Amorphous niobium phosphate:: characterization and acid aspects

The effects of the P/Nb ratio, ion exchange process, washing conditions, and thermal treatment on the composition, acid, and textural properties of the niobium phosphate were studied by X-ray fluorescence, X ray powder diffraction, thermogravimetric and differential thermal analyses. The acid strength distribution measurements were performed by ammonia temperature programmed desorption. As the P/Nb ratio increased, the P content also increased in the precipitate. However, when it was washed, a considerable P was removed from the structure, but extensive washing can remove P by the hydrolysis process. Increasing the content of orthophosphoric acid in the mixture decreased the K content in the products due to the ion-exchange process with hydrogen ions.