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    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, Berrin
    In 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.
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    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, Berrin
    The 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.