the amount of chlorosilanes produced. Simultaneously, the generated chlorosilanes can be separated by simple distillation to obtain high-purity chlorosilanes.

[0087] The aluminum content of high-boiling polysilicon materials and the high-boiling-point product after aluminum removal reaction was tested. The test method referred to Section 5.5, "Determination of Iron, Aluminum, Chromium, Titanium, Copper, Manganese, Nickel, Boron, and Phosphorus Content," of the Chinese Chemical Industry Standard HG / T 5745-2020. The aluminum removal rate was calculated as 1 - (Aluminum content of material after aluminum removal / Aluminum content of material before aluminum removal) × 100%. Gas chromatography was used to analyze the content of hexachlorosilane and pentachlorosilane in the high-boiling polysilicon material before and after pyrolysis. The test results showed that the aluminum removal rate was approximately 99.21%, and the primary conversion rate of the high-boiling polysilicon was approximately 91.26%.

[0088] Compared with existing technologies, the method for removing aluminum from high-boiling polycrystalline silicon, the aluminochloroaluminate ionic liquid, the application, and the catalytic cracking method for high-boiling polycrystalline silicon in this embodiment have the following beneficial effects:

[0089] (1) It has a good aluminum removal effect and can effectively convert aluminum trichloride in polycrystalline silicon high boiling point into chloroaluminate ion liquid. The obtained chloroaluminate ion liquid is in liquid state, which avoids the problem of equipment and pipeline blockage caused by solid slag formation in traditional aluminum removal process.

[0090] (2) Chloroaluminate ionic liquid has a highly efficient catalytic cracking effect as a catalyst, which can decompose high-boiling polycrystalline silicon into low-boiling chlorosilanes. This method integrates aluminum removal and catalysis, reduces equipment investment, and lowers the production cost of enterprises.

[0091] (3) Ionic liquids have a long service life and are easy to recycle and reuse, and have good economic and environmental benefits.

[0092] Example 5

[0093] This embodiment provides a method for removing aluminum from high-boiling polycrystalline silicon, including the following steps:

[0094] Aluminum removal. High-boiling polycrystalline silicon is added to a sealed reactor until the liquid level reaches 60%. Then, 0.5% (by mass) of N-butyl-N-methylpiperidine chloride ([PP)) is added to the high-boiling polycrystalline silicon. 14 ] + Cl- Stir until homogeneous, then heat to 130°C while stirring, and maintain this temperature for 2 hours. N-Butyl-N-methylpiperidine chloride ([PP) 14 ] + Cl - The cations in ) ([PP) 14 ] + ) combines with aluminum trichloride (AlCl3) in high-boiling polycrystalline silicon to form aluminochloride ionic liquid ([PP) 14 ] + AlCl4 - ), generated [PP 14 ] + AlCl4 - It will continue to react with aluminum trichloride, an impurity in high-boiling polycrystalline silicon, to form [PP]. 14 ] + Al2Cl7 - and [PP] 14 ] + Al3Cl 10 - The obtained [PP] 14 ] + AlCl4 - , [PP 14 ] + Al2Cl7 - and [PP] 14 ] + Al3Cl 10 - It exhibits strong Lewis acidity and can be used for the catalytic cracking of high-boiling polycrystalline silicon. High-boiling polycrystalline silicon separates from ionic liquids.

[0095] This embodiment also provides a chloroaluminate ionic liquid, which is prepared by the method described above.

[0096] The chloroaluminate ionic liquid described above in this embodiment is used as a catalyst for the catalytic cracking reaction of high-boiling polycrystalline silicon.

[0097] This embodiment also provides a catalytic cracking method for high-boiling polycrystalline silicon, including the following steps:

[0098] 1) First step, aluminum removal. Add the high-boiling polycrystalline silicon to a sealed reactor until it reaches 60% of the reactor level. Then add 0.5% (by mass) of N-butyl-N-methylpiperidine chloride ([PP... 14 ] + Cl - Stir until homogeneous, then heat to 130°C while stirring, and maintain this temperature for 2 hours. N-Butyl-N-methylpiperidine chloride ([PP) 14 ]+ Cl - The cations in ) ([PP) 14 ] + ) combines with aluminum trichloride (AlCl3) in high-boiling polycrystalline silicon to form aluminochloride ionic liquid ([PP) 14 ] + AlCl4 - ), generated [PP 14 ] + AlCl4 - It will continue to react with aluminum trichloride, an impurity in high-boiling polycrystalline silicon, to form [PP]. 14 ] + Al2Cl7 - and [PP] 14 ] + Al3Cl 10 - The obtained [PP] 14 ] + AlCl4 - , [PP 14 ] + Al2Cl7 - and [PP] 14 ] + Al3Cl 10 - It has strong Lewis acidity and can be used for the catalytic cracking of high-boiling polycrystalline silicon.

