A method for preparing nano-aluminum oxide powder

Abstract

The application discloses a kind of nano-alumina powder preparation methods, comprising the following steps: aluminum isopropoxide is mixed with ethanol to prepare first aluminum-containing compound solution;First aluminum-containing compound solution is added to oily solvent mixture, to obtain second aluminum-containing compound solution;Deionized water is slowly added to second aluminum-containing compound solution mixture, then adjust pH, to obtain aluminum sol;The aluminum sol is sprayed by flame combustion device Combustion, to obtain nano-alumina powder;The nano-alumina powder particle size is 50-350nm;Alumina content is ≥99.99%;Realize the preparation of nano-alumina powder, and alumina powder particle size distribution is relatively uniform.

Description

Technical Field

[0001] This invention relates to the field of nano-alumina powder technology, and in particular to a method for preparing nano-alumina powder. Background Technology

[0002] Nano-alumina powder has the characteristics of porosity, high dispersion, high activity, high hardness, and good dimensional stability, and has wide applications in ceramics, electronics, chemical catalysis, biomedicine and other fields.

[0003] The main challenge in the traditional preparation of nano-alumina powder lies in achieving narrow particle size distribution control, which requires suppressing both agglomeration and secondary growth: differences in precursor hydrolysis-condensation kinetics lead to primary particle size dispersion; driven by high surface energy, van der Waals forces and hydrogen bonds between particles induce hard agglomeration, forming a secondary structure that is difficult to deagglomerate.

[0004] Therefore, how to prepare nano-alumina powder with a relatively uniform particle size distribution has become a problem that urgently needs to be solved in this field. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a nano-alumina powder, which enables the preparation of nano-alumina powder with a relatively uniform particle size distribution.

[0006] This invention provides a method for preparing nano-alumina powder, comprising the following steps: A solution of the first aluminum-containing compound was prepared by mixing aluminum isopropoxide with ethanol; The first aluminum-containing compound solution was added to an oily solvent and mixed to obtain the second aluminum-containing compound solution; Deionized water was slowly added to the second aluminum-containing compound solution and mixed, and then the pH was adjusted to obtain aluminum sol. The aluminum sol was sprayed and burned using a flame combustion device to obtain nano-alumina powder. The nano-alumina powder has a particle size of 50-350 nm and an alumina content of ≥99.99%. The preferred particle size of nano-alumina powder is 50-200 nm.

[0007] Compared with the prior art, the present invention has the following advantages: by mixing aluminum isopropoxide with ethanol to prepare a first aluminum-containing compound solution, aluminum isopropoxide is uniformly dispersed in the first aluminum-containing compound solution and will not be hydrolyzed; By mixing the first aluminum-containing compound solution with an oily solvent and then slowly adding deionized water, the hydrolysis rate of aluminum isopropoxide is slower, and the deionized water and aluminum isopropoxide are uniformly combined, avoiding the problem that some aluminum isopropoxide hydrolyzes quickly while some aluminum isopropoxide hydrolyzes very slowly with water; thus, the aluminum hydroxide particles obtained by the hydrolysis of aluminum isopropoxide are smaller and more uniform in size. Nano-alumina powder is obtained by spraying and burning the aluminum sol through a flame combustion device. This process enables the preparation of alumina from aluminum sol through spontaneous combustion. The resulting alumina powder has a small particle size, and the flow rate of the aluminum sol into the flame combustion device is stable, which further facilitates the preparation of uniform nano-alumina powder particle size. Furthermore, the oily solvent in the aluminum sol helps to prevent the aluminum hydroxide sol particles from increasing in size before they spontaneously combust in the flame combustion device, and also helps to achieve stable spontaneous combustion of the aluminum sol. The final result is the preparation of nano-alumina powder with small and relatively uniform particle size.

[0008] Furthermore, the molar ratio of aluminum isopropoxide to ethanol is 1:(2-5); the oily solvent is butyl acetate or salicylic acid; The volume ratio of the oily solvent to ethanol is (1-1.2):1.

