Process for producing high-purity nanosilica

Abstract

The application belongs to the technical field of silica preparation, and specifically provides a production process of high-purity nano-silica, which comprises the following steps: taking quartz sand for acid immersion, then reacting with hydrofluoric acid to obtain a fluosilicic acid solution, adding concentrated sulfuric acid to the fluosilicic acid solution to prepare silicon tetrafluoride gas, and then performing hydrolysis, filtration, washing, drying and calcination on the silicon tetrafluoride gas to obtain high-purity nano-silica; a dispersing agent is added in the hydrolysis process; the preparation raw materials of the dispersing agent used in the application include maltose and N-hydroxysuccinimide. The nano-silica prepared by the application has a higher specific surface area and purity, and a smaller and more uniform particle size.

Description

Technical Field

[0001] This application belongs to the field of silica preparation technology, and in particular relates to a production process for high-purity nano silica. Background Technology

[0002] Nano-silica, as an important inorganic functional material, plays an irreplaceable role in many fields due to its small size effect, surface interface effect, quantum size effect, and macroscopic quantum tunneling effect. High-purity nano-silica, with its extremely high purity and uniform nanoscale particle size, is widely used in key fields such as electronics, optics, and catalysis. One existing silica preparation process uses quartz sand as raw material, prepares silicon tetrafluoride via a fluorosilicic acid route, and then obtains silica through hydrolysis and other steps. However, this route suffers from severe particle agglomeration during the preparation of nanopowders, significantly limiting product quality.

[0003] Therefore, effectively controlling the dispersion state and suppressing particle aggregation during the silica formation process has become a core technical challenge in the preparation of high-performance, high-purity nano-silica. Meanwhile, existing preparation processes generally suffer from low product purity, further limiting the industrial production and high-end applications of high-purity nano-silica. In summary, developing a preparation process that can effectively control particle dispersion and aggregation and improve product purity is of great significance and value for promoting the development of the high-end materials industry. Summary of the Invention

[0004] To address the aforementioned issues and further improve the purity of silica products, reduce aggregation during the production process, and thus enable the produced silica to have a higher specific surface area and smaller particle size, this application provides a production process for high-purity nano-silica.

[0005] A process for producing high-purity nano-silica includes the following steps: quartz sand is acid-leached, then reacted with hydrofluoric acid to obtain a fluorosilicic acid solution, concentrated sulfuric acid is added to the fluorosilicic acid solution to obtain silicon tetrafluoride gas, and the silicon tetrafluoride gas is hydrolyzed, filtered, washed, and calcined to obtain high-purity nano-silica. A dispersant is added during the hydrolysis process; The raw materials for preparing the dispersant include maltose and N-hydroxysuccinimide; The washing solution is a water-ethanol mixture.

[0006] Furthermore, the preparation method of the dispersant includes the following steps: maltose and succinic anhydride are mixed and subjected to esterification reaction. The resulting reaction solution is added to ethanol for precipitation, separation, washing, and drying to obtain a carboxylated intermediate. The carboxylated intermediate is mixed with deionized water, and then 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide are added. The mixture is reacted for a period of time, and the resulting product system is added to ethanol for precipitation, separation, washing, and drying to obtain the dispersant.

[0007] Furthermore, the purity of the quartz sand is ≥99%.

[0008] Furthermore, the acid leaching solution used in the acid leaching is composed of hydrochloric acid, nitric acid, and hydrofluoric acid.

[0009] Furthermore, the amount of dispersant added during the hydrolysis process is 0.05%-0.06% of the mass of deionized water.

[0010] Furthermore, the hydrolysis process parameters are: reaction temperature 50-60℃, silicon tetrafluoride introduction rate 1.5-2.2m. 3 / h.

[0011] Furthermore, the drying temperature is 100-150℃; the calcination temperature is 500-550℃, and the calcination time is 2-4 hours.

[0012] Furthermore, the mass ratio of water to ethanol in the water-ethanol mixture is 1:(1.2-2).

[0013] Furthermore, the mass ratio of maltose to succinic anhydride is 1:(0.3-0.35).

[0014] Furthermore, the esterification reaction is carried out at a temperature of 25-40°C for a time of 10-12 hours.

[0015] Compared with the prior art, this application has the following beneficial effects: The NHS active ester groups, acting as hydrophobic ends, are distributed on the silica surface, while maltose, acting as a hydrophilic group, faces the water end, forming a hydration layer. This reduces silica aggregation and makes the silica particle size distribution more uniform. During the washing process, under the action of a neutral washing solution, the NHS active ester bonds break, and the maltose groups detach. The detached maltose groups form carboxyl groups at their ends, which can coordinate with metal ions. During the washing process, metal ions are continuously carried away, thereby reducing the presence of impurities in the silica and improving the silica purity. Furthermore, after the maltose groups detach, the residual structure of the dispersant cannot continue to form a hydration layer, which is beneficial for washing away the dispersant and avoiding the introduction of further impurities. Attached Figure Description

[0016] Figure 1This is a particle size distribution diagram of high-purity nano-silica from Example 1 of this application.

