Method and device for improving the preparation of high-purity deuterium gas by electrolysis by pre-treating heavy water with a degassing membrane

Abstract

The application belongs to the field of deuterium gas preparation and purification, and particularly relates to a method and device for improving electrolytic preparation of high-purity deuterium gas by pretreating heavy water with a degassing membrane. The device comprises an electrolytic cell, an oxygen separator, a deuterium separator, a drying tower, a degassing membrane assembly, a circulating pump and a vacuum pump. The cathode of the electrolytic cell is connected to the deuterium separator, the anode of the electrolytic cell is connected to the oxygen separator, the bottom of the oxygen separator is connected to the degassing membrane assembly through the circulating pump, the side of the degassing membrane assembly for separating gaseous substances is connected to the vacuum pump, and the degassing membrane assembly is connected to the electrolytic cell. The method comprises pretreatment, electrolysis and gas purification and separation. The application completes the first purification of heavy water through the pretreatment of the degassing membrane assembly, removes impurities such as oxygen, nitrogen and methane for the first time, and then makes the deuterium gas produced by electrolysis contain only a small amount of water, so that high-purity deuterium gas with a purity of greater than or equal to 99.9999% can be obtained through secondary purification (the drying tower). Meanwhile, the method has strong operability, low safety risk and is easy to scale up.

Description

Technical Field

[0001] This application belongs to the field of deuterium preparation and purification, specifically relating to a method and apparatus for preparing high-purity deuterium by electrolysis after degassing membrane pretreatment of heavy water. Background Technology

[0002] Deuterium, composed of the isotope of deuterium (heavy hydrogen), possesses slightly different physical and chemical properties compared to ordinary hydrogen. It is widely used in nuclear energy, medical testing, pharmaceuticals, and laser weapons. Particularly in the semiconductor industry, deuterium applications are concentrated in key processes such as annealing and metal-organic chemical vapor deposition (MOCVD). Annealing is an indispensable step in semiconductor manufacturing, used to improve the structure and properties of crystals. Deuterium can serve as a hydrogen source substitute in the annealing process; its heavier isotope provides higher thermal conductivity, resulting in more precise annealing. Furthermore, deuterium can be used as a hydrogen source in MOCVD to modulate the properties and structure of deposited films, thereby improving film quality and performance.

[0003] However, the application of deuterium in the semiconductor industry still faces some technical challenges. One of these challenges is that the semiconductor industry has high requirements for the purity and stability of deuterium. However, the commonly used method for preparing deuterium is the heavy water electrolysis method. Due to the limitations of its process, the nitrogen and oxygen content in the deuterium product is high, resulting in high purification difficulty and high purification cost. Summary of the Invention

[0004] To address the challenges and high costs associated with purifying nitrogen and oxygen in the deuterium produced by the existing heavy water electrolysis method, this application provides a method and apparatus for pretreating heavy water with a degassing membrane to enhance the electrolysis process for producing high-purity deuterium.

[0005] In a first aspect, this application provides an apparatus for pretreating heavy water with a degassing membrane to enhance the electrolytic preparation of high-purity deuterium gas, employing the following technical solution:

[0006] An apparatus for improving the electrolytic production of high-purity deuterium by pretreating heavy water through a degassing membrane includes an electrolytic cell, an oxygen separator, a deuterium separator, a drying tower, a degassing membrane assembly, a circulating pump, and a vacuum pump.

[0007] The cathode of the electrolytic cell is connected to the deuterium separator, which is equipped with a deuterium vent valve and is connected to the drying tower.

[0008] The anode of the electrolytic cell is connected to the oxygen separator, which is equipped with an oxygen vent valve; the bottom of the oxygen separator is connected to the degassing membrane module via a circulation pump; the gas-separated side of the degassing membrane module is connected to a vacuum pump; and the degassing membrane module is connected to the electrolytic cell.

[0009] In one specific feasible implementation, the bottom of the deuterium separator is connected to a circulating pump.

