CATALYTIC ACTIVITY OF BULK TUNGSTEN CARBIDES FOR ALKANE REFORMING .1. CHARACTERIZATION AND CATALYTIC ACTIVITY FOR REFORMING OF HEXANE ISOMERS IN THE ABSENCE OF OXYGEN

Hydrogenolysis of 2-methylpentane, n-hexane and methylcyclopentane has been studied on tungsten carbide WC between 150 and 350 degrees C. The experiments have been performed in a classical flow reactor under a great excess of hydrogen (p(H2)/P-HC = 150) flowing at atmospheric pressure. The catalyst samples have been prepared in situ in the flow reactor system by reduction and carburization of WO3 powder by a mixture of CH4(20%)/H-2(80%) at T = 850 degrees C for 4 h. The BET surface area is around 12 m(2)/g. The reactions of these three hydrocarbons give mainly cracking, leading to molecules with less and less carbon atoms as temperature increases. At T = 350 degrees C, only methane is observed. Isomerization products, due to skeletal rearrangement, are mainly observed at low temperature, but they represent only a few percent of the total reaction process. The results show that tungsten carbide exhibits catalytic properties close to those of metals like ruthenium, iridium, and nickel in the field of cracking reactions. (C) 1995 Academic Press, Inc.