[0017] Figure 2 This is a particle size distribution diagram of high-purity nano-silica in Example 2 of this application.

[0018] Figure 3 This is a particle size distribution diagram of high-purity nano-silica in Example 3 of this application.

[0019] Figure 4 This is a particle size distribution diagram of high-purity nano-silica, which is Comparative Example 1 of this application. Detailed Implementation

[0020] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0022] When using “including,” “having,” and “contains” as described herein, the intention is to cover non-exclusive inclusion, unless an explicit qualifying term such as “only,” “consisting of,” etc., is used, in which case another component may be added.

[0023] The terms "preferred," "more preferably," "better," and "even better" used in this application refer to embodiments of this application that provide certain beneficial effects under certain circumstances. However, other embodiments may also be preferred under the same or other circumstances. Furthermore, the description of one or more preferred embodiments does not imply that other embodiments are unavailable, nor is it intended to exclude other embodiments from the scope of this application. That is, in this application, "preferred," "more preferably," "better," and "even better" are merely descriptions of implementations or embodiments with better effects, but do not constitute a limitation on the scope of protection of this application.

[0024] In this application, terms such as "further," "even more," and "particularly" are used for descriptive purposes and indicate differences in content, but should not be construed as limiting the scope of protection of this application.

[0025] In this application, "at least one" means one or more, such as one, two, or more. "Multiple" or "several" means at least two, such as two, three, etc., and "multi-layered" means at least two layers, such as two layers, three layers, etc., unless otherwise explicitly specified. In the description of this application, "several" means at least one, such as one, two, etc., unless otherwise explicitly specified.

[0026] When a numerical range is disclosed herein, the range is considered continuous and includes the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0027] Unless otherwise specified, all steps in this application may be performed sequentially or randomly. For example, the method comprising steps (a) and (b) indicates that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order; for example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc. Unless otherwise stated, singular terms may include plural forms and should not be construed as having a quantity of one.

[0028] In this application, "above" or "below" includes the number itself. For example, "below 1" includes 1.

[0029] In this application, room temperature refers to 0-40°C, including but not limited to 10-40°C, or further to 20-30°C.

[0030] The present application will be further illustrated by the following examples, but these examples do not limit the scope of the present application.

[0031] When numerical ranges are given in the embodiments, it should be understood that, unless otherwise stated in this application, both endpoints of each numerical range and any value between the two endpoints may be selected. Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. All reagents or instruments whose manufacturers are not specified are conventional products that can be purchased commercially. In addition to the specific methods, equipment, and materials used in the embodiments, based on the knowledge of the prior art possessed by one of ordinary skill in the art and the description in this application, any prior art methods, equipment, and materials similar to or equivalent to those described, used, or made by the methods, equipment, and materials in the embodiments of this application may be used to implement this application.

[0032] Example 1 The preparation method of high-purity nano-silica in this embodiment is as follows: 400g of quartz sand (mesh size: 200 mesh, purity: 99%) is immersed in an acid leaching solution composed of 36wt% hydrochloric acid, 65wt% nitric acid, and 40wt% hydrofluoric acid in a mass ratio of 3:1:1. The acid leaching temperature is 85℃, and the acid leaching time is 2h. After filtration, washing, and drying, the solution is placed in a dissolving tank, and 2kg of 40wt% hydrofluoric acid is added and mixed. The mixture is stirred for 3.5h. The resulting solution is transferred to a reaction vessel, and 2.1kg of 98wt% concentrated sulfuric acid is added at a rate of 14.2mL / min. The mixture is stirred at 90℃ until almost no silicon tetrafluoride gas is released. The resulting silicon tetrafluoride gas is then introduced into a hydrolyzer for hydrolysis. The hydrolyzer contains 18L of a dispersant-deionized water mixed solution (the amount of dispersant added is 0.05% of the mass of deionized water). The silicon tetrafluoride flow rate is 1.5m³. 3 The hydrolysis reaction was carried out at a rate of 50°C per hour. After separation, the filter cake was washed with a water-ethanol mixture (water to ethanol mass ratio of 1:1.2), and then dried at 100°C for 10 hours. After drying, calcination was carried out at a heating rate of 4°C / min until it reached 500°C. The temperature was then maintained for 3 hours to obtain high-purity nano-silica.