[0099] 2) The second step is catalytic cracking. Dry HCl is continuously introduced into the reactor, and the reactor temperature is maintained at 130℃. The high-boiling polycrystalline silicon in the reactor undergoes catalytic cracking to produce chlorosilanes. In this process, the chloroaluminate ionic liquid acts as a catalyst, effectively increasing the amount of chlorosilanes produced. Simultaneously, the generated chlorosilanes can be separated by simple distillation to obtain high-purity chlorosilanes.

[0100] The aluminum content of high-boiling polysilicon and the high-boiling product after the aluminum removal reaction was tested. The test method referred to Section 5.5, "Determination of Iron, Aluminum, Chromium, Titanium, Copper, Manganese, Nickel, Boron and Phosphorus Content," of the Chinese Chemical Industry Standard HG / T 5745-2020. The aluminum removal rate was calculated as 1 - (Aluminum content of the material after aluminum removal / Aluminum content of the material before aluminum removal) × 100%. Gas chromatography was used to analyze the content of hexachlorosilane and pentachlorosilane in the high-boiling polysilicon before and after pyrolysis. The tested and calculated aluminum removal rate was approximately 98.31%, and the primary conversion rate of the high-boiling polysilicon was approximately 94.53%.

[0101] Compared with existing technologies, the method for removing aluminum from high-boiling polycrystalline silicon, the aluminochloroaluminate ionic liquid, the application, and the catalytic cracking method for high-boiling polycrystalline silicon in this embodiment have the following beneficial effects:

[0102] (1) It has a good aluminum removal effect and can effectively convert aluminum trichloride in polycrystalline silicon high boiling point into chloroaluminate ion liquid. The obtained chloroaluminate ion liquid is in liquid state, which avoids the problem of equipment and pipeline blockage caused by solid slag formation in traditional aluminum removal process.

[0103] (2) Chloroaluminate ionic liquid has a highly efficient catalytic cracking effect as a catalyst, which can decompose high-boiling polycrystalline silicon into low-boiling chlorosilanes. This method integrates aluminum removal and catalysis, reduces equipment investment, and lowers the production cost of enterprises.

[0104] (3) Ionic liquids have a long service life and are easy to recycle and reuse, and have good economic and environmental benefits.

[0105] Example 6

[0106] This embodiment provides a method for removing aluminum from high-boiling polycrystalline silicon, including the following steps:

[0107] Remove aluminum. Add high-boiling polycrystalline silicon to a sealed reactor until the reactor level reaches 60%, then add 0.3% (by mass) of N-butyl-N-methylpyrrolidone chloride ([Pr... 14 ] + Cl - ) and N-butyl-N-methylpiperidine chloride ([PP 14 ] + Cl - (The mass ratio of the two is 1:1) Stir evenly, heat to 90℃ while stirring, and maintain this temperature for 2 hours. N-Butyl-N-methylpyrrolidine chloride ([Pr 14 ] + Cl - The cations in ) ([Pr 14 ] + ) combines with aluminum trichloride (AlCl3) in high-boiling polycrystalline silicon to form aluminochloride ionic liquid ([Pr 14 ] + AlCl4 - ), generated [Pr 14 ] + AlCl4 - It will continue to react with aluminum trichloride, an impurity in high-boiling polycrystalline silicon, to form [Pr 14 ] + Al2Cl7 - and [Pr 14 ] + Al3Cl 10 - The obtained [Pr 14 ] +AlCl4 - 、[Pr 14 ] + Al2Cl7 - and [Pr 14 ] + Al3Cl 10 - It possesses strong Lewis acidity and can be used as a catalytically active substance for the catalytic cracking of high-boiling polycrystalline silicon; N-butyl-N-methylpiperidine chloride ([PP 14 ] + Cl - The cations in ) ([PP) 14 ] + ) combines with aluminum trichloride (AlCl3) in high-boiling polycrystalline silicon to form aluminochloride ionic liquid ([PP) 14 ] + AlCl4 - ), generated [PP 14 ] + AlCl4 - It will continue to react with aluminum trichloride, an impurity in high-boiling polycrystalline silicon, to form [PP]. 14 ] + Al2Cl7 - and [PP] 14 ] + Al3Cl 10 - The obtained [PP] 14 ] + AlCl4 - , [PP 14 ] + Al2Cl7 - and [PP] 14 ] + Al3Cl 10 - It exhibits strong Lewis acidity and can be used for the catalytic cracking of high-boiling polycrystalline silicon. High-boiling polycrystalline silicon separates from ionic liquids.

