A novel synthesis process for MoO2 and Mo2C particles

This study presents a novel process for the synthesis of MoO2 and Mo2C particles. It consisted of waste polyethylene (PE) pyrolysis and MoO3 reaction with pyrolytic gas in a furnace with two-independently controlled zones. The gaseous species such as H2 and CH4 were in situ generated from the waste during heating to the temperatures ranging from 670 to 800 K. The resultant pyrolytic gas was carried to the MoO3 powder bed by Ar flow to obtain MoO2 at 900 K. Mo2C was synthesized in the temperature range 1000-1300 K by the reaction of pre-reduced MoO2 with the pyrolytic gas. Mo4O11, MoO2, and Mo2C phases sequentially formed during the reduction and carburization of the MoO3 powder. Mo4O11 phase played an intermediate role in the reduction, as predicted by the thermodynamics. MoO2 and Mo2C phases were obtained at PE/oxide reactant ratios higher than those predicted. The discrepancy was discussed in terms of essential characteristics of the thermodynamics and the experiments. Mo2C powders consisted of fine platelet-shaped crystals similar to those of MoO2. Mo2C crystallite size decreased, whereas microstrain increased as the carburization temperature decreased. This study demonstrates that waste PE can be recycled as alternative H2 and C resources in reduction/carburization processes.