Defect-healing driven stable Pt species formation in Silicalite-1 zeolite for base-free alcohol oxidation in water

Hydrothermal defect healing selectively stabilizes catalytically active Pt ensembles by removing weakly anchored species in Silicalite-1. • Confined Pt ensembles exhibit enhanced intrinsic activity, lower activation energy, and improved oxygen activation in aerobic alcohol oxidation. • Catalysis occurs on externally accessible Pt sites and mesoporous regions, enabling efficient oxidation of bulky alcohol molecules. • Defect-healing-induced restructuring provides a general strategy to optimize active site stability and catalytic efficiency in heterogeneous oxidation catalysts. The development of robust Pt catalysts that simultaneously achieve efficient O 2 activation, high intrinsic activity, and structural stability remains a central challenge in aerobic alcohol oxidation. Herein, we report a hydrothermal defect-healing strategy to restructure impregnated weakly anchored Pt species in Silicalite-1 zeolite into highly stable Pt ensembles confined within the zeolite framework (Pt@S-1). Spectroscopic and microscopic analyses reveal that hydrothermal treatment heals silanol defects and drives controlled restructuring of isolated Pt atoms into small ensembles strongly stabilized by the zeolitic microenvironment. The resulting Pt@S-1 catalyst exhibits markedly enhanced intrinsic activity, achieving a turnover frequency of 5560 h −1 in aqueous aerobic oxidation of 3,5,5-trimethylhexanol, exceeding conventional nanoparticle and impregnated analogues by over one order of magnitude despite significantly lower Pt loading. Kinetic studies demonstrate a reduced apparent activation energy (65.7 kJ mol −1 ) and nearly first-order dependence on O 2 pressure, indicating facilitated O 2 activation and optimized competitive adsorption between oxygen and alcohol substrates. The zeolite confinement and aqueous reaction medium synergistically promote selective formation of isononanoic acid and ester while suppressing catalyst sintering and thermal runaway. Furthermore, the catalyst shows excellent stability without requiring hydrogen pretreatment or additional base. This work establishes defect-healing-induced restructuring as an effective approach to generate stable and highly active catalytic ensembles from labile atomically dispersed precursors and provides fundamental insights into structure–activity relationships governing selective aerobic alcohol oxidation. Download: Download high-res image (150KB) Download: Download full-size image A hydrophilic zeolite-supported Pt catalyst cooperates with water to drive base-free and H 2 -free aerobic oxidation of long-chain alcohols under mild aqueous conditions, achieving selective acid formation while suppressing energy demand, metal sintering, and organic solvent use.