Method for purifying diborane and purification system thereof

Abstract

The present application provides a method for purifying diborane and a system for purifying diborane. The method comprises first adsorption, first distillation, second distillation, second adsorption and third adsorption to remove metal elements and impurity gases, especially impurity gases with a boiling point close to that of diborane. The process parameters, such as pressure and temperature, during the purification process are controlled. The setting of the above process parameters can significantly enhance the purification effect and improve the separation efficiency of impurities, and purified diborane with a required purity is obtained.

Description

Technical Field

[0001] This invention belongs to the field of specialty gas production, and specifically relates to a method for purifying and preparing diborane and its purification system. Background Technology

[0002] Diborane, with the molecular formula B₂H₆, is primarily used in the electronics industry as a gaseous impurity source, ion implantation agent, and dopant for boron doping oxidation diffusion. Diborane is typically diluted with gases such as N₂, Ar, He, and H₂ to form a mixed gas for use in semiconductor chip manufacturing. The gases used in chip processing often require a purity level of 5N or higher, and metal elements must be purified to 10⁻⁶. -9 Level 10 -12 As downstream users increase their requirements for the quality and craftsmanship of electronic products, the industry will inevitably pursue higher levels of gas preparation technology.

[0003] The key to obtaining purified diborane gas lies in removing gaseous impurities with similar boiling points and sizes to diborane, as well as metal element impurities. Patent application CN101955156 A only addresses the removal of impurities with similar boiling points to diborane; it does not solve the problem of metal element impurities in high-purity gas. Patent CN210795761 U discloses a purification apparatus for diborane, suitable only for small-scale purification and far from true industrial production.

[0004] Therefore, it is particularly important to further improve the purification and preparation method of diborane. Summary of the Invention

[0005] To overcome the shortcomings of the prior art, the present invention provides a method for purifying and preparing diborane, so as to solve the problem of the influence of gaseous impurities and metal element impurities on the gas purity of diborane.

[0006] The first aspect of this invention provides a method for purifying and preparing diborane, comprising the following steps:

[0007] S1) The crude diborane is subjected to a first adsorption process to remove entrained water, CO2, and O2, yielding the first intermediate product.

[0008] S2) The first intermediate product is subjected to a first distillation to remove non-condensable gases H2, N2, O2, Ar, CO, and CH4 to obtain the second intermediate product;

[0009] S3) The second intermediate product is subjected to a second distillation to remove the high-boiling-point component B4H. 10 B5H9, B5H 11The third intermediate product is obtained, wherein the pressure of the second distillation is greater than that of the first distillation, the reflux temperature of the second distillation is greater than that of the first distillation, and the high-boiling-point component refers to the component with a boiling point greater than that of diborane (-92℃).

[0010] S4) The third intermediate is subjected to a second adsorption to remove metal elements (such as Fe, Mn, etc.) to obtain the fourth intermediate.

[0011] S5) The fourth intermediate product is subjected to a third adsorption to remove CO2 and C2H6 components with boiling points similar to those of diborane, to obtain purified diborane. The pressure of the third adsorption is lower than that of the second adsorption. The components with boiling points similar to those of diborane refer to components whose boiling points differ from those of diborane by ±15℃.

[0012] In the purification and preparation method of this invention, crude diborane is subjected to a first adsorption, a first distillation, a second distillation, a second adsorption, and a third adsorption to remove metal elements and impurity gases, especially those with boiling points close to that of diborane. Furthermore, the pressure of the second distillation is controlled to be higher than that of the first distillation, the reflux temperature of the second distillation is higher than that of the first distillation, and the pressure of the third adsorption is lower than that of the second adsorption. Through the ingenious arrangement of the above-mentioned processing steps and the ingenious setting of the above-mentioned process parameters, the purification effect can be significantly improved and the separation efficiency of impurities can be increased, resulting in diborane with higher purity.

[0013] Furthermore, the pressure difference between the first and second distillations is 1-8 bar.

