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

Abstract

The invention provides a method for preparing silicon dioxide based on a liquid-liquid two-phase interface method, which comprises the following steps: S1, providing an organic solution and water, the organic solution comprising 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 solution; s3, aging the first treatment liquid to obtain a second treatment liquid; the second treatment liquid contains a water phase and an organic phase; s4, separating from the second treatment liquid to obtain a silicon dioxide primary product; and calcining the silicon dioxide primary product to obtain a silicon dioxide product. The silicon dioxide nano powder with high spheroidization degree is prepared on the basis of silicon tetrachloride and a liquid-liquid two-phase interface method, the reaction is mild, and the risk is low.

Description

Technical Field

[0001] The 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. Among them, mesoporous silica nanopowder has a special structure and excellent properties. It has attracted much attention in the fields of materials, chemical engineering and biomedicine due to its large specific surface area, large pore structure, good biocompatibility and biodegradability. There are many pores with a diameter of 2-50nm on the surface of the nanoparticles of mesoporous silica nanopowder, which enables it to load various substances, build an efficient medium transmission system, and improve reaction efficiency.

[0003] Silicon tetrachloride is a colorless, transparent, low-viscosity liquid at room temperature. It is flammable and asphyxiating. It has active chemical properties and is widely used in the synthesis of organic silicon compounds, the production of semiconductor materials, and the manufacture of optical fibers. There are three main ways to process silicon tetrachloride: one is to hydrogenate and reduce silicon tetrachloride to produce trichlorosilane, but the current production technology leads to low conversion rates and high costs; the second is to make silicon tetrachloride into a variety of organic silicon compounds, but due to the constraints of secondary pollution and consumption, this method still has limitations in consuming silicon tetrachloride produced in the production process of multiple silicon products; the third is to use silicon tetrachloride as raw material to produce silicon dioxide, but the conventional gas phase production process requires high temperature and high pressure conditions, and the requirements for equipment are relatively strict.

[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 the existing process, 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 is mainly to hydrolyze tetraethyl orthosilicate (TEOS) under alkaline conditions to generate 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 under the action of a catalyst, which is more complicated than directly using silicon tetrachloride to produce silica microspheres. In addition, the precipitation method and the sol-gel method also have the disadvantages of easy introduction of impurities and long production cycle.

[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 a liquid-liquid two-phase interface method, aiming to solve the above-mentioned 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.

[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: S1, providing an organic solution and water, wherein the organic solution comprises 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 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 product of silicon dioxide from the second treatment liquid.

[0008] Furthermore, the step S4 also 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%.

[0009] 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%.

[0010] Furthermore, the organic solvent includes one or more of toluene and chloroform.

[0011] 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.

[0012] 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.

[0013] 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.

[0014] Furthermore, the aging time is 3-12 hours; the aging temperature is 10-40° C.; and the aging is carried out under static conditions.

[0015] Furthermore, in step S4, the process of separating the primary silica product from the second treatment liquid includes: liquid-liquid separation of the aqueous phase and the organic phase in the second treatment liquid to obtain the aqueous phase and the organic phase; solid-liquid separation of the aqueous phase to obtain the primary silica product.

[0016] Furthermore, 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.

[0017] Compared with the prior art, the present invention has at least the following advantages: The present invention can prepare silicon dioxide products with excellent morphology and high spheroidization degree based on silicon tetrachloride, and the reaction process is mild, without liquid splashing, white smoke, obvious heat generation, and no blockage phenomenon. The present invention controls the reaction to occur at the interface of two phases while maintaining sufficient reaction through liquid-liquid interface reaction, effectively regulates the silicon dioxide generation process, and provides a basis for obtaining high-quality silicon dioxide products. In addition, the present invention has short reaction time, simple process, is not easy to introduce impurities, and the organic solvent can also be recycled.

[0018] In the present invention, the volume ratio of water to organic solution is not less than 1 / 50, silicon tetrachloride exists 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 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 the morphology of silicon dioxide while ensuring a mild reaction, and obtains high-quality nano-scale silicon dioxide products. The present invention prepares silicon dioxide based on the liquid-liquid two-phase interface method, which can reduce safety hazards, reduce process energy consumption, and have a good product spheroidization degree; after introducing a cationic surfactant, the synthesis of mesoporous silicon dioxide nanopowder can be further realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. 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 creative work.

