Study on Reduction of MoO ₂ Powders with CO to Produce Mo ₂ C

Molybdenum hemicarbide (Mo ₂ C), which is widely applied in steel and metal ceramics as well as catalysts, was successfully synthesized by using a simple method of reducing MoO ₂ powders by CO. It was found that the final reduction product was all Mo ₂ C under both isothermal and nonisothermal conditions. However, the reduction mechanisms were significantly different at lower and higher temperatures: at lower temperatures (1070 to 1342 K), reduction of MoO ₂ to Mo ₂ C followed a one‐step reaction (simultaneous reduction and carburization), while at higher temperatures (1423 to 1485 K), MoO ₂ was first reduced to metallic Mo, and then Mo was carburized to Mo ₂ C. Mo ₂ C particles obtained at higher temperatures contained micrometer‐sized surface features which formed during the MoO ₂ to Mo reduction step.