Abstract: The mechanism of multicomponent oxide bismuth vanadomolybdate catalysts for the seldctive oxidation of propane to acrolein has been investigated by IR spectroscopy. The results of IR spectra show that when cation vacancies are introduced randomly in the lattice by replacing V⁵⁺ with Mo⁶⁺ in the scheelite oxides Bi_1-x/3V_1-xMo_xO₄, some of the oxygen combined with Bi cation are released and the tetrahedron Mo(V)O₄ may be distorted to some extent. The formation of the shared structure Mo─O─V makes it possible for lattice oxygen ions to diffuse into the bulk of catalyst. The Mo=O double bond, which plays an important role in selective oxidation, has formed by introducing cation vacancies when χ is 0.45,namely in Bi_0.85V_0.55Mo_0.45O₄ catalyst. The synergistic effect between Mo=O double bond and stronger Bi─O─V bond accounts for the better catalytic performance of this catalyst.

Key words: bismuth vanadomolybdate, propane, selective oxidation, mechanism of catalytic action, IR spectrum