Method for preparing electronic-grade hydroxylamine aqueous solution

Abstract

The invention relates to a method for preparing an electronic-grade hydroxylamine aqueous solution by using an industrial-grade 50% hydroxylamine aqueous solution as a raw material through a microfiltration, ion exchange and nanofiltration combined technology. The method comprises the following steps: firstly, removing suspended particles and colloidal substances by microfiltration pretreatment; removing ion impurities through a specially modified ion exchange resin combined bed; and finally, deeply purifying by utilizing a nanofiltration technology to obtain a high-purity product. The method is short in process route, safe to operate and low in cost, the electronic-grade hydroxylamine aqueous solution can be stably produced, the metal ion content is lower than 10 ppt, the particle size of particles is controlled to be larger than 0.1 micrometer and smaller than 50 particles / ml, the resistivity reaches 18.2 M omega.cm, and the industrial requirements of semiconductor manufacturing, integrated circuits and display panels are met.

Description

Technical Field

[0001] This invention belongs to the field of electronic chemical purification technology, specifically relating to a method for preparing electronic-grade hydroxylamine aqueous solution. Background Technology

[0002] Hydroxylamine aqueous solution, as an important electronic chemical, is widely used in key processes such as photoresist removal, wafer cleaning, and etching in semiconductor and display panel manufacturing. Hydroxylamine aqueous solutions used in the electronics industry need to meet extremely high purity requirements, typically meeting SEMI G3 to G5 standards, meaning a metal ion content of less than 10 ppt to 1 ppb, particulate matter controlled within a certain range, and a solution resistivity of at least 18.2 MΩ·cm.

[0003] Currently, the main methods for preparing electronic-grade hydroxylamine aqueous solutions include ion exchange, electrodialysis, distillation, and metathesis. Patents CN117418245A and CN119056256A published by Zhejiang Jinhua New Material Co., Ltd. describe methods for preparing hydroxylamine aqueous solutions using electrodialysis and modified ion exchange membranes. These methods effectively remove metal ions through special modified ion exchange membranes, improving the purity and stability of the product. However, electrodialysis requires significant equipment investment, is complex to operate, and has high requirements for raw materials. Additionally, CN1648035A proposes a method for preparing high-purity hydroxylamine aqueous solutions by combining low-temperature filtration and ion exchange. While this method can obtain high-purity products, it requires low-temperature operation, consumes a lot of energy, and involves a vacuum distillation step, posing certain safety risks.

[0004] Industrial-grade hydroxylamine aqueous solutions typically contain various impurities, primarily metal ions (such as Na+). + K + Ca 2+ Fe 2+ Cu 2+ etc.), anions (such as Cl-, etc.) - SO4 2- NO3 - Hydroxylamine contains particulate matter and organic impurities. These impurities have a serious impact on the performance of semiconductor devices, potentially causing short circuits, leakage current, and decreased reliability. Therefore, there is a need to develop an efficient, economical, and safe purification process to purify industrial-grade hydroxylamine aqueous solution into an electronic-grade product.

[0005] Table 1 Comparison of different methods for preparing hydroxylamine aqueous solutions

[0006]

[0007] In summary, existing purification technologies have the following main problems: a single purification method is insufficient to completely remove all kinds of impurities. Summary of the Invention

[0008] The purpose of this invention is to provide a method for preparing electronic-grade hydroxylamine aqueous solution using industrial-grade 50% hydroxylamine aqueous solution as raw material through a combination of microfiltration, ion exchange and nanofiltration technologies, thereby solving the problems of poor purification effect, unstable production process, significant safety hazards and high production cost in the prior art.

