A method for preparing a titanium carbonitride aerogel

Abstract

The application discloses a preparation method of titanium carbonitride aerogel, which comprises the following steps: adding a metal oxide catalyst and a carbon source into TiO2 aerogel, heating to 900-1000 DEG C under an argon atmosphere, constant temperature treatment, switching the argon to a mixed gas for carbonitriding treatment after the constant temperature treatment, switching back to the argon and cooling to 500-600 DEG C, and then cooling to room temperature in the furnace, so as to obtain the titanium carbonitride aerogel. On the one hand, the high-valence metal oxide is used as the catalyst, the carbonization temperature of TiO2 is reduced, the carbonization rate is improved, the content of Ti(C, N, O) in the finished product is increased, and the energy consumption is lower than that of the prior art. On the other hand, the mixed gas is used for carbonitriding, the carbonitriding reaction is more sufficient by adding the carbon source, the equipment is simple, the raw materials are easy to obtain, and the cost is low.

Description

Technical Field

[0001] This invention relates to the field of aerogel preparation technology, and specifically to a method for preparing titanium carbonitride aerogel. Background Technology

[0002] Aerogels are solid materials with extremely low density, high porosity, and excellent insulation properties, typically prepared from aerogel precursors through supercritical drying. Titanium carbonitride, as a high-melting-point material, combines the advantages of both titanium carbide and titanium nitride, such as high melting point, high hardness, wear resistance, corrosion resistance, oxidation resistance, and good chemical stability. It is a potential high-temperature resistant aerogel matrix with broad application prospects in multiple fields.

[0003] The research and application of titanium carbonitride aerogels are of great significance in fields such as high-temperature insulation, energy and chemical engineering, environmental catalysis, and semiconductors. For example, the titanium carbonitride aerogel described in Reference 1:

[0004] Reference 1: Chinese patent document with application number CN2020107447774

[0005] Reference 1 describes a method for preparing bulk titanium carbide, titanium nitride, or titanium carbonitride aerogels. Using resorcinol-formaldehyde (RF) and tetrabutyl titanate as carbon and titanium sources, respectively, an alcohol as a solvent, and deionized water as a hydrolysate, a wet gel is prepared via a one-step sol-gel process with the addition of acid catalysts. The wet gel undergoes solvent replacement and supercritical drying to obtain an RF / TiO2 composite aerogel precursor. This precursor is then subjected to high-temperature carbothermic reduction under an inert atmosphere and calcination to remove carbon, yielding bulk titanium carbide, titanium nitride, or titanium carbonitride aerogel materials. This method utilizes the carbon generated by the pyrolysis of the organic aerogel (RF aerogel) for carbothermic reduction, eliminating the need for additional carbon reducing agents and increasing the operability and controllability of the process.

[0006] However, the preparation process of the aforementioned titanium carbonitride aerogel is relatively complicated, requires a large amount of organic solvent, is costly and polluting, and requires heat treatment at around 1700℃ for more than 5 hours. The production process is energy-intensive and has low production efficiency, which is not conducive to large-scale production. Summary of the Invention

[0007] The purpose of this invention is to solve the technical problems of cumbersome preparation process, high cost and high energy consumption of titanium carbonitride aerogel in the prior art, and to provide a method for preparing titanium carbonitride aerogel.

[0008] To address the shortcomings of the aforementioned technical problems, the present invention employs the following technical solution: a method for preparing titanium carbonitride aerogel, comprising adding a metal oxide catalyst and a carbon source to TiO2 aerogel, then heating it to 900–1000°C under an argon atmosphere and maintaining the temperature thereafter, switching the argon atmosphere to CH4-H2-N2 reaction gas for carbonitride treatment, switching back to argon atmosphere and cooling it to 500–600°C before furnace cooling to room temperature to obtain titanium carbonitride aerogel.

[0009] As a further optimization of the preparation method of titanium carbonitride aerogel of the present invention, the preparation method specifically includes the following steps:

[0010] S1. Add the titanium source to anhydrous ethanol and mix well to obtain solution A;

[0011] S2. Add the acidic substance to solution A and mix well to obtain solution B;

[0012] S3. Add the alkaline solution to solution B to obtain TiO2 sol. After the TiO2 sol is allowed to stand and gel, TiO2 gel is obtained. After aging, solvent replacement and supercritical CO2 drying, TiO2 aerogel is obtained.

[0013] S4. Add a metal oxide catalyst and a carbon source to the TiO2 aerogel. Place the TiO2 aerogel in an argon atmosphere and heat it to 900-1000℃, then keep it at a constant temperature. After the isothermal treatment, switch the argon to CH4-H2-N2 reaction gas for carbonitriding treatment. After the treatment, switch back to argon and cool it to 500-600℃. Then, cool it to room temperature in the furnace to obtain titanium carbonitriding aerogel.

