Process for the preparation of spherical submicron silica

Abstract

The present application relates to the technical field of sub-micron material preparation, and particularly relates to a preparation method of spherical sub-micron silicon dioxide. The preparation method comprises the following steps: mixing water, mixed alkali and photovoltaic degraded silicon powder, heating and reacting to obtain a sodium silicate solution; synchronously adding the sodium silicate solution and a precipitant into an aqueous solution containing a surfactant to perform a precipitation reaction, and obtaining a milky white suspension; aging the milky white suspension at 30-75 DEG C for 12-48h; and sequentially performing solid-liquid separation, washing, drying and calcination treatment on the aged product to obtain the spherical sub-micron silicon dioxide. The present application solves the problems of uneven morphology and difficult structure regulation caused by local supersaturation in the traditional precipitation method.

Description

Technical Field

[0001] This invention relates to the field of submicron material preparation technology, and specifically to a method for preparing spherical submicron silica. Background Technology

[0002] Spherical submicron silica has irreplaceable application value in high-end composite materials, semiconductor packaging, drug sustained release, catalysis and energy storage due to its high specific surface area, good chemical stability, functionalizable surface and excellent dispersibility.

[0003] Currently, the industrial preparation of submicron silica mainly involves gas-phase and liquid-phase methods. Gas-phase methods (such as flame hydrolysis of silicon tetrachloride) produce products with high purity and good dispersibility, but suffer from serious drawbacks such as high energy consumption, expensive raw materials, complex equipment, and the generation of corrosive byproducts. Liquid-phase precipitation methods (usually using sodium silicate as the silicon source and acid precipitation) are considered the most scalable route due to their lower cost. However, traditional precipitation methods have two major technical bottlenecks: First, the typical method of adding acid dropwise into the silicate solution leads to a sudden drop in local pH, instantaneous supersaturation of silicic acid, uneven nucleation and growth, making it difficult to obtain monodisperse spherical particles, often resulting in amorphous or agglomerated particles; second, there is a lack of effective means to control the internal structure of the final product. Existing technologies mostly rely on complex template agents or subsequent etching to create pores, which are cumbersome, costly, and difficult to coordinate with particle size control.

[0004] In recent years, the use of degraded or waste silicon powder generated by the photovoltaic and semiconductor industries as a silicon source to prepare silica has achieved high-value utilization of solid waste, which aligns with the concept of green manufacturing. However, how to directly prepare high-end spherical submicron silica with precisely customizable morphology, particle size, and internal structure using inexpensive raw materials and a simple, controllable process remains a critical technical challenge. In particular, optimizing the mixing and mass transfer during the precipitation process from a reaction engineering perspective to achieve uniform nucleation and discovering the regulatory mechanisms of simple post-processing parameters on the microstructure are key to solving these challenges. Summary of the Invention

[0005] To address the problems of uneven nucleation, poor morphology control, and complex structure regulation steps in traditional precipitation methods, this invention aims to provide a simple, precisely controlled method for preparing high-purity spherical submicron silica using photovoltaic-grade silicon powder as raw material. This invention achieves synergistic and integrated control of product particle size and internal structure by innovating the precipitation process and utilizing aging conditions.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] On one hand, the present invention provides a method for preparing spherical submicron silica, the method comprising the following steps: S1. Silicon source dissolution: Water, mixed alkali and photovoltaic degradation silicon powder are mixed and heated at 60~80℃ for 4~8h to obtain sodium silicate solution; the mixed alkali is composed of sodium hydroxide (NaOH), potassium hydroxide (KOH) and tetramethylammonium hydroxide (TMAH); S2. Precipitation and pelleting: The sodium silicate solution obtained in step S1 and the precipitant are simultaneously added dropwise to an aqueous solution containing a surfactant to carry out the precipitation reaction, resulting in a milky white suspension; the pH range of the reaction system is adjusted to 3~9 by adjusting the dropping rate of the sodium silicate solution and the precipitant. This invention abandons the traditional single-sided dropwise addition and adopts a dual-liquid synchronous dropwise addition process. The sodium silicate solution and precipitant obtained in step S1 are simultaneously and uniformly added to a reactor pre-filled with an aqueous solution containing surfactant through an independent metering and delivery device. The reactor is equipped with a precision pH meter and a stirrer. By monitoring the pH value of the reaction solution in real time and controlling the dropwise rate of the two raw material solutions (sodium silicate solution and precipitant) based on feedback, the pH value of the entire precipitation reaction process is precisely stabilized within a preset target range. This process ensures that silicate ions and hydrogen ions meet uniformly and slowly in the entire reaction system, realizing homogeneous nucleation and uniform growth, which is the key to obtaining monodisperse spherical precursors. S3. Structural regulation and aging: The milky white suspension obtained in step S2 is aged at 30~75℃ for 12~48h; This invention involves aging the homogeneous milky white suspension obtained in step S2 at a specific temperature. The invention reveals that aging temperature has a decisive influence on the internal structure and dispersibility of the final product. Aging at lower temperatures (30-60°C) primarily yields dense, solid spheres (solid spherical submicron silica). However, aging at higher temperatures (60-75°C) results in thermally driven recombination and Ostwald ripening of the gel network, tending to form porous spheres with abundant internal pores (spherical submicron silica with a porous internal structure), and significantly improving the monodispersity between particles. S4. Post-processing: The product aged in step S3 is subjected to solid-liquid separation, washing, drying and calcination in sequence to obtain the spherical submicron silica. In step S4, the washing is performed by alternating ultrasonic washing with pure water and ethanol, the drying is performed by vacuum drying at 60~80℃ for 12~24h, and the calcination is performed by heating to 500~700℃ at a rate of 5~10℃ / min under an inert atmosphere and holding at that temperature for 2~4h.

