CN113683110A - Preparation method of high-temperature-resistant silicon-modified alumina aerogel - Google Patents

Preparation method of high-temperature-resistant silicon-modified alumina aerogel Download PDF

Info

Publication number
CN113683110A
CN113683110A CN202111073666.6A CN202111073666A CN113683110A CN 113683110 A CN113683110 A CN 113683110A CN 202111073666 A CN202111073666 A CN 202111073666A CN 113683110 A CN113683110 A CN 113683110A
Authority
CN
China
Prior art keywords
temperature
gel
aerogel
alumina
alumina sol
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
CN202111073666.6A
Other languages
Chinese (zh)
Inventor
姜勇刚
彭飞
冯坚
冯军宗
李良军
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
National University of Defense Technology
Original Assignee
National University of Defense Technology
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by National University of Defense Technology filed Critical National University of Defense Technology
Priority to CN202111073666.6A priority Critical patent/CN113683110A/en
Publication of CN113683110A publication Critical patent/CN113683110A/en
Pending legal-status Critical Current

Links

Images

Classifications

    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
    • C01F7/00—Compounds of aluminium
    • C01F7/02—Aluminium oxide; Aluminium hydroxide; Aluminates
    • C01F7/30—Preparation of aluminium oxide or hydroxide by thermal decomposition or by hydrolysis or oxidation of aluminium compounds
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J13/00—Colloid chemistry, e.g. the production of colloidal materials or their solutions, not otherwise provided for; Making microcapsules or microballoons
    • B01J13/0091—Preparation of aerogels, e.g. xerogels
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y40/00—Manufacture or treatment of nanostructures
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
    • C01F7/00—Compounds of aluminium
    • C01F7/02—Aluminium oxide; Aluminium hydroxide; Aluminates
    • C01F7/021—After-treatment of oxides or hydroxides
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/01—Particle morphology depicted by an image
    • C01P2004/04—Particle morphology depicted by an image obtained by TEM, STEM, STM or AFM
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/12—Surface area

Abstract

The invention provides a preparation method of high-temperature-resistant silicon-modified alumina aerogel, which comprises the following steps: s1, adding an aluminum source into deionized water, reacting, and naturally cooling to obtain a hydrolysate; adding acid into the hydrolysate, stirring uniformly, pouring the mixed solution into a high-pressure kettle, stirring, heating, preserving heat, and naturally cooling to obtain alumina sol; s2, adding the heterogeneous element precursor into the alumina sol, heating for reaction, naturally cooling, adding a coagulant, and fully stirring for dissolving to obtain alumina sol containing the heterogeneous element; s3, gelling and aging the sol obtained in the step S2; then soaking the gel in absolute ethyl alcohol at room temperature, and replacing the gel with new absolute ethyl alcohol at preset time intervals to obtain gel; and S4, placing the gel in a supercritical drying kettle, and carrying out critical drying to obtain the high-temperature-resistant silicon-modified alumina aerogel.

