CN104891510A - Method for preparing millimeter SiO2 aerogel ball by drying under normal pressure - Google Patents
Method for preparing millimeter SiO2 aerogel ball by drying under normal pressure Download PDFInfo
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Abstract
The invention discloses a method for preparing a millimeter SiO2 aerogel ball by drying under normal pressure. The method comprises the following steps of standing and hydrolyzing silica sol with the pH value of 2-3 at room temperature for 12-24h, adjusting the pH value to be 4-6, and then dripping to SiO2 aerogel powder with a hydrophobic angle larger than 90 degrees; standing and performing gelatinization in air for 1-2h to form a spherical wet gel; soaking in absolute ethyl alcohol, carrying out seasoning and ageing for multiple times, then modifying and drying to obtain the millimeter SiO2 aerogel ball. The preparation method has the characteristics of being simple and feasible, and low in cost. The particle size distribution of the prepared SiO2 aerogel ball is 1-2mm, and the specific surface area is 500-850m<2>/g. The millimeter SiO2 aerogel ball has a continuous porous structure with a nano size, the formed net porous structure has the aperture size about 5-20nm, and the inner structure is a typical nanometer mesoporous material and shows well hydrophobic nature.
Description
Technical field
The present invention relates to nano-porous materials preparation field, be specifically related to a kind of constant pressure and dry that adopts and prepare grade SiO
2the method of airsetting glueballs.
Background technology
At present, both at home and abroad about preparation SiO
2the report of aerogel is a lot, usually with silicon ester or water glass for raw material, the finished product prepared mostly are irregular block and powder, prepare large SiO
2airsetting blob of viscose is comparatively difficult in technique, and the size preparing special shape block materials is more wayward, and there is the crisp frangible defect with being difficult to carry out practical application of matter, and the latter then there will be problems such as filling uneven or recovery difficulty in actual applications.And adopt supercritical drying to prepare SiO
2aerogel block body is high to equipment requirements, there is unsafe factor etc.In order to expand SiO
2the range of application of aerogel and efficiency, make up SiO
2deficiency in aerogel microball technology of preparing, expects SiO
2aerogel is prepared into profile rule and the microballoon of size tunable, is expected to for its extensive Synthesis and applications provides a practicable route, significant.
The Chinese patent of " a kind of TiO2/ aerosil ball and preparation method thereof " (patent publication No. is CN1546225A), its balling technique is: in balling-up gel formation container, ammoniacal liquor is housed, tensio-active agent and kerosene, drip solvent in gel formation device.But use ammonia vol large in its preparation technology, colloidal sol is not easy balling-up, and oil phase is recycling not easily.The Chinese patent of " a kind of method preparing grade aerosil ball " (patent publication No. is CN104163431A), its balling technique is: ammoniacal liquor and silicon-dioxide alcosol are entered static mixer mixing by peristaltic pump, flowing into from bottom fills in the gel formation device of soybean oil and ethanol again, forms other silica dioxide gel ball of grade.But the supercritical drying process adopted is high to equipment requirements, condition controls and operational difficulty.
Summary of the invention
For overcoming the problems of the prior art, a kind of constant pressure and dry that adopts is the object of the present invention is to provide to prepare grade SiO
2the method of airsetting glueballs, the method can obtain the continuous pore space structure with nano-scale, and density is low, specific surface area is high, the mesoporous SiO be evenly distributed
2airsetting glueballs, and preparation method is simple, is easy to realize.
For achieving the above object, the technical solution used in the present invention is:
A kind of constant pressure and dry that adopts prepares grade SiO
2the method of airsetting glueballs, comprises the following steps:
1) by pH value be 2 ~ 3 silicon sol at room temperature leave standstill hydrolysis 12 ~ 24h;
2) pH value of the silicon sol after hydrolysis is adjusted to 4 ~ 6, obtains prefabricated silicon sol;
3) hydrophobic angle is greater than the SiO of 90 °
2aerogel powder is evenly laid on flat board as microscope carrier;
4) prefabricated silicon sol is dropwise added drop-wise on microscope carrier, then in air, leaves standstill gelation 1 ~ 2h, form spherical wet gel;
5), after being soaked in dehydrated alcohol by spherical wet gel, gel ball is obtained;
6), after gel ball being carried out repeatedly ageing, burin-in process, adopt the mixing solutions of trimethylchlorosilane and normal hexane to carry out immersion modification 12 ~ 24h, obtain modified gel ball;
7) by dry after the cleaning of modified gel ball, grade SiO is obtained
2airsetting glueballs.
