Preparation method of spherical oxide particles

Abstract

The invention relates to the technical field of nano materials, and discloses a preparation method of spherical oxide particles. The preparation method comprises the following steps: mixing a carbon nanotube, a functional structure oxide and boron oxide, and heating to obtain a molten mass containing the carbon nanotube; and cooling, so that the functional structure oxide and the boron oxide in the molten mass are subjected to phase splitting, the boron oxide is enriched in a carbon nanotube network, the functional structure oxide is separated out into liquid drops, and the liquid drops are solidified to obtain the spherical oxide particles. According to the preparation method provided by the invention, the functional structure oxide and the boron oxide are melted by heating, then the functional structure oxide and the boron oxide are split by cooling, the boron oxide is enriched towards the carbon nano tube under the wetting effect of the carbon nano tube, and the functional structure oxide is separated out under the barrier effect of the carbon nano tube; under the action of surface tension, functional structure oxide liquid drops with high sphericity degree and good dispersity are formed, and finally, the oxide nanoparticles with controllable morphology and no agglomeration phenomenon are obtained through curing.

Description

Technical Field

[0001] The present invention relates to the technical field of nanomaterials, and in particular to a method for preparing spherical oxide particles. Background Art

[0002] Nanomaterials, due to their unique physical and chemical properties, are widely used in fields such as catalysis, optoelectronics, sensors, and biomedicine. Currently, the main methods for preparing spherical oxide nanoparticles include sol-gel, hydrothermal, vapor deposition, and microemulsion. The sol-gel method involves the hydrolysis of metal alkoxides [M(OR)n, where R = Si, Ti, Al, Zr, etc.] in an acidic or alkaline alcohol solution to form an oxide sol, which is then subjected to post-treatment such as aging and drying to produce oxide nanoparticles. The hydrothermal method involves the production of oxide nanoparticles through a hydrothermal reaction. The vapor deposition method utilizes the absorption of laser light at a specific wavelength by a gas to induce a reaction in gas molecules, and then controls the formation and growth of nuclei to produce oxide nanoparticles. The microemulsion method involves the addition of surfactants to form a microemulsion system, followed by the addition of reactants, which then diffuse into the emulsion through the micelle surface, where they react and grow to form oxide nanoparticles.

[0003] The sol-gel method has mild reaction conditions and strong operability, and the oxide nanoparticles produced have good chemical uniformity and high purity. However, the metal alkoxide is expensive, the organic solvent consumption is large, and the production cost is high. In addition, during the drying process of the gel, due to the volatilization of the solvent and water, a large shrinkage stress will be generated, which can easily cause the gel to crack and agglomerate, affecting the dispersion and sphericity of the nanoparticles. The whole process is time-consuming and the production efficiency is low. The oxide nanoparticles produced by the hydrothermal method have good crystal quality and narrow particle size distribution, but the equipment requirements are high, the reaction conditions are complex and the yield is low. The oxides produced by the vapor deposition method have good crystal quality and narrow particle size distribution, but the equipment requirements are high, the reaction conditions are complex and the yield is low. Nanoparticles have high purity, small and uniform particle size, and high surface activity. They can also be deposited on different substrates to form nanoparticle films or arrays with various special structures to meet the needs of different application scenarios, but the equipment is expensive, the process is complex, and the deposition rate is low. The microemulsion method for preparing oxide nanoparticles has good particle size controllability, good dispersibility, mild reaction conditions, and can be produced continuously, and has industrial potential, but the nanoparticles contain surfactant residues and require additional purification treatment. This method also requires the use of a large amount of surfactants and organic solvents to form a microemulsion system, and the raw material cost is relatively high.

[0004] Therefore, there is an urgent need to develop a new method for preparing oxide nanoparticles to address the defects of existing methods, such as high production cost, difficult to control product morphology, poor dispersibility, and severe agglomeration. Summary of the Invention

[0005] The present invention aims to solve at least one of the above-mentioned technical problems in the prior art. To this end, one of the purposes of the present invention is to provide a method for preparing spherical oxide particles.