[0014] Furthermore, the pressure for the first distillation is 1-3.5 bar; the pressure for the second distillation is 3-9 bar.

[0015] Furthermore, the first distillation is a total reflux process, which can effectively remove non-condensable gases; the second distillation has a reflux ratio of 2-40, and selecting an appropriate reflux ratio can effectively remove high-boiling-point components while saving energy.

[0016] Furthermore, the reflux temperature of the first distillation is ≤-65℃, and the reflux temperature of the second distillation is ≤-45℃.

[0017] Furthermore, the pressure of the first adsorption is 0.5-3 bar, and the adsorption temperature of the first adsorption is ≤-65℃.

[0018] Furthermore, the pressure of the second adsorption is the same as the pressure of the second distillation, and the pressure of the third adsorption is 1-8 bar different from the pressure of the second adsorption.

[0019] Furthermore, the adsorption temperature for the second adsorption is ≤-45℃, and the adsorption temperature for the third adsorption is ≤-20℃.

[0020] A second aspect of the present invention provides a purification system for carrying out the above-described method for purifying and preparing diborane, comprising:

[0021] The first adsorption tower is used to perform the first adsorption on the crude diborane to remove water, CO2 and O2 entrained therein, and obtain the first intermediate product.

[0022] A first distillation column connected to the first adsorption column is used to perform a first distillation on the first intermediate product to remove non-condensable gases, such as one or more of H2, N2, O2, Ar, CO, CH4, etc., to obtain a second intermediate product.

[0023] A second distillation column, connected to the first distillation column, is used to perform a second distillation of the second intermediate product to remove high-boiling-point components, such as B4H. 10 B5H9, B5H 11 One or more of these, etc., are used to obtain a third intermediate product;

[0024] The second adsorption column, which is connected to the second distillation column, is used to adsorb the third intermediate product for the second time to remove metal elements, such as one or more of Fe and Mn, to obtain the fourth intermediate product.

[0025] A third adsorption tower connected to the second adsorption tower is used to perform a third adsorption on the fourth intermediate product to remove components with similar boiling points to diborane, such as one or more of CO2, C2H6, etc., to obtain purified diborane.

[0026] Furthermore, a first condenser is provided at the top of the first distillation column, and the first adsorption column is connected to the first distillation column through a first pipeline. A pressurization device is provided on the first pipeline. The first adsorption column is filled with an adsorbent, which is activated carbon or molecular sieve.

[0027] The second distillation column is equipped with a second condenser at the top. The first distillation column and the second distillation column are connected by a second pipeline, which is equipped with a pressurization device.

[0028] Preferably, the second adsorption tower is filled with a resin adsorbent, and the pressure of the second adsorption tower is the same as the pressure of the second distillation tower. The resin adsorbent is a chelating adsorption resin and / or an ion exchange resin.

[0029] More preferably, the resin adsorbent is a combination of chelating adsorption resin and ion exchange resin, and the volume ratio of chelating adsorption resin to ion exchange resin is 1:10-10:1.

[0030] Preferably, the second adsorption tower and the third adsorption tower are connected by a third pipeline, which is equipped with a heat exchanger and a pressure reducing device. The third adsorption tower is filled with molecular sieve adsorbent.

[0031] The technical solution provided by this invention has the following beneficial effects:

[0032] The preparation method provided by this invention is easy to operate and can be easily industrialized, overcoming the shortcomings of existing technologies, which are only suitable for purifying gaseous impurities and cannot be industrialized. Through a superior processing flow, this invention significantly improves the removal of metal elements and impurity gases, especially those with boiling points close to diborane, increasing work efficiency and product purity, achieving a diborane purity of 5N, and saving energy and reducing costs. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the borane purification system of the present invention.