[0009] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing an electronic-grade hydroxylamine aqueous solution, the method comprising the following steps:

[0010] S1 microfiltration pretreatment: Industrial-grade 50% hydroxylamine aqueous solution is passed through a polyvinylidene fluoride microfiltration membrane with a pore size of 0.1–0.2 μm at a temperature of 15–25 °C and an operating pressure of 0.1–0.5 MPa to remove suspended particles and colloidal substances;

[0011] S2 ion exchange purification: The filtrate obtained from S1 is sequentially passed through at least one cation exchange column packed with a strong acidic cation exchange resin, at least one anion exchange column packed with a strong basic anion exchange resin, and a mixed bed exchange column packed with a mixed ion exchange resin; the operating temperature is maintained at 15-25 °C, and the flow rate is controlled at 4-7 BV / h to deeply remove various metal ions and anion impurities.

[0012] S3 nanofiltration purification: The ion-exchanged hydroxylamine aqueous solution is passed through a nanofiltration system using a polyamide composite membrane with a molecular weight cutoff of 150 or higher, at an operating pressure of 1.0–4.0 MPa and a temperature of 20–30 °C, to obtain a high-purity hydroxylamine aqueous solution.

[0013] Preferably, the strong acid resin is a sulfonic acid-modified styrene-divinylbenzene copolymer resin with a crosslinking degree of 8-12%.

[0014] Preferably, the strongly alkaline resin is a quaternary ammonium-modified styrene-divinylbenzene copolymer resin with a crosslinking degree of 6-10%.

[0015] Preferably, the mixed ion exchange resin is composed of a mixture of a strongly acidic cation exchange resin and a strongly basic anion exchange resin.

[0016] Preferably, in the mixed ion exchange resin, the volume ratio of cation exchange resin to anion exchange resin is 1:1.5 to 1:2.0.

[0017] Preferably, the nanofiltration system adopts a two-stage series design, with the first-stage nanofiltration membrane having a molecular weight cutoff of 200-300 Da and the second-stage nanofiltration membrane having a molecular weight cutoff of greater than 150 Da.

[0018] Preferably, the method further includes the step of adding a stabilizer to the aqueous hydroxylamine solution after S2 ion exchange purification and before S3 nanofiltration purification, wherein the stabilizer is one of hydroxyurea or aminoquinoline.

[0019] Preferably, the amount of stabilizer added is 0.01 to 0.05 wt%.

[0020] Preferably, the microfiltration step, ion exchange step, and nanofiltration step are all performed under inert gas protection.

[0021] Preferably, the final electronic-grade hydroxylamine aqueous solution has a metal ion content of less than 10 ppt, a particle size (≥0.1 μm) of less than 50 particles / mL, and a resistivity of 18.2 MΩ·cm.

[0022] The above-described technical solution of the present invention has the following beneficial effects:

[0023] The technical solution of this invention employs a combined microfiltration-ion exchange-nanofiltration process to safely, efficiently, and environmentally friendly prepare high-quality electronic-grade hydroxylamine aqueous solutions. The final product exhibits metal ion content below 10 ppt, total anion content below 2 ppb, particulate matter (≥0.1 μm) not exceeding 50 particles / mL, and resistivity not less than 18.2 MΩ·cm, meeting electronic-grade reagent standards. The entire production process operates under low-temperature, closed conditions, effectively preventing hydroxylamine decomposition and external contamination, thus enhancing production safety. Furthermore, this process is short, energy-efficient, and has high raw material utilization, resulting in good economic benefits. In addition, the system generates minimal wastewater, primarily originating from easily treatable resin regeneration, making it environmentally friendly.

[0024] Introduction to chemical substances and explanation of terminology:

[0025] Hydroxylamine: Chemical formula NH₂OH, relative molecular weight 61.083, unstable white flake or needle-like crystals, rapidly decomposes upon absorbing water vapor and carbon dioxide at room temperature. It explodes violently upon heating. It is readily soluble in water, liquid nitrogen, and methanol.

[0026] Hydroxylamine aqueous solution: The relative densities of the aqueous solution at mass fractions of 100%, 10%, 20%, 30%, 40%, and 50% are 1.2040, 1.0192, 1.0410, 1.0637, 1.0875, and 1.1122, respectively. It decomposes in hot water.

