Fabricating highly-dispersed W-O-Si structure via silanols modulation over WOx/SiO2 catalyst enables efficient olefin metathesis

Silica-supported tungsten oxides (WO x /SiO 2 ) as industrial catalysts are widely applied for the metathesis of ethylene and butylene to propylene, yet often suffer from limited dispersion and stability due to ill-defined interactions between tungsten species and surface silanols microenvironment of silica support. In this work, the type and density of specific surface silanols in silica were successfully tailored by precisely controlling thermal pretreatment temperature. Multiple advanced characterizations and theoretical calculations revealed that vicinal-silanol-rich surface microenvironments were strongly associated with the formation of highly dispersed and stable isolated dioxo W (VI) -O-Si structure, while effectively suppressing the formation of less-active W-O-W aggregates. Under the comparable conditions, the optimized WO x /SiO 2 ‑ 550 catalyst with rich W (VI) -O-Si sites delivered an enviable propylene yield of over 67.9% in the olefin metathesis with a lower deactivation rate (0.069 h −1 ), far outperforming conventional catalysts. Moreover, the catalyst demonstrated satisfactory long-term stability over 200 h on stream and partial activity recovery upon oxidative regeneration. Mechanistic studies further suggested that the dioxo W (VI) -O-Si structure enhanced the adsorption and activation of olefins and favored the formation of surface species consistent with literature-proposed metal‑carbene intermediates, thereby improving both catalytic activity and propylene selectivity. These findings provide a fundamental understanding and a practical strategy for the rational design of highly-dispersed and stable supported tungsten catalysts for olefin metathesis.