[0008] This invention involves solid-liquid separation of the aged product and alternating ultrasonic washing with pure water and ethanol to thoroughly remove impurity ions and surfactants; followed by vacuum drying and calcination under an inert atmosphere to obtain the final high-purity spherical submicron silica product.

[0009] The present invention controls the particle size of the product by adjusting the pH value in step S2. Under the same aging temperature, the higher the pH value of the reaction system, the larger the average particle size of the obtained spherical submicron silica.

[0010] This invention regulates the internal structure and monodispersity of the product by adjusting the aging temperature in step S3. When the aging temperature is 30~60℃, solid spherical submicron silica is obtained; when the aging temperature is 60~75℃, spherical submicron silica with a porous internal structure is obtained, and the monodispersity is improved.

[0011] Preferably, before step S2, a solution purification step is included, which includes: introducing an inert gas into the reaction system of the heating reaction in step S1 and simultaneously performing ultrasonic treatment, followed by filtration to further remove trace metal impurities, ensuring that the product purity is ≥99.99%, and obtaining a purified sodium silicate solution.

[0012] Preferably, in step S2, the sodium silicate solution and the precipitant are added dropwise over a period of 30 to 120 minutes; the precipitation reaction conditions are: a reaction temperature of 20 to 40°C, a stirring speed of 400 to 600 r / min, and a pH range of 3 to 5 for the reaction system.

[0013] Preferably, in step S2, the precipitant is selected from any one of hydrochloric acid, citric acid, and sulfuric acid, and the concentration of the precipitant is 0.5~6 mol / L; the surfactant is selected from any one of hexadecyltrimethylammonium bromide (CTAB), polyethylene glycol 20000 (PEG-20000), and polyvinylpyrrolidone (PVP), and the mass concentration of the surfactant in the aqueous solution is 0.1~5%. The type of surfactant affects the spherical formation of submicron silica in this invention.

[0014] Preferably, in step S1, the mass ratio of water, mixed alkali, and photovoltaic downgraded silicon powder is 17~25:1:0.7~1.4; the mass ratio of sodium hydroxide, potassium hydroxide, and tetramethylammonium hydroxide is 0.8~1.2:0.8~1.2:0.2~0.5. When sodium hydroxide, potassium hydroxide, and tetramethylammonium hydroxide in the mixed alkali are compounded according to this specific mass ratio, the silicon powder can be efficiently dissolved and initially purified.

[0015] It should be noted that this invention reveals the independent control of two key process parameters, specifically: (1) Reaction pH value mainly controls particle size: Under the same aging conditions, by adjusting the pH value in step S2, the particle size of the final spherical particles can be effectively controlled. The higher the pH value, the slower the nucleation rate, and the more abundant the material during the growth period, the larger the particle size (e.g., 200-500nm) tends to be generated; the lower the pH value, the more rapid the nucleation, and the smaller the particle size (e.g., 100-150nm) is generated. (2) Aging temperature mainly controls structure and dispersibility: Under the same pH precipitation conditions, by adjusting the aging temperature in step S3, the internal structure (solid vs. porous) and monodispersity of the particles can be independently controlled. This invention confirms that high-temperature aging is the key to porous structure and excellent dispersibility.