[0027] Table 2 Terminology Explanation

[0028] Attached Figure Description

[0029] Figure 1 This is a flowchart of the preparation process of electronic-grade hydroxylamine aqueous solution according to the present invention.

[0030] Explanation of icon numbers:

[0031] 1. Raw material storage tank; 2. Cooler; 3. Precision microfiltration device; 4 / 5. Ion exchange system; 4A / 4B / Cation exchange column; 5A / 5B Anion exchange column; 45C Mixed bed exchange column; 6. Intermediate storage tank; 7. Terminal nanofiltration device; 8. Collection tank; 9. Online particle counter; 10. Online anion and cation detector. Detailed Implementation

[0032] The following embodiments further illustrate the content of the present invention, but should not be construed as limiting the present invention. Any modifications or substitutions made to the methods, steps, or conditions of the present invention without departing from the spirit and essence of the invention are within the scope of the present invention.

[0033] In the prior art, common methods for purifying hydroxylamine aqueous solutions include ion exchange, electrodialysis, distillation, and metathesis. For example, CN117418245A discloses a method for preparing hydroxylamine aqueous solutions using hydroxylamine salts. This method employs electrodialysis to obtain a 50% hydroxylamine aqueous solution with a total metal content of less than 0.1 mg / kg. CN119056256A discloses a hydroxylamine salt conversion process based on ion exchange and a special ion exchange membrane, resulting in a 50% hydroxylamine aqueous solution with iron and total metal contents both below 0.1 mg / kg. CN1648035A proposes a method for preparing high-purity hydroxylamine aqueous solutions combining metathesis reaction, low-temperature filtration, and ion exchange. The resulting product has copper and iron contents at levels of 0.72 ppb and 4.99 ppb, respectively, but this process relies on distillation for purification.

[0034] Although CN1648035A showed good removal of copper and iron, its removal effect on chloride, sulfate, sodium and potassium ions was average; CN119056256A removed all types, but failed to meet the SEMIG5 standard.

[0035] While the above methods can purify hydroxylamine aqueous solutions to some extent, they still have limitations, such as high operating costs, high energy consumption, safety risks, large amounts of waste generated, and complex subsequent treatment. Specifically, although CN1648035A shows good removal capabilities for specific metals such as copper and iron, its removal effect on other key ions such as chloride, sulfate, sodium, and potassium ions is limited; while CN119056256A, although possessing some removal capabilities for multiple ions, still fails to meet electronic-grade standards for its final product.

[0036] To address the aforementioned problems in existing technologies, this invention, from the perspective of practical industrial applications, aims to develop a comprehensive hydroxylamine aqueous solution purification process. This application emphasizes the synergistic and in-depth removal of various metal cation and anionic impurities, while avoiding the safety and energy consumption issues associated with high temperatures. This achieves a balance between process economy and operational safety, ensuring that the product meets electronic-grade high-purity standards.

[0037] To achieve the above purification process, this invention designs and constructs a continuous purification system. This system is designed so that all components in contact with the material are made of materials with low metal leaching rates (such as 316L stainless steel with electropolishing treatment or high-purity PFA) to ensure that no secondary contamination is introduced during the purification process.

[0038] The system is connected to the following units in sequence via pipelines:

[0039] First, raw material storage tank 1 stores the industrial-grade hydroxylamine aqueous solution to be purified. After being pumped out, the raw material solution first enters cooler 2 to control the material temperature within the range of 15–25 °C. The cooled solution then enters precision microfiltration device 3. This device incorporates a polytetrafluoroethylene (PTFE) microfiltration membrane module with a pore size of 0.1–0.2 μm. Under an operating pressure of 0.1–0.5 MPa, it can effectively remove suspended particles, colloids, and other insoluble impurities from the raw material solution, completing the primary purification of the solution. The microfiltered solution then enters ion exchange system 4 / 5. This system is a multi-stage series design, including at least two sets of cation exchange columns 4A / 4B and at least two sets of anion exchange columns 5A / 5B, capable of deeply removing various metal cations (such as Na+) from the aqueous solution. + K + Cu 2+ Fe 2+ (etc.) and anions (such as Cl) - SO4 2- Impurities (e.g.) are removed. To further improve the purity of the hydroxylamine aqueous solution, a mixed-bed exchange column 45C can be installed after the anion and cation exchange columns in this system. By mixing anion and cation exchange resins, the residual ions are further purified, significantly improving the solution resistivity. The hydroxylamine aqueous solution after ion exchange is temporarily stored in intermediate storage tank 6 to prepare for the next purification step.

