A method for preparing high-purity diborane

Abstract

This invention belongs to the field of high-purity electronic chemicals, specifically relating to a method for preparing high-purity diborane. It addresses the problems in existing technologies regarding the difficulty in effectively removing impurities with boiling points close to diborane, and the impact of impurities such as metal ions and moisture in the raw materials on product purity. This invention utilizes a novel core-shell structured heterogeneous catalyst, MgO@ZrO2-Ir. 0 / Ir + This catalyst, functionalized with ionic liquid, exhibits high catalytic activity and hydrophobicity. It can selectively catalyze the hydrogenation conversion of light impurities under mild conditions. By employing mercapto-modified silica gel and a three-stage adsorption system, it deeply removes metal ions and trace amounts of moisture. Finally, through a combination of catalytic conversion and optimized dual-tower distillation, it effectively separates components with similar boiling points. This invention is applicable to high-end manufacturing fields such as semiconductors and photovoltaics.

Description

Technical Field

[0001] This invention belongs to the field of high-purity electronic chemicals, specifically relating to a method for preparing high-purity diborane (B2H6). Background Technology

[0002] Diborane is a colorless, pungent, and highly toxic gaseous compound that exists at room temperature and pressure. It exhibits typical "electron-deficient" characteristics due to the lack of valence electrons in its molecule. It possesses extremely high chemical reactivity; upon contact with water, it rapidly releases boric acid and hydrogen gas, with the reaction being exothermic and potentially igniting combustion. Diborane has important applications in the electronics industry: as a boron source for ion implantation and diffusion doping, for p-type doping in silicon-based semiconductor devices, and as a reducing agent or precursor in chemical vapor deposition or atomic layer deposition. Furthermore, diborane and its adducts can also be used as reducing agents in organic synthesis. With the increasing demand for diborane in downstream high-end manufacturing sectors, the requirements for product purity are becoming increasingly stringent. High-purity diborane requires extremely low impurity content to prevent impurities from introducing harmful elements or affecting reaction uniformity in semiconductor processes.

[0003] However, the purification of diborane has always been a challenge in producing high-purity products. On the one hand, diborane has a very low boiling point, and many potential impurities have similar boiling points. In traditional cryogenic distillation, these near-boiling-point impurities are difficult to separate completely from diborane, often requiring extremely high reflux ratios, multi-stage distillations, or repeated distillation to barely reduce the impurity content. On the other hand, diborane is extremely sensitive to moisture; once it comes into contact with water during purification, it hydrolyzes to form solid boron oxides, causing product loss and potentially clogging equipment. Different sources of crude diborane may also introduce other impurities. For example, using mercury-containing reagents may introduce mercury vapor, and using alkali metal borohydrides may result in trace metal salt particles being carried by the gas flow. If these metal impurities are not removed, they will severely affect the purity of diborane and cause metal contamination in downstream electronic processes.

[0004] To meet the purity requirements of electronic-grade diborane, various impurity removal schemes have been developed in existing technologies. For example, a potassium borohydride and sodium hydroxide chemical purifier neutralizes and absorbs residual BF3 and acidic impurities in crude diborane; then, high-boiling-point impurities and CO2 are removed by adsorption using a 13X molecular sieve; finally, diborane is solidified at low temperature to separate inert gas impurities. This method can efficiently purify crude diborane obtained by dry reaction to electronic-grade purity with extremely low product impurities. However, the above process is lengthy, requires multiple chemical agents, and involves secondary product processing. Another method involves passing a solid inorganic hydroxide adsorbent through a diborane-boron trihalide mixture to selectively capture halide impurities such as BF3. This method is carried out at low temperatures and can effectively remove impurities such as BF3, but the adsorbent needs to be replaced and regenerated periodically, and it has no effect on other impurities such as phosphine and water.

[0005] In summary, existing methods for preparing diborane have the following shortcomings in the purification process: First, there is a lack of efficient methods to remove impurities with boiling points close to diborane, and relying solely on low-temperature distillation is insufficient to obtain ultra-high purity products. Second, impurities such as metal ions and moisture introduced from raw materials and reaction byproducts are easily included in the distillation process, affecting purity and potentially damaging equipment and catalyst lifespan. Third, some methods use large amounts of chemical reagents for purification, resulting in a complex and costly process. Therefore, an innovative diborane purification method is urgently needed to effectively remove the aforementioned types of impurities, simplify the process, and improve product purity. Summary of the Invention

[0006] This invention provides a method for preparing high-purity diborane, which effectively solves the problems of difficult separation and introduction of impurities in diborane in the prior art through an innovative purification process integrating catalytic conversion and distillation.

