Dodecatungstophosphoric acid is a polymer composed of twelve tungstate and phosphoric acid with special composition heteropolyacids, the appearance is yellow or brown solid, soluble in water, with oxidation property. It is mainly used for newly developed catalyst with wide application. In 20th century, Keggin used X-ray powder diffraction method to test molecular structure of dodecatungstophosphoric acid.
Producing dodecatungstophosphoric acid mainly uses sodium tungstate and sodium hydrogen phosphate as raw material, steps are as following:
1.Dissolve 25g sodium tungstate and 4g sodium hydrogen phosphate in 150ml boiled water, the solution is muddy.
2.Stir and heat the solution, add 25ml HCl solution to make the solution clear, keep heating for 30s. If the solution turns blue, it is the result of reducing tungsten (VI), we can add 3% hydrogen peroxide to make it transparent. And then we can get dodecatungstophosphoric acid solution.
3.Transit solution and precipitated solid to separating funnel, add 35ml ether, then add 10ml6mol / L hydrochloric acid and shake, after the liquid was separated to three layers, put into the evaporating dish.
4. Ether was distilled in a water bath until the surface of the liquid crystal film appears, the evaporating dish on the ventilation (note: to prevent falling into dust), so that the ether in the air gradually evaporate, thus we can obtain a white or pale yellow solid dodecatungstophosphoric acid.