Method for preparing silicon isotope and boron isotope

Abstract

The invention discloses a method for preparing a silicon isotope and a boron isotope. The method comprises the following steps: purifying boron powder through a pretreatment process to obtain high-purity boron powder; vacuumizing the reactor to-0.08 MPa to-0.09 MPa, then introducing inert gas to replace air in the reactor, and carrying out reduction reaction on the high-purity boron powder and the high-purity silicon tetrafluoride gas rich in silicon-28 in the reactor to obtain a crude silicon-28 isotope product; the method comprises the following steps: removing impurities from a crude silicon-28 isotope product through plasma zone melting to obtain a silicon-28 isotope product, removing excessive silicon tetrafluoride from generated boron trifluoride gas through a low-temperature rectification process, preparing boron-10 and boron-11 isotopes, and returning the excessive silicon tetrafluoride to a system for recycling. The one-step coupling preparation technology of the silicon and boron isotopes is developed, the silicon-28 isotopic, the boron-10 isotope and the boron-11 isotope are prepared at the same time, efficient directional conversion of the silicon and boron isotopes is achieved, the production cost is further reduced, and the economic benefits of the process are remarkable.

Description

Technical Field

[0001] This invention belongs to the field of isotope technology, specifically relating to a method for preparing silicon isotopes and boron isotopes. Background Technology

[0002] Isotopes of silicon and boron play crucial roles in cutting-edge technologies. High-purity silicon-28, crafted into perfect spheres, provides an atomic-level definition for the international kilogram standard. Its "zero-spin" property offers a clean, magnetically unaffected environment for quantum computers, while its excellent thermal conductivity promises to be used in the manufacture of smaller, faster next-generation semiconductor chips. Silicon-29, with its nuclear spin properties, serves as a sensitive probe for materials analysis; silicon-30 plays a "specialized tool" role in scientific research, used for cutting-edge physics experiments.

[0003] The value of boron isotopes is concentrated in the field of nuclear energy. Boron-10, with its neutron absorption capacity, serves as both a control and safety valve for nuclear reactors and a precise agent for killing cancer cells in boron neutron capture therapy. Boron-11, due to its neutron permeability, is an ideal material for future nuclear fusion devices. These special isotopes are driving innovative developments in metrology, quantum computing, and nuclear energy technology.

[0004] Currently, the technology for the separation and preparation of silicon and boron isotopes is mature internationally and has entered the industrialization stage. However, research on silicon and boron isotopes in my country is still in its early stages, with significant gaps remaining in engineering capabilities, cost control, and synergistic applications with the semiconductor / quantum industry. CN1327434A discloses a method for producing monoisotope silicon (Si). 28 The method involves reducing silicon tetrafluoride with calcium hydride to prepare silane, and then subjecting the obtained silane to high-temperature decomposition to obtain monoisotope Si. 28 However, these methods have drawbacks such as complex processes, high energy consumption, and difficulty in controlling the reaction. Boron isotopes are mostly prepared using chemical exchange distillation (using boron trifluoride (BF3) or its complexes as raw materials) and low-temperature distillation (using boron trifluoride or boranes as raw materials), but these methods suffer from problems such as limited supply of raw materials and high production costs.

[0005] Therefore, there is an urgent need to develop a method for preparing silicon and boron isotopes that is simple in process, highly efficient in separation, relatively low in energy consumption and cost, and easy to scale up for industrial production. This is of great strategic significance for ensuring my country's self-sufficiency in materials in key areas such as quantum information, nuclear energy security, and precision medicine. Summary of the Invention

[0006] To address the above technical problems, the present invention aims to provide a method for preparing silicon isotopes and boron isotopes that is simple in process, highly efficient in separation, relatively low in energy consumption and cost, and easy to implement in industrial applications.

[0007] To achieve the above technical objectives, the present invention adopts the following technical solution: A method for preparing silicon isotopes and boron isotopes, the process of which is as follows: (1) High-purity boron powder is obtained by purifying boron powder through a pretreatment process; (2) Evacuate the reactor to -0.08MPa~-0.09MPa, and then introduce inert gas to replace the air in the reactor. High-purity boron powder and high-purity tetrafluoride gas rich in silicon-28 undergo a reduction reaction in the reactor to obtain crude silicon-28 isotope product. (3) The silicon-28 isotope product crude product from step (2) is removed by plasma melting to obtain silicon-28 isotope product. The generated boron trifluoride gas is used to remove excess silicon tetrafluoride by low temperature distillation process and then used for the preparation of boron-10 and boron-11 isotopes. Excess silicon tetrafluoride is returned to the system for recycling.