[0010] In one specific implementation, the degassing membrane assembly includes a housing, a degassing membrane, and an encapsulating adhesive, wherein the degassing membrane is embedded in the housing, and the encapsulating adhesive fixes the degassing membrane in the housing; wherein the degassing membrane is made of polytetrafluoroethylene.

[0011] Secondly, this application provides a method for pretreating heavy water with a degassing membrane to enhance the electrolytic preparation of high-purity deuterium gas, employing the following technical solution:

[0012] A method for improving the electrolytic production of high-purity deuterium gas by pretreating heavy water through a degassing membrane includes the following steps:

[0013] I. Pretreatment

[0014] Heavy water is fed into the degassing membrane module via a circulating pump. The degassing membrane module pre-treats the heavy water, separating nitrogen, oxygen, and methane impurities from it. A vacuum pump provides the pressure for membrane separation.

[0015] II. Electrolysis

[0016] The pretreated heavy water is fed into an electrolytic cell containing KOD. The electrolytic cell electrolyzes the heavy water, generating oxygen at the anode and deuterium at the cathode.

[0017] III. Gas Purification and Separation

[0018] Oxygen carrying KOD alkaline solution enters the oxygen separator for separation, while deuterium carrying KOD alkaline solution enters the deuterium separator for separation. The separated deuterium is then dried and bottled for collection.

[0019] In one specific feasible implementation, the purity of the heavy water used in step one is ≥99.7%.

[0020] In one specific feasible implementation, the circulation pump rate is 5–8 kg / min.

[0021] In one specific feasible implementation, the pressure of the vacuum pump is -0.05 to -0.1 MPa.

[0022] This application includes the following beneficial technical effects:

[0023] The apparatus provided in this application includes: an oxygen separator, a deuterium separator, a circulating pump, a degassing membrane, a vacuum pump, an electrolytic cell, a drying tower, and a cylinder group. The degassing membrane component pre-treatment completes the primary purification of the raw material heavy water, removing impurities such as oxygen, nitrogen, and methane from the heavy water. This results in the deuterium gas produced by electrolysis containing only trace amounts of water. Subsequent secondary purification (drying tower) yields high-purity deuterium gas with a purity ≥99.9999%.

[0024] This process significantly simplifies the purification process of deuterium produced by electrolysis compared to traditional, complex, and equipment-intensive electrolytic deuterium production processes. It boasts advantages such as simple design and high operability. Furthermore, this method avoids unsafe reagents and operations, resulting in low safety risks. It also saves production costs and is easily scalable for mass production. The deuterium gas prepared using this method and apparatus exhibits excellent purity, providing a good guarantee and improvement for the quality stability of semiconductor products, thereby leading to better economic benefits and market demand. Attached Figure Description

[0025] Figure 1 This is a process flow diagram of the method for preparing high-purity deuterium gas by electrolysis of degassed membrane pretreatment of heavy water according to this application.

[0026] Explanation of reference numerals in the attached drawings: 1. Electrolytic cell; 2. Oxygen separator; 3. Deuterium separator; 4. Circulating pump; 5. Degassing membrane module; 6. Vacuum pump; 7. Drying tower; 8. Gas cylinder.

[0027] V1, V2, V3, V4, V5, V6, V7, V8, V9, V10, and V11 all represent valves. Detailed Implementation

[0028] The following is in conjunction with the appendix Figure 1 This application will be described in further detail.

[0029] Example 1

[0030] This embodiment provides an apparatus for pretreating heavy water with a degassing membrane to enhance the electrolytic preparation of high-purity deuterium gas, including an electrolytic cell 1, an oxygen separator 2, a deuterium separator 3, a drying tower 7, a degassing membrane assembly 5, a circulating pump 4, a vacuum pump 6, and a gas cylinder 8.

