DECAVANADATE ION-PILLARED HYDROTALCITE - SPECTROSCOPIC STUDIES OF THE THERMAL-DECOMPOSITION PROCESS

In this study, we have focused on the thermal decomposition of the material generated by ion-exchange of decavanadate ions into the layers of a magnesium aluminum hydroxide hydrotalcite-like compound, over the temperature range from ambient to 650°C. Using powder diffraction data and Raman and XANES spectroscopy, it was found that the intercalated decavanadate ions transform into cyclic and chain-like metavanadate species at temperatures between 160-350°C. The metal hydroxide layer structure remains intact until 350°C. Reaction between the metal oxide and the metavanadate species to form magnesium vanadates is only observed for samples heated in excess of 450°C. © 1990.