CN101348255A - Method for preparing hydrophobic silica aerogel from rice husk ash based aquagel - Google Patents
Method for preparing hydrophobic silica aerogel from rice husk ash based aquagel Download PDFInfo
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- CN101348255A CN101348255A CNA2008100422224A CN200810042222A CN101348255A CN 101348255 A CN101348255 A CN 101348255A CN A2008100422224 A CNA2008100422224 A CN A2008100422224A CN 200810042222 A CN200810042222 A CN 200810042222A CN 101348255 A CN101348255 A CN 101348255A
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- hydrogel
- rice hull
- hull ash
- silica aerogel
- hydrophobic silica
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Abstract
The invention provides a method for preparing hydrophobic silicon dioxide aerogel by rice hull ash based water gel. The silicon dioxide water gel obtained by taking rice hull ash as materials is subjected to solvent replacement, surface finish in the siloxane phase and normal-pressure drying treatment to prepare the silicon dioxide aerogel with hydrophobic characteristics. For the aerogel prepared, the specific surface area reaches between 500 and 1000m<2>/g, the volume density is between 0.08 and 0.3g/cm<3>, and the sizes of the micropores are mainly distributed in the range of between 1 and 100nm. The method adopts advanced technologies of the solvent replacement, the surface finish and the preparation of the normal-pressure aerogel, thereby unnecessarily using expensive organic resources, avoiding the use of supercritical drying equipment which is commonly used in the convention preparation of the silicon dioxide aerogel and has problems of high price, low efficiency and high risk and the technological investment, and obviously lowering production risk and production cost. Moreover, the method also has the advantages of simple process, strong manageability and suitable mass production and application.
Description
Technical field
The invention belongs to the novel nano-material preparing technical field, relate to the Prepared by Sol Gel Method aerogel, porous gel, the surface group modification of gel hole and constant pressure and dry method.
Background technology
Aerosil is a kind of novel nano porous material, and its principal character is the three-D nano-porous spacial framework with high-permeability, and hole ratio reaches more than 90%, and specific surface area can reach 1000m
2More than/the g.Owing to there is nano aperture, high-specific surface area, make aerogel have the character of many excellences, make aerogel have unusual performance at aspects such as calorifics, electricity, acoustics, optics, these unusual performances make it to have great application potential in fields such as the energy, information, environmental protection, medicine, agricultural chemicals, metallurgy, catalysis, building and scientific experiments.Hydrophobic silicon dioxide aerogel can be resisted the erosion of moisture or damp atmosphere, avoids caving in of inner pore space structure, therefore is absolutely necessary in many Application Areass.
External aerogel research institution mainly contains some institutions of higher education of states such as the sharp Buddhist More National Laboratory (LLNL) of U.S.'s Lorenz, Lorenz Berkeley National Laboratory (LBNL), American National Air and Space Executive Agent MarsHall Space Flight Center (NASA/Marshall Space Flight Center), application energy research center, German ZAE BAYERN Bavaria, the France sharp dust investigation of materials center of illiteracy Derby and the U.S., Japan, Germany, Sweden at present.In addition, BASF AG of the Nano Pore company of the U.S., Hoechst company and Germany is also just carrying out the commercial applications research of aerogel.Domestic research institution comprises Tongji University, the National University of Defense technology, some colleges and universities such as Tsing-Hua University and research institution.
It is raw material that comprehensive existing patented technology and bibliographical information, existing aerosil production method adopt organosilicon more, prepares with the supercritical drying drying method; there is the raw material costliness; complex process, problems such as danger have seriously restricted the large-scale production and the application of aerogel.
Chinese patent (application number 03127920.1 in the Wang Tao application, publication number CN1449997A and application number 200510012186.3, publication number CN1724353A) having introduced with the rice hull ash in is the silicon source, supercritical drying preparation conventional with method hydrophobic silica aerogel.Though it is the silicon source that two methods have all adopted cheap rice husk, still adopts supercritical drying, the cost height, the equipment complexity, dangerous big, difficult suitable scale production.Having introduced with the rice hull ash in the Chinese patent (application number 200510011378.2, publication number CN1669921A) that Wang Tao further applies for is the silicon source, adopts the method for washing and organic solvent metathetical normal pressure preparation (non-hydrophobic) aerosil.