[0007] The specific technical solution is as follows:

[0008] A method for preparing high-purity diborane is as follows:

[0009] S1: Preparation of heterogeneous catalyst support: Nano-sized magnesium oxide powder was dissolved in deionized water and mechanically stirred to prepare a magnesium oxide suspension; Zirconium oxychloride octahydrate was dissolved in deionized water and added dropwise to the magnesium oxide suspension under stirring; the pH was adjusted to 9-10 with ammonia water to obtain a mixed suspension; the mixed suspension was reacted at 150-180℃ for 12-24 h; after the reaction was completed, the suspension was cooled, filtered, washed, dried, calcined, and ground to obtain a core-shell structured MgO@ZrO2 support.

[0010] S2: Preparation of heterogeneous catalyst.

[0011] S21: Dissolve chloroiridic acid in deionized water to prepare a chloroiridic acid solution; then add the MgO@ZrO2 support prepared in S1 to the chloroiridic acid solution, stir the reaction, cool to room temperature after the reaction is completed, filter, wash, and dry to obtain the catalyst precursor.

[0012] S22: Dissolve 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt in anhydrous methanol, sonicate until completely dissolved, then add the catalyst precursor prepared in S21, stir and impregnate, and dry to obtain the surface-functionalized catalyst precursor.

[0013] S23: The surface-functionalized catalyst precursor prepared in S22 was placed in a tube furnace, and a mixture of 10% H2 and Ar gas (by volume) was introduced. The temperature was programmed and then cooled to room temperature to obtain the catalyst MgO@ZrO2-Ir. 0 / Ir + .

[0014] S3: Purification and preparation.

[0015] S31: After the crude borane feed gas is regulated by a pressure reducing valve, it is introduced into a pretreatment tower containing mercapto-modified silica gel. The outlet pressure of the pretreatment tower is controlled at 0.5–0.8 MPa, the temperature at 20–30°C, and the space velocity at 1000–5000 h⁻¹. -1 Then, deep removal of moisture is achieved through three-stage low-temperature adsorption to obtain pretreated crude borane feed gas.

[0016] S32: The pretreated crude borane feed gas prepared in S31 is mixed with hydrogen, and then passed through the catalyst MgO@ZrO2-Ir prepared in S23. 0 / Ir + A fixed-bed radial reactor was used to obtain converted diborane feed gas.

[0017] S33: The converted borane feed gas is passed through the first distillation column and the second distillation column successively to obtain high-purity borane.

[0018] Furthermore, the mechanical stirring described in S1 has the following parameter settings: rotation speed 500 rpm, duration 2 hours.

[0019] The nano-magnesium oxide powder described in S1 has a solid-liquid ratio of 1:30 with deionized water.

[0020] The mixed suspension described in S1 has a zirconium to magnesium mass ratio of 0.1:1 to 0.3:1.

[0021] The washing described in S1 involves alternating between deionized water and anhydrous ethanol, washing three times each.

[0022] The drying process described in S1 has the following parameters: temperature 80℃, duration 12h.

[0023] The calcination described in S1 has the following parameters: heating rate 2-5℃ / min, temperature 500℃, and holding time 4h.

[0024] Furthermore, in the chloroiridium acid described in S21, the iridium element is loaded at a rate of 0.5 to 2 wt% of the catalyst mass.

[0025] The stirring described in S21 has the following parameters: temperature 60-80℃, duration 6-8h.

[0026] The washing described in S21 involves washing with deionized water until the filtrate is colorless.

[0027] The drying process described in S21 has the following parameters: temperature 80℃, duration 12h.

[0028] Furthermore, the coating amount of the 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt described in S22 is 2 to 10 wt% of the catalyst precursor mass.

[0029] Furthermore, the programmed heating described in S23 has the following parameter settings: heating rate 1-5℃ / mic, temperature 300-400℃, and holding time 2-4h.

[0030] Furthermore, the parameters for the three-stage low-temperature adsorption described in S31 are as follows: the first stage uses 13X molecular sieve, the temperature is -20℃, the pressure is 0.2~0.4MPa, and the space velocity is 2000~6000h. -1 The second stage uses 3A molecular sieve, with a temperature of -40℃, a pressure of 0.2~0.4MPa, and a space velocity of 2000~6000h⁻¹. -1 The third stage uses the metal-organic framework material MIL-101(Cr), with a temperature of -20℃, a pressure of 0.2~0.4MPa, and a space velocity of 2000~6000h. -1 .

