Method for removing trace boron and phosphorus impurities in trichlorosilane by using choline ionic liquid
By reacting choline-based ionic liquids with trichlorosilane to generate high-boiling-point complexes, and then using distillation separation technology, the problem of removing boron and phosphorus impurities in polycrystalline silicon production was solved, achieving efficient and low-cost impurity removal and improving the purity of polycrystalline silicon.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-31
- Publication Date
- 2026-03-27
AI Technical Summary
Existing technologies struggle to efficiently and cost-effectively remove boron and phosphorus impurities from trichlorosilane during polysilicon production. Traditional methods, such as distillation, are energy-intensive, while adsorption methods suffer from low selectivity and efficiency. Furthermore, the complexation method presents significant challenges in selecting the appropriate complexing agent.
Choline-based ionic liquids are used as complexing agents to react with trichlorosilane to form high-boiling-point complexes. By separating these complexes through distillation, boron and phosphorus impurities are selectively removed by utilizing the strong complexing ability and structural tunability of non-toluenesulfonic acid choline ionic liquids.
It significantly reduced energy consumption in the distillation process, improved impurity removal efficiency, and achieved efficient removal of 99.62% of boron impurities and 98.88% of phosphorus impurities, providing a solution for the preparation of high-purity polycrystalline silicon.
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Figure CN121735260A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of polycrystalline silicon industrial production technology, and particularly relates to a method for removing trace boron and phosphorus impurities from trichlorosilane using choline-based ionic liquids. Background Technology
[0002] Polycrystalline silicon is a core material for photovoltaic power generation and semiconductor manufacturing, and its purity directly determines the conversion efficiency of solar cells and the performance of integrated circuits. Currently, the industrial production of polycrystalline silicon mainly uses the modified Siemens process, which primarily involves two steps: First, metallurgical-grade silicon powder reacts with hydrogen chloride gas to produce trichlorosilane, which is then purified through multiple distillations. Subsequently, high-purity chlorosilane raw materials are reduced by hydrogen in a reduction furnace, and polycrystalline silicon is produced by chemical vapor deposition. The concentrations of donor impurities (represented by phosphorus) and acceptor impurities (represented by boron) are key parameters in polycrystalline silicon technical specifications. The presence of both impurities affects carrier concentration and alters conductivity, thus severely impacting the conductivity and photoelectric conversion efficiency of downstream products. Therefore, controlling impurities originating from raw materials and reactions is a core challenge in polycrystalline silicon production. Elements such as boron and phosphorus contained in metallurgical-grade silicon powder are converted into key impurities such as boron trichloride (BCl3) and phosphorus trichloride (PCl3). These two impurities have similar physicochemical properties to trichlorosilane, making them difficult to remove efficiently using traditional purification processes, thus becoming a bottleneck problem restricting the production of high-purity polysilicon. Therefore, developing efficient and low-cost boron and phosphorus impurity removal technologies is of great significance for improving the quality of polysilicon.
[0003] Currently, the main methods for removing boron and phosphorus impurities in industrial processes include distillation, adsorption, and complexation. Distillation primarily utilizes the difference in relative volatility of substances to achieve separation. Most impurities in trichlorosilane can be removed to low concentrations through multi-stage distillation. However, boron and phosphorus impurities, represented by phosphorus trichloride and boron trichloride, have boiling points close to those of trichlorosilane. Further purification often requires enhanced separation methods such as increasing the reflux ratio and reducing the yield, which directly leads to increased energy consumption and decreased production capacity, significantly reducing economic benefits. Adsorption utilizes the difference in intermolecular forces between the adsorbate and adsorbent surface molecules to achieve purification. Adsorption relies on the interaction forces (such as van der Waals forces and chemical bonds) between the adsorbent and impurity molecules to achieve selective adsorption. Commonly used adsorbents in industry include activated carbon, silica gel, and ion exchange resins. While adsorption offers advantages such as simple operation and low cost, it generally suffers from limited adsorption capacity, low selectivity, and a sharp decline in efficiency after reaching the adsorption capacity, making it difficult to meet the requirements for deep removal of boron and phosphorus impurities from electronic-grade polycrystalline silicon. In comparison, the complexation method has become an important direction for the purification of chlorosilanes due to its low energy consumption and high separation efficiency, but the selection of the complexing agent is one of the key challenges. Summary of the Invention
[0004] To address the aforementioned technical problems, this invention proposes a method for removing trace boron and phosphorus impurities from trichlorosilane using choline-based ionic liquids. Ionic liquids are a class of low-temperature molten salts composed of specific cations and anions, existing in a liquid state at room temperature and pressure, and possessing characteristics such as low saturated vapor pressure, high stability, and tunable structure and properties. This invention, guided by Lewis acid-base theory, designs its cations and anions, allowing non-p-toluenesulfonic acid choline ionic liquids to be used as highly efficient complexing agents, thereby significantly reducing energy consumption in subsequent distillation processes and improving overall purification efficiency.