[0009] Further aluminum sol preparation processes include: Add deionized water to the second aluminum-containing compound solution while stirring. After adding deionized water, an acidic catalyst is added to adjust the pH value to 3-5 to obtain aluminum sol; The molar ratio of deionized water to aluminum isopropoxide is (1-3):1; When adding deionized water to the second aluminum-containing compound solution, the flow rate of deionized water is 60-180 g / min; The acidic catalyst is one or more short-chain carboxylic acids; preferably, the short-chain carboxylic acid is acetic acid or propionic acid.

[0010] Furthermore, after adding a dispersant to the aluminum sol and mixing, the aluminum sol is then passed through a fire... The flame combustion device performs spray combustion; The flow agent includes polyvinylpyrrolidone or polyethylene glycol; The volume ratio of the dispersant to ethanol is 1:(0.05-0.2).

[0011] The advantage of the previous step is that the addition of a dispersant helps to avoid the problem of unstable flow rate of aluminum sol during delivery into the flame combustion device due to the viscosity of aluminum sol.

[0012] Further, the organoaluminum salt was mixed with ethanol at a molar ratio of 1:(5-8); then an acidic catalyst was added to adjust the pH to 3-5 to obtain a third aluminum-containing compound solution. The third aluminum-containing compound solution was added to the aluminum sol solution and stirred. The aluminum sol solution is then sprayed and burned using a flame combustion device; The molar ratio of the organoaluminum salt to aluminum isopropoxide is 1:(15-25). The organoaluminum salt is one of the short-chain aluminum carboxylate; The acidic catalyst is one or more short-chain carboxylic acids; The preferred short-chain carboxylic acid includes one of aluminum acetate and aluminum isopropionate.

[0013] The beneficial effect of the previous step is that by adding the third aluminum-containing compound solution to the aluminum sol solution and stirring, the organic aluminum salt is uniformly added to the aluminum sol solution, thereby achieving the hydrolysis of the organic aluminum salt in the aluminum sol. The hydrolysis rate is faster than that of aluminum isopropoxide in the second aluminum-containing compound solution. The aluminum hydroxide hydrosol obtained by the hydrolysis of organic aluminum salt has a larger particle size than that obtained by the hydrolysis of aluminum isopropoxide. It is also beneficial to have the larger-sized aluminum hydroxide hydrosol obtained by the hydrolysis of organic aluminum salt coated on the outside of the smaller-sized aluminum hydroxide hydrosol obtained by the hydrolysis of aluminum isopropoxide. By using a molar ratio of 1:(15-25) between the organoaluminum salt and aluminum isopropoxide, less organoaluminum salt is added, resulting in a lower proportion of aluminum hydroxide sol produced by the hydrolysis of organoaluminum salt. This also helps to avoid excessively large particle size of the aluminum hydroxide sol produced by the hydrolysis of organoaluminum salt and to prevent precipitation. By coating a small amount of aluminum hydroxide sol with a small amount of large-particle-size aluminum hydroxide sol, it is beneficial to generate a small amount of large-particle-size aluminum hydroxide powder around the smaller-particle-size aluminum hydroxide powder when the aluminum sol is burned to generate nano-alumina powder, thereby avoiding the agglomeration problem caused by the small particle size of the nano-alumina powder.

[0014] Furthermore, the viscosity of the aluminum sol solution is (50-200) mPa·s, and the mass fraction of aluminum hydroxide particles in the aluminum sol is 20-40% based on aluminum oxide; the particle size is 20-50 nm. Preferably, the alumina nanoparticles have a particle size of 50-200 nm; wherein the mass fraction of alumina nanoparticles with a particle size of 50-150 nm is 50-60%, and the mass fraction of alumina nanoparticles with a particle size of 150-200 nm is 40-50%.

