Browsing by Author "Aysu, Tevfik"

Now showing 1 - 20 of 32

Assessment of Avocado Seeds (Persea Americana) To Produce Bio-Oil Through Supercritical Liquefaction
(Wiley, 2015) Aysu, Tevfik; Durak, Halil
Avocado (Persea americana) seeds were liquefied in supercritical ethanol and acetone with (KOH, ZnCl2) and without catalyst at various temperatures (250, 270, and 290 degrees C) in an autoclave under high pressure for production of bio-oil. The effects of liquefaction parameters, such as type of solvent, temperature, and type of catalyst, on the liquefaction yields were studied. Acetone as solvent and zinc chloride as catalyst provide the optimum conditions for liquefaction. The results showed that the highest conversion (liquid+gaseous products) of 76.90 % was obtained in acetone at 290 degrees C with ZnCl2 (10%). The produced bio-oils were analyzed and characterized by the methods including Elemental analysis, Fourier transform infrared spectroscopy (FT-IR) and Gas chromatography-mass spectrometry (GC-MS). One hundred seventy and 195 different compounds were identified by GC-MS in the bio-oils obtained in acetone at 270 and 290 degrees C, respectively. (c) 2015 Society of Chemical Industry and John Wiley & Sons, Ltd
Bio-Oil Production Via Catalytic Pyrolysis of Anchusa Azurea: Effects of Operating Conditions on Product Yields and Chromatographic Characterization
(Elsevier Sci Ltd, 2016) Aysu, Tevfik; Durak, Halil; Guner, Serkan; Bengu, Aydin Sukru; Esim, Nevzat
Pyrolysis of Anchusa azurea, a lignocellulosic gramineous plant, was carried out in a tubular, fixed-bed reactor in the presence of four catalysts (Ca(OH)(2), Na2CO3, ZnCl2, Al2O3). The influences of pyrolysis parameters such as catalyst and temperature on the yields of products were studied. It was found that higher temperature resulted in lower liquid (bio-oil) and solid (bio-char) yields and higher gas yields. Catalysts effected the yields of products differently and the composition of bio-oils. Liquid yields were increased in the presence of Na2CO3, ZnCl2 and Al2O3 and decreased with Ca(OH)(2). The highest bio-oil yield (34.05%) by weight including aqueous phase was produced with Na2CO3 catalyst at 450 degrees C. The yields of products (bio-char, bio-oil and gas) and the compositions of the resulting bio-oils were determined by GC-MS, FT-IR and elemental analysis. GC-MS identified 124 and 164 different compounds in the bio-oils obtained at 350 and 550 degrees C respectively. (C) 2016 Elsevier Ltd. All rights reserved.
Bio-Oil Production Via Catalytic Supercritical Liquefaction of Syrian Mesquite (Prosopis Farcta)
(Elsevier, 2016) Aysu, Tevfik; Durak, Halil
Supercritical liquefaction of Syrian mesquite (Prosopis farcta) stems was performed to produce bio-oil in methanol and acetone without and with (zinc chloride, sodium hydroxide) catalyst at three different temperatures (255, 275 and 295 degrees C) using a high pressure (40 MPa) autoclave reactor for 75 min reaction time. The effects of process parameters including temperature, catalyst and solvent on liquefaction yields were investigated. The optimum conditions for liquefaction were provided with zinc chloride as catalyst and acetone as solvent at 295 degrees C. According to the results, the highest conversion of 77.96% and liquid yield of 49.67% were obtained in acetone at 295 degrees C in the presence of zinc chloride. The produced bio-oils were analyzed and characterized by the methods including elemental analysis (EA), Fourier transform infrared spectroscopy (FT-IR) and gas chromatography mass spectrometry (GC-MS). EA indicated that the most of the raw material's energy was recovered in bio-oils with HHVs between 20 and 34 MJ/kg. GC MS showed the formation of diverse compounds including aliphatics, aromatics, oxygenated and nitrogenated compounds. Acetone bio-oils were enriched in aromatics, ketones and esters while methanol bio-oils contained sugars and carboxylic acids. (C) 2015 Elsevier B.V. All rights reserved.