Summary of the invention
The objective of the invention is at the silica hydrogel of rice hull ash through the sol-gel method preparation, by solvent replacing, surface treatment, constant pressure and dry is prepared hydrophobic silicon dioxide aerogel.Low, the environmental protection of this method raw materials cost, technology is simple, and is low for equipment requirements, helps suitability for industrialized production.
Technical scheme of the present invention is: produce hydrophobic silica aerogel under the condition of normal pressure from rice hull ash is the hydrogel of raw material.To be that raw material makes silica hydrogel with the rice hull ash,, reach the purpose that reduces water-content in the hydrogel, and adopt the type siloxane coating materials to carry out finishing then, the hydrophilic OH group of gel surface will be replaced to hydrophobic CH by solvent replacing
3Group by constant pressure and dry, is prepared aerosil again, and its concrete processing step is as follows:
1) solvent replacing
Soak the silica hydrogel that makes by rice hull ash with alcohol organic solvent, to reduce its density;
2) surface treatment
The gel of above-mentioned (1) preparation is soaked into and carried out finishing in the type siloxane surface treatment agent 10 hours to 48 hours, 20 ℃ to 80 ℃ of temperature, the consumption mass ratio of type siloxane surface treatment agent and gel is 1～5: 1;
3) constant pressure and dry
With handling gel separation taking-up completely in the step (2), place heated dry air to carry out drying, 1～2 hour time spent, 70 ℃ to 150 ℃ of drying temperatures can obtain hydrophobic aerosil after drying is finished.
Among the present invention program: the described alcohol organic solvent of step 1) is monohydroxy-alcohols such as methyl alcohol, ethanol, with the consumption mass ratio of hydrogel be 1: 2～5; Step 2) described type siloxane surface treatment agent is X-Si-(CH
3)
3Or X-O-Si-(CH
3)
3, wherein X partly is methyl, ethyl or many carbon alkyl group, with the consumption mass ratio of gel be 1～5: 1; The constant pressure and dry temperature is 70 ℃～150 ℃.
The method that the present invention proposes, compared with prior art:
1. adopting rice hull ash is the silicon source for the preparation of raw material hydrogel, and raw material is utilization of waste material, and the source is abundant, and average price is lower;
2. adopt alcohols to carry out the density that solvent replacing can reduce gel, the consumption of alcohol is less, and operation is simple, can reduce fabrication cycle and cost, and helps quality control;
3. surface treatment is in the wet gel stage, treatment agent can not enter gel inside, the consumption of surface treatment agent significantly reduces, and gel is through aging rear surface structure moulding, be difficult for destroyedly, surface treatment agent exists only between the colloid hole, is easy to recycle, reduce cost greatly, and the aerogel hydrophobic property that obtains performance is good;
4 constant pressure and dries adopt new infrared dry technology cost low, and risk is low;
5 aerogels that make are through the test of BET method, and specific surface area reaches 500～1000m
2/ g, density are low to moderate 0.08g/cm
3, thermal conductivity is lower than 0.03K/mT, finds out the aerogel absorption and the heat-proof quality excellence that obtain thus, has good application prospects in environmental protection and energy-saving field.
Embodiment
The present invention is for extracting the method for hydrophobic silica aerogel under a kind of condition of normal pressure from rice hull ash is the hydrogel of raw material, to with the rice hull ash silica hydrogel that raw material makes, pass through solvent replacing, reduce the proportion of gel, carry out finishing, constant pressure and dry is prepared aerosil, and its technical process is as follows:
1) solvent replacing
Soaking by rice hull ash with alcohol organic solvent is the silica hydrogel that raw material makes, and its density is reduced;
2) surface treatment
The aerogel of above-mentioned (1) preparation is soaked into and carried out finishing in the type siloxane surface treatment agent 10 hours to 48 hours, 20 ℃～80 ℃ of temperature ranges, the consumption mass ratio of type siloxane surface treatment agent and gel is 1～5: 1;
3) constant pressure and dry
To handle gel separation taking-up completely in the step (2), place heated dry air dry, 1～2 hour time spent, 70 ℃～150 ℃ of drying temperatures obtain aerosil after drying is finished.
