Purifying device for high-purity trimethylaluminum

Abstract

The utility model discloses a purification device for high-purity trimethylaluminum. The purification device comprises a raw material tank, a precooler, a primary adsorption tower, a secondary adsorption tower, a condenser and a finished product collecting tank which are connected in sequence, a bottom outlet of the raw material tank is connected with a precooler, an outlet of the precooler is divided into a main path and a bypass, the main path is connected with the primary adsorption tower through an electromagnetic valve, and the bypass is connected with an emergency discharge outlet; a sintered metal distributor and a composite filler layer are arranged in the first-stage adsorption tower, and the top is connected with the second-stage adsorption tower; the secondary adsorption tower is internally provided with a sodium-potassium alloy bed layer and is provided with an electric heating sleeve, and an outlet is connected with the condenser; the bottom of the condenser is connected with the collecting tank through a capillary tube; and the vacuum system is connected with the adsorption tower and the condenser through three-way valve branches. According to the utility model, through the collaborative design of multi-stage purification, the purity of trimethyl aluminum reaches more than 99.9995%, the safety and the efficiency are remarkably improved through the dual-sealing pipeline and the quick response electromagnetic valve less than 50ms, and the device is suitable for semiconductor-grade production.

Description

Technical Field

[0001] The utility model relates to the technical field of gas separation and purification, in particular to a purification device for high-purity trimethylaluminum. Background Art

[0002] As a key organometallic precursor, trimethylaluminum (TMA) plays an irreplaceable role in advanced fabrication processes such as MOCVD and atomic layer deposition (ALD). With the development of emerging technologies like third-generation semiconductors and MicroLEDs, the industry's demand for electronic-grade TMA has shown the following characteristics: purity requirements have increased from the traditional 99.9% to above 99.9995%; metal impurity content (especially Fe, Ni, and Cu) must be controlled to the ppb level; tolerance for oxygen- and sulfur-containing compounds has been reduced to the ppm level; and batch stability must fluctuate within a range of less than ±0.5%.

[0003] The traditional distillation process in existing purification technologies has thermodynamic limitations: the boiling point of TMA (126°C) is close to that of the main impurities (such as Me2AlH, bp. 120°C), and the conventional distillation separation factor is only 1.2~1.5; TMA is prone to self-polymerization in high-temperature environments, resulting in a yield loss of 5~8%; the internal components of the distillation tower (such as tower plates and packing) are easily corroded by aluminides; local overheating of the reboiler leads to coking, and the average operating cycle is less than 200 hours. The dilemma of adsorbent selection for adsorption purification technology: 3A molecular sieve has a low adsorption capacity for CH4 (<0.5mmol / g); activated carbon cannot selectively adsorb sulfides (such as Me2S); conventional adsorbents have a rapid lifespan decay in TMA environments (50% deactivation within 3 months); fixed-bed adsorption towers have channeling and wall effects; incomplete purge during regeneration leads to accumulation of residual impurities. In terms of equipment integration: material transfer problems, large dead volume of the piping system (>50mL), leading to product cross-contamination; the leakage rate at flange connections is as high as 10 -6 Pa·m 3 / s; inadequate thermal management, with a pre-cooling to reheating energy consumption ratio as high as 3:1; system heat loss causes temperature fluctuations of ±5°C. Process control: low automation, with sampling intervals for key parameters (pressure, temperature) >10s; emergency shutdown response time >200ms; oxygen content monitoring lag (alarm response >30s); and lack of a rapid pressure release mechanism. Existing solutions: Complex purification processes, with distillation-adsorption combined technology and equipment complexity; multiple series connections, resulting in yields below 85%; the application of new materials, with ionic liquid extraction investment costs being prohibitive; molecularly imprinted adsorbents not yet industrialized; system optimization: modular design lacks standardized interfaces; and intelligent control algorithms have poor adaptability.

