CN105502417A - Preparation method for low-density silica aerogel - Google Patents
Preparation method for low-density silica aerogel Download PDFInfo
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- CN105502417A CN105502417A CN201410715464.0A CN201410715464A CN105502417A CN 105502417 A CN105502417 A CN 105502417A CN 201410715464 A CN201410715464 A CN 201410715464A CN 105502417 A CN105502417 A CN 105502417A
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Abstract
The invention relates to a preparation method for low-density silica aerogel. The method concretely relates to a series of technological parameters for drying aerogel by using supercritical carbon dioxide, and the technological parameters comprise supercritical carbon dioxide drying time, temperature, pressure, carbon dioxide flow, pressure release rate and other factors. The technical scheme mainly hammers at finding influence reasons of the supercritical drying technological parameters on aerogel and realizing preparation of low-density silica aerogel. By controlling the above parameters, the supercritical carbon dioxide drying technology is applied to the aerogel industrialization process and cost control and technology control are realized Through tests, the final obtained silica aerogel possesses the density lower than 0.078 g/cm<3> and possesses the lowest density of 0.038 g/cm<3>.
Description
Technical field
The present invention relates to a kind of preparation method of low-density silicon dioxide aerogel, particularly relate to a kind of method utilizing supercritical carbon dioxide process to prepare low-density silicon dioxide aerogel.
Technical background
Aerosil is a kind of novel light nano-porous materials, the features such as low density, porosity are high, specific surface area is large, perveance, and its thermal conductivity is less than 0.02W/ (mK), it is a kind of material that in current solid material, thermal conductivity is minimum.
The preparation of aerogel is all by sol-gel method (Sol-gel) at present, and it comprises colloidal sol preparation, gel preparation and such three processes of gel drying, and the drying process of the gel vital process that is one of them.Before gel drying, liquid solvent is filled with in gel network structure, in gel drying process, along with the carrying out of drying, solvent content volatilizees, and liquid forms curved liquid surface in the pore of gel network, produces additional pressure, additional pressure makes particle mutually extrude, assembles, thus gel network structure is caved in.Drying means is mainly divided into two kinds, and a kind of is traditional drying means, i.e. constant pressure and dry; Another kind utilizes supercritical carbon dioxide fluid, i.e. supercritical drying.Traditional drying means is difficult to stop the contraction of gel and cracked, has following disadvantageous effect: the fundamental particle of material is thicker, specific surface area declines to a great extent, hole reduces in a large number to the preparation of aerogel.Supercutical fluid has the character of gas and liquid concurrently, without liquid-gas interface, does not therefore also just have surface tension, there is not the additional pressure produced by surface tension in gel capillary pore now.Therefore utilize, under supercritical fluid conditions, drying is carried out to gel, caving in of the gel structure caused by additional pressure can not be produced, avoid the contraction of gel in drying process, maintain gel network skeleton construction, the obtained ultra-fine aerogel with high-specific surface area, even particle size distribution, large pore volume.
Supercritical co drying process reaches its maturity, and compares advantage become clear day by day with traditional technology, and along with the popularization goed deep into and apply of research, application supercritical fluid drying technology is prepared aerogel and will be had good development prospect.
Summary of the invention
The invention provides a kind of method utilizing supercritical co drying process to prepare low density aerogel, the operating parameters of supercritical co dry aerogels process is studied, this to the aerogel of preparation to realize high-performance most important, so the present invention carries out system thinking to its controlling factor, to make supercritical co dry technology be applied to industrial production better.
The invention provides a kind of preparation method of low-density silicon dioxide aerogel, its technical scheme is as follows:
1. the preparation of wet gel: by water glass (modulus 2.5 ~ 3.6), water mixes according to volume ratio 1: 6 ~ 40, after 3 ~ 10min stirs, according to water glass, acid (0.5 ~ 2mol/L) volume ratio 1: 1 ~ 10 adds acid solution, control ph is 7 ~ 9, hydrolysis 5 ~ 60min, obtain wet gel, by wet gel aging 12 ~ 72h at normal temperatures, add ethanol and carry out solvent exchange 12 ~ 72h, wet gel after displacement is placed in the solution hydrophobically modified 12 ~ 36h of hexamethyldisiloxane and ethanol, then deionized water wash 12 ~ 72h and washing with alcohol 12 ~ 72h is used successively.
2. supercritical co is dry: the wet gel obtained finally is obtained dry gas gel by supercritical co drying process.
Wherein supercritical co drying process 1 ~ 16h time of drying;
Supercritical co drying process drying pressure 8 ~ 20MPa;
Supercritical co drying process drying temperature 40 ~ 70 DEG C;
Supercritical co drying process carbon dioxide flow 0.5L/h ~ 120L/h;
It is 0.1 ~ 1MPa/min that supercritical co drying process puts pressure release speed.
