A method for preparing silicon dioxide based on liquid-liquid two-phase interface method

Abstract

The present invention provides a method for preparing silica based on a liquid-liquid two-phase interface method, comprising the following steps: S1, providing an organic solution and water, wherein the organic solution includes an organic solvent and silicon tetrachloride; the volume ratio of the water to the organic solution is not less than 1 / 50; the molar ratio of the water to the silicon tetrachloride is not less than 4:1; the organic solvent is insoluble or slightly soluble in the water; S2, mixing the water and the organic solution to obtain a first treatment liquid; S3, aging the first treatment liquid to obtain a second treatment liquid; the second treatment liquid comprises an aqueous phase and an organic phase; S4, separating a primary silica product from the second treatment liquid; and calcining the primary silica product to obtain a silica product. The present invention prepares silica nanopowders with a high degree of spheroidization based on silicon tetrachloride and the liquid-liquid two-phase interface method, and the reaction is mild and low-risk.

Description

Technical Field

[0001] The present invention relates to the field of silicon dioxide preparation, and in particular to a method for preparing silicon dioxide based on a liquid-liquid two-phase interface method. Background Art

[0002] Silica is an important chemical material. Mesoporous silica nanopowders have a unique structure and excellent properties. Due to their large specific surface area, large pore structure, good biocompatibility and biodegradability, they have attracted much attention in the fields of materials, chemical engineering and biomedicine. The nanoparticles of mesoporous silica nanopowders have many pores with a diameter of 2-50nm on their surface, which enables them to carry various substances, build efficient medium transmission systems, and improve reaction efficiency.

[0003] Silicon tetrachloride is a colorless, transparent, low-viscosity liquid at room temperature that is flammable and asphyxiating. Its active chemical properties have led to its widespread use in the synthesis of organosilicon compounds, the production of semiconductor materials, and optical fiber manufacturing. There are three main methods for processing silicon tetrachloride: First, hydrogenation and reduction of silicon tetrachloride to produce trichlorosilane, but current production technology results in low conversion rates and high costs. Second, silicon tetrachloride can be made into a variety of organosilicon compounds, but this method, due to secondary pollution and limited consumption, has limitations in terms of the silicon tetrachloride produced during the production process. Third, silicon tetrachloride can be used as a raw material to produce silicon dioxide, but conventional vapor-phase production requires high temperatures and pressures, placing stringent demands on equipment.

[0004] The silicon tetrachloride liquid phase method can produce silicon dioxide based on silicon tetrachloride, but liquid silicon tetrachloride and water will react violently, which not only increases the risk of production but also has poor product morphology. In existing processes, when producing silicon dioxide based on the liquid phase method, the Stöber method, precipitation method, and sol-gel method are usually used; among them, the Stöber method mainly uses tetraethyl orthosilicate (TEOS) to hydrolyze under alkaline conditions to produce silicic acid, and the dehydration condensation between silicic acid molecules forms a Si-O-Si network structure, which gradually grows into microspheres; this method has high raw material costs, requires strict temperature control, and has a long reaction time. In addition, the preparation of TEOS is an esterification reaction between silicon tetrachloride and ethanol in the presence of a catalyst, which is more complicated than the direct use of silicon tetrachloride to produce silica microspheres. In addition, the precipitation method and the sol-gel method also have disadvantages such as easy introduction of impurities and long production cycles.

[0005] In view of this, it is necessary to provide a method for preparing silicon dioxide based on the liquid-liquid two-phase interface method to solve or at least alleviate the technical problems of how to gently prepare silicon dioxide through silicon tetrachloride and improve the morphology of silicon dioxide, as well as how to overcome the introduction of impurities and complex process flow. Summary of the Invention

[0006] The main purpose of the present invention is to provide a method for preparing silicon dioxide based on the liquid-liquid two-phase interface method, aiming to solve the above-mentioned technical problems of how to gently prepare silicon dioxide from silicon tetrachloride and improve the morphology of silicon dioxide, as well as how to overcome the introduction of impurities and complex process flow.

[0007] To achieve the above object, the present invention provides a method for preparing silicon dioxide based on a liquid-liquid two-phase interface method, comprising the steps of:

[0008] S1, providing an organic solution and water, wherein the organic solution comprises an organic solvent and silicon tetrachloride;

[0009] The volume ratio of the water to the organic solution is not less than 1 / 50; the molar ratio of the water to the silicon tetrachloride is not less than 4:1; the organic solvent is insoluble or slightly soluble in the water;

[0010] S2, mixing the water and the organic solution to obtain a first treated liquid;

[0011] S3, aging the first treatment liquid to obtain a second treatment liquid; the second treatment liquid comprises an aqueous phase and an organic phase;

[0012] S4, separating and obtaining a primary silica product from the second treatment liquid.

[0013] Furthermore, the step S4 further includes: calcining the primary silica product to obtain a silica product; the calcination temperature is 500-1000° C.; the calcination time is 0.5-6 hours; the calcination is carried out in an oxygen-containing atmosphere; and the oxygen partial pressure during the calcination process is 20-50%.

[0014] Furthermore, the volume ratio of the water to the organic solution is 1:0.8-30; the molar ratio of the water to the silicon tetrachloride is 5-15:1; and the volume concentration of the silicon tetrachloride in the organic solution is not greater than 30%.