[0034] Wherein, C01 is the first adsorption tower, T01 is the first distillation tower, T02 is the second distillation tower, C02 is the second adsorption tower (liquid phase adsorption tower), C03 is the third adsorption tower (gas phase adsorption tower), G1 is the first pipeline, G2 is the second pipeline, and G3 is the third pipeline. Detailed Implementation

[0035] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and do not imply that the invention is limited thereto. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0036] In the diborane purification system provided by this invention, see [link to relevant documentation]. Figure 1 It mainly includes: the first adsorption tower CO1, the first distillation tower T01, the second distillation tower T02, the second adsorption tower CO2 and the third adsorption tower CO3.

[0037] The first adsorption tower CO1 is used for the first adsorption of crude diborane, which can be stored in a crude product tank (not shown in the figure). The first adsorption tower CO1 is filled with an adsorbent, which is activated carbon or molecular sieve. For example, in some embodiments, the adsorbent in the first adsorption tower CO1 is 3A molecular sieve. In the first adsorption tower CO1, the crude diborane is subjected to the first adsorption to remove water, CO2, and O2, and a first intermediate product is obtained.

[0038] A first condenser is installed at the top of the first distillation column. The first distillation column T01 is connected to the first adsorption column CO1 via a first pipeline G1. A pressurization device is installed on the first pipeline G1 to increase the pressure of the first intermediate product, thereby adjusting the pressure of the first intermediate product to be suitable for entering the first distillation column T01. A first reboiler (not shown in the figure) is installed at the bottom of the first distillation column T01. The material outlet and material inlet of the first condenser are both connected to the top of the first distillation column T01. The packing in the first distillation column T01 is preferably wire mesh packing, preferably with a mesh size of 20-200 mesh. In the first distillation column T01, the first intermediate product undergoes a first distillation, which is a total reflux distillation. The first condenser is connected to a vacuum device to remove non-condensable gases, such as H2, N2, O2, Ar, CO, and CH4, from the first condenser, thereby obtaining the second intermediate product.

[0039] A second condenser is installed at the top of the second distillation column T02. Both the material outlet and inlet of the second condenser are connected to the top of the second distillation column T02. The second distillation column T02 is connected to the first distillation column T01 via a second pipeline G2. A pressurization device is installed on the second pipeline G2 to increase the pressure of the second intermediate product, thereby adjusting the pressure of the second intermediate product to suit its entry into the second distillation column T02. A second reboiler (not shown in the figure) is installed at the bottom of the second distillation column T02. The bottom outlet of the first distillation column T01 is connected to the lower part of the second distillation column T02, preferably powered by a pump. The packing material in the second distillation column T02 is preferably wire mesh packing, with a mesh size of 20-200. The bottom of the second distillation column T02 is connected to a residue tank. In the second distillation column T02, the second intermediate product undergoes a second distillation with a reflux ratio of 2-40 to remove high-boiling-point components, such as B4H. 10 B5H9, B5H 11 The third intermediate product is obtained by distilling, wherein the pressure of the second distillation is greater than that of the first distillation, and the reflux temperature of the second distillation is greater than that of the first distillation.

[0040] The second adsorption tower CO2 is connected to the second distillation tower T02. The second adsorption tower CO2 is a liquid-phase adsorption tower. The top product of the second distillation tower T02 (i.e., the third intermediate product) is collected and enters the second adsorption tower CO2. The second adsorption tower CO2 is filled with a resin adsorbent. The pressure of the second adsorption tower CO2 is the same as that of the second distillation tower T02. The resin adsorbent is a chelating adsorption resin and / or an ion exchange resin. Preferably, the resin adsorbent is a combination of chelating adsorption resin and ion exchange resin, and the volume ratio of chelating adsorption resin to ion exchange resin is 1:10-10:1. In the second adsorption tower CO2, the third intermediate product undergoes a second adsorption to remove metal elements, such as Fe and Mn, to obtain the fourth intermediate product.