[0014] As a further optimization of the preparation method of titanium carbonitride aerogel of the present invention: the titanium source is one or more of tetrabutyl titanate, tetraethyl titanate and titanium tetrachloride.

[0015] As a further optimization of the preparation method of titanium carbonitride aerogel of the present invention: the acidic substance is one or more of organic acid, inorganic acid and acidic gas; the organic acid is formic acid, acetic acid, oxalic acid or lactic acid, the inorganic acid is sulfuric acid, nitric acid or hydrochloric acid, and the acidic gas is sulfur oxide, nitrogen oxide or carbon dioxide.

[0016] As a further optimization of the preparation method of titanium carbonitride aerogel of the present invention: the alkaline solution is one or more of organic alkaline solution and inorganic alkaline solution; the organic alkaline solution is ethylenediamine solution, triethanolamine solution or triethylenetetramine solution, and the inorganic alkaline solution is sodium hydroxide solution, potassium hydroxide solution, calcium hydroxide solution or ammonia water.

[0017] As a further optimization of the preparation method of titanium carbonitride aerogel of the present invention: the catalyst is one or more of Mn2O7, Fe3O4, Co3O4 and Al2O3, and the amount of catalyst added is 5 to 10% of the weight of TiO2 aerogel.

[0018] As a further optimization of the preparation method of titanium carbonitride aerogel of the present invention: the carbon source is one or more of carbon black, carbon nanotubes, C60, fullerene, graphite and graphene, the carbon source particle size D90 is 0.1-200 nm, and the amount of carbon source added is 3-5% of the weight of TiO2 aerogel.

[0019] As a further optimization of the preparation method of titanium carbonitride aerogel of the present invention: the mixed gas contains a carbon source gas, a nitrogen source gas and a reactant gas, wherein the carbon source gas is CH4 or C2H4; the nitrogen source gas is NH3 or N2; and the reactant gas is H2; the proportion of each gas component in the mixed gas is: 4-8% carbon source gas, 5-20% nitrogen source gas and 75-85% reactant gas.

[0020] As a further optimization of the preparation method of titanium carbonitride aerogel of the present invention: the heating rate is 5-30℃ / min, the isothermal treatment time is 30-120min, the reaction time is 0.5-6h, and the cooling rate is 5-30℃ / min.

[0021] The present invention also provides a titanium carbonitride aerogel, which is prepared by the method described above.

[0022] The present invention has the following beneficial effects:

[0023] 1. This invention uses high-valence metal oxides as catalysts, which can reduce the carbonization temperature of TiO2, increase the carbonization rate, and increase the Ti(C,N,O) content in the finished product, while consuming less energy than existing technologies.

[0024] 2. This invention uses a mixed gas for carbonitriding. In addition to nitrogen source gas and reaction gas, carbon source gas is also added, which makes the carbonitriding reaction more complete. The equipment used in the entire preparation process is relatively simple, the raw materials are readily available, and the preparation cost is low. Attached Figure Description

[0025] Figure 1 The image shows the XRD pattern of the Fe-Ti(C,N,O) aerogel prepared in Example 1.

[0026] Figure 2 The XRD pattern of Ti(C,N,O) aerogel prepared in Comparative Example 1 is shown.

[0027] Figure 3 The adsorption-desorption curves of the Fe-Ti(C,N,O) aerogel prepared in Example 1 are shown.

[0028] Figure 4 The image shows a SEM image of the Fe-Ti(C,N,O) aerogel prepared in Example 1. Detailed Implementation

[0029] To better understand the present invention, the following embodiments further illustrate the content of the present invention, but the content of the present invention is not limited to the following embodiments.

[0030] <Titanium Carbonitride Aerogel and its Preparation Method>

[0031] S1. Add the titanium source to anhydrous ethanol and mix well to obtain solution A.

[0032] The titanium source is one or more of tetrabutyl titanate, tetraethyl titanate, and titanium tetrachloride, and the molar ratio of titanium source to anhydrous ethanol is titanium source: anhydrous ethanol = 1~3:20~30.

[0033] S2. Add the acidic substance to solution A and mix well to obtain solution B. The initial pH of solution B is 1 to 6.5.

[0034] Acidic substances are one or more of organic acids, inorganic acids, and acidic gases.

[0035] The organic acids are formic acid, acetic acid, oxalic acid, or lactic acid.

[0036] The inorganic acid is sulfuric acid, nitric acid, or hydrochloric acid.