[0008] Further, in step (1), the boron powder pretreatment and purification process is as follows: the boron powder is dissolved in hydrochloric acid and soaked at 40~60℃ for 1~2h, the concentration of the hydrochloric acid is 5~15wt%, and the mass ratio of boron powder to hydrochloric acid solution is 1:(6~8).

[0009] Furthermore, in step (2), the silicon-28 abundance in the silicon-28-rich silicon tetrafluoride gas is ≥98.5%, and the gas purity is ≥99.9%.

[0010] Further, in step (2), the control conditions for the reduction reaction are: the molar ratio of SiF4 to B is (3.5~4):4; the reaction temperature is 400~700℃; and the reaction pressure is -0.05~-0.15 KPa.

[0011] Furthermore, in step (2), the inert gas is argon, helium, etc.

[0012] Furthermore, in step (3), the control conditions for the low-temperature distillation process are: distillation temperature -48℃ to -30℃, and distillation pressure 1 to 1.5 MPa.

[0013] Further, in step (3), the plasma zone melting control conditions are: a hydrogen-argon mixture system, a temperature of 1420~1550℃, and a pressure of 10... -3 ~10 -5 Pa. Under these conditions, active hydrogen plasma (containing H⁺, H⁻, H) 0 (e.g., H2⁺) reacts chemically with boron in molten silicon to produce borane compounds, such as BH3 and B2H6, which are volatilized in gaseous form to remove impurities.

[0014] Furthermore, the volume ratio of hydrogen to argon in the hydrogen-argon mixture is 1:(4~9), and the hydrogen flow rate is 2~4 L / min.

[0015] Furthermore, the reactor is a fluidized bed, a high-temperature tubular furnace, a microreactor, etc.

[0016] Furthermore, the process for preparing boron-10 and boron-11 isotopes using purified boron trifluoride gas includes, but is not limited to, chemical exchange distillation, cryogenic distillation, ion exchange chromatography, centrifugation, etc.

[0017] The method for preparing silicon isotopes and boron isotopes in this invention mainly involves the following chemical reaction equations: 3SiF4 + 4B → 3Si + 4BF3 Compared with the prior art, the advantages of the present invention are as follows: (1) The strong reducing properties of elemental boron and its extremely high affinity for fluorine constitute the core driving force of the reaction, which promotes the efficient transfer of fluorine ligands from silicon to boron. High-purity silicon-28 products can be directly produced in one step, which fundamentally simplifies the traditional multi-step conversion process and significantly improves the reaction efficiency and economy.

[0018] (2) This invention develops a one-step coupling preparation technology for silicon and boron isotopes, and simultaneously prepares silicon-28 isotopes and boron-10 and boron-11 isotopes, realizing efficient directional conversion of silicon and boron isotopes, further reducing production costs, and the process has significant economic benefits. Attached Figure Description

[0019] Figure 1 This is a process flow diagram of the present invention; Figure 2 The mass spectrometry results of silicon-28 isotopes obtained in Example 1 are shown below. Figure 3 The mass spectrometry result of boron-10 isotopes obtained in Example 1 is shown. Figure 4 This is the mass spectrometry result of boron-11 isotopes obtained in Example 1. Detailed Implementation

[0020] The present application will be further described in detail below with reference to specific embodiments.

[0021] Example 1 A method for preparing silicon isotopes and boron isotopes, such as Figure 1 As shown, the method specifically includes the following steps: Boron powder was dissolved in 5wt% hydrochloric acid for soaking reaction. The mass ratio of boron powder to hydrochloric acid solution was 1:8. The reaction temperature was controlled at 60℃ and the reaction was carried out for 1 hour to remove metal impurities such as iron, aluminum, and magnesium. After washing and drying, it was ready for use.

[0022] Weigh 1.19 kg (110 mol) of 99.5% high-purity boron powder and place it in a fluidized bed reactor. Then, evacuate the reactor to -0.08 MPa and introduce helium gas to replace the evacuation system. Introduce 10 kg (96 mol) of high-purity silicon tetrafluoride gas with an abundance of 98.7% and a purity of 99.95% rich in silicon-28 into the fluidized bed reactor to react with the boron powder. Control the reaction temperature at 420℃ and the reaction pressure at -0.05 kPa.

