CN104986994A - Preparation method of blocky zirconium-carbon composite aerogel material - Google Patents

Abstract

The invention belongs to the field of preparation processes of nano porous materials, and relates to a preparation method of a blocky zirconium-carbon composite aerogel material. The invention takes resorcinol and formaldehyde as carbon sources, inorganic zirconium oxychloride as a zirconium source, deionized water as a hydrolytic agent, alcohols as a solvent and epoxide as a gel promoter, prepares wet gel through sol-gel reaction under the action of an alkaline catalyst, and the wet gel is subjected to aging, solvent replacement, supercritical drying and high-temperature heat treatment to obtain the high-temperature-resistant zirconium-carbon composite aerogel material. The material prepared by using cheap inorganic zirconium salt as a raw material has the characteristics of low density, large specific surface area, high strength, high temperature resistance and complete structure, and the system has good prospects in high-temperature heat insulation and catalytic carrier.

Description

A kind of preparation method of bulk zirconium-carbon composite airgel material

technical field

The invention belongs to the field of preparation technology of nanoporous materials, and relates to a preparation method of carbon-zirconium composite air-condensing heat material. In particular, a CO ₂ supercritical method is used to prepare bulk zirconium-carbon composite airgel materials.

Background technique

Airgel is a nanoporous material made of nanoparticles aggregated with each other. It has high specific surface area and porosity, so it is different from ordinary solid-state materials in thermal, acoustic, and optical aspects. nanoporous materials. The high porosity of the airgel material can reduce the heat conduction of the solid, the nanoporous structure can inhibit the heat conduction of the gas, and the introduction of the infrared opacifier can reduce the radiation heat transfer, which makes the aerogel have excellent heat insulation performance and is currently recognized as the thermal conductivity Lowest solid material. At present, there are many studies on carbon-silicon and carbon-aluminum systems at home and abroad, but there is no specific report on the research on carbon-zirconium system composite aerogels. Therefore, the preparation and research of bulk carbon-zirconium system aerogels have a profound impact on optimizing the performance of materials and the application of reinforced materials.

Contents of the invention

The object of the present invention is to provide a kind of preparation method of bulk zirconium-carbon composite airgel material in order to improve the deficiencies of the prior art. , and as a catalyst carrier.

The technical scheme of the present invention is: a kind of preparation method of bulk zirconium-carbon composite airgel material, and its concrete steps are as follows:

(1) dissolving the inorganic zirconium salt in a solvent to obtain a concentration of 0.1mol/L to 0.5mol/L inorganic zirconium salt solution, then adding polyethylene glycol and formamide to the solution and stirring evenly to obtain ZrO sol _; wherein poly The molar ratio of ethylene glycol to inorganic zirconium salt is (0.2~1):1, and the molar ratio of formamide to inorganic zirconium salt is (0.2~1):1; at the same time, resorcinol, formaldehyde, water, alkaline Catalyst, according to the molar ratio of formaldehyde: water: resorcinol is 2: (33 ~ 55): 1, and the molar ratio of resorcinol: basic catalyst is 80 ~ 120, mix evenly to obtain RF organosol ;

( ₂ ) Mix the ZrO sol and RF organic sol obtained in step (1) according to the molar ratio of inorganic zirconium salt and resorcinol as 1: (1-4), stir evenly, add propylene oxide, and stir again After uniformity, place it in a mold and wait for it to gel to obtain ZrO ₂ /RF gel;

(3) Then add aging liquid to the gel in the mold in step (2), and put it into an oven at 40-70°C for aging treatment and replace impurity ions;

(4) performing supercritical drying treatment on the ZrO ₂ /RF composite wet gel obtained after the aging treatment in step (3), to obtain block ZrO ₂ /RF composite airgel;

(5) heat-treating the ZrO ₂ /RF composite airgel obtained in step (4) under atmosphere protection to obtain a block high temperature resistant carbon-zirconium airgel material.

