Resonance Raman Spectroscopic Study of Alumina-Supported Vanadium Oxide Catalysts with 220 and 287 nm Excitation

Abstract

We present detailed resonance Raman spectroscopic results excited at 220 and 287 nm for alumina-supported VO(x) catalysts. The anharmonic constant, harmonic wavenumber, anharmonic force constant, bond dissociation energy, and bond length change in the excited state for double bonded VO and single bonded V-O were obtained from fundamental and overtone frequencies. Totally symmetric and nontotally symmetric modes could be discerned and assigned on the basis of the overtone and combination progressions found in the resonance Raman spectra. Selective resonance enhancement of two different vibrational modes with two different excitation wavelengths was observed. This allowed us to establish a linear relationship between charge transfer energy and VO bond length and, consequently, to assign the higher-energy charge transfer band centered around 210-250 nm in the UV-vis spectra to the VO transition.

Resonance Raman and surface- and tip-enhanced Raman spectroscopy methods to study solid catalysts and heterogeneous catalytic reactions

“…1 This method is in agreement with methods 1-3 and can be considered as a band-specific unified method. 1 This method is in agreement with methods 1-3 and can be considered as a band-specific unified method.…”

UV Raman Spectroscopic Characterization of Catalysts and Catalytic Active Sites

“…9 a Photocatalytic H 2 evolution activity on TiO 2 samples calcined at different temperatures normalized by specific surface area; b UV Raman spectra of TiO 2 (A)/ TiO 2 (R)-n samples excited at 325 nm; c Photocatalytic H 2 evolution activity on TiO 2 (A)/ TiO 2 (R)-n samples with increasing amount of anatase phase on the surface of rutile TiO 2 . The anatase contents estimated from XRD and UV Raman spectroscopy for TiO 2 (A)/TiO 2 (R)-n samples are also displayed [104] 177.3 nm have been developed by Peter Stair et al [24,117] and our group [118,119], which is necessary for UV and deep UV resonance Raman spectroscopic study in catalysis. And the primary results show the advantages of these techniques.…”

Role of dispersion of vanadia on SBA-15 in the oxidative dehydrogenation of propane

“…[30,31] Recent resonant Raman spectroscopy studies with different excitation-laser wavelengths even point to the presence of three different monomeric VO 4 species on alumina at a loading as low as 0.16 V/nm², although only a single band is resolved in the UV/Vis spectrum. [32,33] The presence of a mixture of different species, including non-monomeric vanadia, has been transmitted also to vanadia on SBA-15, based on near-edge X-ray absorption fine structure (NEXAFS) measurements. [34,35] The shift in the edge energy and adsorption maxima of the dehydrated V/SBA-15 samples in Fig.…”

“…[21] The band at 925 cm -1 is thus assigned to an out-of-phase vanadium-silicon support vibration, in agreement with recent literature. [30][31][32][33]39] The presence of three-dimensional (bulklike) vanadia can be sensitively monitored using Raman spectroscopy, mainly by vibrational resonances at 144, 284, 303, 404, 482, 525, 702 and 994 cm -1 . [19,22] All these peaks are visible in the spectrum of 14V/SBA-15 in Fig.…”