Process for preparing aerogels
By performing multi-step reaction and drying in the reaction tank and solvent replacement tank, the problems of long production time and unstable quality in large-scale aerogel production are solved, and efficient production and quality improvement are achieved.
Patent Information
- Application Number
- CN202380048300.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2022-05-11
- Filing Date
- 2023-05-22
- Publication Date
- 2025-04-25
AI Technical Summary
During large-scale production, aerogels face problems such as long production time, large equipment investment and unstable product quality.
The aerogel powder is obtained by reacting the water glass with the first material in the reaction tank and transferring it to the solvent replacement tank to react with the second material to form an organic gel, and finally drying in a dryer.
This method significantly reduces the total production time and improves the final quality of the aerogel by preparing the organic gel individually structurally preventing the destruction of the mixed feedstock.
Smart Images
Figure CN119894600A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to a method for preparing aerogel. Background Art
[0002] Generally speaking, aerogels have a high porosity of up to 99%, a low refractive index of 1.01 to 1.1, a high transparency of 90% or more, and a 2 Advanced materials with high specific surface area of 0.1 W / g or more, extremely low thermal conductivity of 0.02 W / mK or less, etc.
[0003] Aerogels having these properties are evaluated as having high applicability as energy and environmental materials and as materials for the development of the electronics industry due to their unique thermal, electrical and optical properties. Therefore, attempts have been made to use aerogels as super insulating materials for high-speed circuits of next-generation semiconductors, acoustic wave delay materials, catalyst supports, and interlayer insulating materials.
[0004] However, despite the above excellent properties, aerogels still face many difficulties when they are produced on a large scale for commercial use. Manufacturing aerogels can take a long time and require a large investment in building production facilities. Moreover, the quality of aerogels produced on a large scale can be worse than that of aerogels produced in small quantities in the laboratory. Summary of the invention
[0005] Technical problem to be solved by the invention
[0006] The present invention aims to provide a method for preparing aerogels, which method can reduce production time and realize efficient production equipment.
[0007] The present invention also aims to provide a method for preparing aerogels, which, in addition to the above-mentioned increase in productivity, can also improve the quality of the final product.
[0008] Means for solving technical problems
[0009] According to one aspect of the present invention, there is provided a method for preparing an aerogel, the method comprising: reacting water glass with a first material in a reaction tank to obtain a hydrogel; transferring the hydrogel to a solvent displacement tank, and then reacting the hydrogel with a second material in the solvent displacement tank to obtain an organogel; and transferring the organogel to a dryer, and then drying the organogel in the dryer to obtain an aerogel powder.
[0010] The first material may include pure water, nitric acid, and hexamethyldisilazane (HMDS), which may be sequentially charged into a reaction tank.
[0011] In one embodiment, the method includes: reacting water glass with a first material in a reaction tank to obtain a hydrogel; transferring the hydrogel to a solvent displacement tank, and then reacting the hydrogel with a second material in the solvent displacement tank to obtain an organic gel; and transferring the organic gel to a dryer, and then drying the organic gel in the dryer to obtain an aerogel powder, wherein the first material may include pure water, nitric acid and HMDS, the second material may not be put into the reaction tank, and the second material may include n-hexane.
[0012] The method may further include washing the reaction tank after transferring the hydrogel to the solvent displacement tank.
[0013] Washing the reaction tank after transferring the hydrogel to the solvent replacement tank may include spraying pure water on an inner surface of the reaction tank while rotating the spray nozzle 360°.
[0014] The second material may include n-hexane.
[0015] The organogel may not be present in the reaction vessel.
[0016] The solvent displacement tank may be made of a material having lower corrosion resistance, acid resistance, and high temperature strength than the reaction tank.
[0017] The method may further include discharging wastewater generated together with the organogel from the solvent displacement tank before transferring the organogel to the dryer, wherein discharging the wastewater may include controlling, by a controller, opening and closing of a discharge valve for discharging the wastewater based on a water level of the wastewater measured by a liquid level sensor.
[0018] The liquid level sensor may be installed in the solvent replacement tank, and may be a radar type sensor that emits electromagnetic waves in a direction toward an interface between the organic gel layer and the wastewater layer.
[0019] The method may further include washing the solvent displacement tank after transferring the organogel to the dryer.
[0020] Washing the solvent displacement tank after transferring the organogel to the dryer may include spraying n-hexane on the inner surface of the solvent displacement tank while rotating the spray nozzle 360°.