[0020] Figure 1This is a TEM image of the silicon dioxide product in Example 1 of the present invention; Figure 2 This is a SEM image of the silicon dioxide product in Example 2 of the present invention; Figure 3 This is a SEM image of the silicon dioxide product in Example 3 of the present invention; Figure 4 This is a SEM image of the silicon dioxide product in Example 4 of the present invention; Figure 5 This is a SEM image of the silicon dioxide product in Example 5 of the present invention; Figure 6 This is a SEM image of the silicon dioxide product in Example 6 of the present invention; Figure 7 This is a SEM image of the silicon dioxide product in Example 7 of the present invention; Figure 8 This is a SEM image of the silicon dioxide product in Comparative Example 1 of the present invention; Fig. 9 This is a SEM image of the silicon dioxide product at a certain viewing angle in Comparative Example 2 of the present invention; Fig.10 This is a SEM image of the silicon dioxide product at another viewing angle in Comparative Example 2 of the present invention.

[0021] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with the implementation methods and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0022] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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 creative work are within the scope of protection of the present invention.

[0023] Furthermore, 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 they can be implemented by ordinary technicians in the field. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0024] When numerical ranges are given in the embodiments, it should be understood that, unless otherwise specified in the present invention, both endpoints of each numerical range and any value between the two endpoints can be selected. Unless otherwise defined, all technical and scientific terms used in the present invention are familiar to those skilled in the art and the description of the present invention, and any methods, equipment and materials of the prior art similar or equivalent to the methods, equipment and materials described in the embodiments of the present invention can also be used to implement the present invention.

[0025] 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 a value range of ≤1, where 1 is a perfect sphere.

[0026] The present invention provides a method for preparing silicon dioxide based on a liquid-liquid two-phase interface method, comprising the steps of: S1, providing an organic solution and water; the organic solution comprises an organic solvent and silicon tetrachloride.

[0027] In the present invention, 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. The water in the present invention is added in excess, which can not only ensure the full reaction of the silicon tetrachloride, but also ensure the stable formation of the liquid-liquid two-phase interface.

[0028] As a further description 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 not 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.

[0029] 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.

[0030] 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.

[0031] In the organic solution of the present invention, the volume concentration of silicon tetrachloride is not more than 30%; further, the volume concentration of 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%.

[0032] 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 danger, 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, which can not only effectively avoid the silicon dioxide hydrolysis process from being too fast, but also ensure the morphology of silicon dioxide.

[0033] 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 further 1-5%. In the present invention, the water containing the cationic surfactant is an aqueous solution of the cationic surfactant.

[0034] It should be pointed out that, compared with other types of surfactants and compared with adding the surfactant directly into the organic solvent, the addition of the cationic surfactant into the water in the present invention can also significantly improve the performance of silicon dioxide.

[0035] 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.

[0036] 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.

[0037] S2, mixing the water and the organic solution to obtain a first treated liquid.

[0038] 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 100-600rpm, further 200-400rpm.

[0039] In the present invention, the mixing time is 0.5-5 min, further 1-3 min, further 1.5-3 min. In this step, before the mixing, the aqueous solution is added dropwise to the organic solution; the dropping rate is 5-50 mL / min, further 10-30 mL / min; the organic solution is stirred during the dropping process, and the stirring speed is 100-600 rpm, further 200-400 rpm.

[0040] S3, aging the first treatment liquid to obtain a second treatment liquid.

[0041] In the present invention, the second treatment liquid comprises an aqueous phase and an organic phase; the aqueous phase is rich in silicon dioxide, and the organic phase generally also contains some silicon dioxide; in the experimental case of the present invention, the silicon dioxide in the aqueous phase is collected.

[0042] 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.

[0043] S4, separating and obtaining a primary product of silicon dioxide from the second treatment liquid.

[0044] The process of separating the silica preliminary product from the second treatment liquid includes: liquid-liquid separation of the aqueous phase and the organic phase in the second treatment liquid to obtain the aqueous phase and the organic phase; solid-liquid separation of the aqueous phase to obtain the silica preliminary product. The liquid-liquid separation process includes: separating the aqueous phase and the organic phase in the second treatment liquid through a separatory funnel to obtain the separated aqueous phase and the organic phase; the solid-liquid separation process includes: filtering the aqueous phase obtained after the liquid-liquid separation to obtain the silica preliminary product.