[0015] Furthermore, the organic solvent includes one or more of toluene and chloroform.

[0016] Furthermore, the water contains a cationic surfactant; the mass concentration of the cationic surfactant in the water is 0.5-25%; and the cationic surfactant includes hexadecyltrimethylammonium bromide.

[0017] Furthermore, the mixing is performed at a temperature of 15-40° C.; the mixing time is 0.5-5 min; and the mixing speed is 100-600 rpm.

[0018] Furthermore, in the step S2, before the mixing, the water is added dropwise to the organic solution; the rate of the addition is 5-50 mL / min; and stirring is performed during the addition.

[0019] Furthermore, the aging time is 3-12 hours; the aging temperature is 10-40° C.; and the aging is carried out under static conditions.

[0020] Furthermore, in step S4, the process of separating the primary silica product from the second treatment liquid includes: performing liquid-liquid separation on the aqueous phase and the organic phase in the second treatment liquid to obtain the aqueous phase and the organic phase; and performing solid-liquid separation on the aqueous phase to obtain the primary silica product.

[0021] Furthermore, in step S4, the process of separating the primary silica product from the second treatment liquid further includes: performing solid-liquid separation on the organic phase obtained after the liquid-liquid separation to obtain the primary silica product.

[0022] Compared with the prior art, the present invention has at least the following advantages:

[0023] The present invention can prepare a silicon dioxide product with excellent morphology and high spheroidization based on silicon tetrachloride. The reaction process is mild, and there is no liquid splashing, white smoke, obvious heat generation, or blockage. The present invention controls the reaction to occur at the two-phase interface while maintaining sufficient reaction through liquid-liquid interface reaction, effectively regulating the silicon dioxide generation process, and providing a basis for obtaining high-quality silicon dioxide products. In addition, the present invention has a short reaction time, a simple process, is not prone to the introduction of impurities, and the organic solvent can be recycled.

[0024] In the present invention, the volume ratio of water to organic solution is not less than 1 / 50, silicon tetrachloride is present in the organic solvent, the molar ratio of water to silicon tetrachloride is not less than 4:1, and the water and organic solution are mixed and then aged. Since the organic solvent dissolves silicon tetrachloride and forms a stable interface separation with excess water, a liquid-liquid interface reaction is carried out on this basis, which not only avoids the problem of violent reaction between liquid silicon tetrachloride and water phase, but also ensures a mild reaction while maintaining the morphology of silicon dioxide, thereby obtaining a high-quality nano-scale silicon dioxide product. The present invention prepares silicon dioxide based on a liquid-liquid two-phase interface method, which can reduce safety hazards, reduce process energy consumption, and improve the sphericity of the product. After introducing a cationic surfactant, the synthesis of mesoporous silicon dioxide nanopowder can be further achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0026] Figure 1 This is a TEM image of the silicon dioxide product in Example 1 of the present invention;

[0027] Figure 2 This is an SEM image of the silicon dioxide product in Example 2 of the present invention;

[0028] Figure 3 This is an SEM image of the silicon dioxide product in Example 3 of the present invention;

[0029] Figure 4 This is an SEM image of the silicon dioxide product in Example 4 of the present invention;

[0030] Figure 5 This is a SEM image of the silicon dioxide product in Example 5 of the present invention;

[0031] Figure 6 This is a SEM image of the silicon dioxide product in Example 6 of the present invention;

[0032] Figure 7 This is a SEM image of the silicon dioxide product in Example 7 of the present invention;

[0033] Figure 8 This is an SEM image of the silicon dioxide product in Comparative Example 1 of the present invention;

[0034] Figure 9 This is an SEM image of the silicon dioxide product at a certain viewing angle in Comparative Example 2 of the present invention;

[0035] Figure 10 This is an SEM image of the silicon dioxide product at another viewing angle in Comparative Example 2 of the present invention.

[0036] The realization of the objectives, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0037] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0038] Moreover, the technical solutions between the various embodiments of the present invention may be combined with each other, but this must be based on the fact that ordinary technicians in this field can implement them. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0039] When numerical ranges are given in the examples, it should be understood that unless otherwise specified herein, both endpoints of each numerical range and any value between the two endpoints may be used. Unless otherwise defined, all technical and scientific terms used herein are consistent with the prior art as understood by those skilled in the art and the description of the present invention. Any prior art methods, devices, and materials similar or equivalent to those described in the examples of the present invention may also be used to implement the present invention.

[0040] In the present invention, the spheroidization degree is expressed as roundness; the roundness is calculated by measuring the ratio of the longest axis length to the shortest axis length of the silica spheres through SEM and TEM images, with the value range being ≤1, where 1 represents a perfect sphere.

[0041] The present invention provides a method for preparing silicon dioxide based on a liquid-liquid two-phase interface method, comprising the steps of:

[0042] S1, providing an organic solution and water; the organic solution includes an organic solvent and silicon tetrachloride.

[0043] In the present invention, the volume ratio of the water to the organic solution is no less than 1 / 50; the molar ratio of the water to the silicon tetrachloride is no less than 4:1; and the organic solvent is insoluble or slightly soluble in the water. The water is added in excess to ensure sufficient reaction of the silicon tetrachloride and the stable formation of the liquid-liquid interface.