[0040] Subsequently, the solution enters the terminal nanofiltration unit 7 from the intermediate storage tank 6. This unit is supplied with an operating pressure of 1.0–4.0 MPa by a feed pump, driving the solution through its built-in polyamide composite nanofiltration membrane assembly. This process can retain trace amounts of macromolecular organic matter or colloidal substances that may be present in the solution.

[0041] Finally, the obtained high-purity electronic-grade hydroxylamine aqueous solution is received in product collection tank 8 for later use.

[0042] To ensure stable and controllable product quality, this system also integrates an online detection unit. Specifically, an online anion and cation detector 10 is installed on the outlet pipe of the ion exchange system for real-time monitoring of the purification effect; an online particle counter 9 is installed on the outlet pipe of the product collection tank for monitoring the number of particles in the final product.

[0043] Based on the above purification system and process, the effectiveness of this invention is verified through the following embodiments:

[0044] Example 1

[0045] S1 Microfiltration Pretreatment: Take 100 L of industrial-grade 50% hydroxylamine aqueous solution and place it in the raw material storage tank. Purge with nitrogen to prevent oxidation. Pass the raw material through a 0.2 μm pre-filter, and then into a hollow fiber microfiltration membrane module (polytetrafluoroethylene material, pore size 0.2 μm). Microfiltration is carried out at a temperature of 20 ℃ and an operating pressure of 0.3 MPa.

[0046] S2 Ion Exchange Purification: The microfiltration-pretreated hydroxylamine aqueous solution was sequentially passed through an ion exchange system consisting of a cation exchange column, an anion exchange column, and a mixed-bed exchange column. The cation exchange resin was a sulfonic acid-modified styrene-divinylbenzene copolymer resin (10% crosslinking), and the anion exchange resin was a quaternary ammonium-modified styrene-divinylbenzene copolymer resin (8% crosslinking). The mixed-bed resin volume ratio was 1:1.5. The flow rate was controlled at 5 BV / h, and the system temperature was maintained at 25 °C. 0.05 wt% hydroxyurea was added to the ion-exchanged hydroxylamine aqueous solution. This step removed most of the ionic impurities.

[0047] S3 Nanofiltration Purification: The ion-exchanged hydroxylamine aqueous solution was passed through a two-stage tandem nanofiltration system. The first-stage nanofiltration membrane retained a polyamide composite membrane with a molecular weight cutoff of 300 Da, operating at a pressure of 2.0 MPa; the second-stage nanofiltration membrane retained a polyamide composite membrane with a molecular weight cutoff of 150 Da, operating at a pressure of 2.5 MPa. The temperature was controlled at 25 °C. This step further removed residual small-molecule organic matter and ionic impurities. The final product was collected in a nitrogen-protected product storage tank, with 0.02 wt% hydroxyurea added as a stabilizer.

[0048] Example 2

[0049] The difference between this embodiment and Embodiment 1 is that:

[0050] S1 microfiltration pretreatment: Temperature: 15 ℃, Operating pressure: 0.1 MPa;

[0051] S2 ion exchange purification: cation exchange resin with 8% crosslinking degree, anion exchange resin with 10% crosslinking degree, mixed bed resin with a volume ratio of 1:2.0, flow rate of 6 BV / h, temperature: 20 ℃. 0.02wt% hydroxyurea was added to the hydroxylamine aqueous solution after ion exchange.

