STRUCTURAL EFFECTS IN OXIDATIVE DEHYDROGENATION OF HYDROCARBONS OVER A VANADIA-MOLYBDENA-NIOBIA CATALYST

The oxidative dehydrogenation of ethane, propane and n-butane over a v anadia-molybdena-niobia catalyst has been compared with propane substi tuted in the 2 position with a methyl (isobutane) or a benzyl (isoprop ylbenzene) group. In the normal paraffins, selectivity to the olefin w as found to decrease as the chain length increased. Substitution at th e propane 2 position increased selectivity, particularly in the case o f isopropylbenzene. The results are explained partially in terms of ov er oxidation of the product olefin and partially in terms of structura l effects in the parent hydrocarbon influencing the olefin-producing o xidative dehydrogenation reaction. (C) 1998 SCI.