Description

Preparation method of high-temperature-resistant silicon-modified alumina aerogel
Technical Field
The invention generally relates to the technical field of aerogel preparation, and particularly relates to a preparation method of high-temperature-resistant silicon-modified alumina aerogel.
Background
Ceramic aerogel is a material with low density, high porosity and high specific surface area which can resist high temperature. Among them, silica aerogel is the most mature aerogel material studied at present, and has been used as a high-temperature heat-insulating material, but its short-term use temperature generally does not exceed 800 ℃. The alumina aerogel still does not generate remarkable sintering and shrinkage at 1000 ℃ and maintains the nano-pore network structure and higher specific surface area (400 m)2And/g) is an aerogel material with outstanding temperature resistance in the aerobic environment at present, and has wide application prospects in the fields of high-temperature heat insulation, catalysis, adsorption and the like.
However, significant sintering and phase changes of alumina aerogel occur above 1000 ℃, with volume shrinkage and collapse of pore structure, and with reduced specific surface area and performance, greatly limiting the application of alumina aerogel at higher temperatures (1100 ℃ and above). In response to this problem, researchers have taken a number of approaches to improve the thermal stability of alumina aerogels.
CN201010106916.7 prepared yttrium-doped alumina aerogel by using aluminum chloride and yttrium chloride as precursors and propylene oxide as coagulant. The introduction of yttrium inhibits sintering and phase transition of the alumina aerogel. After the prepared yttrium-doped alumina aerogel is treated by argon at 1000 and 1200 ℃ for 2 hours, the specific surface areas respectively reach 380 and 146m2/g。
CN201310276044.2 proposes that hydrolysis-polycondensation rate of aluminum alkoxide is controlled by acetone-aniline in-situ water method to obtain uniform alumina gel, aluminum sec-butoxide and ethyl orthosilicate hydrolysate are used for supercritical modification of the alumina gel, hexamethyldisilazane is used for gas phase modification of the alumina aerogel to prepare silicon modified alumina aerogel, the silica modified alumina aerogel is linearly contracted by 5 percent after being treated for 2 hours at 1200 ℃, and the specific surface area reaches 280m2In the case of/g, no alpha phase transition occurred. However, the aniline used in the preparation process has high toxicity, and the supercritical modification process is comparatively highComplex and requires the consumption of large quantities of hydrolysis liquid and drying medium.
Horiuchi et al (Horiuchi, T., et al, mainentance of large surface area of aluminum heated at elongated temperature above 1300 ℃ by prepared silica-containing silica-alumina aerogel. journal of Non-Crystalline Solids,2001.291: p.187-198) prepared silica-doped alumina aerogel, after treatment at 1200, 1300, 1400 ℃ the specific surface area was 150, 80, 40m2And about/g.
Fengguang et Al (Fenggang et Al, silicon content vs. Al)2O3-SiO2The influence of aerogel structure and performance, journal of inorganic chemistry, 2009.25(10): p.1758-1763) adopts aluminum sec-butoxide and ethyl orthosilicate as precursors, adopts ethanol supercritical drying mode to prepare alumina-silica aerogel, and the specific surface area is up to 116m after 1200 ℃ treatment2/g。
Trifu et al (Trifu, R., et al, aluminum silicate analytes with high temperature stability, in Advances in Bioceramics and ports Ceramics II, R.Narayan, et al, Editors.2009, John Wiley&Sons, Inc. Hoboken.p.301-316) uses boehmite sol and ethyl orthosilicate as raw materials, and is subjected to carbon dioxide supercritical drying to prepare alumina-silica aerogel, and after the alumina-silica aerogel is subjected to heat treatment at 1100 and 1300 ℃ for 1h, the specific surface areas of the alumina-silica aerogel are respectively 194.2m2/g、32.3m2/g。
Wu et Al (Wu, X., et Al., Synthesis of novel Al)2O3-SiO2composite aerogel with high specific surface area at exposed temperature using 2016.42: p.874-882) prepared by using aluminum chloride and ethyl orthosilicate as raw materials, wherein the aerogel with the molar ratio of Al to Si of 8:1 has a specific surface area of 120m after being treated at 1200 DEG C2Linear shrinkage was 40% per gram.
In conclusion, the thermal stability of the aerogel can be improved by modifying the alumina aerogel. However, at temperatures above 1200 ℃, the specific surface area of the modified alumina aerogel still decreases significantly, and therefore its thermal stability still needs to be further improved. How to prepare the alumina aerogel with high specific surface area and higher temperature resistance by adopting a simpler process is still a difficult problem.
Disclosure of Invention
The invention aims to provide a preparation method of high-temperature-resistant silicon-modified alumina aerogel, which is characterized in that alumina sol is obtained through high-temperature sealing treatment in the sol preparation process, a proper amount of silicon source precursor is added into the sol, and the silicon-modified alumina aerogel is obtained through ethanol supercritical treatment, so that the preparation process is simple.
The technical scheme of the invention is that the preparation method of the high-temperature-resistant silicon modified alumina aerogel comprises the following steps:
s1, preparing alumina sol: adding an aluminum source into deionized water, reacting, and naturally cooling to obtain a hydrolysate; adding acid into the hydrolysate, uniformly stirring, pouring the mixed solution into a high-pressure kettle, starting stirring, heating, then preserving heat, and naturally cooling to obtain alumina sol;
s2, preparing an alumina sol containing a silicon source precursor: adding a heterogeneous element precursor into the alumina sol, heating for reaction, naturally cooling, adding a coagulant, and fully stirring and dissolving to obtain alumina sol containing heterogeneous elements;