[0052] S3 nanofiltration purification: The first-stage nanofiltration membrane has a molecular weight cutoff of 200 Da and an operating pressure of 1.0 MPa; the second-stage membrane has a molecular weight cutoff of 160 Da and an operating pressure of 3.0 MPa. The temperature is controlled at 30 ℃.

[0053] Example 3

[0054] The difference between this embodiment and Embodiment 1 is that:

[0055] S1 microfiltration pretreatment: Temperature: 20 ℃, Operating pressure: 0.5 MPa;

[0056] S2 ion exchange purification: cation exchange resin crosslinking degree 12%, anion exchange resin crosslinking degree 8.5%, flow rate 4 BV / h, temperature: 15 ℃. 0.03 wt% hydroxyurea was added to the aqueous solution of hydroxylamine after ion exchange.

[0057] S3 nanofiltration purification: The first-stage nanofiltration membrane has a molecular weight cutoff of 250 Da and an operating pressure of 4.0 MPa; the second-stage membrane has a molecular weight cutoff of 200 Da and an operating pressure of 1.0 MPa. The temperature is controlled at 20 ℃.

[0058] Example 4

[0059] The difference between this embodiment and Embodiment 1 is that:

[0060] Nanofiltration system: It adopts a three-stage nanofiltration system in series. The first stage has a molecular weight cutoff of 300 Da, the second stage has a molecular weight cutoff of 200 Da, and the third stage has a molecular weight cutoff of 150 Da. The operating pressures are 1.5 MPa, 2.0 MPa and 2.5 MPa, respectively.

[0061] Examples 5-11

[0062] The differences between Examples 5-11 and Example 1 are shown in Table 3:

[0063] Table 3 Examples 5-11

[0064]

[0065] Compare with Example 1

[0066] This comparative example uses the method described in CN119056256A4 to modify the resin with porphyrin groups. Specifically, the anion exchange resin was placed in a plasma surface treatment instrument, and ethyl 3-mercaptopropionate vapor was introduced at a power of 200 W for 120 s to obtain a mercapto-modified resin. Then, 0.1 parts of 5,10,15,20-tetrakis(4-vinylphenyl)porphyrin, 1.5 parts of 1,5-diaminobiurea, 400 parts of ethanol, and 80 parts of the mercapto-modified resin were mixed and stirred at 65 °C for 120 minutes. After filtration and washing with water, the modified resin was obtained. The ion exchange system in this comparative example was an ion exchange column packed with the above-mentioned modified resin, and other steps were the same as in Example 1.

[0067] Compare with Example 2

[0068] This comparative example verifies the crucial role of the ion exchange system.

[0069] Compared with Example 1, this comparative example uses only a mixed bed resin composed of sulfonated styrene resin and quaternary ammonium styrene resin in a volume ratio of 1:1.5 for ion exchange in the ion exchange step.

[0070] Compare with Example 3

[0071] The difference between this comparative example and Example 1 is that:

[0072] S3 Nanofiltration Purification: The nanofiltration step uses a polyamide composite membrane with a molecular weight cutoff of 320 Da, operates at a pressure of 5.0 MPa, and only performs one stage of nanofiltration.

[0073] Compare with Example 4

[0074] The difference between this comparative example and Example 1 is that:

[0075] S2 ion exchange purification: flow rate of 8 BV / h.

[0076] Compare with Example 5

[0077] The difference between this comparative example and Example 1 is that:

[0078] S2 ion exchange purification: flow rate of 10 BV / h.

[0079] Compare with Example 6

[0080] The difference between this comparative example and Example 1 is that:

[0081] S3 nanofiltration purification: The operating pressure of both nanofiltration stages is 5.0 MPa.

[0082] Experimental Example 1:

[0083] Experimental methods: The content of metal ions in the aqueous solution of hydroxylamine was analyzed by inductively coupled plasma mass spectrometry (ICP-MS), and the content of anions in the aqueous solution of hydroxylamine was analyzed by ion chromatography (results are shown in Table 4); the content of particulate matter in the aqueous solution of hydroxylamine was detected by laser particle counter (results are shown in Table 5), and the resistivity of the purified aqueous solution of hydroxylamine was measured by conductivity meter (results are shown in Table 6).

