Powdery White Tungstic Acid and Its Application
Tungstic acid can be roughly divided into yellow tungstic acid and white tungstic acid. More and more practice has shown that tungstic acid not only has an important use in tungsten chemistry, but also has great value in tungsten metallurgy. Powdery white tungstic acid can compose tungsten niobium and tungsten tantalum Heteropoly salt. Tungsten phosphoric acid and tungstic acid can also be composed. The heteropoly acid prepared from powdered white tungstic acid has better catalytic performance than that prepared with tungstic acid. The preparation of white tungstic acid is to drop Na 2 WO 4 solution into dilute acid. In the middle of the process, there is no acid anion, so the precipitation rate is high. In the Na 2 WO 4 solution tungsten exists as monomeric WO42-form. The presence of dilute acid immediately results in protonation and formation of tungstic acid precipitation. Generally, the prepared white tungstic acid is a mixture of mono - tungstic acid and poly - t...