[0045] In order to fully collect silica, the process of separating the primary silica from the second treatment liquid may further include: performing solid-liquid separation on the organic phase obtained after the liquid-liquid separation to obtain the primary silica. The solid-liquid separation process includes: filtering the organic phase obtained after the liquid-liquid separation to obtain the primary silica.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] In the present invention, as an illustration of the preferred embodiment, the process of preparing silicon dioxide by the 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: 2H 2 O+SiCl 4 =SiO 2 +4HCl.

[0051] It should be pointed out that in the existing process of producing silicon dioxide products using sodium silicate as a raw material (such as a 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 silicon dioxide; however, the present invention does not introduce other substances, thus avoiding the problem of introducing impurities in the existing process, and can prepare high-end silicon dioxide products, and can also subsequently recycle and reuse organic solvents.

[0052] As an illustration of other prior arts, a Chinese invention patent application with publication number CN102515104A discloses a method for preparing hydrogen chloride and silicon dioxide by hydrolyzing silicon tetrachloride in an organic solvent; the 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.

[0053] Although this patent application also uses organic solvents and water and is able to 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 the need to avoid excessive addition of water; 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.

[0054] More importantly, the proportion of water in the embodiment 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 product morphology in the present invention, and the quality of the product is not good, especially the spheroidization degree is very poor.

[0055] Furthermore, the sodium dodecylbenzene sulfonate (anionic surfactant) used in the patent application is not a preferred active agent in the technical system of the present invention; and the application directly adds the active agent to the organic solvent, which will also affect the technical effect of the present invention to a certain extent. Therefore, the patent application only provides another method for mildly preparing silica, and it does not consider the preparation of high-quality silica based on the liquid-liquid interface method, nor does it further explore better industrial application conditions based on the liquid-liquid interface method.

[0056] The following are specific examples of the present invention: Example 1 A method for preparing silicon dioxide based on a liquid-liquid two-phase interface method, the steps of which are: S1, dissolving liquid silicon tetrachloride in toluene to obtain an organic solution of silicon tetrachloride; in the organic solution, the volume concentration of silicon tetrachloride is 5%.

[0057] Deionized water and cetyltrimethylammonium bromide (CTAB) are mixed to obtain an aqueous solution of cetyltrimethylammonium bromide; in the aqueous solution, the mass concentration of cetyltrimethylammonium bromide is 2%.

[0058] 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.

[0059] S3, aging the first treatment liquid at room temperature for 6 hours to obtain a second treatment liquid; the second treatment liquid contains an aqueous phase and an organic phase.

[0060] S4, separating the second treated liquid through a separatory funnel to obtain an organic phase and a water phase rich in silica, and recording the separated water phase as a separated liquid.

[0061] 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.

[0062] 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%, and the rest was nitrogen. Upon testing, the calcined product was silicon dioxide, recorded as silicon dioxide product.

[0063] In step S2 of this embodiment, the reaction process is gentle, without liquid splashing, white smoke, obvious heat generation, or blockage.

[0064] In this example, TEM analysis of the silicon dioxide product is shown in Figure 1 As shown, it can be seen that the obtained silicon dioxide product presents a regular circular outline and a good morphology, indicating its good sphericity; its particle size is mainly concentrated around 200 nanometers, which is consistent with the characteristics of nanoscale materials.

[0065] In this embodiment, the particle size range of the silicon dioxide product is basically 50-500nm; in this embodiment, the particles with a roundness greater than 0.95 account for about 94.6%.

[0066] In this embodiment, BET analysis of the silica product shows that it has 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 about 2.2601 nm, and is mainly a mesoporous structure.

[0067] Example 2 Compared with Example 1, the volume concentration of silicon tetrachloride in the organic solution in this example is adjusted to 25%.

[0068] The steps of this embodiment are: S1, dissolving liquid silicon tetrachloride in toluene to obtain an organic solution of silicon tetrachloride; in the organic solution, the volume concentration of silicon tetrachloride is 25%.

[0069] Deionized water and cetyltrimethylammonium bromide (CTAB) are mixed to obtain an aqueous solution of cetyltrimethylammonium bromide; in the aqueous solution, the mass concentration of cetyltrimethylammonium bromide is 2%.

[0070] 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.

[0071] S3, aging the first treatment liquid at room temperature for 6 hours to obtain a second treatment liquid; the second treatment liquid contains an aqueous phase and an organic phase.

[0072] 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 a separated liquid.

[0073] 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.

[0074] 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%, and the rest was nitrogen. Upon testing, the calcined product was silicon dioxide, recorded as silicon dioxide product.