[0084] Table 4 Ionic impurities in purified hydroxylamine aqueous solutions of Examples 1-8 and Control Examples 1-5

[0085]

[0086] Note: The impurity content after purification indicates that multiple measurements have been lower than this value.

[0087] Table 5. Particulate matter content in purified hydroxylamine aqueous solutions of Examples 1-8 and Control Examples 1-5

[0088]

[0089] Table 6. Resistivity of purified hydroxylamine aqueous solutions in Examples 1-8 and Control Examples 1-5

[0090]

[0091] Results analysis:

[0092] As shown in Tables 4-6, Examples 1-8 of this application, through the synergistic combination of three purification steps—microfiltration, ion exchange, and nanofiltration—ensure that the content of both metal ions and anions in the purified hydroxylamine aqueous solution meets the requirements of electronic-grade reagent standards.

[0093] The purification effects of Examples 1-8 were better than those of Control Examples 1-5. However, although Control Example 1 showed better purification of Fe... 2+ Cu 2+ It has the advantage of specific removal (content < 4 ppt), but is not effective against Cl. - SO4 2- The removal effect was poor, and the resistivity (17.5 MΩ·cm) was less than 18.2 MΩ·cm, with a high particulate matter content. In contrast, Examples 1-8 of this application showed better removal of Na. + K + Fe 2+ Cu 2+ Cl - SO4 2- Simultaneous and efficient removal of key ions, with all indicators meeting the requirements of electronic-grade reagent standards.

[0094] S1 microfiltration pretreatment: Using microfiltration membranes with pore sizes of 0.1–0.2 μm (as in Examples 1 and 5), particulate matter in the feed solution is effectively removed, providing protection for subsequent ion exchange resins and nanofiltration membranes and avoiding clogging and contamination.

[0095] S2 Ion Exchange Purification: As in Examples 6-8, a three-stage ion exchange system consisting of cations, anions, and a mixed bed was used, and the flow rate was controlled within the preferred range of 4-7 BV / h, achieving deep removal of ionic impurities. The purification effect of Control Examples 4 and 5 (flow rate too high) decreased, indicating that the parameters of this step have a crucial impact on the overall purification efficiency.

[0096] S3 Nanofiltration Purification: A two-stage (Example 1) or three-stage (Example 4) nanofiltration system was used to achieve efficient retention of residual small molecule impurities at low temperatures (20–30 °C). In contrast, Control Example 3 (using only single-stage nanofiltration, with excessively high operating pressure (5.0 MPa) and membrane molecular weight cutoff (320 Da)) resulted in Na... + K + Plasma impurity content exceeded the standard, especially Cl. - and SO4 2- The concentration increased significantly, with particulate matter also increasing significantly to 81 particles / mL, demonstrating the effectiveness of this step in removing ionic impurities. However, neither ion exchange (S2) nor nanofiltration (S3) alone was sufficient to remove ionic and particulate impurities from the hydroxylamine aqueous solution to within the standard limits. A synergistic effect of both ion exchange and nanofiltration is necessary to achieve the purification goal.

[0097] In summary, S1 creates the conditions for subsequent purification, S2 is the main step for removing ionic impurities, and S3 plays a final purification role. S1 to S3 together constitute a whole, which contrasts with the poor purification effect of Control Example 2 (simplified system). Among them, Example 1 is the preferred embodiment of this application because it achieves the best balance between purification effect and efficiency.

[0098] Experimental Example 2:

[0099] Experimental methods: The metal ion content before and after nanofiltration was tested using ICP-MS, and the particle content was measured using a Rion AF19 filtration instrument. The product flux, impurity rejection rate, and product recovery rate could be calculated. The product flux, rejection rate, and recovery rate results of Examples 1, 9-11, and Control Example 6 are shown in Table 7.

