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    Developing Pt based bimetallic and trimetallic carbon supported catalysts for aqueous-phase reforming of biomass-derived compounds
    (Pergamon-Elsevier Science Ltd, 2015) Özsel Kaya, Burçak; Irmak, Sibel; Hasanoglu, Arif; Erbatur, Oktay
    In the present work, a series of Pt-based bimetallic and trimetallic activated carbon (AC) and multiwalled carbon nanotube (MWCNT) supported catalysts at a 10 wt% total metal loading were prepared by wetness impregnation method to evaluate gasification performance of lignocellulosic biomass hydrolyzate and glucose solution for hydrogen-rich gas production by aqueous-phase reforming (APR) process. The Ru, Ni and Sn were added as promoter to platinum based supported catalysts with a 1:1 atomic ratio for bimetalic catalysts and 1:1:1 for trimetallic catalysts. The interactions between metals and the effect of alloy formation on gasification activity of the catalysts were investigated. The catalytic activity of Pt-MWCNT catalyst increased 21.2% by the addition of Ru metal. Bimetallic PtRu-MWCNT catalyst had a significantly higher catalytic activity and hydrogen selectivity compared to monometallic Pt-MWCNT for APR of biomass compounds. Since Ni and Ru metals promoted the activity of platinum catalysts, those catalysts could be used for displacement of platinum catalysts due to their low cost and relatively good catalytic activity in gasification of biomass-derived compounds. Copyright (C) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.
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    Evaluation of various carbon materials supported Pt catalyts for aqueous-phase reforming of lignocellulosic biomass hydrolysate
    (Pergamon-Elsevier Science Ltd, 2014) Özsel Kaya, Burçak; Irmak, Sibel; Hasanoglu, Arif; Erbatur, Oktay
    Currently, under huge pressure from energy demands and environmental problems, much attention is being paid to produce fuel and chemicals from lignocellulosic biomass. In this matter, development of active and also recyclable catalysts are essential. In the present study, various types of carbon supported Pt reforming catalysts were prepared for use in gasification of wheat straw biomass hydrolysate by aqueous-phase reforming. The supports tested were various carbon materials having different surface and structures that were activated carbon (AC), single- and multi-walled carbon nanotubes (SWCNT and MWCNT), superdarco carbon (SDC) and graphene oxide (GO). The catalysts prepared using these supports were evaluated based on gasification yield, carbon amount consumed in the process, sugar alcohols formation and breaking down of organic compounds in the hydrolysate. Compared to other carbon-based supports tested, Pt on activated carbon showed best performance for gasification of biomass hydrolysate. This catalyst was also active on carbon consumption, sugar alcohols production and breaking down soluble organic compounds in the hydrolysate. The second active catalyst, Pt on single-walled carbon nanotube, showed significantly higher activity compared to multi-walled carbon nanotube since large polysaccharides molecules were not able to enter into narrow graphene sheets in multi-walled carbon nanotube to react with Pt deposited inside graphene layers. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.
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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.