Carbon-supported lacunary Keggin 11-tungstophosphates modified with transition metals as catalysts in 2-(methylthio)-benzothiazole sulfoxidation

ROMANELLI, G.; MIRTA NOEMÍ BLANCO; L. R. PIZZIO

Salamanca, España

Congreso; IX EuropaCat; 2009

Spanish Catalysis Society, Catalysis Division of the Portuguese Chemical Society

Lacunary tungstophosphate compounds with Keggin structure modified with transition metal ions [PW11O39M(H2O)]5-, where M= Ni2+, Co2+, Cu2+ or Zn2+, were synthesized and supported on activated carbon to obtain the PW11MC catalysts. By FT-IR and DTA-TGA it was concluded that the [PW11O39M(H2O)]5- species are interacting with the functional groups of the support, and that the thermal treatment leads to the loss of the coordinatively bonded water molecules, without any noticeable anion degradation. The activity and selectivity of the catalysts in the sulfoxidation reaction of 2-(methylthio)-benzothiazole was evaluated. The reaction was carried out in acetonitrile as solvent using H2O2  35% w/v as a clean oxidant. The conversion values decreased in the following order PW11NiC > PW11CuC > PW11CoC > PW11ZnC, which is the same order of the isopropanol decomposition into acetone and is related to the reducibility of the species present in the catalysts. The selectivity to sulfoxide was higher than 69 %. The catalyst can be re-used without appreciable loss of the catalytic activity at least for three times.