Characterization and catalytic studies of PVD synthesized Mo/V/Nb/Te oxide catalysts

Multicomponent Mo/V/Nb/Te oxide catalysts were synthesized using physical vapor deposition (PVD) onto the substrates of Si wafers and of honeycomb cordierites. The PVD films were prepared at different metal deposition sequences and were subsequently calcined at different temperatures and environment (air or N-2). The PVD films on Si wafer were characterized using several surface techniques, including X-ray photoelectron spectroscopy (XPS), near-edge X-ray absorption fine structure (NEXAFS), and secondary ion mass spectrometry (SIMS). In parallel, PVD films on cordierites were evaluated in a fixed-bed reactor for the selective oxidation of propane to acrylic acid. The combined synthesis, characterization, and reactor studies provided clear evidence that the surface compositions and the catalytic properties of the Mo/V/Nb/Te oxide catalysts depend strongly on the metal deposition sequence, calcination temperature, and calcination environment. (C) 2004 Published by Elsevier Inc.