[0041] The third adsorption tower CO3 is connected to the second adsorption tower CO2 via a third pipeline G3. The third adsorption tower CO3 is a gas-phase adsorption tower. A heat exchanger and a pressure reducing device are installed on the third pipeline G3. The pressure reducing device is used to bring the material to the pressure required for the third adsorption. The third adsorption tower CO3 contains a molecular sieve adsorbent. In some embodiments, the third adsorption tower CO3 uses a 4A molecular sieve, preferably a 4A zeolite molecular sieve. In the third adsorption tower, the fourth intermediate product undergoes a third adsorption to remove components with similar boiling points to diborane, such as CO2 and C2H6, to obtain purified diborane. The pressure of the third adsorption is lower than that of the second adsorption.

[0042] Specifically, a product tank may also be provided, which is connected to the third adsorption tower CO3, for receiving purified diborane.

[0043] There are no special requirements regarding the source of the crude diborane used in this invention. The crude diborane used in the following examples has a purity of 99.8% and is commercially available; the fillers and adsorbents used are also commercially available.

[0044] Chelating resins can be classified according to the source of their polymer matrix: cross-linked polystyrene, polyacrylic acid, and polyvinyl alcohol. Preferably, this application uses cross-linked polystyrene chelating resin.

[0045] Ion exchange resins are classified into anion exchange resins and cation exchange resins. Preferably, this application uses anion exchange resin.

[0046] Example 1

[0047] The crude diborane feedstock of 500 kg / h is pressurized to 2 bar by a pump and enters the first adsorption tower CO1, which is equipped with 3A molecular sieve, from the middle and upper part of the first adsorption tower CO1. The temperature of the first adsorption tower CO1 is -65℃. After the first adsorption, water, CO2, O2 and other substances in the crude diborane are removed, and the first intermediate product (i.e. crude diborane after the first adsorption) is obtained. The first intermediate product is pumped from the outlet of the first adsorption tower CO1 into the first distillation tower T01.

[0048] The first distillation column T01 has a reflux temperature of -77℃ and a column pressure of 2.8 bar. It is packed with 100-mesh wire mesh packing. Through the first distillation in the first distillation column T01, non-condensable gases such as H2, N2, O2, Ar, CO, and CH4 in the first intermediate product are removed. The non-condensable gases are extracted from the top of the column by a vacuum pump with a top collection flow rate of 18.1 kg / h. All other condensate is refluxed to the bottom of the column, where the second intermediate product is obtained. The second intermediate product at the bottom of the column is pumped into the second distillation column T02.

[0049] The second distillation column T02 has a reflux temperature of -50℃ and a pressure of 5.8 bar. It is packed with 100-mesh wire mesh packing. The second intermediate product undergoes a second distillation in the second distillation column T02 with a reflux ratio of 20 to remove high-boiling-point impurities such as B4H. 10 B5H9, B5H 11 These high-boiling-point impurities are collected from the bottom of the column into a residual liquid tank with a flow rate of 23 kg / h. A third intermediate product, after the removal of the above-mentioned high-boiling-point impurities, is obtained from the top of the second distillation column T02. The third intermediate product is collected from the top of the column and enters the second adsorption column CO2 for a second adsorption.

[0050] The second adsorption tower CO2 contains chelating adsorption resin D401 and anion exchange resin in a 1:1 volume ratio. The third intermediate product is first adsorbed by the chelating adsorption resin in the second adsorption tower CO2, and then by the anion exchange resin to remove impurities such as metal elements. The third intermediate product after the second adsorption treatment is collected as the fourth intermediate product from the top of the second adsorption tower CO2. The temperature of the second adsorption tower CO2 is -50℃ and the pressure is 5.8 bar. The fourth intermediate product collected from the top of the second adsorption tower CO2 is depressurized and heated before entering the third adsorption tower CO3 for a third adsorption.

[0051] The third adsorption tower, CO3, operates at a temperature of -35°C and a pressure of 2.8 bar. CO3 is packed with 4A zeolite molecular sieves to remove impurities such as CO2 and C2H6. The CO3 output from the third adsorption tower yields purified diborane at a flow rate of approximately 458 kg / h.

[0052] The results of the purified diborane detection are shown in Table 1.

