A study of active sites for alkene and alkane oxidation over Mo and V mixed oxide catalysts using 18O tracer and Raman spectroscopy

The oxygen ions of MoO₃, V₂O₅, -VOPO₄, -Mg₂V₂O₇, -CoMoO₄and -Bi₂Mo₃O₁₂were exchanged with ¹⁸O via a reduction–oxidation method and the catalytic oxidation of alkene or alkane using ¹⁸O₂. The Raman bands of the catalysts shifted to lower frequencies by the exchange with ¹⁸O tracer. With MoO₃, V₂O₅, -VOPO₄and -Mg₂V₂O₇, the weak oxygen bonds were active to exchange, i.e., to be active for the oxygen insertion and oxidation reactions, but the strong bonds were less active. The results of exchange features on -Bi₂Mo₃O₁₂catalyst indicate that some sets of two lattice oxygen ions in a twin tetrahedra seem to be good for fitting and bonding with allyl intermediates.