CN1884083B - A kind of preparation method of nano-alumina hollow sphere structure - Google Patents

Abstract

The invention discloses a preparing method of nanometer aluminum oxide hollow ball structure, which is characterized by the following: carrying composite solution of AlCl3 and alcohol through nitrogen in the evaporator (1) to evaporate; blending with air and hydrogen at 200-350 deg.c in the combusting reactor (2) through center pipe (3) of triplet channel mouth on the top of combusting reactor; hydrolyzing in the combusting chamber at 1200-2500 deg.c ; generating nanometer Al2O3 hollow ball structure; collecting the product from bottom of combusting reactor; draining tail gas by HCl adsorbed tower; reacting hydrogen and air at 25-100 deg.c in the combusting reactor (2) through two-loop pipe; entering air in the combusting reactor (2) at 50-200 deg.c through three-loop pipe (303).

Description

A kind of preparation method of nano-alumina hollow sphere structure

technical field

The invention relates to a method for preparing a nano-alumina hollow sphere structure.

Background technique

Compared with bulk materials, the special structure of hollow spheres has many characteristics such as large specific surface area and low density. Therefore, the application range of nano hollow spheres has been continuously expanded, and has been extended to many fields such as material science and dye industry. It can be used as a lightweight material. Materials of construction, thermal insulation. Sound insulation and electrical insulation materials, pigments and catalyst carriers, etc. In addition, this special structure enables it to be used as a carrier of guest substances, thus being widely used in the fields of medicine and pharmacy. Due to the excellent performance and broad application prospects of the nano-hollow sphere structure, its development and research have attracted widespread attention, and a variety of methods for preparing nano-hollow spheres have been formed, such as template method, self-assembly method, spray pyrolysis method, sonochemistry method, hydrothermal method, etc. CdS, ZnS, ZrO ₂ , TiO ₂ , Fe ₃ O ₄ , Si, SiO ₂ and other inorganic material hollow nanospheres have been successfully prepared by these methods. Compared with other nanomaterial synthesis methods, gas-phase combustion synthesis of nanocomposite particles has a small particle size and high purity, which is an important method for preparing nanoparticle materials and one of the most promising preparation methods for industrialization.

Takeo Hyodo et al reported a method in the literature (Joumal of the European Ceramic Society, 2005, 25: 3563-3572), but the method has complex equipment, high energy consumption, complex raw materials, and low controllability, making it difficult to implement industrially .

Contents of the invention

The object of the present invention is to provide a method for preparing a nano-alumina hollow sphere structure, so as to overcome the defects in the prior art.

Design of the present invention is such:

After the AlCl ₃ ethanol solution is loaded into the evaporator by N ₂ , since the boiling point of ethanol is low, AlCl ₃ can also sublimate at 177.8°C, so the solution is completely vaporized to form a mixed vapor. After mixing with hot air, it enters the burner of the multi-jet combustion reactor and cools inside the burner. Since the saturated vapor pressure of AlCl ₃ is small, it first desublimates to form tiny particles. As the temperature further decreases, ethanol takes AlCl ₃ particles as the The nuclei condense into tiny mist droplets, which are ejected from the burner at high speed and enter the annular flame produced by _H2 combustion. At the same time, ethanol is also ignited. During this process, AlCl ₃ undergoes high-temperature hydrolysis and nucleates on the surface of the droplet to form hollow particles of Al ₂ O ₃ ·H2O or Al(OH) ₃ , which are further sintered and crystallized in a high-temperature flame to form the final nano Al ₂ O ₃ hollow sphere structure.

The preparation method of the present invention is characterized in that it comprises the steps of:

The mixed solution of AlCl ₃ and ethanol is loaded into the evaporator by the carrier gas N ₂ , vaporized at 150-300°C, and then mixed with air and hydrogen at 200-350°C, the three-channel set on the top of the combustion reactor The central tube of the burner enters the combustion reactor, and the hydrolysis reaction is carried out in the combustion chamber. The reaction temperature is 1200-2500 ° C, and finally a nano-Al ₂ O ₃ hollow sphere structure is formed, which is discharged from the bottom of the combustion reactor and collected. The Al ₂ O ₃ hollow The diameter of the spherical particles is 100-500nm, the thickness of the spherical wall is 20-60nm, and the tail gas is emptied after passing through the HCl absorption tower.

At the same time, the mixed gas of hydrogen and air at a temperature of 25-100°C enters the combustion reactor through the second ring pipe to form an annular auxiliary flame, which is used to maintain the stability of the central jet flame and adjust the temperature of the reaction zone;

At the same time, air with a temperature of 50-200°C enters the combustion reactor through the three-loop pipe;

Through the gas flow rate and preheating temperature of the three-channel burner, the gas temperature at the burner outlet is controlled to be 100-190°C;

The mass concentration of the ethanol solution of aluminum trichloride is 5%-20%;

The ratio of the amount of nitrogen carrier gas to the feed amount of the solution is 0.2-0.5 m ³ /h: 10 ml/min.

The standard volume ratio of hydrogen and air entering the central tube is 1:5-10;

The mixed gas passed into the second ring pipe is 1:0.2~1 according to the standard volume ratio of hydrogen and air;

The volume ratio of gases in each channel is:

Central tube: second ring tube: three ring tube = 1: 0.2~0.6: 0.5~3;

The nano-alumina hollow sphere structure is prepared by the method of the present invention, the equipment is simple, the precursor is chloride, the cost is much lower than that of the organic precursor, and the risk of inflammability and explosion of the organic precursor is eliminated, and the controllability is high , easy to implement in industrialized continuous production. At the same time, the hollow spheres of the product have a small particle size and a controllable wall thickness of the spherical shell, which has broad application prospects in light ceramics and catalyst carriers.

