A method for preparing high-purity silica sol and hydrogen chloride

Abstract

The present invention relates to the technical field of silica sol preparation, and in particular to a method for preparing high-purity silica sol and hydrogen chloride, comprising the following steps: adding a higher alcohol to a reactor, heating to melt the higher alcohol; adding silicon tetrachloride to the reactor, fully reacting silicon tetrachloride with the molten higher alcohol to generate silicate and hydrogen chloride, during the reaction, the higher alcohol and the generated silicate are kept in a heated and melted state, and the hydrogen chloride is discharged from the reactor in the form of gas and collected; the substances in the reactor are kept in a heated and melted state, and an excess of water is added to the reactor to completely hydrolyze the silicate to generate silica hydrosol and higher alcohol; cooling the reactor until the higher alcohol is converted into a solid state and the silica hydrosol remains in a liquid state; and separating the liquid silica hydrosol from the solid higher alcohol. The method for preparing high-purity silica sol of the present application has the advantages of preparing ultra-high purity silica sol and separating hydrogen chloride at a low cost.

Description

Technical Field

[0001] The invention relates to the technical field of silica sol preparation, in particular to a method for preparing high-purity silica sol and hydrogen chloride. Background Art

[0002] As chip manufacturing technology improves, the requirements for metal ions in the manufacturing process are getting higher and higher. Chemical mechanical polishing is one of the key steps in chip manufacturing, and the control of metal ion contamination in the polishing liquid used for chemical mechanical polishing has also increased. Metal ion contamination in the polishing liquid mainly comes from abrasives, so in advanced processes, polishing liquids using ultra-high purity silica sol as abrasives are becoming more and more widely used. The sodium and potassium content of silica sol prepared by the conventional water glass method and silicon powder method gradually cannot meet the demand even after subsequent ion exchange purification.

[0003] The current preparation of ultra-high purity silica sol (total metal ion content less than 1ppm) originated from 1968 The method summarized by W. A Fink, and E.Bohn, J.Colloid Interface Sci., 26, 62 (1968)). This method uses low-grade silicate as raw material, usually tetramethyl silicate or tetraethyl silicate, which is hydrolyzed and polymerized in a mixed solution of low-grade alcohol, water and ammonia to generate silica sol:

[0004] Si(OR)4+2H2O→SiO2+4ROH, R=CH3- or CH3CH2-

[0005] This method does not require the addition of inorganic alkalis, and there is no metal pollution during the production process, so the metal ion content of the silica sol can be controlled by the purity of the silicate. However, the ultra-high purity silicate required by this method is expensive, and the subsequent separation of the silica sol and alcohol requires distillation, which is energy-consuming and time-consuming, resulting in the price of the produced silica sol being dozens to hundreds of times higher than that of ordinary water glass method or silicon powder method. Currently, only Japan's Fuso Chemical Industry Co., Ltd. can reduce the price to several to dozens of times the price of ordinary silica sol through self-production of ultra-high purity silicate and scale effect, so its market share exceeds 90%, and it is difficult for other suppliers to enter this market.

[0006] The booming development of my country's photovoltaic industry has brought with it a large amount of silicon tetrachloride byproducts, and its reasonable and environmentally friendly reuse is a problem that needs to be solved urgently. Silicon tetrachloride can also be used as a raw material for the production of silica sol. The current industrial method is to burn silicon tetrachloride gas in oxygen and hydrogen or natural gas flames to generate agglomerated nano-silicon dioxide, and then mechanically disperse it into silica sol. Although the silica sol prepared by this gas phase method has a low metal ion content, it is easy to cause scratches on the polishing surface when used in the polishing liquid for chip manufacturing, so it cannot be used in advanced processes.

[0007] At present, the direct or indirect preparation of silica sol by hydrolysis of silicon tetrachloride is a hot topic in this field. Many researchers have proposed different preparation methods, but there is no suitable method for separating the hydrogen chloride byproduct:

[0008] SiCl4+2H2O→SiO2+4HCl

[0009] The difficulty lies in the fact that the hydrolysis of silicon tetrachloride requires water, and the generated hydrogen chloride byproduct is very easy to combine with water. In addition to the supersaturated hydrogen chloride escaping in the form of gas, some hydrogen chloride remains in the system in the form of hydrochloric acid. In addition, the hydrolysis reaction of silicon tetrachloride is very violent and difficult to control. Some researchers have proposed to first use ethanol and silicon tetrachloride to generate ethyl silicate, and then use The method is to hydrolyze ethyl silicate to generate silica sol (e.g. Yonghong Su et al. Journal of the Korean Ceramic Society, Vol. 55, No. 6, pp. 562-569, 2018):

[0010] SiCl4+4C2H5OH→Si(OC2H5)4+4HCl

[0011] Si(OC2H5)4+2H2O→SiO2+4C2H5OH

[0012] Although this method slows down the reactivity of hydrolysis to form silica sol, it does not solve the problem of removing hydrogen chloride in the first step of alcoholysis of silicon tetrachloride, because the solubility of hydrogen chloride in lower alcohols is similar to that in water and cannot be completely discharged in the form of gas. This requires a alkali neutralization step that introduces a large amount of metal ions or organic amines, and the chloride ion concentration in silica sol is very high and cannot meet the requirements. If the silicate is prepared in the first step and then fractionated and purified, and then the second step of silicate hydrolysis is carried out, it is similar to The method is exactly the same, there is no cost saving step.

[0013] In summary, separating hydrogen chloride and reducing manufacturing costs are two urgent problems to be solved in preparing ultra-high purity silica sol using silicon tetrachloride as raw material. Summary of the invention

[0014] In order to prepare ultra-high purity silica sol and separate hydrogen chloride at low cost, the present invention provides a method for preparing high purity silica sol and hydrogen chloride in view of the problems of the prior art.

[0015] In the first aspect, the present invention provides a method for preparing high-purity silica sol and hydrogen chloride, which adopts the following technical scheme:

[0016] A method for preparing high-purity silica sol and hydrogen chloride comprises the following steps:

[0017] S1: Add higher alcohol into a reaction kettle and heat to melt the higher alcohol;

[0018] S2: adding silicon tetrachloride to the reaction kettle, and reacting silicon tetrachloride with molten higher alcohol to generate silicate and hydrogen chloride. During the reaction, the higher alcohol and the generated silicate are kept in a heated and molten state, and the hydrogen chloride is discharged from the reaction kettle in the form of gas and collected;

[0019] S3: Keeping the reactor heated, adding excess water into the reactor to hydrolyze the silicate to generate silica hydrosol and higher alcohol;

[0020] S4: Cooling the reactor until the higher alcohol is converted into a solid state and the silica hydrosol remains in a liquid state;

[0021] S5: Separating the liquid silica hydrosol from the solid higher alcohol.

[0022] The higher alcohol molecule contains one and no more than one hydroxyl group, the higher alcohol does not contain unsaturated bonds, the melting point range of the higher alcohol under standard atmospheric pressure is 15-100° C., and the water solubility of the higher alcohol under standard atmospheric pressure and 25° C. is less than 1000 mg / L.

[0023] Preferably, in step S2, the molar ratio of silicon tetrachloride to higher alcohol added into the reaction kettle is in the range of silicon tetrachloride / higher alcohol < 0.25.

[0024] Preferably, the higher alcohol is one or a mixture of several of the following: dodecanol, tetradecanol, hexadecanol, octadecanoic acid, eicosanol, behenyl alcohol, tetracosanol, hexacosanol, octacosanol, menthol, fennel alcohol, tert-butyl cyclohexanol, and cyclododecanoic acid.

[0025] Preferably, in steps S1, S2 and S3, the heating temperature is not higher than 100°C.

[0026] Preferably, in steps S1, S2 and S3, the heating temperature ranges from 45 to 85°C.

[0027] Preferably, in the step S3, the temperature of the added water is not less than the temperature in the reactor.

[0028] Preferably, in step S3, the temperature of the added water is in the range of 45-90°C.

[0029] Preferably, in the step S2, silicon tetrachloride is added by blowing into the reactor with dry air or inert gas as a carrier, and hydrogen chloride is discharged by blowing out of the reactor with dry air or inert gas introduced into the reactor, and the discharged hydrogen chloride enters another reactor containing water, wherein the hydrogen chloride reacts with water and is collected in the form of a hydrochloric acid solution.

[0030] Preferably, in the step S3, the added water may be added with an alkaline pH regulator that does not contain metal ions to adjust the pH to greater than 7, and the pH regulator is one or a mixture of several combinations of ammonia, tetraalkylammonium hydroxide, organic amine, guanidine, and amino acids whose aqueous solutions are alkaline.

[0031] In a second aspect, the present invention provides a high-purity silica sol, which is a silica sol prepared by the method described above.

[0032] In a third aspect, the present invention provides high-purity hydrogen chloride, which is hydrogen chloride prepared by the method described above.

