CN105727851A - Supercritical drying method of silicon-aluminium composite aerogel - Google Patents

Supercritical drying method of silicon-aluminium composite aerogel Download PDF

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Publication number
CN105727851A
CN105727851A CN201610066224.1A CN201610066224A CN105727851A CN 105727851 A CN105727851 A CN 105727851A CN 201610066224 A CN201610066224 A CN 201610066224A CN 105727851 A CN105727851 A CN 105727851A
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supercritical
composite aerogel
sial
drying method
solvent
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杨卓舒
纪勇
孟宪娴
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Zhuoda New Material Technology Group Co Ltd
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Zhuoda New Material Technology Group Co Ltd
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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01JCHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J13/00Colloid chemistry, e.g. the production of colloidal materials or their solutions, not otherwise provided for; Making microcapsules or microballoons
    • B01J13/0091Preparation of aerogels, e.g. xerogels

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  • Organic Chemistry (AREA)
  • Dispersion Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Silicon Compounds (AREA)

Abstract

The invention provides a supercritical drying method of silicon-aluminium composite aerogel. The method is characterized by firstly carrying out solvent exchange and hydrophobic modification on wet gel, then putting hydrophobically modified wet gel in a high pressure reactor, pouring a supercritical medium, setting the heating temperature, carrying out heating and carrying out outgassing or reflux after the medium in the reactor is in a supercritical state to bring out a solvent in wet gel until the solvent is completely recovered, wherein the supercritical medium is an acetonitrile, ethanol or carbon dioxide solvent. The supercritical drying method provided by the invention has the excellent effects that the product produced by the method has high yield and high production efficiency, dusts slightly and can undergo industrial scaling up; the supercritical drying method can be integrated onto assembly lines; the whole preparation method is simple and easy to control, avoids strong acid and alkali corrosion, has low requirements for equipment and is suitable for industrial production after scaling up.