[0044] As a further illustration of the volume ratio of the water to the organic solution, the volume ratio of the water to the organic solution is 1:1-50. The volume ratio of the water to the organic solution may also be no less than 1 / 30; further, the volume ratio of the water to the organic solution is 1:0.8-30; further, the volume ratio of the water to the organic solution is 1:10-30 or 1:0.8-20.

[0045] As a further illustration of the molar ratio of the water to the silicon tetrachloride, the molar ratio of the water to the silicon tetrachloride is not less than 5:1; further, the molar ratio of the water to the silicon tetrachloride is 5-15:1; further, the molar ratio of the water to the silicon tetrachloride is 6-10:1.

[0046] In the present invention, the density of the organic solvent may be less than or greater than that of water; preferably, the density of the organic solvent is less than that of water.

[0047] In the organic solution of the present invention, the volume concentration of the silicon tetrachloride is not more than 30%; further, the volume concentration of the silicon tetrachloride is 1-30%, further 5-25% or 1-10% or 4-6%; the volume proportion of the organic solvent in the organic solution is not less than 70%.

[0048] It should be noted that the reaction rate of silicon tetrachloride with water is too fast, which not only leads to a significant increase in industrial hazards, but also affects the sphering of silicon dioxide. In the present invention, silicon tetrachloride is first placed in the organic solution, and then a stable liquid-liquid interface reaction is carried out based on the organic phase and the aqueous phase. This can not only effectively avoid the silicon dioxide hydrolysis process from being too fast, but also ensure the morphology of silicon dioxide.

[0049] In the present invention, the water contains a cationic surfactant; the mass concentration of the cationic surfactant in the water is 0.5-25%, further 1-25%, and even further 1-5%. In the present invention, the water containing the cationic surfactant is an aqueous solution of the cationic surfactant.

[0050] It should be noted that, compared with other types of surfactants, and compared with adding the surfactant directly to the organic solvent, the addition of the cationic surfactant to the water in the present invention can also significantly improve the performance of silica.

[0051] In the present invention, the organic solution is prepared from the silicon tetrachloride and the organic solvent; the organic solution is an organic mixed solution of the silicon tetrachloride and the organic solvent. In the present invention, the organic solvent in the organic solution includes one or more of toluene and chloroform; further, the organic solvent is toluene. It should be understood that in the early exploration process of the present invention, chloroform was first used to gently prepare the silicon dioxide product; however, since toluene is more stable than chloroform, considering the subsequent industrial implementation, the present invention continues to conduct exploratory experiments with toluene.

[0052] In the present invention, the aqueous solution is prepared from the cationic surfactant and deionized water; the aqueous solution is a template mixed solution obtained by mixing the cationic surfactant and deionized water; the cationic surfactant includes hexadecyltrimethylammonium bromide.

[0053] S2, mixing the water and the organic solution to obtain a first treated liquid.

[0054] In the present invention, the mixing is carried out at a temperature of 15-40° C.; further, the mixing is carried out at a temperature of 20-30° C.; the mixing is carried out at a rotation speed of 100-600 rpm, further 200-400 rpm.

[0055] In the present invention, the mixing time is 0.5-5 minutes, preferably 1-3 minutes, and further preferably 1.5-3 minutes. In this step, before the mixing, the aqueous solution is added dropwise to the organic solution; the addition rate is 5-50 mL / min, and further preferably 10-30 mL / min; and the organic solution is stirred during the addition process at a stirring speed of 100-600 rpm, and further preferably 200-400 rpm.

[0056] S3, aging the first treatment liquid to obtain a second treatment liquid.

[0057] In the present invention, the second treatment liquid comprises an aqueous phase and an organic phase; the aqueous phase is rich in silica, and the organic phase generally also contains some silica; in the experimental case of the present invention, the silica in the aqueous phase is collected.

[0058] In the present invention, the aging time is 3-12 hours; further, the aging time is 5-10 hours, and further 5-7 hours; the aging process is standing; the aging is carried out at 10-40°C or room temperature.

[0059] S4, separating and obtaining a primary silica product from the second treatment liquid.

[0060] The process of separating the primary silica product from the second treated liquid includes: performing liquid-liquid separation on the aqueous phase and the organic phase in the second treated liquid to obtain the aqueous phase and the organic phase; and performing solid-liquid separation on the aqueous phase to obtain the primary silica product. The liquid-liquid separation process includes: separating the aqueous phase and the organic phase in the second treated liquid using a separatory funnel to obtain the separated aqueous phase and the organic phase; and the solid-liquid separation process includes: filtering the aqueous phase obtained after the liquid-liquid separation to obtain the primary silica product.

[0061] To achieve sufficient collection of silica, the process of separating the primary silica product from the second treated liquid may further include: performing solid-liquid separation on the organic phase obtained after the liquid-liquid separation to obtain the primary silica product. The solid-liquid separation process includes filtering the organic phase obtained after the liquid-liquid separation to obtain the primary silica product.

[0062] In the present invention, the primary silicon dioxide product can be stored after drying for further processing; or it can be calcined to directly obtain a processed silicon dioxide product.

[0063] In the present invention, the step S4 further comprises: calcining the primary silica product to obtain a silica product, wherein the silica product is a silica nanopowder; in an embodiment in which the cationic surfactant is introduced, the silica product is a mesoporous silica nanopowder.