Described alcohol organic solvent is a monohydroxy-alcohol, as methyl alcohol, and ethanol.
Described type siloxane surface treatment agent is X-Si-(CH
3)
3Or X-O-Si-(CH
3)
3, wherein X partly is methyl, ethyl or many carbon alkyl group.
Specific embodiments is as follows:
Example 1
Getting with the rice hull ash is the hydrogel 100g of feedstock production, add 300ml ethanol, soaked 24 hours, gel-filtration is come out, add Union carbide A-162 150ml and carry out surface treatment, handled 24 hours through 60 ℃, gel is taken out, place it under the infrared drying lamp, 110 ℃ of arid region temperature promptly obtained hydrophobic silicon dioxide aerogel after 1 hour.Measure hydrophobic deg with the methanol aqueous solution method, reach 40%.Its specific surface area is 512m
2/ g, apparent density 0.093g/cm
3, the pore size distribution peak value is 18.3nm.
Example 2
Getting with the rice hull ash is the hydrogel 100g of feedstock production, add 300ml ethanol, soaked 24 hours, gel-filtration is come out, add hexamethyldisiloxane and each 250ml of trimethylchlorosilane and carry out surface treatment, handled 8 hours through 50 ℃, gel is taken out, place it under the infrared drying lamp, 100 ℃ of arid region temperature promptly obtained hydrophobic silicon dioxide aerogel after 1 hour.Measure hydrophobic deg with the methanol aqueous solution method, reach 45%.Its specific surface area is 567m
2/ g, apparent density 0.077g/cm
3, the pore size distribution peak value is 23.4nm.
Example 3
Getting with the rice hull ash is the hydrogel 100g of feedstock production, add 300ml methyl alcohol, soaked 24 hours, gel-filtration is come out, add dimethyldiethoxysilane 400ml and carry out surface treatment, handled 24 hours through 80 ℃, gel is taken out, place it under the infrared drying lamp, 110 ℃ of arid region temperature promptly obtained hydrophobic silicon dioxide aerogel after 2 hours.Measure hydrophobic deg with the methanol aqueous solution method, reach 40%.Its specific surface area is 512m
2/ g, apparent density 0.088g/cm
3, the pore size distribution peak value is 19.0nm.
The present invention has given up the process of washing, and this helps reducing operation, reduces cost of manufacture and shortens fabrication cycle, helps the formation of the inner vesicular structure of aerogel and the formation on water filling surface, makes the key of aerogel Part Quality Control.We adopt solvent replacing and finishing technology, prepare the hydrophobic silica aerogel of low price raw material under condition of normal pressure, have solved the not clear problem of aerogel and solvent surface properties, have enlarged technological tolerance and application.
The above-mentioned description to embodiment is can understand and use the utility model for ease of those skilled in the art.The person skilled in the art obviously can easily make various modifications to these embodiment, and needn't pass through performing creative labour being applied in the General Principle of this explanation among other embodiment.Therefore, the utility model is not limited to the embodiment here, and those skilled in the art should be within protection domain of the present utility model for improvement and modification that the utility model is made according to announcement of the present utility model.
Claims (9)
1. prepare the method for hydrophobic silica aerogel with the rice hull ash based aquagel, it is characterized in that: may further comprise the steps:
(1) solvent replacing
Soak silica hydrogel with alcohol organic solvent and carry out solvent replacing, its density is further reduced;
(2) finishing is handled
To be soaked in again by the gel that above-mentioned (1) obtains and carry out finishing in the type siloxane surface treatment agent, to obtain high hole ratio and hydrophobic surface;
(3) constant pressure and dry
To take out through the gel separation that handled above-mentioned (2), and place and carry out drying under the infrared drying atmosphere, promptly obtain hydrophobic aerosil behind the complete drying.