Preferably, the solvent described in step (1) is a mixed solvent of water and ethanol in a volume ratio of 1:(3-5).

Preferably, the inorganic zirconium salt described in step (1) is one of zirconium oxychloride octahydrate or zirconyl nitrate hexahydrate or a mixture thereof.

The basic catalyst in the preferred step (1) is one of anhydrous sodium carbonate, sodium hydroxide, calcium hydroxide or potassium carbonate.

Preferably, the amount of propylene oxide added in step (2) is to control the molar ratio of propylene oxide to inorganic zirconium salt to be (1-4):1.

Preferably, the aging solution described in step (3) is one of ethanol, n-hexane or tetraethyl orthosilicate or a mixture thereof; the number of replacements for aging treatment and replacement of impurity ions is 5 to 10 times, and each replacement time 12 to 24 hours.

Preferably, the supercritical drying described in step (4) is _CO2 supercritical drying, using _CO2 as the drying medium, the reaction temperature is 45-60°C, the pressure inside the autoclave is 8-12MPa, and the drying time is 8-14h .

Preferably, the atmosphere described in step (5) is one of nitrogen, argon or helium.

Preferably, the heat treatment temperature in step (5) is 800° C. to 1500° C., and the heat treatment time is 3 to 10 hours.

Preferably, the airgel material prepared in step (5) has an apparent density of 0.15-0.6 g/cm ³ , a specific surface area of 330-500 m ² /g, and a pore size distribution of 5-50 nm.

Beneficial effect:

The method of the present invention and the massive high-temperature-resistant zirconium-carbon composite airgel material by the method have the following characteristics:

(1) The raw material is cheap and the cost is reduced. In the method, the zirconium source is selected from inorganic zirconium salt, and the organic zirconium alkoxide used in the general preparation process is abandoned, and the price of the inorganic zirconium salt is low, which greatly reduces the production cost.

(2) Low density. The mass high temperature resistant zirconium-carbon composite airgel material prepared by the invention has a density of 0.15-0.6 g/cm ² , which is much lower than conventional high temperature heat insulation materials.

(3) The blocky high-temperature-resistant zirconium-carbon composite airgel material prepared by this method, the carbon reactant and the zirconium reactant are not independent reactions in the sol-gel process, and the wet gel obtained is not a simple carbon and zirconium Mixing, but reacting with each other makes the network structure of the wet gel intertwined and stronger. Therefore, airgel has good formability and high strength, and can be used in good applications.

Description of drawings

Fig. 1 is the physical photograph of the shape high temperature resistant zirconium-carbon composite airgel material that embodiment example 1 makes;

Fig. 2 is the nitrogen adsorption-desorption curve of the carbon-zirconium composite airgel that embodiment example 1 makes;

Fig. 3 is the SEM photo of the bulk carbon-zirconium composite airgel prepared in Example 3.

