CN116903032A - Preparation method of silica stabilized lanthanum zirconate aerogel - Google Patents
Preparation method of silica stabilized lanthanum zirconate aerogel Download PDFInfo
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- CN116903032A CN116903032A CN202310908244.9A CN202310908244A CN116903032A CN 116903032 A CN116903032 A CN 116903032A CN 202310908244 A CN202310908244 A CN 202310908244A CN 116903032 A CN116903032 A CN 116903032A
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- 239000004964 aerogel Substances 0.000 title claims abstract description 59
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 title claims abstract description 36
- 229910052746 lanthanum Inorganic materials 0.000 title claims abstract description 32
- FZLIPJUXYLNCLC-UHFFFAOYSA-N lanthanum atom Chemical compound [La] FZLIPJUXYLNCLC-UHFFFAOYSA-N 0.000 title claims abstract description 32
- 238000002360 preparation method Methods 0.000 title claims abstract description 20
- 239000000377 silicon dioxide Substances 0.000 title claims abstract description 18
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims abstract description 69
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims abstract description 20
- GOOHAUXETOMSMM-UHFFFAOYSA-N Propylene oxide Chemical compound CC1CO1 GOOHAUXETOMSMM-UHFFFAOYSA-N 0.000 claims abstract description 20
- 235000019441 ethanol Nutrition 0.000 claims abstract description 20
- 239000011259 mixed solution Substances 0.000 claims abstract description 18
- GJKFIJKSBFYMQK-UHFFFAOYSA-N lanthanum(3+);trinitrate;hexahydrate Chemical compound O.O.O.O.O.O.[La+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O GJKFIJKSBFYMQK-UHFFFAOYSA-N 0.000 claims abstract description 15
- 238000000034 method Methods 0.000 claims abstract description 14
- BOTDANWDWHJENH-UHFFFAOYSA-N Tetraethyl orthosilicate Chemical compound CCO[Si](OCC)(OCC)OCC BOTDANWDWHJENH-UHFFFAOYSA-N 0.000 claims abstract description 13
- 238000000352 supercritical drying Methods 0.000 claims abstract description 13
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 11
- WXKDNDQLOWPOBY-UHFFFAOYSA-N zirconium(4+);tetranitrate;pentahydrate Chemical compound O.O.O.O.O.[Zr+4].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O WXKDNDQLOWPOBY-UHFFFAOYSA-N 0.000 claims abstract description 11
- 230000032683 aging Effects 0.000 claims abstract description 9
- 239000002904 solvent Substances 0.000 claims abstract description 9
- 239000003054 catalyst Substances 0.000 claims abstract description 7
- 239000002243 precursor Substances 0.000 claims abstract description 6
- 229910004298 SiO 2 Inorganic materials 0.000 claims abstract description 5
- 230000003301 hydrolyzing effect Effects 0.000 claims abstract description 3
- 238000003756 stirring Methods 0.000 claims description 31
- 238000007789 sealing Methods 0.000 claims description 10
- 239000000203 mixture Substances 0.000 claims description 7
- 238000006460 hydrolysis reaction Methods 0.000 claims description 6
- 238000003760 magnetic stirring Methods 0.000 claims description 5
- 238000006243 chemical reaction Methods 0.000 claims description 4
- 238000009413 insulation Methods 0.000 abstract description 4
- 239000000499 gel Substances 0.000 description 9
- 238000001816 cooling Methods 0.000 description 8
- 238000010438 heat treatment Methods 0.000 description 8
- 239000000463 material Substances 0.000 description 7
- 238000010586 diagram Methods 0.000 description 4
- 238000010926 purge Methods 0.000 description 4
- 239000011240 wet gel Substances 0.000 description 4
- 238000010790 dilution Methods 0.000 description 3
- 239000012895 dilution Substances 0.000 description 3
- 238000009826 distribution Methods 0.000 description 3
- DZGCGKFAPXFTNM-UHFFFAOYSA-N ethanol;hydron;chloride Chemical compound Cl.CCO DZGCGKFAPXFTNM-UHFFFAOYSA-N 0.000 description 3
- 238000011049 filling Methods 0.000 description 3
- 239000012720 thermal barrier coating Substances 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 238000002441 X-ray diffraction Methods 0.000 description 2
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000002844 melting Methods 0.000 description 2
- 230000008018 melting Effects 0.000 description 2
- 239000011148 porous material Substances 0.000 description 2
