Mo and MoO3 powders: Structure and resistance to CO.

A molybdenum trioxide micropowder (МоО 3 MP) with an average crystallite size of 821 nm was obtained by the thermal treatment of an initial molybdenum nanopowder (Mo NP) with an average crystallite size of 150 nm. The structure of these powders and their resistance to carbon monoxide action at an increased temperature were studied by X-ray diffraction, X-ray fluorescence, and IR spectroscopy. The Mo NP sample contained 88.25% molybdenum and 11.51% oxygen and, as a whole, showed resistance to CO action at 200 °C. However, its crystallites were observed to grow under the specified conditions, and their final average size exceeded 1000 nm. The obtained MoO 3 MP sample contained 67.50% molybdenum and 32.34% oxygen. Мо 2 С, Мо and Мо 4 О 11 were identified in addition to МоО 3 after a treatment with CO at 200 °C. It is concluded that the МоО 3 MP is unstable under the action of carbon monoxide at the indicated temperature. It is suggested that a dissociative sorption of CO involving МоО 3 occurs. [ABSTRACT FROM AUTHOR]