Variation of the vanadium oxidation state within a VPO catalyst layer in a membrane reactor: XPS mapping and modelling

Calibration of the X‐Ray Photoelectron Spectroscopy Binding Energy Scale for the Characterization of Heterogeneous Catalysts: Is Everything Really under Control?

“…In particular, X‐ray photoelectron spectroscopy (XPS) is a powerful technique for the identification and quantification of elements that are present at the surface of solids 1. Determining the XPS binding energy (BE) of peaks characteristic of the catalytically active elements helps to reveal their oxidation state and to correlate this information with the catalytic performance 2. XPS also helps to describe the dispersion of an active phase on a support.…”

Effect of the use in circulating fluidized bed on the performance of a VPO catalyst: Characterization and transient studies

“…However, Casaletto et al [26] found a value of 4.4 in alumina supported catalysts prepared in an aqueous medium. In addition, Suchorski et al [21] reported values of V ox as high as 4.76 in a VPO catalyst layer (organic preparation) on a tubular membrane. The oxidation state of vanadium on the surface decreases after the reaction step for both catalysts, but the change was smaller in the fresh catalyst, in spite of the fact that it had released more oxygen.…”

“…The main problem that appears in this analysis results from the multiplet splitting that leads to different line shapes of the V 5+ , V 4+ and V 3+ components and makes it very difficult to develop a set of fitting parameters for each valence state [21]. To overcome this problem, Coulson et al [22] elaborated a correlation between the first moment of the O 1s and V 2p 3/2 peaks.…”

“…Therefore, in this work the analysis of the XPS spectra has been performed by a curve-fitting procedure in order to distinguish vanadium species in different oxidation states. All the spectra can be deconvoluted into two components at 516.7-516.8 and 517.9-518.0 eV which can be assigned to V 4+ and V 5+ species, respectively [21,23,24].…”

Effect of direct ultrasound synthesis via a sesquihydrate route on bismuth‐promoted vanadyl pyrophosphate catalysts

“…Figure shows a high‐resolution XPS spectrum containing the O1s, V2p 1/2 , and V2p 3/2 photoelectron peaks for VPSU, VPSB1, VPSB3, and VPSB5. The V2p 3/2 peak could be separated into two components at 516.9 and 518.0 eV (Figure ), which can be related to V 4+ and V 5+ species, respectively . The percentages of V 4+ and V 5+ species present were calculated using the deconvolution of the V2p 3/2 peak.…”