Determination of the Maximum Vanadium Oxide Coverage on SnO₂ with a High Surface Area by Raman Spectroscopy

Some V/SnO 2 catalysts with high specific surface areas have been characterized by Raman spectroscopy. Surface support modes, which are intense in the case of SnO 2, have been especially investigated. Their relative intensity decreases with an increase in vanadium loading. This damping phenomenon is not due to a vanadium doping effect into SnO 2 but to the coverage by the polymerically supported phase. Here, a new method for the estimation of the maximum coverage of the supported vanadium oxide on SnO 2 was developed. It was deduced from the evolution of the relative intensity of surface support modes. The first step of the method consists of measuring and calibrating the relative intensity of SnO 2 surface modes according to the specific surface area. Then, the vanadium coverage is calculated from the difference in the relative intensity of surface modes between the covered and the uncovered support. A maximum surface coverage of 3V/nm 2 was found by this method.