System and method for removing nonmetal impurities in tungsten hexafluoride by using hydrogen

Abstract

The system comprises a primary light component removal tower, a discharge port of the primary light component removal tower is communicated with a secondary light component removal tower, top discharge ports of the primary light component removal tower and the secondary light component removal tower are communicated with a light component tank, a discharge port of the secondary light component removal tower is communicated with a tubular heat exchanger, and a discharge port of the tubular heat exchanger is communicated with a discharge port of the primary light component removal tower and a discharge port of the secondary light component removal tower. The tubular heat exchanger is communicated with the collector; the invention also relates to a method for removing non-metallic impurities in tungsten hexafluoride by using hydrogen, which comprises the following steps: introducing a crude product tungsten hexafluoride carrying hydrogen from the bottom of the first-stage light component removal tower, and carrying out oxidation reduction under the conditions of high temperature and a catalyst; after oxidation reduction, the hydrogen enters a second-stage light component removal tower and is further reduced at a higher temperature to form mixed gas, and unreacted hydrogen and light components enter a light component tank from the top of the second-stage light component removal tower; the mixed gas is collected after heat exchange, and finally removal of non-metal impurities in tungsten hexafluoride is completed. The continuous operation of tungsten hexafluoride purification is realized, the technological operation is simple, and the reaction efficiency is high.

Description

Technical Field

[0001] The invention belongs to the technical field of fluorine-containing fine chemical synthesis, and specifically relates to a system and method for removing non-metallic impurities in tungsten hexafluoride by using hydrogen. Background Art

[0002] Tungsten hexafluoride is an electronic gas that is widely used in the field of ultra-large-scale circuits and semiconductor materials. As the main raw material for the chemical vapor deposition (CVD) process, tungsten hexafluoride is the main chemical gas used to manufacture large-scale integrated circuits. Its purity is required to be high, often above 99.99%. At present, the industry mostly uses fluorine gas and metal tungsten powder for gas-solid reaction to prepare tungsten hexafluoride, but it is limited by the purity of metal tungsten powder, resulting in the purity of the prepared product far from meeting the specification requirements.

[0003] Chinese patent CN116621223A discloses a process for removing metal impurities from tungsten hexafluoride. By chemical reduction, molybdenum hexafluoride and chromium hexafluoride in tungsten hexafluoride are reduced to solid-phase metal molybdenum and chromium precipitation using metal tungsten. However, this method has the disadvantage that the subsequently generated metal chromium and metal molybdenum are difficult to effectively separate from the tungsten powder.

[0004] Chinese patent CN118497776A discloses a device and method for preparing tungsten hexafluoride by treating tungsten powder with hydrogen. It discloses a method for removing the oxygen element carried by tungsten powder by reducing it to water at high temperature by using hydrogen generated by electrolysis. This method has complex process and involves an electrolytic fluorine gas production process, and the system safety is poor.

[0005] Chinese patent CN113574020B discloses a method for manufacturing tungsten hexafluoride, a method for purifying tungsten hexafluoride, and tungsten hexafluoride. The method comprises reacting arsenic or an arsenic compound with a fluorine-containing compound gas, and then separating and removing the trivalent arsenic compound through distillation and other processes to obtain tungsten hexafluoride. The tungsten hexafluoride obtained by this method has a high purity, but the arsenic or arsenic compound used contains highly toxic elements, which greatly increases the dangerous characteristics of the system.

[0006] In summary, the methods for purifying tungsten hexafluoride in existing patents and literature have the problems of poor system safety and complicated subsequent processing operations. Summary of the invention

[0007] In order to solve the problem that non-metallic impurities in crude tungsten hexafluoride are difficult to be completely and effectively removed, the present invention provides a system and method for removing non-metallic impurities in tungsten hexafluoride using hydrogen, and provides a feasible solution for improving the purity of tungsten hexafluoride.

[0008] The technical solution adopted by the present invention is: A system for removing non-metallic impurities in tungsten hexafluoride by using hydrogen comprises a primary light-removing tower and a secondary light-removing tower, wherein the primary light-removing tower comprises a primary light-removing tower feed port, a primary light-removing tower discharge port and a primary light-removing tower top gas outlet, wherein the secondary light-removing tower comprises a secondary light-removing tower feed port, a secondary light-removing tower discharge port and a secondary light-removing tower top gas outlet, wherein the primary light-removing tower discharge port is connected to the secondary light-removing tower feed port, the primary light-removing tower top gas outlet and the secondary light-removing tower top gas outlet are connected to a light component tank, the secondary light-removing tower discharge port is connected to a shell-and-tube heat exchanger, and the shell-and-tube heat exchanger is connected to a collector.

