Browsing by Subject "Alkenes"

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    Aromatization of 1-hexene and 1-octene by gallium/H-ZSM-5 catalysts.
    (Elsevier, 1996) Nash, R; Dry, M; O'Connor, C
    Gallium/H-ZSM-5 zeolite catalysts were tested for the aromatization of long-chain alkenes, namely 1-hexene and 1-octene. Aromatic yields of ca. 70% were obtained, which are similar to those reported in the literature for propene aromatization. The catalysts tested were prepared by impregnation by incipient wetness of gallium nitrate, ion-exchange with gallium nitrate and by physical mixing with β-gallium oxide crystallites. Hydrogen pretreatment improved the selectivity to aromatic products of gallium/H-ZSM-5 catalysts prepared by physical mixing with β-gallium oxide, but decreased aromatic selectivity for catalysts prepared by ion-exchange and impregnation.
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    Effect of catalyst modification on the conversion of methanol to light olefins over SAPO-34.
    (Elsevier, 1996) van Niekerk, M; Fletcher, J; O'Connor, C
    The catalytic activity and selectivity of as-prepared and modified samples of SAPO-34 and Me-APSO-34 (Me = Co, Ni) for the conversion of methanol to olefins has been investigated. The catalytic performance for the conversion of methanol to light olefins of all the catalyst samples prepared was found to be closely related to the number of strong acid sites present. Mild steaming, encountered during deep-bed calcination, increased the lifetime of SAPO-34 due to the formation of stronger acid sites probably on the external surface of the crystallites. Selectivities to light olefins were typical of those previously reported and was essentially constant for all the catalysts investigated. The absence of C5+ olefins is ascribed to the ‘cage effect’. Dilution of the methanol with water as opposed to nitrogen increased the catalyst utilization value threefold and reduced the rate of coke formation during reaction. Treatments such as steaming, silanization and poisoning of strong sites by ammonia all reduced the number of strong acid sites and, thus, reduced catalytic performance.