Carbon-supported metal-modified lacunary tungstosilicic

ROMINA FRENZEL; GABRIEL SATHICG; MIRTA BLANCO,; GUSTAVO P. ROMANELLI; LUIS RENÉ PIZZIO

JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2015 vol. 403 p. 27 - 36

1381-1169

Lacunary tungstosilicic polyoxometallates modified with transition metal ions [SiW11O39M(H2O)]6− where M=Mn2+, Fe2+, Co2+or Cu2+, were synthesized and supported on activated carbon to obtain the SiW11MC catalysts. The samples were characterized by FT-IR, XRD, N2 adsorption?desorption measurements,and the acidic properties were determined using the isopropanol dehydration test reaction.The activity and selectivity of the catalysts were evaluated in the selective oxidation of aseries of sulfides to sulfoxides or sulfone. The reaction was carried out in acetonitrile as solvent using H2O2 35% p/V as a clean oxidant. The conversion values decreased in the following order:SiW11MnC> SiW11FeC > SiW11CuC > SiW11CoC. The catalysts were reused without appreciable loss of their catalytic activity. It was found that the activity of the catalysts decreases in parallel with the increment in the reduction temperature values. The most easily reducible catalyst displayed the highest conversion values. We found a convenient and selective procedure for oxidizing sulfides to sulfoxides or sulfones using aqueous hydrogen peroxide and a catalytic amount of lacunary tungstosilicic polyoxometallates supported on carbon at low temperatures (20-50 ºC) in a reasonably short reaction time