Detailed ways

Example 1

According to the molar ratio of zirconium oxychloride octahydrate and resorcinol of 1: ₂ , ZrO sol and RF sol were respectively configured, and zirconium oxychloride octahydrate was dissolved in a mixed solvent with a volume ratio of ethanol and water of 1:4 so that Its concentration is 0.5mol/L, add polyethylene glycol 1000, formamide to it, and the molar ratio of polyethylene glycol 1000 and formamide to zirconium oxychloride octahydrate is 0.5:1, mix and stir evenly to obtain ZrO ₂ Sol. Formaldehyde: water: resorcinol = 2:55:1, resorcinol: sodium carbonate = 100 molar ratio uniformly mixed and fully stirred to obtain organosol (RF sol). Mix the above two kinds of sols and stir them evenly, then add propylene oxide with a molar ratio of 1:1 to zirconium oxychloride, stir for 15 minutes, pour into the mold, and gel in about 6 hours. After the RF/ZrO ₂ gel obtained above was placed at room temperature for 12 hours, ethanol was added as an aging solution to replace the impurity ions in the wet gel, and then placed in an oven at 50°C for 8 replacements, 24 hours each time. Then put the aged RF/ZrO2 composite wet gel into a high _- temperature autoclave, and use the _CO2 supercritical drying method to dry the sample, wherein the _CO2 pressure is controlled at 10MPa, the temperature is controlled at 50 °C, and the supercritical drying time 9h, thus making block RF/ZrO ₂ composite airgel with good formability. Then, the organic airgel was heat-treated at 1500° C. for 3 h under the protection of argon to obtain the desired bulk carbon-zirconium composite airgel material. The physical photo of the obtained high-temperature-resistant zirconium-carbon composite airgel material is shown in Figure 1: it can be seen that the composite airgel is a complete block with no cracks on the surface, and has a certain mechanical strength, and its nitrogen adsorption The desorption curve is shown in Figure 2: it can be seen that the curve is a typical type IV curve, indicating that the material is a typical mesoporous material with a large specific surface area, which is conducive to use as a high temperature resistant heat insulation material. It is found through characterization that its density is 0.41g/cm ² , its specific surface area is 420.1m ² /g, and its pore size distribution is 5-30nm.

Example 2

According to the molar ratio of zirconium oxychloride octahydrate and resorcinol of 1: ₁ , ZrO sol and RF sol were respectively configured, and zirconium oxychloride octahydrate was dissolved in a mixed solvent with a volume ratio of ethanol and water of 1:3 so that Its concentration is 0.5mol/L, add polyethylene glycol 600, formamide to it, and the molar ratio of polyethylene glycol 600 and formamide to zirconium oxychloride octahydrate is 0.2:1, mix and stir evenly to obtain ZrO ₂ Sol. Formaldehyde: water: resorcinol = 2:55:1, resorcinol: potassium carbonate = 100 molar ratio uniformly mixed and fully stirred to obtain organosol (RF sol). Mix the above two kinds of sols and stir them well, then add propylene oxide with a molar ratio of 1:1 to zirconium oxychloride, stir for 10 minutes, pour into the mold, and gel in about 8 hours. After the RF/ZrO ₂ gel obtained above was placed at room temperature for 12 hours, ethanol was added as an aging solution to replace the impurity ions in the wet gel, and then placed in an oven at 40°C for 10 replacements, 24 hours each time. Then put the aged RF/ZrO2 composite wet gel into a high _- temperature autoclave, and use the _CO2 supercritical drying method to dry the sample, wherein the _CO2 pressure is controlled at 8MPa, the temperature is controlled at 60 °C, and the supercritical drying time For 12h, block RF/ZrO ₂ composite airgel with good formability was obtained. Then, the organic airgel was heat-treated at 1500° C. for 10 h under the protection of argon to obtain the required bulk carbon-zirconium composite airgel material. The prepared composite airgel has a density of 0.51g/cm ² , a specific surface area of 338.4m ² /g, and a pore size distribution of 10-40nm.

