Switching HMF Oxidation Selectivity From FDCA to HMFCA via Carbon-Induced Constructing Strong Metal-Support Interaction Between Gold Nanoparticles and Al2O3.

Constructing strong metal-support interaction (SMSI) between gold nanoparticles and conventionally nonreducible oxide supports presents a significant challenge, and the mechanistic understanding of SMSI in selective catalytic reactions remains limited. Herein, we demonstrate a carbon induced SMSI between the irreducible oxide alumina and Au nanoparticles (Au/Al2O3@C-SMSI). The resulting system exhibits electronic and geometric features analogous to classical SMSI, with the driving force inherently rooted in the nature of Au-Al and Au-O-Al interfacial bonding. The Au/Al2O3@C-SMSI catalyst exhibits exceptional selectivity toward the partial oxidation product 5-hydroxymethyl-2-furancarboxylic acid (HMFCA) in the oxidation of 5-hydroxymethylfurfural (HMF), achieving a remarkable HMFCA yield of 98.5%. Advanced characterization combined with density functional theory calculations reveals that the high selectivity stems from the synergistic differential activation of C─H bonds and competitive adsorption of HMFCA on Au and Al sites. Furthermore, the Au/Al2O3@C-SMSI catalyst maintain high activity without significant deactivation after six consecutive catalytic cycles using industrial-grade HMF (85% purity) as the substrate, demonstrating strong antipoisoning capability and promising potential for industrial application. This study offers an innovative approach for establishing SMSI on nonreducible oxide supports and opens new avenues for designing highly active and selective heterogeneous catalysts.