[0053] Table 1

[0054]

[0055]

[0056] Example 2

[0057] The crude diborane feedstock of 490 kg / h is pressurized to 1.9 bar by a pump and enters the first adsorption tower CO1, which is equipped with 3A molecular sieve, from the middle and upper part of the first adsorption tower CO1. The temperature of the first adsorption tower CO1 is -68℃. After the first adsorption, water, CO2, O2 and other substances in the crude diborane are removed, and the first intermediate product (i.e. crude diborane after the first adsorption) is obtained. The first intermediate product is pumped from the outlet of the first adsorption tower CO1 into the first distillation tower T01.

[0058] The first distillation column T01 has a reflux temperature of -79℃ and a column pressure of 2.6 bar. It is packed with 100-mesh wire mesh packing. Through the first distillation in the first distillation column T01, non-condensable gases such as H2, N2, O2, Ar, CO, and CH4 are removed from the first intermediate product. The non-condensable gases are extracted from the top of the column by a vacuum pump with a top outflow rate of 17.8 kg / h. All other condensate is refluxed to the bottom of the column, where the second intermediate product is obtained. The second intermediate product at the bottom of the column is pumped into the second distillation column T02.

[0059] The second distillation column T02 has a reflux temperature of -46℃ and a column pressure of 5.6 bar. It is packed with 100-mesh wire mesh packing. The second intermediate product undergoes a second distillation in the second distillation column T02 with a reflux ratio of 20 to remove high-boiling-point impurities such as B4H. 10 B5H9, B5H 11 These high-boiling-point impurities are collected from the bottom of the column into the residual liquid tank, which has a flow rate of 22.6 kg / h. The third intermediate product, after the removal of the above-mentioned high-boiling-point impurities, is obtained from the top of the second distillation column T02. The third intermediate product is collected from the top of the column and enters the second adsorption column CO2 for a second adsorption.

[0060] The second adsorption tower CO2 contains chelating adsorption resin D401 and anion exchange resin in a 1:1 volume ratio. The third intermediate product is first treated with the ion exchange resin in the second adsorption tower CO2, and then with the chelating adsorption resin to remove impurities such as metal elements. The third intermediate product after the second adsorption treatment is collected as the fourth intermediate product from the top of the second adsorption tower CO2. The temperature of the second adsorption tower CO2 is -46℃ and the pressure is 5.6 bar. The fourth intermediate product collected from the top of the second adsorption tower CO2 is depressurized and heated before entering the third adsorption tower CO3 for a third adsorption.

[0061] The third adsorption tower, CO3, operates at a temperature of -38℃ and a pressure of 2.6 bar. CO3 is packed with 4A zeolite molecular sieves to remove impurities such as CO2 and C2H6. The CO3 output from the third adsorption tower yields purified diborane at a flow rate of approximately 449.5 kg / h.

[0062] The results of the purified diborane detection are shown in Table 2.

[0063] Table 2

[0064]

[0065] Example 3

[0066] The crude diborane feedstock of 504 kg / h is pressurized to 2.1 bar by a pump and enters the first adsorption tower CO1, which is equipped with 3A molecular sieve, from the middle and upper part of the first adsorption tower CO1. The temperature of the first adsorption tower CO1 is -66℃. After the first adsorption, water, CO2, O2 and other substances in the crude diborane are removed, and the first intermediate product (i.e. crude diborane after the first adsorption) is obtained. The first intermediate product is pumped from the outlet of the first adsorption tower CO1 into the first distillation tower T01.

[0067] The first distillation column T01 has a reflux temperature of -75℃ and a column pressure of 2.9 bar. It is packed with 100-mesh wire mesh packing. Through the first distillation in the first distillation column T01, non-condensable gases such as H2, N2, O2, Ar, CO, and CH4 in the first intermediate product are removed. The non-condensable gases are extracted from the top of the column by a vacuum pump with a top collection flow rate of 18.4 kg / h. All other condensate is refluxed to the bottom of the column, where the second intermediate product is obtained. The second intermediate product at the bottom of the column is pumped into the second distillation column T02.

