CN117819580A - High-temperature-resistant alumina aerogel and preparation method thereof - Google Patents
High-temperature-resistant alumina aerogel and preparation method thereof Download PDFInfo
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- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 title claims abstract description 207
- 239000004964 aerogel Substances 0.000 title claims abstract description 87
- 238000002360 preparation method Methods 0.000 title claims abstract description 23
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims abstract description 56
- 239000007787 solid Substances 0.000 claims abstract description 48
- 239000002904 solvent Substances 0.000 claims abstract description 34
- RMAQACBXLXPBSY-UHFFFAOYSA-N silicic acid Chemical compound O[Si](O)(O)O RMAQACBXLXPBSY-UHFFFAOYSA-N 0.000 claims abstract description 33
- 238000000034 method Methods 0.000 claims abstract description 32
- 238000003756 stirring Methods 0.000 claims abstract description 24
- 238000000352 supercritical drying Methods 0.000 claims abstract description 20
- 230000032683 aging Effects 0.000 claims abstract description 19
- 230000008569 process Effects 0.000 claims abstract description 17
- 238000006068 polycondensation reaction Methods 0.000 claims abstract description 14
- 239000003999 initiator Substances 0.000 claims abstract description 11
- 238000002156 mixing Methods 0.000 claims abstract description 9
- 238000001879 gelation Methods 0.000 claims abstract description 8
- 239000003054 catalyst Substances 0.000 claims abstract description 7
- 239000002245 particle Substances 0.000 claims description 44
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 33
- 229910052782 aluminium Inorganic materials 0.000 claims description 13
- 239000000377 silicon dioxide Substances 0.000 claims description 13
- 238000005245 sintering Methods 0.000 claims description 12
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 9
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical group [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 claims description 8
- 235000011114 ammonium hydroxide Nutrition 0.000 claims description 8
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims description 6
- BFNBIHQBYMNNAN-UHFFFAOYSA-N ammonium sulfate Chemical compound N.N.OS(O)(=O)=O BFNBIHQBYMNNAN-UHFFFAOYSA-N 0.000 claims description 6
- 229910052921 ammonium sulfate Inorganic materials 0.000 claims description 6
- 235000011130 ammonium sulphate Nutrition 0.000 claims description 6
- 229910052710 silicon Inorganic materials 0.000 claims description 5
- 239000010703 silicon Substances 0.000 claims description 5
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 claims description 4
- LRHPLDYGYMQRHN-UHFFFAOYSA-N N-Butanol Chemical compound CCCCO LRHPLDYGYMQRHN-UHFFFAOYSA-N 0.000 claims description 4
- BTANRVKWQNVYAZ-UHFFFAOYSA-N butan-2-ol Chemical compound CCC(C)O BTANRVKWQNVYAZ-UHFFFAOYSA-N 0.000 claims description 4
- BDERNNFJNOPAEC-UHFFFAOYSA-N propan-1-ol Chemical compound CCCO BDERNNFJNOPAEC-UHFFFAOYSA-N 0.000 claims description 4
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 claims description 3
- 239000004202 carbamide Substances 0.000 claims description 3
- 238000009792 diffusion process Methods 0.000 claims description 3
- PAWQVTBBRAZDMG-UHFFFAOYSA-N 2-(3-bromo-2-fluorophenyl)acetic acid Chemical compound OC(=O)CC1=CC=CC(Br)=C1F PAWQVTBBRAZDMG-UHFFFAOYSA-N 0.000 claims description 2
- PQUCIEFHOVEZAU-UHFFFAOYSA-N Diammonium sulfite Chemical compound [NH4+].[NH4+].[O-]S([O-])=O PQUCIEFHOVEZAU-UHFFFAOYSA-N 0.000 claims description 2
- 239000011148 porous material Substances 0.000 abstract description 14
- 239000002994 raw material Substances 0.000 abstract description 11
- 239000000499 gel Substances 0.000 description 43
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 13
- 238000003917 TEM image Methods 0.000 description 8
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 6
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 6
- 230000000903 blocking effect Effects 0.000 description 5
- 238000001816 cooling Methods 0.000 description 5
- 239000002243 precursor Substances 0.000 description 5
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 4
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 4
- -1 aluminum alkoxides Chemical class 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 238000007789 sealing Methods 0.000 description 4
- 229910021529 ammonia Inorganic materials 0.000 description 3
- 238000001035 drying Methods 0.000 description 3
- 238000010438 heat treatment Methods 0.000 description 3
- 230000006872 improvement Effects 0.000 description 3
- 230000014759 maintenance of location Effects 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
- 238000012986 modification Methods 0.000 description 3
- 229910052814 silicon oxide Inorganic materials 0.000 description 3
- AZDRQVAHHNSJOQ-UHFFFAOYSA-N alumane Chemical class [AlH3] AZDRQVAHHNSJOQ-UHFFFAOYSA-N 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 230000001276 controlling effect Effects 0.000 description 2
- 239000012046 mixed solvent Substances 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- 238000003980 solgel method Methods 0.000 description 2