Biomass Pyrolysis in a Fixed-Bed Reactor: Effects of Pyrolysis Parameters on Product Yields and Characterization of Products
(Pergamon-elsevier Science Ltd, 2014) Aysu, Tevfik; Kucuk, M. Masuk
Slow pyrolysis of eastern giant fennel (Ferula orientalis L.) stalks has been performed in a fixed-bed tubular reactor with (ZnO, Al2O3) and without catalyst at six different temperatures ranging from 350 degrees C to 600 degrees C with heating rates of 15, 30, 50 degrees C/min. The amounts of bio-char, bio-oil and gas produced, as well as the compositions of the resulting bio-oils were determined by FT-IR and GC-MS. The effects of pyrolysis parameters such as temperature, catalyst and ratio of catalyst, particle size (D-P) and sweeping gas flow rate on product yields were investigated. According to results, temperature and catalyst seem to be the main factors effecting the conversion of F. orientalis L. into solid, liquid and gaseous products. The highest liquid yield (45.22%) including water was obtained with 15% zinc oxide catalyst at 500 degrees C temperature at a heating rate of 50 degrees C/min when 0.224 > D-P > 0.150 mm particle size raw material and 100 cm(3)/min of sweeping gas flow rate were used. (C) 2013 Elsevier Ltd. All rights reserved.
Catalytic Effects of Borax and Iron(Iii) Chloride on Supercritical Liquefaction of Anchusa Azurea With Methanol and Isopropanol
(Taylor & Francis inc, 2016) Aysu, Tevfik; Durak, Halil
Anchusa azurea is a lignocellulosic gramineous plant, and it has been selected as a renewable feedstock to be used in a liquefaction process to obtain biofuel. Milled Anchusa azurea stalks were converted to liquid products in methanol and isopropanol with (borax or iron(III) chloride) and without catalyst in an autoclave at temperatures of 260, 280, and 300 degrees C. The liquefaction parameter effects such as catalyst, solvents, and temperature were investigated. The highest percentages of liquid yields from methanol and isopropanol conversions were 64.70% (with borax) and 29.20% (with borax) at 300 degrees C in the catalytic runs, respectively. The highest conversion (73.80%) was obtained in methanol with borax catalyst at the same temperature. The obtained liquid products at 300 degrees C were analyzed and characterized by elemental, Fourier transform infrared spectroscopy and gas chromatography-mass spectrometry (GC-MS). Seventy-three different compounds have been identified by GC-MS in the liquid products obtained in methanol at 300 degrees C.
Catalytic Liquefaction of Spirogyra Gratiana Transeau Alga With Supercritical Solvents
(Taylor & Francis inc, 2017) Turhan, Mehmet; Aysu, Tevfik; Calimli, M. Harbi; Kucuk, M. Masuk
Spirogyra gratiana transeau alga was liquefied in organic solvents with and without catalyst in a cylindrical reactor at temperatures of 493, 513, and 533 K under supercritical conditions. The liquefied compounds were extracted with diethyl ether and benzene using an extraction procedure. The product yields in supercritical methanol, ethanol, and acetone were found to be 15.5, 23.7, and 34.4% at 533 K, respectively. The highest conversion to liquid products was obtained in supercritical ethanol with 10% sodium hydroxide as catalyst at the same temperature in the catalytic runs. Main chemical compounds present in the liquid product obtained in acetone without catalyst at 533 K were analyzed and characterized by gas chromatography-mass spectrometry (GC-MS).
