Influence of the nitridation parameters on the stoichiometry, structure and specific surface area of zirconium phosphate oxynitride catalysts

Oxygen can be exchanged by nitrogen atom in high surface specific and amorphous zirconium phosphate solids thank to nitridation process. Various nitridation parameters influence the O/N substitution. A minimum temperature of 550 degrees C is required for efficient nitridation whereas temperature higher than 850 and 1300 degrees C induces reduction of phosphorus and zirconium atoms respectively. In intermediate temperature range, O/N exchange increases with temperature as well as with time of nitridation. In these conditions, the ZrPON solids obtained are X-ray amorphous and a slight decrease of precursor specific surface area is observed (110-210 m(2) g(-1)). (C) 1999 Kluwer Academic Publishers.