- -1 rare earth nitrate Chemical class 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 238000003980 solgel method Methods 0.000 description 2
- 238000002336 sorption--desorption measurement Methods 0.000 description 2
- 229910002651 NO3 Inorganic materials 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 230000003064 anti-oxidating effect Effects 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 230000018109 developmental process Effects 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 238000010348 incorporation Methods 0.000 description 1
- 238000011031 large-scale manufacturing process Methods 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 238000010248 power generation Methods 0.000 description 1
- 239000011253 protective coating Substances 0.000 description 1
- 229910052761 rare earth metal Inorganic materials 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
- C01G25/00—Compounds of zirconium
- C01G25/02—Oxides
-
- 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
-
- 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
- C01F17/00—Compounds of rare earth metals
- C01F17/10—Preparation or treatment, e.g. separation or purification
-
- 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
- C01F17/00—Compounds of rare earth metals
- C01F17/30—Compounds containing rare earth metals and at least one element other than a rare earth metal, oxygen or hydrogen, e.g. La4S3Br6
- C01F17/32—Compounds containing rare earth metals and at least one element other than a rare earth metal, oxygen or hydrogen, e.g. La4S3Br6 oxide or hydroxide being the only anion, e.g. NaCeO2 or MgxCayEuO
-
- 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
- C01P2006/13—Surface area thermal stability thereof at high temperatures
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Life Sciences & Earth Sciences (AREA)
- Geology (AREA)
- Analytical Chemistry (AREA)
- Dispersion Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Inorganic Compounds Of Heavy Metals (AREA)
Abstract
The invention provides a preparation method of silica stabilized lanthanum zirconate aerogel, which comprises the following steps: lanthanum nitrate hexahydrate and zirconium nitrate pentahydrate are used as precursors, propylene oxide is used as a catalyst, and LZ sol is obtained in an absolute ethyl alcohol solvent; the method comprises the steps of using tetraethoxysilane as a precursor, using hydrochloric acid as a catalyst, and hydrolyzing in ethanol and a water solvent to obtain SiO 2 Sol; the SiO obtained is then used to prepare 2 Dropwise adding the sol into the LZ sol to obtain a mixed solution, and dropwise adding the mixed solution into the propylene oxide gel accelerator to obtain the LZS sol; standing the LZS sol in an oven to obtain LZS gel; aging and supercritical drying the LZS gel to obtain blocky LZS aerogel. The invention obtains twoThe silica stabilized lanthanum zirconate aerogel has a unique pyrochlore structure and good thermal stability, and has a very large application prospect in the field of heat insulation.
Description
Technical Field
The invention belongs to the technical field of aerogel preparation, and particularly relates to a preparation method of silica stabilized lanthanum zirconate aerogel.
Background
The thermal barrier coating has good heat insulation and antioxidation effects, is one of the most advanced high-temperature protective coatings at present, and is widely applied to industries such as aviation, aerospace, automobiles, large-scale thermal power generation and the like. The most commonly used thermal barrier coating material at present is 8mol% Y 2 O 3 -ZrO 2 (8 YSZ), but the long-term use temperature of this material is below 1200 ℃, which has not been able to meet the needs of future technological development. Lanthanum zirconate is considered to be a novel potential thermal barrier coating material due to the characteristics of high melting point, stable phase structure, low heat conductivity coefficient and the like, and has a unique pyrochlore structure. At present, the lanthanum zirconate aerogel prepared by a sol-gel method has better high-temperature stability and has no phase transition between room temperature and a melting point. However, the pyrochlore structure is easy to accelerate sintering to generate cracks due to oxygen vacancies, so that the thermal stability of the aerogel material is poor.
