| 1. |
- Kirilin, Alexey V, et al.
(författare)
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Reaction products and transformations of intermediates in the aqueous-phase reforming of sorbitol
- 2010
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Ingår i: ChemSusChem. - Weinheim : WILEY-VCH Verlag GmbH & Co. KGaA. - 1864-564X .- 1864-5631. ; 3:6, s. 708-718
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Tidskriftsartikel (refereegranskat)abstract
- Aqueous phase reforming of sorbitol over Pt supported on an alumina catalyst is investigated, in order to identify the intermediates involved in the transformation of the initial feed. Parameters such as the sorbitol feed rate and temperature are studied. To identify the intermediates, an approach based on analysis of the gas and liquid phases as well as the total carbon content was developed. According to analysis by gas chromatography combined with mass spectrometry of volatile substances collected with solid-phase microextraction, over 260 compounds are involved in the transformation of sorbitol. Of these, 50 of the major products are identified with high reliability. It is shown that a great variety of compounds, bearing different functionalities, form part of the reaction network. The formation of the majority of identified compounds is explained and a reaction network for the formation of sorbitol and intermediate molecules transformation is proposed.
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| 2. |
- Kirilin, Alexey V, et al.
(författare)
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Aqueous phase reforming of xylitol and sorbitol : comparison and influence of substrate structure
- 2012
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Ingår i: Applied Catalysis A. - : Elsevier. - 0926-860X .- 1873-3875. ; 435-436, s. 172-180
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Tidskriftsartikel (refereegranskat)abstract
- The behavior of abundant polyol stemming from hemicelluloses, xylitol, was investigated in the aqueous phase reforming (APR) over supported Pt/Al2O3. The data obtained in the case of xylitol was compared to aqueous phase reforming of sorbitol under the same operating conditions. The effect of weight hour space velocity on the performance of a catalytic system as well as on selectivity towards hydrogen and alkanes was studied. The catalyst showed stable performance with insignificant deactivation over 160 hours time-on-stream. The selectivity towards H2 diminished from 86 to 70% within 120 hours. The regeneration of the catalytic system in a H2 flow allowed to recover the catalyst activity and to improve selectivity towards H2 to 75%. It was found that both polyols demonstrated similar behavior in the APR in the whole range of space velocities studied. The selectivity towards H2 went through a maximum in the case of xylitol and sorbitol when changing a space velocity. This behavior was attributed to a number of side reactions which involved hydrogen thus leading to its consumption. Additionally, the yields of target APR product, hydrogen, were higher in the case of xylitol compared to sorbitol due to the longer carbon chain in the latter substrate. The plausible reaction network based on the hypothesis that APR process proceeds through the terminal position of polyol was proposed to explain similarity in the gas and liquid product composition in the APR of xylitol and sorbitol. The reaction scheme describing formation of the main gas and liquid products via various pathways was proposed and discussed. The results obtained and explanations provided are in perfect coincidence with the results obtained for different substrates in the literature.
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| 3. |
- Kirilin, Alexey V., et al.
(författare)
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Aqueous-phase reforming of xylitol over Pt/C and Pt/TiC-CDC catalysts : catalyst characterization and catalytic performance
- 2014
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Ingår i: Catalysis Science & Technology. - : RSC Publishing. - 2044-4753. ; 4:2, s. 387-401
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Tidskriftsartikel (refereegranskat)abstract
- The aqueous phase reforming (APR) of xylitol was studied over five Pt/C catalysts. The correlation between physico-chemical properties of the catalysts and catalytic performance was established. The Pt/C catalysts have different textural properties as well as different mean Pt cluster sizes and surface acidity. The average Pt cluster size was investigated by means of CO chemisorption as well as by TEM. The reaction was found to be structure sensitive and TOF linearly increases with increasing average Pt cluster size in the studied domain. The catalysts which possess higher surface acidity favoured higher rates of hydrocarbon production. On the contrary the Pt/C materials with lower acidities generated hydrogen with high selectivity and TOF.
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| 4. |
- Kirilin, Alexey V., et al.
(författare)
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Aqueous phase reforming of xylitol over Pt-Re bimetallic catalyst : Effect of the Re addition
- 2014
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Ingår i: Catalysis Today. - : Elsevier. - 0920-5861 .- 1873-4308. ; 223, s. 97-107
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Tidskriftsartikel (refereegranskat)abstract
- The aqueous phase reforming (APR) of xylitol was studied in a continuous fixed bed reactor over three catalysts: Pt/Al2O3, Pt/TiO2 and Pt-Re/TiO2. The data obtained in the case of the monometallic Pt catalysts was compared to the bimetallic Pt-Re sample. The effect of Re addition on the catalyst stability, activity, product formation and selectivity toward hydrogen and alkanes was studied. The bimetallic catalyst demonstrated a higher selectivity to alkanes compared to the monometallic samples. The monometallic catalyst was more selective toward hydrogen formation. A plausible reaction scheme explaining differences in selectivity toward hydrogen and alkanes was proposed and discussed.
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