[0004] To address these issues, the present invention provides a high-purity trimethylaluminum purification device that achieves the coordinated removal of multiple impurities and precise control of process parameters, ensuring a stable product purity exceeding 99.9995%. Through its integrated structural design and intelligent control system, this device effectively addresses key technical challenges inherent in traditional processes, including low efficiency, poor safety, and insufficient product consistency. Utility Model Content

[0005] The utility model aims to provide a high-purity trimethylaluminum purification device to achieve the coordinated removal of multi-level impurities and precise control of process parameters, thereby ensuring that the product purity stably reaches above 99.9995%.

[0006] In order to achieve the above purpose, the technical solution adopted by the utility model is:

[0007] A high-purity trimethylaluminum purification device comprises: a raw material tank with a cooling jacket, the bottom outlet of which is connected to the lower inlet of a precooler via a first pipeline, wherein a first solenoid valve is provided on the first pipeline;

[0008] The precooler has an upper outlet divided into two paths through a second pipeline, wherein the main path is connected to the bottom inlet of the first-stage adsorption tower through a second solenoid valve, and the bypass path is connected to the emergency discharge port through a third solenoid valve, and the emergency discharge port is connected to the inert gas purge system;

[0009] A primary adsorption tower, the top outlet of which is connected to the bottom inlet of a secondary adsorption tower via a fourth pipeline. The primary adsorption tower is filled with a composite filler layer of 3A molecular sieve and activated carbon, and a sintered metal distributor is provided at the bottom;

[0010] A secondary adsorption tower, the top outlet of which is connected to the upper air inlet of the condenser through a fifth pipeline, the secondary adsorption tower having a built-in sodium-potassium alloy dispersion bed and an external electric heating jacket;

[0011] A condenser, the bottom outlet of which is connected to the upper liquid inlet of the finished product collection tank through a sixth pipe, wherein the sixth pipe is a capillary tube with an inner diameter of 0.5 mm;

[0012] The vacuum system includes a molecular pump connected to a three-way valve through a seventh pipeline, a first branch of the three-way valve is connected to the top exhaust port of the first-level adsorption tower through an eighth pipeline, and a second branch is connected to the exhaust port of the condenser through a ninth pipeline.

[0013] Furthermore, an inert gas inlet is provided on the top of the raw material tank to maintain a slight positive pressure of 0.1~0.3 bar in the tank.

[0014] Furthermore, a 5 μm sintered metal filter is provided in front of the bottom outlet of the raw material tank.

[0015] Furthermore, the precooler is a spiral coil structure, the inner wall of which is coated with magnesium fluoride, and a -30°C refrigerant is passed through the outside.

[0016] Furthermore, the ratio of the composite filler layer height to the tower diameter of the first-stage adsorption tower is 5:1.

[0017] Furthermore, the sodium-potassium alloy bed of the secondary adsorption tower is distributed in a wave shape, and the temperature control range of the electric heating jacket is 45~55°C.

[0018] Furthermore, the condenser is a double-helix structure with a -78°C dry ice / acetone refrigerant inlet on the top; the finished product collection tank is equipped with a weighing sensor with a measurement accuracy of ±0.1g.

[0019] Furthermore, the first to ninth pipelines are all made of 316L stainless steel, the inner walls are electrolytically polished to a surface roughness of Ra≤0.2μm, and the pipelines are connected by double O-ring sealing flanges.

[0020] Furthermore, the response time from the first solenoid valve to the third solenoid valve is less than 50ms, and is linked to a PLC controller.

[0021] Furthermore, the vacuum system also includes a first vacuum gauge provided on the eighth pipeline and a second vacuum gauge provided on the ninth pipeline, which are used to monitor the vacuum degree of the first-stage adsorption tower and the condenser respectively.

[0022] Due to the application of the above technical solution, the utility model has the following advantages compared with the prior art:

[0023] 1. This utility model achieves a breakthrough in purity. It uses a "pre-cooling-two-stage adsorption-low-temperature condensation" collaborative purification system to increase the purity of trimethylaluminum from the industry standard of 99.9% to over 99.9995%. The specially designed sodium-potassium alloy bed can specifically remove sulfur-containing impurities (removal rate > 99.8%).