[0005] To achieve the above objectives, the present invention provides the following technical solution:
[0006] This invention provides a method for removing trace boron and phosphorus impurities from trichlorosilane using choline-based ionic liquids, comprising the following steps: adding choline-based ionic liquids to crude trichlorosilane products to carry out a complexation reaction, and distilling the resulting reaction mixture to obtain purified trichlorosilane.
[0007] The mass ratio of the crude trichlorosilane product to the choline-based ionic liquid is (800-1250):1;
[0008] The choline-based ionic liquid is a non-p-toluenesulfonic acid choline ionic liquid;
[0009] The temperature of the complexation reaction is not lower than 20°C.
[0010] Non-toluenesulfonic acid choline ionic liquids, as a green medium with high stability, low volatility and structural tunability, are dominated by anions. They selectively complex with BCl3, which is strongly electron-deficient, and PCl3, which is weak Lewis base, through electron-donating or electron-withdrawing effects. Boron impurities, represented by BCl3, mainly act as electron acceptors, while phosphorus impurities, represented by PCl3, act as electron donors. Meanwhile, although the cations do not directly coordinate, the exposure and electron migration efficiency of the anions are enhanced through microscopic solvent environment regulation. For example, the hydroxyl groups and quaternary ammonium salt structures in non-p-toluenesulfonic acid choline ionic liquids can effectively coordinate with phosphorus impurities. Furthermore, by introducing anions containing ester or pyridine functional groups for structural regulation, the selective complexation ability for boron impurities can be further enhanced. Combined with the extremely low saturated vapor pressure of non-p-toluenesulfonic acid choline ionic liquids, they remain in the liquid phase under distillation conditions without introducing new volatiles during distillation, significantly reducing subsequent distillation energy consumption and improving purification efficiency, thus achieving the synergistic removal of both boron and phosphorus impurities. Non-p-toluenesulfonic acid choline ionic liquids are inexpensive, low in toxicity, and biodegradable, easily separated from the product and recycled, effectively reducing reagent consumption and environmental pollution risks. The strong complexing ability and designable molecular structure of non-p-toluenesulfonic acid choline ionic liquids provide a new technical pathway for the efficient and precise removal of boron and phosphorus impurities from trichlorosilane.
[0011] Furthermore, the choline-based ionic liquid is selected from acetic choline ionic liquid, lactic choline ionic liquid, methanesulfonate choline ionic liquid, triazole choline ionic liquid, or 2-hydroxypyridinized choline ionic liquid.
[0012] Furthermore, the triazole choline ionic liquid is a 1,2,4-triazole choline ionic liquid.
[0013] Furthermore, the preparation method of the choline-based ionic liquid is as follows: choline hydroxide is mixed with the corresponding acid to cause an acid-base neutralization reaction in the system, water is removed by rotary evaporation, and the mixture is washed and dried to obtain the choline-based ionic liquid;
[0014] Alternatively, choline chloride can be mixed with the corresponding anionic compound in a solvent to induce anion displacement reaction, remove the precipitated byproducts and solvent, and then dried to obtain the choline-based ionic liquid.
[0015] Furthermore, the corresponding acid is selected from acetic acid, methanesulfonic acid, or lactic acid; the corresponding anionic compound is selected from 2-hydroxypyridine or 1,2,4-triazole.
[0016] Furthermore, the complexation reaction is carried out at a temperature of 25-75°C for 1 hour and at a pressure of 0.1 MPa; preferably, the complexation reaction is carried out at a temperature of 25-40°C.
[0017] Furthermore, the distillation temperature is 50-90℃ and the pressure is 0.1 MPa; preferably, the distillation temperature is 50-70℃.
[0018] Compared with the prior art, the present invention has the following advantages and technical effects:
[0019] This invention removes trace boron and phosphorus impurities from chlorosilanes using non-p-toluenesulfonic acid choline ionic liquids under strictly anhydrous conditions. The removal efficiency for boron impurities in crude trichlorosilane is up to 99.62%, and the removal efficiency for phosphorus impurities is up to 98.88%. Attached Figure Description
[0020] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:
[0021] Figure 1 This is a flowchart illustrating the process of removing trace boron and phosphorus impurities from chlorosilanes using choline-based ionic liquids according to the present invention. Detailed Implementation
[0022] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.
[0023] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.
[0024] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.
[0025] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.
[0026] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.
