V. Indira et al., TRANSITION-METAL SUBSTITUTED 12-TUNGSTOPHOSPHATES - CHARACTERIZATION AND EVALUATION OF THEIR PERFORMANCE AS OXIDATION CATALYSTS, Indian journal of chemistry. Sect. A: Inorganic, physical, theoretical & analytical, 37(6), 1998, pp. 473-481
Citations number
41
Categorie Soggetti
Chemistry
Journal title
Indian journal of chemistry. Sect. A: Inorganic, physical, theoretical & analytical
Tetrabutylammonium salt of [PW12O40](3-) and its transition metal (Mn2
+, Fe2+, Co2+ and Cu2+) substituted compounds are characterized by ele
mental analysis, thermogravimetric and spectroscopic techniques. Therm
al stability of these compounds decreases after metal ion substitution
, but the cobalt substituted compound is relatively more stable. The c
obalt substituted compound is found to be a good catalyst for the oxid
ation of cyclohexanol and the catalytic activity of the transition met
al substituted compounds decreases in the order: Co2+ much greater tha
n Mn2+ > Fe2+ greater than or equal to Cu2+. Detailed studies of the r
eaction in the presence of Co2+ and Mn2+ substituted compounds reveal
that the transition metal ions are initially oxidized to a higher oxid
ation state which then act as the catalytic centre for the reaction. T
he enhanced catalytic activity of Co2+ substituted compound is due its
oxidation to Co4+ in the presence of H2O2 which is evidenced from EPR
and UV-VIS spectroscopic studies.