[0024] 2. The process efficiency of this utility model is significantly improved. The integrated modular design reduces the equipment volume by 40% and energy consumption by 35%. The fully automatic control system realizes unattended operation and improves production efficiency by 50%.

[0025] 3. The safety performance of this utility model has been comprehensively upgraded. The emergency interlock system with a quick response of less than 50ms has increased the accident prevention rate by 90%. The double-sealed pipeline design has reduced the leakage rate to less than 10. -9 Pa·m 3 / s;

[0026] 4. The operating cost of this utility model is greatly reduced. The new sintered metal distributor extends the service life of the filler by 3 times; the intelligent regeneration system reduces the inert gas consumption by 60%. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a process flow chart of Example 1 of the present utility model;

[0028] Figure 2 This is a cross-sectional view of the first-stage adsorption tower of Example 1 of the present utility model;

[0029] Among them, 1-raw material tank; 2-precooler; 3-first-stage adsorption tower; 3a-composite filler layer; 3b-sintered metal distributor; 4-second-stage adsorption tower; 5-condenser; 6-finished product collection tank; 7-molecular pump; 8-sintered metal filter; 9-first solenoid valve; 10-second solenoid valve; 11-third solenoid valve; 12-three-way valve; 13-first vacuum gauge; 14-second vacuum gauge. DETAILED DESCRIPTION

[0030] In order to more clearly understand the above-mentioned purposes, features and advantages of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods. These drawings are all simplified schematic diagrams, which only illustrate the basic structure of the present invention in a schematic manner. Therefore, they only show the structures related to the present invention. It should be noted that, unless there is a conflict, the embodiments in this application and the features in the embodiments can be combined with each other.

[0031] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Therefore, the scope of protection of the present invention is not limited to the specific embodiments disclosed below.

[0032] Example 1

[0033] As attached Figure 1 and attached Figure 2 As shown, this embodiment provides a purification device for high-purity trimethylaluminum, comprising: a raw material tank 1 with a cooling jacket, the bottom outlet of which is connected to the lower inlet of a precooler 2 via a first pipeline, and a first solenoid valve 9 is provided on the first pipeline;

[0034] The upper outlet of the precooler 2 is divided into two paths through a second pipeline, wherein the main path is connected to the bottom inlet of the first-stage adsorption tower 3 through a second solenoid valve 10, and the bypass path is connected to the emergency discharge port through a third solenoid valve 11, and the emergency discharge port is connected to the inert gas purge system;

[0035] The top outlet of the primary adsorption tower 3 is connected to the bottom inlet of the secondary adsorption tower 4 through a fourth pipeline. The primary adsorption tower 3 is filled with a composite filler layer 3a of 3A molecular sieve and activated carbon, and a sintered metal distributor 3b is provided at the bottom;

[0036] A secondary adsorption tower 4, the top outlet of which is connected to the upper air inlet of the condenser 5 through a fifth pipeline, the secondary adsorption tower 4 having a built-in sodium-potassium alloy dispersion bed and an external electric heating jacket;

[0037] The bottom outlet of the condenser 5 is connected to the upper liquid inlet of the finished product collection tank 6 through a sixth pipe, and the sixth pipe is a capillary tube with an inner diameter of 0.5 mm;

[0038] The vacuum system includes a molecular pump 7 connected to a three-way valve 12 through a seventh pipeline, a first branch of the three-way valve 12 is connected to the top exhaust port of the first-level adsorption tower 3 through an eighth pipeline, and a second branch is connected to the exhaust port of the condenser 5 through a ninth pipeline.

[0039] Furthermore, an inert gas inlet is provided on the top of the raw material tank 1 for maintaining a slight positive pressure of 0.2 bar in the tank, and nitrogen is selected as the inert gas.

[0040] Furthermore, a 5 μm sintered metal filter 8 is provided in front of the bottom outlet of the raw material tank 1 .

[0041] Furthermore, the precooler 2 is a spiral coil structure, the inner wall of which is coated with magnesium fluoride, and a -30°C refrigerant is passed through the outside.

[0042] Furthermore, the ratio of the height of the composite filler layer 3a of the first-stage adsorption tower 3 to the tower diameter is 5:1.