[0009] Preferably, the feed port of the first-stage light removal tower is connected to a mass flow meter.

[0010] Preferably, the primary light-removal tower and the secondary light-removal tower are made of monel alloy, and the shell-and-tube heat exchanger and the collector are made of stainless steel.

[0011] A method for removing non-metallic impurities in tungsten hexafluoride by using hydrogen, comprising the following steps: S1. Crude tungsten hexafluoride with hydrogen is introduced from the feed port of the primary light removal tower. Under high temperature and catalyst conditions, hydrogen contacts the non-metallic compounds in tungsten hexafluoride through gas phase evaporation and liquid phase reflux to carry out oxidation-reduction. Unreacted hydrogen and light components enter the light component tank from the top outlet of the primary light removal tower. S2, after oxidation and reduction, enters the secondary light-removal tower for further high-temperature oxidation and reduction, and the unreacted hydrogen and light components enter the light component tank from the top outlet of the secondary light-removal tower; S3. After the high-temperature oxidation and reduction is completed, the mixed gas is collected after heat exchange, and finally the non-metallic impurities in tungsten hexafluoride are removed.

[0012] Preferably, the purity of crude tungsten hexafluoride in S1 is below 95%; the hydrogen concentration is 150-200 ppm, and the gas velocity of the crude tungsten hexafluoride carrying hydrogen is 2-5 m / s.

[0013] Preferably, the high temperature in S1 is 100°C~250°C; the pressure of the primary light removal tower is controlled at 0.15~0.35MPa, the redox reaction time is 4~10min, and the gas flow rate in the primary light removal tower is 5~10m / s.

[0014] Preferably, the high temperature in S2 is 150°C~300°C, the pressure of the secondary light removal tower is controlled at 0.1~0.30 MPa; the reaction time is 2~4min, and the flow rate of the gas in the secondary light removal tower is 3~6m / s.

[0015] Preferably, the collection temperature in S3 is controlled between -40 and -140°C, and the collection rate reaches more than 99%.

[0016] Preferably, the heat exchange temperature in S3 is 7° C. to 10° C., and the product gas components are determined by component analysis using gas chromatography.

[0017] Preferably, the catalyst in S1 is a high boiling point metal fluoride, and the high boiling point metal fluoride is one or more of potassium fluoride, sodium fluoride and calcium fluoride.

[0018] The beneficial effects obtained by the present invention are: In S1, the redox reaction is carried out, and the low-cost non-metallic impurities are sent to the secondary light removal tower for further redox reaction. The product gas then enters the tube-and-shell heat exchanger for heat exchange and then enters the collector. This avoids the problem of introducing a large amount of hydrogen and reducing the safety of the system.

[0019] There is hydrogen in tungsten hexafluoride gas with a purity of less than 95%, and there are high-boiling point metal fluorides in the reaction equipment, mainly potassium fluoride, sodium fluoride, and calcium fluoride. The waste heat of the reaction and the heat provided by the equipment are used to stimulate the reaction of hydrogen and non-metallic impurities. After reaction and separation, the purity of the product is above 99.99%.

[0020] The separation efficiency of non-metallic impurities in tungsten hexafluoride reaches over 99.9%, among which the removal efficiency of impurity elements such as P, S, O, and C is over 99.9%.

[0021] The present invention mainly utilizes hydrogen of a certain concentration in crude tungsten hexafluoride and realizes continuous operation of tungsten hexafluoride purification by adjusting the kettle temperature and pressure of a two-stage light removal tower. The process operation is simple and the reaction efficiency is high.

[0022] By utilizing hydrogen of a certain purity in crude tungsten hexafluoride, the high-price non-metallic impurities carried in the tungsten hexafluoride are reduced and removed, and the effect of removing hydrogen impurities is achieved at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic diagram of the structure of a system for removing non-metallic impurities in tungsten hexafluoride using hydrogen according to the present invention; 1. Mass flow meter, 2. Primary light component removal tower, 3. Secondary light component removal tower, 4. Light component tank, 5. Shell and tube heat exchanger, 6. Collector. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0025] Two types of crude tungsten hexafluoride raw materials are taken, namely sample 1 and sample 2. The contents of non-metallic impurities in the crude tungsten hexafluoride of sample 1 and sample 2 are shown in Table 1 below.

