Determination of surface sites using infrared spectroscopy for mixed oxides of vanadium obtained by the sol–gel method

The presence of Lewis and Brønsted acid sites in calcined mixed oxides 10% V2O5/SiO2, 10% V2O5/TiO2, and 10% V2O5/Al2O3 obtained by sol–gel method was determined through infrared spectroscopy using pyridine as a molecular probe. Texturally, they are formed by mesopores and present high specific surface area and controlled porosity. Scanning electron microscopy revealed that vanadium is homogeneously distributed in the materials. The infrared spectra of samples submitted to different temperatures after the absorbance of pyridine were obtained. The existence of active metal ions on the surface of the materials was evidenced by the presence of Lewis and Brønsted acid sites, which confers them potential catalytic properties.