The advantage that the present invention has relative to prior art and beneficial effect:
(1) system thinking is carried out to its controlling factor, instruct supercritical co dry technology to be applied in aerogel process of industrialization and realize cost control and technical controlling;
(2) present invention achieves the overcritical Controlling Technology of complexity to become and be easy to control, simple to operate;
(3) aerosil that obtains of the present invention, density is at 0.038g/cm
3~ 0.078g/cm
3.
Embodiment
Embodiment 1 ~ 2: in supercritical drying process, different time of drying is on the impact of aerogel density
Water intaking glass (modulus 3.0), according to volume ratio 1: 12, water glass and water are mixed, through 5min rapid stirring, according to certain volume than water glass and sulfuric acid are poured in mixed solution, control ph is 8, rapid stirring 1min, leave standstill hydrolysis 10min, obtain wet gel, by the wet gel aging 48h at normal temperatures obtained, add ethanol and carry out solvent exchange 36h (each 12h, totally 3 times), wet gel after displacement is placed in the solution hydrophobically modified 36h (concentration 15%) of hexamethyldisiloxane and ethanol, then deionized water wash 36h (each 12h is used successively, totally 3 times) and washing with alcohol 36h (each 12h, totally 3 times), by the wet gel that obtains by supercritical co drying process, control certain time of drying, drying pressure 12MPa, drying temperature 40 DEG C, carbon dioxide flow 20L/h, pressure release speed 1MPa/min, finally obtain dry gas gel.In embodiment 1, time of drying is 1h; Time of drying in embodiment 2 is 10h.
Embodiment 3 ~ 4: in supercritical drying process, different drying pressure is on the impact of aerogel density
Water intaking glass (modulus 3.0), according to volume ratio 1: 12, water glass and water are mixed, through 5min rapid stirring, according to certain volume than water glass and sulfuric acid are poured in mixed solution, control ph is 8, rapid stirring 1min, leave standstill hydrolysis 10min, obtain wet gel, by the wet gel aging 48h at normal temperatures obtained, add ethanol and carry out solvent exchange 36h (each 12h, totally 3 times), wet gel after displacement is placed in the solution hydrophobically modified 36h (concentration 15%) of hexamethyldisiloxane and ethanol, then deionized water wash 36h (each 12h is used successively, totally 3 times) and washing with alcohol 36h (each 12h, totally 3 times), by the wet gel that obtains by supercritical co drying process, control 8h time of drying, certain drying pressure, drying temperature 40 DEG C, carbon dioxide flow 20L/h, pressure release speed 1MPa/min, finally obtain dry gas gel.Drying pressure in embodiment 3 is 8MPa; Drying pressure in embodiment 4 is 18MPa.
Embodiment 5 ~ 6: in supercritical drying process, different drying temperature is on the impact of aerogel density
Water intaking glass (modulus 3.0), according to volume ratio 1: 12, water glass and water are mixed, through 5min rapid stirring, according to certain volume than water glass and sulfuric acid are poured in mixed solution, control ph is 8, rapid stirring 1min, leave standstill hydrolysis 10min, obtain wet gel, by the wet gel aging 48h at normal temperatures obtained, add ethanol and carry out solvent exchange 36h (each 12h, totally 3 times), wet gel after displacement is placed in the solution hydrophobically modified 36h (concentration 15%) of hexamethyldisiloxane and ethanol, then deionized water wash 36h (each 12h is used successively, totally 3 times) and washing with alcohol 36h (each 12h, totally 3 times), by the wet gel that obtains by supercritical co drying process, control 8h time of drying, drying pressure 12MPa, certain drying temperature, carbon dioxide flow 20L/h, pressure release speed 1MPa/min, finally obtain dry gas gel.Drying temperature in embodiment 5 is 40 DEG C; Drying temperature in embodiment 6 is 60 DEG C.
Embodiment 7 ~ 8: in supercritical drying process, different carbon dioxide flow is on the impact of aerogel density
Water intaking glass (modulus 3.0), according to volume ratio 1: 12, water glass and water are mixed, through 5min rapid stirring, according to certain volume than water glass and sulfuric acid are poured in mixed solution, control ph is 8, rapid stirring 1min, leave standstill hydrolysis 10min, obtain wet gel, by the wet gel aging 48h at normal temperatures obtained, add ethanol and carry out solvent exchange 36h (each 12h, totally 3 times), wet gel after displacement is placed in the solution hydrophobically modified 36h (concentration 15%) of hexamethyldisiloxane and ethanol, then deionized water wash 36h (each 12h is used successively, totally 3 times) and washing with alcohol 36h (each 12h, totally 3 times), by the wet gel that obtains by supercritical co drying process, control 8h time of drying, drying pressure 12MPa, drying temperature 40 DEG C, certain carbon dioxide flow, pressure release speed 1MPa/min, finally obtain dry gas gel.Carbon dioxide flow in embodiment 7 is 15L/h; Carbon dioxide flow in embodiment 8 is 30L/h.
