An adsorption system for removing impurities in chlorosilane systems

Abstract

The application is suitable for the technical field of chlorosilane purification, and provides an adsorption system for removing impurities in a chlorosilane system, which comprises a pretreatment unit and an adsorption purification unit; the pretreatment unit comprises a constant-temperature drying device and at least three TET gradient soaking devices connected in series, and is used for activating treatment of a silica-alumina gel adsorbent; the adsorption purification unit comprises at least one adsorption column; the adsorption column is filled with the silica-alumina gel adsorbent activated by the pretreatment unit, and is provided with a chlorosilane inlet, a purification outlet, a temperature control component and an outlet monitoring point; through optimization of a pretreatment process and an adsorption structure design, the adsorption system realizes efficient activation of the silica-alumina gel adsorbent, significantly improves an impurity removal rate, inhibits disproportionation reaction, prolongs adsorption life, and guarantees purity of a chlorosilane product.

Description

Technical Field

[0001] This invention relates to the field of chlorosilane purification technology, and more specifically, to an adsorption system for removing impurities from chlorosilane systems. Background Technology

[0002] Chlorosilanes (such as TCS and TET) are core raw materials in the photovoltaic and semiconductor industries, and their purity directly determines the electrical properties and product yield of downstream products such as polysilicon. In industrial production, chlorosilane raw materials are often accompanied by non-metallic impurities such as boron and phosphorus, as well as trace metallic impurities, which need to be removed through adsorption processes.

[0003] In existing adsorption technologies, commonly used adsorbents include activated carbon and resins, but they have significant drawbacks: activated carbon is prone to violent reactions when in contact with chlorosilanes, releasing harmful gases and lacking safety, while also easily leading to TCS disproportionation reactions with conversion rates exceeding 5%, resulting in raw material loss; resin adsorbents experience structural collapse at 120℃, exhibiting poor thermal stability, and have limited removal efficiency for boron and phosphorus impurities; although silica-alumina gel possesses good thermal stability, its direct use releases metallic impurities such as aluminum and copper, contaminating chlorosilane raw materials and limiting its industrial application.

[0004] Therefore, developing a safe, efficient, thermally stable, high impurity removal rate, and long service life adsorption system has become a technical challenge that the industry urgently needs to solve. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide an adsorption system for removing impurities from chlorosilane systems. By optimizing the pretreatment process and adsorption structure design, the system achieves efficient activation of the silica-alumina gel adsorbent, significantly improves the impurity removal rate, inhibits disproportionation reactions, extends adsorption life, and ensures the purity of chlorosilane products.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] An adsorption system for removing impurities from a chlorosilane system includes a pretreatment unit and an adsorption purification unit. The pretreatment unit includes a constant temperature drying device and at least three TET gradient immersion devices connected in series for activating a silica-alumina gel adsorbent. The adsorption purification unit includes at least one adsorption column. The adsorption column is filled with silica-alumina gel adsorbent activated by the pretreatment unit and is equipped with a chlorosilane inlet, a purification outlet, a temperature control component, and an outlet monitoring point.

[0008] The present invention is further configured such that: the TET gradient immersion device includes at least three immersion tanks connected in series; each immersion tank contains TET leachate; a TET replacement mechanism is provided between adjacent immersion tanks; the TET replacement mechanism includes a supply pipeline, a drain pipeline and a control valve connected to each immersion tank, for automatically replacing fresh TET leachate before the silica-alumina gel is transferred to the next immersion tank.

[0009] The present invention is further configured such that: the constant temperature drying device controls the drying temperature to 100-120℃ and the drying time to 2-4 hours, so that the weight loss rate of the silica-alumina gel is ≤10%; in the TET gradient soaking device, the volume ratio of silica-alumina gel to TET is 2:5, the amount of TET in the subsequent soaking tank is 1.2-1.5 times that of the previous stage, and the soaking time for each stage is 12-24 hours.

[0010] The present invention is further configured such that the temperature control component includes a temperature sensor and a heating / cooling device, for controlling the operating temperature inside the adsorption column to ≤90℃.

[0011] The present invention is further configured such that: the outlet monitoring point includes an online analyzer for real-time monitoring of the content of boron and phosphorus impurities and the amount of metal release in the purified chlorosilane, wherein the monitoring indicators meet the requirements of boron removal rate ≥90%, phosphorus removal rate ≥60%, and metal release <0.1ppm.

