A system and method for removing non-metallic impurities from tungsten hexafluoride by hydrogen

Abstract

The present application relates to a kind of hydrogen removal nonmetallic impurities in tungsten hexafluoride system, including primary light removal tower, the primary light removal tower outlet is communicated secondary light removal tower, the primary light removal tower and secondary light removal tower top outlet is communicated light component tank, the secondary light removal tower outlet is communicated column tube heat exchanger, the column tube heat exchanger is communicated collector;The present application also relates to a kind of hydrogen removal nonmetallic impurities in tungsten hexafluoride method, from the bottom of primary light removal tower, crude tungsten hexafluoride with hydrogen is introduced, and it is carried out under high temperature, catalyst condition oxidation reduction;After oxidation reduction, into secondary light removal tower, it is further reduced under higher temperature, form mixed gas, unreacted hydrogen and light component from the top of secondary light removal tower into light component tank;Mixed gas is collected after heat exchange, finally complete the removal of nonmetallic impurities in tungsten hexafluoride.The present application realizes the continuous operation of tungsten hexafluoride purification, process operation is simple, and reaction efficiency is high.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of fluorine-containing fine chemical synthesis, and particularly relates to a system and method for removing non-metallic impurities from tungsten hexafluoride by hydrogen. BACKGROUND

[0002] Tungsten hexafluoride is an electronic gas widely used in the field of super-large-scale circuit and semiconductor materials. As the main raw material for chemical vapor deposition (CVD) process, tungsten hexafluoride is a main chemical gas for manufacturing large-scale integrated circuits, and its purity is required to be higher than 99.99%. Currently, tungsten hexafluoride is prepared by gas-solid reaction of fluorine gas and tungsten powder in industry, but the purity of the prepared product cannot meet the specification requirements due to the limitation of the purity of tungsten powder.

[0003] The process for removing metal impurities from tungsten hexafluoride in Chinese patent CN116621223A uses a chemical reduction method to reduce molybdenum hexafluoride and chromium hexafluoride in tungsten hexafluoride into solid-phase metal molybdenum and chromium by using tungsten. However, this method has the disadvantage that the generated metal chromium and metal molybdenum are difficult to separate from tungsten powder.

[0004] Chinese patent CN118497776A discloses a device and method for preparing tungsten hexafluoride by using hydrogen gas to reduce oxygen elements carried by tungsten powder into water at high temperature. However, this method has the disadvantages of complex process and poor system safety due to the electrolytic fluorine gas process.

[0005] Chinese patent CN113574020B discloses a method for manufacturing tungsten hexafluoride, a purification method thereof, and tungsten hexafluoride. The method uses arsenic or arsenic compounds to react with fluorine-containing compound gas, and then removes trivalent arsenic compounds by distillation and other processes to obtain tungsten hexafluoride. However, this method has the disadvantage that the used arsenic or arsenic compounds contain toxic elements, which greatly increases the risk characteristics of the system.

[0006] In summary, the existing patents and literature have the problems of poor system safety and complicated subsequent processing operation in the method for purifying tungsten hexafluoride. SUMMARY

[0007] To solve the problem of difficult and effective removal of non-metallic impurities in crude tungsten hexafluoride, the application provides a system and method for removing non-metallic impurities from tungsten hexafluoride by hydrogen, which provides a feasible scheme for improving the purity of tungsten hexafluoride.

[0008] The technical scheme adopted by the application is as follows:

[0009] A system for removing non-metallic impurities in tungsten hexafluoride by hydrogen removal, comprising a first light removal column and a second light removal column, the first light removal column comprising a first light removal column feed port, a first light removal column discharge port and a first light removal column top gas outlet, the second light removal column comprising a second light removal column feed port, a second light removal column discharge port and a second light removal column top gas outlet, the first light removal column discharge port being connected to the second light removal column feed port, the first light removal column top gas outlet and the second light removal column top gas outlet being connected to a light component tank, the second light removal column discharge port being connected to a tube heat exchanger, and the tube heat exchanger being connected to a collector.

[0010] Preferably, the first light removal column feed port is connected to a mass flow meter.

[0011] Preferably, the first light removal column and the second light removal column are made of Monel, and the tube heat exchanger and the collector are made of stainless steel.

[0012] A method for removing non-metallic impurities in tungsten hexafluoride by hydrogen removal, comprising the following steps:

[0013] S1. Introducing crude tungsten hexafluoride carrying hydrogen from the first light removal column feed port, and under high temperature and catalyst conditions, hydrogen and non-metallic compounds in tungsten hexafluoride are contacted by gas phase evaporation and liquid phase reflux to perform oxidation and reduction, and unreacted hydrogen and light components are discharged from the first light removal column top gas outlet into the light component tank;

[0014] S2. After oxidation and reduction, further high temperature oxidation and reduction are performed in the second light removal column, and unreacted hydrogen and light components are discharged from the second light removal column top gas outlet into the light component tank;

[0015] S3. After high temperature oxidation and reduction, the mixed gas is collected after heat exchange, and the removal of non-metallic impurities in tungsten hexafluoride is finally completed.

