One-Stone-Two-Birds: High-Density Single-Site Cobalt in Hierarchical Zeolite Boosts Aerobic Styrene Epoxidation

The catalytic efficiency of single-component cobalt catalysts (featuring exclusively Co-based active sites) for styrene epoxidation is significantly constrained by mass-transport limitations inherent to the micropores of conventional supports. To overcome this, we devise a one-stone-two-birds strategy synthesizing hierarchical CoSAPO-34 using a core-shell ZIF-67@SiO2 composite as a combined Co/Si source and template. This approach simultaneously creates (i) atomically dispersed, high-loading Co(II) sites within the framework and (ii) a hierarchical pore architecture (micro/meso/macro). The introduced meso/macropores dramatically enhance reactant accessibility to the active sites. This synergistic integration yields exceptional performance in aerobic styrene epoxidation: achieving 95.8% conversion with 70.0% selectivity toward styrene oxide, corresponding to a 67.1% yield in only 4 h at 90 °C. Remarkably, this represents the highest styrene oxide yield reported for a catalyst based on single-component cobalt active sites using air as the sole oxidant, and it was achieved within a short reaction time. This strategy provides a novel blueprint for designing efficient catalysts demanding maximized active-site accessibility.