Molybdenum carbide belongs to the transition metal carbide, which is a family of interstitial compounds with metallic properties formed by carbon entering the crystal lattice of the transition metal.
Molybdenum carbide is a gray hexagonal crystal. It has the characteristics of high melting point and hardness, good thermal and mechanical stability and good corrosion resistance. The melting point is 2692°C. Insoluble in water and lye, slightly soluble in nitric acid, sulfuric acid and hydrofluoric acid.
Molybdenum carbide has a high initial catalytic activity in the benzene hydrogenation reaction. Although the catalyst gradually deactivates as the reaction progresses, its steady-state conversion frequency (TOF) is still comparable to that of noble metals Pt or Ru.
Polymorphism in stoichiometric and
non-stoichiometric MO carbides is
described. Up to 1190 ℃ the stable
phase is orthohrombic α Mo-C, between
1190 ℃ and 1655℃ hexagonal βMo2C
is stable. Above 1655 ℃ a non-stoichiometric MO-C phase exists, hexagonal up
to 1960 ℃ and face centred cubic
between 1960 and the melting point,
2580 ℃ . Heating MO and C in a solar
furnace at 1600 ℃ resulted in synthesis
of non-stoichiometic hexagonal MoC（1-x）in 30 minutes. It is suggested that there
is a photochemical reaction.
[1] Photochemical synthesis of molybdenum carbide for molybdenum and carbon powders[J]. Metal Powder Report, 2000, 55 11: Page 46. DOI:10.1016/0026-0657(00)92257-4.