[0015] Furthermore, the viscosity of the aluminum sol solution is (50-180) mPa·s, and the mass fraction of aluminum hydroxide particles in the aluminum sol is 20-35% based on alumina; the mass ratio of aluminum hydroxide particles with a particle size of 20-50 nm to aluminum hydroxide particles with a particle size of 100-300 nm is (15-25):1; preferably, the mass fraction of alumina powder with a particle size of 50-150 nm is 75-85%, the mass fraction of alumina powder with a particle size of 150-200 nm is 10-19%, and the mass fraction of alumina powder with a particle size of 200-350 nm is 3-6%.

[0016] Furthermore, the flame combustion device includes a combustion chamber, an aluminum sol solution injection device, a flame generating device, a protective gas injection device, and an oxidizing gas injection device; The aluminum sol solution injection device includes an aluminum sol solution nozzle; the flame generating device includes a first flame nozzle and a second flame nozzle; the protective gas injection device includes a first protective gas nozzle and a second protective gas nozzle; the combustion-supporting gas injection device includes a first combustion-supporting gas nozzle and a second combustion-supporting gas nozzle. The bottom of the combustion chamber cavity is provided with a sixth through hole, a fourth through hole, a second through hole, a first through hole, a third through hole, a fifth through hole, and a seventh through hole in sequence from one side to the other. The aluminum sol solution nozzle, the first combustion-supporting gas nozzle, the second combustion-supporting gas nozzle, the first flame nozzle, the second flame nozzle, the first protective gas nozzle, and the second protective gas nozzle are respectively connected to the internal space of the combustion chamber through the first through hole, the second through hole, the third through hole, the fourth through hole, the fifth through hole, the sixth through hole, and the seventh through hole.

[0017] Furthermore, the process of spraying and burning the aluminum sol solution using a flame combustion device includes the following steps: Turn on the protective gas injection device and inject protective gas into the combustion chamber through the first protective gas nozzle and the second protective gas nozzle; The flame generating device is activated, and flames are injected into the combustion chamber through the first flame nozzle and the second flame nozzle. Flames ejected from the first and second flame nozzles relative to each other; Turn on the aluminum sol solution injection device and spray the atomized aluminum sol solution into the combustion chamber through the aluminum sol solution nozzle. Turn on the combustion gas injection device and inject combustion gas into the combustion chamber through the first combustion gas nozzle and the second combustion gas nozzle. The first and second combustion-supporting gas nozzles spray combustion-supporting gases relative to each other. The flow rate of the aluminum sol solution entering the solution atomization chamber through the first infusion line is 5-15 L / min; The flow rate of the atomizing gas entering the solution atomization chamber is 15-25 L / min; The temperature inside the combustion chamber is maintained at 800-1200℃ by injecting flames into the combustion chamber through the first flame nozzle and the second flame nozzle.