Description

A kind of supercritical drying drying method of sial composite aerogel
Technical field
The present invention relates to a kind of supercritical drying drying method, be specifically related to the supercritical drying drying method of a kind of sial composite aerogel.
Background technology
Aeroge is the material that in solid matter, heat conductivity is minimum, is only slightly higher than vacuum, is approximately 0.013W/m K.Aeroge also has extremely low density, is the minimum solid of the density generally acknowledged in the world, and least density can accomplish 3kg/m3, more slightly higher than the density of air.Therefore aeroge is the insulation material that heat insulation effect is best in the world, density is minimum.
The kind of current aeroge is more, has carbon aerogels, silicon system aeroge, alumina aerogels etc..The preparing raw material and can adopt tetraethyl orthosilicate or sodium silicate of silica aerogel, preparation method can be respectively adopted non-pressure process and supercritical, and its preparation method is highly developed.The preparation of alumina aerogels, mainly alkoxide process, drying means adopts supercritical process substantially.And the preparation of silica/alumina composite aerogel, rarely having report, even if being prepared into pluralgel, being also adopt alkoxide process to carry out gel.
Inorganic salt method prepares the method for sial composite aerogel, rarely has report, and at present major part aeroge composition is one pack system, for instance silica aerogel is mainly silicon dioxide, aluminum aeroge be mainly composed of aluminium oxide.The raw material of silica aerogel has two kinds, and one is tetraethyl orthosilicate, and one is waterglass, and two kinds of raw materials have different sol-gel process for preparing.The raw material major part that alumina aerogels adopts is aluminium-alcohol salt, adopts supercritical process.Therefore, the raw material production cost that tradition prepares alumina aerogels is expensive, and gel process is complicated;If what traditional alumina aerogels preparation adopted is tetraethyl orthosilicate, sol-gel process is also intended to the hydrolysis through raw material and polycondensation, and preparation method is more complicated.
The constant pressure and dry techniques that adopt at present, but the product dry linting that constant pressure and dry produces, product appearance is poor more.
Summary of the invention
In order to obtain quality and the good composite aerogel of condition, the present invention proposes the supercritical drying drying method of sial composite aerogel.
In order to achieve the above object, the invention provides employing following technical proposals:
A kind of supercritical drying drying method of sial composite aerogel, first wet gel is carried out solvent displacement and hydrophobically modified, then the wet gel that hydrophobically modified is good is put into autoclave, pour supercritical medium into, set heating-up temperature, be heated, after the medium state of reactor reaches supercritical, carry out exitting or refluxing, the solvent in wet gel is taken out of, until solvent recovery is complete;Described supercritical medium is acetonitrile, ethanol or carbon dioxide solvent.
First preferred version of the supercritical drying drying method of a kind of sial composite aerogel, the setting heating-up temperature of supercritical drying drying method is higher than the temperature of the super critical point of medium 5~10 DEG C, the high 0.5~2MPa of pressure.
A kind of second preferred version of the supercritical drying drying method of sial composite aerogel, purely inorganic salt method is prepared sial composite aerogel and is comprised the following steps:
(1) first configure the sodium aluminate solution of certain mass concentration, stir to complete hydrolysis;
(2) when stirring, adding the sodium aluminate solution in step (1), continue stirring 1~2min mix homogeneously in the water glass solution after diluted, room temperature stands 5~30min, obtains sial complex sol;
(3) granule becoming diameter to be 2~3cm the sial complex sol Manual pulverizing obtained, deionized water cleans repeatedly, obtains sial compound wet gel;
(4) carrying out solvent displacement, sial complex sol step (3) obtained immerses alcoholic solution, and through insulation, solvent is replaced, modified, namely obtains sial composite aerogel after drying.
A kind of 3rd preferred version of the supercritical drying drying method of sial composite aerogel, the preparation method of waterglass is as follows:
1) magnetic bead in magnetic separation separation of fine coal ash;
2) mechanical grinding;
3) acidleach: at 150 DEG C~220 DEG C, mixes flyash with the sulphuric acid that concentration is 80%~98% with the ratio that solid-to-liquid ratio is 2:1~1:1 of sulphuric acid in flyash, reacts 4~6h;
4) solid-liquid separation: after reactant is cooled to room temperature, it is that 1:2~1:6 preparation adds water by the solid-to-liquid ratio of flyash Yu water, at 75~95 DEG C, after stirring 1~3h, sucking filtration, the filter cake water washing that solid-to-liquid ratio is 2:1~1:2 by flyash Yu water, obtains the solution of iron sulfate and aluminum sulfate and high silicon acid leaching residue;
5) acid leaching residue prepares waterglass: by acid leaching residue and 9%~12% soda lye by the proportions mixed liquor that solid-to-liquid ratio is 1:1~1:2, heat after 6~10h in reactor at 160~200 DEG C, be cooled to room temperature, filter and wash solid slag with water.
4th preferred version of the supercritical drying drying method of a kind of sial composite aerogel, the light transmittance of sial compound wet gel is more than 80%.
5th preferred version of the supercritical drying drying method of a kind of sial composite aerogel, solvent displacement adopts ethanol, and hexane equal solvent, described holding temperature is 50~70 DEG C, and described solvent time swap is more than 8 hours.
6th preferred version of the supercritical drying drying method of a kind of sial composite aerogel, modified raw material adopts siloxanyl modified liquid, and modification temperature is 50~70 DEG C, and modification time is 7~9h.
