Browsing by Author "Dickson, Bruce L."

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    Mossbauer Studies of Ferrous-A Zeolite: Part 1.—Adsorption/Desorption of Water
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1974, 70 (11), 1974) Dickson, Bruce L.; Rees, Lovat V. C.
    Ferrous ions have been ion exchanged into A zeolite. The ferrous ions in the dehydrated form of the zeolite give an isomer shift of 1.08 mm s~l and a temperature independent quadrupole splitting of 0.46 mm s~l. The ferrous ions are shown to be located in the sodalite window site with 3-fold coordination to lattice oxygens. In the partially hydrated zeolite two species of iron are seen in the Mossbauer spectra. Temperature studies show these two sites to be related by an equilibrium process, which is interpreted as the dissociation of a water molecule attached to a ferrous ion to give a hydroxyl group.
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    Mossbauer Studies of Ferrous-A Zeolite: Part 2.—The Mobile Adsorption of Ethylene
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1974, 70 (11), 1974) Dickson, Bruce L.; Rees, Lovat V. C.
    The titration of ethlene into dehydrated ferrous-A has been followed by 57Fe Mössbauer spectroscopy. The adsorption of ethylene increases the isomer shift and the quadrupole splitting of the single doublet of the outgassed sorbent. A 50% decrease in the Mössbauer absorption area is found when half the Fe2+ cations are covered with ethylene. Cooling the ferrous-A zeolite + adsorbed ethylene system to below 200 K caused the spectrum to split into two doublets. These changes show that the ethylene molecules are moving freely in the zeolite at room temperature but at temperatures below 200 K the molecules have residence times on the ferrous ion adsorption sites of the same order of magnitude as the half life of the Mössbauer event. Theoretical spectra have been derived to describe these experimental spectra based on such a hopping mechanism.
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    Mossbauer Studies of Ferrous-A Zeolite: Part 3.—The Adsorption of Ethanol
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1974, 70 (11), 1974) Dickson, Bruce L.; Rees, Lovat V. C.
    Mossbauer spectra have been taken after successive additions of small doses of ethanol have been made in dehydrated ferrous-A. These spectra show that two molecules of adsorbate coordinate to each ferrous ion. When the zeolite is saturated with ethanol, ca. 20 % of the ferrous ions remain uncomplexed. The restrictions of space in the cages of this zeolite prevent the optimum packing of the adsorbate molecules. The complexes formed with the ferrous ions by water, methanol and ethanol are compared and their differences interpreted.