[0068] The second distillation column T02 has a reflux temperature of -45℃ and a pressure of 5.9 bar. It is packed with 100-mesh wire mesh packing. The second intermediate product undergoes a second distillation in the second distillation column T02 with a reflux ratio of 20 to remove high-boiling-point impurities such as B4H. 10 B5H9, B5H 11 These high-boiling-point impurities are collected from the bottom of the column into the residual liquid tank, which has a flow rate of 23.3 kg / h. The third intermediate product, after the removal of the above-mentioned high-boiling-point impurities, is obtained from the top of the second distillation column T02. The third intermediate product is collected from the top of the column and enters the second adsorption column CO2 for a second adsorption.

[0069] The second adsorption tower CO2 contains chelating adsorption resin D401 and anion exchange resin in a volume ratio of 1:3. The third intermediate product is first treated by the chelating adsorption resin in the second adsorption tower CO2, and then by the anion exchange resin to remove impurities such as metal elements. The third intermediate product after the second adsorption treatment is collected from the top of the second adsorption tower as the fourth intermediate product. The temperature of the second adsorption tower CO2 is -45℃ and the pressure is 5.9 bar. The fourth intermediate product collected from the top of the second adsorption tower CO2 is depressurized and heated before entering the third adsorption tower CO3 for a third adsorption.

[0070] The third adsorption tower, CO3, operates at a temperature of -30℃ and a pressure of 2.9 bar. CO3 is packed with 4A zeolite molecular sieves to remove impurities such as CO2 and C2H6. The CO3 output from the third adsorption tower yields purified diborane at a flow rate of approximately 463.3 kg / h.

[0071] The results of the purified diborane detection are shown in Table 3.

[0072] Table 3

[0073]

[0074]

[0075] Comparative Example 1

[0076] The crude diborane feedstock of 502 kg / h is pressurized to 2.1 bar by a pump and enters the first adsorption tower CO1, which is filled with activated carbon, from the middle and upper part of the first adsorption tower CO1. The temperature of the first adsorption tower CO1 is -62℃. After the first adsorption, water, CO2, O2 and other substances in the crude diborane are removed, and the first adsorption product is obtained. The first adsorption product is pumped from the outlet of the first adsorption tower CO1 to the first distillation tower T01.

[0077] The first distillation column T01 has a reflux temperature of -75℃ and a column pressure of 2.9 bar. It is packed with 100-mesh wire mesh packing. Through the first distillation in the first distillation column T01, non-condensable gases such as H2, N2, O2, Ar, CO, and CH4 in the first adsorption product are removed. The non-condensable gases are extracted from the top of the column by a vacuum pump at a flow rate of 18.4 kg / h. All other condensate is refluxed to the bottom of the column, where the first distillation product is obtained. The first distillation product at the bottom of the column is pumped into the second distillation column T02.

[0078] The second distillation column T02 has a reflux temperature of -45℃ and a pressure of 5.9 bar. It is packed with 100-mesh wire mesh packing. The product from the first distillation undergoes a second distillation in the second distillation column T02 with a reflux ratio of 20 to remove high-boiling-point impurities such as B4H. 10 B5H9, B5H 11 These high-boiling-point impurities are collected from the bottom of the column into the residual liquid tank, which has a flow rate of 23.3 kg / h. The second distillation product, after the removal of the high-boiling-point impurities, is obtained from the top of the second distillation column T02. The second distillation product is then collected from the top of the column and enters the second adsorption column CO2 for a second adsorption.

[0079] The second adsorption tower, CO2, contains chelating adsorption resin D401 and anion exchange resin in a 1:1 volume ratio. The product from the second distillation process is first treated with the ion exchange resin in the second adsorption tower CO2, and then with the chelating adsorption resin to remove impurities such as metal elements.