[0037] The acidic gases are sulfur oxides, nitrogen oxides, or carbon dioxide.

[0038] S3. Add the alkaline solution to solution B to obtain TiO2 sol. After the TiO2 sol is allowed to stand and gel, TiO2 gel is obtained. After aging, solvent replacement and supercritical CO2 drying, TiO2 aerogel is obtained.

[0039] The alkaline solution is one or more of organic and inorganic alkaline solutions.

[0040] The organic base solution is ethylenediamine solution, triethanolamine solution, or triethylenetetramine solution.

[0041] Inorganic bases are sodium hydroxide solution, potassium hydroxide solution, calcium hydroxide solution, or ammonia water.

[0042] S4. Add a metal oxide catalyst and a carbon source to the TiO2 aerogel. Place the TiO2 aerogel under an argon atmosphere and heat it to 900-1000℃ (heating rate of 5-30℃ / min), then hold it at that temperature for 30-120 min. After the isothermal treatment, switch the argon gas to CH4-H2-N2 reaction gas for carbonitriding treatment (1-3 h). After the treatment, switch back to argon gas and cool it down (cooling rate of 5-30℃ / min) to 500-600℃, then cool it to room temperature in the furnace to obtain titanium carbonitriding aerogel.

[0043] The metal oxide catalyst and carbon source are added by mechanical stirring until they are mixed evenly at a speed of 50-1000 rpm.

[0044] The catalyst is one or more of Mn2O7, Fe3O4, Co3O4 and Al2O3, and the amount of catalyst added is 5 to 10% of the weight of TiO2 aerogel.

[0045] The carbon source is one or more of carbon black, carbon nanotubes, C60, fullerene, graphite and graphene, the carbon source particle size D90 is 0.1 to 200 nm, and the amount of carbon source added is 3 to 5% of the weight of TiO2 aerogel.

[0046] The mixed gas contains a carbon source gas, a nitrogen source gas, and a reactant gas. The carbon source gas is CH4 or C2H4; the nitrogen source gas is NH3 or N2; and the reactant gas is H2. The proportions of each gas component in the mixed gas are: 4-8% carbon source gas, 5-20% nitrogen source gas, and 75-85% reactant gas.

[0047] <Example 1>

[0048] A method for preparing titanium carbonitride aerogel includes the following steps:

[0049] S1, add 37.44g of tetrabutyl titanate to 100ml of anhydrous ethanol and disperse thoroughly to obtain solution A.

[0050] S2, 0.5 mol / L hydrochloric acid is added dropwise to solution A and dispersed thoroughly to obtain solution B. The initial pH of solution B is 3.7.

[0051] S3, 0.5 mol / L sodium hydroxide solution was added dropwise to solution B to obtain TiO2 sol. The obtained TiO2 sol was allowed to stand for 0.5 h to gel, and TiO2 gel was obtained. The TiO2 gel was aged at 25℃ for 48 h, solvent was replaced and supercritical CO2 drying was performed to obtain TiO2 aerogel. The initial pH of solution C was 10.5.

[0052] S4, 1.87g Fe3O4 was added to TiO2 aerogel;

[0053] S5. The obtained TiO2 aerogel was heated to 900℃ at a heating rate of 5℃ / min under argon atmosphere protection and held at that temperature for 120min. The argon was then switched to a mixed gas (CH4 5%, NH3 20%, and H2 75%) to start carbonitriding treatment. After reacting for 3h, the gas was switched back to argon and the temperature was lowered to 500℃ at a cooling rate of 5℃ / min and then cooled to room temperature in the furnace to obtain Fe-Ti(C,N,O) aerogel.

[0054] Figure 1 The XRD pattern of the obtained Fe-Ti(C,N,O) aerogel is shown in the figure. The peak at 27° is a characteristic peak of titanium dioxide rutile, the peaks at 36°, 39°, 42.3°, and 61° are characteristic peaks of Ti(C,N,O), and the small peaks at 41.24° and 64° are characteristic peaks of Fe.

[0055] like Figure 3 As shown, the adsorption-desorption curves of the prepared Fe-Ti(C,N,O) aerogel exhibit a distinct hysteresis loop, indicating that the product is a mesoporous material. The specific surface area, pore volume, and pore size of the Fe-Ti(C,N,O) aerogel are 358.7 m² / s. 2 / g, 3.3cm 3 / g and 18.48nm.

[0056] like Figure 4 The image shows the SEM image of the prepared Fe-Ti(C,N,O) aerogel. It can be seen that the obtained composite aerogel has a three-dimensional porous network structure, indicating that the product has good thermal insulation performance.