[0027] Embodiments of the present invention provide a method for removing trace boron and phosphorus impurities from trichlorosilane using choline-based ionic liquids, the flowchart of which is shown below. Figure 1 As shown, the process includes the following steps: adding choline-based ionic liquid as a complexing agent and crude trichlorosilane into a reactor to carry out a complexation reaction; adding the resulting reaction mixture into a distillation apparatus for distillation to separate the high-boiling-point complex and obtain purified trichlorosilane.
[0028] The mass ratio of crude trichlorosilane to choline-based ionic liquid is (800-1250):1, such as 800:1, 830:1, 850:1, 950:1, 957:1, 985:1, 1000:1, 1025:1, 1050:1 or 1250:1.
[0029] Choline-based ionic liquids are non-p-toluenesulfonic acid choline ionic liquids;
[0030] The temperature of the complexation reaction is not lower than 20℃.
[0031] In a preferred embodiment of the present invention, the choline-based ionic liquid is selected from acetic choline ionic liquid, lactic choline ionic liquid, methanesulfonate choline ionic liquid, triazole choline ionic liquid or 2-hydroxypyridinized choline ionic liquid.
[0032] In a preferred embodiment of the present invention, the triazole choline ionic liquid is a 1,2,4-triazole choline ionic liquid.
[0033] The choline cation structure of the non-p-toluenesulfonic acid choline ionic liquid used in this invention is as follows: Anions include CH3COO - CH3CH(OH)COO - CH3SO3 - C2H2N3 - C5H4NO - The structural formula is as follows: , , , , .
[0034] In a preferred embodiment of the present invention, the method for preparing choline-based ionic liquids is as follows: choline hydroxide is mixed with a corresponding acid to cause an acid-base neutralization reaction in the system, followed by rotary evaporation to remove water and washing and drying to obtain choline-based ionic liquids; or, choline chloride is mixed with a corresponding anionic compound in a solvent to cause an anion displacement reaction in the system, removing the precipitated byproducts and removing the solvent, followed by drying to obtain choline-based ionic liquids.
[0035] In a preferred embodiment of the present invention, when preparing choline-based ionic liquids, before mixing choline chloride with the corresponding anionic compound in a solvent, 1,2,4-triazole is first mixed with sodium hydroxide to convert 1,2,4-triazole into an ionic compound. Subsequently, this ionic compound undergoes ion exchange with choline chloride to generate the corresponding choline-based ionic liquid.
[0036] In a preferred embodiment of the present invention, the corresponding acid is selected from acetic acid, methanesulfonic acid or lactic acid; the corresponding anionic compound is selected from 2-hydroxypyridine or 1,2,4-triazole.
[0037] In a preferred embodiment of the present invention, the temperature of the complexation reaction is 25-75°C, the time is 1 hour, and the pressure is 0.1 MPa; preferably, the temperature of the complexation reaction is 25-40°C, such as 25°C, 30°C, or 40°C.
[0038] In a preferred embodiment of the present invention, the distillation temperature is 50-90°C and the pressure is 0.1 MPa; preferably, the distillation temperature is 50-70°C, such as 50°C, 55°C, 60°C or 70°C.
[0039] Although existing literature (Exploration of lithium brine purification via simultaneous extraction of magnesium and boron using novel ionic liquids: Atheoretical and experimental molecular study and Metal separation and recovery employing choline chloride-based deep eutectic solvents: Diverse functions of water) reports the efficient extraction of boric acid and metal ions in aqueous solutions using ionic liquids or deep eutectic solvents, the application scenarios and chlorosilane purification systems in these studies differ fundamentally from those of this invention. In existing literature, boron is mainly extracted using B(OH)3 / B(OH)4. -The boron in the crude chlorosilane exists in a hydrated form, and its boron extraction mechanism relies on the formation of a four-coordinate chelate structure between polyhydroxy ligands and boric acid. The complexation behavior is regulated by the hydration shell, hydrogen bond network, and pH conditions. However, the chlorosilane system treated in this invention is a strictly anhydrous, weakly polar medium, where boron exists as molecular BCl3, lacking a basis for aqueous chelation. The traditional "vicinal diol-boric acid" complexation pathway is completely ineffective. This invention is based on Lewis acid-base interactions, utilizing the strong complexing ability, green adjustability, high stability, and low volatility of non-toluenesulfonic acid choline ionic liquids to selectively complex boron and phosphorus impurities in the crude chlorosilane product, generating high-boiling-point complexes. Subsequently, through distillation separation, the difference in boiling points between the complexes and the target chlorosilane product is used to effectively remove impurities, thereby obtaining high-purity chlorosilanes (i.e., trichlorosilane). The method of this invention is simple to operate, can effectively reduce the energy consumption of subsequent distillation processes, and improve the efficiency of impurity removal, providing an economical and environmentally friendly solution for the preparation of high-purity polycrystalline silicon.