[0080] The second distillation product after the second adsorption treatment is collected from the top of the second adsorption tower CO2 as the second adsorption product. The temperature of the second adsorption tower CO2 is -45℃ and the pressure is 5.9 bar. The second adsorption product collected from the top of the second adsorption tower CO2 is depressurized and then discharged from the material outlet of the second adsorption tower CO2 to obtain the product diborane, with a flow rate of about 470 kg / h.

[0081] The purified diborane was tested and found to contain CO2 and C2H6 impurities ≥10ppm.

[0082] Comparative Example 2

[0083] The crude diborane feedstock of 488 kg / h is pressurized to 1.9 bar by a pump and enters the first adsorption tower CO1, which is equipped with 3A molecular sieve, from the middle and upper part of the first adsorption tower CO1. The temperature of the first adsorption tower CO1 is -68℃. After the first adsorption, water, CO2, O2 and other substances in the crude diborane are removed, and the first adsorption product is obtained. The first adsorption product is pumped from the outlet of the first adsorption tower CO1 to the first distillation tower T01.

[0084] The first distillation column T01 has a reflux temperature of -79℃ and a column pressure of 2.6 bar. It is packed with 100-mesh wire mesh packing. The first distillation in the first distillation column removes non-condensable gases such as H2, N2, O2, Ar, CO, and CH4 from the first adsorption product. The non-condensable gases are extracted from the top of the column by a vacuum pump at a flow rate of 17.8 kg / h. All other condensate is refluxed to the bottom of the column, where the first distillation product is obtained. The first distillation product at the bottom of the column is then pumped into the second distillation column T02.

[0085] The second distillation column T02 has a reflux temperature of -46℃ and a pressure of 5.6 bar. It is packed with 100-mesh wire mesh packing. The product from the first distillation undergoes a second distillation in the second column with a reflux ratio of 20 to remove high-boiling-point impurities such as B4H. 10 B5H9, B5H 11 These high-boiling-point impurities are collected from the bottom of the column into a residual liquid tank with a flow rate of 22.6 kg / h. The second distillation product, after the removal of the high-boiling-point impurities, is obtained from the top of the second distillation column. The second distillation product is collected from the top of the column, depressurized, and then enters the third adsorption column CO3 for a third adsorption.

[0086] The third adsorption tower, CO3, operates at a temperature of -30℃ and a pressure of 2.9 bar. CO3 is packed with 4A zeolite molecular sieves to remove impurities such as CO2 and C2H6. The product diborane is obtained from the CO3 outlet at a flow rate of approximately 445.5 kg / h.

[0087] The purified diborane test results showed that the content of metal element impurities such as Fe and Mn was ≥1ppm.

[0088] Comparative Example 3

[0089] The procedure was carried out in accordance with Example 1, except that the reflux temperature of the second distillation column TO2 was changed to -30°C, the pressure of the second absorption column CO2 was adjusted to 3 bar, and the pressure of the third absorption column CO3 was adjusted to 4 bar, while other parameters remained unchanged. The purified diborane was tested and found to contain CO2 and C2H6 impurities ≥50 ppm, and Fe, Mn, and other metallic element impurities ≥5 ppm.

[0090] Tests show that this invention, through a first adsorption, first distillation, second distillation, second adsorption, and third adsorption, and by precisely controlling the temperature and pressure in each adsorption and distillation process, can significantly increase the removal of metal elements and impurity gases, especially those with boiling points close to diborane. The resulting high-purity diborane has a purity of 5N, a total impurity content ≤10ppm, and a purity of up to 9N based on metal elements. In Comparative Example 1, because the diborane did not undergo a third adsorption, the content of components with boiling points close to diborane, such as CO2 and C2H6, increased in the test results. In Comparative Example 2, because the diborane did not undergo a second adsorption, the content of metal element impurities such as Fe and Mn increased in the test results. In Comparative Example 3, the pressure of the third absorption tower was greater than that of the second absorption tower, meaning the pressure of the third adsorption was greater than that of the second adsorption. Consequently, the content of components with boiling points close to diborane, such as CO2 and C2H6, increased significantly in the test results, as did the content of metal element impurities such as Fe and Mn.

