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Quantitative FTIR studies of alumina hydroxyl groups have been used to measure the surface coverage of V/Al2O3 catalysts. The IR spectra show a preferential consumption of the most basic hydroxyls (3769 cm−1) with the initial V uptake. The integrated area of the hydroxyl region was used to calculate the surface coverage of the catalysts. The surface coverage increased to 0.63 as the V loading increased to 6.7 wt%. The surface coverage results obtained from IR were compared to those measured by ion scattering spectroscopy (ISS) and CO2 chemisorption. The surface coverages measured by ISS were comparable to those obtained by IR. In contrast, CO2 chemisorption appears to overestimate the surface coverage of the catalysts. The overestimation of the surface coverage by the CO2 chemisorption method is attributed to the preferential adsorption of the V phase onto the most basic hydroxyls, the same sites which interact with CO2.

The distribution of supported species in a series of W/TiO2 catalysts (1.8 – 28 wt% WO3) has been determined by Raman and X-ray photoelectron spectroscopy (XPS, ESCA). The results show that three tungsten species are present on oxidic W/TiO2 catalysts. A tungsten interaction species is formed almost exclusively for catalysts with W loadings lower or equal to 6.7 wt% WO3. WO3 is observed above 6.7 wt% WO3. For W loadings higher than 10 wt%, a disordered W species WDS is also present. The amounts of WDS and WO3 increase with increasing W content above 10 wt% WO3.