[0064] In the present invention, the calcination temperature is 500-1000°C, further 500-600°C; the calcination time is 0.5-6h, further 3-5h; the calcination is carried out in an oxygen-containing atmosphere, the calcination is oxygen-enriched calcination, the oxygen partial pressure during the calcination process is 20-50%, further 20-40%, and the rest is inert gas; in the present invention, the primary silica product is calcined under oxygen-containing conditions to further remove impurities and form a stable silica structure.

[0065] In the present invention, before the calcination, the primary silica product is washed; specifically, the solid separation is then repeatedly washed with deionized water and anhydrous ethanol to obtain the washed solid separation.

[0066] In the present invention, as an illustration of a preferred embodiment, the process of preparing silicon dioxide using a liquid-liquid two-phase interface method mainly includes: first dissolving silicon tetrachloride in an organic solvent that is insoluble in water, then dropping an aqueous solution containing a cationic surfactant, stirring, and reacting for a period of time to obtain silicon dioxide particles. The reaction formula in the present invention includes: 2H2O+SiCl4=SiO2+4HCl.

[0067] It should be noted that in the existing process of producing silica products using sodium silicate as a raw material (such as the precipitation method), since sodium silicate is rich in impurities such as Na, impurities need to be removed when preparing high-end products such as high-purity silica; however, the present invention does not introduce other substances, thus avoiding the problem of introducing impurities in the existing process, can prepare high-end silica products, and can also subsequently recover and reuse the organic solvent.

[0068] As an illustration of other prior arts, Chinese invention patent application publication number CN102515104A discloses a method for preparing hydrogen chloride and silicon dioxide by hydrolyzing silicon tetrachloride in an organic solvent. This patent application uses an organic solvent as a medium, adds water to a mixed solution prepared by silicon tetrachloride, an organic solvent, and a surfactant, and performs a hydrolysis reaction to generate hydrogen chloride gas and silicon dioxide.

[0069] Although this patent application also uses organic solvents and water and can prepare silicon dioxide in a mild manner; however, the maximum molar ratio of water to silicon tetrachloride recorded therein is 2.5:1, which just exceeds the stoichiometric ratio of the two, and its specification clearly states that excessive addition of water should be avoided; the interfacial stability of the interfacial reaction is not high, and it is difficult to achieve a stable interfacial reaction under excess water conditions of the present invention.

[0070] More importantly, the proportion of water in the embodiments is extremely low. According to actual verification, when the amount of water is extremely low, the morphology of silicon dioxide will be significantly lower than the morphology of the product in the present invention, and the quality of the product is not good, especially the spheroidization is very poor.

[0071] Furthermore, the sodium dodecylbenzenesulfonate (anionic surfactant) used in this patent application is not a preferred surfactant in the technical system of the present invention. Furthermore, the direct addition of the surfactant to the organic solvent in this application also affects the technical effects of the present invention to a certain extent. Therefore, this patent application merely provides another method for the mild preparation of silica. It does not consider the preparation of high-quality silica based on the liquid-liquid interface method, nor does it further explore the optimal industrial application conditions for this method.

[0072] The following are specific examples of the present invention:

[0073] Example 1

[0074] A method for preparing silicon dioxide based on a liquid-liquid two-phase interface method, comprising the following steps:

[0075] S1, dissolving liquid silicon tetrachloride in toluene to obtain an organic solution of silicon tetrachloride; the volume concentration of silicon tetrachloride in the organic solution is 5%.

[0076] Deionized water and cetyltrimethylammonium bromide (CTAB) are mixed to obtain an aqueous solution of cetyltrimethylammonium bromide; the mass concentration of cetyltrimethylammonium bromide in the aqueous solution is 2%.

[0077] S2, adding the above aqueous solution to the above organic solution at a rate of 20 mL / min, and stirring during and after the dropping process to obtain a first treatment liquid; the stirring process is carried out at a temperature of 25°C; the volume ratio of the aqueous solution to the organic solution is 1:19, the stirring rate is 300 rpm, and the stirring time after the dropping is completed is 2 min.

[0078] S3, aging the first treatment liquid at room temperature for 6 hours to obtain a second treatment liquid; the second treatment liquid comprises an aqueous phase and an organic phase.

[0079] S4, separating the second treated liquid through a separatory funnel to obtain an organic phase and a silica-rich aqueous phase, and the separated aqueous phase is recorded as a separated liquid.

[0080] The separated liquid was filtered, and then the solid separated matter was washed three times with deionized water and anhydrous ethanol respectively to obtain a washed solid separated matter.

[0081] The solid separator was calcined under oxygen-rich conditions at a temperature of 550° C. for 4 hours. The oxygen partial pressure during the calcination process was 30%, with the remainder being nitrogen. The calcined product was found to be silicon dioxide, which was recorded as a silicon dioxide product.

[0082] In step S2 of this embodiment, the reaction process is gentle, with no liquid splashing, no white smoke, no significant heat generation, and no blockage.

[0083] In this example, the TEM analysis of the silica product is shown in Figure 1 As shown, it can be seen that the obtained silicon dioxide product presents a regular circular outline and good morphology, indicating its good sphericity; its particle size is mainly concentrated around 200 nanometers, which is consistent with the characteristics of nanoscale materials.

