Preparation of palladium oxide nanoparticles-encapsulating porous oxide catalysts for oxidation utilizing a silsesquioxane ligand

The controlled calcination of Pd complexes bearing a silsesquioxane-amine ligand (c-C5H9)7Si7O10{OSi(Me2)CH2CH2CH2NH2} (1), at 823 K in air stream for 4 h afforded porous silicas of high surface areas and uniformly controlled micropores of ca. 0.6 nm diameter encapsulating monodispersed palladium oxide nanoparticles. The calcination after the impregnation of palladium complexes bearing 1 onto titanium oxide afforded oxides with both meso- and micropores. These catalysts showed excellent catalytic activities towards the aerobic oxidation of benzyl alcohol, especially even in water (benzaldehyde yield up to 87% in air at 353 K for 24 h with 0.10 mol% Pd).