[0040] Unless otherwise specified, the room temperature in this invention is 25±2℃.
[0041] All raw materials used in the embodiments of this invention were purchased commercially. As an example, p-toluenesulfonic acid choline ionic liquid was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.
[0042] It should be noted that any aspects not described in detail in this invention are conventional practices in the field and are not the focus of this invention.
[0043] The technical solution of the present invention will be further illustrated by the following embodiments.
[0044] Example 1
[0045] A method for removing trace boron and phosphorus impurities from trichlorosilane using choline-based ionic liquids comprises the following steps:
[0046] Preparation of S1, 1,2,4-triazole choline ionic liquid: 1,2,4-triazole and sodium hydroxide were thoroughly mixed in methanol, and then choline chloride in an equimolar ratio with 1,2,4-triazole was added to carry out anion displacement reaction. After filtering to remove insoluble matter, the solvent was removed by rotary evaporation, and the liquid was dried to obtain 1,2,4-triazole choline ionic liquid.
[0047] S2. Weigh 0.1g of 1,2,4-triazolylcholine ionic liquid as a complexing agent, add 100g of crude trichlorosilane product (boron content of 83.67ppb and phosphorus content of 79.45ppb) and the complexing agent into the reactor, and react at 0.1MPa pressure and 30℃ for 1h to obtain the reaction mixture.
[0048] S3. Place the obtained reaction mixture in a distillation apparatus and heat it to 60°C at 0.1 MPa. The complex formed by the ionic liquid and boron and phosphorus impurities is a high-boiling-point complex, which cannot be distilled off at this temperature, while trichlorosilane can be completely distilled off. The distilled product (fraction) is the purified trichlorosilane.
[0049] According to ICP-MS testing, the boron content in the trichlorosilane obtained in this embodiment is 0.32 ppb and the phosphorus content is 0.89 ppb. That is, the removal efficiency of boron impurities in the crude trichlorosilane product in this embodiment is 99.62% and the removal efficiency of phosphorus impurities is 98.88%.
[0050] Example 2
[0051] A method for removing trace boron and phosphorus impurities from trichlorosilane using choline-based ionic liquids comprises the following steps:
[0052] Preparation of S1, 2-hydroxypyridinized choline ionic liquid: 2-hydroxypyridine and sodium hydroxide were thoroughly mixed in methanol solvent at 60℃, and choline chloride in an equimolar ratio with 2-hydroxypyridine was added to carry out anion displacement reaction. After filtering to remove insoluble matter, the solvent was removed by rotary evaporation, and the liquid was dried to obtain 2-hydroxypyridinized choline ionic liquid.
[0053] S2. Weigh 0.1g of 2-hydroxypyridinized choline ionic liquid as a complexing agent, add 100g of crude trichlorosilane product (boron content of 83.67ppb and phosphorus content of 79.45ppb) and the complexing agent into the reactor, and react at 0.1MPa pressure and 30℃ for 1h to obtain the reaction mixture.
[0054] S3. Place the obtained reaction mixture in a distillation apparatus, heat it to 60°C at 0.1 MPa, and collect the distillate to obtain purified trichlorosilane.
[0055] According to ICP-MS testing, the trichlorosilane obtained in this embodiment has a boron content of 0.44 ppb and a phosphorus content of 0.95 ppb.
[0056] Example 3
[0057] A method for removing trace boron and phosphorus impurities from trichlorosilane using choline-based ionic liquids comprises the following steps:
[0058] S1. Preparation of choline acetate ionic liquid: Choline hydroxide and acetic acid in an equimolar ratio are thoroughly mixed in an ice-water bath, the mixture is removed by rotary evaporation, washed with ether, and dried to obtain choline acetate ionic liquid.
[0059] S2. Weigh 0.1g of choline acetate ionic liquid as a complexing agent, add 100g of crude trichlorosilane product (boron content of 83.67ppb and phosphorus content of 79.45ppb) and the complexing agent into the reactor, and react at 0.1MPa pressure and 30℃ for 1h to obtain the reaction mixture.
[0060] S3. Place the obtained reaction mixture in a distillation apparatus, heat it to 60°C at 0.1 MPa, and collect the distillate to obtain purified trichlorosilane.
[0061] According to ICP-MS testing, the trichlorosilane obtained in this embodiment has a boron content of 0.9 ppb and a phosphorus content of 1.24 ppb.
