CN103588175A - Method for making nano-powder through ultrasonic atomization-microwave pyrolysis - Google Patents

Abstract

The invention relates to a method for preparing nano powder by ultrasonic atomization-microwave pyrolysis, and belongs to the technical field of inorganic nano materials. First, the mixed solution of soluble easily decomposable metal salt, water and ethanol is configured as a precursor solution, and the precursor solution prepared by the above steps is ultrasonically atomized to obtain droplets; under the action of carrier gas or fan, the above steps are prepared to obtain The mist droplets are brought into the microwave, quickly dried and pyrolyzed, and nano-powders can be prepared. The nano-powders are nano-shell metal oxide or composite oxide powders. The present invention combines the advantages of ultrasonic and microwave methods. Ultrasonic waves will generate a large number of tiny bubbles in the liquid due to cavitation. Drops have a spherical hollow vacuole structure within a certain period of time. Microwave heating has the advantages of uniform heating from the inside to the outside, selective heating, fast heating speed, and easy control.

Description

A method for preparing nano powder by ultrasonic atomization-microwave pyrolysis

technical field

The invention relates to a method for preparing nano powder by ultrasonic atomization-microwave pyrolysis, which belongs to the technical field of inorganic nano materials.

Background technique

The invention adopts the method for preparing nano powder by ultrasonic atomization-microwave pyrolysis to prepare nano shell metal oxide powder, nano composite powder and nano thin film.

Nanocomposite materials have good properties and are widely used in photoelectric display devices, transparent electrodes, solar cells, liquid crystal displays, catalysis, etc., such as ITO (Sn-doped In2O3), AZO (Al-doped ZnO), GZO (Ga Doped ZnO), IZO (In-doped ZnO), FTO (F-doped SnO2), etc. At present, the methods for preparing composite powder include coprecipitation method, spray thermal decomposition method, organic solvent azeotropic method, etc. Among these methods, the reagents of the former method are easy to obtain, but the cycle time is longer, while the latter method needs to use higher-priced organic reagents and has high cost, so it is rarely used. The spray pyrolysis method can quickly obtain the particle size Uniform powder.

Nano metal oxide powder has many advantages such as high specific surface area, high activity, strong ability to absorb and scatter ultraviolet light, etc. Aspects have been developed and applied, showing attractive prospects. To make nanopowder materials have good performance, the preparation of nanopowder is the key. At present, the preparation methods of nanopowders including metal oxides and composite oxide nanopowders can be divided into physical methods and chemical methods.

The physical methods for preparing metal oxides and composite oxide nanopowders include physical pulverization and mechanical ball milling. The physical pulverization method is to obtain nanoparticles by mechanical pulverization, electric spark explosion and other methods. It is characterized by simple operation and low cost, but the product has low purity and uneven particle distribution. The mechanical ball milling method is to control appropriate conditions to obtain pure element nanoparticles, alloy nanoparticles or nanoparticles of composite materials. The method has the advantages of simple operation and low cost, but at the same time, the prepared product has low purity and uneven particle distribution.

Preparation of nano-powder materials by chemical methods is a current research hotspot, including vapor deposition, precipitation and sol-gel methods.

Vapor deposition method directly uses gas or turns substances into gas, then undergoes chemical reactions in the gaseous state, and finally cools and condenses into nanoparticles. The particle size distribution of the powder prepared by this method is relatively uniform, and the agglomeration is light. However, this method requires special and expensive equipment, strict control of sample conditions, and complicated and immature operation.

At present, there are many studies on the preparation of nano-powder materials by chemical precipitation. The use of ordinary chemical equipment has a simple process and is more suitable for large-scale production. It is currently a hot method for preparing nano-powders. However, it is difficult to wash anions, and the powder is easy to agglomerate, which is the main problem of this method.

The sol-gel method uses a metal salt solution, a precipitant, and a surfactant to prepare a nano-powder precursor, and then undergoes strict aging, washing, and calcination to prepare a nano-oxide powder material. The advantage of this process is that the obtained nano-powder has a uniform particle size and stable composition. The disadvantages are that the process is complex, the process is long, and additives and surfactants are required, which not only increases the cost but also brings problems such as high wastewater treatment costs.

The traditional spray pyrolysis method is a process method that combines the advantages of liquid phase method and gas phase method to prepare powder technology to a certain extent. Generally, the pressure spray method is used to break up the liquid into droplets, and then introduce it into the heating furnace cavity. Internal heat exchange completes the drying and pyrolysis process. The advantage of this method is that the drying and pyrolysis processes are completed in one cavity, and the product can be obtained directly without subsequent filtration, washing, drying, and crushing processes, and the operation is simple. But the disadvantage is that coal gas, natural gas or heavy oil are mostly used as the heat source, not only the large amount of waste gas produced must be treated separately, but also the waste gas takes away a lot of heat and consumes a lot of energy.

