Effect of Different Calcination Duration on Physicochemical Properties of Vanadium Phosphate Catalysts

Abstract

Vanadium phosphate catalysts have been prepared by calcining VOHPO₄4·0.5H₂O which were prepared via two methods i.e. organic (VPO method) and dihydrate (VPD method) routes for different duration under anaerobic atmosphere. Increasing the calcinations duration led to a decrease in total surface area. It is also promote the formation of V⁵⁺ phase in the catalysts. Scanning electron microscopy clearly revealed that the morphologies of all catalysts composed of plate-like crystallites that were arranged into the characteristic of rosette cluster. However, by increasing the pretreatment duration in an inert environment, the rosette-shape of the clusters which normally obtained in reaction condition was collapsed. Prolong the duration of N₂ calcination also resulted in an increment in the amount of oxygen desorbed (from O₂-TPD) and removed (obtained from H₂-TPR).