[0062] Example 4
[0063] A method for removing trace boron and phosphorus impurities from trichlorosilane using choline-based ionic liquids comprises the following steps:
[0064] S1. Preparation of lactic acid choline ionic liquid: Equimolar amounts of choline hydroxide and lactic acid were thoroughly mixed in an ice-water bath, and after rotary evaporation to remove water, the mixture was washed with tetrahydrofuran and dried to obtain lactic acid choline ionic liquid.
[0065] S2. Weigh 0.1g of lactic choline ionic liquid as a complexing agent, add 100g of crude trichlorosilane product (boron content of 83.67ppb and phosphorus content of 79.45ppb) and the complexing agent into the reactor, and react at 0.1MPa pressure and 30℃ for 1h to obtain the reaction mixture.
[0066] S3. Place the obtained reaction mixture in a distillation apparatus, heat it to 60°C at 0.1 MPa, and collect the distillate to obtain purified trichlorosilane.
[0067] According to ICP-MS testing, the trichlorosilane obtained in this embodiment has a boron content of 1.11 ppb and a phosphorus content of 1.27 ppb.
[0068] Example 5
[0069] A method for removing trace boron and phosphorus impurities from trichlorosilane using choline-based ionic liquids comprises the following steps:
[0070] S1. Preparation of methanesulfonic acid choline ionic liquid: Choline hydroxide and methanesulfonic acid in an equimolar ratio are thoroughly mixed in an ice-water bath, the mixture is removed by rotary evaporation, washed with ether, and dried to obtain methanesulfonic acid choline ionic liquid.
[0071] S2. Weigh 0.1g of methanesulfonic acid choline ionic liquid as a complexing agent, add 100g of crude trichlorosilane product (boron content of 83.67ppb and phosphorus content of 79.45ppb) and the complexing agent into the reactor, and react at 0.1MPa pressure and 30℃ for 1h to obtain the reaction mixture.
[0072] S3. Place the obtained reaction mixture in a distillation apparatus, heat it to 60°C at 0.1 MPa, and collect the distillate to obtain purified trichlorosilane.
[0073] According to ICP-MS testing, the trichlorosilane obtained in this embodiment has a boron content of 1.17 ppb and a phosphorus content of 1.65 ppb.
[0074] Example 6
[0075] A method for removing trace boron and phosphorus impurities from trichlorosilane using choline-based ionic liquids comprises the following steps:
[0076] The preparation method of S1, 1,2,4-triazole choline ionic liquid is the same as in Example 1;
[0077] S2. Weigh 0.08 g of 1,2,4-triazolylcholine ionic liquid as a complexing agent, add 100 g of crude trichlorosilane product (boron content of 83.67 ppb and phosphorus content of 79.45 ppb) and the complexing agent into the reactor, and react at 0.1 MPa pressure and 30 °C for 1 h to obtain the reaction mixture.
[0078] S3. Place the obtained reaction mixture in a distillation apparatus, heat it to 60°C at 0.1 MPa, and collect the distillate to obtain purified trichlorosilane.
[0079] According to ICP-MS testing, the trichlorosilane obtained in this embodiment has a boron content of 0.48 ppb and a phosphorus content of 1 ppb.
[0080] Example 7
[0081] A method for removing trace boron and phosphorus impurities from trichlorosilane using choline-based ionic liquids comprises the following steps:
[0082] The preparation method of S1, 1,2,4-triazole choline ionic liquid is the same as in Example 1;
[0083] S2. Weigh 0.125g of 1,2,4-triazole choline ionic liquid as a complexing agent, add 100g of crude trichlorosilane product (boron content of 83.67ppb and phosphorus content of 79.45ppb) and the complexing agent into the reactor, and react at 0.1MPa pressure and 30℃ for 1h to obtain the reaction mixture.
[0084] S3. Place the obtained reaction mixture in a distillation apparatus, heat it to 60°C at 0.1 MPa, and collect the distillate to obtain purified trichlorosilane.
[0085] According to ICP-MS testing, the trichlorosilane obtained in this embodiment has a boron content of 0.43 ppb and a phosphorus content of 0.97 ppb.
[0086] Example 8
[0087] A method for removing trace boron and phosphorus impurities from trichlorosilane using choline-based ionic liquids comprises the following steps:
[0088] The preparation method of S1, 1,2,4-triazole choline ionic liquid is the same as in Example 1;
[0089] S2. Weigh 0.1g of 1,2,4-triazolecholine ionic liquid as a complexing agent, add 100g of crude trichlorosilane product (boron content of 83.67ppb and phosphorus content of 79.45ppb) and the complexing agent into the reactor, and react at 0.1MPa pressure and 25℃ for 1h to obtain the reaction mixture.
[0090] S3. Place the obtained reaction mixture in a distillation apparatus, heat it to 60°C at 0.1 MPa, and collect the distillate to obtain purified trichlorosilane.
