Preparation of caesium-substituted phosphomolybdic acid via solid-state ion exchange method

In this paper, we report the preparation of caesium-exchanged phosphomolybdic acid, Cs3PMo12O40, via the solid-state reaction between caesium chloride and ammonium phosphomolybdate. The calcination of this mixture was performed at 400 °C–600 °C. The thermal genesis of Cs3PMo12O40 from its precursors was explored using thermo-gravimetric (TGA), differential thermal (DTA), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM) and energy dispersive X-ray analyses. The results obtained indicated that pure ammonium phosphomolybdate hydrate first lost its crystal water and later decomposed at temperatures higher than 450 °C. In the CsCl and (NH4)3PMo12O40 mixture, it was demonstrated that Cs+ moves into exchange positions at such temperature without destroying the Keggin structure of the heteropoly compound.