[0043] Furthermore, the sodium-potassium alloy bed of the secondary adsorption tower 4 is distributed in a wave shape, and the temperature of the electric heating jacket is controlled at 50°C.

[0044] Furthermore, the condenser 5 is a double helix structure, and a -78°C dry ice / acetone refrigerant inlet is provided on the top; the finished product collection tank 6 is equipped with a weighing sensor with a measurement accuracy of ±0.1g.

[0045] Furthermore, the first to ninth pipelines are all made of 316L stainless steel, the inner walls are electrolytically polished to a surface roughness of Ra≤0.2μm, and the pipelines are connected by double O-ring sealing flanges.

[0046] Furthermore, the response time from the first solenoid valve to the third solenoid valve is less than 50ms, and is linked to a PLC controller.

[0047] Furthermore, the vacuum system also includes a first vacuum gauge 13 provided on the eighth pipeline and a second vacuum gauge 14 provided on the ninth pipeline, which are used to monitor the vacuum degree of the primary adsorption tower 3 and the condenser 5 respectively.

[0048] Comparative Example 1

[0049] This comparative example is a trimethylaluminum purification device using a traditional single-stage adsorption + distillation device in the prior art (ordinary flange sealing, manual control).

[0050] The operating conditions of Example 1 and Comparative Example 1 are:

[0051] Raw materials: industrial grade trimethylaluminum (purity 99.2%, containing Fe 50ppb, S compound 200ppm);

[0052] Operating parameters: feed rate 5L / h;

[0053] System pressure 10 -2 Pa;

[0054] 100 hours of continuous operation.

[0055] The test results of the embodiments and comparative examples are listed in Table 1.

[0056] Table 1

[0057]

[0058] Table 1 shows that in terms of purity and impurity control, Example 1 achieves a 100-fold increase in product purity, with the key metal impurity (Fe) content reduced to 1 / 16 of that in the comparative example, and sulfide is completely removed. This is due to the specific adsorption of sulfides by the sodium-potassium alloy bed (removal rate >99.95%) and the electrolytic polishing of the pipeline to prevent metal ion contamination. In terms of energy consumption and efficiency, Example 1 achieves a 39.2% energy saving, primarily due to the integrated heat recovery design of the precooler and adsorption tower, and the intelligent control system that optimizes operating parameters in real time. Regarding sealing and safety, the double seal reduces the leakage rate by four orders of magnitude and increases emergency response speed by five times, completely resolving the pain points of leaks and slow response associated with traditional devices. In terms of operational stability, Example 1 extends the continuous operating cycle by 13 times, demonstrating the durability advantages of the sintered metal distributor 3b and corrosion-resistant sealing materials. Through innovative structures (such as a dual-stage adsorption tower), materials (such as magnesium fluoride-coated piping), and control technologies (fast response time of <50ms), this new technology surpasses conventional technologies in core performance indicators such as purity, energy efficiency, and safety, meeting the stringent requirements of semiconductor-grade TMA. The results of Comparative Example 1 highlight bottlenecks that are difficult to overcome with existing technologies, such as high residual impurities, high energy consumption, and frequent maintenance, further demonstrating the technological advancement and industrial value of this new technology.

[0059] In summary, the purity of this utility model has been improved significantly. The "pre-cooling-two-stage adsorption-low-temperature condensation" coordinated purification system can increase the purity of trimethylaluminum from the industry standard of 99.9% to more than 99.9995%; the specially designed sodium-potassium alloy bed can remove sulfur-containing impurities in a targeted manner (removal rate > 99.8%); the process efficiency of this utility model has been significantly improved, and the integrated modular design has reduced the equipment volume by 40% and energy consumption by 35%; the fully automatic control system realizes unattended operation and improves production efficiency by 50%; the safety performance of this utility model has been comprehensively upgraded, and the emergency interlock system with a fast response of < 50ms has increased the accident prevention rate by 90%; the double-sealed pipeline design has reduced the leakage rate by < 10 -9 Pa·m 3 / s; The utility model significantly reduces operating costs, and the new sintered metal distributor extends the service life of the filler by 3 times; the intelligent regeneration system reduces inert gas consumption by 60%.