- 230000009466 transformation Effects 0.000 description 2
- WOZZOSDBXABUFO-UHFFFAOYSA-N tri(butan-2-yloxy)alumane Chemical compound [Al+3].CCC(C)[O-].CCC(C)[O-].CCC(C)[O-] WOZZOSDBXABUFO-UHFFFAOYSA-N 0.000 description 2
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
- BOTDANWDWHJENH-UHFFFAOYSA-N Tetraethyl orthosilicate Chemical compound CCO[Si](OCC)(OCC)OCC BOTDANWDWHJENH-UHFFFAOYSA-N 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- SMZOGRDCAXLAAR-UHFFFAOYSA-N aluminium isopropoxide Chemical compound [Al+3].CC(C)[O-].CC(C)[O-].CC(C)[O-] SMZOGRDCAXLAAR-UHFFFAOYSA-N 0.000 description 1
- 150000001450 anions Chemical class 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 230000001627 detrimental effect Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000011049 filling Methods 0.000 description 1
- 238000011010 flushing procedure Methods 0.000 description 1
- 239000012774 insulation material Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 239000002105 nanoparticle Substances 0.000 description 1
- 239000007783 nanoporous material Substances 0.000 description 1
- 229910017604 nitric acid Inorganic materials 0.000 description 1
- 231100000252 nontoxic Toxicity 0.000 description 1
- 230000003000 nontoxic effect Effects 0.000 description 1
- 230000006911 nucleation Effects 0.000 description 1
- 238000010899 nucleation Methods 0.000 description 1
- 239000005416 organic matter Substances 0.000 description 1
- 238000004321 preservation Methods 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 230000009257 reactivity Effects 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
- 239000011240 wet gel Substances 0.000 description 1
Abstract
The high temperature resistant alumina aerogel and its preparation process includes adding high solid content alumina hydrosol into alcohol solvent, stirring to prepare alumina sol with alcohol solvent as main solvent component; adding silica sol into the obtained alumina sol, and uniformly mixing to obtain alumina-silica sol; adding an initiator into the obtained alumina-silica sol, stirring uniformly, and adding a catalyst to promote gel polycondensation; placing the obtained alumina-silica sol under high temperature condition for gelation and aging to obtain alumina gel; and carrying out supercritical drying on the alumina gel to obtain the high-temperature-resistant alumina aerogel. The invention uses alumina sol with high solid content as raw material, does not need solvent replacement process, and has simple process and convenient operation. The prepared high-temperature-resistant alumina aerogel still has higher specific surface area and pore volume in a high-temperature environment of 1300-1500 ℃.
Description
Technical Field
The invention mainly relates to the technical field of aerogel materials, in particular to a high-temperature-resistant alumina aerogel and a preparation method thereof.
Background
Alumina aerogel is a high porosity nanoporous material. Compared with the silicon oxide aerogel widely applied at present, the aluminum oxide aerogel has the characteristics of low heat conductivity and high specific surface area, and simultaneously has better temperature resistance, so that the aluminum oxide aerogel has wide application prospect when being used as a heat insulation material, a catalyst carrier and the like at higher temperature.
At present, a common method is to prepare alumina aerogel by utilizing hydrolysis-polycondensation reaction of an aluminum source precursor and adopting a sol-gel method combined with a supercritical drying mode. The commonly used aluminum source precursors are organic aluminum alkoxides and inorganic aluminum salts. According to the scheme of taking organic aluminum alkoxide as an aluminum source precursor, raw materials are high in price, high in reactivity and not easy to prepare stable alumina sol. According to the scheme of taking inorganic aluminum salt as an aluminum source precursor raw material, a large amount of anions and water are contained in sol, and the sol needs to be removed by adopting a repeated solvent replacement process so as to ensure that the surface tension of alumina gel is very low in a supercritical drying process, so that massive alumina aerogel is obtained, and the process is complex and the period is long.
In addition, the typical structure of the existing alumina aerogel is a nano particle unit with small size, the surface activity is high, obvious sintering and phase transformation can occur at the temperature of more than 1000 ℃, the specific surface area (retention rate) is obviously reduced, the pore structure is collapsed, and the performance is degraded. In order to solve this problem, it has been proposed that the heat resistance of alumina aerogel can be improved to 1200 ℃ by incorporating a silicon component therein. However, even so, this approach of incorporating a silicon component into the alumina aerogel can still result in significant particle sintering and collapse of the pore structure if at higher temperatures in excess of 1200 ℃. At present, the high temperature resistance of the alumina aerogel prepared according to the preparation scheme disclosed in the art is difficult to break through the higher temperature of the level of 1200 ℃.