[0021] Effects of the Invention
[0022] According to the method for preparing aerogel of the present invention, a hydrogel is obtained from water glass in a reaction tank, and the hydrogel is transferred to a solvent displacement tank to obtain an organic gel, and then the organic gel is dried in a dryer to obtain an aerogel powder. In this case, when the displacement process is carried out for a long time in the solvent displacement tank, the next round of reaction occurs in the reaction tank, and therefore, the total production time can be significantly reduced.
[0023] Furthermore, since the organogel is prepared separately in the solvent replacement tank, the destruction of the mixed raw materials that occurs when the organogel remains in the reaction tank can be structurally prevented compared to the case where the organogel is prepared in the reaction tank. Due to the absence of such destruction, the quality of the aerogel finally produced can also be improved. BRIEF DESCRIPTION OF THE DRAWINGS
[0024] Figure 1 is a flow chart of a method for preparing an aerogel according to an embodiment of the present invention.
[0025] Figure 2 It is shown that the Figure 1 A conceptual diagram of the arrangement of a preparation apparatus 100 and input of materials of a preparation method.
[0026] Figure 3 It is shown Figure 2 1 is a conceptual diagram of a specific structure of the solvent replacement tank 130. DETAILED DESCRIPTION
[0027] A first embodiment relates to a method for preparing an aerogel, the method comprising:
[0028] reacting water glass with the first material in a reaction tank to obtain a hydrogel;
[0029] transferring the hydrogel to a solvent displacement tank, and then reacting the hydrogel with a second material in the solvent displacement tank to obtain an organogel; and
[0030] The organogel was transferred to a dryer, and then dried in the dryer to obtain an aerogel powder.
[0031] A second embodiment relates to a method for preparing an aerogel, the method comprising
[0032] reacting water glass with the first material in a reaction tank to obtain a hydrogel;
[0033] transferring the hydrogel to a solvent displacement tank, and then reacting the hydrogel with a second material in the solvent displacement tank to obtain an organogel; and
[0034] transferring the organogel to a dryer and then drying the organogel in the dryer to obtain an aerogel powder,
[0035] The first material includes pure water, nitric acid and hexamethyldisilazane (HMDS),
[0036] The second material is not put into the reaction tank, and
[0037] The second material includes n-hexane.
[0038] Modes for carrying out the invention
[0039] Hereinafter, an aerogel preparation method according to an exemplary embodiment of the present invention will be described in detail with reference to the accompanying drawings. In this specification, regardless of the embodiment, the same or similar elements will be assigned the same or similar reference numerals, and their descriptions are the same as the first description.
[0040] Figure 1 is a flow chart of a method for preparing an aerogel according to an embodiment of the present invention, and Figure 2 It is shown that the Figure 1 A conceptual diagram of the arrangement of a preparation apparatus 100 and input of materials of a preparation method.
[0041] Referring to the drawings, the preparation of aerogel starts from the step (S1) of reacting water glass with a first material.
[0042] The first water glass to be put into the reaction tank 110 is sodium silicate (Na2SiO3). After measuring the amount of water glass required for the reaction, the water glass may be placed in a storage tank and then put into the reaction tank 110. Due to gravity, the water glass may be put into the reaction tank 110 in a short time.
[0043] After water glass is put into the reaction tank 110, the first material is put into the reaction tank 110. Specifically, the first material may include pure water (deionized water), nitric acid, and HMDS, which need to be put into the reaction tank 110 in sequence.
[0044] Since water glass and pure water cannot be mixed well due to the large difference in specific gravity, a stirrer may be installed in the reaction tank 110 and used for stirring to fully mix the water glass and pure water. The input of the raw materials may be performed by the following operation: while stirring the water glass and pure water, nitric acid (HNO3, 60%) is input at intervals of 1 minute for 3 minutes, and then HMDS is input. After the input of HMDS, the reaction may be performed for about 5 minutes. It is preferred that the stirrer is continuously operated even during the reaction to mix them well.
[0045] When pure water is added to water glass, water glass is hydrolyzed to form a water glass aqueous solution. When nitric acid is added to the water glass aqueous solution, the phase changes to a gel phase, and pH begins to be neutralized. Subsequently, when HMDS is added, the change to the gel phase is accelerated. The total processing time in the reaction tank 110 is within 20 minutes.
[0046] In order to react water glass with the first material, the temperature inside the reaction tank 110 should be about 45° C. to 50° C. For this purpose, the heating jacket covering the outer shell of the reaction tank 110 uses hot water to heat the reaction tank 110. As the reaction proceeds smoothly, the temperature inside the reaction tank 110 may become about 60° C.
