Reduction characteristics of molybdenum trioxide with aluminum and silicon.

Thermodynamics for reduction of molybdenum oxides by aluminum and silicon were calculated, and the results show that reduction reaction is feasible at a certain temperature region. Compared to the presence of CaO or CaCO₃, reduction products of molybdenum trioxide with aluminum and silicon at various temperatures were detected by X-ray diffraction (XRD). Results show that molybdenum trioxide is reduced by aluminum or silicon step by step, and the intermediate product is MoO₂. At 1000 °C, molybdenum trioxide could be reduced to metal Mo by aluminum, and in the presence of CaO, metal Mo as the reduction product appears even at 800 °C. In contrast, silicon could barely reduce molybdenum trioxide to metal Mo even at 1200 °C. In the presence of CaO or CaCO₃, reducibility of silicon increases significantly, and the reduction products are metal Mo and MoSi₂. Altogether, CaO or CaCO₃ performs two major roles in reduction process: restraining sublimation of MoO₃ and decreasing the temperature of reducing MoO₃ to metal Mo. [ABSTRACT FROM AUTHOR]