[0031] The fixed-bed radial reactor described in S32 has the following parameter settings: temperature 40–60℃, pressure 0.3–0.7 MPa, and space velocity 1000–15000 h⁻¹. -1 .

[0032] The parameters of the first distillation column described in S33 are as follows: top temperature -75 to -65℃, bottom temperature -55 to -45℃, and pressure 0.4 to 0.6 MPa.

[0033] The parameters of the second distillation column described in S33 are as follows: top temperature -100 to -90℃, bottom temperature -80 to -70℃, and pressure 0.2 to 0.4 MPa.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] 1. This invention utilizes MgO@ZrO2-Ir 0 / Ir + The catalyst, with its ZrO2 shell protecting the MgO core and improving stability; Ir 0 / Ir + The dual active centers exhibit excellent hydrogenation activity and selectivity; the hydrophobic protective layer formed by ionic liquid functionalization effectively repels moisture, prevents catalyst poisoning, and greatly extends service life.

[0036] 2. This invention solves the problem of separating impurities with similar boiling points by integrating catalytic conversion and distillation separation into easily separable substances through catalytic reaction. Attached Figure Description

[0037] Figure 1 This is a process flow diagram for the preparation of high-purity diborane.

[0038] Figure 2 This is a scanning electron microscope image of the core-shell structured MgO@ZrO2 support prepared in Example 1. Detailed Implementation

[0039] The following embodiments further explain and illustrate the technical solutions of the present invention. It should be specifically noted that each specific embodiment is a concretization and explanation of the technical solution and should not be considered as a limitation on the scope of protection of the present invention. Those skilled in the art still have the right to modify the technical solutions of these embodiments and make equivalent substitutions for some or all of the technical features, and these modifications or substitutions do not change the essence of the corresponding technical solutions, nor do they cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions described in the present invention.

[0040] This invention proposes a method for preparing high-purity diborane. First, the crude diborane gas is pretreated, including metal trapping and fractional drying, to remove trace metal ion impurities and moisture. Then, the pretreated gas is passed into a specially designed core-shell catalyst bed, where impurities undergo a transformation reaction in the presence of hydrogen, converting impurities with similar boiling points into other easily separable substances or trapping them by adsorption. Finally, the gaseous product is sent to a dual-tower distillation system to sequentially separate and remove residual heavy and light impurities, outputting a high-purity diborane product. Through the synergistic effect of these multiple purification methods, the purity of the final diborane is significantly improved. (See attached diagram) Figure 1 The diagram shows a method for preparing high-purity diborane, and its detailed technical solution is as follows:

[0041] 1. Catalyst Preparation

[0042] By utilizing the hydrolysis and deposition reactions of Zr precursors under hydrothermal conditions, a porous ZrO2 shell is grown in situ on the surface of nano-MgO particles. The MgO core provides abundant surface alkaline sites, which is beneficial for subsequent catalytic reactions; the ZrO2 shell acts as a stable mesoporous support, and its abundant hydroxyl groups are ideal sites for anchoring iridium active centers. At the same time, it can protect the MgO core from reacting too quickly with acidic components in the reactants, thereby improving catalyst lifetime.

[0043] By utilizing the negatively charged hydroxyl sites on the ZrO2 shell surface, and reacting with the negatively charged [IrCl6] in solution... 2- Ion exchange occurs between complex anions. The ZrOCl2 precursor used in the hydrothermal reaction ensures that the ZrO2 shell still contains a certain amount of chloride ions after calcination, which helps to form [IrCl6] which is beneficial for adsorption. 2-The surface environment. This method allows iridium to be highly dispersed and firmly anchored on the ZrO2 surface, preventing loss or aggregation of the active component during subsequent use.

[0044] The catalyst precursor is immersed in an ionic liquid solution, which coats the catalyst surface through physical adsorption and possible weak chemical interactions. After drying, a stable hydrophobic film is formed. This film effectively repels trace amounts of moisture in the feed gas, preventing water molecules from contacting the iridium active center or magnesium oxide core, thereby alleviating catalyst poisoning and deactivation problems and significantly improving its stability. The selected 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt has extremely high thermal stability and chemical inertness, and is also highly hydrophobic.

[0045] Under a hydrogen atmosphere and at a suitable temperature, [IrCl6] on the surface of the catalyst precursor is... 2- The complex ion is reduced to zero-valent iridium and partially oxidized iridium, forming Ir with hydrogenation catalytic activity. 0 / Ir + Dual active centers.

