Preparation method of nano-aluminum oxide

Abstract

The application provides a preparation method of nano-alumina and relates to the technical field of metal oxides. The preparation method comprises the steps of gel preparation, heat treatment and cooling, washing, drying and the like. The application realizes preparation of nano-alumina products with high specific surface area and high stability, and the prepared nano-alumina has the advantages of uniform particle size distribution and good crystallinity, and is beneficial to promoting application and popularization of the nano-alumina in various fields.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metal oxide, in particular to a preparation method of nano-alumina. BACKGROUND

[0002] Nano-alumina (Al2O3) is an important inorganic nanomaterial with eleven kinds of crystals, including alpha, beta, gamma, delta, eta, theta, kappa and chi. Specific surface area refers to the surface area of a unit mass of a substance in contact with the outside world, which is an important parameter for measuring the surface activity of a substance. For nano-alumina, the larger the specific surface area, the more substances can be contacted and reacted with a unit mass of alumina, thereby improving its performance and efficiency in multiple fields such as catalysis, sensing, driving, optics, electrochemical energy storage and conversion. For example, in a catalyst carrier, the high specific surface area of nano-alumina can provide more active sites, increase the utilization rate and selectivity of the catalyst; in a coating, the high specific surface area of nano-alumina can improve the wear resistance and anti-pollution of the coating; in a battery, the high specific surface area of nano-alumina can increase the capacitance and conductivity of the electrode.

[0003] However, the current method for preparing nano-alumina has some problems, such as uneven particle size distribution, low specific surface area, and poor crystallinity. Therefore, it is necessary to provide an efficient method for preparing nano-alumina with high specific surface area to solve the problems in the prior art. SUMMARY

[0004] To solve the above problems, the present application provides a preparation method of nano-alumina, which is simple in process and low in equipment requirement, and can realize the preparation of nano-alumina with high specific surface area.

[0005] The preparation method of nano-alumina according to the present application comprises the following steps:

[0006] S1, mixing aluminum alkoxide with a solvent, then adding deionized water drop by drop, and then aging to obtain alumina alcohol gel;

[0007] S2, rapidly cooling the hydroxide alcohol gel to room temperature after the first heat treatment, then heating and performing the second heat treatment, and then cooling, washing and drying after the treatment to obtain nano-alumina.

[0008] Further, the aluminum alkoxide is one or both of aluminum triisopropoxide and aluminum triethoxide. Preferably, the aluminum alkoxide is aluminum triisopropoxide.

[0009] Further, the solution is an alcohol solution and an aromatic solution.

[0010] Further, the alcohol solution is one or more of methanol, ethanol and propanol. Preferably, the alcohol solution is methanol.

[0011] Further, the aromatic solution is one or more of toluene, xylene, ethylbenzene, styrene. Preferably, the aromatic solution is toluene.

[0012] Further, the volume ratio of the alcohol solution to the aromatic solution in the solvent is 1:2-5.

[0013] Further, the concentration of the aluminum alcohol salt in the solvent is 5-20 g / L. Preferably, the concentration of the aluminum alcohol salt in the solvent is 5-10 g / L.

[0014] Further, the molar ratio of the aluminum alcohol salt to deionized water is 1:2-5.

[0015] Further, the standing aging temperature is 20-30℃, and the standing aging time is 3-5 d.

[0016] Further, the first heat treatment temperature is 150-250℃, and the holding time is 15-30 min. Preferably, the first heat treatment temperature is 200℃, and the holding time is 25 min.

[0017] Further, the second heat treatment temperature is 100-180℃, and the holding time is 4-6 h. Preferably, the second heat treatment temperature is 120℃, and the holding time is 5.5 h.

[0018] Further, the washing process is specifically as follows: first washing once with deionized water and then washing once with methanol with a concentration of 7-10 g / mL.

[0019] The present application does not strictly limit the drying temperature after washing, and the drying effect can be achieved.

[0020] Compared with the prior art, the present application has the beneficial technical effects of:

[0021] The present application realizes the preparation of high specific surface area and high stability nano-alumina products. The prepared nano-alumina has a specific surface area of >500 m 2 / g, an average pore size of 8.2-9.5 nm, and has the advantages of uniform particle size distribution and good crystallinity, which is beneficial to promote the application and popularization of nano-alumina in various fields. DETAILED DESCRIPTION

[0022] The technical solutions provided by the present application are further described below in combination with examples.

[0023] Example 1

[0024] A preparation method of nano-alumina, the steps are as follows:

[0025] S1, aging for 5 days at 25℃ after mixing aluminum isopropoxide, methanol and toluene and then adding deionized water drop by drop, to obtain an alumina alcohol gel, wherein the volume ratio of methanol to toluene is 1:5, the concentration of aluminum isopropoxide in the solvent is 5 g / L, and the molar ratio of aluminum isopropoxide to deionized water is 1:2.5;

[0026] S2, rapidly cooling to room temperature after keeping the hydroxide alcohol gel at 200℃ for 25 min, then heating to 120℃ and keeping for 5.5 h, cooling to room temperature after the treatment is completed, washing once with deionized water, then washing once with a methanol solution with a concentration of 10 g / L, and drying to obtain nano-alumina.

