Study on the Reduction Behaviour of Nickel Doped Molybdenum Trioxide by Using Carbon Monoxide as Reductant

The reduction behaviour of molybdenum trioxide, (MoO3) and nickel (Ni) doped MoO3 using carbon monoxide (CO) as reductant was investigated by temperature programmed reduction (TPR) and characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) and transmission electron microscope analysis (TEM). The reduction characteristics of MoO3 to MoO2 were examined up to temperature 700 super(o)C and continued with isothermal reduction by 20 vol. % CO in nitrogen. The studies show that, TPR spectra of doped MoO3 slightly shift to a lower temperature as compared to the undoped MoO3 which begins at 630 super(o)C. The interaction between nickel and molybdenum ions leads to this slightly decrease of the reduction temperature of Ni doped MoO3. Analysis using XRD confirmed, the addition of Ni enhances the reducibility of MoO3. By addition of Ni, complete reduction to MoO2 were take place at only 30 minutes starting of the isothermal reduction at 700 degree C. Whereas, for undoped MoO3 it takes about 60 minutes to completely reduce to MoO2. However, excess of CO brings to the formation of molybdenum carbide (Mo2C). Based on the results, it is confirmed addition of Ni to MoO3 has a remarkable influence by reducing temperature in the reduction process. The ability to enhance the reducibility involved in MoO3 may be associated to the presence of nickel molybdate, NiMoO4 compound.