[0100] Table 7. Comparison of nanofiltration purification performance of Examples 1, 9-11 and Control Example 6

[0101]

[0102] As shown in Table 7, in Example 1, hydroxylamine aqueous solution was purified to meet the requirements of electronically pure reagents through two-stage nanofiltration at an operating temperature of 25°C. Examples 1 and 9-11 show that, within a low temperature range of 20-30°C and an operating pressure of 1.0-3.0 MPa, the system achieved a product throughput of 15.2-33.5 L / m²·h and a recovery rate of 85.3%-93.5% while maintaining a high impurity rejection rate (98.5%-99.9%). In contrast, the high-pressure operation of Control Example 6 at 5.0 MPa negatively impacted system performance, resulting in low rejection and recovery rates. This demonstrates that the combination of a pressure range of 1.0-3.0 MPa and low-temperature operation employed in this application achieves highly efficient purification.

[0103] In summary, this application achieves a high product recovery rate (over 85.3%) while ensuring a high impurity rejection rate (over 98.5%).

[0104] The above-described embodiments are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for preparing an electronic-grade hydroxylamine aqueous solution, characterized in that, The method includes the following steps: S1 microfiltration pretreatment: Industrial-grade 50% hydroxylamine aqueous solution is passed through a polyvinylidene fluoride microfiltration membrane with a pore size of 0.1–0.2 μm at a temperature of 15–25 °C and an operating pressure of 0.1–0.5 MPa to remove suspended particles and colloidal substances; S2 ion exchange purification: The filtrate obtained from S1 is sequentially passed through at least one cation exchange column packed with a strong acidic cation exchange resin, at least one anion exchange column packed with a strong basic anion exchange resin, and a mixed bed exchange column packed with a mixed ion exchange resin; the operating temperature is maintained at 15-25 °C, and the flow rate is controlled at 4-7 BV / h to deeply remove various metal ions and anion impurities. S3 Nanofiltration Purification: The ion-exchanged hydroxylamine aqueous solution is passed through a nanofiltration system using a polyamide composite membrane with a molecular weight cutoff of 150 or higher. The operating pressure is 1.0–4.0 MPa and the temperature is 20–30 °C to obtain purified hydroxylamine aqueous solution.

2. The method according to claim 1, characterized in that, The strongly acidic resin is a sulfonic acid-modified styrene-divinylbenzene copolymer resin with a crosslinking degree of 8-12%.

3. The method according to claim 1, characterized in that, The strongly alkaline resin is a quaternary ammonium-modified styrene-divinylbenzene copolymer resin with a crosslinking degree of 6-10%.

4. The method according to claim 1, characterized in that, The mixed ion exchange resin is composed of a mixture of a strongly acidic cation exchange resin and a strongly basic anion exchange resin.

5. The method according to claim 4, characterized in that, In the mixed ion exchange resin, the volume ratio of cation exchange resin to anion exchange resin is 1:1.5 to 1:2.

0.

6. The method according to claim 1, characterized in that, The nanofiltration system adopts a two-stage series design. The first-stage nanofiltration membrane has a molecular weight cutoff of 200-300 Da, and the second-stage nanofiltration membrane has a molecular weight cutoff of more than 150 Da.

7. The method according to claim 1, characterized in that, It also includes the step of adding a stabilizer to an aqueous hydroxylamine solution after S2 ion exchange purification and before S3 nanofiltration purification, wherein the stabilizer is one of hydroxyurea or aminoquinoline.

8. The method according to claim 7, characterized in that, The amount of stabilizer added is 0.01 to 0.05 wt%.

9. The method according to claim 1, characterized in that, The microfiltration, ion exchange, and nanofiltration steps are all performed under inert gas protection.

10. The method according to claim 1, characterized in that, The final electronic-grade hydroxylamine aqueous solution has a metal ion content of less than 10 ppt, a particle size (≥0.1 μm) of less than 50 particles / mL, and a resistivity of 18.2 MΩ·cm.

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