Nano Tungsten Trioxide-Titanium Dioxide Composite Catalyst Preparation

Recently, with development of nano technology, nano material is commonly used in various field. WO3 as semi-conducting metal oxide, its excellent gas sensitivity and photosensitiveness become researching focus in and abroad.

Tungsten trioxide and titanium dioxide are common seen photocatalyst material. They are used in composite form in real application. The common used method for preparing tungsten trioxide is hydrothermal method. However, it can not control temperature, concentration, acidity and alkalinity very well which may cause significant difference in the result. So people researched a new method as following:

1. Preparing Ammonium Tungstate

1.1 Dissolve ammonium metatungstate in water, temperature is 60℃. Purifying the obtained ammonium tungstate by purifying device with double membrane. The first layer is micron membrane, the second layer is nano membrane. Concentration of tungstate is 250g/L after purifying.

1.2 Obtain ammonium tungstate solution by ion exchange method with ion exchange resin from step 1.1.

1.3 Adjust pH value from step 1.2 to 5, then use spray crystalline equipment to dry it and obtain ammonium tungstate.

2. Preparing Tungsten Trioxide - Titanium Dioxide Composite Catalyst

2.1 Mixing tetrabutyl titanate, absolute ethanol and glacial acetic acid in a volume ratio of 1:2:2, magnetically stirring for 30 min, adding dilute nitric acid, and magnetically stirring for 30 min in a water bath at 50 ° C to obtain titanium dioxide sol.

2.2 Add 20mg ammonium tungstate into mixing solution of oxalic acid and concentrated hydrochloric acid. Stirring for 40min to dissolve ammonium tungstate.

2.3 Mixing titanium dioxide sol and ammonium tungstate solution evenly, put into reaction furnace with lining polytetrafluoroethylene. Reacting for 24 hours under 160℃. After cooling down, filtration, washing, drying can get tungsten trioxide - titanium dioxide composite catalyst.

Ultraviolet-visible spectroscopy analysis of the prepared tungsten trioxide-titanium dioxide composite catalyst showed that the absorption intensity of the composite catalyst was significantly improved compared with pure titanium dioxide, indicating that the tungsten oxide composite extended the wavelength range of TiO2 light absorption and enhanced the composite. The light absorbing ability of the catalyst further increases the photocatalytic activity of the tungsten trioxide-titanium dioxide composite catalyst.

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