[0006] A second object of the present invention is to provide spherical oxide particles.

[0007] A third object of the present invention is to provide applications of spherical oxide particles.

[0008] In order to achieve the above object, the technical solution adopted by the present invention is:

[0009] A first aspect of the present invention provides a method for preparing spherical oxide particles, comprising the following steps:

[0010] S1, mixing carbon nanotubes, functional structural oxides and boron oxide, and heating to obtain a melt containing carbon nanotubes;

[0011] S2. Cooling the melt to separate the functional structural oxide from the boron oxide, causing the boron oxide to be enriched in the carbon nanotube network, and the functional structural oxide to precipitate as droplets and solidify to obtain the spherical oxide particles.

[0012] In some embodiments of the present invention, the functional structural oxide is selected from at least one of SiO2, TiO2, ZnO, Al2O3, and MgO.

[0013] In the present invention, spherical oxide particles are prepared using SiO2, TiO2, ZnO, Al2O3 or MgO as raw materials. The raw materials themselves have functions such as serving as a skeleton structure or photocatalysis, and are functional structural oxides. The prepared spherical oxide particles will also have some of the functions of the raw materials themselves and have practical value.

[0014] In some embodiments of the present invention, the mass ratio of the functional structural oxide to boron oxide is 1:(0.5-5).

[0015] In some embodiments of the present invention, the carbon nanotubes have a diameter of 10-30 μm.

[0016] In some specific embodiments of the present invention, the diameter of the carbon nanotube is 10-20 μm.

[0017] In some embodiments of the present invention, the heating temperature is 600-1300°C.

[0018] In some specific embodiments of the present invention, the heating temperature is 700-850°C.

[0019] In some embodiments of the present invention, the heating time is 5-50 minutes.

[0020] In some specific embodiments of the present invention, the heating time is 20-40 minutes.

[0021] In some embodiments of the present invention, the temperature is lowered to room temperature at a rate of 5-20°C / min.

[0022] The basic principles of the present invention are described as follows:

[0023] 1) After mixing carbon nanotubes (CNTs), functional structural oxides, and boron oxide, the mixture is heated to a minimum temperature at which both the functional structural oxides and the boron oxide can melt and maintained for a period of time to form a melt of the functional structural oxides and the boron oxide. At this heating temperature, the carbon nanotubes, due to their high melting point and good thermal stability, are not melted and are dispersed in the melt.

[0024] 2) A melt containing boron oxide and functional structural oxide components, the former having a layered structure and the latter having a framework structure. During cooling from a high temperature, the boron oxide transforms from a layered structure to a tetrahedral structure. During this process, due to the differences in physical and chemical properties between the functional structural oxide and the boron oxide, the interaction between the two changes, leading to delamination (referred to as deboration).

[0025] 3) Carbon nanotubes have unique nanostructures and surface properties. When their diameter is 10-30 μm, their specific surface area is large and their surface energy is high. Since carbon nanotubes have a high wettability for boron oxide, boron oxide will be attracted to the surface of the carbon nanotubes in the system and enriched in the carbon nanotubes. The functional structural oxide will be precipitated into small droplets of micro-nano scale due to the barrier effect of the carbon nanotubes and form a very good sphere under surface tension. By cooling and solidifying, spherical oxide nanoparticles can be obtained on the surface of the carbon nanotubes. In this process, since the carbon nanotubes only play an adsorption and barrier role, there is no special limit on their dosage.

[0026] The second aspect of the present invention provides spherical oxide particles, which are prepared by the preparation method described in the first aspect of the present invention.

[0027] In some embodiments of the present invention, the particle size of the spherical oxide particles is 20-500 nm.

[0028] In some specific embodiments of the present invention, the particle size of the spherical oxide particles is 20-300 nm.

[0029] The third aspect of the present invention provides the use of the spherical oxide particles described in the second aspect of the present invention in the field of catalysis.

[0030] In some embodiments of the present invention, the application includes using spherical oxide particles as a catalyst or catalyst support.