[0018] The beneficial effect of the previous step is that, through the flame combustion device including the combustion chamber cavity, aluminum sol solution injection device, flame generating device, protective gas injection device, and combustion-supporting gas injection device, the aluminum sol can be stably burned in the combustion chamber cavity to generate nano-alumina. The aluminum sol solution injection device enables the stable injection of aluminum sol or aluminum sol mixed with combustion-supporting gas into the combustion chamber cavity for combustion at the aluminum sol solution nozzle. The flame generating device sprays flames into the combustion chamber through the first flame nozzle and the second flame nozzle, thereby igniting the aluminum sol and maintaining the temperature around the aluminum sol at 800-1200℃. The combustion-supporting gas is injected into the combustion chamber through the first combustion-supporting gas nozzle and the second combustion-supporting gas nozzle using a combustion-supporting gas injection device. The protective gas injection device enables the injection of combustion-supporting gas into the combustion chamber cavity through the first protective gas nozzle and the second protective gas nozzle. The combustion chamber cavity is provided with a sixth through hole, a fourth through hole, a second through hole, a first through hole, a third through hole, a fifth through hole, and a seventh through hole in sequence from one side to the other. This allows the aluminum sol solution nozzle to be in the middle, the first combustion-supporting gas nozzle and the second combustion-supporting gas nozzle to be located on both sides of the aluminum sol solution nozzle, the first flame nozzle and the second flame nozzle to spray flames into the combustion chamber cavity on both sides of the first combustion-supporting gas nozzle and the second combustion-supporting gas nozzle, and the first protective gas nozzle and the second protective gas nozzle to be located on both sides of the first flame nozzle and the second flame nozzle. This ensures that the first and second combustion-supporting gas nozzles provide sufficient combustion-supporting gas to the burning aluminum sol, thereby achieving complete combustion of the aluminum sol. It also facilitates the upward movement of the burning aluminum sol flame towards the top of the combustion chamber, which in turn facilitates the upward movement of the generated nano-alumina powder towards the top of the combustion chamber, thus promoting the collection of the generated nano-alumina. The injected combustion-supporting gas also helps to disperse the generated nano-alumina, thus avoiding the problem of nano-alumina agglomeration. The combustion-supporting gas also helps to stabilize the flames ejected from the first and second flame nozzles, and the flames are concentrated upwards, which helps to prevent the flames from spreading to both sides. The protective gases ejected from the first protective gas nozzle and the second protective gas nozzle are more conducive to the upward concentration of the flames ejected from the first flame nozzle and the second flame nozzle, and are more conducive to preventing the flames from dispersing to both sides. This helps to achieve a uniform particle size distribution in the prepared nano-alumina and helps to avoid the agglomeration of nano-alumina.

[0019] Furthermore, the top of the combustion chamber is provided with a discharge port, which is connected to a negative pressure discharge device; the bottom of the combustion chamber is provided with an electric spark outlet between the fourth and fifth through holes.

[0020] The beneficial effect of the previous step is that by connecting the discharge port to the negative pressure discharge device, the nano-alumina generated by the combustion of aluminum sol can leave the combustion chamber cavity from the top of the cavity and be collected. This further helps to avoid the excessive increase in the particle size of nano-alumina caused by prolonged heating in the combustion chamber cavity.

[0021] Furthermore, the discharge port of the combustion chamber is connected to a filtering and dispersing device, which is connected to a negative pressure discharge device. The filtration and dispersion device includes a filtration and dispersion chamber, with a filtration and dispersion chamber inlet at the bottom and a filtration and dispersion chamber outlet at the top. The inlet of the dispersion chamber is connected to the outlet of the combustion chamber; the outlet of the dispersion chamber is connected to the negative pressure discharge device. The inlet of the dispersion chamber is provided with a first alumina fiber filter membrane; the inlet of the dispersion chamber is provided with a second alumina fiber filter membrane; The pore size of the first alumina fiber filter membrane is 0.5-2 μm, and the pore size of the second alumina fiber filter membrane is 0.2-0.4 μm; The sidewall of the dispersion chamber is provided with several pulse air inlets; Furthermore, the intake pressure of the pulse air inlet of the filtration and dispersion device is 4-6 kPa, and air is introduced once every 5-10 minutes.

[0022] The advantage of the previous step is that the nano-alumina powder is dispersed and collected by the filtration and dispersion device, thus avoiding the agglomeration of the nano-alumina powder.

[0023] Furthermore, the negative pressure discharge device includes a negative pressure pump, a gas-powder separator, a gas-powder conveying pipeline, and an exhaust pipeline; The air-powder separator includes a separator inlet, a separator powder outlet, and a separator air outlet; One end of the gas-powder conveying pipeline is connected to the inlet of the dispersion chamber, and the other end of the gas-powder conveying pipeline is connected to the inlet of the separator; the outlet of the separator is connected to the exhaust pipeline, and the gas-powder conveying pipeline is connected to the negative pressure pump.

[0024] The advantage of the previous step is that the nano-alumina powder is collected by the negative pressure discharge device, and excess waste is discharged. Detailed Implementation

[0025] To better understand the technical solution of the present invention, the present invention will be further described below with reference to specific embodiments.