[0057] <Example 2>

[0058] A method for preparing titanium carbonitride aerogel includes the following steps:

[0059] S1, add 52.84g of tetraethyl titanate to 100ml of anhydrous ethanol and disperse thoroughly to obtain solution A.

[0060] S2, 0.5 mol / L formic acid is added dropwise to solution A and dispersed thoroughly to obtain solution B. The initial pH of solution B is 3.7.

[0061] S3, 0.5 mol / L ethylenediamine solution was added dropwise to solution B to obtain TiO2 sol. The obtained TiO2 sol was allowed to stand for 0.5 h to gel, and TiO2 gel was obtained. The TiO2 gel was aged at 25℃ for 48 h, solvent was replaced and supercritical CO2 drying was performed to obtain TiO2 aerogel. The initial pH of solution C was 10.5.

[0062] S4. 2.71g Mn2O7 was added to TiO2 aerogel. The resulting TiO2 aerogel was heated to 1000℃ at a heating rate of 30℃ / min under argon atmosphere protection and held at that temperature for 30min. The argon was then switched to a mixed gas (8% C2H4, 12% N2 and 80% H2) to start carbonitriding treatment. After reacting for 6h, the gas was switched back to argon and the temperature was lowered to 600℃ at a cooling rate of 30℃ / min and then cooled to room temperature in the furnace to obtain Mn-Ti(C,N,O) aerogel.

[0063] <Example 3>

[0064] A method for preparing titanium carbonitride aerogel includes the following steps:

[0065] S1, add 23.18g of titanium tetrachloride to 100ml of anhydrous ethanol and disperse thoroughly to obtain solution A;

[0066] S2, 0.5 mol / L hydrochloric acid is added dropwise to solution A and dispersed thoroughly to obtain solution B. The initial pH of solution B is 3.7.

[0067] S3, 0.5 mol / L ammonia water was added dropwise to solution B to obtain TiO2 sol. The obtained TiO2 sol was allowed to stand for 0.5 h to gel, and TiO2 gel was obtained. The TiO2 gel was aged at 25℃ for 48 h, solvent was replaced and supercritical CO2 drying was performed to obtain TiO2 aerogel. The initial pH of solution C was 10.5.

[0068] S4, 1.66g Co3O4 was added to TiO2 aerogel;

[0069] S5. The obtained TiO2 aerogel was heated to 950℃ at a heating rate of 8℃ / min under argon atmosphere protection and held at that temperature for 45min. The argon was then switched to a mixed gas (8% C2H4, 12% N2 and 80% H2) to start carbonitriding treatment. After reacting for 2h, the gas was switched back to argon and the temperature was lowered to 550℃ at a cooling rate of 6℃ / min and then cooled to room temperature in the furnace to obtain Co-Ti(C,N,O) aerogel.

[0070] <Example 4>

[0071] A method for preparing titanium carbonitride aerogel includes the following steps:

[0072] S1, add 37.44g of tetrabutyl titanate to 100ml of anhydrous ethanol and disperse thoroughly to obtain solution A.

[0073] S2, 0.5 mol / L hydrochloric acid is added dropwise to solution A and dispersed thoroughly to obtain solution B. The initial pH of solution B is 3.7.

[0074] S3, 0.5 mol / L sodium hydroxide solution was added dropwise to solution B to obtain TiO2 sol. The obtained TiO2 sol was allowed to stand for 0.5 h to gel, and TiO2 gel was obtained. The TiO2 gel was aged at 25℃ for 48 h, solvent was replaced and supercritical CO2 drying was performed to obtain TiO2 aerogel. The initial pH of solution C was 10.5.

[0075] S4, 2.07g Al2O3 was added to TiO2 aerogel;

[0076] S5. The obtained TiO2 aerogel was heated to 900℃ at a heating rate of 5℃ / min under argon atmosphere protection and held at that temperature for 60min. The argon was then switched to a mixed gas (CH4 7%, NH3 16%, and H2 77%) to start carbonitriding treatment. After reacting for 3h, the gas was switched back to argon and the temperature was lowered to 500℃ at a cooling rate of 5℃ / min and then cooled to room temperature in the furnace to obtain Al-Ti(C,N,O) aerogel.

[0077] <Comparative Example 1>

[0078] S1, add 37.44g of tetrabutyl titanate to 100ml of anhydrous ethanol and disperse thoroughly to obtain solution A.

[0079] S2, 0.5 mol / L hydrochloric acid is added dropwise to solution A and dispersed thoroughly to obtain solution B. The initial pH of solution B is 3.7.

