Nanometer Tungsten Trioxide Preparation by Prolysis Method

Tungsten trioxide is mainly used for high melting point alloy and cemented carbide, tungsten wire and fire gas sensitive materials, also for the photocatalytic materials.

The scope of application of nanometer tungsten trioxide is more and more widely. There are two methods for the synthesis of nano tungsten which is oxide gas phase method and liquid phase method.

Recently, some scholars proposed a synthesis method of tungsten oxide, it is called precursor pyrolysis method, the process is as follows:

1. High purity ammonium para tungstate (APT) with a grain size of 5 μm is used as the reaction material. Then add distilled water into a reaction vessel, stir with an electromagnetic agitator, add citric acid while stirring.

2. After all the citric acid solution is dissolved and mixed evenly, add high purity ammonium para tungstate (APT) into the reaction vessel while stirring.

3. After finishing ammonium tungstate (APT), the ammonia water is added into the vessel and mixed evenly, the reaction solution is obtained.

4. The reaction solution is concentrated in an evaporation container, the obtained concentrate was dried at 150-160°C in the drying equipment to get the precursor.

5. Pulverizing the precursor in the grinding equipment. Then proceed heat treatment with oxygen into the crucible. Finally get the tungsten trioxide (WO₃) nano powder.

In the process of production, the purity of high purity ammonium para tungstate (APT) is more than 99.9%. The molar ratio of ammonium para tungstate (APT) to citric acid is calculated to be 1:3. The concentration of ammonia is 30%. The stirring speed is 180-200r/min, the pyrolysis temperature is 500-520°C, and the time is 1.2-1.5h.

Tungsten oxide (WO₃) nano powder completely inherited the crystal structure of APT crystal, WO₃ nanorods, the maximum length of nanorods is about 2.5 um, diameter is about 30~60 nm, the maximum diameter is about 1:80 ratio, uniform particle size distribution, nano tungsten powder is of high quality.

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