[0026] Example 1: This embodiment provides a method for preparing nano-alumina powder, including the following steps: A solution of the first aluminum-containing compound was prepared by mixing aluminum isopropoxide with ethanol; The first aluminum-containing compound solution was mixed with an oily solvent to obtain a second aluminum-containing compound solution; the molar ratio of aluminum isopropoxide to ethanol was 1:3; the oily solvent was butyl acetate; and the volume ratio of the oily solvent to ethanol was 1.1:1.

[0027] Deionized water was slowly added to the second aluminum-containing compound solution and mixed, and then the pH was adjusted to obtain aluminum sol. The aluminum sol preparation process includes: adding deionized water to a second aluminum-containing compound solution while stirring; after adding deionized water, adding an acidic catalyst to adjust the pH value to 3-5 to obtain aluminum sol; the molar ratio of deionized water to aluminum isopropoxide is 2:1. When deionized water is added to the second aluminum-containing compound solution, the flow rate of deionized water is 120 g / min. The acidic catalyst is a short-chain carboxylic acid, and the short-chain carboxylic acid is acetic acid.

[0028] The viscosity of the aluminum sol solution is 225 mPa·s, and the mass fraction of aluminum hydroxide particles in the aluminum sol is 35% based on aluminum oxide; the particle size is 20-50 nm.

[0029] The aluminum sol was sprayed and burned using a flame combustion device to obtain nano-alumina powder. The flame combustion device includes a combustion chamber, an aluminum sol solution injection device, a flame generating device, a protective gas injection device, and an oxidizing gas injection device; The aluminum sol solution injection device includes an aluminum sol solution nozzle; the flame generating device includes a first flame nozzle and a second flame nozzle; the protective gas injection device includes a first protective gas nozzle and a second protective gas nozzle; the combustion-supporting gas injection device includes a first combustion-supporting gas nozzle and a second combustion-supporting gas nozzle. The bottom of the combustion chamber cavity is provided with a sixth through hole, a fourth through hole, a second through hole, a first through hole, a third through hole, a fifth through hole, and a seventh through hole in sequence from one side to the other. The aluminum sol solution nozzle, the first combustion-supporting gas nozzle, the second combustion-supporting gas nozzle, the first flame nozzle, the second flame nozzle, the first protective gas nozzle, and the second protective gas nozzle are respectively connected to the internal space of the combustion chamber through the first through hole, the second through hole, the third through hole, the fourth through hole, the fifth through hole, the sixth through hole, and the seventh through hole.

[0030] The process of spraying and burning the aluminum sol solution through a flame combustion device includes the following steps: Turn on the protective gas injection device and inject protective gas into the combustion chamber through the first protective gas nozzle and the second protective gas nozzle; The flame generating device is activated, and flames are injected into the combustion chamber through the first flame nozzle and the second flame nozzle. Flames ejected from the first and second flame nozzles relative to each other; Turn on the aluminum sol solution injection device and spray the atomized aluminum sol solution into the combustion chamber through the aluminum sol solution nozzle. Turn on the combustion gas injection device and inject combustion gas into the combustion chamber through the first combustion gas nozzle and the second combustion gas nozzle. The first and second combustion-supporting gas nozzles spray combustion-supporting gases relative to each other. The flow rate of the aluminum sol solution entering the solution atomization chamber through the first infusion line is 10 L / min; The flow rate of the atomizing gas entering the solution atomization chamber is 20 L / min; The temperature inside the combustion chamber is maintained at 1000℃ by injecting flames into the combustion chamber through the first flame nozzle and the second flame nozzle.

[0031] The nano-alumina powder has a particle size of 50-200 nm; of which the mass fraction of alumina powder with a particle size of 50-150 nm is 55%, and the mass fraction of alumina powder with a particle size of 150-200 nm is 45%; the alumina content is ≥99.99%.

[0032] Example 2: The content that is the same as in Example 1 will not be repeated here; the differences between this embodiment and Example 1 are as follows: The method for preparing nano-alumina powder provided in this embodiment further includes: After adding a dispersant to the aluminum sol and mixing, the aluminum sol is then passed through a fire... The flame combustion device performs spray combustion; The flow agent includes polyvinylpyrrolidone; The volume ratio of the dispersant to ethanol is 1:0.125.