[0016] Preferably, the purity of the 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.

[0017] Preferably, the high temperature in S1 is 100-250°C; the pressure in the first light removal column is controlled at 0.15-0.35 MPa, the oxidation and reduction reaction time is 4-10 min, and the gas flow rate in the first light removal column is 5-10 m / s.

[0018] Preferably, the high temperature in S2 is 150-300°C, the pressure in the second light removal column is controlled at 0.1-0.30 MPa; the reaction time is 2-4 min, and the gas flow rate in the second light removal column is 3-6 m / s.

[0019] Preferably, the collection temperature in S3 is controlled at -40 to -140°C, and the collection rate is above 99%.

[0020] Preferably, the heat exchange temperature in S3 is 7-10℃, and the product gas components are determined by component analysis by gas chromatography.

[0021] Preferably, the catalyst in S1 is a high-boiling metal fluoride, and the high-boiling metal fluoride is one or more of potassium fluoride, sodium fluoride and calcium fluoride.

[0022] The present application has the following beneficial effects:

[0023] In S1, the low-valence non-metallic impurities obtained by the redox reaction are further oxidized and reduced in the secondary light-removing tower, and the product gas is introduced into the tube heat exchanger and then into the collector, thereby avoiding the problem of reducing the system safety by introducing a large amount of hydrogen.

[0024] The hydrogen gas in the tungsten hexafluoride gas with a purity of less than 95%, the high-boiling metal fluoride in the reaction equipment, mainly potassium fluoride, sodium fluoride and calcium fluoride, and the reaction of hydrogen and non-metallic impurities excited by the reaction waste heat and the heat provided by the equipment are utilized, and after the reaction and separation, the purity of the product is more than 99.99%.

[0025] The separation efficiency of the non-metallic impurities in the tungsten hexafluoride is more than 99.9%, and the removal efficiency of the impurity elements such as P, S, O and C is more than 99.9%.

[0026] The present application mainly utilizes the hydrogen gas in the crude tungsten hexafluoride with a certain concentration, and adjusts the kettle temperature and pressure of the two-stage light-removing tower to realize the continuous operation of the tungsten hexafluoride purification, which is simple in process operation and high in reaction efficiency.

[0027] The high-valence non-metallic impurities carried in the tungsten hexafluoride are reduced and removed by utilizing the hydrogen gas in the crude tungsten hexafluoride with a certain purity, and the effect of removing the hydrogen impurities is realized. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 It is a system structure schematic diagram for removing non-metallic impurities in tungsten hexafluoride by hydrogen gas.

[0029] 1. mass flow meter, 2. first-stage light-removing tower, 3. second-stage light-removing tower, 4. light component tank, 5. tube heat exchanger, 6. collector. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments.

[0031] Two kinds of crude tungsten hexafluoride raw materials were taken as sample 1 and sample 2, and the non-metallic impurity contents in the crude tungsten hexafluoride of sample 1 and sample 2 were shown in Table 1.

[0032] Table 1 Non-metallic impurity content in crude tungsten hexafluoride

[0033] Indicator Sample 1 before separation / ppm Sample 2 before separation / ppm P 21.59 20.63 S 5.06 6.05 O 202.02 198.56 C 19.15 23.07

[0034] The gas components before separation were analyzed by gas chromatography, and the purity of sample 1 was 94.24%, and the purity of sample 2 was 94.25%.

[0035] Device embodiment

[0036] A system for removing non-metallic impurities in tungsten hexafluoride by hydrogen, comprising a first light removal column 2 and a second light removal column 3, the first light removal column feed port is communicated with a mass flow meter 1, the first light removal column 2 comprises a first light removal column feed port, a first light removal column discharge port and a first light removal column top gas outlet, the second light removal column 3 comprises a second light removal column feed port, a second light removal column discharge port and a second light removal column top gas outlet, the first light removal column discharge port is communicated with the second light removal column feed port, the first light removal column top gas outlet and the second light removal column top gas outlet are communicated with a light component tank 4, and the second light removal column discharge port is communicated with a tube heat exchanger 5, and the tube heat exchanger 5 is communicated with a collector 6. The material of the first light removal column and the second light removal column is Monel alloy, and the materials of the tube heat exchanger and the collector are stainless steel.