[0047] The reaction scheme of the above reaction is as follows.
[0048] Na2SiO3+2HNO3+HMDS→2NaNO3+NH3+aerogel(Si3(CH3)6O3) n
[0049] Referring to the above reaction scheme, HMDS reacts with nitric acid to generate ammonia (NH3) gas, and the gas is treated using a scrubber 190. The resulting wastewater is transferred to a wastewater treatment facility and treated therein. Whether the reaction in the reaction tank 110 is complete can be determined by confirming the pH of the reaction product.
[0050] When the reaction is completed, a hydrogel is formed in the reaction tank 110. The produced hydrogel is discharged from the reaction tank 110.
[0051] After the reaction tank 110 is emptied, the reaction tank 110 may be washed. For washing, a spray nozzle is operated in the reaction tank 110. The spray nozzle may spray pure water on the inner surface of the reaction tank 110 while rotating 360°. Thus, the reaction tank 110 in a fully washed state receives the next round of water glass and the first material. The resulting waste water is transferred to a waste water treatment facility and treated therein.
[0052] The hydrogel discharged from the reaction tank 110 is transferred (S3) to another container, that is, the solvent displacement tank 130. The solvent displacement tank 130 may be manufactured using a material different from that of the reaction tank 110. Specifically, the reaction tank 110 should be manufactured using, for example, STS316L to cope with corrosion and temperature drop caused by strong acids and strong alkalis. On the other hand, since the solvent displacement tank 130 is not like this, STS304, which is a material having lower corrosion resistance, acid resistance, and high temperature strength than the reaction tank 110, is sufficient.
[0053] Therefore, the solvent displacement tank 130 can be manufactured at about 40% of the material cost of the reaction tank 110. Since the solvent displacement tank 130 should be twice as large as the reaction tank 110, even when the solvent displacement tank 130 is manufactured as a separate unit, the total cost is reduced compared to when only one large reaction tank 110 is manufactured.
[0054] In the solvent displacement tank 130, a second material, such as n-hexane, is added (S5) to the hydrogel. The hydrogel undergoes a condensation reaction with the n-hexane and is thereby displaced to form an organic gel and water. The displacement process is completed within 40 minutes while maintaining a temperature of 50° C. at atmospheric pressure. This time is about twice the time in the reaction tank 110. The resulting wastewater is discharged to a wastewater treatment facility, which will be referred to as Figure 3 Give a description.
[0055] Reference again Figure 1 and Figure 2 , the organogel is transferred (S7) to the dryer 150. After the solvent displacement tank 130 is emptied, the solvent displacement tank 130 may be washed. The washing may be performed by spraying n-hexane on the inner surface of the solvent displacement tank 130. The n-hexane may be fully sprayed on the inner surface of the solvent displacement tank 130 through a spray nozzle that rotates 360°.
[0056] In the dryer 150, the organic gel is turned into (S9) aerogel powder through a drying process. Specifically, the organic gel put into the dryer 150 is stirred at about 130° C. under vacuum. As a result, n-hexane and residual moisture evaporate, and the phase of the organic gel changes to a solid phase. The n-hexane can be separated, transferred to the condenser 170, liquefied, and re-put into the solvent replacement tank 130. The reuse rate of n-hexane can be about 90%, and a certain amount needs to be discharged periodically to maintain quality. In order to compensate for this, new n-hexane is additionally mixed with the reused n-hexane. Through drying, the aerogel powder is subjected to shear force, and its pores are homogenized. The aerogel powder is transferred to a silo and stored, and the required amount can be shipped.
[0057] Reference Figure 3 The solvent displacement tank 130 is further described. Figure 3 It is shown Figure 2 1 is a conceptual diagram of a specific structure of the solvent replacement tank 130.
[0058] Referring to the drawings, organogel O and wastewater W are generated by a condensation reaction in a housing 131 of a solvent displacement tank 130. Here, the organogel O is located above the wastewater W due to a specific gravity difference. When an agitator is operated in the housing 131, layer separation of the organogel O and the wastewater W may occur more easily.
[0059] The wastewater W should be discharged to a wastewater treatment facility via the discharge valve 133 . The discharge valve 133 should be controlled to open just before discharging the wastewater W. To this end, a controller (not shown) that controls opening and closing of the discharge valve 133 is operated based on the sensing result of the liquid level sensor 135 .