[0033] In summary, the present invention includes the following beneficial technical effects:

[0034] Without being limited by theory, it is believed that as the number of carbon atoms in the molecule of alcohol increases, its melting point increases, its water solubility decreases, and the solubility of hydrogen chloride therein also decreases. By selecting a suitable higher alcohol to react with silicon tetrachloride, hydrogen chloride is insoluble or almost insoluble in the higher alcohol, so that hydrogen chloride can be completely or almost completely separated in the form of gas, and there is no residue or very little residue in the higher alcohol and the corresponding silicate, so that subsequent treatments such as fractionation are not required, which greatly simplifies the preparation of silicate. At the same time, the solubility of the selected higher alcohol in water is very low and its melting point is relatively high. After the hydrolysis of its corresponding silicate is completed, the separation of the higher alcohol and the silica sol can be carried out by simple solid-liquid separation, and distillation separation is not required, which greatly simplifies the preparation of silica sol and reduces the preparation cost. The present invention is suitable for industrial large-scale environmentally friendly and energy-saving preparation of ultra-high purity silica sol and hydrogen chloride using silicon tetrachloride as a raw material, so that silicon tetrachloride, a byproduct of the photovoltaic industry, can be turned into treasure. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 is a flow chart of the method provided by the present application;

[0036] Figure 2 This is a scanning electron microscope image of the silica sol in Example 1 of the present application; DETAILED DESCRIPTION

[0037] As used herein, the terms "consisting of," "including," "comprising," "having," "having" or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a process, method, article, or apparatus that comprises a list of features is not necessarily limited to only those features but may include other features not expressly listed or inherent to such process, method, article, or apparatus.

[0038] As used herein, unless otherwise expressly stated, "or" refers to an inclusive "or" rather than an exclusive "or". For example, any of the following may satisfy condition A or B: A is true (or exists) and B is false (or does not exist), A is false (or does not exist) and B is true (or exists), and both A and B are true (or exist). The present application is further described in detail below in conjunction with the embodiments.

[0039] The present invention provides a method for preparing high-purity silica sol and hydrogen chloride. Specifically, the present invention uses a higher alcohol to react with silicon tetrachloride to generate silicate and hydrogen chloride, and then reacts the silicate with water to generate silicon dioxide hydrosol. Figure 1 As shown, the following steps are included:

[0040] S1: Add higher alcohol into a reaction kettle and heat to melt the higher alcohol;

[0041] S2: adding silicon tetrachloride to the reaction kettle, and reacting silicon tetrachloride with molten higher alcohol to generate silicate and hydrogen chloride. During the reaction, the higher alcohol and the generated silicate are kept in a heated and molten state, and the hydrogen chloride is discharged from the reaction kettle in the form of gas and collected;

[0042] S3: Keeping the reactor heated, adding excess water into the reactor to hydrolyze the silicate to generate silica hydrosol and higher alcohol;

[0043] S4: Cooling the reactor until the higher alcohol is converted into a solid state and the silica hydrosol remains in a liquid state;

[0044] S5: Separating the liquid silica hydrosol from the solid higher alcohol.

[0045] Higher alcohols: The preparation of silicates requires alcohols to react with silicon tetrachloride. The alcohols used in the present invention are required to have a melting point between 15°C and 100°C at a standard atmospheric pressure. Usually, only alcohols containing enough carbon atoms can reach the melting point required by this method, so they are called higher alcohols. The reason why the melting point is required to be not less than 15°C is that in the subsequent separation step of silica sol and alcohol, the silica sol can be solidified by cooling to a temperature lower than the melting point of the alcohol while the silica sol remains in a liquid state, so that a simple solid-liquid separation can be used without distillation separation. The higher the melting point of the alcohol, the easier it is to cool and solidify, so the melting point is preferably not less than 16°C, more preferably not less than 17°C, more preferably not less than 18°C, more preferably not less than 19°C, and more preferably not less than 20°C. On the other hand, the melting point of the selected alcohol should not be greater than 100°C, otherwise water will evaporate easily in the silicate hydrolysis step. It is preferably not greater than 95°C, more preferably not greater than 90°C, more preferably not greater than 89°C, more preferably not greater than 88°C, more preferably not greater than 87°C, more preferably not greater than 86°C, and more preferably not greater than 85°C.

[0046] The higher alcohol used in the present invention is also required to have a water solubility of less than 1000 mg / L at 25°C and a standard atmospheric pressure. If the water solubility is too high, it is not conducive to the subsequent separation from the silica sol. Preferably, the water solubility is less than 800 mg / L, more preferably less than 500 mg / L, and more preferably less than 100 mg / L.

[0047] The higher alcohol used in the present invention is also required to contain no more than one hydroxyl group in the molecular formula, that is, the higher alcohol is a monohydric alcohol. Without being limited by theory, it is believed that the alcohol containing two or more hydroxyl groups may react with silicon tetrachloride to form oligomeric or polymeric silicates, which have a higher melting point than the non-polymerized silicates or the above alcohols, and thus may be solid at the original reaction temperature and encapsulate the liquid alcohol that has not reacted with silicon tetrachloride, resulting in incomplete reaction.

[0048] The higher alcohol used in the present invention is also required to contain no unsaturated bonds in the molecular formula. Without being limited by theory, it is believed that the unsaturated bonds are chemically active and may react with silicon tetrachloride or hydrogen chloride so that the higher alcohol is continuously consumed, making it impossible to recycle the higher alcohol.

[0049] The alcohol meeting the above conditions can be a linear or substantially linear higher monohydric alcohol of carbon atom arrangement, for example dodecanol, tridecanol, tetradecanol, pentadecanol, hexadecanol, heptadecanol, octadecanoyl alcohol, nonadecanol, eicosanol, heneicosanol, docosanol, tricosanol, tetracosanol, pentacosanol, hexacosanol, heptadecanol, octacosanol, nonacosanol, triacontanol or its mixture.Preferred dodecanol, tetradecanol, hexadecanol, octadecanoyl alcohol, eicosanol, docosanol, tetracosanol, hexacosanol, octacosanol, triacontanol or its mixture, more preferably, select dodecanol, tetradecanol, hexadecanol, octadecanoyl alcohol, eicosanol, docosanol, tetracosanol, hexacosanol, octacosanol or its mixture.The alcohol meeting the above conditions can also be a cyclic higher monohydric alcohol containing carbon atom arrangement in the molecule, for example cyclododecanol, menthol, anise alcohol, 4-tert-butyl cyclohexanol, or its mixture.The alcohol meeting the above conditions can also be a mixture of the above-mentioned linear higher monohydric alcohol and the above-mentioned cyclic higher monohydric alcohol.

[0050] Heating: Since the higher alcohol used in the present invention has a high melting point, it needs to be heated to melt it into a liquid in order to fully react with silicon tetrachloride. The heating temperature must not only be higher than the melting point of the selected higher alcohol, but also be greater than the melting point of the corresponding silicate to ensure that the reaction proceeds smoothly. Without being limited by theory, experiments have shown that the melting point of the silicate generated by the reaction of the higher alcohol selected under the above conditions with silicon tetrachloride is similar to that of the corresponding higher alcohol, and there can be a suitable temperature range to keep both of them in a liquid state. At the same time, heating also helps the hydrolysis reaction of the silicate hydrolysis step. On the other hand, the heating temperature should not be too high to cause a large amount of water evaporation in the hydrolysis step. Therefore, the heating temperature is not easy to be higher than 100°C, preferably, between 45°C and 85°C. The esterification step and the hydrolysis step can be kept at the same temperature, and ordinary professionals in this field can also choose to carry out the above two steps at different temperatures according to needs, as long as the reactants and products are kept in liquid during the reaction.

[0051] Addition of silicon tetrachloride: After the selected higher alcohol is completely melted, silicon tetrachloride can be added. In the present invention, the amount of silicon tetrachloride added is preferably insufficient, that is, the amount of higher alcohol is excessive, to ensure that silicon tetrachloride reacts completely. Since the selected alcohol is a monohydric alcohol, one silicon tetrachloride molecule needs to react with four alcohol molecules, so the molar amount of silicon tetrachloride added and the molar amount of the above-mentioned higher alcohol comply with the following relationship: silicon tetrachloride / higher alcohol <0.25. Ordinary professionals in this field can optimize the amount of silicon tetrachloride added according to the selected higher alcohol.

[0052] Silicon tetrachloride is in liquid form at room temperature and is volatile. It can be added in liquid form or in gas form. The speed of addition should generally not be greater than the reaction speed of silicon tetrachloride and alcohol so that it can react completely without escaping. If a closed reactor is selected for alcoholysis reaction, silicon tetrachloride can be added at a speed greater than the alcoholysis speed because there is no escape route. A person of ordinary skill in the art can optimize the speed of adding silicon tetrachloride according to the selected alcohol, heating temperature and reaction device. The metal impurities in silicon tetrachloride are the main source of metal impurities in silica sol. Therefore, it is advisable to select a silicon tetrachloride purity that matches the requirements of metal impurities in silica sol. From this aspect, it is preferably added in gas form because this is equivalent to purifying silicon tetrachloride once more. The gas form can be selected by heating to convert silicon tetrachloride into gas, or it can be blown into a non-closed reactor with air or inert gas as a carrier by utilizing the volatile property of silicon tetrachloride. It is preferably blown into air or inert gas as a carrier, and more preferably blown into with dried air or inert gas as a carrier to prevent silicon tetrachloride from reacting with the moisture therein. The addition rate of silicon tetrachloride can be controlled by the flow rate of the carrier and the temperature of silicon tetrachloride.