[0031] Electrolytic cell 1 is used to electrolyze heavy water to generate deuterium gas. The cathode of electrolytic cell 1 is connected to the bottom of deuterium separator 3 via valve V8, and the anode of electrolytic cell 1 is connected to the bottom of oxygen separator 2 via valve V7. Electrolytic cell 1 is also connected to degassing membrane assembly 5 via V6. Valves V9 are provided at the top of oxygen separator 2 to vent oxygen. Valves V10 are provided at the top of deuterium separator 3 to vent air from deuterium separator 3 to obtain high-purity deuterium gas. Valves V11 are also provided at the top of deuterium separator 3, and deuterium separator 3 is connected to drying tower 7 via valve V11. Drying tower 7 is used to dry deuterium gas mixed with moisture, and the bottom of deuterium separator 3 is connected to cylinder 8, which is used to store deuterium gas. Circulating pump 4 is a metering pump used to control the flow rate of heavy water.

[0032] A valve V3 is provided on the left side of the circulating pump 4 to control the flow of heavy water; the right side of the circulating pump 4 is connected to the degassing membrane assembly 5, and the side of the degassing membrane assembly 5 away from the circulating pump 4 is connected to the vacuum pump 6 through valve V5.

[0033] The oxygen separator 2 is equipped with valve V1 at the bottom, the deuterium separator 3 is equipped with valve V2 at the bottom, the circulating pump 4 is equipped with valve V3 on the left side, and the circulating pump 4 is connected to the degassing membrane assembly 5 on the right side through valve V4.

[0034] The degassing membrane module 5 includes a housing, a degassing membrane, and an encapsulating adhesive. The degassing membrane is housed within the housing, and the encapsulating adhesive secures the degassing membrane within the housing. The degassing membrane is made of polytetrafluoroethylene (PTFE), the encapsulating adhesive is epoxy resin, and the housing is UPVC. The degassing membrane module 5 of this application primarily uses a PTFE hollow fiber membrane as the mass transfer medium. The micropores on the surface of this membrane act as the mass transfer interface. Due to the hydrophobicity of PTFE, liquid water cannot pass through the membrane pores, but gas molecules dissolved in the water can. During operation, heavy water flows inside the PTFE hollow fiber membrane, thereby achieving gas removal.

[0035] The separation principles of oxygen separator 2 and deuterium separator 3 are relatively mature existing technologies, which will not be elaborated here. Oxygen separator 2 and deuterium separator 3 are filled with heavy water, which is used to separate and dissolve KOD entrained in oxygen or deuterium. The dissolved KOD heavy water solution can be introduced into electrolytic cell 1 through a valve for recycling. Before electrolysis starts, the heavy water in deuterium separator 3 and oxygen separator 2 can also be used as raw material. The purity of the heavy water is not less than 99.7% to obtain high-purity deuterium.

[0036] Example 2

[0037] Based on the apparatus provided in Example 1, this application provides a method for preparing high-purity deuterium gas by electrolysis of degassed membrane pretreatment of heavy water, comprising the following steps:

[0038] I. Pretreatment

[0039] Open valves V1, V2, V3, V4, V5, and V6, and pass heavy water with a purity of not less than 99.7% into the degassing membrane module 5 through the circulation pump 4. The degassing membrane module 5 separates impurities such as nitrogen, oxygen, and methane from the heavy water. During this process, the vacuum pump 6 provides the pressure for membrane separation. Control the speed of the circulation pump 4 to 5 kg / min and the pressure of the vacuum pump 6 to -0.05 MPa.

[0040] II. Electrolysis

[0041] The pretreated heavy water is fed into an electrolytic cell 1 equipped with KOD. The temperature of the electrolytic cell 1, the deuterium separator 3 and the oxygen separator 2 are controlled at 20°C and the electrolysis current is 100A. The electrolytic cell 1 electrolyzes the heavy water, generating oxygen at the anode and deuterium at the cathode.

