Dealuminization for a Modified (Si–OH)n–Pt Interface: Self-Activation of Pt/NaY Catalysts for Oxidation of Ethylene Glycol in a Base-Free Medium

Aqueous oxidation of bio-derived ethylene glycol to glycolic acid represents a sustainable route to polyglycolic acid. However, a strong acidic/basic oxidative medium often causes structural evolution and metal sintering of supported metal catalysts. We reported an unusual self-activation of Pt/NaY catalysts for enhanced oxidation of ethylene glycol in a base-free medium. Owing to a dealuminization-induced shortened Si-OH bond and formulation of a Pt-acid interface caused by glycolic acid, the activity of self-activated Pt/NaY catalysts displays a 2-fold enhancement compared with fresh ones. As the key finding in this work, dealuminization is found to cause an electronic coupling effect through shortened Si-OH bonds and formulating the (Si-OH)-Pt interface. Such a coupling effect leads to electron-rich nature of Pt sites for oxidation reactions, and thus, the self-activated Pt/NaY catalysts display leading performances in terms of activity and durability as seen in literature reports. Various characterization techniques, including transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy, provide consistent and supporting evidence for such unique interfacial behaviors. Catalyst characterization further reveals that metallic Pt-0 species is the intrinsically active phase for s-activation rather than p-activation of ethylene glycol molecules. Isotopic tests and kinetic modeling further confirm the reaction mechanism on the surface of fresh and spent Pt/NaY catalyst samples. The special activity enhancement of spent catalysts can be applied to investigate the plausible mechanism of various other oxidation reactions.