[0033] The molar ratio of aluminum isopropoxide to ethanol is 1:2.5; the oily solvent is salicylic acid; and the volume ratio of the oily solvent to ethanol is 1.05:1.

[0034] Deionized water was added to the second aluminum-containing compound solution while stirring; after adding deionized water, an acidic catalyst was added to adjust the pH to 3-5 to obtain aluminum sol; the molar ratio of deionized water to aluminum isopropoxide was 1.5:1. When deionized water is added to the second aluminum-containing compound solution, the flow rate of deionized water is 70 g / min. The acidic catalyst is a short-chain carboxylic acid, and the short-chain carboxylic acid is propionic acid.

[0035] The viscosity of the aluminum sol solution is 160 mPa·s, and the mass fraction of aluminum hydroxide particles in the aluminum sol is 39% based on aluminum oxide.

[0036] The flow rate of the aluminum sol solution entering the solution atomization chamber through the first infusion line is 13 L / min; The flow rate of the atomizing gas entering the solution atomization chamber is 23 L / min; The temperature inside the combustion chamber is maintained at 1100℃ by injecting flames into the combustion chamber through the first flame nozzle and the second flame nozzle.

[0037] The nano-alumina powder has a particle size of 50-200 nm; of which the mass fraction of alumina powder with a particle size of 50-150 nm is 58%, and the mass fraction of alumina powder with a particle size of 150-200 nm is 42%; the alumina content is ≥99.99%.

[0038] Example 3: The content that is the same as in Example 1 will not be repeated here; the differences between this embodiment and Example 1 are as follows: The method for preparing nano-alumina powder provided in this embodiment further includes: The organoaluminum salt was mixed with ethanol at a molar ratio of 1:7; then an acidic catalyst was added to adjust the pH to 3-5 to obtain a third aluminum-containing compound solution. The third aluminum-containing compound solution was added to the aluminum sol solution and stirred. The aluminum sol solution is then sprayed and burned using a flame combustion device; The molar ratio of the organoaluminum salt to aluminum isopropoxide is 1:20; The organoaluminum salt is one of the short-chain aluminum carboxylatees, and the short-chain carboxylate is aluminum acetate; The acidic catalyst is acetic acid; The viscosity of the aluminum sol solution is 170 mPa·s. The aluminum hydroxide particles, calculated as aluminum oxide, are located on aluminum... The sol has a mass fraction of 34%; the mass ratio of aluminum hydroxide particles with a particle size of 20-50 nm to aluminum hydroxide particles with a particle size of 100-500 nm is 20:1.

[0039] Deionized water was added to the second aluminum-containing compound solution while stirring; after the deionized water was added, an acidic catalyst was added to adjust the pH to 3-5 to obtain an aluminum sol; the molar ratio of deionized water to aluminum isopropoxide was 2.8:1. When deionized water is added to the second aluminum-containing compound solution, the flow rate of deionized water is 70 g / min. The flow rate of the aluminum sol solution entering the solution atomization chamber through the first infusion line is 12 L / min; The flow rate of the atomizing gas entering the solution atomization chamber is 18 L / min; The temperature inside the combustion chamber is maintained at 1150°C by injecting flames into the combustion chamber through the first flame nozzle and the second flame nozzle.

[0040] The combustion chamber cavity is provided with a discharge port at the top, which is connected to a negative pressure discharge device; the combustion chamber cavity is provided with an electric spark outlet at the bottom between the fourth and fifth through holes.