[0046] 2. Purification process of diborane

[0047] By utilizing the extremely strong soft acid-soft base coordination between thiol groups and metal ions, a stable metal thiol complex is formed, thereby specifically and irreversibly capturing and fixing metal ions on the surface of the adsorbent.

[0048] The pretreated gas is mixed with metered H2 and then passed through a container containing MgO@ZrO2-Ir 0 / Ir + A fixed-bed reactor for the catalyst. At the active sites of the catalyst, light, inert impurities with boiling points close to those of diborane undergo selective catalytic hydrogenation and are converted into products with higher boiling points that are easily separated by distillation.

[0049] The final separation is achieved through two-stage precision distillation, utilizing the differences in the relative volatility of the components in the mixture. Specifically, the first distillation column operates at a relatively high pressure to remove high-boiling-point impurities generated in the catalytic unit, as well as other heavy components that may be present in the feed. Increasing the pressure raises the boiling points of these high-boiling-point components, making them easier to concentrate and discharge from the bottom of the column. The second distillation column operates at a relatively low pressure to separate diborane and residual trace amounts of light components. Decreasing the pressure increases the relative volatility of diborane and these light components, making separation easier. Thus, when high-purity diborane is collected from the top of the column, the light components are vented as non-condensable gas from the top of the column.

[0050] A combination of adsorption and temperature gradient techniques is employed. Different adsorbents exhibit varying adsorption capacities and kinetic properties for water at different temperatures. By progressively decreasing the temperature and using the optimal adsorbent, deep and complete removal of water molecules can be achieved. Specifically: The first stage uses 13X molecular sieves with large pore sizes, enabling rapid adsorption of large amounts of water at relatively high temperatures, thus bearing the main dehydration load; the second stage uses 3A molecular sieves with pore sizes that allow only water molecules to enter while repelling larger B2H6 molecules, avoiding co-adsorption loss of product gases and achieving selective dehydration; the third stage uses MOF materials with ultra-high specific surface area and pore volume, exhibiting a strong ability to capture water molecules at low temperatures.

[0051] Example 1

[0052] A method for preparing high-purity diborane is as follows:

[0053] Table 1 Main Raw Materials

[0054]

[0055] S1: Preparation of heterogeneous catalyst support: Nano-sized magnesium oxide powder was dissolved in deionized water and mechanically stirred to prepare a magnesium oxide suspension. Zirconium oxychloride octahydrate was dissolved in deionized water and added dropwise to the magnesium oxide suspension under stirring. The pH was adjusted to 9.5 with ammonia to obtain a mixed suspension. The mixed suspension was reacted at 165℃ for 18 h. After the reaction, it was cooled, filtered, washed, dried, calcined, and ground to obtain a core-shell structured MgO@ZrO2 support. The mechanical stirring parameters were: 500 rpm for 2 h; the solid-liquid ratio of nano-sized magnesium oxide powder to deionized water was 1:30; the mass ratio of zirconium to magnesium was 0.2:1. The drying parameters were: 80℃ for 12 h. The calcination parameters were: heating rate 4℃ / min, temperature 500℃, and holding time 4 h. Figure 2 To obtain the core-shell structure MgO@ZrO2 support for scanning electron microscopy, the material was sputtered with gold. The scanning electron microscopy parameters were set as follows: accelerating voltage 10kV, working distance 7mm.

[0056] S2: Preparation of heterogeneous catalyst.

[0057] S21: Chloroiridic acid was dissolved in deionized water to prepare a chloroiridic acid solution; then the MgO@ZrO2 support prepared in S1 was added to the chloroiridic acid solution, and the reaction was stirred. After the reaction was completed, the mixture was cooled to room temperature, filtered, washed, and dried to obtain the catalyst precursor. The iridium loading in the chloroiridic acid was 1.3 wt% of the catalyst mass; the stirring parameters were set as follows: temperature 70℃, time 7 h; the drying parameters were set as follows: temperature 80℃, time 12 h.

[0058] S22: 1-Ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt is dissolved in anhydrous methanol, sonicated until completely dissolved, then the catalyst precursor prepared in S21 is added, stirred and impregnated, and dried to obtain a surface-functionalized catalyst precursor. The coating amount of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt is 6 wt% of the catalyst precursor mass.

