Browsing by Author "Trimm, David L."

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    Adsorption of Gases on Polycrystalline Nickel Films Studied by X-Ray and Ultra-violet Photoelectron Spectroscopy
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1974, 70 (09), 1974) Page, Peter J.; Trimm, David L.; Williams, Peter M.
    The adsorption of a series of gases onto clean evaporated films of polycrystalline nickel has been studied using ultraviolet and X-ray photoelcctron (u.p.e. and X.p.e. respectively) spectroscopy. Observation of the intensity of photoemission from states close to the Fermi level enables conclusions to be drawn regarding the nature of the adsorbate-metal bond. Different mechanisms are shown to be involved between the two series CO—, C2H4—, O2— and H2S—Ni, and H2O—, CO2—Ni. It is further demonstrated that u.p.e. may be used to follow a surface reaction; "results show the progressive displacement by O2 of CO adsorbed on clean Ni. Interpretation of the ultra-violet spectra of adsorbed species is discussed in terms of a possible correlation with energy states of the free molecules.
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    Reorganisation of Nickel under Steam Reforming Conditions
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1977, 73 (09), 1977) Moayeri, Massoud; Trimm, David L.
    The reorganisation of nickel films supported on silica has been studied under conditions pertinent to the steam reforming of propylene. Examination of reorganisation under steam reforming conditions, and in the presence of individual reactants and products, shows that hydrogen has a large effect on metal restructuring. The kinetics of the process are studied and are shown to be consistent with theoretical predictions based on the concept that the mechanism of nickel reorganisation involves surface self diffusion of the metal. The effect of hydrogen pressure is complex and is tentatively explained in terms of the formation of different nickel hydrides. If carbon is deposited on the metal, reorganisation of the films is found to be slow.