Disclosure of Invention
In order to solve the problems of complex preparation process, high preparation cost and easy sintering shrinkage at high temperature of the alumina aerogel in the prior art, the invention provides the high-temperature-resistant alumina aerogel and the preparation method thereof, and the prepared high-temperature-resistant alumina aerogel still has higher specific surface area and pore volume in a high-temperature environment of 1300-1500 ℃.
In order to achieve the above purpose, the technical scheme adopted by the invention is as follows:
in one aspect, the invention provides a method for preparing a high temperature resistant alumina aerogel, comprising:
s1, adding high-solid content alumina hydrosol into an alcohol solvent, and uniformly stirring to prepare alumina hydrosol taking the alcohol solvent as a main solvent component, wherein the solid content of the high-solid content alumina hydrosol is 30-50wt% and the particle size of alumina in the high-solid content alumina hydrosol is 20-100 nm;
s2, adding silica sol into the alumina sol obtained in the step S1, and uniformly mixing to obtain alumina-silica sol, wherein the particle size of silica in the silica sol is 20-80 nm, and uniformly mixing, so that the obtained alumina-silica sol forms an isolated phase structure with large-particle-size silica particles uniformly distributed around the large-particle-size alumina particles, and can inhibit contact, atomic diffusion and sintering among the alumina particles;
s3, adding an initiator into the alumina-silica sol obtained in the step S2, uniformly stirring, and adding a catalyst to promote gel polycondensation;
s4, placing the alumina-silica sol obtained in the step S3 under a high temperature condition for gelation and aging to obtain alumina gel;
s5, performing supercritical drying on the alumina gel prepared in the step S4 to obtain the high-temperature-resistant alumina aerogel.
Preferably, the particle size of the alumina in the high solids alumina hydrosol is 50 to 95nm.
Preferably, the silica particle size in the silica sol is 30nm.
On the other hand, the invention provides the high-temperature-resistant alumina aerogel, which is prepared by adopting the preparation method of the high-temperature-resistant alumina aerogel, and the prepared high-temperature-resistant alumina aerogel still has higher specific surface area and pore volume in a high-temperature environment of 1300-1500 ℃.
Compared with the prior art, the invention has the following technical effects:
the preparation process of the method mainly comprises sol preparation, aging and supercritical drying, does not need a solvent replacement process, and is simple in process and convenient to operate. The prepared high-temperature-resistant alumina aerogel still has higher specific surface area and pore volume in a high-temperature environment of 1300-1500 ℃.
The raw materials of the invention adopt the alumina sol of the water system, the raw materials are simple and easy to obtain, the cost is relatively low, the sol preparation process is simpler, more direct and controllable, and the invention is suitable for batch preparation. Compared with the most commonly used organic aluminum alkoxide used as an aluminum source at present, the method can save more than half of raw material cost.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to the structures shown in these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a flow chart of a method for preparing a high temperature resistant alumina aerogel according to one embodiment;
FIG. 2 is a graphical representation of the high temperature resistant alumina aerogel prepared in example 1;
FIG. 3 is a transmission electron micrograph of the high temperature resistant alumina aerogel prepared in example 4 before 1400℃treatment, wherein (a) is a transmission electron micrograph (scale: 50 nm) of the high temperature resistant alumina aerogel prepared in example 4 before 1400℃treatment, and (b) is a transmission electron micrograph (scale: 20 nm) of the high temperature resistant alumina aerogel prepared in example 4 before 1400℃treatment;
FIG. 4 is a transmission electron micrograph of the high temperature resistant alumina aerogel prepared in example 4 after being heat treated at 1400℃for 2 hours, wherein (a) is a transmission electron micrograph (scale: 50 nm) of the high temperature resistant alumina aerogel prepared in example 4 after being heat treated at 1400℃for 2 hours, and (b) is a transmission electron micrograph (scale: 20 nm) of the high temperature resistant alumina aerogel prepared in example 4 after being heat treated at 1400℃for 2 hours.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are only some, but not all embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Referring to fig. 1, an embodiment provides a method for preparing a high temperature resistant alumina aerogel, specifically, the method includes the following steps:
s1, preparing alumina sol;
adding the high-solid content alumina hydrosol into an alcohol solvent, and uniformly stirring to prepare the alumina hydrosol taking the alcohol solvent as a main solvent component, wherein the solid content of the high-solid content alumina hydrosol is 30-50wt%, and the particle size of alumina in the high-solid content alumina hydrosol is 20-100 nm.
