Chemical Engineering / Kimya Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/14
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Article Citation - WoS: 2Catalytic Activity of Heteropolytungstic Acid Encapsulated Into Mesoporous Material Structure(Walter de Gruyter GmbH, 2007) Gündüz, Gönül; Yılmaz, Selahattin; Dimitrova, Rayna P.; Yılmaz, Selahattin; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyThe paper presents a spectroscopic and catalytic study of encapsulated Keggin type heteropoly acid (12-tungstophosphoric acid, HPW) in the mesopores of MCM-41 molecular sieves. Nitrogen physisorption, FTIR, SEM, XRD and catalytic methods have been used to characterize and compare the properties of the samples. Methanol conversion, alpha-pinene isomerization and ethyl acetate oxidation have been applied as model reactions for the evaluation of acid site activity. The combined physicochemical and catalytic investigations clearly show that the introduction of 12-tungstophosphoric acid into MCM-41 causes significant changes in the properties of the sample.Article Citation - WoS: 39Citation - Scopus: 46Alpha-Pinene Isomerization on Acid-Treated Clays(Elsevier Ltd., 2002) Beşün, Nurgün; Özkan, Seher Fehime; Gündüz, Gönül; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyLiquid phase isomerization of α-pinene was studied over a number of differently pre-treated montmorillonite clays. The effects of the acid pre-treatment parameters (acid-to-clay ratio (A/C), water-to-acid ratio (W/A), temperature and pre-treatment time) on the product distribution were investigated. It was observed that the pre-treatment with acid improved the catalytic activity of that catalyst which was activated at 200 °C for 4 h at A/C ratios between 0.2 and 0.4. Alpha-pinene consumption was very small over the catalysts prepared with an A/C ratio of 0.8. Characterization studies that were done by nitrogen and water vapor adsorption experiments and by IR measurements showed that catalysts with high differential pore volumes for pores around 2 nm and homogenous mesopore distributions and with low dealumination degrees were good catalysts for the production of camphene. Catalysts having heterogeneous mesoporosity were found to be the preferable ones for limonene production.