Liquid phase oxidation of benzyl alcohol to benzaldehyde over chromium borophosphate catalyst synthesized by solution combustion method using different types of fuel

In this paper, chromium borophosphates have been prepared by the solution combustion method using different types of fuel and enhanced as a catalyst for liquid-phase oxidation of benzyl alcohol to benzaldehyde for the first time. Carbohydrazide, citric acid, hexamethylenetetramine, oxalyldihydrazide and urea used as an organic fuel and the obtained chromium borophosphates were systematically characterized by infrared spectroscopy, X-ray powder diffraction, thermogravimetry, scanning electron microscopy, and surface analysis techniques. They are structurally identical and thermally stable up to 1000 °C. According to fuel, their surface properties differ from each other and the long and short rod-like particles, which have a surface area between 7 and 19 m² g⁻¹, are formed. The effects of solvent type, reaction temperature, reaction time, peroxide amount and catalyst amount were also examined for catalytic studies, and the reaction conditions were optimized. As compared with the other fuels, hexamethylenetetramine-assisted synthesized chromium borophosphate catalyst provides high benzaldehyde conversion (52.09%) and selectivity (100%) under the optimized condition and has potential as a heterogeneous catalyst for oxidation reactions.