Low temperature rectification separation process for high abundance boron-10 halides

Abstract

The present application relates to a kind of low-temperature rectification separation methods of high-abundance boron halide-10 in the field of chemical synthesis and separation, comprising: S1, boron halide gas is pumped into dry device and is dry handled;S2, the boron halide gas that is handled by step S1 dry is pumped into rectification pipe body from the bottom of low-temperature rectification tower, rectification tank body is filled with liquid nitrogen, and multiple trays are arranged in rectification tank body, and the filler in the tray is graphene aerogel, and the boron halide pumped from the bottom of rectification tank body rises to the top of tower after sequentially passing through graphene aerogel in each layer of tray from bottom to top;S3, multiple low-temperature rectification towers are sequentially connected to form multistage low-temperature rectification tower, and the abundance of boron halide-10 in the boron halide gas output from the top of last-stage rectification tower is greater than or equal to 99%.The present application solves the technical problems such as corrosion and blockage caused by cracking in the chemical exchange rectification method of boron fluoride-methyl ether complex.

Description

Technical Field

[0001] This invention relates to the field of chemical synthesis and separation technology, specifically to a low-temperature distillation separation method for high-abundance boron halide-10. Background Technology

[0002] Boron (B) has two stable isotopes: 10B and 11B, with abundances of approximately 19.8% and 80.2% in nature, respectively. Boron 10 (10B) has a very strong neutron absorption capacity, especially for thermal neutrons, and is therefore widely used in nuclear power, military equipment, modern industry, and medicine.

[0003] The industrial production of boron-10 isotopes is extremely difficult, and currently only a few countries can industrially produce them. These countries maintain strict secrecy regarding their boron-10 production technology and rigorously control the export of boron-10 products. There are many methods for enriching boron-10 isotopes, but three main methods have been successfully implemented for industrial production: the boron fluoride-diethyl ether complex chemical exchange distillation method, the boron trifluoride-methyl ether complex chemical exchange distillation method, and the boron trifluoride-anisole complex chemical exchange distillation method. Among these, the boron trifluoride-diethyl ether complex chemical exchange distillation method has been largely superseded by the boron trifluoride-methyl ether complex chemical exchange distillation method and the boron trifluoride-anisole complex chemical exchange distillation method.

[0004] Currently, the chemical exchange distillation method for boron trifluoride-methyl ether complexes is the main method for enriching and producing boron-10 isotopes. For example, Chinese invention patent CN109942005A discloses an industrial production method for boron-10 isotopes. Methyl ether is pressurized to become a liquid, and the liquid methyl ether is adsorbed using a molecular sieve. Boron trifluoride gas is distilled in a low-temperature distillation column and exits from the top. Methyl ether and boron trifluoride undergo a complexation reaction in a complexation reactor. The resulting complex enters an exchange reaction distillation column. The complex is heated in a reboiler, and decomposes at a certain temperature. All the vapor condenses back into a liquid, reforming the boron trifluoride-methyl ether complex. The refluxed liquid and vapor undergo a chemical exchange reaction, causing boron trifluoride-10 to successively enter the liquid phase from the gas phase. As the downward-flowing liquid enters the column bottom, the boron trifluoride-11 complex also continuously undergoes an exchange reaction, changing from the liquid phase to the gas phase and rising to the top of the column. Although small quantities of boron-10 isotope products can be produced intermittently, the separation coefficient of the boron fluoride methyl ether complex is large, and there is a problem of it decomposing into boron fluoride and methyl ether. The decomposed boron fluoride reacts with water to form highly corrosive hydrofluoric acid, posing serious corrosiveness and safety issues such as pipeline blockage. The approach taken by those skilled in the art to solve this technical problem is to add a complex drying process to avoid the presence of moisture during distillation, but it is difficult to achieve an ideal state. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the purpose of this invention is to provide a low-temperature distillation separation method for high-abundance boron halide-10.

[0006] A low-temperature distillation separation method for high-abundance boron halide-10 provided by the present invention includes:

[0007] S1, the boron halide gas is pumped into the drying device for drying;

[0008] S2, the boron halide gas dried in step S1 is pumped from the bottom of the low-temperature distillation column into the distillation tank. The distillation tank is fitted inside the low-temperature distillation column. Liquid nitrogen is filled outside the distillation tank to maintain the temperature of the distillation tank. The distillation tank is equipped with multiple layers of trays. The packing material in the trays is graphene aerogel. The boron halide pumped from the bottom of the distillation tank passes through the graphene aerogel in each tray from bottom to top and rises to the top of the column.