S2, preparing alumina-silica sol;
adding silica sol into the alumina sol obtained in the step S1, and uniformly mixing to obtain alumina-silica sol;
s3, gel polycondensation;
adding an initiator into the alumina-silica sol obtained in the step S2, stirring uniformly, and adding catalysts such as ammonia water, urea and the like to promote gel polycondensation;
s4, performing gel and aging to obtain alumina gel;
placing the alumina-silica sol obtained in the step S3 under a high temperature condition for gelation and aging to obtain alumina gel;
s5, performing supercritical drying to obtain high-temperature-resistant alumina aerogel;
and (3) carrying out supercritical drying on the alumina gel prepared in the step (S4) to obtain the high-temperature-resistant alumina aerogel.
In the embodiment, the high-solid-content and large-particle-size water-based alumina sol is adopted as a raw material, and after being diluted by an alcohol solvent (any one of ethanol, isopropanol, n-propanol, sec-butanol, n-butanol and methanol), a modifying component (large-particle-size water-based silica sol) and a catalyst are added to enable the water-based alumina sol to gel, and finally, high-temperature supercritical drying is directly carried out, a solvent replacement process is not needed, the process is simple, the operation is convenient, and the prepared high-temperature-resistant alumina aerogel still has higher specific surface area and pore volume in a high-temperature environment of 1300-1500 ℃.
The alumina sol of the water system has the advantages of simple and easily obtained raw materials, nontoxic raw materials and relatively low cost, the price of the raw materials is about 1/2 to 1/3 of that of the aluminum sec-butoxide, and the aluminum content is 1.5 to 2.5 times of that of the aluminum sec-butoxide. Compared with organic aluminum alkoxide, the aqueous alumina sol has low organic matter content, no byproduct is produced in the sol-gel process, and supercritical drying can be directly carried out after gel, so that a complex solvent replacement process is omitted, and the sol preparation process is simpler, more direct and controllable and is suitable for batch preparation.
According to the invention, in the step S1, alumina hydrosol with large particle size alumina is adopted, the particle size of alumina in the high-solid content alumina hydrosol is 20-100 nm, the size of unit particles in the finally prepared high-temperature-resistant alumina aerogel can be increased, and the surface energy of the particles is reduced, so that sintering and phase transition are not easy to occur at high temperature, the use temperature is greatly increased, and the high-temperature-resistant alumina aerogel has more excellent high-temperature resistance.
On the other hand, in the step S1, the high-solid content alumina hydrosol is added into the alcohol solvent, the solid content of the high-solid content alumina hydrosol is 30-50 wt%, the water content in the alumina hydrosol is obviously reduced, the alcohol solvent content is obviously improved, on one hand, the density of the prepared high-temperature-resistant alumina aerogel can be effectively regulated, on the other hand, the influence of water on the surface tension in the supercritical process is obviously reduced, the process can be simplified under the condition of not replacing water in gel, and the alumina aerogel with good blocking property and pore structure can be obtained by drying. The method does not need a solvent replacement process, shortens the preparation period and saves the production cost.
The alumina with large particle size in the alumina hydrosol with high solid content can ensure that the finally prepared high-temperature-resistant alumina aerogel does not generate structural collapse at high temperature. The larger the alumina particles, the higher the temperature resistance of the aerogel, but the larger the alumina particle size is detrimental to the formation of a stable high solids sol. Therefore, the raw material used in the invention is the alumina hydrosol with high solid content, the solid content is 30-50wt%, and the particle size of the alumina in the alumina hydrosol with high solid content is 20-100 nm.
In the step S2 of the invention, silica sol is added into the alumina sol obtained in the step S1 as a modifying component, and the blocking property of the alumina gel material is improved by introducing the silica sol. For silica sol, the selection of the particle size also has a great influence on the temperature resistance of the finally prepared high-temperature-resistant alumina aerogel. Specifically, if the particle size of the silica in the silica sol is smaller than 20nm, the surface activity of the silica sol is higher, and the improvement of the temperature resistance of the alumina aerogel is not obvious. However, if the silica particle size in the silica sol is more than 80nm, the blocking property and strength of the alumina aerogel are reduced. Therefore, in the invention, in the step S2, the silica particle size of the silica sol added into the alumina sol obtained in the step S1 is 20-80 nm, so that the temperature resistance and the high-temperature specific surface area of the finally prepared alumina aerogel can be obviously improved.