[0080] S3, 0.5 mol / L sodium hydroxide solution was added dropwise to solution B to obtain TiO2 sol. The obtained TiO2 sol was allowed to stand for 0.5 h to gel, and TiO2 gel was obtained. The TiO2 gel was aged at 25℃ for 48 h, solvent was replaced and supercritical CO2 drying was performed to obtain TiO2 aerogel. The initial pH of solution C was 10.5.

[0081] S4. The obtained TiO2 aerogel was heated to 900℃ at a heating rate of 5℃ / min under argon atmosphere protection and held at the temperature for 120min. The argon was then switched to a mixed gas (CH4 5%, NH3 20%, and H2 75%) to start the carbonitriding experiment. After reacting for 3h, the gas was switched back to argon and the temperature was lowered to 500℃ at a cooling rate of 5℃ / min and then cooled to room temperature with the furnace to obtain titanium carbonitriding aerogel.

[0082] Figure 2 The XRD pattern of the obtained Ti(C,N,O) aerogel is shown in the figure. The peak at 27° is a characteristic peak of titanium dioxide rutile, and the peaks at 36°, 39°, 42.3°, and 61° are characteristic peaks of Ti(C,N,O), but they are different from those of Ti(C,N,O). Figure 1The characteristic peaks in the samples show that the Ti(C,N,O) aerogel obtained in Comparative Example 1 has a higher titanium dioxide content and a lower titanium carbonitride content. This indicates that the conversion rate of the preparation method in Comparative Example 1 is lower than that in Example 1. This demonstrates that the present invention, using high-valence metal oxides as catalysts, can lower the TiO2 carbonization temperature, increase the carbonization rate, and improve the Ti(C,N,O) content in the finished product.

[0083] The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A method for preparing titanium carbonitride aerogel, characterized in that: Includes the following steps: S1. Add the titanium source to anhydrous ethanol and mix well to obtain solution A; S2. Add the acidic substance to solution A and mix well to obtain solution B; S3. Add the alkaline solution to solution B to obtain TiO2 sol. After the TiO2 sol is allowed to stand and gel, TiO2 gel is obtained. After aging, solvent replacement and supercritical CO2 drying, TiO2 aerogel is obtained. S4. Add metal oxide catalyst and carbon source to TiO2 aerogel, heat TiO2 aerogel to 900~1000℃ under argon atmosphere and then keep it at a constant temperature. After the isothermal treatment, switch argon to mixed gas for carbonitriding treatment. After the treatment, switch back to argon and cool to 500~600℃ and then cool to room temperature with the furnace to obtain titanium carbonitriding aerogel. The mixed gas contains a carbon source gas, a nitrogen source gas, and a reactant gas; The catalyst is one or more of Mn2O7, Fe3O4, Co3O4 and Al2O3, and the amount of catalyst added is 5-10% of the weight of TiO2 aerogel; The heating rate is 5~30℃ / min, the isothermal treatment time is 30~120min, the reaction time is 0.5~6h, and the cooling rate is 5~30℃ / min.

2. The method for preparing titanium carbonitride aerogel as described in claim 1, characterized in that: The titanium source is one or more of tetrabutyl titanate, tetraethyl titanate, and titanium tetrachloride.

3. The method for preparing titanium carbonitride aerogel as described in claim 1, characterized in that: The acidic substance is one or more of organic acids, inorganic acids, and acidic gases; the organic acid is formic acid, acetic acid, oxalic acid, or lactic acid; the inorganic acid is sulfuric acid, nitric acid, or hydrochloric acid; and the acidic gas is sulfur oxides, nitrogen oxides, or carbon dioxide.

4. The method for preparing titanium carbonitride aerogel as described in claim 1, characterized in that: The alkaline solution is one or more of organic and inorganic alkaline solutions; the organic alkaline solution is ethylenediamine solution, triethanolamine solution or triethylenetetramine solution, and the inorganic alkaline solution is sodium hydroxide solution, potassium hydroxide solution, calcium hydroxide solution or ammonia water.

5. The method for preparing titanium carbonitride aerogel as described in claim 1, characterized in that: The carbon source is one or more of carbon black, carbon nanotubes, C60, fullerene, graphite and graphene, the carbon source particle size D90 is 0.1~200nm, and the amount of carbon source added is 2~6% of the weight of TiO2 aerogel.

6. The method for preparing titanium carbonitride aerogel as described in claim 1, characterized in that: The carbon source gas is CH4 or C2H4; the nitrogen source gas is NH3 or N2; the reactant gas is H2; the proportion of each gas component in the mixed gas is: 4-8% carbon source gas, 5-20% nitrogen source gas, and 75-85% reactant gas.

7. Titanium carbonitride aerogel prepared by the method according to any one of claims 1-6.

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