[0026] Table 1 Non-metallic impurity content in crude tungsten hexafluoride index Sample before separation 1 / ppm Sample before separation 2 / ppm P 21.59 20.63 S 5.06 6.05 O 202.02 198.56 C 19.15 23.07 Before separation, the gas components were analyzed by gas chromatography. The purity of sample 1 was 94.24%, and the purity of sample 2 was 94.25%.

[0027] Device Embodiment A system for removing non-metallic impurities in tungsten hexafluoride by hydrogen, comprising a primary light-removing tower 2 and a secondary light-removing tower 3, wherein the primary light-removing tower feed port is connected to a mass flowmeter 1, the primary light-removing tower 2 comprises a primary light-removing tower feed port, a primary light-removing tower discharge port and a primary light-removing tower top gas outlet, the secondary light-removing tower 3 comprises a secondary light-removing tower feed port, a secondary light-removing tower discharge port and a secondary light-removing tower top gas outlet, the primary light-removing tower discharge port is connected to the secondary light-removing tower feed port, the primary light-removing tower top gas outlet and the secondary light-removing tower top gas outlet are connected to a light component tank 4, the secondary light-removing tower discharge port is connected to a shell-and-tube heat exchanger 5, and the shell-and-tube heat exchanger 5 is connected to a collector 6. The primary light-removing tower and the secondary light-removing tower are made of monel alloy, and the shell-and-tube heat exchanger and the collector are made of stainless steel.

[0028] Method Embodiment Example 1

[0029] A method for removing non-metallic impurities in tungsten hexafluoride by using hydrogen, comprising the following steps: S1. Crude tungsten hexafluoride with hydrogen is introduced from the feed port of the primary light removal tower. Under high temperature and catalyst conditions, hydrogen contacts the non-metallic compounds in tungsten hexafluoride through gas phase evaporation and liquid phase reflux to carry out oxidation-reduction. Unreacted hydrogen and light components enter the light component tank from the top outlet of the primary light removal tower. S2, after oxidation and reduction, enters the secondary light-removal tower for further high-temperature oxidation and reduction, and the unreacted hydrogen and light components enter the light component tank from the top outlet of the secondary light-removal tower; S3. After the high-temperature oxidation and reduction is completed, the mixed gas is collected after heat exchange, and finally the non-metallic impurities in tungsten hexafluoride are removed.

[0030] First, crude tungsten hexafluoride carrying hydrogen is introduced into the primary light removal tower 2 through the mass flow meter 1, and the mixed gas passing through the primary light removal tower 2 is then introduced into the secondary light removal tower 3 with a higher temperature, and finally the high-valent metal in the non-metallic impurities is reduced to a low-valent metal, wherein the unreacted hydrogen and light components enter the light component tank 4 for temporary storage, and the mixed gas after the reaction enters the shell and tube heat exchanger 5 for pre-heat exchange, and finally enters the collector 6 for collection, and finally the non-metallic impurities in tungsten hexafluoride are removed.

[0031] A method for removing non-metallic impurities from tungsten hexafluoride by hydrogen, wherein the gas velocity of crude tungsten hexafluoride carrying hydrogen is 5 m / s, the hydrogen concentration is 200 ppm, the temperature of the primary light removal tower 2 is 100-150°C, the pressure of the primary light removal tower 2 is controlled at 0.15-0.20 MPa, the reaction time of the primary light removal tower 2 is 4-10 min, and the gas flow rate in the primary light removal tower 2 is 5-10 m / s; the temperature of the secondary light removal tower 3 is 150-200°C, the pressure of the secondary light removal tower 3 is controlled at 0.1-0.15 MPa, the reaction time of the secondary light removal tower 3 is 2-4 min, and the gas flow rate in the secondary light removal tower 3 is 3-6 m / s. The catalyst is potassium fluoride, and the content of tungsten hexafluoride components in the collector 6 after the reaction is shown in Table 2 below.

[0032] The product gas passes through the shell-and-tube heat exchanger 5 and enters the collector 6. The collection temperature of the collector 6 is -40~-140℃. The impurity content is reduced by 99.91% through actual analysis and comparison calculation. The product gas components are characterized by gas chromatography, and comparative analysis is performed before and after separation.

[0033] Table 2 Non-metallic impurity content in the product index After separation, the sample is 1 / ppm After separation, the sample is 2 / ppm P 0.019 0.018 S 0.004 0.005 O 0.181 0.178 C 0.017 0.020 After separation, the gas components were analyzed by gas chromatography. The purity of sample 1 was 99.990%, and the purity of sample 2 was 99.992%.