Described step 1) in pH value be 2 ~ 3 silicon sol obtain by the following method: to be the pH value of the silicon sol of 30% be quality of regulation concentration 2 ~ 3 or after by industrial-grade sodium silicate, 1:4 mixes by volume with deionized water, obtains through the ion-exchange of strong acid type styrene type cation exchange resin.
Described step 2) in pH value be that the ammonia soln of employing 0.5 ~ 2mol/L carries out regulating.
Described step 4) in the spacing of spherical wet gel be greater than 3mm.
Described step 5) in soak time be 10 ~ 14h.
Described step 6) in the volume ratio of trimethylchlorosilane and normal hexane be 1:(9 ~ 10).
Described step 6) in repeatedly ageing, aging technique process detailed process be: (1) adopts the aging 10 ~ 20h of dehydrated alcohol; (2) the aging 45 ~ 52h of mixed solution of tetraethoxy and dehydrated alcohol is adopted; (3) the aging 20 ~ 30h of normal hexane is adopted; (4) the aging 40 ~ 50h of mixed solution of tetraethoxy and dehydrated alcohol is adopted; (5) the aging 22 ~ 30h of normal hexane is adopted; Wherein, in the mixed solution of tetraethoxy and dehydrated alcohol, tetraethoxy accounts for 70 ~ 80% of the volume of the mixed solution of tetraethoxy and dehydrated alcohol.
Described step 6) in gel ball is carried out repeatedly ageing, burin-in process after, adopt normal hexane cleaning gel ball after carry out modification again.
Described step 7) in cleaning adopt normal hexane carry out.
Described step 7) in drying carry out in 30 ~ 40 DEG C at ambient pressure.
Compared with prior art, the present invention has following beneficial effect: the present invention with silicon source for raw material, adopt the techniques such as ion-exchange, collosol and gel, dropping liquid balling-up, surface modification, prepared grade hydrophobic type SiO2 airsetting glueballs in conjunction with drop method and constant pressure and dry technology, this preparation method has the features such as simple and easy to do, cost is low; The pH value of the silicon sol after hydrolysis is adjusted to 4 ~ 6, silicon sol moment gel can be prevented; Due to SiO in the present invention
2the hydrophobic angle of aerogel powder is greater than 90 °, so small droplets can be made to have sufficiently high sphericity; When the surface strength of spherical small droplets can overcome the surface tension of ethanolic soln, more spherical small droplets is soaked in dehydrated alcohol, can the breakup of drop be prevented; Gel internal networking structure can be strengthened, to prevent gel ball broken in constant pressure and dry process through repeatedly ageing, aging work process.
The SiO that the present invention prepares
2the diameter of airsetting glueballs is 0.1 ~ 3mm, and specific surface area is 500 ~ 850m
2/ g, has the continuous pore space structure of nano-scale, and the network vesicular structure aperture size formed is about 5 ~ 20nm, and internal structure is typical mesoporous nano material, presents good hydrophobic property; Density is low, specific surface area is high, be mesoporously evenly distributed, and the SiO of gained
2airsetting glueballs is grade spherule, and the rolling characteristics of airsetting glueballs significantly improves, and is easy to application, has a extensive future in fields such as heat insulation, catalysis and chromatogram fillings; To the SiO of preparation
2airsetting glueballs has carried out SEM, BET, DG-TA, FTIR and has characterized, and all shows prepared SiO
2aerogel ball has typical properties of aerogels.The present invention is by SiO
2aerogel is prepared into profile rule and size tunable spherical, is expand SiO
2the range of application of aerogel and efficiency, make up SiO
2deficiency in airsetting glueballs technology of preparing, significant.
Further, be dropwise added drop-wise on microscope carrier by prefabricated silicon sol, be that dispersion drips, the silicon sol ball on microscope carrier is separated from each other the spacing being greater than 3mm, can prevent colloidal sol from contacting like this and merge.
Further, clean gel ball with normal hexane before modified, thoroughly can remove the ethanol in gel, to prevent trimethylammonium chlorine alkane and ethanol synthesis, affect modified effect.