[0108] This embodiment also provides a chloroaluminate ionic liquid, which is prepared by the method described above.

[0109] The chloroaluminate ionic liquid described above in this embodiment is used as a catalyst for the catalytic cracking reaction of high-boiling polycrystalline silicon.

[0110] This embodiment also provides a catalytic cracking method for high-boiling polycrystalline silicon, including the following steps:

[0111] 1) Aluminum removal. High-boiling polycrystalline silicon is added to a sealed reactor until the liquid level reaches 60%. Then, 0.3% (by mass) of N-butyl-N-methylpyrrolidone chloride ([Pr...) is added. 14 ] + Cl - ) and N-butyl-N-methylpiperidine chloride ([PP 14 ] + Cl - (The mass ratio of the two is 1:1) Stir evenly, heat to 90℃ while stirring, and maintain this temperature for 2 hours. N-Butyl-N-methylpyrrolidine chloride ([Pr 14 ] + Cl - The cations in ) ([Pr 14 ] + ) combines with aluminum trichloride (AlCl3) in high-boiling polycrystalline silicon to form aluminochloride ionic liquid ([Pr 14 ] + AlCl4 - ), generated [Pr 14 ] + AlCl4 - It will continue to react with aluminum trichloride, an impurity in high-boiling polycrystalline silicon, to form [Pr 14 ] + Al2Cl7 - and [Pr 14 ] + Al3Cl 10 - The obtained [Pr 14 ] + AlCl4 - 、[Pr 14 ] + Al2Cl7 - and [Pr 14 ] + Al3Cl 10 - It possesses strong Lewis acidity and can be used as a catalytically active substance for the catalytic cracking of high-boiling polycrystalline silicon; N-butyl-N-methylpiperidine chloride ([PP 14 ] + Cl - The cations in ) ([PP) 14 ] + ) combines with aluminum trichloride (AlCl3) in high-boiling polycrystalline silicon to form aluminochloride ionic liquid ([PP) 14 ] + AlCl4 - ), generated [PP 14 ] + AlCl4- It will continue to react with aluminum trichloride, an impurity in high-boiling polycrystalline silicon, to form [PP]. 14 ] + Al2Cl7 - and [PP] 14 ] + Al3Cl 10 - The obtained [PP] 14 ] + AlCl4 - , [PP 14 ] + Al2Cl7 - and [PP] 14 ] + Al3Cl 10 - It has strong Lewis acidity and can be used for the catalytic cracking of high-boiling polycrystalline silicon.

[0112] 2) Catalytic cracking. Dry HCl is continuously introduced into the reactor, and the reactor temperature is maintained at 90℃. High-boiling-point substances in the reactor undergo catalytic cracking to produce chlorosilanes. In this process, the chloroaluminate ionic liquid acts as a catalyst, effectively increasing the amount of chlorosilanes produced. Simultaneously, the generated chlorosilanes can be separated by simple distillation to obtain high-purity chlorosilanes.

[0113] The aluminum content of high-boiling polysilicon and the high-boiling product after aluminum removal reaction was tested. The test method referred to Section 5.5, "Determination of Iron, Aluminum, Chromium, Titanium, Copper, Manganese, Nickel, Boron and Phosphorus Content," of the Chinese Chemical Industry Standard HG / T 5745-2020. The aluminum removal rate was calculated as 1 - (Aluminum content of material after aluminum removal / Aluminum content of material before aluminum removal) × 100%. Gas chromatography was used to analyze the content of hexachlorosilane and pentachlorosilane in the high-boiling polysilicon before and after pyrolysis. The test results showed that the aluminum removal rate was approximately 99.11%, and the primary conversion rate of the high-boiling polysilicon was approximately 92.3%.