s3, gel aging and replacement: carrying out gelation and aging on alumina sol containing heterogeneous elements; then, soaking the gel in absolute ethyl alcohol at room temperature, and replacing the gel soaking solution with new absolute ethyl alcohol at preset time intervals to obtain gel;
s4, supercritical drying: and (3) placing the gel in a supercritical drying kettle, and carrying out critical drying to obtain the high-temperature-resistant silicon modified alumina aerogel.
According to the method, excessive deionized water is used for fully hydrolyzing the aluminum source, so that the crystallinity of a hydrolysate product is improved, and the content of organic groups in the prepared aerogel is greatly reduced; the size and the appearance of alumina sol particles are regulated and controlled through high-temperature sealing treatment, so that skeleton particles forming the aerogel are rod-shaped (anisotropic) with uniform size, the contact among the particles is reduced, and sintering and phase change are not easy to occur; a proper amount of silicon source precursor is added into the sol, and silicon oxide particles are generated on the surface of the skeleton particles through reaction, so that an isolation effect is achieved among the silicon oxide particles, the sintering of the aerogel is obviously inhibited, and the aerogel still has a high specific surface area at the temperature of more than 1400 ℃; in conclusion, the aerogel obtained by the invention is not easy to sinter and change phase at high temperature, and still has high specific surface area above 1300 ℃.
Further, in step S1, the method includes: the aluminum source is any one of aluminum isopropoxide, aluminum n-propoxide, aluminum sec-butoxide, aluminum n-butoxide and aluminum tert-butoxide; the molar ratio of the deionized water to the aluminum source is (20-80): 1; the acid is any one of nitric acid, hydrochloric acid and acetic acid, and the molar ratio of the acid to the aluminum source is (0.05-0.3): 1.
further, in step S1, the method includes: adding the aluminum source into deionized water at the temperature of 50-95 ℃, and keeping the temperature of 50-95 ℃ for reaction for 1 h; the temperature of the mixed solution heated and insulated in the autoclave is 120-240 ℃, the time of the insulation is 0.5-24 h, and the pressure in the autoclave is 0.1-4 MPa.
And (3) in natural air, placing the hydrolysate in an autoclave, sealing, heating to 120-240 ℃, keeping the temperature for 0.5-24 h, keeping the pressure in the autoclave at 0.1-4 MPa, and increasing the aggregation and growth of sol particles at high temperature, so that the crystallinity is improved, the size of crystal grains is increased, and the temperature and the time are important for controlling the growth of the crystal grains.
Further, in step S2, the method includes: the heterogeneous element precursor is any one or combination of several of ethyl orthosilicate, methyltriethoxysilane, ethyltriethoxysilane, dimethyldiethoxysilane, diethyldiethoxysilane, trimethylethoxysilane, triethylethoxysilane, methyl orthosilicate, methyltrimethoxysilane, ethyltrimethoxysilane, dimethyldimethoxysilane, diethyldimethoxysilane, trimethylmethoxysilane and triethylmethoxysilane; the molar ratio of the silicon source precursor to the aluminum source in the step S1 is (0.05-0.5): 1;
further, in step S2, the method includes: the heating reaction temperature is 40-70 ℃, and the time is 0.5-2 h; the coagulant is any one of urea and hexamethylenetetramine; the molar ratio of the coagulant to the aluminum source in the step S1 is (0.08-0.3): 1.
further, in step S3, the method for gelling and aging the alumina sol containing the foreign element comprises: and standing the alumina sol for 24-72 hours at the temperature of 80-160 ℃.
Further, in the step S3, the absolute ethyl alcohol is ethyl alcohol with a mass fraction of not less than 99.5%, and the gel soak solution is replaced with the absolute ethyl alcohol every 12 hours for 3 to 5 times.
Further, in step S4, the supercritical drying method includes: placing the gel in a supercritical drying kettle, adopting absolute ethyl alcohol with the mass fraction of more than or equal to 99.5% as a drying medium, pre-charging 0.5-2 MPa of nitrogen, heating to the temperature above the supercritical point of the ethanol at the speed of 0.5-2 ℃/min, keeping the temperature for 2-8 h, slowly releasing the pressure at the speed of 30-100 kPa/min, and finally flushing with nitrogen for 15-60 min to obtain the high-temperature resistant massive alumina aerogel.
Drying is carried out in a supercritical mode, so that the surface tension of ethanol in gel pores is zero, and the blocking property and the nano porous structure of the aerogel are ensured.
The invention can achieve the following beneficial effects:
(1) the method has the advantages of easily obtained raw materials, simple and feasible preparation process and capability of realizing batch preparation.
(2) The silicon modified alumina aerogel prepared by the method has high specific surface area and good high temperature resistance: the initial specific surface area of the aerogel can reach 312m2More than g. After the aerogel is treated at high temperature, the aerogel still has very high specific surface area: after being treated for 2 hours at 1200, 1300 and 1400 ℃, the specific surface areas are respectively 226 m, 177 m and 64m2/g。
(3) The particle size, morphology and porous network structure of the silicon modified alumina aerogel obtained by the method are basically unchanged at the high temperature of 1300 ℃, and the silicon modified alumina aerogel still keeps a transition phase alumina crystalline state at the high temperature of 1400 ℃, so that the silicon modified alumina aerogel is beneficial to keeping good heat insulation, catalysis and adsorption performances, and particularly can keep the performance not to be remarkably reduced at the high temperature.
(4) The silica-modified alumina aerogel obtained by the method has good blocking property.
Drawings
These and/or other aspects and advantages of the present invention will become more apparent and more readily appreciated from the following detailed description of the embodiments of the invention, taken in conjunction with the accompanying drawings of which:
FIG. 1 is a flow chart of a process for preparing a silica-modified alumina aerogel according to the present invention;
FIG. 2 is a graph showing the specific surface area of a silica-modified alumina aerogel according to the present invention after heat treatment;
FIG. 3 is a transmission electron micrograph of a silicon-modified alumina aerogel according to the present invention;
FIG. 4 is a transmission electron micrograph of a silicon-modified alumina aerogel according to the present invention after heat treatment at 1300 ℃.
Detailed Description
In order that those skilled in the art will better understand the present invention, the following detailed description of the invention is provided in conjunction with the accompanying drawings and the detailed description of the invention.
Example 1
A high temperature resistant silica modified alumina aerogel, the process flow diagram of which is shown in figure 1, comprises the following steps:
the first step is as follows: uniformly adding aluminum isopropoxide into deionized water at 80 ℃, keeping the temperature of 80 ℃ for reaction for 1h, and naturally cooling to obtain hydrolysate. Adding nitric acid into the hydrolysate, stirring uniformly, pouring the mixed solution into a high-pressure kettle, starting stirring, heating to 200 ℃, preserving heat for 8 hours, and naturally cooling to obtain the alumina sol. The molar ratio of deionized water, nitric acid and aluminum isopropoxide is 40:0.1: 1.
The second step is that: adding ethyl orthosilicate into the alumina sol, heating to 50 ℃, reacting for 1h, naturally cooling, adding urea, and fully stirring and dissolving to obtain the silica-containing alumina sol. The molar ratio of the ethyl orthosilicate to the urea to the aluminum isopropoxide is 0.15:0.15: 1.
Step three, keeping the silica-containing alumina sol at 90 ℃ for 72 hours to gel and age the silica-containing alumina sol; soaking the gel in anhydrous ethanol at room temperature, and replacing the anhydrous ethanol every 12h for 3 times.
And fourthly, placing the gel in a supercritical drying kettle, adopting absolute ethyl alcohol (the mass fraction is more than or equal to 99.5%) as a drying medium, pre-charging 2MPa of nitrogen, heating to the temperature above the supercritical point of the ethyl alcohol at the speed of 1 ℃/minute, keeping the temperature for 8 hours, and slowly releasing the pressure at the speed of 50 kPa/minute to obtain the blocky alumina aerogel.
The specific surface area data of the silica-modified alumina aerogel prepared in this example is shown in FIG. 2, where the initial (after drying) specific surface area of the aerogel is 312m2The specific surface area of the material is still very high after heat treatment at 1200, 1300 and 1400 ℃, and is respectively 226 m, 177 m and 64m2(ii) in terms of/g. The aerogel still remains in the transition alumina and mullite phases at 1400 ℃ and is not converted to dense alpha-Al2O3And (4) phase(s).
Example 2
A high temperature resistant silica modified alumina aerogel, the process flow diagram of which is shown in figure 1, comprises the following steps:
the first step is as follows: and uniformly adding aluminum sec-butoxide into deionized water at 85 ℃, reacting for 1h at 85 ℃, and naturally cooling to obtain hydrolysate. Adding nitric acid into the hydrolysate, stirring uniformly, pouring the mixed solution into a high-pressure kettle, starting stirring, heating to 140 ℃, preserving heat for 1h, and naturally cooling to obtain the alumina sol. The molar ratio of deionized water, nitric acid and aluminum isopropoxide is 40:0.1: 1.
The second step is that: adding ethyl orthosilicate into the alumina sol, heating to 50 ℃, reacting for 1h, naturally cooling, adding urea, and fully stirring and dissolving to obtain the silica-containing alumina sol. The molar ratio of the ethyl orthosilicate to the urea to the aluminum sec-butoxide is 0.15:0.1: 1.
Step three, keeping the silica-containing alumina sol at 90 ℃ for 72 hours to gel and age the silica-containing alumina sol; soaking the gel in anhydrous ethanol at room temperature, and replacing the anhydrous ethanol every 12h for 3 times.
And fourthly, placing the gel in a supercritical drying kettle, adopting absolute ethyl alcohol (the mass fraction is more than or equal to 99.5%) as a drying medium, pre-charging 2MPa of nitrogen, heating to the temperature above the supercritical point of the ethyl alcohol at the speed of 1 ℃/minute, keeping the temperature for 8 hours, and slowly releasing the pressure at the speed of 50 kPa/minute to obtain the blocky alumina aerogel.
The silica-modified alumina aerogel prepared in example 2 has a rod-like particle shape and a length and width dimension of about 15nm as shown in fig. 3, and this anisotropic structure can reduce the number of contact points between particles. The microscopic image of the silica-modified alumina aerogel prepared in this example after treatment at 1300 ℃ is shown in fig. 4, no significant sintering (average particle size less than 35nm) occurred, and the three-dimensional nanoporous structure was maintained. The initial (after drying) specific surface area of the prepared silica-modified alumina aerogel prepared in this example was 357m2(g) still has very high specific surface area after heat treatment at 1200, 1300 and 1400 ℃, and is respectively 165, 92 and 38m2/g。
Example 3
A high temperature resistant silica modified alumina aerogel, the preparation process is:
the first step is as follows: uniformly adding aluminum isopropoxide into deionized water at 80 ℃, keeping the temperature of 80 ℃ for reaction for 1h, and naturally cooling to obtain hydrolysate. Adding hydrochloric acid into the hydrolysate, stirring uniformly, pouring the mixed solution into a high-pressure kettle, starting stirring, heating to 240 ℃, preserving heat for 24 hours, and naturally cooling to obtain the alumina sol. The molar ratio of deionized water, hydrochloric acid and aluminum isopropoxide was 40:0.15: 1.
The second step is that: adding methyl orthosilicate into the alumina sol, heating to 50 ℃, reacting for 1h, naturally cooling, adding urea, and fully stirring and dissolving to obtain the silica-containing alumina sol. The molar ratio of the ethyl orthosilicate to the urea to the aluminum source is 0.15:0.15: 1.