Description of drawings

Fig. 1 is the said schematic flow chart of the present invention.

Fig. 2 is the electron micrograph of the product of embodiment 1.

Fig. 3 is the electron micrograph of the product of embodiment 2.

Detailed ways

Referring to Fig. 1, the preparation method described in the invention comprises the steps:

The mixed solution of AlCl3 _and ethanol is loaded into the evaporator ₁ by the carrier gas N2 to be vaporized, and then mixed with air and hydrogen, and enters the combustion reaction through the center pipe 301 of the three-channel burner 3 arranged on the top of the combustion reactor 2 The reactor 2 carries out the hydrolysis reaction in the combustion chamber, and finally generates a nano-Al ₂ O ₃ hollow sphere structure, which is discharged from the bottom of the combustion reactor 2 and collected by the collection device 4. The tail gas of the collection device 4 passes through the HCl absorption tower and then is emptied.

At the same time, the mixed gas of hydrogen and air enters the combustion reactor through the second ring pipe 302;

At the same time, air enters the combustion reactor from the three-ring pipe 303 .

Example 1

The dehydrated ethanol solution of aluminum trichloride (mass percent concentration is 15%, 5ml/min) is loaded into evaporator by _N , and evaporator temperature is controlled as 300 ℃, and the air (250 ℃, 250 ℃, 2m ³ /h), central tube hydrogen (0.5m ³ /h) and then enter the combustion reactor (13) from the burner central tube. The mixed gas of second-ring hydrogen (2m ³ /h) and second-ring air (1m ³ /h) is fed into the second-ring inlet to form an annular auxiliary flame, which is used to maintain the stability of the central jet flame and adjust the temperature of the reaction zone. There is another path of air (50°C, 3m ³ /h) that has been preheated by drying and filtering through the three rings, and the hydrolysis reaction of the precursor is carried out in the combustion chamber. The gas temperature at the outlet of the burner is controlled to be partially condensed within the range of 100°C to form atomized steam, which enters the combustion chamber for combustion and undergoes a high-temperature hydrolysis reaction. The thickness is 50nm. see picture 1.

Example 2

The dehydrated ethanol solution of aluminum trichloride (mass percentage concentration is 8%, 3ml/min) is loaded into _evaporator by N , and evaporator temperature is controlled as 170 ℃, and the air (200 ℃, 200 ℃, 3m ³ /h) and central tube hydrogen (0.2m ³ /h) are uniformly mixed and enter the combustion reactor from the burner central tube. The mixed gas of second-ring hydrogen (3m ³ /h) and second-ring air (1m ³ /h) is added through the inlet of the second ring to form an annular auxiliary flame, which is used to maintain the stability of the central jet flame and adjust the temperature of the reaction zone. In addition, three-ring air (50°C, 5m ³ /h) preheated through dry filtration is added through the three-ring, and the hydrolysis reaction of the precursor is carried out in the combustion chamber. The gas temperature at the outlet of the burner is controlled to be partially condensed within the range of 160°C to form atomized steam, which enters the combustion chamber for combustion and undergoes a high-temperature hydrolysis reaction. The thickness is 30nm. See Figure 2.

Claims (5)

1. the preparation method of a nano alumina hollow ball structure is characterized in that, comprises the steps: AlCl ₃With the alcoholic acid mixing solutions, by carrier gas N ₂Be written into vaporizer (1) vaporization, then with after 200～350 ℃ air and hydrogen mix, pipe core (3) by the triple channel burner that is arranged on the combustion reactor top enters combustion reactor (2), reaction is hydrolyzed in the combustion chamber, temperature of reaction is 1200～2500 ℃, and generates nanometer Al at last ₂O ₃Hollow ball structure is discharged collection from the combustion reactor bottom, emptying behind the tail gas process HCl absorption tower;

Simultaneously, temperature is that 25～100 ℃ hydrogen and Air mixing gas enters combustion reactor (2) by two endless tubes;

Simultaneously, temperature is that 50～200 ℃ air enters combustion reactor (2) by three endless tubes (303);

Wherein, enter the hydrogen of pipe core, the standard volume ratio of air is 1: 5～10; The mixed gas that feeds two endless tubes is 1: 0.2～1 by the standard volume ratio of hydrogen and air;

The volume ratio of the gas in each passage is: pipe core: two endless tubes: three endless tubes=1: 0.2～0.6: 0.5～3;

Described Al ₂O ₃The hollow ball particle diameter is at 100～500nm.

2. method according to claim 1 is characterized in that, the burner Outlet Gas Temperature is 100～190 ℃.

3. method according to claim 1 is characterized in that, the ethanolic soln mass concentration of aluminum chloride is 5%～20%, and the ratio of the inlet amount of nitrogen carrier gas amount and solution is 0.2～0.5m ³/ h: 10ml/min.

4. method according to claim 1 is characterized in that, with AlCl ₃With the alcoholic acid mixing solutions, by carrier gas N ₂Be written into vaporizer (1), 150～300 ℃ of vaporizations down.

5. according to each described method of claim 1～4, it is characterized in that Al ₂O ₃The ball wall thickness of hollow ball is 20～60nm.

Images