[0016] On the other hand, the present invention provides spherical submicron silica prepared by the preparation method described herein, wherein the spherical submicron silica has a purity ≥99.99%, an average particle size of 100nm~1μm, and an internal structure that is solid or porous.

[0017] In another aspect, the present invention provides the application of spherical submicron silicon dioxide in semiconductor packaging materials, catalyst supports, drug delivery systems, and / or lithium battery separator coatings.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention employs a simultaneous two-liquid dropwise addition process, adding sodium silicate solution and a precipitant dropwise simultaneously to an aqueous solution containing a surfactant. A pH meter is used for real-time monitoring and feedback control, ensuring the pH of the reaction system remains precisely stable within a preset range, achieving uniform nucleation and yielding a precursor with high sphericity and narrow particle size distribution. Furthermore, by controlling the aging temperature, the assembly behavior of the precursor gel network is regulated, ultimately resulting in high-purity spherical submicron silica with a tunable internal structure (solid or porous) and good monodispersity after washing, drying, and calcination. This invention features a green and precisely controlled process, solving the problems of uneven morphology caused by localized oversaturation and difficulties in structural control inherent in traditional precipitation methods. The product has broad application prospects in high-end packaging, catalysis, and biomedicine. Specifically: (1) The present invention adopts synchronous dripping and real-time precise pH control technology, which fundamentally solves the problem of local supersaturation, realizes true homogeneous precipitation, lays a solid foundation for the preparation of monodisperse spherical particles, and achieves a significant improvement in nucleation uniformity.

[0019] (2) This invention is the first to clearly define a distinct and independent control mechanism for pH-controlled particle size and temperature-controlled structure in the same simple system. By adjusting only two easily monitored physical parameters (pH and temperature), it is possible to customize products in various forms, such as small solid spheres and large porous spheres, without the need for complex formula changes or post-processing. The process is robust and achieves precise control of particle size and structure in a coordinated manner.

[0020] (3) This invention uses photovoltaic downgraded silicon powder as raw material, which is low in cost and environmentally friendly. Through the precise control process of this invention, this low-value raw material can be transformed into high-purity (≥99.99%), high-performance spherical submicron silicon dioxide, which meets the requirements of high-end fields such as semiconductors and biomedicine, and realizes extremely high added value utilization of waste.

[0021] (4) The entire process of this invention is a typical one-pot liquid phase process with mild reaction conditions (atmospheric pressure and low temperature), simple equipment requirements, and key control parameters (pH and temperature) are easy to automate, thus having good prospects for large-scale production. Attached Figure Description

[0022] Figure 1 This is an SEM image of the product prepared in Example 1 of the present invention.

[0023] Figure 2 This is an SEM image of the product prepared in Example 2 of the present invention.

[0024] Figure 3 This is an SEM image of the product prepared in Example 3 of the present invention.

[0025] Figure 4 This is an SEM image of the product prepared in Example 4 of the present invention.

[0026] Figure 5 This is an SEM image of the product prepared in Example 5 of the present invention.

[0027] Figure 6 SEM image of the product prepared for Comparative Example 1.

[0028] Figure 7 SEM image of the product prepared for Comparative Example 2. Detailed Implementation

[0029] The technical solution of the present invention will be described below with reference to embodiments. However, the present invention is not limited to the following embodiments. Unless otherwise specified, the experimental methods and detection methods described in each embodiment are conventional methods; unless otherwise specified, the reagents and materials can be purchased commercially.

