Styrene oxide transformation on SiO2-stabilised Ag nanoparticles prepared by gamma-radiolysis

Ag nanoparticles have been prepared by gamma-radiolysis of AgNO3 in aqueous matrix of SiO2 (Aerosil 200) in the presence of 2-propanol as OH radical scavenger. The presence of SiO2 prevents rapid agglomeration of Ag and the Ag nanoparticles formed become attached to SiO2. Transmission electron microscope (TEM), XRD and UV-vis measurements have shown that by adjusting the SiO2/solvent ratio the size of Ag nanoparticles can be controlled. Decreasing solvent/SiO2 ratio and high dose rate facilitated formation of small particles of 2-6 nm on SiO2. The in situ generation of Ag particles on silica has been attributed to the participation of solvated electrons formed at the silica/solvent interfacial layer. The Ag/SiO2 catalysts were tested in transformation of styrene oxide in hydrogen/He stream. The main reaction pathway is removal of oxygen. The low yield of aldehyde and alcohol can be attributed to low surface coverage of hydrogen on Ag.