Example 3

According to the molar ratio of zirconium oxychloride octahydrate and resorcinol of 1: ₄ , ZrO sol and RF sol were respectively configured, and zirconium oxychloride octahydrate was dissolved in a mixed solvent with a volume ratio of ethanol and water of 1:5 so that Its concentration is 0.5mol/L, add polyethylene glycol 1000, formamide to it, and the molar ratio of polyethylene glycol 1000 and formamide to zirconium oxychloride octahydrate is 0.8:1, mix and stir evenly to obtain ZrO ₂ Sol. Formaldehyde: water: resorcinol = 2:55:1, resorcinol: sodium carbonate = 100 molar ratio uniformly mixed and fully stirred to obtain organosol (RF sol). Mix the above two kinds of sols and stir them evenly, then add propylene oxide with a molar ratio of 1:1 to zirconium oxychloride, stir for 15 minutes, pour into the mold, and gel in about 5 hours. After the RF/ZrO ₂ gel obtained above was placed at room temperature for 12 hours, ethanol was added as an aging solution to replace the impurity ions in the wet gel, and then placed in an oven at 70°C for 5 replacements, 12 hours each time. Then put the aged RF/ZrO2 composite wet gel into a high _- temperature autoclave, and use the _CO2 supercritical drying method to dry the sample, in which the _CO2 pressure is controlled at 12MPa, the temperature is controlled at 45°C, and the supercritical drying time 8h, thus making block RF/ZrO ₂ composite airgel with good formability. Then, the organic airgel was heat-treated at 1500° C. for 3 h under the protection of argon to obtain the desired bulk carbon-zirconium composite airgel material. The SEM image of the prepared carbon-zirconium composite airgel material is shown in Figure 3. It can be seen from the figure that the obtained block carbon-zirconium composite airgel is a porous network structure, and its density is found to be 0.24g/ cm ² , the specific surface area is 429.0m ² /g, and the pore size distribution is 5-40nm.

Example 4

According to the molar ratio of zirconium oxychloride and resorcinol of 1:2, respectively configure ZrO ₂ sol and RF sol, and dissolve zirconium oxychloride octahydrate in a mixed solvent with a volume ratio of ethanol and water of 1:4 so that its concentration 0.1mol/L, add polyethylene glycol 600, formamide to it, the molar ratio of polyethylene glycol 600 and formamide to zirconium oxychloride octahydrate is 1:1, mix and stir evenly to obtain ZrO ₂ sol . Formaldehyde: water: resorcinol = 2:55:1, resorcinol: sodium carbonate = 80 molar ratio uniformly mixed and fully stirred to obtain organosol (RF sol). Mix the above two sols and stir them evenly, then add propylene oxide with a molar ratio of 3:1 to zirconium oxychloride, stir for 10 minutes, pour into the mold, and gel in about 3 hours. After the RF/ZrO ₂ gel obtained above was placed at room temperature for 12 hours, ethanol was added as an aging solution to replace the impurity ions in the wet gel, and then placed in an oven at 50°C for 7 replacements, 24 hours each time. Then put the aged RF/ZrO2 composite wet gel into a high _- temperature autoclave, and use the _CO2 supercritical drying method to dry the sample, wherein the _CO2 pressure is controlled at 10MPa, the temperature is controlled at 50 °C, and the supercritical drying time For 10h, the block RF/ZrO ₂ composite airgel with good formability was obtained. Then, the organic airgel was heat-treated at 1500° C. for 5 h under the protection of helium to obtain the required bulk carbon-zirconium composite airgel material. The prepared composite airgel has a density of 0.17g/cm ² , a specific surface area of 490.1m ² /g, and a pore size distribution of 10-50nm.

Example 5

According to the molar ratio of zirconium oxynitrate hexahydrate and resorcinol at 1:2, ZrO ₂ sol and RF sol were respectively configured, and zirconium oxynitrate hexahydrate was dissolved in a mixed solvent with a volume ratio of ethanol and water of 1:4 so that its concentration 0.5mol/L, add polyethylene glycol 1000, formamide, the molar ratio of polyethylene glycol 1000 and formamide to zirconium oxynitrate hexahydrate is 0.5:1, mix and stir evenly to obtain ZrO ₂ sol. Formaldehyde: water: resorcinol = 2:33:1, resorcinol: sodium carbonate = 120 molar ratio uniformly mixed and fully stirred to obtain organosol (RF sol). Mix the two sols above and stir them evenly, then add propylene oxide to the zirconium oxychloride molar ratio of 1:1, stir for 10 minutes, pour into the mold, and gel in about 6 hours. After the RF/ZrO ₂ gel obtained above was placed at room temperature for 12 hours, n-hexane was added as an aging solution to replace the impurity ions in the wet gel, and then placed in an oven at 50°C for 8 replacements, 24 hours each time. Then put the aged RF/ZrO2 composite wet gel into a high _- temperature autoclave, and use the _CO2 supercritical drying method to dry the sample, wherein the _CO2 pressure is controlled at 10MPa, the temperature is controlled at 50 °C, and the supercritical drying time 14h, thus making a block RF/ZrO ₂ composite airgel with good formability. Then, the organic airgel was heat-treated at 800° C. for 3 h under the protection of nitrogen to obtain the desired bulk carbon-zirconium composite airgel material. The prepared composite airgel has a density of 0.58g/cm ² , a specific surface area of 377.2m ² /g, and a pore size distribution of 5-20nm.

