Kinetics of formation of molybdenum carbide (Mo2C) by reaction between carbon monoxide and molybdenite or molybdenum

Investigations have been conducted on the reactions between molybdenite (technical grade MoS 2 ) and molybdenum metal powders with carbon monoxide in the temperature range 1123 to 1298K. The rates of both MoS 2 + CO and Mo+CO reactions have been found to increase significantly with temperature. XRD examination of the reaction products reveal the formation of Mo 2 C directly by the reduction-carburization of MoS 2 . The said carbide is also observed to be the dominant product of molycarburization (Mo + CO) reaction. The MoS 2 conversion has been found to be a slow process, whose results fit into a linear rate law with a high activation energy value (230 kJ mol -1 ). In contrast, the carburization of Mo powder has been observed to be a fast process, initially rapid upto about 30% conversion and subsequently progress in accordance with parabolic kinetics (low activation energy values of 76 and 33.5 kJ mol -1 , respectively for initial and parabolic stages). Since no elemental Mo has been detected in the products of the MoS 2 +CO reaction, it is not possible to separate it from the subsequent in-situ molycarburization (Mo+CO) reaction. An indepth analyses of the findings indicate that the linear kinetics and the high activation energy value (230 kJ mol -1 ) determined for the overall reduction-carburization of MoS 2 may pertain to the pre-requisite reaction (namely, MoS 2 +2CO=Mo+2COS) itself.