Characterization and catalytic activity of vanadia supported on rice husk silica promoted samaria

A series of supported vanadia catalysts (2-10 wt'% V2O5) were prepared by wet impregnation method using rice husk silica promoted samaria as the support. Analysis of the catalysts was done by various physicochemical techniques like energy dispersive X-ray analysis (EDX), powder X-ray diffraction (XRD), BET surface area measurements, thermal analysis (TGA/DTA) and UV-Vis diffused reflectance spectroscopy (DR UV-Vis). Temperature programmed desorption (TPD-NH3) of ammonia was employed to quantify the various types of acid sites oil the surface of the catalysts. Catalytic activity of these catalysts was studied in liquid phase oxidation of benzyl alcohol with H2O2 as oxidant. The structural characterization of the catalysts suggests the formation of an orthovanadate (SmVO4) type phase at higher loadings of V2O5. The catalytic activity increases with vanadia loading up to 6 wt% V2O5, and further increase reduces the conversion rate as well as selectivity. (c) 2007 Elsevier B.V. All rights reserved.