Step three, keeping the silica-containing alumina sol at 90 ℃ for 72 hours to gel and age the silica-containing alumina sol; soaking the gel in anhydrous ethanol at room temperature, and replacing the anhydrous ethanol every 12h for 3 times.
And fourthly, placing the gel in a supercritical drying kettle, adopting absolute ethyl alcohol (the mass fraction is more than or equal to 99.5%) as a drying medium, pre-charging 2MPa of nitrogen, heating to the temperature above the supercritical point of the ethyl alcohol at the speed of 1 ℃/minute, keeping the temperature for 8 hours, and slowly releasing the pressure at the speed of 50 kPa/minute to obtain the blocky alumina aerogel.
The initial (after drying) specific surface area of the silica-modified alumina aerogel prepared in example 3 was 221m2(g) still has very high specific surface areas of 187, 134 and 53m after heat treatment at 1200, 1300 and 1400 DEG C2/g。
Example 4
A high temperature resistant silica modified alumina aerogel, the preparation process is:
the first step is as follows: uniformly adding aluminum isopropoxide into deionized water at 80 ℃, keeping the temperature of 80 ℃ for reaction for 1h, and naturally cooling to obtain hydrolysate. Adding nitric acid into the hydrolysate, stirring uniformly, pouring the mixed solution into a high-pressure kettle, starting stirring, heating to 200 ℃, preserving heat for 8 hours, and naturally cooling to obtain the alumina sol. The molar ratio of deionized water, nitric acid and aluminum isopropoxide is 40:0.1: 1.
The second step is that: adding ethyl orthosilicate into the alumina sol, heating to 50 ℃, reacting for 1h, naturally cooling, adding urea, and fully stirring and dissolving to obtain the silica-containing alumina sol. The molar ratio of the ethyl orthosilicate to the urea to the aluminum isopropoxide is 0.25:0.15: 1.
Step three, keeping the silica-containing alumina sol at 90 ℃ for 72 hours to gel and age the silica-containing alumina sol; soaking the gel in anhydrous ethanol at room temperature, and replacing the anhydrous ethanol every 12h for 5 times.
And fourthly, placing the gel in a supercritical drying kettle, adopting absolute ethyl alcohol (the mass fraction is more than or equal to 99.5%) as a drying medium, pre-charging 2MPa of nitrogen, heating to the temperature above the supercritical point of the ethyl alcohol at the speed of 1 ℃/minute, keeping the temperature for 4 hours, and slowly releasing the pressure at the speed of 50 kPa/minute to obtain the blocky alumina aerogel.
The initial (after drying) specific surface area of the silica-modified alumina aerogel prepared in example 4 was 345m2(g) still has very high specific surface area after heat treatment at 1200, 1300 and 1400 ℃, which is 198, 147 and 59m respectively2/g。
Example 5
A high temperature resistant silica modified alumina aerogel, the preparation process is:
the first step is as follows: uniformly adding aluminum isopropoxide into deionized water at 90 ℃, keeping the temperature of 90 ℃ for reaction for 1 hour, and naturally cooling to obtain hydrolysate. Adding nitric acid into the hydrolysate, stirring uniformly, pouring the mixed solution into a high-pressure kettle, starting stirring, heating to 200 ℃, preserving heat for 8 hours, and naturally cooling to obtain the alumina sol. The molar ratio of deionized water, nitric acid and aluminum isopropoxide is 40:0.1: 1.
The second step is that: adding ethyl triethoxysilane into the alumina sol, heating to 50 ℃, reacting for 1h, naturally cooling, adding hexamethylenetetramine, and fully stirring and dissolving to obtain the silica-containing alumina sol. The molar ratio of the ethyl triethoxysilane to the hexamethylenetetramine to the aluminum isopropoxide is 0.5:0.1: 1.
Step three, keeping the silica-containing alumina sol at 90 ℃ for 72 hours to gel and age the silica-containing alumina sol; soaking the gel in anhydrous ethanol at room temperature, and replacing the anhydrous ethanol every 12h for 3 times.
And fourthly, placing the gel in a supercritical drying kettle, adopting absolute ethyl alcohol (the mass fraction is more than or equal to 99.5%) as a drying medium, pre-charging 2MPa of nitrogen, heating to the temperature above the supercritical point of the ethyl alcohol at the speed of 1 ℃/minute, keeping the temperature for 8 hours, and slowly releasing the pressure at the speed of 50 kPa/minute to obtain the blocky alumina aerogel.
The initial (after drying) specific surface area of the silica-modified alumina aerogel prepared in example 5 was 376m2(g) still has very high specific surface areas of 183 m, 106 m and 43m after heat treatment at 1200 ℃, 1300 ℃ and 1400 DEG C2/g。
Example 6
A high temperature resistant silica modified alumina aerogel, the preparation process is:
the first step is as follows: uniformly adding aluminum isopropoxide into deionized water at 90 ℃, keeping the temperature of 90 ℃ for reaction for 1 hour, and naturally cooling to obtain hydrolysate. Adding nitric acid into the hydrolysate, stirring uniformly, pouring the mixed solution into a high-pressure kettle, starting stirring, heating to 200 ℃, preserving heat for 8 hours, and naturally cooling to obtain the alumina sol. The molar ratio of deionized water, nitric acid and aluminum isopropoxide is 40:0.1: 1.
The second step is that: adding ethyl triethoxysilane into the alumina sol, heating to 50 ℃, reacting for 1h, naturally cooling, adding hexamethylenetetramine, and fully stirring and dissolving to obtain the silica-containing alumina sol. The molar ratio of the ethyl triethoxysilane to the hexamethylenetetramine to the aluminum isopropoxide is 0.05:0.1: 1.
Step three, keeping the silica-containing alumina sol at 90 ℃ for 72 hours to gel and age the silica-containing alumina sol; soaking the gel in anhydrous ethanol at room temperature, and replacing the anhydrous ethanol every 12h for 3 times.
And fourthly, placing the gel in a supercritical drying kettle, adopting absolute ethyl alcohol (the mass fraction is more than or equal to 99.5%) as a drying medium, pre-charging 2MPa of nitrogen, heating to the temperature above the supercritical point of the ethyl alcohol at the speed of 1 ℃/minute, keeping the temperature for 8 hours, and slowly releasing the pressure at the speed of 50 kPa/minute to obtain the blocky alumina aerogel.