Catalytic Pyrolysis of Alcea Pallida Stems in a Fixed-Bed Reactor for Production of Liquid Bio-Fuels
(Elsevier Sci Ltd, 2015) Aysu, Tevfik
Pyrolysis of Alcea pallida stems was performed in a fixed-bed tubular reactor with and without catalyst at three different temperatures. The effects of pyrolysis parameters including temperature and catalyst on the product yields were investigated. It was found that higher temperature resulted in lower liquid (bio-oil) and solid (bio-char) yields and higher gas yields. Catalysts had different effects on product yields and composition of bio-oils. Liquid yields were increased in the presence of zinc chloride and alumina but decreased with calcium hydroxide, tincal and ulexite. The highest bio-oil yield (39.35%) by weight including aqueous phase was produced with alumina catalyst at 500 degrees C. The yields of bio-char, bio-oil and gas produced, as well as the compositions of the resulting bio-oils were determined by elemental analysis, TGA, FT-IR and GC-MS. 160 different compounds were identified by GC-MS in the bio-oils obtained at 500 degrees C. (C) 2015 Elsevier Ltd. All rights reserved.
Catalytic Pyrolysis of Eremurus Spectabilis for Bio-Oil Production in a Fixed-Bed Reactor: Effects of Pyrolysis Parameters on Product Yields and Character
(Elsevier, 2015) Aysu, Tevfik
Conventional slow pyrolysis of Eremurus spectabilis samples has been performed in a fixed-bed tubular reactor with (tincal, colemanite and ulexite) and without catalyst in the temperature range between 350 and 550 degrees C with heating rates of 10, 30,50 degrees C/min. The yields of bin-char, bio-oil and gas produced, as well as the compositions of the resulting bio-oils were determined by elemental analysis, Fourier transform infrared spectroscopy (FT-IR) and gas chromatography/mass spectrometry (GC-MS). The effects of pyrolysis parameters such as heating rate, temperature, catalyst type, sweeping gas flow rate and particle size (Dp) on product yields were investigated. The results show that temperature and catalyst are the main factors that effect the conversion off. spectabilis into solid, liquid and gaseous products. The highest liquid yield of 38.14% including aqueous phase was achieved with ulexite catalyst at 500 degrees C temperature at a heating rate of 50 degrees C/min when 0224 > Dp > 0.150 mm particle size raw material and 100 mL/min of sweeping gas flow rate were used. Ninety-one and ninety-seven different compounds have been identified by GC-MS in bio-oils obtained at 350 and 550 degrees C respectively. (C) 2014 Elsevier B.V. All rights reserved.
Catalytic Pyrolysis of Liquorice (Glycyrrhiza Glabra L.) in a Fixed-Bed Reactor: Effects of Pyrolysis Parameters on Product Yields and Character
(Elsevier, 2015) Aysu, Tevfik; Durak, Halil
Pyrolysis of liquorice (Glycyrrhiza glabra L.) stalks were performed in a fixed-bed tubular reactor with (ZnO, FeCl3, K2CO3, Al2O3. Na2B4O7 center dot 10H(2)O) and without catalyst at three different temperatures (350, 450,550 degrees C) with a constant heating rate of 40 degrees C/min. The amounts of bio-char, bio-oil and gas produced, as well as the compositions of the resulting bio-oils were determined by GC MS. The effects of pyrolysis parameters on product yields were investigated. The results indicate that both temperature and catalysts effect the conversions of G. glabra L. into solid, liquid and gaseous products. The highest conversion of 74.50% and liquid yield of 34.35% were obtained with Na2B4O7 center dot 10H(2)O catalyst at 550 degrees C temperature when 0.224 > Dp > 0.150mm particle sized samples and 100 mL/min of sweeping gas flow rate were used. Liquid products (bio-oils) obtained at 350 and 550 degrees C were analyzed by elemental analysis and gas chromatography/mass spectrometry (GC MS). 133 and 148 different compounds were identified by GC MS in the bio-oils obtained at 350 and 550 degrees C, respectively. (C) 2014 Elsevier B.V. All rights reserved.