Further, the present invention adopts constant pressure and dry, and reaction conditions is gentle, avoids supercritical drying process high to equipment requirements, and condition controls and operates the problems such as difficult.The method technique is simple, with low cost and potential safety hazard is little.
Further, dryly in the present invention to carry out at 30 ~ 40 DEG C, can prevent that temperature is too high, the too fast gel ball that causes of rate of drying is broken.
Accompanying drawing explanation
Fig. 1 is grade SiO in the present invention
2the photomacrograph of airsetting glueballs.
Fig. 2 is grade SiO in the present invention
2the diameter Distribution statistical graph of airsetting glueballs.
Fig. 3 is grade SiO in the present invention
2the SEM figure of airsetting glueballs.
Fig. 4 is grade SiO in the present invention
2the N of airsetting glueballs
2absorption-desorption thermoisopleth.
Fig. 5 is grade SiO in the present invention
2the graph of pore diameter distribution of airsetting glueballs.
Fig. 6 is grade SiO in the present invention
2the TG-DTA curve of airsetting glueballs.
Fig. 7 is grade SiO in the present invention
2the FTIR spectrum of airsetting glueballs.
Embodiment
Below in conjunction with drawings and Examples, the present invention is described in detail.Hydrophobic angle is adopted to be greater than the SiO of 90 ° in the present invention
2aerogel powder is to ensure hydrophilic SiO as microscope carrier
2wet gel can remain good grade spherule on microscope carrier surface in subsequent processes.
Embodiment 1
1) take industrial-grade sodium silicate as silicon source, by industrial-grade sodium silicate and deionized water by volume for 1:4 mixes, solution after mixing is prepared through the ion-exchange of strong acid type styrene type cation exchange resin the silicon sol that pH value is 2 ~ 3, then at room temperature leaves standstill hydrolysis 12h.
2) in the silicon sol after hydrolysis, slowly drip the ammonia soln of 1mol/L, regulate its pH value to 6, obtain prefabricated silicon sol.
3) hydrophobic angle is about the SiO of 126 °
2aerogel powder is evenly laid on flat board as microscope carrier.
4) syringe is adopted dropwise to be added drop-wise on microscope carrier by prefabricated silicon sol, form the stable spherical droplets of diameter 0.1 ~ 5mm, in air, leave standstill gelation 1h with the surface tension making the surface strength of spherical small droplets enough overcome ethanolic soln, form spherical wet gel; The spacing of spherical wet gel is greater than 3mm, can prevent colloidal sol from contacting and merge.
5) modification 12h is soaked, to make SiO by spherical wet gel immigration ethanol solution
2the thorough gelation of ball, obtains wet gel ball.
6) wet gel ball is carried out repeatedly ageing, burin-in process to strengthen gel internal networking structure, then adopt normal hexane to clean thoroughly to remove the ethanol in gel, to prevent trimethylammonium chlorine alkane and ethanol synthesis, affect modified effect.Then adopt the trimethylchlorosilane of volume ratio 1:9 and the mixing solutions of normal hexane to carry out modification 24h, obtain modified gel ball; Wherein, repeatedly ageing, aging technique process detailed process are: (1) adopts the aging 12h of dehydrated alcohol; (2) the aging 48h of mixed solution of tetraethoxy and dehydrated alcohol is adopted; (3) the aging 24h of normal hexane is adopted; (4) the aging 48h of mixed solution of tetraethoxy and dehydrated alcohol is adopted; (5) the aging 24h of normal hexane is adopted; Wherein, in the mixed solution of tetraethoxy and dehydrated alcohol, tetraethoxy accounts for 70% of the volume of the mixed solution of tetraethoxy and dehydrated alcohol.
7) modified gel ball is cleaned 3 times through normal hexane, then in loft drier, at 35 DEG C, carry out constant pressure and dry, obtain grade SiO
2airsetting glueballs, this airsetting glueballs is hydrophobic type.
The SiO obtained to embodiment 1
2the photomacrograph of airsetting glueballs, see Fig. 1, as can be seen from Figure 1, SiO
2the diameter of airsetting glueballs is about 1 ~ 1.5mm, surfacing, and sphericity is high.