The initial (after drying) specific surface area of the silica-modified alumina aerogel prepared in example 6 was 245m2(g) still has very high specific surface areas of 175, 103 and 41m after heat treatment at 1200, 1300 and 1400 DEG C2/g。
Example 7
A high temperature resistant silica modified alumina aerogel, the preparation process is:
the first step is as follows: and uniformly adding the aluminum sec-butoxide into deionized water at the temperature of 80 ℃, keeping the temperature of 80 ℃ for reaction for 1 hour, and naturally cooling to obtain hydrolysate. Adding nitric acid into the hydrolysate, stirring uniformly, pouring the mixed solution into a high-pressure kettle, starting stirring, heating to 120 ℃, preserving heat for 0.5h, and naturally cooling to obtain the alumina sol. The molar ratio of the deionized water, the nitric acid and the secondary aluminum butoxide is 40:0.1: 1.
The second step is that: adding dimethyl diethoxy silane into the alumina sol, heating to 50 ℃, reacting for 1h, naturally cooling, adding urea, and fully stirring and dissolving to obtain the silicon-containing alumina sol. The molar ratio of the dimethyl diethoxysilane to the urea to the aluminum sec-butoxide is 0.15:0.15: 1.
Step three, keeping the silica-containing alumina sol at 90 ℃ for 72 hours to gel and age the silica-containing alumina sol; soaking the gel in anhydrous ethanol at room temperature, and replacing the anhydrous ethanol every 12h for 4 times.
And fourthly, placing the gel in a supercritical drying kettle, adopting absolute ethyl alcohol (the mass fraction is more than or equal to 99.5%) as a drying medium, pre-charging 2MPa of nitrogen, heating to the temperature above the supercritical point of the ethyl alcohol at the speed of 1 ℃/min, keeping the temperature for 2h, and slowly releasing the pressure at the speed of 50 kPa/min to obtain the blocky alumina aerogel.
The initial (after drying) specific surface area of the silica-modified alumina aerogel prepared in example 7 was 332m2The specific surface area of the material is still high after heat treatment at 1200, 1300 and 1400 ℃, and is respectively 148, 71 and 36m2/g。
Example 8
A high temperature resistant silica modified alumina aerogel, the preparation process is:
the first step is as follows: uniformly adding aluminum isopropoxide into deionized water at 80 ℃, keeping the temperature of 80 ℃ for reaction for 1h, and naturally cooling to obtain hydrolysate. Adding nitric acid into the hydrolysate, stirring uniformly, pouring the mixed solution into a high-pressure kettle, starting stirring, heating to 120 ℃, preserving heat for 0.5h, and naturally cooling to obtain the alumina sol. The molar ratio of deionized water, nitric acid and aluminum isopropoxide is 35:0.1: 1.
The second step is that: adding triethyl ethoxy silane into the alumina sol, heating to 60 ℃, reacting for 0.5h, naturally cooling, adding urea, and fully stirring and dissolving to obtain the silica-containing alumina sol. The molar ratio of triethyl ethoxysilane to urea to aluminum isopropoxide was 0.05:0.15: 1.
Step three, keeping the silica-containing alumina sol at 90 ℃ for 72 hours to gel and age the silica-containing alumina sol; soaking the gel in anhydrous ethanol at room temperature, and replacing the anhydrous ethanol every 12h for 3 times.
And fourthly, placing the gel in a supercritical drying kettle, adopting absolute ethyl alcohol (the mass fraction is more than or equal to 99.5%) as a drying medium, pre-charging 2MPa of nitrogen, heating to the temperature above the supercritical point of the ethyl alcohol at the speed of 1 ℃/minute, keeping the temperature for 4 hours, and slowly releasing the pressure at the speed of 50 kPa/minute to obtain the blocky alumina aerogel.
The initial (after drying) specific surface area of the silica-modified alumina aerogel prepared in example 8 was 353m2Per g, at 1200, 1300 and 1400 DEG CAfter heat treatment, the material still has high specific surface areas of 152 m, 68 m and 34m2/g。
Example 9
A high temperature resistant silica modified alumina aerogel, the preparation process is:
the first step is as follows: uniformly adding aluminum isopropoxide into deionized water at 90 ℃, keeping the temperature of 90 ℃ for reaction for 1 hour, and naturally cooling to obtain hydrolysate. Adding nitric acid into the hydrolysate, stirring uniformly, pouring the mixed solution into a high-pressure kettle, starting stirring, heating to 200 ℃, preserving heat for 8 hours, and naturally cooling to obtain the alumina sol. The molar ratio of deionized water, nitric acid and aluminum isopropoxide is 40:0.1: 1.
The second step is that: adding ethyl triethoxysilane into the alumina sol, heating to 50 ℃, reacting for 1h, naturally cooling, adding urea, and fully stirring for dissolving to obtain the silica-containing alumina sol. The molar ratio of the ethyl triethoxysilane to the urea to the aluminum isopropoxide is 0.5:0.1: 1.
Step three, keeping the silica-containing alumina sol at 90 ℃ for 72 hours to gel and age the silica-containing alumina sol; soaking the gel in anhydrous ethanol at room temperature, and replacing the anhydrous ethanol every 12h for 3 times.
And fourthly, placing the gel in a supercritical drying kettle, adopting absolute ethyl alcohol (the mass fraction is more than or equal to 99.5%) as a drying medium, pre-charging 2MPa of nitrogen, heating to the temperature above the supercritical point of the ethyl alcohol at the speed of 1 ℃/minute, keeping the temperature for 8 hours, and slowly releasing the pressure at the speed of 50 kPa/minute to obtain the blocky alumina aerogel.
The initial (after drying) specific surface area of the silica-modified alumina aerogel prepared in example 9 was 389m2(g) still has very high specific surface area after heat treatment at 1200, 1300 and 1400 ℃, and is respectively 144 m, 66 m and 31m2/g。
Having described embodiments of the present invention, the foregoing description is intended to be exemplary, not exhaustive, and not limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims (8)