Disclosure of Invention
In order to solve the problems in the prior art, the invention provides a preparation method of silica stabilized lanthanum zirconate aerogel, which is used for obtaining the silica stabilized lanthanum zirconate aerogel, has a unique pyrochlore structure and good thermal stability, and has a very large application prospect in the field of heat insulation.
The invention solves the technical problems by adopting the following technical scheme:
the invention aims to provide a preparation method of silica stabilized lanthanum zirconate aerogel, which is characterized by comprising the following steps:
lanthanum nitrate hexahydrate and zirconium nitrate pentahydrate are used as precursors, propylene oxide is used as a catalyst, and LZ sol is obtained in an absolute ethyl alcohol solvent;
the preparation method comprises the steps of using tetraethoxysilane as a precursor, using hydrochloric acid as a catalyst, and hydrolyzing in ethanol and water solvent to obtain SiO 2 Sol;
the SiO obtained is then used to prepare 2 Dropwise adding the sol into the LZ sol to obtain a mixed solution, and dropwise adding the mixed solution into the propylene oxide gel accelerator to obtain the LZS sol;
standing the LZS sol in an oven to obtain LZS gel;
aging and supercritical drying the LZS gel to obtain blocky LZS aerogel.
The preparation method of the silica stabilized lanthanum zirconate aerogel is characterized by comprising the following steps of:
1) Sequentially adding lanthanum nitrate hexahydrate, zirconium nitrate pentahydrate and ethanol into a beaker according to a proportion, stirring in a heat-collecting magnetic stirring pot at 80 ℃ until the mixture is clear and transparent, and standing the mixture to room temperature to obtain a mixed solution;
2) Dropwise adding propylene oxide into the mixed sol obtained in the step 1), and uniformly stirring to obtain LZ sol;
3) Sequentially adding ethyl orthosilicate, ethanol and water into a three-neck flask according to the mol ratio of 1:14:2, mechanically stirring for 15min, dropwise adding hydrochloric acid into the mixture through a constant pressure funnel, and stirring for 120min. Sealing and standing for 24 hours at room temperature after stirring is completed, so that the hydrolysis reaction is fully and slowly carried out, and SiO is obtained 2 Sol;
4) SiO obtained in step 3) is reacted with 2 Dropwise adding the sol into the LZ sol obtained in the step 2), and uniformly stirring to obtain a mixed solution;
5) Dropwise adding propylene oxide into the mixed solution obtained in the step 4), uniformly stirring to obtain LZS sol, and putting the LZS sol into an oven to obtain LZS gel;
6) And (3) sealing, standing and aging the obtained LZS gel for 72 hours at normal temperature, and performing supercritical drying to obtain blocky LZS aerogel.
Further, in the step 1), the mol ratio of lanthanum nitrate hexahydrate, zirconium nitrate pentahydrate and ethanol is 1:1:40-100.
Further, the reaction temperature in the step 1) is 80 ℃, and the reaction degree is clear and transparent.
Further, in the step (2), the mol ratio of lanthanum nitrate hexahydrate to propylene oxide is 1:2, and the stirring time is 10min.
Further, in the step (3), the mol ratio of the tetraethoxysilane to the ethanol to the water is 1:14:2, and the stirring time is 15min.
Further, in the step (3), the mass fraction of the hydrochloric acid is 0.05wt%, and the molar ratio of the tetraethoxysilane to the hydrochloric acid is 5:10 -4 。
Further, in the step (3), hydrochloric acid is added and stirred for 120min, and after stirring is completed, the mixture is sealed and kept stand for 24h at room temperature, so that the hydrolysis reaction is fully and slowly carried out.
Further, the mole fraction of Si doped in the step (4) is 4% -20%.