[0037] Method embodiment

[0038] Example 1

[0039] A method for removing non-metallic impurities in tungsten hexafluoride by hydrogen, comprising the following steps:

[0040] S1, introducing crude tungsten hexafluoride carrying hydrogen from the first light removal column feed port, under the condition of high temperature and catalyst, through the action of gas phase evaporation and liquid phase reflux, hydrogen contacts with non-metallic compounds in tungsten hexafluoride to carry out oxidation and reduction, and unreacted hydrogen and light components enter the light component tank from the first light removal column top gas outlet;

[0041] S2, after oxidation and reduction, further high-temperature oxidation and reduction are carried out in the second light removal column, and unreacted hydrogen and light components enter the light component tank from the second light removal column top gas outlet;

[0042] S3, after high-temperature oxidation and reduction, the mixed gas is collected after heat exchange, and the removal of non-metallic impurities in tungsten hexafluoride is finally completed.

[0043] Firstly, the crude tungsten hexafluoride carrying hydrogen is introduced into the first light removal tower 2 through the mass flow meter 1, the mixed gas passing through the first light removal tower 2 is introduced into the second light removal tower 3 with higher temperature, and finally the high-valence metal in the non-metallic impurities is reduced to low-valence metal, wherein the unreacted hydrogen and light components enter the light component tank 4 for temporary storage, the reacted mixed gas enters the tube heat exchanger 5 for pre-heating, and finally enters the collector 6 for collection, and finally the removal of non-metallic impurities in tungsten hexafluoride is completed.

[0044] A method for removing non-metallic impurities from tungsten hexafluoride by hydrogen, the gas velocity of crude tungsten hexafluoride carrying hydrogen is 5 m / s, the hydrogen concentration is 200 ppm, the temperature of the first light removal tower 2 is 100-150 DEG C, the pressure of the first light removal tower 2 is controlled at 0.15-0.20 MPa, the reaction time of the first light removal tower 2 is 4-10 min, and the gas flow rate in the first light removal tower 2 is 5-10 m / s; the temperature of the second light removal tower 3 is 150-200 DEG C, the pressure of the second light removal tower 3 is controlled at 0.1-0.15 MPa, the reaction time of the second light removal tower 3 is 2-4 min, and the gas flow rate in the second light removal tower 3 is 3-6 m / s. The catalyst is potassium fluoride, and the tungsten hexafluoride component content in the collector 6 after reaction is shown in Table 2.

[0045] The product gas enters the collector 6 through the tube heat exchanger 5, the collection temperature of the collector 6 is -40 to -140 DEG C, the impurity content is reduced by 99.91% through actual analysis and comparison, and the product gas component is characterized by gas chromatography.

[0046] Table 2 Non-metallic impurity content in product

[0047] Indicator Sample 1 after separation / ppm Sample 2 after separation / ppm P 0.019 0.018 S 0.004 0.005 O 0.181 0.178 C 0.017 0.020

[0048] The separated gas component is analyzed by gas chromatography, the purity of sample 1 is 99.990%, and the purity of sample 2 is 99.992%.

[0049] Example 2

[0050] A method for removing non-metallic impurities from tungsten hexafluoride by hydrogen, the gas velocity of crude tungsten hexafluoride carrying hydrogen is 5 m / s, the hydrogen concentration is 200 ppm, the temperature of the first light removal tower 2 is 100-150 DEG C, the pressure of the first light removal tower 2 is controlled at 0.15-0.20 MPa, the reaction time of the first light removal tower 2 is 4-10 min, and the gas flow rate in the first light removal tower 2 is 5-10 m / s; the temperature of the second light removal tower 3 is 150-200 DEG C, the pressure of the second light removal tower 3 is controlled at 0.1-0.15 MPa, the reaction time of the second light removal tower 3 is 2-4 min, and the gas flow rate in the second light removal tower 3 is 3-6 m / s. The catalyst is potassium fluoride, and the tungsten hexafluoride component content in the collector 6 after reaction is shown in Table 2.

[0051] The product gas enters the collector 6 through the tube heat exchanger 5, the collection temperature of the collector 6 is -40~ -140℃, the impurity content is reduced by 99.90% through actual analysis and comparison calculation, and the product gas components are characterized by gas chromatography.

[0052] Table 3: Gas impurity content in the product

[0053] Indicator Sample 1 after separation / ppm Sample 2 after separation / ppm P 0.021 0.020 S 0.005 0.006 O 0.202 0.198 C 0.019 0.023

[0054] After separation, the gas components are analyzed by gas chromatography, the purity of sample 1 is 99.991%, and the purity of sample 2 is 99.993%.