[0059] S23: The surface-functionalized catalyst precursor prepared in S22 was placed in a tube furnace, and a mixture of 10% H2 and Ar gas (by volume) was introduced. The temperature was programmed and then cooled to room temperature to obtain the catalyst MgO@ZrO2-Ir. 0 / Ir + The programmed heating parameters are set as follows: heating rate 3℃ / mic, temperature 350℃, and holding time 3h.

[0060] S3: Purification and preparation.

[0061] S31: After the crude borane feed gas is regulated by a pressure reducing valve, it is introduced into a pretreatment tower containing mercapto-modified silica gel. The outlet pressure of the pretreatment tower is controlled at 0.7 MPa, the temperature at 25℃, and the space velocity at 3000 h⁻¹. -1 Then, deep removal of moisture is achieved through three-stage low-temperature adsorption to obtain pretreated crude diborane feed gas. Specifically, the parameters for the three-stage low-temperature adsorption described in S31 are as follows: the first stage uses 13X molecular sieve, temperature -20℃, pressure 0.3MPa, and space velocity 4000h⁻¹. -1 The second stage uses 3A molecular sieve, with a temperature of -40℃, a pressure of 0.3MPa, and a space velocity of 4000h⁻¹. -1 The third stage uses MIL-101(Cr), with a temperature of -20℃, a pressure of 0.3MPa, and a space velocity of 4000h. -1 .

[0062] S32: The pretreated crude borane feed gas prepared in S31 is mixed with hydrogen, and then passed through the catalyst MgO@ZrO2-Ir prepared in S23. 0 / Ir + A fixed-bed radial reactor was used to obtain the converted diborane feed gas. The parameters of the fixed-bed radial reactor were set as follows: temperature 50℃, pressure 0.5MPa, and space velocity 8000h⁻¹. -1 .

[0063] S33: The converted diborane feed gas is passed successively through a first distillation column and a second distillation column to obtain high-purity diborane. The first distillation column has a top temperature of -70℃, a bottom temperature of -50℃, and a pressure of 0.5MPa; the second distillation column has a top temperature of -95℃, a bottom temperature of -75℃, and a pressure of 0.3MPa.

[0064] Example 2

[0065] The composition and preparation process are the same as in Example 1, except that:

[0066] In step S1 of the preparation process, the mixed suspension was reacted at 150℃ for 12h, and the calcination heating rate was 2℃ / min. Other steps were the same.

[0067] In the preparation process S1, the mass ratio of zirconium to magnesium in the mixed suspension is 0.1:1, and the other components are the same.

[0068] In the preparation process S21, the iridium loading in the chloroiridic acid is 0.5 wt% of the catalyst mass, and the other components are the same.

[0069] In step S21 of the preparation process, the stirring temperature is 60℃ and the stirring time is 6h, while the other steps are the same.

[0070] In the preparation process, 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt in S22 is coated with 2 wt% of the catalyst precursor, and the other components are the same.

[0071] In step S23 of the preparation process, the temperature is programmed and the parameters are set as follows: heating rate 1℃ / mic, temperature 300℃, holding time 2h, and other steps are the same.

[0072] In process S31, the pretreatment tower outlet pressure is 0.5 MPa, the temperature is 20℃, and the space velocity is 1000 h⁻¹. -1 Three-stage cryogenic adsorption parameter settings: First stage pressure 0.2 MPa, space velocity 2000 h⁻¹ -1 Second-stage pressure: 0.2 MPa, space velocity: 2000 h⁻¹ -1 The third stage pressure is 0.2 MPa, and the air velocity is 2000 h⁻¹. -1 The other steps are the same.

[0073] The fixed-bed radial reactor in the S32 preparation process has the following parameters: temperature 40℃, pressure 0.3MPa, and space velocity 1000h⁻¹. -1 The other steps are the same.

[0074] In the preparation process S33, the top temperature of the first distillation column is -75℃, the bottom temperature is -55℃, and the pressure is 0.4MPa; the top temperature of the second distillation column is -100℃, the bottom temperature is -80℃, and the pressure is 0.2MPa, with the other steps being the same.

[0075] Example 3

[0076] The composition and preparation process are the same as in Example 1, except that:

[0077] In step S1 of the preparation process, the mixed suspension was reacted at 180℃ for 24 hours, and the calcination heating rate was 5℃ / min. Other steps were the same.

[0078] In the preparation process S1, the mass ratio of zirconium to magnesium in the mixed suspension is 0.3:1, and the other components are the same.

[0079] In the preparation process S21, the iridium loading in the chloroiridic acid is 2 wt% of the catalyst mass, and the other components are the same.

