Abstract:

Molybdenum carbide, prepared by temperature-programmed reaction(TPR), using CH₄/H₂ gas mixture to carburize molybdenum trioxide, was characterized by TG-DTA, XRD, BET, SEM and XPS techniques. The results indicate that molybdenum carbide can be prepared by the pathway of MoO₃→MoO₂→MoO_xC_y→Mo₂C in CH₄/H₂ mixture to carburize molybdenum trioxide by TPR, and the proper carburizing temperature is about 675℃. The phase of molybdenum carbide is β--Mo ₂C, the particles with the dimension of about 3.9μm are orderly and uniform. It is found that the XPS spectra of Mo3d included two peaks, one is due to Mo--C identified to Mo ²⁺ which is the dominant species and the other is due to Mo--O identified to Mo ^δ+ . The four peaks of C1s spectra are corresponding to C--Mo, C--C, C--H and C--O species respectively, and the C-- Mo is the dominant species. The particle size of Mo2C is aggrandized, the BET area decreased, and free carbon of the surface increased with the increase of carburizing temperature, furthermore the Mo atoms on the surface are mainly in the form of Mo--C identified to Mo ²⁺ , and only a small part is passivated by oxygen, because of the cover and
protection of free carbon.

Key words: molybdenum trioxide, molybdenum carbide, preparation, characterization