Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection

Permanent URI for this collectionhttps://hdl.handle.net/11147/7148

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Institution Author: search.filters.institutionAuthor.Çakıcıoğlu Özkan, Seher FehimePublisher: search.filters.publisher.Taylor and Francis Ltd.

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  • Article
    Citation - WoS: 23
    Citation - Scopus: 27
    Isomerization of Alpha-Pinene Over Acid Treated Natural Zeolite
    (Taylor and Francis Ltd., 2005) Ünveren, Ercan; Özkan, Seher Fehime; Çakıcıoğlu Özkan, Fehime; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    In this study, isomerization of α-pinene was studied over several acid-treated natural zeolite catalysts rich in clinoptilolite. Zeolite samples were contacted with HCl at different concentrations at 30°'C or at 60°C for 3 and 24 hours and tested in isomerization reaction of alpha-pinene. The catalysts prepared were characterized by XRD, nitrogen adsorption, and acidity studies. Acidity strength and the distribution of Lewis and Brönsted acid sites of the catalysts were determined, and their catalytic activities in α-pinene isomerization and selectivities to main reaction products, camphene and limonene, were investigated. Acid treatment improved the selectivity of catalyst samples to camphene, decreasing the selectivity to limonene, probably forcing limonene to secondary reactions at high conversions. The kinetics of α-pinene consumption was described by first-order kinetics. Two kinetic models were tested for the reaction mechanism and one model was found to give a good correlation between the theoretical and experimental data. In the models, the key intermediate was the pinylcarbonium ion, which was formed irreversibly from α-pinene. Number and distribution of Lewis and Brönsted acid sites affect the formation of bicyclic and monocyclic products.
  • Article
    Citation - WoS: 19
    Flexible Poly(vinyl Chloride)-Zeolite Composites for Dye Adsorption From Aqueous Solutions
    (Taylor and Francis Ltd., 1996) Balköse, Devrim; Ulutan, Sevgi; Balköse, Devrim; Ülkü, Semra; Özkan, Seher Fehime; Ülkü, Semra; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    Flexible poly(vinyl chloride) (PVC) composites having natural zeolite clinoptillolite were prepared by plastisol-plastigel technology. Adsoption of methylene blue on each raw material and on composites was studied both from an equilibrium and a rate approach. It was observed that the adsorption capacity of zeolite decreased when it was embedded in composites. The equilibrium uptake of methylene blue increased with an increasing zeolite fraction in composites. Methylene blue was adsorbed from a 0.02 g·cm-3 aqueous solution slowly, but was nearly adsorbed completely with a composite having a 0.3 volume fraction of zeolite. The effective diffusion coefficient of methylene blue in composites was of the order of 10-13 m2·s-1 and decreased with increasing filler fraction.