[0080] In step S21 of the preparation process, the stirring temperature is 80℃ and the stirring time is 8h, while the other steps are the same.

[0081] In the preparation process, 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt in S22 is coated with 10 wt% of the catalyst precursor, and the other components are the same.

[0082] In step S23 of the preparation process, the temperature is programmed and the parameters are set as follows: heating rate 5℃ / mic, temperature 400℃, holding time 4h, and other steps are the same.

[0083] In process S31, the pretreatment tower outlet pressure is 0.8 MPa, the temperature is 30℃, and the space velocity is 5000 h⁻¹. -1 Three-stage cryogenic adsorption parameter settings: First stage pressure 0.4 MPa, space velocity 6000 h⁻¹ -1 The second stage pressure is 0.4 MPa, and the space velocity is 6000 h⁻¹. -1 The third stage pressure is 0.4 MPa, and the space velocity is 6000 h⁻¹. -1 The other steps are the same.

[0084] The fixed-bed radial reactor in the S32 preparation process has the following parameters: temperature 60℃, pressure 0.7MPa, and space velocity 15000h⁻¹. -1 The other steps are the same.

[0085] In the preparation process S33, the top temperature of the first distillation column is -65℃, the bottom temperature is -55℃, and the pressure is 0.6MPa; the top temperature of the second distillation column is -90℃, the bottom temperature is -70℃, and the pressure is 0.4MPa. The other steps are the same.

[0086] Example 4

[0087] The composition and preparation process are the same as in Example 1, except that:

[0088] In step S1 of the preparation process, the mixed suspension was reacted at 170℃ for 20h, and the calcination heating rate was 3℃ / min. Other steps were the same.

[0089] In the preparation process S1, the mass ratio of zirconium to magnesium in the mixed suspension is 0.25:1, and the other components are the same.

[0090] In the preparation process S21, the iridium loading in the chloroiridic acid is 1.5 wt% of the catalyst mass, and the other components are the same.

[0091] In step S21 of the preparation process, the stirring temperature is 75℃ and the stirring time is 6.5h, while the other steps are the same.

[0092] In the preparation process, 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt in S22 is coated with 8 wt% of the catalyst precursor, and the other components are the same.

[0093] In step S23 of the preparation process, the temperature is programmed and the parameters are set as follows: heating rate 2℃ / min, temperature 350℃, duration 2.5h, and other steps are the same.

[0094] In process S31, the pretreatment tower outlet pressure is 0.6 MPa, the temperature is 28℃, and the space velocity is 4000 h⁻¹. -1 Three-stage cryogenic adsorption parameter settings: First stage pressure 0.35 MPa, space velocity 2500 h⁻¹ -1 Second-stage pressure: 0.25 MPa, air velocity: 4000 h⁻¹ -1 The third stage pressure is 0.35 MPa, and the space velocity is 2500 h⁻¹. -1 The other steps are the same.

[0095] The fixed-bed radial reactor in the S32 preparation process has the following parameters: temperature 55℃, pressure 0.6MPa, and space velocity 13000h⁻¹. -1 The other steps are the same.

[0096] In the preparation process S33, the top temperature of the first distillation column is -68℃, the bottom temperature is -52℃, and the pressure is 0.45MPa; the top temperature of the second distillation column is -97℃, the bottom temperature is -77℃, and the pressure is 0.25MPa. The other steps are the same.

[0097] Comparative Example 1

[0098] The composition and preparation process are the same as in Example 1, except that:

[0099] In step S22 of the preparation process, the 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt treatment is removed, and a catalyst that has not undergone hydrophobic functionalization is used for treatment. The other steps are the same.

[0100] Comparative Example 2

[0101] The composition and preparation process are the same as in Example 1, except that:

[0102] In step S31 of the preparation process, the three-stage combined adsorption and dehydration is removed, and only a single-stage 13X molecular sieve is used for dehydration at 25°C. The other steps are the same.

[0103] Comparative Example 3

[0104] The composition and preparation process are the same as in Example 1, except that:

[0105] In step S32 of the preparation process, the catalyst treatment is removed and replaced with iodine catalyst; the other steps remain the same.

[0106] Based on Examples 1-4 and Comparative Examples 1-3, samples of the finally prepared diborane were taken for purity and hydrogen chloride content tests, referring to the standard GB / T 6017-2021 "Determination of Purity and Hydrocarbon Impurities of Industrial Butadiene by Gas Chromatography".