[0053] Collection of hydrogen chloride: Silicon tetrachloride reacts with alcohol to generate silicate and hydrogen chloride. Without being limited by theory, experiments show that the solubility of hydrogen chloride in the selected higher alcohol and the corresponding silicate is very low, so hydrogen chloride exists almost entirely in the form of gas. Hydrogen chloride can be collected in the form of gas, or it can be collected in the form of hydrochloric acid by passing hydrogen chloride into a container containing water. Preferably, dry air or inert gas is introduced into the acid-base resistant reactor, and the hydrogen chloride gas is blown out of the reactor and into another container containing water to be collected in the form of hydrochloric acid.

[0054] Added water: After the esterification is complete and the hydrogen chloride is discharged, water can be added to carry out the hydrolysis step of silicate. The added water can be tap water, distilled water or deionized water. Distilled water and deionized water are preferred according to the requirements for metal impurities in silica sol, and deionized water with a resistance of not less than 18.2 megohms is more preferred. The added water can be pure water, or an aqueous solution with a pH greater than 7 adjusted by an alkaline substance without metal ions. The alkaline substance can be selected from ammonia water, quaternary ammonium base, organic amine, guanidine, or amino acids with alkaline aqueous solution. Adding alkaline substances to adjust the pH of the aqueous solution to greater than 7 is conducive to the hydrolysis of silicate. The simplest judgment of complete esterification and clean discharge of hydrogen chloride is that the pH after hydrolysis with pure water without pH adjustment must be greater than 3, that is, the residual hydrogen chloride in the water is less than about 37ppm. Since the added water is not only used to completely hydrolyze the silicate, but also as a carrier of silica to form silica sol, the amount of water added needs to be excessive, and can preferably be greater than the molar amount of two times the silicate, or greater than the molar amount of two times the silicon tetrachloride. A person skilled in the art can select a suitable amount of water to be added according to the requirements. If the temperature of the added water is too low, the temperature in the reaction kettle may be reduced to below the melting point of the alcohol or silicate and solidify, so the temperature of the added water is preferably not lower than the temperature in the kettle. On the other hand, if the temperature of the water is too high, the evaporation amount is large and it is not conducive to controlling the amount of addition, so it is more preferred that the temperature of the added water is between 45°C and 90°C. In view of the fact that the formation of silica sol must have a nucleation process, a person skilled in the art can also add a small amount of silica sol to the added water to affect the process of hydrolysis to prepare silica sol.

[0055] Mixing method: Since the alcohol selected and the generated ester in the system of the present invention are insoluble or almost insoluble in water, there is a separation of the organic phase and the aqueous phase rather than a uniform phase, and the hydrolysis reaction of the silicate ester only occurs at the interface of the organic phase and the aqueous phase, so increasing the surface area of ​​the organic phase and the aqueous phase in contact is the key to the hydrolysis step. The method of increasing the surface area of ​​the organic phase and the aqueous phase in contact can be stirring, vibration, liquid flow circulation (adding a circulation pipeline to the acid and alkali resistant reactor to make the liquid circulate at high speed to form turbulence), or introducing ultrasound, and also introducing air or inert gas from the bottom of the reactor to disturb the organic phase and the aqueous phase using airflow. Considering the limitations of equipment for large-scale production, stirring is preferred. A person of ordinary skill in the art can also add a surfactant to increase or stabilize the interface of the organic phase and the aqueous phase.

[0056] Separation of silica sol: After the silicate is completely hydrolyzed into the original higher alcohol and silica sol, the system can be cooled to a temperature lower than the melting point of the higher alcohol to solidify it, and the silica sol is kept in a liquid state. Generally, the density of the higher alcohol is lower than that of the silica sol, and the higher alcohol floats on the silica sol in a solid state after cooling. After a simple solid-liquid separation, the silica sol can be obtained, and the higher alcohol can be recovered. The obtained silica sol can be used directly according to demand, or it can be evaporated and concentrated, and it can also replace the water in the above steps and react once or more to increase the solid content.

[0057] Example

[0058] Table 1 lists the melting points and solubility in water of the alcohols used in the examples and comparative examples. The data are mainly derived from experimental data collected by ChemSpider (www.chemspider.com); if ChemSpider does not have experimental data, the experimental data collected by PubChem (pubchem.ncbi.nlm.nih.gov) are used; if neither is available, the experimental data in the "Chemical Safety Data Sheet" of Merck / Sigma-Aldrich is used; if none of the three are available, the calculated data provided by ChemSpider is used. When there is an obvious conflict between the experimental data collected by ChemSpider and PubChem, the experimental data in the "Chemical Safety Data Sheet" of Merck / Sigma-Aldrich is used. When there is no water solubility data at 25°C but there is experimental water solubility data at a similar temperature, the water solubility experimental data at a similar temperature is used.

[0059] Table 1. Melting points and solubility in water of the alcohols used in the examples and comparative examples.

[0060]

[0061]

[0062] [1] Experimental data collected by ChemSpider (www.chemspider.com)

[0063] [2] Experimental data collected by PubChem (pubchem.ncbi.nlm.nih.gov)

[0064] [3] Merck / Sigma-Aldrich SDS

[0065] [4] Calculation data provided by ChemSpider (WSKOW v1.41)

[0066] Example 1

[0067] 400 g of octadecyl alcohol is added to a three-necked flask with a specification of 1000 ml, a magnetic stirring rotor is added to the three-necked flask, a rubber stopper with a silicone tube A is plugged on one of the mouths of the three-necked flask, the silicone tube A is connected to the air inlet of a glass washing bottle A with a specification of 1000 ml, 1000 ml of deionized water is added to the washing bottle A, and then the lid of the washing bottle A is plugged tightly; a rubber stopper with a glass tube is plugged on the second mouth of the three-necked flask, one end of the glass tube extends into the bottom of the three-necked flask, the other end of the glass tube is connected to the air outlet of a glass washing bottle B with a specification of 100 ml by a silicone tube B, and the air inlet of the washing bottle B is connected to an air pump by a silicone tube C;

[0068] Place the three-necked flask in a water bath with magnetic stirring, heat and keep warm at 85°C, and turn on the magnetic stirring after the octadecyl alcohol is completely melted;

[0069] After adding 40g of silicon tetrachloride to the washing bottle B, plug the lid of the washing bottle B tightly, completely seal the three-necked flask, turn on the air pump to let air into the washing bottle B, the air from the washing bottle B carries the silicon tetrachloride gas into the bottom of the three-necked flask and reacts with the molten octadecyl alcohol under stirring to generate silicate and hydrogen chloride, the reaction product hydrogen chloride gas is blown out of the three-necked flask by the air into the washing bottle A to react with water to generate hydrochloric acid, and the liquid in the three-necked flask is milky white liquid;

[0070] After 44 hours, the air pump was turned off, the connection between the washing bottle A and the washing bottle B and the three-necked flask was disconnected, 300 grams of deionized water preheated to 85° C. without adjusting the pH was added to the three-necked flask, and the three-necked flask was sealed, and the stirring was continued for 24 hours, and then the stirring and the insulation were stopped. The liquid in the three-necked flask was a milky white liquid, and it was left to stand until the temperature dropped to room temperature; at this time, the upper layer in the three-necked flask was a white waxy solid octadecyl alcohol, and the lower layer was a milky white silica hydrosol. The solid octadecyl alcohol and the silica hydrosol were separated, and the solid octadecyl alcohol was recovered and dried; the pH of the silica hydrosol was measured, and its z-average particle size and PDI (dispersity index) were measured using a dynamic light scattering nanoparticle size analyzer, and the results are listed in Table 2; and the particles of the silica hydrosol were observed using a scanning electron microscope, and it was found that its morphology was a network of particles with a diameter of about 20 nanometers, which was similar to the morphology prepared by the gas phase method (reference Figure 2 ).