[0075] In step S2 of this embodiment, the reaction process is gentle, without liquid splashing, white smoke, obvious heat generation, or blockage.

[0076] In this example, 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 proportion of particles with a roundness greater than 0.95 is about 92.2%.

[0077] 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.

[0078] Example 3 Compared with Example 1, the toluene in this example is changed to chloroform.

[0079] The steps of this embodiment are: S1, dissolving liquid silicon tetrachloride in chloroform to obtain an organic solution of silicon tetrachloride; in the organic solution, the volume concentration of silicon tetrachloride is 5%.

[0080] Deionized water and cetyltrimethylammonium bromide (CTAB) are mixed to obtain an aqueous solution of cetyltrimethylammonium bromide; in the aqueous solution, the mass concentration of cetyltrimethylammonium bromide is 2%.

[0081] 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.

[0082] S3, aging the first treatment liquid at room temperature for 6 hours to obtain a second treatment liquid; the second treatment liquid contains an aqueous phase and an organic phase.

[0083] 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 a separated liquid.

[0084] 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.

[0085] 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%, and the rest was nitrogen. Upon testing, the calcined product was silicon dioxide, recorded as silicon dioxide product.

[0086] In step S2 of this embodiment, the reaction process is gentle, without liquid splashing, white smoke, obvious heat generation, or blockage.

[0087] In this example, the SEM of the silica product is shown in FIG. Figure 3 As shown, the silicon dioxide product of this embodiment is silicon dioxide nanoparticles with regular morphology and high degree of spheroidization; in this embodiment, the particles with a roundness greater than 0.95 account for about 93.5%.

[0088] 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.

[0089] Example 4 Compared with Example 1, the calcination in this example is adjusted to drying.

[0090] The steps of this embodiment are: S1, dissolving liquid silicon tetrachloride in toluene to obtain an organic solution of silicon tetrachloride; in the organic solution, the volume concentration of silicon tetrachloride is 5%.

[0091] Deionized water and cetyltrimethylammonium bromide (CTAB) are mixed to obtain an aqueous solution of cetyltrimethylammonium bromide; in the aqueous solution, the mass concentration of cetyltrimethylammonium bromide is 2%.

[0092] 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.

[0093] S3, aging the first treatment liquid at room temperature for 6 hours to obtain a second treatment liquid; the second treatment liquid contains an aqueous phase and an organic phase.

[0094] 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 a separated liquid.

[0095] 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.

[0096] The solid separation was dried in a vacuum dryer at 60° C. and 0.2 atmospheres for 24 hours. After testing, the dried product was found to be silicon dioxide, which was recorded as a silicon dioxide product.

[0097] In step S2 of this embodiment, the reaction process is gentle, without liquid splashing, white smoke, obvious heat generation, or blockage.

[0098] In this example, 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 contour; in this embodiment, the particles with a roundness greater than 0.95 account for about 94.6%.

[0099] 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.

[0100] Example 5 Compared with Example 1, cetyltrimethylammonium bromide was not added in this example.

[0101] The steps of this embodiment are: S1, dissolving liquid silicon tetrachloride in toluene to obtain an organic solution of silicon tetrachloride; in the organic solution, the volume concentration of silicon tetrachloride is 5%.

[0102] 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.

[0103] S3, aging the first treatment liquid at room temperature for 6 hours to obtain a second treatment liquid; the second treatment liquid contains an aqueous phase and an organic phase.

[0104] 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 a separated liquid.

[0105] 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.

[0106] 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%, and the rest was nitrogen. Upon testing, the calcined product was silicon dioxide, recorded as silicon dioxide product.

[0107] In step S2 of this embodiment, the reaction process is gentle, without liquid splashing, white smoke, obvious heat generation, or blockage.

[0108] In this example, 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.

[0109] 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.

[0110] Example 6 Compared with Example 1, the cationic surfactant (hexadecyltrimethylammonium bromide) in this example is changed to an anionic surfactant (sodium dodecylbenzenesulfonate).

[0111] The steps of this embodiment are: S1, dissolving liquid silicon tetrachloride in toluene to obtain an organic solution of silicon tetrachloride; in the organic solution, the volume concentration of silicon tetrachloride is 5%.

[0112] Deionized water and sodium dodecylbenzene sulfonate are mixed to obtain an aqueous solution of sodium dodecylbenzene sulfonate; in the aqueous solution, the mass concentration of sodium dodecylbenzene sulfonate is 2%.

