Preparation, characterization and catalytic properties of promoted vanadium phosphate catalysts

Various transition metal promoted (M = Co, Cr, Mo) vanadium phosphate (VPO) catalysts were prepared using two different supports such as TiO2 (anatase) and γ-Al2O3. These samples were characterized by N2-adsorption, X-ray diffraction (XRD), FTIR-spectroscopy, UV–DRS and acidity measurements by potentiometric titrations. The catalytic properties were checked in the heterogeneous catalytic ammoxidation of 2-chloro benzaldehyde to 2-chloro benzonitrile as a model reaction. The characterization revealed the formation of (VO)2P2O7 in all the catalysts. However, the formation of crystalline proportions of mixed oxides was not observed. The catalytic ammoxidation runs revealed a significant effect of the promoter metals on the catalytic performance of the catalysts. A considerable increase in activity and selectivity was observed over promoted VPOs compared to bulk VPO solids. Almost complete conversion of 2-chloro benzaldehyde and about 90% selectivity of nitrile were observed using a 25%VPCrO/TiO2 catalyst.