[0023] After the reaction, crude silicon-28 isotope was obtained, which was then transferred to a zone furnace and evacuated to 10 °C. -3 Pa was charged with an H2 / Ar mixture (H2 flow rate 2 L / min, Ar flow rate 18 L / min) and melted at 1420 °C to remove impurities, yielding 2.13 kg of silicon-28 isotope product with a purity of 99.92% and an abundance of 98.7%. The mass spectrum is shown below. Figure 2 As shown. The generated boron trifluoride gas enters a distillation column, with the distillation temperature controlled at -30℃ and the distillation pressure at 1.5 MPa. Liquid silicon tetrafluoride is discharged from the bottom of the distillation column and recycled. 7.32 kg of 99.95% pure boron trifluoride gas is discharged from the top of the distillation column and used to prepare boron-10 and boron-11 isotopes using the method described in patent application CN118681406A. The boron-10 isotope abundance is 99.5%, and the mass spectrum is shown below. Figure 3 The purity shown is 99.91%; the boron-11 isotope abundance is 99.7%, and the mass spectrum is as follows. Figure 4 As shown, the purity is 99.99%.

[0024] Example 2 A method for preparing silicon isotopes and boron isotopes, the method specifically comprising the following steps: Boron powder was dissolved in 10wt% hydrochloric acid for soaking reaction. The mass ratio of boron powder to hydrochloric acid solution was 1:7. The reaction temperature was controlled at 50℃ and the reaction was carried out for 1.5h to remove metal impurities such as iron, aluminum, and magnesium. After washing and drying, it was ready for use.

[0025] Weigh 1.64 kg of high-purity boron powder (99.6% purity) and place it in a high-temperature tube furnace. Then, evacuate the furnace to -0.088 MPa and introduce an argon gas replacement system. Introduce 15 kg of high-purity silicon tetrafluoride gas (98.9% abundance, 99.99% purity) rich in silicon-28 into the high-temperature tube furnace to react with the boron powder. Control the reaction temperature at 600℃ and the reaction pressure at -0.01 kPa.

[0026] After the reaction, crude silicon-28 isotope was obtained, which was then transferred to a zone furnace and evacuated to 10 °C. -4A mixture of H2 / Ar (H2 flow rate 4 L / min, Ar flow rate 16 L / min) was introduced and melt-purified at 1500℃ to obtain 3.01 kg of silicon-28 isotope product with a purity of 99.98% and an abundance of 98.9%. The generated boron trifluoride gas entered a distillation column, with the distillation temperature controlled at -38℃ and the distillation pressure at 1.2 MPa. Liquid silicon tetrafluoride was discharged from the bottom of the distillation column and recycled. 10.14 kg of boron trifluoride gas (99.98% purity) was discharged from the top of the distillation column and used to prepare boron-10 and boron-11 isotopes using the method described in patent application CN118681406A. The boron-10 isotope abundance was 98.9% and the purity was 99.95%; the boron-11 isotope abundance was 99.9% and the purity was 99.99%.

[0027] Example 3 A method for preparing silicon isotopes and boron isotopes, the method specifically comprising the following steps: Boron powder was dissolved in 15wt% hydrochloric acid for soaking reaction. The mass ratio of boron powder to hydrochloric acid solution was 1:6. The reaction temperature was controlled at 40℃ and the reaction was carried out for 2 hours to remove metal impurities such as iron, aluminum, and magnesium. After washing and drying, it was ready for use.

[0028] The microchannel reactor was evacuated to -0.09 MPa, and an argon gas replacement system was introduced. Then, high-purity boron powder (99.8% purity) was introduced into the microchannel reactor using argon gas as a carrier. At the same time, high-purity silicon tetrafluoride gas with an abundance of 98.4% and a purity of 99.97% and rich in silicon-28 was also introduced into the microchannel reactor. 2.08 kg of high-purity boron powder and 20 kg of high-purity silicon tetrafluoride gas were introduced, and the two underwent a reduction reaction. The reaction temperature was controlled at 700℃ and the reaction pressure at -0.015 kPa.