[0030] Example 1: Preparation of small-diameter solid spheres by low pH-low temperature aging S1. Add 200g water, 10g mixed alkali (NaOH:KOH:TMAH=1:1:0.3, mass ratio) and 10g photovoltaic degradation silicon powder to a reactor and stir at 70℃ for 6h. After the reaction is completed, nitrogen gas is introduced into the reaction system and ultrasonic treatment is performed (power 150W, 50min). Then, the mixture is filtered through a 0.1μm filter to obtain a high-purity sodium silicate solution. S2. In another reactor equipped with a stirrer, pH meter, and dual-dropper device, add 200g of an aqueous solution containing 1% (mass concentration) PEG-20000 as the reaction medium; start stirring (500r / min) and control the temperature at 25℃; add all the sodium silicate solution obtained in step S1 and 200mL of 1mol / L hydrochloric acid solution simultaneously using two peristaltic pumps; use a PID controller to dynamically fine-tune the dropping rate of the sodium silicate solution and hydrochloric acid solution according to the pH meter feedback signal (set pH=3) to keep the pH of the reaction solution stable at 3.0±0.1, and control the total dropping time at 60min; after the dropping is completed, continue stirring for 1h to obtain a uniform milky white suspension; S3. Transfer the milky white suspension obtained in step S2 to a constant temperature water bath and let it stand and age at 30°C for 24 hours; S4. Centrifuge the material after aging in step S3. Wash the precipitate with pure water and anhydrous ethanol three times each by ultrasonication. Then dry it in a vacuum drying oven at 70°C for 18 hours. Finally, place the dried powder in a tube furnace and heat it to 600°C at 5°C / min under nitrogen protection. Hold it at that temperature for 2 hours and then cool it naturally to obtain the final product (spherical submicron silica).

[0031] Characterization: The final product is a white, fluffy powder; SEM ( Figure 1 The particles were solid submicron spheres with excellent sphericity, with an average particle size of about 100 nm and uniform distribution. ICP-MS analysis showed that the purity of the spherical submicron silica was >99.995%.

[0032] Example 2: Preparation of small-diameter solid spheres by high pH-low temperature aging S1. Add 200g water, 10g mixed alkali (NaOH:KOH:TMAH=1:1:0.3, mass ratio) and 10g photovoltaic degradation silicon powder to a reactor and stir at 70℃ for 6h. After the reaction is completed, nitrogen gas is introduced into the reaction system and ultrasonic treatment is performed (power 150W, 50min). Then, the mixture is filtered through a 0.1μm filter to obtain a high-purity sodium silicate solution. S2. In another reactor equipped with a stirrer, pH meter, and dual-dropper device, add 200g of an aqueous solution containing 1% (mass concentration) polyvinylpyrrolidone as the reaction medium; start stirring (500r / min) and control the temperature at 25℃; add all the sodium silicate solution obtained in step S1 and 200mL of 1mol / L citric acid solution simultaneously using two peristaltic pumps; use a PID controller to dynamically fine-tune the dropping rate of sodium silicate solution and citric acid solution according to the pH meter feedback signal (set pH=9) to keep the pH of the reaction solution stable at 3.0±0.1, and control the total dropping time at 60min; after the dropping is completed, continue stirring for 1h to obtain a uniform milky white suspension; S3. Transfer the milky white suspension obtained in step S2 to a constant temperature water bath and let it stand and age at 30°C for 24 hours; S4. Centrifuge the material after aging in step S3. Wash the precipitate with pure water and anhydrous ethanol three times each by ultrasonication. Then dry it in a vacuum drying oven at 70°C for 18 hours. Finally, place the dried powder in a tube furnace and heat it to 600°C at 5°C / min under nitrogen protection. Hold it at that temperature for 2 hours and then cool it naturally to obtain the final product (spherical submicron silica).

[0033] Characterization: The final product is a white, fluffy powder; SEM ( Figure 2 The particles were solid submicron spheres with excellent sphericity, with an average particle size of about 100 nm and uniform distribution. ICP-MS analysis showed that the purity of the spherical submicron silica was >99.995%.

[0034] Example 3: Preparation of small-diameter solid spheres by high pH-low temperature aging S1. Add 200g water, 10g mixed alkali (NaOH:KOH:TMAH=1:1:0.3, mass ratio) and 10g photovoltaic degradation silicon powder to a reactor and stir at 70℃ for 6h. After the reaction is completed, nitrogen gas is introduced into the reaction system and ultrasonic treatment is performed (power 150W, 50min). Then, the mixture is filtered through a 0.1μm filter to obtain a high-purity sodium silicate solution. S2. In another reactor equipped with a stirrer, pH meter, and dual-dropper device, add 200g of an aqueous solution containing 1% (mass concentration) hexadecyltrimethylammonium bromide as the reaction medium; start stirring (500r / min) and control the temperature at 25℃; add all the sodium silicate solution obtained in step S1 and 200mL of 1mol / L sulfuric acid solution simultaneously using two peristaltic pumps; use a PID controller to dynamically fine-tune the dropping rate of the sodium silicate solution and sulfuric acid solution based on the pH meter feedback signal (set pH=9) to keep the pH of the reaction solution stable at 3.0±0.1, and control the total dropping time at 60min; after the dropping is completed, continue stirring for 1h to obtain a uniform milky white suspension; S3. Transfer the milky white suspension obtained in step S2 to a constant temperature water bath and let it stand and age at 30°C for 24 hours; S4. Centrifuge the material after aging in step S3. Wash the precipitate with pure water and anhydrous ethanol three times each by ultrasonication. Then dry it in a vacuum drying oven at 70°C for 18 hours. Finally, place the dried powder in a tube furnace and heat it to 600°C at 5°C / min under nitrogen protection. Hold it at that temperature for 2 hours and then cool it naturally to obtain the final product (spherical submicron silica).