[0033] The method for preparing the dispersant in this embodiment is as follows: 1) First, take 100 mL of dimethyl sulfoxide and put it into a flask. Add 5 g of maltose, 1.5 g of succinic anhydride and 0.1 g of catalyst 4-dimethylaminopyridine. React at 25 °C for 12 h. Add the resulting reaction solution to twice the volume of ethanol for precipitation. Centrifuge at 5000 r / min. Wash the obtained solid component with ethanol and dry it at room temperature to obtain the carboxylated intermediate. 2) Place the carboxylation intermediate into a flask, add 300g of deionized water, stir at 300rpm for 30min at room temperature, then add 3g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 1.6g of N-hydroxysuccinimide, and continue stirring for 40min. The resulting product system is added to ethanol for precipitation, centrifuged at 4500r / min, and the obtained solid component is washed with ethanol and dried at room temperature to obtain the dispersant.

[0034] Example 2 The preparation method of high-purity nano-silica in this embodiment is as follows: 400g of quartz sand (mesh size: 200 mesh, purity: 99%) is immersed in an acid leaching solution composed of 36wt% hydrochloric acid, 65wt% nitric acid, and 40wt% hydrofluoric acid in a mass ratio of 3:1:1. The acid leaching temperature is 85℃, and the acid leaching time is 2h. After filtration, washing, and drying, the solution is placed in a dissolving tank, and 2.2kg of 40wt% hydrofluoric acid is added and mixed. The mixture is stirred for 3.5h. The resulting solution is transferred to a reaction vessel, and 2.2kg of 98wt% concentrated sulfuric acid is added at a rate of 14.2mL / min. The mixture is stirred at 90℃ until almost no silicon tetrafluoride gas is released. The resulting silicon tetrafluoride gas is then introduced into a hydrolyzer for hydrolysis. The hydrolyzer contains 20L of a dispersant-deionized water mixed solution (the amount of dispersant added is 0.06% of the mass of deionized water). The silicon tetrafluoride flow rate is 2.2m. 3 The hydrolysis reaction was carried out at a temperature of 60℃. After separation, the filter cake was washed with a water-ethanol mixture (water to ethanol mass ratio of 1:2), and then dried at 150℃ for 8 hours. After drying, calcination was carried out at a heating rate of 4℃ / min until it reached 550℃, and then held at that temperature for 3 hours to obtain high-purity nano-silica.

[0035] The method for preparing the dispersant in this embodiment is as follows: 1) First, take 100 mL of dimethyl sulfoxide and put it into a flask. Add 5 g of maltose, 1.75 g of succinic anhydride and 0.12 g of catalyst 4-dimethylaminopyridine. React at 40 °C for 10 h. Add the resulting reaction solution to twice the volume of ethanol for precipitation. Centrifuge at 5000 r / min. Wash the obtained solid component with ethanol and dry it at room temperature to obtain the carboxylated intermediate. 2) Place the carboxylation intermediate into a flask, add 350g of deionized water, stir at 300rpm for 30min at room temperature, then add 3g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 1.7g of N-hydroxysuccinimide, and continue stirring for 40min. The resulting product system is added to ethanol for precipitation, centrifuged at 4500r / min, and the obtained solid component is washed with ethanol and dried at room temperature to obtain the dispersant.

[0036] Example 3 The preparation method of high-purity nano-silica in this embodiment is as follows: 450g of quartz sand (mesh size: 200 mesh, purity: 99%) is immersed in an acid leaching solution composed of 36wt% hydrochloric acid, 65wt% nitric acid, and 40wt% hydrofluoric acid in a mass ratio of 3:1:1. The acid leaching temperature is 85℃, and the acid leaching time is 2h. After filtration, washing, and drying, the solution is placed in a dissolving tank, and 2.2kg of 40wt% hydrofluoric acid is added and mixed. The mixture is stirred for 3.5h. The resulting solution is transferred to a reaction vessel, and 2.2kg of 98wt% concentrated sulfuric acid is added at a rate of 14.2mL / min. The mixture is stirred at 90℃ until almost no silicon tetrafluoride gas is released. The resulting silicon tetrafluoride gas is then introduced into a hydrolyzer for hydrolysis. The hydrolyzer contains 18L of a dispersant-deionized water mixed solution (the amount of dispersant added is 0.052% of the mass of deionized water). The silicon tetrafluoride flow rate is 2m³ / min. 3 The hydrolysis reaction was carried out at a temperature of 55℃. After separation, the filter cake was washed with a water-ethanol mixture (the mass ratio of water to ethanol was 1:1.3), and then dried at 110℃ for 9 hours. After drying, calcination was carried out at a heating rate of 4℃ / min until it reached 520℃. The temperature was then maintained for 3 hours to obtain high-purity nano-silica.