Specifically, in step S2, a large-particle-size silica sol is added to the alumina sol obtained in step S1, and the mixture is uniformly mixed, so that the obtained alumina-silica sol forms a kind of silica solThe large-particle-size silicon oxide particles are uniformly distributed in the isolating phase structure around the large-particle-size aluminum oxide particles, and the two particle units are large in size and have low surface energy, so that the large-particle-size silicon oxide particles are not easy to sinter at high temperature. The large-particle-size silica sol means that the particle size of silica in the silica sol is large, and the particle size of silica in the silica sol is 20-80 nm. The silica particles are uniformly distributed around the alumina particles to play a role of an isolating phase, so that the contact, the atomic diffusion and the sintering among the alumina particles are obviously inhibited, the structure has strong sintering resistance at high temperature, and the structure can keep higher specific surface area, pore volume and good pore structure at high temperature. According to the prior art, the prepared alumina aerogel added with silicon has smaller unit sizes of alumina particles and silica particles, the small-size alumina particles have large specific surface area, sintering and phase transformation are easy to occur when the alumina aerogel is heated so as to reduce self energy, and the sintering activity is still relatively high, so that the alumina aerogel cannot achieve high temperature resistance. The invention adopts large-particle alumina to keep the gel stable in structure under the heated condition. Simultaneously, the neck contact area among alumina grains with large grain size is reduced, and the neck sintering and alpha-Al of the aerogel are reduced 2 O 3 Nucleation probability, the prepared material is not easy to generate sintering phase change to cause collapse of the pore structure. The introduction of the large-particle-diameter silica sol as the modifying component further improves the temperature resistance of the alumina aerogel, and at the same time, can improve the blocking property of the alumina aerogel.
In the step S1, alumina sol of an alcohol/water mixed solvent system which takes alcohol as a main solvent component is prepared, and alumina sol with different contents is prepared by controlling the amount of alcohol added into aqueous alumina sol. In a preferred embodiment, the alcohol solvent used in step S1 is ethanol. In the alumina sol process of the prepared alcohol/water mixed solvent system, the solid content of the alumina sol prepared in the step S1 is controlled by controlling the addition amount of the ethanol, the content of the alumina in the alumina sol is controlled to be 5-25 wt%, and the content of the ethanol is controlled to be 67-90 wt%.
In a preferred embodiment, the modifying component in step S2 is an acidic silica sol, and the ratio of the added silica sol precursor to the alumina sol is controlled so that in the alumina-silica sol prepared in step S2, the preferred scheme is that the molar ratio of aluminum to silicon is controlled to be 1:0.5 to 1:0.125.
in a preferred embodiment, the initiator in step S3 is one or more of ammonium sulfate, ammonium sulfite and ammonium nitrate, and the molar ratio of the initiator to the alumina is (0.0001-0.5): 1, a step of; the concentration of the added ammonia water is 1 to 10 weight percent, and the molar ratio of the ammonia water to the aluminum source is (0.0001 to 0.5): 1. too high a concentration of ammonia will result in a rapid formation of gel due to too high a local concentration of ammonia in the sol during the addition process, and too low a concentration of ammonia will introduce too much water to affect the gelling process.
A preferred embodiment proposes that the gel and aging conditions of step S4 are: the gel aging temperature is 50-160 ℃, and the constant temperature is kept for 24-72 hours. High-temperature aging is carried out within the temperature and time range, so that the gel can be ensured to have better strength and network structure.
In a preferred embodiment, the supercritical drying method in step S5 is as follows: and (3) taking alcohol as a drying medium, pre-filling nitrogen with the pressure of 0.5-4 MPa in an autoclave, heating to a temperature above the supercritical point of the alcohol at the speed of 0.5-2 ℃/min, preserving heat for 2-20 h, slowly releasing pressure at the speed of 30-100 kPa/min, and finally flushing with nitrogen for 15-60 min to obtain the high-temperature-resistant alumina aerogel.
To demonstrate the effectiveness of the present invention, several specific examples of the preparation method of the high temperature resistant alumina aerogel provided by the present invention are provided below, and a comparative example is provided. The method comprises the following steps:
example 1:
the preparation method of the high-temperature-resistant alumina aerogel comprises the following steps:
s1, preparing alumina sol;
adding 20g of high-solid content alumina hydrosol into 30g of ethanol solvent, and uniformly stirring to prepare the alumina hydrosol taking ethanol as a main solvent component, wherein the solid content of the high-solid content alumina hydrosol is 50wt%, and the particle size of alumina in the high-solid content alumina hydrosol is 50nm.
S2, gel polycondensation;
and (2) adding 0.5g of initiator, namely ammonium sulfate, into the alumina sol obtained in the step (S1), uniformly stirring, dropwise adding 5ml of 5% ammonia water solution to promote gel polycondensation, stirring for 5min, and sealing.
S3, performing gel and aging to obtain alumina gel;
and (3) placing the product obtained in the step (S2) under high temperature conditions for gelation and aging, specifically, preserving heat at 80 ℃ for 48 hours in a high temperature furnace, slowly cooling to room temperature, and taking out a sample to obtain the alumina gel.
S4, performing supercritical drying to obtain high-temperature-resistant alumina aerogel;
and (3) carrying out supercritical drying on the alumina gel prepared in the step (S3) to obtain the high-temperature-resistant alumina aerogel.