[0071] Example 2

[0072] The reaction apparatus, method and steps are the same as those in Example 1, except that 400 g of octadecyl alcohol is added to the three-necked flask, the three-necked flask is placed in a water bath with magnetic stirring, heated and kept at 85° C., and the magnetic stirring is turned on after the octadecyl alcohol is completely melted;

[0073] Add 40g of silicon tetrachloride to the washing bottle B, completely seal the three-necked flask, turn on the air pump to pass air into the washing bottle B, the air from the washing bottle B carries the silicon tetrachloride gas into the bottom of the three-necked flask and reacts with the molten octadecyl alcohol under stirring to generate silicate and hydrogen chloride, the reaction product hydrogen chloride gas is blown out of the three-necked flask by the air into the washing bottle A to react with water and collect, the liquid in the three-necked flask is milky white liquid;

[0074] After 27.5 hours, the air pump was turned off, the connection between the washing bottle A and the washing bottle B and the three-necked flask was disconnected, and 300 grams of deionized water preheated to 85° C. was added to the three-necked flask and then the three-necked flask was sealed. The deionized water was adjusted to pH 13 using tetramethylammonium hydroxide in advance, and the mixture was kept warm and stirred for 24.5 hours, and then the stirring and insulation were stopped. The liquid in the three-necked flask was a milky white liquid and was left to stand until the temperature dropped to room temperature; at this time, the upper layer in the three-necked flask was a white waxy solid octadecyl alcohol, and the lower layer was a milky white silica hydrosol, and the solid octadecyl alcohol and the silica hydrosol were separated, and the solid octadecyl alcohol was recovered and dried; the pH of the silica hydrosol was measured, and its z-average particle size and PDI (dispersity index) were measured using a dynamic light scattering nanoparticle size analyzer, and the results are listed in Table II.

[0075] Example 3

[0076] The reaction apparatus, method and steps are the same as those in Example 1, except that 400 g of octadecyl alcohol is added to the three-necked flask, the three-necked flask is placed in a water bath with magnetic stirring, heated and kept at 85° C., after the octadecyl alcohol is completely melted, the magnetic stirring is turned on, and then 40 g of silicon tetrachloride is added to the three-necked flask, the three-necked flask is immediately and completely sealed, and the reaction is stirred for 10 minutes;

[0077] Turn on the air pump to introduce air into the washing bottle B. The air enters the bottom of the three-necked flask from the washing bottle B. The reaction product, hydrogen chloride gas, is blown out of the three-necked flask by the air and enters the washing bottle A to react with water and collect. The liquid in the three-necked flask is milky white liquid.

[0078] After 18.5 hours, the air pump was turned off, the connection between the washing bottle A and the washing bottle B and the three-necked flask was disconnected, and 300 grams of deionized water preheated to 85° C. was added to the three-necked flask and then the three-necked flask was sealed. The deionized water was adjusted to pH 13 using tetramethylammonium hydroxide in advance, and the mixture was kept warm and stirred for 96 hours. Then the stirring and insulation were stopped. The liquid in the three-necked flask was a milky white liquid and was allowed to stand until the temperature dropped to room temperature. At this time, the upper layer in the three-necked flask was a white waxy solid octadecyl alcohol, and the lower layer was a milky white silica hydrosol. The solid octadecyl alcohol and the silica hydrosol were separated, and the solid octadecyl alcohol was recovered and dried. The pH of the silica hydrosol was measured, and its z-average particle size and PDI (dispersity index) were measured using a dynamic light scattering nanoparticle size analyzer. The results are listed in Table II.

[0079] Example 4

[0080] The reaction apparatus, method and steps are the same as those in Example 1, except that 400 g of octadecyl alcohol is added to the three-necked flask, the three-necked flask is placed in a water bath with magnetic stirring, heated and kept at 85° C., and the magnetic stirring is turned on after the octadecyl alcohol is completely melted;

[0081] Add 40g of silicon tetrachloride to the washing bottle B, completely seal the three-necked flask, turn on the air pump to pass air into the washing bottle B, the air from the washing bottle B carries the silicon tetrachloride gas into the bottom of the three-necked flask and reacts with the molten octadecyl alcohol under stirring to generate silicate and hydrogen chloride, the reaction product hydrogen chloride gas is blown out of the three-necked flask by the air into the washing bottle A to react with water and collect, the liquid in the three-necked flask is milky white liquid;

[0082] After 44 hours, the air pump was turned off, the connection between the washing bottle A and the washing bottle B and the three-necked flask was disconnected, 300 grams of deionized water preheated to 85° C. was added to the three-necked flask and then the three-necked flask was sealed. The deionized water was adjusted to pH 12 using tetramethylguanidine in advance, and the mixture was kept warm and stirred for 25 hours. Then the stirring and the insulation were stopped. The liquid in the three-necked flask was a milky white liquid and was allowed to stand until the temperature dropped to room temperature. At this time, the upper layer in the three-necked flask was a white waxy solid octadecyl alcohol, and the lower layer was a milky white silica hydrosol. The solid octadecyl alcohol and the silica hydrosol were separated, and the solid octadecyl alcohol was recovered and dried. The pH of the silica hydrosol was measured, and its z-average particle size and PDI (dispersity index) were measured using a dynamic light scattering nanoparticle size analyzer. The results are listed in Table 2.

[0083] Example 5

[0084] The reaction apparatus, method and steps are the same as those in Example 1, except that 400 g of octadecyl alcohol is added to the three-necked flask, the three-necked flask is placed in a water bath with magnetic stirring, heated and kept at 85° C., and the magnetic stirring is turned on after the octadecyl alcohol is completely melted;

[0085] Add 40g of silicon tetrachloride to the washing bottle B, completely seal the three-necked flask, turn on the air pump to pass air into the washing bottle B, the air from the washing bottle B carries the silicon tetrachloride gas into the bottom of the three-necked flask and reacts with the molten octadecyl alcohol under stirring to generate silicate and hydrogen chloride, the reaction product hydrogen chloride gas is blown out of the three-necked flask by the air into the washing bottle A to react with water and collect, the liquid in the three-necked flask is milky white liquid;

[0086] After 45 hours, the air pump was turned off, the connection between the washing bottle A, the washing bottle B and the three-necked flask was disconnected, 300 grams of deionized water preheated to 85° C. was added to the three-necked flask and then the three-necked flask was sealed. The deionized water was adjusted to pH 10 using arginine in advance, and the mixture was kept warm and stirred for 25 hours. Then the stirring and the insulation were stopped. The liquid in the three-necked flask was a milky white liquid and was allowed to stand until the temperature dropped to room temperature. At this time, the upper layer in the three-necked flask was a white waxy solid octadecyl alcohol, and the lower layer was a milky white silica hydrosol. The solid octadecyl alcohol and the silica hydrosol were separated, and the solid octadecyl alcohol was recovered and dried. The pH of the silica hydrosol was measured, and its z-average particle size and PDI (dispersity index) were measured using a dynamic light scattering nanoparticle size analyzer. The results are listed in Table 2.

[0087] Example 6

[0088] The reaction apparatus, method and steps are the same as those in Example 1, except that 400 g of octadecyl alcohol is added to the three-necked flask, the three-necked flask is placed in a water bath with magnetic stirring, heated and kept at 85° C., and the magnetic stirring is turned on after the octadecyl alcohol is completely melted;

[0089] Add 40g of silicon tetrachloride to the washing bottle B, completely seal the three-necked flask, turn on the air pump to pass air into the washing bottle B, the air from the washing bottle B carries the silicon tetrachloride gas into the bottom of the three-necked flask and reacts with the molten octadecyl alcohol under stirring to generate silicate and hydrogen chloride, the reaction product hydrogen chloride gas is blown out of the three-necked flask by the air into the washing bottle A to react with water and collect, the liquid in the three-necked flask is milky white liquid;

[0090] After 44 hours, the air pump was turned off, the connection between the washing bottle A and the washing bottle B and the three-necked flask was disconnected, 300 grams of deionized water preheated to 85° C. was added to the three-necked flask and then the three-necked flask was sealed. The deionized water was adjusted to pH 8 using triethanolamine in advance, and the mixture was kept warm and stirred for 44 hours. Then the stirring and the insulation were stopped. The liquid in the three-necked flask was a milky white liquid and was allowed to stand until the temperature dropped to room temperature. At this time, the upper layer in the three-necked flask was a white waxy solid octadecyl alcohol, and the lower layer was a milky white silica hydrosol. The solid octadecyl alcohol and the silica hydrosol were separated, and the solid octadecyl alcohol was recovered and dried. The pH of the silica hydrosol was measured, and its z-average particle size and PDI (dispersity index) were measured using a dynamic light scattering nanoparticle size analyzer. The results are listed in Table 2.

[0091] Example 7

[0092] The reaction apparatus, method and steps are the same as those in Example 1, except that 400 g of hexadecanol is added to the three-necked flask, the three-necked flask is placed in a water bath with magnetic stirring, heated and kept at 85° C., and the magnetic stirring is turned on after the hexadecanol is completely melted;

[0093] 41 g of silicon tetrachloride was added to the washing bottle B, and the three-necked flask was completely sealed. The air pump was turned on to introduce air into the washing bottle B. The air from the washing bottle B carried the silicon tetrachloride gas into the bottom of the three-necked flask and reacted with the molten hexadecanol under stirring to generate silicate and hydrogen chloride. The reaction product hydrogen chloride gas was blown out of the three-necked flask by the air and entered the washing bottle A to react with water and be collected. The liquid in the three-necked flask was milky white liquid.