7th preferred version of the supercritical drying drying method of a kind of sial composite aerogel, the heat conductivity of sial composite aerogel is 0.02~0.024W/ (m K), and density is 120~300kg/m3, and water absorption rate is less than 3%.
8th preferred version of the supercritical drying drying method of a kind of sial composite aerogel, sial composite aerogel is the fire prevention of A level, and refractory temperature is higher than 650 DEG C.
Compared with immediate prior art, technical scheme provided by the invention has following excellent effect:
1. the invention provides the simple process of a kind of supercritical drying drying method using two kinds of alkaline, inorganic salts to prepare sial composite aerogel;
2. the invention provides the product that supercritical drying drying method produces, product yield is high, and production efficiency is high, and product dry linting is slight, it is possible to carry out industrialization amplification;
3. supercritical drying drying method can be integrated to streamline, it is simple to industrialized production;
4. the raw material of the present invention is sodium metaaluminate and waterglass, and raw materials for production are cheap;
5. the gel method of the present invention be carry out mixture by two kinds of materials after, carry out gel reaction, it is to avoid the complicated approach of other aeroge collosol and gel;
6. whole preparation method is simple and easy to control, corrodes without strong acid and strong base, low for equipment requirements, after method is amplified, is suitable for industrialized production.
Detailed description of the invention
It is described in further detail below in conjunction with specific embodiment, technical scheme is clearly and completely described, it is clear that described embodiment is only a part of embodiment of the present invention, rather than whole embodiments.Based on the embodiment in the present invention, the every other embodiment that those of ordinary skill in the art obtain under not making creative work premise, broadly fall into the scope of protection of the invention.
Inorganic salt method prepares the process of sial composite aerogel:
First configuring the sodium aluminate solution of certain mass concentration, stirring, until sodium metaaluminate complete hydrolysis;Then, by the requirement of waterglass dilution process proportioning;When stirring, in the water glass solution after diluted, add the sodium aluminate solution of required amount, after continuing stirring 1~2min, it is ensured that when solution mix homogeneously, stop stirring, stand 5~30min, obtain sial complex sol.
Before solvent replacement process, in order to accelerate solvent replacing velocity, aeroge is crushed, the granule becoming diameter to be 2~3cm the sial complex sol Manual pulverizing obtained, clean water for several times, until the wet colloidal sol of gained sial compound is alkalescence on the weak side, obtains sial compound wet gel.Then, carrying out solvent displacement, the sial compound wet gel obtained is immersed alcoholic solution, is incubated 50~70 DEG C, solvent time swap is more than 8h.After solvent has been replaced, adopting siloxanyl modified liquid to be modified, modification temperature is 50~70 DEG C, and modification time is 7~9h.Finally, the wet gel that hydrophobically modified is good is put into autoclave, pour supercritical medium into, set heating-up temperature, be heated, until the super critical condition of medium.After the medium state of reactor reaches supercritical, carry out exitting or refluxing, the solvent in gel is taken out of, until solvent recovery is complete, obtain sial composite aerogel granule.
The sodium aluminate solution of configuration, it is necessary to all dissolve, it is not possible to have impurity, solution requires transparent limpid, and sodium aluminate solution requires matching while using, can not long storage time;Waterglass is in the process of dilution, after adding a certain amount of deionized water, and more than magnetic agitation 5min, it is ensured that dilute solution mix homogeneously.
Postcritical medium can adopt acetonitrile, ethanol or carbon dioxide solvent, and the supercritical temperature of acetonitrile is 274.7 DEG C, supercritical pressure 4.83MPa;The supercritical temperature of ethanol is 243 DEG C, supercritical pressure 6.7MPa;The supercritical temperature of carbon dioxide is 31.1 DEG C, and supercritical pressure is 7.29MPa;The temperature requirement of critical drying process is higher than the temperature of the super critical point of medium 5~10 DEG C, the high 0.5~2MPa of pressure, to guarantee that superfluid dries the protected effect to sample.
The preparation of waterglass: flyash is through 4 magnetic separation, then through mechanical grinding, mill speed is 1200r/min, the fine powder powder obtained after pulverizing 4min, then with 82% sulphuric acid mix by solid-to-liquid ratio 5:4, and at 200 DEG C react 4h;Reaction end is that 1:3 adds water by the solid-to-liquid ratio of flyash Yu water, is heated to 90 DEG C after being cooled to room temperature, stirs 2h, after sucking filtration obtains filter cake, and is that 1:1 washs by the solid-to-liquid ratio of flyash Yu water, obtains the solution of iron sulfate and aluminum sulfate and high silicon acid leaching residue;By the solid-to-liquid ratio of acid leaching residue Yu solution be 1:1 add concentration be the soda lye of 10.5%, and put into autoclave heat 10h, reaction temperature 180 DEG C;After being cooled to room temperature, filter and with a small amount of water washing solid slag, obtain waterglass.
The properties of product test will prepared under different technology conditions, is shown in following table.
Method parameter in each embodiment of table 1 and performance
Above example is only limited in order to technical scheme to be described; those of ordinary skill in the field are to be understood that; the specific embodiment of the present invention can being modified with reference to above-described embodiment or equivalent replacement, these are all being applied within the claims awaited the reply without departing from any amendment or equivalent replacement of spirit and scope of the invention.