[0041] The discharge port of the combustion chamber is connected to a filtration and dispersion device, which is connected to a negative pressure discharge device. The filtration and dispersion device includes a filtration and dispersion chamber, with a filtration and dispersion chamber inlet at the bottom and a filtration and dispersion chamber outlet at the top. The inlet of the dispersion chamber is connected to the outlet of the combustion chamber; the outlet of the dispersion chamber is connected to the negative pressure discharge device. The inlet of the dispersion chamber is provided with a first alumina fiber filter membrane; the inlet of the dispersion chamber is provided with a second alumina fiber filter membrane; The first alumina fiber filter membrane has a pore size of 1 μm, and the second alumina fiber filter membrane has a pore size of 0.38 μm; The sidewall of the dispersion chamber is provided with several pulse air inlets; The pulse air inlet of the filtration and dispersion device has an air inlet pressure of 5 kPa and air is introduced once every 8 minutes.

[0042] The negative pressure discharge device includes a negative pressure pump, a gas-powder separator, a gas-powder conveying pipeline, and an exhaust pipeline; The air-powder separator includes a separator inlet, a separator powder outlet, and a separator air outlet; One end of the gas-powder conveying pipeline is connected to the inlet of the dispersion chamber, and the other end of the gas-powder conveying pipeline is connected to the inlet of the separator; the outlet of the separator is connected to the exhaust pipeline, and the gas-powder conveying pipeline is connected to the negative pressure pump.

[0043] The nano-alumina powder has a particle size of 50-350nm; the mass fraction of alumina powder with a particle size of 50-150nm is 85%, the mass fraction of alumina powder with a particle size of 150-200nm is 11%, and the mass fraction of alumina powder with a particle size of 200-350nm is 4%; the alumina content is ≥99.99%.

[0044] The above description is merely a preferred embodiment of this application and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to the technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the inventive concept. For example, the above-described features have similar functions to (but are not limited to) those disclosed in this application.

Claims

1. A method for preparing nano-alumina powder, characterized in that, Includes the following steps: A solution of the first aluminum-containing compound was prepared by mixing aluminum isopropoxide with ethanol; The first aluminum-containing compound solution was added to an oily solvent and mixed to obtain the second aluminum-containing compound solution; Deionized water was slowly added to the second aluminum-containing compound solution and mixed, and then the pH was adjusted to obtain aluminum sol. The aluminum sol was sprayed and burned using a flame combustion device to obtain nano-alumina powder. The nano-alumina powder has a particle size of 50-350 nm and an alumina content of ≥99.99%.

2. The method for preparing nano-alumina powder according to claim 1, wherein the... The characteristic is that the molar ratio of aluminum isopropoxide to ethanol is 1:(2-5). The oily solvent is butyl acetate or salicylic acid; The volume ratio of the oily solvent to ethanol is (1-1.2):

1.

3. The method for preparing nano-alumina powder according to claim 2, wherein the... The characteristic is that the aluminum sol preparation process includes: Add deionized water to the second aluminum-containing compound solution while stirring. After adding deionized water, an acidic catalyst is added to adjust the pH value to 3-5 to obtain aluminum sol; The molar ratio of deionized water to aluminum isopropoxide is (1-3):1; When adding deionized water to the second aluminum-containing compound solution, the flow rate of deionized water is 60-180 g / min; The acidic catalyst is one or more short-chain carboxylic acids.

4. The method for preparing nano-alumina powder according to claim 1, characterized in that, After adding a dispersant to the aluminum sol and mixing, the aluminum sol is then sprayed and burned through a flame combustion device. The flow agent includes polyvinylpyrrolidone or polyethylene glycol; The volume ratio of the dispersant to ethanol is 1:(0.05-0.2).

5. The method for preparing nano-alumina powder according to claim 1, characterized in that, The organoaluminum salt was mixed with ethanol at a molar ratio of 1:(5-8); then an acidic catalyst was added to adjust the pH to 3-5 to obtain a third aluminum-containing compound solution. The third aluminum-containing compound solution was added to the aluminum sol solution and stirred. The aluminum sol solution is then sprayed and burned using a flame combustion device; The molar ratio of the organoaluminum salt to aluminum isopropoxide is 1:(15-25). The organoaluminum salt is one of the short-chain aluminum carboxylate; The acidic catalyst is one or more short-chain carboxylic acids.