[0094] After 3 hours, the air pump was turned off, the connection between the washing bottle A, the washing bottle B and the three-necked flask was disconnected, 300 grams of deionized water preheated to 85°C without adjusting the pH was added to the three-necked flask, and the three-necked flask was sealed, and the stirring was continued for 24 hours, and then the stirring and the insulation were stopped. The liquid in the three-necked flask was a milky white liquid, and was allowed to stand until the temperature dropped to room temperature; at this time, the upper layer in the three-necked flask was white waxy solid hexadecanol, and the lower layer was a milky white silica hydrosol, the solid hexadecanol and the silica hydrosol were separated, the solid hexadecanol was recovered and dried; the pH of the silica hydrosol was measured, and its z-average particle size and PDI (dispersity index) were measured using a dynamic light scattering nanoparticle size analyzer, and the results are listed in Table 2.

[0095] Example 8

[0096] The reaction apparatus, method and steps are the same as those in Example 1, except that 400 g of tetradecanol is added to the three-necked flask, the three-necked flask is placed in a water bath with magnetic stirring, heated and kept at 85° C., and after the tetradecanol is completely melted, the magnetic stirring is turned on;

[0097] Add 40g of silicon tetrachloride into the washing bottle B, completely seal the three-necked flask, turn on the air pump to pass air into the washing bottle B, the air from the washing bottle B carries the silicon tetrachloride gas into the bottom of the three-necked flask and reacts with the molten tetradecanol under stirring to generate silicate and hydrogen chloride, the reaction product hydrogen chloride gas is blown out of the three-necked flask by the air into the washing bottle A to react with water and collect, the liquid in the three-necked flask is milky white liquid;

[0098] After 25 hours, the air pump was turned off, the connection between the washing bottle A, the washing bottle B and the three-necked flask was disconnected, 300 grams of deionized water preheated to 85°C without adjusting the pH was added to the three-necked flask, and the three-necked flask was sealed, and the stirring was continued for 24 hours, and then the stirring and the insulation were stopped. The liquid in the three-necked flask was a milky white liquid, and was allowed to stand until the temperature dropped to room temperature; at this time, the upper layer in the three-necked flask was a white waxy solid tetradecanol, and the lower layer was a milky white silica hydrosol, the solid tetradecanol and the silica hydrosol were separated, the solid tetradecanol was recovered and dried; the pH of the silica hydrosol was measured, and its z-average particle size and PDI (dispersity index) were measured using a dynamic light scattering nanoparticle size analyzer, and the results are listed in Table 2.

[0099] Example 9

[0100] The reaction apparatus, method and steps are the same as those in Example 1, except that 400 g of dodecanol is added to the three-necked flask, the three-necked flask is placed in a water bath with magnetic stirring, heated and kept at 45° C., and the magnetic stirring is turned on after the dodecanol is completely melted;

[0101] Add 40g of silicon tetrachloride into the washing bottle B, completely seal the three-necked flask, turn on the air pump to pass air into the washing bottle B, the air from the washing bottle B carries the silicon tetrachloride gas into the bottom of the three-necked flask and reacts with the molten dodecanol under stirring to generate silicate and hydrogen chloride, the reaction product hydrogen chloride gas is blown out of the three-necked flask by the air into the washing bottle A to react with water and collect, the liquid in the three-necked flask is milky white liquid;

[0102] After 25 hours, the air pump was turned off, the connection between the washing bottle A and the washing bottle B and the three-necked flask was disconnected, and 300 grams of deionized water preheated to 45°C without adjusting the pH was added to the three-necked flask, and the three-necked flask was sealed, and the stirring was continued for 24.5 hours, and then the stirring and the insulation were stopped. The liquid in the three-necked flask was a milky liquid, and the three-necked flask was placed in a refrigerator and cooled to 4°C. At this time, the upper layer in the three-necked flask was a white waxy solid dodecanol, and the lower layer was a milky white silica hydrosol. The solid dodecanol and the silica hydrosol were separated, and the solid dodecanol was recovered and dried; the pH of the silica hydrosol was measured, and its z-average particle size and PDI (dispersity index) were measured with a dynamic light scattering nanoparticle size analyzer, and the results are listed in Table II.

[0103] Example 10

[0104] The reaction apparatus, method and steps are the same as those in Example 1, except that 400 g of docosanol is added to the three-necked flask, the three-necked flask is placed in a water bath with magnetic stirring, heated and kept at 85° C., and after the docosanol is completely melted, the magnetic stirring is turned on;

[0105] 41 g of silicon tetrachloride was added to the washing bottle B, and the three-necked flask was completely sealed. The air pump was turned on to introduce air into the washing bottle B. The air from the washing bottle B carried the silicon tetrachloride gas into the bottom of the three-necked flask and reacted with the molten dodecyl alcohol under stirring to generate silicate and hydrogen chloride. The reaction product hydrogen chloride gas was blown out of the three-necked flask by the air and entered the washing bottle A to react with water and be collected. The liquid in the three-necked flask was milky white liquid.

[0106] After 3 hours, the air pump was turned off, the connection between the washing bottle A, the washing bottle B and the three-necked flask was disconnected, 300 grams of deionized water preheated to 85° C. without adjusting the pH was added to the three-necked flask, and the three-necked flask was sealed, and the stirring was continued for 24 hours, and then the stirring and the insulation were stopped. The liquid in the three-necked flask was milky white liquid, and it was allowed to stand until the temperature dropped to room temperature; at this time, the upper layer in the three-necked flask was white waxy solid docosanol, and the lower layer was milky white silica hydrosol, the solid docosanol and the silica hydrosol were separated, and the solid docosanol was recovered and dried; the pH of the silica hydrosol was measured, and its z-average particle size and PDI (dispersity index) were measured using a dynamic light scattering nanoparticle size analyzer, and the results are listed in Table 2.

[0107] Embodiment 11

[0108] The reaction apparatus, method and steps are the same as those in Example 1, except that 100 g of cyclododecanol is added to the three-necked flask, the three-necked flask is placed in a water bath with magnetic stirring, heated and kept at 85° C., and the magnetic stirring is turned on after the cyclododecanol is completely melted;

[0109] Add 10 grams of silicon tetrachloride to the washing bottle B, completely seal the three-necked flask, turn on the air pump to pass air into the washing bottle B, the air from the washing bottle B carries the silicon tetrachloride gas into the bottom of the three-necked flask and reacts with the molten cyclododecanol under stirring to generate silicate and hydrogen chloride, the reaction product hydrogen chloride gas is blown out of the three-necked flask by the air into the washing bottle A to react with water and collect, the liquid in the three-necked flask is milky white liquid;

[0110] After 29 hours, the air pump was turned off, the connection between the washing bottle A and the washing bottle B and the three-necked flask was disconnected, and 75 grams of deionized water preheated to 85° C. was added to the three-necked flask and then the three-necked flask was sealed. The deionized water was adjusted to pH 12 using tetramethylammonium hydroxide in advance, and the mixture was kept warm and stirred for 38 hours. Then the stirring and the insulation were stopped. The liquid in the three-necked flask was a milky white liquid and was allowed to stand until the temperature dropped to room temperature. At this time, the upper layer in the three-necked flask was a white waxy solid cyclododecanol, and the lower layer was a milky white silica hydrosol. The solid cyclododecanol and the silica hydrosol were separated, and the solid cyclododecanol was recovered and dried. The pH of the silica hydrosol was measured, and its z-average particle size and PDI (dispersity index) were measured using a dynamic light scattering nanoparticle size analyzer. The results are listed in Table 2.

[0111] Example 12

[0112] The reaction device, method and steps are the same as those in Example 1, except that 400 g of menthol is added to the three-necked flask, the three-necked flask is placed in a water bath with magnetic stirring, heated and kept at 85° C., and the magnetic stirring is turned on after the menthol is completely melted;

[0113] Add 40g of silicon tetrachloride into the washing bottle B, completely seal the three-necked flask, turn on the air pump to introduce air into the washing bottle B, the air from the washing bottle B carries the silicon tetrachloride gas into the bottom of the three-necked flask and reacts with the molten menthol under stirring to generate silicate and hydrogen chloride, the reaction product hydrogen chloride gas is blown out of the three-necked flask by the air into the washing bottle A to react with water and be collected;

[0114] After 30 hours, the air pump was turned off, the connection between the washing bottle A and the washing bottle B and the three-necked flask was disconnected, the liquid in the three-necked flask was cooled to 65°C and maintained at this temperature, 300 grams of deionized water preheated to 65°C was added to the three-necked flask and then the three-necked flask was sealed, the deionized water was adjusted to pH 12 with ammonia water in advance, and the mixture was kept warm and stirred for 16 hours, and then the liquid in the three-necked flask was cooled to 45°C and continued to be kept warm and stirred for 56 hours, and then the stirring and insulation were stopped. The liquid in the three-necked flask was a light yellow emulsion and was left to stand until the temperature dropped to room temperature; at this time, the upper layer in the three-necked flask was waxy solid menthol, and the lower layer was light yellow silica hydrosol, the solid menthol and the silica hydrosol were separated, the solid menthol was recovered and dried; the pH of the silica hydrosol was measured, and its z-average particle size and PDI (dispersity index) were measured using a dynamic light scattering nanoparticle size analyzer, and the results are listed in Table 2.