[0060] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0061] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to the above embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein, but is intended to encompass the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A purification device for high-purity trimethylaluminum, characterized in that: It comprises: a raw material tank (1) with a cooling jacket, the bottom outlet of which is connected to the lower inlet of a precooler (2) via a first pipeline, wherein a first solenoid valve (9) is provided on the first pipeline; The precooler (2) has an upper outlet divided into two paths through a second pipeline, wherein the main path is connected to the bottom inlet of the first-stage adsorption tower (3) through a second solenoid valve (10), and the bypass path is connected to the emergency discharge port through a third solenoid valve (11), and the emergency discharge port is connected to the inert gas purge system; A primary adsorption tower (3), the top outlet of which is connected to the bottom inlet of a secondary adsorption tower (4) via a fourth pipeline, the primary adsorption tower (3) being filled with a composite filler layer (3a) of 3A molecular sieve and activated carbon, and having a sintered metal distributor (3b) at the bottom; A secondary adsorption tower (4), the top outlet of which is connected to the upper air inlet of the condenser (5) via a fifth pipeline, wherein the secondary adsorption tower (4) has a built-in sodium-potassium alloy dispersion bed layer and an external electric heating jacket; A condenser (5), the bottom outlet of which is connected to the upper liquid inlet of a finished product collection tank (6) via a sixth pipe, wherein the sixth pipe is a capillary tube with an inner diameter of 0.5 mm; The vacuum system comprises a molecular pump (7) connected to a three-way valve (12) via a seventh pipeline, a first branch of the three-way valve (12) connected to the top air extraction port of the first-stage adsorption tower (3) via an eighth pipeline, and a second branch connected to the air extraction port of the condenser (5) via a ninth pipeline.

2. The purification device for high-purity trimethylaluminum according to claim 1, characterized in that: The top of the raw material tank (1) is provided with an inert gas inlet for maintaining a slight positive pressure of 0.1-0.3 bar in the tank.

3. The purification device for high-purity trimethylaluminum according to claim 1, characterized in that: A 5 μm sintered metal filter (8) is provided in front of the bottom outlet of the raw material tank (1).

4. The purification device for high-purity trimethylaluminum according to claim 1, characterized in that: The precooler (2) is a spiral coil structure, the inner wall of which is coated with a magnesium fluoride coating, and a -30°C refrigerant is passed through the outside.

5. The purification device for high-purity trimethylaluminum according to claim 1, characterized in that: The ratio of the composite filler layer (3a) height to tower diameter of the first-stage adsorption tower (3) is 5:

1.

6. The purification device for high-purity trimethylaluminum according to claim 1, characterized in that: The sodium-potassium alloy bed of the secondary adsorption tower (4) is distributed in a wave shape, and the temperature control range of the electric heating jacket is 45-55°C.

7. The purification device for high-purity trimethylaluminum according to claim 1, characterized in that: The condenser (5) is a double helix structure, with a -78°C dry ice / acetone refrigerant inlet provided on the top; the finished product collection tank (6) is equipped with a weighing sensor with a measurement accuracy of ±0.1g.

8. The purification device for high-purity trimethylaluminum according to claim 1, characterized in that: The first to ninth pipelines are all made of 316L stainless steel, and the inner walls are electrolytically polished to a surface roughness of Ra≤0.2μm. Double O-ring sealing flanges are used to connect the pipelines.

9. The purification device for high-purity trimethylaluminum according to claim 1, characterized in that: The response time from the first solenoid valve to the third solenoid valve is less than 50ms, and is linked to the PLC controller.

10. The purification device for high-purity trimethylaluminum according to claim 1, characterized in that: The vacuum system further comprises a first vacuum gauge (13) provided on the eighth pipeline and a second vacuum gauge (14) provided on the ninth pipeline, which are used to monitor the vacuum degree of the first-stage adsorption tower (3) and the condenser (5), respectively.

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