Catalytic Pyrolysis of Tetraselmis and Isochrysis Microalgae by Nickel Ceria Based Catalysts for Hydrocarbon Production
(Pergamon-elsevier Science Ltd, 2016) Aysu, Tevfik; Abd Rahman, Nur Adilah; Sanna, Aimaro
The catalytic pyrolysis of Tetraselmis sp. and Isochrysis sp. was carried out over ceria based catalysts in a fixed bed reactor. There was a clear effect of the catalysts on the product yields and quality, with the catalysts able to recover a large fraction of the starting microalgae energy (67-77%) in the bio-oils. Biooil yield was found to be higher in presence of Ni-Ce/Al2O3 and Ni-C/ZrO2 (26 wt.%). The produced bio-oils had HHVs (higher heating values) of 34-35 MJ/kg and suffered strong deoxygenation, with O level decreased from 40-41% in the starting microalgae to 9-15%. Also, 15-20% N removal was obtained using the ceria based catalysts. The oxygen contents in the bio-oils were remarkably lower than those previously obtained using ZSM-5 (25%) and other species without catalyst (17-24%). H-1 NMR and GC-MS analysis showed that the bio-oils were enriched in aliphatics and depleted in N-compounds and water using the ceria based catalysts. (C) 2016 Elsevier Ltd. All rights reserved.
Ceria on Alumina Support for Catalytic Pyrolysis of Pavlova Sp Microalgae To High-Quality Bio-Oils
(Elsevier Science Bv, 2018) Aysu, Tevfik; Fermoso, Javier; Sanna, Aimaro
In this work, we report for the first time the in-situ catalytic pyrolysis of Pavlova sp. microalgae, which has been performed in a fixed-bed reactor in presence of Ce/Al2O3-based catalysts. The effects of pyrolysis parameters, such as temperature and catalyst were studied on the products yield distribution and bio-oil composition, among others. Results showed that all catalysts increased the bio-oil yield with respect to the non-catalytic runs and reduced the O/C ratio from 0.69 (Pavlova sp.) to 0.1-0.15, which is close to that of crude oil. In terms of bio-oil oxygen content, MgCe/Al2O3 presented the best performance with a reduction of more than 30%, from 14.1 to 9.8 wt%, of the oxygen concentration in comparison with thermal pyrolysis. However, NiCe/Al2O3 gave rise to the highest aliphatics/aromatics fractions. The elemental and gas analysis indicates that N was partially removed from the catalytic bio-oils in the gas phase in forms of NH3 and HCN. (C) 2017 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved.
Ceria Promoted Deoxygenation and Denitrogenation of Thalassiosira Weissflogii and Its Model Compounds by Catalytic In-Situ Pyrolysis
(Elsevier Sci Ltd, 2016) Aysu, Tevfik; Maroto-Valer, M. Mercedes; Sanna, Aimaro
Pyrolysis of microcrystalline cellulose, egg white powder, palm-jojoba oils mixtures Thalassiosira weissflogii model compounds was performed with CeO2 at 500 degrees C, to evaluate its catalytic upgrading mechanism. Light organics, aromatics and aliphatics were originated from carbohydrates, proteins and lipids, respectively. Dehydration and decarboxylation were the main reactions involved in the algae and model compounds deoxygenation, while nitrogen was removed as NH3 and HCN. CeO2 increased decarbonylation reactions compared to in absence of catalyst, with production of ketones. The results showed that the catalysts had a significant effect on the pyrolysis products composition of T. weissflogii. CeO2, NiCeAl2O3 and MgCe/Al2O3 catalysts increased the aliphatics and decreased the oxygen content in bio-oils to 6-7 wt% of the algae starting O-2 content. Ceria catalysts were also able to consistently reduce the N-content in the bio-oil to 20-38% of that in the parent material, with NiCe/Al2O3 being the most effective. (C) 2016 Elsevier Ltd. All rights reserved.
