Browsing by Author "Barthomeuf, Denise"

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    Characterization of the Hydroxyls in Offretitc Zeolite
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1978, 74 (07), 1978) Mirodatos, Claude; Abou-Kais, Antoine; Vedrine, Jacques C.; Barthomeuf, Denise
    It is shown that three structural hydroxyl groups are generated in offretite upon cation exchange. The 3660 cm–1 OH groups are either not acidic or only slightly so and are probably located in the inaccessible hexagonal prism (O6H). The 3610 and 3550 cm–1 hydroxyls are acidic. Their strength increases at low cation content. The 3610 cm–1 groups are mainly located in the channel (O5H) while the low frequency groups are suggested to be in the cancrinite cage (O2H or O4H).
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    Inoperative Protonic Sites in Highly Exchanged L-Zeolites
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1977, 73 (10), 1977) Ballivet, Danielle; Barthomeuf, Denise
    It has been shown that highly exchanged L zeolites have hydroxyls vibrating at 3740, 3730, 3680 and 3630 cm–1 and a large number of strongly interacting hydroxyls. The structural 3630 cm–1 hydroxyls, stable under the conditions of catalytic experiments, are strongly acidic toward pyridine. Their inactivity in catalysis for less basic molecules such as hydrocarbons suggests that protons in these highly exchanged samples become inoperative either because they form hydroxyl nests or because they move to inaccessible cavities.