Browsing by Author "Demirbas, Ayhan"

Now showing 1 - 2 of 2

Evaluation of Eremurus Spectabilis for Production of Bio-Oils With Supercritical Solvents
(Elsevier Science Bv, 2015) Aysu, Tevfik; Demirbas, Ayhan; Bengu, Aydin Sukru; Kucuk, Mehmet Masuk
Eremurus spectabilis samples were liquefied in organic solvents (methanol, ethanol and acetone) with (sodium hydroxide and ferric chloride) and without catalyst in a cylindrical reactor at temperatures of 270, 290 and 310 degrees C under supercritical conditions. The effects of liquefaction parameters such as temperature, catalyst and solvent on product yields were investigated. The liquid products were extracted with diethyl ether and benzene using an extraction procedure. The product yields in supercritical methanol, ethanol and acetone were found to as 41.6%, 53.8% and 64.3% in the non-catalytic runs at 310 degrees C, respectively. The highest conversion was obtained in supercritical acetone in the presence of ferric chloride (10%) at same temperature in the catalytic runs. The produced liquids in acetone were analyzed and characterized by elemental, Fourier transform infrared spectroscopy (FT-IR), gas chromatography-mass spectrometry (GC-MS). The liquid products (bio-oils) obtained with acetone contained various types of components including aromatics, nitrogenated and oxygenated compounds. As the bio-oils obtained exhibit high heat values, E. spectabilis is presented as a potential feedstock candidate for production of bio-fuels or valuable chemicals. (C) 2014 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.
Optimization of Process Variables for Supercritical Liquefaction of Giant Fennel
(Royal Soc Chemistry, 2014) Aysu, Tevfik; Kucuk, Mehmet Masuk; Demirbas, Ayhan
Milled giant fennel (Ferula orientalis L.) stalks were treated in supercritical solvents in the presence of catalyst in a high pressure reactor. Effects of process variables including temperature (from 240 to 320 degrees C), solvent (2-propanol, 2-butanol, and acetone), catalyst (Na2CO3, NaOH, and ZnCl2), particle size (from 0.224 > D-p > 0.150 to 0.850 > D-p > 0.425), solvent/mass ratio (from 50/5 to 50/15) and reaction time (from 45 to 95 min) on product yields were investigated. The amounts of solid, liquid and gas produced, as well as the properties of the resulting bio-oils were determined. Temperature, catalyst and reaction time were major factors affecting the product yields and composition of bio-oils. The highest conversion (liquid + gas products) of 73.48% was achieved in acetone with 10% zinc chloride at 320 degrees C. Acetone as solvent, zinc chloride (10%) as catalyst, 0.224 > D-p > 0.150 as particle size, 50/5 as solvent/mass ratio, and 80 minutes as reaction time provide the optimum conditions for the supercritical liquefaction of Ferula orientalis L. The liquid products (bio-oils) obtained at 300 degrees C were analyzed by gas chromatography-mass spectrometry (GC-MS). The bio-oils which contained a higher amount of carbon and hydrogen than that of the original raw material had higher heating values ranging from 23.66 to 26.17 MJ kg(-1).