Collect. Czech. Chem. Commun. 1998, 63, 1915-1926

Competitive Catalytic Hydrogenation in Unsaturated Hydrocarbon Systems With Sterically Hindered Double Bonds

Petr Kačera, Leiv Laateb and Libor Červenýa

a Department of Organic Technology, Prague Institute of Chemical Technology, 166 28 Prague 6, Czech Republic
b Department of Industrial Chemistry, Norwegian University of Science and Technology, Trondheim N-7034, Norway


A competitive hydrogenation of unsaturated hydrocarbons (a-methylstyrene, cyclohexene, 1-methylcyclohex-1-ene, 1-tert-butylcyclohex-1-ene and 3-tert-butylcyclohex-1-ene) in binary and ternary systems with palladium-, platinum- and rhodium-supported catalysts in a semibatch isothermal reactor at 20 °C under atmospheric pressure was studied. It was found that considerable variance in selectivity values of competitive hydrogenation in a series of substrates with increasing substituent bulkiness is caused by differences in adsorption and in reactivity of adsorbed molecules. In the case of ternary systems, a change in selectivity of competitive hydrogenation of two substrates was observed, due to the presence of a third substance, caused by a competitive adsorption of all three substrates and their interaction on a catalytic surface.

Keywords: Competitive hydrogenation; Palladium; Platinum; Rhodium; Adsorptivity; Heterogeneous catalysis; Unsaturated hydrocarbons.