Further, in the step (5), the molar ratio of lanthanum nitrate hexahydrate to propylene oxide is 1:1.
Further, the temperature set in the oven in step (5) was 60 ℃.
Further, the aging time of the gel in the step (6) was 72 hours.
Further, the supercritical ethanol drying method comprises the following steps: ethanol is used as a medium for supercritical drying, nitrogen is pre-filled to ensure that the pressure in the kettle is not less than 2MPa, the temperature in the kettle is increased to 270 ℃ at the heating rate of 1 ℃/min, and the temperature is kept for 2 hours until the pressure in the kettle is 8-10 MPa. After the water cooling device is opened and the pressure in the kettle is slowly released to normal pressure, N is introduced 2 Purging the kettle, and cooling to room temperature to obtain the LZS aerogel.
Compared with the prior art, the invention has the beneficial technical effects that:
the invention uses rare earth nitrate and tetraethoxysilane as raw materials, ethanol as a solvent, acid and alkali as catalysts, uses a sol-gel method to prepare silicon modified lanthanum zirconate wet gel, and obtains massive silica stabilized lanthanum zirconate aerogel after ethanol supercritical drying. The prepared aerogel has low density, high specific surface area and good heat insulation performance.
The preparation method has low requirements on equipment, short time consumption and simple preparation process, and is suitable for large-scale production. The process can reduce the density of the lanthanum zirconate aerogel and improve the formability and the thermal stability of the lanthanum zirconate aerogel. By controlling the ethanol content and doping SiO 2 The mole fraction of (c) controls the density and structure of the aerogel, further controlling its thermal conductivity. Incorporation of SiO into lanthanum zirconate aerogel 2 The complete block structure can be obtained, and the thermal stability of the aerogel is further improved.
The foregoing description is only an overview of the present invention, and is intended to be implemented in accordance with the teachings of the present invention in order that the technical means thereof may be more clearly understood, and in order that the present invention may be more readily understood, its objects, features and advantages be more particularly described below.
Drawings
Fig. 1 is a macroscopic view of LZS aerogel obtained in example 1 in a method for preparing a silica stabilized lanthanum zirconate aerogel according to the present invention.
Fig. 2 is an N2 adsorption-desorption curve and pore size distribution diagram of the LZS aerogel obtained in example 1 in the preparation method of the silica stabilized lanthanum zirconate aerogel according to the present invention.
Fig. 3 is an SEM micro morphology chart of the LZS aerogel obtained in example 1 in the preparation method of the silica stabilized lanthanum zirconate aerogel according to the present invention.
Fig. 4 is an XRD pattern of LZS aerogel obtained in example 1 and example 3 after heat treatment at 1200 ℃ in the preparation method of a silica stabilized lanthanum zirconate aerogel according to the present invention.
Detailed Description
The technical scheme of the invention is further described in detail below with reference to the attached drawings and specific embodiments. It is to be understood that the following examples are illustrative only and are not to be construed as limiting the scope of the invention. All techniques implemented based on the above description of the invention are intended to be included within the scope of the invention.
In addition, unless otherwise specifically indicated, the various raw materials, reagents, instruments and equipment used in the present invention may be obtained commercially or prepared by existing methods.
Example 1:
the preparation method of the silica stabilized lanthanum zirconate aerogel comprises the following steps:
1) 2.598g of lanthanum nitrate hexahydrate, 2.5759g of zirconium nitrate pentahydrate and 11.0568g of absolute ethyl alcohol are sequentially added into a beaker, stirred in a heat-collecting magnetic stirring pot at 80 ℃ until clear and transparent, and kept stand to room temperature to obtain a mixed solution.
2) 0.6969g of propylene oxide is dropwise added into the mixed sol obtained in the step 1), and LZ sol is obtained after uniform stirring.