[0035] Characterization: The final product is a white, fluffy powder; SEM ( Figure 3 The particles were solid submicron spheres with excellent sphericity, with an average particle size of about 100 nm and uniform distribution. ICP-MS analysis showed that the purity of the spherical submicron silica was >99.994%.

[0036] Example 4: Preparation of large-diameter solid spheres by high pH-low temperature aging The steps are exactly the same as in Example 1, except that the target pH control value in step S2 is changed from 3 to 9.

[0037] Characterization: SEM ( Figure 4 The results showed that the final product was still a regular solid sphere, but the average particle size increased significantly to about 300 nm; ICP-MS analysis showed that the purity of the spherical submicron silica was >99.995%.

[0038] Example 5: Preparation of large-size porous spheres by high pH-high temperature aging The steps are exactly the same as in Example 1, except that the target pH control value in step S2 is changed from 3 to 9; the aging temperature in step S3 is changed from 30℃ to 75℃, and the aging time is extended to 36h.

[0039] Characterization: SEM ( Figure 5 The results show that the final product particles are well-spherical and contain a large number of submicron-sized pores, which is a typical porous structure.

[0040] Comparative Example 1: Traditional single-sided dripping process S1. Same as Example 1; S2. The sodium silicate solution obtained in step S1 was mixed with 200g of an aqueous solution containing 1% (mass concentration) PEG-20000 in a reactor beforehand. Then, under stirring (500r / min), 200mL of 1mol / L hydrochloric acid solution was added dropwise to the mixture unidirectionally; the pH was not controlled during the addition, and the pH value was observed to decrease rapidly from the initial alkalinity and fluctuate drastically. S3. Same as Example 1; S4. Same as Example 1.

[0041] Characterization: SEM ( Figure 6 The results show that the final product has an extremely irregular morphology, consisting mostly of amorphous aggregates and a small number of incomplete spherical particles, with a very wide particle size distribution. This demonstrates that uneven nucleation caused by localized supersaturation is the main reason for the uncontrolled morphology.

[0042] Comparative Example 2: No aging process The steps are the same as in Example 1, but step S3 is omitted. After the reaction in step S2 is completed, step S4 is performed directly.

[0043] Characterization: SEM ( Figure 7 The results showed that the sphericity of the final product was acceptable, but the particle size distribution was significantly widened, and the particle surface was rough. Some particles cracked after calcination. This indicates that the aging process is crucial for the stabilization and homogenization of the gel network and the final formation of a complete and uniform spherical structure.

[0044] As can be seen, this invention ensures uniform nucleation during the precipitation stage through simultaneous dropwise addition and precise pH control, resulting in spherical precursors. Furthermore, by controlling the aging temperature, the gel structure of the precursor is reshaped, ultimately yielding high-purity spherical submicron silica with controllable internal structure (solid / porous) and monodispersity. This invention perfectly combines raw material cost advantages with high-end product performance, offering strong process controllability and significant innovative and industrialization value.

[0045] The final products obtained from Examples 1-5 and Comparative Examples 1-2 were subjected to ICP-MS (Inductively Coupled Plasma Mass Spectrometry) to detect the concentration of various metal impurity elements in the final products, in ppm (parts per million). The results are shown in Table 1.