Referring to fig. 2, fig. 2 is a physical view of the high temperature resistant alumina aerogel prepared in example 1, showing that the alumina aerogel prepared in example 1 has good blocking property and uniformity.
Example 2:
the preparation method of the high-temperature-resistant alumina aerogel comprises the following steps:
s1, preparing alumina sol;
adding 20g of high-solid content alumina hydrosol into 30g of ethanol solvent, and uniformly stirring to prepare the alumina hydrosol taking ethanol as a main solvent component, wherein the solid content of the high-solid content alumina hydrosol is 50wt%, and the particle size of alumina in the high-solid content alumina hydrosol is 50nm.
S2, preparing alumina-silica sol;
and (2) adding 12g of silica sol into the alumina sol obtained in the step (S1), and uniformly mixing to obtain the alumina-silica sol, wherein the solid content of the silica sol is 15wt%, and the particle size of the silica in the silica sol is 30nm.
S3, gel polycondensation;
and (2) adding 0.5g of initiator, namely ammonium sulfate, into the alumina-silica sol obtained in the step (S2), uniformly stirring, then dropwise adding 5ml of 5% ammonia water solution to promote gel polycondensation, stirring for 5min, and sealing.
S4, performing gel and aging to obtain alumina gel;
and (3) placing the alumina-silica sol obtained in the step (S3) under high temperature condition for gelation and aging, specifically, preserving heat for 48 hours at 80 ℃ in a high temperature furnace, slowly cooling to room temperature, and taking out a sample to obtain the alumina gel.
S5, performing supercritical drying to obtain high-temperature-resistant alumina aerogel;
and (3) carrying out supercritical drying on the alumina gel prepared in the step (S4) to obtain the high-temperature-resistant alumina aerogel.
Example 3:
the preparation method of the high-temperature-resistant alumina aerogel comprises the following steps:
s1, preparing alumina sol;
adding 20g of high-solid content alumina hydrosol into 80g of ethanol solvent, and uniformly stirring to prepare the alumina hydrosol taking ethanol as a main solvent component, wherein the solid content of the high-solid content alumina hydrosol is 50wt%, and the particle size of alumina in the high-solid content alumina hydrosol is 50nm.
S2, preparing alumina-silica sol;
and (2) adding 12g of silica sol into the alumina sol obtained in the step (S1), and uniformly mixing to obtain the alumina-silica sol, wherein the solid content of the silica sol is 15wt%, and the particle size of the silica in the silica sol is 30nm.
S3, gel polycondensation;
and (2) adding 0.5g of initiator, namely ammonium sulfate, into the alumina-silica sol obtained in the step (S2), uniformly stirring, then dropwise adding 5ml of 5% ammonia water solution to promote gel polycondensation, stirring for 5min, and sealing.
S4, performing gel and aging to obtain alumina gel;
and (3) placing the alumina-silica sol obtained in the step (S3) under high temperature condition for gelation and aging, specifically, preserving heat for 48 hours at 80 ℃ in a high temperature furnace, slowly cooling to room temperature, and taking out a sample to obtain the alumina gel.
S5, performing supercritical drying to obtain high-temperature-resistant alumina aerogel;
and (3) carrying out supercritical drying on the alumina gel prepared in the step (S4) to obtain the high-temperature-resistant alumina aerogel.
Example 4:
the preparation method of the high-temperature-resistant alumina aerogel comprises the following steps:
s1, preparing alumina sol;
adding 20g of high-solid content alumina hydrosol into 40g of ethanol solvent, and uniformly stirring to prepare the alumina hydrosol taking ethanol as a main solvent component, wherein the solid content of the high-solid content alumina hydrosol is 30wt%, and the particle size of alumina in the high-solid content alumina hydrosol is 95nm.
S2, preparing alumina-silica sol;
and (2) adding 12g of silica sol into the alumina sol obtained in the step (S1), and uniformly mixing to obtain the alumina-silica sol, wherein the solid content of the silica sol is 15wt%, and the particle size of the silica in the silica sol is 30nm.
S3, gel polycondensation;
and (2) adding 0.5g of initiator, namely ammonium sulfate, into the alumina-silica sol obtained in the step (S2), uniformly stirring, then dropwise adding 5ml of 5% ammonia water solution to promote gel polycondensation, stirring for 5min, and sealing.
S4, performing gel and aging to obtain alumina gel;
and (3) placing the alumina-silica sol obtained in the step (S3) under high temperature condition for gelation and aging, specifically, preserving heat for 48 hours at 80 ℃ in a high temperature furnace, slowly cooling to room temperature, and taking out a sample to obtain the alumina gel.
S5, performing supercritical drying to obtain high-temperature-resistant alumina aerogel;
and (3) carrying out supercritical drying on the alumina gel prepared in the step (S4) to obtain the high-temperature-resistant alumina aerogel.
