Thermal dehydration of H3 + xPVxM12 − xO40·yH2O Keggin type heteropolyacids; formation, thermal stability and structure of the anhydrous acids H3PM12O40, of the corresponding anhydrides PM12O38.5 and of a novel trihydrate H3PW12O40·3H2O

Abstract

The formation and thermal stability of the catalytically important anhydrous acids H3PM12O40 (M = Mo,W,V), of the corresponding anhydrides PM12O38.5 and of a novel first time isolated trihydrate H3PW12O40·3H2O have been studied by high temperature X-ray diffraction (XRD) and thermogravimetry (TG). The corresponding crystal structures were determined from X-ray powder data using the Rietveld method and by deriving three-dimensional structure models from the experimental radial distribution functions.