Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Citation - WoS: 23Citation - Scopus: 24Epoxidation of Propene by High-Throughput Screening Method Over Combinatorially Prepared Cu Catalysts Supported on High and Low Surface Area Silica(Springer Verlag, 2012) Düzenli, Derya; Şeker, Erol; Senkan, Selim; Önal, IşıkGas phase epoxidation of propene using molecular oxygen was studied by use of a high-throughput testing technique. A large number of catalysts including promoted and un-promoted Cu were synthesized in a much faster combinatorial fashion using a sol-gel method. Metal catalysts supported on high and low surface area silica were tested and ranked in a high-throughput activity and selectivity testing apparatus at different experimental conditions such as reaction temperature and reactant gas ratio. The amount of Cu loading and the addition of alkali promoters such as K and Li resulted in different tendencies in consumption rate for both silica materials. The maximum PO production rate was obtained as 25.82 μmol/g/ cat./min (2.90 % conv. and 20.49 % selectivity) for 3 % Cu-2.25 % K catalyst supported on high surface area silica. There was no noticeable difference in structural and chemical properties of catalysts after modification with K when examined by XRD and TEM; however, the overall activation energy of un-modified catalysts (92 kJ/mol) decreased to 71 kJ/mol for K-modified catalyst. There was negligible difference between the activation energies calculated for PO production (75 vs. 77 kJ/mol).Article Citation - WoS: 12Citation - Scopus: 13Single Step Sol-Gel Made Silver Chloride on Titania Xerogels To Inhibit E. Coli Bacteria Growth: Effect of Preparation and Chloride Ion on Bactericidal Activity(Springer Verlag, 2011) Tuncer, Mert; Şeker, ErolWe report the antibacterial efficacies of silver and/or silver chloride containing titania xerogels synthesized with modified single step sol-gel methods against Escherichia coli bacteria. As the silver loading in TiO 2 increases, the amount of the xerogel required to inhibit the growth of the bacteria decreases and also we found that pure TiO2 was not bactericidal. Among modified single step sol-gel methods used in this study, the additional HCl treatment sol-gel route III was very effective to obtain only AgCl crystallites in TiO2. Based on viable cell count method, 0.125 g/L of 29%Ag/TiO2 (made with HNO3 sol-gel route I) was enough to inhibit the growth of E. coli whereas 0.6 g/L of 29%Ag/TiO2 (made with the additional HCl treatment sol-gel route III) was required. However, antibacterial activity of 29%Ag/TiO2 (made with HNO 3 sol-gel route I) after 6 usages was the same as 29%Ag/TiO 2 (made with the additional HCl treatment sol-gel route III).Article Citation - WoS: 36Citation - Scopus: 39Transesterification of Sunflower Oil on Single Step Sol-Gel Made Al2o3 Supported Cao Catalysts: Effect of Basic Strength and Basicity on Turnover Frequency(Elsevier Ltd., 2012) Umdu, Emin Selahattin; Şeker, ErolThe activities of single step sol-gel made calcium oxide on alumina catalysts were studied as a function of CaO loading, methanol/oil molar ratio and the amount of the catalyst in the transesterification of sunflower oil at 50°C. Also, the turnover frequency (TOF) of the catalysts was calculated to better understand the relationship between the basicity/basic strength and the catalytic activity. From volcano curve (TOF vs. basic strength), it was found that under 50°C and methanol/oil molar ratio of 9, 60% CaO/Al 2O 3 had the highest turnover frequency, 0.028s -1, whereas 85% CaO/Al 2O 3 showed the highest biodiesel yield, ∼96.6%, but TOF obtained on it was 0.012s -1. It seemed that 60% CaO catalyst had the proper basic strength to obtain the highest TOF. © 2011 Elsevier Ltd.Conference Object Citation - WoS: 22Citation - Scopus: 22Propylene Epoxidation: High-Throughput Screening of Supported Metal Catalysts Combinatorially Prepared by Rapid Sol-Gel Method(Springer Verlag, 2010) Önal, Işık; Düzenli, Derya; Seubsai, Anusorn; Kahn, Michael; Şeker, Erol; Senkan, Selim M.The gas phase oxidation of propylene using molecular oxygen was studied on a variety of supported metal catalysts. The most promising PO activity was obtained for Cu supported on high surface area SiO 2 and the multimetallic systems exhibit synergistic effects that increased the desired PO yield by several folds for Ag promoted with Cu on SiO 2 after screening a large number of catalysts by a high throughput testing technique. © 2009 Springer Science+Business Media, LLC.Article Citation - WoS: 273Citation - Scopus: 327Transesterification of Nannochloropsis Oculata Microalga's Lipid To Biodiesel on Al2o3 Supported Cao and Mgo Catalysts(Elsevier Ltd., 2009) Umdu, Emin Selahattin; Tuncer, Mert; Şeker, ErolIn this study, we present the activities of Al2O3 supported CaO and MgO catalysts in the transesterification of lipid of yellow green microalgae, Nannochloropsis oculata, as a function of methanol amount and the CaO and MgO loadings at 50 °C. We found that pure CaO and MgO were not active and CaO/Al2O3 catalyst among all the mixed oxide catalysts showed the highest activity. Not only the basic site density but also the basic strength is important to achieve the high biodiesel yield. Biodiesel yield over 80 wt.% CaO/Al2O3 catalyst increased to 97.5% from 23% when methanol/lipid molar ratio was 30.