Title:Structural and Compositional Effect of Heteropolyoxoanions [NiMo<sub>6-x</sub> W<sub>x</sub>O<sub>24</sub>H<sub>6</sub>]<sup>4-</sup> on the Catalytic Activity of Clean Selective Oxidation of Diphenylsulfide
VOLUME: 3 ISSUE: 2
Author(s):Mercedes Munoza, Maria G. Egusquiza, Irma L. Botto and Carmen I. Cabello
Affiliation:CIC PBA Researcher, Facultad de Ingeniería, UNLP.
Keywords:Clean oxidation, Diphenylsulfone, Diphenylsulfoxide, Hydrogen peroxide, Selective oxidation, W and Mo heteropolymetalates.
Abstract:Diphenyilsulfide oxidation by H2O2 as oxidant was studied through the structural effect of the isomorphous
W-Mo systems, Anderson type, with [Ni(II)Mo(VI)6-xW(VI)xO24H6]4- composition. These phases were proved as alternative
catalysts instead of W and Mo conventional systems. The characterization of the substituted phases was carried out by
different physico-chemical techniques (AAS, DRS, micro-Raman, XRD, TPR). The catalytic evaluation for the phase
NiW6 revealed that the process was selective to the sulfone formation (selectivity ~ 81-88 %) while the Ni-Mo bi-metallic
system (NiMo6) was only selective to the sulfoxide production (selectivity 98 %). The activity was 90 % at 60 and 180
min for the NiMo6 and NiW6 respectively, whereas the substituted phases presented intermediate values. The observed
differences can be related to the strength of the bridge bonds (Mo-O…Ni and W-O…Ni) associated to the higher electronegativity
and ionic potential of Mo with respect to W. Hence, the W-O bond is more reactive by the inductive effect of
Ni, which produces a higher oxidation of diphenyilsulfide to give sulfone, considering the electronic mobility in the redox
processes.