[0042] III. Gas Purification and Separation

[0043] Oxygen mixed with some KOD alkaline solution is passed into oxygen separator 2 for separation. The separated oxygen is then directly vented. Deuterium separator 3, drying tower 7, and cylinder 8 are vented through valve V10. After the air is vented, valve V8 is opened to pass deuterium gas into deuterium separator 3 for separation. The separated deuterium gas is then directly passed into drying tower 7 through valve V11 for drying. After drying, the deuterium gas is passed into cylinder 8.

[0044] Example 3

[0045] Based on the apparatus provided in Example 1, this application provides a method for preparing high-purity deuterium gas by electrolysis of degassed membrane pretreatment of heavy water, comprising the following steps:

[0046] I. Pretreatment

[0047] Open valves V1, V2, V3, V4, V5, and V6, and pass heavy water with a purity of not less than 99.7% into the degassing membrane module 5 through the circulation pump 4. The degassing membrane module 5 separates impurities such as nitrogen, oxygen, and methane from the heavy water. During this process, the vacuum pump 6 provides the pressure for membrane separation. Control the speed of the circulation pump 4 to 6 kg / min and the pressure of the vacuum pump 6 to -0.07 MPa.

[0048] II. Electrolysis

[0049] The pretreated heavy water is fed into an electrolytic cell 1 equipped with KOD. The temperature of the electrolytic cell 1, the deuterium separator 3 and the oxygen separator 2 is controlled at 40°C and the electrolysis current is 300A. The electrolytic cell 1 electrolyzes the heavy water, generating oxygen at the anode and deuterium at the cathode.

[0050] III. Gas Purification and Separation

[0051] Oxygen mixed with some KOD alkaline solution is passed into oxygen separator 2 for separation. The separated oxygen is then directly vented. Deuterium separator 3, drying tower 7, and cylinder 8 are vented through valve V10. After the air is vented, valve V8 is opened to pass deuterium gas into deuterium separator 3 for separation. The separated deuterium gas is then directly passed into drying tower 7 through valve V11 for drying. After drying, the deuterium gas is passed into cylinder 8.

[0052] Example 4

[0053] Based on the apparatus provided in Example 1, this application provides a method for preparing high-purity deuterium gas by electrolysis of degassed membrane pretreatment of heavy water, comprising the following steps:

[0054] I. Pretreatment

[0055] Open valves V1, V2, V3, V4, V5, and V6, and pass heavy water with a purity of not less than 99.7% into the degassing membrane module 5 through the circulation pump 4. The degassing membrane module 5 separates impurities such as nitrogen, oxygen, and methane from the heavy water. During this process, the vacuum pump 6 provides the pressure for membrane separation. Control the speed of the circulation pump 4 to 7 kg / min and the pressure of the vacuum pump 6 to -0.08 MPa.

[0056] II. Electrolysis

[0057] The pretreated heavy water is fed into an electrolytic cell 1 equipped with KOD. The temperature of the electrolytic cell 1, the deuterium separator 3 and the oxygen separator 2 is controlled at 60°C and the electrolysis current is 700A. The electrolytic cell 1 electrolyzes the heavy water, generating oxygen at the anode and deuterium at the cathode.

[0058] III. Gas Purification and Separation

[0059] Oxygen mixed with some KOD alkaline solution is passed into oxygen separator 2 for separation. The separated oxygen is then directly vented. Deuterium separator 3, drying tower 7, and cylinder 8 are vented through valve V10. After the air is vented, valve V8 is opened to pass deuterium gas into deuterium separator 3 for separation. The separated deuterium gas is then directly passed into drying tower 7 through valve V11 for drying. After drying, the deuterium gas is passed into cylinder 8.

[0060] Example 5

[0061] Based on the apparatus provided in Example 1, this application provides a method for preparing high-purity deuterium gas by electrolysis of degassed membrane pretreatment of heavy water, comprising the following steps:

[0062] I. Pretreatment

[0063] Open valves V1, V2, V3, V4, V5, and V6, and pass heavy water with a purity of not less than 99.7% into the degassing membrane module 5 through the circulation pump 4. The degassing membrane module 5 separates impurities such as nitrogen, oxygen, and methane from the heavy water. During this process, the vacuum pump 6 provides the pressure for membrane separation. Control the speed of the circulation pump 4 to 8 kg / min and the pressure of the vacuum pump 6 to -0.1 MPa.