[0115] Example 13

[0116] The reaction apparatus, method and steps are the same as those in Example 1, except that 100 g of aniseed alcohol is added to the three-necked flask, the three-necked flask is placed in a water bath with magnetic stirring, heated and kept at 75° C., and the magnetic stirring is turned on after the aniseed alcohol is completely melted;

[0117] Add 10 grams of silicon tetrachloride to the washing bottle B, completely seal the three-necked flask, turn on the air pump to pass air into the washing bottle B, the air from the washing bottle B carries the silicon tetrachloride gas into the bottom of the three-necked flask and reacts with the molten anise alcohol under stirring to form silicate and hydrogen chloride, the reaction product hydrogen chloride gas is blown out of the three-necked flask by the air into the washing bottle A to react with water and collect;

[0118] After 47 hours, the air pump was turned off, the connection between the washing bottle A, the washing bottle B and the three-necked flask was disconnected, 75 grams of deionized water preheated to 75° C. was added to the three-necked flask and then the three-necked flask was sealed. The deionized water was adjusted to pH 12 using tetramethylammonium hydroxide in advance, and the mixture was kept warm and stirred for 24 hours. Then the stirring and the heat preservation were stopped, and the three-necked flask was placed in a refrigerator and cooled to 4° C.; at this time, the upper layer in the three-necked flask was yellow paste solid anise alcohol, and the lower layer was milky white silica hydrosol. The solid anise alcohol and the silica hydrosol were separated, and the solid anise alcohol was recovered and dried; the pH of the silica hydrosol was measured, and its z-average particle size and PDI (dispersity index) were measured using a dynamic light scattering nanoparticle size analyzer, and the results are listed in Table 2.

[0119] Embodiment 14

[0120] The reaction apparatus, method and steps are the same as those in Example 1, except that 400 g of 4-tert-butyl cyclohexanol is added to the three-necked flask, the three-necked flask is placed in a water bath with magnetic stirring, heated and kept at 75° C., and after the 4-tert-butyl cyclohexanol is completely melted, the magnetic stirring is turned on;

[0121] Add 40g of silicon tetrachloride into the washing bottle B, completely seal the three-necked flask, turn on the air pump to introduce air into the washing bottle B, the air from the washing bottle B carries the silicon tetrachloride gas into the bottom of the three-necked flask and reacts with the molten 4-tert-butyl cyclohexanol under stirring to generate silicate and hydrogen chloride, the reaction product hydrogen chloride gas is blown out of the three-necked flask by the air into the washing bottle A to react with water and be collected;

[0122] After 45 hours, the air pump was turned off, the connection between the washing bottle A, the washing bottle B and the three-necked flask was disconnected, 300 grams of deionized water preheated to 75° C. was added to the three-necked flask and then the three-necked flask was sealed. The deionized water was adjusted to pH 12 using tetramethylammonium hydroxide in advance, and the mixture was kept warm and stirred for 25 hours, then the stirring and the insulation were stopped, and the mixture was allowed to stand until the temperature dropped to room temperature; at this time, the upper layer in the three-necked flask was solid 4-tert-butyl cyclohexanol, and the lower layer was light yellow silica hydrosol, the solid 4-tert-butyl cyclohexanol and the silica hydrosol were separated, the solid 4-tert-butyl cyclohexanol was recovered and dried; the pH of the silica hydrosol was measured, and its z-average particle size and PDI (dispersity index) were measured using a dynamic light scattering nanoparticle size analyzer, and the results are listed in Table 2.

[0123] Comparative Example

[0124] Comparative Example 1

[0125] The reaction apparatus, method and steps are the same as those in Example 1, except that 400 g of n-decanol is added to the three-necked flask, the three-necked flask is placed in a water bath with magnetic stirring, heated and kept at 45° C., and the magnetic stirring is turned on;

[0126] Add 40g of silicon tetrachloride to the washing bottle B, completely seal the three-necked flask, turn on the air pump to introduce air into the washing bottle B, the air from the washing bottle B carries the silicon tetrachloride gas into the bottom of the three-necked flask and reacts with the liquid n-decanol under stirring to generate silicate and hydrogen chloride, the reaction product hydrogen chloride gas is blown out of the three-necked flask by the air into the washing bottle A to react with water and be collected;

[0127] After 24 hours, the air pump was turned off, the connection between the washing bottle A, the washing bottle B and the three-necked flask was disconnected, 300 grams of deionized water preheated to 45°C without adjusting the pH was added to the three-necked flask, and the three-necked flask was sealed. The stirring was continued for 25 hours, and then the stirring and the heat preservation were stopped. The three-necked flask was placed in a refrigerator to cool and stand to 4°C; at this time, the liquid in the three-necked flask was a viscous emulsion with no stratification, and the aqueous silica sol could not be separated.

[0128] Comparative Example 2

[0129] The reaction apparatus, method and steps are the same as those in Example 1, except that 400 g of isooctyl alcohol is added to the three-necked flask, the three-necked flask is placed in a water bath with magnetic stirring, heated and kept at 45° C., and the magnetic stirring is turned on;

[0130] Add 40g of silicon tetrachloride to the washing bottle B, completely seal the three-necked flask, turn on the air pump to pass air into the washing bottle B, the air from the washing bottle B carries the silicon tetrachloride gas into the bottom of the three-necked flask and reacts with the liquid isooctyl alcohol under stirring to generate silicate and hydrogen chloride, the reaction product hydrogen chloride gas is blown out of the three-necked flask by the air into the washing bottle A to react with water and be collected;

[0131] After 24 hours, the air pump was turned off, the connection between the washing bottle A, the washing bottle B and the three-necked flask was disconnected, 300 grams of deionized water preheated to 45°C without adjusting the pH was added to the three-necked flask, and the three-necked flask was sealed. The stirring was continued for 25 hours, and then the stirring and the heat preservation were stopped. The three-necked flask was placed in a refrigerator to cool and stand to 4°C; at this time, the liquid in the three-necked flask was an emulsion with no stratification, and the aqueous silica sol could not be separated.

[0132] Comparative Example 3

[0133] The reaction apparatus, method and steps are the same as those in Example 1, except that 400 g of cinnamyl alcohol is added to a three-necked flask, the three-necked flask is placed in a water bath with magnetic stirring, heated and kept at 85° C., and after the cinnamyl alcohol is completely melted, the magnetic stirring is turned on;

[0134] Add 40g of silicon tetrachloride into the washing bottle B, completely seal the three-necked flask, turn on the air pump to introduce air into the washing bottle B, the air from the washing bottle B carries the silicon tetrachloride gas into the bottom of the three-necked flask and reacts with the molten cinnamyl alcohol under stirring to generate silicate and hydrogen chloride, the reaction product hydrogen chloride gas is blown out of the three-necked flask by the air into the washing bottle A to react with water and be collected;

[0135] After 29.5 hours, the air pump was turned off, the connection between the washing bottle A, the washing bottle B and the three-necked flask was disconnected, 300 grams of deionized water preheated to 85° C. was added to the three-necked flask and the three-necked flask was sealed. The deionized water was adjusted to pH 12 using tetramethylammonium hydroxide in advance, and the stirring was continued for 102 hours. Then the stirring and the insulation were stopped, and the flask was allowed to stand and cool to room temperature. At this time, the liquid in the three-necked flask was a high-viscosity yellow paste with no stratification, and the aqueous silica sol could not be separated.

[0136] Comparative Example 4

[0137] The reaction apparatus, method and steps are the same as those in Example 1, except that 400 g of citronellol is added to the three-necked flask, the three-necked flask is placed in a water bath with magnetic stirring, heated and kept at 85° C., and the magnetic stirring is turned on;

[0138] Add 40 grams of silicon tetrachloride to the washing bottle B, completely seal the three-necked flask, turn on the air pump to pass air into the washing bottle B, the air from the washing bottle B carries the silicon tetrachloride gas into the bottom of the three-necked flask and reacts with the liquid citronellol under stirring to generate silicate and hydrogen chloride, the reaction product hydrogen chloride gas is blown out of the three-necked flask by the air into the washing bottle A to react with water and collect;

[0139] After 27 hours, the air pump was turned off, the connection between the washing bottle A, the washing bottle B and the three-necked flask was disconnected, 300 grams of deionized water preheated to 85°C was added to the three-necked flask and then the three-necked flask was sealed. The deionized water was pre-adjusted to pH 12 using tetramethylammonium hydroxide. The flask was kept warm and stirred for 62 hours. The reactant liquid turned dark brown, and then the stirring and insulation were stopped. The flask was allowed to stand and cool to room temperature without solid-liquid stratification. The three-necked flask was then placed in a refrigerator to cool and stand to 4°C to obtain an upper layer of black liquid, a middle layer of slightly transparent liquid and a lower layer of yellow solid-liquid mixture. The aqueous silica sol could not be effectively separated.