[0012] The present invention is further configured such that: the volume ratio of silica-alumina gel adsorbent to chlorosilane in the adsorption column is 1:(500-4000); the adsorption purification unit further includes an adsorbent replacement indicator connected to the signal of the outlet monitoring point; the adsorbent replacement indicator is configured to issue a replacement reminder after the adsorption column has accumulated 4000-8000 hours of operation.

[0013] The advantages of this invention are:

[0014] This invention utilizes a pretreatment process of "constant temperature drying + three-stage TET gradient immersion" to achieve deep removal of metal impurities from silica-alumina gel adsorbents, with an aluminum removal rate of ≥98%, solving the problem of metal release pollution when silica-alumina gels are used directly. During adsorption, the temperature is precisely controlled to ≤90℃, effectively inhibiting the disproportionation reaction of chlorosilanes, achieving a conversion rate of ≤0.18% and significantly reducing raw material loss. The adsorbent has a lifespan of 4000-8000 hours, four times longer than traditional activated carbon adsorbents, and exhibits high removal rates of boron and phosphorus impurities. Metal release meets stringent industry standards, balancing safety, efficiency, and economy, making it suitable for large-scale industrial production. Attached Figure Description

[0015] Figure 1 This is a flowchart of an adsorption system for removing impurities from a chlorosilane system according to the present invention. Detailed Implementation

[0016] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0017] It should be noted that, unless otherwise specified, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0018] In this invention, unless otherwise stated, the directional terms such as "up" and "down" generally refer to the directions shown in the accompanying drawings, or to the vertical, perpendicular, or gravitational direction; similarly, for ease of understanding and description, "left" and "right" generally refer to the left and right shown in the accompanying drawings; "inner" and "outer" refer to the inner and outer contours of each component itself, but the above directional terms are not intended to limit this invention.

[0019] Example 1, please refer to Figure 1 The present invention provides the following technical solutions:

[0020] An adsorption system for removing impurities from a chlorosilane system, specifically comprising a pretreatment unit and an adsorption purification unit; the pretreatment unit includes a constant temperature drying device and at least three TET gradient immersion devices connected in series for activating the silica-alumina gel adsorbent; the adsorption purification unit includes at least one adsorption column; the adsorption column is filled with silica-alumina gel adsorbent activated by the pretreatment unit and is equipped with a chlorosilane inlet, a purification outlet, a temperature control component, and an outlet monitoring point.

[0021] Constant temperature drying device: An electric heating constant temperature drying oven is used, with the drying temperature set at 110℃ and the drying time at 3 hours to ensure that the weight loss rate of the silica-alumina gel is controlled at ≤8%. By removing the moisture and volatile impurities adsorbed on the surface of the adsorbent, conditions are created for the subsequent TET immersion to remove metal impurities.

[0022] TET gradient immersion device: It adopts three-stage series of corrosion-resistant immersion tanks (material is polytetrafluoroethylene), each immersion tank has an effective volume of 100L, and the transfer of silica-alumina gel between adjacent immersion tanks is controlled by pneumatic valves. The TET leaching solution uses high-purity silicon tetrachloride with a purity of ≥99.99%.

[0023] Adsorption column: Made of stainless steel, the column is 2000mm long and 300mm in diameter. The chlorosilane inlet is located at the bottom of the adsorption column and the purification outlet is located at the top, forming a countercurrent adsorption mode to improve adsorption efficiency. The temperature control component adopts an embedded temperature sensor combined with an electric heating jacket to monitor and regulate the temperature inside the column in real time.

[0024] Export monitoring point: Equipped with dedicated online chromatographic analyzers for boron and phosphorus, and online ICP-MS monitoring instruments for metal elements, to collect and test purified chlorosilane samples in real time.

[0025] Working principle of this embodiment:

[0026] First, the pretreatment unit is started, and the silica-alumina gel to be activated is sent to a constant temperature drying device and dried at 110°C for 3 hours to remove moisture and volatile impurities. The dried silica-alumina gel is then sequentially introduced into a three-stage series TET gradient immersion device. Through gradient elution with TET leachate, soluble aluminum and other metallic impurities in the silica-alumina gel are gradually removed. The activated silica-alumina gel is then packed into an adsorption column. Chlorosilane raw material containing boron and phosphorus impurities is introduced into the adsorption column through the chlorosilane inlet. Under the appropriate temperature controlled by the temperature control component, the chlorosilane and silica-alumina gel adsorbent are in full contact, and the boron, phosphorus impurities and residual metallic impurities are retained by the adsorbent. The purified chlorosilane is discharged through the purification outlet, and the impurity content and metal release are monitored in real time at the outlet monitoring point to ensure that the product meets the standards.

