Preparation and benzene hydrogenation activity of supported molybdenum carbide catalysts

Alumina-supported molybdenum carbide catalysts have been prepared from Mo0 3/A l2O 3 by (i) reduction with H2 followed by carburization, (ii) direct carburization with CH 4/H 2, and (iii) nitriding with NH 3 followed by carburization. The temperature required for the complete reduction Of MoO3/A1 2O 3 depended strongly on the reductant employed. Temperature-programmed reduction coupled with on-line mass spectrometry and X-ray diffraction revealed reactions involved in the reduction and carburization of Mo0 3. The supported molybdenum carbide catalysts exhibited high catalytic activity in benzene hydrogenation comparable to those of Pt or Ru. Complete reduction of molybdenum was essential for the high activity. Metallic molybdenum was much less active and less stable than its carbides, probably due to too strong adsorption of benzene.