[0084] In this embodiment, the particle size range of the silicon dioxide product is basically 50-500 nm; in this embodiment, the particles with a roundness greater than 0.95 account for approximately 94.6%.

[0085] In this example, BET analysis of the silica product showed that it had a high specific surface area of 948.97 m² / g and a total pore volume of 0.5362 cm³ / g, an average pore diameter of approximately 2.2601 nm, and a predominantly mesoporous structure.

[0086] Example 2

[0087] Compared with Example 1, the volume concentration of silicon tetrachloride in the organic solution in this example is adjusted to 25%.

[0088] The steps of this embodiment are:

[0089] S1, dissolving liquid silicon tetrachloride in toluene to obtain an organic solution of silicon tetrachloride; the volume concentration of silicon tetrachloride in the organic solution is 25%.

[0090] Deionized water and cetyltrimethylammonium bromide (CTAB) are mixed to obtain an aqueous solution of cetyltrimethylammonium bromide; the mass concentration of cetyltrimethylammonium bromide in the aqueous solution is 2%.

[0091] S2, adding the above aqueous solution to the above organic solution at a rate of 20 mL / min, and stirring during and after the dropping process to obtain a first treatment liquid; the stirring process is carried out at a temperature of 25°C; the volume ratio of the aqueous solution to the organic solution is 1:3, the stirring rate is 300 rpm, and the stirring time after the dropping is completed is 2 min.

[0092] S3, aging the first treatment liquid at room temperature for 6 hours to obtain a second treatment liquid; the second treatment liquid comprises an aqueous phase and an organic phase.

[0093] S4, separating the second treated liquid through a separatory funnel to obtain an organic phase and an aqueous phase, and recording the separated aqueous phase as the separated liquid.

[0094] The separated liquid was filtered, and then the solid separated matter was washed three times with deionized water and anhydrous ethanol respectively to obtain a washed solid separated matter.

[0095] The solid separator was calcined under oxygen-rich conditions at a temperature of 550° C. for 4 hours. The oxygen partial pressure during the calcination process was 30%, with the remainder being nitrogen. The calcined product was found to be silicon dioxide, which was recorded as a silicon dioxide product.

[0096] In step S2 of this embodiment, the reaction process is gentle, with no liquid splashing, no white smoke, no significant heat generation, and no blockage.

[0097] In this embodiment, the SEM of the silica product is shown in FIG. Figure 2 As shown, it can be seen that the obtained silicon dioxide product presents a regular circular contour, good morphology, good sphericity, and meets the characteristics of nanoscale materials; in this embodiment, the particles with a roundness greater than 0.95 account for approximately 92.2%.

[0098] In this example, BET analysis of the silica product showed that it had a specific surface area of 673.94 m² / g and a total pore volume of 0.5368 cm³ / g, with an average pore diameter of 3.1862 nm.

[0099] Example 3

[0100] Compared with Example 1, the toluene in this example is replaced with chloroform.

[0101] The steps of this embodiment are:

[0102] S1, dissolving liquid silicon tetrachloride in chloroform to obtain an organic solution of silicon tetrachloride; the volume concentration of silicon tetrachloride in the organic solution is 5%.

[0103] Deionized water and cetyltrimethylammonium bromide (CTAB) are mixed to obtain an aqueous solution of cetyltrimethylammonium bromide; the mass concentration of cetyltrimethylammonium bromide in the aqueous solution is 2%.

[0104] S2, adding the above aqueous solution to the above organic solution at a rate of 20 mL / min, and stirring during and after the dropping process to obtain a first treatment liquid; the stirring process is carried out at a temperature of 25°C; the volume ratio of the aqueous solution to the organic solution is 1:19, the stirring rate is 300 rpm, and the stirring time after the dropping is completed is 2 min.

[0105] S3, aging the first treatment liquid at room temperature for 6 hours to obtain a second treatment liquid; the second treatment liquid comprises an aqueous phase and an organic phase.

[0106] S4, separating the second treated liquid through a separatory funnel to obtain an organic phase and an aqueous phase, and recording the separated aqueous phase as the separated liquid.

[0107] The separated liquid was filtered, and then the solid separated matter was washed three times with deionized water and anhydrous ethanol respectively to obtain a washed solid separated matter.

[0108] The solid separator was calcined under oxygen-rich conditions at a temperature of 550° C. for 4 hours. The oxygen partial pressure during the calcination process was 30%, with the remainder being nitrogen. The calcined product was found to be silicon dioxide, which was recorded as a silicon dioxide product.

[0109] In step S2 of this embodiment, the reaction process is gentle, with no liquid splashing, no white smoke, no significant heat generation, and no blockage.

[0110] In this embodiment, the SEM of the silica product is shown in FIG. Figure 3 As shown, the silica product of this embodiment is silica nanoparticles with regular morphology and high degree of sphericity; in this embodiment, the particles with a roundness greater than 0.95 account for approximately 93.5%.

[0111] In this example, BET analysis of the silica product showed that it had a specific surface area of 853.29 m² / g and a total pore volume of 0.5367 cm³ / g, with an average pore diameter of 2.8791 nm.

[0112] Example 4

[0113] Compared with Example 1, the calcination in this example is adjusted to drying.

[0114] The steps of this embodiment are:

[0115] S1, dissolving liquid silicon tetrachloride in toluene to obtain an organic solution of silicon tetrachloride; the volume concentration of silicon tetrachloride in the organic solution is 5%.