[0091] According to ICP-MS testing, the trichlorosilane obtained in this embodiment has a boron content of 0.55 ppb and a phosphorus content of 0.98 ppb.
[0092] Example 9
[0093] A method for removing trace boron and phosphorus impurities from trichlorosilane using choline-based ionic liquids comprises the following steps:
[0094] The preparation method of S1, 1,2,4-triazole choline ionic liquid is the same as in Example 1;
[0095] S2. Weigh 0.1g of 1,2,4-triazolylcholine ionic liquid as a complexing agent, add 100g of crude trichlorosilane product (boron content of 83.67ppb, phosphorus content of 79.45ppb) and the complexing agent into the reactor, and react at 0.1MPa pressure and 40℃ for 1h to obtain the reaction mixture.
[0096] S3. Place the obtained reaction mixture in a distillation apparatus and heat it to 60°C at 0.1 MPa to completely distill off the trichlorosilane. Collect the distillate to obtain purified trichlorosilane.
[0097] According to ICP-MS testing, the trichlorosilane obtained in this embodiment has a boron content of 0.46 ppb and a phosphorus content of 1.02 ppb.
[0098] Example 10
[0099] A method for removing trace boron and phosphorus impurities from trichlorosilane using choline-based ionic liquids comprises the following steps:
[0100] The preparation method of S1, 1,2,4-triazole choline ionic liquid is the same as in Example 1;
[0101] S2. Weigh 0.1g of 1,2,4-triazolylcholine ionic liquid as a complexing agent, add 100g of crude trichlorosilane product (boron content of 83.67ppb and phosphorus content of 79.45ppb) and the complexing agent into the reactor, and react at 0.1MPa pressure and 30℃ for 1h to obtain the reaction mixture.
[0102] S3. Place the obtained reaction mixture in a distillation apparatus, heat it to 50°C at 0.1 MPa, and collect the distillate to obtain purified trichlorosilane.
[0103] According to ICP-MS testing, the trichlorosilane obtained in this embodiment has a boron content of 0.67 ppb and a phosphorus content of 1.13 ppb.
[0104] Example 11
[0105] A method for removing trace boron and phosphorus impurities from trichlorosilane using choline-based ionic liquids comprises the following steps:
[0106] The preparation method of S1, 1,2,4-triazole choline ionic liquid is the same as in Example 1;
[0107] S2. Weigh 0.1g of 1,2,4-triazolylcholine ionic liquid as a complexing agent, add 100g of crude trichlorosilane product (boron content of 83.67ppb and phosphorus content of 79.45ppb) and the complexing agent into the reactor, and react at 0.1MPa pressure and 30℃ for 1h to obtain the reaction mixture.
[0108] S3. Place the obtained reaction mixture in a distillation apparatus, heat it to 70°C at 0.1 MPa, and collect the distillate to obtain purified trichlorosilane.
[0109] According to ICP-MS testing, the trichlorosilane obtained in this embodiment has a boron content of 0.39 ppb and a phosphorus content of 0.96 ppb.
[0110] Example 12
[0111] A method for removing trace boron and phosphorus impurities from trichlorosilane using choline-based ionic liquids comprises the following steps:
[0112] The preparation method of S1, 1,2,4-triazole choline ionic liquid is the same as in Example 1;
[0113] S2. Weigh 0.1g of 1,2,4-triazolylcholine ionic liquid as a complexing agent, add 100g of crude trichlorosilane product (boron content of 83.67ppb, phosphorus content of 79.45ppb) and the complexing agent into the reactor, and react at 0.1MPa pressure and 50℃ for 1h to obtain the reaction mixture.
[0114] S3. Place the obtained reaction mixture in a distillation apparatus, heat it to 60°C at 0.1 MPa, and collect the distillate to obtain purified trichlorosilane.
[0115] According to ICP-MS testing, the trichlorosilane obtained in this embodiment has a boron content of 0.47 ppb and a phosphorus content of 1.01 ppb.
[0116] Example 13
[0117] A method for removing trace boron and phosphorus impurities from trichlorosilane using choline-based ionic liquids comprises the following steps:
[0118] The preparation method of S1, 1,2,4-triazole choline ionic liquid is the same as in Example 1;
[0119] S2. Weigh 0.1g of 1,2,4-triazole choline ionic liquid as a complexing agent, add 100g of crude trichlorosilane product (boron content of 83.67ppb and phosphorus content of 79.45ppb) and the complexing agent into the reactor, and react at 0.1MPa pressure and 75℃ for 1h to obtain the reaction mixture.