[0027] In summary, the synergistic effect of the pretreatment unit and the adsorption purification unit achieves efficient removal of impurities in the chlorosilane system, while avoiding the safety hazards of traditional adsorbents and improving the stability of the adsorption process.

[0028] Example 2, please refer to Figure 1 This embodiment two is an improvement on the first embodiment as follows: Specifically, each soaking tank is filled with TET leachate; a TET replacement mechanism is provided between adjacent soaking tanks; the TET replacement mechanism includes a supply pipeline, a drain pipeline and a control valve connected to each soaking tank, which is used to automatically replace fresh TET leachate before the silica-alumina gel is transferred to the next soaking tank.

[0029] The constant temperature drying device controls the drying temperature at 100-120℃ and the drying time at 2-4 hours to ensure that the weight loss rate of the silica-alumina gel is ≤10%. In the TET gradient immersion device, the volume ratio of silica-alumina gel to TET is 2:5, the amount of TET in the subsequent immersion tank is 1.2-1.5 times that of the previous stage, and the immersion time for each stage is 12-24 hours.

[0030] The temperature control components include a temperature sensor and a heating / cooling device, used to control the operating temperature inside the adsorption column to ≤90℃.

[0031] The export monitoring point includes an online analyzer used to monitor the content of boron and phosphorus impurities and the release of metals in the purified chlorosilane in real time. The monitoring indicators meet the requirements of boron removal rate ≥90%, phosphorus removal rate ≥60%, and metal release <0.1ppm.

[0032] The volume ratio of silica-alumina gel adsorbent to chlorosilane in the adsorption column is 1:(500-4000); the adsorption purification unit also includes an adsorbent replacement indicator connected to the outlet monitoring point signal; the adsorbent replacement indicator is configured to issue a replacement reminder after the adsorption column has accumulated 4000-8000 hours of operation.

[0033] The working principle of this embodiment two is as follows:

[0034] The constant temperature drying device controls the drying temperature at 120℃ and the drying time at 4 hours to ensure that the weight loss rate of the silica-alumina gel is ≤6.9%. In the TET gradient immersion device, the volume ratio of silica-alumina gel to TET is 2:5. The TET volume in the first immersion tank is 500L, the TET volume in the second immersion tank is 600L (1.2 times that of the previous stage), and the TET volume in the third immersion tank is 750L (1.25 times that of the previous stage). The immersion time for each stage is 24 hours.

[0035] The temperature control component includes a temperature sensor and a heating / cooling device, which is used to control the operating temperature inside the adsorption column to ≤90℃. In this embodiment, the control temperature is set to 85℃.

[0036] The volume ratio of silica-alumina gel adsorbent to chlorosilane in the adsorption column is 1:2000; the adsorption purification unit also includes an adsorbent replacement indicator connected to the outlet monitoring point signal; the adsorbent replacement indicator is configured to issue a replacement reminder after the adsorption column has accumulated 4000-8000 hours of operation, and in this embodiment, the trigger threshold is set to 6000 hours.

[0037] This second embodiment also adds a filtration unit, which is set between the TET gradient immersion device and the adsorption column. It uses polytetrafluoroethylene filter paper with a pore size of 0.22μm to trap metal impurity particles that precipitate during the immersion process, further reducing the risk of metal release from the silica-alumina gel adsorbent.

[0038] In the pretreatment stage, a constant temperature drying device was activated to dry 400L of silica-alumina gel at 120℃ for 4 hours, reducing the weight loss to 6.5% to ensure unobstructed internal pore structure of the adsorbent. Subsequently, the silica-alumina gel was transferred to the first-stage soaking tank and mixed with 500L of high-purity TET at a volume ratio of 2:5. After soaking for 24 hours, 78.7% of aluminum impurities were removed. After soaking, the waste TET in the first soaking tank was discharged through the drain pipe. The control valve automatically closed the drain pipe and opened the supply pipe, injecting 600L of fresh TET into the second soaking tank. The silica-alumina gel was then transferred to the second soaking tank and soaked for another 24 hours, increasing the aluminum impurity removal rate to 90.3%. Similarly, 750L of fresh TET was injected into the third soaking tank, and after soaking the silica-alumina gel for 24 hours, the aluminum impurity removal rate reached 98.2%. After soaking, the silica-alumina gel was filtered to remove metal impurity particles and then packed into the adsorption column. At this point, the metal release from the silica-alumina gel decreased to 0.0104mg / L (<0.1ppm).