[0116] Deionized water and cetyltrimethylammonium bromide (CTAB) are mixed to obtain an aqueous solution of cetyltrimethylammonium bromide; the mass concentration of cetyltrimethylammonium bromide in the aqueous solution is 2%.

[0117] S2, adding the above aqueous solution to the above organic solution at a rate of 20 mL / min, and stirring during and after the dropping process to obtain a first treatment liquid; the stirring process is carried out at a temperature of 25°C; the volume ratio of the aqueous solution to the organic solution is 1:19, the stirring rate is 300 rpm, and the stirring time after the dropping is completed is 2 min.

[0118] S3, aging the first treatment liquid at room temperature for 6 hours to obtain a second treatment liquid; the second treatment liquid comprises an aqueous phase and an organic phase.

[0119] S4, separating the second treated liquid through a separatory funnel to obtain an organic phase and an aqueous phase, and recording the separated aqueous phase as the separated liquid.

[0120] The separated liquid was filtered, and then the solid separated matter was washed three times with deionized water and anhydrous ethanol respectively to obtain a washed solid separated matter.

[0121] The solid separated material was dried in a vacuum dryer at 60° C. and 0.2 atmospheres for 24 hours. The dried product was found to be silicon dioxide, which was recorded as a silicon dioxide product.

[0122] In step S2 of this embodiment, the reaction process is gentle, with no liquid splashing, no white smoke, no significant heat generation, and no blockage.

[0123] In this embodiment, the SEM of the silica product is shown in FIG. Figure 4 As shown, it can be seen that the obtained silicon dioxide product presents a regular circular outline; in this embodiment, the particles with a roundness greater than 0.95 account for approximately 94.6%.

[0124] In this example, BET analysis of the silica product showed that it had a specific surface area of 409.52 m² / g and a total pore volume of 0.4022 cm³ / g, with an average pore diameter of 3.9282 nm.

[0125] Example 5

[0126] Compared with Example 1, cetyltrimethylammonium bromide was not added in this example.

[0127] The steps of this embodiment are:

[0128] S1, dissolving liquid silicon tetrachloride in toluene to obtain an organic solution of silicon tetrachloride; the volume concentration of silicon tetrachloride in the organic solution is 5%.

[0129] S2, deionized water is added dropwise to the above organic solution at a rate of 20 mL / min, and stirred during and after the addition to obtain a first treatment liquid; the stirring process is carried out at a temperature of 25°C; the volume ratio of deionized water to the organic solution is 1:19, the stirring rate is 300 rpm, and the stirring time after the addition is completed is 2 min.

[0130] S3, aging the first treatment liquid at room temperature for 6 hours to obtain a second treatment liquid; the second treatment liquid comprises an aqueous phase and an organic phase.

[0131] S4, separating the second treated liquid through a separatory funnel to obtain an organic phase and an aqueous phase, and recording the separated aqueous phase as the separated liquid.

[0132] The separated liquid was filtered, and then the solid separated matter was washed three times with deionized water and anhydrous ethanol respectively to obtain a washed solid separated matter.

[0133] The solid separator was calcined under oxygen-rich conditions at a temperature of 550° C. for 4 hours. The oxygen partial pressure during the calcination process was 30%, with the remainder being nitrogen. The calcined product was found to be silicon dioxide, which was recorded as a silicon dioxide product.

[0134] In step S2 of this embodiment, the reaction process is gentle, with no liquid splashing, no white smoke, no significant heat generation, and no blockage.

[0135] In this embodiment, the SEM of the silica product is shown in FIG. Figure 5 As shown, most of the particle sizes are in the range of 100-500 nm. In this embodiment, particles with a roundness greater than 0.95 account for about 87.5%, and particles with a roundness greater than 0.9 account for about 92%, and the morphology is relatively regular.

[0136] In this example, BET analysis of the silica product showed that its specific surface area was 129.91 m² / g and its total pore volume was 0.065721 cm³ / g.

[0137] Example 6

[0138] Compared with Example 1, the cationic surfactant (cetyltrimethylammonium bromide) in this example is replaced by an anionic surfactant (sodium dodecylbenzenesulfonate).

[0139] The steps of this embodiment are:

[0140] S1, dissolving liquid silicon tetrachloride in toluene to obtain an organic solution of silicon tetrachloride; the volume concentration of silicon tetrachloride in the organic solution is 5%.

[0141] Deionized water and sodium dodecylbenzenesulfonate are mixed to obtain an aqueous solution of sodium dodecylbenzenesulfonate; the mass concentration of sodium dodecylbenzenesulfonate in the aqueous solution is 2%.

[0142] S2, adding the above aqueous solution to the above organic solution at a rate of 20 mL / min, and stirring during and after the dropping process to obtain a first treatment liquid; the stirring process is carried out at a temperature of 25°C; the volume ratio of the aqueous solution to the organic solution is 1:19, the stirring rate is 300 rpm, and the stirring time after the dropping is completed is 2 min.

[0143] S3, aging the first treatment liquid at room temperature for 6 hours to obtain a second treatment liquid; the second treatment liquid comprises an aqueous phase and an organic phase.

