New Niobate Based Catalyst for Organic Dye Oxidation: A Mechanistic Approach

In this work, we aimed to demonstrate new polyoxoniobate containing surface peroxo groups obtained after the treatment of niobic acid with hydrogen peroxide and lyophilization process. Raman and diffuse reflectance measurements confirm the presence of peroxo groups in the new polyoxometalate. Isotherms from N₂ adsorption/desorption have evidenced a drastic change in specific surface area after treatment with hydrogen peroxide, from 195 m².g⁻¹ for Nb1 to 4 m².g⁻¹ for Nb3. Catalytic studies were performed for Congo red (CR) oxidation using H₂O₂ as oxidizing promoter. The results showed a new material with larger specific area, smaller particle size and an increase in peroxo groups, thus leading to higher catalytic response of discoloration of the Congo red (about 70% for Nb3 and close to 20% for the other catalysts) as compared with the raw material, without previous treatment.