Contents of the invention

Aiming at the problems and deficiencies in the above-mentioned prior art, the present invention provides a method for preparing nanopowder by ultrasonic atomization-microwave pyrolysis. The invention combines the advantages of ultrasonic and microwave methods to prepare nano-shell metal oxide powder and nano-composite powder. Ultrasonic waves will produce a large number of tiny bubbles in the liquid due to cavitation. On the surface of the liquid, these small droplets are thrown off the liquid surface to form mist droplets, and these mist droplets have a spherical hollow bubble structure within a certain period of time. Microwave heating has the advantages of uniform heating from inside to outside, selective heating, fast heating speed, and easy control. Pyrolysis or continue with the follow-up process to obtain nano-shell metal oxide powder and nano-composite powder. Therefore, the spray pyrolysis method combining ultrasonic atomization and microwave heating can be applied to high-tech fields such as photocatalysis, and the present invention is realized through the following technical solutions.

A method for preparing nano powder by ultrasonic atomization-microwave pyrolysis, the specific steps are as follows:

(1) Firstly, the mixed solution of soluble easily decomposable metal salt, water and ethanol is configured as a precursor solution, wherein the volume ratio of water and ethanol in the mixed solution is (50-100): (0-50);

(2) Ultrasonic atomization of the precursor solution prepared in step (1) to obtain droplets with an average diameter of 10-200 μm;

(3) Under the action of carrier gas or fan, the droplets prepared in step (2) are brought into the microwave, and quickly dried and pyrolyzed at a temperature of 300-1200°C to prepare nano-powder, nano-powder It is nano-shell metal oxide or composite oxide powder.

The molar concentration of the soluble metal salt in the precursor solution in the step (1) is 0.001-2 mol/L.

When the soluble easily decomposable metal salt is a metal salt of a single metal element, the prepared nanopowder is a nanoshell metal oxide.

In the step (1), in addition to adding a soluble and easily decomposable metal salt of a single metal element, when another soluble and easily decomposable salt of a different element is added, the prepared nanopowder is a composite oxide powder.

The soluble easily decomposable metal salt is acetate, chloride, nitrate or sulfate.

In the preparation of the composite oxide powder above, another soluble easily decomposable salt of a different element can be a non-metal salt or a metal salt.

The nano-powder prepared above is a composite oxide powder. The salts of different elements added are the same as the elements of the nano-composite powder to be obtained, and the molar ratio of the different elements added is also the same as that of the required nano-composite powder. The molar ratios of the elements in the body are the same.

The beneficial effects of the present invention are: (1) The precursor solution is atomized by means of ultrasonic waves, the size of the atomized droplets can be controlled by adjusting the frequency and power of the ultrasonic waves, and then the particle size distribution and shape of the prepared metal oxide can be adjusted. Appearance, that is, the particle size and shape of the product can be controlled; (2) Microwave heating is used to precisely control the pyrolysis temperature. Microwave heating replaces traditional heating methods such as electric furnace, gas or heavy oil. It has the advantages of easy control, safety, reliability, and environmental friendliness; (3) The process route is simple, the reaction process is fast and stable, and the waste gas generated after absorption treatment is clean and pollution-free, with high production efficiency, high product purity and good quality; (4) The The process equipment is simple, the product is easy to collect, it is suitable for continuous production, and has broad application prospects.

Description of drawings

Fig. 1 is a schematic SEM diagram of nanoshell zinc oxide powder corresponding to Example 1 of the present invention.

Detailed ways

The present invention will be further described below in combination with the accompanying drawings and specific embodiments.

Example 1

The method for preparing nano powder by ultrasonic atomization-microwave pyrolysis, its specific steps are as follows:

(1) Firstly, the soluble easily decomposable metal salt and water and ethanol solution are configured to form a precursor solution, wherein the volume ratio of water and ethanol solution is 100:0, and the molar concentration of the soluble metal salt in the precursor solution is 0.001mol/L, The soluble metal salt is zinc acetate;

(2) Ultrasonic atomization of the precursor solution prepared in step (1) to obtain droplets with an average diameter of 10 μm;

(3) Under the action of carrier gas or fan, the droplets prepared in step (2) are brought into the microwave, and quickly dried and pyrolyzed at 450°C to prepare nano-shell zinc oxide powder.

The shell thickness of the nano-shell metal oxide powder is about 10 nm, the particles are evenly distributed, and the dispersibility is good, as shown in FIG. 1 .

Example 2

The method for preparing nano powder by ultrasonic atomization-microwave pyrolysis, its specific steps are as follows:

(1) Firstly, the soluble easily decomposable metal salt and water and ethanol solution are configured into a precursor solution, wherein the volume ratio of water and ethanol solution is 80:20, and the soluble easily decomposable metal salt is 2.16g of InCl ₃ .5H ₂ O and 0.19 g of SnCl ₂ .2H ₂ O;

(2) Ultrasonic atomization of the precursor solution prepared in step (1) to obtain droplets with an average diameter of 100 μm;

(3) Under the action of carrier gas or fan, the mist prepared in step (2) is brought into the microwave, and quickly dried and pyrolyzed at 700 ° C to prepare nano-ITO powder.