[0114] Compared with existing technologies, the method for removing aluminum from high-boiling polycrystalline silicon, the aluminochloroaluminate ionic liquid, the application, and the catalytic cracking method for high-boiling polycrystalline silicon in this embodiment have the following beneficial effects:

[0115] (1) It has a good aluminum removal effect and can effectively convert aluminum trichloride in polycrystalline silicon high boiling point into chloroaluminate ion liquid. The obtained chloroaluminate ion liquid is in liquid state, which avoids the problem of equipment and pipeline blockage caused by solid slag formation in traditional aluminum removal process.

[0116] (2) Chloroaluminate ionic liquid has a highly efficient catalytic cracking effect as a catalyst, which can decompose high-boiling polycrystalline silicon into low-boiling chlorosilanes. This method integrates aluminum removal and catalysis, reduces equipment investment, and lowers the production cost of enterprises.

[0117] (3) Ionic liquids have a long service life and are easy to recycle and reuse, and have good economic and environmental benefits.

[0118] Example 7

[0119] This embodiment provides a method for removing aluminum from high-boiling polycrystalline silicon, including the following steps:

[0120] Remove aluminum. Add high-boiling polycrystalline silicon to a sealed reactor until the reactor level reaches 60%, then add 0.1% (by mass) of N-propyl-N-methylpiperidine chloride ([PP... 13 ] + Cl - ) and N-butyl-N-methylpiperidine chloride ([PP 14 ] + Cl - (The mass ratio of the two is 2:1) Stir evenly, heat to 110℃ while stirring, and maintain this temperature for 2 hours. N-propyl-N-methylpiperidine chloride ([PP 13 ] + Cl - The cations in ) ([PP) 13 ] + ) combines with aluminum trichloride (AlCl3) in high-boiling polycrystalline silicon to form aluminochloride ionic liquid ([PP) 13 ] + AlCl4 - ), generated [PP 13 ] + AlCl4 - It will continue to react with aluminum trichloride, an impurity in high-boiling polycrystalline silicon, to form [PP]. 13 ] + Al2Cl7 - and [PP] 13 ] + Al3Cl 10 - The obtained [PP] 13 ] + AlCl4 - , [PP 13 ] + Al2Cl7 - and [PP] 13 ] + Al3Cl 10 -It possesses strong Lewis acidity and can be used as a catalytically active substance for the catalytic cracking of high-boiling polycrystalline silicon; N-butyl-N-methylpiperidine chloride ([PP 14 ] + Cl - The cations in ) ([PP) 14 ] + ) combines with aluminum trichloride (AlCl3) in high-boiling polycrystalline silicon to form aluminochloride ionic liquid ([PP) 14 ] + AlCl4 - ), generated [PP 14 ] + AlCl4 - It will continue to react with aluminum trichloride, an impurity in high-boiling polycrystalline silicon, to form [PP]. 14 ] + Al2Cl7 - and [PP] 14 ] + Al3Cl 10 - The obtained [PP] 14 ] + AlCl4 - , [PP 14 ] + Al2Cl7 - and [PP] 14 ] + Al3Cl 10 - It exhibits strong Lewis acidity and can be used for the catalytic cracking of high-boiling polycrystalline silicon. High-boiling polycrystalline silicon separates from ionic liquids.

[0121] This embodiment also provides a chloroaluminate ionic liquid, which is prepared by the method described above.

[0122] The chloroaluminate ionic liquid described above in this embodiment is used as a catalyst for the catalytic cracking reaction of high-boiling polycrystalline silicon.

[0123] This embodiment also provides a catalytic cracking method for high-boiling polycrystalline silicon, including the following steps:

