Síntese de novos catalisadores a base de nióbio para oxidação de moléculas industrialmente atrativas

Abstract

A new niobium compound containing surface peroxo groups was obtained after treatment with hydrogen peroxide. Raman scattering and IFTR absorption spectroscopy and diffuse reflectance measurements confirm the presence of peroxo groups. N2 adsorption/desorption isotherms showed a drastic change in the specific surface area after treatment with hydrogen peroxide, from 195 m²/g to 4 m²/g. In terms of catalytic activity, cyclohexene oxidation reached considerable selectivity for cyclohexene-1-one (45% for 6 h of reaction at 70 °C) in the liquid phase using H2O2 as oxidant. Product distribution and percentage conversion were dependent on the oxidant used (H2O2, oxone, and T-BHP). The selectivity of the new material is due to the presence of peroxo groups on the surface caused by the treatment with H2O2, reducing its acidity and specific area. A subsequent study was carried out to insert transition metals in the structure of L-AmNbO. The Fe-AmNbO, Co-AmNbO, and Mn-AmNbO materials were tested in the oxidation of cyclohexene and Congo Red azo dye, with significant discoloration and conversion rates to Fe-AmNbO.