[0029] After the reaction, crude silicon-28 isotope was obtained, which was then transferred to a zone furnace and evacuated to 10 °C. -3 A mixture of H2 / Ar (H2 flow rate 3 L / min, Ar flow rate 17 L / min) was introduced and melt-purified at 1550 °C to obtain 3.77 kg of silicon-28 isotope product with a purity of 99.97% and an abundance of 98.4%. The generated boron trifluoride gas entered a distillation column, with the distillation temperature controlled at -45 °C and the distillation pressure at 1 MPa. Liquid silicon tetrafluoride was discharged from the bottom of the distillation column and recycled. 12.82 kg of boron trifluoride gas (99.97% purity) was discharged from the top of the distillation column and used to prepare boron-10 and boron-11 isotopes using the method described in patent application CN118681406A. The boron-10 isotope abundance was 98.6% and the purity was 99.92%; the boron-11 isotope abundance was 99.6% and the purity was 99.98%.

[0030] This invention is also applicable to the preparation of silicon-29 and silicon-30 isotopes.

[0031] Note: Isotope abundance was detected by mass spectrometry, and the vertical axis in the figure indicates the detection intensity; purity is obtained by subtraction after detecting impurities.

[0032] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the specific implementation of the present invention and not to limit it. Those skilled in the art should understand that any equivalent substitutions or obvious modifications made to the implementation of the present invention without changing its performance or use, without departing from the spirit of the present invention, should be covered within the scope of protection claimed by the present invention.

Claims

1. A method for producing silicon isotopes and boron isotopes, characterized by, The process is as follows: (1) high-purity boron powder is obtained by pretreatment process purification of boron powder; (2) the reactor is vacuumed to-0.08MPa~ -0.09MPa, then inert gas is introduced to replace the air in the reactor, and high-purity boron powder and high-purity silicon tetrafluoride gas enriched in silicon-28 are subjected to reduction reaction in the reactor to obtain crude silicon-28 isotope product; (3) the crude silicon-28 isotope product of step (2) is subjected to plasma zone refining to obtain silicon-28 isotope product, the generated boron trifluoride gas is subjected to low-temperature rectification process to remove excess silicon tetrafluoride, and then is used for preparation of boron-10 and boron-11 isotopes, and the excess silicon tetrafluoride is returned to the system for recycling.

2. The method for producing silicon isotopes and boron isotopes according to claim 1, characterized by, In step (1), the boron powder pretreatment and purification process is: the boron powder is dissolved in hydrochloric acid and soaked at 40~60℃ for 1~2h, the concentration of the hydrochloric acid is 5~15wt%, and the mass ratio of boron powder to hydrochloric acid solution is 1:(6~8).

3. The method for preparing silicon isotopes and boron isotopes according to claim 1, characterized in that, In step (2), the silicon tetrafluoride gas enriched in silicon-28 has a silicon-28 abundance of ≥98.5% and a gas purity of ≥99.9%.

4. The method of claim 1, wherein the silicon isotope and boron isotope are produced by the method of claim 1, wherein the method further comprises: In step (2), the control conditions of the reduction reaction are: the molar ratio of SiF4:B is (3.5~4):4; the reaction temperature is 400~700℃; and the reaction pressure is-0.05~-0.15KPa. ​ 5. The method of claim 1, wherein the silicon isotope and boron isotope are produced by the method of claim 1, wherein the method further comprises: In step (3), the control conditions of the low-temperature rectification process are: the rectification temperature is-48℃~-30℃, and the rectification pressure is 1~1.5MPa. ​ 6. The method of claim 1, wherein the silicon isotope and boron isotope are produced by the method of claim 1, wherein the method further comprises: In step (3), the control conditions of the plasma zone melting are as follows: hydrogen-argon mixed system, temperature 1420-1550℃, pressure 10 -3 ~10 -5 Pa. ​ 7. The method of claim 6, wherein the silicon isotope and boron isotope are produced by, The volume ratio of hydrogen to argon in the hydrogen-argon mixed system is 1:(4~9), and the hydrogen flow rate is 2~4 L / min.

8. The method of claim 1, wherein the silicon isotope and boron isotope are produced by the method of claim 1, wherein the method further comprises: In step (2), the reactor is a fluidized bed, a high-temperature tubular furnace or a microreaction device. ​

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