Transition metal-modified polyoxometalates supported on carbon as catalyst in 2-(methylthio)-benzothiazole oxidation

ROMINA FRENZEL; GUSTAVO P. ROMANELLI; MIRTA N. BLANCO; LUIS R. PIZZIO

journal of chemical sciences

Springer

Lugar: Bangalore; Año: 2014

0974-3626

Polyoxometalates with lacunary 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 DTATGA 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, an emerging environmental pollutant, were evaluated. 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: PW11NiC > PW11CuC > PW11CoC > PW11ZnC, with selectivities to sulfoxide higher than 69%. The catalyst could be reused without appreciable loss of the catalytic activity at least three times. The materials were found to be efficient and recyclable catalysts for 2-(methylthio)- benzothiazole sulfoxidation in order to obtain a more biodegradable product than the corresponding substrate.