[0027] It is detected that the BET specific surface area of the obtained nano-alumina is 526 m 2 / g, and the average pore size is 8.2 nm.

[0028] Example 2

[0029] A method for preparing nano-alumina, comprising the following steps:

[0030] S1, aging for 3 days at 20℃ after mixing aluminum triethoxide, ethanol and ethylbenzene and then adding deionized water drop by drop, to obtain an alumina alcohol gel, wherein the volume ratio of ethanol to ethylbenzene is 1:3, the concentration of aluminum triethoxide in the solvent is 10 g / L, and the molar ratio of aluminum triethoxide to deionized water is 1:5;

[0031] S2, rapidly cooling to room temperature after keeping the hydroxide alcohol gel at 250℃ for 15 min, then heating to 100℃ and keeping for 6 h, cooling to room temperature after the treatment is completed, washing once with deionized water, then washing once with a methanol solution with a concentration of 7 g / L, and drying to obtain nano-alumina.

[0032] It is detected that the BET specific surface area of the obtained nano-alumina is 506 m 2 / g, and the average pore size is 8.5 nm.

[0033] Example 3

[0034] A method for preparing nano-alumina, comprising the following steps:

[0035] S1, aging for 5 days at 25℃ after mixing aluminum isopropoxide, propanol and styrene and then adding deionized water drop by drop, to obtain an alumina alcohol gel, wherein the volume ratio of propanol to styrene is 1:3.5, the concentration of aluminum isopropoxide in the solvent is 15 g / L, and the molar ratio of aluminum isopropoxide to deionized water is 1:2;

[0036] S2, the hydroxide alcohol gel is kept at 250°C for 30 min, then rapidly cooled to room temperature, and then heated to 120°C for 4.5 h. After the treatment is completed, the sample is cooled to room temperature, washed once with deionized water, then washed once with a methanol solution having a concentration of 8 g / L, and dried to obtain the nano-alumina.

[0037] The BET specific surface area of the obtained nano-alumina is 511 m 2 / g, and the average pore size is 9.4 nm.

[0038] Comparative Example 1

[0039] The same as Example 1, except that the toluene in the solvent is replaced with an equal amount of methanol.

[0040] The BET specific surface area of the obtained nano-alumina is 477 m 2 / g.

[0041] Comparative Example 2

[0042] The same as Example 1, except that the aging time is 1 d.

[0043] The BET specific surface area of the obtained nano-alumina is 418 m 2 / g.

[0044] Comparative Example 3

[0045] The same as Example 1, except that the aging time is 6 d.

[0046] The BET specific surface area of the obtained nano-alumina is 495 m 2 / g.

[0047] Comparative Example 4

[0048] The same as Example 1, except that the volume ratio of methanol to toluene is 1:1.

[0049] The BET specific surface area of the obtained nano-alumina is 402 m 2 / g.

[0050] Comparative Example 5

[0051] The same as Example 1, except that the methanol is replaced with an equal amount of butanol.

[0052] The BET specific surface area of the obtained nano-alumina is 451 m 2 / g.

[0053] Comparative Example 6

[0054] The same as Example 1, except that only one heat treatment is performed.

[0055] The BET specific surface area of the obtained nano-alumina is 399 m 2 / g.

[0056] The principles and implementations of the present application are described herein with specific examples. The above examples are only used to help understand the method of the present application and its core idea; meanwhile, for those skilled in the art, according to the idea of the present application, the specific implementation and application range will be changed. In summary, the content of the specification should not be understood as a limitation of the present application.

Claims

1. A method for preparing nano-aluminum oxide, characterized in that, The method comprises the following steps: S1, mixing aluminum alkoxide with solvent, then adding dropwise into deionized water, and aging to obtain an aluminum oxide alcohol gel; S2, after the first heat treatment of the aluminum oxide alcohol gel, rapidly cooling to room temperature, then heating and performing the second heat treatment, and after the treatment, cooling, washing, and drying to obtain nano-aluminum oxide; The solvent is composed as follows: The volume ratio of methanol to toluene is 1:5; or, The volume ratio of ethanol to ethylbenzene is 1:3; or, The volume ratio of propanol to styrene is 1:3.5; The aging temperature is 20-30 DEG C, and the aging time is 3-5 days; The first heat treatment temperature is 150-250 DEG C, and the holding time is 15-30 min; The second heat treatment temperature is 100-180 DEG C, and the holding time is 4-6 h.

2. The method of claim 1, wherein the nano-aluminum oxide is prepared by the steps of: The aluminum alkoxide is one or both of aluminum triisopropoxide and aluminum triethoxide. ​ 3. The method for preparing nano-alumina according to claim 1, characterized in that, The concentration of the aluminum alkoxide in the solvent is 5-20 g / L.

4. The method for preparing nano-alumina according to claim 1, characterized in that, The molar ratio of the aluminum alkoxide to deionized water is 1:2-5.