Claims (9)

1. the supercritical drying drying method of a sial composite aerogel, it is characterised in that the wet gel of solvent displacement and hydrophobically modified is put into autoclave, pour supercritical medium into, setting heating-up temperature heats, and after the medium state of reactor reaches supercritical, carries out exitting or refluxing;Described supercritical medium is acetonitrile, ethanol or carbon dioxide solvent.
2. the supercritical drying drying method of a kind of sial composite aerogel according to claim 1, it is characterised in that the setting heating-up temperature of described supercritical drying drying method is higher than the temperature of the super critical point of medium 5~10 DEG C, the high 0.5~2MPa of pressure.
3. the supercritical drying drying method of a kind of sial composite aerogel according to claim 1, it is characterised in that described sial composite aerogel comprises the following steps:
(1) preparation sodium metaaluminate aqueous solution;
(2) prepare sial complex sol: under stirring, add in water glass solution preparation in step (1) sodium aluminate solution, after stirring mixing 1~2min, room temperature stands 5~30min;
(3) preparing the sial complex sol granule that diameter is 2~3cm, deionized water cleans repeatedly, obtains sial compound wet gel;
(4) solvent displacement: sial complex sol step (3) obtained immerses alcoholic solution, through insulation, solvent is replaced, modified, namely obtains sial composite aerogel after drying.
4. the supercritical drying drying method of a kind of sial composite aerogel according to claim 3, it is characterised in that the preparation method of described waterglass is as follows:
1) magnetic bead in magnetic separation separation of fine coal ash;
2) mechanical grinding;
3) acidleach: at 150 DEG C~220 DEG C, mixes flyash with the sulphuric acid that concentration is 80%~98% with the ratio that solid-to-liquid ratio is 2:1~1:1 of sulphuric acid in flyash, reacts 4~6h;
4) solid-liquid separation: after reactant is cooled to room temperature, it is that 1:2~1:6 preparation adds water by the solid-to-liquid ratio of flyash Yu water, at 75~95 DEG C, after stirring 1~3h, sucking filtration, the filter cake water washing that solid-to-liquid ratio is 2:1~1:2 by flyash Yu water, obtains the solution of iron sulfate and aluminum sulfate and high silicon acid leaching residue;
5) acid leaching residue prepares waterglass: by acid leaching residue and 9%~12% soda lye by the proportions mixed liquor that solid-to-liquid ratio is 1:1~1:2, heat after 6~10h in reactor at 160~200 DEG C, be cooled to room temperature, filter and wash solid slag with water.
5. the supercritical drying drying method of a kind of sial composite aerogel according to claim 3, it is characterised in that the light transmittance of described sial compound wet gel is more than 80%.
6. the supercritical drying drying method of a kind of sial composite aerogel according to claim 3, it is characterised in that the displacement of described solvent adopts ethanol, and hexane equal solvent, described holding temperature is 50~70 DEG C, and described solvent time swap is more than 8 hours.
7. the supercritical drying drying method of a kind of sial composite aerogel according to claim 3, it is characterised in that described modified raw material adopts siloxanyl modified liquid, and modification temperature is 50~70 DEG C, and modification time is 7~9h.
8. the supercritical drying drying method of a kind of sial composite aerogel according to claim 3, it is characterised in that the heat conductivity of described sial composite aerogel is 0.02~0.024W/ (m K), and density is 120~300kg/m3, water absorption rate is less than 3%.
9. the supercritical drying drying method of a kind of sial composite aerogel according to claim 3, it is characterised in that described sial composite aerogel is the fire prevention of A level, and refractory temperature is higher than 650 DEG C.
CN201610066224.1A 2016-01-29 2016-01-29 Supercritical drying method of silicon-aluminium composite aerogel Pending CN105727851A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108786673A (en) * 2018-06-05 2018-11-13 浙江大学 A kind of preparation method of nickel phosphate/nanogold particle composite aerogel

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CN101698592A (en) * 2009-11-13 2010-04-28 航天特种材料及工艺技术研究所 Silicon-aluminium aerogel composite material and manufacturing method thereof
CN101717214A (en) * 2009-11-26 2010-06-02 西南科技大学 Method for preparing silicon-aluminum aerogel by using fly ash as raw material through normal pressure drying
CN101993087A (en) * 2010-11-29 2011-03-30 中煤平朔煤业有限责任公司 Method for preparing water glass by using fly ash
CN104495899A (en) * 2014-11-30 2015-04-08 湖南科技大学 Method for synergic resource utilization of acetylene sludge and coal ash
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CN1562753A (en) * 2004-03-25 2005-01-12 浙江大学 Method for preparing alumina in fire resistant and high specific surface
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CN104495899A (en) * 2014-11-30 2015-04-08 湖南科技大学 Method for synergic resource utilization of acetylene sludge and coal ash
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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108786673A (en) * 2018-06-05 2018-11-13 浙江大学 A kind of preparation method of nickel phosphate/nanogold particle composite aerogel

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