3) 5g of TEOS, 15.456g of absolute ethanol and 0.864, 0.864g H were placed in a three-necked flask 2 O was mechanically stirred for 15min, to which 0.864g of 0.05wt% ethanol hydrochloride dilution was added dropwise at a rate of 6 s/drop via a constant pressure funnel, and stirred for 120min. Sealing and standing for 24 hours at room temperature after stirring is completed, so that the hydrolysis reaction is fully and slowly carried out, and SiO is obtained 2 And (3) sol.
4) 0.7579g of SiO from step 3) are reacted with 2 Slowly dripping sol into LZ sol obtained in the step 2), and magnetically stirring for 30min to obtain SiO 2 The amount of the mixed solution was 12% by mole.
5) 0.3485g of propylene oxide is dropwise added into the material obtained in the step 4), and SiO is obtained after uniform stirring 2 And (3) putting the sol into a baking oven at 60 ℃ for standing to obtain wet gel.
6) Sealing, standing and aging the LZS gel for 72 hours, performing supercritical drying, taking ethanol as a supercritical drying medium, and pre-filling N 2 Until the pressure in the kettle is 2MPa. Raising the temperature in the kettle to 270 ℃ at a heating rate of 1 ℃/min, and preserving the temperature for 2 hours until the pressure in the kettle is 10MPa. After the water cooling device is opened and the pressure in the kettle is slowly released to normal pressure, N is introduced 2 Purging the kettle, and cooling to room temperature to obtain the LZS aerogel.
Referring to FIG. 1, for a macroscopic view of the bulk LZS aerogel obtained in this example, an aerogel density of 0.1573g/cm was obtained 3 The heat conductivity coefficient is 0.0379W/mK, the specific surface area is 452.7m 2 And/g. FIG. 2 is a diagram of embodiment N 2 The adsorption-desorption curves and pore size distribution diagrams are shown in fig. 3 which is an aerogel microstructure diagram, and fig. 4 which is an XRD curve of the LZS aerogel after 1200 ℃ heat treatment, it can be seen that the isotherm of the LZS aerogel shows a typical type iii isotherm, havingThe H3 type hysteresis loop shows the characteristic distribution of the slit-shaped holes, and the aperture is between 20 and 40 nm. After heat treatment at 1200℃, la 2 Zr 2 O 7 As the main substance, siO 2 The addition of (2) enhances the stability of the lanthanum zirconate aerogel.
Example 2:
the preparation method of the silica stabilized lanthanum zirconate aerogel comprises the following steps:
1) 2.598g of lanthanum nitrate hexahydrate, 2.5759g of zirconium nitrate pentahydrate and 22.1136g of absolute ethyl alcohol are sequentially added into a beaker, stirred in a heat-collecting magnetic stirring pot at 80 ℃ until clear and transparent, and kept stand to room temperature to obtain a mixed solution.
2) 0.6969g of propylene oxide is dropwise added into the mixed sol obtained in the step 1), and LZ sol is obtained after uniform stirring.
3) 5g of TEOS, 15.456g of absolute ethanol and 0.864, 0.864g H were placed in a three-necked flask 2 O was mechanically stirred for 15min, to which 0.864g of 0.05wt% ethanol hydrochloride dilution was added dropwise at a rate of 6 s/drop via a constant pressure funnel, and stirred for 120min. Sealing and standing for 24 hours at room temperature after stirring is completed, so that the hydrolysis reaction is fully and slowly carried out, and SiO is obtained 2 And (3) sol.
4) 0.7579g of SiO from step 3) are reacted with 2 Slowly dripping the sol into the LZ sol obtained in the step 2), and magnetically stirring for 30min to obtain a mixed solution with Si doping amount of 12% in mole fraction.
5) 0.3485g of propylene oxide is dropwise added into the material obtained in the step 4), and SiO is obtained after uniform stirring 2 And (3) putting the sol into a baking oven at 60 ℃ for standing to obtain wet gel.
