hide
Free keywords:
supported vanadium oxide, vanadia, SBA-15, methanol oxidation, spectroscopy, XPS, Raman
Vanadia in C4 selective oxidations
Abstract:
Nanostructured vanadia model catalysts, i.e. highly dispersed vanadium oxide supported on mesoporous silica SBA-15 (VOx/SBA-15), were prepared. The mechanism for the synthesis of VOx/SBA-15 was elucidated by detailed characterization of the individual synthesis steps using XPS and vibrational spectrocopy. The resulting surface vanadium oxide species (0 – 2.3 V/nm2), grafted on the inner pores of the SBA-15 silica matrix, consists of tetrahedrally coordinated vanadia as inferred from UV-VIS- and Raman spectroscopy. The prepared vanadia model catalysts were tested in the partial oxidation of methanol to formaldehyde yielding high formaldehyde selectivities of 94% at 350ºC. XPS and Raman analysis of the catalyst after reaction reveal the presence of methoxy as well as a significant amount of carbonaceous species on the surface. Our results demonstrate that a detailed understanding of partial oxidation reactions requires the combination of complementary spectroscopic techniques ultimately within one experimental set-up.