[0144] S4, separating the second treated liquid through a separatory funnel to obtain an organic phase and an aqueous phase, and recording the separated aqueous phase as the separated liquid.

[0145] The separated liquid was filtered, and then the solid separated matter was washed three times with deionized water and anhydrous ethanol respectively to obtain a washed solid separated matter.

[0146] The solid separator was calcined under oxygen-rich conditions at a temperature of 550° C. for 4 hours. The oxygen partial pressure during the calcination process was 30%, with the remainder being nitrogen. The calcined product was found to be silicon dioxide, which was recorded as a silicon dioxide product.

[0147] In step S2 of this embodiment, the reaction process is gentle, with no liquid splashing, no white smoke, no significant heat generation, and no blockage.

[0148] See also Figure 6 As shown, the silica product obtained in this embodiment is mainly spherical and has a relatively regular morphology. In this embodiment, the particles with a roundness greater than 0.95 account for about 82.4%, and the particles with a roundness greater than 0.9 account for about 90%.

[0149] In this example, BET analysis of the silica product showed that its specific surface area was 296.66 m² / g and its total pore volume was 0.309 cm³ / g.

[0150] Example 7

[0151] Compared with Example 1, this example adds cetyltrimethylammonium bromide to the organic solution.

[0152] The steps of this embodiment are:

[0153] S1, liquid silicon tetrachloride and cetyltrimethylammonium bromide (CTAB) are mixed in toluene and recorded as an organic solution of silicon tetrachloride; in the organic solution, the volume concentration of silicon tetrachloride is 5%, and the mass concentration of cetyltrimethylammonium bromide is 2%.

[0154] S2, deionized water is added dropwise to the above organic solution at a rate of 20 mL / min, and stirred during and after the addition to obtain a first treatment liquid; the stirring process is carried out at a temperature of 25°C; the volume ratio of deionized water to the organic solution is 1:19, the stirring rate is 300 rpm, and the stirring time after the addition is completed is 2 min.

[0155] S3, aging the first treatment liquid at room temperature for 6 hours to obtain a second treatment liquid; the second treatment liquid comprises an aqueous phase and an organic phase.

[0156] S4, separating the second treated liquid through a separatory funnel to obtain an organic phase and an aqueous phase, and recording the separated aqueous phase as the separated liquid.

[0157] The separated liquid was filtered, and then the solid separated matter was washed three times with deionized water and anhydrous ethanol respectively to obtain a washed solid separated matter.

[0158] The solid separator was calcined under oxygen-rich conditions at a temperature of 550° C. for 4 hours. The oxygen partial pressure during the calcination process was 30%, with the remainder being nitrogen. The calcined product was found to be silicon dioxide, which was recorded as a silicon dioxide product.

[0159] In step S2 of this embodiment, the reaction process is gentle, with no liquid splashing, no white smoke, no significant heat generation, and no blockage.

[0160] See also Figure 7 As shown, the silica product obtained in this embodiment is mainly dispersed spherical particles with a relatively regular morphology. In this embodiment, the particles with a roundness greater than 0.95 account for about 85.8%, and the particles with a roundness greater than 0.9 account for about 91.6%.

[0161] In this example, BET analysis of the silica product showed that its specific surface area was 279.35 m² / g and its total pore volume was 0.316 cm³ / g.

[0162] Comparative Example 1

[0163] Compared with Example 1, in this comparative example, silicon tetrachloride and the aqueous solution are directly reacted.

[0164] The steps of this comparative example are:

[0165] S1. Mix deionized water and cetyltrimethylammonium bromide (CTAB) to obtain an aqueous solution of cetyltrimethylammonium bromide; the mass concentration of cetyltrimethylammonium bromide in the aqueous solution is 2%.

[0166] S2, adding liquid silicon tetrachloride dropwise to the above aqueous solution at a rate of 5 mL / min, and stirring during and after the dropping process to obtain a first treatment liquid; the stirring process is carried out at a temperature of 25°C; the volume ratio of the aqueous solution to the liquid silicon tetrachloride is 19:1, the stirring rate is 300 rpm, and the stirring time after the dropping is 2 min.

[0167] S3, aging the first treatment liquid at room temperature for 6 hours to obtain a second treatment liquid; the second treatment liquid comprises an aqueous phase and an organic phase.

[0168] S4, separating the second treated liquid through a separatory funnel to obtain an organic phase and an aqueous phase, and recording the separated aqueous phase as the separated liquid.

[0169] The separated liquid was filtered, and then the solid separated matter was washed three times with deionized water and anhydrous ethanol respectively to obtain a washed solid separated matter.

[0170] The solid separator was calcined under oxygen-rich conditions at a temperature of 550° C. for 4 hours. The oxygen partial pressure during the calcination process was 30%, with the remainder being nitrogen. The calcined product was found to be silicon dioxide, which was recorded as a silicon dioxide product.

[0171] In step S2 of this comparative example, silicon tetrachloride and water undergo a violent hydrolysis reaction, resulting in liquid splashing, white smoke, and significant heat generation. During the reaction, the dropper nozzle encounters moisture in the air and becomes clogged.

[0172] In this comparative example, the SEM of the silica product is shown in FIG. Figure 8 As shown, the silica product obtained in this comparative example was polymerized and had a poor morphology.

[0173] Comparative Example 2

[0174] Compared with Example 1, the proportion of the aqueous solution in this comparative example is reduced.

