Key Role of Precursor Nature in Phase Composition of Supported Molybdenum Carbides and Nitrides.

In this work, we studied the effect of molybdenum precursors and the synthesis conditions on the final phase composition of bulk and supported molybdenum carbides and nitrides. Ammonium heptamolybdate, its mixture with hexamethylenetetramine, and their complex were used as the precursors at different temperatures. It was investigated that the synthesis of the target molybdenum nitrides strongly depended on the structure of the precursor and temperature conditions, while the synthesis of carbide samples always led to the target phase composition. Unlike the carbide samples, where the α-Mo2C phase was predominant, the mixture of β-Mo2N, MoO2 with a small amount of metal molybdenum was generally formed during the nitridation. All supported samples showed a very good dispersion of the carbide or nitride phases. [ABSTRACT FROM AUTHOR]