Fig. 2 is the sphere diameter distribution to the millimeter spherical silicon dioxide aerogel that embodiment 1 is prepared in a large number, and as can be seen from Figure 2, ball primary diameters prepared by the present embodiment is between 1.1 ~ 1.5mm, wherein maximum with the ball of 1.3 ~ 1.35mm diameter.
Fig. 3 is the scanning electron photo of grade spherical silicon dioxide aerogel section prepared by the present embodiment, and as can be seen from Figure 3, the network structure of aerogel is kept preferably, still remains a large amount of meso-hole structure.
Fig. 4 is the nitrogen adsorption-desorption curve of grade spherical silicon dioxide aerogel prepared by the present embodiment, calculates and shows that specific surface area is 734.4m
2/ g, shows that it is the material with aerogel structure.
Fig. 5 is the nano aperture distribution of grade spherical silicon dioxide aerogel prepared by the present embodiment, and as can be seen from Figure 5, primary aperture is distributed in 40 ~ 120 dusts, and most probable pore size is 121.9 dusts, and its mean pore size is 73.5 dusts, belongs to meso-hole structure.
Fig. 6 is the differential thermal-thermogravimetric curve of grade spherical silicon dioxide aerogel prepared by the present embodiment, is raised to 1000 DEG C of quality only reduces 12.7% from room temperature, is an endothermic process at temperature-rise period.
Fig. 7 is the infrared spectra curve of grade spherical silicon dioxide aerogel prepared by the present embodiment, as can be seen from Figure 7, except the Si-O key of itself, also has significantly-CH
3, to show in preparation process in microtexture scion grafting-CH
3, therefore there is certain hydrophobicity.
Embodiment 2
1) take industrial-grade sodium silicate as silicon source, by industrial-grade sodium silicate and deionized water by volume for 1:4 mixes, solution after mixing is prepared through the ion-exchange of strong acid type styrene type cation exchange resin the silicon sol that pH value is 2, then at room temperature leaves standstill hydrolysis 24h.
2) in the silicon sol after hydrolysis, slowly drip the ammonia soln of 1mol/L, regulate its pH value to 5, obtain prefabricated silicon sol.
3) hydrophobic angle is about the SiO of 126 °
2aerogel powder is evenly laid on flat board as microscope carrier.
4) syringe is adopted dropwise to be added drop-wise on microscope carrier by prefabricated silicon sol, form the stable spherical droplets of diameter 0.1 ~ 5mm, in air, leave standstill gelation 2h, with the surface tension making the surface strength of spherical small droplets enough overcome ethanolic soln, form spherical wet gel; The spacing of spherical wet gel is greater than 3mm, can prevent colloidal sol from contacting and merge.
5) 12h is soaked, to make SiO by spherical wet gel immigration ethanol solution
2the thorough gelation of ball, obtains wet gel ball.
6) wet gel ball is carried out repeatedly ageing, aging technique process to strengthen gel internal networking structure, then adopt normal hexane to clean thoroughly to remove the ethanol in gel, to prevent trimethylammonium chlorine alkane and ethanol synthesis, affect modified effect.Then adopt the trimethylchlorosilane of volume ratio 1:9 and the mixing solutions of normal hexane to carry out modification 24h, obtain modified gel ball; Wherein, repeatedly ageing, aging technique process detailed process are: (1) adopts the aging 10h of dehydrated alcohol; (2) the aging 46h of mixed solution of tetraethoxy and dehydrated alcohol is adopted; (3) the aging 27h of normal hexane is adopted; (4) the aging 50h of mixed solution of tetraethoxy and dehydrated alcohol is adopted; (5) the aging 22h of normal hexane is adopted; Wherein, in the mixed solution of tetraethoxy and dehydrated alcohol, tetraethoxy accounts for 80% of the volume of the mixed solution of tetraethoxy and dehydrated alcohol.
7) modified gel ball normal hexane is cleaned 3 times, then in loft drier at 35 DEG C constant pressure and dry, obtain grade SiO
2airsetting glueballs, this airsetting glueballs is hydrophobic type.
Nitrogen adsorption-the desorption curve of the grade spherical silicon dioxide aerogel prepared by the present embodiment, calculates and shows that specific surface area is 546.8m
2/ g, shows that it is the material with aerogel structure, and has the continuous pore space structure of nano-scale, and the network vesicular structure aperture size formed is about 16nm.