[0091] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for purifying and preparing diborane, characterized in that, Includes the following steps: S1) The crude diborane product is subjected to a first adsorption to remove water, CO2 and O2 entrained therein, to obtain the first intermediate product; S2) The first intermediate product is subjected to a first distillation to remove non-condensable gases and obtain a second intermediate product. S3) The second intermediate product is subjected to a second distillation to remove high-boiling-point components, yielding a third intermediate product. The pressure of the second distillation is greater than that of the first distillation, and the pressure difference between the first and second distillations is 1-8 bar. The reflux temperature of the second distillation is greater than that of the first distillation, where the reflux temperature of the first distillation is ≤-65°C and the reflux temperature of the second distillation is ≤-45°C. S4) The third intermediate product is subjected to a second adsorption to remove the metal elements therein, and a fourth intermediate product is obtained. S5) The fourth intermediate product is subjected to a third adsorption to remove components with similar boiling points to diborane, thereby obtaining purified diborane. The pressure of the third adsorption is lower than that of the second adsorption, the pressure of the second adsorption is the same as that of the second distillation, and the difference between the pressure of the third adsorption and the pressure of the second adsorption is 1-8 bar.

2. The method for purifying and preparing diborane according to claim 1, characterized in that, The pressure of the first distillation is 1-3.5 bar; the pressure of the second distillation is 3-9 bar.

3. The method for purifying and preparing diborane according to any one of claims 1-2, characterized in that, The first distillation is a total reflux, and the reflux ratio of the second distillation is 2-40.

4. The method for purifying and preparing diborane according to any one of claims 1-2, characterized in that, The pressure of the first adsorption is 0.5-3 bar, and the adsorption temperature of the first adsorption is ≤-65℃.

5. The method for purifying and preparing diborane according to claim 1, characterized in that, The adsorption temperature for the second adsorption is ≤-45℃, and the adsorption temperature for the third adsorption is ≤-20℃.

6. The method for purifying and preparing diborane according to claim 1 or 2, characterized in that, A purification system is used, which includes: The first adsorption tower is used to perform the first adsorption on the crude diborane to remove water, CO2 and O2 entrained therein, and obtain the first intermediate product. A first distillation column connected to the first adsorption column is used to perform a first distillation on the first intermediate product to remove non-condensable gases and obtain a second intermediate product. A second distillation column connected to the first distillation column is used to perform a second distillation on the second intermediate product to remove high-boiling-point components and obtain a third intermediate product. A second adsorption column connected to the second distillation column is used to perform a second adsorption on the third intermediate product to remove the metal elements therein, thereby obtaining a fourth intermediate product. A third adsorption tower connected to the second adsorption tower is used to perform a third adsorption on the fourth intermediate product to remove components with boiling points close to that of diborane, so as to obtain purified diborane.

7. The method for purifying and preparing diborane according to claim 6, characterized in that, The first distillation column is equipped with a first condenser at the top. The first adsorption column is connected to the first distillation column through a first pipeline. A pressurization device is installed on the first pipeline. The first adsorption column is filled with an adsorbent, which is activated carbon or molecular sieve. The second distillation column is equipped with a second condenser at the top. The first distillation column and the second distillation column are connected by a second pipeline, and a pressurization device is installed on the second pipeline.

8. The method for purifying and preparing diborane according to claim 7, characterized in that, The second adsorption tower is filled with a resin adsorbent, wherein the resin adsorbent is a chelating adsorption resin and / or an ion exchange resin.

9. The method for purifying and preparing diborane according to claim 8, characterized in that, The resin adsorbent is a combination of chelating adsorption resin and ion exchange resin, and the volume ratio of the chelating adsorption resin to the ion exchange resin is 1:10-10:

1.

10. The method for purifying and preparing diborane according to claim 7, characterized in that, The second adsorption tower and the third adsorption tower are connected by a third pipeline, which is equipped with a heat exchanger and a pressure reducing device. The third adsorption tower is filled with molecular sieve adsorbent.

Images