[0034] Example 2

[0035] A method for removing non-metallic impurities from tungsten hexafluoride by hydrogen, wherein the gas velocity of crude tungsten hexafluoride with hydrogen is 2 m / s, the hydrogen concentration is 150 ppm, the temperature of the primary light removal tower 2 is 150-200°C, the pressure of the primary light removal tower 2 is controlled at 0.15-0.20 MPa, the reaction time of the primary light removal tower 2 is 4-10 min, and the gas flow rate in the primary light removal tower 2 is 5-10 m / s; the temperature of the secondary light removal tower 3 is 200-250°C, the pressure of the secondary light removal tower 3 is controlled at 0.10-0.15 MPa, the reaction time of the secondary light removal tower 3 is 2-4 min, and the gas flow rate in the secondary light removal tower 3 is 3-6 m / s. The catalyst is calcium fluoride, and the content of tungsten hexafluoride components in the collector after the reaction is shown in Table 3 below.

[0036] The product gas passes through the shell and tube heat exchanger 5 and enters the collector 6. The collection temperature of the collector 6 is -40~-140℃. The impurity content is reduced by 99.90% through actual analysis and comparison calculation. The product gas components are characterized by gas chromatography, and comparative analysis is performed before and after separation.

[0037] Table 3 Gas impurity content in the product index After separation, the sample is 1 / ppm After separation, the sample is 2 / ppm P 0.021 0.020 S 0.005 0.006 O 0.202 0.198 C 0.019 0.023 After separation, the gas components were analyzed by gas chromatography. The purity of sample 1 was 99.991%, and the purity of sample 2 was 99.993%.

[0038] Example 3

[0039] A method for removing non-metallic impurities from tungsten hexafluoride by hydrogen, wherein the gas velocity of crude tungsten hexafluoride carrying hydrogen is 3 m / s, the hydrogen concentration is 180 ppm, the temperature of the primary light removal tower 2 is 200-250°C, the pressure of the primary light removal tower 2 is controlled at 0.3-0.35 MPa, the reaction time of the primary light removal tower is 4-10 min, and the gas flow rate in the primary light removal tower 2 is 5-10 m / s; the temperature of the secondary light removal tower 3 is 250-300°C, the pressure of the secondary light removal tower 3 is controlled at 0.25-0.30 MPa, the reaction time of the secondary light removal tower 3 is 2-4 min, and the gas flow rate in the secondary light removal tower 3 is 3-6 m / s. The catalyst is sodium fluoride, and the content of tungsten hexafluoride components in the collector after the reaction is shown in Table 4 below.

[0040] The product gas passes through the shell-and-tube heat exchanger 5 and enters the collector 6. The collection temperature of the collector 6 is -40~-140°C. The impurity content is reduced by 99.94% through actual analysis and comparison calculation. The product gas components are characterized by gas chromatography.

[0041] Table 4 Gas impurity content in the product index After separation, the sample is 1 / ppm After separation, the sample is 2 / ppm P 0.0129 0.0123 S 0.003 0.0036 O 0.121 0.119 C 0.011 0.013 After separation, the gas components were analyzed by gas chromatography. The purity of sample 1 was 99.995%, and the purity of sample 2 was 99.998%.

[0042] Example 4

[0043] A method for removing non-metallic impurities from tungsten hexafluoride by hydrogen, wherein the gas velocity of crude tungsten hexafluoride carrying hydrogen is 4 m / s, the hydrogen concentration is 200 ppm, the temperature of the primary light removal tower 2 is 150-200°C, the pressure of the primary light removal tower 2 is controlled at 0.2-0.25 MPa, the reaction time of the primary light removal tower 2 is 4-10 min, and the gas flow rate in the primary light removal tower 2 is 5-10 m / s; the temperature of the secondary light removal tower 3 is 200-250°C, the pressure of the secondary light removal tower 3 is controlled at 0.15-0.20 MPa, the reaction time of the secondary light removal tower 3 is 2-4 min, and the gas flow rate in the secondary light removal tower 3 is 3-6 m / s. The catalyst is potassium fluoride, and the content of tungsten hexafluoride components in the collector after the reaction is shown in Table 5 below.

[0044] The product gas passes through the shell-and-tube heat exchanger 5 and enters the collector 6. The collection temperature of the collector 6 is -40~-140°C. The impurity content is reduced by 99.93% through actual analysis and comparison calculation. The product gas components are characterized by gas chromatography.

