Synthesis and catalytic activity of periodic mesoporous materials incorporating gold nanoparticles

A mesoporous silica containing gold nanoparticles (mpAu-SiO₂) has been obtained by one pot synthesis, starting from tetraethylorthosilicate (TEOS) and colloidal gold particles (2-5 nm) stabilized with N-[3-(triethoxysilyl)propyl] O-2(dicetylmethylammonium)ethyl urethane. This stabilizer ligand interacts with gold nanoparticles through the quaternary ammonium ions, whose long chains also show affinity for the cetyltrimethylammonium surfactant. On the other hand, the triethoxysilyl group is adequate to undergo co-condensation with TEOS during the formation of the silica. The periodic mesoporous structure of the mpAu-SiO₂ materials was assessed by X-ray diffraction, TEM and isothermal gas adsorption of calcined mpAu-SiO₂ (S_BET 488 m² × g ^-1, pore size 3.5 nm). This material exhibits high activity and reusability for the solventless, aerobic oxidation of secondary alcohols to ketones.