FIG. 3 is a transmission electron micrograph of the high temperature resistant alumina aerogel prepared in example 4 prior to 1400 ℃. FIG. 4 is a transmission electron micrograph of the high temperature resistant alumina aerogel prepared in example 4 after being heat treated at 1400℃for 2 hours. Compared with fig. 3, after the aluminum oxide aerogel is subjected to heat treatment at 1400 ℃ for 2 hours, the skeleton particles of the aluminum oxide aerogel are not obviously sintered and grown, and good nanoscale morphology and nano pore structure are still maintained, so that the aluminum oxide aerogel has excellent high temperature resistance.
Comparative example 1:
40g of aluminum isopropoxide was added to 160g of water with rapid stirring, and 1.2ml of nitric acid solution was added to the above sol with rapid stirring, and the temperature was raised to 150℃and constant for 4 hours. After cooling, adding 1.8g of urea into the sol, stirring uniformly, adding 6g of ethyl orthosilicate, stirring uniformly, and then transferring to a high-temperature furnace for heat preservation at 80 ℃ for 12 hours. And placing the prepared alumina wet gel in an ethanol solution for solvent replacement for 12 hours, repeating for 4 times, taking out a sample, and drying by a supercritical drying method to obtain the silicon-doped alumina aerogel block material.
The following table compares the specific surface area and pore volume retention of alumina aerogels prepared at different heat treatment temperatures:
as can be seen from the table, the high-temperature-resistant alumina aerogel prepared by the method still has higher specific surface area and pore volume in a high-temperature environment of 1300-1500 ℃. In example 1, alumina sol with solid content of 50wt% and alumina particle size of 50nm was selected, silica sol was not added, and specific surface area of the prepared aerogel was lower and temperature resistance was worse than that of examples 2 and 3 in which silica sol was added. Example 2 has a higher solids content and better temperature resistance than the alumina sol of example 3. Meanwhile, in the embodiment 4, alumina sol with solid content of 30wt% and alumina grain size of 95nm is selected, and the alumina sol has better temperature resistance due to the larger alumina grain size and the influence of the silica grains, and still has higher specific surface area retention rate in a high-temperature environment of 1300-1500 ℃ under a high-temperature environment of over 1200 ℃.
The invention is not a matter of the known technology.
The technical features of the above embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.
The above examples merely represent a few embodiments of the present application, which are described in more detail and are not to be construed as limiting the scope of the invention. It should be noted that it would be apparent to those skilled in the art that various modifications and improvements could be made without departing from the spirit of the present application, which would be within the scope of the present application. Accordingly, the scope of protection of the present application is to be determined by the claims appended hereto.
The above description is only of the preferred embodiments of the present invention and is not intended to limit the present invention, but various modifications and variations can be made to the present invention by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (5)
1. The preparation method of the high-temperature-resistant alumina aerogel is characterized by comprising the following steps of:
s1, adding high-solid content alumina hydrosol into an alcohol solvent, and uniformly stirring to prepare alumina hydrosol taking the alcohol solvent as a main solvent component, wherein the solid content of the high-solid content alumina hydrosol is 30-50wt% and the particle size of alumina in the high-solid content alumina hydrosol is 50-95 nm; the alcohol solvent is ethanol, the solid content of the alumina sol prepared in the step S1 is controlled by controlling the addition amount of the ethanol in the process of preparing the alumina sol, the content of alumina in the alumina sol is controlled to be 5-25 wt%, and the content of the ethanol is controlled to be 67-90 wt%;
s2, adding silica sol into the alumina sol obtained in the step S1, and uniformly mixing to obtain alumina-silica sol, wherein the particle size of silica in the silica sol is 30nm, and uniformly mixing, so that the obtained alumina-silica sol forms an isolated phase structure with large-particle-size silica particles uniformly distributed around the large-particle-size alumina particles, and the contact, atomic diffusion and sintering among the alumina particles can be inhibited; the molar ratio of aluminum to silicon in the alumina-silica sol is controlled to be 1:0.5 to 1:0.125;
s3, adding an initiator into the alumina-silica sol obtained in the step S2, uniformly stirring, and adding a catalyst to promote gel polycondensation;
s4, placing the alumina-silica sol obtained in the step S3 under a high temperature condition for gelation and aging to obtain alumina gel;
s5, performing supercritical drying on the alumina gel prepared in the step S4 to obtain the high-temperature-resistant alumina aerogel.
2. The method for preparing high temperature resistant alumina aerogel according to claim 1, wherein the alcohol solvent in step S1 is any one of ethanol, isopropanol, n-propanol, sec-butanol, n-butanol, and methanol.
3. The method for preparing high temperature resistant alumina aerogel according to claim 1, wherein in step S3, the initiator is one or more of ammonium sulfate, ammonium sulfite and ammonium nitrate, and the catalyst is ammonia water or urea.
