The catalytic Hydrogenation of Benzene and toluene over evaporated films of Nickel and Tungsten

Abstract

In the vapour-phase hydrogenation of benzene and toluene over evaporated films of nickel and tungsten there is some poisoning of the catalyst surface by adsorbed hydrocarbon residues, resulting in falling rates of hydrogenation. Activation energies and frequency factors are obtained from initial rates. On poisoned nickel, rates pass through a maximum at about 90 °C. The rate and extent of poisoning increase with temperature. Some cyclohexene is sometimes formed during the hydrogenation of benzene over nickel. The hydrogenation of cyclohexene over nickel is extremely rapid but strongly inhibited by benzene. On a benzene poisoned nickel surface cyclohexene disproportionates to benzene and cyclohexane, and this reaction also occurs to a small extent during hydrogenation of cyclohexene.