[0055] Example 3

[0056] A method for removing non-metallic impurities from tungsten hexafluoride by hydrogen removal, the gas velocity of crude tungsten hexafluoride carrying hydrogen is 3m / s, the hydrogen concentration is 180ppm, the temperature of the first light removal tower 2 is 200~250℃, the pressure of the first light removal tower 2 is controlled at 0.3~0.35MPa, the reaction time of the first light removal tower is 4~10min, the gas flow rate in the first light removal tower 2 is 5~10m / s; the temperature of the second light removal tower 3 is 250~300℃, the pressure of the second light removal tower 3 is controlled at 0.25~0.30MPa, the reaction time of the second light removal tower 3 is 2~4min, and the gas flow rate in the second light removal tower 3 is 3~6m / s. The catalyst is sodium fluoride, and the tungsten hexafluoride component content in the collector after reaction is shown in Table 4 below.

[0057] The product gas enters the collector 6 through the tube heat exchanger 5, the collection temperature of the collector 6 is -40~ -140℃, the impurity content is reduced by 99.90% through actual analysis and comparison calculation, and the product gas components are characterized by gas chromatography.

[0058] Table 4: Gas impurity content in the product

[0059] Indicator Sample 1 after separation / ppm Sample 2 after separation / ppm P 0.0129 0.0123 S 0.003 0.0036 O 0.121 0.119 C 0.011 0.013

[0060] After separation, the gas components are analyzed by gas chromatography, the purity of sample 1 is 99.995%, and the purity of sample 2 is 99.998%.

[0061] Example 4

[0062] A method for removing non-metallic impurities from tungsten hexafluoride by hydrogen removal, the gas velocity of crude tungsten hexafluoride carrying hydrogen is 4 m / s, the hydrogen concentration is 200 ppm, the temperature of the first light removal tower 2 is 150-200 DEG C, the pressure of the first light removal tower 2 is controlled at 0.2-0.25 MPa, the reaction time of the first light removal tower 2 is 4-10 min, the gas flow rate in the first light removal tower 2 is 5-10 m / s, the temperature of the second light removal tower 3 is 200-250 DEG C, the pressure of the second light removal tower 3 is controlled at 0.15-0.20 MPa, the reaction time of the second light removal tower 3 is 2-4 min, and the gas flow rate in the second light removal tower 3 is 3-6 m / s. The catalyst is potassium fluoride, and the tungsten hexafluoride component content in the collector after the reaction is shown in Table 5.

[0063] The product gas passes through the tube heat exchanger 5 into the collector 6, the collection temperature of the collector 6 is -40 to -140 DEG C, the impurity content is reduced by 99.93% through actual analysis and comparison calculation, and the product gas component is characterized by gas chromatography.

[0064] Table 5 impurity content in the product

[0065] Indicator Sample 1 after separation / ppm Sample 2 after separation / ppm P 0.015 0.014 S 0.003 0.004 O 0.141 0.138 C 0.013 0.016

[0066] The separated gas component is analyzed by gas chromatography, the purity of sample 1 is 99.992%, and the purity of sample 2 is 99.996%.

[0067] The above is only the preferred specific embodiment of the present application, but the protection scope of the present application is not limited to this, any skilled person in the art can make equivalent replacement or change according to the technical scheme and the inventive concept of the present application within the technical range disclosed by the present application, which should be covered in the protection scope of the present application.

Claims

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

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

3. The system for removing non-metallic impurities from tungsten hexafluoride 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 from tungsten hexafluoride using hydrogen, employing the system for removing non-metallic impurities from tungsten hexafluoride using hydrogen as described in claim 1, characterized in that... Includes the following steps: S1. Crude tungsten hexafluoride carrying hydrogen is introduced from the feed inlet of the first-stage light component removal tower. Under high temperature and catalyst conditions, hydrogen comes into contact with non-metallic compounds in tungsten hexafluoride through gas phase evaporation and liquid phase reflux, and undergoes oxidation and reduction. Unreacted hydrogen and light components enter the light component tank (4) from the top outlet of the first-stage light component removal tower. The high temperature in S1 is 100℃~250℃; the pressure of the first-stage 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 first-stage light removal tower (2) is 5~10m / s; The catalyst in S1 is a high-boiling-point metal fluoride, which is one or more of potassium fluoride, sodium fluoride, and calcium fluoride. S2, after oxidation and reduction, enters the secondary light component removal tower (3) for further high-temperature oxidation and reduction. Unreacted hydrogen and light components enter the light component tank (4) from the top outlet of the secondary light component removal tower. The high temperature in S2 is 150℃~300℃, the pressure in the secondary light removal tower (3) is controlled at 0.1~0.30 MPa; the reaction time is 2~4 min, and the gas flow rate in the secondary light removal tower (3) is 3~6 m / s; S3. After the high-temperature oxidation-reduction is completed, the mixed gas is collected after heat exchange, and the removal of non-metallic impurities in tungsten hexafluoride is finally completed.

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

6. The method for removing non-metallic impurities from tungsten hexafluoride using hydrogen according to claim 4, characterized in that, The collection temperature in S3 is controlled between -40 and -140℃.

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

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