[0064] II. Electrolysis

[0065] The pretreated heavy water is fed into an electrolytic cell 1 equipped with KOD. The temperature of the electrolytic cell 1, the deuterium separator 3 and the oxygen separator 2 is controlled at 80°C and the electrolysis current is 1000A. The electrolytic cell 1 electrolyzes the heavy water, generating oxygen at the anode and deuterium at the cathode.

[0066] III. Gas Purification and Separation

[0067] Oxygen mixed with some KOD alkaline solution is passed into oxygen separator 2 for separation. The separated oxygen is then directly vented. Deuterium separator 3, drying tower 7, and cylinder 8 are vented through valve V10. After the air is vented, valve V8 is opened to pass deuterium gas into deuterium separator 3 for separation. The separated deuterium gas is then directly passed into drying tower 7 through valve V11 for drying. After drying, the deuterium gas is passed into cylinder 8.

[0068] Test results

[0069] The purity of the deuterium gas collected in cylinder 8 of Examples 2-5 was tested by GC, and the purity of the deuterium gas obtained in Examples 2-5 was found to be above 99.9999%.

[0070] Currently, the technical solution of this application has undergone pilot testing, i.e., small-scale experiments before large-scale mass production. After the pilot testing was completed, user surveys were conducted on a small scale, and the survey results showed that user satisfaction was high. Now, preparations are underway for the formal production and industrialization of the product (including intellectual property risk warning surveys). The above description is only a preferred embodiment of the present invention; however, the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and its improved concepts, should be covered within the scope of protection of the present invention.

Claims

1. A method for improving the preparation of high-purity deuterium gas by electrolysis of heavy water with degassing membrane pretreatment, characterized in that, It comprises the following steps: I. Pretreatment Heavy water is introduced into a degassing membrane assembly (5) by a circulating pump (4), the degassing membrane assembly (5) separates nitrogen and oxygen and methane impurities in the heavy water, and a vacuum pump (6) provides pressure during membrane separation; II. Electrolysis The pretreated heavy water is introduced into an electrolytic tank (1) containing KOD, the electrolytic tank (1) electrolyzes the heavy water, oxygen is generated at the anode, and deuterium is generated at the cathode; III. Gas purification and separation Oxygen carrying KOD lye is introduced into an oxygen separator (2) for separation, deuterium carrying KOD lye is introduced into a deuterium separator (3) for separation, and the separated deuterium is dried and collected after filling; The purity of the heavy water used in step I is ≥99.7%; The circulating pump (4) has a rate of 5-8 kg / min; The vacuum pump (6) has a pressure of -0.05 to -0.1 MPa; The method relies on the following device: The device comprises an electrolytic tank (1), an oxygen separator (2), a deuterium separator (3), a drying tower (7), a degassing membrane assembly (5), a circulating pump (4), and a vacuum pump (6); The cathode of the electrolytic tank (1) is connected to the deuterium separator (3), the deuterium separator (3) is provided with a deuterium evacuation valve, and the deuterium separator (3) is connected to the drying tower (7); The anode of the electrolytic tank (1) is connected to the oxygen separator (2), the oxygen separator (2) is provided with an oxygen evacuation valve, the bottom of the oxygen separator (2) is connected to the degassing membrane assembly (5) by the circulating pump (4), one side of the degassing membrane assembly (5) is connected to the vacuum pump (6), and the degassing membrane assembly (5) is connected to the electrolytic tank (1); The bottom of the deuterium separator (3) is connected to the circulating pump (4); The degassing membrane assembly (5) comprises a shell, a degassing membrane, and encapsulation glue, the degassing membrane is built-in the shell, and the encapsulation glue fixes the degassing membrane in the shell; wherein the material of the degassing membrane is polytetrafluoroethylene.

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