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

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.

Thermodynomic data from Gas-Liqud partition Chromatography

Partition coefficients obtained from gas-liquid partition chromatography have been compared with those obtained in a static system to show that the former are true equilibrium values. The heats and entropies of solution have been obtained from the temperature dependence of the partition coefficients.

Study of adsorption on metals by the contact potential technique

The change in contact potential between metals due to physical adsorption of water vapour, isopropanol, and ethyl acetate has been studied. The plot of contact potential against relative vapour pressure showed a hysteresis loop, the behaviour varying for different methods of surface preparation. An initial irreversible potential change was always found, due to chemisorption. By studying the dependence of the contact potential on the temperature of one of the metal surfaces it has been possible to determine the change in work function of a gold surface due to physical adsorption.