1. A preparation method of high-temperature-resistant silicon-modified alumina aerogel is characterized by comprising the following steps:
s1, preparing alumina sol: adding an aluminum source into deionized water, reacting, and naturally cooling to obtain a hydrolysate; adding acid into the hydrolysate, stirring uniformly, pouring the mixed solution into a high-pressure kettle, starting stirring, heating, preserving heat, and naturally cooling to obtain alumina sol;
s2, preparing an alumina sol containing a silicon source precursor: adding a heterogeneous element precursor into the alumina sol, heating for reaction, naturally cooling, adding a coagulant, and fully stirring and dissolving to obtain alumina sol containing heterogeneous elements;
s3, gel aging and replacement: carrying out gelation and aging on alumina sol containing heterogeneous elements; then, soaking the gel in absolute ethyl alcohol at room temperature, and replacing the gel soaking solution with new absolute ethyl alcohol at preset time intervals to obtain gel;
s4, supercritical drying: and (3) placing the gel in a supercritical drying kettle, and carrying out critical drying to obtain the high-temperature-resistant silicon modified alumina aerogel.
2. The method of preparing high temperature resistant silica-modified alumina aerogel according to claim 1,
in the step S1:
the aluminum source is any one of aluminum isopropoxide, aluminum n-propoxide, aluminum sec-butoxide, aluminum n-butoxide and aluminum tert-butoxide; the molar ratio of the deionized water to the aluminum source is (20-80): 1;
the acid is any one of nitric acid, hydrochloric acid and acetic acid, and the molar ratio of the acid to the aluminum source is (0.05-0.3): 1.
3. the method for preparing high temperature resistant silica-modified alumina aerogel according to claim 1, wherein in step S1:
adding the aluminum source into deionized water at the temperature of 50-95 ℃, and keeping the temperature of 50-95 ℃ for reaction for 1 h;
the temperature of the mixed solution is 120-240 ℃ in the autoclave, the heat preservation time is 0.5-24 h, and the pressure in the autoclave is 0.1-4 MPa.
4. The method for preparing high temperature resistant silica-modified alumina aerogel according to claim 1, wherein in step S2:
the heterogeneous element precursor is any one or combination of several of ethyl orthosilicate, methyltriethoxysilane, ethyltriethoxysilane, dimethyldiethoxysilane, diethyldiethoxysilane, trimethylethoxysilane, triethylethoxysilane, methyl orthosilicate, methyltrimethoxysilane, ethyltrimethoxysilane, dimethyldimethoxysilane, diethyldimethoxysilane, trimethylmethoxysilane and triethylmethoxysilane; the molar ratio of the silicon source precursor to the aluminum source in the step S1 is (0.05-0.5): 1.
5. the method for preparing high temperature resistant silica-modified alumina aerogel according to claim 1, wherein in step S2:
the heating reaction temperature is 40-70 ℃, and the time is 0.5-2 h;
the coagulant is any one of urea and hexamethylenetetramine; the molar ratio of the coagulant to the aluminum source in the step S1 is (0.08-0.3): 1.
6. the method for preparing refractory silica-modified alumina aerogel according to claim 1, wherein in step S3, the method for gelling and aging the alumina sol containing heterogeneous elements comprises: and standing the alumina sol for 24-72 hours at the temperature of 80-160 ℃.
7. The preparation method of the high temperature resistant silica-modified alumina aerogel according to claim 1, wherein in step S3, the absolute ethyl alcohol is ethyl alcohol with a mass fraction of 99.5% or more, and the gel soaking solution is replaced with the absolute ethyl alcohol every 12 hours for 3-5 times.
8. The method for preparing high temperature resistant silica-modified alumina aerogel according to claim 1, wherein in step S4, the supercritical drying method comprises: placing the gel in a supercritical drying kettle, adopting absolute ethyl alcohol with the mass fraction of more than or equal to 99.5% as a drying medium, pre-charging 0.5-2 MPa of nitrogen, heating to the temperature above the supercritical point of the ethanol at the speed of 0.5-2 ℃/min, keeping the temperature for 2-8 h, slowly releasing the pressure at the speed of 30-100 kPa/min, and finally flushing with nitrogen for 15-60 min to obtain the high-temperature-resistant silicon modified alumina aerogel.
CN202111073666.6A 2021-09-14 2021-09-14 Preparation method of high-temperature-resistant silicon-modified alumina aerogel Pending CN113683110A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202111073666.6A CN113683110A (en) 2021-09-14 2021-09-14 Preparation method of high-temperature-resistant silicon-modified alumina aerogel