[0113] 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.

[0114] S3, aging the first treatment liquid at room temperature for 6 hours to obtain a second treatment liquid; the second treatment liquid contains an aqueous phase and an organic phase.

[0115] 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 a separated liquid.

[0116] 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.

[0117] 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%, and the rest was nitrogen. Upon testing, the calcined product was silicon dioxide, recorded as silicon dioxide product.

[0118] In step S2 of this embodiment, the reaction process is gentle, without liquid splashing, white smoke, obvious heat generation, or blockage.

[0119] See also Figure 6 As shown, the silicon dioxide 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%.

[0120] 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.

[0121] Example 7 Compared with Example 1, in this example, hexadecyltrimethylammonium bromide is added to the organic solution.

[0122] The steps of this embodiment are: S1, liquid silicon tetrachloride and hexadecyltrimethylammonium 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 hexadecyltrimethylammonium bromide is 2%.

[0123] 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.

[0124] S3, aging the first treatment liquid at room temperature for 6 hours to obtain a second treatment liquid; the second treatment liquid contains an aqueous phase and an organic phase.

[0125] 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 a separated liquid.

[0126] 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.

[0127] 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%, and the rest was nitrogen. Upon testing, the calcined product was silicon dioxide, recorded as silicon dioxide product.

[0128] In step S2 of this embodiment, the reaction process is gentle, without liquid splashing, white smoke, obvious heat generation, or blockage.

[0129] See also Figure 7 As shown, the silicon dioxide 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%.

[0130] 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.

[0131] Comparative Example 1 Compared with Example 1, in this comparative example, silicon tetrachloride and the aqueous solution are directly reacted.

[0132] The steps of this comparative example are: S1, mixing deionized water and cetyltrimethylammonium bromide (CTAB) to obtain an aqueous solution of cetyltrimethylammonium bromide; in the aqueous solution, the mass concentration of cetyltrimethylammonium bromide is 2%.

[0133] S2, adding liquid silicon tetrachloride 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.

[0134] S3, aging the first treatment liquid at room temperature for 6 hours to obtain a second treatment liquid; the second treatment liquid contains an aqueous phase and an organic phase.

[0135] 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 a separated liquid.

[0136] 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.

[0137] 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%, and the rest was nitrogen. Upon testing, the calcined product was silicon dioxide, recorded as silicon dioxide product.

[0138] In step S2 of this comparative example, silicon tetrachloride and water undergo a violent hydrolysis reaction, with liquid splashing, white smoke, and significant heat generation; during the reaction, the dropper nozzle encounters moisture in the air and becomes clogged.

[0139] In this comparative example, the SEM of the silica product is shown in Figure 8 As shown, the silicon dioxide product obtained in this comparative example was polymerized and had a poor morphology.

[0140] Comparative Example 2 Compared with Example 1, the proportion of the aqueous solution in this comparative example is reduced.

[0141] The steps of this comparative example are: S1, dissolving liquid silicon tetrachloride in toluene to obtain an organic solution of silicon tetrachloride; in the organic solution, the volume concentration of silicon tetrachloride is 5%.

[0142] Deionized water and cetyltrimethylammonium bromide (CTAB) are mixed to obtain an aqueous solution of cetyltrimethylammonium bromide; in the aqueous solution, the mass concentration of cetyltrimethylammonium bromide is 2%.

[0143] 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.

[0144] 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.

[0145] S4, filtering the second treatment liquid, and then washing the solid separation with deionized water and anhydrous ethanol for three times respectively to obtain a washed solid separation.

[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%, and the rest was nitrogen. Upon testing, the calcined product was silicon dioxide, recorded as silicon dioxide product.

[0147] 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, resulting in poor sphericity of the silica product obtained in this comparative example; in this comparative example, the proportion of particles with a roundness greater than 0.9 is only about 10.8%.

[0148] 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.

[0149] The above technical solutions of the present invention are only preferred embodiments of the present invention, and the patent scope of the present invention is not limited thereto. All equivalent structural changes made by using the contents of the present invention specification 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: Includes steps: S1, providing an organic solution and water, wherein the organic solution comprises 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 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 product of silicon dioxide 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 also 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: 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%.

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 water contains a cationic surfactant; the mass concentration of the cationic surfactant in the water is 0.5-25%; the cationic surfactant includes hexadecyltrimethylammonium bromide.

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 carried out 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 the 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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