Example 6

According to the molar ratio of zirconium oxychloride octahydrate and resorcinol of 1: ₂ , ZrO sol and RF sol were respectively configured, and zirconium oxychloride octahydrate was dissolved in a mixed solvent with a volume ratio of ethanol and water of 1:4 so that The concentration is 0.3mol/L, add polyethylene glycol 600, formamide to it, the molar ratio of polyethylene glycol 600 and formamide to zirconium oxychloride octahydrate is 0.5:1, mix and stir evenly to obtain ZrO ₂ Sol. Formaldehyde: water: resorcinol = 2:55:1, resorcinol: sodium carbonate = 100 molar ratio uniformly mixed and fully stirred to obtain organosol (RF sol). Mix the two sols above and stir them evenly, then add propylene oxide with a molar ratio of 2.5:1 to the zirconium oxychloride, stir for 10 minutes, pour into the mold, and gel in about 3 hours. After the RF/ZrO ₂ gel obtained above was placed at room temperature for 12 hours, ethanol was added as an aging solution to replace the impurity ions in the wet gel, and then placed in an oven at 50°C for 10 replacements, 24 hours each time. Then put the aged RF/ZrO2 composite wet gel into a high _- temperature autoclave, and use the _CO2 supercritical drying method to dry the sample, wherein the _CO2 pressure is controlled at 10MPa, the temperature is controlled at 50 °C, and the supercritical drying time 11h, thus making block RF/ZrO ₂ composite airgel with good formability. Then, the organic airgel was heat-treated at 1500° C. for 3 h under the protection of argon to obtain the desired bulk carbon-zirconium composite airgel material. The prepared composite airgel has a density of 0.26g/cm ² , a specific surface area of 488.7m ² /g, and a pore size distribution of 5-40nm.

Example 7

According to the molar ratio of zirconium oxychloride octahydrate and resorcinol of ₁ :1.5, ZrO sol and RF sol were respectively configured, and zirconium oxychloride octahydrate was dissolved in a mixed solvent with a volume ratio of ethanol and water of 1:4 so that Its concentration is 0.5mol/L, add polyethylene glycol 1000, formamide to it, and the molar ratio of polyethylene glycol 1000 and formamide to zirconium oxychloride octahydrate is 0.5:1, mix and stir evenly to obtain ZrO ₂ Sol. Formaldehyde: water: resorcinol = 2:55:1, resorcinol: sodium hydroxide = 100 molar ratio uniformly mixed and fully stirred to obtain organosol (RF sol). Mix the above two kinds of sols and stir them evenly, then add propylene oxide with a molar ratio of 1:1 to zirconium oxychloride, stir for 12 minutes, pour into the mold, and gel in about 7 hours. After the RF/ZrO ₂ gel obtained above was placed at room temperature for 12 hours, ethanol was added as an aging solution to replace the impurity ions in the wet gel, and then placed in an oven at 50°C for 8 replacements, 24 hours each time. Then put the aged RF/ZrO2 composite wet gel into a high _- temperature autoclave, and use the _CO2 supercritical drying method to dry the sample, in which the _CO2 pressure is controlled at 12MPa, the temperature is controlled at 45°C, and the supercritical drying time 8h, thus making block RF/ZrO ₂ composite airgel with good formability. Then, the organic airgel was heat-treated at 1500° C. for 5 h under the protection of argon to obtain the desired bulk carbon-zirconium composite airgel material. The prepared composite airgel has a density of 0.48g/cm ² , a specific surface area of 338.8m ² /g, and a pore size distribution of 5-30nm.

