Direct synthesis of hydrogen peroxide from hydrogen and oxygen over a Pd core-silica shell catalyst

Pd core-silica shell particles (Pd@SiO₂) were prepared by encapsulating Pd colloids with a silica shell through the Stöber method. The palladium core particles were well dispersed (Dispersion = 43%) and had uniform size (4 nm) and shape inside the porous silica shell. Pd@SiO₂ showed good catalytic activity (554 mmol H₂O₂/g Pd•h) for the direct synthesis of H₂O₂, which was better than those of impregnated Pd catalysts (Pd/SiO₂ and Pd/Al ₂O₃). It is expected that the stabilization of less coordinated Pd crystals in a highly dispersed state by core-shell formation is effective for the improvement of H₂O₂ production.