[0037] The method for preparing the dispersant in this embodiment is as follows: 1) First, take 100 mL of dimethyl sulfoxide and put it into a flask. Add 5 g of maltose, 1.6 g of succinic anhydride and 0.1 g of catalyst 4-dimethylaminopyridine. React at 35 °C for 11.5 h. Add the resulting reaction solution to twice the volume of ethanol for precipitation. Centrifuge at 5000 r / min. Wash the obtained solid component with ethanol and dry it at room temperature to obtain the carboxylated intermediate. 2) Place the carboxylation intermediate into a flask, add 300g of deionized water, stir at 300rpm for 30min at room temperature, then add 3g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 1.6g of N-hydroxysuccinimide, and continue stirring for 40min. The resulting product system is added to ethanol for precipitation, centrifuged at 4500r / min, and the obtained solid component is washed with ethanol and dried at room temperature to obtain the dispersant.

[0038] Control group 1 The difference between this control group and Example 1 is that the dispersant used is OP-10. All other steps are the same as in Example 1.

[0039] Performance testing 1. Purity Testing: The purity of nano-silica was tested using inductively coupled plasma atomic emission spectrometry (ICP-MS). The test results are shown in Table 1.

[0040] 2. Specific surface area test: The specific surface area of ​​nano-silica was determined using a specific surface area and porosity analyzer (BET). The test results are shown in Table 1.

[0041] 3. The particle size distribution of nano-silica was characterized using a laser particle size analyzer. The test results are as follows: Figure 1-4 As shown.

[0042] Table 1 Performance test data of nano-silica in Examples 1-3 and Comparative Example 1 Combined with Table 1 and Figure 1-4 Analysis of Examples 1-3 and Comparative Example 1 shows that the dispersant prepared in this application can improve the specific surface area and purity of silica by dispersing and chelating and adsorbing metal impurities during the production process of nano silica. The good dispersing effect also makes the particle size distribution of silica more concentrated and reduces agglomeration, thereby giving silica a smaller average particle size.

[0043] Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A production process for high-purity nano-silica, characterized in that: The process includes the following steps: quartz sand is acid-leached, then reacted with hydrofluoric acid to obtain a fluorosilicic acid solution. Concentrated sulfuric acid is added to the fluorosilicic acid solution to produce silicon tetrafluoride gas. The silicon tetrafluoride gas is then hydrolyzed, filtered, washed, dried, and calcined to obtain high-purity nano-silica. A dispersant is added during the hydrolysis process; The raw materials for preparing the dispersant include maltose and N-hydroxysuccinimide; The washing solution is a water-ethanol mixture.

2. The production process of high-purity nano-silica according to claim 1, characterized in that: The preparation method of the dispersant includes the following steps: maltose and succinic anhydride are mixed and subjected to esterification reaction. The resulting reaction solution is added to ethanol for precipitation, separation, washing, and drying to obtain a carboxylated intermediate. The carboxylated intermediate is mixed with deionized water, and then 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide are added. The mixture is reacted for a period of time, and the resulting product system is added to ethanol for precipitation, separation, washing, and drying to obtain the dispersant.

3. The production process of high-purity nano-silica according to claim 1, characterized in that: The purity of the quartz sand is ≥99%.

4. The production process of high-purity nano-silica according to claim 1, characterized in that: The acid leaching solution used in the acid leaching process consists of hydrochloric acid, nitric acid, and hydrofluoric acid.

5. The production process of high-purity nano-silica according to claim 1, characterized in that: The amount of dispersant added during the hydrolysis process is 0.05%-0.06% of the mass of deionized water.

6. The production process of high-purity nano-silica according to claim 1, characterized in that: The hydrolysis process parameters are: reaction temperature 50-60℃, silicon tetrafluoride introduction rate 1.5-2.2m. 3 / h.

7. The production process of high-purity nano-silica according to claim 1, characterized in that: The drying temperature is 100-150℃; the calcination temperature is 500-550℃, and the calcination time is 2-4 hours.

8. The production process of high-purity nano-silica according to claim 1, characterized in that: The mass ratio of water to ethanol in the water-ethanol mixture is 1:(1.2-2).

9. The production process of high-purity nano-silica according to claim 2, characterized in that: The mass ratio of maltose to succinic anhydride is 1:(0.3-0.35).

10. The production process of high-purity nano-silica according to claim 2, characterized in that: The esterification reaction is carried out at a temperature of 25-40℃ for 10-12 hours.

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