[0124] 1) First step, aluminum removal. Add the high-boiling polycrystalline silicon to a sealed reactor until it reaches 60% of the reactor's liquid level. Then add 0.1% (by mass) of N-propyl-N-methylpiperidine chloride ([PP... 13 ] + Cl - ) and N-butyl-N-methylpiperidine chloride ([PP 14 ] + Cl -(The mass ratio of the two is 2:1) Stir evenly, heat to 110℃ while stirring, and maintain this temperature for 2 hours. N-propyl-N-methylpiperidine chloride ([PP 13 ] + Cl - The cations in ) ([PP) 13 ] + ) combines with aluminum trichloride (AlCl3) in high-boiling polycrystalline silicon to form aluminochloride ionic liquid ([PP) 13 ] + AlCl4 - ), generated [PP 13 ] + AlCl4 - It will continue to react with aluminum trichloride, an impurity in high-boiling polycrystalline silicon, to form [PP]. 13 ] + Al2Cl7 - and [PP] 13 ] + Al3Cl 10 - The obtained [PP] 13 ] + AlCl4 - , [PP 13 ] + Al2Cl7 - and [PP] 13 ] + Al3Cl 10 - It possesses strong Lewis acidity and can be used as a catalytically active substance for the catalytic cracking of high-boiling polycrystalline silicon; N-butyl-N-methylpiperidine chloride ([PP 14 ] + Cl - The cations in ) ([PP) 14 ] + ) combines with aluminum trichloride (AlCl3) in high-boiling polycrystalline silicon to form aluminochloride ionic liquid ([PP) 14 ] + AlCl4 - ), generated [PP 14 ] + AlCl4 - It will continue to react with aluminum trichloride, an impurity in high-boiling polycrystalline silicon, to form [PP]. 14 ] + Al2Cl7 - and [PP] 14 ] + Al3Cl 10 - The obtained [PP] 14 ] +AlCl4 - , [PP 14 ] + Al2Cl7 - and [PP] 14 ] + Al3Cl 10 - It has strong Lewis acidity and can be used for the catalytic cracking of high-boiling polycrystalline silicon.

[0125] 2) The second step is catalytic cracking. Dry HCl is continuously introduced into the reactor, and the reactor temperature is maintained at 110℃. The high-boiling polycrystalline silicon in the reactor undergoes catalytic cracking to produce chlorosilanes. In this process, the chloroaluminate ionic liquid acts as a catalyst, effectively increasing the amount of chlorosilanes produced. Simultaneously, the generated chlorosilanes can be separated by simple distillation to obtain high-purity chlorosilanes.

[0126] The aluminum content of high-boiling polysilicon and the high-boiling product after aluminum removal reaction was tested. The test method referred to Section 5.5, "Determination of Iron, Aluminum, Chromium, Titanium, Copper, Manganese, Nickel, Boron and Phosphorus Content," of the Chinese Chemical Industry Standard HG / T 5745-2020. The aluminum removal rate was calculated as 1 - (Aluminum content of material after aluminum removal / Aluminum content of material before aluminum removal) × 100%. Gas chromatography was used to analyze the content of hexachlorosilane and pentachlorosilane in the high-boiling polysilicon before and after pyrolysis. The test results showed that the aluminum removal rate was approximately 98.97%, and the primary conversion rate of the high-boiling polysilicon was approximately 93.8%.

[0127] Compared with existing technologies, the method for removing aluminum from high-boiling polycrystalline silicon, the aluminochloroaluminate ionic liquid, the application, and the catalytic cracking method for high-boiling polycrystalline silicon in this embodiment have the following beneficial effects:

[0128] (1) It has a good aluminum removal effect and can effectively convert aluminum trichloride in polycrystalline silicon high boiling point into chloroaluminate ion liquid. The obtained chloroaluminate ion liquid is in liquid state, which avoids the problem of equipment and pipeline blockage caused by solid slag formation in traditional aluminum removal process.

[0129] (2) Chloroaluminate ionic liquid has a highly efficient catalytic cracking effect as a catalyst, which can decompose high-boiling polycrystalline silicon into low-boiling chlorosilanes. This method integrates aluminum removal and catalysis, reduces equipment investment, and lowers the production cost of enterprises.

[0130] (3) Ionic liquids have a long service life and are easy to recycle and reuse, and have good economic and environmental benefits.

[0131] Comparative Example 1

[0132] This comparative example also provides a catalytic cracking method for high-boiling polycrystalline silicon, which is basically the same as that in Example 2, except that:

[0133] No ionic liquid was added in this comparative example. Dry HCl was continuously introduced into the reactor, and the reactor temperature was maintained at 130°C. The high-boiling polycrystalline silicon in the reactor decomposed to produce chlorosilanes, which could be separated by simple distillation to obtain high-purity chlorosilanes.