[0175] The steps of this comparative example are:

[0176] S1, dissolving liquid silicon tetrachloride in toluene to obtain an organic solution of silicon tetrachloride; the volume concentration of silicon tetrachloride in the organic solution is 5%.

[0177] Deionized water and cetyltrimethylammonium bromide (CTAB) are mixed to obtain an aqueous solution of cetyltrimethylammonium bromide; the mass concentration of cetyltrimethylammonium bromide in the aqueous solution is 2%.

[0178] S2, adding the above aqueous solution to the above organic solution at a rate of 20 mL / min, and stirring during and after the dropping process to obtain a first treatment liquid; the stirring process is carried out at a temperature of 25°C; the volume ratio of the aqueous solution to the organic solution is 1:125, the stirring rate is 300 rpm, and the stirring time after the dropping is completed is 2 min.

[0179] S3, aging the first treatment liquid at room temperature for 6 hours to obtain a second treatment liquid; no obvious stratification is observed in the second treatment liquid.

[0180] S4, filtering the second treated liquid, and then washing the solid separation with deionized water and anhydrous ethanol three times respectively to obtain a washed solid separation.

[0181] The solid separator was calcined under oxygen-rich conditions at a temperature of 550° C. for 4 hours. The oxygen partial pressure during the calcination process was 30%, with the remainder being nitrogen. The calcined product was found to be silicon dioxide, which was recorded as a silicon dioxide product.

[0182] In this comparative example, see Figure 9-10 As shown, due to the low proportion of aqueous solution, the liquid-liquid interface cannot exist stably, resulting in uneven distribution of reactants at the interface, affecting the morphology of the silica spheres, and causing the silica product obtained in this comparative example to have poor sphericity; in this comparative example, the proportion of particles with a roundness greater than 0.9 is only about 10.8%.

[0183] In this comparative example, BET analysis of the silica product showed that its specific surface area was 729.61 m² / g and its total pore volume was 0.498 cm³ / g.

[0184] The above technical solutions of the present invention are only preferred embodiments of the present invention and do not limit the patent scope of the present invention. All equivalent structural transformations made by using the contents of the present invention's description and drawings under the technical concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A method for preparing silicon dioxide based on a liquid-liquid two-phase interface method, characterized in that: Including steps: S1, providing an organic solution and water, wherein the organic solution includes an organic solvent and silicon tetrachloride; the water contains a cationic surfactant, and the cationic surfactant includes hexadecyltrimethylammonium bromide; The volume ratio of the water to the organic solution is 1:0.8-30; the molar ratio of the water to the silicon tetrachloride is 5-15:1; the organic solvent is insoluble or slightly soluble in the water; S2, mixing the water and the organic solution to obtain a first treated liquid; S3, aging the first treatment liquid to obtain a second treatment liquid; the second treatment liquid comprises an aqueous phase and an organic phase; S4, separating and obtaining a primary silica product from the second treatment liquid.

2. The method for preparing silicon dioxide based on the liquid-liquid two-phase interface method according to claim 1, characterized in that: The step S4 further includes: calcining the primary silica product to obtain a silica product; the calcination temperature is 500-1000° C.; the calcination time is 0.5-6 hours; the calcination is carried out in an oxygen-containing atmosphere; and the oxygen partial pressure during the calcination process is 20-50%.

3. The method for preparing silicon dioxide based on the liquid-liquid two-phase interface method according to claim 1, characterized in that: In the organic solution, the volume concentration of silicon tetrachloride is no more than 30%.

4. The method for preparing silicon dioxide based on the liquid-liquid two-phase interface method according to claim 1, characterized in that: The organic solvent includes one or more of toluene and chloroform.

5. The method for preparing silicon dioxide based on the liquid-liquid two-phase interface method according to claim 1, characterized in that: The mass concentration of the cationic surfactant in the water is 0.5-25%.

6. The method for preparing silicon dioxide based on the liquid-liquid two-phase interface method according to claim 1, characterized in that: The mixing is performed at a temperature of 15-40° C.; the mixing time is 0.5-5 min; and the mixing speed is 100-600 rpm.

7. The method for preparing silicon dioxide based on the liquid-liquid two-phase interface method according to claim 1, characterized in that: In the step S2, before the mixing, the water is added dropwise to the organic solution; the rate of the addition is 5-50 mL / min; and stirring is performed during the addition.

8. The method for preparing silicon dioxide based on the liquid-liquid two-phase interface method according to claim 1, characterized in that: The aging time is 3-12 hours; the aging temperature is 10-40° C.; and the aging is carried out under static conditions.

9. The method for preparing silicon dioxide based on the liquid-liquid two-phase interface method according to any one of claims 1 to 8, characterized in that: In step S4, the process of separating the primary silica product from the second treatment liquid includes: performing liquid-liquid separation on the aqueous phase and the organic phase in the second treatment liquid to obtain the aqueous phase and the organic phase; and performing solid-liquid separation on the aqueous phase to obtain the primary silica product.

10. The method for preparing silicon dioxide based on the liquid-liquid two-phase interface method according to claim 9, characterized in that: In the step S4, the process of separating the primary silica product from the second treatment liquid further includes: performing solid-liquid separation on the organic phase obtained after the liquid-liquid separation to obtain the primary silica product.

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