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Öğe Conversion of Cellulose to 5-HMF in the Presence of Silica-Alumina Catalysts Synthesized by Dual Template at Low Temperature(2023) Hosgun, Halit; Topçu, Özlem; Hosgun, Emir Zafer; Bozan, BerrinIn this study, which incorporates many principles of green chemistry (use of renewable feedstocks, catalysis, improvement of energy efficiency, and harmless solvents and auxiliaries), the single-phase catalytic conversion of cellulose to 5-HMF in over silica-alumina catalysts was investigated. A series of dual-template silica-alumina catalysts with CTAB as the main template and F127 or triethylamine (TEA) as the co-template were synthesized at a low temperature of 60 °C and characterized by XRD, N2 adsorption-desorption technique, FT-IR and pyridine adsorption FT-IR. The surface area is increased by using the second template in silica-alumina catalyst. In addition, the acidity of the surface was changed by using the second template. The cellulose conversion and yield of 5-HMF increased from 36% to 52% and from 3.13% to 4.24%, respectively, due to the properties gained by using the second template. 52% cellulose conversion and 8.13% selectivity of 5-HMF were obtained in aqueous medium, 220 °C and 6 h reaction time with the catalyst using TEA as co-template. Eco-friendly silica catalysts synthesized at low temperatures with a dual template can be considered as a potential alternative for the conversion of cellulose into value-added biobased products.Öğe Direct Conversion of Cellulose into 5-HMF by Transition-Metal Doped Montmorillonite Catalyst in Water(Cambridge Univ Press, 2023) Tunc, Ebru; Hosguen, Emir Zafer; Hosguen, Halit L.; Bozan, BerrinCatalysts are very important in the use of cellulose, the main component of biomass, as a raw material for the large-scale production of liquid fuels and chemicals. 5-Hydroxymethylfurfural (HMF) is an extremely important intermediate in the fine chemical industry. HMF can be synthesized by acid-catalyzed dehydration of fructose, glucose, cellulose, or sucrose. The conversion of cellulose to HMF is challenging due to its chemical structure. The objective of the present study was to devise a more facile synthesis method using transition metal-doped montmorillonite catalysts (10Cr-Mnt, 10Cu-Mnt, 10Fe-Mnt, and 10Zn-Mnt) by wet impregnation. Samples were characterized by X-ray powder diffraction, specific surface area, and NH3-TPD analyses. The synthesized catalysts were used for the conversion of cellulose to 5-HMF in an aqueous medium. Among the metals studied, Cr showed the greatest catalytic activity. With the use of this catalyst, efficient conversion of cellulose to 5-HMF was achieved, affording a conversion yield of 93.47% and 5-HMF yield of 9.07% within 6 h at 200 degrees C. The study described here could be useful for the efficient conversion of cellulose into 5-HMF, as well as into other biomass-derived chemicals.Öğe Hydrothermal liquefaction of olive mill solid waste using transition metal doped montmorillonite catalyst via biorefinery approach(Taylor & Francis Inc, 2025) Ozcan, Burak; Hosgun, Emir Zafer; Hosgun, Halit Levent; Bozan, BerrinThe olive oil industry produces significant waste that contributes to escalating environmental damage. In this study, catalytic hydrothermal liquefaction (HTL) of solid olive mill waste with clays (montmorillonite, kaolin, and bentonite) was carried out at 300 degrees C for 30 min to recover the bio-oil. The yield of the bio-oil without a catalyst was 23.92%. The highest bio-oil yield of 28.56% was obtained with montmorillonite (MMT). Subsequently, various transition metals (chromium, cobalt, zinc, manganese, and nickel) were loaded on MMT by pillaring method and characterized by XRD, XRF, BET, and SEM methods. The yield of bio-oil products increased significantly with the addition of transition metals to MMT catalysts. The Ni/MMT catalyst showed the highest bio-oil yield (38.23%). The elemental analysis shows that the oxygen content of the bio-oil was reduced by the catalysts. The maximum calorific value of the bio-oil (36.13 MJ/kg) was achieved with the MMT catalyst, which was significantly higher than that of the feedstock (19.92 MJ/kg). The energy balance results showed that Ni/MMT had the best positive effect on energy recovery and energy consumption, although the MMT catalyst had the highest HHV. Furthermore, the catalyst significantly affected the composition of hydrocarbons, acids, esters, amides, and heterocyclic compounds in the bio-oil.Öğe Synthesis 5-hydroxymethylfurfural (5-HMF) from fructose over cetyl trimethylammonium bromide-directed mesoporous alumina catalyst: effect of cetyl trimethylammonium bromide amount and calcination temperature(Springer, 2020) Hoşgün, Halit Levent; Türe, Ayşe Gül; Hosgun, E. Zafer; Bozan, BerrinIn this study, mesoporous alumina was synthesized using aluminium isopropoxide as Al precursor and cationic surfactant cetyl trimethylammonium bromide (CTAB) as structure directing agent and it was tested in the dehydration reaction of fructose into 5-HMF. The experiments were carried out in a microwave reactor at 200 degrees C for 5 min. The various ratio of CTAB/Al2O3 and calcination temperature between 400 and 700 degrees C were selected as synthesis parameters. The synthesized samples were analyzed by BET and XRD. The highest surface area was obtained as 602.22 m(2)/g with the weight ratio of CTAB to Al2O3 of 1.00 at the calcination temperature of 400 degrees C. When calcination temperature increased from 400 to 700 degrees C, surface area decreased into 286.14 m(2)/g. N-2 adsorption/desorption isotherms of samples showed characteristic mesoporous type IV according to IUPAC classification. According to XRD patterns, all catalysts were in the amorphous structure. The maximum 5-HMF yield of 51% was achieved with the alumina catalyst calcined at 400 degrees C and CTAB/Al2O3 ratio of 1.0. Although the surface area decreased by rising the calcination temperature from 400 to 550 degrees C, the fructose conversion reached the highest value (97.54%).