[0046] Table 1. Impurity data of the final product

[0047] As shown in Table 1, on the one hand, the total content of each impurity metal element in all samples is extremely low (generally in the range of 0-0.3 ppm), and the content of individual impurities is mostly below 0.1 ppm. This indicates that the preparation method of the present invention can effectively remove metal impurities from the raw silicon powder and successfully convert industrial-grade silicon powder into ultra-high purity silicon dioxide. On the other hand, the impurity spectra of Examples 1-5 are generally very clean and similar; although most impurities in Comparative Example 1 are also extremely low, Al 0.1 ppm was found while Al was not detected in other samples; this suggests that the traditional non-uniform precipitation process may have introduced trace aluminum contamination from the equipment or environment during the process, or that the encapsulation / entrainment behavior of specific impurities is different, proving that the synchronous dripping and pH control process of the present invention is superior in ensuring purity; Comparative Example 2 showed higher levels of Ca 0.3 ppm and Na 0.3 ppm. This indicates that the aging step not only regulates the structure but also helps the further diffusion and precipitation of impurity ions, making them easier to remove in subsequent washing. Omitting aging will result in slightly higher impurity residues. On the other hand, while changing the pH and aging temperature to regulate the particle size and internal structure of the product, the impurity content of the final product remained at the same level, without introducing significant purity fluctuations due to the adjustment of process parameters. This shows that the pH-controlled particle size and temperature-controlled structure regulation mechanism is independent and robust, and will not sacrifice product purity, thus meeting the requirements of high-end applications for consistent material performance.

[0048] It should be understood that the disclosed invention is not limited to the specific methods, schemes, and substances described, as these are all subject to variation. It should also be understood that the terminology used herein is for the purpose of describing specific embodiments only and is not intended to limit the scope of the invention, which is limited only by the appended claims.

Claims

1. A method for preparing spherical submicron silica, characterized in that, The preparation method includes the following steps: S1. Silicon source dissolution: Water, mixed alkali, and photovoltaic degradation silicon powder are mixed and heated to react, resulting in a sodium silicate solution; the mixed alkali is composed of sodium hydroxide, potassium hydroxide, and tetramethylammonium hydroxide; S2. Precipitation and pelleting: The sodium silicate solution obtained in step S1 and the precipitant are simultaneously added dropwise to an aqueous solution containing a surfactant to carry out the precipitation reaction, resulting in a milky white suspension; the pH range of the reaction system is adjusted to 3~9 by adjusting the dropping rate of the sodium silicate solution and the precipitant. S3. Structural regulation and aging: The milky white suspension obtained in step S2 is aged at 30~75℃ for 12~48h; S4. Post-processing: The product aged in step S3 is subjected to solid-liquid separation, washing, drying and calcination in sequence to obtain the spherical submicron silica. In step S2, the precipitant is selected from any one of hydrochloric acid, citric acid and sulfuric acid, and the concentration of the precipitant is 0.5~6 mol / L; the surfactant is selected from any one of cetyltrimethylammonium bromide, polyethylene glycol 20000 and polyvinylpyrrolidone, and the mass concentration of the surfactant in the aqueous solution is 0.1~5%.

2. The preparation method according to claim 1, characterized in that, Before step S2, a solution purification step is also included, which includes: introducing an inert gas into the reaction system of the heating reaction in step S1 and simultaneously performing ultrasonic treatment, followed by filtration to obtain a purified sodium silicate solution.

3. The preparation method according to claim 1, characterized in that, In step S2, The sodium silicate solution and precipitant are added dropwise over a period of 30 to 120 minutes. The conditions for the precipitation reaction are: reaction temperature of 20~40℃ and stirring speed of 400~600r / min; The pH range of the reaction system is 3 to 5.

4. The preparation method according to claim 1, characterized in that, In step S1, The mass ratio of water, mixed alkali, and photovoltaic downgraded silicon powder is 17~25:1:0.7~1.4; The mass ratio of sodium hydroxide, potassium hydroxide and tetramethylammonium hydroxide is 0.8~1.2:0.8~1.2:0.2~0.

5.

5. The preparation method according to claim 1, characterized in that, In step S1, the heating reaction conditions are: temperature 60~80℃, time 4~8h.

6. The preparation method according to claim 1, characterized in that, In step S4, the washing is performed by alternating ultrasonic washing with pure water and ethanol, and the drying is performed by vacuum drying at 60~80℃ for 12~24h.

7. The preparation method according to claim 1, characterized in that, In step S4, the calcination is carried out under an inert atmosphere, with the temperature increased to 500-700°C at a rate of 5-10°C / min, and held for 2-4 hours.

8. The spherical submicron silica prepared by the preparation method according to any one of claims 1-7, characterized in that, The spherical submicron silica has a purity of ≥99.99%, an average particle size of 100nm~1μm, and an internal structure that is solid or porous.

9. The application of the spherical submicron silica of claim 8 in semiconductor packaging materials, catalyst supports, drug delivery systems and / or lithium battery separator coatings.

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