2. according to claim 1 is to extract the method for hydrophobic silica aerogel the hydrogel of raw material from rice hull ash, it is characterized in that: the density of alcohol organic solvent and can be water-soluble less than water in the solvent replacing.
3. according to claim 2 is to extract the method for hydrophobic silica aerogel the hydrogel of raw material from rice hull ash, it is characterized in that: alcohol organic solvent is-unit's alcohol in the solvent replacing.
4. according to claim 1 is to extract the method for hydrophobic silica aerogel the hydrogel of raw material from rice hull ash, and it is characterized in that: the consumption mass ratio of alcohol organic solvent and hydrogel is 1: 2～5 in the solvent replacing, time swap 4～24 hours.
5. according to claim 1 is to extract the method for hydrophobic silica aerogel the hydrogel of raw material from rice hull ash, and it is characterized in that: the type siloxane surface treatment agent is X-Si-(CH
3)
3Or X-O-Si-(CH
3)
3, wherein X partly is methyl, ethyl or many carbon alkyl group.
6. according to claim 1 is to extract the method for hydrophobic silica aerogel the hydrogel of raw material from rice hull ash, and it is characterized in that: the temperature that finishing is handled is between 20 ℃～80 ℃.
7. according to claim 1 is to extract the method for hydrophobic silica aerogel the hydrogel of raw material from rice hull ash, and it is characterized in that: the time that finishing is handled was at 10 hours to 48 hours.
8. according to claim 1 is to extract the method for hydrophobic silica aerogel the hydrogel of raw material from rice hull ash, and it is characterized in that: the type siloxane surface treatment agent that finishing is handled and the consumption mass ratio of gel are 1～5: 1.
9. according to claim 1 is to extract the method for hydrophobic silica aerogel the hydrogel of raw material from rice hull ash, and it is characterized in that: the temperature of drying treatment is 70 ℃～150 ℃.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNA2008100422224A CN101348255A (en) | 2008-08-29 | 2008-08-29 | Method for preparing hydrophobic silica aerogel from rice husk ash based aquagel |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNA2008100422224A CN101348255A (en) | 2008-08-29 | 2008-08-29 | Method for preparing hydrophobic silica aerogel from rice husk ash based aquagel |
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|---|---|
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102659120A (en) * | 2012-04-18 | 2012-09-12 | 同济大学 | Preparation method for hydrophobic large-size bulk nanometer porous SiO2 aerogel |
| CN102795631A (en) * | 2012-06-19 | 2012-11-28 | 刘相红 | Method for preparing silicon dioxide aerogel |
| CN113767083A (en) * | 2019-08-09 | 2021-12-07 | 株式会社Lg化学 | Method of drying wet gel felt and method of making aerogel felt using the same |
| CN115925376A (en) * | 2022-09-06 | 2023-04-07 | 安徽省城建设计研究总院股份有限公司 | Modified cement vertical barrier material and preparation method thereof |
| WO2023230251A1 (en) | 2022-05-27 | 2023-11-30 | Cabot Corporation | Aerogel composition for thermal insulation |
-
2008
- 2008-08-29 CN CNA2008100422224A patent/CN101348255A/en active Pending
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102659120A (en) * | 2012-04-18 | 2012-09-12 | 同济大学 | Preparation method for hydrophobic large-size bulk nanometer porous SiO2 aerogel |
| CN102795631A (en) * | 2012-06-19 | 2012-11-28 | 刘相红 | Method for preparing silicon dioxide aerogel |
| CN102795631B (en) * | 2012-06-19 | 2013-11-20 | 中亨新型材料科技有限公司 | Method for preparing silicon dioxide aerogel |
| CN113767083A (en) * | 2019-08-09 | 2021-12-07 | 株式会社Lg化学 | Method of drying wet gel felt and method of making aerogel felt using the same |
| WO2023230251A1 (en) | 2022-05-27 | 2023-11-30 | Cabot Corporation | Aerogel composition for thermal insulation |
| CN115925376A (en) * | 2022-09-06 | 2023-04-07 | 安徽省城建设计研究总院股份有限公司 | Modified cement vertical barrier material and preparation method thereof |
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Open date: 20090121 |