6) Sealing, standing and aging the LZS gel for 72 hours, performing supercritical drying, taking ethanol as a supercritical drying medium, and pre-filling N 2 Until the pressure in the kettle is 2MPa. Raising the temperature in the kettle to 270 ℃ at a heating rate of 1 ℃/min, and preserving the temperature for 2 hours until the pressure in the kettle is 10MPa. After the water cooling device is opened and the pressure in the kettle is slowly released to normal pressure, N is introduced 2 Purging the kettle, and cooling to room temperature to obtain the LZS aerogel.
The bulk LZS aerogel obtained in example 2 had a density of 0.0788g/cm 3 The heat conductivity coefficient is 0.0368W/mK, the specific surface area is 436.9m 2 And/g. The addition amount of the solvent in the LZ sol preparation process has great influence on the density of the LZS aerogel, and the addition amount of the solvent in the LZ sol preparation process is as follows: n is n Lanthanum nitrate hexahydrate ：n Zirconium nitrate pentahydrate ：n Ethanol ＝1:1:40～100。
Example 3:
the preparation method of the silica stabilized lanthanum zirconate aerogel comprises the following steps:
1) 2.598g of lanthanum nitrate hexahydrate, 2.5759g of zirconium nitrate pentahydrate and 11.0568g of absolute ethyl alcohol are sequentially added into a beaker, stirred in a heat-collecting magnetic stirring pot at 80 ℃ until clear and transparent, and kept stand to room temperature to obtain a mixed solution.
2) 0.6969g of propylene oxide is dropwise added into the mixed sol obtained in the step 1), and LZ sol is obtained after uniform stirring.
3) 5g of TEOS, 15.456g of absolute ethanol and 0.864, 0.864g H were placed in a three-necked flask 2 O was mechanically stirred for 15min, to which 0.864g of 0.05wt% ethanol hydrochloride dilution was added dropwise at a rate of 6 s/drop via a constant pressure funnel, and stirred for 120min. Sealing and standing for 24 hours at room temperature after stirring is completed, so that the hydrolysis reaction is fully and slowly carried out, and SiO is obtained 2 And (3) sol.
4) 0.4806g of SiO from step 3) are reacted with 2 Slowly dripping the sol into the LZ sol obtained in the step 2), and magnetically stirring for 30min to obtain a mixed solution with Si doping amount of 8% in mole fraction.
5) 0.3485g of propylene oxide is dropwise added into the material obtained in the step 4), and SiO is obtained after uniform stirring 2 And (3) putting the sol into a baking oven at 60 ℃ for standing to obtain wet gel.
6) Sealing, standing and aging the LZS gel for 72 hours, performing supercritical drying, taking ethanol as a supercritical drying medium, and pre-filling N 2 Until the pressure in the kettle is 2MPa. Raising the temperature in the kettle to 270 ℃ at a heating rate of 1 ℃/min, and preserving the temperature for 2 hours until the pressure in the kettle is 10MPa. After the water cooling device is opened and the pressure in the kettle is slowly released to normal pressure, N is introduced 2 Purging the kettle, and cooling to room temperature to obtain the LZS aerogel.
The bulk LZS aerogel obtained in example 3 had a density of 0.199g/cm 3 The heat conductivity coefficient is 0.0321W/mK, the specific surface area is 462.8m 2 And/g. FIG. 4 shows XRD patterns after heat treatment at 1200deg.C, in which SiO is the preferred embodiment 2 After the content is reduced, the heat conductivity coefficient is increased, the XRD of the aerogel is hardly changed, and La 2 Zr 2 O 7 To some extent, the zirconia peak is enhanced, and it can be seen that a proper amount of SiO is added 2 The thermal stability of the aerogel can be effectively improved.
The foregoing embodiment numbers of the present invention are merely for the purpose of description, and do not represent the advantages or disadvantages of the embodiments.
The embodiments of the present invention have been described above with reference to the accompanying drawings, but the present invention is not limited to the above-described embodiments, which are merely illustrative and not restrictive, and many forms may be made by those having ordinary skill in the art without departing from the spirit of the present invention and the scope of the claims, which are to be protected by the present invention.