Embodiment 3
1) take industrial-grade sodium silicate as silicon source, by industrial-grade sodium silicate and deionized water by volume for 1:4 mixes, solution after mixing is prepared through the ion-exchange of strong acid type styrene type cation exchange resin the silicon sol that pH value is 3, then at room temperature leaves standstill hydrolysis 12h.
2) hydrophobic angle is about the SiO of 126 °
2aerogel powder is evenly laid on flat board as microscope carrier.
3) adopt syringe by pH value be 3 silicon sol dropwise disperse to be added drop-wise on aerogel microscope carrier, obtain spherical colloidal sol and drip.
4) another syringe is adopted to be injected by the ammonia soln of 1mol/L in spherical colloidal sol drips, regulating spherical colloidal sol to drip pH value is 5, to accelerate gelation, then in air, leave standstill gelation 1h, to form the capillary spherical gel that surface strength enough overcomes ethanolic soln.
5) 12h is soaked, to make SiO by spherical gel immigration ethanol solution
2the thorough gelation of ball, obtains wet gel ball.
6) wet gel ball is carried out repeatedly ageing, aging technique process, to strengthen gel internal networking structure, then adopt normal hexane to clean thoroughly to remove the ethanol in gel, to prevent trimethylammonium chlorine alkane and ethanol synthesis, affect modified effect.Then adopt the trimethylchlorosilane of volume ratio 1:9 and the mixing solutions of normal hexane to carry out modification 24h, obtain modified gel ball; Wherein, repeatedly ageing, aging technique process detailed process are: (1) adopts the aging 20h of dehydrated alcohol; (2) the aging 50h of mixed solution of tetraethoxy and dehydrated alcohol is adopted; (3) the aging 25h of normal hexane is adopted; (4) the aging 45h of mixed solution of tetraethoxy and dehydrated alcohol is adopted; (5) the aging 30h of normal hexane is adopted; Wherein, in the mixed solution of tetraethoxy and dehydrated alcohol, tetraethoxy accounts for 75% of the volume of the mixed solution of tetraethoxy and dehydrated alcohol.
7) modified gel ball normal hexane is cleaned 3 times, then in loft drier at 35 DEG C constant pressure and dry, obtain grade SiO
2airsetting glueballs, this airsetting glueballs is hydrophobic type.
Nitrogen adsorption-the desorption curve of the grade spherical silicon dioxide aerogel prepared by the present embodiment, calculates and shows that specific surface area is 852.1m
2/ g, shows that it is the material with aerogel structure, and has the continuous pore space structure of nano-scale, and the network vesicular structure aperture size formed is about 12nm.
Embodiment 4
1) take industrial-grade sodium silicate as silicon source, by industrial-grade sodium silicate and deionized water by volume for 1:4 mixes, solution after mixing is prepared through the ion-exchange of strong acid type styrene type cation exchange resin the silicon sol that pH value is 2, then at room temperature leaves standstill hydrolysis 24h.
2) hydrophobic angle is about the SiO of 126 °
2aerogel powder is evenly laid on flat board as microscope carrier.
3) adopt syringe by pH value be 2 silicon sol dropwise disperse to be added drop-wise on aerogel microscope carrier, obtain spherical colloidal sol and drip.
4) another syringe is adopted to be injected by the ammonia soln of 1mol/L in spherical colloidal sol drips, regulating spherical colloidal sol to drip pH value is 5, to accelerate gelation, then in air, leave standstill gelation 2h, to form the capillary spherical gel that surface strength enough overcomes ethanolic soln.
5) 12h is soaked, to make SiO when spherical gel moves in ethanol solution
2the thorough gelation of ball, obtains wet gel ball.
6) wet gel ball is carried out repeatedly ageing, aging technique process, to strengthen gel internal networking structure, then adopt normal hexane to clean thoroughly to remove the ethanol in gel, to prevent trimethylammonium chlorine alkane and ethanol synthesis, affect modified effect.Then adopt the trimethylchlorosilane of volume ratio 1:9 and the mixing solutions of normal hexane to carry out modification 24h, obtain modified gel ball; Wherein, repeatedly ageing, aging technique process detailed process are: (1) adopts the aging 16h of dehydrated alcohol; (2) the aging 52h of mixed solution of tetraethoxy and dehydrated alcohol is adopted; (3) the aging 20h of normal hexane is adopted; (4) the aging 46h of mixed solution of tetraethoxy and dehydrated alcohol is adopted; (5) the aging 22h of normal hexane is adopted; Wherein, in the mixed solution of tetraethoxy and dehydrated alcohol, tetraethoxy accounts for 72% of the volume of the mixed solution of tetraethoxy and dehydrated alcohol.
