Tungstic Acid Hydrogen Reduction Producing Violet Tungsten Oxide Process
1.Heat tungstic acid over 100℃, decompose it to generate WO3 and steam H2O, equation: mWO3•nH2O＝mWO3+nH2O
2.Add NH3, when reacting temperature is over 500℃, ammonia under catalytic reacting of tungsten oxide will generate H2, so as to reduce WO3 into WO2.9.
3.Blue tungsten oxide reduces under hydrogen atmosphere, violet tungsten oxide is obtained.
During this process of producing violet tungsten oxide, H2O can react with WOx(2≤x≤3) to generate WO2(OH)2, hydrated tungsten oxide WO2(OH)2 is gas under high temperature. With hydrated WO2(OH)2 gas phase migration, violet tungsten oxide WO2.72 crystal nucleus will grow into acicular violet tungsten oxide.