Synthesis, characterization, and activity studies of V2O5/ZrO2-SiO2 catalysts

A porous ZrO2-SiO2 mixed oxide catalyst support was synthesized by a sol-ge l method using 2,4-pentane dione as the complexing agent. A series of suppo rted vanadia catalysts with V2O5 contents ranging from 1-10 wt% were prepar ed using the ZrO2-SiO2 mixed oxide as the support. Characterization techniq ues such as BET surface area, solid-state V-51 and H-1 MAS NMR, and diffuse reflectance FT-IR were employed for the structural elucidation studies of the support and catalysts. Partial oxidation activities of the catalysts we re determined using ethanol oxidation as the model reaction. V-51 NMR studi es indicated the presence of tetrahedally coordinated vanadate species at l ower vanadia contents and octahedral vanadyl species at higher V2O5 loading s. H-1 MAS NMR spectra showed peaks corresponding to hydroxyl groups of zir conia and silica. Ethanol partial oxidation activities of the catalysts ind icated higher acetaldehyde selectivity for the V/Zr-Si catalysts in compari son to the V2O5/ZrO2 and V2O5/SiO2 catalysts. (C) 1999 Academic Press.