[0045] Table 5 Impurity content in the product index After separation, the sample is 1 / ppm After separation, the sample is 2 / ppm P 0.015 0.014 S 0.003 0.004 O 0.141 0.138 C 0.013 0.016 After separation, the gas components were analyzed by gas chromatography. The purity of sample 1 was 99.992%, and the purity of sample 2 was 99.996%.

[0046] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A system for removing non-metallic impurities from tungsten hexafluoride by using hydrogen, characterized in that: The invention comprises a primary light-removal tower (2) and a secondary light-removal tower (3), wherein the primary light-removal tower (2) comprises a primary light-removal tower feed port, a primary light-removal tower discharge port and a primary light-removal tower top gas outlet, and the secondary light-removal tower (3) comprises a secondary light-removal tower feed port, a secondary light-removal tower discharge port and a secondary light-removal tower top gas outlet, the primary light-removal tower discharge port is connected to the secondary light-removal tower feed port, the primary light-removal tower top gas outlet and the secondary light-removal tower top gas outlet are connected to a light component tank (4), the secondary light-removal tower discharge port is connected to a shell-and-tube heat exchanger (5), and the shell-and-tube heat exchanger (5) is connected to a collector (6).

2. A system for removing non-metallic impurities in tungsten hexafluoride by using hydrogen according to claim 1, characterized in that: The feed inlet of the first-stage light removal tower is connected to a mass flow meter (1).

3. The system for removing non-metallic impurities in tungsten hexafluoride by using hydrogen according to claim 1, characterized in that: The primary light-removal tower (2) and the secondary light-removal tower (3) are made of monel alloy, and the shell-and-tube heat exchanger (5) and the collector (6) are made of stainless steel.

4. A method for removing non-metallic impurities in tungsten hexafluoride by using hydrogen, using the system for removing non-metallic impurities in tungsten hexafluoride by using hydrogen as claimed in claim 1, characterized in that: The following steps are involved: S1. Crude tungsten hexafluoride carrying hydrogen is introduced from the feed port of the primary light removal tower. Under high temperature and catalyst conditions, hydrogen contacts the non-metallic compounds in the tungsten hexafluoride through gas phase evaporation and liquid phase reflux to undergo oxidation-reduction. Unreacted hydrogen and light components enter the light component tank (4) from the top outlet of the primary light removal tower. S2, after oxidation and reduction, enters the secondary light component removal tower (3) for further high-temperature oxidation and reduction, and the unreacted hydrogen and light components enter the light component tank (4) from the top outlet of the secondary light component removal tower; S3. After the high-temperature oxidation and reduction is completed, the mixed gas is collected after heat exchange, and finally the non-metallic impurities in tungsten hexafluoride are removed.

5. The method for removing non-metallic impurities in tungsten hexafluoride by using hydrogen according to claim 4, characterized in that: The purity of crude tungsten hexafluoride in S1 is below 95%; the hydrogen concentration is 150-200ppm, and the gas velocity of crude tungsten hexafluoride carrying hydrogen is 2-5m / s.

6. A method for removing non-metallic impurities in tungsten hexafluoride with hydrogen according to claim 4, characterized in that: The high temperature in S1 is 100°C~250°C; the pressure of the primary light removal tower (2) is controlled at 0.15~0.35MPa, the redox reaction time is 4~10min, and the gas flow rate in the primary light removal tower (2) is 5~10m / s.

7. The method for removing non-metallic impurities in tungsten hexafluoride by using hydrogen according to claim 4, characterized in that: The high temperature in S2 is 150°C~300°C, the pressure of the secondary light removal tower (3) is controlled at 0.1~0.30 MPa; the reaction time is 2~4 minutes, and the flow rate of the gas in the secondary light removal tower (3) is 3~6 m / s.

8. The method for removing non-metallic impurities in tungsten hexafluoride by using hydrogen according to claim 4, characterized in that: The collection temperature in S3 is controlled between -40 and -140°C.

9. The method for removing non-metallic impurities in tungsten hexafluoride by using hydrogen according to claim 4, characterized in that: The heat exchange temperature in S3 is 7°C~10°C, and the product gas components are determined by component analysis using gas chromatography.

10. The method for removing non-metallic impurities in tungsten hexafluoride by using hydrogen according to claim 4, characterized in that: The catalyst in S1 is a high boiling point metal fluoride, and the high boiling point metal fluoride is one or more of potassium fluoride, sodium fluoride and calcium fluoride.

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