[0140] Comparative Example 5

[0141] The reaction device, method and steps are the same as those in Example 1, except that 400 g of α-terpineol is added to the three-necked flask, the three-necked flask is placed in a water bath with magnetic stirring, heated and kept at 65° C., and after the α-terpineol is completely melted, the magnetic stirring is turned on;

[0142] Add 40g of silicon tetrachloride to the washing bottle B, completely seal the three-necked flask, turn on the air pump to pass air into the washing bottle B, the air from the washing bottle B carries the silicon tetrachloride gas into the bottom of the three-necked flask and reacts with the molten α-pinene alcohol under stirring to generate silicate and hydrogen chloride, the reaction product hydrogen chloride gas is blown out of the three-necked flask by the air into the washing bottle A to react with water and collect, the solution quickly turns black during the reaction;

[0143] After 24.5 hours, the air pump was turned off, the connection between the washing bottle A, the washing bottle B and the three-necked flask was disconnected, 300 grams of deionized water preheated to 65° C. was added to the three-necked flask and the three-necked flask was sealed. The deionized water was adjusted to pH 12 using tetramethylammonium hydroxide in advance, and the stirring was continued for 106 hours. Then the stirring and the insulation were stopped, and the flask was allowed to stand and cool to room temperature. At this time, the liquid in the three-necked flask was a dark brown viscous liquid with no stratification, and the aqueous silica sol could not be separated.

[0144] Comparative Example 6

[0145] The reaction apparatus, method and steps are the same as those in Example 1, except that 400 g of phenylethanol is added to the three-necked flask, the three-necked flask is placed in a water bath with magnetic stirring, heated and kept at 60° C., and the magnetic stirring is turned on;

[0146] Add 40g of silicon tetrachloride into the washing bottle B, completely seal the three-necked flask, turn on the air pump to let air into the washing bottle B, the air from the washing bottle B carries the silicon tetrachloride gas into the bottom of the three-necked flask and reacts with the liquid phenylethanol under stirring to generate silicate and hydrogen chloride, the reaction product hydrogen chloride gas is blown out of the three-necked flask by the air into the washing bottle A to react with water and be collected;

[0147] After 29 hours, the air pump was turned off, the connection between the washing bottle A, the washing bottle B and the three-necked flask was disconnected, 300 grams of deionized water preheated to 60°C was added to the three-necked flask and the three-necked flask was sealed. The deionized water was adjusted to pH 12 using tetramethylammonium hydroxide in advance. The liquid turned light yellow during the reaction, and the stirring was continued for 34 hours. Then the stirring and the insulation were stopped, and the mixture was allowed to stand and cool to room temperature. At this time, the upper layer of the liquid in the three-necked flask was a yellow oily liquid, the middle layer was a white liquid, and the lower layer was a white solid. The aqueous silica sol could not be effectively separated after cooling to 4°C.

[0148] Comparative Example 7

[0149] The reaction apparatus, method and steps are the same as those in Example 1, except that 400 g of p-methoxybenzyl alcohol is added to the three-necked flask, the three-necked flask is placed in a water bath with magnetic stirring, heated and kept at 85° C., and after the p-methoxybenzyl alcohol is completely melted, the magnetic stirring is turned on;

[0150] Add 40 grams of silicon tetrachloride to the washing bottle B, completely seal the three-necked flask, turn on the air pump to pass air into the washing bottle B, the air from the washing bottle B carries the silicon tetrachloride gas into the bottom of the three-necked flask and reacts with the molten p-methoxybenzyl alcohol under stirring to generate silicate and hydrogen chloride, the reaction product hydrogen chloride gas is blown out of the three-necked flask by the air into the washing bottle A to react with water and collect;

[0151] After 24.5 hours, the air pump was turned off, the connection between the washing bottle A, the washing bottle B and the three-necked flask was disconnected, 300 grams of deionized water preheated to 85° C. was added to the three-necked flask and the three-necked flask was sealed. The deionized water was adjusted to pH 12 using tetramethylammonium hydroxide in advance, and the mixture was kept warm and stirred for 25 hours. Then, the stirring and the heat preservation were stopped, and the mixture was allowed to stand and cool to room temperature. At this time, the upper layer of the liquid in the three-necked flask was a yellow liquid, and the lower layer was a light yellow viscous paste. The aqueous silica sol could not be separated even after the temperature was lowered to 4° C.

[0152] Comparative Example 8

[0153] The reaction apparatus, method and steps are the same as those in Example 1, except that 100 g of dihydromyrcenol is added to the three-necked flask, the three-necked flask is placed in a water bath with magnetic stirring, heated and kept at 85° C., and the magnetic stirring is turned on;

[0154] 10 g of silicon tetrachloride was added to the washing bottle B, and the three-necked flask was completely sealed. The air pump was turned on to introduce air into the washing bottle B. The air from the washing bottle B carried silicon tetrachloride gas into the bottom of the three-necked flask and reacted with liquid dihydromyrcenol under stirring to generate silicate and hydrogen chloride. After the silicon tetrachloride was introduced for several minutes, the liquid in the three-necked flask changed from colorless and transparent to brown-red, and crystallization occurred. The reaction product hydrogen chloride gas was blown out of the three-necked flask by the air and entered the washing bottle A to react with water and be collected;

[0155] After 24 hours, the air pump was turned off, and the connection between the washing bottles A and B and the three-necked flask was disconnected. The liquid in the three-necked flask turned into gray powder. 75 grams of deionized water preheated to 85°C without adjusting the pH was added to the three-necked flask, and the three-necked flask was sealed. The stirring was continued for 24 hours, and then the stirring and the heating were stopped, and the flask was allowed to stand and cool to room temperature. At this time, the liquid in the three-necked flask was a brown turbid liquid, and the aqueous silica sol could not be separated even after the temperature was lowered to 4°C.

[0156] Comparative Example 9

[0157] The reaction apparatus, method and steps are the same as those in Example 1, except that 100 g of neopentyl glycol mono(hydroxypivalate) is added to a three-necked flask, the three-necked flask is placed in a water bath with magnetic stirring, heated and kept at 85° C., and after the neopentyl glycol mono(hydroxypivalate) is completely melted, magnetic stirring is turned on;

[0158] Add 10 grams of silicon tetrachloride to the washing bottle B, completely seal the three-necked flask, turn on the air pump to pass air into the washing bottle B, the air from the washing bottle B carries the silicon tetrachloride gas into the bottom of the three-necked flask and reacts with the molten neopentyl glycol mono(hydroxypivalate) under stirring to generate silicate and hydrogen chloride, the reaction product hydrogen chloride gas is blown out of the three-necked flask by the air into the washing bottle A to react with water and be collected;

[0159] After 24 hours, the air pump was turned off, the connection between the washing bottle A, the washing bottle B and the three-necked flask was disconnected, 75 grams of deionized water preheated to 85°C without adjusting the pH was added to the three-necked flask, and the three-necked flask was sealed, and the stirring was continued for 26 hours. Then the stirring and the heating were stopped, and the flask was allowed to stand and cool to room temperature. At this time, the liquid in the three-necked flask was a transparent solution with a small amount of white solid precipitation at the bottom, and the aqueous silica sol could not be separated.

[0160] Comparative Example 10

[0161] The reaction apparatus, method and steps are the same as those in Example 1, except that 100 g of 1-naphthylethanol is added to the three-necked flask, the three-necked flask is placed in a water bath with magnetic stirring, heated and kept warm at 85° C., and after the 1-naphthylethanol is completely melted, the magnetic stirring is turned on;

[0162] Add 10 grams of silicon tetrachloride to the washing bottle B, completely seal the three-necked flask, turn on the air pump to pass air into the washing bottle B, the air from the washing bottle B carries the silicon tetrachloride gas into the bottom of the three-necked flask and reacts with the molten 1-naphthylethanol under stirring to generate silicate and hydrogen chloride, the reaction product hydrogen chloride gas is blown out of the three-necked flask by the air into the washing bottle A to react with water and collect;

[0163] After 29 hours, the air pump was turned off, the connection between the washing bottle A, the washing bottle B and the three-necked flask was disconnected, 75 grams of deionized water preheated to 85°C was added to the three-necked flask and the three-necked flask was sealed. The deionized water was adjusted to pH 12 with tetramethylammonium hydroxide in advance, and the stirring was continued for 48 hours. Then the stirring and the insulation were stopped, and the flask was allowed to stand and cool to room temperature. At this time, the upper layer of the liquid in the three-necked flask was a brown viscous liquid, and the lower layer was a very small amount of milky white liquid. The aqueous silica sol could not be effectively separated after cooling to 4°C.

[0164] Comparative Example 11

[0165] The reaction apparatus, method and steps are the same as those in Example 1, except that 100 g of 1,2-octanediol is added to the three-necked flask, the three-necked flask is placed in a water bath with magnetic stirring, heated and kept at 85° C., and after the 1,2-octanediol is completely melted, the magnetic stirring is turned on;

[0166] Add 10 grams of silicon tetrachloride to the washing bottle B, completely seal the three-necked flask, turn on the air pump to pass air into the washing bottle B, the air from the washing bottle B carries the silicon tetrachloride gas into the bottom of the three-necked flask and reacts with the molten 1,2-octanediol under stirring to generate silicate and hydrogen chloride, the reaction product hydrogen chloride gas is blown out of the three-necked flask by the air into the washing bottle A to react with water and be collected;

[0167] After 24 hours, the air pump was turned off, the connection between the washing bottle A, the washing bottle B and the three-necked flask was disconnected, 75 grams of deionized water preheated to 85° C. was added to the three-necked flask and the three-necked flask was sealed. The deionized water was adjusted to pH 12 using tetramethylammonium hydroxide in advance, and the stirring was continued for 25 hours. Then the stirring and the insulation were stopped, and the three-necked flask was placed in a refrigerator and allowed to stand and cool to 4° C. At this time, the liquid in the three-necked flask was a transparent high-viscosity liquid without stratification, and the aqueous silica sol could not be separated.

