IN-SITU CARBURIZATION OF METALLIC MOLYBDENUM DURING CATALYTIC REACTIONS OF CARBON-CONTAINING GASES

Supported molybdenum clusters were prepared by sublimation of Mo(CO)6 onto dehydroxylated alumina followed by decomposition in flowing dihydrogen at 970 K. These alumina-supported molybdenum clusters were found by XAFS to transform into Mo2C if heated in a 20% methane/H-2 mixture at 950 K. For the hydrogenolysis of n-butane at 510 K and CO-H-2 reactions at 570 K, both at atmospheric pressure, molybdenum and carburized molybdenum showed similar, but different for each reaction, turnover rates. The product distribution was the same for each reaction on Mo and Mo2C. In both reactions, in situ XAFS data for fresh and used catalysts indicated that Mo clusters progressively transformed into Mo2C under the reaction conditions