Example 3

The method for preparing nano powder by ultrasonic atomization-microwave pyrolysis, its specific steps are as follows:

(1) Firstly, the soluble easily decomposable metal salt and water and ethanol solution are configured into a precursor solution, wherein the volume ratio of water and ethanol solution is 70:30, and the soluble easily decomposable metal salt is 2.25g of SbCl ₃ and 6.75g of SnCl ₂ .2H ₂ O;

(2) Ultrasonic atomization of the precursor solution prepared in step (1) to obtain droplets with an average diameter of 100 μm;

(3) Under the action of carrier gas or fan, the droplets prepared in step (2) are brought into the microwave, and quickly dried and pyrolyzed at 600°C, the composite metal of nano-antimony oxide doped tin oxide can be prepared oxide powder.

Example 4

The method for preparing nano powder by ultrasonic atomization-microwave pyrolysis, its specific steps are as follows:

(1) Firstly, the soluble easily decomposable metal salt and water and ethanol solution are configured to form a precursor solution, wherein the volume ratio of water and ethanol solution is 85:15, and the soluble easily decomposable metal salt is 2.25g of NH ₄ F and 6g of SnCl ₄ .5H ₂ O;

(2) Ultrasonic atomization of the precursor solution prepared in step (1) to obtain droplets with an average diameter of 100 μm;

(3) Under the action of carrier gas or fan, the mist prepared in step (2) is brought into the microwave, and quickly dried and pyrolyzed at 500 ° C to prepare nano-nano FTO powder.

Example 5

The method for preparing nano powder by ultrasonic atomization-microwave pyrolysis, its specific steps are as follows:

(1) First, the soluble easily decomposable metal salt and water and ethanol solution are configured to form a precursor solution, wherein the volume ratio of water and ethanol solution is 50:50, and the molar concentration of the soluble metal salt is 1mol/L, and the soluble easily decomposable metal The salt is zinc nitrate;

(2) Ultrasonic atomization of the precursor solution prepared in step (1) to obtain droplets with an average diameter of 200 μm;

(3) Under the action of carrier gas or fan, the mist prepared in step (2) is brought into the microwave, and quickly dried and pyrolyzed at 300 ° C to prepare nano-shell zinc oxide powder.

Example 6

The method for preparing nano powder by ultrasonic atomization-microwave pyrolysis, its specific steps are as follows:

(1) Firstly, the mixed solution of soluble easily decomposable metal salts, water and ethanol is configured as a precursor solution, wherein the volume ratio of water and ethanol in the mixed solution is 90:10, and the molar concentration of soluble metal salts in the precursor solution is 2mol/L, the soluble easily decomposable metal salt is copper sulfate;

(2) Ultrasonic atomization of the precursor solution prepared in step (1) to obtain droplets with an average diameter of 100 μm;

(3) Under the action of a carrier gas or a fan, the droplets prepared in step (2) are brought into the microwave, and quickly dried and pyrolyzed at a temperature of 1200°C to prepare nano-powders, which are nano- Shell copper oxide powder.

Claims (5)

1. ultrasonic atomization-microwave-heating is prepared a method for nano-powder, it is characterized in that concrete steps are as follows:

(1) first the mixing solutions of the easy decomposing metal salt of solubility and water and ethanol is configured to precursor solution, wherein in mixing solutions, the volume ratio of water and ethanol is (50～100): (0～50);

(2) precursor solution step (1) being prepared obtains the droplet of equal footpath 10～200 μ m through ultrasonic atomization;

(3) under carrier gas or fan effect, step (2) is prepared to droplet to be brought in microwave, in temperature, be rapid drying pyrolysis under 300～1200 ℃ of conditions, can prepare nano-powder, nano-powder is nanoshells metal oxide or composite oxide powder.

2. ultrasonic atomization-microwave-heating according to claim 1 is prepared the method for nano-powder, it is characterized in that: in described step (1), in precursor solution, the volumetric molar concentration of soluble metallic salt is 0.001～2mol/L.

3. ultrasonic atomization-microwave-heating according to claim 2 is prepared the method for nano-powder, it is characterized in that: during metal-salt that the easy decomposing metal salt of described solubility is single metallic element, the nano-powder preparing is nanoshells metal oxide.

4. ultrasonic atomization-microwave-heating according to claim 2 is prepared the method for nano-powder, it is characterized in that: in described step (1) except adding solubility easily to decompose the metal-salt of single metallic element, while also having added the easy salt decomposition of solubility of another kind of different elements, the nano-powder preparing is composite oxide powder.

5. according to the ultrasonic atomization-microwave-heating described in claim 1 to 4, prepare the method for nano-powder, it is characterized in that: the easy decomposing metal salt of described solubility is acetate, villaumite, nitrate or vitriol.