[0039] During the adsorption stage, TCS raw material with a boron impurity concentration of 0.7835 mg / L and a phosphorus impurity concentration of 0.35 mg / L is introduced into the adsorption column through the chlorosilane inlet. The flow rate is controlled to ensure that the residence time of TCS in the adsorption column is ≥24 hours, and the temperature inside the adsorption column is stabilized at 85℃ by the temperature control component. TCS and silica-alumina gel adsorbent are in full contact, boron impurities are efficiently adsorbed, and phosphorus impurities are gradually retained. The disproportionation reaction conversion rate is controlled at ≤0.18%. The outlet monitoring point monitors in real time. When the boron removal rate is ≥92%, the phosphorus removal rate is ≥65%, and the metal release is ≤0.08 ppm, the product is judged to meet the standards and is output through the purified outlet. If the monitoring indicators do not meet the standards, the system automatically triggers the feedback adjustment mechanism to check whether the adsorption column temperature deviates from the set value and whether the adsorbent has reduced adsorption capacity due to insufficient soaking. After adjustment, the adsorption operation is repeated.

[0040] When the adsorption column has accumulated 6000 hours of operation, the adsorbent replacement indicator will emit an audible and visual warning to remind staff to replace the adsorbent. The replaced adsorbent can be recycled after regeneration treatment, further reducing production costs.

[0041] This embodiment achieves a dual improvement in impurity removal rate and adsorption life by precisely controlling pretreatment parameters, optimizing the TET replacement mechanism and adsorption process conditions. Compared with traditional activated carbon adsorbents, TCS loss is reduced by 4% and adsorption life is increased by 3 times, significantly enhancing the economy and practicality of industrial applications.

[0042] Obviously, the embodiments described above are merely some, not all, embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.

[0043] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0044] It should be noted that the terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in sequences other than those illustrated or described herein.

[0045] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0046] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. An adsorption system for removing impurities from a chlorosilane system, characterized in that: It includes a pretreatment unit and an adsorption purification unit; the pretreatment unit includes a constant temperature drying device and at least three TET gradient immersion devices connected in series for activating the silica-alumina gel adsorbent; the adsorption purification unit includes at least one adsorption column; the adsorption column is filled with silica-alumina gel adsorbent activated by the pretreatment unit, and is equipped with a chlorosilane inlet, a purification outlet, a temperature control component, and an outlet monitoring point.

2. The adsorption system for removing impurities from a chlorosilane system according to claim 1, characterized in that: The TET gradient immersion device includes at least three immersion tanks connected in series; each immersion tank contains TET leachate; a TET replacement mechanism is provided between adjacent immersion tanks; the TET replacement mechanism includes a supply pipeline, a drainage pipeline and a control valve connected to each immersion tank, for automatically replacing fresh TET leachate before the silica-alumina gel is transferred to the next immersion tank.

3. The adsorption system for removing impurities from a chlorosilane system according to claim 2, characterized in that: The constant temperature drying device controls the drying temperature to 100-120℃ and the drying time to 2-4 hours, so that the weight loss rate of the silica-alumina gel is ≤10%; in the TET gradient immersion device, the volume ratio of silica-alumina gel to TET is 2:5, the amount of TET in the subsequent immersion tank is 1.2-1.5 times that of the previous stage, and the immersion time for each stage is 12-24 hours.

4. An adsorption system for removing impurities from a chlorosilane system according to claim 3, characterized in that: The temperature control component includes a temperature sensor and a heating / cooling device, used to control the operating temperature inside the adsorption column to ≤90℃.

5. An adsorption system for removing impurities from a chlorosilane system according to claim 4, characterized in that: The outlet monitoring point includes an online analyzer used to monitor the content of boron and phosphorus impurities and the amount of metal released in the purified chlorosilane in real time. The monitoring indicators meet the requirements of boron removal rate ≥90%, phosphorus removal rate ≥60%, and metal release <0.1ppm.

6. An adsorption system for removing impurities from a chlorosilane system according to claim 5, characterized in that: The volume ratio of silica-alumina gel adsorbent to chlorosilane in the adsorption column is 1:(500-4000); the adsorption purification unit also includes an adsorbent replacement indicator connected to the outlet monitoring point signal; the adsorbent replacement indicator is configured to issue a replacement reminder after the adsorption column has accumulated 4000-8000 hours of operation.

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