Competitive catalytic hydrogenation in systems of unsaturated hydrocarbonsand nitrocompounds

Competitive catalytic hydrogenation was studied in binary systems of aromat ic and aliphatic nitrocompounds (nitrobenzene, 2-nitrotoluene, 3-nitrotolue ne, 4-nitrotoluene, 1-nitropropane) and in systems of nitrocompound-unsatur ated hydrocarbon (cyclohexene, 1-methylcyclohexene and 1-tert-butylcyclohex ene) on palladium, platinum and rhodium supported catalysts in liquid phase . Acquired kinetic parameters enabled discussion of structural effects in t he course of heterogeneous catalytic hydrogenation. In the case of nitrocom pounds, potential differences in values of selectivities of competitive hyd rogenations were possible to unambiguously attribute to variance in adsorpt ivities of these substances. In the case of competitive hydrogenations in s ystems of unsaturated hydrocarbon-aromatic nitrocompound, depending on the amount of aromatic amine produced, selectivity increase was observed in fav or of aromatic nitrocompound, which led to an entire suppression of unsatur ated hydrocarbon hydrogenation. Ultimate counter-behavior was observed in t he systems of unsaturated hydrocarbon-aliphatic nitrocompound. (C) 2000 Els evier Science B.V. All rights reserved.