Benzaldehyde is a crucial chemical product which acts as a versatile and important intermediate for other fine chemicals in industry. However, the catalysis used so far for the selective partial oxidation of benzyl alcohol to benzaldehyde are relatively less environmentally friendly or efficient.

Inn this study, palladium (Pd) loaded functionalized magnetic SBA-15 catalysts, Pd/FeMagSBA (iron oxide-supported) and Pd/CoMagSBA (cobalt oxide-supported), were prepared and applied as the heterogeneous catalysts for partial oxidation from benzyl alcohol to benzaldehyde under the conditions of solventless, atmospheric pressure, lower temperature (<100°C), no external bases and oxidant of molecular oxygen. The magnetic property of catalysts makes them to be easily recovered for reuse.

Different loadings of Pd, Fe, and Co, reaction temperatures, and stirring rates have been explored for the reaction. The catalysts have advantageo...[ Read more ]

Benzaldehyde is a crucial chemical product which acts as a versatile and important intermediate for other fine chemicals in industry. However, the catalysis used so far for the selective partial oxidation of benzyl alcohol to benzaldehyde are relatively less environmentally friendly or efficient.

Inn this study, palladium (Pd) loaded functionalized magnetic SBA-15 catalysts, Pd/FeMagSBA (iron oxide-supported) and Pd/CoMagSBA (cobalt oxide-supported), were prepared and applied as the heterogeneous catalysts for partial oxidation from benzyl alcohol to benzaldehyde under the conditions of solventless, atmospheric pressure, lower temperature (<100°C), no external bases and oxidant of molecular oxygen. The magnetic property of catalysts makes them to be easily recovered for reuse.

Different loadings of Pd, Fe, and Co, reaction temperatures, and stirring rates have been explored for the reaction. The catalysts have advantageous of easy separation (by magnetic field), good recyclability, and good durability for its catalytic activity.

The role of Pd and Co in the reaction were studied. The Pd/CoMagSBA catalyst, MPM-2, was selected as the optimized catalyst with fair conversion rate (51%) and higher selectivity (95%) after 3h40min at 95°C (although some other catalysts in this study could obtain higher yield). The activation energy (E_a) of MPM-2 was evaluated to be 17.6 KJ/mol.

To understand the reaction and the influence from basicity, Pd/CoMagSBA catalysts prepared from different precursors and methods were studied, CO₂-TPD-MS and CO₂-TPD-TCD were taken as the measurement for the basicity. A mechanism of the catalytic reaction was proposed. The catalyst is acid-base bifunctional and is predominantly basic, Pd nanoparticles and the O^2- of CoO acted as the Lewis base sites, while Co²⁺ acted as the Lewis acid sites.