Claims (10)

1. a preparation method for block zirconium-carbon aerogel composite, its concrete steps are as follows:

(1) inorganic zirconium salts being dissolved in solvent configuration, to obtain concentration be 0.1mol/L ~ 0.5mol/L inorganic zirconium salts solution, then in solution, add polyoxyethylene glycol and methane amide stirs, and obtains ZrO ₂colloidal sol; Wherein the mol ratio of polyoxyethylene glycol and inorganic zirconium salts is (0.2 ~ 1): 1, and the mol ratio of methane amide and inorganic zirconium salts is (0.2 ~ 1): 1; Simultaneously by Resorcinol, formaldehyde, water, basic catalyst, according to formaldehyde: water: the mol ratio of Resorcinol is 2:(33 ~ 55): 1, Resorcinol: the mol ratio of basic catalyst is the ratio mixing of 80 ~ 120, stirs and obtains RF organosol;

(2) ZrO will obtained in step (1) ₂colloidal sol and RF organosol are 1:(1 ~ 4 according to inorganic zirconium salts with the mol ratio of Resorcinol) mix, add propylene oxide after stirring, then stir to be placed in mould and treat its gel, obtain ZrO ₂/ RF gel;

(3) then add Ageing solution to gel in mould in step (2), and the baking oven putting into 40 ~ 70 DEG C carries out burin-in process and replaces foreign ion;

(4) ZrO will obtained after burin-in process in step (3) ₂/ RF compound wet gel carries out supercritical drying process, obtains block ZrO ₂/ RF composite aerogel;

(5) ZrO will obtained in step (4) ₂the thermal treatment under atmosphere protection of/RF composite aerogel, obtains block high temperature resistant carbon-zirconium aerogel material.

2. preparation method according to claim 1, is characterized in that the solvent described in step (1) be water and ethanol is 1:(3 ~ 5 according to volume ratio) mixed solvent that configures.

3. preparation method according to claim 1, is characterized in that the inorganic zirconium salts described in step (1) is one in eight hydration zirconium oxychlorides or six nitric hydrate oxygen zirconiums or its mixture.

4. preparation method according to claim 1, the basic catalyst that it is characterized in that in step (1) is the one in anhydrous sodium carbonate, sodium hydroxide, calcium hydroxide or salt of wormwood.

5. preparation method according to claim 1, it is characterized in that the add-on of step (2) propylene oxide be the mol ratio of gate ring Ethylene Oxide and inorganic zirconium salts for (1 ~ 4): 1.

6. preparation method according to claim 1, is characterized in that the Ageing solution described in step (3) is one in ethanol, normal hexane or tetraethyl orthosilicate or its mixture; Burin-in process the displacement number of times of replacing foreign ion is 5 ~ 10 times, each time swap is 12 ~ 24h.

7. preparation method according to claim 1, is characterized in that the supercritical drying described in step (4) is CO ₂supercritical drying, with CO ₂as drying medium, temperature of reaction is 45 ~ 60 DEG C, and in autoclave, pressure is 8 ~ 12MPa, and time of drying is 8 ~ 14h.

8. preparation method according to claim 1, is characterized in that the atmosphere described in step (5) is the one in nitrogen, argon gas or helium.

9. preparation method according to claim 1, it is characterized in that in step (5), thermal treatment temp is 800 DEG C ~ 1500 DEG C, heat treatment time is 3 ~ 10h.

10. preparation method according to claim 1, is characterized in that the apparent density of the aerogel material that step (5) is obtained is 0.15 ~ 0.6g/cm ³, specific surface area is at 330 ~ 500m ²/ g, pore size distribution is at 5 ~ 50nm.