[0009] S3 is a multi-stage cryogenic distillation column formed by connecting multiple sets of cryogenic distillation columns in sequence. The boron halide gas output from the top of the first-stage distillation column is separated by cryogenic distillation in the second-stage to the last-stage distillation column. The abundance of boron halide-10 in the boron halide gas output from the top of the last-stage distillation column is greater than or equal to 99%.

[0010] In some embodiments, the thickness of the graphene aerogel filling each layer of the tray is 0.5-1 mm.

[0011] In some embodiments, the number of trays in the distillation column is 3000-5000.

[0012] In some embodiments, the spacing between the trays in the cryogenic distillation column is 2-10 mm.

[0013] In some embodiments, the multi-stage distillation is formed by connecting 3-10 distillation columns in series.

[0014] In some embodiments, the multi-stage cryogenic distillation consists of a four-stage cryogenic distillation system composed of four sets of cryogenic distillation columns connected together.

[0015] In some embodiments, the abundance of boron halide-10 in the boron halide gas output from the top of the first-stage cryogenic distillation column is 45%-50%, the abundance of boron halide-10 in the boron halide gas output from the top of the second-stage cryogenic distillation column is 63%-67%, the abundance of boron halide-10 in the boron halide gas output from the top of the third-stage cryogenic distillation column is 85%-90%, and the abundance of boron halide-10 in the boron halide gas output from the top of the fourth-stage cryogenic distillation column is greater than or equal to 99%.

[0016] In some embodiments, the boron halide is boron fluoride or boron chloride.

[0017] In some embodiments, in step S1, the water vapor content of the dried boron halide gas is less than 0.01%-0.02%.

[0018] In some embodiments, the boron halide is boron fluoride or boron chloride.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] This invention uses graphene aerogel as a condenser, making full use of the porous, large specific surface area, and ultrathin characteristics of graphene aerogel. This results in an exponential increase in the contact area and number of contacts between boron halide gas and the graphene aerogel as the condenser, overcoming the deficiency of low gas-liquid exchange coefficient between boron halide gas and condenser alone. It effectively solves the problems of corrosion and blockage caused by cracking in the chemical exchange distillation method of boron fluoride-methyl ether complex. Moreover, the process is simple, easy to operate, low in cost, and highly safe. Attached Figure Description

[0021] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0022] Figure 1 This is a flowchart of the low-temperature distillation separation method for high-abundance boron fluoride-10 of the present invention;

[0023] Figure 2 This is a cross-sectional structural diagram of the distillation tank of the low-temperature distillation column of the present invention. Detailed Implementation

[0024] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0025] This invention provides a low-temperature distillation separation method for high-abundance boron fluoride-10, such as... Figure 1-2 As shown, it includes the following steps:

[0026] S1, pure boron fluoride gas is first pumped into a drying device for drying to remove trace amounts of moisture from the boron fluoride, so that the water vapor content in the boron fluoride gas is less than 0.01%-0.02%.

[0027] In step S2, the boron fluoride gas, after being dried in step S1, is introduced into the distillation tank within the cryogenic distillation column via a high-pressure pump. The boron fluoride gas enters from the bottom of the distillation tank and flows upwards under the continuous pressure of the pump. The distillation tank is fitted inside the column, and a cavity is provided between the outer wall of the tank and the insulation layer of the column. This cavity is filled with liquid nitrogen, which maintains the temperature inside the tank at approximately -100°C, providing the required temperature for the distillation of the boron fluoride gas. Multiple trays are installed within the distillation tank, stacked at intervals. The packing material within the trays is graphene aerogel. Graphene aerogel is a porous material with a high specific surface area; compared to conventional packing materials in existing trays, its specific surface area is increased by approximately 10 times, significantly improving the contact area with the boron fluoride gas. Due to the inherent properties of graphene aerogel, the trays can be made very thin, with each tray being 1-2 mm thick and the graphene aerogel filling the tray being 0.5-1 mm thick. The number of trays in a cryogenic distillation column can reach 3000-5000, with a spacing of 2-10 mm between adjacent trays. Compared to the 200-300 trays in existing technologies, the number of trays has an exponential change, greatly increasing the number of contact times between boron fluoride gas and graphene aerogel.

[0028] Under high pressure, gaseous boron fluoride moves from the bottom to the top of the distillation tank. As the boron fluoride gas rises, it passes through a layer of graphene aerogel in the tray. When it comes into contact with the graphene aerogel, the temperature of the boron fluoride gas is higher than that of the graphene aerogel, causing some of the gaseous boron fluoride to condense into liquid. Since boron fluoride-10 is the light component and boron fluoride-11 is the heavy component in the boron fluoride gas, the abundance of boron fluoride-11 increases in the condensed boron fluoride liquid, while the abundance of boron fluoride-10 increases in the uncondensed boron fluoride gas.

