Fm. Bautista et al., EFFECT OF PRECIPITATION MEDIUM AND THERMAL-TREATMENT ON STRUCTURE ANDTEXTURAL PROPERTIES OF CHROMIUM ORTHOPHOSPHATES, Reaction kinetics and catalysis letters, 49(1), 1993, pp. 173-181
The effect of the precipitation agent on the structure and textural pr
operties of CrPO4 (Cr/P=1) catalYsts has been studied. Catalysts obtai
ned in propylene oxide-aqueous ammonia exhibited higher thermal stabil
ity and, hence, greater surface areas and pore volumes than catalysts
obtained in propylene oxide or aqueous ammonia exclusively. The former
also showed a small,surface area decrease on increasing calcination t
emperature up to 1073 K. Nevertheless, calcination at 1273 K develops
in all cases crystalline CrPO4, showing the beta-structure. Moreover,
CrPO4 catalysts thermally treated below 1273 K only exhibited hydrogen
bonded hydroxy groups (nu(O-H) congruent-to 3450 cm-1).