The complex heteropolyoxotungstates of formula K-10[M-4(H2O)(2)(PW9O34)(2)]center dot 20H(2)O (PWM) with M=Co(II), Zn(II), Cu(II) and Mn(II), and their precursor, Delta-Na8HPW9O34 center dot 19H(2)O (Delta-PW9), were evaluated as bulk in limonene epoxidation using H2O2 as oxidant, 1,2 dicloroethane as solvent and metiltricaprilamonium chloride (Aliquat 336) as a phase transfer agent at 2 degrees C. In these biphasic conditions PWCu was the most active phase. Subsequently this phase was supported on gamma-Al2O3, the metal load was determined by AAS, ICP and X-ray fluorescence and the preservation of PWCu structure was confirmed by XPS and Raman microprobe. PWCu/gamma-Al2O3 was evaluated at 70 degrees C with acetonitrile as solvent. The pure PWCu showed a higher conversion to epoxide but lower selectivity due to the formation of secondary products. (C) 2012 Elsevier B.V. All rights reserved.
Advance in the study of limonene epoxidation with H2O2 catalyzed by Cu(II) complex heteropolytungstates / Maria G., Egusquiza; Carmen I., Cabello; Irma L., Botto; J., Thomas Horacio; Sandra, Casuscelli; Eduardo, Herrero; Gazzoli, Delia. - In: CATALYSIS COMMUNICATIONS. - ISSN 1566-7367. - STAMPA. - 26(2012), pp. 117-121. [10.1016/j.catcom.2012.04.030]