[0134] The aluminum content of high-boiling-point polycrystalline silicon materials and the chlorosilane materials distilled after aluminum removal and pyrolysis were tested. The test method referred to Section 5.5, "Determination of Iron, Aluminum, Chromium, Titanium, Copper, Manganese, Nickel, Boron, and Phosphorus Content," of the Chinese Chemical Industry Standard HG / T 5745-2020. The aluminum removal rate was calculated as 1 - (Aluminum content of material after aluminum removal / Aluminum content of material before aluminum removal) × 100%. Gas chromatography was used to analyze the component content of hexachlorosilane and pentachlorosilane before and after pyrolysis of the high-boiling-point material. The tested and calculated aluminum removal rate was approximately 26.30%, and the primary conversion rate of the high-boiling-point material was approximately 5.31%.

[0135] Comparative Example 2

[0136] This comparative example also provides a catalytic cracking method for high-boiling polycrystalline silicon, which is basically the same as that in Example 2, except that:

[0137] In this comparative example, no ionic liquid was added. Dry HCl was continuously introduced into the reactor, and 0.5% of a commercial organic amine catalyst was added. The reactor temperature was maintained at 130°C. The high-boiling substances in the reactor were catalytically decomposed to produce chlorosilanes. The chlorosilanes produced could be separated by simple distillation to obtain high-purity chlorosilanes.

[0138] The aluminum content of high-boiling polysilicon materials and the high-boiling-point residue after aluminum removal reaction was tested. The test method referred to Section 5.5, "Determination of Iron, Aluminum, Chromium, Titanium, Copper, Manganese, Nickel, Boron, and Phosphorus Content," of the Chinese Chemical Industry Standard HG / T 5745-2020. The aluminum removal rate was calculated as 1 - (Aluminum content of material after aluminum removal / Aluminum content of material before aluminum removal) × 100%. Gas chromatography was used to analyze the content of hexachlorosilane and pentachlorosilane components before and after the cracking of the high-boiling-point material. The tested and calculated aluminum removal rate was approximately 68.93%, and the primary conversion rate of the high-boiling-point residue was approximately 86.57%.

[0139] The present invention provides a method for aluminum removal and catalytic cracking of high-boiling polycrystalline silicon. By first efficiently converting aluminum trichloride impurities in the high-boiling polycrystalline silicon raw material into liquid aluminochloride ionic liquid using an ionic liquid, the traditional aluminum removal method can avoid the formation of solid slag that blocks equipment and pipelines. At the same time, the aluminochloride ionic liquid enables the catalytic cracking reaction of high-boiling polycrystalline silicon to have a high cracking rate.

[0140] Table 1. Composition of high-boiling-point polysilicon materials in the examples and comparative examples.

[0141]

[0142] Table 2. Composition of high-boiling-point substances in polycrystalline silicon after aluminum removal in Example 2.

[0143]

[0144] It is understood that the above embodiments are merely exemplary implementations used to illustrate the principles of the present invention, and the present invention is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A process for the catalytic cracking of polysilicon high boilers, characterized in that, Includes the following steps: 1) Pass an ionic liquid, including pyrrolidine ionic liquid and / or piperidine ionic liquid, into a high-boiling polycrystalline silicon material, and heat it to allow the cations in the ionic liquid to combine with aluminum trichloride in the high-boiling polycrystalline silicon material to form aluminochloride ionic liquid. 2) Hydrogen chloride is introduced into the high-boiling polycrystalline silicon and heated to 90~130℃. The high-boiling polycrystalline silicon undergoes a catalytic cracking reaction to produce chlorosilane. In this process, the chloroaluminate ionic liquid acts as a catalyst.

2. The catalytic cracking method for high-boiling polycrystalline silicon compounds according to claim 1, characterized in that, Step 1) involves introducing an ionic liquid into the high-boiling polycrystalline silicon material, specifically as follows: Add ionic liquid with a mass fraction of 0.1-0.5% of high-boiling polycrystalline silicon.

3. The catalytic cracking method for high-boiling polycrystalline silicon compounds according to claim 1, characterized in that, Pyrrolidine ionic liquids include: N-propyl-N-methylpyrrolidine chloride and / or N-butyl-N-methylpyrrolidine chloride.

4. The catalytic cracking method for high-boiling polycrystalline silicon compounds according to claim 1, characterized in that, Piperidine ionic liquids include N-propyl-N-methylpiperidine chloride and / or N-butyl-N-methylpiperidine chloride.

5. The catalytic cracking method for high-boiling polycrystalline silicon compounds according to claim 1, characterized in that, The heating temperature in step 1) is 90~130℃.

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