[0031] In the present invention, the spherical oxide particles prepared by the preparation method of spherical oxide particles have a nanometer-sized structure and include SiO2, TiO2, ZnO, Al2O3 or MgO nanoparticles. SiO2 nanoparticles have a large specific surface area, high porosity, and a large number of surface active centers, and can be used as catalysts or catalyst carriers; TiO2 nanoparticles can be activated by sunlight or ultraviolet light in lamplight to generate free radicals with high catalytic activity, which can produce strong photooxidation and reduction capabilities and can be used as photocatalysts; ZnO nanoparticles can exhibit photocatalytic activity below the light intensity and can be used as photocatalysts to participate in oxidation or reduction reactions or photocatalytically degrade organic pollutants; Al2O3 nanoparticles can be used as catalyst carriers to improve the activity and stability of the catalyst, or as catalysts in processes such as automobile exhaust purification and organic synthesis; MgO nanoparticles can be used as catalysts or catalyst carriers in chemical reactions such as methane oxidation.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] 1) The method for preparing spherical oxide particles provided by the present invention utilizes heating to melt a functional structural oxide and boron oxide, and then cooling to separate the two phases. Under the wetting effect of carbon nanotubes, the boron oxide is enriched in the carbon nanotubes, and the functional structural oxide is precipitated under the barrier effect of the carbon nanotubes. Under the action of surface tension, functional structural oxide droplets with high sphericity and good dispersion are formed. Finally, solidification is carried out to obtain oxide nanoparticles with controllable morphology and no agglomeration.

[0034] 2) The method for preparing spherical oxide particles provided by the present invention has simple steps, low equipment requirements, short time consumption, low production cost, high production efficiency, is environmentally friendly, and is suitable for industrial use;

[0035] 3) The spherical oxide particles prepared by the preparation method of the spherical oxide particles provided by the present invention have good uniformity and high purity, and all have catalytic properties, and can be used as catalysts or catalyst carriers in the field of catalysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 is a scanning electron microscope image of the SiO2 spherical droplet in Example 1;

[0037] Figure 2 This is a scanning electron microscope image of the spherical SiO2 particles in Example 1. DETAILED DESCRIPTION

[0038] The present invention is further described in detail below by way of specific examples. Unless otherwise specified, the raw materials, reagents, or devices used in the examples are all commercially available or can be obtained by conventional methods. Unless otherwise specified, all experiments or testing methods are conventional methods in the art.

[0039] Example 1

[0040] This embodiment prepares a spherical SiO2 particle, and the steps are as follows:

[0041] S11, mixing SiO2 and boron oxide in a mass ratio of 1:0.5, adding carbon nanotubes with a diameter of 15 μm, heating to 700-850° C., and holding for 40 minutes to obtain a melt containing carbon nanotubes;

[0042] S21. Cool down to room temperature at a rate of 20°C / min to separate boron oxide and SiO2 due to deboration. Boron oxide is enriched in the carbon nanotubes, and SiO2 is precipitated under the barrier effect of the carbon nanotubes. Spherical droplets are formed under the action of surface tension and finally solidify into spherical SiO2 particles.

[0043] Example 2

[0044] This embodiment prepares a spherical TiO2 particle, and the steps are as follows:

[0045] S11, mixing TiO2 and boron oxide in a mass ratio of 1:2, adding carbon nanotubes with a diameter of 20 μm, heating to 950-1100° C., and maintaining for 40 minutes to obtain a melt containing carbon nanotubes;

[0046] S21. Cool down to room temperature at a rate of 20°C / min to separate boron oxide and TiO2 due to deboration. Boron oxide is enriched in carbon nanotubes, and TiO2 is precipitated under the barrier effect of carbon nanotubes. Spherical droplets are formed under the action of surface tension and finally solidify into spherical TiO2 particles.

