Abstract: The effect of rare earth cation Ce³⁺ on the catalytic behaviour of multicomponent oxides consisted of PMo₁₂Bi₃Fe_8-xCe_x K_0.1O_y(x=0-8) for ammoxidation of propylenc has been investigated in a fluidized bed reactor. The structure of the catalyst was characterized by XRD, IR, SEM and TG techniques. It is found that the highest yield of aerylonitrile could be obtained at x=2—3, with Fe₂(MoO₄)₃, Ce₂(MoO₄)₃ and α-Bi₂O_ε·3MoO₃ being coexisted in the catalyst. The dissolution and coagulation of the above three phases in the solid solution and the formation of a Pseudohomogeneous phase make the active component uniformly distributed at the surface and boundaries of the phases. The activity of the catalysts is considered mainly caused by synergistic effect of the individual active components. Cerium inhibits the sublimation of MoO₃, stabilizing the structure, of active phases.

Key words: Propylene, Ammoxidation, Heterogeneous catalysis, Acrylonitrile, Rare earth catalyst