7) modified gel ball normal hexane is cleaned 3 times, then in loft drier at 35 DEG C constant pressure and dry, obtain grade SiO
2airsetting glueballs, this airsetting glueballs is hydrophobic type.
Nitrogen adsorption-the desorption curve of the grade spherical silicon dioxide aerogel prepared by the present embodiment, calculates and shows that specific surface area is 653.5m
2/ g, shows that it is the material with aerogel structure, and has the continuous pore space structure of nano-scale, and the network vesicular structure aperture size formed is about 9nm.
Embodiment 5
1) using silicon sol as silicon source, quality of regulation concentration is the pH value of the silicon sol of 30% is 2.5, then at room temperature leaves standstill hydrolysis 14h.
2) in the silicon sol after hydrolysis, slowly drip the ammonia soln of 0.5mol/L, regulate its pH value to 4, obtain prefabricated silicon sol.
3) hydrophobic angle is greater than the SiO of 90 °
2aerogel powder is evenly laid on flat board as microscope carrier.
4) syringe is adopted dropwise to be added drop-wise on microscope carrier by prefabricated silicon sol, form the stable spherical droplets of diameter 0.1 ~ 5mm, in air, leave standstill gelation 1.5h with the surface tension making the surface strength of spherical small droplets enough overcome ethanolic soln, form spherical wet gel; The spacing of spherical wet gel is greater than 3mm, can prevent colloidal sol from contacting and merge.
5) modification 10h is soaked to make SiO by spherical wet gel immigration ethanol solution
2the thorough gelation of ball, obtains wet gel ball.
6) wet gel ball is carried out repeatedly ageing, burin-in process to strengthen gel internal networking structure, then adopt normal hexane to clean thoroughly to remove the ethanol in gel, to prevent trimethylammonium chlorine alkane and ethanol synthesis, affect modified effect.Then adopt the trimethylchlorosilane of volume ratio 1:10 and the mixing solutions of normal hexane to carry out modification 12h, obtain modified gel ball; Wherein, repeatedly ageing, aging technique process detailed process are: (1) adopts the aging 20h of dehydrated alcohol; (2) the aging 48h of mixed solution of tetraethoxy and dehydrated alcohol is adopted; (3) the aging 30h of normal hexane is adopted; (4) the aging 40h of mixed solution of tetraethoxy and dehydrated alcohol is adopted; (5) the aging 27h of normal hexane is adopted; Wherein, in the mixed solution of tetraethoxy and dehydrated alcohol, tetraethoxy accounts for 78% of the volume of the mixed solution of tetraethoxy and dehydrated alcohol.
7) modified gel ball is cleaned 3 times through normal hexane, then in loft drier, at 30 DEG C, carry out constant pressure and dry, obtain grade SiO
2airsetting glueballs, this airsetting glueballs is hydrophobic type.
Embodiment 6
1) using silicon sol as silicon source, quality of regulation concentration is the pH value of the silicon sol of 30% is 3, then at room temperature leaves standstill hydrolysis 20h.
2) in the silicon sol after hydrolysis, slowly drip the ammonia soln of 2mol/L, regulate its pH value to 6, obtain prefabricated silicon sol.
3) hydrophobic angle is greater than the SiO of 90 °
2aerogel powder is evenly laid on flat board as microscope carrier.
4) syringe is adopted dropwise to be added drop-wise on microscope carrier by prefabricated silicon sol, form the stable spherical droplets of diameter 0.1 ~ 5mm, in air, leave standstill gelation 1h with the surface tension making the surface strength of spherical small droplets enough overcome ethanolic soln, form spherical wet gel; The spacing of spherical wet gel is greater than 3mm, can prevent colloidal sol from contacting and merge.
5) modification 14h is soaked to make SiO by spherical wet gel immigration ethanol solution
2the thorough gelation of ball, obtains wet gel ball.
6) wet gel ball is carried out repeatedly ageing, burin-in process to strengthen gel internal networking structure, then adopt normal hexane to clean thoroughly to remove the ethanol in gel, to prevent trimethylammonium chlorine alkane and ethanol synthesis, affect modified effect.Then adopt the trimethylchlorosilane of volume ratio 1:9.5 and the mixing solutions of normal hexane to carry out modification 16h, obtain modified gel ball; Wherein, repeatedly ageing, aging technique process detailed process are: (1) adopts the aging 18h of dehydrated alcohol; (2) the aging 45h of mixed solution of tetraethoxy and dehydrated alcohol is adopted; (3) the aging 21h of normal hexane is adopted; (4) the aging 43h of mixed solution of tetraethoxy and dehydrated alcohol is adopted; (5) the aging 28h of normal hexane is adopted; Wherein, in the mixed solution of tetraethoxy and dehydrated alcohol, tetraethoxy accounts for 70% of the volume of the mixed solution of tetraethoxy and dehydrated alcohol.
7) modified gel ball is cleaned 3 times through normal hexane, then in loft drier, at 40 DEG C, carry out constant pressure and dry, obtain grade SiO
2airsetting glueballs, this airsetting glueballs is hydrophobic type.
The present invention take industrial-grade sodium silicate as silicon source or is raw material with silicon sol, prefabricated silicon sol is dropped on microscope carrier, form the spherical drop of diameter 0.1 ~ 5mm, make small droplets gel in atmosphere, when the surface strength of spherical small droplets enough overcomes ethanolic soln capillary time, small droplets is put into ethanolic soln soak, then exchange and surface modification through more solvent, the present invention has prepared grade hydrophobic type SiO in conjunction with the technology such as drop method and constant pressure and dry
2airsetting glueballs, and SEM, BET, DG-TA, FTIR sign has been carried out to prepared ball, all show that prepared ball has typical properties of aerogels.By SiO
2aerogel is prepared into profile rule and size tunable spherical, is expand SiO
2the range of application of aerogel and efficiency, make up SiO
2deficiency in airsetting glueballs technology of preparing, significant.
Time in the present invention using silicon sol as silicon source, the mass concentration on market be 30% silicon sol also can, only its pH value need be adjusted to 2 ~ 3.
The present invention compared with prior art has the following advantages:
1. the present invention take industrial-grade sodium silicate as silicon source, has prepared grade hydrophobic type SiO in conjunction with the technology such as drop method and constant pressure and dry
2airsetting glueballs, and SEM, BET, DSC-TGA, FTIR sign has been carried out to prepared ball, all show that prepared ball has typical properties of aerogels.
2. the present invention adopts constant pressure and dry, and reaction conditions is gentle, avoids supercritical drying process high to equipment requirements, and condition controls and operates the problems such as difficult.The method technique is simple, with low cost and potential safety hazard is little.
3. the grade SiO for preparing of method of the present invention
2aerogel spherolite footpath is distributed as 1 ~ 2mm, and specific surface area is 500 ~ 850m
2/ g, can be prepared into profile rule and size tunable spherical, is expand SiO
2the range of application of aerogel and efficiency, make up SiO
2deficiency in airsetting glueballs technology of preparing, significant.
Claims (10)
1. one kind adopts constant pressure and dry to prepare grade SiO
2the method of airsetting glueballs, is characterized in that, comprises the following steps:
1) by pH value be 2 ~ 3 silicon sol at room temperature leave standstill hydrolysis 12 ~ 24h;
2) pH value of the silicon sol after hydrolysis is adjusted to 4 ~ 6, obtains prefabricated silicon sol;
3) hydrophobic angle is greater than the SiO of 90 °
2aerogel powder is evenly laid on flat board as microscope carrier;
4) prefabricated silicon sol is dropwise added drop-wise on microscope carrier, then in air, leaves standstill gelation 1 ~ 2h, form spherical wet gel;
5), after being soaked in dehydrated alcohol by spherical wet gel, gel ball is obtained;
6), after gel ball being carried out repeatedly ageing, burin-in process, adopt the mixing solutions of trimethylchlorosilane and normal hexane to carry out immersion modification 12 ~ 24h, obtain modified gel ball;
7) by dry after the cleaning of modified gel ball, grade SiO is obtained
2airsetting glueballs.
2. employing constant pressure and dry according to claim 1 prepares grade SiO
2the method of airsetting glueballs, it is characterized in that, described step 1) in pH value be 2 ~ 3 silicon sol obtain by the following method: to be the pH value of the silicon sol of 30% be quality of regulation concentration 2 ~ 3 or after by industrial-grade sodium silicate, 1:4 mixes by volume with deionized water, obtains through the ion-exchange of strong acid type styrene type cation exchange resin.
3. employing constant pressure and dry according to claim 1 prepares grade SiO
2the method of airsetting glueballs, is characterized in that, described step 2) in pH value be that the ammonia soln of employing 0.5 ~ 2mol/L carries out regulating.
4. employing constant pressure and dry according to claim 1 prepares grade SiO
2the method of airsetting glueballs, is characterized in that, described step 4) in the spacing of spherical wet gel be greater than 3mm.
5. employing constant pressure and dry according to claim 1 prepares grade SiO
2the method of airsetting glueballs, is characterized in that, described step 5) in soak time be 10 ~ 14h.
6. employing constant pressure and dry according to claim 1 prepares grade SiO
2the method of airsetting glueballs, is characterized in that, described step 6) in the volume ratio of trimethylchlorosilane and normal hexane be 1:(9 ~ 10).
7. employing constant pressure and dry according to claim 1 prepares grade SiO
2the method of airsetting glueballs, is characterized in that, described step 6) in repeatedly ageing, aging technique process detailed process be: (1) adopts the aging 10 ~ 20h of dehydrated alcohol; (2) the aging 45 ~ 52h of mixed solution of tetraethoxy and dehydrated alcohol is adopted; (3) the aging 20 ~ 30h of normal hexane is adopted; (4) the aging 40 ~ 50h of mixed solution of tetraethoxy and dehydrated alcohol is adopted; (5) the aging 22 ~ 30h of normal hexane is adopted; Wherein, in the mixed solution of tetraethoxy and dehydrated alcohol, tetraethoxy accounts for 70 ~ 80% of the volume of the mixed solution of tetraethoxy and dehydrated alcohol.
8. the employing constant pressure and dry according to claim 1 or 7 prepares grade SiO
2the method of airsetting glueballs, is characterized in that, described step 6) in gel ball is carried out repeatedly ageing, burin-in process after, adopt normal hexane cleaning gel ball after carry out modification again.
9. employing constant pressure and dry according to claim 1 prepares grade SiO
2the method of airsetting glueballs, is characterized in that, described step 7) in cleaning adopt normal hexane carry out.
10. the employing constant pressure and dry according to claim 1 or 9 prepares grade SiO
2the method of airsetting glueballs, is characterized in that, described step 7) in drying carry out in 30 ~ 40 DEG C at ambient pressure.
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| CN201510282789.9A CN104891510A (en) | 2015-05-28 | 2015-05-28 | Method for preparing millimeter SiO2 aerogel ball by drying under normal pressure |
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| CN105600789A (en) * | 2015-12-28 | 2016-05-25 | 南京众力盛强新材料科技有限公司 | Millimeter-scale porous silica ball and preparation method thereof |
| CN106467304A (en) * | 2016-08-29 | 2017-03-01 | 长春工业大学 | A kind of silica aerosil microballoon and preparation method thereof |
| CN106517219A (en) * | 2015-12-02 | 2017-03-22 | 苏州同玄新材料有限公司 | Aerogel ball and preparation method thereof |
| CN108975342A (en) * | 2018-08-31 | 2018-12-11 | 武汉理工大学 | A method of aerosil ball is continuously prepared using vibration hydrophobic surface |
| CN116393052A (en) * | 2023-03-31 | 2023-07-07 | 广东埃力生科技股份有限公司 | Aerogel product, and preparation method and preparation system thereof |
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| CN106517219A (en) * | 2015-12-02 | 2017-03-22 | 苏州同玄新材料有限公司 | Aerogel ball and preparation method thereof |
| CN106517219B (en) * | 2015-12-02 | 2019-02-12 | 苏州同玄新材料有限公司 | Airsetting glueballs and preparation method thereof |
| CN105600789A (en) * | 2015-12-28 | 2016-05-25 | 南京众力盛强新材料科技有限公司 | Millimeter-scale porous silica ball and preparation method thereof |
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