Effect of Process Parameters on Supercritical Liquefaction of Xanthium Strumarium for Bio-Oil Production
(Elsevier, 2016) Genel, Yasar; Durak, Halil; Aysu, Tevfik; Genel, Ilyas
Supercritical liquefaction process is used for producing energy from biomass. The common reaction conditions for supercritical liquefaction process are the 240-380 degrees C temperature range and 5-20 MPa pressure values range. Xanthium strumarium liquefaction experiments were performed in a cylindrical reactor (75 mL) in organic solvents (acetone, ethanol, methanol) under supercritical conditions with (zinc oxide, calcium hydroxide) and without catalyst at the temperatures of 250, 275 and 300 degrees C. The produced liquids at 300 degrees C in liquefaction were analyzed and characterized by Elemental, GC-MS and FT-IR. 36, 37 and 50 different types of compounds were identified by GC-MS obtained in acetone, ethanol and methanol respectively. The liquid product efficiency has been obtained at 300 degrees C in acetone with zinc oxide catalyst (74.80%). The highest HHV value has been calculated as 32.16 MJ/kg with calcium hydroxide catalyst in acetone. (C) 2016 Elsevier B.V. All rights reserved.
Effect of Pyrolysis Temperature and Catalyst on Production of Bio-Oil and Bio-Char From Avocado Seeds
(Springer, 2015) Durak, Halil; Aysu, Tevfik
The slow pyrolysis of avocado seeds (Persea americana) was performed in a fixed-bed tubular reactor with (KOH, Al2O3) and without a catalyst, at three temperatures ranging from 400 to 600 A degrees C, with heating rates of 50 A degrees C/min. The amounts of bio-char, bio-oil and gas produced, as well as the compositions of the resulting bio-oils, were determined by GC-MS and FT-IR. The influences of pyrolysis parameters, such as temperature and catalysts, on product yields were subsequently investigated. Both temperature and catalysts were determined to be the main factors affecting the conversion (liquid+gas products) of avocado seeds into solid, liquid and gaseous products. The highest liquid yield (37.5 %) including water was obtained using 10 % KOH catalyst at 600 A degrees C at a heating rate of 50 A degrees C/min when employing 0.224 > Dp > 0.150 mm particle size raw material and a 100 cm(3)/min sweeping gas flow rate.
Effects of Catalysts and Solvents on Liquefaction of Onopordum Heteracanthum for Production of Bio-Oils
(Elsevier Sci Ltd, 2014) Durak, Halil; Aysu, Tevfik
Milled Onopordum heteracanthum stalks were converted to liquid products in organic solvents (methanol, ethanol and acetone) with (KOH and ZnCl2) and without catalyst in an autoclave at temperatures of 523, 543 and 563 K. Effects of liquefaction parameters such as catalyst and solvent were investigated. The percentage yields from supercritical methanol, ethanol and acetone conversions were 48.2, 50.4 and 66.2 at 563 K in the non-catalytic runs, respectively. In the catalytic run with ZnCl2, the highest conversion (70.2%) was obtained in acetone at the same temperature. The obtained liquid products at 563 K were analyzed and characterized by elemental, Fourier transform infrared spectroscopy, gas chromatography-mass spectrometry. 106 different compounds have been identified by GC-MS in the liquid products obtained in methanol at 563 K. (C) 2014 Elsevier Ltd. All rights reserved.
Effects of Titania Based Catalysts on In-Situ Pyrolysis of Pavlova Microalgae
(Elsevier Science Bv, 2017) Aysu, Tevfik; Ola, Oluwafunmilola; Maroto-Valer, M. Mercedes; Sanna, Aimaro
Pavlova microalga was pyrolysed in presence of titania based catalysts in a fixed bed reactor at various temperatures. The effects of catalysts on Pavlova microalga pyrolysis were investigated. A large fraction of the starting energy (similar to 63-74% daf) was recovered in the bio-oils when the catalysts were used. The bio-oil yield was 20% higher in presence of Ni/TiO2 (22.55 wt%) at 500 degrees C. The High Heating Values of the produced bio-oils were in the range of similar to 35-37 Mykg and suffered strong deoxygenation, with O content (% daf) diminished from 51 wt% to similar to 9-12 wt%. The H-1 Nuclear Magnetic Resounance and Gas Chromatography Mass Spectrometry suggested that the titania catalysts enlarged the aliphatics and aromatic compounds and decreased oxygenates in the bio-oils. Ni/TiO2 had the greatest activity in increasing aliphatic protons (60%) and decreasing coke formation. Its enhanced cracking activity was due to its higher availability on the catalyst surface, compared to Co and Ce, and to strong interaction between Ni and TiO2 support. Despite the fact that the bio-oils were partially de-nitrogenated, the N-content still represent a major limitation for their use as bio-fuels without further upgrading. (C) 2017 Published by Elsevier B.V.