6. The method for preparing nano-alumina powder according to claim 1, characterized in that, The viscosity of the aluminum sol solution is (50-200) mPa·s, and the mass fraction of aluminum hydroxide particles in the aluminum sol is 20-40% based on aluminum oxide; the particle size is 20-50 nm.

7. The method for preparing nano-alumina powder according to claim 5, characterized in that, The viscosity of the aluminum sol solution is (50-180) mPa·s, and the mass fraction of aluminum hydroxide particles in the aluminum sol is 20-35% based on aluminum oxide; the mass ratio of aluminum hydroxide particles with a particle size of 20-50 nm to that with a particle size of 100-300 nm is (15-25):

1.

8. The method for preparing nano-alumina powder according to claim 1, characterized in that... It lies in, The flame combustion device includes a combustion chamber, an aluminum sol solution injection device, a flame generating device, a protective gas injection device, and an oxidizing gas injection device; The aluminum sol solution injection device includes an aluminum sol solution nozzle; the flame generating device includes a first flame nozzle and a second flame nozzle; the protective gas injection device includes a first protective gas nozzle and a second protective gas nozzle; the combustion-supporting gas injection device includes a first combustion-supporting gas nozzle and a second combustion-supporting gas nozzle. The bottom of the combustion chamber cavity is provided with a sixth through hole, a fourth through hole, a second through hole, a first through hole, a third through hole, a fifth through hole, and a seventh through hole in sequence from one side to the other. The aluminum sol solution nozzle, the first combustion-supporting gas nozzle, the second combustion-supporting gas nozzle, the first flame nozzle, the second flame nozzle, the first protective gas nozzle, and the second protective gas nozzle are respectively connected to the internal space of the combustion chamber through the first through hole, the second through hole, the third through hole, the fourth through hole, the fifth through hole, the sixth through hole, and the seventh through hole.

9. The method for preparing nano-alumina powder according to claim 8, characterized in that... It lies in, The aluminum sol solution spraying device also includes an aluminum sol solution storage tank, a pump body, a first inlet pipeline, a solution atomization chamber, and a second inlet pipeline; the solution atomization chamber includes an inlet, a first air inlet, and an outlet. The pump body's inlet is connected to an aluminum sol solution storage tank, and the pump body's outlet is connected to the inlet of the solution atomization chamber via a first inlet pipeline. The solution atomization chamber's outlet is connected to the aluminum sol solution nozzle via a second inlet pipeline. The solution atomization chamber's first air inlet is connected to an atomizing gas delivery pipe. The atomizing gas is air or oxygen. The protective gas ejected from the first and second protective gas nozzles of the protective gas injection device is an inert gas; The combustion-supporting gas ejected from the first and second combustion-supporting gas nozzles of the combustion-supporting gas injection device is oxygen.

10. The method for preparing nano-alumina powder according to claim 9, characterized in that, The process of spraying and burning the aluminum sol solution through a flame combustion device includes the following steps: Turn on the protective gas injection device and inject protective gas into the combustion chamber through the first protective gas nozzle and the second protective gas nozzle; The flame generating device is activated, and flames are injected into the combustion chamber through the first flame nozzle and the second flame nozzle. Flames ejected from the first and second flame nozzles relative to each other; Turn on the aluminum sol solution injection device and spray the atomized aluminum sol solution into the combustion chamber through the aluminum sol solution nozzle. Turn on the combustion gas injection device and inject combustion gas into the combustion chamber through the first combustion gas nozzle and the second combustion gas nozzle. The first and second combustion-supporting gas nozzles spray combustion-supporting gases relative to each other. The flow rate of the aluminum sol solution entering the solution atomization chamber through the first infusion line is 5-15 L / min; The flow rate of the atomizing gas entering the solution atomization chamber is 15-25 L / min; The temperature inside the combustion chamber is maintained at 800-1200℃ by injecting flames into the combustion chamber through the first flame nozzle and the second flame nozzle.