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 Pt0 species is the intrinsically active phase for σ-activation rather than π-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.