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.
Liquefaction of Giant Fennel (Ferula Orientalis L.) in Supercritical Organic Solvents: Effects of Liquefaction Parameters on Product Yields and Character
(Elsevier, 2013) Aysu, Tevfik; Kucuk, Mehmet Masuk
Ferule orientalis L stalks were liquefied in an autoclave in supercritical organic solvents (methanol, ethanol, 2-propanol, acetone and 2-butanol) with (NaOH, Na2CO3, ZnCl2) and without catalyst at five different temperatures ranging from 240 degrees C to 320 degrees C. The amounts of solid (unconverted raw material), liquid (bio-oil) and gas produced, as well as the composition of the resulting liquid phase, were determined. The effects of various parameters such as temperature, solvent, catalyst and ratio of catalyst on product yields were investigated. The results showed that conversion highly depends on the temperature and catalyst. The highest bio-oil yield (53.97%) was obtained using acetone with 10% zinc chloride at 300 degrees C. The liquid products were extracted with benzene and diethyl ether. Some of selected liquid products (bio-oils) were analyzed by elemental, FT-IR and GC-MS. 126 different compounds were identified by GC-MS in the liquid products obtained in ethanol at 300 degrees C. (C) 2013 Elsevier B.V. All rights reserved.
Liquefaction of Giant Reed (Arundo Donax L.) by Supercritical Fluid Extraction
(Elsevier Sci Ltd, 2013) Aysu, Tevfik; Kucuk, Mehmet Masuk
Air dried and ground Arundo donax L. was subjected to supercritical and catalytic fluid extraction by using organic solvents (methanol, ethanol, acetone and 2-butanol) with (NaOH or Na2CO3) and without catalyst at different temperatures. The liquid products obtained were extracted by liquid-liquid extraction with benzene and diethyl ether. The percentage of yields of liquid products from supercritical extraction by methanol, ethanol, acetone and 2-butanol conversions were 40.3%, 60.7%, 73.58% and 82.1% at 558 K respectively. The highest conversion was obtained in 2-butanol without using catalyst at 558 K. As for the catalytic run, it was with NaOH in ethanol at the same temperature (558 K). Two of selected yields of conversion were analyzed by GC-MS. (C) 2012 Elsevier Ltd. All rights reserved.
Liquefaction of Typha Latifolia by Supercritical Fluid Extraction
(Elsevier Sci Ltd, 2012) Aysu, Tevfik; Turhan, Mehmet; Kucuk, Mehmet Masuk
Milled Typha latifolia stalk mill was converted to liquid products by using organic solvents (methanol, ethanol, acetone and 2-butanol) with catalysts (10% NaOH or Na2CO3) and without catalyst in an autoclave at temperatures of 518, 538 and 558 K. The products were extracted by liquid-liquid extraction (benzene and diethyl ether). The percentage yields from supercritical methanol, ethanol, 2-butanol and acetone conversions were 55.0, 58.5, 62.7 and 70.5 at 538 K, respectively. In the catalytic run with NaOH, the highest conversion was obtained by using ethanol as a solvent at the same temperature. Conversion yields were analyzed by GC-MS. The aim of the present study was to obtain an alternative for petroleum derived fuels or chemical raw materials. (C) 2011 Elsevier Ltd. All rights reserved.