Preparation of iron borate-cerium oxide catalyst mixtures and use in the oxidation of benzyl alcohol

In this study demonstrated as a Master of Science Thesis, the mechanochemical preparation of iron borate-cerium oxide mixtures and their catalytic efficiency in the oxidation of benzyl alcohol were investigated. In the preparation of these mixtures, commercial CeO2 and Fe3BO6 (iron oxoborate), synthesized from Fe2(SO4)3 and boric acid, were used and catalysts in the composition of Fe3BO6 + xCeO2 (x = %1, 5, 10, 20 by mole) were obtained by ball milling. Fe3BO6 + xCeO2 mixtures were analyzed by XRD (X-Ray Diffraction), SEM (Scanning Electron Microscopy), FT-IR (Fourier Transform Infrared) Spectroscopy and BET (Surface Area Measurement Device) techniques. The oxidation reaction of benzyl alcohol to benzaldehyde was studied with the catalyst mixture containing 5% moles of CeO2, which showed the best surface area, crystallinity and structural properties. The oxidation reaction of benzyl alcohol was carried out in a stirred reactor under reflux in the presence of hydrogen peroxide oxidant. Samples taken from the reaction vessel at certain temperatures and periods of time were analyzed by GC-MS (Gas Chromatography / Mass Spectroscopy) instrument and the amount of benzaldehyde formed was determined. Optimization studies were carried out for the solvent type, temperature, reaction time and benzyl alcohol/catalyst ratio parameters, and the conversion graphs of benzyl alcohol to benzaldehyde were obtained. It was observed that the conversion increased with CeO2 addition up to a certain molar percentage but decreased again. 34.5% conversion and 81.3% benzaldehyde selectivity were reached after 4 hours of reaction at 90C in a solvent-free environment with the catalyst containing 5% CeO2. The catalyst was found to be stable when used under these conditions and there was no significant decrease in its activity after recycling for three times.