Synthesis, characterization and catalytic activity of Nd203 supported V205 catalysts

A series of rare-earth ncodyrnia supported vanadium oxide catalysts with various V20, loadings ranging from 3 \0 15 wt. ')f. were prepared by the wet impregnation method using ammonium mciavanadate as the vanadium precursor. The nature of vanadia species formed on the support surface is characterized hy a series of different physicochemical techniques like X-ray diffraction (XRD). Fourier transform infrared spcctroscopy (Fl'IR). BET surface area. diffuse reflectance UV~V)s spectroscopy (DR UV-vis). thermal analysis (TG-DTG/DTA) and SEM. The acidity of the prepared systems were verified by the stcpwisc temperature programmed desorprion of ammonia (NH,-TPDj and found that the total acidity gets increased with the percentage of vanadia loading. XRD and FT1R results shows the presence of surface dispersed vanadyl species at lower loadings and the formation of higher vanadate species as the percentage composition of vanadia is increased above 9 wt.%. IThe low surface area of the support. calcination temperature and the percentage of vanadia loading are found to influence the formation of higher vanadia species. The catalytic activity of the V20,-Nu20, catalysts was probed in the liquid phase hydrnxylation of phenol and the lresult show that the present catalysts are active at lower vanadia concentrations. iD2005 Elscvicr B.Y. All rights reserved