Browsing by Author "Harrison, Brian H."

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    Molecular Sieve Properties of the Carbonaceous Products prepared by Chemical Dehydrohalogenation of Polyvinylidene Chloride
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1972, 68 (9), 1972) Barton, Stuart S.; Beswick, Paul G.; Harrison, Brian H.
    The molecular sieve properties of the carbonaceous products prepared by chemical dehydrohalogenation of polyvinylidene chloride (hereafter referred to as “carbons”) have been investigated by a heat of immersion study, using the immersional liquid as a molecular probe. Dehydrohalogenation reaction time has been found to play an important role in the carbons' molecular sieve properties. Characterization of the carbons by low temperature nitrogen adsorption was found in some cases to be limited by activated diffusion so the study was supplemented by measuring the adsorption of carbon dioxide at –78 and 0°C. A marked transition was observed in the molecular sieve properties as reaction time during dehydrohalogenation was varied. This was clearly illustrated by a sudden drop in surface area, as measured by low temperature nitrogen adsorption, when entrance into the pores by nitrogen is prevented by an activated diffusion mechanism. The carbons prepared using a small reaction time are shown to have 4–5 Å molecular sieve properties which can separate straight and branched chain hydrocarbons. Carbons prepared by longer reaction periods were found to have 3 Å molecular sieve properties. These carbons have also been contrasted to the properties of carbons prepared by pyrolysing polyvinylidene chloride.
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    Surface Studies on Graphite: Desorption of Surface Oxide
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1973, 69 (6), 1973) Barton, Stuart S.; Harrison, Brian H.
    The kinetics of desorption of surface oxide as CO and CO2 from graphite have been followed, using a mass spectrometer system, allowing their activation energies of desorption to be measured as a function of the amount desorbed. After the initial degassing of the graphite, surface oxide was reformed by chemisorption at 298 K and 573 K, and oxygen pressures of 760 Torrf and 0.2 Torr respectively. Similar analysis of the desorption kinetics of these oxides, formed under controlled conditions, has allowed a comparison of their desorption energetics to be made.