4. The method of preparing a high temperature alumina aerogel according to claim 1 or claim 2 or claim 3, wherein the gel and aging conditions of step S4 are: the gel aging temperature is 50-160 ℃, and the constant temperature is kept for 24-72 hours.
5. The high-temperature-resistant alumina aerogel is characterized in that the high-temperature-resistant alumina aerogel is prepared by the preparation method of the high-temperature-resistant alumina aerogel according to claim 1.
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Citations (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1999064354A1 (en) * | 1998-06-12 | 1999-12-16 | Asahi Glass Company Ltd. | Silica-alumina composite sol, processes for producing the same, and recording medium |
| CN101792299A (en) * | 2010-01-08 | 2010-08-04 | 中国人民解放军国防科学技术大学 | Method for preparing heat-resisting alumina-silox aerogel thermal-protective composite material |
| CN102503508A (en) * | 2011-10-27 | 2012-06-20 | 中钢集团洛阳耐火材料研究院有限公司 | Method for preparing alumina nanometer porous thermal insulation materials |
| CN105801156A (en) * | 2016-02-19 | 2016-07-27 | 厦门纳美特新材料科技有限公司 | Porous alumina-silicon oxide aerogel balls and quick preparation method thereof |
| CN106809842A (en) * | 2015-11-30 | 2017-06-09 | 航天特种材料及工艺技术研究所 | A kind of preparation method of high temperature oxidation resisting Silica Aerogels |
| CN111943704A (en) * | 2020-08-18 | 2020-11-17 | 航天特种材料及工艺技术研究所 | Reusable high-temperature-resistant nanocrystalline aerogel material and preparation method thereof |
| CN112265998A (en) * | 2020-11-06 | 2021-01-26 | 湖南荣岚智能科技有限公司 | Large-size silica aerogel with ultralow density and low thermal conductivity and preparation method thereof |
| CN113683110A (en) * | 2021-09-14 | 2021-11-23 | 中国人民解放军国防科技大学 | Preparation method of high-temperature-resistant silicon-modified alumina aerogel |
| CN114213142A (en) * | 2022-01-07 | 2022-03-22 | 中国人民解放军国防科技大学 | Preparation method of extruded 3D printed silicon-aluminum oxide ceramic aerogel |
| WO2023239952A1 (en) * | 2022-06-10 | 2023-12-14 | Aspen Aerogels, Inc. | Aluminosilicate aerogels |
Patent Citations (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1999064354A1 (en) * | 1998-06-12 | 1999-12-16 | Asahi Glass Company Ltd. | Silica-alumina composite sol, processes for producing the same, and recording medium |
| CN101792299A (en) * | 2010-01-08 | 2010-08-04 | 中国人民解放军国防科学技术大学 | Method for preparing heat-resisting alumina-silox aerogel thermal-protective composite material |
| CN102503508A (en) * | 2011-10-27 | 2012-06-20 | 中钢集团洛阳耐火材料研究院有限公司 | Method for preparing alumina nanometer porous thermal insulation materials |
| CN106809842A (en) * | 2015-11-30 | 2017-06-09 | 航天特种材料及工艺技术研究所 | A kind of preparation method of high temperature oxidation resisting Silica Aerogels |
| CN105801156A (en) * | 2016-02-19 | 2016-07-27 | 厦门纳美特新材料科技有限公司 | Porous alumina-silicon oxide aerogel balls and quick preparation method thereof |
| CN111943704A (en) * | 2020-08-18 | 2020-11-17 | 航天特种材料及工艺技术研究所 | Reusable high-temperature-resistant nanocrystalline aerogel material and preparation method thereof |
| CN112265998A (en) * | 2020-11-06 | 2021-01-26 | 湖南荣岚智能科技有限公司 | Large-size silica aerogel with ultralow density and low thermal conductivity and preparation method thereof |
| CN113683110A (en) * | 2021-09-14 | 2021-11-23 | 中国人民解放军国防科技大学 | Preparation method of high-temperature-resistant silicon-modified alumina aerogel |
| CN114213142A (en) * | 2022-01-07 | 2022-03-22 | 中国人民解放军国防科技大学 | Preparation method of extruded 3D printed silicon-aluminum oxide ceramic aerogel |
| WO2023239952A1 (en) * | 2022-06-10 | 2023-12-14 | Aspen Aerogels, Inc. | Aluminosilicate aerogels |
Non-Patent Citations (1)
| Title |
|---|
| 张恩爽;黄红岩;刘韬;贺丽娟;郭慧;李文静;张凡;杨洁颖;张昊;赵英民;: "结构强健的Al_2O_3-SiO_2气凝胶的制备及可重复使用性能", 高等学校化学学报, no. 12, 10 December 2019 (2019-12-10) * |
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