Controlling Multiple Active Sites on Pd-CeO2 for Sequential C-C Cross-coupling and Alcohol Oxidation in One Reaction System

Abstract

Ceria (CeO2)-supported metal catalysts have been widely utilized for various single-step chemical transformations. However, using such catalysts for a multistep organic reaction in one reaction system has rarely been achieved. Here, we investigate multiple active sites on Pd-CeO2 catalysts and optimize them for a multistep reaction of C-C cross-coupling and alcohol oxidation. Atomic-level imaging and spectroscopic studies reveal that metallic Pd-0 and Pd-CeO2 interface are active sites on Pd-CeO2 for C-C cross-coupling and oxidation, respectively. These active sites are controlled under the structural evolution of Pd-CeO2 during reductive heat-treatments. Accordingly, we found that optimally reduced Pd-CeO2 catalysts containing similar to 1.5 nm-sized Pd nanoclusters with both sites in balance are ideal for multistep chemical transformations in one reaction system. Our strategy to design supported metal catalysts leads to one-pot sequential synthetic protocols for pharmaceutical building blocks.