[0107] Based on Examples 1-4 and Comparative Examples 1-3, samples of the finally prepared diborane were taken and tested for moisture content, referring to standard GB / T 5832.2-2016 "Determination of trace moisture in gases - Part 2: Dew point method".

[0108] Based on Examples 1-4 and Comparative Examples 1-3, samples of the finally prepared diborane were taken and the content of metal ion Ir was tested, referring to the standard GB / T 30301-2013 "General Rules for Test Methods of High Purity Reagents".

[0109] The specific test results are shown in Table 2:

[0110] Table 2 Comparison of core performance of Examples 1-4 and Comparative Examples 1-3

[0111]

[0112] The comparison results show that Example 1 has the highest purity. The synergistic effect of catalyst functionalization, deep dehydration, and catalytic conversion results in a purity of 99.9995%, with all key impurities at extremely low levels. This indicates that Example 1 effectively removes impurities with boiling points close to diborane, as well as metal ions and moisture from the raw materials. Examples 2 to 4 have slightly lower overall performance than Example 1 but still maintain a high level, demonstrating excellent purification results even with a wide range of parameter variations. Comparative Example 1, lacking ionic liquid functionalization, experienced a sharp decline in catalyst performance despite normal dehydration. Ir nanoparticles were prone to sintering and detachment during the reaction, leading to metal contamination of the product. Simultaneously, the acidic sites on the unmodified support surface reacted with B2H6, generating a large amount of HCl. Comparative Example 2, relying solely on a single-stage molecular sieve, could not achieve the deep dehydration required for electronic-grade gas, leaving a large amount of residual moisture. This not only directly reduces product purity but also causes hydrolysis, generating borane polymers and hydrogen. Comparative Example 3 lacked MgO@ZrO2-Ir.0 / Ir + The catalyst, HCl, cannot be effectively separated by physical distillation and ends up in large quantities in the product, resulting in a significant decrease in purity.

[0113] In summary, it is clear from the above examples and comparative examples that the high-purity diborane provided by the present invention is superior to traditional methods in terms of purification. This is attributed to the construction of the catalyst MgO@ZrO2-Ir. 0 / Ir + Its sophisticated design, three-stage adsorption, and catalytic conversion of impurities effectively remove impurities with boiling points close to those of diborane.

Claims

1. A method for preparing high-purity diborane, characterized in that: the method for preparing high-purity diborane comprises the following steps: The preparation method adopts a heterogeneous catalyst MgO@ZrO2-Ir 0 / Ir + and a catalytic-distillation integrated purification system; the heterogeneous catalyst MgO@ZrO2-Ir 0 / Ir + After being ionically functionalized, the catalyst has high catalytic activity and hydrophobicity, and can selectively catalyze hydrogenation conversion of light impurities; the catalytic-distillation integrated purification system removes metal ions and trace water through mercapto-modified silica gel and a three-stage combined adsorption system, and separates components with close boiling points through catalytic conversion combined with a double-tower distillation. The converted diborane raw gas is sequentially passed through a first rectifying tower and a second rectifying tower to obtain high-purity diborane. The crude diborane raw material gas is regulated by a pressure reducing valve, and then is introduced into a pretreatment tower containing mercapto-modified silica gel, the pressure at the outlet of the pretreatment tower is controlled to be 0.5-0.8 MPa, the temperature is controlled to be 20-30℃, and the space velocity is controlled to be 1000-5000 h -1 ; then, the moisture is deeply removed by three-stage low-temperature adsorption, and the pretreated crude diborane raw material gas is obtained. The pretreated raw diborane gas is mixed with hydrogen and then passed through a fixed bed radial reactor containing a catalyst MgO@ZrO2-Ir 0 / Ir + to obtain a converted diborane feed gas.

2. The method for preparing high-purity diborane according to claim 1, characterized in that: The catalytic-distillation integrated purification system comprises, in sequence, a pretreatment adsorption tower provided with sulfhydryl-modified silica gel, a three-stage combined adsorption dehydration tower, a fixed-bed radial catalytic reactor provided with a hydrogen injection port, a first rectifying tower, and a second rectifying tower. The heterogeneous catalyst MgO@ZrO2-Ir 0 / Ir + which is composed of an MgO core, a ZrO2 shell, and a metal Ir active center and an ionic liquid hydrophobic protective layer supported on the shell; The method comprises the following steps:

3. The method of claim 1, wherein the method is characterized by, S1: Preparation of a heterogeneous catalyst carrier, wherein nano-magnesium oxide powder is dissolved in deionized water, mechanical stirring is performed, and a magnesium oxide suspension is prepared; zirconium oxychloride octahydrate is dissolved in deionized water, and the solution is added dropwise to the magnesium oxide suspension under stirring, and the pH is adjusted to 9-10 with ammonia water to obtain a mixed suspension; the mixed suspension is reacted at 150-180°C for 12-24h, after the reaction is completed, the mixture is cooled, filtered, washed, dried, calcined, and ground to obtain a core-shell structure MgO@ZrO2 carrier; S2: Preparation of a heterogeneous catalyst; S21: Chloroiridic acid is dissolved in deionized water to prepare a chloroiridic acid solution; then the MgO@ZrO2 carrier prepared in S1 is added to the chloroiridic acid solution, and stirring is performed; after the reaction is completed, the mixture is cooled to room temperature, filtered, washed, and dried to obtain a catalyst precursor; S22: The catalyst precursor prepared in S21 is added to an ionic liquid, stirring is performed, and the mixture is dried to obtain a surface-functionalized catalyst precursor; 4. The method for preparing high-purity diborane according to claim 3, characterized in that: S23: The surface functionalized catalyst precursor prepared in S22 was placed in a tube furnace, and 10% H2 mixed with Ar was introduced, and the temperature was programmed to rise, and then cooled to room temperature to obtain the catalyst MgO@ZrO2-Ir 0 / Ir + . In S1, the mechanical stirring is performed at a rotation speed of 500 rpm for 2h; In S1, the solid-liquid ratio of the nano-magnesium oxide powder to deionized water is 1:30; In S1, the mass ratio of zirconium to magnesium in the mixed suspension is 0.1:1-0.3:1; In S1, the washing is performed with deionized water and anhydrous ethanol alternately for 3 times each; In S1, the drying is performed at a temperature of 80°C for 12h; In S1, the calcination is performed at a temperature of 500°C at a temperature increasing rate of 2-5°C / min for 4h.

5. The method for preparing high-purity diborane according to claim 3, characterized in that: In S21, the loading amount of iridium in the chloroiridic acid is 0.5-2wt% of the mass of the catalyst; In S21, the stirring is performed at a temperature of 60-80°C for 6-8h; In S21, the washing is performed with deionized water until the filtrate is colorless; In S21, the drying is performed at a temperature of 80°C for 12h.

6. The method for preparing high-purity diborane according to claim 3, characterized in that: In S22, the ionic liquid is 1-ethyl-3-methylimidazolium bistrifluoromethylsulfonylimide, and the amount of the ionic liquid is 2-10wt% of the mass of the catalyst precursor in S21.

7. The method for preparing high-purity diborane according to claim 3, characterized in that: ​ The temperature is raised according to the procedure of S23, and the parameters are set as follows: temperature raising rate 1-5 ℃ / mic, temperature 300-400 ℃, and holding time 2-4 h.

8. The method of claim 1, wherein the high-purity diborane is prepared by the following steps: 1) preparing a mixture of diborane and hydrogen; 2) purifying the mixture of diborane and hydrogen; and 3) collecting the purified diborane. The structure and parameters of the three-stage low-temperature adsorption include: the first stage uses 13X molecular sieve, the temperature is -20 DEG C, the pressure is 0.2-0.4 MPa, the space velocity is 2000-6000 h -1 -1; the second stage uses 3A molecular sieve, the temperature is -40 DEG C, the pressure is 0.2-0.4 MPa, the space velocity is 2000-6000 h -1 -1; the third stage uses metal organic framework material, the temperature is -20 DEG C, the pressure is 0.2-0.4 MPa, the space velocity is 2000-6000 h -1 -1.

9. The method of claim 1, wherein the high-purity diborane is prepared by the following steps: 1) preparing a mixture of diborane and hydrogen; 2) purifying the mixture of diborane and hydrogen; and 3) collecting the purified diborane. The fixed bed radial reactor has the following parameter settings: temperature 40-60℃, pressure 0.3-0.7MPa, space velocity 1000-15000h -1 .

10. The method of claim 1, wherein the high-purity diborane is prepared by the following steps: 1) preparing a mixture of diborane and hydrogen; 2) purifying the mixture of diborane and hydrogen; and 3) collecting the purified diborane. The first rectifying tower is set as follows: top temperature -75 to -65 ℃, bottom temperature -55 to -45 ℃, and pressure 0.4 to 0.6 MPa. The second rectifying tower is set as follows: top temperature -100 to -90 ℃, bottom temperature -80 to -70 ℃, and pressure 0.2 to 0.4 MPa.

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