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202111073666.6A CN113683110A (en) 2021-09-14 2021-09-14 Preparation method of high-temperature-resistant silicon-modified alumina aerogel

Publications (1)

Publication Number Publication Date
CN113683110A true CN113683110A (en) 2021-11-23

Family

ID=78586238

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202111073666.6A Pending CN113683110A (en) 2021-09-14 2021-09-14 Preparation method of high-temperature-resistant silicon-modified alumina aerogel

Country Status (1)

Country Link
CN (1) CN113683110A (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114602110A (en) * 2022-03-07 2022-06-10 浙江浩泉消防科技有限公司 Fire extinguishing agent and preparation method thereof
CN117819580A (en) * 2024-03-05 2024-04-05 湖南荣岚智能科技有限公司 High-temperature-resistant alumina aerogel and preparation method thereof
CN117819580B (en) * 2024-03-05 2024-05-14 湖南荣岚智能科技有限公司 High-temperature-resistant alumina aerogel and preparation method thereof

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH06218282A (en) * 1993-01-26 1994-08-09 Kurosaki Refract Co Ltd Heat resistant catalyst carrier and production thereof
CN102302917A (en) * 2011-07-18 2012-01-04 南京工业大学 Preparation method of bulk C-Al2O3 composite aerogel
CN108380144A (en) * 2018-03-26 2018-08-10 湖南科技大学 A kind of Al2O3-SiO2The preparation method of composite aerogel
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
CN112456961A (en) * 2020-11-27 2021-03-09 南京龙宇光电材料科技有限公司 Composite aerogel heat insulation material and preparation method and application thereof

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH06218282A (en) * 1993-01-26 1994-08-09 Kurosaki Refract Co Ltd Heat resistant catalyst carrier and production thereof
CN102302917A (en) * 2011-07-18 2012-01-04 南京工业大学 Preparation method of bulk C-Al2O3 composite aerogel
CN108380144A (en) * 2018-03-26 2018-08-10 湖南科技大学 A kind of Al2O3-SiO2The preparation method of composite aerogel
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
CN112456961A (en) * 2020-11-27 2021-03-09 南京龙宇光电材料科技有限公司 Composite aerogel heat insulation material and preparation method and application thereof

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
FEI PENG ET AL.: "A facile method to fabricate monolithic alumina–silica aerogels with high surface areas and good mechanical properties", 《JOURNAL OF THE EUROPEAN CERAMIC SOCIETY》 *
TATSURO HORIUCHI ET AL.: "Maintenance of large surface area of alumina heated at elevated temperatures above 1300℃ by preparing silicacontaining pseudoboehmite aerogel", 《JOURNAL OF NON-CRYSTALLINE SOLIDS》 *
冯坚等: "硅含量对Al2O3-SiO2气凝胶结构和性能的影响", 《无机化学学报》 *

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114602110A (en) * 2022-03-07 2022-06-10 浙江浩泉消防科技有限公司 Fire extinguishing agent and preparation method thereof
CN117819580A (en) * 2024-03-05 2024-04-05 湖南荣岚智能科技有限公司 High-temperature-resistant alumina aerogel and preparation method thereof
CN117819580B (en) * 2024-03-05 2024-05-14 湖南荣岚智能科技有限公司 High-temperature-resistant alumina aerogel and preparation method thereof

Similar Documents

Publication Publication Date Title
CN102276236B (en) High temperature resistant Si-C-O aerogel thermal insulation composite material and preparation method thereof
CN113716572B (en) Preparation method of alumina-silica aerogel composite material
CN110698101B (en) Infrared shielding coating modified fiber reinforced aerogel heat insulation material and preparation method thereof
CN104086200A (en) Preparation method of mullite fiber
KR20120070948A (en) Manufacturing method of hydropobic silica aerogel powder with insulating performance
CN109553395B (en) Low-cost preparation method of ceramic aerogel
CN105780126B (en) A kind of preparation method of the porous mullite formed by generated in-situ whisker overlap joint
CN110745827B (en) Preparation method of two-dimensional flaky SiC material
KR101129375B1 (en) Porous Ceramic Prepared From Sodium Silicate and Aerogel and A Method for Preparing Thereof
CN113683110A (en) Preparation method of high-temperature-resistant silicon-modified alumina aerogel
CN112457037B (en) Performance and application of mullite fiber whisker porous reinforcement reinforced silica aerogel composite material prepared based on liquid phase method
CN110436953B (en) High-temperature-resistant Al-Si-B-O ceramic aerogel material and synthesis method thereof
CN112759388A (en) ZrO preparation by adopting sol-gel method2-SiO2Method for coating binary mixed sol
CN111099596B (en) Simple method for coating high-hydrophobicity boron nitride nanosheet thin layer on surface of silicon dioxide aerogel particle
CN106966744B (en) Carbon fiber reinforced alumina ceramic composite material and preparation method thereof
KR20110064986A (en) Aerogel and preparation method thereof
CN108383132B (en) Low-temperature preparation method of superfine mullite powder
CN103130271A (en) Ultra-low density block-shaped fully stabilized zirconia gel and preparing method thereof
CN108439418B (en) Method for producing nano-silica aerogel through supercritical extraction, nano-silica aerogel produced by method and aerogel product
CN112320833B (en) High temperature resistant SiO 2 -Gd 2 O 3 Composite aerogel and preparation method thereof
CN113735148B (en) Preparation method of high-temperature-resistant massive alumina aerogel
CN111453739B (en) Preparation method of hybrid silica aerogel and hybrid silica aerogel
CN114874026A (en) Preparation method of high-strength fiber composite zirconia foamed ceramic
CN116903032A (en) Preparation method of silica stabilized lanthanum zirconate aerogel
CN115321546B (en) Method for preparing hydrophobic and high-temperature-resistant alumina-silica aerogel in situ

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination