High Purity Phosphotungstic Acid Preparation
Heteropoly acid is one of the most active catalysts in acid catalytic reaction and redox reaction. Phosphotungstic acid H3PW12O40•nH2O is the most widely used in heteropoly acid. The purity of phosphotungstic acid directly affects the conversion rate of the catalytic system. Therefore, the preparation of high purity phosphotungstic acid is especially important.
Some scholars have proposed a purification method for phosphotungstic acid crystals.
(1) The crystal of industrial phosphotungstic acid is dissolved in water and the inorganic acid is added to the solution of phosphotungstic acid containing inorganic acid. The concentration of tungsten trioxide is 50-150g/L, and the volume molar concentration of the inorganic acid is 0.5 ~ 6mol/L.
(2) In the solution of phosphotungstic acid containing inorganic acids, the oil phase organic alcohol extractant was extracted with the volume concentration of 5-50%, and the volume ratio of the two phase was oil phase = 1:1-10:1, and the organic phase loaded with tungsten was obtained.
(3) The organic phase containing tungsten is extracted by distilling water with volume ratio as oil phase: water phase = 3:1-10:1, and the stripping solution is obtained.
(4) High purity phosphotungstic acid crystals can be obtained by heating evaporating crystals or spray drying, and the yield is more than 95.4%.
The new process is short, the preparation cost is low, the environment is not polluted, and it is easier for large-scale industrial production.
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