Embodiment 9 ~ 10: in supercritical drying process, different pressure release speed is on the impact of aerogel density
Water intaking glass (modulus 3.0), according to volume ratio 1: 12, water glass and water are mixed, through 5min rapid stirring, according to certain volume than water glass and sulfuric acid are poured in mixed solution, control ph is 8, rapid stirring 1min, leave standstill hydrolysis 10min, obtain wet gel, by the wet gel aging 48h at normal temperatures obtained, add ethanol and carry out solvent exchange 36h (each 12h, totally 3 times), wet gel after displacement is placed in the solution hydrophobically modified 36h (concentration 15%) of hexamethyldisiloxane and ethanol, then deionized water wash 36h (each 12h is used successively, totally 3 times) and washing with alcohol 36h (each 12h, totally 3 times), by the wet gel that obtains by supercritical co drying process, control time swap 4h, time of drying 4h, drying pressure 12MPa, drying temperature 40 DEG C, carbon dioxide flow 15L/h, certain pressure release speed, finally obtain dry gas gel.The dry pressure release speed 0.2MPa/min of supercritical co in embodiment 9; The dry pressure release speed 0.4MPa/min of supercritical co in embodiment 10.
Claims (6)
1. the preparation method of a low-density silicon dioxide aerogel, following several step is comprised: by water glass (modulus 2.5 ~ 3.6) described in it is characterized in that, water mixes according to volume ratio 1: 6 ~ 40, after 3 ~ 10min stirs, according to water glass, acid (0.5 ~ 2mol/L) volume ratio 1: 1 ~ 10 adds hydrochloric acid soln, control ph is 7 ~ 9, hydrolysis 5 ~ 60min, obtain wet gel, by wet gel aging 12 ~ 72h at normal temperatures, add ethanol and carry out solvent exchange 12 ~ 72h, wet gel after displacement is placed in the solution hydrophobically modified 12 ~ 36h of hexamethyldisiloxane and ethanol, then deionized water wash 12 ~ 72h and washing with alcohol 12 ~ 72h is used successively respectively, by the wet gel that obtains by supercritical co drying process, finally obtain dry gas gel.
2., according to a kind of method utilizing supercritical process to prepare low density aerogel according to claim 1, it is characterized in that supercritical co drying process 1 ~ 16h time of drying.
3., according to a kind of method utilizing supercritical process to prepare low density aerogel according to claim 1, it is characterized in that supercritical co drying process drying pressure 8 ~ 20MPa.
4., according to a kind of method utilizing supercritical process to prepare low density aerogel according to claim 1, it is characterized in that supercritical co drying process drying temperature 40 ~ 70 DEG C.
5., according to a kind of method utilizing supercritical process to prepare low density aerogel according to claim 1, it is characterized in that supercritical co drying process carbon dioxide flow 0.5L/h ~ 120L/h.
6., according to a kind of method utilizing supercritical process to prepare low density aerogel according to claim 1, it is characterized in that supercritical co drying process puts pressure release speed is 0.1 ~ 1MPa/min.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107128933A (en) * | 2017-06-15 | 2017-09-05 | 武汉理工大学 | A kind of supercritical drying preparation method of aerosil heat-barrier material |
| CN115849390A (en) * | 2022-10-19 | 2023-03-28 | 江苏泛亚微透科技股份有限公司 | Method for preparing silica aerogel based on alkaline environment and silica aerogel |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1241953A (en) * | 1996-11-26 | 2000-01-19 | 卡伯特公司 | Method for producing organically modified, permanently hydrophobic aerogels |
| CN101244825A (en) * | 2008-03-20 | 2008-08-20 | 绍兴纳诺气凝胶新材料研发中心有限公司 | Method for producing silicon dioxide silica aerogel with tripolite as raw material |
| CN103808117A (en) * | 2014-03-12 | 2014-05-21 | 厦门大学 | Continuous drying device and method for mesoporous powder material |
-
2014
- 2014-12-02 CN CN201410715464.0A patent/CN105502417A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1241953A (en) * | 1996-11-26 | 2000-01-19 | 卡伯特公司 | Method for producing organically modified, permanently hydrophobic aerogels |
| CN101244825A (en) * | 2008-03-20 | 2008-08-20 | 绍兴纳诺气凝胶新材料研发中心有限公司 | Method for producing silicon dioxide silica aerogel with tripolite as raw material |
| CN103808117A (en) * | 2014-03-12 | 2014-05-21 | 厦门大学 | Continuous drying device and method for mesoporous powder material |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107128933A (en) * | 2017-06-15 | 2017-09-05 | 武汉理工大学 | A kind of supercritical drying preparation method of aerosil heat-barrier material |
| CN115849390A (en) * | 2022-10-19 | 2023-03-28 | 江苏泛亚微透科技股份有限公司 | Method for preparing silica aerogel based on alkaline environment and silica aerogel |
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