WoS İndeksli Yayınlar Koleksiyonu / WoS Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7150
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Article Citation - WoS: 41Citation - Scopus: 42Fructose Dehydration To 5-Hydroxymethylfurfural Over Sulfated Tio2-Sio2, Ti-Sba Zro2, Sio2, and Activated Carbon Catalysts(American Chemical Society, 2015) Kılınç, Emre; Yılmaz, SelahattinDifferent sulfated catalysts including SO4/TiO2-SiO2, SO4/Ti-SBA-15, SO4/ZrO2, SO4/AC, and SO4/SiO2 were tested in fructose dehydration to 5-hydroxymethylfurfural (HMF). Reactions were carried out in dimethyl sulfoxide (DMSO) at 110 °C. Characterization results indicated that no sulfur leaching was observed from SO4/ZrO2, SO4/TiO2-SiO2, and SO4/Ti-SBA-15 catalysts in the reaction tests. The SO4/TiO2-SiO2 catalyst had a high amount of strong acid sites and the highest amount of Bronsted sites. The highest selectivity to HMF at high conversion, that is, 89% selectivity at 77% fructose conversion was obtained over this catalyst. It preserved its activity after four times reuse.Activated carbonCarbonCatalystsDehydrationArticle Citation - WoS: 167Citation - Scopus: 197Preparation and Characterization of Activated Carbons by One-Step Steam Pyrolysis/Activation From Apricot Stones(Elsevier Ltd., 2006) Şentorun-Shalaby, Çiğdem; Uçak Astarlıoğlu, Mine G.; Artok, Levent; Sarıcı, ÇiğdemThe activated carbons were prepared from Malatya (a city located in the south-east of Turkey) apricot stones by one-step steam pyrolysis/activation process and characterized for their pore structures. Three kinds of apricot stones that differ in their sulfur content, because of the different drying processes, were chosen for this study to investigate the effect of sulfur in the activated carbon production. The effect of process variables, such as activation temperature, soak time, and particle size range was studied on these samples. The activation temperature and time tested were in the ranges of 650-850 °C for 1-4 h. The activated carbons were evaluated for their chemical (elemental composition), surface (BET surface area, mercury porosimetry), and adsorption (iodine number) properties. Carbonization behavior of the apricot stones was investigated by thermogravimetric analysis. Scanning electron microscopy (SEM) was used to follow the changes in the carbon texture upon activation. The experimental results revealed that carbons obtained by the same conditions of activation show differences in their pore structures and adsorption characteristics due to their sulfur contents. The highest BET surface area carbon (1092 m2/g) was obtained from the low sulfur content (0.04%) apricot stone with a particle size range of 1-3.35 mm at the activation conditions of 800 °C for 4 h. The experimental results showed that commercial production of porous activated carbons from Malatya apricot stones is feasible in Turkey.Article Citation - WoS: 21Citation - Scopus: 23Activated Carbon Adsorption of Fuel Oxygenates Mtbe and Etbe From Water(Springer Verlag, 2009) İnal, Fikret; Yetgin, Senem; Aksu, Gülsüm T.; Şimşek, Selvi; Sofuoğlu, Aysun; Sofuoğlu, Sait CemilThe aqueous phase adsorption of fuel oxygenates methyl tertiary butyl ether (MTBE) and ethyl tertiary butyl ether (ETBE) onto commercially available granular activated carbon (GAC; Norit GAC 1240) was investigated in a batch system at 27°C. The oxygenate concentrations were determined by headspace gas chromatography/mass spectrometry analyses. The experimental data were used with four two-parameter isotherm models (Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich) and two kinetic models (pseudo first-order and pseudo second-order) to determine equilibrium and kinetic parameters. Considering the correlation coefficient and root mean square error, Dubinin-Radushkevich isotherm showed better fit with the equilibrium data for MTBE. However, the performances of Langmuir and Dubinin-Radushkevich models were comparable for ETBE. The adsorption capacities were calculated as 5.50 and 6.92 mg/g for MTBE and ETBE, respectively, at an equilibrium solution concentration of 1 mg/L using Dubinin-Radushkevich isotherm. The differences between the model predictions and experimental data were similar for the pseudo first-order and pseudo second-order kinetic models. Gibbs free-energy changes of adsorption were found to be -22.59 and -28.55 kJ/mol for MTBE-GAC and ETBE-GAC systems, respectively, under the experimental conditions studied.