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    Hydrogen production from aqueous-phase reforming of sorghum biomass: An application of the response surface methodology
    (Pergamon-Elsevier Science Ltd, 2014) Meryemoglu, Bahar; Hasanoglu, Arif; Özsel Kaya, Burçak; Irmak, Sibel; Erbatur, Oktay
    Aqueous-phase reforming (APR) of sorghum hydrolyzate was performed in a fixed bed reactor applying response surface methodology (RSM) based on the Box-Behnken design (BBD) to produce hydrogen gas. The results showed that RSM based on the BBD was a well-matched method for optimizing of APR of sorghum hydrolyzate. The independent variables such as interactive effects of temperature, feed flow rate, and carbon content of sorghum hydrolyzate on the APR were investigated. The mathematical model and experimental results showed that the operation temperature was the main positive linear effect whereas the interaction between temperature and feed flow rate was the main negative linear effect on the hydrogen yield. The highest hydrogen production was found to be a temperature of 270 degrees C, a hydrolyzate flow rate of 0.30 mL/min, and a carbon content of biomass concentration of 2500 mg/L. The highest H-2/CO2 mole ratio (7.9) obtained at 270 degrees C when carbon content of sorghum hydrolyzate was 1000 mg/L. 2013 Elsevier Ltd. All rights reserved.
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    Improving activity of Pt supported metal catalysts by changing reduction method of Pt precursor for hydrogen production from biomass
    (Pergamon-Elsevier Science Ltd, 2015) Irmak, Sibel; Meryemoglu, Bahar; Özsel Kaya, Burçak; Hasanoglu, Arif; Erbatur, Oktay
    Since Pt is an expensive noble metal, enhancement of activity of Pt-based catalysts is important. In the present study, effects of reduction methods of Pt precursor on activity of supported platinum catalysts were investigated. Activities of the prepared catalysts were evaluated through conversion of biomass compounds to hydrogen-rich gas mixture by aqueous-phase reforming. The results indicated that thermal reduction of Pt precursor (platinum (IV) chloride) under N-2 flow produced more active catalyst compared to H-2 flow for hydrogen-rich gas production by aqueous-phase reforming (APR). Performing reduction process with chemical reduction using NaBH4 reducing agent that followed by thermal treatment significantly improved the catalyst activity. The use of ethylene glycol during impregnation of Pt precursor did not cause an increase in activity. The preparation of nano-sized and uniform Pt deposited catalysts was highly dependent on the type of support used. In this case, AC is the best support compared to alumina and titanium dioxide. Copyright (C) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.
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    Influence of particle size of support on reforming activity and selectivity of activated carbon supported platinum catalyst in APR
    (Elsevier Sci Ltd, 2014) Meryemoglu, Bahar; Irmak, Sibel; Hasanoglu, Arif; Erbatur, Oktay; Özsel Kaya, Burçak
    The aqueous-phase reforming (APR) of biomass-derived compounds has been considered as a promising way to produce hydrogen and developing active reforming catalysts for this process is the challenging issue. The current research was conducted to determine the effect of particle size of support on activity and hydrogen selectivity of activated carbon supported platinum catalyst for APR of glucose, biomass-derived model compound. The commercial activated carbon material was pounded and fractionated based on particle size using 60, 80 and 170 mesh sieves. The activated carbon supported Pt catalysts were prepared by deposition of Pt metals on those fractions by incipient wetness impregnation method. The results showed that although Pt particles deposited on the pounded supports were same size, smaller-sized activated carbon supported Pt catalyst exhibited higher activity and hydrogen selectivity. The performance of the catalyst was better when narrower size distribution of the support particles was used. (C) 2014 Elsevier Ltd. All rights reserved.
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    Utilization of waste cotton linter for preparation of activated carbon to be used as catalyst support in aqueous-phase reforming process
    (Wiley, 2019) Özsel Kaya, Burçak; Niş, Berna; Meryemoglu, Bahar; Hasanoglu, Arif; Irmak, Sibel
    Waste cotton linter was evaluated for production of activated carbons (ACs) that can be used as catalyst support in aqueous-phase reforming (APR) process. Activated carbons were prepared by two different precarbonization methods (thermal and hydrothermal) and two types of chemical activating agents (H3PO4 and KOH). The catalysts prepared by deposition of platinum particles on these carbon materials were evaluated for conversion of glycerol to hydrogen gas by APR. Thermal precarbonization treated LTA and LTB samples had a higher surface area (416.7 and 775.2 m(2)/g) than hydrothermal precarbonized LHA and LHB samples (395.8 and 627.5 m(2)/g) regardless type of the activating agent. In general, KOH was more effective activating agent than H3PO4 in creating porosity in the carbon structures derived from cotton linter. The Pt/LHB catalyst (hydrothermal precarbonization-KOH activation) showed promising catalytic performance with hydrogen selectivity of 76.0% and 99.0% glycerol conversion at same APR conditions. (c) 2018 American Institute of Chemical Engineers Environ Prog, 38: 445-450, 2019