Browsing by Author "Derrah, R. I."

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    Sorption of Ethylene, Propylene and Cyclopropane in 5A Zeolite: Analysis of Equilibrium Isotherms
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1972, 68 (10), 1972) Derrah, R. I.; Loughlin, K. F.; Ruthven, D. M.
    Experimental equilibrium isotherms are presented for the sorption of light unsaturated hydrocarbons in type A zeolite. The data are analyzed according to the extended potential theory of Dubinin and also by the use of a simple statistical model isotherm. Henry constants and heats and entropies of sorption are calculated and compared with the values previously obtained for the light paraffins. It is shown that the relatively stronger adsorption of the olefins, in comparison with the corresponding paraffins, is almost entirely attributable to the greater energy of sorption arising from specific electrostatic interactions. Under comparable conditions the entropies of sorption of paraffins and olefins arc very similar.
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    Transition State Theory of Zeolitic Diffusion: Diffusion of CH4 and CF4 in 5A Zeolite
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1972, 68 (12), 1972) Ruthven, D. M.; Derrah, R. I.
    A simple theory of zeolitic diffusion is developed from the principles of transition state theory. General expressions for the diffusivity are derived in terms of the lattice parameter and the partition function for the transition state which, for the type A zeolites, is identified as a molecule in passage through the 8-membercd oxygen window. Theoretical diffusivities calculated for CH4 and CF4 in 5A zeolite agree well with experimental data and it is shown that, in the transition state, the CF4 molecule has a high degree of rotational freedom whereas the rotation of the CH4 molecule is severely restricted. This difference is attributed to the difference in the moments of inertia.