Elucidating Structure–Property Relationships in the Design of Metal Nanoparticle Catalysts for the Activation of Molecular Oxygen

Abstract

A novel synthetic strategy for the design of metal nanoparticles by extrusion of anionic chloride precursors from a porous copper chlorophosphate framework has been devised for the sustainable aerobic oxidation of vanillyl alcohol (4-hydroxy-3-methoxybenzyl alcohol) to vanillin (4-hydroxy-3-methoxybenzaldehyde) using a one-step, base-free method. The precise nature of the Au, Pt, and Pd species has been elucidated for the as-synthesized and thermally activated analogues, which exhibit fascinating catalytic properties when subjected to diverse activation environments. By employing a combination of structural and spectroscopic characterization tools, it has been shown that analogous heat treatments have differing effects on extrusion of a particular metal species. The most active catalysts in this series of materials were the extruded Pt nanoparticles that were generated by reduction in H2, which exhibit enhanced catalytic behavior, when compared to its Au or Pd counterparts, for industrially significant, aerobic oxidation reactions.