[0047] Example 3

[0048] This embodiment prepares spherical ZnO particles in the following steps:

[0049] S11, ZnO and boron oxide are mixed in a mass ratio of 1:5, carbon nanotubes with a diameter of 20 μm are added, and the mixture is heated to 600-750° C. and maintained for 20 minutes to obtain a melt containing carbon nanotubes;

[0050] S21. Cooling to room temperature at a rate of 20°C / min allows boron oxide and ZnO to separate due to deboration, boron oxide to be enriched in the carbon nanotubes, and ZnO to be precipitated under the barrier effect of the carbon nanotubes, forming spherical droplets under the action of surface tension, and finally solidifying into spherical ZnO particles.

[0051] Example 4

[0052] This embodiment prepares spherical Al2O3 particles in the following steps:

[0053] S11, mixing Al2O3 and boron oxide in a mass ratio of 1:3, adding carbon nanotubes with a diameter of 10 μm, heating to 700-850°C, and maintaining for 30 minutes to obtain a melt containing carbon nanotubes;

[0054] S21. Cooling to room temperature at a rate of 20°C / min allows boron oxide and Al2O3 to separate due to deboration, boron oxide to be enriched in the carbon nanotubes, Al2O3 to be precipitated under the barrier effect of the carbon nanotubes, and spherical droplets to be formed under the action of surface tension, which eventually solidify into spherical Al2O3 particles.

[0055] Example 5

[0056] This embodiment prepares spherical MgO particles in the following steps:

[0057] S11, mixing MgO and boron oxide in a mass ratio of 1:5, adding carbon nanotubes with a diameter of 15 μm, heating to 600-750° C., and maintaining for 20 minutes to obtain a melt containing carbon nanotubes;

[0058] S21. Cooling to room temperature at a rate of 20°C / min allows boron oxide and MgO to separate due to deboration, boron oxide to be enriched in the carbon nanotubes, and MgO to be precipitated under the barrier effect of the carbon nanotubes, forming spherical droplets under the action of surface tension, and finally solidifying into spherical MgO particles.

[0059] Figure 1 is a scanning electron microscope image of the SiO2 spherical droplet in Example 1, Figure 1 It can be seen that during the cooling process, boron oxide and SiO2 will separate due to deboration. Under the wetting effect of carbon nanotubes, boron oxide will be attracted to the surface of carbon nanotubes in the system, while SiO2 will be blocked by carbon nanotubes and precipitate to form SiO2 droplets with high sphericity. There is no aggregation between the droplets, and the dispersion is good, which is conducive to the formation of highly dispersed and uniform nanoparticles.

[0060] Figure 2 is a scanning electron microscope image of the spherical SiO2 particles in Example 1, Figure 2 It can be seen that Example 1 successfully prepared spherical SiO2 nanoparticles with a particle size of about 20-300 nm. The nanoparticles have high sphericity, the preparation process is simple and time-saving, and has the potential for industrial production.

Claims

1. A method for preparing spherical oxide particles, characterized in that: The following steps are involved: S1, mixing carbon nanotubes, functional structural oxides and boron oxide, and heating to obtain a melt containing carbon nanotubes; S2. Cooling the melt to separate the functional structural oxide from the boron oxide, causing the boron oxide to be enriched in the carbon nanotube network, and the functional structural oxide to precipitate as droplets and solidify to obtain the spherical oxide particles.

2. The preparation method according to claim 1, characterized in that The functional structural oxide is selected from at least one of SiO2, TiO2, ZnO, Al2O3, and MgO.

3. The preparation method according to claim 1, characterized in that The mass ratio of the functional structural oxide to boron oxide is 1:(0.5-5).

4. The preparation method according to claim 1, characterized in that The diameter of the carbon nanotubes is 10-30 μm.

5. The preparation method according to claim 1, characterized in that The heating temperature is 600-1300°C.

6. The preparation method according to claim 5, characterized in that The heating time is 5-50 minutes.

7. The preparation method according to claim 1, characterized in that The temperature is lowered to room temperature at a rate of 5-20°C / min.

8. A spherical oxide particle, characterized in that: The method comprises adopting the preparation method according to any one of claims 1 to 7.

9. The spherical oxide particles according to claim 8, characterized in that The particle size of the spherical oxide particles is 20-500 nm.

10. Use of the spherical oxide particles according to claim 8 or 9 in the field of catalysis.

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