[0120] S3. Place the obtained reaction mixture in a distillation apparatus, heat it to 60°C at 0.1 MPa, and collect the distillate to obtain purified trichlorosilane.
[0121] According to ICP-MS testing, the trichlorosilane obtained in this embodiment has a boron content of 0.48 ppb and a phosphorus content of 0.97 ppb.
[0122] Example 14
[0123] A method for removing trace boron and phosphorus impurities from trichlorosilane using choline-based ionic liquids comprises the following steps:
[0124] The preparation method of S1, 1,2,4-triazole choline ionic liquid is the same as in Example 1;
[0125] S2. Weigh 0.1g of 1,2,4-triazolylcholine ionic liquid as a complexing agent, add 100g of crude trichlorosilane product (boron content of 83.67ppb and phosphorus content of 79.45ppb) and the complexing agent into the reactor, and react at 0.1MPa pressure and 30℃ for 1h to obtain the reaction mixture.
[0126] S3. Place the obtained reaction mixture in a distillation apparatus, heat it to 90°C at 0.1 MPa, and collect the distillate to obtain purified trichlorosilane.
[0127] According to ICP-MS testing, the trichlorosilane obtained in this embodiment has a boron content of 0.41 ppb and a phosphorus content of 0.96 ppb.
[0128] Comparative Example 1
[0129] A method for removing trace boron and phosphorus impurities from trichlorosilane using choline chloride, comprising the following steps:
[0130] S1. Weigh 0.1g of choline chloride as a complexing agent, add 100g of crude trichlorosilane (boron content of 83.67ppb and phosphorus content of 79.45ppb) and the complexing agent into the reactor, and react at 0.1MPa pressure and 30℃ for 1h to obtain the reaction mixture.
[0131] S2. Place the obtained reaction mixture in a distillation apparatus, heat it to 60°C at 0.1 MPa, and collect the distillate to obtain purified trichlorosilane.
[0132] According to ICP-MS testing, the boron content in the trichlorosilane obtained in this comparative example was 2.34 ppb, and the phosphorus content was 2.56 ppb.
[0133] Comparative Example 2
[0134] A method for removing trace boron and phosphorus impurities from trichlorosilane using choline-based ionic liquids comprises the following steps:
[0135] S1. Weigh 0.1g of p-toluenesulfonic acid choline ionic liquid as a complexing agent, add 100g of crude trichlorosilane product (boron content of 83.67ppb and phosphorus content of 79.45ppb) and the complexing agent into the reactor, and react at 0.1MPa pressure and 30℃ for 1h to obtain the reaction mixture.
[0136] S2. Place the obtained reaction mixture in a distillation apparatus, heat it to 60°C at 0.1 MPa, and collect the distillate to obtain purified trichlorosilane.
[0137] According to ICP-MS testing, the boron content in the trichlorosilane obtained in this comparative example was 2.97 ppb, and the phosphorus content was 3.75 ppb.
[0138] The anion of p-toluenesulfonic acid choline has a strong electron-withdrawing effect, making it unable to form stable coordination complexes with impurities; moreover, the system lacks auxiliary forces such as hydrogen bonds and van der Waals forces, which further reduces the complexation efficiency.
[0139] Comparative Example 3
[0140] A method for removing trace boron and phosphorus impurities from trichlorosilane using choline-based ionic liquids comprises the following steps:
[0141] The preparation method of S1, 1,2,4-triazole choline ionic liquid is the same as in Example 1;
[0142] S2. Weigh 0.04 g of 1,2,4-triazole choline ionic liquid as a complexing agent, add 100 g of crude trichlorosilane product (boron content of 83.67 ppb and phosphorus content of 79.45 ppb) and the complexing agent into the reactor, and react at 0.1 MPa pressure and 30 °C for 1 h to obtain the reaction mixture.
[0143] S3. Place the obtained reaction mixture in a distillation apparatus, heat it to 60°C at 0.1 MPa, and collect the distillate to obtain purified trichlorosilane.
[0144] According to ICP-MS testing, the boron content in the trichlorosilane obtained in this comparative example was 3.59 ppb and the phosphorus content was 4.78 ppb.
[0145] Comparative Example 4
[0146] A method for removing trace boron and phosphorus impurities from trichlorosilane using choline-based ionic liquids comprises the following steps:
[0147] The preparation method of S1, 1,2,4-triazole choline ionic liquid is the same as in Example 1;
[0148] S2. Weigh 0.1g of 1,2,4-triazolecholine ionic liquid as a complexing agent, add 100g of crude trichlorosilane product (boron content of 83.67ppb and phosphorus content of 79.45ppb) and the complexing agent into the reactor, and react at 0.1MPa pressure and 10℃ for 1h to obtain the reaction mixture.
