Design strategy for effective supported Au–Pd catalysts for selective oxidation of 5-hydroxymethylfurfural under mild conditions

Abstract

Preparation of catalysts with predesigned composition, structure and distribution of active species is an important challenge as such characteristics determine the catalytic performance. This work introduces a strategy to rationally design effective catalysts for the selective HMF oxidation to FDCA under mild conditions. We show the effect of the preparation technique (impregnation, deposition–precipitation, impregnation–reduction) on the active species formation in ZrO₂-supported Au, Pd, and AuPd catalysts, discuss the effects of the metal dispersion and state on the catalyst performance and provide insight into reaction pathways of aerobic HMF oxidation over bimetallic AuPd/ZrO₂ catalysts. The impregnation–reduction allows preparing the active mono- and bimetallic catalysts in contrast to other techniques used, with the bimetallic formulations featuring the enhanced catalyst performance caused by the synergistic effect. The alloyed Au_0.56Pd_0.44/ZrO₂ catalyst shows a per-site TOF of 0.25 s⁻¹ that is ∼4 times higher than the one for the Au/ZrO₂ catalysts.