[0029] S3 consists of four sets of cryogenic distillation columns forming a four-stage cryogenic distillation process. From beginning to end, the four sets of columns are: a first-stage cryogenic distillation column, a second-stage cryogenic distillation column, a third-stage cryogenic distillation column, and a final-stage cryogenic distillation column. The final-stage cryogenic distillation column is the fourth-stage cryogenic distillation column. The setup and distillation procedure for all four stages remain essentially the same. After boron fluoride gas rises from the bottom to the top of the distillation tank within each stage, the abundance of boron fluoride-10 increases accordingly. The basic rules are as follows: the abundance of boron fluoride-10 in the boron fluoride gas output from the top of the first-stage cryogenic distillation column is 45%-50%; the abundance of boron fluoride-10 in the boron fluoride gas output from the top of the second-stage cryogenic distillation column is 63%-67%; the abundance of boron fluoride-10 in the boron fluoride gas output from the top of the third-stage cryogenic distillation column is 85%-90%; and the abundance of boron fluoride-10 in the boron fluoride gas output from the top of the fourth-stage cryogenic distillation column is greater than or equal to 99%.

[0030] This invention uses graphene aerogel as a condenser, fully utilizing its porous, large specific surface area, and ultrathin properties to exponentially increase the contact area and number of contacts between boron fluoride gas and the condenser. This overcomes the low gas-liquid exchange coefficient of boron fluoride gas alone with the condenser, effectively solving the technical problems of corrosion and blockage caused by cracking in the chemical exchange distillation method of boron fluoride-methyl ether complex. Furthermore, the process is simple, easy to operate, low in cost, and highly safe. In addition, using liquid nitrogen for condensation further reduces production costs.

[0031] In the description of this application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0032] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A low-temperature distillation separation method for high-abundance boron halide-10, characterized in that, include: S1, the boron halide gas is pumped into the drying device for drying; S2, the boron halide gas dried in step S1 is pumped from the bottom of the low-temperature distillation column into the distillation tank. The distillation tank is fitted inside the low-temperature distillation column. Liquid nitrogen is filled outside the distillation tank to maintain the temperature of the distillation tank. The distillation tank is equipped with multiple layers of trays. The packing material in the trays is graphene aerogel. The boron halide pumped from the bottom of the distillation tank passes through the graphene aerogel in each tray from bottom to top and rises to the top of the column. S3 is a multi-stage cryogenic distillation column formed by connecting multiple sets of cryogenic distillation columns in sequence. The boron halide gas output from the top of the first-stage distillation column is separated by cryogenic distillation in the second-stage to the last-stage distillation column. The abundance of boron halide-10 in the boron halide gas output from the top of the last-stage distillation column is greater than or equal to 99%.

2. The low-temperature distillation separation method for high-abundance boron halide-10 according to claim 1, characterized in that, The thickness of the graphene aerogel filling each of the trays is 0.5-1 mm.

3. The low-temperature distillation separation method for high-abundance boron halide-10 according to claim 2, characterized in that, The distillation column has 3,000-5,000 trays.

4. The low-temperature distillation separation method for high-abundance boron halide-10 according to claim 3, characterized in that, The spacing between the trays in the cryogenic distillation column is 2-10 mm.

5. The low-temperature distillation separation method for high-abundance boron halide-10 according to claim 1, characterized in that, The multi-stage cryogenic distillation column is formed by connecting 3-10 distillation columns in series.

6. The low-temperature distillation separation method for high-abundance boron halide-10 according to claim 5, characterized in that, The multi-stage cryogenic distillation column consists of four sets of cryogenic distillation columns connected together to form a four-stage cryogenic distillation system.

7. The low-temperature distillation separation method for high-abundance boron halide-10 according to claim 6, characterized in that, The abundance of boron halide-10 in the boron halide gas output from the top of the first-stage cryogenic distillation column is 45%-50%, the abundance of boron halide-10 in the boron halide gas output from the top of the second-stage cryogenic distillation column is 63%-67%, the abundance of boron halide-10 in the boron halide gas output from the top of the third-stage cryogenic distillation column is 85%-90%, and the abundance of boron halide-10 in the boron halide gas output from the top of the fourth-stage cryogenic distillation column is greater than or equal to 99%.

8. The low-temperature distillation separation method for high-abundance boron halide-10 according to claim 1, characterized in that, In step S1, the water vapor content of the dried boron halide gas is less than 0.01%-0.02%.

9. The low-temperature distillation separation method for high-abundance boron halide-10 according to any one of claims 1-8, characterized in that, The boron halide is either boron fluoride or boron chloride.

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