[0149] S3. Place the obtained reaction mixture in a distillation apparatus, heat it to 60°C at 0.1 MPa, and collect the distillate to obtain purified trichlorosilane.
[0150] According to ICP-MS testing, the boron content in the trichlorosilane obtained in this comparative example was 2.45 ppb, and the phosphorus content was 3.6 ppb.
[0151] Comparative Example 5
[0152] A method for removing trace boron and phosphorus impurities from trichlorosilane using choline-based ionic liquids comprises the following steps:
[0153] S1. Weigh 0.1g of trifluoromethanesulfonate choline as a complexing agent, add 100g of crude trichlorosilane (boron content 83.67ppb, phosphorus content 79.45ppb) and the complexing agent into the reactor, and react at 0.1MPa pressure and 30℃ for 1h to obtain the reaction mixture.
[0154] S2. Place the obtained reaction mixture in a distillation apparatus, heat it to 60°C at 0.1 MPa, and collect the distillate to obtain purified trichlorosilane.
[0155] ICP-MS testing showed that the boron content in the trichlorosilane obtained in this comparative example was 4.55 ppb, and the phosphorus content was 4.93 ppb. Comparison of Examples 1, 6, 7, and Comparative Example 1 revealed that a mass ratio of crude trichlorosilane to ionic liquid complexing agent of (800-1250):1 is beneficial for improving the purity of trichlorosilane.
[0156] By comparing Examples 1, 8, and 9 with Comparative Example 2, it can be seen that limiting the temperature of the complexation reaction within a preferred range is beneficial to further improving the purity of trichlorosilane.
[0157] By comparing Examples 1, 10 and 11, it can be seen that limiting the distillation temperature to a preferred range is beneficial to further improve the purity of trichlorosilane. If the temperature is too high, it will lead to excessive distillation energy consumption.
[0158] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.
Claims
1. A method for removing trace boron and phosphorus impurities from trichlorosilane using choline-based ionic liquids, characterized in that, Includes the following steps: Choline-based ionic liquids were added to crude trichlorosilane to carry out a complexation reaction. The resulting reaction mixture was then distilled to obtain purified trichlorosilane. The mass ratio of the crude trichlorosilane product to the choline-based ionic liquid is (800-1250):1; The choline-based ionic liquid is a non-p-toluenesulfonic acid choline ionic liquid; The temperature of the complexation reaction is not lower than 20°C.
2. The method for removing trace boron and phosphorus impurities from trichlorosilane using choline-based ionic liquids according to claim 1, characterized in that, The choline-based ionic liquid is selected from acetic choline ionic liquid, lactic choline ionic liquid, methanesulfonic acid choline ionic liquid, triazole choline ionic liquid, or 2-hydroxypyridinized choline ionic liquid.
3. The method for removing trace boron and phosphorus impurities from trichlorosilane using choline-based ionic liquids according to claim 2, characterized in that, The triazole choline ionic liquid is a 1,2,4-triazole choline ionic liquid.
4. The method for removing trace boron and phosphorus impurities from trichlorosilane using choline-based ionic liquids according to claim 2, characterized in that, The choline-based ionic liquid is prepared by the following steps: mixing choline hydroxide with a corresponding acid to carry out an acid-base neutralization reaction, removing water by rotary evaporation, washing and drying to obtain the choline-based ionic liquid; Alternatively, choline chloride is mixed with the corresponding anionic compound in a solvent to carry out anion displacement reaction, the precipitated byproducts are removed and the solvent is removed, and the mixture is dried to obtain the choline-based ionic liquid.
5. The method for removing trace boron and phosphorus impurities from trichlorosilane using choline-based ionic liquids according to claim 4, characterized in that, The corresponding acid is selected from acetic acid, methanesulfonic acid, or lactic acid; the corresponding anionic compound is selected from 2-hydroxypyridine or 1,2,4-triazole.
6. The method for removing trace boron and phosphorus impurities from trichlorosilane using choline-based ionic liquids according to claim 1, characterized in that, The complexation reaction was carried out at a temperature of 25-75℃ for 1 hour and a pressure of 0.1 MPa.
7. The method for removing trace boron and phosphorus impurities from trichlorosilane using choline-based ionic liquids according to claim 6, characterized in that, The temperature of the complexation reaction is 25-40℃.
8. The method for removing trace boron and phosphorus impurities from trichlorosilane using choline-based ionic liquids according to claim 1, characterized in that, The distillation temperature is 50-90℃ and the pressure is 0.1 MPa.
9. The method for removing trace boron and phosphorus impurities from trichlorosilane using choline-based ionic liquids according to claim 8, characterized in that, The distillation temperature is 50-70℃.