[0060] The liquid level sensor 135 measures the water level of the wastewater W by determining the interface I between the organogel O and the wastewater W. To this end, the liquid level sensor 135 may be a radar type sensor installed in the housing 131. Therefore, the liquid level sensor 135 may measure the height of the interface I in a non-contact manner by emitting electromagnetic waves in a direction toward the interface I.
[0061] The controller may control the discharge valve 133 to open and close according to the accurate water level of the waste water W based on the sensing result of the liquid level sensor 135 . This prevents the organic gel O from being discharged together with the waste water W.
[0062] After the waste water W is discharged, the organogel O may be transferred to the dryer 150 via another line 137. In addition, the ammonia generated in the housing 131 may be transferred to the scrubber 190 via a separate line 139.
[0063] The above-mentioned aerogel preparation method is not limited to the composition and operation method of the above-mentioned embodiment. The above-mentioned embodiment may be configured so that various modifications may be made by selectively combining all or some of the embodiments.
[0064] Example
[0065] Water glass was reacted with pure water, nitric acid and HMDS in a reaction tank to prepare a hydrogel, and then the hydrogel was transferred to a solvent displacement tank and reacted with n-hexane to obtain an organogel. The obtained organogel was dried to prepare an aerogel powder. The thermal conductivity of the prepared aerogel powder was measured to be 0.01835 W / mk.
[0066] Comparative Examples
[0067] Water glass was reacted with pure water, nitric acid, HMDS and n-hexane in a reaction tank to prepare a hydrogel, which was then transferred to a solvent displacement tank to obtain an organogel. The obtained organogel was dried to prepare an aerogel powder. The thermal conductivity of the prepared aerogel powder was measured to be 0.02147 W / mk.
[0068] Industrial Applicability
[0069] According to the method for preparing aerogel of the present invention, a hydrogel is obtained from water glass in a reaction tank, and the hydrogel is transferred to a solvent displacement tank to obtain an organic gel, and then the organic gel is dried in a dryer to obtain an aerogel powder. In this case, when the displacement process is carried out for a long time in the solvent displacement tank, the next round of reaction occurs in the reaction tank, and therefore, the total production time can be significantly reduced.
[0070] Furthermore, since the organogel is prepared separately in the solvent replacement tank, the destruction of the mixed raw materials that occurs when the organogel remains in the reaction tank can be structurally prevented compared to the case where the organogel is prepared in the reaction tank. Due to the absence of such destruction, the quality of the aerogel finally produced can also be improved.
Claims
1. A method for preparing an aerogel, the method comprising: reacting water glass with the first material in a reaction tank to obtain a hydrogel; transferring the hydrogel to a solvent displacement tank, and then reacting the hydrogel with a second material in the solvent displacement tank to obtain an organogel; and transferring the organogel to a dryer, and then drying the organogel in the dryer to obtain an aerogel powder, The first material includes pure water, nitric acid and hexamethyldisilazane (HMDS), The second material is not put into the reaction tank, and The second material includes n-hexane. 2 . The method for preparing aerogel according to claim 1 , wherein the pure water, nitric acid and HMDS are sequentially put into the reaction tank. 3 . The method for preparing an aerogel according to claim 1 , further comprising washing the reaction tank after transferring the hydrogel to the solvent replacement tank.
4. The method for preparing an aerogel according to claim 3, wherein washing the reaction tank after transferring the hydrogel to the solvent replacement tank comprises spraying pure water on an inner surface of the reaction tank while rotating a spray nozzle 360°. 5 . The method for preparing aerogel according to claim 1 , wherein the organogel does not exist in the reaction tank. 6 . The method for preparing aerogel according to claim 1 , wherein the solvent replacement tank is made of a material having lower corrosion resistance, acid resistance, and high temperature strength than those of the reaction tank.
7. The method for preparing aerogel according to claim 1, further comprising discharging waste water generated together with the organogel from the solvent displacement tank before transferring the organogel to the dryer, Discharging the waste water includes controlling, by a controller, opening and closing of a discharge valve for discharging the waste water based on a water level of the waste water measured by a liquid level sensor.
8. The method for producing an aerogel according to claim 7, wherein the liquid level sensor is installed in the solvent displacement tank and is a radar type sensor that emits electromagnetic waves in a direction toward an interface between the organic gel layer and the wastewater layer. 9 . The method for preparing an aerogel according to claim 1 , further comprising washing the solvent displacement tank after transferring the organogel to the dryer.
10. The method for preparing an aerogel according to claim 9, wherein washing the solvent displacement tank after transferring the organogel to the dryer comprises spraying n-hexane on an inner surface of the solvent displacement tank while rotating a spray nozzle 360°.