Hydrogenolysis of saturated hydrocarbons on a nickel catalyst I. Kinetics of hydrogenolysis of ethylcyclohexane and reactivity of alkylcyclohexanes

Abstract The hydrogenolysis of a series of alkylcyclohexanes on a nickel catalyst containing 8% by weight of aluminum oxide was investigated in a flow apparatus at 220 °C and under atmospheric pressure of hydrogen. In this reaction the alkyl groups were successively degraded with the formation of methane and saturated alicyclic hydrocarbons with a lesser number of carbon atoms in the side chain. The cyclohexane ring was not cleaved under the given conditions. For ethylcyclohexane a complete kinetic analysis of the reaction was made. The experimental data satisfied a Langmuir-Hinshelwood type of relation in which the rate-determining step is a surface reaction of adsorbed molecules of the hydrocarbon and hydrogen. The reactivities of homologous alkylcyclohexanes were compared on the basis of initial reaction rates measured under the same conditions. These data serve as a basis for considerations on the effect of the structure on reactivity and on the reaction mechanism.