[0168] Comparative Example 12

[0169] The reaction apparatus, method and steps are the same as those in Example 1, except that 400 g of 1,12-dodecanediol is added to the three-necked flask, the three-necked flask is placed in a water bath with magnetic stirring, heated and kept at 85° C., and after the 1,12-dodecanediol is completely melted, the magnetic stirring is turned on;

[0170] Add 40 grams of silicon tetrachloride to the washing bottle B, completely seal the three-necked flask, turn on the air pump to introduce air into the washing bottle B, and the air from the washing bottle B carries the silicon tetrachloride gas into the bottom of the three-necked flask to react with the molten 1,12-dodecanediol. A white solid product is immediately generated in the three-necked flask and covers the liquid reactant, causing the reaction to fail to proceed smoothly and stop the reaction.

[0171] Comparative Example 13

[0172] The reaction apparatus, method and steps are the same as those in Example 1, except that 400 g of 1,10-decanediol is added to the three-necked flask, the three-necked flask is placed in a water bath with magnetic stirring, heated and kept at 85° C., and after the 1,10-decanediol is completely melted, the magnetic stirring is turned on;

[0173] Add 40 grams of silicon tetrachloride to the washing bottle B, completely seal the three-necked flask, turn on the air pump to introduce air into the washing bottle B, and the air from the washing bottle B carries the silicon tetrachloride gas into the bottom of the three-necked flask to react with the molten 1,10-decanediol. A white solid product is immediately generated in the three-necked flask and covers the liquid reactant, causing the reaction to fail to proceed smoothly and stop the reaction.

[0174] Comparative Example 14

[0175] The reaction apparatus, method and steps are the same as those in Example 1, except that 400 g of octadecanol is added to the three-necked flask, and the octadecanol is not heated to melt;

[0176] Add 40 grams of silicon tetrachloride to washing bottle B, completely seal the three-necked flask, turn on the air pump to introduce air into washing bottle B, and the air carrying silicon tetrachloride gas from washing bottle B enters the bottom of the three-necked flask and contacts with octadecanol, making the surface of octadecanol whiter. A large amount of unreacted silicon tetrachloride enters washing bottle A, turning the air inlet pipe of washing bottle A white and making the water in washing bottle A turbid.

[0177] Performance test data

[0178] Table 2 Test data of silica sol of Examples 1-14 and Comparative Examples 1-14

[0179] pH z-average particle size / nanometer PDI Example 1 5.06 225.24 0.353 Example 2 11.10 221.26 0.343 Example 3 11.41 258.31 0.420 Example 4 4.92 2863.01 0.835 Example 5 5.34 344.97 0.548 Example 6 3.75 6946.59 0.451 Example 7 3.80 6104.56 0.534 Example 8 3.68 255.12 0.337 Example 9 3.30 254.30 0.287 Example 10 3.40 7120.24 0.663 Embodiment 11 3.77 7028.12 0.671 Example 12 10.82 581.85 4.279 Example 13 3.91 493.45 1.270 Embodiment 14 4.61 5806.73 0.735 Comparative Examples 1-14 / / /

[0180] Combining Examples 1-14 and Comparative Examples 1-7 with Table 1, it can be seen that when the melting point range of the higher alcohol at standard atmospheric pressure is not between 15 and 100° C., and the water solubility at standard atmospheric pressure and 25° C. is greater than 1000 mg / L, the silica sol cannot be effectively separated;

[0181] Combining Examples 1-14 and Comparative Examples 3-10 with Table 1, it can be seen that when the alcohol contains an unsaturated bond, the alcohol reacts with silicon tetrachloride or hydrogen chloride to generate a yellow, black, gray, brown or transparent substance, which is very different from the original higher alcohol. After the experiment, the alcohol cannot be recovered, indicating that the alcohol is consumed during the reaction.

[0182] Combining Examples 1-14 and Comparative Examples 9, 11, 12, 13 and Table 1, it can be seen that when the alcohol contains two or more hydroxyl groups, the reaction of the alcohol with silicon tetrachloride cannot generate silica sol under the conditions of the present invention.

[0183] It can be seen from Examples 1-14 and Table 1 that the prepared silica sol and hydrogen chloride are effectively separated, hydrogen chloride is insoluble or almost insoluble in higher alcohols, and hydrogen chloride can be completely or almost completely separated in the form of gas, with no or very little residue in higher alcohols and silicates, so no subsequent treatment such as fractionation is required, which greatly simplifies the preparation of silicates and reduces costs. In addition, after the hydrolysis of silicates is completed, the separation of higher alcohols and silica sol can be carried out by simple solid-liquid separation, and no distillation separation is required, which greatly simplifies the preparation of silica sol, and the prepared silica sol has high purity, achieving effective separation of hydrogen chloride and reducing the preparation cost of ultra-high purity silica sol.

[0184] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention is disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technician familiar with the profession can make some changes or modifications to equivalent embodiments of equivalent changes by using the technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent changes and modifications made to the above embodiments according to the technology of the present invention are within the scope of the technical solution of the present invention without departing from the content of the technical solution of the present invention.

Claims

1. A method for preparing high-purity silica sol and hydrogen chloride, characterized in that: The following steps are involved: S1: Add higher alcohol into a reaction kettle and heat to melt the higher alcohol; S2: adding silicon tetrachloride to the reaction kettle, and the silicon tetrachloride fully reacts with the molten higher alcohol to generate silicate and hydrogen chloride. During the reaction, the higher alcohol and the generated silicate are kept in a heated and molten state, and the hydrogen chloride is discharged from the reaction kettle in the form of gas and collected; S3: The material in the reactor is kept in a heated and molten state, and excess water is added to the reactor to completely hydrolyze the silicate to generate silica hydrosol and higher alcohol; S4: Cooling the reactor until the higher alcohol is converted into a solid state and the silica hydrosol remains in a liquid state; S5: separating the liquid silica hydrosol from the solid higher alcohol; The higher alcohol molecule contains one and no more than one hydroxyl group, the higher alcohol does not contain unsaturated bonds, the melting point range of the higher alcohol at standard atmospheric pressure is 15-100° C., and the water solubility of the higher alcohol at standard atmospheric pressure and 25° C. is less than 1000 mg / L.

2. The method for preparing high-purity silica sol and hydrogen chloride according to claim 1, characterized in that: In step S2, the molar ratio of silicon tetrachloride to the higher alcohol added into the reaction kettle is in the range of silicon tetrachloride / higher alcohol < 0.

25.

3. The method for preparing high-purity silica sol and hydrogen chloride according to claim 1, characterized in that: The higher alcohol is one of dodecanol, tetradecanol, hexadecanol, octadecanoic acid, eicosanol, behenyl alcohol, tetracosanol, hexacosanol, octacosanol, menthol, fenchyl alcohol, tert-butyl cyclohexanol, and cyclododecanoic acid, or a mixture of several combinations thereof.

4. The method for preparing high-purity silica sol and hydrogen chloride according to claim 1, characterized in that: In the steps S1, S2 and S3, the heating temperature is not higher than 100°C.

5. The method for preparing high-purity silica sol and hydrogen chloride according to claim 4, characterized in that: In the steps S1, S2 and S3, the heating temperature ranges from 45°C to 85°C.

6. The method for preparing high-purity silica sol and hydrogen chloride according to claim 5, characterized in that: In the step S3, the temperature of the added water is not less than the temperature in the reactor, and the temperature range of the added water is 45-90°C.

7. The method for preparing high-purity silica sol and hydrogen chloride according to claim 1, characterized in that: In the step S2, silicon tetrachloride is added by blowing into the reactor with dry air or inert gas as a carrier, and hydrogen chloride is discharged by blowing out of the reactor with the dry air or inert gas introduced into the reactor, and the discharged hydrogen chloride enters another reactor containing water, where the hydrogen chloride reacts with water and is collected in the form of a hydrochloric acid solution.

8. The method for preparing high-purity silica sol and hydrogen chloride according to claim 1, characterized in that: In the step S3, the pH of the added water is greater than 7, and the pH of the added water is adjusted by an alkaline pH regulator that does not contain metal ions.

9. The method for preparing high-purity silica sol and hydrogen chloride according to claim 8, characterized in that: The pH regulator is one or a mixture of ammonia, tetraalkylammonium hydroxide, organic amines, guanidines, and amino acids whose aqueous solutions are alkaline.

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