Claims (9)
1. The preparation method of the silica stabilized lanthanum zirconate aerogel is characterized by comprising the following steps of:
lanthanum nitrate hexahydrate and zirconium nitrate pentahydrate are used as precursors, propylene oxide is used as a catalyst, and LZ sol is obtained in an absolute ethyl alcohol solvent;
the method comprises the steps of using tetraethoxysilane as a precursor, using hydrochloric acid as a catalyst, and hydrolyzing in ethanol and a water solvent to obtain SiO 2 Sol;
the SiO obtained is then used to prepare 2 Dropwise adding the sol into the LZ sol to obtain a mixed solution, and dropwise adding the mixed solution into the propylene oxide gel accelerator to obtain the LZS sol;
standing the LZS sol in an oven to obtain LZS gel;
aging and supercritical drying the LZS gel to obtain blocky LZS aerogel.
2. The method for preparing silica-stabilized lanthanum zirconate aerogel according to claim 1, comprising the steps of:
1) Sequentially adding lanthanum nitrate hexahydrate, zirconium nitrate pentahydrate and ethanol into a beaker according to a proportion, stirring in a heat-collecting magnetic stirring pot at 80 ℃ until the mixture is clear and transparent, and standing the mixture to room temperature to obtain a mixed solution;
2) Dropwise adding propylene oxide into the mixed sol obtained in the step 1), and uniformly stirring to obtain LZ sol;
3) Sequentially adding ethyl orthosilicate, ethanol and water into a three-neck flask according to a proportion, mechanically stirring for 15min, dropwise adding hydrochloric acid into the mixture through a constant pressure funnel, and stirring for 120min. Sealing and standing for 24 hours at room temperature after stirring is completed, so that the hydrolysis reaction is fully and slowly carried out, and SiO is obtained 2 Sol;
4) SiO obtained in step 3) is reacted with 2 Dropwise adding the sol into the LZ sol obtained in the step 2), and uniformly stirring to obtain a mixed solution;
5) Dropwise adding propylene oxide into the mixed solution obtained in the step 4), uniformly stirring to obtain LZS sol, and putting the LZS sol into an oven to obtain LZS gel;
6) And (3) sealing, standing and aging the obtained LZS gel for 72 hours at normal temperature, and performing supercritical drying to obtain blocky LZS aerogel.
3. The method for preparing the silica-stabilized lanthanum zirconate aerogel according to claim 2, wherein: in the step 1), the mol ratio of lanthanum nitrate hexahydrate, zirconium nitrate pentahydrate and ethanol is 1:1:40-100.
4. The method for preparing the silica-stabilized lanthanum zirconate aerogel according to claim 2, wherein: the reaction temperature in the step 1) is 80 ℃, and the reaction degree is clear and transparent.
5. The method for preparing the silica-stabilized lanthanum zirconate aerogel according to claim 2, wherein: in the step 2), the mol ratio of lanthanum nitrate hexahydrate to propylene oxide is 1:2, and the stirring time is 10min.
6. The method for preparing the silica-stabilized lanthanum zirconate aerogel according to claim 2, wherein: in the step 3), the mol ratio of the ethyl orthosilicate to the ethanol to the water is 1:14:2, and the stirring time is 15min.
7. The method for preparing the silica-stabilized lanthanum zirconate aerogel according to claim 2, wherein: the mass fraction of hydrochloric acid in the step 3) is 0.05wt%, and the mol ratio of the tetraethoxysilane to the hydrochloric acid is 5:10 -4 。
8. The method for preparing the silica-stabilized lanthanum zirconate aerogel according to claim 2, wherein: the mole fraction of Si doped in the step 4) is 4-20%.
9. The method for preparing the silica-stabilized lanthanum zirconate aerogel according to claim 2, wherein: the molar ratio of lanthanum nitrate hexahydrate to propylene oxide in step 5) is 1:1.
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