Sürdürülebilir Yeşil Kampüs Koleksiyonu / Sustainable Green Campus Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7755
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Article Citation - WoS: 30Citation - Scopus: 31Esterification of Cetyl Alcohol With Palmitic Acid Over Wo3/Zr-sba-15 and Zr-Sba Catalysts(Elsevier Ltd., 2016) Mutlu, Nahide Nuran; Yılmaz, SelahattinTungsten loaded and Zr incorporated SBA-15 catalysts (WO3/Zr-SBA-15 and Zr-SBA-15) were developed for esterification of cetyl alcohol and palmitic acid. The influence of the Zr content, tungsten loading amount, calcination temperature, feed composition and catalyst amount has been studied. Higher tungsten loading decreased the acidity due to formation of WO3 crystals whereas calcination temperature enhanced the acidity by favoring the dispersion of WOx species. Activities of the catalyst changed depending on their amount of Brønsted sites and total number of acid sites. Zr-SBA-15 catalyst which had the highest amount of Brønsted acid sites gave maximum cetyl palmitate yield (63.1%). This catalyst retained its activity up to 3 reuse cycles without significant loss of activity.Article Citation - WoS: 165Citation - Scopus: 174Heterogeneous Fenton-Like Degradation of Rhodamine 6g in Water Using Cufezsm-5 Zeolite Catalyst Prepared by Hydrothermal Synthesis(Elsevier Ltd., 2010) Dükkancı, Meral; Gündüz, G.; Yılmaz, Selahattin; Prihod’ko, R. V.In this study, heterogeneous Fenton-like degradation of reactive azo dye Rhodamine 6G in water was investigated over a CuFeZSM-5 zeolite catalyst prepared by hydrothermal synthesis. At initial pH of 3.4, a color removal of 100% was achieved after a reaction time of 45min. TOC elimination was measured to be 51.8% after 2h of oxidation. Initial decolorization rate was described by an equation of -rA0=4.56×102 e-24.83/RTCR6G,0CH2O2,00.35 where R is in kJ/mol. The leaching of iron and copper cations from zeolite structure into the solution during oxidation was dependent on pH strongly. The regulation of pH from 6.5 (dye solution pH) to 3.4, increased leaching for iron from 0.7 to 0.8mg/dm3 and for copper from 1.4 to 2.1mg/dm3. The copper was totally leached from the catalyst during the process at pH 3.4. © 2010 Elsevier B.V.Article Citation - WoS: 53Citation - Scopus: 60Supercritical Deposition of Pt on Sno2-Coated Al2o3 Foams: Phase Behaviour and Catalytic Performance(Elsevier Ltd., 2008) Garrido, G. Incera; Patcas, F. C.; Upper, G.; Türk, M.; Yılmaz, Selahattin; Kraushaar-Czarnetzki, B.Deposition and reduction of an organometallic platinum complex from a supercritical Pt(COD)Me2/CO2 solution was carried out to produce Pt/SnO2 catalysts supported on Al2O3 foams for CO oxidation at moderate temperatures. The phase behaviour of the complex in supercritical carbon dioxide was investigated to find the optimum pressure and temperature conditions for the deposition. For the Pt(COD)Me2/CO2 mixture, the melting point decreased with increasing pressure from 378 K at 0.1 MPa to 360 K at 25.6 MPa. Additional investigations showed that the solubility of Pt(COD)Me2 in CO2 increases from 5.9 × 10-4 mol/mol at 11.2 MPa and 313 K to 3.4 × 10-3 mol/mol at 29.6 MPa and 353 K. The supercritical deposition yielded catalysts with highly dispersed platinum nanoparticles of approx. 3 nm having a narrow size distribution and thus, a superior activity towards oxidation of carbon monoxide in comparison to a catalyst prepared by the conventional aqueous impregnation of Pt.Article Citation - WoS: 41Citation - Scopus: 43Isomerisation of ?-Pinene Over Beta Zeolites Synthesised by Different Methods(Elsevier Ltd., 2005) Gündüz, Gönül; Dimitrova, Raina D.; Yılmaz, Selahattin; Dimitrov, Ljubomir; Spassova, MayaLiquid-phase α-pinene isomerisation at l00°C in a batch reactor is studied over Beta zeolites synthesised by different methods. It is confirmed that α-pinene forms a carbenium ion in an acidic environment, which rearranges without capture by nucleophiles, to form mainly hydrocarbons as camphene, terpinenes, terpinolenes and heavy products. The microporous Beta samples show low activity despite the high acidity most probably because of the hindered intermediate formation. The nature of the enhanced activity of Beta mesopores samples is suggested to be a result from the high accessibility of the acidic sites. The isomerisation of α-pinene was studied over Beta zeolites synthesised by different methods. The main products are camphene, terpinenes, terpinolenes and heavy products. Beta zeolites with micro-/mesopores reveal excellent activity because of the appropriate balance between acidity and bimodal pore system. The microporous Beta samples show low activity despite the good total acidity most probably because of the steric effect for the formation of the intermediate cations.Article Citation - WoS: 36Citation - Scopus: 40The Kinetics of Citral Hydrogenation Over Pd Supported on Clinoptilolite Rich Natural Zeolite(Elsevier Ltd., 2005) Yılmaz, Selahattin; Uçar, Şule; Artok, Levent; Güleç, HilalThe liquid phase hydrogenation of citral has been investigated over Pd (2.42%) supported on clinoptilolite rich natural zeolite catalyst for different reaction conditions. The zeolite support did not affect the active metal properties. This was attributed to the large size of Pd particles on the support. High selectivity (90%) to citronellal was obtained at complete conversion of citral. The catalytic activity increased with reaction temperature (80, 100, 120°C) following an Arrhenius behaviour, while selectivity remained constant for a given conversion. Selectivity to citronellal increased from 78 to 90% with increase in the amount of catalyst in the reaction solution (Citral/Pd mole ratio 293, 176 and 105). The spent catalyst regained its fresh activity and selectivity upon regeneration.