Vanadium antimonate as a partial oxidation catalyst.

S. LARRONDO; BEATRIZ IRIGOYEN; BARONETTI GRACIELA,; AMADEO NORMA,

APPLIED CATALYSIS A-GENERAL

Elsevier

Lugar: Amsterdam; Año: 2003 vol. 250 p. 279 - 285

0926-860X

The catalytic selective oxidation on vanadium antimonate oxides partially doped with titanium was studied. Solids withnominal composition VSbO4, V0.8SbTi0.2O4 and VSb0.8Ti0.2O4 were prepared by solid-state reaction. The solids werecharacterised by sorptometry, X-ray diffraction (XRD), temperature programmed reduction (TPR) and X-ray photoelectronspectroscopy (XPS). Catalytic tests were carried out in a fixed-bed reactor using toluene and air as reactants. It was found thatpartial substitution of V or Sb by Ti produces changes in the unit-cell composition and the redox properties of the solids. Apossible role for V and Sb in the reaction mechanism of partial oxidation was established. Vanadium sites (V4+) are involvedin the incorporation of gaseous oxygen as lattice oxygen and hold the Sb sites in an oxidation state (Sb5+) high enough toinsert the lattice oxygen in the hydrocarbon molecule. A relationship between activity and V4+/Sb5+ ratio of the unit-cellwas found. The selectivity to benzaldehyde is correlated with the redox properties of the solids while the selectivity to totaloxidation products could be interpreted by the site isolation theory.