Hydrodeoxygenation of sulfoxides to sulfides by a Pt and MoOx co-loaded TiO sub(2) catalyst

Supported metal nanoparticle catalysts were studied for the hydrodeoxygenation of sulfoxides to sulfides under solvent-free and mild conditions (50-155 degree C, 1 or 7 atm H sub(2)). The catalytic activity for the model reaction of diphenyl sulfoxide depended on the type of metals, support materials and co-loaded oxides of transition metals (V, Nb, Mo, W, Re). Pt and MoOx co-loaded TiO sub(2) (Pt-MoOx/TiO sub(2)) showed the highest activity. Pt-MoOx/TiO sub(2) was reusable after the reaction and was effective for the reduction of various sulfoxides and showed a higher turnover number (TON) than previously reported catalysts. Using Pt-MoOx/TiO sub(2), benzylphenylsulfone was reduced by H sub(2) to give phenylbenzyl sulfide viabenzylphenyl sulfoxides, which represented the first example of catalytic conversion of a sulfone to a sulfide by H sub(2). Characterization studies of Pt-MoOx/TiO sub(2) show that the surface of TiO sub(2) is covered by small (or thin layer) Mo oxide species with exposed Mo cations as Lewis acid sites, and 4-5 nm sized Pt metal nanoparticles are supported on the Mo oxide-covered TiO sub(2).